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Autoimmune Disease and RA

Understanding the role played by the bodys immune system in the progress of rheumatoid arthritis.

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WebMD Feature Archive

By Annie Stuart WebMD FeatureReviewed by Louise Chang, MD

What do rheumatoid arthritis (RA), type 1 diabetes , Graves' disease , and multiple sclerosis have in common?One affects joints, another blood sugar. One puts the thyroid into overdrive. And the last condition affects the

brain and spinal cord. Although the diseases seem pretty different, there is one common denominator. They areall believed to be autoimmune diseases.

RA is one of about 80 different types of autoimmune diseases. After cancer and heart disease , autoimmunediseases are the most common type of disease in the U.S., affecting 50 million Americans. Women make upnearly eight out of every 10 people with an autoimmune disease.

Recommended Related to Rheumatoid Arthritis

Young Adults Living With RA

Last winter, after spending a few afternoons shoveling snow, Heather Miceli, 27, woke up in the middle of thenight and couldnt get out of bed. My joints had swelled up so much that I couldnt move without crying, shesays. Two months later, the college professor at Johnson and Wales University in Providence, R.I., who hadalways been healthy, was diagnosed with rheumatoid arthritis (RA) -- a debilitating autoimmune disease thatcauses inflammation and swelling in the joints and surrounding tissues,...

Read the Young Adults Living With RA article > >

What is the common link between autoimmune diseases? And how does autoimmunity lead to rheumatoidarthr itis? Heres what you need to know.

What Is the Immune System?To understand autoimmune diseases such as RA, it helps to know how the immune system normally works. Itsmost important job is protecting your body against foreign invaders, such as bacteria and viruses. White bloodcells are the agents of the immune system. The immune system works in two main ways. It either directlyattacks foreign invaders or it produces proteins called antibodies that attack the intruders.

Normally, the choreography of this interaction between the white blood cells works very well, says John A.Peyman, PhD, program officer in the clinical immunology branch of the National Institute of Allergy andInfectious Diseases (NIAID).

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He tells WebMD that the body can tell what is a threat and what isnt. When you have a cut on your finger, forexample, you may end up with a small infection caused by germs that enter the wound. This prompts a type ofimmune response known as inflammation -- often marked by redness, swelling, heat, and pain . Then theimmune systems white blood cells heal the wound and remove the infection.

What Are Autoimmune Diseases?

With an autoimmune disease like RA, however, something goes awry. The white blood cells overreact tostimuli inside the body. Instead of protecting the body from infection or disease as it normally does, the immunesystem attacks and destroys the bodys healthy tissue. It does this by producing antibodies against the bodystissue. This is called autoimmunity.

When the disease affects many organs, as in lupus , its called a systemic autoimmune disease. If it affects asingle organ or type of tissue, such as in type 1 diabetes, its known as a localized autoimmune disease.Different autoimmune diseases often cluster in families and may affect almost any organ in the body. Whenthey do, they may cause abnormal growth or changes in function.

There are some similarities to allergies in the way the body reacts negatively with an autoimmune disease. Thedifference is that with allergies, the bodys overreaction and response is to external factors such as dust ordander. With an autoimmune disease, the body is responding to itself.

Virginia T. Ladd, RT, is president and executive director of the American Autoimmune Related DiseasesAssociation Inc. (AARDA). She tells WebMD it helps to think of autoimmune diseases the way we think ofcancer. In other words, it helps to think of them as a disease category.

There are more than 100 different forms of cancer, Ladd says, but theyre all formed by a mutant cell thatthe immune system allows to proli ferate. She says that autoimmune diseases also share a common disease

pathway. Theyre all caused by the immune system attacking its own tissue. For this reason, she says, weneed a shift in our thinking about autoimmune diseases. In the past, these diseases have been looked at asindividual cars on a train with too little focus on the engine thats driving the train. In her view, researchinto autoimmunity has been stymied by specialization of medicine, which is organized by the organ - not theorigin - of disease.

