B cells regulate early lung macrophage activation during influenza virus infection via production of acetylcholine

Abstract

Abstract The neurotransmitter Acetylcholine (ACh) is produced by the enzyme choline acetyltransferase (ChAT). Recently, ChAT expression was found in leukocytes, however, the function of leukocyte-derived ACh is incompletely understood. Flow cytometry showed that most ChAT-expressing cells in the spleen, lymph nodes, lung, and pleural cavity of ChAT-GFP reporter mice are B cells. B-1 cells contain the highest frequencies of ChAT-expressors. B cell-specific Mb1-Cre+ ChAT fl/flknockouts (B Chat-KO) showed comparable bone marrow B cell development and steady-state serum IgG and IgM production as wild-type littermate controls. Given earlier studies showing TLR-mediated induction of ChAT in B cells, we studied infection of ChAT-GFP mice with Influenza A/Puerto Rico/8/34. Infection resulted in an accumulation of ChAT-expressing B cells in the lungs by 1- and 3-days post infection (dpi). Moreover, B Chat-KOmice showed significant reductions in viral loads at 1 dpi, suggesting that B cell-derived ACh regulates early innate antiviral immunity. Indeed, B Chat-KOshowed increased TNFa-expressing and CD86 hilung macrophages at 1dpi. Consistent with this, acetylcholine reduced TNFa-expression in LPS-stimulated macrophages in vitro. In contrast, Lck-Cre+ ChAT fl/flthat lack ChAT in T cells showed no difference in lung viral loads at 1dpi compared to controls, and the numbers of ChAT-expressing T cells in the lungs and draining lymph nodes did not increase until 7dpi. Together these data suggest a new regulatory function for B cells in early virus-induced lung inflammation via production of ACh. - Chan Zuckerberg Initiative to Colin Reardon and Nicole Baumgarth - NIH/NIAID R01AI148652 Nicole Baumgarth