Suppression of co-stimulatory molecule expressions on splenic B lymphocytes by a macrolide antibiotic, roxithromycin in vitro

Efficacy of clarithromycin as a protective agent in the methotrexate-induced pulmonary fibrosis model

Introduction

Methotrexate is a cytotoxic agent used in leukemia, and several other cancer types and at lower doses in auto-inflammatory diseases such as rheumatoid arthritis, ankylosing spondylitis and psoriasis. Macrolide antibiotics are effective against gram-positive and Gram-negative bacteria. They have anti-inflammatory activities as well. Clarithromycin is a macrolide with anti-inflammatory activity through blockage of the p38 MAPK signal cascade, which is involved in methotrexate-induced pulmonary toxicity.

Aim

In this study, the efficacy of clarithromycin in protecting against pulmonary fibrosis was investigated in the rat model for methotrexate-induced pulmonary fibrosis.

Material and methods

A total of 30 female rats were divided into three groups. Group I was administered intraperitoneal and intragastric saline; group II was administered oral 3 mg/kg methotrexate; and group III was administered oral 3 mg/kg methotrexate + intraperitoneal 200 mg/kg clarithromycin for 28 days. Histopathological analyses of the lung tissues were performed under light microscopy.

Results

Normal histopathological changes were observed in the control group. Pulmonary fibrosis was significantly higher in the methotrexate group than in the other groups (p < 0.005).

Conclusions

Clarithromycin was shown to be effective in protecting against methotrexate-induced pulmonary fibrosis; further studies should be performed to determine the dosage and safety.

Pathogen- and host-directed anti-inflammatory activities of macrolide antibiotics

Macrolide antibiotics possess several, beneficial, secondary properties which complement their primary antimicrobial activity. In addition to high levels of tissue penetration, which may counteract seemingly macrolide-resistant bacterial pathogens, these agents also possess anti-inflammatory properties, unrelated to their primary antimicrobial activity. Macrolides target cells of both the innate and adaptive immune systems, as well as structural cells, and are beneficial in controlling harmful inflammatory responses during acute and chronic bacterial infection. These secondary anti-inflammatory activities of macrolides appear to be particularly effective in attenuating neutrophil-mediated inflammation. This, in turn, may contribute to the usefulness of these agents in the treatment of acute and chronic inflammatory disorders of both microbial and nonmicrobial origin, predominantly of the airways. This paper is focused on the various mechanisms of macrolide-mediated anti-inflammatory activity which target both microbial pathogens and the cells of the innate and adaptive immune systems, with emphasis on their clinical relevance.

Suppression of nitric oxide production from nasal fibroblasts by metabolized clarithromycin in vitro

Background

Low-dose and long-term administration of 14-membered macrolide antibiotics, so called macrolide therapy, has been reported to favorably modify the clinical conditions of chronic airway diseases. Since there is growing evidence that macrolide antibiotic-resistant bacteria's spreaders in the populations received macrolide therapy, it is strongly desired to develop macrolide antibiotics, which showed only anti-inflammatory action. The present study was designed to examine the influence of clarithromycin (CAM) and its metabolized materials, M-1, M-4 and M-5, on free radical generation from nasal polyp fibroblasts (NPFs) through the choice of nitric oxide (NO), which is one of important effector molecule in the development of airway inflammatory disease in vitro.

Methods

NPFs (5 × 10⁵ cells/ml) were stimulated with 1.0 μg/ml lipopolysaccharide (LPS) in the presence of agents for 24 hours. NO levels in culture supernatants were examined by the Griess method. We also examined the influence of agents on the phosphorylation of MAPKs, NF-κB activation, iNOS mRNA expression and iNOS production in NPFs cultured for 2, 4, 8, and 12 hours, respectively.

Results

The addition of CAM (> 0.4 μg/ml) and M-4 (> 0.04 μg/ml) could suppress NO production from NPFs after LPS stimulation through the suppression of iNOS mRNA expression and NF-κB activation. CAM and M-4 also suppressed phosphorylation of MAPKs, ERK and p38 MAPK, but not JNK, which are increased LPS stimulation. On the other hand, M-1 and M-5 could not inhibit the NO generation, even when 0.1 μg/ml of the agent was added to cell cultures.

Conclusion

The present results may suggest that M-4 will be a good candidate for the agent in the treatment of chronic airway inflammatory diseases, since M-4 did not have antimicribiological effects on gram positive and negative bacteria.