Role of β-endorphin on phospholipase production in Malassezia pachydermatis in dogs:: new insights into the pathogenesis of this yeast

Malassezia spp. are lipophilic yeasts that are part of the normal cutaneous microflora and sometimes act as pathogens causing dermatitis. This study investigated the interactions occurring between beta-endorphin and phospholipase activity in isolates of M. pachydermatis in dogs presenting cutaneous lesions. Phospholipase production was evaluated and quantified on 144 isolates suspended in Dixon broth to which different beta-endorphin concentrations (from 600 to 0.6 pM) were added. The isolates were divided into three groups: group A comprised isolates from lesional skin of dogs with dermatitis confined to one site, group B consisted of isolates from the healthy skin of the same dogs with localized lesions, and group C was made up of isolates from assorted skin sites of healthy dogs. A statistically higher phospholipase activity than that of the controls was recorded in group B at all tested beta-endorphin concentrations. In groups A (Pz =0.62) and C (Pz =0.62) phospholipase activity was statistically higher than the controls only at a concentration of 600 pM. This study suggests that beta-endorphin plays an important role in the production of phospholipase in M. pachydermatis isolates and provides evidence that beta-endorphin concentrations affect the number but not the Pz value of phospholipase-producing isolates. B-endorphin concentrations may play a relevant role in inducing M. pachydermatis cell differentiation towards the production or non-production of phospholipase.