Frequency and Causes

Rheumatoid arthritis is the most common inflammatory joint disease worldwide. In India the prevalence of RA is 0.28-0.7%.1

Women are affected about three times more frequently than men.

Rheumatoid arthritis is diagnosed in many cases between the ages of 30 and 50, but can occur at any age.

Rheumatoid arthritis (RA) is one of the autoimmune diseases. These diseases are characterized by the fact that the immune system of those affected not only attacks harmful invaders such as bacteria or viruses, but also targets cells of their own body. In the case of RA, these misguided attacks of the immune system primarily affect the cells of the synovium, which lines the joint from the inside. An inflammatory reaction is triggered, in the course of which inflammatory signal substances such as TNF-alpha and so-called interleukins are released. These signal substances continue to fuel the inflammatory process and thereby strengthen themselves. Because the inflammation within the affected joints can not heal, it is called a chronic, i.e. Persistent Inflammation.

If this chronic inflammation is not treated, the inflamed synovium can proliferate in the cartilage and even in the bones, forming a so-called pannus. As a result, there may be permanent damage to the joint and bone with deformation and stiffening and total loss of joint function.

normal joint

Fig:1

1(a) RA commonly occurs in the small joints(left)
1(b) A healthy Joint and Joint affected by RA(right)

In detail: The role of the immune system in rheumatoid arthritis

Our immune system has the task to protect us from all pathogens. The prerequisite for this is that the immune system recognizes pathogens as foreign to the body and can render them harmless. This requires a complex interaction of different specialized cells and specific organs.

A special role is played by the so-called T cells and B cells. The T cells are white blood cells (leukocytes) and are constantly on the lookout for pathogens. If they find them, they cause the release of messenger substances (cytokines), which in turn call the B cells on the plan.

When B cells come into contact with a pathogen, they cause the production of antibodies. Antibodies "mark" the pathogen as harmful and mediate its destruction by specialized cells.

The immune system of people with rheumatoid arthritis is overly active and falsely recognizes the synovial membrane as a foreign body - Triggering the typical inflammatory response.

Fig: 2



So far, it is unclear why the immune system in RA directed against the body's own tissue and sets an inflammatory process in motion. Genetic, viral or bacterial or environmental factors (smoking, obesity) may play a role in the development of RA.

Bibliography

  1. Handa et. al., International Journal of Rheumatic Diseases: 19:440-51

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