Axial spondyloarthritis is characterized by activation of innate immune cells, which manifested in elevation of classical monocytes and predominance of the proinflammatory phenotype. However, the immunosuppressive potential of monocyte/macrophages remains practically unexplored. We evaluated the expression of Mer tyrosine kinase (MerTK) and arginase-1 (Arg1) in monocyte subsets in patients with axial spondyloarthritis, considering different clinical features. The expression of MerTK and Arg1 in intermediate and non-classical monocytes from patients with axial spondyloarthritis was reduced in comparison with the normal. The most pronounced decrease in monocyte expression of MerTK and Arg1 was associated with a more aggressive course of the disease (presence of coxitis, high disease activity, HLA-B27 positivity) and lack of response to conventional therapy. These data demonstrate an important role of MerTK and Arg1 in limiting myeloid-driven inflammation.

BACKGROUND:In multiple myeloma (MM), immune checkpoint blockade is being explored as a treatment strategy. However, the role of inhibitory checkpoint receptors on myeloid cells remains poorly understood. The aim of our study was to investigate the expression of PD-1 and TIM-3 on monocytes and monocytic myeloid-derived suppressor cells (M-MDSCs) and their contribution to early immune reconstitution. METHODS:The count of monocytic cells and expression of PD-1 and TIM-3 was assessed by flow cytometry. RESULTS:At the engraftment, monocyte subsets counts were similar to pre-transplant values, while the relative content of M-MDSCs was significantly higher. The frequencies of TIM-3-positive cells among intermediate and non-classical monocytes were significantly increased. Incubation of mononuclear cells of MM patients in remission with homeostatic cytokines led to a significant increase in intermediate monocytes and a trend to an increase in the M-MDSCs count and stimulated the expression of PD-1 and TIM-3. PD-1 and TIM-3 expression on monocytes and M-MDSCs inversely correlated with lymphocyte count at the engraftment. TIM-3 expression on monocytic cells was associated with regulatory T-cell count. After auto-HSCT, PD-1/TIM-3-expressing cells exhibited significantly elevated IL-10 production (with decreased TNFα production). CONCLUSION:PD-1 and TIM-3 on monocytic cells may play a significant role in immune reconstitution.

We studied the ability of human macrophage conditioned media to inhibit differentiation of lung fibroblasts in vitro. The results showed that the conditioned medium of M-CSF-differentiated non-polarized macrophages (induced by macrophage CSF) suppressed TGF-β-induced differentiation, reduced the expression of myofibroblast markers (α-smooth muscle actin and vimentin), and decreased the contractile activity of lung myofibroblasts, while the conditioned media of dexamethasone-polarized macrophages and GM-CSF-differentiated non-polarized macrophages (differentiation stimulus is granulocyte-macrophage CSF) produced no such effects. Thus, the obtained data indicate the antifibrogenic potential of non-polarized M-CSF-differentiated macrophages.

Aim – to evaluate myeloid-derived suppressor cell (MDSC) subset counts and their suppressor potential in axial spondyloarthritis (axSpA) patients, as well as to analyze changes in the studied parameters in biological therapy (BT). Materials and methods. The study included 50 axSpA patients receiving 1st line therapy (non-steroidal anti-inflammatory drugs ±sulfasalazine/methotrexate) and 44 ageand sex-related healthy donors. Eight patients were initiated with BT (TNFαor IL-17 inhibitors). Peripheral blood granulocytic (G-MDSC), monocytic (M-MDSC) MDSCs, early-stage differentiation MDSCs (E-MDSC), and inhibitory molecule expression (PDL1, Arg-1, and IDO) were evaluated by flow cytometry. Results. The axSpA patients were characterized by increased G-MDSC counts (р<0.01), particularly manifested with high disease activity. Axial manifestation was associated with a combination of increased G-MDSC and E-MDSC numbers (р<0.05). The extra-axial group showed an isolated increase in G-MDSC (р<0.05), whereas coxitis was associated with an increase in both G-MDSC and M-MDSC (р<0.05). Low activity was associated with an isolated M-MDSC increase (р=0.045). Patients had reduced expression of majority of the studied suppressor molecules in MDSCs. Axial manifestation was characterized by a decreased expression of PDL1 and IDO in G-MDSCs and E-MDSCs (р<0.05), as well as Arg-1 in E-MDSCs and M-MDSCs (р<0.05). Patients with extra-axial manifestations (including coxitis) exhibited the most significant reduction in the expression of all three inhibitory molecules in M-MDSCs. High activity was associated with a decrease in PDL1+ G-MDSCs and E-MDSCs (р<0.05), as well as Arg-1and IDO-expressing M-MDSCs (р<0.05). In low disease activity, most of the analyzed parameters did not differ significantly from donor values, with the exception of a reduced Arg-1+ M-MDSC frequency (р=0.04). BT reduced G-MDSC counts in 75% of patients to levels comparable to those of healthy donors. Conclusion. Despite the reduced suppressor potential of MDSCs, patients undergoing first-line therapy with high activity demonstrated increased G-MDSC counts, while low activity axSpA was characterized by an isolated increase in M-MDSCs. The BT administration blocked G-MDSC accumulation.

