Catholic University of Korea researchers link gut IgA to liver inflammation

Excessive alcohol consumption can cause immunoglobulin A (IgA)—an antibody typically responsible for defending mucosal surfaces in the gut and respiratory tract against bacteria and viruses—to migrate to the liver and intensify inflammatory responses by immune cells, according to a study published in the international journal Gut.

Identification of the Gut-Liver IgA Immune Axis

Researchers at the Catholic University of Korea Seoul St. Mary’s Hospital identified what they termed the gut-liver IgA immune axis in alcohol-associated liver disease. The research team included Sung Pil-soo, Tak Kwon-yong, and Kim Min-gu. While previous medical knowledge established that patients with alcohol-associated liver disease often display elevated blood IgA levels, it remained unclear whether this increase was merely a byproduct of the condition or an active driver of liver inflammation and tissue damage.

Combining Patient Tissue Analysis With Animal Models

To uncover the mechanism, the research team combined human blood and liver tissue analysis with animal models, spatial transcriptomics, and experiments involving human immune cells. Investigators concentrated specifically on monocytes and macrophages, which clear foreign substances and aid in tissue repair but can trigger inflammation if they become hyperactive. The analysis showed that higher blood IgA levels correlated with greater IgA accumulation inside liver tissue, where the antibody bound directly to monocytes and macrophages. This binding pattern aligned with elevated levels of interleukin-1 beta (IL-1β), a key protein associated with inflammatory responses.

Impact of Immune Cell Modulation in Animal Tests

Tests conducted on animal models administered with alcohol demonstrated matching increases in blood IgA, liver macrophage IgA binding, IL-1β expression, and overall liver injury. When the research team administered FTY720—a drug that regulates immune cell movement—levels of blood IgA and IgA-bound liver macrophages decreased significantly, alongside measurable reductions in inflammation and liver damage. The findings indicate that the antibody does more than serve as a diagnostic marker, actively participating in the progression of alcohol-associated liver disease through its interactions with liver immune cells.