What is Rheumatoid Arthritis? Definition And Causes

Rheumatoid arthritis (referred to as RA in the medical field) is a unique disorder, in the sense that, it is caused by the wrong response of the autoimmune system of our body itself.

In other words, rheumatoid arthritis is an autoimmune disease caused by the body’s own immune system mistakenly attacking the body’s own tissues.

The autoimmune system is the mechanism, which acts as defense force of our body, protecting it from external invasive forces (e.g. bacteria). Rheumatoid arthritis is thus a result of our own autoimmune system.

Definition

Rheumatoid arthritis is a chronic, progressive inflammatory disorder, which commonly attacks the smaller synovial joints of the hands and feet (fingers, wrists, feet, and ankles), and can cause synovitis and erosion of the cartilage of the joints.

Typically, in RA the same joints are involved on both sides of the body.

Sometimes bigger joints like the shoulder and knees can also get involved. This inflammatory process can also extend to the lungs, heart, skin and the eyes.

Rheumatoid arthritis is commonly seen more after the age of 40 years and with a 2.5 higher prevalence in women than in men. About 1.5 million people suffer from RA in the United States.

It affects 0.5 to 1% of the population in the developed world. Between 5 to 50 of 100,000 people newly develop this condition.

Rheumatoid Arthritis Causes

In RA, the autoimmune mechanism inadvertently attacks the synovial membrane. This is the soft tissue found between the joint capsule and the joint cavity of the synovial joints.

As a result, the synovium  becomes thickened and inflamed. Eventually, if the inflammation is left untreated, the autoimmune reaction destroys the cartilage and the surrounding bones within the joint.

As a result, the ligaments and tendons that are attached to the bones of the joint weaken and become loose. Over time, the joint loses its alignment and shape.

However, why this happens is still unknown. A genetic factor does seem likely, which can make you more prone to rheumatoid arthritis due to environmental factors such as infection by bacteria and viruses when the autoimmune system becomes active.

According to the Arthritis foundation: “Researchers have shown that people with a specific genetic marker called the HLA shared epitope have a fivefold greater chance of developing rheumatoid arthritis than do people without the marker.”

RA trigger factors

Research is still incomplete about the causes and the risk factors that can lead to rheumatoid arthritis, but some headway is being made.

Cigarette smoking

A number of detailed studies have shown that cigarette smoking carries a considerable risk for the development of this disease and further to its severity. This risk becomes stronger in individuals who carry the shared epitope and more pronounced in individuals who carry the RA autoantibodies.

Oral bacteria

Another finding is recent years is the association between rheumatoid disease and  periodontal disease. Periodontal disease, including periodontitis, is the infection of the gums and the tissues that surround the teeth and support them. Periodontitis can cause a slow destruction of the alveolar bone around the teeth and of the collagen matrix.

It is now established that a specific species of bacteria, Porphyromonas gingivalis, which causes periodontal disease contains an enzyme that can cause citrullination of proteins.

Citrullination of proteins is the preceding process to the autoimmune response that leads to RA. This link strongly suggests that periodontal infection can lead to rheumatoid arthritis in some people and has led researchers to study this angle more deeply.

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