FATTY ACID RECEPTOR GPR84 AND Th1/Th2 BALANCE IN THE EXPERIMENTAL SYSTEM IN VIVO

While conducting numerous studies, including researchers in our laboratory, it was found that Th1/Th2 balance plays an essential role in the regulation of reactions that determine the outcomes of immunopathological processes in both chronic and acute GVHD models. However, the question about activity of which element in the regulatory process during GVHD induction (for example, a receptor or an enzyme) affects the ratio of this balance depends remains open. It has been suggested that the degree of activation of the GPR84 receptor during GVHD induction can significantly affect the host Th1/Th2 balance. And, by assessing this parameter, the direction of development and the intensity of the pathological process can be determined. The aim of this work was to investigate the effect of ligands such as medium-chain fatty acid receptor GPR84 on the Th1/Th2 balance in an experimental model in an in vivo system.Female DBA/2 and hybrids (C57Bl/6 × DBA/2) F1 mouse strains were used in the experiments.The studied ligands of GPR84 were capric and lauric acids, as well as a synthetic ligand 6-OAU. Chronic GVHD in the semi-allogenic system was induced by injecting splenocytes from DBA/2 mice to B6D2F1 hybrid mice: 60-70 × 106 -cells iv twice with an interval of 6 days. The first administration of the GPR84 ligands was performed one hour after the donor cell transfer and then once a day for two weeks.The effect of the study drugs on the course of chronic GVHD was assessed three months after the onset of the experiment.It was shown that the administration of GPR84 ligands to to animals during the induction of chronic GVHD affects the activity of the receptor and the host Th1/Th2 ratio. In the group with the injection of 6-OAU, the number of animals which the immunopathological process developed according to the Th1-dependent variant increased by more than 1.5-fold, compared with the control group. This fact is consistent with the literature data obtained in the in vitro system. Apparently, the effect of a mixture of capric and lauric acids is mediated by some other mechanism, differed from the GPR84 activation. Therefore, further research is required to realize the promising possibility of adjusting immune responses by including certain fatty acids in the diet

LYMPHOPENIA AS A FACTOR INVOLVED IN THE AUTOIMMUNITY DEVELOPMENT IN MURINE GRAFT VS. HOST DISEASE

Syngeneic splenocyte transplantation leads to lymphopenia development in intact mice owing to decreased proliferative activity of bone marrow hematopoietic progenitor cells. In the mice with induced chronic graft-versus-host disease (cGVHD) transfer of syngeneic lymphocytes has little or no effect on the level of already existing lymphopenia, but increases its duration. These results are in close agreement with the received evidences that transfer of syngeneic cells increases frequency of autoimmune glomerulonephritis at cGVHD. Thus, results of research speak in favor of conclusion that lymphopenia and initiated by it homeostatic proliferation play a pathogenetic role in the development of autoimmune reactions at cGVHD

Extracellular DNA in blood: an index of <i>in vivo</i> inflammatory response

Increased concentration of cell-free DNA (cfDNA) in the circulating blood of humans and animals is a sign of inflammatory conditions and a distinctive characteristic of various pathophysiological processes in the body. The aim of the present study was to investigate the possible role of tumor necrosis factor (TNFα) in changes of cfDNA contents in peripheral blood as a response to experimentally induced systemic inflammation.We used 40 female hybrid mice (C57Bl/6xDBA/2) F1 at the age of 6-8 weeks. The concentration of cfDNA and its individual fractions was determined using a PicoGreen fluorescent dye. The dynamics of inflammatory process was evaluated after 4, 8, 11 and 24 hours following LPS injection. A significant increase in the blood plasma cfDNA levels was shown under the action of E. coli lipopolysaccharide (LPS), along with simultaneous decreased levels of cfDNA, associated with cell surface. The ratio of cell surface-bound cfDNA to the total cfDNA contents was reduced in dose-dependent manner as early as 4 hours after LPS injection to the animals, thus allowing us to consider this ratio a characteristic sign of netosis of neutrophilic granulocytes during the development of acute inflammation. The described effects are significantly suppressed with co-injection of recombinant TNFα neutralizing protein along with LPS, whereas increased intake of neutrophils in the tissues is determined by some other factors which are not directly related to the production of this cytokine.Based on the obtained data, we proposed a following hypothesis: induction of netosis by inflammatory stimuli causes an increase in the concentration of cfDNA in blood plasma not only due to de novo emerging extracellular DNA by neutrophil netosis, but also by the release of distinct cfDNA fraction that was previously firmly bound to cell membranes in multiple body tissues under the action of proteases released during netosis

