Autoimmunity Is a Disorder of Our Time – Elemental by Medium

Genetics explain a good portion of autoimmune disease prevalence. Scientists know that these diseases tend to cluster in families. When one family member has an autoimmune condition, other family members are at an increased risk of autoimmunity — though not necessarily of the same disease. It’s not uncommon for someone with rheumatoid arthritis to have an aunt with, say, ulcerative colitis or any number of seemingly unrelated autoimmune conditions. What this means is that one of the main factors contributing to autoimmune susceptibility more generally is likely genetic.

Scientists also know that autoimmune diseases affect women at a disproportionately higher rate than men. By some estimates, women account for 75% of the U.S. population affected by autoimmunity, or some 30 million people. Some research suggests that the fact that women have two X chromosomes could be a factor. The X chromosome is home to tiny pieces of genetic material called microRNAs, which are thought to be involved in immune system function. While this is one reason women live longer, it could also make their immune system more susceptible to turning on itself.

It’s not so much our cleanliness but our increasingly industrial lifestyle that is blocking the intake of these important microorganisms.

Still, the rate at which autoimmune conditions are rising far outpaces the rate at which genes can pass them on, Rose says. “Autoimmune diseases, like many diseases, are a combination of genetic susceptibility on one hand and some exposure on the other,” he says. “We’re talking about an increase over 20, 25, 30 years. Genetics don’t change that rapidly, so it must be something environmental.”

Scientists began noticing a steep uptick in cases of autoimmune disease and allergies in the 1980s and 1990s, while cases of infectious diseases such as mumps, measles, and tuberculosis were falling, largely due to the widespread use of vaccines and antibiotics. Researchers theorized that these trends were related: Perhaps the absence of infection — the very thing our immune systems were designed to protect us from — was causing those systems to malfunction.

This observation was the genesis of the so-called hygiene hypothesis, the theory that sterile modern environments leave children vulnerable in unanticipated ways. Researchers thought children should be introduced to more pathogens at a young age to build up the immune system. Scientists have since refined this theory. According to Graham Rook, emeritus professor of medical microbiology at University College London, the immune system needs early and regular exposure to common and harmless microbes — bacteria, essentially — in order to learn how to react to threats.

“Epidemiologically, the point is confirmed that if you don’t have the right organisms in your gut at a certain critical point in your development, then there are defects in the immune system,” Rook says.

These much-needed microorganisms come primarily from the natural environment and what’s known as the maternal microbiome — the healthy bacteria we get from our mother in utero, through the vaginal canal, and even through breast milk. These sources have been compromised in developed nations due to less exposure to green spaces, a less varied diet, the overuse of antibiotics, and falling rates of breastfeeding and natural birth, Rook argues. People are exposed to a far less diverse range of microbes (or, in the case of antibiotics, those microbes are killed off), and that means our immune systems are less equipped to deal with the bacteria — good or bad — that comes our way. It’s not so much our cleanliness but our increasingly industrial lifestyle that is blocking the intake of these important microorganisms.

“The greater diversity of organisms in our gut, the healthier we seem to be,” Rook says.

People who live in developed countries have higher rates of autoimmune diseases than people living in the least developed countries, and people living in rapidly modernizing nations are more susceptible to autoimmune disease as their countries modernize. Studies show that developed nations have less microbially diverse environments than undeveloped ones, according to Rook, suggesting a strong link between the onset of autoimmunity and a lack of exposure to diverse microbes.

Rook and other researchers recommend that people try to get more exposure to nature by spending time outside, use antibiotics more judiciously — especially pregnant or breastfeeding women — and eat a healthy, holistic diet. They also acknowledge that there’s a limit to how much individuals can do to steel themselves against autoimmunity.

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