Do Autoimmune Diseases Begin in the Gut?

Bonnie: Hey, Gastroenterologists! If you don't want to listen to us or your patients, maybe you'll listen to one of your colleagues. This piece appears on Medscape.

"My name is Dr Stephen Paget. I am the physician-in-chief emeritus at Hospital for Special Surgery, and professor of medicine at Weill Cornell School of Medicine in New York City.

Today I am going to talk about the microbiome, an extraordinary concept that is probably not well understood by most physicians but that truly defines us as people. The microbiome is those bacteria that live in various parts of our bodies, particularly the intestine. There are 100 times more genes in the bacteria inside us than each of us has as human beings. Our immune systems are defined by the microbiome and the interactions with those bacteria, almost 80% of which are not the usual bacteria that we know about.

It now has become clear that the makeup of those bacteria can define whether we are healthy or have disease. What is truly extraordinary is that we now have ways to change a person's bacterial growth and microbiome.

From Gut to Immune System

People who have persistent, antibiotic-resistant Clostridium difficile colitis are undergoing fecal transplant to enhance microbiomes that are not functioning well. Fecal transplant can be accomplished in various ways, even in pill form, to change the flora and the balance within the person's intestine, and heal them completely.

Animal models of different types of arthritis have shown that an animal that lives in a germ-free environment may not develop a certain type of arthritis. As soon as the animal is moved to an environment with specific bacteria, however, those bacteria interact with the animal's genetics and other environmental factors internally and externally to cause arthritis.

Thus, as we learn more about autoimmune diseases and types of arthritis, we have a tremendous opportunity to make a huge difference. Some scientists have shown that periodontal bacteria may play a significant role as a stimulus for rheumatoid arthritis. Similarly, intestinal bacteria play a significant role as a cause of various types of spondyloarthritis, including ankylosing spondylitis and psoriatic arthritis.

This is a new world and a new age. We are coming to grips with who we are as organisms, both the organism that is visible on the outside and the organism that is inside us, with both working together in health and in disease."