Neutralizing GM-CSF autoantibodies in pulmonary alveolar proteinosis, cryptococcal meningitis and severe nocardiosis.

BACKGROUND: Anti GM-CSF autoantibodies (aAb) have been related to acquired pulmonary alveolar proteinosis (PAP) and described in cases of severe infections such as cryptococcosis and nocardiosis in previously healthy subjects. Whether there are different anti-GM-CSF autoantibodies corresponding to these phenotypes is unclear. Therefore, we examined anti-GM-CSF autoantibodies to determine whether amount or neutralizing activity could distinguish between groups. METHODS: Plasma samples gathered in the National Institute of Health from patients with anti GM-CSF aAb and either PAP (n = 15), cryptococcal meningitis (n = 15), severe nocardiosis (n = 5) or overlapping phenotypes (n = 6) were compared. The relative amount of aAb was assessed using a particle-based approach, reported as a mouse monoclonal anti-human GM-CSF as standard curve and expressed in an arbitrary Mouse Monoclonal Antibody Unit (MMAU). The neutralizing activity of the plasma was assessed by inhibition of GM-CSF-induced intracellular phospho-STAT5 (pSTAT5) in monocytes. RESULTS: Anti-GM-CSF aAb relative amounts were higher in PAP patients compared to those with cryptococcosis (mean 495 ± 464 MMAU vs 197 ± 159 MMAU, p = 0.02); there was no difference with patients with nocardiosis (430 ± 493 MMAU) nor between the two types of infections. The dilution of plasma resulting in 50% inhibition of GM-CSF-induced pSTAT5 (approximate IC50) did not vary appreciably across groups of patients (1.6 ± 3.1%, 3.9 ± 6% and 1.8 ± 2.2% in PAP patients, cryptococcosis and nocardiosis patients, respectively). Nor was the concentration of GM-CSF necessary to induce 50% of maximal GM-CSF-induced pSTAT5 in the presence of 10 MMAU of anti-GM-CSF aAb (EC50). When studying longitudinal samples from patients with PAP or disseminated nocardiosis, the neutralizing effect of anti-GM-CSF aAb was relatively constant over time despite targeted treatments and variations in aAb levels. CONCLUSIONS: Despite different clinical manifestations, anti-GM-CSF antibodies were similar across PAP, cryptococcosis and nocardiosis. Underlying host genetics and functional analyses may help further differentiate the biology of these conditions.

MDA5 signaling induces type 1 IFN- and IL-1-dependent lung vascular permeability which protects mice from opportunistic fungal infection.

Lungs balance threat from primary viral infection, secondary infection, and inflammatory damage. Severe pulmonary inflammation induces vascular permeability, edema, and organ dysfunction. We previously demonstrated that poly(I:C) (pICLC) induced type 1 interferon (t1IFN) protected mice from Cryptococcus gattii (Cg) via local iron restriction. Here we show pICLC increased serum protein and intravenously injected FITC-dextran in the lung airspace suggesting pICLC induces vascular permeability. Interestingly, pICLC induced a pro-inflammatory signature with significant expression of IL-1 and IL-6 which depended on MDA5 and t1IFN. Vascular permeability depended on MDA5, t1IFN, IL-1, and IL-6. T1IFN also induced MDA5 and other MDA5 signaling components suggesting that positive feedback contributes to t1IFN dependent expression of the pro-inflammatory signature. Vascular permeability, induced by pICLC or another compound, inhibited Cg by limiting iron. These data suggest that pICLC induces t1IFN which potentiates pICLC-MDA5 signaling increasing IL-1 and IL-6 resulting in leakage of antimicrobial serum factors into lung airspace. Thus, induced vascular permeability may act as an innate defense mechanism against opportunistic fungal infection, such as cryptococcosis, and may be exploited as a host-directed therapeutic target.

Pulmonary Iron Limitation Induced by Exogenous Type I IFN Protects Mice from Cryptococcus gattii Independently of T Cells.

