Pnpla3 silencing with antisense oligonucleotides ameliorates nonalcoholic steatohepatitis and fibrosis in Pnpla3 I148M knock-in mice

Abstract

Objective Nonalcoholic fatty liver disease (NAFLD) is becoming a leading cause of advanced chronic liver disease. The progression of NAFLD, including nonalcoholic steatohepatitis (NASH), has a strong genetic component, and the most robust contributor is the patatin-like phospholipase domain-containing 3 ( PNPLA3 ) rs738409 encoding the 148M protein sequence variant. We hypothesized that suppressing the expression of the PNPLA3 148M mutant protein would exert a beneficial effect on the entire spectrum of NAFLD. Methods We examined the effects of liver-targeted GalNAc 3 -conjugated antisense oligonucleotide (ASO)-mediated silencing of Pnpla3 in a knock-in mouse model in which we introduced the human PNPLA3 I148M mutation. Results ASO-mediated silencing of Pnpla3 reduced liver steatosis ( p = 0.038) in homozygous Pnpla3 148M/M knock-in mutant mice but not in wild-type littermates fed a steatogenic high-sucrose diet. In mice fed a NASH-inducing diet, ASO-mediated silencing of Pnpla3 reduced liver steatosis score and NAFLD activity score independent of the Pnpla3 genotype, while reductions in liver inflammation score ( p = 0.018) and fibrosis stage ( p = 0.031) were observed only in the Pnpla3 knock-in 148M/M mutant mice. These responses were accompanied by reduced liver levels of Mcp1 ( p = 0.026) and Timp2 ( p = 0.007) specifically in the mutant knock-in mice. This may reduce levels of chemokine attracting inflammatory cells and increase the collagenolytic activity during tissue regeneration. Conclusion This study provides the first evidence that a Pnpla3 ASO therapy can improve all features of NAFLD, including liver fibrosis, and suppress the expression of a strong innate genetic risk factor, Pnpla3 148M, which may open up a precision medicine approach in NASH.

Metabolic regulation of hepatic PNPLA3 expression and severity of liver fibrosis in patients with NASH

“…Although our patient cohort is relatively small (n = 26) compared to other previous studies, serum liver enzymes such as ALT and AST (Table ) are consistently increased in NASH patients with the PNPLA3 genetic variant along with the steatosis grade, inflammation, ballooning and NAS score, compared to the C/C carriers (Table ). Over the last decade the genetic polymorphism of PNPLA3, known as I148M, was strongly linked to non‐alcoholic fatty liver disease (NAFLD) and to the progression towards severity of liver diseases, such as cirrhosis and liver cancer . Notably, the present study strongly supports our previous findings in vitro with primary human HSCs, and therefore contributes to highlight the importance to group patients according to the different PNPLA3 genotype.…”

The Underpinnings of PNPLA3‐Mediated Fatty Liver Emerge

“…The authors go on to show that short hairpin RNA–mediated knockdown or expression of fusion constructs that target PNPLA3 I148M for proteasomal degradation reduced protein abundance and normalized hepatic TAG levels. In support, recent studies also show that knockdown of PNPLA3 in livers of mice homozygous for I148M largely negates the detrimental effects of a NASH‐promoting diet . Thus, this work highlights the potential of reducing PNPLA3 protein levels in I148M carriers as a means to alleviate steatosis.…”

“…In support, recent studies also show that knockdown of PNPLA3 in livers of mice homozygous for I148M largely negates the detrimental effects of a NASH-promoting diet. (7) Thus, this work highlights the potential of reducing PNPLA3 protein levels in I148M carriers as a means to alleviate steatosis.…”

HSD17B13 as a promising therapeutic target against chronic liver disease

“…In brief, the role of HSD17B13 in human physiology and the molecular mechanism behind the genetic protection are far from being clear. The interplay between HSD17B13 and PNPLA3 is a further complicating issue, especially given that PNPLA3 itself is a potential target for therapeutic inhibition in the context of FLD . It will be important to determine what proportion of the protective effect of the HSD17B13 variant is mediated by PNPLA3 downregulation.…”