STAT3 and juvenile idiopathic arthritis: In patients with JIA, the activity or expression level of STAT3 shows an abnormally elevated state [5]. However, this study revealed no significant difference in STAT3 expression levels between JIA patients and healthy controls, which was inconsistent with the findings of some previous reports. The reasons are as follows: First, the STAT3 detected in this study originated from serum exosomes, but STAT3 is mainly located within cells, with extremely low content in serum.