Young people get arthritis too...

Juvenile Idiopathic Arthritis (JIA):
Juvenile= affecting young people.
Idiopathic= a disease with an unknown cause.
Arthritis: a common disease causing pain and inflammation in joints.

JIA is a common childhood disease affecting the musculoskeletal system. 1 in 1000 children in the UK are affected by the autoimmune condition. JIA first occurs in young people before they reach 16 years of age. This is when they start to display common signs of arthritis including red, warm, painful and stiff joints, as well as having a recurrent fever and skin rash that come and go in parallel with joint inflammation. Although the cause of the disease remains a mystery, it is thought that a combination of genetic and environmental factors provoke the immune system to attack cells and tissues in the body, especially in the joints.

In a healthy individual, the immune system is able to distinguish between the body’s own cells and tissues from pathogens by recognising antigens. When the immune system recognises antigens on the surfaces of pathogens, an immunological response is triggered. However, with self-antigens, there is no such response, which means that healthy tissues in the body aren’t damaged.

When the immune system is in self-destruct mode, there is a breakdown of self-tolerance, which means that cells of the immune system start responding to self-antigens to cause a harmful response. The response is usually inflammation due to the release of autoantibodies by plasma cells, which leads to the degradation of cells in the joint- bringing about symptoms of pain, swelling and stiffness.

There are many chemical messengers involved in JIA, one of which are cytokines. These molecules attract cells of the immune system to enter the synovial membrane. More and more cells gravitate towards the membrane as more cytokines are produced (this is an example of positive feedback), which causes further inflammation of the synovial membrane. This disrupts the synovial fluid that lubricates the joint, contributing to more pain, swelling and stiffness.

Understanding the immunological basis of JIA has helped enormously in developing and advancing treatments for the disease. In the past, JIA was so difficult to treat that young people grew into adulthood with severe joint damage. Nowadays, JIA can be treated using monoclonal antibodies and fusion proteins. These treatments are used when cheaper, anti-inflammatory treatments fail to alleviate symptoms.

Monoclonal antibodies:
>derived from a single clone of cells
>they only bind to 1 type of molecule
>these antibodies can bind to cytokines to prevent cytokines from binding to their complementary receptors, which means that there’s reduced inflammation.

Fusion proteins:
>essentially antibody-receptor complexes
>act as decoy receptors to essentially ‘mop up’ cytokines, which can potentially be harmful

In conclusion, while young people with JIA are likely to grow up with a condition requiring lifelong monitoring and treatment, the future certainly looks brighter for them now than it did decades ago.

Sources:
>Biological Sciences Review >https://www.jia.org.uk/what-is-jia-
N.B: Apologies for not posting on the blog for so very long. I have been kept busy over the past few months with the UCAS process and trial exams. 
By Kumaran Rajaratnam.

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