Aislamiento de Sporothrix pallida y Trichophyton rubrum en onicomicosis de mano / Isolation of Sporothrix pallida and Trichophyton rubrum in hand onychomycosis

Se presenta un caso de onicomicosis de mano, de la cual se aisló en repetidas ocasiones Sporothrix pallida y Trichophyton rubrum. Se discute sobre los principales agentes de onicomicosis, el rol de los hon- gos ambientales y del aislamiento de S.pallida en este y en otro tipo de muestras.

It reports a case of hand onychomycosis, which was isolated repeatedly Sporothrix pallida and Trichophyton rubrum. We discuss the main agents of onychomycosis, the role of the environmental fungi and S.pallida isolation in this and other samples.

Transmigração endotelial do fungo patogênico Sporothrix schenckii: modulação da via de p38MAPK/MLCK, Src e de moléculas de adesão celular / Endothelial transmigration of the pathogenic fungus, Sporothrix schenckii: pathway modulation of p38MAPK/MLCK, Src and cell adhesion molecules

Sporothrix schenckii é um fungo dimórfico, agente etiológico da esporotricose, uma micose subaguda ou crônica que pode eventualmente evoluir para complicações sistêmicas, principalmente em pacientes imunocomprometidos. O endotélio exerce um papel crucial durante infecções disseminadas já que, juntamente com as células epiteliais, representa uma barreira a ser ultrapassada por microorganismos invasores. Em estudos anteriores, observamos que S. schenckii transmigra preferencialmente pela rota paracelular (passagem entre células endoteliais adjacentes), interagindo em seguida com componenetes da matriz subendotelial. Também foram identificadas algumas vias de sinalização relacionadas à diferentes fases da interação de leveduras de S. schenckii com o endotélio in vitro (associação/endocitose, transmigração). No entanto, a correlação entre tais vias de sinalização e os mecanismos celulares da invasão do endotélio pelo fungo não foram efetivamente demonstrados. No presente trabalho, a análise do perfil de proteínas endoteliais totais fosforiladas em resíduos de tirosina mostrou que S. schenckii induz fosforilações em tempos curtos (< 15 minutos), em proteínas de massas moleculares 20, 13, 12 e 6KDa, enquanto alunas proteínas de mais alto peso molecular (83, 123, 136, 140 e 193 KDa) persistem fosforiladas em tempos mais longos durante a infecção (6 horas). As vias de transdução de sinais disparadas pela interação do fungo com o endotélio foram investigadas através do uso de inibidores da ativação de MAPKs p38 (SB 203580) e ERK (PD 98059), MLCK (W7) e de um quelante de Ca2+ intracelular (BAPTA). A transmigração de S. schenckii através de monocamadas de HUVECs por 6 horas mostrou ser dependente da ativação de ERK e p38, ions Ca2+ intracelular e MLCK. Estas vias estão também envolvidas nos rearranjos do citoesqueleto de actina que levam à contratilidade celular e aumento da permeabilidade endotelial. A interação do fungo com HUVECs induziu ativação de Src...

Sporothrix schenckii, a dimorphic fungus, is the causative agent of sporotrichosis, a cutaneous/subcutaneous mycosis which can eventually evolve to systemic complications, mainly in immunocompromised patients. The primary interaction of pathogenic fungi with endothelial cells (EC) is throught to be essential for the development of systemic infections. We have previously shown that S. schenckii cross endothelial monolayers through a paracellular pathway, in a process also modulated by the subendothelial matrix, and that the fungus is able to alter host signaling pathways. We observed that the interaction of S. schenckii with human umbilical vein endothelial cells (HUVECs) was regulated by tyrosine-phosphorylation of EC proteins. In the present work, we observed that S. schenckii stimulates the early increase (<15 minutes) in tyrosine-phorphorylation of 20, 13, 12 e 6 KDa endothelial proteins, whereas tyrosine-phosphorylation of higher molecular weight proteins (83, 123, 136, 140 e 193 KDa) persists up to 6 hours of endothelial infection. Selective signal transduction inhibitors (SB203580 and W7, for blocking p38 MAPK and MLCK activation, respectively) were able to inhibit transendothelial migration of S. schenckii. The process was also modulated by Ca++ions. These signaling pathways are crucial for the actin rearrangement associated to impairment of endothelial permeability. Long-term (3 hours) interaction of S. schenckii with HUVECs lead to increase of MLC2 phosphorylation and Src activation. Src was shown by others to be involved in the phosphorylation of VE-cadherin, thus provoking adherent junctions (AJs) disassembly. We found that S. schenckii induces tyrosine-phosphorylation of endothelial VE-cadherin up to 3 hours of interaction with endothelial cells. VE-cadherin phosphorylation can be triggered by the activation of E-selectin in endothelial cells. Since the time-course of the major signaling events correlated with the time needed...

Adhesion of the human pathogen Sporothrix schenckii to several extracellular matrix proteins

The pathogenic fungus Sporothrix schenckii is the causative agent of sporotrichosis. This subcutaneous mycosis may disseminate in immunocompromised individuals and also affect several internal organs and tissues, most commonly the bone, joints and lung. Since adhesion is the first step involved with the dissemination of pathogens in the host, we have studied the interaction between S. schenckii and several extracellular matrix (ECM) proteins. The binding of two morphological phases of S. schenckii, yeast cells and conidia, to immobilized type II collagen, laminin, fibronectin, fibrinogen and thrombospondin was investigated. Poly (2-hydroxyethyl methacrylate) (poly-HEMA) was used as the negative control. Cell adhesion was assessed by ELISA with a rabbit anti-S. schenckii antiserum. The results indicate that both morphological phases of this fungus can bind significantly to type II collagen, fibronectin and laminin in comparison to the binding observed with BSA (used as blocking agent). The adhesion rate observed with the ECM proteins (type II collagen, fibronectin and laminin) was statistically significant (P<0.05) when compared to the adhesion obtained with BSA. No significant binding of conidia was observed to either fibrinogen or thrombospondin, but yeast cells did bind to the fibrinogen. Our results indicate that S. schenckii can bind to fibronectin, laminin and type II collagen and also show differences in binding capacity according to the morphological form of the fungus