Role of NF-kB in TNFRp55-/- macrophage hyper-activation by Yersinia lipopolysaccharide

ARIAS JL.; ELIÇABE R.J.; CARGNELUTTI E.; DI GENARO M.S.

Mendoza

Congreso; XXVI Reunión Científica Anual Sociedad de Biología de Cuyo - I Reunión Dirección Investigación, Ciencia y Técnica Ministerio de Salud ? Gobierno de Mendoza; 2008

Sociedad de Biología de Cuyo

Role of NF-kB in TNFRp55-/-macrophage hyper-activation by Yersinia lipopolysaccharideArias JL, Eliçabe RJ, Cargnelutti E, Di Genaro MS Immunology, FQBF, National University of San Luis. E mail:sdigena@unsl.edu.ar. The inducible transcription factor nuclear factor-kappaB (NF-kB) regulates gene expression during inflammatory and immune responses. Previously, we have demonstrated that TNFRp55 deficiency increases macrophage pro-inflammatory activity induced by Yersinia lipopolysaccharide (LPS) stimulation. The objective of the present work was to investigate whether NF-kB mediates this LPS-induced activation. Peritoneal macrophages from wild-type and TNFRp55-/- C57BL/6 mice were stimulated with Yersinia LPS (10, 100 or 1000 ng). Since the most abundant NF-kB form found in stimulated cells is the p65/p50 heterodimer, we analysed the effect of NF-kB inhibition by incubation of 100 ng LPS-stimulated macrophages with an oligonucleotide sequence of p65 antisense (1microM). Nitric oxide (NO) concentrations were measured in the supernatants by Griess reaction. Higher NO levels were secreted by TNFRp55-/- macrophages stimulated with 100 or 1000 ng LPS (p<0.01 or p<0.005, respectively) compared with wild-type macrophages. In addition, polymixine B treatment, a LPS inhibitor, decreased significantly NO secretion (p<0.003). Interesting, antisense p65 significantly reduced NO secretion of LPS-stimulated TNFRp55-/- macrophages (p<0.05). Taken together, the above evidence implies that TNFRp55 deficiency increases susceptibility of macrophages to LPS stimulation, and NF-kB p65 is a transcriptional regulator of this LPS-induced hyper-activation.