Search

Interleukin (IL)-25, also known as IL-17E, belongs to the IL-17 family of cytokines. Unlike other IL-17 family members, IL-25 promotes Th2-type immune responses, stimulating IL-4, IL-5, and IL-13 production. Here, we employed murine models of skin graft to explore the role of IL-25 in suppression of graft rejection. We found that IL-25 expression is increased during allograft rejection, and allograft rejection was enhanced in IL-25 KO mice. IL-25 KO was associated with down-regulation of Foxp3 expression in CD4+ T cells. Further, while adoptive transfer of WT regulatory T cells (Tregs) protected against allograft rejection, adoptive transfer of IL-25 deficient Tregs failed to protect against allograft rejection. Exogenous IL-25 restored Foxp3 expression and Treg function in vitro. Moreover, IL-25 promoted phosphorylation of NFAT2. Thus, IL-25 may enhance Treg function by up-regulating NFAT2 phosphorylation. Our findings suggest that IL-25 can sustain Foxp3 expression, enhance the suppressive function of Tregs, and prolong skin-graft survival. [ABSTRACT FROM AUTHOR]

Obliterative bronchiolitis (OB) remains the major limitations for the long-term survival of allografts after lung transplantation. Th17 cells and IL-17 have been recognized as mediators of the development of OB in both animal models and human beings. IL-25, also called IL-17E, is the only anti-inflammatory cytokine of the IL-17 family, capable of regulating Th17 cells function in autoimmune inflammations. Whether IL-25 affects Th17 cells responses and the development of OB remains poorly understood. Acute rejection (AR) of the lung allograft has been regarded as the main problem for the development of OB, in which infiltrations of monocytes/macrophages play important roles. This study explored the potential role of IL-25 in regulation of macrophages polarization and inhibition of IL-17 production in the progression of OB. Here, we showed that IL-25 directly suppressed the expression of inflammatory cytokines, such as IL-6, IL-23, TNF-α, and IL-1β in LPS-induced pro-inflammatory M1 macrophages in vitro. In vivo data demonstrated that IL-25 deficiency promoted the polarization and function of M1 macrophages and aggravated the progression of OB in murine models of both orthotopic and heterotopic trachea transplantation. In conclusion, these data indicated that IL-25 attenuated OB by suppressing the function of M1 macrophages and IL-17 expression, providing an alternative strategy to intervene the development of OB. [ABSTRACT FROM AUTHOR]

• The ACE activity and TGF-β1 expression were involved in diabetic retinopathy. • ACE enhanced the expression of total/activated TGF-β1 in rat RMCs and RCECs. • ACE exacerbated elevated damage to the barrier function in RCECs. • ACE damaged b lood- r etina b arrier by activating the TGF-β1/Smad signaling pathway. Diabetes mellitus (DM) is a systemic, chronic metabolic disease that is related to heredity and autoimmunity and is often accompanied by complications of retinopathy. However, the causative mechanism involved in the pathological process remains unclear. In this research, treatment with fosinopril or LY2109761 was found to be responsible for the improvement of the pathological processes, serum biochemical indexes and retinopathy in rats with streptozotocin-induced diabetes. In addition, the upregulation of angiotensin-converting enzyme (ACE) in the serum and the increased expression of TGF-β1 in the pathological outer nuclear layer (ONL) and inner nuclear layer (INL) of the retina were also reduced. In vitro experiments demonstrated that ACE enhanced cell damage and TGF-β1/Smad signaling pathway activation in retinal capillary endothelial cells (RCECs) under high glucose conditions. In addition, the activity of ACE was also considered to be related to the increasing levels of activated TGF-β1 in both rat retinal Müller cells (RMCs) and RCECs, but ACE activity had no effect on the high glucose-mediated upregulation of total TGF-β1 in RMCs. Coculture experiments with RCECs and RMCs showed that the barrier that was established under normal conditions was significantly impaired when exposed to high glucose combined with ACE, and damage of barrier can be prevented by adding fosinopril or LY2109761. Finally, a similar auxiliary effect of ACE was also observed in the activated TGF-β1-mediated barrier damage in blood-retinal barrier model in vitro. In summary, ACE-mediated TGF-β1/Smad signaling pathway activation was found to be involved in the destruction of the blood-retina barrier during diabetic retinopathy in a model of streptozotocin-induced diabetes, and these data may provide evidence to guide the treatment of the complications of diabetes mellitus. [ABSTRACT FROM AUTHOR]