Assessment of serum and cutaneous JAK3 in juvenile scleroderma

Background: Janus kinases (JAKs) family include JAK 1, 2, 3 and tyrosine kinase 2 play central role in cytokine and growth factor signaling and few studies suggest their possible contribution in the pathogenesis of scleroderma. Objective: To evaluate serum and cutaneous expression of JAK3 in pediatric patients with juvenile scleroderma (JSD) and their association with the disease severity. Methods: This was a pilot study that included 16 pediatric patients with JSD; they were 11 patients with juvenile systemic sclerosis (JSSc) and 5 patients with juvenile localized scleroderma (JLS). The patients were compared to 17 healthy controls. Disease severity was assessed using modified Rodnan skin score (mRSSc) and JSSc severity score (J4S) in JSSc patients while localized scleroderma damage index (LoSDI) was used in JLS patients. Serum and cutaneous expression of JAK3 were measured by enzyme linked immunosorbent assay. Results: The median (IQR) of serum JAK3 was significantly higher among JSSc patients as compared to that of controls [430 (320-520) versus 270 (180-385), p = 0.005], while comparable values were found among JLS and controls as well as JLS and JSSc patients (p>0.05). Cutaneous expression of JAK3 was comparable between all patients and controls (p>0.05). Serum and cutaneous expression of JAK 3 did not correlate significantly with mRSSc and J4S in JSSc patients and LoSDI in JLS patients (p>0.05). Conclusion: JAK3 seems to contribute to the pathogenesis of JSSc and further studies are needed to establish its role and the usefulness of using JAK 3 inhibitors in these patients.