Doctors aren’t entirely sure what triggers rheumatoid arthritis, a disease in which the body turns on itself to attack the joints, but an emerging body of research focuses on a potential culprit: bacteria that live in our intestines.
Several recent studies have found that joint pain is linked to bacteria in the gut, joint pain from rheumatoid arthritis, for example, and other diseases in which the body’s immune system goes haywire and attacks its own tissues.
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Joint pain related to bacteria in the intestines.
A study found that people with rheumatoid arthritis were much more likely to have a bacteria called Prevotella copri in their intestines than people who did not have the disease. In another study found that patients with psoriatic arthritis, another type of autoimmune joint disease, had significantly lower levels of other types of gut bacteria.
This work is part of a growing effort by researchers around the world to understand how the microbiome – the mass of microbes that live in the gastrointestinal tract – affects our overall health. The intestine contains up to a thousand different species of bacteria, which together weigh between one and three kilos.
This mass contains trillions of cells, more than the number of cells that make up our own body. In recent years, scientists have compiled a growing collection of evidence that many of these organisms can have a major effect on our well-being, with some chronic triggers, non-infectious diseases, such as rheumatoid arthritis, and others protecting against this type of disease.
Bacteria in the intestines affect the immune system.
“It is becoming increasingly clear that these microbes can affect the immune system, even in diseases that are not in the gut and that joint pain is related to bacteria in the gut.”
Scientists are especially intrigued by how these bacteria influence the immune system. In recent decades, the incidence of many autoimmune diseases has been increasing; Many microbiome researchers argue that at least part of this increase is due to changes in our bacterial ecosystem.
Altered diet, the explosion of antibiotic use, etc. “Our microbiome has changed significantly over the last century, and especially in the last 50 years,” says microbiologist. “We are losing good microbes with each generation; it’s extinguished. These changes have consequences”.
Helicobacter pylori has brought an increase in diseases such as asthma.
Blaser points to his own research on a good species of bacteria called Helicobacter pylori (so named because it looks like a helicopter). Bacteria were taken from the gut from a group of children in the United States, and found that Helicobacter pylori existed in only 6 percent of them. In comparison, other research has shown that the strain is common in the vast majority of people in many parts of the world, especially in developing countries.
The decline of Helicobacter pylori in the West, probably related to the spread of antibiotics, as well as improved sanitation, may have medical consequences: some research indicates that bacteria can reduce the risk of asthma, perhaps by reducing the body’s immune response to stimuli in the air. Blaser suspects that asthma is one of the diseases affected by our changing microbiome. There was an increase in three decades, and it grew more than 28 percent between 2001 and 2011.
In fact, these bacteria have a powerful stake in controlling how our bodies respond to intruders. Blaser and others say that it appears that many of the organisms that live within us have thrived by modulating the immune system to avoid being recognized and attacked as invaders; In essence, these organisms train immune cells not to be trigger-happy.
A microbiome with the wrong type of bacteria, or the wrong ratio of bacteria, a condition known as dysbiosis, can throw this immune system out of balance, causing immune cells to attack not only those bacteria, but also the body itself.
Prevotella copri bacteria can stimulate an immune reaction that targets tissue causing joint pain.
Microbes are especially influential in the gut, where two-thirds of the body’s immune cells are found. During digestion, the gastrointestinal tract must deal with a constant stream of food-related foreign microbes, which must be monitored and, if harmful, destroyed. For this, our intestines have developed an extensive immune system, whose effects go far beyond the intestine. Immune cells in the gut appear to be able to activate inflammatory cells throughout the body, including in the joints.
But while many scientists are sure of the link between the microbiome and arthritis, they have not specified what special role bacteria play in triggering the disease.
The Prevotella copri can stimulate an immune reaction which is then directed to the tissue causing joint pain. Or it can crowd out the beneficial microbes that keep the immune system’s attack cells highly aggressive (a theory supported by the fact that people with high levels of Prevotella copri had also reduced the numbers of Bacteroides fragilis bacteria, which appears to contain the immune system).
A similar mechanism could explain the results in the psoriatic arthritis study; the species of bacteria disappeared: Akkermansias, Ruminococcus and Pseudobutyrivibrio, can indicate to the immune system to moderate.
Diet and microbial adjustment could be the cure for arthritis and other autoimmune diseases.
It will be possible to treat arthritis by adjusting the microbiome. Dozens of researchers are investigating a number of possible strategies for using bacteria as medicine for immune diseases.
Already, millions of Americans ingest probiotics – cocktails of supposedly beneficial bacteria that claim to treat everything from acne to insomnia. Many microbiome scientists are skeptical that these products are helpful. For one thing it’s unclear whether most of the microbes in probiotics can survive the digestive process.
Finnish researchers found that a vegan diet changed the gut microbiome, and that this change was linked to an improvement in arthritis symptoms by lowering inflammation and joint pain.
Others focus on particular dietary mistakes. Researchers have found that a species of Prevotella bacteria, P. histicola, can prevent, in experiments, rheumatoid arthritis and multiple sclerosis, an autoimmune disease of the brain and nerves.
And some scientists are not focusing on bacteria, but on the compounds they produce. He discovered that a compound from the bacterium B. fragilis, for example, can alleviate autoimmune disease such as multiple sclerosis, by releasing a molecule called polysaccharide A, or PSA.
At this time, doctors are not using microbes or their metabolites in patients with arthritis and multiple sclerosis.