Cryptococcus neoformans causes deadly mycosis primarily in AIDS patients, whereas Cryptococcus gattii infects mostly non-HIV patients, even in regions with high burdens of HIV/AIDS and an established environmental presence of C. gattii As HIV induces type I IFN (t1IFN), we hypothesized that t1IFN would differentially affect the outcome of C. neoformans and C. gattii infections. Exogenous t1IFN induction using stabilized poly(I·C) (pICLC) improved murine outcomes in either cryptococcal infection. In C. neoformans-infected mice, pICLC activity was associated with C. neoformans containment and classical Th1 immunity. In contrast, pICLC activity against C. gattii did not require any immune factors previously associated with C. neoformans immunity: T, B, and NK cells, IFN-γ, and macrophages were all dispensable. Interestingly, C. gattii pICLC activity depended on ß-2-microglobulin, which impacts iron levels among other functions. Iron supplementation reversed pICLC activity, suggesting C. gattii pICLC activity requires iron limitation. Also, pICLC induced a set of iron control proteins, some of which were directly inhibitory to cryptococcus in vitro, suggesting t1IFN regulates iron availability in the pulmonary air space fluids. Thus, exogenous induction of t1IFN significantly improves the outcome of murine infection by C. gattii and C. neoformans but by distinct mechanisms; the C. gattii effect was mediated by iron limitation, while the effect on C. neoformans infection was through induction of classical T-cell-dependent immunity. Together this difference in types of T-cell-dependent t1IFN immunity for different Cryptococcus species suggests a possible mechanism by which HIV infection may select against C. gattii but not C. neoformansIMPORTANCECryptococcus neoformans and Cryptococcus gattii cause fatal infection in immunodeficient and immunocompetent individuals. While these fungi are sibling species, C. gattii infects very few AIDS patients, while C. neoformans infection is an AIDS-defining illness, suggesting that the host response to HIV selects C. neoformans over C. gattii We used a viral mimic molecule (pICLC) to stimulate the immune response, and pICLC treatment improved mouse outcomes from both species. pICLC-induced action against C. neoformans was due to activation of well-defined immune pathways known to deter C. neoformans, whereas these immune pathways were dispensable for pICLC treatment of C. gattii Since these immune pathways are eventually destroyed by HIV/AIDS, our data help explain why the antiviral immune response in AIDS patients is unable to control C. neoformans infection but is protective against C. gattii Furthermore, pICLC induced tighter control of iron in the lungs of mice, which inhibited C. gattii, thus suggesting an entirely new mode of nutritional immunity activated by viral signals.

Recognition of DHN-melanin by a C-type lectin receptor is required for immunity to Aspergillus.

Resistance to infection is critically dependent on the ability of pattern recognition receptors to recognize microbial invasion and induce protective immune responses. One such family of receptors are the C-type lectins, which are central to antifungal immunity. These receptors activate key effector mechanisms upon recognition of conserved fungal cell-wall carbohydrates. However, several other immunologically active fungal ligands have been described; these include melanin, for which the mechanism of recognition is hitherto undefined. Here we identify a C-type lectin receptor, melanin-sensing C-type lectin receptor (MelLec), that has an essential role in antifungal immunity through recognition of the naphthalene-diol unit of 1,8-dihydroxynaphthalene (DHN)-melanin. MelLec recognizes melanin in conidial spores of Aspergillus fumigatus as well as in other DHN-melanized fungi. MelLec is ubiquitously expressed by CD31+ endothelial cells in mice, and is also expressed by a sub-population of these cells that co-express epithelial cell adhesion molecule and are detected only in the lung and the liver. In mouse models, MelLec was required for protection against disseminated infection with A. fumigatus. In humans, MelLec is also expressed by myeloid cells, and we identified a single nucleotide polymorphism of this receptor that negatively affected myeloid inflammatory responses and significantly increased the susceptibility of stem-cell transplant recipients to disseminated Aspergillus infections. MelLec therefore recognizes an immunologically active component commonly found on fungi and has an essential role in protective antifungal immunity in both mice and humans.

Exogenous Stimulation of Type I Interferon Protects Mice with Chronic Granulomatous Disease from Aspergillosis through Early Recruitment of Host-Protective Neutrophils into the Lung.

