OBJECTIVES Malassezia spp. may act as opportunistic skin pathogens of humans and animals [Chen TA, Hill PB. Vet Dermatol 2005; 16: 4-26]. Malassezia pachydermatis proliferation and phospholipase production may play a pathogenic role in the occurrence of skin lesions in dogs [Cafarchia C, Otranto D. J Clin Microbiol 2004; 42: 4868-4869]. G–protein associated with opioid receptors (e.g., μ opioid receptor - MOR) at the cellular membrane level has been known to modulate the activity of some phospholipases (i.e., Cβ and A2) [Pan YXDNA Cell Biol. 2005; 24: 736-750]. Endogenous opioid peptides, such as β –endorphin, have a high affinity with MOR and may affect multiple physiological functions in both the central nervous system and peripheral tissues [Slominski A J Invest Dermatol 2003; 120: 1073-1080]. It has been suggested that β –endorphin might play a role in inducing M. pachydermatis cell differentiation towards the production or non-production of phospholipase [Cafarchia et al., Med Mycol. 2007; 45:11-15]. However, no information is currently available on the expression of MOR on M. pachydermatis cell membranes. Thus, the aim of the present work was to study MOR expression on the membrane of M. pachydermatis cells and its role in modulating phospholipase activity in yeasts isolated from healthy dogs and dogs with skin lesions. METHODS Phospholipase Activity was assessed by means of the egg-yolk plate method as previously reported [Cafarchia et al., Med Mycol. 2007; 45:11-15] on 64 M. pachydermatis isolates 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. RESULTS A statistically higher p.a. than that of the controls was recorded in isolates from 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. Using Western blot analysis, a band corresponding to MOR protein (with a molecular weighting of about 65 kDa) was observed in the protein fraction obtained from both clones of Group A and Group B. An additional band of around 98kDa was also detected, with a higher expression in the clone from Group B than that from Group A. MOR expression and localization was also demonstrated by immunofluorescence in isolates from Groups A and B. CONCLUSION This study suggests that opioid receptors are present in isolates of M. pachydermatis and may be involved in mediating the effects of opioid agents. Their expression mechanisms might be strictly related to the chemical composition of the skin and may have a role to play in influencing the pathogenic or commensal phenotype of Malassezia. Further functional investigations of opioid receptors and their expression mechanism could raise hypotheses about pathogenic processes in animals colonized by M. pachydermatis, thus opening new avenues for the topical control of Malassezia lesions.
Opioid receptor on Malassezia pachydermatis cells
CAFARCHIA, Claudia;DELL'AQUILA, Maria Elena;ALBRIZIO, MARIA;
2009-01-01
Abstract
OBJECTIVES Malassezia spp. may act as opportunistic skin pathogens of humans and animals [Chen TA, Hill PB. Vet Dermatol 2005; 16: 4-26]. Malassezia pachydermatis proliferation and phospholipase production may play a pathogenic role in the occurrence of skin lesions in dogs [Cafarchia C, Otranto D. J Clin Microbiol 2004; 42: 4868-4869]. G–protein associated with opioid receptors (e.g., μ opioid receptor - MOR) at the cellular membrane level has been known to modulate the activity of some phospholipases (i.e., Cβ and A2) [Pan YXDNA Cell Biol. 2005; 24: 736-750]. Endogenous opioid peptides, such as β –endorphin, have a high affinity with MOR and may affect multiple physiological functions in both the central nervous system and peripheral tissues [Slominski A J Invest Dermatol 2003; 120: 1073-1080]. It has been suggested that β –endorphin might play a role in inducing M. pachydermatis cell differentiation towards the production or non-production of phospholipase [Cafarchia et al., Med Mycol. 2007; 45:11-15]. However, no information is currently available on the expression of MOR on M. pachydermatis cell membranes. Thus, the aim of the present work was to study MOR expression on the membrane of M. pachydermatis cells and its role in modulating phospholipase activity in yeasts isolated from healthy dogs and dogs with skin lesions. METHODS Phospholipase Activity was assessed by means of the egg-yolk plate method as previously reported [Cafarchia et al., Med Mycol. 2007; 45:11-15] on 64 M. pachydermatis isolates 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. RESULTS A statistically higher p.a. than that of the controls was recorded in isolates from 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. Using Western blot analysis, a band corresponding to MOR protein (with a molecular weighting of about 65 kDa) was observed in the protein fraction obtained from both clones of Group A and Group B. An additional band of around 98kDa was also detected, with a higher expression in the clone from Group B than that from Group A. MOR expression and localization was also demonstrated by immunofluorescence in isolates from Groups A and B. CONCLUSION This study suggests that opioid receptors are present in isolates of M. pachydermatis and may be involved in mediating the effects of opioid agents. Their expression mechanisms might be strictly related to the chemical composition of the skin and may have a role to play in influencing the pathogenic or commensal phenotype of Malassezia. Further functional investigations of opioid receptors and their expression mechanism could raise hypotheses about pathogenic processes in animals colonized by M. pachydermatis, thus opening new avenues for the topical control of Malassezia lesions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.