Lipolytic activity of Malassezia spp. on inflamed seborrheic areas increases after exposure to beta-endorphin

Abstract

Annotation. The opiate system of the skin modulates inflammation and regeneration, while metabolic products of some bacteria and fungi disrupt the skin barrier and cause inflammation. Therefore, the study aimed to evaluate the effect of beta-endorphin (BE) on the lipolytic activity (LA) of Malassezia spp. isolated from both seborrheic areas and healthy skin of patients with seborrheic dermatitis. The study included 42 patients with moderate and severe forms of SD, with positive growth of Malassezia spp., and 17 medical workers without any skin diseases constituting the control group. Two smears were taken from the SD patients: from the face, specifically inflamed areas affected by SD, and intact skin of the sternum. Samples were transferred to MLNA (37°C; 72 h), colonies were suspended in Dixon broth, and 500 nmol/L human BE was added (3 days; 32 °C). 1 ml of the suspension was then applied to yolk agar (7 days; 35 °C). The precipitation zone was considered a sign of the presence of LA. The following statistical research methods were used: chi-square test, Mann-Whitney t-test, and Student’s test. Half of the Malassezia spp. isolated from healthy individuals did not show any LA before and after BE exposure. 69% of samples obtained from healthy areas and 95% of samples from inflamed skin areas from SD patients had LA. After BE stimulation, all samples from healthy areas of SD patients had LA. In healthy individuals, the average value of the LA did not show a significant difference after BE exposure (0.99 (0.99-1.00) vs 0.95 (0.92-0.97) p=0.358). In patients with SD, the intensity of lipolysis significantly increased. In samples obtained from healthy areas, the difference in LA was smaller than in samples from inflamed skin areas (0.06 p≤0.031; 0.22 p≤0.001). However, when comparing the intensity of LA in samples from healthy areas of SD patients and healthy individuals, no significant difference was found either before or after BE stimulation (0.91 (0.86-0.95) vs 0.95 (0.92-0.97) p=0.173). It was established that BE increases the LA of Malassezia spp., which colonizes the inflamed skin areas of patients with SD. Further research using opioid receptor blockers for the treatment of seborrheic dermatitis would be a logical next step.