Damage-associated molecular patterns--emerging targets for biologic therapy of childhood arthritides

Juvenile idiopathic arthritis (JIA) is a group of chronic childhood arthritides of unknown origin. Although the use of glucocorticoids and immunosuppressants brought a substantial improvement in treatment, the present therapeutic regime could not be considered satisfactory. As inflammation seems to be an essential part of pathogenesis of JIA, efforts have been made to develop pharmaceutical means to mitigate the innate immune system. Emerging targets for treatment are alarmins, a family of multifunctional intracellular proteins with strong pro-inflammatory activity. In the context of JIA, particularly interesting are high mobility group box 1 (HMGB-1) and three members of the S100 family: S100A8, S100A9, and S100A12. No definite conclusion can be made at the time, but both animal models and clinical studies support the concept of alarmins as possible key mediators of JIA. Therefore, pharmacological interference with alarmin pathways could turn out to be an excellent strategy for long-term management of JIA. Several options have been tested and they either inhibit the release of alarmins or sequester the already secreted ones. Although still very few in number, therapeutic experiments on mice are quite optimistic. Thus, it was the purpose of the present review to give an overview of the present knowledge on the topic and to bring this exciting new therapeutic possibility to the focus of rheumatologists.