title: Antimicrobial effects of alpha-MSH peptides.
abstract: The presence of the ancient anti-inflammatory peptide alpha-melanocyte-stimulating hormone [alpha-MSH (1-13), SYSMEHFRWGKPV] in barrier organs such as gut and skin suggests a role in the nonspecific (innate) host defense. alpha-MSH and and its carboxy-terminal tripeptide (11-13, KPV) were determined to have antimicrobial influences against two major and representative pathogens: Staphylococcus aureus and Candida albicans. alpha-MSH peptides significantly inhibited S. aureus colony formation and reversed the enhancing effect of urokinase on colony formation. Antimicrobial effects occurred over a broad range of concentrations including the physiological (picomolar) range. Small concentrations of alpha-MSH peptides likewise reduced viability and germ tube formation of the yeast C. albicans. Antimicrobial influences of alpha-MSH peptides could be mediated by their capacity to increase cellular cAMP. Indeed, this messenger was significantly augmented in peptide-treated yeast and the potent adenylyl cyclase inhibitor dideoxyadenosine (ddAdo) partly reversed the killing activity of alpha-MSH peptides. Reduced killing of pathogens is a detrimental consequence of therapy with anti-inflammatory drugs. Because alpha-MSH has potent anti-inflammatory effects we determined influences of alpha-MSH on C. albicans and S. aureus killing by human neutrophils. alpha-MSH peptides did not reduce killing but rather enhanced it, likely as a consequence of the direct antimicrobial activity. alpha-MSH peptides that combine antipyretic, anti-inflammatory, and antimicrobial effects could be useful in treatment of disorders in which infection and inflammation coexist.
authors.affiliation: 3rd Division of Internal Medicine, IRCCS Ospedale Maggiore, Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cutuli
authors.forename: S
authors.initials: S
authors.lastname: Cristiani
authors.forename: J M
authors.initials: JM
authors.lastname: Lipton
authors.forename: A
authors.initials: A
authors.lastname: Catania
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D000935:Antifungal Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects*; D000242:Cyclic AMP / Q000502:physiology; D003602:Cytotoxicity, Immunologic; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009504:Neutrophils / Q000502:physiology; D010446:Peptide Fragments / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D015290:Second Messenger Systems / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects*; D013329:Structure-Activity Relationship; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors; D000521:alpha-MSH / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D010446:Peptide Fragments; D000521:alpha-MSH; D000242:Cyclic AMP; D014568:Urokinase-Type Plasminogen Activator