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Effects of Telithromycin in In Vitro and In Vivo Models of Lipopolysaccharide-Induced Airway Inflammation^*

^* From the Microbial Immunology Research Group, Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain.

Correspondence to: Maria Jimenez-Valera, PhD, Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada 18071, Spain; e-mail: aruizbr{at}ugr.es

Abstract

Background: The ketolide antibiotic telithromycin (TEL) exerts immunomodulatory and antiinflammatory effects in vitro and in a mouse model of septic shock. We studied the antiinflammatory activity of TEL in in vitro and in vivo models of airway inflammation induced by lipopolysaccharide (LPS).

Methods: We measured the effects of TEL on the response of RAW 264.7 macrophages to LPS and of murine lung epithelial (MLE)-12 cells to supernatants of LPS-stimulated RAW 264.7 macrophages. Macrophage inflammatory protein (MIP)-2 and tumor necrosis factor (TNF)- production, nuclear factor (NF)-B activation, and apoptosis were determined. Acute airway inflammation was induced in untreated and TEL-treated BALB/c mice by nebulization with LPS. Total number of leukocytes, macrophages, and neutrophils, the protein concentration, and nitrite and cytokine levels were determined in the BAL fluid.

Results: TEL inhibited in a dose-dependent manner the production of MIP-2 and TNF- by LPS-stimulated RAW 264.7 macrophages, and the production of MIP-2 by MLE-12 epithelial cells to supernatants of LPS-stimulated RAW 264.7 macrophages. NF-B activation was inhibited and apoptosis was increased in both cell lines by TEL. The LPS-induced influx of neutrophils in BAL fluid was decreased by TEL pretreatment. TEL also reduced protein, nitrite, MIP-2, and TNF- levels in the BAL fluid of LPS-nebulized animals.

Conclusions: We have provided evidence that TEL exerts potent antiinflammatory effects in LPS-induced airways injury. We propose that TEL acts in the early phase of inflammation by reducing the release of inflammatory mediators through NF-B inhibition, and in the later phase through enhancement of inflammatory cell apoptosis.

Key Words: airway inflammation • antiinflammatory activity • apoptosis • macrophage inflammatory protein-2 • neutrophil recruitment • nuclear factor-B inhibition • telithromycin