Long-lived TRM Th17 cells develop after bacterial immunization.

AMEZCUA VESELY MARIA CAROLINA; PALLIS, PARIS; BIELECKI, PIOTR; FLAVELL, RICHARD A.

Congreso; Gordon Conference; 2016

Gordon Foundation

A defining feature of adaptive immunity is the ability to generate long-lived populations of memory cells. Upon microbial infections, CD8 and CD4 T cells experience clonal expansion followed by a contraction phase and the development of memory. Th17 cells have been revealed as a subset of effector CD4 T cells with an important role in the control of specific pathogens as well as in the development of autoimmune diseases, however their maintenance and stability during memory immune response is controversial. Recent studies suggest that subsets of memory T cells are retained at specific sites as tissue-resident memory T cells (TRM), and may confer an effective in situ first line of defense to tissue-specific infections. CD4-TRM cells are present in several mucosal tissues and they were mainly described as IFN-gamma producers after viral infections. The origin of CD4 TRM cells is still unknown, however CD8 TRM seem to be more closely related to circulating TCM than to TEM based on KLRG1 expression. The maintenance of CD8 TRM involves TGF-b and IL-15, though the factors those keep the longevity of CD4 TRM are an area of extensive research. We are interesting in the study of Th17 TRM and we found that intranasal bacterial immunization induce the differentiation of CD4 TRM Th17 cells that remains as a quiescent population for at least 110 days after immunization. Our data suggest that Th17 cells include a population of long-lived TRM, which could potentially have important implications for targeting site-specific immunity in vaccines and immunotherapies.