[Relapsing-remitting multiple sclerosis: clinical and immunological aspects of the pathology on the example of molecules Sema4D and CD72]

OBJECTIVE

To study the expression of Sema4D (CD100), receptor CD72 and a role of Sema4D-CD72-dependent signal in the control of the functions of immunocompetent cells in relapsing-remitting multiple sclerosis (RRMS).

MATERIAL AND METHODS

We studied 76 patients, including 52 with RRMS (41 in remission and 11 in exacerbation), 35 women (67.3%) and 17 men (32.7%) aged 18-55 years, who did not receive disease-modifying drugs, and 24 healthy donors. A controlled clinical and immunological examination of patients with RRMS was carried out proving the involvement of the Sema4D molecule and its CD72 receptor in pathological reactions in this autoimmune disease.

RESULTS AND CONCLUSION

The use of SemaD as a target in the treatment of RRMS is scientifically substantiated. In case of a positive decision on the use of anti-Sema4D drugs, it will be necessary to take into account the effects of semaphorin not only in the central nervous system, but also in the immune system of patients with RRMS.

[Relapsing-remitting multiple sclerosis: clinical and immunological aspects of the pathology on the example Sema4D and CD72]

AIM

To explore the expression of Sema4D, CD72 receptor and a role of Sema4D-CD72 signal in the control of immunocompetent cell function in remitting-relapsing multiple sclerosis (RRMS).

MATERIAL AND METHODS

Fifty-two patients with RRMS diagnosis according to 2010 revised McDonald's criteria were studied. The control group included 24 healthy people. A flow cytometry method was used to measure the expression of semaphorin Sema4D by T-lymphocytes of peripheral blood, expression of CD72 receptor by B-lymphocytes, percentage of cells containing pro- and anti-inflammatory cytokines. The level of soluble Sema4D (sSema4D) was evaluated by ELISA.

RESULTS

The level of Sema4D expression on T-lymphocytes (Mean Fluorescence Intensity - MFI) prevailed in cell subpopulations in patients with RRMS compared with the control group. Characteristics of membrane and sSema4D correlate with clinical presentations of the autoimmune disease. An increase in sSema4D level during cell cultivation was identified in RRMS patients. The results show the involvement of Sema4D in the hyperactivation of B-cell-mediated immunity through CD72 receptor and induction of proinflammatory cytokine synthesis.

CONCLUSION

RRMS is associated with elevated expression of Sema4D in the immune system. Membrane and sSema4D involved in the pathological process in RRMS. The authors suggest several mechanisms of the involvement of semaphorin and its receptor in the pathogenesis of RRMS: the direct damage of nervous tissues by sSema4D penetrated through the blood brain barrier disrupted in RRMS or by membrane Sema4D due to the infiltration of the central nervous system by T-lymphocytes and hyperactivation of B-cell-mediated immunity.

Molecular Mechanisms of Control of Differentiation of Regulatory T-Lymphocytes by Exogenous Melatonin

We investigated the role of epiphyseal hormone melatonin in the differentiation of naive CD4⁺ T cells into regulatory T cells (Treg). The hormone at physiological and pharmacological concentrations inhibited Treg differentiation, decreasing both the proportion of CD4⁺FOXP3⁺ cells in the culture and the level of TGF-β, the key cytokine for this T cell subpopulation. The inhibitory effect of exogenous melatonin was due to its interaction with the membrane receptors MT1 and MT2. At the same time, the signals realized through RORα-the nuclear receptor for melatonin-stimulated Treg formation; however, they were considerably weaker than the signals from the membrane receptors and were overlapped by the latter. Since the Treg subpopulation plays an important role in physiological and pathological processes in the body, the revealed effects of melatonin should be taken into account in its therapeutic use.

New aspects of the Seam4D-dependent control of lymphocyte activation

Novel targets for action of the class IV semaphorin Seam4D have been identified in the immune system. The low-affinity CD72 receptor for Seam4D was detected not only on B lymphocytes, but also in a proportion of T cells, whereas the high-affinity semaphorin receptor, plexin B1, originally considered to belong to non-immune cells, proved to be in a great proportion of intact T and B cells. Seam4D is constitutively expressed in B cells, which, along with T cells, can serve as a source of both membrane and soluble semaphorin. The results obtained make significant adjustments in understanding of Seam4D effects in lymphoid cells.

