The Effect of Cigarette Smoke Exposure on the Development of Inflammation in Lungs, Gut and Joints of TNF(ΔARE) Mice

The inflammatory cytokine TNF-α is a central mediator in many immune-mediated diseases, such as Crohn’s disease (CD), spondyloarthritis (SpA) and chronic obstructive pulmonary disease (COPD). Epidemiologic studies have shown that cigarette smoking (CS) is a prominent common risk factor in these TNF-dependent diseases. We exposed TNF(ΔARE) mice; in which a systemic TNF-α overexpression leads to the development of inflammation; to 2 or 4 weeks of air or CS. We investigated the effect of deregulated TNF expression on CS-induced pulmonary inflammation and the effect of CS exposure on the initiation and progression of gut and joint inflammation. Upon 2 weeks of CS exposure, inflammation in lungs of TNF(ΔARE) mice was significantly aggravated. However, upon 4 weeks of CS-exposure, this aggravation was no longer observed. TNF(ΔARE) mice have no increases in CD4+ and CD8+ T cells and a diminished neutrophil response in the lungs after 4 weeks of CS exposure. In the gut and joints of TNF(ΔARE) mice, 2 or 4 weeks of CS exposure did not modulate the development of inflammation. In conclusion, CS exposure does not modulate gut and joint inflammation in TNF(ΔARE) mice. The lung responses towards CS in TNF(ΔARE) mice however depend on the duration of CS exposure.