Combination therapy with clinically approved PPARα/δ/γ subtype-selective agonists pemafibrate, seladelpar, and pioglitazone in a 4-week diet-induced early-stage MASLD mouse model.

Numerous treatments for metabolic dysfunction-associated steatohepatitis (MASH) have been developed, but none of them have been clinically approved except for resmetirom and semaglutide. One of the most promising drugs targets peroxisome proliferator-activated receptors α/δ/γ (PPARα/δ/γ). Although several PPAR dual/pan agonists have shown efficacy in treating lipid/glucose metabolism disorders, they remain unapproved because of ineffectiveness or serious side effects. The therapeutic effects of approved/safe PPARα/δ/γ-selective agonists (pemafibrate, seladelpar, and pioglitazone), administered alone or in combination, were investigated in an early-stage metabolic dysfunction-associated steatotic liver disease (MASLD) model. Adult mice were fed a high-fat/high-cholesterol/high-cholic acid diet with 1% cyclodextrin water ad libitum, and specific MASLD-like symptoms (hepatic steatosis, inflammation, and limited fibrosis) developed within 4 weeks. Each agonist or their combination was administered with food at a dose intended not to cause significant weight loss. Blood concentrations of each agonist during the combination therapies were comparable to those during monotherapy. Liver histological analysis showed that pioglitazone alone and the combination of pemafibrate/seladelpar or all three agonists improved fibrosis, but they had no effect on triglyceride accumulation or inflammation. Expression analysis of inflammatory and fibrotic marker genes in the liver revealed that pemafibrate or pioglitazone alone, or any combination of the two drugs, reduced the expression level of these genes. MALDI mass spectrometry imaging revealed that specific triglyceride species accumulated in the liver of mice with MASLD and they were reduced by pioglitazone or the combination of seladelpar/pioglitazone. Collectively, the combination of seladelpar and pioglitazone is a promising therapeutic option for early-stage MASLD.