Rheumatoid Arthritis Causes
Rheumatoid arthritis occurs when the immune system attacks the synovium. When this happens, the synovium thickens, swells, and eventually invades and damages the cartilage and bone within the joint. The tendons and ligaments that hold the joint together weaken and stretch. The affected joint gradually loses its shape and alignment.
The exact reason what starts off this process remains unclear, but the interplay between some factors are thought to contribute to the development of rheumatoid arthritis. These factors include: abnormal autoimmune response, genetics, and some environmental or biologic trigger, such as a viral infection or hormonal changes.
The Immune Response and Inflammatory Process
The normal immune system response. The body's immune system triggers inflammation to protect itself against infections, and to allow damaged tissues to heal. When the body is exposed to an injury or an infection, white blood cells are mobilized to rid the body of any foreign proteins such as bacteria or virus. The masses of blood cells that gather at the injured or infected site produce substances that help repair wounds, clot the blood, and fight infections. The immune system is normally capable of controlling and limiting the inflammatory process.
The immune system has two important components that are crucial in the inflammation associated with rheumatoid arthritis. These components are known as B cells and T cells.
If the T cell recognizes a foreign body or antigen, it will produce chemicals known as cytokines which cause B cells to multiply and release antibodies. These antibodies disperse widely in the bloodstream, recognizing the antigens and setting off inflammation to protect the body from invasion. In rheumatoid arthritis, both the T cells and the B cells become overactive.
Genetic factors are thought to be involved in RA. While genes do not causes the disease, it may increase a person's susceptibility to environmental and biologic triggers. In addition, genetic factors may increase the severity of rheumatoid arthritis, once the disease has developed.
Environmental factors such as infections have been suggested to play a role in the development of RA. Many microorganisms have been studied, but no single causative agent has been identified to be the main trigger for the autoimmune response and the inflammation that occurs in rheumatoid arthritis.
It has been found that the synovial fluid of some people with rheumatoid arthritis contain higher than average levels of antibodies that react with an intestinal bacteria known as E.coli. Some experts think that this may stimulate the immune system to prolong the duration of rheumatoid arthritis once the disease has been triggered by infection. Other microorganisms that are considered as potential triggers include: Streptococcus, mycoplasma, parvovirus B19, retroviruses, mycobacteria, and Epstein-Barr virus.
Anyone can develop rheumatoid arthritis, but some people are more likely to get it than others. Below are factors that may increase one's risk of rheumatoid arthritis:
Gender. Rheumatoid arthritis is 2 to 3 times more common in women than in men. The reasons for women's increased susceptibility to the disease are still not known.
Age. Although rheumatoid arthritis can occur at any age, it most commonly begins between the ages of 40 and 60.
Family history. If some members of your family have rheumatoid arthritis or other sort of autoimmune disease, this could mean that you may have a genetic predisposition to such diseases. Experts believe that rheumatoid arthritis is not directly inherited, however, one can inherit predisposition to the disease.
Smoking. Some studies suggest that smoking significantly increases the severity of rheumatoid arthritis.