Kv1.3 knockdown attenuates alcohol-related liver injury in mice through induction of tryptamine.

Alcohol-related liver disease (ALD) refers to a spectrum of liver diseases caused by chronic or acute excessive alcohol consumption. Excess alcohol consumption and dysregulated immunometabolism are the major contributors to the disease progression. The pathogenesis of ALD remains unclear with macrophage activity playing a key role in disease development. Kv1.3 potassium channel is essential for the regulation of macrophage function. In this study, we investigated whether Kv1.3 channels influenced the progression of ALD by modulating macrophage function. A murine model of ALD was established in male mice. We showed that Kv1.3 knockdown significantly attenuated alcohol-induced liver injury, lipid deposition, and inflammatory responses in ALD mice. Metabolomic analysis revealed that Kv1.3 knockdown significantly increased the levels of tryptamine, a tryptophan metabolite, in the liver of ALD mice. During the last 5 days of the EtOH feeding period, injection of exogenous tryptamine (1, 10, 20 mg·kg^-1·d^-1, i.p.) notably alleviated ethanol-induced liver steatosis and inflammation in ALD mice. In LPS-challenged RAW264.7 cells, tryptamine (62.5, 125, 250 μM) dose-dependently suppressed the secretion of pro-inflammatory cytokines IL-6, IL-1β and TNF-α. RNA-seq analysis of RAW264.7 cells revealed that tryptamine treatment significantly altered Toll-like receptor and NF-κB signaling pathways. We conclude that in the ALD mice, Kv1.3 negatively regulates tryptamine levels, which inhibits macrophage activation and reduces the inflammatory responses through the TLR4/NF-κB signaling pathway. Our results offer new targets and intervention strategies for the prevention and treatment of ALD.