3. Discussion
Chikungunya fever causes arthritis, which often persists for a long time in many cases. The sibling patients also suffered from arthralgia even with taking non-steroidal anti-inflammatory drugs. The sister in particular had severe symptoms of arthralgia that persisted for about a year. Based on the results of serum IL-36α and IL-36β levels, the association between IL-36 and chikungunya fever was discussed. Both IL-36α and IL-36β were reduced by 56 days. In the case of psoriatic arthritis, IL-36 activates dendritic cells inducing Th17 cells to generate IL-17 and IL-22, resulting in persistent arthritis. Therefore, the mechanism of chronic arthritis caused by psoriatic arthritis is different from that of chronic arthritis in chikungunya fever and IL-36 may not be involved in the chronic arthritis of chikungunya fever. IL-36α is produced by monocytes, B cells, and T cells. IL-36β is produced by dendritic cells and induces proinflammatory cytokines, including IL-12, IL-1β, IL-6, and TNF-α. Both IL-36α and IL-36β play an important role in host immunity, and it has been suggested that one physiological function of IL-36 may be to counteract microbial immune evasion [5]. IL-36β was highest at the initial visit, indicating that inflammatory cytokines may have been induced during the infection control process. And IL-36α was persistently high or increased from the time of initial visit to one week, suggesting that the acquired immune mechanism may be the peak. IL-36 might act as an immunological defense mechanism during chikungunya virus infection.