Metformin and empagliflozin combined therapy may have complementary effects that go beyond the well-recognized targets of their monotherapy through AMPK activation. Therefore, the current study was designed to investigate for the first time the hepatoprotective effects of such combination therapy in the carbon tetrachloride (CCl₄)-induced hepatic fibrosis model in mice.

Determination of liver enzymes and the liver content of oxidative stress parameters, and hydroxyproline were performed biochemically. ELISA was performed to measure PDGF-BB, TNF-α, TGF-β, TIMP-1, AMPK, p-mTOR, NF-κB P65 binding activity, p38 MAPKα, JNK1/2 and ERK1/2. Real-time qPCR was conducted to determine Col1a1 and α-SMA. In addition, histopathological examination using H&E and Masson's trichrome stain were performed for determination of histopathological changes.

Empagliflozin inhibited the activation of p38 MAPK and ERK1/2 and exhibited a weak AMPKα stimulation. On the other hand, metformin exerted a more robust stimulatory action on the AMPKα that was accompanied by a notable decrease in the NF-κB nuclear binding activity and a decline in the p-mTOR levels. Nevertheless, the effect of metformin on MAPK kinases was insignificant. Our results revealed that blunting p38 MAPKα and ERK1/2 activities by empagliflozin enhanced the antifibrotic effect of metformin and augmented its AMPK-induced NF-κB inactivation.

As diabetes is one of the most common risk factors for liver fibrosis, the use of antidiabetic drugs is expected to improve therapeutic outcome. Therefore, metformin/empagliflozin combined therapy could be promising in preventing hepatic inflammation and fibrosis via exhibiting complementary effects particularly in diabetic patients.