Effect of the tolerance to LPS in the cytokine production and activity of epigenetic enzymes in endotoxemic mice

Abstract

Epigenetic alteration could be associated to pre-conditioning procedures. Chromatin remodeling in LPS tolerance is achieved by histone acetylation. LPS low doses induce a gene hypo-transcription in acute immune response. We investigated how the tolerance to LPS could regulate the epigenetic response in the endotoxemia. Male "Balb C" mice were divided in: C group – control, not manipulated; TD group – induced tolerance and challenged -1mg/Kg LPS during 5 days before the challenge (5mg/Kg LPS); D group – challenged without tolerance - 100μL of NaCl 0.9% during 5 days before the challenge (5mg/kg LPS). Spleens and plasma were collected 48 hours after the challenge. Activity of Histone Acetyltransferases (HAT) and Histone Deacetylases (HDAC) were assessed by colorimetric kits (abcam and biovision); Acetylation of histones H3 and H4 were analyzed by western blotting; cytokines production was measured by ELISA. Results represent the media of 5 animals. Statistical analysis was performed by ANOVA. Production of IL-6, IL-10 and TNF-α was inhibited by the induction of the tolerance compared to D group. HAT and HDAC activities were increased in the TD group compared to C/D groups (p<0.05). H3 acetylated was reduced in TD compared to D. H4 acetylated was maintained at basal levels in TD and D groups. In conclusion, the reduction of cytokines during the tolerance to LPS is associated to H3 acetylation.