Among several factors known to modulate embryo implantation and survival, uterine quiescence and neovascularization, maternal immunotolerance through the Th1/Th2 cytokine balance towards a Th2 profile, local regulatory T-cell (Treg) activation, and high levels of progesterone were assigned a prominent role. Vasoactive intestinal peptide (VIP) is a neuroimmunopeptide that has anti-inflammatory effects, promotes Th2 cytokines and CD4+CD25+FOXP3+ Treg activation, and stimulates exocrine secretion, smooth muscle relaxation, and vasodilatation favoring uterus quiescence. The goal of the present work was to explore the participation of VIP in the implantation sites of normal and pregnant prediabetic nonobese diabetic (NOD) females, a mouse strain that spontaneously develops an autoimmune exocrinopathy similar to Sjögren's syndrome. Our results indicate a reduction in litter size from the third parturition onwards in the NOD female lifespan with increased resorption rates. Progesterone systemic levels were significantly decreased in pregnant NOD mice compared with BALB/c mice, although the allogeneic response to progesterone by spleen cells was not impaired. VIP receptors, Vipr1 and Vipr2 (Vpac1 and Vpac2), were expressed at the implantation sites and VIP induced leukemia inhibitory factor (LIF) and Treg marker expression in both strains; however, a reduced Vip expression was found in NOD implantation sites. We conclude that the reduced birth rate at 16-week-old NOD mice with a Th1 systemic cytokine profile involves resorption processes with a lower expression of VIP at the sites of implantation, which acts as a local inducer of pro-implantatory LIF and Treg activation.
Valeria Roca, Mario Calafat, Luciana Larocca, Rosanna Ramhorst, Mariana Farina, Ana Maria Franchi and Claudia Pérez Leirós
Valeria Roca, Luciana Larocca, Mario Calafat, Julieta Aisemberg, Roberto Meiss, Ana M Franchi and Claudia Pérez Leirós
A functional interaction between progesterone, Th2 cytokines and a suitable balance between nitric oxide and prostaglandins in the uterus is considered to have a major role in the success of embryo implantation and pregnancy. Non-obese diabetic (NOD) mice offer a suitable model to study the modulatory role of Th1 cytokines on uterus signalling and function, since at the prediabetic stage they develop a spontaneous Th1 autoimmune response against exocrine glands similar to Sjögren’s syndrome. Vasoactive intestinal peptide (VIP) is a vasoactive neuro- and immunopeptide that promotes Th2 profiles and contributes to the smooth muscle relaxation and vasodilation. The aim of the present study was to investigate the activities of nitric oxide synthase and cyclo-oxygenase and the effect of VIP in the uterus of NOD mice with an emerging Th1 cytokine response. We present evidence of a reduced basal and VIP-stimulated activity of both enzymes in the uterus of NOD mice compared with normal BALB/c mice in proestrus. An altered functional interaction between both enzymes is also present in NOD mice at the time when increased levels of serum interleukin (IL)-12 and tumour necrosis factor-α but not interferon (IFN)-γ or IL-10 were detected. We conclude that signalling alterations in uteri of NOD mice are simultaneous to the onset of a systemic Th1 cytokine response.
Elizabeth Soczewski, Esteban Grasso, Lucila Gallino, Vanesa Hauk, Laura Fernández, Soledad Gori, Daniel Paparini, Claudia Perez Leirós and Rosanna Ramhorst
Decidualization denotes the reprogramming of endometrial stromal cells that includes the secretion of different mediators like cytokines, chemokines, and the selective recruitment of immune cells. This physiological process involves changes in the secretome of the endometrial stromal cells leading to the production of immunomodulatory factors. The increased amount of protein secretion is associated with a physiological endoplasmic reticulum (ER) stress and the resulting unfolded protein response (UPR), allowing the expansion of ER and the machinery to assist the protein folding. Notably, the signaling pathways involved in the ER stress and the UPR are interconnected with the onset of a sterile inflammatory response, as well as with angiogenesis. Both of these processes have a key role in decidualization and placentation, therefore, alterations in them could lead to pregnancy complications. In this review, we will discuss how the induction of ER stress and the UPR processes that accompanies the decidualization are associated with embryo implantation and whether they might condition pregnancy outcome. The ER stress activates/triggers sensing proteins which, among others, induces kinase/RNAse-TXNIP expression, activating the NLRP3 inflammasome. This multiprotein system allows caspase-1 activation, which catalyzes the cleavage of the inactive IL-1β proform toward the mature secretory form, with pro-implantatory effects. However, the sterile inflammatory response should be later controlled in favor of a tolerogenic microenvironment to sustain pregnancy. In accordance, alterations of the ER stress and UPR processes can be reflected in recurrent implantation failures (RIF), recurrent pregnancy loss (RPL), or complications associated with deficient placentation, such as preeclampsia (PE).