The Impact of Air Pollution on the Lung–Gut–Liver Axis: Oxidative Stress and Its Role in Liver Disease

The expression “lung–gut–liver axis” refers to the interconnected processes occurring in the lungs, gastrointestinal tract, and liver, particularly in relation to immune function, microbial regulation, and metabolic responses. Over the past decade, growing concern has emerged regarding the detrimental impact of air pollution on liver disease. Air pollutants, including particulate matter (PM) and chemical gases such as nitrogen oxides (NOx), can influence the microbiome in the lungs and gut by generating reactive oxygen species (ROS), which induce oxidative stress and local inflammation. This redox imbalance leads to the production of altered secondary microbial metabolites, potentially disrupting both the alveolar–capillary and gut barriers. Under these conditions, microbes and their metabolites can translocate to the liver, triggering inflammation and contributing to liver diseases, particularly metabolic dysfunction-associated steatotic liver disease (MASLD), cirrhosis, and hepatocellular carcinoma (HCC). This manuscript aims to review recent findings on the impact of air pollution on liver disease pathogenesis, exploring the molecular, genetic, and microbiome-related mechanisms underlying lung–gut–liver interactions, providing insights into potential strategies to prevent or mitigate liver disease progression.