[Melatonin as an inducing factor for multiple sclerosis]

Melatonin is one of the most multifunctional regulators in the organism. It plays a key role in the control of nerve, endocrine, and immune systems. Due to hormone neuroprotective activity, the possibility is now discussed on its clinical usage in treating neurodegenerative diseases, including multiple sclerosis. At the same time, melatonin is an effective regulator of immune reactions, in part, the reactions toward autoantigens. In this respect, the subset ofT lymphocytes producing IL-17 (Th17) is of special interest. As the Th17 subset plays a key role iri multiple sclerosis pathogenesis, the immunomodulating hormone effects toward Th17, may, in theory, nullify its positive neuroprotective activity.

[Neuroinflammatory, Neurodegenerative and Structural Brain Biomarkers of the Main Types of Post-Stroke Cognitive Impairment in Acute Period of Ischemic Stroke]

Background

Post-stroke cognitive impairment is a clinically heterogeneous condition, some types of which cannot be fully differentiated neuropsychologically that necessitates the active search for biomarkers.

Aims

Analyze parameters of neuroinflammation and neurodegeneration in combination with neuroimaging markers in patients with different types of post-stroke cognitive impairment in acute ischemic stroke.

Materials and Methods

In 72 patients we performed the assessment of cognitive status and distinguished 3 types: normal cognition, dysexecutive, and mixed cognitive impairment. In each group we determined the concentration of cytokines (IL-1β, IL-6, TNFα, IL-10) in liquor and serum, β-amyloid 1−40 in liquor and a number of MRI morphometric parameters and fractional anisotropy.

Results

In all groups of patients we detected higher level of IL-10 in serum compared with the control. Patients with dysexecutive cognitive impairment had higher concentration of IL-1β, IL-10 in liquor, IL-6 level in serum, lower fractional anisotropy of ipsilateral thalamus compared with patients with normal cognition and largest size of infarct. Patients with dysexecutive and mixed cognitive impairment had the higher area of leukoareosis and ventricular volume, reduced fractional anisotropy of contralateral cingulum compared with patients with normal cognition. Patients with mixed cognitive impairment characterized by lower fractional anisotropy of contralateral fronto-occipital fasciculus compared with patients with dysexecutive cognitive deficit.

Conclusions

Serum and cerebrospinal fluid concentrations of cytokines studied in combination with MRI parameters particularly fractional anisotropy seems to be informative biomarkers of pathogenic types of PSCI.

[THE RELATIONSHIP BETWEEN SERUM AND LIQUOR IL-1β, IL-6, TNFα, IL-10 LEVELS AND CLINICAL, COGNITIVE AND FUNCTIONAL CHARACTERISTICS IN ACUTE ISCHEMIC STROKE]

INTRODUCTION

Inflammation is probably the main process that links cardiovascular risk factors with damage to blood vessels and neurons. Elucidation of mechanisms of this relationship is an important issue.

MATERIALS AND METHODS

70 acute stroke patients were studied to assess their neuropsychological (MMSE, MoCA, FAB, Clock Drawing Test, Shulte Tables and Verbal Fluency) and functional status (mRS, Rivermead Mobility Index). The serum and liquor IL-1β, IL-6, TNFa and IL-10 levels were analyzed. Control group included subjects without cerebrovascular diseases.

RESULTS

Stroke patients had higher IL-10 serum concentration than controls. No difference was found for other cytokines. There was correlation between serum and liquor cytokines levels. We found positive correlation between IL-1β, IL-6 and IL-10 levels. High IL-1β concentration was associated with vascular risk factors, cardio embolic stroke, enhanced severity of cerebral stroke, low processing speed, impaired executive and visual-spatial functions and higher grade of mRS on discharge. The same pattern was revealed for IL-6 and IL-10. IL-6 level was related to mRS without relation to NIHSS on admission. High TNFa concentration was linked with vascular risk factors, low MMSE score and processing speed.

