Diet, Microbes & Inflammation: Unique Microbial Genetic Strains in Inflammatory Disease, Plus a Possible Arthritis Diet

ACR CONVERGENCE 2020—How does the body’s microbiome affect inflammatory diseases, such as rheumatoid arthritis (RA)? Can diet alter a patient’s microbiome or metabolome enough to improve symptoms or disease activity? In November at ACR Convergence 2020, two researchers discussed their laboratories’ efforts to answer these questions and, hopefully, provide evidencebased dietary advice to patients.

The Microbiome & Systemic Health
In chronic, inflammatory diseases, such as RA, the interplay of a patient’s environment, microbial exposures and immune system is an intriguing area to explore, said Curtis Huttenhower, PhD, professor of computational biology and bioinformatics at the Harvard T.H. Chan School of Public Health, Boston.

“The links between the microbiome and chronic disease are most obvious in the gastrointestinal tract, where the majority of microbes reside. But the same is true throughout the body, as microbes rest on the skin, or in the joints or oral cavity,” Dr. Huttenhower said.

Transmitted through the human immune system, these microorganisms may have an effect on arthritis symptoms, such as joint pain or inflammation, or more systemic phenotypes, such as the gut-brain axis. Antibiotics and other drugs can alter the gut microbiome, and the same is true for dietary compounds.

“There’s been a lot of work on the direct effects of diet on the microbiome [because] it contributes to human metabolism. But the microbiome also has an indirect effect on our dietary components that changes things like circulating metabolites, blood sugar responses and blood lipids, all of which can have effects on systemic health. We don’t know how it works yet, but the microbiome is a promising mechanism to monitor and improve health,” said Dr. Huttenhower.

Dr. Huttenhower’s laboratory studies microbiome epidemiology and its contributions to health on a population-wide scale, mostly associations between the microbiome and inflammatory bowel disease (IBD) and colorectal cancer. They want to develop a consistent perspective on what features of the microbiome relate to particular microbial exposures and health outcomes, and to understand what drives these relationships.

“Then, we can take population-scale human observations back to a more lab-controlled model, such as animal studies or in vitro microbial cultures, to get a mechanistic perspective on how these interactions might be causal, and how you can modify these aspects of the microbiome to improve disease outcomes,” he said.

New Arthritis Initiative
Dr. Huttenhower is an associate member of the Inflammatory Arthritis Microbiome Consortium (IAMC), which is conducting a multi-year study at four centers in England that began in April 2016. Researchers are recruiting patients with RA, ankylosing spondylitis (AS), psoriatic arthritis (PsA) and juvenile idiopathic arthritis (JIA). They are also conducting experiments on mice to study subjects’ microbiomes, how microbiome biomarkers may predict disease outcomes or therapy responses, and which individual microbes may worsen or protect against inflammatory disease. He shared some early findings from their research.