This is especially important because autoimmune diseases often run in families. And members of these familiesoften develop different types of autoimmune diseases. If you were going in to see a doctor for joint problems,would you think i t mattered to mention that your brother had Crohns? Ladd asks. Probably not. Most peoplewouldnt put two and two together. Understanding this connection is very important, though, because earlydiagnosis and treatment of an autoimmune disease like RA can often make a big difference.

What Causes Autoimmune Diseases?

The causes of autoimmune diseases remain unknown. Much more research is needed to fully understand them.However, evidence is pointing to infectious agents, such as viruses and bacteria. They may be importanttriggers in people who have a certain genetic makeup. Smoking or drugs also may trigger these chronicdiseases.

The initiating cause can occur up to four years before any clinical symptoms appear, Peyman says.

Everyone should be aware that they can reduce their risk of developing these diseases, Peyman says. As withcardiovascular disease and many cancers, inflammation is a major factor in the dysfunction of the immune

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system with autoimmune diseases. A diet rich in antioxidants and smoking cessation are good places to begin inreducing inflammation, he says.

What Is Rheumatoid Arthritis?

Joint destruction is the hallmark of RA. The immune system attacks joint tissues for unknown reasons. White blood cells travel to the joint lining, or synovium, and cause inflammation known as synovitis. This leads tosymptoms of warmth, redness, swelling, and pain. The chronic inflammation of RA causes the normally thinsynovium to become thick and joints to become swollen and puffy.

With time, the inflamed synovium invades and destroys the cartilage and bone within the joint. Researchersstudying rheumatoid arthritis now believe that it begins to damage bones during the first year or two that a

person has the disease. Thats one reason why early diagnosis and treatme nt are so important.

About 1.3 million adults have RA. Thats down from a 1990 estimate of 2.1 million. The decrease partlyreflects a more narrow definition of RA. However, the prevalence of RA does appear to be declining around theworld. Women with rheumatoid arthritis still outnumber men two to one.

What Causes Rheumatoid Arthritis?

Recent research is uncovering a complex interplay between the hormonal, nervous, and immune systems inrheumatoid arthritis. Researchers are also trying to learn why rheumatoid arthritis often improves during

pregnancy . One study suggests that certain proteins passed between the mother and unborn child may beresponsible for the improvement. These are proteins that help the immune system tell the difference between the

bodys own cells and foreign ones. This exchange of proteins may change the mothers immune system during pregnancy in some way.

Both genetics and environmental factors combined appear to be the main triggers of RA.

Genetics. Those at risk for autoimmune diseases such as rheumatoid arthritis inherit certain types of humanleukocyte antigens (HLAs). These are white blood cell proteins that cause the white blood cells to overreact.This genetic difference puts related family members at an increased risk for one or more autoimmune diseases.

Researchers are collecting information from families to gain even greater insights into genetic links. They haveidentified several genetic regions that increase the susceptibility for rheumatoid arthritis in animal models.Recent studies have found several novel genes associated with the disease.

Environmental factors. An original insult from an infection or other factor in the environment can lead tochronic arthritis years later. This makes it more difficult to identify the culprit. However, researchers arehoming in on some possible targets, Peyman tells WebMD. They include:

Smoking Parvovirus B19, also known as fifth disease Epstein-Barr virus, a prominent infectious agent Bacterial gum disease (periodontitis)

Recent studies show that smoking tobacco modifies proteins in the lungs, says Peyman. These modified proteins are similar to th ose showing up in inflamed joints. Cells travel from the lungs to an injured joint,where the immune system reacts strongly, causing ongoing inflammation.

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A similar process can happen with an infection. In people with genetic susceptibility, a minor localizedinfection in the mouth, for example, can trick the immune system into looking other places for modified

proteins. This can lead to a smoldering additional inflammation in the body, which chronically attacks the joints, Peyman says.

This molecular mimicry is the basis of much of the research into the immunology of autoimmune disease,Peyman says. Researchers are trying to find which components of a microbe or environmental insult aresimilar to the known targets of the immune system in autoimmune diseases. With rheumatoid arthritis, this has

been a decades- long quest.