Apoptosis and subsequent removal of dead cells are an essential part of wound healing. Macrophages phagocytize apoptotic cells (efferocytosis) and contribute to the resolution of inflammation. However, their participation in fibrogenesis and the mechanisms of influence on this process remain unclear. In the present study, we focused on the fibrogenic properties of human monocyte-derived macrophages polarized in the M2 direction by interaction with apoptotic cells. We studied their influence on the proliferation ([3H]-thymidine incorporation), differentiation (by the expression of α-SMA, a myofibroblast marker) and collagen-producing activity (ELISA) of dermal fibroblasts compared to classically (LPS) and alternatively (IL-4) activated macrophages. Macrophages polarized by the interaction with apoptotic cells had a unique phenotype and profile of produced factors and differed from the compared macrophage subtypes. Their conditioned media promoted the proliferation of dermal fibroblasts and the expression of α-SMA in them at the level of macrophages stimulated by IL-4, while the stimulating effect on the collagen-producing activity was more pronounced compared to that of the other macrophage subtypes. Moreover, they are characterized by the high level of production of pro-fibrotic factors such as TIMP-1, TGF-β1 and angiogenin. Taken together, M2-like macrophages polarized by efferocytosis demonstrate in vitro pro-fibrotic activity by promoting the functional activity of dermal fibroblasts and producing pro-fibrotic and pro-angiogenic factors.

Innate immune cells, including myeloid cells — myeloid derived suppressor cells (MDSCs) — are supposed to play an important role in the pathogenesis of axial spondyloarthritis (AxSp). Myeloid derived suppressor cells represent a heterogeneous population of immature cells capable of suppressing innate and adaptive immune responses with the most pronounced suppressor activity against T cells. Biological disease-modifying antirheumatic drugs (bDMARDs) can reduce the clinical and laboratory disease activity, but their effectiveness varies widely in different patients with AxSp. The present study is aimed at studying MDSCs subpopulations and their suppressive function depending on the response to bDMARD therapy in AxSp. The study included AxSp patients with a disease duration of 16.5 years (median); HLA-B27 (+) status was detected in 79% of cases. All patients received bDMARDs at least the past 12 weeks, including TNF inhibitors (etanercept, certolizumab pegol, adalimumab, or golimumab) or IL-17 inhibitors (secukinumab, ixekizumab, or netakimab). Percentage of granulocytic MDSCs (G-MDSCs, Lin-HLA-DR-CD33+CD66b+), monocytic MDSCs (M-MDSCs, HLA-DRlow/-CD14+), MDSCs of early stage differentiation (E-MDSCs, Lin-HLA-DR- CD33+CD66b-), as well as intracellular expression of arginase-1 was assessed by flow cytometry. Frequency of circulating MDSC subpopulations of patients with a stable response to bDMARDs (responders) did not differ significantly compared to healthy donors. Patients not responding to bDMARDs therapy showed increased relative and absolute number of E-MDSCs compared to healthy donors (pU = 0.01 and pU = 0.02, respectively) and the responders (pU = 0.03 and pU = 0.07, respectively). Increased percentage of E-MDSCs was positively correlated to disease activity — ESR (Rs = 0.821; p = 0.023), CRP (Rs = 0.714; p = 0.07) and ASDASCRP (Rs = 0.829; p = 0.042) in the non-responder group. Responder patients exhibited no correlation between disease activity and circulating MDSCs. The suppressor potential of MDSCs was analyzed by the intracellular expression of arginase-1 molecule which is involved in the inhibition of T cell response. Patients with the stable response were characterized by increased expression of arginase-1 in E-MDSCs compared to donors (pU = 0.02). Non-responders did not demonstrate significant changes in Arg-1 expression, however, the percentage of arginase-1-expressing G-MDSCs was positively correlated to indexes ASDASESR (Rs = 0.857; p = 0.014) and BASDAI (Rs = 0.785; p = 0.036). Thus, E-MDSCs as well as arginase-1 expression in MDSCs may serve as biomarkers of effectiveness bDMARD therapy, and act as potential candidate predictors of response to therapy in AxSp.

