Immuno-Histochemical Assessment of the Expression of IL-33 in Inflammatory Acne Vulgaris and the Effect of Treatment with Intense Pulsed Light on Its Expression

Abstract Background Acne vulgaris is the most common inflammatory skin condition. Inflammation is the main event in pathogenesis of acne but little is known about role of IL-33 in the pathogenesis. Objective To assess the expression of IL-33 in the tissue of inflammatory acne vulgaris patients versus controls and its relation to severity of the disease and to assess the efficacy of intense pulsed light (IPL) in treatment of inflammatory acne and on IL-33 expression. Patients and Methods We performed clinical and dermatological for thirty (30) patients complaining of inflammatory acne vulgaris divided as 15 patients with mild to moderate acne (group A) and 15 patients with severe acne (group B). Skin biopsy was taken from the lesions of the patients and normal acne prone skin from controls and immune-histochemical staining by anti-IL-33 monoclonal antibody was done. Then patients were treated by IPL sessions and another biopsy was taken from them and IHC was done to compare IL-33 expression before and after treatment. Results IL-33 was positive in 100% of patients and 80% of controls. GAGS score significantly decreased in both groups after IPL treatment; for group A GAGS score was 17.40 ± 3.46 before and 8.00 ± 2.51 after treatment and for group B it was 31.80 ± 0.94 before and 14.67 ± 3.35 after treatment. In group A, IL-33 was found to be mild in 20%, moderate in 66.7% and dense in only 13.3% of patients after treatment (compared to 20% moderate and 80% dense before treatment). In group B it turned negative in 13.3%, mild in 20%, moderate in 60.0% and dense in only 6.7% of patients after treatment (compared to 6.7% mild, 20% moderate and 73.3% dense before treatment). This means that IPL improved inflammation in acne lesions and decreased the density of inflammatory cytokines including IL-33. Conclusion IL-33 is elevated in Acne vulgaris compared to controls and IPL treatment lead to decrease expression.