THE INHIBITORY EFFECT OF LIDOCAINE ON LPS-INDUCED NEUTROPHILIC AIRWAY INFLAMMATION IN A MOUSE MODEL

Abstract

Lidocaine, widely used as a local analgesic or an anti-ventricular arrhythmia agent, is known to have an anti-inflammatory effect. We investigated the effect of lidocaine on pulmonary inflammation induced by the exposure of lipopolysaccharide (LPS) in mice. LPS-induced lung injury model was established by the intratracheal exposure of LPS to male C57BL/6 mice at 8-10 weeks of age. Lidocaine at 3 or 30 mg/kg was injected intraperitoneally 30 minutes before exposure of LPS. Bronchoalveolar lavage fluid (BALF) and peripheral blood were collected 24 hours after the administration of LPS. Total cells and differetial cell counts in BALF were measured. Interleukin-6 (IL-6) in BALF was measured using enzyme-linked immunosorbent assay. Injection of lidocaine alone by the intraperitoneal route did not alter any cell population in BALF and peripheral blood compared to vehicle control. Treatment with lidocaine significantly reduced the alveolar recruitment of neutrophils in BALF. In concordance with the downregulation of neutrophils, lidacaine reduced the concentration of IL-6, highly associated with neutrophilic inflammation, in BALF. These results suggest that systemic treatment of lidocaine can suppress LPS-induced neutrophic inflammtion in a murine model.