Qingshu Meng

The Critical Role of Induced CD4+ FoxP3+ Regulatory Cells in Suppression of Interleukin-17 Production and Attenuation of Mouse Orthotopic Lung Allograft Rejection.

Background Lung transplantation is the only definitive therapy for many forms of end-stage lung disease. Studies have demonstrated the critical role of interleukin (IL)-17 in the development of lung rejection. Regulatory T cells (Tregs) are essential for the establishment and maintenance of immune tolerance. Methods We established mouse orthotopic lung transplantation models to investigate the importance of IL-17 and IL-17–producing cell types in acute lung allograft rejection and the efficacy of the adoptive transfer of induced Tregs (iTregs) in attenuating pathologic lesions of lung allografts. Results We found that the IL-17 produced by Th17 cells and &ggr;&dgr; T cells might make the primary contributions to the progression of acute lung allograft rejection. Interleukin-17 deficiency decreased lung allograft lesions. Exogenous iTregs maintained their FoxP3 expression levels in lung allograft recipients. Induced Tregs therapy downregulated the expressions of Th17 and IL-17+ &ggr;&dgr; T cells and increased IL-10 production in the mouse orthotopic lung transplantation models. Moreover, the adoptive transfer of iTregs prolonged the survivals of the lung allografts and attenuated the progression of acute rejection. Conclusion These data suggested that the adoptive transfer of iTregs could suppress the Th17 cells and IL-17+ &ggr;&dgr; cells of the recipients, decrease the expression of IL-17, and attenuate the pathology of acute lung allograft rejection. Exogenous iTregs upregulated immunosuppressive factors, such as IL-10 and suppressed IL-17–producing cells, which was one of the pathways to play a role in protecting lung allografts.

Mesenchymal stem cells reprogram host macrophages to attenuate obliterative bronchiolitis in murine orthotopic tracheal transplantation.

After lung transplantation, obliterative bronchiolitis (OB) is one of the major limitations for the long-term survival of allografts. At present, effective treatment to prevent this phenomenon remains elusive. Mesenchymal stem cells (MSCs) are capable of modulating the immune system through the interaction with a wide range of immune cells. Here, we found that treatment of mice with bone marrow derived MSCs prevents the development of airway occlusion and increased IL-10 levels in trachea grafts, which was eliminated by the depletion of macrophages. Mechanistically, MSCs-derived PGE2, through the receptors EP2 and EP4, promoted the release of IL-10 and inhibited the production of IL-6 and TNF-α by macrophages. These results suggest that MSCs can both decrease the innate inflammatory responses and prevent allograft rejection by down-regulating the levels of IL-6 and TNF-α and increasing IL-10 production respectively. For easy availability and immune privilege, MSC-based treatment of OB provides an effective strategy for regulation of immune responses in lung transplantation.

C-Kit Positive Cardiac Stem Cells and Bone Marrow–Derived Mesenchymal Stem Cells Synergistically Enhance Angiogenesis and Improve Cardiac Function After Myocardial Infarction in a Paracrine Manner

BACKGROUND Stem cell transplantation offers a promising treatment for heart failure. Recent studies show that both c-kit positive cardiac stem cells (CSCs) and bone marrow-derived mesenchymal stem cells (BM-MSCs) are good candidates for stem cell therapy to treat heart failure; however, the exact mechanism of stem cell therapy in improving cardiac function of ischemic cardiomyopathy is not fully known. Our objective was to test our hypothesis that CSCs and/or BM-MSCs repair the damaged heart by boosting post-myocardial infarction (MI) angiogenesis in a paracrine manner. METHODS AND RESULTS We isolated and purified CSCs and BM-MSCs from rats. Intramyocardial injections of CSCs and/or BM-MSCs were performed at 28 days after MI. We applied cardiac ultrasound and histological analysis to evaluate the effect of cell therapy on cardiac function and cardiac remodeling. In vivo donor cell transplantation experiments showed that CSCs and/or BM-MSCs improved cardiac function after MI and reduced infarct size. However, in vivo cell tracking experiments showed that minimal donor cells remained in the myocardium after cell transplantation. Our further in vitro and in vivo experiments showed that transplantation of CSCs enhanced the expression of pro-angiogenic factors and boosted post-MI angiogenesis in the myocardium in a paracrine manner, which in part contributed to the effect of CSCs on cardiac recovery after MI. CSCs and BM-MSCs synergistically inhibited CSC/BM-MSC apoptosis and enhanced their proliferation in a paracrine manner. This resulted in a larger number of transplanted cells remaining in the post-MI myocardium after coinjection of CSCs and BM-MSCs, and therefore the accumulation of more pro-angiogenic factors in the heart tissue compared to transplantation of CSCs or MSCs alone. Consequently, transplantation of both CSCs and BM-MSCs was superior to transplantation of either CSCs or BM-MSCs alone to boost post-MI angiogenesis and improve cardiac function after MI. CONCLUSION C-kit+ CSC and/or BM-MSC transplantation can improve cardiac function after MI in a paracrine manner. Coinjection of both CSCs and BM-MSCs improves cardiac function more significantly than CSC or BM-MSC transplantation alone in a paracrine manner by improving the engraftment of donor cells and boosting the expression of multiple pro-angiogenic factors.

