ABHD5 overexpression protects PNPLA3-148M primary human hepatocytes from steatosis in liver chimeric mice with NAFLD

Background and Aims The methionine variant of patatin-like phospholipase domain-containing protein 3 (PNPLA3-148M) is associated with advanced fatty liver disease. Previous studies have proposed a mechanism where PNPLA3-148M sequesters alpha/beta-hydrolase domain containing 5 (ABHD5), thereby impairing adipose triglyceride lipase (ATGL) activity on lipid droplets. Here we test the hypothesis that ABHD5 overexpression in primary human hepatocytes (PHH) with PNPLA3-148M can overcome sequestration and improve steatosis in liver chimeric mice with NAFLD.

Methods PHH from a homozygous PNPLA3-148M donor (PHH-148M) were lentivirally transduced with ABHD5 prior to transplantation into immunodeficient Fah-/- liver injury mice. To link the PNPLA3 genotype to advanced steatotic liver disease, PNPLA3-148M and ABHD5 were co-transduced in PHH from a homozygous PNPLA3-148I donor (PHH-148I). After reaching peak liver humanization animals were challenged with a Western-style diet (WD, 60% kcal from lard, 23% sucrose, 0.03% cholesterol) for four weeks.

Results PHH-148M developed more severe steatosis in response to WD than PHH-148I, which was confirmed in PNPLA3-148M transduced PHH-148I that also displayed widespread microvesicular steatosis. ABHD5 overexpression in PHH-148I did not affect steatosis. In contrast, ABHD5 overexpression in PHH-148M resulted in>4-fold lower steatosis compared to control mice. While ABHD5 minimally improved steatosis in PNPLA3-148M transduced PHH-148I, it nearly completely resolved microvesicular steatosis.

Conclusion These findings support a model where sequestration of ABHD5 by PNPLA3-148M impairs triglyceride lipolysis by ATGL, leading to excess steatosis upon hypercaloric feeding. Overexpression liver chimeras with PHH-148I or PHH-148M grafts provide mechanistic insights on how PNPLA3 and ATGL maintain human lipid homeostasis under hypercaloric conditions.

Publication History

Article published online:
23 January 2024