Lactobacillus rhamnosus GG inhibits neutrophil extracellular trap formation

Abstract

Alterations in the gut microbiota, referred to as dysbiosis, are strongly associated with chronic inflammatory bowel diseases. Neutrophils are one of the earliest cells to respond to an inflammatory stimulus and, in the inflamed intestine, constitute a significant proportion of cells that are recruited. Whereas probiotics have been shown to exert beneficial effects on gut homeostasis, their effect on neutrophil extracellular trap (NET) formation remains undefined. Therefore, the aim of this study was to determine the effects of the probiotic Lactobacillus rhamnosus GG (LGG) on the dynamics of NET formation. Bone marrow‐derived neutrophils (BMDN) were isolated from C57BL6 mice and co‐incubated with LGG (1 h, 37°C, 5% CO2) prior to stimulation with phorbol 12‐myristate 13‐acetate (PMA, 100 nM), which is an inducer of NET formation. Measurements of extracellular DNA (Sytox Green, 5 nM) and immunofluorescence microscopy staining for DNA, elastase and histones demonstrated that LGG mediated a concentration‐dependent reduction in NET‐osis. Given the proximity of recruited neutrophils to the lumen of the inflamed gut and the resident intestinal microbiota, it is important to define how neutrophil‐microbe interactions affect the local microenvironment. This work was funded by CIHR (operating grant MOP‐89894).