m6A demethylase ALKBH5 is required for antibacterial innate defense by intrinsic motivation of neutrophil migration

Neutrophil migration into the site of infection is necessary for antibacterial innate defense, whereas impaired neutrophil migration may result in excessive inflammation and even sepsis. The neutrophil migration directed by extracellular signals such as chemokines has been extensively studied, yet the intrinsic mechanism for determining neutrophil ability to migrate needs further investigation. N-6-methyladenosine (m(6)A) RNA modification is important in immunity and inflammation, and our preliminary data indicate downregulation of RNA m(6)A demethylase alkB homolog 5 (ALKBH5) in neutrophils during bacterial infection. Whether m(6)A modification and ALKBH5 might intrinsically modulate neutrophil innate response remain unknown. Here we report that ALKBH5 is required for antibacterial innate defense by enhancing intrinsic ability of neutrophil migration. We found that deficiency of ALKBH5 increased mortality of mice with polymicrobial sepsis induced by cecal ligation and puncture (CLP), and Alkbh5-deficient CLP mice exhibited higher bacterial burden and massive proinflammatory cytokine production in the peritoneal cavity and blood because of less neutrophil migration. Alkbh5-deficient neutrophils had lower CXCR2 expression, thus exhibiting impaired migration toward chemokine CXCL2. Mechanistically, ALKBH5-mediated m(6)A demethylation empowered neutrophils with high migration capability through altering the RNA decay, consequently regulating protein expression of its targets, neutrophil migration-related molecules, including increased expression of neutrophil migration-promoting CXCR2 and NLRP12, but decreased expression of neutrophil migration-suppressive PTGER4, TNC, and WNK1. Our findings reveal a previously unknown role of ALKBH5 in imprinting migration-promoting transcriptome signatures in neutrophils and intrinsically promoting neutrophil migration for antibacterial defense, highlighting the potential application of targeting neutrophil m(6)A modification in controlling bacterial infections.

Automated summary

This study reveals the important role of ALKBH5 in enhancing the intrinsic ability of neutrophil migration for antibacterial innate defense. Deficiency of ALKBH5 results in impaired neutrophil migration, leading to increased mortality and proinflammatory cytokine production in mice with polymicrobial sepsis. Mechanistically, ALKBH5 regulates protein expression of neutrophil migration-related molecules by altering RNA decay, thereby empowering neutrophils with high migration capability.