How gut bacteria breaking down tryptophan may drive inflammatory arthritis

Influence of bacterial tryptophan metabolism on inflammatory arthritis

NIH-funded research University of Colorado Denver · NIH-11166419

This project looks at whether gut bacteria that convert the amino acid tryptophan into indole compounds promote inflammation in people with rheumatoid arthritis and spondyloarthritis.

Quick facts

Grant typeR01 grant
Study typeNIH-funded research
Funding institutionUniversity of Colorado Denver NIH-funded
Lab location1 site (Aurora, UNITED STATES)
Project IDNIH-11166419 on NIH RePORTER

What this research studies

Researchers compare gut microbes and metabolites from people with rheumatoid arthritis or axial spondyloarthritis to find bacteria that make indoles from tryptophan. They study human intestinal tissue, antibodies, and T cells to see immune reactions tied to those bacteria. In parallel, they use mouse models to test whether indole-producing bacteria, indole supplementation, low-tryptophan diets, or antibiotics change joint inflammation. The team will examine how indoles affect intestinal dendritic cells and Th17 cells and how that influences autoantibody-driven disease.

Who could benefit from this research

Good fit: People with rheumatoid arthritis or axial spondyloarthritis, and individuals considered at high risk for these autoimmune diseases, are the kinds of patients whose samples and immune responses are being studied.

Not a fit: People with non-autoimmune joint conditions such as osteoarthritis or those whose disease is unrelated to gut microbial metabolism may not benefit from these findings.

Why it matters

Potential benefit: If successful, this work could point to gut-targeted approaches (diet changes, microbiome therapies, or drugs) to prevent or reduce inflammatory joint damage in RA and spondyloarthritis.

How similar studies have performed: Previous human-sample and animal-model work has linked the gut microbiome to inflammatory arthritis and mouse studies support a role for indole, but translating these findings into human treatments is still early and novel.

Where this research is happening

Aurora, UNITED STATES

Researchers

About this research

  1. This is an active NIH-funded research project — typically early-stage science, not a clinical trial accepting patient enrollment.
  2. Some NIH-funded labs run parallel clinical studies or seek volunteers for related work. To check, contact the principal investigator or institution listed above.
  3. For full project details, budget, and progress reports, visit the official NIH RePORTER page below.
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.