Serum YKL ‐40 and IL 17 in Psoriasis: Reliability as prognostic markers for disease severity and responsiveness to treatment

YKL-40, a mammalian chitinase 3- like protein that was associated with multiple inflammatory and immune diseases. Previous studies have suggested a role for YKL-40 in psoriasis based on its significantly higher levels in the serum of psoriatic patient compared with healthy controls. The aim of this study was to determine the correlation between serum YKL-40, psoriasis severity using PASI score and serum levels of IL-17 before and after narrow-band UVB therapy. 28 patients with moderate to severe plaque psoriasis, as defined by PASI scores, were enrolled in this prospective cohort study. All cases received NB-UVB phototherapy twice weekly for 3 months. Serum YKL-40 and IL-17 levels were evaluated before and after 3 months of treatment. Clinical photographs were taken both at baseline and after 3 months. There was a statistical positive correlation between serum levels of YKL-40 and serum IL-17 levels as well as PASI score in patients with moderate to severe psoriasis before and after treatment. YKL-40 represents a reliable marker for psoriasis severity estimated by PASI and positively correlated with IL 17 as an inflammatory marker in psoriasis.