Flagellin induces innate immune genes in bronchial epithelial cells in vivo : role of TET2

Abstract

The treatment of pneumonia is hampered by emerging anti-microbial resistance among common respiratory pathogens.1Stimulation of innate immune receptors in the lungs is a promising approach to boost protective immunity and improve the outcome of difficult to treat pulmonary infections. In this respect, flagellin has received much attention.2 Toll- like receptor (TLR) 5, which is the receptor of flagellin, is highly expressed by respiratory epithelial cells and exposure of these cells to flagellin in vitro induces the expression of multiple genes involved in innate immunity.2 Administration of flagellin via the airways of mice enhances host defence during experimental pneumonia.3,4 Notably, however, many different cell types express TLR5 and thus far it has not been established whether flagellin activates bronchial epithelial cells in vivo.