The short chain fatty acid butyrate prevents intracellular replication of Legionella by regulating cysteine levels in macrophages

Macrophages can prevent infections from intracellular pathogens by restricting access to essential nutrients, termed nutritional immunity. With the exception of tryptophan depletion, it is unclear if other amino acids are similarly regulated in infected macrophages. Here, we show that the expression of nutrient transporters in Legionella-infected macrophages is modulated by the short chain fatty acid butyrate. Butyrate prevented the upregulation of the cystine/glutamate exchanger, Slc7a11, in macrophages infected with L. pneumophila, which decreased cellular cysteine levels. Butyrate and the Slc7a11 inhibitor erastin impaired intracellular Legionella replication in macrophages in vitro, with these being restored by exogenous supplementation with cysteine. Butyrate caused increased histone acetylation in infected macrophages, and pan- and class II HDAC inhibitors also restricted intracellular Legionella growth in a cysteine-dependent manner. Intranasal administration of butyrate reduced L. pneumophila lung burdens in mice. Our data suggest that butyrate alters the metabolism of macrophages to promote nutritional immunity by decreasing cysteine levels and that this can be harnessed to treat bacterial lung infections.