Abstract
Species of Scedosporium and Lomentospora are considered as emerging opportunists, affecting immunosuppressed and otherwise debilitated patients, although classically they are known from ...causing trauma-associated infections in healthy individuals. Clinical manifestations range from local infection to pulmonary colonization and severe invasive disease, in which mortality rates may be over 80%. These unacceptably high rates are due to the clinical status of patients, diagnostic difficulties, and to intrinsic antifungal resistance of these fungi. In consequence, several consortia have been founded to increase research efforts on these orphan fungi. The current review presents recent findings and summarizes the most relevant points, including the Scedosporium/Lomentospora taxonomy, environmental distribution, epidemiology, pathology, virulence factors, immunology, diagnostic methods, and therapeutic strategies.
Scedosporium apiospermum is an emerging fungal pathogen that causes both localized and disseminated infections in immunocompromised patients. Glucosylceramides (CMH, GlcCer) are the main neutral ...glycosphingolipids expressed in fungal cells. In this study, glucosylceramides (GlcCer) were extracted and purified in several chromatographic steps. Using high-performance thin layer chromatography (HPTLC) and electrospray ionization mass spectrometry (ESI-MS), N-2'-hydroxyhexadecanoyl-1-β-D-glucopyranosyl-9-methyl-4,8-sphingadienine was identified as the main GlcCer in S. apiospermum. A monoclonal antibody (Mab) against this molecule was used for indirect immunofluorescence experiments, which revealed that this CMH is present on the surface of the mycelial and conidial forms of S. apiospermum. Treatment of S. apiospermum conidia with the Mab significantly reduced fungal growth. In addition, the Mab also enhanced the phagocytosis and killing of S. apiospermum by murine cells. In vitro assays were performed to evaluate the CMHs for their cytotoxic activities against the mammalian cell lines L.929 and RAW, and an inhibitory effect on cell proliferation was observed. Synergistic in vitro interactions were observed between the Mab against GlcCer and both amphotericin B (AmB) and itraconazole. Because Scedosporium species develop drug resistance, the number of available antifungal drugs is limited; our data indicate that combining immunotherapy with the available drugs might be a viable treatment option. These results suggest that in S. apiospermum, GlcCer are most likely cell wall components that are targeted by antifungal antibodies, which directly inhibit fungal development and enhance macrophage function; furthermore, these results suggest the combined use of monoclonal antibodies against GlcCer and antifungal drugs for antifungal immunotherapy.
complex is composed of filamentous fungi, including some clinically relevant species, such as
,
and
. Glucosylceramide (GlcCer), a conserved neutral glycosphingolipid, has been described as an ...important cell surface molecule playing a role in fungal morphological transition and pathogenesis. The present work aimed at the evaluation of GlcCer structures in
and
, a clinical and an environmental isolate, respectively, in order to determine their participation in fungal growth and host-pathogen interactions. Structural analysis by positive ion-mode ESI-MS (electrospray ionization mass spectrometer) revealed the presence of different ceramide moieties in GlcCer in these species. Monoclonal antibodies against
GlcCer could recognize
and
conidia, suggesting a conserved epitope in fungal GlcCer. In addition, these antibodies reduced fungal viability, enhanced conidia phagocytosis by macrophages, and decreased fungal survival inside phagocytic cells. Purified GlcCer from both species led to macrophage activation, increasing cell viability as well as nitric oxide and superoxide production in different proportions between the two species. These results evidenced some important properties of GlcCer from species of the
complex, as well as the effects of monoclonal anti-GlcCer antibodies on fungal cells and host-pathogen interaction. The differences between the two species regarding the observed biological properties suggest that variation in GlcCer structures and strain origin could interfere in the role of GlcCer in host-pathogen interaction.
Abstract
The genus Scedosporium is composed of clinically relevant fungal species, such as Scedosporium aurantiacum, Scedosporium apiospermum, and Scedosporium boydii. Surface molecules have been ...described that play crucial roles in fungi-macrophage interaction, and many of them are pathogen-associated molecular patterns (PAMPs). The present study aims to characterize peptidoglycans obtained from Scedosporium aurantiacum and Scedosporium minutisporum, a clinical and an environmental isolate, respectively, and compare their roles in pathogen-host interaction. Both molecules were characterized as peptidorhamnomannans (PRMs), similar to what has been already described for other Scedosporium species. Rabbit immune sera obtained by injecting whole cells from each species recognized both fungal cells and purified PRMs, suggesting that a cross-reaction occur between both fungi. Immunofluorescent microscopy revealed that PRMs are exposed on fungal surface. Prior incubation of purified molecules with immune sera before adding to cells led to loss of fluorescent, indicating that PRM is a major molecule recognized by immune sera. Fungi-macrophage interaction revealed that S. aurantiacum is able to survive more inside phagocytic cells than S. minutisporum, and PRM from both fungi plays a role in phagocytosis when the purified molecule is pre-incubated with macrophage. In addition, PRM induce nitric oxide release by macrophages. Our data indicate that PRM is an important PAMP exposed on fungal surface with the potential of immune modulation.
Lay Summary
In this work, peptidorhamnomannans from Scedosporium aurantiacum and Scedosporium minutisporum have been characterized. These molecules play important roles in phagocytosis and oxidative burst in peritoneal macrophages and are recognized by immune sera.
As a result of fundamental changes in the International Code of Nomenclature on the use of separate names for sexual and asexual stages of fungi, generic names of many groups should be reconsidered. ...Members of the ECMM/ISHAM working group on
Pseudallescheria/Scedosporium
infections herein advocate a novel nomenclature for genera and species in
Pseudallescheria
,
Scedosporium
and allied taxa. The generic names
Parascedosporium, Lomentospora, Petriella, Petriellopsis
, and
Scedosporium
are proposed for a lineage within
Microascaceae
with mostly
Scedosporium
anamorphs producing slimy, annellidic conidia. Considering that
Scedosporium
has priority over
Pseudallescheria
and that
Scedosporium prolificans
is phylogenetically distinct from the other
Scedosporium
species, some name changes are proposed.
Pseudallescheria minutispora
and
Petriellidium desertorum
are renamed as
Scedosporium minutisporum
and
S. desertorum
, respectively.
Scedosporium prolificans
is renamed as
Lomentospora prolificans
.
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