DISCUSSION

Despite the antagonistic effects of IL-1β, IL-6 and IL-10 on inflammation, associations of these cytokines with anamnestic, clinical, neuropsychological and functional characteristics were similar in acute ischemic stroke. Probably, this fact indicates that during the acute ischemic brain damage process the immune response develops at the same time in pro- and anti-inflammatory directions. Its magnitude correlates with the damage severity and is associated with the effects of vascular risk factors before stroke.

Role of B cells in presentation of autoantigens to CD4(+) T cells in patients with autoimmune thyroiditis

The antigen-presenting activity of B cells and expression of molecules involved in antigen presentation by B cells have been studied in patients with autoimmune thyroiditis (AIT). The disease is characterized by enhanced expression of the costimulatory molecule CD80 in naive B cells (CD19(+)CD27(-) cells) both ex vivo and under the conditions of polyclonal cell activation in a culture. Under in vitro conditions, antigen-loaded B cells have been shown to be capable of inducing proliferation of autologous CD4(+) cells, in particular, proliferation of autospecific T cells in patients with AIT. Given that an intense infiltration of thyroid tissue by B cells is a typical sign of AIT, the antigen-presenting activity of B cells appears to contribute to this pathology.

[Extrathymic Differentiation of αβT Lymphocytes]

Extrathymic differentiation is an alternative way of αβT lymphocyte development. In normal conditions it is expressed slightly and limited mainly to the liver and intestinal mucous. However, it increases significantly with age, as well as in certain physiological and pathological conditions, buying more widespread. In the review, the phenotypical and functional features of extrathymic T lymphocytes have been considered in detail depending on their localization and a way of the process activation. The mechanisms of such differentiation induction have been analyzed. Special attention is paid to the biological significance of extrathymic αβT cell development.

Semaforin Sema4D in the immune system in multiple sclerosis

The expression of class IV semaforin Sema4D and its CD72 receptor on lymphocytes was studied in patients with multiple sclerosis. The disease was associated with an increase in Sema4D level on intact T lymphocytes and with its more intense shedding from the membrane of activated cell. Multiple sclerosis was also associated with a decrease of CD72 receptor expression by B lymphocytes. Possible contribution of Sema4D to the disease development via the direct effects in the CNS and the immunomodulatory effect, specifically, B cell activity regulation, was discussed.

Molecular mechanisms of T-cell anergy

Anergy is a long-term stable state of T-lymphocyte unresponsiveness to antigenic stimulation associated with the blockade of IL-2 production and proliferation. Anergy is a pathway of peripheral tolerance formation. In this review, mechanisms underlying T-cell tolerization are considered in a classical in vitro model of clonal anergy, and these mechanisms are compared with different pathways of anergy induction in vivo. Special attention is given to regulatory T-lymphocytes because, on one hand, anergy is a specific feature of these cells, and on the other hand anergy is also a mechanism of their action on target cells - effector T-lymphocytes. The role of this phenomenon in the differentiation of regulatory T-cells and also in the development of activation-induced apoptosis in effector T-lymphocytes is discussed.

[Extrathymic differentiation and antigen response of alphabetaT lymphocytes in pregnancy]

We studied reactivity of alphabetaT lymphocytes in CBA pregnant females toward male antigens and the presence of gene rearrangement in T-cells antigen receptor in peripheral lymphoid organs of mice in the case of three breeding variants: CBA x BALB/c (normal allogenic pregnancy), CBA x CBA (syngenetic pregnancy), and CBA x DBA/2 (prone to abortion combination). It was shown that proliferative response of alphabetaT lymphocytes in pregnant CBA females to male spleen cells was the most marked at normal allogenic pregnancy, the least marked at syngenic pregnancy, and was not observed at the combination CBA x DBA/2. In addition, cells ofparaaortic lymphatic nodes (draining uterus) respond to male antigen reliably more effectively than lymphocytes in mesenterial and axillary lymphatic nodes. Simultaneous estimation of recombinase RAG-1, the key enzyme in rearrangement of T-receptor genes, revealed similar principles: predominant activity of recombinase in T lymphocytes in paraaortal lymphatic nodes of CBA pregnant females. This points to the relationship between extrathymic rearrangement of antigen receptor genes and change in the antigen-detecting repertoire of these cells. The possible biological significance of the discovered phenomenon is discussed.

