Abstract
Purpureocillium lilacinum is a filamentous, hyaline fungus considered an emerging pathogen in humans. The aim of our study was to evaluate the outcome of hyalohyphomycosis in C57BL/6 murine models inoculated with two clinical P. lilacinum isolates (S1 and S2). Each isolate was inoculated in mice randomly distributed in immunocompetent (CPT) and immunosuppressed (SPS) groups. Mice were evaluated at day 7, 21, and 45 after inoculation for histopathological analysis, recovery of fungal cells, and immunological studies. Histological analysis showed scarce conidia-like structures in lung tissue from CPT mice and a lot of fungal cells in SPS mice inoculated with S2 compared to mice inoculated with S1. The maximum recovery of fungal cells was seen in CPT mice inoculated with both isolates at day 7, but with mean significantly higher in those inoculated with S2 isolate. Phenotypical characterization of T cells showed TCD8+ lymphocytes predominance over TCD4+ in immunosuppressed mice infected and control groups. We also observed higher percentages of the central and effector memory/effector phenotype in CPT mice infected with S2 strain, especially in TCD8+ in the initial period of infection. Regulatory T cells showed higher percentages in immunosuppressed, predominantly after the acute phase. Our results showed that the P. lilacinum is a fungus capable to cause damages in competent and immunosuppressed experimental hosts. Furthermore, S2 isolate seems to cause more damage to the experimental host and it was possible to identify different cellular subsets involved in the mice immune response.
Highlights
Purpureocillium lilacinum (Thom) Luangsa-ard, Houbraken, Hywel-Jones and Samson, comb. nov. is a filamentous, hyaline, anamorphic fungus (Luangsa-Ard et al, 2011) considered an emerging pathogen in humans, especially immunosuppressed
The aim of this study was to evaluate the outcome of hyalohyphomycosis in immunocompetent and immunosuppressed C57BL/6 murine models inoculated with P. lilacinum clinical isolates and to characterize phenotypically the systemic immune response
Our results corroborate those authors statement since experimental host immunosuppression was necessary to provoke hyalohyphomycosis clinical signs by P. lilacinum in C57BL/6 murine model as well as in BALB/c mice studied by Brito et al (2011)
Summary
Purpureocillium lilacinum (Thom) Luangsa-ard, Houbraken, Hywel-Jones and Samson, comb. nov. is a filamentous, hyaline, anamorphic fungus (Luangsa-Ard et al, 2011) considered an emerging pathogen in humans, especially immunosuppressed. Is a filamentous, hyaline, anamorphic fungus (Luangsa-Ard et al, 2011) considered an emerging pathogen in humans, especially immunosuppressed. The clinical manifestations of hyalohyphomycosis caused by P. lilacinum may vary from localized infection in immunocompetent hosts to disseminated infection in immunosuppressed individuals. The virulence of P. lilacinum has been considered moderate by some authors and in experimental models it has been reported as low and requiring high inocula along with immunosuppression of the animals to establish infection (Pujol et al, 2002; Pastor and Guarro, 2006). Our group showed the ability of this fungus to infect and cause disease in immunocompetent and immunosuppressed BALB/c mice with low inoculums (Brito et al, 2011)
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