Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, United States.
Innovation Center for Biomedical Informatics, Georgetown University, Washington, DC, United States.
Front Immunol. 2019 Sep 24;10:2273. doi: 10.3389/fimmu.2019.02273. eCollection 2019.
No vaccine exists against visceral leishmaniasis. Toward developing vaccines against VL, we have reported previously on the immunogenicity of live attenuated parasites in animal models. Immunization with parasites has been shown to induce durable protective immunity in pre-clinical animal models. Although the innate immune responses favoring a Th1 type immunity are produced following immunization, the molecular determinants of such responses remain unknown. To identify early biomarkers of immunogenicity associated with live attenuated parasitic vaccines, we infected macrophages derived from healthy human blood donors with or parasites and compared the early gene expression profiles. In addition to altered expression of immune related genes, we identified several microRNAs that regulate important cytokine genes, significantly altered in infection compared to infection. Importantly, we found that infection suppresses the expression of microRNA-21 (miR-21) in human macrophages, which negatively regulates IL12, compared to infection. In murine DC experiments, infection showed a reduced miR-21 expression with a concomitant induction of IL12. Silencing of miR-21 using specific inhibitors resulted in an augmented induction of IL12 in infected BMDCs, illustrating the role of miR-21 in mediated suppression of IL12. Further, exosomes isolated from infected DCs contained significantly reduced levels of miR-21 compared to infection, that promoted proliferation of CD4 T cells . Similar miR-21 mediated IL12 regulation was also observed in human macrophage infection experiments indicating that miR-21 plays a role in early IL12 mediated immunity. Our studies demonstrate that infection suppresses miR-21 expression, enables IL12 mediated induction of adaptive immunity including proliferation of antigen experienced CD4 T cells and development of a Th1 immunity, and suggest that miR-21 could be an important biomarker for vaccine immunity in human clinical trials.
Role of miR-21 in vaccine induced immunity.
目前尚无针对内脏利什曼病的疫苗。为了开发针对利什曼病的疫苗，我们之前曾报道过在动物模型中活减毒寄生虫的免疫原性。免疫接种寄生虫已被证明可在临床前动物模型中诱导持久的保护性免疫。尽管在接种后会产生有利于 Th1 型免疫的先天免疫反应，但这些反应的分子决定因素尚不清楚。为了鉴定与活减毒寄生虫疫苗相关的免疫原性的早期生物标志物，我们用 或 寄生虫感染来自健康人类供体的巨噬细胞，并比较了早期基因表达谱。除了免疫相关基因的表达改变外，我们还鉴定了几个调节重要细胞因子基因的 microRNAs，这些基因在 感染中与 感染相比显著改变。重要的是，我们发现与 感染相比， 感染可抑制人巨噬细胞中 microRNA-21 (miR-21)的表达，从而负调控 IL12。在鼠 DC 实验中，与 感染相比， 感染显示 miR-21 表达降低，同时诱导 IL12。使用特异性抑制剂沉默 miR-21 可导致 感染的 BMDC 中 IL12 的诱导增加，说明 miR-21 在 介导的 IL12 抑制中起作用。此外，与 感染相比，从 感染的 DC 分离的外泌体中 miR-21 的水平显著降低，从而促进 CD4 T 细胞的增殖。在 感染的人巨噬细胞实验中也观察到类似的 miR-21 介导的 IL12 调节，表明 miR-21 在早期 IL12 介导的免疫中起作用。我们的研究表明， 感染抑制 miR-21 的表达，使 IL12 介导适应性免疫，包括抗原经历的 CD4 T 细胞的增殖和 Th1 免疫的发展成为可能，并表明 miR-21 可能是人类临床试验中 疫苗免疫的重要生物标志物。
