MIR ournal
Microbiology Independent Research Journal
DOI: 10.18527/2500-2236-2022-9-1-37-55
REVIEW
Antimicrobial peptides and proteins in human biological fluids
Asiya M. Iksanova* , Vera G. Arzumanian , Svetlana Y. Konanykhina , Pavel V. Samoylikov
Mechnikov Research Institute for Vaccines and Sera, 5A, Malyy Kazennyy Pereulok, Moscow, 105064 Russia
ABSTRACT
Antimicrobial peptides and proteins (AMPs) are endogenous compounds that have a direct antimicrobial effect on bacteria (e.g. by disrupting bacterial membranes) as well as on fungi and viruses. AMPs are the main components of the innate immunity of living organisms and are produced by both epithelial cells (skin cells, cells of respiratory tract, intestines, urinary and genital tracts) and cells of the immune system and are secreted into secretory fluids. AMPs can also act as chemoattractants for immunocompetent cells (neutrophils, monocytes, T lymphocytes, dendritic cells) in the inflammation site and affect the antigen presenting cells by modulating adaptive T cell immune responses. The representatives of the main 15 AMP classes, that we describe in this review, are the most studied group of the large pool of these compounds. We discuss their localization, expression, and concentration in various human biofluids under normal and pathological conditions.
Keywords: antimicrobial peptides, hepcidin, histatins, defensins, cathelicidin, dermcidins, adrenomedullin, psoriasin, secretory leukoprotease inhibitor, lysozyme, lipocalin, azurocidin, calprotectin, lactoferrin
#For correspondence: Asiya M. Iksanova, research scientist, Laboratory of fungal and bacterial physiology, Mechnikov Research
Institute for Vaccines and Sera, 5A, Malyy Kazennyy Pereulok, Moscow, 105064 Russia, e-mail: [email protected]
Citation: Iksanova AM, Arzumanian VG, Konanykhina SY, Samoylikov PV. Antimicrobial peptides and proteins in human biological
fluids. MIR J 2022; 9(1), 37-55. doi: 10.18527/2500-2236-2022-9-1-37-55.
Received: August 28, 2021
Accepted: November 14, 2021
Published: June 1, 2022
Copyright: © 2022 Iksanova et al. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License (CC BYNC-SA), which permits unrestricted use, distribution, and reproduction in any medium, as long as the material is not used for commercial purposes, provided that the original author and source are cited. Conflict of interest: The authors have no commercial or financial interests.
Funding: The study was carried out with the support of budgetary funding within the framework of research project no. 0525-2018-0018.
0®@©
INTRODUCTION
Antimicrobial peptides and proteins (AMPs) are an important part of innate immunity. The most studied and most common human AMPs can be divided into 15 classes. AMPs are expressed by cells of various tissues and are present in human biofluids. Their composition and concentration differ depending on the type of biofluid as well as on the state of human health (normal or pathological conditions).
There are many definitions of AMPs in the literature as well as descriptions of various mechanisms of their action and spectrum of activity against various pathogens: bacteria, fungi, protozoa, and some viruses [1]. Despite differences in terminology, it is generally accepted that antimicrobial peptides are polypeptides or oligopeptides containing a different number of amino acids (from 5 to 100); polypeptides, with a large number of amino acids,
are proteins. Usually, AMPs have a cationic charge and act similar against pathogens, the main mechanism of action being the destruction of the microbial membrane. Information on the presence and concentration of different AMPs in the particular biofluid should add to the understanding of their contribution to the protective properties of this biofluid against the pathogenic microorganisms.
The purpose of this review is to systematize the scientific literature data on the presence and concentration of AMPs in the main human biological fluids in healthy individuals as well as in patients with various diseases and pathologies. We describe here AMPs in ascending order of their molecular masses and give a brief description of their main properties. The classification of AMPs that is suggested here is based on both their concentration in biofluids and the type of cells that produce them.
THE MAIN REPRESENTATIVES OF THE AMPs Hepcidin
Fig. 1. Hepcidin-201 (DBAASP v3.0 Database of antimicrobial activity and structure of peptides https://dbaasp.org/home) Amino acid sequence: ICIFCCGCCHRSKCGMCCKT
Hepcidin is a peptide with a molecular mass of 2.8 kDa [2], which serves as an antimicrobial peptide and as an iron regulator, and it acts against bacteria and fungi [3]. It has relatively low antimicrobial activity compared to the other AMPs [4]. Hepcidin is synthesized in the liver and excreted in the urine [3]. In addition, hepcidin can be synthesized by adipocytes [5], macrophages [6], and pancreatic p-cells [7].
Hepcidin is best known as a major iron regulator: it downregulates plasma iron levels ("locks" iron in tissues). Hepcidin binds to ferroportin, which is located on the surface of cells that are iron carriers (macrophages, en-terocytes, hepatocytes), and does not allow iron to leave the cells [3]. Hepcidin is an acute phase protein; its level correlates with the level of C-reactive protein and ferritin [8]. An increase in the level of hepcidin expression is observed in obesity [5]. Vitamin D reduces the level of hepcidin [9], but during an infection, there is an increase in the level of hepcidin in the blood and urine [10].
Macrophages, in addition to immune functions, play the role of an iron depot and regulate the level of hepci-din. They bind to hepatocytes, regulating the release of hepcidin through various proteins, including regulation through transferrin [11]. Tissue hypoxia prevents the expression of hepcidin in hepatocytes, regardless of iron reserves in the body [12].
Hepcidin is found in various biological fluids (Table 1). The concentration of hepcidin in urine is comparable to its level in the blood; in saliva, it is an order of magnitude lower. Hepcidin is normally present in bile and transudates. Its concentration is higher in exudates. According
to some authors, hepcidin is a marker for the separation of transudates and exudates [13]. Hepcidin was not found in vaginal and sweat secretions. The blood level of hepcidin increases in inflammation, myeloma, and chronic kidney diseases [10, 14], while decreasing in iron deficiency anemia and hemochromatosis [14].
Histatins
Fig. 2. Histatin-3 (UniPort Database https://www.uniprot.org/ peptidesearch/)
Amino acid sequence: MKFFVFALILALMLSMTGADSHAKRHHGYK RKFHEKHHSHRGYRSNYLYDN
Histatins form a separate group of AMPs. The most studied three types of histatins are 1, 3, and 5, with molecular masses of 4.9 kDa, 4.0 kDa, and 3.0 kDa, respectively [15]. Of these, histatin-5 is the most active, and histatin-1 is the least active [16]. Histatins usually have a cationic charge due to the peculiarities of the primary structure, which primarily contains basic amino acids [17].
Histatins have a pronounced antifungal activity (anti-candidal activity in particular), which some authors attribute to a high content of the amino acid histidine [17]. Histatins can bind to metal ions, which determines their antimicrobial function [18], but calcium blocks the fungicidal activity of histatin-5 in human saliva [19]. Another function of histatins is wound healing [20, 21]. Histatin is produced by the epithelial cells of the human parotid and submandibular glands [18] as well as in the lacrimal glands [22].
The concentration of histatin in saliva reaches 50,000 ng/ml (Table 1); sometimes it is found in the urine. Histatin-1 is present in the lacrimal fluid, while it is not found in other biological fluids. The concentration of histatin in saliva in human immunodeficiency virus (HIV) patients decreases which leads to an increased susceptibility of these patients to candidiasis [23]. The concentration of histatin in the lacrimal fluid is also reduced in dry eye syndrome [22].
Defensins
Defensins are AMPs with a molecular mass of 2.1- 5.0 kDa [24]. They are small (18-50 amino acids) cationic
Table 1. Concentration of antimicrobial peptides and proteins in the biofluids of healthy individuals.
Serum Urine Saliva Vaginal secretion Sweat Other biofluids References
A B C D E F
1. Hepcidin 1. 1.344-280a 2. 0.38-0,77 3. 0-31.38 4.29-254 (males), 17-268 (females) 2.156-560 0.6-6.2 n/a n/ab 0-14.77 (bile) 0-31.9 (transudate) A [108; 10; 13; 14] B [108] C [13] F [13]
2. Histatins n/a sometimes present 14300-46900 16600-50000 missing n/a absent in nasal secretion, present in lacrimal fluid B [109] C [110; 111] D [112] F [112; 22]
3. Defensins 4.3-7.1 (HBD-1) 0.019-0.053 (HBD-2) 137-249 (HNP-2) 10-100 (HBD-1) 200-1600 (HNP-1) 20-60 (HBD-1) 440-700 (HBD-2) 280-420 (HNP1-3) n/a n/a A [31; 148] B [113] C [32] D [114]
4. Cathelicidin LL-37 594-903 27.2 0.2-5.9 20-65 65-1000 4500 48700-124300 (seminal fluid) A [115; 116] B [38] c [39] D [114] E [117] F [118]
5. Dermcidins 2000-2200 n/a n/a n/a 1000-20000 (face, cervix, breast) 70000 (front) n/a A [45] E [119]
6. Adrenomedul-lin 1.91 0.004160.03644 0.055-0.065 n/a present present in milk, amniotic fluid A [55] B [56] c [50] E [51] F [51]
7. Psoriasin 331 n/a 12700-15300 820-1920 present n/a A [62] C [60] D [120] E [121]
8. Secretory leukoprotease inhibitor 25-43 n/a 500-3500 2.3-1919.9 50-200 600-800 n/a n/a A [122] C [123; 124] D [125; 114]
9. Lysozyme 2000-3600 9600-16800 <300 2200-5900 10900-49000 400-3000 11000-15000 present 290000-300000 (breast milk) >500000 (tears) A [126; 127] B [126] C [128; 129] D [125; 114] E [130] F [131; 132]
10. RNase 0 (RNase 7) 1500-5700 (RNase 3) 188-216.2 (RNase 1) 235-3467.2 (RNase 7) present present present n/a A [74] B [133] C [133] D [134] E [73]
11. Lipocalin 18.9-46.5 168 57-105 2.1-9.6 34.5 194-462 0.561 n/a n/a A [79; 81; 135] B [79; 81] C [135] D [83]
12. Azurocidin 0.4-10.98 4-19 0.041 n/a present 2.4-8.7 (liquor) A [89] B [136] C [90] E [137] F [91]
13. Calprotectin <450 215.8-3770 51 45 3200-40900 2.19 939-4019 290 27000-41000 5000-14000 present 19.9 (coprofiltrate) 25.8 (coprofiltrate) A [138; 139] B [140; 96] C [141; 142; 143; 144] D [114; 125] E [137] F [95; 145]
Continuation of Table 1. Concentration of antimicrobial peptides and proteins in the biofluids of healthy individuals.
