IL-6 Drives Neutrophil-Mediated Pulmonary Inflammation Associated with Bacteremia in Murine Models of Colitis.
Level 5 - mechanism / opinion, no new human data
Preclinical animal model study
PubMed 29684360 · doi:10.1016/j.ajpath.2018.03.016
What was done
Researchers used trinitrobenzenesulfonic acid (TNBS)- and dextran sulfate sodium (DSS)-induced murine models of colitis to investigate immune mechanisms underlying pulmonary manifestations of inflammatory bowel disease. They evaluated lung tissue neutrophil accumulation, systemic markers of inflammation (bacteremia and pyrexia), bone marrow neutrophil recruitment, and the therapeutic impact of functional IL-6 inhibition.
What was found
The abstract reports no exact numerical values, effect sizes, or confidence intervals. Qualitatively, both colitis models showed increased neutrophil infiltration in lung tissue surrounding the pulmonary vasculature. Systemic neutrophilia was associated with bacteremia and pyrexia. IL-6 was identified as a systemic driver of bone marrow neutrophil recruitment in DSS colitis. Functional blockade of IL-6 decreased systemic and pulmonary neutrophilia, though it did not reduce established intestinal colitis pathology.
Why it matters
These findings suggest that systemic bacteremia secondary to colitis promotes IL-6 secretion, which drives extraintestinal pulmonary neutrophil infiltration. Targeting IL-6 could represent a strategy for managing respiratory complications in inflammatory bowel disease independent of primary gut pathology.
Limits
The study was conducted entirely in rodent models of chemically induced colitis, which may not fully capture the complexity or chronicity of human inflammatory bowel disease. The abstract provides no sample sizes, numerical data, or statistical significance values, and non-neutrophil immune cell contributions to lung pathology were not described.
Cited by
- supports Localized intestinal inflammation triggers the release of systemic cytokines that transmit inflammatory signals to other organ systems throughout the body.