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Inflammatory effects of Salmonella typhimurium porins
F Galdiero1, M A Tufano, M Galdiero
1Istituto di Microbiologia, I Facoltà di Medicina e Chirurgia, Università di Napoli, Naples, Italy.
Abstract:
The inflammatory activity of porins purified from Salmonella typhimurium has been investigated. Porins (0.3 to 30 micrograms) injected into the rat paw induced a dose-related edema that was not due to lipopolysaccharide contamination and did not appear to be dependent on the activation of the complement system. The edema induced by 30 micrograms of porins was comparable to that caused by 1 mg of carrageenin and was inhibited by indomethacin (5 mg/kg) and dexamethasone (0.1 mg/kg). Porins (1 to 10 micrograms/ml) induced a concentration-related release of histamine from rat peritoneal cells. These results are discussed in the light of the possible pathogenic role of porins in infections.
Insights
Salmonella typhimurium porins cause inflammation and edema in rats, independent of LPS or complement. This inflammatory activity, mediated by histamine release, suggests a pathogenic role for porins in infections.
Area of Science:
- Microbiology
- Immunology
- Pharmacology
Background:
- Porins are outer membrane proteins of Gram-negative bacteria like Salmonella typhimurium.
- Their role in bacterial pathogenesis and host immune response requires further elucidation.
Purpose of the Study:
- To investigate the inflammatory potential of purified Salmonella typhimurium porins.
- To determine the mechanisms underlying porin-induced inflammation.
Main Methods:
- Purified porins were injected into rat paws to assess edema formation.
- Histamine release from rat peritoneal cells was measured in response to porins.
- The effects of anti-inflammatory drugs (indomethacin, dexamethasone) were evaluated.
Main Results:
- Porins induced a dose-dependent edema in rat paws, distinct from lipopolysaccharide contamination.
- The edema was not dependent on complement system activation.
- Porins stimulated a concentration-dependent release of histamine from peritoneal cells.
- Indomethacin and dexamethasone significantly inhibited porin-induced edema.
Conclusions:
- Salmonella typhimurium porins possess intrinsic inflammatory activity.
- Porins contribute to inflammation through histamine release, suggesting a pathogenic role in infections.