Maternal adaptation of the immune system aimed at limiting the immune response to fetal antigens is a necessary condition for a successful pregnancy. It involves various mechanisms (Th1/Th2 switching, Treg expansion, induction of anergy and apoptosis of T lymphocytes, development of T cell depletion) that are induced through the ligation of inhibitory receptors. Accordingly, the expression of inhibitory receptors on T cells, including PD-1, CTLA-4, and Tim-3 molecules, may reflect the effectiveness of immune adaptation and its impairment in pregnancy pathology. Preeclampsia (PE), the pathogenesis of which is associated with the impairments of immunological tolerance is a major complication of pregnancy. Accordingly, changes in the expression of inhibitory receptors on T cells may be biomarkers of abnormal gestation and potential therapeutic targets. The aim of this work was to study the expression of inhibitory molecules on peripheral blood T cells in women with PE. The study recruited 29 pregnant women with PE and 36 women with uncomplicated pregnancies in the second half of pregnancy. Pregnant women of the study groups were comparable in terms of gestational age, number of pregnancies and parity of childbirth. The control group consisted of 28 fertile women with children. Relative content of CD8+PD-1+, CD8+CTLA-4+, CD8+TIM-3+, CD8+PD-1+TIM-3+, CD4+PD-1+, CD4+CTLA-4+, CD4+TIM-3+, CD4+PD-1+TIM-3+T cells in blood were analyzed by flow cytometry. It has been shown that uncomplicated pregnancy is associated with increased expression of PD-1 and Tim-3 T cells, which is manifested by an increase in the relative content of CD4+Tim-3+, CD8+PD-1+ and PD-1+Tim-3+T lymphocytes . In PE, on the contrary, there is a reduction in the expression of PD-1 and Tim-3 by T cells, in particular, a decrease in the proportion of CD4+Tim-3+ and CD8+PD-1+ cells; the absence of elevated levels in PD-1+Tim-3+ cells (compared to uncomplicated gestation) and an increase in CTLA-4+ cells within CD4+ lymphocytes. Changes in the expression of inhibitory receptors are associated with the severity of PE. A decrease in CD4+Tim-3+ and CD8+PD-1+T cells is most typical for patients with moderate PE, and an increase in CD4+CTLA-4T cells for pregnant women with severe PE. The relationship between changes in the expression of inhibitory molecules and the onset of PE has also been demonstrated. A distinctive feature of early PE is a decrease in the proportion of CD8+CTLA-4+ cells and a more pronounced increase in CD4+CTLA-4+ cells, while late PE is associated with a decrease in CD4+PD-1+ cells and a more pronounced decrease in CD4+Tim-3+ cells. The results obtained indicate a changes in the expression of CTLA-4, PD-1 and Tim-3 molecules on circulating T cells in pregnant women with PE and the association of these changes with the severity and the onset of PE manifestation.

