AUTHOR=Chen Banru , Ni Xiang , Sun Rui , Zeng Benhua , Wei Hong , Tian Zhigang , Wei Haiming 

TITLE=Commensal Bacteria-Dependent CD8αβ+ T Cells in the Intestinal Epithelium Produce Antimicrobial Peptides

JOURNAL=Frontiers in Immunology

VOLUME=Volume 9 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2018.01065

DOI=10.3389/fimmu.2018.01065

ISSN=1664-3224

ABSTRACT=The epithelium of the intestine functions as the primary, frontline, physical barrier for protection from enteric microbiota. Intraepithelial lymphocytes (IELs) distributed along the intestinal epithelium are predominantly CD8+ T cells, among which CD8αβ+ IELs are a large population. In this investigation, the proportion and absolute number of CD8αβ+ IELs decreased significantly, in both antibiotic-treated and germ-free mice. Moreover, CD8αβ+ IELs were positively correlated with the diversity of commensal microbes, especially Bacteroidetes and Actinobacteria. Microarray analysis revealed that CD8αβ+ IELs expressed a series of genes encoding potent antimicrobial peptides (AMPs), while CD8αβ+ splenocytes (SPLs) did not. The antimicrobial activity of CD8αβ+ IELs was confirmed by bactericidal assay. In conclusion, microbicidal CD8αβ+ IELs are regulated by commensal bacteria, which in turn, secrete AMPs that play a vital role in maintaining the homeostasis of the small intestine.