Invasive aspergillosis (IA) remains the primary cause of morbidity and mortality in chronic granulomatous disease (CGD) patients, often due to infection by Aspergillus species refractory to antifungals. This motivates the search for alternative treatments, including immunotherapy. We investigated the effect of exogenous type I interferon (IFN) activation on the outcome of IA caused by three Aspergillus species, A. fumigatus, A. nidulans, and A. tanneri, in CGD mice. The animals were treated with poly(I):poly(C) carboxymethyl cellulose poly-l-lysine (PICLC), a mimetic of double-stranded RNA, 24 h preinfection and postinfection. The survival rates and lung fungal burdens were markedly improved by PICLC immunotherapy in animals infected with any one of the three Aspergillus species. While protection from IA was remarkable, PICLC induction of type I IFN in the lungs surged 24 h posttreatment and returned to baseline levels by 48 h, suggesting that PICLC altered early events in protection against IA. Immunophenotyping of recruited leukocytes and histopathological examination of tissue sections showed that PICLC induced similar cellular infiltrates as those in untreated-infected mice, in both cases dominated by monocytic cells and neutrophils. However, the PICLC immunotherapy resulted in a marked earlier recruitment of the leukocytes. Unlike with conidia, infection with A. nidulans germlings reduced the protective effect of PICLC immunotherapy. Additionally, antibody depletion of neutrophils totally reversed the protection, suggesting that neutrophils are crucial for PICLC-mediated protection. Together, these data show that prophylactic PICLC immunotherapy prerecruits these cells, enabling them to attack the conidia and thus resulting in a profound protection from IA.IMPORTANCE Patients with chronic granulomatous disease (CGD) are highly susceptible to invasive aspergillosis (IA). While Aspergillus fumigatus is the most-studied Aspergillus species, CGD patients often suffer IA caused by A. nidulans, A. tanneri, and other rare species. These non-fumigatus Aspergillus species are more resistant to antifungal drugs and cause higher fatality rates than A. fumigatus Therefore, alternative therapies are needed to protect CGD patients. We report an effective immunotherapy of mice infected with three Aspergillus species via PICLC dosing. While protection from IA was long lasting, PICLC induction of type I IFN surged but quickly returned to baseline levels, suggesting that PICLC was altering early events in IA. Interestingly, we found responding immune cells to be similar between PICLC-treated and untreated-infected mice. However, PICLC immunotherapy resulted in an earlier recruitment of the leukocytes and suppressed fungal growth. This study highlights the value of type I IFN induction in CGD patients.

Host immune status-specific production of gliotoxin and bis-methyl-gliotoxin during invasive aspergillosis in mice.

Delayed diagnosis in invasive aspergillosis (IA) contributes to its high mortality. Gliotoxin (GT) and bis-methyl-gliotoxin (bmGT) are secondary metabolites produced by Aspergillus during invasive, hyphal growth and may prove diagnostically useful. Because IA pathophysiology and GT's role in virulence vary depending on the underlying host immune status, we hypothesized that GT and bmGT production in vivo may differ in three mouse models of IA that mimic human disease. We defined temporal kinetics of GT and bmGT in serum, bronchoalveolar lavage fluid (BALF) and lungs of A. fumigatus-infected chronic granulomatous disease (CGD), hydrocortisone-treated, and neutropenic mice. We harvested lungs for assessment of fungal burden, histology and GT/bmGT biosynthetic genes' mRNA induction. GT levels were higher in neutropenic versus CGD or steroid-treated lungs. bmGT was persistently detected only in CGD lungs. GT, but not bmGT, was detected in 71% of sera and 50% of BALF of neutropenic mice; neither was detected in serum/BALF of CGD or steroid-treated mice. Enrichment of GT in Aspergillus-infected neutropenic lung correlated with fungal burden and hyphal length but not induction of GT biosynthetic genes. In summary, GT is detectable in mouse lungs, serum and BALF during neutropenic IA, suggesting that GT may be useful to diagnose IA in neutropenic patients.

Cryptococcus gattii Capsule Blocks Surface Recognition Required for Dendritic Cell Maturation Independent of Internalization and Antigen Processing.

Cryptococcus gattii is an emerging fungal pathogen on the west coast of Canada and the United States that causes a potentially fatal infection in otherwise healthy individuals. In previous investigations of the mechanisms by which C. gattii might subvert cell-mediated immunity, we found that C. gattii failed to induce dendritic cell (DC) maturation, leading to defective T cell responses. However, the virulence factor and the mechanisms of evasion of DC maturation remain unknown. The cryptococcal polysaccharide capsule is a leading candidate because of its antiphagocytic properties. Consequently, we asked if the capsule of C. gattii was involved in evasion of DC maturation. We constructed an acapsular strain of C. gattii through CAP59 gene deletion by homologous integration. Encapsulated C. gattii failed to induce human monocyte-derived DC maturation and T cell proliferation, whereas the acapsular mutant induced both processes. Surprisingly, encapsulation impaired DC maturation independent of its effect on phagocytosis. Indeed, DC maturation required extracellular receptor signaling that was dependent on TNF-α and p38 MAPK, but not ERK activation, and the cryptococcal capsule blocked this extracellular recognition. Although the capsule impaired phagocytosis that led to pH-dependent serine-, threonine-, and cysteine-sensitive protease-dependent Ag processing, it was insufficient to impair T cell responses. In summary, C. gattii affects two independent processes, leading to DC maturation and Ag processing. The polysaccharide capsule masked extracellular detection and reduced phagocytosis that was required for DC maturation and Ag processing, respectively. However, the T cell response was fully restored by inducing DC maturation.

