Peripheral Tolerance Research Articles

The elevated expression of LAG-3 on CD8+T cells correlates with disease severity of pulmonary TB

ObjectiveLymphocyte-activation gene 3 (LAG-3) plays an important role in regulating T-cell responses and inducing peripheral tolerance. Our aim in this study was to investigate the relationship between LAG-3 and active tuberculosis (ATB) and the impact of LAG-3 blockade on CD8+T cells. MethodsFlow cytometry was used to detect the expression of LAG-3 on CD4+T and CD8+T cells in the peripheral blood and bronchoalveolar lavage fluid from ATB patients and to explore the relationship between LAG-3 and ATB. ResultsThe expression of LAG-3 on CD4+T and CD8+T cells in ATB patients was increased (P < 0.001), and CD8+T cells with high expression of LAG-3 were associated with sputum culture results (P < 0.05). We further analyzed the relationship between the expression of LAG-3 in CD8+T cells and the severity of tuberculosis and found that the expression of LAG-3 on CD8+T cells in smear-positive tuberculosis patients was significantly higher than that in sputum smear-negative tuberculosis patients (P < 0.05). LAG-3 expression on CD8+T cells was negatively correlated with the presence of lung lesions (P < 0.05). After stimulation with a tuberculosis-specific antigen, the expression of LAG-3 on tuberculosis-specific CD8+T cells was also upregulated, and LAG-3-expressing CD8+T cells showed reduced production of IFN-γ, decreased activation, and lower proliferation, while the function of CD8+T cells was restored when LAG-3 signaling was blocked. ConclusionsThis study further explored the relationship between immune exhaustion caused by LAG-3 and immune escape of Mycobacterium tuberculosis and revealed that the elevated expression of LAG-3 on CD8+T cells correlates with functional defects of CD8+T cells and the severity of pulmonary TB.

Spontaneous development of an autoimmune hepatitis - primary biliary cholangitis overlap syndrome in dnTGFβRII Aire-/- mice.

Autoimmune regulator (Aire) and TGF-β signaling play important roles in central tolerance and peripheral tolerance, respectively, by eliminating or suppressing the activity of autoreactive T cells. We previously demonstrated that dnTGFβRII mice develop a defect in peripheral tolerance and a primary biliary cholangitis (PBC)-like disease. We hypothesized that by introducing the Aire gene to this model, we would observe a more severe PBC phenotype. Interestingly, however, we demonstrated that, while dnTGFβRII Aire-/- mice do manifest key histological and serological features of autoimmune cholangitis, they also develop mild to moderate interface hepatitis and show high levels of alanine transaminase (ALT) and antinuclear antibodies (ANA), characteristics of autoimmune hepatitis (AIH). To further understand this unique phenotype, we performed RNA sequencing (RNA-seq) and flow cytometry to explore the functional pathways and immune cell pathways in the liver of dnTGFβRII Aire-/- mice. Our data revealed enrichments of programmed cell death pathways and predominant CD8+ T cell infiltrates. Depleting CD8+ T cells using an anti-CD8α antibody significantly alleviated hepatic inflammation and prolonged the life span of these mice. Finally, RNA-seq data indicated the clonal expansion of hepatic CD8+ T cells. In conclusion, these mice developed an autoreactive CD8+ T-cell-mediated autoimmune cholangitis with concurrent hepatitis that exhibited key histological and serological features of the AIH-PBC overlap syndrome, representing a novel model for the study of tolerance and autoimmune liver disease. © 2023 The Pathological Society of Great Britain and Ireland.

The Role of LFA-1 for the Differentiation and Function of Regulatory T Cells-Lessons Learned from Different Transgenic Mouse Models.