Serum Urine Saliva Vaginal secretion Sweat Other biofluids References
A B C D E F
14. Bactericidal/ permeability-increasing protein 4.9-72.1 n/a 77.4-78.9 n/a present n/a A [146] c [147] E [137]
C [147] 400 270 55 8000 245 700-1100 8000 21 8000000 (colostrum), 15000004000000 (milk), 2000000 (tears), 112000 (semen), absent in liquor A [103; 42] B [42] C [103; 42] D [125; 103] E [42] F [103]
E [137] 14 classes 11 classes 14 classes 9 classes 10 classes
a Concentrations are in ng/ml b n/a — no data available
amphiphilic peptides that show activity against bacteria and fungi as well as antiviral activity [25]. Mammalian defensins have beta-sheet structures with three intramolecular disulfide bonds. They can be divided into three main classes according to their structural differences: alpha-defensins, beta-defensins, and theta-defensins [26].
Humans have both alpha-defensins and beta-defen-sins. Our hominin ancestors lost the ability to produce theta-defensins after the orangutan and hominin lineages diverged. Humans have theta-defensin genes, but they contain a stop codon in the sequence responsible for signal peptide synthesis. It is believed that this mutation made humans more susceptible to HIV infection [27].
Defensins act by non-specific binding to anionic phospholipids in bacterial membranes. Cationic charge, amphipathicity, and the ability to oligomerize are
Fig. 3. Human alpha-defensin 5 (HD-5) (DBAASPv3.0 Database of antimicrobial activity and structure of peptides https://dbaasp.org/ home)
Amino acid sequence: ATCYCRTGRCATRESLSGVCEISGRLYRLCCR
considered the key factors that enable their antibacterial activity [28].
Defensins are produced by cells of the immune system and epithelial cells. Alpha-defensins (human neutrophil peptides, HNP) are isolated from azurophilic granules of neutrophils and Paneth cells (small intestine). The main producers of beta-defensins (human beta-defen-sin, HBD) are macrophages, monocytes, dendritic cells, Paneth cells, mucosal epithelial cells, and keratinocytes. The production of beta-defensins by keratinocytes in patients with psoriasis has been observed [26, 29, 30].
Defensins are found in the blood, urine, saliva, and vaginal secretions (Table 1). The concentration of defensins in the blood and urine reaches 100 ng/ml. In saliva and vaginal secretion, their concentration is two orders of magnitude higher. The concentration of defensins in the biological fluids of sick people usually increases. Their concentration in the blood of patients with sepsis reaches 170 pg/ml. High levels of HBD-1 and HBD-2 are found in the blood serum of patients with lung cancer [31] as well as in saliva of patients with diseases of the oral mucosa [32]. The level of alpha-defensins in T lymphocytes is increased in patients with schizophrenia. Therefore, alpha-defensin can be considered as a risk marker for schizophrenia [33].
Cathelicidin
Cathelicidin LL-37 is an AMP with molecular mass of 4.5 kDa that is produced as a precursor hCAP18 (molecular mass 19 kDa) and subsequently converted to LL-37. It is expressed in leukocytes and in various epithelial cells. Approximately 30 cathelicidin genes are known in mammals, while in humans, it is represented by only one gene - CAMP (Cathelicidin Antimicrobial
Peptide) [34]. Cathelicidin is found in different epithelial
Fig. 4. Cathelicidin LL-37 (DBAASPv3.0 Database of antimicrobial activity and structure of peptides https://dbaasp.org/home) Amino acid sequence: LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLV PRTES
tissues - epitheliocytes of the skin, gastrointestinal tract (GIT), ovaries, and lungs as well as in the epithelium of the oral cavity, esophagus, tongue, and genitourinary tract [35].
The predominant source of cathelicidins are secretory granules of neutrophils. Cathelicidin is stored in granules as a precursor - hCAP18, which is released from cells upon activation, and is cleaved by neutrophil elastase to form the active peptide LL-37 [36]. In addition, cathelicidin is found in macrophages and monocytes, in B and T lymphocytes, and in natural killer cells. In macrophages, cathelicidin synthesis is stimulated by vitamin D [37]. Cathelicidin is present in the following biological fluids: in the blood, urine, saliva, vaginal secretions, sweat, and semen (Table 1). The concentration of cathelicidins in semen is several orders of magnitude higher than that in other biofluids. In the course of an infection, its concentration increases in the urine in children with cystitis and pyelonephritis (up to 312.5 ng/ml) [38], in the saliva of patients with some erosive diseases in the oral cavity [39] as well as in patients with bacterial vaginosis [40]. In psoriasis, an increase in the concentration of cathelicidin correlates with an increase in the number of T cells [41].
Dermcidin
Dermcidin, an AMP with a molecular mass of 11.28 kDa (precursor) [42], is present in the body in two variants: DCD-1 and DCD-1L that contains leucine at the C-terminus. Unlike most AMPs dermcidin is an anionic peptide: DCD-1L has a net negative charge. DCD-1L exhibits antimicrobial activity against bacteria and fungi, which is maintained over a broad pH range and at high salt concentrations [43].
Dermcidin is expressed in human eccrine (merocrine) sweat glands and excreted in sweat on the skin surface
Fig. 5. Dermcidin (DBAASPv3.0 Database of antimicrobial activity
and structure of peptide https://dbaasp.org/home)
Amino acid sequence: SSLLEKGLDGAKKAVGGLGKLGKDAVEDLES
VGKGAVHDVKDVLDSVL
[44]. It was detected in blood at concentrations up to 2200 ng/ mL, and in sweat at concentrations up to 70,000 ng/mL, but it was not found in other biofluids (Table 1). A slight increase in the concentration of dermcidin in the blood is observed in melanoma [45], and a certain amount of this AMP is expressed in tissues in breast cancer [46]. A reduced amount of dermcidin in sweat is observed in atopic dermatitis [44].
Adrenomedullin
Adrenomedullin is a peptide with a molecular mass of 6 kDa [47]. It contains a sequence of 52 amino acids and has parts that are structurally similar to calcitonin; therefore, it belongs to the calcitonin family [48]. It is a hormone with a vasodilating effect being more a local rather than a systemic vasodilator [49]. Adrenomedullin is produced in various tissues [50], although it is believed that it is most common in the cardiovascular system. It is a secretory product of the endothelium [51] and it serves as adipokine - an adipose tissue hormone [52]; it is synthesized by monocytes and macrophages [51].
Fig. 6. Adrenomedullin (DBAASPv3.0 Database of antimicrobial activity and structure of peptides https://dbaasp.org/home) Amino acid sequence: YROSMNNFOGLRSFGCRFGTCTVOKLAHOI YOFTDKDKDNVAPRSKISPOGY
Adrenomedullin accumulates in epithelial tissues and various biofluids: blood, sweat, milk, saliva, and amniotic fluid. Adrenomedullin as an AMP acts against grampositive and gram-negative bacteria [51]. The mechanism of the antimicrobial action of adrenomedullin is not known in detail, but there is an assumption that, like most AMPs, it disrupts bacterial membranes [48].
In the blood, its concentration is normally M.91 ng/ml (Table 1). Increased blood levels of adrenomedullin were detected in patients with arterial hypertension and heart failure [53], in the acute phase of myocardial infarction [54], in patients with pancreatic cancer (4.51 ng/ml) and other diseases (sepsis, type 2 diabetes) [55]. In urine and saliva, its concentrations are low; its concentration increases in the urine of patients with pyelonephritis [56] and in the saliva of patients with periodontitis [57].
Psoriasin
Psoriasin is an AMP with a molecular mass of 11.5 kDa [58]. It is produced in the epidermal keratinocytes and sebaceous glands of human skin, but it is not found in ec-crine (merocrine) sweat glands [59]. It was first detected in keratinocytes in psoriasis. It is also found in human fetal tissues. The tissues of the ears, skin, and tongue have the highest content of psoriasin. It is not found in the cells of the immune system, in normal human fibroblasts, lymphocytes, endothelial cells, and transformed epithelial cells of keratinocyte origin in healthy individuals [58]. Psoriasin is a chemoattractant for T cells and is involved in the pathogenesis of acne and psoriasis [60]. It was shown that psoriasin is expressed in bladder carcinoma cells and it was detected in the urine of patients with this disease. Psoriasin expression has also been found in breast cancer. However, it remains unknown whether
Fig. 7. Psoriasin (RCSB PDB (Protein Data Bank) https://www.rcsb. org/pages/about-us/index)
Amino acid sequence: SNTQAERSIIGMIDMFHKYTRRDDKIDKPSLL TMMKENFPNFLSACDKKGTNYLADVFEKKDKNEDKKIDFSEFLSLLG DIATDYHKOSHGAAPCSGGSO
psoriasin could be considered as a tumor marker in clinical diagnostics [61].
Psoriasin is found in the following biological fluids of healthy individuals: blood, saliva, sweat, and vaginal secretions (Table 1). At the same time, the concentration of psoriasin in saliva is higher than in other biofluids. Psoriasin is not specific for psoriasis; it is also activated in other skin diseases that exhibit hyperproliferation and inflammation [61]. In systemic sclerosis, the concentration of psoriasin in saliva increases up to 25,500 ng/mL [60]. In psoriasis, the level of psoriasin in the blood increases, but decreases with the increasing severity of the disease [62]. Psoriasin is a marker of proliferative skin diseases.
Secretory leukocyte protease inhibitor
The secretory leukocyte protease inhibitor (SLPI) has a molecular mass of 12 kDa [63]. It is a potent inhibitor of granulocyte elastase and cathepsin G as well as an inhibitor of pancreatic enzymes such as trypsin, chymotrypsin, and pancreatic elastase [64].
