Autoimmune diseases can strike any part of the body, and mostly affect women

Lauran Neergaard,
MDT/AP Medical Writer

Our immune system has a dark side: It’s supposed to fight off invaders, but sometimes it turns traitor and attacks our own cells and tissues. Autoimmune diseases can affect nearly every part of the body — including the brain — and tens of millions of people. While most common in women, they can strike anyone, and they’re on the rise.

New research is raising hopes for treatments that do more than manage symptoms. Dozens of clinical trials are testing ways to re-program a malfunctioning immune system. Furthest along is CAR-T therapy, originally a cancer treatment, which has shown early success against lupus, myositis and other illnesses. It wipes out immune system B cells — both rogue and normal — with the expectation that healthier ones grow back. Researchers are also exploring ways to delay disease onset, inspired by a drug that postpones Type 1 diabetes.

They’re chronic illnesses ranging from mild to life-threatening, with more than 100 types. Rheumatoid and psoriatic arthritis attack joints. Sjögren’s disease causes dry eyes and mouth. Myositis and myasthenia gravis weaken muscles in different ways. Lupus can cause a butterfly-shaped facial rash, joint and muscle pain, fevers and organ damage. Some, such as autoimmune encephalitis, even affect the brain. These conditions are unpredictable and can “flare” suddenly.

Symptoms often mimic other conditions and may come and go. Many autoimmune diseases overlap — rheumatoid arthritis and Sjögren’s can also damage major organs. Diagnosis can take multiple tests, including blood tests for misguided antibodies. It typically hinges on symptoms and ruling out other causes, sometimes over years and with several doctors.

There are improvements underway. The National MS Society is educating doctors on updated guidelines to streamline MS diagnosis. Scientists are also identifying more harmful antibodies behind autoimmune encephalitis, improving detection.

The immune system is an army of sentinels, fighters and peacemakers designed to distinguish invaders from “you.” Sometimes confused immune cells slip through, or the peacemakers fail to calm inflammation. If the system doesn’t correct itself, autoimmune disease follows.

Most autoimmune diseases aren’t caused by a single gene. Instead, many genes can increase susceptibility, with an environmental trigger — infection, smoking or pollutants — setting the illness in motion. Researchers are zeroing in on early molecular events. Over-active neutrophils, first-responder white blood cells, are implicated in lupus, rheumatoid arthritis and others.

Epstein-Barr virus is known to trigger MS in some people, and new evidence links it to lupus. Stanford researchers found the virus can hide in a tiny fraction of B cells and occasionally push them into an inflammatory state that sparks autoimmune reactions. This may help explain long-term impacts of infections.

About 80 percent of autoimmune patients are women. Hormones play a role, and abnormalities in how female cells switch off one X chromosome may increase vulnerability. But men are affected too — one severe condition, VEXAS syndrome, discovered in 2020, primarily strikes men over 50. Some groups have higher risks: lupus is more common in Black and Hispanic women; MS is more common among Northern Europeans.

The global market for autoimmune treatments is about $100 billion a year. Care is lifelong and expensive. Older therapies relied on high-dose steroids and broad immune-suppressing drugs, which increased risks of infections and cancer. Today, newer drugs target specific molecules and dampen immunity less broadly, but for many diseases treatment remains trial and error, with little guidance for patients.

[Abridged]