Regulatory T cells (Treg) are essential for the maintenance of peripheral tolerance. Treg dysfunction results in diverse inflammatory and autoimmune diseases with life-threatening consequences. β2-integrins (CD11a-d/CD18) play important roles in the migration of leukocytes into inflamed tissues and cell signaling. Of all β2-integrins, T cells, including Treg, only express CD11a/CD18, termed lymphocyte function-associated antigen 1 (LFA-1), on their surface. In humans, loss-of-function mutations in the common subunit CD18 result in leukocyte adhesion deficiency type-1 (LAD-1). Clinical symptoms vary depending on the extent of residual β2-integrin function, and patients may experience leukocytosis and recurrent infections. Some patients can develop autoimmune diseases, but the immune processes underlying the paradoxical situation of immune deficiency and autoimmunity have been scarcely investigated. To understand this complex phenotype, different transgenic mouse strains with a constitutive knockout of β2-integrins have been established. However, since a constitutive knockout affects all leukocytes and may limit the validity of studies focusing on their cell type-specific role, we established a Treg-specific CD18-floxed mouse strain. This mini-review aims to delineate the role of LFA-1 for the induction, maintenance, and regulatory function of Treg in vitro and in vivo as deduced from observations using the various β2-integrin-deficient mouse models.

Coevolutionary analysis of Forkhead box protein P3 and its physical binary interactors E3 ubiquitin-protein ligase CHIP, Zfp-90, and nuclear receptor ROR-α.

Forkhead box protein P3 (FOXP3) is known to orchestrate the development and maintenance of T regulatory cells, a cell population specialized in immune suppression and peripheral immune tolerance. FOXP3 activity is fine-tuned through its interaction with several protein-binding partners. By using IntAct database, we retrieved three physical binary interactors: E3 ubiquitin-protein ligase CHIP, Zfp-90, and nuclear receptor ROR-α. Coevolution clusters between FOXP3 and its interactors were identified with the use of iBIS2 algorithm, the iterative version of BIS/BIS2. Most of the coevolving pairs came from some species of monotremes and marsupials, as well as from a group of bats, thus suggesting that protein interactions of FOXP3 with its partners may be changed and/or modulated during mammalian speciation. Furthermore, our analysis would suggest the occurrence of a determinant role of FOXP3 in suppressing pregnancy alloreactions in placental mammals. Similarly, FOXP3, through its interaction with different protein interaction mechanisms, would explain the unique control of inflammatory response to infections in bats. By identifying several inter-protein clusters between the different protein pairs, our findings may provide a guide for new therapeutic approaches to modulate T regulatory suppression and/or enhance immune tolerance.

Induced pluripotent stem cell-derived dendritic cell vaccine therapy genetically modified on the ubiquitin-proteasome system.

We previously reported that dendritic cells (DCs) transduced with the full-length tumor-associated antigen (TAA) gene induced TAA-specific cytotoxic T lymphocytes (CTLs) to elicit antitumor responses. To overcome the issue of quantity and quality of DCs required for DC vaccine therapy, we focused on induced pluripotent stem cells (iPSCs) as a new tool for obtaining DCs and reported efficacy of iPSCs-derived DCs (iPSDCs). However, in clinical application of iPSDC vaccine therapy, further enhancement of the antitumor effect is necessary. In this study, we targeted mesothelin (MSLN) as a potentially useful TAA, and focused on the ubiquitin-proteasome system to enhance antigen-presenting ability of iPSDCs. The CTLs induced by iPSDCs transduced with MSLN gene (iPSDCs-MSLN) from healthy donors showed cytotoxic activity against autologous lymphoblastoid cells (LCLs) expressing MSLN (LCLs-MSLN). The CTLs induced by iPSDCs transduced ubiquitin-MSLN fusion gene exhibited higher cytotoxic activity against LCLs-MSLN than the CTLs induced by iPSDCs-MSLN. The current study was designed that peripheral T-cell tolerance to MSLN could be overcome by the immunization of genetically modified iPSDCs simultaneously expressing ubiquitin and MSLN, leading to a strong cytotoxicity against tumors endogenously expressing MSLN. Therefore, this strategy may be promising for clinical application as an effective cancer vaccine therapy.

CLL stereotyped B-cell receptor immunoglobulin sequences are recurrent in the B-cell repertoire of healthy individuals: Apparent lack of central and early peripheral tolerance censoring.

