Inflammatory Arthritis and Gut Health

By Linda Rath

A healthy gastrointestinal (GI) tract plays a critical role in overall health and houses the largest number of immune cells in the body. A faulty immune system is responsible for the most common types of inflammatory arthritis including gout, rheumatoid arthritis (RA), psoriatic arthritis (PsA), axial spondyloarthritis (axSpA) and juvenile idiopathic arthritis (JIA). 

So how does gut health affect these conditions?  It has to do with the way that microbes or microorganisms interact with the immune system. The trillions of microbes that live in (and on) our bodies are collectively called the microbiome. The ones in the GI tract help digest food, make impor­tant vitamins and control the growth of cells that line our lungs, intestine and other organs. They also help teach our immune system the difference between harmless bacteria and germs that can make sick, according to Sarkis Mazmanian PhD, a professor of microbiology at the California Institute of Technology.

Knowing friend from foe is crucial, because it helps the immune system decide when to attack and when not to. Mazmanian says some of those decisions are controlled by specific gut microbes. Certain microbes activate immune T cells that promote or suppress inflammation. In a healthy microbiome, this means the immune system does what it’s supposed to: Pathogens are destroyed, and harmless cells are free to go about their business. But things go awry when there are too many pro-inflammatory T cells or not enough anti-inflamma­tory ones to rein them in. That’s why researchers think a problem with the microbiome might play a major – even an inciting – role in inflammatory types of arthritis, where the body attacks healthy tissue instead of invading organisms.

Beyond the Gut

Many factors, especially antibiotics, smoking, stress and certain foods, can disrupt the microbiome. This, in turn, can trigger an abnormal immune response and runaway inflammation in the gut. An inflamed gut can cause problems throughout the body. This is because what happens in the gut doesn’t always stay there. Inflammatory cells can escape into the bloodstream and travel to other parts of the body, according to Jose Scher, MD. Dr. Scher is a noted authority on the microbiome and director of the Psoriatic Arthritis Center and the Microbiome Center for Rheumatology and Autoimmunity at NYU Langone Health in New York City. In 2015, he and his colleagues published a study comparing intestinal bacteria in healthy people with those of people who had PsA or psoriasis. The patients all had a far less robust and diverse mi­crobiome than people in the healthy group did. And the microbiomes in the PsA patients looked almost exactly like the microbiomes of people with inflammatory bowel disease or IBD.

Other studies have also shown that RA, JIA, gout, and ankylosing spondylitis patients had abnormalities and less diversity in their gut microbes. Dr. Scher says the loss of protective bacteria means the immune system can’t regulate inflam­mation.

“A change in cell biology may allow inflammatory chemicals to es­cape from gut tissue to other part of the body,” he explains. If the microbial community continues to be disrupted, these inflammatory cells can attack joints and set the stage for inflammation to affect internal organs.

Promoting Gut Health

There are several ways to optimize gut health. Diet plays a critical role. A varied, plant-based diet that includes prebiotic and probiotic foods is a great start. But many healthy lifestyle habits that are good for arthritis are also beneficial for your gut. These include exercise, good sleep habits, stress management and smoking cessation.