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Section 7. Medical science
Matyakubova Salomat Aleksandrovna, Senior Researcher of Department of Obstetrics and Gynaecology of Tashkent Medical Academy, Uzbekistan E-mail: mbshakur@mail.ru
Some pathogenesis aspects hypertension induced by pregnancy
Abstract: The study included 139 pregnant women aged between 17 and 27 years (21.3±4.22 years). HIP was diagnosed in 119 women after 20 weeks of pregnancy. 20 patients (control group) were with physiological course of pregnancy. Results of the study showed that in pregnant women at risk of hypertensive disorders, especially after 20-22 weeks of gestation and later, lymphocytes ability to platelets adhesion is rose, the concentrations of proinflammatory cytokines and NO level are increased. The direct relationship between DBP high level with degree of LPA, CECs, NO, IL-Ip and TNF-a cytokines at gestation period of 20-22 weeks indicates their importance in the pathogenesis of hypertensive disorders in pregnant women.
Keywords: hypertension induced by pregnancy, lymphocyte-platelet adhesion, interleukins, transforming necrosis factor — a, endothelial dysfunction.
Introduction. The problem of hypertensive disorders is extremely urgent in clinical and social terms, for leads to high reproductive losses. Hypertensive disorders, occupying a leading position in the structure of the pathology of pregnancy, has a significant influence on the course and outcome of pregnancy and is a major cause of perinatal mortality and maternal mortality [4; 9]. Functional systems, structures of cell membranes, activity of the haemostasis system, as well as the endothelial state and its secretory function play the special role in this process [1; 8]. The realization of defence mechanisms because of damaged blood vessels at the level of the whole organism is accompanied by increased activity of platelet adhesion to lymphocytes, which was called the phenomenon of lymphocyte-platelet adhesion [6; 18]. The LPA phenomenon plays the important role in the development of protective and reparative processes [6]. Platelets were established to promote migration oflymphocytes and their fixation on the surface ofdamaged vascular wall that allows them to withstand the shear force of blood flow [3]. Platelets release a number of anti-inflammatory and growth factors. Damage of the vascular endothelium by aggression factors and hypoxia hampers expression of most of the known adhesion molecules [2]. As a result, cell migration and cooperation in certain areas of fixation of the vascular wall are disrupted. In this regard, platelet functions are enhanced. Platelets provide contact of lymphocytes and collagen fibers, partly compensate missing antigen-preventing function, helps to promote lymphocytes deeper the damaged part of the vascular system [10]. Because of disturbance of the processes of lymphocyte contact with collagen fibers, the reaction of stabilization in the lesions is decreased, vascular permeability is increased, haemostasis on the lesion site is developed, the system of immune response is initiated, as well as the conditions for angiogenesis and tissue proliferation are appeared. Changes in the state of vascular endothelium, platelet adhesion to lymphocytes and features of mechanisms in the systemic circulation of mother are poor studied.
Objective: To determine the significance of lymphocyte-platelet adhesion (LPA), pro-inflammatory cytokines and en-
dothelial dysfunction in the development of hypertension induced by pregnancy (HIP).
Material and Methods. The study included 139 pregnant women aged between 17 and 27 years (21.3±4.22 years). HIP was diagnosed in 119 women after 20 weeks of pregnancy. 20 patients (control group) were with physiological course of pregnancy. Exclusion criteria for the study were: (1) chronic hypertension, (2) somatic diseases (coronary heart disease, hypertension, diabetes, renal and hepatic pathologies). The distribution of patients by groups was carried out according to the level ofblood pressure (BP) in accordance with ICD-10 (Geneva, WHO, 2002). The 1st group consisted of 39 women, whose systolic BP (SBP) increased up to 140 mm Hg and diastolic BP (DBP) rose to 90 mm Hg after 20 weeks of pregnancy. The 2nd group included 47 women with SBP over 140 to 160 mm Hg and DBP greater than 90 to 100 mm Hg. In the 3rd group were 33 patients with SBP more than 160 mm Hg and DBP greater than 100 mm Hg. In women of control group at this time of observation SBP was mean 105.8±3.26 mm Hg and DBP was mean 68.7±2.84 mm Hg.
The survey was conducted at the moment of detection pregnancy from 7 to 10 weeks and in dynamics of I, II and III trimesters of gestation. HIP was verified at absence of distinct clinical symptoms that characteristic for arterial hypertension, and negative kidney samples: protein content in urine less than 0.002 g/l, glomerular filtration rate — 155.8 ml/min, the normal levels of creatinine and urea. In the dynamics of gestation, the number of desquamated endothelial cells circulating in the systemic circulation (CECs) was counted by Alad-ovec J. (1978) method in the modification by Petrishev N. N. and Vlasov T. D. [7]. Nitrates levels were determined by Metelskaya V A. and Gumanova M. G. method [5]. The adhesion of platelets was assessed by their ability to form co-aggregates with lymphocytes as described by Vitkovskiy Y. A. et al. [11] by determining the percentage of lymphocytes aggregates with thrombocytes (lymphocyte-platelet plugs). The concentrations of IL-Ip and TNF-a were measured by immunoen-zymatic method ELISA on computerized immunoenzymatic
Some pathogenesis aspects hypertension induced by pregnancy
analyzer (IEA-AT-858 LTD, China) with reagents of "Vector-Best" company (Novosibirsk, Russia).
Statistical and regression analysis was performed using Statistica 6.0 for Windows. Student's t-test and Pearson's correlation coefficient (r) was assessed. Significant differences were considered at P<0.05.