We studied angiogenin production by human macrophages and evaluated the role of this factor in the macrophage-mediated regulation of fibroblasts. All macrophage subtypes, and especially the efferocytosis-polarized macrophages, M2(LS), actively produced angiogenin. Exogenous recombinant angiogenin dose-dependently enhanced the proliferation and differentiation of dermal fibroblasts. The addition of the angiogenin inhibitor to fibroblasts cultures suppressed the stimulating effect of exogenous angiogenin or M2(LS) conditioned media. These findings indicate the involvement of angiogenin in the macrophage-mediated paracrine regulation of skin fibroblasts.

During pregnancy, the maternal immune system must maintain tolerance to paternal antigens, at the same time being able to eliminate pathogens, which is achieved by the weakening of adoptive immunity and the activation of innate immunity, in particular, monocytes. However, the question about the functional phenotype of monocytes, having not only pro-inflammatory, but also anti-inflammatory activity, remains open. In the given work, we have investigated the expression of M2-associated suppressive markers Arg1 and MerTK in monocyte subpopulations during uncomplicated pregnancy. Fifty-three pregnant women with uncomplicated gestation were recruited, including 14 pregnant in the 1st trimester, 20 – in the 2nd and 19 – in the third pregnancy trimester. The comparison group consisted of 15 fertile unpregnant women without aggravated somatic anamnesis, with a history of at least one childbirth. The findings showed that in the unpregnant group circulating Mo express Arg1 and MerTK, and the most relative number of Arg1+ and MerTK+ cells is concentrated in intermediate and nonclassic monocytes. During pregnancy the expression of researched molecules in monocytes reliably increases. An increase in MerTK expression is manifested by a simultaneous increase in the number of MerTK+ cells and the mean fluorescence intensity of this marker; it is observed in the 1st and 2nd trimesters and registered in all three monocyte subpopulations. At the same time, an increase in Arg1 expression is manifested either by an enhancement of Arg1+ cells, or an increase in receptor density; it is registered throughout pregnancy, including the 3rd trimester, and is maximally expressed in classic monocytes. There is a direct correlation between the number of Arg1+ and MerTK+ cells in intermediate Mo, which increases with the progression of pregnancy, and in the 3rd trimester is also detected in classical and non-classical Mo. In general, the revealed increase in the expression of Arg1 and MerTK by monocytes indicates an increase in the anti-inflammatory potential of monocytes during pregnancy, and the involvement of monocytes in the regulation of the inflammatory process at the system level. Moreover, the features of Arg1 and MerTK expression in various monocyte subpopulations during pregnancy suggest that monocytes expressing Arg1 and MerTK can mediate different mechanisms of immune adaptation during pregnancy.

Background. Inhibitory receptors and their ligands (also called checkpoint molecules) are important feedback regulators of the immune response. However, their role in immunological adaptation during pregnancy remains poorly understood.The aim of the study was to evaluate the level of checkpoint molecule (PD-1, CTLA-4, Tim-3) expression in peripheral T cells in pregnant women compared with fertile non-pregnant women.Materials and methods. The study included 36 women in the second half of pregnancy without pregnancy complications, 12 of whom had extragenital pathology. The control group consisted of 28 age-matched fertile non-pregnant women. The proportion of CD8+PD-1+, CD8+TIM-3+, CD8+PD-1+TIM-3+, CD4+PD-1+, CD4+TIM-3+, and CD4+PD-1+TIM-3+ was evaluated by flow cytometry using the corresponding monoclonal antibodies (BD Biosciences, USA).Results. The proportion of CD4+Tim-3+ and CD8+PD-1+ Т cells and CD4+ and CD8+ Т lymphocytes co-expressing PD-1 and Tim-3 in the peripheral blood of pregnant women was statistically significantly higher than in non-pregnant women. An increase in CD4+Tim-3+ and CD8+PD-1+ T cells was observed both in pregnant women with and without extragenital pathology. However, pregnant women with extragenital pathology were characterized by a higher CD8+PD-1+ count and a smaller number of CD8+Tim-3+ cells, as well as by a lack of an increase in PD-1+Tim-3+ T cells typical of pregnant women. The number of comorbidities was directly correlated with the proportion of CD8+PD-1+ lymphocytes and inversely correlated with the proportion of CD8+Tim-3+ and CD4+ PD-1+Tim-3+ cells. In addition, the expression of checkpoint molecules was associated with gestational age (a direct correlation was found with the proportion of CD8+Tim-3+, CD4+PD-1+Tim-3+, and CD8+PD-1+Tim-3+ cells) and to a lesser extent – with the age of pregnant women (an inverse relationship was found with the proportion of CD8+Tim-3+ cells).Conclusion. Pregnant women in the second half of pregnancy are characterized by increased expression of PD-1 and Tim-3 molecules in peripheral T cells. At the same time, concomitant extragenital pathology affects the expression of these molecules.

