Gut bacterium shows promise as probiotic approach to lupus

Researchers at UT Health San Antonio have identified a gut bacterium that may point toward a probiotic treatment strategy for lupus. The finding matters because systemic lupus erythematosus has no cure, and current therapies focus on controlling symptoms and limiting organ damage.

The work, published in Nature Communications, centers on Faecalibacterium prausnitzii, a bacterium the UT Health San Antonio team said is reduced in the gut microbiomes of lupus patients. In animal models, adding the bacterium back sharply lowered markers associated with the disease, according to the researchers.

Laurence Morel, a professor and Zachary Foundation Distinguished Chair in the Department of Microbiology, Immunology and Molecular Genetics, said the study marks the first time lupus researchers have identified a depleted bacterium that appears to help when restored. Morel led the study with Yong Ge, an assistant professor in the same department at UT San Antonio’s Joe R. and Teresa Lozano Long School of Medicine.

How the bacterium may affect inflammation

Systemic lupus erythematosus is the most common form of lupus and affects about 1.5 million Americans, according to UT Health San Antonio. The disease occurs when the immune system attacks healthy tissues and organs, causing inflammation that can involve the joints, skin, brain, heart, lungs and other organs.

UT Health San Antonio said standard treatment often relies on immunosuppressants, including steroids. Those drugs can be effective, but the researchers said they can bring side effects such as weight gain, swelling and cardiovascular complications, while also making patients more vulnerable to infections. The university said infection is a major cause of death in lupus.

Scientists have studied ties between the gut microbiome and lupus for about a decade, according to the research team. Earlier studies found that the gut microbes of people with lupus differ from those of healthy people, and at least three bacterial strains have been linked to disease progression.

Ge’s earlier work found that F. prausnitzii helps gut microbes break down dietary fiber in healthy conditions, according to UT Health San Antonio. The bacterium produces butyrate, a short-chain fatty acid that helps reduce inflammation and supplies energy to cells that line the colon.

Those colon-lining cells help maintain mucin, the protective barrier between the gut and the rest of the body, the researchers said. When levels of F. prausnitzii fall, fiber is processed less effectively, short-chain fatty acid levels decline and the gut environment can become more inflammatory, Ge said.

Early findings, not an over-the-counter answer

The team reported that restoring the bacterium partly improved immune regulation in the animal models and showed beneficial effects involving the kidneys and spleen. Ge said the exact mechanism remains unclear, but the bacterium appears to act indirectly by changing the broader microbiome so it digests more fiber and less mucin.

The researchers cautioned that F. prausnitzii is not a typical probiotic found in most store-bought supplements. UT Health San Antonio said the bacterium has strain-specific properties, is highly sensitive to oxygen and can become inactive quickly after air exposure.

The bacterium also declines quickly, meaning repeated treatment would be needed to maintain levels, according to the team. More research is needed to understand its role in the microbiome and to test whether the approach can benefit people with lupus.

Morel said the next phase will examine metabolites to identify which cell populations are tied to immune protection or inflammation. The researchers also plan studies on diet, the microbiome and immune responses, including how different dietary carbohydrates may relate to health outcomes.

This story draws on original reporting from Medical Xpress.