Type I IFN Induction via Poly-ICLC Protects Mice against Cryptococcosis.

Cryptococcus neoformans is the most common cause of fungal meningoencephalitis in AIDS patients. Depletion of CD4 cells, such as occurs during advanced AIDS, is known to be a critical risk factor for developing cryptococcosis. However, the role of HIV-induced innate inflammation in susceptibility to cryptococcosis has not been evaluated. Thus, we sought to determine the role of Type I IFN induction in host defense against cryptococci by treatment of C. neoformans (H99) infected mice with poly-ICLC (pICLC), a dsRNA virus mimic. Unexpectedly, pICLC treatment greatly extended survival of infected mice and reduced fungal burdens in the brain. Protection from cryptococcosis by pICLC-induced Type I IFN was mediated by MDA5 rather than TLR3. PICLC treatment induced a large, rapid and sustained influx of neutrophils and Ly6Chigh monocytes into the lung while suppressing the development of eosinophilia. The pICLC-mediated protection against H99 was CD4 T cell dependent and analysis of CD4 T cell polyfunctionality showed a reduction in IL-5 producing CD4 T cells, marginal increases in Th1 cells and dramatic increases in RORγt+ Th17 cells in pICLC treated mice. Moreover, the protective effect of pICLC against H99 was diminished in IFNγ KO mice and by IL-17A neutralization with blocking mAbs. Furthermore, pICLC treatment also significantly extended survival of C. gattii infected mice with reduced fungal loads in the lungs. These data demonstrate that induction of type I IFN dramatically improves host resistance against the etiologic agents of cryptococcosis by beneficial alterations in both innate and adaptive immune responses.

Anti-granulocyte-macrophage colony-stimulating factor autoantibodies are a risk factor for central nervous system infection by Cryptococcus gattii in otherwise immunocompetent patients.

Cryptococcosis is caused by either Cryptococcus neoformans or C. gattii. While cryptococcal meningoencephalitis is caused mostly by C. neoformans in immunocompromised patients, the risk factors remain unclear for patients with no known immune defect. Recently, anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies were detected in the plasma of seven "immunocompetent" cryptococcosis patients, and the cryptococcal strains from these patients were reported as C. neoformans (three strains), C. gattii (one strain), and Cryptococcus (three strains not identified to the species level). We identified all three strains that had not been identified to the species level as C. gattii. Notably, the three strains that were reported as C. neoformans but were unavailable for species confirmation originated from Sothern California and Thailand where C. gattii is endemic. Most clinical laboratories designate C. neoformans without distinguishing between the two species; hence, these three strains could have been C. gattii. Since C. gattii infects more immunocompetent patients than C. neoformans, we pursued the possibility that this antibody may be more prevalent in patients infected with C. gattii than in those infected with C. neoformans. We screened the plasma of 20 healthy controls and 30 "immunocompetent" patients with cryptococcal meningoencephalitis from China and Australia (multiple ethnicities). Anti-GM-CSF autoantibodies were detected only in the plasma of seven patients infected by C. gattii and one healthy volunteer and in none infected by C. neoformans. While plasma from these C. gattii patients completely prevented GM-CSF-induced p-STAT5 in normal human peripheral blood mononuclear cells (PBMCs), plasma from one healthy volunteer positive for anti-GM-CSF autoantibodies caused only partial blockage. Our results suggest that anti-GM-CSF autoantibodies may predispose otherwise immunocompetent individuals to meningoencephalitis caused by C. gattii but not necessarily to that caused by C. neoformans. IMPORTANCE Cryptococcal meningoencephalitis is the most serious central nervous system (CNS) infection caused by Cryptococcus neoformans or C. gattii. Cryptococcus primarily infects immunocopromised patients but is also sporadically encountered in otherwise "immunocompetent" patients with no known risk. In a recent study, anti-GM-CSF autoantibodies were detected in the plasma of seven otherwise immunocompetent patients with cryptococcal meningoencephalitis. Four of seven (57%) cryptococcal isolates from these patients were identified as C. gattii, while three strains were unavailable for species confirmation. We collected plasma from 30 otherwise healthy patients with CNS cryptococcosis in China and Australia (multiethnic) and analyzed the samples for the presence of anti-GM-CSF autoantibodies. The results suggest that anti-GM-CSF autoantibodies are a risk factor for CNS infection by C. gattii but not C. neoformans. GM-CSF may have a specific role in host defense against C. gattii, thereby elevating the importance of determining the level of anti-GM-CSF autoantibodies which can impact clinical management.