Influence of soluble factors from the M2 phenotype macrophages on hematopoiesis in depression-like state

Chronic psychosocial stress provokes anxious behavior and depressive disorders. The longitudinal stress-induced neuroendocrine signals may alter functioning of immune (central and peripheral) organs. Increased myelopoiesis is observed in bone marrow, being detrimental to lympho- and erythropoiesis, with increased emigration of monocytic bone marrow cells to the periphery and their acquisition of “inflammatory” phenotype. The subsequent migration of such monocytes to the brain with differentiation into the M1 type macrophages which form inflammatory signals, and their effect upon endothelial cells and microglia leads to increased production of cytokines, chemokines, and adhesion molecules, thus accelerating accumulation of bone marrow-derived monocytes migrating to the brain. The signals from bone marrow monocytes and activated microglia promote neuroinflammatory condition which leads to behavioral changes. Current data on the presence of non-resident bone marrow macrophages in the brain of depressed patients require studies of hematopoiesis in depression-like states. Pronounced plasticity is a characteristic feature of macrophages, i.e., their ability to acquire M1 or M2 phenotype depending on the microenvironment signals. M1 exhibit high pro-inflammatory activity and have neurodestructive properties, whereas M2 cells are characterized by low pro-inflammatory activity and pronounced regenerative potential, due to the production of multiple soluble mediators and cytokines, including neurotrophic and immunoregulatory factors, anti-inflammatory substances that provide neuroprotection, stimulate neurogenesis, synaptogenesis, growth and myelinization of axons, thus theoretically substantiating an opportunity of using the potential of M2 macrophages in the treatment of depression. In this work, we studied the effect of soluble factors of human macrophages, polarized into cells with M2 phenotype under the conditions of serum deprivation, upon bone marrow hematopoiesis and peripheral blood cells in a model of stress-induced depression. We have shown enhanced differentiation of hematopoietic stem cells into the granulocyte-macrophage (CFU-GM) lineage, along with increased monocyte population in peripheral blood in the depressive-like murine model. Development of a depressive-like state in the animals was associated with reduced amounts of both erythroid precursors in bone marrow and erythrocytes/hemoglobin in peripheral blood. Intranasal administration of soluble M2 macrophage factors (M2-SFs) for 7 days was accompanied by a corrective effect on the above parameters, being significant for peripheral blood monocytes. The data obtained suggest effectiveness of the M2-SFS anti-inflammatory effects in correcting changes in hematopoiesis caused by social stress in depressive-like animals

Early markers of phenotypic heterogeneity in the induced model of systemic lupus erythematosus

