The immune system protects the body against foreign invaders that cause illness. Through a series of steps, the immune system launches an all-out attack on dangerous viruses, bacteria and other pathogens. In autoimmune disease however, the immune system attacks healthy cells by mistake. Doctors currently prescribe treatments, such as steroids, to suppress the immune system. Now medical researchers are investigating the benefits of using probiotics to manage autoimmune responses.
Probiotics are bacteria that provide health benefits to their host. Many of these probiotics live in the gut alongside unhealthy bacteria that cause disease. In a healthy gut, probiotics help keep the numbers of pathogens low by competing for food and space within the intestinal tract. Probiotics can help with diarrhea, maintaining heart health, and even reduce the severity of some allergies. Now research suggests these friendly bacteria can help reduce unhealthy autoimmune responses.
About 50 million people in the United States struggle with an autoimmune disease, according to the American Autoimmune Related Diseases Association (AARDA). This means about one in five Americans struggles with rheumatoid arthritis, lupus, multiple sclerosis (MS) and other diseases that occur when the immune system attacks the body’s own cells, tissues, and organs. Recent research suggests an increase in the number of autoimmune disease diagnoses, with an uptick in Type 1 diabetes, lupus and celiac disease cases.
The scientific community is still working to understand the exact causes of autoimmune diseases and to determine why some people are especially susceptible to these conditions. New research suggests that gut bacteria may play an important role in autoimmune responses.
The connection between the microorganisms living in the digestive tract, known collectively as the gut microbiome, and the immune system is clear. An estimated 70 to 80 percent of immune cells are in the intestines, making the gut the cornerstone of the immune system. If a person does not have a healthy gut, he or she cannot have a healthy immune system.
A healthy and well-balanced gut microbiome improves function of the gastrointestinal tract by breaking down food and synthesizing vitamins. Probiotics living in the gut also defend the body against invading pathogens by improving the function of the intestinal barrier, which is a single layer of cells lining the inside of the gut. The intestinal barrier allows nutrients to pass from the intestine into the body and prevents pathogens from getting through. Many conditions, such as gastrointestinal diseases, including inflammatory bowel diseases, celiac disease, gastrointestinal infections and diarrhea, can impair the function of the intestinal barrier.
Antibiotics, stress, illnesses, and poor nutrition can disrupt the delicate balance of the gut microbiome. Imbalances in the gut microbiome can upset digestion and affect the intestinal barrier. Microbial imbalances can also cause widespread inflammation throughout the body.
In some cases, leaky gut can develop. Leaky gut is a condition in which damage to the intestinal lining impairs its function, allowing bacteria, toxic waste products, and undigested food to pass through the intestinal barrier and enter the blood stream. Once in the bloodstream, the contaminants trigger the overreaction from the immune system.
An increasing body of research links the microbiome to a myriad of other conditions, such as Some researchers think that the bodies of some people respond to microbial imbalances by sending the immune system into overdrive; the immune system triggers a cascade of inflammatory chemicals that cause chronic inflammation in the short term and, over time, an autoimmune disease. A 2017 study found that participants with MS had four times the amount of two types of bacteria, Acinetobacter calcoaceticus and Akkermansia muciniphila, in their guts as people without the autoimmune disease; participants with MS also had one-quarter of another type of bacteria, Parabacteroides distasonis, as their counterparts without the condition.
In a 2017 study, researchers looked at mice that carried a specific mutated gene that made the rodents more susceptible to autoimmune problems. They found that the lab mice would show changes in their gut bacteria at about the same time as the rodents began developing inflammation and other autoimmune symptoms. The scientists administered probiotics to the mice to “reset” the balance of bacteria in the guts of the mice. After receiving the probiotics, the mice’s digestive systems returned to normal.
Probiotics living in the gut can improve the function of the intestinal barrier and protect it from damage. These beneficial bacteria do that in a number of ways, but one of the most important ways is by maintaining tight junctions, which are the small connections between the thin layer of cells of the intestinal barrier. Strong tight junctions prevent pathogens from passing into the bloodstream and sparking the autoimmune response. Future research should make the connection between probiotics and a healthy immune response clearer.