What is the second step in the proposed pathophysiology of enteropathic arthritis?

• A. Gut inflammation damages the intestinal barrier
• B. Molecular mimicry
• C. Bacterial antigens travel to joints
• D. Autoimmune joint damage

Answer: (C)

The key idea is the sequence linking gut disease to joint inflammation. In enteropathic arthritis, the process starts with gut inflammation that disrupts the intestinal barrier. Once the barrier is compromised, bacterial antigens can leak into the circulation and reach the joints. There, these antigens trigger an immune response that can lead to autoimmune joint inflammation, potentially through mechanisms like molecular mimicry. So the step where bacterial antigens travel to the joints is the second step because it comes after barrier disruption and serves as the immediate bridge between intestinal pathology and joint involvement. The autoimmune joint damage is the downstream result, and molecular mimicry is a mechanism that may contribute along the way but occurs after antigens reach the joints.