miR-27b-3p aggravates steatohepatitis progression by targeting the Nrf2/HO-1 pathway

Objective：This study aimed to investigate whether miR-27b-3p regulates oxidative stress and inflammatory responses through the Nrf2/HO-1 signaling pathway during the progression of fatty liver.Methods：Liver tissues from dairy cows with fatty liver and high-fat diet (HFD)induced fatty liver mice were collected to evaluate lipid accumulation, oxidative stress, inflammation, and the expression of miR-27b-3p and Nrf2/HO-1 pathway components.An in vitro steatosis model was established in AML-12 hepatocytes using palmitic acid (PA).Oxidative stress markers (ROS, SOD, and MDA), inflammatory cytokines (IL-1β, IL-6, and TNF-α), and apoptosis-related proteins were assessed.Bioinformatic prediction and dual-luciferase reporter assays were used to determine the targeting relationship between miR-27b-3p and Nrf2.Gain-and loss-of-function experiments were performed using miR-27b-3p mimics and inhibitors to evaluate its regulatory effects on the Nrf2/HO-1 pathway and downstream cellular responses.Results：Fatty liver tissues from dairy cows and HFD-fed mice exhibited significant lipid deposition, enhanced oxidative stress, and elevated inflammatory responses, accompanied by increased miR-27b-3p expression and reduced Nrf2/HO-1 signaling activity.Similar alterations were observed in PA-treated AML-12 cells.Bioinformatic analysis and dual-luciferase assays confirmed that miR-27b-3p directly binds to the 3′ untranslated region of Nrf2.Inhibition of miR-27b-3p restored Nrf2 and HO-1 expression, reduced ROS and MDA levels, increased SOD activity, suppressed NF-κB activation, decreased pro-inflammatory cytokine production, and alleviated apoptosis.