Cigarette smoke increases TLR4 and TLR9 expression and induces cytokine production from CD8⁺ T cells in chronic obstructive pulmonary disease

Cigarette smoke is a major risk factor for chronic obstructive pulmonary disease (COPD), an inflammatory lung disorder. COPD is characterized by an increase in CD8⁺ T cells within the central and peripheral airways. We hypothesized that the CD8⁺ T cells in COPD patients have increased Toll-like receptor (TLR) expression compared to control subjects due to the exposure of cigarette smoke in the airways