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

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.

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.

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. Conversely, overexpression of miR-27b-3p further inhibited Nrf2/HO-1 signaling and exacerbated oxidative stress, inflammation, and cell injury.

miR-27b-3p promotes the progression of fatty liver toward steatohepatitis by directly targeting Nrf2 and suppressing the Nrf2/HO-1 antioxidant pathway, thereby enhancing oxidative stress, inflammatory responses, and hepatocyte apoptosis. These findings identify miR-27b-3p as a key upstream regulator of redox imbalance in fatty liver and suggest that targeting miR-27b-3p may represent a promising strategy for the prevention and treatment of bovine fatty liver disease.