Following inoculation of Leishmania, a protozoan parasite, into the skin of a mammal, the epidermal keratinocytes recognize the parasite and influence the local immune response that can give rise to different outcomes of leishmaniasis. The early keratinocyte-derived cytokines and keratinocytes-T cells interactions shape the anti-leishmanial immune responses that contribute to the resistance or susceptibility to leishmaniasis. The keratinocyte-derived cytokines can directly potentiate the leishmanicidal activity of monocytes and macrophages. As keratinocytes express MHC-II and enhance the expression of costimulatory molecules, these cells act as antigen-presenting cells (APCs) in cutaneous leishmaniasis (CL). Depending on the epidermal microenvironment, the keratinocytes induce various types of effector CD4⁺ T cells. Keratinocyte apoptosis and necrosis have been also implicated in ulceration in CL. Further, keratinocytes contribute to the healing of Leishmania-related cutaneous wounds. However, keratinocyte-derived IL-10 may play a key role in the development of post-kala-azar dermal leishmaniasis (PKDL). In this review, a comprehensive discussion regarding the multiple roles played by keratinocytes during leishmaniasis was provided, while highlighting novel insights concerning the immunological and pathological roles of these cells.

中文翻译：

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角化细胞在利什曼病中的免疫作用

将一种原生动物寄生虫利什曼原虫接种到哺乳动物的皮肤中后，表皮角质形成细胞会识别寄生虫并影响局部免疫反应，从而导致利什曼病的不同结果。早期角质形成细胞衍生的细胞因子和角质形成细胞-T 细胞相互作用形成抗利什曼原虫免疫反应，有助于抵抗或易感利什曼病。角质形成细胞衍生的细胞因子可以直接增强单核细胞和巨噬细胞的利什曼原虫活性。由于角质形成细胞表达 MHC-II 并增强共刺激分子的表达，这些细胞在皮肤利什曼病 (CL) 中充当抗原呈递细胞 (APC)。根据表皮微环境，角质形成细胞诱导各种类型的效应子 CD4⁺ T 细胞。角化细胞凋亡和坏死也与 CL 的溃疡形成有关。此外，角质形成细胞有助于利什曼原虫相关皮肤伤口的愈合。然而，角质形成细胞衍生的 IL-10 可能在黑热病后皮肤利什曼病 (PKDL) 的发展中起关键作用。在这篇综述中，提供了关于角化细胞在利什曼病期间所发挥的多重作用的全面讨论，同时强调了关于这些细胞的免疫学和病理学作用的新见解。