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Usmanova Durdona Djurabaevna, Doctor, of Medical Sciences, Assistant, the Department of Neurology, Tashkent Pediatric Medical institute, Pediatric Neurology and Medical Genetics Arifdjanova Jonona Farrukh qizi, Student, the Faculty of Pediatrics Tashkent Pediatric Medical institute, E-mail: [email protected]
IMMUNOLOGICAL MECHANISMS OF PROGRESSING AND COURSE OF CHRONIC BRAIN ISCHEMIA ON THE BACKGROUND OF ARTERIAL HYPERTENSION AND ATHEROSCLEROSIS
Abstract: Nowadays, cerebral vascular diseases remain at the center of society's attention due to the very alarming epidemiological situation of the incidence of stroke in Uzbekistan, as well as the catastrophic consequences of different forms of cerebrovascular pathology for the physical and mental health of the nation [1].
Keywords: chronic cerebral ischemia, proinflammatory cytokines, arterial hypertension.
Numerous large-scale studies have shown that the atherosclerotic.) All the examined patients were dimain cause and the most important factor of chronic cerebral ischemia (CCI) is AH (arterial hypertension) and cerebral artery atherosclerosis [3, 8, 9]. They have a key role in vascular dementia [1, 5, 7]. Numerous studies have demonstrated the involvement of inflammation in atherogenesis and the development of CCI [4, 9]. Even with relative functional preservation, patients with CCI develop autoimmunization to the structural components of the neural tissue, which depends not only on the antigen release beyond the blood-brain barrier, but also on the violation of the complex regulation of the neu-roimmune system that determines immune homeostasis [6, 10]. However, the role of the immuno-mediated inflammatory process as a possible universal constituent pathogenesis of CCI of various genesis is unspecified.
The aim of the study was to study the proinflammatory cytokines: IL-1^, TNF-a and IL-6, in the serum of peripheral blood of patients with CCI, depending on its genesis (hypertonic and atherosclerotic), and on the degree and duration of hypertension.
Material and methods of the study. We studied several proinflammatory cytokines: IL-1^, TNF-a and IL-6, in the serum of peripheral blood of 84 patients with CCI, depending on its genesis (hypertonic and
vided into 2 groups according to the pathogenesis of the development of the CCI.1 group comprised 53 (63.1%) patients with CCI, which developed mainly on the background of hypertension. According to the classification of hypertension depending to the level of blood pressure in accordance with the recommendations of the Russian Society for Arterial Hypertension and the All-Russian Scientific Society of Cardiology (3rd revision, 2008) [2], we divided the patients of group 1 into 3 subgroups: 21 patients with AH I degree, 22 patients with AH of II degree and 10 patients with AH of III degree. Also divided by the duration of hypertension: AH I degree 5 years were10 patients, more than 5 years - 11. With AH II degree 5 years - 12 patients, more than 5 years were 10 patients. The 2nd group included 31 (36.9%) patients with CCI, which developed mainly on the background of atherosclerosis. A control group for the purpose of comparing im-munological studies comprised 29 practically healthy donors. Studies of the cytokine content (IL-1^, IL-6, TNF- a) in serum of peripheral blood were determined by ELISA analysis using commercial test systems Vector-Best, Novosibirsk, Russia, 2013. Statistical processing was carried out on a personal computer Pentium-4.
Results and its discussion. A comparative analysis of the level of proinflammatory cytokines in patients with CCI in both groups of patients revealed the presence of a significant difference with the values of the control group (Table 1). Thus, the content of IL-1^ in the serum of patients with CCI showed a significant increase in 1.51 (P < 0.05) and 1.28 (P < 0.05) times, relatively to the
Table 1.- The average indices of ml) in patients with CCI of
values of practically healthy individuals, respectively, in 1st and in the 2nd groups. Moreover, the highest content of IL-1^ was diagnosed in patients of the 1st group: an increase in 1.18 (P < 0.05) times the values of patients with CCI of atherosclerotic origin: in the first group of patients IL-1^ was 14.96 ± 0.86 pg/ml, whereas in the second group - 12.71 ± 0.58 pg/ml.
