The JAK1 Inhibitor Upadacitinib Curbs Acute Liver Failure via Suppressing IFN-γ/JAK1/STAT1 and TNF-α/NF-κB/MAPK Pathways and Modulating Bax/Bcl-2 Ratio.

Acute liver failure (ALF) is a fulminant hepatic syndrome characterized by rapid hepatocellular destruction, severe impairment of liver function, and high mortality. Effective pharmacological interventions capable of limiting early hepatic injury remain lacking. Upadacitinib (UPA), a selective inhibitor for Janus kinase 1 (JAK1) with established anti-inflammatory activity, has not previously been investigated in experimental ALF. Consequently, the current study examined the hepatoprotective potential and underlying mechanisms of UPA in a lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced ALF murine model. Mice were pretreated with UPA (10 or 20 mg/kg) prior to LPS/D-GalN challenge. UPA significantly attenuated liver injury, as demonstrated by marked reductions in serum ALT, AST, ALP, and γ-GT levels, together with substantial improvement in hepatic histopathology, attenuation of necroinflammation, and reduction in neutrophil accumulation. UPA also restored hepatic redox balance through reduction in lipid peroxidation and nitrosative stress, alongside enhancement of antioxidant capacity. Mechanistically, UPA suppressed IFN-γ/JAK1/STAT1 signaling and downregulated NF-κB p65 and inducible nitric oxide synthase (iNOS) expression, with subsequent reduction in hepatic TNF-α production. In parallel, UPA inhibited MAPK pathway activation, including ERK1/2, JNK, and p38 signaling. Moreover, UPA attenuated hepatocellular apoptosis through suppression of active caspase-3 and Bax expression with restoration of Bcl-2 levels. The 20 mg/kg dose consistently produced greater biochemical, molecular, and histopathological protection than the lower dose. In conclusion, UPA confers significant protection against LPS/D-GalN-induced ALF through coordinated suppression of oxidative stress, inflammatory signaling, and apoptosis, primarily associated with inhibition of the IFN-γ/JAK1/STAT1 and TNF-α/NF-κB/MAPK pathways and modulation of the Bax/Bcl-2 ratio, underscoring its viability as a promising therapeutic candidate for ALF.