Extracellular matrix protein 1 promotes follicular helper T cell differentiation and antibody production.

He, Lan; Gu, Wangpeng; Wang, Meng; Chang, Xiaoyan; Sun, Xiaoyu; Zhang, Yuan; Lin, Xuan; Yan, Chenghua et al. · Proc Natl Acad Sci U S A · 2018

basic_science · Level V

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Abstract

T-follicular helper (T<sub>FH</sub>) cells are a subset of CD4<sup>+</sup> helper T cells that help germinal center (GC) B-cell differentiation and high-affinity antibody production during germinal center reactions. Whether important extracellular molecules control T<sub>FH</sub> differentiation is not fully understood. Here, we demonstrate that a secreted protein extracellular matrix protein 1 (ECM1) is critical for T<sub>FH</sub> differentiation and antibody response. A lack of ECM1 inhibited T<sub>FH</sub> cell development and impaired GC B-cell reactions and antigen-specific antibody production in an antigen-immunized mouse model. ECM1 was induced by IL-6 and IL-21 in T<sub>FH</sub> cells, promoting T<sub>FH</sub> differentiation by down-regulating the level of STAT5 phosphorylation and up-regulating Bcl6 expression. Furthermore, injection of recombinant ECM1 protein into mice infected with PR8 influenza virus promoted protective immune responses effectively, by enhancing T<sub>FH</sub> differentiation and neutralizing antibody production. Collectively, our data identify ECM1 as a soluble protein to promote T<sub>FH</sub> cell differentiation and antibody production.

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