a b s t r a c tIntroduction: Immunoregulation implies the activation of negative pathways leading to the modulation of specific immune responses. Co-inhibitory receptors (such as PD-1 and TIM-3) represent possible tools for this purpose. PD-1 and TIM-3 have been demonstrated to be present on immune cells suggesting general involvement in immunosuppression such as fetomaternal tolerance. The aim of our study was to investigate the expression pattern of PD-1, TIM-3, and its ligand Gal-9 on different immune cell subsets in the peripheral blood and at the fetomaternal interface in pregnant mice. Methods: TIM-3 and PD-1 expression by peripheral and decidual immune cells from pregnant BALB-c mice in 2 weeks of gestational age were measures by flow cytometry. Placental galectin-9 expression was determined by immunohistochemically and RT-PCR. Results: Gal-9 was found to be present in the spongiotrophoblast layer of the haemochorial placenta.Decidual NK, NKT and g/d T cells showed increased PD-1 expression and reduced cytotoxic potential when compared to the periphery. TIM-3 expression by NK cells and g/d T cells is similar both in the periphery and in the decidua, notably, their relative TIM-3 expression is increased locally which is associated with reduced lytic activity. Decidual NKT cells exhibit a reduced TIM-3 expression with increased relative receptor expression and a slightly increased cytotoxicity when compared to the periphery. Discussion: Our data reveals a particularly complex, tissue and cell type specific immunoregulatory mechanism by the investigated co-inhibitory receptors at the fetomaternal interface.

Altered frequency and reduced PD-1 expression combined together with the elevated perforin content of MAIT cells insinuate their potential roles in the pathogenesis of early-onset pre-eclampsia.

The programmed cell death protein 1 (PD-1) receptor has been reported to downregulate T cell activation effectively via binding to its ligands PD-L1 or PD-L2 in a negative co-stimulatory manner. Little is known about the involvement of PD-1 mediated immunoregulation in pregnancy and in pregnancy-related disorders. In this work, we investigated the possible role of the PD-1 co-stimulatory pathway in the pathogenesis of the clinical phase of early-onset preeclampsia characterized by a systemic maternal inflammatory response. We performed a cross-sectional study for comparative analysis of phenotypic and functional characteristics of peripheral blood mononuclear cells in women with early-onset preeclampsia and third-trimester healthy pregnant controls. According to our findings, enhanced expression of either PD-1 or its ligand PD-L1, or both, on the cell surface of effector cells (T cells, natural killer (NK) cells, natural killer T (NKT)-like cells) and Tregs could be observed, but PD-1 expression did not correlate with effector cells exhaustion. These results suggest the failure of the axis to downregulate Th1 responses, contributing thereby to the exaggerated immunoactivation observed in early-onset preeclampsia.

The only remarkable finding is the recruitment of Gal-9+ Th cells to the decidua promoting local immune homeostasis in PACAP KO mice, which nevertheless cannot explain the reduced fertility observed in these mice.

The abortifacient Mifepristone (RU486) has proven to be a safe, effective, acceptable option for millions of women seeking abortion during the first and second trimester of pregnancy although its precise mechanism of action is not well understood. The main objective of this study was to investigate the impact of low dose Mifepristone administration on placental Galectin-9 (Gal-9) expression, as well as its effect on the cell surface expression of Gal-9, TIM-3 and CD107a molecules by different T and NK cell subsets. A model of Mifepristone-induced immunological changes was established in syngeneic pregnant BALB/c mice. RU486-induced alteration in placental Gal-9 expression was determined by immunohistochemistry. For immunophenotypic analysis, mid-pregnancy decidual lymphocytes and peripheral mononuclear cells were obtained from Mifepristone treated and control mice at the 14.5 day of gestation. TIM-3 and Gal-9 expression by peripheral and decidual immune cells were examined by flow cytometry. Our results revealed a dramatically decreased intracellular Gal-9 expression in the spongiotrophoblast layer of the haemochorial placenta in Mifepristone treated pregnant mice. Although low dose RU486 treatment did not cause considerable change in the phenotypic distribution of decidual and peripheral immune cells, it altered the Gal-9 and TIM-3 expression by different NK and T cell subsets. In addition, the treatment significantly decreased the CD107a expression by decidual TIM-3+ NK cells, but increased its expression by decidual NKT cell compared to the peripheral counterparts. These findings suggest that low dose Mifepristone administration might induce immune alterations in both progesterone dependent and independent way.

Problem Pituitary adenylate cyclase‐activating polypeptide (PACAP) is a neuropeptide having several regulatory functions in the nervous system and in peripheral organs including those of the reproductive system. PACAP‐deficient male mice have several morphological, biochemical, behavioral defects and show disturbed signaling in spermatogenesis affecting fertility in PACAP KO mice. Reproductive functions such as fertility, mating, and maternal behaviors have been widely investigated, but no immune analyses are available regarding the testicular immune‐privileged environment in male PACAP‐deficient mice. Method of Study We performed detailed immunophenotyping of testicular immune cells and investigated the expression of TIM‐3 and PD‐1 Immune checkpoint molecules of immune cells together with the detection of galectin‐9 and perforin. We investigated the percentage of numerous immune cell populations in the testis of wild‐type and PACAP‐deficient mice. Results We demonstrated a significant increase in the frequency of testicular CD8+ T cells together with the decrease in Treg cell number obtained from PACAP KO mice compared with wild‐type mice. Investigating Immune checkpoint receptors, only PD‐1 showed a significantly decreased expression in CD8+ T cells in PACAP KO mice compared with wild‐type suggesting an impaired PD‐1/PD‐L1 pathway. Regarding TIM‐3 expression, we did not find any significant difference between the investigated groups. Conclusion We hypothesize that these local changes may result in an immune activation with disturbed testicular immunoregulation in PACAP KO mice; however, determining the exact function requires further investigations. Our data further support the view that besides a systemic immune tolerance, localized active immunosuppression is involved in the regulation of testicular immune privilege.

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