Resistance of melanized yeast cells of Paracoccidioides brasiliensis to antimicrobial oxidants and inhibition of phagocytosis using carbohydrates and monoclonal antibody to CD18.
Paracoccidioides brasiliensis, a thermal dimorphic fungal pathogen, produces a melanin-like pigment in vitro and in vivo. We investigated the involvement of carbohydrates and monoclonal antibody to CD18, on phagocytosis inhibition, involving macrophage receptors and the resistance of melanized fungal cells to chemically generated nitric oxide (NO), reactive oxygen species (ROS), hypochlorite and H2O2. Our results demonstrate that melanized yeast cells were more resistant than nonmelanized yeast cells to chemically generated NO, ROS, hypochlorite and H2O2, in vitro. Phagocytosis of melanized yeast cells was virtually abolished when mannan, N-acetyl glucosamine and anti-CD18 antibody were added together in this system. Intratracheal infection of BALB/c mice, with melanized yeast cells, resulted in higher lung colony forming units, when compared to nonmelanized yeast cells. Therefore, melanin is a virulence factor of P. brasiliensis.
Silva
Marcelo Barbosa da
MB
Departamento de Microbiologia, Laboratório de Micologia Médica - LIM53 - Hospital de Clínicas, Faculdade de Medicina, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brasil .
Thomaz
Luciana
L
Marques
Alexandre Ferreira
AF
Svidzinski
Artur E
AE
Nosanchuk
Josh D
JD
Casadevall
Arturo
A
Travassos
Luiz R
LR
Taborda
Carlos P
CP
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D018821:CD18 Antigens / Q000187:drug effects; D002241:Carbohydrates / Q000494:pharmacology; D008264:Macrophages / Q000382:microbiology*; D008543:Melanins / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D016877:Oxidants / Q000494:pharmacology*; D010228:Paracoccidioides / Q000187:drug effects / Q000378:metabolism / Q000472:pathogenicity*; D010587:Phagocytosis; D037521:Virulence Factors / Q000502:physiology
D000911:Antibodies, Monoclonal; D000935:Antifungal Agents; D018821:CD18 Antigens; D002241:Carbohydrates; D008543:Melanins; D016877:Oxidants; D037521:Virulence Factors