IL-25 regulates the polarization of macrophages and attenuates obliterative bronchiolitis in murine trachea transplantation models.

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.

IL-25 promotes the function of CD4+CD25+ T regulatory cells and prolongs skin-graft survival in murine models.

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.

IL-17 contributes to the pathogenesis of obliterative bronchiolitis via regulation of M1 macrophages polarization in murine heterotopic trachea transplantation models

ABSTRACT Acute allograft rejection is a principal conundrum in lung obliterative bronchiolitis (OB). Monocytes/macrophages infiltration has been proved to be the main reason for acute rejection. IL‐17 contributes to the recruitment and function of macrophages. However, the mechanism of IL‐17 underlying OB progression remains elusive. In the present study, we showed that the deficiency of IL‐17 attenuated the pathology of murine heterotopic trachea allografts. Compared to WT recipients, IL‐17−/− mice displayed higher frequency of CD206 + cells and lower ratio of CD86 + cells among F4/80 + macrophages in allografts and spleens on day 7 post heterotopic trachea transplantation. Moreover, mRNA levels of pro‐inflammatory cytokines including IL‐6, TNF‐&agr;, and IL‐1&bgr; decreased in allografts of IL‐17−/− recipients, but these of MRC1 and Arg‐1 increased in comparison with WT. IL‐17 deficiency can inhibit LPS induced M1 while promote IL‐4 induced M2 polarization of bone marrow‐derived macrophages. Further data demonstrated that the deficiency of IL‐17 suppressed the lipopolysaccharide‐induced M1 polarization and function through prevention of phosphorylation of both STAT3 and STAT5. Therefore, IL‐17 contributes to OB pathogenesis through regulating macrophages function, thereby it may unravel part of the complexity of IL‐17 in OB and enhance future therapeutic development. HighlightsDeficiency of IL‐17 attenuated the pathology of murine HTT allografts.Deficiency of IL‐17 contributed to M2 while inhibited M1 macrophages polarization in vivo and in vitro.Deficiency of IL‐17 suppressed LPS induced M1 polarization and function through STAT signaling pathway.

Fasudil preserves lung endothelial function and reduces pulmonary vascular remodeling in a rat model of end‑stage pulmonary hypertension with left heart disease

Pulmonary hypertension (PH) due to left heart disease (LHD) is a common condition associated with significant morbidity. It contributes to the elevation of pulmonary vascular resistance and mean pulmonary pressure, eventually leading to heart failure and even mortality. The present study aimed to explore the potential efficacy of late and long-term treatment with a Rho-kinase (ROCK) signaling inhibitor, namely fasudil, in a rat model of end-stage PH-LHD. The PH-LHD model was established by supracoronary aortic banding, and the effect of fasudil treatment on the progression of PH-LHD was monitored. After 9 weeks (63 days) of supracoronary aortic banding, a significant increase in mean pulmonary pressure and RV systolic pressure was observed in the rats, associated with increased RhoA/ROCK activity in the lungs. Therapy with fasudil (30 mg/kg/day, intraperitoneal) for 4 weeks from postoperative day 35 reversed the hemodynamic disorder and prevented pulmonary vascular remodeling in rats with PH-LHD. In addition, the blockade of ROCK signaling by fasudil decreased the protein levels of endothelin-1 (ET-1) and the mRNA expression levels of endothelin A receptor and promoted the production of nitric oxide (NO) in rats with PH-LHD. Furthermore, fasudil inhibited the migration of human pulmonary microvascular endothelial cells and the proliferation of pulmonary artery smooth muscle cells induced by ET-1. Therefore, this late, long-term blockade of the ROCK pathway by fasudil may be a promising strategy to reverse hemodynamic dysfunction and impede the development of end-stage PH-LHD in patients.