Lee Woojong, Kingstad-Bakke Brock, Kedl Ross M, Kawaoka Yoshihiro, Suresh M
bioRxiv. 2021 Mar 25:2021.03.24.436901. doi: 10.1101/2021.03.24.436901.
Elicitation of lung tissue-resident memory CD8 T cells (T s) is a goal of T-cell based vaccines against respiratory viral pathogens such as influenza A virus (IAV). Chemokine receptor 2 (CCR2)-dependent monocyte trafficking plays an essential role in the establishment of CD8 T s in lungs of IAV-infected mice. Here, we used a combination adjuvant-based subunit vaccine strategy that evokes multifaceted (T 1/T 17/T 1/T 17) IAV nucleoprotein-specific lung T s, to determine whether CCR2 and monocyte infiltration are essential for vaccine-induced T development and protective immunity to IAV in lungs. Following intranasal vaccination, neutrophils, monocytes, conventional dendrtitic cells (DCs) and monocyte-derived DCs internalized and processed vaccine antigen in lungs. We also found that Basic Leucine Zipper ATF-Like Transcription Factor 3 (BATF-3)-dependent DCs were essential for eliciting T cell responses, but CCR2 deficiency enhanced the differentiation of CD127 /KLRG-1 , OX40 CD62L and mucosally imprinted CD69 CD103 effector and memory CD8 T cells in lungs and airways of vaccinated mice. Mechanistically, increased development of lung T s, induced by CCR2 deficiency was linked to dampened expression of T-bet, but not altered TCF-1 levels or T cell receptor signaling in CD8 T cells. T1/T17 functional programming, parenchymal localization of CD8/CD4 effector and memory T cells, recall T cell responses and protective immunity to a lethal IAV infection were unaffected in CCR2-deficient mice. Taken together, we identified a negative regulatory role for CCR2 and monocyte trafficking in mucosal imprinting and differentiation of vaccine-induced T s. Mechanistic insights from this study may aid the development of T-cell-based vaccines against respiratory viral pathogens including IAV and SARS-CoV-2.
While antibody-based immunity to influenza A virus (IAV) is type and sub-type specific, lung and airway-resident memory T cells that recognize conserved epitopes in the internal viral proteins are known to provide heterosubtypic immunity. Hence, broadly protective IAV vaccines need to elicit robust T-cell memory in the respiratory tract. We have developed a combination adjuvant-based IAV nucleoprotein vaccine that elicits strong CD4 and CD8 T cell memory in lungs and protects against H1N1 and H5N1 strains of IAV. In this study, we examined the mechanisms that control vaccine-induced protective memory T cells in the respiratory tract. We found that trafficking of monocytes into lungs might limit the development of anti-viral lung-resident memory T cells, following intranasal vaccination. These findings suggested that strategies that limit monocyte infiltration can potentiate vaccine-induced frontline T-cell immunity to respiratory viruses such as IAV and SARS-CoV-2.
诱导肺组织驻留记忆CD8 T细胞（Trm）是基于T细胞的抗呼吸道病毒病原体（如甲型流感病毒（IAV））疫苗的目标。趋化因子受体2（CCR2）依赖性单核细胞运输在IAV感染小鼠肺部CD8 Trm的建立中起重要作用。在此，我们使用了一种基于佐剂的组合亚单位疫苗策略，该策略可诱发多方面（Th1/Th17/Tc1/Tc17）的IAV核蛋白特异性肺Trm，以确定CCR2和单核细胞浸润对于疫苗诱导的Trm发育以及对肺部IAV的保护性免疫是否必不可少。鼻内接种疫苗后，中性粒细胞、单核细胞、常规树突状细胞（DC）和单核细胞衍生的DC在肺部内化并处理疫苗抗原。我们还发现，依赖碱性亮氨酸拉链ATF样转录因子3（BATF-3）的DC对于引发T细胞反应至关重要，但CCR2缺陷增强了接种疫苗小鼠肺部和气道中CD127⁺/KLRG-1⁻、OX40⁺CD62L⁺和黏膜印记CD69⁺CD103⁺效应和记忆CD8 T细胞的分化。从机制上讲，CCR2缺陷诱导的肺Trm发育增加与T-bet表达降低有关，但CD8 T细胞中的TCF-1水平或T细胞受体信号未改变。T1/T17功能编程、CD8/CD4效应和记忆T细胞的实质定位、回忆性T细胞反应以及对致死性IAV感染的保护性免疫在CCR2缺陷小鼠中未受影响。综上所述，我们确定了CCR2和单核细胞运输在疫苗诱导的Trm的黏膜印记和分化中的负调节作用。本研究的机制见解可能有助于开发针对包括IAV和SARS-CoV-2在内的呼吸道病毒病原体的基于T细胞的疫苗。
虽然针对甲型流感病毒（IAV）的基于抗体的免疫具有型和亚型特异性，但已知识别病毒内部蛋白中保守表位的肺和气道驻留记忆T细胞可提供异源亚型免疫。因此，具有广泛保护作用的IAV疫苗需要在呼吸道中引发强大的T细胞记忆。我们开发了一种基于佐剂组合的IAV核蛋白疫苗，可在肺部引发强烈的CD4和CD8 T细胞记忆，并预防IAV的H1N1和H5N1毒株。在本研究中，我们研究了控制呼吸道中疫苗诱导的保护性记忆T细胞的机制。我们发现，鼻内接种疫苗后，单核细胞向肺部的运输可能会限制抗病毒肺驻留记忆T细胞的发育。这些发现表明，限制单核细胞浸润的策略可以增强疫苗诱导的对呼吸道病毒（如IAV和SARS-CoV-2）的一线T细胞免疫。