In humans circulating monocytes include classical (CD14++CD16- ), intermediate (CD14++CD16+) and non-classical/alternative (CD14+CD16++) monocytes, which in turn can be activated via the classical or alternative pathway. Pregnancy is accompanied by significant changes in the monocyte compartment, which is manifested by an increase in the number of circulating monocytes, including the proportion of intermediate monocytes, and a change in their function. However, the functional properties of monocyte subsets during gestation remain largely unexplored. We hypothesized that circulating monocytes may be activated in an alternative pattern and acquire features of M2 polarization (anti-inflammatory / immunosuppressive properties). The aim of the investigation was to study M2-associated markers that characterize the anti-inflammatory and immunosuppressive potential of myeloid cells in subpopulations of circulating monocytes in fertile nonpregnant women and women with uncomplicated pregnancy in the 2nd trimester. It was shown that in fertile non-pregnant women intermediate and non-classical monocytes are characterized by a higher expression of M2-associated markers (CD206, Arginase 1, MerTK) compared to classical monocytes. In the 2nd trimester of pregnancy, the expression of these molecules on monocytes increases significantly, which is manifested by 1) an increase in the proportion of CD206+ cells in subpopulations of classical and intermediate monocytes, 2) an increase in the mean fluorescence intensity of Arginase 1 in all monocyte subsets, 3) an increase in the proportion of MerTK+ cells in subpopulations of classical and intermediate monocytes and mean fluorescence intensity across all monocyte subsets. The highest content of CD206+ and MerTK+ cells in pregnant women is detected in the subpopulation of intermediate monocytes, and the highest values of the mean fluorescence intensity of Arginase 1 and MerTK – in the subpopulations of intermediate and non-classical monocytes. The data obtained demonstrate that monocytes of pregnant women in the 2nd trimester of pregnancy are characterized by signs of M2 polarization. This is confirmed not only by an increase in the expression of the M2-associated mannose receptor CD206, but also by an increase in the expression of Arginase 1 and MerTK, which mediate the immunosuppressive activity of myeloid cells and, in particular, macrophages of the M2 phenotype. Further studies of M2-associated markers in monocyte subpopulations during gestation will allow a more detailed characterization of the regulatory role of circulating myeloid cells during pregnancy.