SLPI is produced by various epithelial cells. It protects tissues of the macroorganism from damage by endogenous proteolytic enzymes. The SLPI gene is expressed by cells on many mucosal surfaces located in the tissues of the lungs, cervix, seminal vesicles, and parotid ducts. SLPI is also one of the dominant proteins in epithelial nasal mucosa and nasal secretions [65]. The expression of SLPI in the beta cells of the islets of Langerhans (pancreas) have been demonstrated by means of immunohis-tochemical methods [64].
SLPI has a broad spectrum of antibiotic activity, including bactericidal, antifungal [66], and antiretroviral
Fig. 8. Secretory leukoprotease inhibitor (SLPI) (UniPort Database https://www.uniprot.org/peptidesearch/)
Amino acid sequence: IVGGRRARPHAWPFMVSLOLRGGHFCGATLI APNFVMSAAHCVANVNVRAVRVVLGAHNLSRREPTROVFAVORIFE NGYDPVNLLNDIVILOLNGSATINANVOVAOLPAOGRRLGNGVOCL
amgwgllgrnrgiaSvloelnvtvvtslcrrsnvCtlvrgroaGvc fgdsgsplvcnglihgiasfvrggcasglypdafapvaofvnwTdsiio
activity, which is thought to be the reason for the rare oral transmission of HIV [67].
SLPI is found in the blood, urine, and sweat, and its highest concentration was detected in saliva and vaginal secretions (Table 1). Elevated levels of SLPI in saliva and blood may be an indicator of an HIV infection [68]; in the blood, it is observed in ovarian cancer; in the blood and urine, it is found in acute kidney injury and may be considered as a marker of acute kidney injury [69].
Lysozyme
Lysozyme is an antimicrobial protein that destroys the peptidoglycan of bacterial cell walls. Consequently, its action is more pronounced against gram-positive bacteria. The molecular mass of lysozyme is 14.5 kDa [70].
Lysozyme is produced in the cells of the immune system- phagocytes, including macrophages, neutrophils, and dendritic cells [71]. In addition, lysozyme is found in epitheliocytes: in some parts of the rough endoplasmic reticulum of the epithelial cells of the pyloric glands, in the mucinous granules of the stomach, in the cells of the fundic glands, in the epithelial cells of the Brunner glands (duodenal glands), and in Paneth cells [72].
Lysozyme is found in many biological fluids (Table 1). It is found in abundance in saliva and vaginal secretions, in the blood, and it is also present in sweat and urine. It is found in large quantities in the breast milk (up to 0.3 g/l) and tears (over 0.5 g/l). Its concentration increases in infected patients.
Fig. 9. Lysozyme (RCSB PDB (Protein Data Bank) https://www.rcsb. org/pages/about-us/index)
Amino acid sequence: KVFERCELARTLKRLGMDGYRGISLANWMC LAKWESGYNTRATNYNAGDRSTDYGIFQINSRYWCNDGKTPGAVN ACHLSCSALLODNIADAVACAKRWRDPOGIRAWVAWRNRCONRD VROYVOGCGV
RNases (ribonucleases)
RNases (ribonucleases) perform the function of RNA degradation in the body. In addition, RNases act as antimicrobial agents. Along with intracellular RNases, there are also secreted RNases. One of the RNases - RNase 7 -has a molecular mass of 14.5 kDa [73].
The most well-known is RNase A superfamily, which consists of RNase 1 (pancreatic RNase), RNase 2 - eo-sinophil derived neurotoxin (EDN), RNase 3 - eosinophil cationic protein (ECP), RNase 4, RNase 5 (angiogenin), RNase 6, RNase 7 (skin RNase), and RNase 8 [74].
RNases are secreted by a variety of immune cells, including eosinophils, neutrophils, monocytes, and macrophages [74]. RNase 3 (ECP) is found in the secondary granules of eosinophils [75].
RNases are also secreted by epithelial cells. Pancreatic RNase 1 is expressed in various tissues, including human endothelial cells [76]. RNase 7 was first identified as the most abundant human skin RNase secreted by keratino-cytes [73]. RNase 7 is expressed in the epithelial tissues involved in host defense, for example in the respiratory [77] or urinary tract [78].
RNases are present in many biofluids in healthy individuals: blood, urine, saliva, vaginal secretions, and sweat (Table 1). RNases 1, 3, and 7 are secreted into serum under conditions of tissue injury (major surgery or sepsis). RNase 3 (ECP) is used in a blood test to determine the severity of asthma and other allergic diseases. RNase 7 level is significantly higher in patients with renal dysfunction [74].
Fig. 10. RNase 2 (UniPort Database https://www.uniprot.org/pep-tidesearch/)
Amino acid sequence: MKPPOFTWAOWFETOHINMTSOOCTNAM OVINNYORRCKNONTFLLTTFANVVNVCGNPNMTCPSNKTRKNCH HSGSOVPLIHCNLTTPSPONISNCRYAOTPANMFYIVACDNRDORRD PPOYPWPVHLDRII
Lipocalin
Fig. 11. Lipocalin 2 (RCSB PDB (Protein Data Bank) https://www. rcsb.org/pages/about-us/index)
Amino acid sequence: ODSTSDLIPAPPLSKVPLOONFODNOFHGK
wywglagnrilrddoHpmnmyatiyelkedksynvtsvisshkkc eytiatfvpgsopgefTlgniksygdktsylvrvvstdynoyavvffk
LAEDNAEFFAITIYGRTKELASELKENFIRFSKSLGLPENHIVFPVPID OCIDG
Lipocalin (synonyms: NGAL - neutrophil gelatinase-as-sociated lipocalin, lipocalin 2) is a protein with a molecular mass of 25 kDa [79]. It was first isolated from human neutrophils. Lipocalin enters the plasma from secondary granules of neutrophils, but it has been found that it is synthesized in various organs and tissues. It is expressed and secreted by hepatocytes and the cells of the renal tubules under various pathological conditions [80]. It is also secreted by the cells of the renal tubules after various damaging stimuli [79].
Lipocalin is an acute phase protein, but its concentration does not depend on the number of neutrophils detected in the blood. Lipocalin is a useful early diagnostic biomarker for acute kidney injury [81] and pancreas [82]. Lipocalin prevents iron uptake by microorganisms [83], binds lipophilic substances such as bacterial-derived formyl peptides and lipopolysaccharides, and can act as an inflammation modulator [84].
Lipocalin is present in various biofluids of healthy individuals: blood, urine, and saliva (Table 1). It was found in small quantities in the vaginal secretions. In patients with kidney damage, its blood level increases by 7-16 times and urine level - by 25-1,000 times. The level of lipocalin in urine and bile is also increased in patients with pancreatic cancer and chronic pancreatitis [82].
Azurocidin
Azurocidin (synonyms: cationic antimicrobial protein, CAP37), or heparin-binding protein (HBP) belongs to the
Fig. 12. Azurocidin (UniPort Database https://www.uniprot.org/ peptidesearch/)
Amino acid sequence: IVGGRKARPROFPFLASIONOGRHFCGGALI
harfvmtaascfosonpgvstvvlgaYdlrrrerosrotfsissmse ngydpoonlndLmlloldreanltssvtilplplonatveagtrco
VAGWGSORSGGRLSRFPRFVNVTVTPEDOCRPNNVCTGVLTRRGGI CNGDGGTPLVCEGLAHGVASFSLGPCGRGPDFFTRVALFRDWIDGVL NNPGPGPA
serprocidin family. Serprocidins - elastase, proteinase 3, cathepsin G, azurocidin - are present in the azurophilic granules of neutrophils. Only one of them - azurocidin -does not show proteolytic activity [85]. The molecular mass of azurocidin is 37 kDa [86].
It has a wide spectrum of antimicrobial activity, mainly against gram-negative bacteria. Azurocidin serves as a multifunctional inflammatory mediator due to its action on endothelial cells: it causes an increase in vascular permeability, binds endotoxin, and attracts monocytes to inflammation sites [87].
Azurocidin is found in the blood, urine, saliva, sweat, and cerebrospinal fluid (Table 1). High plasma level of azurocidin is a marker for the development of sepsis with circulatory failure [88]. Low maternal serum level of azurocidin in the first trimester is associated with the premature rupture of the fetal membranes [89]. The level of azurocidin in the saliva of patients with the inflammation of the oral cavity increases by 8.8 times [90]. The presence of elevated levels of this heparin-binding protein in the cerebrospinal fluid serves as a marker for acute bacterial meningitis that helps to distinguish patients with this condition from those patients with other infections of the central nervous system [91].
Calprotectin
Calprotectin (synonym: leukocyte protein L1) is a protein with a molecular mass of 36 kDa [92] that is found in high concentrations in neutrophils, monocytes, and some reactive tissue macrophages. In fact, it comprises approx. 60% of the neutrophilic cytosolic protein fraction [93]. In monocytes, it is expressed on the membrane [94].
Fig. 13. Calprotectin (UniPort Database. https://www.uniprot.org/ peptidesearch/)
Amino acid sequence: MLTELEKALNSIIDVYHKYSLIKGNFHAVYRD DLKKLLETESPOYIRKKGADVWFKELDINTDGAVNFOEFLILVIKMGV AAHKKSHEESHKE
Calprotectin is released upon the activation of neu-trophils or endothelial adhesion of monocytes, and it can be detected in serum or body fluids as a potentially useful clinical marker of inflammation. The soluble form of calprotectin has a bacteriostatic and cytokine-like effect in the local environment [94].
Calprotectin is present in various biological fluids: blood, urine, saliva, vaginal secretions, sweat, and co-profiltrate (Table 1). Its determination in coprofiltrate is of particular importance because calprotectin serves as a marker in the diagnostics of inflammatory bowel disease [95]. In healthy individuals, calprotectin is present in the coprofiltrate at a concentration of 25.8 ng/ml, while in patients with adenoma its concentration reaches 66.3 ng/ml, with intestinal infections -306 ng/ml, and with inflammatory bowel diseases - 797 ng/ml. In the urine of healthy individuals, its content is insignificant, but in patients with acute kidney damage (renal damage), its concentration increases many times, although in patients with prerenal damage to the kidneys, it remains normal. Thus, urinary calprotectin serves as a marker for the differential diagnosis of renal and prerenal kidney damage [96].
