Researchers have found that childhood arthritis is not simply ‘little person’s arthritis’ and that the breakdown that occurs in children with the condition is distinctly different to the breakdown that occurs in adults.
Researchers from Murdoch Childrens Research Institute and the University of Melbourne analysed synovial fluid samples from children and adults with arthritis and looked at the patterns of cartilage degradation. They were surprised to find the breakdown in cartilage that happens during juvenile idiopathic arthritis (JIA) is markedly different to adult arthritis.
Whilst they found that several of the degradation products were the same as in adult arthritis, the key, signature fragment was absent in JIA. The unexpected finding suggests that there are different causes in JIA compared with adult rheumatoid arthritis, which means JIA is not just the child version of rheumatoid arthritis.
JIA is a chronic disease characterised by persistent inflammation which, if unresolved, can lead to joint destruction and permanent disability. Juvenile idiopathic arthritis is the most commonly diagnosed rheumatic disease in children, with prevalence ranging between 1-4 per 1,000 children.
The current treatments for JIA are designed to manage and ease inflammation within the joint, however there are no treatments to manage or prevent cartilage erosion. The development of new treatments for limiting cartilage erosion in JIA is hampered by the lack of information on the mechanisms involved in joint destruction; studies on cartilage erosion to date have focussed exclusively on adult cartilage.
Presently there are drugs in development for the prevention of cartilage erosion in adult arthritis.
Lead researcher, A/Professor Amanda Fosang said the study has clinical implications, as current treatments for cartilage erosion which are in trial, may not be suitable for children.
“We were really surprised to find that the pattern of cartilage degradation products in JIA was different to the pattern in adults. The findings support a need to understand more about the mechanisms driving cartilage erosion in patients with juvenile arthritis because the cartilage-sparing drugs currently in development for adult therapies might not be useful for preventing cartilage erosion in children.”
She said although there has been major improvements in JIA outcomes brought about by the introduction of the anti-inflammatory therapies, destructive cartilage erosion leading to irreparable joint abnormalities remains a long term risk for JIA patients.
Amanda said her team will now focus on trying to understand how and why the fragmentation pattern in kids is different to adults.
“Our research will now focus on understanding the difference. We want to know if a different enzyme is involved, or if other factors might also be important in the breakdown of cartilage in children.”