Distinct expression profiles of inflammasome-associated genes in systemic juvenile idiopathic arthritis

This study aimed to clarify the activation profile of inflammasome-associated genes in systemic JIA (s-JIA).

Sixteen patients with s-JIA, including four patients with macrophage activation syndrome (MAS) associated with s-JIA and 10 healthy controls (HCs) were enrolled. Whole blood samples were collected upon diagnosis with s-JIA or MAS. mRNA was purified and the mRNA expressions of inflammasome-associated genes was analysed using the Human Inflammasomes RT2 Profiler™ polymerase chain reaction (PCR) Array (Qiagen Sciences).

The mRNA expression levels of six genes (NLRC4, AIM2, CASP5, NAIP, TNFSF4, MAPK11) were significantly elevated in patients with s-JIA compared with HCs. The expression of IRF1 and NFKB1A was significantly elevated in patients with MAS compared with those with s-JIA in the acute phase. The mRNA expression levels of patients with s-JIA were clustered into two distinct groups: the MYD88-dominant and NLRC5-dominant groups. The MYD88-dominant group had a significantly higher number of joints with active disease.

NLRC4, AIM2 inflammasome and CASP5 activation may play an important role in s-JIA. IRF1 may be associated with the development of MAS. The distinct expression profile of inflammasome-associated genes in s-JIA may indicate the heterogeneity of s-JIA.