Bactericidal/permeability-increasing protein
Bactericidal/permeability-increasing protein (BPI, CAP57), a 55 kDa protein [97] found in the azurophilic granules of mature neutrophils, has a high affinity for lipopolysaccha-rides and exhibits selective cytotoxic, antiendotoxic, and opsonic activity against gram-negative bacteria [98]. The selective activity of BPI against gram-negative bacteria is explained by its high affinity for the lipid A fragment of
Fig. 14. Bactericidal/permeability-increasing protein (BPI, CAP57) (UniPort Database https://www.uniprot.org/peptidesearch/) Amino acid sequence: VNPGVVVRISOKGLDYASOOGTAALOKELK RIKIPDYSDSFKIKHLGKGHYSFYSMDIREFOLPSSOISMVPNVGLKF SISNANIKISGKWKAOKRFLKMSGNFDLSIEGMSISADLKLGSNPTSG KPTITCSSCSSHINSVHVHISKSKVGWLIOLFHKKIESALRNKMNSOV CEKVTNSVSSKLOPYFOTLPVMTKIDSVAGINYGLVAPPATTAETLDV OMKGEFYSENHHNPPPFAPPVMEFPAAHDRMVYLGLSDYFFNTAG
Lvyoeagvlkmtlrddmipkeskfrlttkffgtflpevakkfpnmki
OIHVSASTPPHLSVOPTGLTFYPAVDVOAFAVLPNSALASLFLIGMH TTGSMEVSAESNRLVGELKLDRLLLELKHSNIGPFPVELLODIMNYIV PILVLPRVNEKLOKGFPLPTPARVOLYNVVLOPHONFLLFGADVVYK
bacterial lipopolysaccharide (LPS). BPI recognizes the highly conserved lipid A region of bacterial LPS through residues clustered at the amino-terminal domain of the BPI molecule [99]. BPI may be present in other tissues, including the epithelial lining of mucous membranes [100]. BPI is found in the blood, saliva, and sweat (Table 1). In patients, its concentration in the blood increases tenfold, while in patients with infectious diseases, its concentration reaches 1,000 ng/ml in ascitic fluid [101].
Lactoferrin
Lactoferrin (synonym: lactotransferrin) - an 80 kDa protein [102] - is a glycoprotein capable of binding two ferric ions per molecule [103]. Lactoferrin exhibits an antimicrobial effect by binding iron [104] and shows a direct antimicrobial action, presumably by disrupting the bacterial membrane [105].
Lactoferrin has antimicrobial activity against gram-positive and gram-negative bacteria and fungi. In addition, it has been shown that lactoferrin has an antiviral effect, in particular against HIV [106].
Lactoferrin is localized in the specific granules of neutrophils and is released from the cells at infection and inflammation sites [107]. In addition, lactoferrin is synthesized by exocrine glands [107] and is one of the main proteins of almost all mammalian exocrine secretions.
In healthy individuals, lactoferrin is present in the blood, urine, saliva, vaginal secretions, sweat, seminal
Fig. 15. Lactotransferrin (UniPort Database https://www.uniprot. org/peptidesearch/)
Amino acid sequence: GRRRSVOWCTVSOPEATKCFOWORNMRK
vrgppvscikrdspiocioaiaenRAdavtldggfiyeaglapyklrp vaaevygteroprtHyyavavvkkggsfolneloglkschtglrrt
AGWNVPIGTLRPFLNWTGPPEPIEAAVARFFSASCVPGADKGOFPN LCRLCAGTGENKCAFSSOEPYFSYSGAFKCLRDGAGDVAFIRESTVFE
dlsdeaerdeyellcpdNtrkpvdkfkdchlarvpshavvarsvng
KEDAIWNLLROAOEKFGKDKSPKFOLFGSPSGOKDLLFKDSAIGFSR
vppridsglylGsGyftaionlrkseeevaarrarvvwcavgeoelr kcnowsglsegsvtcssasttedcialvlkgeadamsldggyVyta
GKCGLVPVLAENYKSOOSSDPDPNCVDRPVEGYLAVAVVRRSDTSL TWNSVKGKKSCHTAVDRTAGWNIPMGLLFNOTGSCKFDEYFSOSCA
pgsdprsnlcalcigdeogenkcvpnsneryygytgafrclaeNag-
DVAFVKDVTVLONTDGNNNEAWAKDLKLADFALLCLDGKRKPVTE ARSCHLAMAPNHAVVSRMDKVERLKOVLLHOOAKFGRNGSDCPD-KFCLFOSETKNLLFNDNTECLARLHGKTTYEKYLGPOYVAGITNLK-KCSTSPLLEACEFLRK
fluid, milk, and tears (Table 1), while it is not found in cerebrospinal fluid. The highest concentrations of lacto-ferrin are found in tears and milk. At the same time, its concentration in mature milk is 2-5 times lower than in colostrum.
DISCUSSION
AMPs are present in the different biofluids of healthy individuals in variable concentrations. Despite the fact that different authors have different, sometimes even conflicting, data on AMPs concentrations in biofluids, it is possible to conditionally divide their concentrations into 3 groups: high (over 10,000 ng/ml), medium (100-9,999 ng/ml), and low (0-99 ng/ml).
Saliva and vaginal secretions are the richest in AMPs among the considered biofluids, while urine is the least rich. Almost all the classes of AMPs except dermcidins are present in saliva, with a prevailing concentration of histatin, and high concentrations of psoriasin, lyso-zyme, and calprotectin. Nine of the fifteen considered AMP classes are represented in the vaginal secretion, wherein calprotectin and lysozyme have a high concentration. Dermcidin is present in high concentrations in sweat, while cathelicidin is found there in moderate
concentrations. Blood serum is a biofluid containing all of the classes of AMPs, except histatins. Their concentrations are distributed fairly evenly: most of AMPs are found in blood serum in medium concentrations. Few AMPs are present in the urine, usually at low concentrations, with lysozyme and RNases (particularly RNase 7) reaching moderate concentrations.
Other biofluids with high levels of AMPs include semen (cathelicidin and lactoferrin), milk and tears (lacto-ferrin and lysozyme), and colostrum (lactoferrin).
It is possible to correlate the intensity of AMP synthesis with a certain cell type by comparison of AMP-producing cells, their AMP products, and the amount of these products in healthy individuals. The leaders in the AMP production are glandular epithelial cells of exocrine secretion: the mammary gland (lactoferrin), the lacrimal gland (lysozyme), and the salivary glands (histatin). These cells produce AMPs in high and ultra-high concentrations.
AMPs produced by the cells of the immune system (adrenomedullin, azurocidin, BPI, alpha-defensins) usually are present in the corresponding biofluids in lower concentrations. AMPs, which are produced both by cells of the immune system and by various epithelial cells (ly-sozyme, RNase, cathelicidin, lactoferrin, beta-defensins), have a higher concentration in biofluids if they are produced by the glandular epithelium.
Dermcidins, psoriasin, and a secretory leukoprotease inhibitor are produced by integumentary tissues to protect against pathogens and from their own enzymes.
Some AMPs perform other functions in the body in addition to the antimicrobial action. For example, hep-cidin and lipocalin are acute phase proteins: in the acute phase, hepcidin is secreted into the blood and lipocalin is secreted into the urine. Hepcidin and adrenomedullin are hormones that perform regulatory functions. RNase, being a ribonuclease, performs the functions of RNA degradation.
CONCLUSION
All of the AMPs described here can be conditionally divided into several groups based on the data on the AMPs concentrations in biofluids, their main producing cells, and their functions in the body:
a) Secretory AMPs - produced by glandular epithelium (exocrine glands) and may be present at high and ultra-high concentrations in biofluids.
b) Barrier AMPs - produced by integumentary epithelium, secreted in healthy individuals and in patients with pathological conditions; their function is to provide protection against pathogen penetration (barrier).
Their concentrations in biofluids are usually average, but in case of tissue damage or inflammation, they can be present in biofluids at high and ultra-high concentrations.
c) Leukocyte AMPs - localized in the granules or cytosol of immune cells, associated with the immune response and usually present in biofluids at low or moderate concentrations, corresponding to the number of neutrophils or other immune cells.
d) AMPs with other functions - acute phase proteins, immunomodulators, hormones, and enzymes. These
REFERENCES
1. Fazly Bazzaz BS, Seyedi S, Hoseini Goki N, Khame-neh B. Human Antimicrobial Peptides: Spectrum, Mode of Action and Resistance Mechanisms. Int J Pept Res Ther 2021; 27(1), 801-16. doi: 10.1007/ s10989-020-10127-2.
2. Walker AP, Partridge J, Srai SK, Dooley JS. Hepcidin: what every gastroenterologist should know. Gut 2004; 53(5), 624-7. doi: 10.1136/gut.2003.030304.
3. Park CH, Valore EV, Waring AJ, Ganz T. Hepcidin, a urinary antimicrobial peptide snthesized in the liver. J Biol Chem 2001; 276(11), 7806-10. doi: 10.1074/ jbc.M008922200.
4. Prentice AM. Clinical Implications of New Insights into Hepcidin-Mediated Regulation of Iron Absorption and Metabolism. Ann Nutr Metab 2017; 71(3), 40-8. doi: 10.1159/000480743.
5. Bekri S, Gual P, Anty R, Luciani N, Dahman M, Ra-mesh B et al. Increased adipose tissue expression of hepcidin in severe obesity is independent from diabetes and NASH. Gastroenterology 2006; 131(3), 788-96. doi: 10.1053/j.gastro.2006.07.007.
6. Fatoumata S, Florence W, Satoskar A, Schlesinger L, Zwilling B, Lafuse W. Expression and localization of hepcidin in macrophages: A role in host defense against tuberculosis. J Leukoc Biol 2007; 82(4), 93445. doi: 10.1189/jlb.0407216.
7. Kulaksiz H, Fein E, Redecker P, Stremmel W, Adler G, Cetin Y. Pancreatic ß-cells express hepcidin, an iron-uptake regulatory peptide. J Endocrinol 2008; 197(2), 241-9. doi: 10.1677/J0E-07-0528.
