α-1,3-葡聚糖在monophora着色霉慢性感染中的作用机制研究

着色芽生菌病是由暗色真菌引起的一种病程慢性的深部真菌病。Th1免疫激活不足是慢性病程的关键，而病原菌与宿主未能有效识别可能是其内在机制。我们前期实验表明着色霉新种F.monophora细胞壁α-1,3-glucan对β-1,3-glucan的屏蔽作用可能导致模式识别受体激活不足引起病原菌免疫逃逸，进而导致着色芽生菌病慢性感染形成。本项目拟通过靶向敲除α-1,3-glucan编码基因，利用巨噬细胞共培养证实模式识别受体Dectin-1激活不足与α-1,3-glucan对β-1,3-glucan的屏蔽作用直接相关，并检测其对免疫细胞活力的影响及Th1,Th2细胞激活关键因子的表达情况；动物模型进一步验证α-1,3-glucan编码基因缺失对F.monophora致病性及宿主Th1/Th2免疫平衡的影响，从而明确α-1,3-glucan在F.monophora 慢性感染中的作用机制。

Chromoblastomycosis is a chronic deep mycosis caused by dematiaceos fungi. The inactivation of Th1 plays key role in the chronic course of chromoblastomycosis, and the ineffective recognition between fungal pathogens and host may be its inner mechanism. Our former study showed that the shielding of β-1,3-glucan by α-1,3-glucan in the cell wall to evade immune recognition, which may be induce ineffective activation of pattern-recognition receptors and the pathogenic fungus cannot to be totally cleared by host immune cells, so the chronic course of chromoblastomycosis formed. In this study, we will construct the gene knock-out system of the new Fonsecaea species - F. monophora through knocking out the α-1,3-glucan encoding gene. Then we will use macrophage co-culture system to confirm that the ineffective activation of pattern recognition receptor - Dectin-1 is directly related to the shielding of β-1,3-glucan by α-1,3-glucan, and we will evaluate the influence of immune cell vitality and the key cytokines involved in the Th1,Th2 immune system. And then we will establish animal model to prove that the absence of α-1,3-glucan encoding gene will influence the pathogenicity of F. monophora and the Th1/Th2 immune balance of host. Finally we can confirm the molecular mechanism of α-1,3-glucan in the chronic infection of F. monophora.