Phospholipase activity after β‐endorphin exposure discriminates Malassezia strains isolated from healthy and seborrhoeic dermatitis skin

Background Phospholipase activity and its induction by β‐endorphin have been associated with pathogenic Malassezia pachydermatis animal isolates. Objective To evaluate Malassezia phosholipase activity in human isolates from seborrhoeic dermatitis (SD) and healthy controls before and after β‐endorphin exposure. Methods Eighty‐four volunteers with or without SD (N = 41) were sampled. Isolated Malassezia strains were incubated in Dixon’s medium with and without 100 nmol/L β‐endorphin. Subsequently, phospholipase activity was assessed in egg‐yolk agar and the results were compared employing Wilcoxon sign test for paired data, chi‐squared test and multinomial logistic regression analysis. Results A total of 64 Malassezia strains were isolated. SD strains tended to have decreased phospholipase activity before (P = 0.057) and increased after exposure to β‐endorphin (P = 0.061) compared to isolates from healthy skin. Phospholipase activity after β‐endorphin exposure related to basal enzyme activity as a measure of per strain phospholipase inducibility by β‐endorphin did not depend on Malassezia species (P = 0.652). However, this latter biochemical trait discriminates strains isolated from SD lesional and healthy skin (P = 0.036). Conclusion β‐endorphin exposure modifies the in vitro phosholipase activity in Malassezia species isolated from SD lesional skin. This is in accordance with emerging evidence that enhanced local lipase activity is involved in the pathogenesis of SD.