IMMUNE REGULATION AND VACCINE DEVELOPMENT IN LEISHMANIASIS

炎性单核细胞可以被环境线索操纵来执行多种功能。为了确定单核细胞在吞噬体内病原体感染的原发或继发部位的作用，我们使用了利什曼原虫主要红色荧光蛋白(RFP)寄生虫和多色流式细胞术来定义和计数皮肤中感染和未感染的炎症细胞。在初次感染期间，感染的单核细胞改变了成熟，是寄生虫复制的初始单核宿主细胞。在次级位点，同样的群体以干扰素依赖的方式迅速产生诱导型一氧化氮合酶(INOS)，这对寄生虫的杀灭至关重要。单核细胞诱导型一氧化氮合酶的产生不需要成熟为树突状细胞样表型，单核细胞募集增加与干扰素依赖的cxcl10表达相关。相比之下，中性粒细胞是原发和继发部位寄生虫的安全避难所。因此，炎性单核细胞在原发和继发感染部位的吞噬体内感染过程中扮演着不同的角色。 皮肤感染中真皮巨噬细胞的来源和功能尚不清楚。我们发现，与治愈株(LmFn)相比，在常规耐药的C57BL/6小鼠身上产生不可愈合皮肤损害的大利什曼原虫(LMSD)株在体外被M2极化的骨髓来源的巨噬细胞(BMDM)更有效地摄取，在体内通过真皮巨噬细胞的甘露糖受体(MR)更有效地摄取。在稳定期和炎症状态下，MRHI真皮巨噬细胞均表现出M2特征。值得注意的是，LMSD对M2 BMDM的有利感染依赖于MR。MR的基因缺失和抗CSF-1受体抗体选择性地去除MRHI真皮巨噬细胞都逆转了这种不可愈合的表型。MRHI真皮巨噬细胞具有放射抗性，在感染期间不被成人骨髓来源的细胞取代，但由IL-4和IL-10局部维持。我们的结论是，胚胎来源的M2样真皮巨噬细胞即使在强大的TH1免疫环境中也允许寄生虫生长，这些细胞的优先感染在皮肤病的严重程度中起着至关重要的作用。

Inflammatory monocytes can be manipulated by environmental cues to perform multiple functions. To define the role of monocytes at primary or secondary sites of infection with an intra-phagosomal pathogen we employed Leishmania major-red fluorescent protein (RFP) parasites and multi-color flow cytometry to define and enumerate infected and uninfected inflammatory cells in the skin. During primary infection, infected monocytes had altered maturation and were the initial mononuclear host cell for parasite replication. At secondary sites, this same population rapidly produced inducible nitric oxide synthase (iNOS) in an IFN- dependent manner and was critical for parasite killing. Maturation to a dendritic cell-like phenotype was not required for monocyte iNOS-production, and enhanced monocyte recruitment correlated with IFN- dependent cxcl10 expression. In contrast, neutrophils were a safe haven for parasite in both primary and secondary sites. Thus, inflammatory monocytes play divergent roles during intra-phagosomal infection at primary versus secondary sites of infection. The origin and function of dermal macrophages in cutaneous infections remain poorly studied. We found that a strain of Leishmania major (LmSd) that produces non-healing cutaneous lesions in conventionally resistant C57BL/6 mice was more efficiently taken up by M2-polarized bone marrow derived macrophages (BMDMs) in vitro and by mannose receptor (MR)hi dermal macrophages in vivo compared with a healing strain (LmFn). Both in steady and inflammatory states, the MRhi dermal macrophages showed M2 characteristics. Notably, the favored infection of M2 BMDMs by LmSd depends on MR. Both genetic deletion of MR and selective depletion of MRhi dermal macrophages by anti-CSF-1 receptor antibody reversed the non-healing phenotype. The MRhi dermal macrophages were radio-resistant and not replaced by adult bone marrow-derived cells during infection, but were locally maintained by IL-4 and IL-10. We conclude that embryonic-derived, M2-like dermal macrophages are permissive for parasite growth even in a strong TH1 immune environment, and the preferential infection of these cells plays a crucial role in the severity of cutaneous disease.