Diosmetin alleviates liver inflammation by improving liver sinusoidal endothelial cell dysfunction.

Background & Aims: Tumor necrosis factor-alpha (TNFalpha) induces pro-inflammatory activation in liver sinusoidal endothelial cells (LSEC) and liver inflammation. However, knowledge about whether modulating LSEC activation can alleviate liver inflammation is scarce. This study aimed to establish and validate an animal model mimicking LSEC dysfunction observed in patients with elevated plasma levels of TNFalpha, and explore whether vasoactive flavonoid diosmetin could serve as a therapeutic agent for liver inflammation. Approach & Results: Genetic deletion of Mcpip1 in myeloid leukocytes (Mcpip1fl/flLysMCre) resulted in the development of systemic and liver inflammation in mice. Symptoms were compared with those in liver samples from obese humans with elevated TNFalpha. Mice were treated with diosmetin, and its effectiveness in alleviating liver inflammation was evaluated. Elevated TNFalpha correlated with reduced Mcpip1 expression in peripheral blood mononuclear cells and LSEC dysfunction in obese patients. Mcpip1 knockout in myeloid cells in mice replicated molecular signs observed in human samples. Diosmetin efficiently reduced LSEC activation and liver inflammation in Mcpip1fl/flLysMCre mice. Diosmetin's effects may stem from inhibiting NF-kappaB-p50 subunit production in TNFalpha-activated endothelial cells. Conclusions: Diosmetin treatment efficiently restricted liver inflammation, despite ongoing systemic inflammation, by diminishing LSEC dysfunction. Mcpip1fl/flLysMCre mice mimic symptoms of liver inflammation observed in humans and can be useful in studies on new anti-inflammatory therapies for the liver. We show that diosmetin, a vasoactive flavonoid that is successfully used in the clinic to treat chronic venous insufficiency, has also strong anti-inflammatory properties in the liver. This suggests that diosmetin treatment may be tested in humans as a supportive therapy for liver inflammation. ### Competing Interest Statement The authors have declared no competing interest.