The leukemic cells of patients with chronic lymphocytic leukemia (CLL) are often unique, expressing remarkably similar IGHV-IGHD-IGHJ gene rearrangements, "stereotyped BCRs". The B-cell receptors (BCRs) on CLL cells are also distinctive in often deriving from autoreactive B lymphocytes, leading to the assumption of a defect in immune tolerance. Using bulk and single-cell immunoglobulin heavy and light chain variable domain sequencing, we enumerated CLL stereotype-like IGHV-IGHD-IGHJ sequences (CLL-SLS) in B cells from cord blood (CB) and adult peripheral blood (PBMC) and bone marrow (BM of healthy donors. CLL-SLS were found at similar frequencies among CB, BM, and PBMC, suggesting that age does not influence CLL-SLS levels. Moreover, the frequencies of CLL-SLS did not differ among B lymphocytes in the BM at early stages of development, and only re-circulating marginal zone B cells contained significantly higher CLL-SLS frequencies than other mature B-cell subpopulations. Although we identified CLL-SLS corresponding to most of the CLL major stereotyped subsets, CLL-SLS frequencies did not correlate with those found in patients. Interestingly, in CB samples, half of the CLL-SLS identified were attributed to two IGHV-mutated subsets. We also found satellite CLL-SLS among the same normal samples, and they were also enriched in naïve B cells but unexpectedly, these were ~10-fold higher than standard CLL-SLS. In general, IGHV-mutated CLL-SLS subsets were enriched among antigen-experienced B-cell subpopulations, and IGHV-unmutated CLL-SLS were found mostly in antigen-inexperienced B cells. Nevertheless, CLL-SLS with an IGHV-mutation status matching that of CLL clones varied among the normal B-cell subpopulations, suggesting that specific CLL-SLS could originate from distinct subpopulations of normal B cells. Lastly, using single-cell DNA sequencing, we identified paired IGH and IGL rearrangements in normal B lymphocytes resembling those of stereotyped BCRs in CLL, although some differed from those in patients based on IG isotype or somatic mutation. CLL-SLS are present in normal B-lymphocyte populations at all stages of development. Thus, despite their autoreactive profile they are not deleted by central tolerance mechanisms, possibly because the level of autoreactivity is not registered as dangerous by deletion mechanisms or because editing of L-chain variable genes occurred which our experimental approach could not identify.

IFNγ-induction of TH1-like regulatory T cells controls antiviral responses.

Regulatory T (Treg) cells are an immunosuppressive population that are required to maintain peripheral tolerance and prevent tissue damage from immunopathology, via anti-inflammatory cytokines, inhibitor receptors and metabolic disruption. Here we show that Treg cells acquire an effector-like state, yet remain stable and functional, when exposed to interferon gamma (IFNγ) during infection with lymphocytic choriomeningitis and influenza A virus. Treg cell-restricted deletion of the IFNγ receptor (encoded by Ifngr1), but not the interleukin 12 (IL12) receptor (encoded by Il12rb2), prevented TH1-like polarization (decreased expression of T-bet, CXC motif chemokine receptor 3 and IFNγ) and promoted TH2-like polarization (increased expression of GATA-3, CCR4 and IL4). TH1-like Treg cells limited CD8+ T cell effector function, proliferation and memory formation during acute and chronic infection. These findings provide fundamental insights into how Treg cells sense inflammatory cues from the environment (such as IFNγ) during viral infection to provide guidance to the effector immune response. This regulatory circuit prevents prolonged immunoinflammatory responses and shapes the quality and quantity of the memory T cell response.

A single-amino acid substitution in the adaptor LAT accelerates TCR proofreading kinetics and alters T-cell selection, maintenance and function

Mature T cells must discriminate between brief interactions with self-peptides and prolonged binding to agonists. The kinetic proofreading model posits that certain T-cell antigen receptor signaling nodes serve as molecular timers to facilitate such discrimination. However, the physiological significance of this regulatory mechanism and the pathological consequences of disrupting it are unknown. Here we report that accelerating the normally slow phosphorylation of the linker for activation of T cells (LAT) residue Y136 by introducing an adjacent Gly135Asp alteration (LATG135D) disrupts ligand discrimination in vivo. The enhanced self-reactivity of LATG135D T cells triggers excessive thymic negative selection and promotes T-cell anergy. During Listeria infection, LATG135D T cells expand more than wild-type counterparts in response to very weak stimuli but display an imbalance between effector and memory responses. Moreover, despite their enhanced engagement of central and peripheral tolerance mechanisms, mice bearing LATG135D show features associated with autoimmunity and immunopathology. Our data reveal the importance of kinetic proofreading in balancing tolerance and immunity.