proinflammatory cytokines (pg / different genesis, M ± m
Index Control group. n = 29 1st group. n = 53 p1 2 nd group. n = 31 p. P2
IL-1| 9.94 ± 1.78 14.96 ± 0.86 < 0.05 12.71 ± 0.58 < 0.05 < 0.05
IL-6 3.42 ± 0.28 9.06 ± 0.54 < 0.001 6.94 ± 0.34 < 0.001 < 0.01
TNF-a 4.58 ± 0.81 11.70 ± 0.64 < 0.001 8.04 ± 0.36 < 0.001 < 0.001
According to literature data, IL-1^ is a multifunctional cytokine with a wide spectrum of action, plays a key role in the development and regulation of nonspecific defense and specific immunity, one of the first included in the response protective reaction of the organism under the action of pathogenic factors (Biochemmak). The main producers of IL-1^ are macrophages and monocytes, as well as lymphocytes, fibroblasts. IL-1^ initiates and regulates inflammatory, immune processes, activates neutrophils, T- and B-lymphocytes, stimulates the synthesis of acute phase proteins, cytokines (IL-2,-3,-6, TNF-a), adhesion molecules (E -selectins), procoagulants, prostaglandins. It increases chemotaxis, phagocytosis, hemopoiesis, permeability ofthe vascular wall, cytotoxic and bactericidal activity, has a pyrogenic effect, etc. Endothelial cells of human vessels under the influence of IL-1a and ^ secrete polypeptides, like thrombocyte growth factor. These polypeptides can stimulate cellular migration and proliferation and cause the release of vascular mediators of inflammation, which, with a significant increase in these cytokines, can lead to an disseminated intravascular coagulation. The observed increase in the level of IL-1^ in our patients seems to be due to the stimulation of pre-IL^ ligand by the CD40 ligand and the release ofbiologically active cytokine in en-dothelial cells and arterial cells, thus indicating both the mechanism of DIC activation in the inflammatory process atherogenesis and other pathological conditions, as well as a new mechanism of IL-1^ activation in vascular cells. It has been established that Th1 cells produce powerful cytokines with a pro-inflammatory effect, such as IL-1^, TNF-a, etc. [6, 8]. Th2 cells secrete anti-inflammatory cytokines, such as IL-4, which stimulate the predominantly
humoral immunity unit. Violation of the balance of production of Th1/Th2 cytokines is of great importance in the immunopathogenesis of the development of CCI and its progression. Based on the foregoing, we studied the cytokine content of IL-6 in the serum of patients with CCI. Analysis of the content of IL-6 in the serum of peripheral blood of patients with CCI allowed to reveal a significant increase in all study groups relatively to control. Thus, in the 1st group, the IL-6 level was increased 2.65 times (P < 0.001), in the 2nd group - in 2.02 times (P < 0.001), with respect to the control, making 9.06 ± 0, 54 pg/ml and 6.94 ± 0.34 pg/ml, respectively. As can be seen from the data presented, at CCI ofhypertensive genesis, the changes in IL-6 level are more pronounced and significantly exceed the values of patients with CCI atherosclerotic genesis of 1.31 times (P < 0.01). It should be noted that IL-6 induces the synthesis of acute phase proteins, and therefore (as well as IL-1^ and TNFa) can be referred to as inflammatory cytokines. According to the literature, IL-6 causes a significant increase in the level of the c-sis gene (^-chain) mRNA in cultured human endothelial cells, which can mediate inflammatory vascular effects. Another cytokine that determines the development of inflammatory processes is TNF-a. The study of its level in patients with CCI ofdifferent genesis showed a significant increase in all patients. Thus, it was found that the serum level of TNF-a in the group of patients of the 1 st and 2nd groups was increased in 2.56 (P < 0.001) and 1.76 (P < 0.001), respectively, relatively to the control group, 11.70 ± 0.64 pg/ml and 8.04 ± 0.36 pg/ml in the 1st and 2nd groups, with a control value of 4.58 ± 0.81 pg/ml. We found a significant increase in the levels of TNF-a in groups of patients
with CCI in the background of hypertension, and in the first group of patients the level of TNF-a was increased in 1.45 times compared with the value of the second group. Consequently, we found a significant increase in serum TNF-a in both groups of patients with CCI, which can serve as a criterion for the presence of an inflammatory process in CCI.
It should be noted that the group of tumor necrosis factors includes TNFa and | (lymphotoxin). TNFa is a product of monocytes/macrophages, endothelial, mast and myeloid cells, glia cells, in special cases - activated T-lymphocytes. The latter are the main producers of TNF|, which is formed by the action of antigens and mitogens on T-cells much later than TNFa (2-3 days after activation). There are three main areas of action of TNF: cytotoxic, directed at tumor cells or cells infected with viruses; immunomodulatory and anti-inflammatory, causes the activation of macrophages, neutrophils, eosinophils, and endo-thelial cells; influence on the metabolism, which can lead to hyperglycemia, bone resorption and increased muscle glycogenolysis, i.e. cachexia, observed in some parasitic infections. As a result of the release of TNF, the permeability of capillaries increases, the endothelium of the vessels is damaged, and intravascular thrombosis develops. It is TNF-a that plays an important role in the development of inflammatory vascular lesions. Excessive levels of proinflammatory cytokines, such as TNF-a, IL-1| and IL-6, contribute to the maintenance ofthe inflammatory process in the body as a whole and can enhance blood coagulation.
