Why does Rheumatoid Arthritis start in the distal joints of the hands?

Why does Rheumatoid Arthritis start in the distal joints of the hands?

PD Dr. Dr. med. Caroline Ospelt, Center of Experimental Rheumatology, Department of Rheumatology, University Hospital of Zurich

Rheumatoid Arthritis (RA) is a systemic autoimmune disease with a distinct pattern of joint involvement. The chronic inflammation is typically localized in the small, distal joints of the hands and feet. More proximal joints, e.g. knees are involved less often and usually later in disease, while some joints, like hips or spine are typically spared.

In our analysis of joint specific differences between synovial fibroblasts from different joints, we found many genes that were differentially expressed in hand compared to shoulder and knee synovial fibroblasts. The expression of these genes might render the small distal joints of the hands and feet more susceptible to developing RA. Therefore, we want to further analyze these genes and characterize their specific function in distal joints of the body.

The typical pattern of joint affection seen in RA clearly shows us that anatomic location matters in disease development. Nevertheless, the cause of this typical pattern has hardly been addressed by researchers and therefore remains incomprehensible. Unraveling why RA starts in distal joints, but spares other joints, brings us a decisive step forward in understanding RA pathogenesis and is key to prevent the progression of RA and develop better treatment.

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