Staphylococci induce the production of melanoma differentiation-associated protein-7/IL-24

Mda-7 or IL-24, a novel member of the IL-10 cytokine family has growth inhibitory effect on several human cancers including melanoma via selective apoptosis. Expression of IL-24 could be induced in human PBMC by treatment with phytohaemagglutinin, lypopolisaccharide, IL-4 or influenza A virus infection.

Human PBMC were stimulated with staphylococcal strains originating from clinical specimens, and the appearance of IL-24 at the level of transcription and translation was followed by RT-nested PCR and Western blot assays.

All staphylococcal strains induced IL-24 mRNA. Staphylococci, pathogenic or not, did induce the production of IL-24 in PBMC, but there was a difference between the different staphylococcal strains in their effect on the production of the IL-24 protein.

The pathogenic S. aureus or bacteria belonging to the normal flora of the skin (S. epidermidis and S. saprophyticus) as factors stimulating the production of the Mda-7 protein may be a crucial lead in the investigation of different skin lesions.