[The CD100 semaphorin expression on peripheral blood T-lymphocytes in patients with relapsing-remitting multiple sclerosis]

The expression of CD100 semaphorin by the intact peripheral blood T lymphocytes in multiple sclerosis (MS) has been studied. The level of middle florescence intensity (MFI) and the number of B-lymphocytes bearing CD72 were evaluated. There were significant differences in the level of CD100 in patients compared to healthy volunteers. These data suggest the use of semaphorin as a possible therapeutic target in pathological inflammation in MS.

Role of cyclooxygenase in the chorionic gonadotropin regulation of human neutrophil activity

The involvement of cyclooxygenase in the regulation of the main functions of human neutrophils by chorionic gonadotropin was studied. The inhibitory effect of the hormone on phagocytosis and oxidative activity of neutrophils is completely or partially canceled under conditions of cyclooxygenase blocking. In addition, gonadotropin directly induces the expression of cyclooxygenase inducible form mRNA in these cells. These data indicate that realization of the suppressive effects of chorionic gonadotropin in the neutrophils is partially linked with activation of cyclooxygenase (both the constitutive and inducible forms of the enzyme).

Extrathymic rearrangement of alphabetaT-lymphocyte antigen receptor genes during pregnancy

The existence of alphabetaT-lymphocyte differentiation processes have been demonstrated in mouse peripheral lymphoid organs during pregnancy. Study of pregnant Swiss mice has shown that the development of the second half of gestation is accompanied by expression of RAG-1 recombinase mRNA and unrearranged TCR alpha-chain (pre-TCRalpha) preferentially in T-lymphocytes of lymph nodes involved in uterine drainage (para-aortal lymph nodes), and to a lesser extent in other lymph nodes (mainly from axillary lymph nodes). The data suggest that during pregnancy the differentiation of alphabetaT lymphocytes may occur not only in central (thymus) but also in peripheral lymphoid organs.

Revision of the antigen receptor of T-lymphocytes

This review considers a crucially new mechanism of T-cell antigen-recognizing repertoire formation. It includes the revision of T-cell antigen receptor (TCR), which implies the secondary rearrangement of TCR genes in peripheral T-lymphocytes and surface expression of a new antigen receptor with altered specificity. Factors and mechanisms involved in the induction of this process have been analyzed. Certain attention is paid to a possible role of TCR revision in the formation of peripheral tolerance in the processes of "avidity maturation" of T-lymphocytes during immune response and also negative consequences related to appearance of potentially autoreactive clones in the periphery.

[Reproductive hormones in the control of Th1/Th2 cytokine balance]

Individual and combined effects of chorionic gonadotropin (CG), estradiol, and progesterone on the production of IFNgamma and IL-4 by human peripheral blood lymphocytes was studied in vitro together with certain intracellular mechanisms underlying the hormonal effects. High CG dose (100 IU/ml) proved to significantly decrease IFNgamma level in the T cell culture supernatant, although this effect was not observed at the background of steroid hormones. In contrast, progesterone (100 ng/ml) increased IFNgamma production by activated T lymphocytes but proved inefficient in a physiological combination with CG and estradiol. IL-4 production was almost doubled by all studied hormones and their combinations, which considerably decreased the IFNgamma/IL-4 ratio in the culture. Inhibition analysis employing blockers of cAMP-dependent protein kinase (H-89) and L-type calcium channels (verapamil) as well as an antagonist of progesterone nuclear receptors (RU-486) demonstrated that the inhibitory (for IFNgamma) and stimulatory (for IL-4) effects of CG were mediated by cAMP, while the effects of steroid hormones on the production of these cytokines were realized through genomic and non-genomic mechanisms (the latter mechanisms were largely mediated by L-type calcium channel regulation). Overall, the studied reproductive hormones could efficiently regulate synthesis of the main Th1 (IFNgamma) and Th2 (IL-4) cytokines by T lymphocytes and seem to play the key role in changing the pregnancy-specific pattern of secreted cytokines.