GM-CSF and M-CSF, the hematopoietic colony-stimulating factors, induce various phenotypic changes in macrophage lineage populations and promote cell differentiation, respectively, into M1- and M2-like macrophages. The pro- and anti-inflammatory properties of macrophages generated by these colony-stimulating factors are well described, but the contribution of differentiation and polarization signals to the fibromodulatory activity of macrophages remains unexplored. To clarify the differences in the fibrogenesis regulation mechanisms inherent in differently activated macrophages, we studied the effects of macrophage-conditioned media on proliferation and differentiation of dermal fibroblasts. In this study, the human macrophages generated from peripheral blood monocytes were investigated. They were induced for differentiation by M-CSF or GM-CSF, being further polarized in the M1 direction with lipopolysaccharide and, in the M2 direction, with IL-4 or dexamethasone. Proliferative response of the fibroblasts was determined radiometrically by [3H]-thymidine incorporation. Differentiation into myofibroblasts was determined with flow cytometry technique, as expression of a specific marker α-smooth muscle actin (α-SMA). The level of macrophage TGF-β1 production was assessed using an appropriate ELISA kit. The data obtained indicate that the macrophages differentiated under the influence of “homeostatic” M-CSF are characterized by a moderate stimulating effect upon fibroblast proliferation, and the effects of M2 (IL-4) and M2 (Dex) macrophages exceed that of M1 (LPS), but do not differ significantly from each other. The M-CSF-induced M1 (LPS) and M2 (IL-4) macrophages, but not M2 (Dex), enhance the fibroblast differentiation and show similar level of stimulation. In contrast to M-CSF, the macrophages induced by “pro-inflammatory” GM-CSF exhibit a pronounced stimulatory effect on fibroblast proliferation, and the effects of M2 macrophages exceed those of M1 cells, being most pronounced for M2 (Dex). At the same time, only GM-CSF-induced M2 (IL-4) macrophages enhance fibroblast differentiation. Dexamethasone-polarized macrophages do not significantly affect fibroblast differentiation regardless of the CSF used (M-CSF or GM-CSF). The content of TGF-β1 in the supernatants of differently activated macrophages does not correlate with the level of stimulating effect of macrophage-conditioned media upon fibroblast differentiation. In general, the data obtained suggest the involvement of differentiation and polarization signals into modulation of pro- and anti-fibrogenic properties of macrophages.

Viral hepatitis remains the most common cause of liver cirrhosis (LC). Monocytes, capable of migrating to the liver and participating in inflammation and fibrogenesis, play an important role in the LC pathogenesis as confirmed by the association of certain monocyte subsets with the disease severity and mortality in alcoholic and biliary LC. However, the clinical and prognostic relevance of monocytes in viral LC remains poorly investigated. This study was aimed to investigate the disturbances in circulating monocytes including classical (CD14++CD16, cMo), intermediate (CD14++CD16+, iMo) and non-classical monocytes (CD14+CD16++, nMo) in patients with viral LC, as well as their correlation with viral characteristics, LC severity and progression of the disease 12 months after combination therapy. A significant increase in iMo and nMo, cMo level tended to decrease, and a two-fold decline in cMo/iMo ratio was revealed in patients with viral LC vs. healthy donors. These changes in monocyte pattern did not depend on the type of virus (HCV vs HBV/HDV) or its replication (replication vs the integrative phase), but were associated with the LC severity. The iMo level was positively correlated with laboratory indicators of liver damage, ChildPugh (rS = 0.57; P = 0.001) and MELD score (rS = 0.41; P = 0.033). ROC analysis showed that the cMo/iMo ratio at 9.5 allowed to predict the risk of LC progression with a sensitivity of 83.3% and a specificity of 76.2%. Of note, in comparison groups patients with alcoholic or biliary/autoimmune LC also demonstrated increased frequencies in iMo and nMo and decreased cMo/iMo ratio. However, in this case, the LC severity was negatively correlated with CD16+monocytes, particularly with the iMo and nMo subset, respectively, in alcoholic and biliary LC, evidencing the protective role of such cell subsets. Thus in viral LC the changes in circulating monocyte profile to increased iMO and nMo as well as decreased cMo are not associated with the virus type and replication; in contrast to the alcoholic and biliary/autoimmune LC, the level of iMo directly correlates with the indicators of liver damage and LC severity; cMo/iMo ratio is a biomarker of therapy response/disease progression.

