BACKGROUND Salmonella enterica serovar Typhi (S. Typhi) is a highly invasive bacterium that infects the human intestinal mucosa and causes ~ 11.9-20.6 million infections and ~ 130,000-223,000 deaths annually worldwide. Oral typhoid vaccine Ty21a confers a moderate level of long-lived protection (5-7 years) in the field. New and improved vaccines against enteric pathogens are needed but their development is hindered by a lack of the immunological correlates of protection especially at the site of infection. Tissue resident memory T (TRM) cells provide immediate adaptive effector immune responsiveness at the infection site. However, the mechanism(s) by which S. Typhi induces TRM in the intestinal mucosa are unknown. Here, we focus on the induction of S. Typhi-specific CD4+TRM subsets by Ty21a in the human terminal ileum lamina propria and epithelial compartments. METHODS Terminal ileum biopsies were obtained from consenting volunteers undergoing routine colonoscopy who were either immunized orally with 4 doses of Ty21a or not. Isolated lamina propria mononuclear cells (LPMC) and intraepithelial lymphocytes (IEL) CD4+TRM immune responses were determined using either S. Typhi-infected or non-infected autologous EBV-B cell lines as stimulator cells. T-CMI was assessed by the production of 4 cytokines [interferon (IFN)γ, interleukin (IL)-2, IL-17A and tumor necrosis factor (TNF)α] in 36 volunteers (18 vaccinees and 18 controls volunteers). RESULTS Although the frequencies of LPMC CD103+ CD4+TRM were significant decreased, both CD103+ and CD103- CD4+TRM subsets spontaneously produced significantly higher levels of cytokines (IFNγ and IL-17A) following Ty21a-immunization. Importantly, we observed significant increases in S. Typhi-specific LPMC CD103+ CD4+TRM (IFNγ and IL-17A) and CD103- CD4+TRM (IL-2 and IL-17A) responses following Ty21a-immunization. Further, differences in S. Typhi-specific responses between these two CD4+TRM subsets were observed following multifunctional analysis. In addition, we determined the effect of Ty21a-immunization on IEL and observed significant changes in the frequencies of IEL CD103+ (decrease) and CD103- CD4+TRM (increase) following immunization. Finally, we observed that IEL CD103- CD4+TRM, but not CD103+ CD4+TRM, produced increased cytokines (IFNγ, TNFα and IL-17A) to S. Typhi-specific stimulation following Ty21a-immunization. CONCLUSIONS Oral Ty21a-immunization elicits distinct compartment specific immune responses in CD4+TRM (CD103+ and CD103-) subsets. This study provides novel insights in the generation of local vaccine-specific responses. Trial registration This study was approved by the Institutional Review Board and registered on ClinicalTrials.gov (identifier NCT03970304, Registered 29 May 2019-Retrospectively registered, http://www.ClinicalTrials.gov/NCT03970304).

中文翻译：

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口服伤寒疫苗Ty21a在人末端回肠固有层和上皮区室中引起抗原特异性的常驻CD4 + T细胞。

背景技术肠炎沙门氏菌伤寒沙门氏菌（S. Typhi）是一种高侵入性细菌，其感染人肠粘膜并在全世界每年导致约11.9-20.6百万感染和约130,000-223,000死亡。口服伤寒疫苗Ty21a在现场可提供中等水平的长期保护（5-7年）。需要新的和改良的针对肠病原体的疫苗，但是由于缺乏保护性免疫相关性，特别是在感染部位，阻碍了它们的发展。组织常驻记忆T（TRM）细胞在感染部位提供即时的适应性效应免疫应答。然而，伤寒沙门氏菌在肠粘膜中诱导TRM的机制尚不清楚。在这里，我们集中于S的归纳。Ty21a在人类末端回肠固有层和上皮区室中的Typhi特异性CD4 + TRM亚型。方法从接受常规结肠镜检查的自愿志愿者那里获得末端回肠活组织检查，他们可以口服或不接种4剂Ty21a进行免疫。使用伤寒沙门氏菌感染或未感染的自体EBV-B细胞系作为刺激细胞，确定分离的固有层单核细胞（LPMC）和上皮内淋巴细胞（IEL）CD4 + TRM免疫应答。通过在36名志愿者（18名疫苗接种者和18名对照志愿者）中产生4种细胞因子[干扰素（IFN）γ，白介素（IL）-2，IL-17A和肿瘤坏死因子（TNF）α]评估T-CMI。结果尽管LPMC CD103 + CD4 + TRM的频率显着降低，Ty21a免疫后，CD103 +和CD103- CD4 + TRM亚群均自发产生明显更高水平的细胞因子（IFNγ和IL-17A）。重要的是，我们观察到Ty21a免疫后，伤寒沙门氏菌特异性LPMC CD103 + CD4 + TRM（IFNγ和IL-17A）和CD103-CD4 + TRM（IL-2和IL-17A）应答显着增加。此外，多功能分析后观察到这两个CD4 + TRM亚型之间的伤寒沙门氏菌特异性应答有所不同。此外，我们确定了Ty21a免疫对IEL的影响，并观察了免疫后IEL CD103 +（减少）和CD103-CD4 + TRM（增加）频率的显着变化。最后，我们观察到，Ty21a免疫后，IEL CD103- CD4 + TRM而非CD103 + CD4 + TRM产生了针对鼠伤寒沙门氏菌特异性刺激的细胞因子（IFNγ，TNFα和IL-17A）增加。结论口服Ty21a免疫在CD4 + TRM（CD103 +和CD103-）亚群中引起不同的区室特异性免疫反应。这项研究为产生局部疫苗特异性反应提供了新的见解。试验注册本研究已获得机构审查委员会的批准并在ClinicalTrials.gov上进行注册（标识符NCT03970304，于2019年5月29日注册-追溯注册，http：//www.ClinicalTrials.gov/NCT03970304）。