Neutrophil Extracellular Traps Serve as Key Effector Molecules in the Protection Against Phialophora verrucosa

Phialophora verrucosa (P. verrucosa) is a pathogen that can cause chromoblastomycosis and phaeohyphomycosis. Recent evidence suggests that neutrophils can produce neutrophil extracellular traps (NETs) that can protect against invasive pathogens. As such, we herein explored the in vitro functional importance of P. verrucosa-induced NET formation. By assessing the co-localization of neutrophil elastase and DNA, we were able to confirm the formation of classical NETs entrapping P. verrucosa specimens. Sytox Green was then used to stain these NETs following neutrophil infection with P. verrucosa in order to quantify the formation of these extracellular structures. NET formation was induced upon neutrophil exposure to both live, UV-inactivated, and dead P. verrucosa fungi. The ability of these NETs to kill fungal hyphae and conidia was demonstrated through MTT and pouring plate assays, respectively. Overall, our results confirmed that P. verrucosa was able to trigger the production of NETs, suggesting that these extracellular structures may represent an important innate immune effector mechanism controlling physiological responses to P. verrucosa infection, thereby aiding in pathogen control during the acute phases of infection.

Silver(I) and Copper(II) Complexes of 1,10-Phenanthroline-5,6-Dione Against Phialophora verrucosa: A Focus on the Interaction With Human Macrophages and Galleria mellonella Larvae

Phialophora verrucosa is a dematiaceous fungus that causes mainly chromoblastomycosis, but also disseminated infections such as phaeohyphomycosis and mycetoma. These diseases are extremely hard to treat and often refractory to current antifungal therapies. In this work, we have evaluated the effect of 1,10-phenanthroline-5,6-dione (phendione) and its metal-based complexes, [Ag (phendione)2]ClO4 and [Cu(phendione)3](ClO4)2.4H2O, against P. verrucosa, focusing on (i) conidial viability when combined with amphotericin B (AmB); (ii) biofilm formation and disarticulation events; (iii) in vitro interaction with human macrophages; and (iv) in vivo infection of Galleria mellonella larvae. The combination of AmB with each of the test compounds promoted the additive inhibition of P. verrucosa growth, as judged by the checkerboard assay. During the biofilm formation process over polystyrene surface, sub-minimum inhibitory concentrations (MIC) of phendione and its silver(I) and copper(II) complexes were able to reduce biomass and extracellular matrix production. Moreover, a mature biofilm treated with high concentrations of the test compounds diminished biofilm viability in a concentration-dependent manner. Pre-treatment of conidial cells with the test compounds did not alter the percentage of infected THP-1 macrophages; however, [Ag(phendione)2]ClO4 caused a significant reduction in the number of intracellular fungal cells compared to the untreated system. In addition, the killing process was significantly enhanced by post-treatment of infected macrophages with the test compounds. P. verrucosa induced a typically cell density-dependent effect on G. mellonella larvae death after 7 days of infection. Interestingly, exposure to the silver(I) complex protected the larvae from P. verrucosa infection. Collectively, the results corroborate the promising therapeutic potential of phendione-based drugs against fungal infections, including those caused by P. verrucosa.

Chromoblastomycosis Caused by Phialophora—Proven Cases from Mexico

Chromoblastomycosis is a chronic severely mutilating disease caused by fungi of the order Chaetothyriales. Classically, Phialophora verrucosa has been listed among these etiologic agents. This species is known to occur in the environment and has been found to cause other infections like phaeohyphomycosis, while reported cases of chromoblastomycosis are scant. Phialophora is phylogenetically diverse, and thus retrospective confirmation of etiology is necessary. We studied ten proven cases of chromoblastomycosis from Mexico and further analyzed the population genetics and genomics of the Phialophora species to understand their pathogenicity and predilection. The clinical strains were molecularly identified as Phialophora americana (n = 4), Phialophorachinensis (n = 4), and Phialophora macrospora (n = 2). No genetic distinction between clinical and environmental strains was possible. Further analysis of strains from diverse origins are needed to address eventual differences in virulence and niche predilection between the species.

Los animales domésticos (perros y gatos) como reservorio fúngico

En una investigación epidemiológica efectuada en la ciudad de Valparaíso y sus alrededores, entre los años 1985-86, se estudió mediante la técnica del tapete la presencia de hongos patógenos y oportunistas en 278 animales domésticos -191 perros y 87 gatos- sin lesiones clínicas aparentes de dermatofitosis en su pelaje.En los 191 perros, un 6,3% presentó dermatófitos zoofíficos (4 Trichophyton mentagrophytes y 8 Microsporum canis) y un 17,3% de dermatofitos geofílicos (2 Microsporum gypseum-fulvum complex, 6 Keratinomyces ajelloi y 24 Trichophyton terrestre). Los 87 gatos presentaron un 18,4% de zoofíficos (2 T. mentogrophytes, 14 M. canis) y un 12,6% de geofí1icos (1 M. gypseum-fulvum complex, 4 K. ajelloi y 4 T. terrestre).La mayor frecuencia de M. canis (16,1% en gatos y solo un 4,2% en perros}, indica que este agente es capaz de sobrevivir en el pelaje sin causar lesiones aparentes y debe considerarse la especie Zoo-antropofílica más común transmisible al hombre en la edad pediátrica.Entre los Onygenales e Hyphomycetes relacionados, la mayoría de los aislamientos corresponde a las especies de chrysosporium (30,9% del total de perros y 50,6% del total de gatos).Entre las especies fúngicas potencialmente patógenas, puede apreciarse una franca predominancia de los géneros Scopulariopsis, Altenaria y Aspergillus en perros y de Scopulariopsis y Alrernaria. en gatos. Phialophora verrucosa y Exophiala jeanselmei, se destacan como hallazgos interesantes