At the same time, of the proinflammatory cytokines studied by us, the highest level was determined by IL-6 in relatively to the control. However, the severity of these changes was different. The greatest increase was characteristic for IL-6 and TNF-a. Thus, in patients with hypertensive CCI, the level of these cytokines exceeded the values of IL-1| and TNF-a in 1.76 (P < 0.01) and 2 (P < 0.001) times, respectively. In patients with CCI of atherosclerotic genesis, this increase was 1.59 (P < 0.01) and 1.37 (P < 0.05) times, respectively, IL-6 and TNF-a cytokines. In our opinion, this is due to the development of inflammatory vascular effects under the influence of IL-6 and TNF-a: an increase in the penetration of capillaries, damage to the endothelium and the development ofintravascular thrombosis. Next, we studied the status of proinflammatory cytokines, depending on the degree of hypertension in patients with chronic hypertensive genesis (Table 2). It was found that the serum level of IL-1| in patients with AH I degree was 11.39 ± 1.17 pg/ml, AH II degree - 15.95 ± 0.98 pg/ml (P < 0.01), AH III - 20.27 ± 2.26 pg/ml (P < 0.01). It should be noted that the content of IL-1| in AH I degree only tended to increase, whereas as the weight ofhypertension increased, the changes were statistically significant: an increase of 1.61 (P < 0.01) in AH II degree and 2, 04 (P < 0.001) times with AH III degree in relation to the control. In the intergroup difference, it was found that the level of IL-1| was increased by 1.4 (P < 0.01) in patients with AH II and in 1.78 (P < 0.01) in patients with AH grade III group AH I degree.
Table 2. - The average indices of proinflammatory cytokines (pg / ml) in patients with chronic hypertensive genesis as a function of the degree of hypertension, M ± m
Index Control group. n = 29 Group 1 (n = 53)
AH degree I. n = 21 AH of II degree.n = 22 AH III degree. n = 10
IL-1p 9.94 ± 1.78 11.39 ± 1.17 15.95 ± 0.98**AA 20.27 ± 2.26**AA
IL-6 3.42 ± 0.28 6.89 ± 0.82*** 9.75 ± 0.61***AA 12.12 ± 1.29***AA
TNF-a 4.58 ± 0.81 9.07 ± 0.96*** 12.63 ± 0.81***AA 15.21 ± 1.32***AAA
Note: * - the differences with regard to the control group are significant (** - P < 0.01, *** - P < 0.001);A - the differences relatively to the AH data of the 1st degree are significant (AA - P < 0.01, AAA - P <0.001).
Unlike the IL-1^ indices, the content of IL-6 in the serum of peripheral blood of patients increased more strongly. Thus, in patients with AH I degree, the level of IL-6 increased statistically significantly in 2.1 (P < 0.001) times, in 2.85 (P < 0.001) times - with AH II degree and in 3.54 (P < 0.001) times - with AH III degree in relation to the control. Thus, IL-6 in the group of patients
with AH I degree was 6.89 ± 0.82 pg/ml, with grade II AH - 9.75 ± 0.61 pg/ml, while in the group with grade III AH - 12, 12 ± 1.29 pg/ml. Regarding the values ofpa-tients with AH I degree, in patients with II grade hypertension the level of IL-6 increased in 1.42 (P < 0.01), and in patients with AH III this increase was 1.76 (P < 0.01) times. As can be seen from the data presented, the IL-6
content progressively increases with the aggravation of the pathological process. Analysis of the level of TNF-a in the serum of patients with AH showed a progressive increase in it. Thus, in patients with AH I, AH II and AH III degrees, the level of this cytokine was increased in 1.98 (P < 0.001); 2.76 (P < 0.001) and 3.32 (P < 0.001), respectively, with respect to the values of the control group of individuals. We found a significant increase in the level of TNF-a in the group of patients with AH III degree. In comparison with the indices of the group of patients with AH I degree, the values of TNF-a increased in 1.4 (P < 0.05) times in the group of patients with AH ofII degree and in 1.7 (P < 0.01) times - in patients with AH III degree.
Thus, the conducted studies showed a progressive increase in the content of the cytokines studied as the degree of hypertension increased. The greatest changes are characteristic for AH III degree, especially IL-6 and TNF-a. Next, we studied the content of proinflammatory cytokines as a function of the duration of hyper-
analysis showed that the serum level of IL-1^ in patients with AH I degree up to 5 years was 10.22 ± 0.92 pg/ml, more than 5 years - 12.67 ± 2.23 pg/ml. They had only a tendency to increase relative to the values of practically healthy individuals, the differences between the groups were statistically insignificant. The serum IL-6 level was 6.26 ± 0.62 pg/ml and 7.59 ± 1.60 pg/ml in the group of patients with AH I degree with duration of disease up to and above 5 years, exceeding the normative values of 1, 83 (P < 0.001) and 2.22 (P < 0.001) times, respectively. The differences between the groups were statistically insignificant. The level of TNF-a in the group of patients with AH I degree to 5 years and more than 5 years was 8.15 ± 0.71 pg/ml and 10.08 ± 1.86 pg/ml, exceeding the normative values of 1.78 (P < 0.01) and 2.2 (P < 0.01) times, respectively, with respect to the control. The differences between the groups were statistically insignificant. As can be seen from the data presented, the differences in the content of proinflammatory cytokines as a function of the duration of hypertension were insignificant and not reliable.