8. Uijterschout L, Swinkels DW, Domellof M, Lager-qvist C, Hudig C, Tjalsma H et al. Serum hepcidin measured by immunochemical and mass-spec-trometric methods and their correlation with iron status indicators in healthy children aged 0.5-3 y. Pediatr Res 2014; 76(4), 409-14. doi: 10.1038/ pr.2014.109.
AMPs usually have a weak antimicrobial effect and perform other functions in addition to antimicrobial action. Their concentrations in biofluids are usually low compared to other AMPs.
Taking into account the fact that the same AMPs can be synthesized by different groups of cells under different conditions, it is reasonable to study such AMPs separately. For example, lysozymes can be subdivided into leukocyte (located in neutrophil granules), secretory (as a part of lacrimal secretion and breast milk), and barrier (on the surface of epithelial tissues).
9. Bacchetta J, Zaritsky JJ, Sea JL, Chun RF, Lisse TS, Zavala K et al. Suppression of iron-regulatory hepcidin by vitamin D. J Am Soc Nephrol 2014; 25(3), 564-72. doi: 10.1681/ASN.2013040355.
10. Nikitin EN, Nikitin YuE, Shklyaev AE, Aleksandro-va OV. Hepcidin in patients with community-acquired pneumonia complicated by anemia. Pulmonologiya 2014; 2, 5-9. (In Russian). doi: 10.18093/0869-01892014-0-2-5-9.
11. Zhao N, Zhang AS, Enns CA. Iron regulation by hepcidin. J Clin Invest 2013; 123(6), 2337-43. doi: 10.1172/ JCI67225.
12. Nicolas G, Chauvet C, Viatte L, Danan JL, Bigard X, Devaux I et al. The gene encoding the iron regulatory peptide hepcidin is regulated by anemia, hypoxia, and inflammation. J Clin Invest 2002; 110(7), 1037-44. doi: 10.1172/JCI15686.
13. Arnold J, Sangwaiya A, Manglam V, Geoghegan F, Thursz M, Busbridge M. Presence of hepcidin-25 in biological fluids: Bile, ascitic and pleural fluids. World J Gastroenterol 2010; 16(17), 2129-33. doi: 10.3748/ wjg.v16.i17.2129.
14. Ganz T, Olbina G, Girelli D, Nemeth E, Westerman M. Immunoassay for human serum hepcidin. Blood 2008; 112(10), 4292-7. doi: 10.1182/blood-2008-02-139915.
15. Oppenheim FG, Xu T, McMillian FM, Levitz SM, Diamond RD, Offner GD, Troxler RF. Histatins, a Novel Family of Histidine-Rich Proteins in Human Parotid Secretion. Isolation, Characterization, Primary Structure, and Fungistatic Effects on Candida Albicans. J Biol Chem 1988; 263(16), 7472-7. PMID: 3286634.
16. Xu T, Levitz SM, Diamond RD, Oppenheim FG. Anti-candidal activity of major human salivary histatins. Infect Immun 1991; 59, 2549-54. doi: 10.1128/ iai.59.8.2549-2554.1991.
17. Woong SJ, Edgerton M. Salivary Histatins: Structure, Function, and Mechanisms of Antifungal Activity.
Candida and Candidiasis, Second Edition. 2012, 18594. doi:10.1128/9781555817176.ch13.
18. Khurshid Z, Najeeb S, Mali M, Moin SF, Raza SO, Zo-haib S et al. Histatin peptides: Pharmacological functions and their applications in dentistry. Saudi Pharmaceutical Journal 2017; 25(1), 25-31. doi: 10.1016/j. jsps.2016.04.027.
19. Dong J, Vylkova S, Li XS, Edgerton M. Calcium blocks fungicidal activity of human salivary histatin 5 through disruption of binding with Candida albicans. J Dent Res 2003; 82(9), 748-52. doi: 10.1177/ 154405910308200917.
20. Kavanagh K, Dowd S. Histatins: antimicrobial pep-tides with therapeutic potential. J Pharm Pharmacol 2004, 56(3), 285-9. doi: 10.1211/0022357022971.
21. Oudhoff MJ, Bolscher JG, Nazmi K, Kalay H, van 't Hof W, Amerongen AV, Veerman EC. Histatins are the major wound-closure stimulating factors in human saliva as identified in a cell culture assay. FASEB Journal 2008; 22(11), 3805-12. doi: 10.1096/fj.08-112003.
22. Kalmodia S, Son KN, Cao D, Lee BS, Surenkhuu B, Shah D et al. Presence of Histatin-1 in Human Tears and Association with Aqueous Deficient Dry Eye Diagnosis: A Preliminary Study. Sci Rep 2019; 9(1), 10304. doi: 10.1038/s41598-019-46623-9.
23. Khan SA, Fidel PL, Jr., Al Thunayyan A, Varlotta S, Meiller TF, Jabra-Rizk MA. Impaired histatin-5 levels and salivary antimicrobial activity against C. albicans in HIV infected individuals. J AIDS Clin Res 2013; 4(193), 1000193. doi: 10.4172/2155-6113.1000193.
24. Jarczak J, Kosciuczuk EM, Lisowski P, Strzalkow-ska N, Jozwik A, Horbanczuk J et al. Defensins: natural component of human innate immunity. Hum Immunol 2013; 74(9), 1069-79. doi: 10.1016/ j.humimm.2013.05.008.
25. Park MS, Kim JI, Lee I, Park S, Bae JY, Park MS. Towards the Application of Human Defensins as Anti-virals. Biomol Ther (Seoul) 2018; 26(3), 242-54. doi: 10.4062/biomolther.2017.172.
26. Schneider JJ, Unholzer A, Schaller M, Schafer-Kort-ing M, Korting HC. Human defensins. J Mol Med 2005; 83(8), 587-95. doi: 10.1007/s00109-005-0657-1.
27. Nguyen TX, Cole AM, Lehrer RI. Evolution of primate theta-defensins: a serpentine path to a sweet tooth. Peptides 2003; 24(11), 1647-54. doi: 10.1016/ j.peptides.2003.07.023.
28. Suresh A, Verma C. Modelling study of dimerization in mammalian defensins. BMC Bioinformatics 2006; 18(7, Suppl 5), S17. doi: 10.1186/1471-2105-7-S5-S17.
29. Budikhina AS, Pinegin BV. Defensins as multifunctional human cationic peptides. Immunopatologia, allergologia i infektologia 2008; 2, 31-40. (In Russian).
30. Tikhomirova E, Slazhneva E, Atrushkevich V. p-de-fensins and the inflammatory periodontal diseases: a systematic review. Parodontologiya 2020; 25(4), 276-86. (In Russian). doi: 10.33925/1683-3759-202025-4-276-286.
31. Arimura Y, Ashitani J, Yanagi S, Tokojima M, Abe K, Mukae H et al. Elevated serum beta-defensins concentrations in patients with lung cancer. Anticancer Res 2004; 24(6), 4051-7. PMID: 15736451.
32. Kucukkolbashi H, Kucukkolbashi S, Dursun R, Ayyil-diz F, Kara H. Determination of defensing HNP-1 in human saliva of patients with oral mucosal diseases. J Immunoassay Immunochem 2011; 32(4), 284-95. doi: 10.1080/15321819.2011.569045.
33. Craddock RM, Huang JT, Jackson E, Harris N, Tor-rey EF, Herberth M et al. Increased alpha defensins as a blood marker for schizophrenia susceptibility. Mol Cell Proteomics 2008; 7(7), 1204-13. doi: 10.1074/ mcp.M700459-MCP200.
34. Gudmundsson GH, Magnusson KP, Chowdhary BP, Johansson M, Andersson L, Boman HG. Structure of the gene for porcine peptide antibiotic PR-39, a cathelin gene family member: comparative mapping of the locus for the human peptide antibiotic FALL-39. Proc Natl Acad Sci USA 1995; 92, 7085-89. doi: 10.1073/ pnas.92.15.7085.
35. Bals R, Wang X, Zasloff M, Wilson JM. The peptide antibiotic LL-37/hCAP-18 is expressed in epithelia of the human lung where it has broad antimicrobial activity at the airway surface. Proc Natl Acad Sci USA 1998; 95, 9541-46. doi: 10.1073/pnas.95.16.9541.
36. Zanetti M, Gennaro R, Romeo D. Cathelicidins: a novel protein family with a common proregion an a variable C-terminal antimicrobial domain. FEBS Lett 1995; 374, 1-5. doi: 10.1016/0014-5793(95)01050-o.
37. Zasloff M. Antimicrobial peptides, innate immunity, and the normally sterile urinary tract. J Am Soc Nephrol 2007; 18, 2810-16. doi: 10.1681/ASN.2007050611.
38. Chromek M, Slamova Z, Bergman P, Kovacs L, Podrac-ka L, Ehren I et al. The antimicrobial peptide cathelici-din protects the urinary tract against invasive bacterial infection. Nat Med 2006; 12, 636-41. doi: 10.1038/ nm1407.
39. Davidopoulou S, Theodoridis H, Nazer K, Kessopou-lou E, Menexes G, Kalfas S. Salivary concentration of the antimicrobial peptide LL-37 in patients with oral lichen planus. J Oral Microbiol 2014; 6, 26156. doi: 10.3402/jom.v6.26156.
40. Frew L, Makieva S, McKinlay AT, McHugh BJ, Doust A, Norman JE et al. Human cathelicidin production by the cervix. PLoS One 2014; 9(8), e103434. doi: 10.1371/journal.pone.0103434.
41. Lande R, Botti E, Jandus C, Dojcinovic D, Fanelli G, Conrad C et al. The antimicrobial peptide LL37 is a T-cell autoantigen in psoriasis. Nat Commun 2014; 5, 5621. doi: 10.1038/ncomms6621.
42. Park JH, Park GT, Cho IH, Sim SM, Yang JM, Lee DY. An antimicrobial protein, lactoferrin exists in the sweat: proteomic analysis of sweat. Exp Dermatol 2011; 20(4), 369-71. doi: 10.1111/j.1600-0625.2010.01218.x.
43. Paulmann M, Arnold T, Linke D, Ozdirekcan S, Kopp A, Gutsmann T et al. Structure-Activity Analysis of the Dermcidin-derived Peptide DCD-1L, an Anionic Antimicrobial Peptide Present in Human Sweat. J Biol Chem 2012; 287(11), 8434-43. doi: 10.1074/jbc. M111.332270.
