Effect of a synthetic lipid immunomodulator on the regulation of the transcription factor NF-kappa B

Macrophage activation plays a central role in host defense against a variet y of pathogens via inducible messengers. The transcription factor NF-kappaB controls the synthesis of cytokines involved in immune responses. In quies cent cells, NF-kappaB is located in the cytosol bound to an inhibitor I kap paB. Upon appropriate signal, NF-kappaB translocates to the nucleus and bin ds to DNA. The present study investigated the involvement of an immunomodul ator, (diHDA-glycerol) on the NF-kappaB/I kappaB complex. Results were comp ared to those obtained with lipopolysaccharide (LPS) as a major virulence f actor in bacterial sepsis. Data showed that exposure of J774.1 cells either to LPS or diHDA-glycerol substantially increased with time the nuclear lev els of NF-kappaB complexes. Antibodies to various NF-kappaB proteins supers hifted p50, p65 and to a lesser extent c-rel. Western blot analyses showed a rapid cytosolic I kappaB-alpha turn over following LPS exposure in contra st to diHDA-glycerol treatment. Further experiments investigated the involv ement of protein kinase C (PKC) by using two inhibitors, staurosporine and H7. Pretreatment of J774.1 with either inhibitor prior to diHDA-glycerol or LPS exposure decreased NF-kappaB activation. Our results indicate that diH DA-glycerol was acting on NF-kappaB through I kappaB regulative mechanisms differing from those used by LPS. DiHDA-glycerol is likely acting on many o ther transcription factors targeting distinct genes implied in up regulatio n of the immune system.