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The aim of this study was to verify whether Salmonella typhimurium porins can affect the expression of interleukin-1 (IL-1) and interleukin-6 (IL-6) genes. Human monocytes were treated with porins, and total RNAs were analysed by Northern blotting to evaluate the expression of IL-1 alpha, IL-1 beta and IL-6 in both treated and untreated cell cultures. Porins induced a significant increase in IL-1 and IL-6 transcripts. This increase was related to the dose of porins, and it peaked 5 hr after treatment. The same results were obtained when polymyxin B was added to the porin preparation to eliminate eventual traces of lipopolysaccharide (LPS) associated with porins. The porins-mediated increase in interleukin transcripts did not require de novo protein synthesis, and it was because of the enhanced half-life of IL-1 and IL-6 mRNAs, rather an increased rate of gene transcription. These data suggest that porins may affect inflammatory and immunological responses by enhancing the expression of cytokine genes.

Nine new cytotoxic steroidal glycosides 1-9 have been isolated from the starfish #Fromia monilis$ collected off New Caledonia. Structures of these compounds, which include four mono- (1-4), two di- (5,6), and three tri-glycosides (7-9), were elucidated through spectral interpretation. Monilosides G (7), H (8), and I (9) are the first tri-glycosides to be found amoung the group of glycosides of polyhydroxilated steroids from starfishes. (Résumé d'auteur)

A study was made of K+, Na+, Ca++ and Mg++ binding and ion-exchange properties of S-layer proteins from Bacillus subtilis. Our results indicate that the proteins of S-layer have two binding sites with pK of 3.17 and 2.41. To study the capacity of S-layer subunits to bind K+, Na+, Ca++ and Mg++, potentiometric titrations were performed according to Albert on proteins in solution in the presence and the absence of cations. It appears that the proteins possess dissociable groups with different affinity for various cations.

In this study, we describe the role of porins extracted from the outer membrane of S. typhimurium on the interaction with the host organism. The tests were performed on CD-1 mice immunized both with whole S. typhimurium cells and with purified porins. The antibody titres obtained in mice treated with purified porins and in those treated with whole Salmonella are 1/320 and 1/80 respectively. Cell-mediated response was found to be stimulated in both mice groups: our results show that T lymphocytes determine an increase in H3-thymidine incorporation and MIF production. An increase in lymphocytes with membrane immunoglobulins was observed in the lymphocyte population from the spleens of the treated mice. Purified porins added to macrophages cultures exerted a toxic effect at concentrations between 10 and 20 micrograms/ml. Subinhibiting concentrations (5 micrograms/ml) led to modifications in the surface tension of macrophages layers adhering to the slides. Moreover, subinhibiting porins concentrations were found to modify macrophage functionality as shown by evaluation of the phagocytic index and of intracellular killing, both of which were found to have diminished with respect to controls. When purified porins were added in vitro to populations enriched with T and B lymphocytes, at concentrations between 1 and 5 micrograms/ml they were found to be mitogenic with respect to B lymphocytes. The results we obtained showed that lymphocytes with IgM increase in porins tests. Eventually, purified porins added to Hela and Hep-2 cells were shown to exert a toxic effect which became detectable in the final concentration of 5 micrograms/ml and 1 micrograms/ml for Hela and Hep-2 cells respectively.