44. Rieg S, Steffen H, Seeber S, Humeny A, Kalbacher H, Dietz K et al. Deficiency of Dermcidin-Derived Antimicrobial Peptides in Sweat of Patients with Atopic Dermatitis Correlates with an Impaired Innate Defense of Human Skin In Vivo. J Immunol 2005; 174, 8003-10. doi: 10.4049/jimmunol.174.12.8003.
45. Ortega-Martinez I, Gardeazabal J, Erramuzpe A, Sanchez-Diez A, Cortes J, Garcia-Vazquez MD et al. Vitronectin and dermcidin serum levels predict the metastatic progression of AJCC I—II early-stage melanoma. Int J Cancer 2016; 139(7), 1598-607. doi: 10.1002/ijc.30202.
46. Porter D, Weremowicz S, Chin K, Seth P, Keshavi-ah A, Lahti-Domenici J et al. A neural survival factor is a candidate oncogene in breast cancer. Proc Natl Acad Sci USA 2003; 100, 10931-6. doi: 10.1073/ pnas.1932980100.
47. Kitamura K, Kangawa K, Kawamoto M, Ichiki Y, Na-kamura S, Matsuo H et al. Adrenomedullin: a novel hypotensive peptide isolated from human pheochro-mocytoma. Biochem Biophys Res Commun 1993; 192(2), 553-60. doi: 10.1006/bbrc.1993.1451.
48. Hans M, Madaan Hans V. Epithelial antimicrobial peptides: guardian of the oral cavity. Int J Pept 2014; 2014(370297), 1-13. doi:10.1155/2014/370297.
49. He H, Bessho H, Fujisawa Y, Horiuchi K, Tomohiro A, Kita T, Aki Y et al. Effects of a synthetic rat adre-nomedullin on regional hemodynamics in rats. Eur J Pharmacol 1995; 273(3), 209-14. doi: 10.1016/0014-2999(94)00683-x.
50. Kapas S, Pahal K, Cruchley AT, Hagi-Pavli E, Hin-son JP. Expression of adrenomedullin and its receptors in human salivary tissue. J Dent Res 2004; 83(4), 333-7. doi: 10.1177/154405910408300412.
51. Tabassum N, Rasool S. Role of adrenomedullin in human body. Int J Curr Res 2011; 3(2), 108-14. ISSN: 0975-833X.
52. Li Y, Jiang C, Wang X, Zhang Y, Shibahara S, Taka-hashi K. Adrenomedullin is a novel adipokine: adrenomedullin in adipocytes and adipose tissues. Peptides 2007; 28, 1129-43. doi: 10.1016/ j.peptides.2007.03.005.
53. Cheung BM, Li CY, Wong LY. Adrenomedullin: its role in the cardiovascular system. Semin Vasc Med 2004; 4(2), 129-34. doi: 10.1055/s-2004-835370
54. Kitamura K, Ichiki Y, Tanaka M, Kawamoto M, Emu-ra J, Sakakibara S et al. Immunoreactive adrenomedullin in human plasma. FEBS Lett 1994; 341(2-3), 288-90. doi: 10.1016/0014-5793(94)80474-5.
55. D'Angelo F, Letizia C, Antolinno L, La Rocca M, Au-rello P, Ramacciato G. Adrenomedullin in pancreatic carcinoma: A case-control study of 22 patients. In-tegrative Cancer Science and Therapeutics (ICST) 2016; 3(2), 390-2. doi: 10.15761/ICST.1000175.
56. Sharifian M, Esmaeli Zand R, Ahmadi M, Ziaee SA, Mohkam M, Dalirani R et al. Urinary Adrenomedullin Level in Children With Acute Pyelonephritis Before and After Treatment. Iran J Kidney Dis 2013; 7(4), 277-81. PMID: 23880804.
57. Suchetha A, Garg A, Lakshmi P, Bhat D, Sapna N, Apoorva SM. Adrenomedullin, periodontitis, diabetes-unraveling the equivocal relationship. A clinico-biochemical cross-sectional study. Contemp Clin Dent 2013; 4(4), 454-9. doi: 10.4103/0976-237X.123040.
58. Madsen P, Rasmussen HH, Leffers H, Honore B, De-jgaard K, Olsen E et al. Molecular cloning, occurrence, and expression of a novel partially secreted protein "psoriasin" that is highly up-regulated in psoriatic skin. J Invest Dermatol 1991; 97(4), 701-12. doi:10.1111/1523-1747.ep12484041.
59. Glaser R, Harder J, Lange H, Bartels J, Christophers E, Schroder J-M. Antimicrobial psoriasin (S100A7) protects human skin from Escherichia coli infection. Nat Immunol 2005; 6(1), 57-64. doi: 10.1038/ni1142.
60. Giusti L, Sernissi F, Donadio E, Ciregia F, Giacomel-li C, Giannaccini G et al. Salivary psoriasin (S100A7) correlates with diffusion capacity of carbon monoxide in a large cohort of systemic sclerosis patients. J Transl Med 2016; 14, 262. doi: 10.1186/s12967-016-1023-5.
61. Glaser R, Koten B, Wittersheim M, Harder J. Psoriasin: key molecule of the cutaneous barrier? J Dtsch Dermatol Ges 2011; 9(11), 897-902. doi: 10.1111/j.1610-0387.2011.07683.x.
62. Anderson KS, Wong J, Polyak K, Aronzon D, Ener-back C. Detection of psoriasin/S100A7 in the sera of patients with psoriasis. British Journal of Dermatology 2009; 160(2), 325-32. doi: 10.1111/j.1365-2133.2008.08904.x.
63. Abe T, Kobayashi N, Yoshimura K, Trapnell BC, Kim H, Hubbard RC et al. Expression of the secretory leuko-protease inhibitor gene in epithelial cells. J Clin Invest 1991; 87(6), 2207-15. doi: 10.1172/JCI115255.
64. Nystrom M, Bergenfeldt M, Ljungcrantz I, Linde -heim A, Ohlsson K. Production of secretory leucocyte protease inhibitor (SLPI) in human pancreatic beta-cells. Mediators Inflamm 1999; 8(3), 147-51. doi: 10.1080/09629359990478.
65. Kumar R, Vicari M, Gori I, Achtari C, Fiche M, Surbeck I et al. Compartmentalized secretory leukocyte protease inhibitor expression and hormone responses along the reproductive tract of postmenopaus-al women. J Reprod Immunol 2011; 92(1-2), 88-96. doi: 10.1016/j.jri.2011.06.103.
66. Doumas S, Kolokotronis A, Stefanopoulos P. Anti-Inflammatory and Antimicrobial Roles of Secretory Leukocyte Protease Inhibitor. Infect Immun 2005; 73(3), 1271-4. doi: 10.1128/IAI.73.3.1271-1274.2005.
67. McNeely TB, Dealy M, Dripps DJ, Orenstein JM, Eisenberg SP, Wahl SM. Secretory leukocyte protease inhibitor: a human saliva protein exhibiting anti-human immunodeficiency virus 1 activity in vitro. J Clin Invest 1995; 96(1), 456-64. doi: 10.1172/JCI118056.
68. Tsukishiro S, Suzumori N, Nishikawa H, Arakawa A, Suzumori K. Use of serum secretory leukocyte protease inhibitor levels in patients to improve specificity of ovarian cancer diagnosis. Gynecol Oncol 2005; 96(2), 516-9. doi: 10.1016/j.ygyno.2004.10.036.
69. Averdunk L, Fitzner C, Levkovich T, Leaf DE, Sobot-ta M, Vieten J et al. Secretory Leukocyte Protease Inhibitor (SLPI)-A Novel Predictive Biomarker of Acute Kidney Injury after Cardiac Surgery: A Prospective Observational Study. J Clin Med 2019; 8(11), 1931. doi: 10.3390/jcm8111931.
70. Yousif AN, Albright LJ, Evelin TPT. Occurrence of ly-sozyme in the eggs of coho salmon Oncorhynchus kisutch. Dis Aquat Org 1991; 10, 45-9. doi: 10.3354/ dao010045.
71. Lelouard H, Henri S, De Bovis B, Mugnier B, Chol-lat-Namy A, Malissen B et al. Pathogenic bacteria and dead cells are internalized by a unique subset of Peyer's patch dendritic cells that express lysozyme. Gastroenterology 2010; 138(1), 173-84. e1-3 (epub ahead of print). doi: 10.1053/j.gastro.2009.09.051.
72. Saito H, Kasajima T, Masuda A, Imai Y, Ishikawa M. Lysozyme localization in human gastric and duodenal epithelium. An immunocytochemical study. Cell Tissue Res 1988; 251(2), 307-13. doi: 10.1007/ BF00215838.
73. Harder J, Schroder JM. RNase 7, a novel innate immune defense antimicrobial protein of healthy
human skin. J Biol Chem 2002; 277(48), 46779-84. doi: 10.1074/jbc.M207587200.
74. Martin L, Koczera P, Simons N, Zechendorf E, Hoeger J, Marx G et al. The Human Host Defense Ribonucleas-es 1, 3 and 7 Are Elevated in Patients with Sepsis after Major Surgery-A Pilot Study. Int J Mol Sci 2016; 17(3), 294. doi: 10.3390/ijms17030294.
75. Shamri R, Xenakis JJ, Spencer LA. Eosinophils in innate immunity: An evolving story. Cell Tissue Res 2011; 343(1), 57-83. doi: 10.1007/s00441-010-1049-6.
76. Landre JBP, Hewett PW, Olivot J-M, Friedl P, Ko Y, Sachinidis A et al. Human endothelial cells selectively express large amounts of pancreatic-type ribonu-clease (RNase 1). J Cell Biochem 2002; 86(3), 540-52. doi: 10.1002/jcb.10234.
77. Laudien M, Dressel S, Harder J, Glaser R. Differential expression pattern of antimicrobial peptides in nasal mucosa and secretion. Rhinology 2011; 49(1) 107-11. doi: 10.4193/Rhino10.036.