[Molecular mechanisms of thymocyte differentiation]

A review of the main molecular events occurring during differentiation of T-lymphocytes in the thymus: T-cell specialization of early intrathymic precursors, formation and expression of antigen receptor, formation of antigen recognizing cell repertoire, and alpha beta/gamma beta- and CD4/CD8-commitment. The mechanisms of glucocorticoid-induced apoptosis of thymocytes and its blockade during antigen-dependent activation are considered. A special attention is paid to the analysis of intracellular signals underlying the clonal selection of thymocytes.

[Regulation of oxidative activity of neutrophils by chorionic gonadotropin. The role of female steroid sex hormones]

We studied the effect of the main sex hormone, chorionic gonadotropin, on the production of the active forms of oxygen and nitrogen by human neutrophils and the control of its effects by female steroid sex hormones. Gonadotropin proved to inhibit both total production of oxygen metabolites and NO synthesis by the cells. Gonadotropin-dependent regulation of oxidative activity of the neutrophils is controlled by female steroid sex hormones. At the same time, progesterone completely or partially inhibits the suppressive effects of gonadotropin, while estradiol has antagonistic, sensibilizing, or permissive effect on gonadotropin depending on the dose, incubation conditions, and activation status of the cells.

Reproductive hormones in the regulation of apoptosis of neutrophils

The ability of main reproductive hormones such as chorionic gonadotropin (CG), estradiol, and progesterone to regulate apoptosis of human neutrophils was studied. The hormones were studied separately and in physiological combinations specific for different trimesters of pregnancy. A low dose of CG (10 IU/ml) increased the spontaneous apoptosis of neutrophils, whereas its combination with estradiol and progesterone corresponding to that of trimester III of pregnancy significantly decreased this parameter. The stimulating effect of CG was prevented by an inhibitor of protein kinase A, whereas the hormone-induced suppression of apoptosis depended on the activity of Ca2+-channels. The antiapoptotic effect of the hormonal combination corresponding to that of trimester III was also manifested in the presence of autologous T-lymphocytes and on stimulation of neutrophils by bacterial lipopolysaccharide. The apoptosis induced with monoclonal antibodies to CD95 was significantly suppressed by the hormones studied and their combinations. Thus, apoptosis of neutrophils is effectively regulated by reproductive hormones; this seems to be an important control mechanism of activation of these cells in pregnancy.

Role of reproductive hormones in control of apoptosis of T-lymphocytes

Effects of chorionic gonadotropin (CG), estradiol, progesterone, and their physiological combinations on apoptosis of human peripheral blood T-lymphocytes were studied. Neither the hormones separately nor their combinations affected the spontaneous apoptosis of T-cells. On stimulation with mitogens, a high dose of CG (100 IU/ml) significantly increased apoptosis of T-lymphocytes, but its combination with steroid hormones specific for trimester I of pregnancy decreased this parameter. Apoptosis of T-lymphocytes induced by neutrophils in mixed culture was also inhibited by the hormone combination corresponding to trimester I. In greater detail, this hormonal combination was shown to display differential effects on different T-cell subpopulations: it stimulated apoptosis of CD8(+)-lymphocytes (which seemed to be provided by CG) and inhibited apoptosis of CD4(+)-cells. Apoptosis of T-lymphocytes induced by anti-CD95 was suppressed by a high dose of progesterone (100 ng/ml) and also by its combination with CG and estradiol specific for trimester III of pregnancy. Thus, the reproductive hormones studied effectively regulated apoptosis of peripheral blood T-lymphocytes. The effect of the hormones depended on the cell type and their activation and seemed to be an important mechanism of hormonal control of immune reactions in pregnancy.

[Effect of chorionic gonadotropin on thymocyte differentiation in the presence of thymus epithelial cells]

We studied the effects of the main placental hormone, chorionic gonadotropin, on differentiation of human thymocytes in vitro in the presence of thymic epithelial cells. It was shown that the hormone at a high dose (100 IU/ml) enhanced the epithelium-induced phenotypic maturation of thymocytes, which is registered by an increased expression of the membrane marker CD3 and transition of CD4+8+ thymocytes in the cells with CD4+8- and CD4-8+ phenotypes. In addition, gonadotropin enhanced the proliferative response of thymocytes to the mitogen during their cultivation with the epithelium. The stimulating effect of the hormone on the epithelium-induced differentiation of thymocytes is mediated by the humoral factors of epithelial cells. In addition, gonadotropin at this dose exerts its own differentiating activity with respect to thymocytes and stimulates their phenotypic and functional maturation in a monoculture.

