ABSTRACT Background Psoriasis is a chronic inflammatory skin disease often associated with systemic conditions like psoriatic arthritis and inflammatory bowel disease (IBD). Calprotectin, an inflammatory biomarker commonly used in IBD, has also been found elevated in psoriasis. Objectives This study examined serum and fecal calprotectin levels in patients with moderate‐to‐severe psoriasis who did not respond to TNF‐α inhibitors and were switched to brodalumab, an IL‐17 inhibitor. Methods This open‐label, randomized, parallel‐group cross‐over study included 20 patients. Serum and fecal calprotectin levels were measured at baseline and after 12 weeks of brodalumab treatment. Statistical analysis assessed changes in calprotectin levels and their correlation with clinical factors. Results Elevated serum and fecal calprotectin levels were observed pre‐treatment, particularly in fecal samples. After switching to brodalumab, no significant changes in calprotectin levels were found. Additionally, no correlations between fecal and serum calprotectin levels and PASI, BMI, age, sex, NSAID or PPI use, or disease duration were identified. Conclusions Elevated calprotectin levels, especially fecal, suggest a possible link to gut dysbiosis in psoriasis. However, no correlation with disease severity (PASI) was found. The study's small sample size and lack of a control group highlight the need for further investigation. Trial Registration SAHL1011. EudraCT number: 2018‐001021‐10.
Vižlin et al. (2026) studied this question.