Rapid identification of antifungal compounds against Exserohilum rostratum using high throughput drug repurposing screens.

A recent large outbreak of fungal infections by Exserohilum rostratum from contaminated compounding solutions has highlighted the need to rapidly screen available pharmaceuticals that could be useful in therapy. The present study utilized two newly-developed high throughput assays to screen approved drugs and pharmaceutically active compounds for identification of potential antifungal agents. Several known drugs were found that have potent effects against E. rostratum including the triazole antifungal posaconazole. Posaconazole is likely to be effective against infections involving septic joints and may provide an alternative for refractory central nervous system infections. The anti-E. rostratum activities of several other drugs including bithionol (an anti-parasitic drug), tacrolimus (an immunosuppressive agent) and floxuridine (an antimetabolite) were also identified from the drug repurposing screens. In addition, activities of other potential antifungal agents against E. rostratum were excluded, which may avoid unnecessary therapeutic trials and reveals the limited therapeutic alternatives for this outbreak. In summary, this study has demonstrated that drug repurposing screens can be quickly conducted within a useful time-frame. This would allow clinical implementation of identified alternative therapeutics and should be considered as part of the initial public health response to new outbreaks or rapidly-emerging microbial pathogens.

Olfm4 deletion enhances defense against Staphylococcus aureus in chronic granulomatous disease.

Chronic granulomatous disease (CGD) patients have recurrent life-threatening bacterial and fungal infections. Olfactomedin 4 (OLFM4) is a neutrophil granule protein that negatively regulates host defense against bacterial infection. The goal of this study was to evaluate the impact of Olfm4 deletion on host defense against Staphylococcus aureus and Aspergillus fumigatus in a murine X-linked gp91phox-deficiency CGD model. We found that intracellular killing and in vivo clearance of S. aureus, as well as resistance to S. aureus sepsis, were significantly increased in gp91phox and Olfm4 double-deficient mice compared with CGD mice. The activities of cathepsin C and its downstream proteases (neutrophil elastase and cathepsin G) and serum levels of IL-1ß, IL-6, IL-12p40, CXCL2, G-CSF, and GM-CSF in Olfm4-deficient as well as gp91phox and Olfm4 double-deficient mice were significantly higher than those in WT and CGD mice after challenge with S. aureus. We did not observe enhanced defense against A. fumigatus in Olfm4-deficient mice using a lung infection model. These results show that Olfm4 deletion can successfully enhance immune defense against S. aureus, but not A. fumigatus, in CGD mice. These data suggest that OLFM4 may be an important target in CGD patients for the augmentation of host defense against bacterial infection.

Chloroquine modulates the fungal immune response in phagocytic cells from patients with chronic granulomatous disease.

Invasive aspergillosis is a major threat to patients with chronic granulomatous disease (CGD). Fungal pathogenesis is the result of a diminished antifungal capacity and dysregulated inflammation. A deficient NADPH-oxidase complex results in defective phagolysosomal alkalization. To investigate the contribution of defective pH regulation in phagocytes among patients with CGD during fungal pathogenesis, we evaluated the effect of the acidotropic, antimalarial drug chloroquine (CQ) on the antifungal capacity of polymorphonuclear cells (PMNs) and on the inflammatory response of peripheral blood mononuclear cells (PBMCs). Chloroquine exerted a direct pH-dependent antifungal effect on Aspergillus fumigatus and Aspergillus nidulans; it increased the antifungal activity of PMNs from patients with CGD at a significantly lower concentration, compared with the concentration for PMNs from healthy individuals; and decreased the hyperinflammatory state of PBMCs from patients with CGD, as observed by decreased tumor necrosis factor α and interleukin 1ß release. Chloroquine targets both limbs of fungal pathogenesis and might be of great value in the clearance of invasive aspergillosis in patients with CGD.