78. Spencer JD, Schwaderer AL, Wang H, Bartz J, Kline J, Eichler T et al. Ribonuclease 7, an antimicrobial peptide upregulated during infection, contributes to mi-crobial defense of the human urinary tract. Kidney Int 2013; 83(4), 615-25. doi: 10.1038/ki.2012.410.
79. Bolignano D, Lacquaniti A, Coppolino G, Campo S, Arena A, Buemi M. Neutrophil gelatinaseassociated lipo-calin reflects the severity of renal impairment in subjects affected by chronic kidney disease. Kidney Blood Press Res 2008; 31(4), 255-8. doi: 10.1159/000143726.
80. Schmidt-Ott KM, Mori K, Li JY, Kalandadze A, Cohen D, Devarajan P et al. Dual Action of Neutrophil Gelatinase-Associated Lipocalin. J Am Soc Nephrol 2007; 18(2), 407-13. doi: 10.1681/ASN.2006080882.
81. Matsa R, Ashley E Sharma V, Walden AP, Keating L. Plasma and urine neutrophil gelatinase-associated lipocalin in the diagnosis of new onset acute kidney injury in critically ill patients. Critical Care 2014; 18(14), R137. doi: 10.1186/cc13958.
82. Hogendorf P, Durczynski A, Skulimowski A , Kumor A, Poznanska G, Strzelczyk J. Neutrophil Gelatinase-As-sociated Lipocalin (NGAL) concentration in urine is superior to CA19-9 and Ca 125 in differentiation of pancreatic mass: Preliminary report. Cancer Biomark 2016; 16(4), 537-43. doi: 10.3233/CBM-160595.
83. Beghini J, Giraldo PC, Linhares IM, Ledger WJ, Wit-kin SS. Neutrophil Gelatinase-Associated Lipocalin Concentration in Vaginal Fluid: Relation to Bacterial Vaginosis and Vulvovaginal Candidiasis. Reprod Sci 2015; 22(8), 964-8. doi: 10.1177/1933719115570914.
84. Cowland JB, Borregaard N. Molecular characterization and pattern of tissue expression of the gene for neutrophil gelatinase-associated lipocalinfrom
humans. Genomics 1997; 45(1), 17-23. doi: 10.1006/ geno.1997.4896.
85. Almeida RP, Melchior M, Campanelli D, Nathan C, Gabay JE. Complementary DNA sequence of human neutrophil azurocidin, an antibiotic with extensive homology to serine proteases. Biochem Biophys Res Commun 1991; 177(2), 688-95. doi: 10.1016/0006-291x(91)91843-2.
86. Soehnlein O, Lindbom L. Neutrophil-derived azuro-cidin alarms the immune system. J Leukoc Biol 2009; 85, 344-51. doi: 10.1189/jlb.0808495.
87. Watorek W. Azurocidin - inactive serine proteinase homolog acting as a multifunctional inflammatory mediator. Acta Biochim Pol 2003; 50(3), 743-52. PMID: 14515154.
88. Linder A, Christensson B, Herwald H, Bjorck L, Akes-son P. Heparin-binding protein: an early marker of circulatory failure in sepsis. Clin Infect Dis 2009, 49(7), 1044-50. doi: 10.1086/605563.
89. Dhaifalah I, Andrys C, Drahosova M, Musilova I, Ada-mik Z, Kacerovsky M. Azurocidin levels in maternal serum in the first trimester can predict preterm prelabor rupture of membranes. J Matern Fetal Neonatal Med 2014; 27(5), 511-5. doi: 10.3109/14767058. 2013.820698.
90. Choi Y-J, Heo S-H, Lee J-M, Cho J-Y. Identification of azurocidin as a potential periodontitis biomarker by a proteomic analysis of gingival crevicular fluid. Pro-teome Sci 2011; 9, 42. doi: 10.1186/1477-5956-9-42.
91. Linder A, Akesson P, Brink M, Studahl M, Bjorck L, Christensson B. Heparin-binding protein: a diagnostic marker of acute bacterial meningitis. Crit Care Med 2011; 39(4), 812-7. doi: 10.1097/CCM. 0b013e318206c396.
92. Johne B, Fagerhol MK, Lyberg T, Prydz H, Brandtzag P, Naess-Andresen CF et al. Functional and clinical aspects of the myelomonocyte protein calprotec-tin. Mol Pathol 1997; 50(3), 113-23. doi: 10.1136/ mp.50.3.113.
93. Brandtzaeg P, Gabrielsen T, Dale I, Muller F, Stein-bakk M, Fagerhol MK. The leucocyte protein L1 (calprotectin): a putative nonspecific defence factor at epithelial surfaces. Adv Exp Med Biol 1995; 371A, 201-6. doi: 10.1007/978-1-4615-1941-6_41.
94. Striz I, Trebichavsky I. Calprotectin - A pleiotropic molecule in acute and chronic inflammation. Physiol Res 2004; 53, 245-53. PMID: 15209531.
95. Aomatsu T, Yoden A, Matsumoto K, Kimura E, In-oue K, Andoh A, Tamai H. Fecal calprotectin is a useful marker for disease activity in pediatric patients with inflammatory bowel disease. Dig Dis Sci 2011; 56(8), 2372-7. doi: 10.1007/s10620-011-1633-y.
96. Heller F, Frischmann S, Grunbaum M, Zidek W, Westhoff TH. Urinary calprotectin and the distinction between prerenal and intrinsic acute kidney injury. Clin J Am Soc Nephrol 2011; 6, 2347-55. doi: 10.2215/ CJN.02490311.
97. Elsbach P, Weiss J. Role of the bactericidal/permeability-increasing protein in host defence. Curr Opin Immunol 1998; 10, 45-9. doi: 10.1016/s0952-7915(98)80030-7.
98. Levy O, Sisson R, Kenyon J, Eichenwald E, Macone AB, Goldmann D. Enhancement of neonatal innate defense: effects of adding an N-terminal recombinant fragment of bactericidal / permeability-increasing protein (rBPI21) on growth and TNF-inducing activity of Gram-negative bacteria tested in neonatal cord blood ex vivo. Infect Immun 2000; 68(9), 5120-5. doi: 10.1128/iai.68.9.5120-5125.2000.
99. Gazzano-Santoro H, Parent JB, Grinna L, Horwitz A, Parsons T, Theofan G et al. High-affinity binding of the bactericidal/permeability- increasing protein and a recombinant aminoterminal fragment to the lipid A region of lipopolysaccharide. Infect Immun 1992; 60, 4754-61. doi: 10.1128/iai.60.11.4754-4761.1992.
100. Canny G, Levy O, Furuta GT, Narravula-Alipati S, Sisson RB, Serhan CN, Colgan SP. Lipid mediator-induced expression of bactericidal/ permeability-increasing protein (BPI) in human mucosal epi-thelia. Proc Natl Acad Sci USA 2002; 99(6), 3902-7. doi: 10.1073/pnas.052533799.
101. Weinrauch Y, Foreman A, Shu C, Zarember K, Levy O, Elsbach P et al. Extracellular accumulation of potently microbicidal bactericidal / permeability-increasing protein and p15s in an evolving sterile rabbit peritoneal inflammatory exudate. J Clin Invest 1995; 95, 1916-24. doi: 10.1172/JCI117873.
102. Anderson B, Baker H, Dodson E. Structure of human lactoferrin at 3.2 angstrom resolution. Proc Natl Acad Sci USA 1987; 84, 1769-73. doi: 10.1073/ pnas.84.7.1769.
103. Berlutti F, Pilloni A, Pietropaoli M, Polimeni A, Val-enti P. Lacroferrin and oral diseases: current status and perspective in periodontitis. Ann Stomatol (Roma) 2011; 2(3-4), 10-8. PMID: 22545184.
104. Jurado RL. Iron, infections, and anemia of inflammation. Clin Infect Dis 1997; 25, 888-95. doi: 10.1086/515549.
105. Chapple DS, Mason DJ, Joannou CL, Odell EW, Gant V, Evans RW. Structure-function relationship of antibacterial synthetic peptides homologous to a helical surface region on human lactoferrin against Escherichia coli serotype O111. Infect Immun 1998; 66(6), 2434-40. doi: 10.1128/IAI.66.6.2434-2440.
106. Harmsen MC, Swart PJ, de Bethune MP, Pauwels R, De Clercq E, The TH et al. Antiviral effects of plasma and milk proteins: lactoferrin shows potent activity against both human immunodeficiency virus and human cytomegalovirus replication in vitro. J Infect Dis 1995; 172(2), 380-8. doi: 10.1093/ infdis/172.2.380.
107. Valenti P, Antonini G. Lactoferrin: an important host defence against microbial and viral attack. Cell Mol Life Sci 2005; 62, 2576-87. doi: 10.1007/s00018-005-5372-0.
108. Wolff F, Deleers M, Melot C, Gulbis B, Cotton F. Hep-cidin-25: Measurement by LC-MS/MS in serum and urine, reference ranges and urinary fractional excretion. Clin Chim Acta 2013; 423, 99-104. doi: 10.1016/j. cca.2013.04.021.
109. Perez V, Lopez D, Boixadera E, Ibernon M, Espina A, Bonet J et al. Comparative differential proteomic analysis of minimal change disease and focal segmental glomerulosclerosis. BMC Nephrol 2017; 18(1), 49. doi: 10.1186/s12882-017-0452-6.
110. Tsai H, Bobek LA. Human salivary histatins; promising anti-fungial therapeutic agents. Crit Rev Oral Biol Med 1998; 9(4), 480-97. doi: 10.1177/ 10454411980090040601.
111. Campese M, Sun X, Bosch JA, Oppenheim FG, Helmer-horst EJ. Concentration and Fate of Histatins and Acidic Proline-rich Proteins in the Oral Environment. Arch Oral Biol 2009; 54(4), 345-53. doi: 10.1016/ j.archoralbio.2008.11.010.
112. Sakurada K, Akutsu T, Watanabe K, Fujinami Y, Yoshino M. Expression of statherin mRNA and protein in nasal and vaginal secretions. Leg Med 2011; 13(6), 309-13. doi: 10.1016/j.legalmed.2011.07.002.
113. Valore EV, Park CH, Ouayle AJ, Wiles KR, McCray PB Jr., Ganz T. Human beta-Defensin-1: An Antimicrobial Peptide of Urogenital Tissues. J Clin Invest 1998; 101(8), 1633-42. doi: 10.1172/JCI1861.