tension in patients of group 1 (Table 3). Comparative
Table 3. - The content of proinflammatory cytokines (pg / ml) in patients, depending on the duration of hypertension, M ± m
Index Control group (n = 29) 1 group (n = 43)
AH 1st degree (n = 21)
AH < 5 years (n = 10) AH >5 years (n = 11)
IL-1| 9.94 ± 1.78 10.22 ± 0.92 12.67 ± 2.23
IL-6 3.42 ± 0.28 6.26 ± 0.62*** 7.59 ± 1.60*
TNF-a 4.58 ± 0.81 8.15 ± 0.71** 10.08 ± 1.86*
AH of II degree (n = 22)
AH < 5 years (n = 12) AH > 5 years (n = 10)
IL-1| 9.94 ± 1.78 14.75 ± 1.36*AA 17.15 ± 1.38**AAA
IL-6 3.42 ± 0.28 9.36 ± 0.81***AA 10.15 ± 0.94***AA
TNF-a 4.58 ± 0.81 11.89 ± 1.07***AA 13.36 ± 1.23***AA
Note: * - the differences relatively to the control group are significant (* - P < 0.05, ** - P < 0.01, *** - P < 0.001), A - differences relatively to group AH data < 5 years are significant (AA - P < 0.01, AAA - P < 0.001).
The level ofIL-1^ in the group ofpatients with AH of II degree up to 5 years was 14.75 ± 1.36 pg/ml, and in the group with grade II AH more than 5 years - 17.15 ± 1.38 pg/ml, exceeding normative values in 1.48 (P < 0.05) and 1.73 times (P < 0.01). The differences between the groups were statistically insignificant. The IL-6 content in the group of patients with grade II AH up to 5 years was 9.36 ± 0.81 pg/ml, and in the group with grade II
AH more than 5 years - 10.15 ± 0.94 pg/ml. These values were statistically significantly higher than those of practically healthy individuals at 2.74 (P < 0.001) and 2.97 (P < 0.001) times. However, the differences in the rates between the groups, depending on the duration of the disease, we did not reveal. The TNF- a content in the group of patients with grade II AH up to 5 years was 11.89 ± 1.07 pg/ml, and in the group with grade II AH
more than 5 years - 13.36 ± 1.23 pg/ml. These values statistically significantly exceeded those of healthy subjects in 2.6 (P < 0.001) and 2.92 (P < 0.001) times. However, the differences in the rates between the groups, depending on the duration of the disease, we did not reveal.
Consequently, in patients with grade II AH, the changes in the indices of all cytokines studied did not depend on the prescription of hypertension.
Thus, the severity of changes in the content of proinflammatory cytokines in patients with CCI of hypertonic genesis, depending on the duration of the disease, was not revealed.
The increase the levels of IL-1^, IL-6 and TNF-a in patients with CCI on the background of hypertension convincingly reflects the dynamics of the immu-nopathological process, correlating with the clinical picture and the more pronounced decrease in the cognitive scores in this group of patients. In many respects the development of cerebrovascular insufficiency is determined by the formation of micro- and macroan-giopathies, leading to the formation of metabolic and hemodynamic disorders. Diffuse lesion of small arteries, observed with CCI hypertensive genesis is accompanied by a wide range of changes in the brain. The defeat of the brain is characterized by the gradual ac-
cumulation of ischemic and secondary degenerative changes in the brain, caused by repeated ischemic episodes in various vascular pools, primarily in the blood supply zones of shallow penetrating cerebral arteries and arterioles.
It is known that cerebral ischemia itself leads to the accumulation of cytotoxic substances, which in turn lead to the activation of microglia, which begins to progressively produce cytokines. Apparently, the results obtained by us confirm the increase in the level of proinflammatory cytokines. In addition, a significant increase in production of IL-6 was a marker of the activation of the pathological process in the atherosclerotic genesis of CCI, It is known that IL-6 is an intermediate cytokine, the long-term activation of which is clinically manifested by chronicization and autoimmunization of the organism.
Conclusion: CCI is characterized by an increase in the level of pro-inflammatory cytokines, especially IL-6. The greatest changes were noted in patients with CCI of hypertonic genesis and the dynamics of their level change was directly dependent on the degree of hypertension. The expression of changes in the content of proinflammatory cytokines in patients with chronic hypertensive genesis does not depend on the duration of the disease.
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