Autoimmune disease

An autoimmune disease is a medical condition caused by an anomalous response from the adaptive immune system. Usually, the adaptive immune system identifies and fights foreign organisms like bacteria or viruses. In an autoimmune disease, this system makes a mistake. It mistakenly targets and attacks the body's own healthy, functioning cells and tissues. Scientists have recognized more than 80 distinct autoimmune diseases. However, recent evidence suggests there may actually be more than 100 different conditions. These diseases are a separate class from autoinflammatory diseases. While both involve immune malfunctions, autoinflammatory diseases involve the innate immune system. Autoimmune diseases specifically involve a malfunction of the adaptive immune system.

The mechanism of these diseases depends on which part of the body is being attacked. The immune system creates an inflammatory response, which causes damage to specific tissues. For example, in type 1 diabetes, the immune system attacks the insulin-producing beta cells in the pancreas. This attack prevents the body from regulating blood sugar correctly. In multiple sclerosis, the immune system targets myelin. Myelin is the protective covering around nerve fibers in the central nervous system. When myelin is damaged, communication between the brain and the rest of the body becomes difficult. Other diseases may target the small intestine, the skin, or even the thyroid gland.

There are many different types of autoimmune diseases that affect various organ systems. Celiac disease is an immune reaction to gluten, a protein found in wheat, barley, and rye. This reaction damages the villi, which are small fingerlike projections in the small intestine used for nutrient absorption. Graves' disease involves the development of autoantibodies that target thyroid-stimulating hormone receptors. This causes an unregulated release of thyroid hormone, leading to a rapid heart rate or weight loss. Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis, involve chronic inflammation of the digestive tract. These conditions often occur because the body loses immune tolerance for normal bacteria in the gut microbiome.

Other common conditions include rheumatoid arthritis and systemic lupus erythematosus. Rheumatoid arthritis primarily targets the joints, causing persistent inflammation, pain, and stiffness. This disease is often symmetrical, meaning it affects both sides of the body, like both knees or both hands. Systemic lupus erythematosus, or lupus, is a systemic disease. This means it can affect multiple organs, including the skin, kidneys, and nervous system. Lupus is characterized by a widespread loss of immune tolerance. Some people may also experience polyautoimmunity, which is the condition of having more than one autoimmune disease at the same time.

Researchers have been studying the recognition of autoimmune diseases since the early 1900s. Since that time, scientific understanding of these conditions has grown substantially. However, the exact causes remain unclear and are likely multifactorial. This means many different factors work together to cause the disease. Scientists believe there is a complex interplay between genetic and environmental influences. Some diseases, such as lupus, show familial aggregation, which suggests a genetic predisposition. Other cases may be triggered by infectious triggers or exposure to specific environmental factors. The exact etiology, or cause, is still being unraveled by researchers.

These diseases have a significant impact on populations. A study conducted in the UK found that 10% of the population is affected by an autoimmune disease. Women are more commonly affected by these conditions than men. While they can start at any age, they predominantly begin in adulthood. Fatigue is the most common symptom reported by patients. A 2015 US survey found that 98% of people with autoimmune diseases experienced fatigue. Furthermore, 89% of those surveyed called fatigue a major issue. Symptoms often fluctuate between periods of high activity, called flare-ups, and periods of inactivity, called remissions.

Managing autoimmune diseases requires long-term care because most treatments do not offer a cure. Instead, therapeutic approaches aim to manage symptoms and reduce immune system activity. Doctors may use nonsteroidal anti-inflammatory drugs, or NSAIDs, to reduce inflammation. Immunosuppressants are also commonly used to control the overactive immune response. In some specific cases, medical professionals may administer intravenous immunoglobulin to help regulate the immune system. These treatments help maintain the body's ability to fight actual diseases while minimizing the damage caused by the autoimmune response. Tracking how symptoms occur is vital for monitoring disease progression and how well a patient responds to treatment.