Role of cAMP and neutrophil cyclooxygenase in gonadotropin-dependent regulation of T lymphocyte proliferation

The effect of the main pregnancy hormone, chorionic gonadotropin (CG), on proliferation of peripheral blood mononuclear cells (PBMC) was studied in the presence of autologous neutrophils; also, hormone-dependent regulation of the cAMP levels in T lymphocytes and neutrophils was evaluated. PBMC proliferation in response to a mitogen is suppressed by physiological doses of CG (10, 50, and 100 IU/ml). Autologous neutrophils enhance the suppression induced by the low dose of CG (10 IU/ml), but when cyclooxygenase was inhibited this effect was not observed; this suggests that the anti-proliferative effects of the low dose of CG can be mediated by the products generated by neutrophil cyclooxygenase. The effect of CG was associated with increased cAMP levels in T lymphocytes and neutrophils. Comparison of functional and cAMP-related effects of CG in both cell populations indicates that cAMP is involved in the anti-proliferative effects of CG.

Role of transcription factor NFAT in the immune response

Molecular mechanisms of activation of nuclear factor NFAT in cells of the lympho-myeloid complex are considered. Members of the NFAT family regulate transcription of genes encoding proteins involved in the induction and/or regulation of the immune response. It is possible that altered transcription activity of NFAT under conditions of its deficit or blockade of expression may account for changes in the immune status of an organism.

Role of cAMP-dependent signal transduction in the control of T lymphocyte activation

The role of cAMP in the regulation of antigen-dependent differentiation of T cells is discussed with consideration of the molecular mechanisms of cAMP effects. Characteristics of activation signal in various T lymphocyte subpopulations determining differential sensitivity to cAMP are reviewed. Specific attention is given to the involvement of the cAMP-dependent messenger system in the formation of the spectrum of secreted cytokines because their level and ratio determine the type of immune response.

[Modulation of the neutrophil functional activity by chorionic gonadotropin]

The functions of nonpregnant woman neutrophils in the presence of chorionic gonadotropin (CG) have been studied, as well as possible mechanisms of intracellular hormone signaling. Expression of adhesion molecule CD18 and phagocyte activity of the cells are shown to be inhibited by a high dose of CG (100 IU/ml). Oxygen metabolite production by activated neutrophils decreases almost in a half in the presence of hormone, irrespective of the dose. Synthesis of nitric oxide, an oxidant and effective regulator molecule, is also suppressed by CG. Neutrophil incubation with hormone induces a dose-dependent modulation of intracellular cAMP level. The effect of CG is most strongly expressed for a low hormone dose (10 IU/ml), implying the presence of high affinity hormone-binding structures on the cell membrane. Judging from the correlation of data obtained, the functional effects of CG cannot be attributed to the regulation of adenylatcyclase activity and suggests that this is not the major mechanism of hormone signal transduction. Neutrophil sensitivity to suppressive CG effects is one of the ways of regulating nonspecific defence reactions in different physiological and/or pathological states connected with the presence of this hormone in the organism.

[Role of chorionic gonadotropin in the differentiation of thymocytes]

The effects of chorionic gonadotropin, a basic hormone of pregnancy, on the differentiation of the human thymocytes were studied. The hormone does not affect the phenotype as determined by expression of the membrane molecules CD3, CD4, CD8 and functional activity of intrathymic pre-T-lymphocytes, but stimulates production of autocrine growth factors by these cells. Cultivation of cortical thymocytes in the presence of chorionic gonadotropin induces their phenotypic maturation with predominant development of CD4+ CD8- cells. In addition, at a high physiological dose (100 MU/ml) the hormone induces functional maturation of the cortical thymocytes. Thus, the data obtained allow us to consider this hormone as a factor regulating antigen-independent differentiation of T-lymphocytes during pregnancy and determining development of the immune system in embryogenesis.