Nitric oxide prevents a pathogen-permissive granulocytic inflammation during tuberculosis.

Nature microbiology, Volume: 2
May 15, 2017
Bibhuti B Mishra BB, Rustin R Lovewell RR, Andrew J Olive AJ, Guoliang Zhang G, Wenfei Wang W, Eliseo Eugenin E, Clare M Smith CM, Jia Yao Phuah JY, Jarukit E Long JE, Michelle L Dubuke ML, Samantha G Palace SG, Jon D Goguen JD, Richard E Baker RE, Subhalaxmi Nambi S, Rabinarayan Mishra R, Matthew G Booty MG, Christina E Baer CE, Scott A Shaffer SA, Veronique Dartois V, Beth A McCormick BA, Xinchun Chen X, Christopher M Sassetti CM

Nitric oxide contributes to protection from tuberculosis. It is generally assumed that this protection is due to direct inhibition of Mycobacterium tuberculosis growth, which prevents subsequent pathological inflammation. In contrast, we report that nitric oxide primarily protects mice by repressing an interleukin-1- and 12/15-lipoxygenase-dependent neutrophil recruitment cascade that promotes bacterial replication. Using M. tuberculosis mutants as indicators of the pathogen’s environment, we inferred that granulocytic inflammation generates a nutrient-replete niche that supports M. tuberculosis growth. Parallel clinical studies indicate that a similar inflammatory pathway promotes tuberculosis in patients. The human 12/15-lipoxygenase orthologue, ALOX12, is expressed in cavitary tuberculosis lesions; the abundance of its products correlates with the number of airway neutrophils and bacterial burden and a genetic polymorphism that increases ALOX12 expression is associated with tuberculosis risk. These data suggest that M. tuberculosis exploits neutrophilic inflammation to preferentially replicate at sites of tissue damage that promote contagion.

Courtesy of the U.S. National Library of Medicine