Serum level of the human antimicrobial cathelicidin (hCAP18/LL-37) in patients with psoriasis vulgaris

Introduction : Psoriasis is a chronic immune-mediated inflammatory disease. Human cathelicidin (hCAP18/LL37) has been elucidated recently as a modulator of inflammation in the affected skin. Vitamin D may induce expression of this antimicrobial peptide. Our trial aimed to study the circulating level of hCAP18/LL-37 and to explore its relationship with the severity of psoriasis. Material and Methods : 79 patients with moderate to severe psoriasis (PASI >10) were included in a retrospective analysis. Stored serum samples were used for assessment of 25-hydroxyvitamin D - 25(OH)D and to measure the circulating human cathelicidin (LL-37). Results : In a study group of 79 patients we assessed mean level of 25(OH)D of 30.25 nmol/l (95% CI 25.87 – 34.62 nmol/l). Mean circulating cathelicidin was 27.17 ng/ml (95% CI 21.52 – 32.83 ng/ml). Only 8.9% of patients had LL-37 level > 54 ng/ml. Although circulating LL-37 was lower in severe psoriasis than in moderate psoriasis (24.33 ng/ml vs. 31.14 ng/ml), the variation is nonsignificant. We further evaluated the association of LL-37 with both PASI score and 25(OH)D concentration in the subgroup of patients with vitamin D deficiency (n=39). It was interesting to find a significant correlation between the level of LL-37 and 25(OH)D (r=0.38, p=0.017) and inverse association between the level of LL-37 and PASI (r= -0.30, p=0.06). Conclusion : In this pilot trial we assessed low serum levels of cathelicidin antimicrobial peptide in the patients with psoriasis. LL-37 may be discussed as related to PASI and 25(OH)D in a subgroup of psoriatic patients with vitamin D deficiency.