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Updated: Jun 25, 2026
Infecting Mice with Malassezia spp. to Study the Fungus-Host Interaction
Published on: November 6, 2019
Expression of the micro-opioid receptor on Malassezia pachydermatis and its effect in modulating phospholipase
C Cafarchia1, M E Dell'Aquila, D Traversa
1Department of Veterinary Public Health, Faculty of Veterinary Medicine, University of Bari, Valenzano, Bari, Italy.
Abstract:
Malassezia spp. may act as opportunistic skin pathogens in humans and animals. Malassezia pachydermatis proliferation and phospholipase production may play a pathogenic role in the occurrence of skin lesions in dogs. This study investigates the presence of mu-opioid receptor (MOR) in M. pachydermatis strains isolated from healthy dogs and dogs with skin lesions and its effects on phospholipase activity (p.a.). P.a. of 64 M. pachydermatis isolates was evaluated using different concentrations of naloxone (Nx), a MOR antagonist. Isolates were divided into Group A (i.e., 40 isolates from 26 dogs with dermatitis) and Group B (i.e., 24 isolates from 12 healthy dogs). The MOR expression was analyzed by Western blot and immunofluorescence. A statistically higher p.a. than that of the controls was found with isolates in Group A at a Nx concentration of 10(-6) M (P<0.05). No isolate in Group B displayed p.a. in either control samples or in the presence of any Nx concentration. Immunoblotting revealed two positive MOR immunoreactive bands of approximately 65 and 98 kDa. MOR expression and localization was also demonstrated by immunofluorescence in isolates from Groups A and B. This study provides the first evidence of MOR expression on M. pachydermatis cell membranes pointing to its possible role in modulating p.a. production in isolates from dogs with skin lesions.
Insights
Malassezia pachydermatis, a yeast causing dog skin issues, expresses mu-opioid receptors (MOR). This receptor influences phospholipase activity in yeast from dogs with dermatitis, suggesting a role in skin lesions.
Area of Science:
- Veterinary Dermatology
- Microbiology
- Molecular Biology
Background:
- Malassezia species are opportunistic pathogens implicated in human and animal skin conditions.
- Malassezia pachydermatis proliferation and phospholipase production are suspected contributors to canine dermatitis.
- The role of specific receptors in Malassezia pathogenesis remains largely unexplored.
Purpose of the Study:
- To investigate the presence and expression of mu-opioid receptor (MOR) in Malassezia pachydermatis isolates from healthy dogs and dogs with skin lesions.
- To evaluate the effect of MOR antagonism on the phospholipase activity of M. pachydermatis.
Main Methods:
- Isolation and characterization of M. pachydermatis from canine skin.
- Phospholipase activity assays using varying concentrations of naloxone (a MOR antagonist).
- Analysis of MOR expression via Western blot and immunofluorescence.
Main Results:
- M. pachydermatis isolates from dogs with dermatitis (Group A) exhibited significantly higher phospholipase activity in the presence of naloxone compared to controls.
- Isolates from healthy dogs (Group B) showed no significant phospholipase activity under any tested condition.
- Western blot confirmed MOR expression with bands at approximately 65 and 98 kDa; immunofluorescence localized MOR on the cell membrane.
Conclusions:
- This study presents the first evidence of MOR expression on the cell membrane of Malassezia pachydermatis.
- MOR expression in M. pachydermatis may play a role in modulating phospholipase activity, particularly in isolates from dogs with skin lesions.
- These findings suggest MOR as a potential target for understanding and managing canine Malassezia-associated dermatitis.