Expansion of myeloid-derived suppressor cells (MDSCs) due to impaired differentiation of myeloid progenitor cells under conditions of inflammation was described in a number of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, and type 1 diabetes mellitus. Studying the role of MDSCs in ankylosing spondylitis is an important issue, given that increased concentration of proinflammatory mediators in this pathology can also cause myelopoiesis disorders. The aim of present work was to study the quantitative content of MDSC subpopulations in patients with different clinical phenotypes and activity of AS. 37 patients, including 10 patients without peripheral skeletal lesions (axial form) and 27 patients with simultaneous lesions of spine and peripheral joints (peripheral form) were recruited into the study. The control group consisted of 32 age/sex-related healthy donors. Evaluation of granulocytic (LinHLA-DRCD33+CD66b+; G-MDSC), monocytic (CD14+HLA-DRlow/-; M-MDSC) and early-stage MDSCs (LinHLA-DRCD33+CD66b- ; E-MDSC) was performed using corresponding antibodies (BD Biosciences, USA) in the population of peripheral blood mononuclear cells by flow cytometry. In general, the AS patients were characterized by an increased relative and absolute amount of M-MDSC (p = 0.00002 and p = 0.00003, respectively) and G-MDSC (p = 0.0002 and p = 0.0006, respectively). Patient gender, age, and HLA-B27 expression did not significantly affect the content of these cells in peripheral blood. An increase in the median values of M-MDSC was detected both in patients with axial (Ме 5.0 (3.2-6.3) versus 2.4 (1.7-3.5) %; p = 0.001) and peripheral form (Ме 5.0 (3.0-7.0) versus 2.4 (1.7-3.5) %; p = 0.0002) AS. At the same time, the G-MDSC expansion was observed only in patients with involvement of peripheral joints (Ме 0.16 (0.07-0.3) % versus 0.05 (0.04-0.09) %; p = 0.0001). The relative contents of E-MDSC, M-MDSC and G-MDSC in the axial form of AS was in direct correlation with the activity of the disease (R = 0.58, p = 0.02; R = 0.73, p = 0.08 and R = 0.65 p = 0.04, respectively). This relationship was not observed in peripheral form of AS. The data obtained suggest a potential involvement of MDSCs in pathogenesis and phenotypic heterogeneity of AS. Simultaneously, the revealed direct correlation between the MDSC contents and the disease activity suggests a decrease in suppressive activity and/or appearance of pro-inflammatory activity in MDSC, thus requiring further research in the field.

We studied the effect of conditioned media of GM-CSF-differentiated human macrophages polarized in M1(LPS), M2a(IL-4), M2c(dexamethasone), and M2(low serum) phenotypes on proliferation, differentiation, and collagen-producing activity of dermal fibroblasts. It was found that M1(LPS) and M2a(IL-4) were characterized by moderate influence on functional activity of fibroblasts. At the same time, soluble factors of M2c(dexamethasone) significantly enhanced the proliferative response of fibroblasts, but not their differentiation and type I collagen production. On the contrary, M2(low serum) generated under conditions of growth factors deficiency had a pronounced stimulating effect on the differentiation of fibroblasts and production of type I collagen by these cells, but moderately stimulated the fibroblast proliferation. Thus, the secretory activity of various functional phenotypes of macrophages is an important mechanism of fibrogenesis regulation.

We studied the expression of arginase-1 (Arg1) and tyrosine kinase Mer (MerTK) in GMCSF-differentiated human macrophage populations М0, М1(IFNγ), М2а(IL-4), and М2(low serum) generated under conditions of growth/serum factor deficiency. The maximum relative content of Arg1+ and MerTK+ cells was found in М2 macrophage populations: М2а(IL-4) and М2(low serum). As the uptake of apoptotic cells is the key mechanism of M2 polarization during M2(low serum) generation, we performed a special series of experiments and showed that incubation with allogeneic apoptotic neutrophils significantly increased the percentages of CD206+ macrophages co-expressing Arg1 and MerTK.

In the present study, we used multicolor flow cytometry assay to measure the numbers of various myeloid suppressor cell subpopulations (Lin-HLA-DR-CD33+, Lin-HLA-DR-CD33+CD66b+, and CD14+HLA-DRlow/-) in peripheral blood of 51 participants, including 33 patients with viral- and 1 8 patients with «nonviral» (alcoholic or biliary/autoimmune) liver cirrhosis. Patients in both groups had increased proportions of Lin-HLA-DR-CD33+, Lin-HLA-DR-CD33+CD66b+, and CD 14+HLA-DRlow/-cells which levels did not depend on the type and replication of the virus in viral liver cirrhosis. In viral liver cirrhosis, the relative numbers of Lin-HLA-DR-CD33+cells directly correlated with the albumin levels (Rs=0.45; p=0.029). In «nonviral» group an inverse relationship was found between these indicators (Rs = -0.56; p=0.02), in addition the proportion of Lin-HLA-DR-CD33+and CD14+HLA-DRlow/-cells directly correlated with disease severity scores (Child-Pugh and MELD) direct correlation of the proportion of Lin-HLA-DR-CD33+and CD14+HLA-DRlow/-cells with the disease severity scores (Child-Pugh and MELD). Comparison of the initial content of myeloid suppressors with the response to complex therapy (that included autologous bone marrow-derived cell transplantation), showed that in viral liver cirrhosis, the proportion of Lin-HLA-DR-CD33+cells was characterized by a prognostic significance and, at values