Aryl hydrocarbon receptor activity downstream of IL-10 signaling is required to promote regulatory functions in human dendritic cells

Interleukin (IL)-10 is a main player in peripheral immune tolerance, the physiological mechanism preventing immune reactions to self/harmless antigens. Here, we investigate IL-10-induced molecular mechanisms generating tolerogenic dendritic cells (tolDC) from monocytes. Using genomic studies, we show that IL-10 induces a pattern of accessible enhancers exploited by aryl hydrocarbon receptor (AHR) to promote expression of a set of core genes. We demonstrate that AHR activity occurs downstream of IL-10 signaling in myeloid cells and is required for the induction of tolerogenic activities in DC. Analyses of circulating DCs show that IL-10/AHR genomic signature is active invivo in health. In multiple sclerosis patients, we instead observe significantly altered signature correlating with functional defects and reduced frequencies of IL-10-induced-tolDC invitro and invivo. Our studies identify molecular mechanisms controlling tolerogenic activities in human myeloid cells and may help in designing therapies to re-establish immune tolerance.

Long-term persistence and functionality of adoptively transferred antigen-specific T cells with genetically ablated PD-1 expression

Engagement of the inhibitory T cell receptor programmed cell death protein 1 (PD-1) associates with dysfunctional states of pathogen- or tumor-specific T cells. Accordingly, systemic antibody-mediated blockade of PD-1 has become a central target for immunotherapies but is also associated with severe toxicities due to loss of peripheral tolerance. Therefore, selective ablation of PD-1 expression on adoptively transferred T cells through direct genetic knockout (KO) is currently being explored as an alternative therapeutic approach. However, since PD-1 might also be required for the regulation of physiological T cell function and differentiation, the suitability of PD-1 as an engineering target is controversial. In this study, we systematically investigated the maintenance of T cell functionality after CRISPR/Cas9-mediated PD-1 KO invivo during and after acute and chronic antigen encounter. Under all tested conditions, PD-1 ablation preserved the persistence, differentiation, and memory formation of adoptively transferred receptor transgenic T cells. Functional PD-1 KO T cells expressing chimeric antigen receptors (CARs) targeting CD19 could be robustly detected for over 390 d in a syngeneic immunocompetent mouse model, in which constant antigen exposure was provided by continuous B cell renewal, representing the longest invivo follow-up of CAR-T cells described to date. PD-1 KO CAR-T cells showed no evidence for malignant transformation during the entire observation period. Our data demonstrate that genetic ablation of PD-1 does not impair functionality and longevity of adoptively transferred T cells per se and therefore may be pursued more generally in engineered T cell-based immunotherapy to overcome a central immunosuppressive axis.

PCSK9 Inhibitors in Cancer Patients Treated with Immune-Checkpoint Inhibitors to Reduce Cardiovascular Events: New Frontiers in Cardioncology

Cancer patients treated with immune checkpoint inhibitors (ICIs) are exposed to a high risk of atherosclerosis and cardiometabolic diseases due to systemic inflammatory conditions and immune-related atheroma destabilization. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key protein involved in metabolism of low-density lipoprotein (LDL) cholesterol. PCSK9 blocking agents are clinically available and involve monoclonal antibodies, and SiRNA reduces LDL levels in high-risk patients and atherosclerotic cardiovascular disease events in multiple patient cohorts. Moreover, PCSK9 induces peripheral immune tolerance (inhibition of cancer cell- immune recognition), reduces cardiac mitochondrial metabolism, and enhances cancer cell survival. The present review summarizes the potential benefits of PCSK9 inhibition through selective blocking antibodies and siRNA in patients with cancer, especially in those treated with ICIs therapies, in order to reduce atherosclerotic cardiovascular events and potentially improve ICIs-related anticancer functions.

Autoantibody repertoire characterization provides insight into the pathogenesis of monogenic and polygenic autoimmune diseases.

