Adipose‐Specific Lipin‐1 Overexpression Renders Hepatic Ferroptosis and Exacerbates Alcoholic Steatohepatitis in Mice

Abstract

Lipin‐1 is a Mg 2+ ‐dependent phosphatidic acid phosphohydrolase involved in the generation of diacylglycerol during synthesis of phospholipids and triglycerides. Ethanol‐mediated inhibitory effects on adipose‐specific lipin‐1 expression were associated with experimental steatohepatitis in rodents. In the present study, using an adipose‐specific lipin‐1 overexpression transgenic ( Lpin1 ‐Tg) mouse model, we tested a hypothesis that adipose‐specific lipin‐1 overexpression in mice might dampen ethanol‐induced liver damage. Experimental alcoholic steatohepatitis was induced by pair‐feeding ethanol to Lpin1 ‐Tg and wild‐type (WT) mice using the chronic‐plus‐binge ethanol feeding protocol. Unexpectedly, following the chronic‐plus‐binge ethanol challenge, Lpin1 ‐Tg mice exhibited much more pronounced steatosis, exacerbated inflammation, augmented elevation of serum liver enzymes, hepatobiliary damage, and fibrogenic responses compared with the WT mice. Mechanistically, overexpression of adipose lipin‐1 in mice facilitated the onset of hepatic ferroptosis, which is an iron‐dependent form of cell death, and subsequently induced ferroptotic liver damage in mice under ethanol exposure. Concurrently, adipose lipin‐1 overexpression induced defective adiponectin signaling pathways in ethanol‐fed mice. Conclusion : We identified ferroptosis as a mechanism in mediating the detrimental effects of adipose‐specific lipin‐1 overexpression in mice under chronic‐plus‐binge ethanol exposure. Our present study sheds light on potential therapeutic approaches for the prevention and treatment of human alcoholic steatohepatitis.

Intestinal SIRT1 Deficiency Protects Mice from Ethanol-Induced Liver Injury by Mitigating Ferroptosis

“…Of interest, augmented iron concentrations were found in the livers of ethanol-fed female mice compared with ethanol-fed male mice. 15,37 It is possible that the sex-specific responses in hepatic iron contents may lead to the sex differences in ferroptosis and liver damage in mice after ethanol challenge. The detailed mechanisms underlying sex differences in ferroptosis and their relationship with ethanol-induced liver damage are currently under investigation in our laboratory.…”

“…5,6 Hematoxylin and eosin staining and Prussian Blue staining were performed with a commercial staining kit (Sigma, St. Louis, MO). 15 Immunohistochemistry staining of myeloperoxidase (MPO) was performed with a primary MPO antibody (Biocare Medical, Pacheco, CA) and a horseradish peroxidaseebased secondary detection kit (Vector Laboratories, Burlingame, CA).…”

“…5,6,12 Iron Assay Iron concentrations were measured with an Iron Assay Kit (ab83366; Abcam) according to the manufacturer's instructions. 5,15 GSH and NADP þ and NADPH Assays Hepatic glutathione (GSH) level was assessed with a GSH luminesce assay kit (Promega, Madison, WI) according to the manufacturer's instructions. 15 Hepatic nicotinamide adenine dinucleotide phosphate (NADP) þ and NADPH concentrations were assessed with a NADPH colorimetric assay kit (Abcam).…”

“…Liver glutathione peroxidase (GPX) enzyme activity was analyzed with a commercialized colorimetric assay kit (Biovision). 15…”

“…Primary antibodies and secondary antibodies linked with horseradish peroxidase were used for detection as previously described. 5,6,15…”