Results and Discussion. We have found that pregnant women with HIP that developed in terms of 7-10 weeks of gestation had no damage of the endothelial cells and increase in their number in blood, in comparison with control. Along with this, in 5 (10.8%) patients of the 2nd group and in 8 (24.2%) patients of the 3rd group, the number of CECs exceeded the average levels. With increasing gestational age to 22 weeks the number of CECs in women of the 1st, 2nd and 3rd groups increased, respectively, in 1.5, 1.9 and 2.2 times (P<0.01 and P<0.001), reaching a maximum at term of more than 22 weeks. Thus, the number of desquamated CECs was over the control values in 1.6, 2.0 and 2.6 times, respectively.
Increase in the number of CECs circulating in blood is a highly specific marker of endothelial dysfunction (ED) [14]. NO expression due to initiation of inducible form of NO-synthase (iNOS) in response to depression of activity of the basal level of endothelial NO-synthase (eNOS) can contribute to vascular wall damage [8; 9]. At the same time, at 7-10 weeks of gestation, in pregnant women of main group NO level in the systemic circulation was within the upper limit of control. In 5 (10.6%) and 8 (24.2%) patients of the 2nd and 3rd groups, respectively, were found elevated CECs and NO levels. After 20-22 weeks of gestation, changes in NO-system were exacerbated: in the 1st group these indices were 1.2-fold (P<0.05) and 1.3-fold (P<0.01) higher control levels; in the 2nd group — 1.3-fold (P<0.01) and 1.4-fold (P<0.001); in the 3rd group — 1.7-fold and 1.9-fold (P<0.001), respectively. Evidently, increase of NO level with increasing of gestational age in pregnant women with HIP is due to peculiarities of restructuring of the membrane structures of endothelial cells as a consequence of exposure of environmental factors [22; 25]. This influences on the repair processes in the vascular endothelium of pregnant women with predisposition to HIP. Since NO is involved in the implementation of various pathophysiological processes, including cell cooperation, NO expression in pregnant women prone to HIP can enhance the aggregation of blood cells. It was established that NO expression stimulates formation of tissue factor of activation of coagulation haemostasis [1; 9; 16]. NO overexpression has the ability to support vasospasm in microcirculation of the body of pregnant women for a long time [25]. As a result, tissue hypoxia is exacerbated; area of possible development of DE at the system and polyorgan levels is expanded [12]. Deceleration of blood flow in organs and tissues against vasospasm and thrombosis reduces potential of shift that, subsequently, reduces eNOS activity and initiates iNOS activity and NO formation [17].
There was found a strong direct relationship between the amount of CECs and NO level in blood of pregnant wom-
en of main group (r=0.77; P<0.01). Hence, damage of the endothelium leads to NO increase, inducing, thereby, processes of endothelial damage and increasing CECs in blood stream. It was believed that pro-inflammatory cytokines that stimulate iNOS formation in neutrophils, macrophages, endothelial cells and vascular smooth muscle cells contribute to this process [11]. We confirm this fact in our research, which has found increase of NO and CECs levels in the circulating blood. At the same time, in patients of the 1st, 2nd and 3rd groups in terms of 7-10 weeks of gestation these indices were within the control values. After 20-22 weeks, IL-I^ and TNF-a contents in the 1st group were higher in 1.4 and 1.5 times (P<0.01), in the 2nd group — in 1.8 and 1.7 times (P<0.001), in the 3rd group — in 2.0 and 1.9 times (P<0.001), respectively, in comparison with control. Activation of macrophages, which are capable to produce active pro-inflammatory cytokines, has an important place in the initiation of IL-I^ and TNF-a [20]. The impact of the latter on the endothelium exacerbates endothelial damage, thereby, increasing the number of CECs and NO level in blood, activating processes of aggregation, adhesion and hemostasis. We have established a strong direct relationship between CECs in pregnant women after 20-22 weeks of gestation and IL-I^ and TNF-a levels (r=0.81 and r=0.86; P<0.001).
Thus, damage of the endothelium and other tissues during pregnancy is the triggering factor of ED and cytokine production. In this case, there was a strong relationship between the concentrations of IL-I^, TNF-a and NO in blood of pregnant women predisposed to GH (r=0.81 and r=0.90; P<0.001, respectively). Previous studies in vitro showed that NO expression may be one of the mechanisms of the phenomenon of leukocyte aggression [5]. Probably, NO expression leads to stimulation of cells of the immune system and facilitates the production of the studied pro-inflammatory cytokines. Increase of the concentrations of IL-I^ and TNF-a leads to activation of the haemostatic system, consequently, reducing the potential of shift, stimulating iNOS activity and, as a result, increasing NO level. Our studies are consistent with previous findings. After 7-10 weeks of gestation, all pregnant women of main group marked increase of adhesiveness of platelets to lymphocytes, which was within the upper limit of control. After 20-22 weeks of gestation, lymphocyte-platelet plugs increased in the 1st, 2nd and 3rd groups in 1.2 (P<0.05), 1.3 (P<0.01) and 1.4 (P<0.001) times, respectively, with trend to increase significantly at later terms.
In pregnant women with predisposition to HIP we found a direct strong relationship between adhesive ability of lymphocytes, blood platelets and CECs in the circulating blood (r=0.88; P<0.001). Therefore, high concentration of pro-inflammatory cytokines, between which and the percentage of lymphocyte-plate co-aggregates was marked a strong direct relationship (r=0.83-0.88; P<0.01) as well, is believed to be the starting mechanism of these processes in the development of GH. Earlier established fact of in vitro LPA amplification by IL-I^ and TNF-a confirms our findings [3; 13; 15]. It was