Autoimmune diseases vary in the magnitude and diversity of autoantibody profiles, and these differences may be a consequence of different types of breaks in tolerance. Here, we compared the disparate autoimmune diseases autoimmune polyendocrinopathy-candidiasis-ecto-dermal dystrophy (APECED), systemic lupus erythematosus (SLE), and Sjogren's syndrome (SjS) to gain insight into the etiology of breaks in tolerance triggering autoimmunity. APECED was chosen as a prototypical monogenic disease with organ-specific pathology while SjS and SLE represent polygenic autoimmunity with focal or systemic disease. Using protein microarrays for autoantibody profiling, we found that APECED patients develop a focused but highly reactive set of shared mostly anti-cytokine antibodies, while SLE patients develop broad and less expanded autoantibody repertoires against mostly intracellular autoantigens. SjS patients had few autoantibody specificities with the highest shared reactivities observed against Ro-52 and La. RNA-seq B-cell receptor analysis revealed that APECED samples have fewer, but highly expanded, clonotypes compared with SLE samples containing a diverse, but less clonally expanded, B-cell receptor repertoire. Based on these data, we propose a model whereby the presence of autoreactive T-cells in APECED allows T-dependent B-cell responses against autoantigens, while SLE is driven by breaks in peripheral B-cell tolerance and extrafollicular B-cell activation. These results highlight differences in the autoimmunity observed in several monogenic and polygenic disorders and may be generalizable to other autoimmune diseases.

Sodium perturbs mitochondrial respiration and induces dysfunctional Tregs

FOXP3+ regulatory Tcells (Tregs) are central for peripheral tolerance, and their deregulation is associated with autoimmunity. Dysfunctional autoimmune Tregs display pro-inflammatory features and altered mitochondrial metabolism, but contributing factors remain elusive. High salt (HS) has been identified to alter immune function and to promote autoimmunity. By investigating longitudinal transcriptional changes of human Tregs, we identified that HS induces metabolic reprogramming, recapitulating features of autoimmune Tregs. Mechanistically, extracellular HS raises intracellular Na+, perturbing mitochondrial respiration by interfering with the electron transport chain (ETC). Metabolic disturbance by a temporary HS encounter or complex III blockade rapidly induces a pro-inflammatory signature and FOXP3 downregulation, leading to long-term dysfunction invitro and invivo. The HS-induced effect could be reversed by inhibition of mitochondrial Na+/Ca2+ exchanger (NCLX). Our results indicate that salt could contribute to metabolic reprogramming and that short-term HS encounter perturb metabolic fitness and long-term function of human Tregs with important implications for autoimmunity.

P074 Interferon-γ promotes antigen processing and presentation pathway in the intestinal epithelium of patients with Crohn’s disease

Abstract Background Interferon-γ (IFN-γ) is a major driver of excessive immune response, leading to intestinal mucosal damage and contributing the pathogenesis of Crohn’s diseases (CD). In contrast to the inflammatory cells and immune system, IFN-γ-induced cellular responses has not been well documented in the intestinal epithelium. The intestinal epithelium consists of multiple cell types and patient-derived intestinal organoid model may be appropriate to evaluate the IFN-γ-induced epithelial cellular responses in patients with CD. Methods To evaluate the IFN-γ-mediated epithelial cellular responses, human small intestinal organoids (enteroids) derived from the controls (n=6) and patients with Crohn’s disease (CD, n=10) were constructed. We focused on the IFN-γ-induced cell death mechanism upregulated in CD enteroids and validated them in surgically resected small intestine in patients with active CD. Results As the concentration of IFN-γ increased in the culture medium, the organoid-forming efficiency decreased steadily, which did not differ between control and CD enteroids. The enteroid viability measured using MTT was estimated to be 83.10 pg/ml for EC50. In control and CD enteroids treated with 100 pg/ml IFN-γ, PANoptosis was the main inflammatory cell death mechanism. Bulk and single-cell RNA sequencing revealed that IFN-γ induced the expression of MHC class II-associated genes, co-inhibitory molecule CD274 (PD-L1), and IDO1 in control and CD enteroids, which may be associated with peripheral tolerance in the absence of exogenous antigens. Gene set enrichment analysis identified an up-regulated antigen processing and presentation pathway with increased expression of MHC class I molecules in IFN-γ-treated CD enteroids compared to IFN-γ-treated control enteroids (normalized enrichment score=2.13, p=0.002, q=0.005). IFN-γ-induced MHC class I pathway could result in T cell-mediated cytotoxicity in CD enteroids. The selective JAK1 inhibitor, upadacitinib, inhibited the IFN-γ-induced PANoptosis and T cell-mediated cytotoxicity in CD enteroids. The expression of HLA-A and B was higher in the inflamed small intestine in patients with CD than those in patients with ischemic enteritis. Conclusion IFN-γ promotes antigen processing and presentation pathway in the intestinal epithelium. In patients with CD, increased expression of MHC class I molecules may induce T cell-mediated cytotoxicity, which could contribute to the development of CD.