114. Valore EV, Park CH, Igreti SL, Ganz T. Antimicrobial components of vaginal fluid. J Obstet Gynecol 2002; 187(3), 561-8. doi: 10.1172/JCI1861.
115. Bhan I, Camargo CA Jr., Wenger J, Ricciardi C, Ye J, Borregaard N, Thadhani R. Circulating levels of 25-hydroxyvitamin D and human cathelicidin in healthy adults. J Allergy Clin Immunol 2011; 127(5), 1302-04. doi: 10.1016/j.jaci.2010.12.1097.
116. Jeng L, Yamshchikov AV, Judd SE, Blumberg HM, Martin GS, Ziegler TR et al. Alterations in vitamin D status and anti-microbial peptide levels in patients in the intensive care unit with sepsis. J Transl Med 2009; 7, 28. doi: 10.1186/1479-5876-7-28.
117. Murakami M, Ohtake T, Dorschner RA, Gallo RL, Schittek B, Garbe C. Cathelicidin Anti-Microbial Pep-tide Expression in Sweat, an Innate Defense System for the Skin. J Invest Dermatol 2002; 119(5), 1090-95. doi: 10.1046/j.1523-1747.2002.19507.x.
118. Malm J, Sorensen O, Persson T, Frohm-Nilsson M, Johansson B, Bjartell A et al. The human cationic antimicrobial protein (hCAP-18) is expressed in the epithelium of human epididymis, is present in seminal plasma at high concentrations, and is attached to spermatozoa. Infect Immun 2002; 68(7), 4297-302. doi: 10.1128/IAI.68.7.4297-4302.2000.
119. Schittek B. The Multiple Facets of Dermcidin in Cell Survival and Host Defense. J Innate Immun 2012; 4(4), 349-60. doi: 10.1159/000336844.
120. Mildner M, Stichenwirth M, Abtin A, Eckhart L, Sam C, Glaser R et al. Psoriasin (S100A7) is a major Escherichia coli-cidal factor of the female genital tract. Mucosal Immunol 2010; 3(6), 602-9. doi: 10.1038/ mi.2010.37.
121. Glaser R, Meyer-Hoffert U, Harder J, Cordes J, Wittersheim M, Kobliakova J et al. The Antimicrobial Protein Psoriasin (S100A7) Is Upregulated in Atopic Dermatitis and after Experimental Skin Barrier Disruption. J Invest Dermatol 2009; 129(3), 641-9. doi: 10.1038/jid.2008.268.
122. Tsukishiro S, Suzumori N, Nishikawa H, Arakawa A, Suzumori K. Use of serum secretory leukocyte protease inhibitor levels in patients to improve specificity of ovarian cancer diagnosis. Gynecol Oncol 2005; 96(2), 516-9. doi: 10.1016/j.ygyno.2004.10.036.
123. Wahl SM, McNeely TB, Janoff EN, Shugars D, Wor-ley P, Tucker C et al. Secretory leukocyte protease inhibitor (SLPI) in mucosal fluids inhibits HIV-I. Oral Dis 1997; 3(Suppl. 1), S64-S69. doi: 10.1111/j.1601-0825.1997.tb00377.x.
124. Rahman S, Campbell CMP, Torres BN, O'Keefe MT, Ingles DJ, Villa LL et al. Distribution and factors associated with salivary secretory leukocyte protease inhibitor (SLPI) concentrations. Oral Dis 2016; 22(8), 781-90. doi: 10.1111/odi.12550.
125. Valore EV, Wiley DJ, Ganz T. Reversible deficiency of antimicrobial polypeptides in bacterial vaginosis. Infect Immun 2006; 74(10), 5693-702. doi: 10.1128/ IAI.00524-06.
126. Johansson BG, Malmquist J. Quantitative immunochemical determination of lysoqyme (murami-dase) in serum and urine. Scand J Clin Lab Invest 1971; 27(3), 255-61. doi: 10.3109/00365517109080216.
127. Sahin O, Ziaei A, Karaismailoglu E, Taheri N. The serum angiotensin converting enzyme and lyso-zyme levels in patients with ocular involvement of
autoimmune and infectious diseases. BMC Ophthal-mol 2016; 16, 19. doi: 10.1186/s12886-016-0194-4.
128. Jenzano JW, Hogan SL, Lundblad RL. Factors Influencing Measurement of Human Salivary Lysozyme in Lysoplate and Turbidimetric Assays. J clin micro-biol 1986; 24(6), 963-7. PMID: 3782460.
129. Kmiliauskisa MA, Palmeiraa P, Arslaniana C, Pon-tesa GN, Costa-Carvalhob BT, Jacobc CM, Carnei-ro-Sampaioa MMS. Salivary lysozyme levels in patients with primary immunodeficiencies. Aller-gologia et Immunopathologia 2005; 33(2), 65-8. doi: 10.1157/13072915.
130. Papini M, Simonetti S, Franceschini S, Binazzi M. Serum and skin lysozyme activity in several skin disorders. Arch Dermatol Res 1983; 275(1), 67-8. doi: 10.1007/BF00516559.
131. Karimova SF, Yuldashev NM, Ismailova GO, Nishan-taev MK. Biochemistry of milk. Advances in current natural sciences 2015; 9(3), 422-8. URL: https://nat-ural-sciences.ru/en/article/view?id=35604 (access date: 05/30/2022).
132. Sen DK, Sarin GS. Biological variations of lysozyme concentration in the tear fluids of healthy persons. Br J Ophthalmol 1986; 70(4), 246-8. doi: 10.1136/ bjo.70.4.246.
133. Spencer JD, Schwaderer AL, Dirosario JD, McHugh KM, McGillivary G, Justice SS et al. Ribonu-clease 7 is a potent antimicrobial peptide within the human urinary tract. Kidney Int 2011; 80(2), 174-80. doi: 10.1038/ki.2011.109.
134. Koczera P, Martin L, Marx G, Schuerholz1 T. The Ribonuclease A Superfamily in Humans: Canonical RNases as the Buttress of Innate Immunity. Int J Mol Sci 2016; 17(8), 1278. doi: 10.3390/ijms17081278.
135. Tamimi A, Kord E, Rappaport YH, Cooper A, Abu Hamad R, Efrati S et al. Salivary Neutrophil Gelati-nase-Associated Lipocalin Sampling Feasibility in Acute Renal Colic. J Endourol 2018; 32(6), 566-71. doi: 10.1089/end.2017.0864.
136. Kjolvmark C, Pahlman LI, Akesson P, Linder A. Hep-arin-binding protein: a diagnostic biomarker of urinary tract infection in adults. Open Forum Infectious Diseases 2014; 1(1), ofu004. doi: 10.1093/ofid/ ofu004.
137. Burian M, Velic A, Matic K, Gunther S, Kraft B, Gon-ser L et al. Quantitative Proteomics of the Human Skin Secretome Reveal a Reduction in Immune Defense Mediators in Ectodermal Dysplasia Patients. J Invest Dermatol 2015; 135(3), 759-67. doi: 10.1038/ jid.2014.462.
138. Nanees A, Marcel W, Al Swaff R, Sherin H. Serum calprotectin level for diagnosis and detection of disease activity in rheumatoid arthritis. International Journal of Immunology 2014; 2(1), 6-10. doi: 10.11648/j. iji.20140201.12.
139. Meuwis MA, Vernier-Massouille G, Grimaud JC, Bouhnik Y, Laharie D, Piver E et al. Serum calprotectin as a biomarker for Crohn's. J Crohns Colitis 2013; 7(12), e678-83. doi: 10.1016/j.crohns.2013.06.008.
140. Ebbing J, Mathia S, Seibert FS, Pagonas N, Bauer F, Erber B et al. Urinary calprotectin: a new diagnostic marker in urothelial carcinoma of the bladder. J Urol 2014; 32(6), 1485-92. doi: 10.1007/s00345-013-1227-8.
141. Jonsson R, Cuida M, Brun J, Tynning TR. Calpro-tectin levels in oral fluids: the importance of collection. Wiley Online Libruary 1995; 103(1), 8-10. doi: 10.1111/j.1600-0722.1995.tb00003.x.
142. Panov VE, Krasteva A, Krasteva AZ, Ivanova A, Pan-ov A, Krastev Z. Azithromycin decrease saliva calprotectin in patients with periodontal diseases. J of IMAB 2014; 20(1), 464-8. doi: 10.5272/jimab.2014201.464.
143. Zhou M, Meng HX, Zhao YB, Chen ZB. Changes of Four Proinflammatory Proteins in Whole Saliva during Experimental Gingivitis. Chin J Dent Res 2012; 15(2), 121-7. PMID: 23509833.
144. Sweet SP, Denbury AN, Challacombe SJ. Salivary cal-protectin levels are raised in patients with oral can-didiasis or Sjögren's syndrome but decreased by HIV infection. Oral Microbiol Immunol 2001; 16(2), 11923. doi: 10.1034/j.1399-302x.2001.016002119.x.
145. Damms A, Bischoff SC. Validation and clinical significance of a new calprotectin rapid test for the diagnosis of gastrointestinal diseases. Int J Colorectal Dis 2008; 23(10), 985-92. doi: 10.1007/s00384-008-0506-0.
146. White ML, Ma JK, Birr CA, Trown PW, Carroll SF. Measurement of bactericidal/permeability-increasing protein in human body fluids by sandwich ELISA. J Immunol Methods 1994; 167(1-2), 227-35. doi: 10.1016/0022-1759(94)90091-4.
147. Bartunkova J, Sediva A, Skalicka A, Tomasova H, Bar-tosova J, Vavrova V. The levels of bactericidal/permeability increasing protein (BPI) in body fluids. J Allergy Clin Immunol 2004; 113(2), 132. doi: 10.1016/j. jaci.2003.12.468.
148. van den Broek I, Sparidans RW, Engwegen JY, Cats A, Depla AC, Schellens JH, Beijnen JH. Evaluation of human neutrophil peptide-1, -2 and -3 as serum markers for colorectal cancer. Cancer Biomark 2010; 7(2), 109-15. doi: 10.3233/CBM-2010-0153.