The study aimed at evaluating the predisposition for development of different variants of SLE based on an inflammatory response in intact mice.Materials and methods. Low-dose systemic inflammatory response was modeled by the administration of lipopolysaccharide (LPS) of E. coli (strain 111: B4) by intact B6D2F1 recipients in the dose of 10 ng/mouse or 1 μg / mouse. We evaluated the number of leukocytes, neutrophils, and lymphocytes in the blood, the index of neutrophils / lymphocytes (ratio N/L), and the level of free DNA (cf DNA cell free) in dynamics. The first day after LPS injection we induced SLE model: the female B6D2F1 mice were injected 60–70 x 106 spleen cells of the DBA / 2 parent mice twice with interval five days. Three months after the induction of the model, the level of protein in the urine was measured twice: the mice with proteinuria 3 mg/ml and more were assigned to the group SLEnephritis+, and mice with less than 3 mg/ml of protein in the urine were assigned to the group SLEnephritis–.Results. It was established that administration of LPS does not change the frequency of nephritis in mice. The retrospective analysis of the number of leukocytes, neutrophils, and lymphocytes does not allow the prediction of the development of nephritis. We observed a significant increase in the frequency and the absolute value of the N/L index at week 8 relative to 4 weeks four weeks before the appearance of proteinuria in the group of mice SLEnephritis+ in contrast to mice SLEnephritis– when LPS was administered at a dose of 10 ng/mouse. Mice SLEnephritis+ and SLEnephritis– show different kinetics of the inflammatory response by an increase in the N/L index every subsequent hour relative to the previous one when LPS was administered at a dose of 1 μg/mouse. The dynamics of the cfDNA level is similar to the kinetics of an index N/L in the group SLEnephritis+ and the SLEnephritis–. The data obtained indicate the possibility of using of the index N/L and cfDNA level as a parameter of inflammatory response in mice and prediction of the susceptibility the development of nephritis

СORRECTION OF AUTOIMMUNE GLOMERULONEPHRITIS BY LETHAL IRRADIATION AND TRANSFER OF SYNGENEIC BONE MARROW CELLS IN AN EXPERIMENTAL MODEL

Mice with lupus-like autoimmune glomerulonephritis induced by chronic graft-versus-host reaction, have been treated with irradiation at lethal doses, followed by injection of bone marrow cells from syngeneic donors. Following such treatment, the autoimmune process was interrupted, as judged by disappearance of anti-DNA autoantibodies in peripheral blood. A drop in urine protein to normal values was also observed in the marrow recipients, thus being a characteristic sign of recovery from glomerulonephritis. Correction of the disease was confirmed by morphological data: the signs of oedema were diminished, and inflammatory reaction was found to be decreased in the kidneys of animals with lupus-like disorder after marrow transplantation

ANTI-ERGOTYPIC RESPONSE: ROLE IN NORMAL IMMUNE RESPONSE AND AUTOIMMUNE PATHOLOGY IN EXPERIMENTAL MODEL

Abstract. Anti-ergotypic cells are a part of peripheral regulatory network, and they are thought to control autoreactive T cells by recognition of certain clonotypic and ergotypic determinants on the surface of activated T cells. The aim of our study was to investigate ability of anti-CD3 activated syngeneic splenocytes to induce anti-ergotypic  response  and  to  assess  immune  response  in  delayed-type hypersensitivity (DTH) reaction.DTH response in experimental group was significantly greater than in control and intact groups. Upon crossadministration, DTH response was minimal and there were no significant differences between the groups. No changes in cellular and humoral immune response were observed under such conditions. These results suggest a development of immune response to activated antigen-nonspecific cells. In a model of chronic GvHD, donor immunization was shown to exert a protective effect, with regard of proteinuria dynamics in recipients, whereas immunization of recipients did not alter the GvHD dynamics. (Med. Immunol., 2011, vol. 13, N 1, pp 29-34

CYTOKINE PROFILE OF TH1- AND TH2-DEPENDENT VARIANTS OF CHRONIC GVHD

Abstract. Induction of chronic GVHD in the DBA/2→(C57Bl/6xDBA/2) F1 semi-allogeneic murine model results into development of Th1- and Th2-dependent immunopathological conditions that are characterized by different cytokine profiles. Chronic GVHD is accompanied by a sharp increase in IgE levels, thus presuming considerable IL-4 production. In recipients with Th2-dependent GvHD variant, elevated contents of serum IL-6, IL-7 and TNFα were also observed, which, along with other effects, may support polyclonal activation of B cells, thus leading to development of autoimmune pathology