CD8+ T cell survival in lethal fungal sepsis was ameliorated by T-cell-specific mTOR deletion

Lethal fungal sepsis causes high morbidity and mortality in intensive care patients. Fungal infections have an immunological basis, and it has been shown in recent studies that decreased CD8⁺ T-cell count in fungal infections is related to prognosis, while the underlying mechanism is still unclear. Here, a lethal fungal sepsis model induced by candidemia was created and we found a decreased CD8⁺ T-cell count and exaggerated apoptosis. Simultaneously, expression of light chain (LC)3B in CD8⁺ T cells increased, along with increased autophagosomes and accumulation of p62 in infected mice. We regulated the activity of the mammalian target of rapamycin (mTOR) pathway using T-cell-specific mTOR/ TSC1 deletion mice. We observed increased number of autophagosomes and expression of LC3B in CD8⁺T cells after T-cell-specific mTOR knockout, while accumulation of p62 was not ameliorated, and there was no increase in the number of autolysosomes. Apoptosis rate and expression of BIM, a pro-apoptotic gene, decreased in CD8⁺ T cells in mTOR-deletion mice but increased in TSC1-deletion mice. Our results showed increased CD8⁺ T-cell death in spleen of lethal fungal sepsis mice, and decreased expression of mTOR ameliorated CD8⁺ T-cell survival. mTOR may be a possible target to reverse CD8⁺ T-cell immune dysfunction in lethal fungal sepsis.     

芦荟凝胶多糖对急性放射性皮肤损伤模型的修复作用及机制研究

目的研究芦荟凝胶多糖基于磷脂酰肌醇3-激酶(PI3K)-蛋白激酶B(Akt)-雷帕霉素靶蛋白(mTOR)信号通路对急性放射性皮肤损伤模型的修复作用。方法选取40只雄性Wistar大鼠,10只为正常组(等体积生理盐水),其余30只建立急性放射性皮肤损伤模型,随机分为模型组、低剂量组、高剂量组,每组10只。模型组和正常组均给予等体积生理盐水干预,低剂量组、高剂量组分别以单层纱布浸润0.4 mg/mL、0.8 mg/mL的芦荟凝胶多糖外敷干预。记录创面愈合时间、放射性皮肤损伤评级,检测创面微血管密度、血管内皮生长因子(VEGF)含量,病理学观察创面组织细胞形态,Western blot检测PI3K-Akt-mTOR信号通路相关蛋白表达。结果低剂量组和高剂量组创面愈合时间均短于模型组,且高剂量组创面愈合时间显著短于低剂量组(P<0.05);与模型组相比,正常组大鼠0级较多,Ⅳ级较少;低剂量组和高剂量组大鼠Ⅳ级较少(P<0.05)。模型组、低剂量组、高剂量组创面微血管密度、VEGF、PI3K、Akt蛋白表达量低于正常组,mTOR蛋白表达量高于正常组;低剂量组、高剂量组创面微血管密度、VEGF、PI3K、Akt蛋白表达量高于模型组,mTOR蛋白表达量低于模型组;高剂量组创面微血管密度、VEGF、PI3K、Akt蛋白表达量高于低剂量组,mTOR蛋白表达量低于低剂量组。结论高剂量芦荟凝胶多糖可通过调控PI3K-Akt-mTOR信号通路促进急性放射性皮肤损伤模型创面新生血管形成,加快创面修复。     

Mammalian target of rapamycin inhibition after solid organ transplantation: can it,and does it,reduce cancer risk?

The mammalian target of rapamycin (mTOR) inhibitors sirolimus and everolimus has been increasingly used as immunosuppressants for recipients of solid organ transplants. Over the years, potential advantages unique to this class of immunosuppressants have been recognized, including chemoprevention by virtue of their antiproliferative effects. Prevention of malignancy after transplant through mTOR inhibitor‐based immunosuppression may have a specific practical application in transplant recipients with preexisting malignancy including hepatocellular carcinoma or cholangiocarcinoma. This review will reveal how the biochemistry of the mTOR pathway, as it pertains to chemoprevention, can support a clinical role for mTOR inhibitors in the prevention of malignancies, recurrent or de novo, after solid organ transplantation in selected patients.     

Estrogen Activation of G-Protein–Coupled Estrogen Receptor 1 Regulates Phosphoinositide 3-Kinase and mTOR Signaling to Promote Liver Growth in Zebrafish and Proliferation of Human Hepatocytes

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Rapamycin ameliorates the CTLA4‐Ig–mediated defect in CD8+ T cell immunity during gammaherpesvirus infection

Latent viral infections are a major concern among immunosuppressed transplant patients. During clinical trials with belatacept, a CTLA4‐Ig fusion protein, patients showed an increased risk of Epstein–Barr virus‐associated posttransplant lymphoproliferative disorder, thought to be due to a deficient primary CD8⁺ T cell response to the virus. Using a murine model of latent viral infection, we observed that rapamycin treatment alone led to a significant increase in virus‐specific CD8⁺ T cells, as well as increased functionality of these cells, including the ability to make multiple cytokines, while CTLA4‐Ig treatment alone significantly dampened the response and inhibited the generation of polyfunctional antigen‐specific CD8⁺ T cells. However, the addition of rapamycin to the CTLA4‐Ig regimen was able to quantitatively and qualitatively restore the antigen‐specific CD8⁺ T cell response to the virus. This improvement was physiologically relevant, in that CTLA4‐Ig treated animals exhibited a greater viral burden following infection that was reduced to levels observed in untreated immunocompetent animals by the addition of rapamycin. These results reveal that modulation of T cell differentiation though inhibition of mTOR signaling can restore virus‐specific immune competence even in the absence of CD28 costimulation, and have implications for improving protective immunity in transplant recipients.     

雷帕霉素联合TAT-凋亡素抑制胶质瘤的研究

目的：研究雷帕霉素(Rapamycin, Rapa)和凋亡素(TAT-apoptin, T-ap)联合应用对神经胶质瘤的治疗作用。方法用 MTT 实验比较 Rapa、 TAT-apoptin 单用和联合应用对 U87细胞增殖的影响; AO/EB 荧光染色与流式细胞仪检测对 U87细胞凋亡的影响;建立裸鼠 C6胶质瘤皮下移植模型,计算 Rapa、TAT-apoptin 单独及联合作用下的抑瘤率。结果 Rapa 与 TAT-apoptin 单独用药均能抑制 U87细胞的增殖,呈剂量依赖性,联合用药组细胞增殖率明显低于单独用药组(P ﹤0.05);联合用药组凋亡状态比单独用药更明显,呈晚期凋亡形态,细胞凋亡率显著高于单独用药组(P ﹤0.01);在体内实验中,联合用药组抑瘤率为65.5％,雷帕霉素与 TAT-凋亡素单独用药抑瘤率分别为29.59％,24.4％,前者比后者高1倍(P ﹤0.05)。结论 Rapa 与 TAT-ap 联合用药可增强对胶质瘤细胞增殖的抑制作用,促进胶质瘤细胞的凋亡,产生协同的抗肿瘤作用。