Acute inflammation, mediated by lung neutrophils, confers enhanced protection against Mycobacterium tuberculosis infection in mice

Inflammation plays a crucial role in the control of Mycobacterium tuberculosis (M.tb) infection. In this study, we demonstrate that an inflammatory pulmonary environment at the time of infection mediated by liposaccharide (LPS) treatment in mice confers enhanced protection against M.tb for up to 6 months post infection. This transient protective inflammatory environment was associated with a neutrophil and monocyte/macrophage influx as well as increased inflammatory cytokines. In vitro infection of neutrophils from LPS treated mice demonstrated that LPS neutrophils exhibited increased recognition of M.tb, and had a greater innate capacity for killing M.tb. Finally, partial depletion of neutrophils in LPS treated mice showed an increase in M.tb burden, suggesting neutrophils conferred the enhanced protection observed in LPS treated mice. These results indicate a positive role of an inflammatory environment during initial M.tb infection, and suggests that acute inflammation at the time of M.tb infection can positively alter disease outcome.