The “Three Amigos” lurking behind type 1 diabetes: Hygiene, gut microbiota and viruses

Incidence of type 1 diabetes (T1D) is on the rise and yet, despite decades of research, the exact ethology of the disease still remains a mystery. The autoimmune reaction, which ultimately leads to the destruction of pancreatic beta cells, causing insulin deficiency and T1D, is a result of genetic susceptibility and environmental factors. Precisely, what are these environmental factors? Current popular opinion implies these pathogens, such as viruses, especially human enteroviruses, are a triggering factor. On the other hand, the hygiene hypotheses states in which the increase of autoimmune diseases, such as T1D, can, in fact, be explained by the decrease of infections, and infectious agents, more like viruses, actually serve as a defense mechanism, therefore, protect us from developing certain autoimmune diseases. Additionally, the relationship between the gut microbiota and autoimmune diseases is currently gaining increased interest including relative research now demonstrating how the guts immune system plays a crucial role in the development of autoimmune diseases. This literature review aims to evaluate these three popular suspects: Viral infections, hygiene and gut microbiota, in relation to their potential triggering effect on T1D and their close relationship to one another

Immune Checkpoint Molecules in Reproductive Immunology

Immune checkpoint molecules, like CTLA-4, TIM-3, PD-1, are negative regulators of immune responses to avoid immune injury. Checkpoint regulators are thought to actively participate in the immune defense of infections, prevention of autoimmunity, transplantation, and tumor immune evasion. Maternal-fetal immunotolerance represents a real immunological challenge for the immune system of the mother: beside acceptance of the semiallogeneic fetus, the maternal immune system has to be prepared for immune defense mostly against infections. In this particular situation, the role of immune checkpoint molecules could be of special interest. In this review, we describe current knowledge on the role of immune checkpoint molecules in reproductive immunology

The Role of Type I and Type II NKT Cells in Materno-Fetal Immunity

NKT cells represent a small but significant immune cell population as being a part of and bridging innate and adaptive immunity. Their ability to exert strong immune responses via cytotoxicity and cytokine secretion makes them significant immune effectors. Since pregnancy requires unconventional maternal immunity with a tolerogenic phenotype, investigation of the possible role of NKT cells in materno-fetal immune tolerance mechanisms is of particular importance. This review aims to summarize and organize the findings of previous studies in this field. Data and information about NKT cells from mice and humans will be presented, focusing on NKT cells characteristics during normal pregnancy in the periphery and at the materno-fetal interface and their possible involvement in female reproductive failure and pregnancy complications with an immunological background

Medawar’s post era: Galectins emerged as key players during fetal-maternal glycoimmune adaptation

Lectin-glycan interactions, in particular those mediated by the galectin family, regulate many processes required for a successful pregnancy. Over the past decades, increasing evidence gathered from in vitro and in vivo experiments indicate that members of the galectin family specifically bind to both intracellular and membrane bound carbohydrate ligands regulating angiogenesis, immune-cell adaptations required to tolerate the fetal semi-allograft and mammalian embryogenesis. Therefore, galectins play important roles in fetal development and placentation contributing to maternal and fetal health. This review discusses the expression and role of galectins during the course of pregnancy, with an emphasis on maternal immune adaptions and galectin-glycan interactions uncovered in the recent years. In addition, we summarize the galectin fingerprints associated with pathological gestation with particular focus on preeclampsia

Examination of the TIGIT, CD226, CD112, and CD155 Immune Checkpoint Molecules in Peripheral Blood Mononuclear Cells in Women Diagnosed with Early-Onset Preeclampsia

