Alteration of skin immune environment by sand fly saliva across progressive Leishmaniasis

总结 内脏利什曼病（VL），由杜氏利什曼原虫复合体引起。导致20000- 每年有4万人死亡。L.婴儿是地中海盆地VL的原因，并输入到南方和非洲。 和北美L.婴儿是犬科动物的宿主。利什曼主要传播的是 雌性沙蝇或白蛉在哺乳动物宿主之间传播。已经确定， 白蛉和宿主因素调节寄生虫首次接触皮肤时的局部皮肤免疫， 引导局部和全身免疫并影响感染结果。关于这一点，我们所知甚少。 进行性VL期间的皮肤免疫环境，真皮免疫变化如何改变宿主传染性， 对免疫调节性沙蝇唾液成分的反应。感染L.原虫 感染与传播效率相关，比寄生虫血症更相关，尽管晚期感染的狗 疾病的传染性低于那些轻中度疾病。我们已经证明，无症状VL 临床状态在狗中与人一样，与生产性Th 1型应答相关，而症状性 感染与耗尽的CD 4+和CD 8 + T细胞的存在相关，程序化T细胞的显著表达， 死亡1（PD-1）及其配体，B细胞和巨噬细胞上的PD-L1以及巨噬细胞寄生虫的丢失 间隙这些发现共同引导我们假设亚临床或非临床免疫细胞应答是免疫细胞应答的一部分。 临床感染宿主的皮肤，无论是来自狗还是人，都决定了宿主的传染性。我们会解决这个问题 在这项拟议的工作中，通过三个具体的目标，1）确定独特的真皮免疫环境 在亚临床与临床宿主中，改变对幼稚白蛉的感染性，2）评估 沙蝇唾液蛋白在进行性VL期间受到皮肤变化的影响，导致对 媒介唾液-宿主相互作用以及它们如何促进白蛉的传染性，以及3）评估如何 通过皮肤免疫疗法改变皮肤免疫环境改变了咬位炎症， 传输因此，这里提出的工作是重要的，因为它提供了感染控制相关的 关于皮肤微环境及其如何改变进行性婴儿乳杆菌感染性的证据 感染这里提出的研究是显着的创新，因为他们在空间层面上定量 评估寄生虫负荷和不同皮肤炎症状态如何改变对白蛉的感染性。使用 纯化的唾液抗原，皮肤活检，组织病理学和转录组分析和一个关键的独特的天然 感染队列，我们将确定如何进行性VL改变景观，其中载体唾液蛋白 对理解VL的宿主传染性和流行病学都有影响。当 完成后，这些拟议研究的结果都将强调进行性皮肤炎症 影响宿主的传染性，并提供关键数据，以进一步评估适当的干预措施， 防止犬-沙蝇-人传播。

Summary Visceral leishmaniasis (VL), caused by Leishmania donovani complex spp. causes between 20,000- 40,000 deaths a year. L. infantum is the cause of VL in the Mediterranean basin and imported to both South and North America. L. infantum is zoonotic with canid reservoirs. Leishmania spp. are transmitted primarily between mammalian hosts by female Lutzomyia or Phlebotomus sand flies. It has been established that both sand fly and host factors modulate local dermal immunity when and where parasites first encounter skin, guiding immunity locally and systemically and impacting infection outcomes. Relatively little is known about the skin immune environment during progressive VL, how dermal immune changes alter host infectiousness or responses to immunomodulatory sand fly salivary components. Skin parasite burden in dogs with L. infantum infection correlates with transmission efficiency, more so than parasitemia, though dogs with late-stage disease were less infectious than those with mild-moderate disease. We have shown that asymptomatic VL clinical status was associated in dogs, as in humans, with productive Th1 type responses, while symptomatic infection correlated with presence of exhausted CD4+ and CD8+ T cells, significant expression of Programmed Death 1 (PD-1) and its ligand, PD-L1 on both B cells and macrophages and loss of macrophage parasite clearance. These findings collectively lead us to hypothesize that immune cell responses in subclinical or clinically infected hosts’ skin, whether from dogs or humans, dictate host infectiousness. We will address this hypothesis through three specific aims in this proposed work, 1) Identify unique dermal immune environments in subclinical vs. clinical hosts that alter infectiousness to naïve sand flies, 2) Evaluate how the functions of sand fly salivary proteins are impacted by skin changes during progressive VL leading to new understanding of vector saliva-host interactions and how they contribute to infectiousness to sand flies and 3) Evaluate how alteration of the dermal immune environment through dermal immunotherapy alters bite-site inflammation and transmission. The work proposed here is therefore significant, as it provides infection control relevant evidence regarding the dermal microenvironment and how it alters infectivity during progressive L infantum infection. The studies proposed here are significantly innovative as they quantitatively on a spatial level assess how parasite burden and different dermal inflammatory states alter infectiousness to sand flies. Using purified salivary antigens, skin biopsy, histopathologic and transcriptome analysis and a key unique natural infection cohort, we will determine how progressive VL alters the landscape in which vector salivary proteins operate with consequences for understanding both host infectiousness and the epidemiology of VL. When completed, findings from these proposed studies will both underscore how progressive dermal inflammation impacts reservoir host infectiousness and provide critical data to further assess appropriate interventions to prevent canine-sand fly-human transmission.