糖尿病交感神经系统失能导致皮肤表面微生物区改变诱发糖尿病溃疡机制的研究

Previous studies showed that skin microbiota maintains skin integrity. The change of microbiota is associated with the diabetic ulcers, and the bacterial load is too heavy to impact wound healing. However, the molecular mechanism of microbiota change in diabetic skin is still unclear.Our previous studies have shown that long-term diabetic state caused damage to sympathetic nerve in skin, and the damage of sympathetic nerve would affect skin perspiration, thickness and blood flow. We speculate that diabetes impaired the function of sympathetic nerve would affect the feature of keratinocytes, skin moisture, both lipids and antimicrobial peptides, which is secreted by sebaceous glands and sweat glands. Eventually, causing the changes of skin surface microbiota and immune function, which are the key factors in the occurrence of diabetic ulcer and hard-to-heal. The study investigate the skin surface microbiota in the different time of diabetes states to understand the change characteristics of microbiota; establish diabetes with sympathetic neurophy animal model to observe the affection of the antimicrobial peptides which is secreted by keratinocytes, and the secreted features of sweat and lipids in the denervated skin. Being sympathetic damaged induced change of microbiota and local immunity, skin barrier dysfunction, then caused diabetic skin ulcers, and healing disorders. The project would help to provide effective means to avoid diabetic wound, and accelerate the refractory wound healing. It would enrich the theory of wound healing.

既往研究表明，体表微生物区维持着皮肤完整性。糖尿病患者皮肤微生物区改变与溃疡相关，且其造成的细菌负载影响愈合。但目前糖尿病皮肤微生物区改变的分子机制不甚清楚。我们既往研究显示，长期糖尿病状态引起皮肤交感神经损害，从而造成皮肤排汗、表皮层厚度和皮肤内附件的改变。我们推测，糖尿病交感神经功能受损后通过影响角质形成细胞、皮脂腺和汗腺分泌抗菌肽、脂质，以及皮肤湿润度，最终致皮肤表面微生物区改变，同时皮肤免疫功能变化，成为糖尿病溃疡发生和难愈的关键因素。本课题通过对糖尿病不同患病时间皮肤表面微生物区的调查，了解其变化特点；建立失糖尿病交感神经动物模型，观察失神经后角质形成细胞抗菌肽分泌情况，以及汗液、脂质分泌特点。获取交感神经受损-微生物区变化-皮肤屏障功能破坏-糖尿病皮肤溃疡发生，且愈合期出现障碍的链条式证据。课题将为延缓糖尿病溃疡发生并加速难愈创面愈合提供新思路与手段，极大丰富组织修复理论。

人体的定植微生物总量超过宿主细胞近 10 倍，而基因的数量超过近 100 倍，机体的定植微生物组不仅参与了氨基酸以及异源生物的代谢，还参与了维生素、类异戊二烯和其他营养素的合成。现有的体内及体外实验均指出微生物的多样性及结构变化将会影响创面的愈合过程，但是这种影响到底是怎么样的并不清楚。本课题首先对正常患者及不同患病周期糖尿病患者足部微生物菌群结构差异进行了初步的探索。随后对糖尿病创面愈合中的微生物菌群的多样性及菌种的丰度变化进行了探索，并联合了人胎儿间充质干细胞分泌素（HFS），将其用于鼠的创面模型中，以观察其对创面愈合的影响及在整个创面愈合过程中微生物菌群结构的变化，通过促进VEGF 持续且均匀的分泌，招募 CD68 细胞，抑制 IL-6 及 CRP 的分泌，促进创面血管化过程，减轻炎症反应，其中巨噬细胞可能参与了炎症因子及血管化的消退，帮助创面更快的转化为正常的组织。本研究初步确立微生物区在糖尿病患者皮肤健康中扮演着内源性稳定剂的作用，是未来进行糖尿病患者皮肤健康预测、慢性创面治疗修复及非特异性皮炎干预治疗的关键点。本研究有助于阐明微生物区在皮肤健康中充当的重要角色，并为将来创面修复开启新的研究方向。