Inflammation is prevalent in all stages of
chronic obstructive pulmonary disease, and, furthermore, individuals undergo periods of exacerbation, during which
pulmonary inflammation increases, often a result of
bacterial infection. The present study investigates the in vivo consequences of cigarette
smoke exposure on bacterial challenge with nontypeable Haemophilus influenzae (NTHi). BALB/c and C57 black 6 (C57BL/6) mice were exposed to cigarette
smoke once or twice daily for a total period of 8 weeks. Exacerbated
inflammation was observed in cigarette
smoke-exposed compared to room-air-exposed mice following challenge with live or heat-inactivated NTHi. Accelerated clearance of live NTHi from cigarette
smoke-exposed mice was independent of the establishment of chronic
inflammation or direct toxic effects of cigarette
smoke components on bacteria. Mechanistically, a cell-free factor in the bronchoalveolar lavage fluid contributed to accelerated clearance following passive transfer to naive mice. Further investigation demonstrated increased titres of
immunoglobulin A in the bronchoalveolar lavage fluid, but not the blood, of cigarette
smoke-exposed mice, including increased titres of NTHi-specific
immunoglobulin A, whereas heavy chain joining
element (J(H))(-/-) B-cell-deficient cigarette
smoke-exposed mice did not demonstrate decreased bacterial burden following challenge. The present results demonstrate that cigarette
smoke exposure results in exacerbated
inflammation following challenge with NTHi, as well as increased titres of
antibodies that contribute to bacterial clearance.