Centre de Physiopathologie Toulouse Purpan (CPTP), INSERM, CNRS, Université de Toulouse, UPS, Toulouse, France.
CNRS, INSERM, CIML, Aix Marseille Université, Marseille, France.
EMBO Mol Med. 2017 Nov;9(11):1605-1621. doi: 10.15252/emmm.201708123.
In malaria, CD4 Th1 and T follicular helper (T) cells are important for controlling parasite growth, but Th1 cells also contribute to immunopathology. Moreover, various regulatory CD4 T-cell subsets are critical to hamper pathology. Yet the antigen-presenting cells controlling Th functionality, as well as the antigens recognized by CD4 T cells, are largely unknown. Here, we characterize the MHC II immunopeptidome presented by DC during blood-stage malaria in mice. We establish the immunodominance hierarchy of 14 MHC II ligands derived from conserved parasite proteins. Immunodominance is shaped differently whether blood stage is preceded or not by liver stage, but the same ETRAMP-specific dominant response develops in both contexts. In naïve mice and at the onset of cerebral malaria, CD8α dendritic cells (cDC1) are superior to other DC subsets for MHC II presentation of the ETRAMP epitope. Using depletion of cDC1, we show that cDC1 promote parasite-specific Th1 cells and inhibit the development of IL-10 CD4 T cells. This work profiles the blood-stage MHC II immunopeptidome, highlights the potency of cDC1 to present malaria antigens on MHC II, and reveals a major role for cDC1 in regulating malaria-specific CD4 T-cell responses.
在疟疾中,CD4 Th1 和滤泡辅助 T 细胞(Tfh)对于控制寄生虫生长很重要,但 Th1 细胞也有助于免疫病理学。此外,各种调节性 CD4 T 细胞亚群对于抑制病理学至关重要。然而,控制 Th 功能的抗原呈递细胞以及 CD4 T 细胞识别的抗原在很大程度上是未知的。在这里,我们描述了在小鼠的血液期疟原虫感染过程中,树突状细胞(DC)呈递的 MHC II 免疫肽组。我们确定了来自保守寄生虫蛋白的 14 种 MHC II 配体的免疫优势等级。无论是否存在肝期,血液期的免疫优势都呈现不同的模式,但在两种情况下都会发展出相同的 ETRAMP 特异性主导反应。在未感染的小鼠和脑型疟的发病初期,CD8α 树突状细胞(cDC1)在 MHC II 呈递 ETRAMP 表位方面优于其他 DC 亚群。通过 cDC1 的耗竭,我们表明 cDC1 促进寄生虫特异性 Th1 细胞的产生,并抑制 IL-10 CD4 T 细胞的发育。这项工作描绘了血液期 MHC II 免疫肽组,强调了 cDC1 在 MHC II 上呈递疟疾抗原的能力,并揭示了 cDC1 在调节疟疾特异性 CD4 T 细胞反应中的主要作用。
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