Clinical adoptive regulatory T Cell therapy: State of the art, challenges, and prospective.

Rejection of solid organ transplant and graft versus host disease (GvHD) continue to be challenging in post transplantation management. The introduction of calcineurin inhibitors dramatically improved recipients' short-term prognosis. However, long-term clinical outlook remains poor, moreover, the lifelong dependency on these toxic drugs leads to chronic deterioration of graft function, in particular the renal function, infections and de-novo malignancies. These observations led investigators to identify alternative therapeutic options to promote long-term graft survival, which could be used concomitantly, but preferably, replace pharmacologic immunosuppression as standard of care. Adoptive T cell (ATC) therapy has evolved as one of the most promising approaches in regenerative medicine in the recent years. A range of cell types with disparate immunoregulatory and regenerative properties are actively being investigated as potential therapeutic agents for specific transplant rejection, autoimmunity or injury-related indications. A significant body of data from preclinical models pointed to efficacy of cellular therapies. Significantly, early clinical trial observations have confirmed safety and tolerability, and yielded promising data in support of efficacy of the cellular therapeutics. The first class of these therapeutic agents commonly referred to as advanced therapy medicinal products have been approved and are now available for clinical use. Specifically, clinical trials have supported the utility of CD4+CD25+FOXP3+ regulatory T cells (Tregs) to minimize unwanted or overshooting immune responses and reduce the level of pharmacological immunosuppression in transplant recipients. Tregs are recognized as the principal orchestrators of maintaining peripheral tolerance, thereby blocking excessive immune responses and prevent autoimmunity. Here, we summarize rationale for the adoptive Treg therapy, challenges in manufacturing and clinical experiences with this novel living drug and outline future perspectives of its use in transplantation.

C-terminal citrullinated peptide alters antigen-specific APC:T cell interactions leading to breach of immune tolerance

In rheumatoid arthritis, the emergence of anti-citrullinated autoimmunity is associated with HLA-antigen-T cell receptor complexes. The precise mechanisms underpinning this breach of tolerance are not well understood. Porphyromonas gingivalis expresses an enzyme capable of non-endogenous C-terminal citrullination with potential to generate citrullinated autoantigens. Here we document how C-terminal citrullination of ovalbumin peptide323-339 alters the interaction between antigen-presenting cells and OTII T cells to induce functional changes in responding T cells. These data reveal that C-terminal citrullination is sufficient to breach T cell peripheral tolerance in vivo and reveal the potential of C-terminal citrullination to lower the threshold for T cell activation. Finally, we demonstrate a role for the IL-2/STAT5/CD25 signalling axis in breach of tolerance. Together, our data identify a tractable mechanism and targetable pathways underpinning breach of tolerance in rheumatoid arthritis and provide new conceptual insight into the origins of anti-citrullinated autoimmunity.

Regulatory T cells suppress CD4+ effector T cell activation by controlling protein synthesis.

Regulatory T cells (Tregs) suppress the activation and subsequent effector functions of CD4 effector T cells (Teffs). However, molecular mechanisms that enforce Treg-mediated suppression in CD4 Teff are unclear. We found that Tregs suppressed activation-induced global protein synthesis in CD4 Teffs prior to cell division. We analyzed genome-wide changes in the transcriptome and translatome of activated CD4 Teffs. We show that mRNAs encoding for the protein synthesis machinery are regulated at the level of translation in activated CD4 Teffs by Tregs. Tregs suppressed global protein synthesis of CD4 Teffs by specifically inhibiting mRNAs of the translation machinery at the level of mTORC1-mediated translation control through concerted action of immunosuppressive cytokines IL-10 and TGFβ. Lastly, we found that the therapeutic targeting of protein synthesis with the RNA helicase eIF4A inhibitor rocaglamide A can alleviate inflammatory CD4 Teff activation caused by acute Treg depletion in vivo. These data show that peripheral tolerance is enforced by Tregs through mRNA translational control in CD4 Teffs.

