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Potential effects of erythromycin on host defense systems and virulence of Pseudomonas aeruginosa
Y Hirakata1, M Kaku, R Mizukane
1Department of Microbiology, Toho University School of Medicine, Tokyo, Japan.
Abstract:
We evaluated several potential effects of erythromycin (EM) on host defense systems and the virulence of Pseudomonas aeruginosa. Peritoneal macrophages obtained from mice given 250 mg of EM per kg of body weight for 7 days by the intraperitoneal, intravenous, subcutaneous, or oral route produced significantly greater amounts of thymocyte-activating factors. These data suggest that EM enhances the in vivo production of cytokines, such as interleukins 1 and 6. Treatment of P. aeruginosa D4 with subinhibitory concentrations of EM enhanced the association of bacteria with murine Kupffer cells in vitro and increased bacterial clearance from the blood in mice. EM suppressed the in vitro production of exotoxin A, total protease, elastase, and phospholipase C by P. aeruginosa D4; exotoxin A production by P. aeruginosa PA-103; and total protease production by P. aeruginosa B16 and PAO1 in a generally dose-dependent manner. These data demonstrate that EM produces various effects in addition to its direct antimicrobial activity, suggesting that it has potential as an immunomodulator or bacterial virulence-suppressing agent against P. aeruginosa and other infections.
Insights
Erythromycin (EM) boosts immune responses and reduces Pseudomonas aeruginosa virulence. This antibiotic enhances cytokine production and bacterial clearance, while suppressing key toxins, suggesting its potential as an immunomodulator.
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Erythromycin (EM) is a known antibiotic.
- The immunomodulatory and anti-virulence effects of EM require further investigation.
Purpose of the Study:
- To evaluate the effects of erythromycin on host defense mechanisms.
- To assess the impact of erythromycin on Pseudomonas aeruginosa virulence factors.
- To explore the potential of EM as an immunomodulator and virulence-suppressing agent.
Main Methods:
- Mice were administered erythromycin via various routes.
- Peritoneal macrophages were analyzed for cytokine production.
- In vitro and in vivo models were used to assess bacterial association with Kupffer cells and blood clearance.
- In vitro assays measured the suppression of bacterial toxins by erythromycin.
Main Results:
- Erythromycin administration enhanced thymocyte-activating factors and cytokine production (interleukins 1 and 6) in mice.
- Subinhibitory concentrations of EM increased bacterial association with Kupffer cells and improved bacterial clearance.
- EM suppressed the production of exotoxin A, protease, elastase, and phospholipase C by P. aeruginosa in a dose-dependent manner.
Conclusions:
- Erythromycin exhibits immunomodulatory effects by enhancing cytokine production and Kupffer cell association.
- EM significantly reduces the virulence of Pseudomonas aeruginosa by suppressing key toxins.
- Erythromycin demonstrates potential as an immunomodulator and virulence-suppressing agent against P. aeruginosa infections.