Background. Recent studies demonstrated immunosuppressive properties of vascular endothelial growth factor (VEGF-A) and identified VEGF-A as a key mediator of tumor-induced immunosuppression. Placental growth factor (PlGF) is another member of VEGF family in which dramatic elevation is associated with effective immune adaptation in successful pregnancy, whereas low concentrations are related to pregnancy complications resulting from the activation of immune system. Previously, we have shown that activated T cells express VEGF receptor type 1 (VEGFR-1), and PlGF inhibits T cell proliferation in VEGFR-1–dependent manner.The aim of the present study was to further characterize PlGF effects on T cell responses in vitro.Materials and methods. Peripheral blood mononuclear cells (PBMC) from healthy donors were stimulated with anti-CD3 monoclonal antibodies (a-CD3) in the absence or presence of PlGF and assessed for IL-10 production, programmed cell death and the expression of inhibitory receptors (PD-1, CTLA-4, Tim-3) in CD4+ and CD8+ T cell subsets.Results. The addition of PlGF to PBMC cultures activated with a-CD3 resulted in increased percentages of IL- 10-producing CD4+ and CD8+ T cells. Besides, PlGF promoted CD8+ T cells apoptosis while did not affect programmed cell death within CD4+ T cells. Notable, T cell activation with a-CD3 in the presence of PlGF was accompanied by the enhancement of PD-1-expressing cells in CD8+ T cell subset and Tim-3-expressing cells in both CD4+ and CD8+ T cells, and by the increased expression of PD-1 and Tim-3 on T cells.Conclusion. Our in vitro findings indicate that PlGF can inhibit T cell responses due to the increasing interleukin-10 (IL-10) production, promoting CD8+ T cell apoptosis and enhancing the expression of PD-1 and Tim-3 inhibitory receptors. Given the elevated levels of PlGF in successful pregnancy and its decrease in gestation complications, the obtained data also suggest that PlGF-mediated suppression may be implicated into the governing immune evasion in pregnancy.

Besides an antigen-presenting function and ability to induce antitumor immune responses, dendritic cells (DCs) possess a direct tumoricidal activity. We previously reported that monocyte-derived IFNα-induced DCs (IFN-DCs) of glioblastoma multiforme patients express low levels of membrane TNFα molecule (mTNFα) and have impaired TNFα/TNF-R1-mediated cytotoxicity against immortalized tumor cell line HEp-2. However, whether the observed defect could affect killer activity of glioma patient DCs against autologous tumor cells remained unclear. Here, we show that donor IFN-DCs possess cytotoxic activity against glioblastoma cell lines derived from a primary tumor culture. Granule-mediated and TNFα/TNF-R1-dependent pathways were established as the main mechanisms underlying cytotoxic activity of IFN-DCs. Glioblastoma patient IFN-DCs showed lower cytotoxicity against autologous glioblastoma cells sensitive to TNFα/TNFR1-mediated lysis, which was associated with low TNFα mRNA expression and high TACE/ADAM-17 enzyme activity. Recombinant IL-2 (rIL-2) and human double-stranded DNA (dsDNA) increased 1.5-fold cytotoxic activity of patient IFN-DCs against autologous glioblastoma cells. dsDNA, but not rIL-2, enhanced the expression of TNFα mRNA and decreased expression and activity of TACE/ADAM-17 enzyme. In addition, dsDNA and rIL-2 stimulated the expression of perforin and granzyme B (in the presence of dsDNA), suggesting the possibility of enhancing DC cytotoxicity against autologous glioblastoma cells via various mechanisms.