Rapid turnover of the intestinal epithelium is a critical strategy to balance the uptake of nutrients and defend against environmental insults, whereas inappropriate death promotes the spread of inflammation. PPARα is highly expressed in the small intestine and regulates the absorption of dietary lipids. However, as a key mediator of inflammation, the impact of intestinal PPARα signaling on cell death pathways is unknown. Here, we show that Pparα deficiency of intestinal epithelium up-regulates necroptosis signals, disrupts the gut vascular barrier, and promotes LPS translocation into the liver. Intestinal Pparα deficiency drives age-related hepatic steatosis and aggravates hepatic fibrosis induced by a high-fat plus high-sucrose diet (HFHS). PPARα levels correlate with TRIM38 and MLKL in the human ileum. Inhibition of PPARα up-regulates necroptosis signals in the intestinal organoids triggered by TNF-α and LPS stimuli via TRIM38/TRIF and CREB3L3/MLKL pathways. Butyric acid ameliorates hepatic steatosis induced by intestinal Pparα deficiency through the inhibition of necroptosis. Our data suggest that intestinal PPARα is essential for the maintenance of microenvironmental homeostasis and the spread of inflammation via the gut-liver axis.

Aim To investigate the interactions be-tween the neuroinflammation caused by lipopolysaccha-ride(LPS) and brain CYP2E1.Methods The human cholinergic neuroblastoma cell line IMR-32 was treated with LPS ( 0.1 mg · L-1 , 1.0 mg · L-1 ) , and the LDH and SOD activities were determined after 24 h in-cubation .In order to determine the roles of MAPK sig-naling pathway in the regulation of CYP 2E1 by LPS, the IMR-32 cells were treated with p38 pathway inhibi-tor SB203580 or ERK pathway inhibitor U 0126 for 45 min before the incubation with LPS .The human do-paminergic neuroblastoma cell line SH-SY5Y with CYP2 E1 over-expression was established . The LDH and SOD activities were determined in SH-SY5 Y cells over-expressed CYP2 E1 and control cells treated with LPS(0.1 mg· L-1 , 1.0 mg· L-1 ) for 24 h.Results
The levels of LDH in IMR-32 cells treated with high-dose LPS were increased by 1.38-fold ( P <0.01 ) compared with the control group , and the levels of SOD reduced by 15.0%( P <0.01 ) .Compared with the control, CYP2E1 mRNA and protein levels in IMR-32 cells treated with high-dose LPS were increased by 1.25-fold(P<0.01) and 1.19-fold(P<0.05).The up-regulation of CYP2E1 by LPS could be attenuated by SB203580 and U0126 pretreatment.Compared with the control cells, the CYP2E1 over-expression in-creased LDH levels by 1.28-fold ( P<0.01 ) and de-creased SOD levels by 3.53-fold ( P<0.01 ) after the low-dose of LPS treatment .The CYP2E1 over-expres-sion increased LDH levels by 1.54-fold ( P <0.01 ) and decreased SOD levels by 2.17-fold( P<0.01) af-ter the high-dose of LPS treatment , compared with the control cells.Conclusions LPS can induce CYP2E1 mRNA and protein levels , and the p38 and ERK sig-naling pathway may be involved in the regulation .The elevated CYP2 E1 levels aggravate the damage to neuro-nal cells caused by LPS .Brain CYP2E1 may be an im-portant contributing factor to the pathological process of neuroinflammatory injury .