T regulatory Function and Modification for Future Application

T regulatory cell is a very particular type of T cell that plays an important role in maintaining homeostasis and peripheral tolerance. The Treg (T regulatory cell) is a CD4+ T cell that has many mechanisms to create immune tolerance by effecting B and T cells. They are important for the control of tumour immunity, micro biome, organ transplants, allergy and of course self-tolerance. There are also times where Tregs fail to create tolerance whether by the decrease in population, no recognition of certain antigens (Inheritance) and also many other reasons such as environmental (theory that our immune system exposed to less pathogens in the modern cities so our immune system starts to react against our own antigens, potential reason for the increase in allergy) but not enough scientific evidence is provided yet. The fail in immune tolerance can result in auto-immune disease such as apoptotic dermatitis and DT1 (diabetes type 1). Research about cell and non-cell therapies are being researched and undergoing in clinical trials potentially cure or control autoimmune diseases as well as increase the success rates for organ transplant etc., by modifying Tregs.

Галектин-9/Tim-3-зависимый механизм регуляции функциональной активности натуральных киллеров при беременности

Galectins are a family of β-galactoside-binding low molecular weight proteins (lectins) homologous in the amino acid sequence of the carbohydrate-binding site. Galectins interact with glycans on the cell surface and are involved in regulating the functional activity of most cells of the human body. Galectin-9 plays a crucial role in controlling the functions of cells of the immune system. Of particular importance are the immunoregulatory effects of galectin-9 during pregnancy, when its production by trophoblast cells increases significantly, which is associated with the formation of peripheral immune tolerance. The main ligand for galectin-9 is the Tim-3 (T-cell immunoglobulin and mucin domain 3) molecule, whose high expression is detected on natural killers (NK cells). During pregnancy, the phenotype and functions of NK cells change significantly, which is necessary to prevent cytotoxic reactions to fetal cells. The review systematizes data on the role of galectin-9 in Tim-3-mediated regulation of NK cell functions in the aspect of pregnancy. The study of the regulation of the functional activity of NK cells is necessary to increase the effectiveness of NK cell therapy.

EXPERIMENTAL GESTATIONAL DIABETES DISRUPTS THE FORMATION OF IMMUNE TOLERANCE IN OFFSPRING.

The aim: To analyze the mRNA gene expression level of Aire, Deaf1, Foxp3, Ctla4, Il10, Nlrp3 and distribution of NLRP3+-cells in mesenteric lymph nodes (MLNs) of the offspring of rats with GD, both untreated and treated with glibenclamide and in conditions of insulin oral tolerance formation. Materials and methods: The study involves 160 male rats, one- or six-month-old. The mRNA genes expression was studied by real time quantitative poly¬merase chain reaction. Structure of Nlrp3+ -cells population was studied by histological sections of MLNs. Results: We observed AIRE gene repression, reduced mRNA levels of Deaf1 and the transcription factor Foxp3 in offspring of rats with GD. This was accompanied by inhibition of IL-10 gene expression and negative costimulatory molecules Ctla4. The development of the experimental GD was accompanied by transcrip¬tional induction of the Nlrp3 gene in MLNs of descendants. The administration of glibenclamide to pregnant female rats with GD inhibited the transcription of the Nlrp3 gene only in one-month-old offspring (5.3-fold) and did not change it in six-month-old animals. In offspring of rats with GD, the density of the NLRP3+-lymphocyte population in the MLNs increased, more pronounced in one-month-old animals. The administration of glibenclamide to pregnant rats with GD reduced the number of NLRP3+ -lymphocytes only in one-month-old offspring (by 33.0 %), whereas this index in six month-old offspring even increased. Conclusions: Experimental prenatal hyperglycemia leads to increased proinflammatory signaling and violation of peripheral immunological tolerance formation more pronounced at one month of life.