Dysregulated T and B Cell Interactions in Early-onset Oligoarticular Juvenile Idiopathic Arthritis

Key Words: Juvenile idiopathic arthritis, T cells, B cells

Oligoarticular juvenile idiopathic arthritis (oligo JIA) is a pediatric form of chronic inflammatory arthritis that is defined by limited joint involvement (<5 joints) during the first 6 months of disease. It is the most common type of inflammatory arthritis in children in North America. Many children with oligo JIA require treatment with medications that suppress the immune system, and there is no known cure for this disease. To better understand oligo JIA, this proposal seeks to study a group of children, mostly girls, with oligo JIA who share a number of clinical characteristics, including early age of disease onset (less than 6 years of age), the presence of autoantibodies, and high risk for eye inflammation.

Using biosamples from oligo JIA patients, we will study the interactions between immune cells found in the joint with a focus on T cells and B cells. T peripheral helper (Tph) cells help B cells to mature and produce antibodies in inflamed tissues. Our preliminary results show that Tph cells are expanded in the joints of children with oligo JIA. To further investigate Tph cells, we will conduct experiments to determine if this immune cell population has become overly activated, promoting B cells to produce autoantibodies that drive chronic arthritis. We will also determine if there are other subsets of T cells that can counterbalance Tph cells and inhibit their activity. Through our research, we may better understand factors that cause arthritis in oligo JIA and identify novel strategies to treat children with this disease. Our ultimate goal is to improve outcomes for children with oligo JIA.