Metabolic oxidative stress via
CYP2E1 can act as a second hit in NASH progression. Our previous studies have shown that oxidative stress in NASH causes higher
leptin levels and induces
purinergic receptor X7 (P2X7r). We tested the hypothesis that higher circulating
leptin due to CYP2E1-mediated oxidative stress induces P2X7r. P2X7r in turn activates stellate cells and causes increased proliferation via modulating Glut4, the
glucose transporter, and increased intracellular
glucose. Using a high fat diet-fed
NAFLD model where
bromodichloromethane (BDCM) was administered to induce CYP2E1-mediated oxidative stress, we show that P2X7r expression and
protein levels were
leptin and
CYP2E1 dependent. P2X7r KO mice had significantly decreased stellate cell proliferation. Human NASH livers showed marked increase in P2X7r, and Glut4 in α-SMA positive cells. NASH livers had significant increase in
Glut4 protein and phosphorylated AKT, needed for Glut4 translocation while
leptin KO and P2X7r KO mice showed marked decrease in Glut4 levels primarily in stellate cells. Mechanistically stellate cells showed increase in phosphorylated AKT,
Glut4 protein and localization in the membrane following administration of P2X7r agonist or leptin+P2X7r agonist, while use of P2X7r antagonist or AKT inhibitor attenuated the response suggesting that leptin-P2X7r axis in concert but not
leptin alone is responsible for the Glut4 induction and translocation. Finally P2X7r-agonist and
leptin caused an increase in intracellular
glucose and consumption by increasing the activity of
hexokinase. In conclusion, the study shows a novel role of
leptin-induced P2X7r in modulating Glut4 induction and translocation in hepatic stellate cells, that are key to NASH progression.