新证据!糖尿病竟是“细菌”惹的祸?
2016/05/19
5月16日,发表在Journal of Clinical Investigation上的一项研究表明,细菌在1型糖尿病的发展中扮演着非常重要的角色,它能够触发免疫系统破坏产生胰岛素的细胞。


图片来源:BBSCR

5月16日,发表在Journal of Clinical Investigation上的一项研究表明,细菌在1型糖尿病的发展中扮演着非常重要的角色,它能够触发免疫系统破坏产生胰岛素的细胞。研究人员希望这一结果能够帮助形成新的诊断、预防甚至治愈1型糖尿病的方法。

先前有研究表明,一种保护我们免受细菌伤害的杀手T细胞(killer T-cells)通过破坏β细胞在1型糖尿病发展中发挥了主要的作用。这一新研究中,Cardiff大学的科学家小组发现,杀手T细胞能够被某些细菌强烈激活。领导该研究的Andy Sewell教授说:“杀手T细胞能够极其有效地杀死细菌,但当它们开始错误的攻击自身组织时,会带来毁灭性的影响。”

与2型糖尿病不同,1型糖尿病多发生于儿童和青少年,与饮食无关。目前,科学界对1型糖尿病的形成机制了解甚少,目前该疾病无法治愈且需要终身治疗。在先前的研究中,Cardiff大学的科学家团队从1型糖尿病患者中分离出杀手T细胞,用以观察其杀死β细胞的相互作用。

研究发现,杀手T细胞是高度可交叉反应的(cross-reactive),这意味着它们可对多种不同的触发因子作出反应,这也提出了一种可能性,即有病原体可以刺激启动1型糖尿病的T细胞。研究人员表示,杀手T细胞通过细胞表面受体感受它们的环境,这些受体像高度敏感的“指尖”,扫描细菌。然而,有时这些传感器会识别错误的靶标,杀手T细胞会攻击自身的组织,如在1型糖尿病患者中破坏β细胞。

论文的第一作者David Cole博士说:“这一最新的研究中,我们希望找到导致T细胞杀死β细胞的原因。我们鉴定出了导致T细胞‘故障’的部分原因。”该研究首次观察到了细菌如何触发杀手T细胞导致1型糖尿病。

细菌与2型糖尿病关联的证据

关于细菌与糖尿病的关系,此前也有一些相关的研究。2015年2月24日,发表在mBio上的一项研究中,爱荷华大学的微生物学家指出,2型糖尿病可能也是由细菌引起的。Patrick Schlievert教授领导研究团队发现,持续接触金黄色葡萄球菌产生的毒素会使兔子发展出2型糖尿病的标志性症状,包括胰岛素抵抗、葡萄糖耐受不良和系统性炎症。

众所周知,肥胖是2型糖尿病的重要风险因子,且肥胖会改变机体的微生物组。Schlievert说:“我们发现,随着体重的增加,人体皮肤表面越来越容易被金黄色葡萄球菌占领,这样的个体会长期暴露在细菌生产的超级抗原(superantigens)中。”

先前的研究表明,超级抗原能够干扰免疫系统造成致命的感染,比如中毒性休克综合症、脓毒症和心内膜炎。新研究发现,超级抗原还能与脂肪细胞和免疫系统互作,引发慢性系统性炎症。这种炎症会导致胰岛素抵抗等2型糖尿病的多种标志症状。对4名糖尿病患者皮肤上的金黄色葡萄球菌水平进行分析发现,这些人接触的细菌超级抗原与引发兔子糖尿病的超级抗原剂量相当。

本文参考资料:

medicalxpress,原标题“Do germs cause type 1 diabetes?”

sciencedaily,原标题“Bacteria may cause type 2 diabetes”

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