Arthritis Arthritis Basics

Rheumatoid Arthritis: Immunological Factors

In the case of rheumatoid arthritis, the cytokines build up in the synovium, which draws in more inflammatory cells and results in painful swelling of the joints, hands and feet. Excessive amounts of these damaging cytokines can lead to inflammation in other body tissues as well such as the tendons, cartilage, eyes, heart, lungs and kidneys.

Cytokines Responsible for Joint Damage
Two specific cytokines have been linked to rheumatoid arthritis. They include interleukin-1 (IL–1) and tumor necrosis factor-alpha (TNF-alpha). Both send inflammatory messages to other cells that help fuel the overall immune response that leads to inflammation and joint damage, and both have been found to be abundant in the synovial lining of the joint.

The presence of these cytokines is believed to lead to joint deterioration and erosion of the cartilage that is the cushioning material at the end of bones. Their presence also causes swelling of the synovium. The joint damage results as the cartilage wears down and the space between the bones narrows. If the condition worsens, the bones start to rub against each other. If the joint lining expands, it can invade into or erode the bone and can eventually lead to irreversible bone damage.

Novel Treatments Target Cytokines
As doctors learn more about how the immune system functions and the specific cytokines responsible for the progression of disease, they have been better able to both target the mechanisms that cause specific immune responses and develop novel therapies that zero in on this aspect of the disease.

Already, they have made significant progress in determining how best to seek out and destroy harmful immune cells while leaving other parts of the body’s disease fighting system intact. A class of medications known as biologics has shown promise in their ability to seek out and destroy certain cytokines. Biologic treatments already on the market block the production of TNF-alpha and IL-1.

A new class of medications called co-stimulation modulators were recently approved to treat rheumatoid arthritis by inactivating the T cells that stimulate the inflammatory response.

More attention is being focused on B cells as well. A monoclonal antibody called Rituxan (rituximab), which has typically been used to treat cancer, was recently approved for the treatment of rheumatoid arthritis. It targets and reduces the number of B cells in the body, which are believed to play a role in the initiation and development of the disease.

Researchers are also looking at the role played by other cytokines. For example, a new therapy is aimed at blocking interleukin-6 (IL-6), another protein found in excessive amounts in the joints of people with rheumatoid arthritis. It is also believed to be responsible for joint damage and swelling. Investigators now surmise that IL-6 may be a cause of fever and excess blood platelets (thrombocytosis) in people with rheumatoid arthritis. Researchers hope that blocking IL-6 can reduce its damage and early research has shown promise.

In the future, researchers may discover that other cytokines are also at work in the deterioration caused by rheumatoid arthritis. For example, it is possible that the cytokines that normally suppress inflammation are missing or are present in low numbers. Scientists may one day develop biologic medications that boost their levels to rebalance the immune system and restore it to its normal purpose.

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