Changes in growth hormone receptor gene expression during therapy in children with Juvenile Idiopathic arthritis

Background: High levels of cytokines in juvenile idiopathic arthritis (JIA) can alter target cell sensitivity to growth hormone (GH) leading to short stature in adulthood. We hypothesized that the down-regulation of GH receptor (GHR) gene expression could be involved in growth failure of children with JIA. Methods: In 18 (12 F and 6 M) prepubertal JIA patients and 13 age- and sex-matched healthy children, we evaluated serum growth-promoting factors and inflammatory indexes. We also measured GHR gene expression, by real-time PCR, in lymphocytes of patients and controls. All parameters were evaluated in patients before and after treatment of JIA. Results: The most interesting (p = 0.007) result was the increase in GHR mRNA expression in all JIA patients. Moreover, we observed a significant (p = 0.0156) decrease in IL-6 levels in JIA patients after 2 years of therapy (19.37 8 41.01) with respect to basal values (90.84 ± 124.71). On the contrary, IGF-I significantly (p = 0.0005) increased to a mean SDS value of 0 (range -1.69 to +1.70 SDS) with respect to values at disease onset (-0.64 SDS). Conclusions: Our pre- liminary data suggest that the restoration of both GHR gene expression and IGF-I secretion correlate with inactive disease in JIA children.