A team of scientists from Japan has identified hidden immune 'hubs' that drive joint damage in patients with rheumatoid arthritis. 

Rheumatoid arthritis (RA) is an autoimmune disease that affects millions worldwide and can have a devastating impact on patients' lives. Yet, about one in three patients responds poorly to existing treatments.

The team from Kyoto University discovered that peripheral helper T cells (Tph cells) -- a key type of immune cell involved in RA -- exist in two forms: stem-like Tph cells and effector Tph cells. The stem-like Tph cells reside in immune "hubs" called tertiary lymphoid structures within inflamed joints, where they multiply and activate B cells.