A role for hydroxy-methylglutaryl coenzyme A reductase in pulmonary inflammation and host defense

Rationale: A growing literature indicates that hydroxy-methylglutaryl coenzyme A reductase inhibitors (statins) modulate proinflammatory cellular signaling and functions. No studies to date, however, have addressed whether statins modulate pulmonary inflammation triggered by aerogenic stimuli or whether they affect host defense. Objectives: To test whether lovastatin modulates LPS-induced pulmonary inflammation and antibacterial host defense. Methods: To address these questions, and to confirm any effect of statins as dependent on inhibition of hydroxy-methylglutaryl coenzyme A reductase, we treated C57BI/6 mice with three oral doses of 10 mg/kg lovastatin (or vehicle) and three intraperitoneal doses of 10 mg/kg mevalonic acid (or saline), and then exposed them to the following: (1) aerosolized LPS, (2) intratracheal keratinocyte-derived chemokine (KC), or (3) intratracheal Klebsiella pneumoniae. Measurements and main results: LPS- and KC-induced airspace neutrophils were reduced by lovastatin, an effect that was blocked by mevalonic acid cotreatment. Lovastatin was also associated with reduced parenchymal myeloperoxidase and microvascular permeability, and altered airspace and serum cytokines after LPS. Native pulmonary clearance of K. pneumoniae was inhibited by lovastatin and extrapulmonary dissemination was enhanced, both reversibly with mevalonic acid. Ex vivo studies of neutrophils isolated from lovastatin-treated mice confirmed inhibitory effects on Rac activation, actin polymerization, chemotaxis, and bacterial killing. Conclusion: Lovastatin attenuates pulmonary inflammation induced by aerosolized LPS and impairs host defense.