Early-onset preeclampsia is a common obstetrical disease with a potential genetic back- ground and is characterized by the predominance of Th1 immune response. However, although many studies investigated the immunological environment in preeclamptic patients, no information is available about the potential role of the TIGIT/CD226/CD112/CD155 immune checkpoint pathway. A total of 37 pregnant women diagnosed with early-onset preeclampsia and 36 control women with appropriately matched gestational age were enrolled in this study. From venous blood, mononu- clear cells were isolated and stored in the freezer. Using multicolor flow cytometry T-, NK cell and monocyte subpopulations were determined. After characterization of the immune cell subsets, TIGIT, CD226, CD112, and CD155 surface expression and intracellular granzyme B content were determined by flow cytometer. Significantly decreased CD226 expression and increased CD112 and CD155 sur- face expression were detected in almost all investigated T-cell, NK cell, and monocyte subpopulations in women diagnosed with preeclampsia compared to the healthy group. Furthermore, reduced TIGIT and granzyme B expression were measured only in preeclamptic CD8+ T cells compared to healthy pregnant women. A decreased level of the activatory receptor CD226 in effector lymphocytes accompanied with an elevated surface presence of the CD112 and CD155 ligands in monocytes could promote the TIGIT/CD112 and/or TIGIT/CD155 ligation, which mediates inhibitory signals. We assume that the inhibition of the immune response via this immune checkpoint pathway might contribute to compensate for the Th1 predominance during early-onset preeclampsia

Peripartum Investigation of Red Blood Cell Properties in Women Diagnosed with Early-Onset Preeclampsia

We investigated peripartum maternal red blood cell (RBC) properties in early-onset preeclampsia (PE). Repeated blood samples were taken prospectively for hemorheological measurements at PE diagnosis (n = 13) or during 26–34 weeks of gestation in healthy pregnancies (n = 24), then at delivery, and 72 h postpartum. RBC aggregation was characterized by M index (infrared light transmission between the aggregated RBCs in stasis) and aggregation index (AI—laser backscattering from the RBC aggregates). We observed significantly elevated RBC aggregation (M index = 9.8 vs. 8.5; AI = 72.9% vs. 67.5%; p < 0.001) and reduced RBC deformability in PE (p < 0.05). A positive linear relationship was observed between AI and gestational age at birth in PE by regression analysis (R 2 = 0.554; p = 0.006). ROC analysis of AI showed an AUC of 0.84 (0.68–0.99) (p = 0.001) for PE and indicated a cutoff of 69.4% (sensitivity = 83.3%; specificity = 62.5%), while M values showed an AUC of 0.75 (0.58–0.92) (p = 0.019) and indicated a cutoff of 8.39 (sensitivity = 90.9% and specificity = 50%). The predicted probabilities from the combination of AI and M variables showed increased AUC = 0.90 (0.79–1.00) (p < 0.001). Our results established impaired microcirculation in early-onset PE manifesting as deteriorated maternal RBC properties. The longer the pathologic pregnancy persists, the more pronounced the maternal erythrocyte aggregation. AI and M index could help in the prognostication of early-onset PE, but further investigations are warranted to confirm the prognostic role before the onset of symptoms

The importance of the PD-1/PD-L1 pathway at the maternal-fetal interface

Abstract Background Our goal with this study was to investigate the contribution of PD-1/PD-L1 immune-checkpoint pathway to maternal immunotolerance mechanisms. Methods Thirteen healthy pregnant women and 10 non-pregnant controls were involved in this project. PBMCs and DICs were isolated from peripheral blood and from decidual tissues. After the characterization of different immune cell subsets, we used fluorochrome-conjugated monoclonal antibodies to measure the expression level of PD-1, PD-L1, NKG2D, and CD107a molecules by flow cytometry. Results We measured significant alternations in the proportion of decidual immune cell subsets compared to the periphery. Elevated PD-1 expression by decidual CD8+ T, CD4+ T, and NKT-like cells were also detected accompanied by the increased PD-L1 expression by decidual CD4+ T, Treg, NKT-like and CD56 + NK cell subsets compared to peripheral blood. The cytotoxic potential was significantly higher in PD-1- decidual immune cells compared to the periphery, however we measured a significantly lower cytotoxicity in the decidual PD-1+ CD8+ T cells compared with the peripheral subsets. An activation receptor NKG2D expression was decreased by the PD-1+ CD8+ T subsets in the first trimester compared to non-pregnant condition but the expression level of the decidual counterparts was significantly elevated compared to the periphery. The cytotoxic potential of decidual PD1/NKG2D double positive CD8+ T cells was significantly decreased compared to the peripheral subsets. Conclusions Based on our results we assume that PD-1/PD-L1 pathway might have a novel role in the maintaining of the local immunological environment. Accompanied by NKG2D activating receptor this checkpoint interaction could regulate decidual CD8 Tc cell subsets and may contribute maternal immunotolerance