Cryptococcus neoformans-derived microvesicles enhance the pathogenesis of fungal brain infection.

Cryptococcal meningoencephalitis is the most common fungal disease in the central nervous system. The mechanisms by which Cryptococcus neoformans invades the brain are largely unknown. In this study, we found that C. neoformans-derived microvesicles (CnMVs) can enhance the traversal of the blood-brain barrier (BBB) by C. neoformans invitro. The immunofluorescence imaging demonstrates that CnMVs can fuse with human brain microvascular endothelial cells (HBMECs), the constituents of the BBB. This activity is presumably due to the ability of the CnMVs to activate HBMEC membrane rafts and induce cell fusogenic activity. CnMVs also enhanced C. neoformans infection of the brain, found in both infected brains and cerebrospinal fluid. In infected mouse brains, CnMVs are distributed inside and around C. neoformans-induced cystic lesions. GFAP (glial fibrillary acidic protein)-positive astrocytes were found surrounding the cystic lesions, overlapping with the 14-3-3-GFP (14-3-3-green fluorescence protein fusion) signals. Substantial changes could be observed in areas that have a high density of CnMV staining. This is the first demonstration that C. neoformans-derived microvesicles can facilitate cryptococcal traversal across the BBB and accumulate at lesion sites of C. neoformans-infected brains. Results of this study suggested that CnMVs play an important role in the pathogenesis of cryptococcal meningoencephalitis.

Aspergillus tanneri sp. nov., a new pathogen that causes invasive disease refractory to antifungal therapy.

The most common cause of invasive aspergillosis (IA) in patients with chronic granulomatous disease (CGD) is Aspergillus fumigatus followed by A. nidulans; other aspergilli rarely cause the disease. Here we review two clinical cases of fatal IA in CGD patients and describe a new etiologic agent of IA refractory to antifungal therapy. Unlike typical IA caused by A. fumigatus, the disease caused by the new species was chronic and spread from the lung to multiple adjacent organs. Mycological characteristics and the phylogenetic relationship with other aspergilli based on the sequence analysis of Mcm7, RPB2, and Tsr1 indicated that the new species, which we named as A. tanneri, belongs to Aspergillus section Circumdati. The species has a higher amphotericin B, voriconazole, and itraconazole MIC and causes more chronic infection in CGD mice than A. fumigatus. This is the first report documenting IA in CGD patients caused by a species belonging to the Aspergillus section Circumdati that is inherently resistant to azoles and amphotericin B. Unlike the results seen with many members of Aspergillus section Circumdati, ochratoxin was not detected in filtrates of cultures grown in various media. Our phenotypic and genetic characterization of the new species and the case reports will assist future diagnosis of infection caused by A. tanneri and lead to more appropriate patient management.

Hyaluronic acid receptor CD44 deficiency is associated with decreased Cryptococcus neoformans brain infection.

Cryptococcus neoformans is a pathogenic yeast that can invade the brain and cause meningoencephalitis. Our previous in vitro studies suggested that the interaction between C. neoformans hyaluronic acid and human brain endothelial CD44 could be the initial step of brain invasion. In this report, we used a CD44 knock-out (KO or CD44(-/-)) mouse model to explore the importance of CD44 in C. neoformans brain invasion. Our results showed that C. neoformans-infected CD44 KO mice survived longer than the infected wild-type mice. Consistent with our in vitro results, the brain and cerebrospinal fluid fungal burden was reduced in CD44-deficient mice. Histopathological studies showed smaller and fewer cystic lesions in the brains of CD44 KO mice. Interestingly, the cystic lesions contained C. neoformans cells embedded within their polysaccharide capsule and were surrounded by host glial cells. We also found that a secondary hyaluronic acid receptor, RHAMM (receptor of hyaluronan-mediated motility), was present in the CD44 KO mice. Importantly, our studies demonstrated an in vivo blocking effect of simvastatin. These results suggest that the CD44 and RHAMM receptors function on membrane lipid rafts during invasion and that simvastatin may have a potential therapeutic role in C. neoformans infections of the brain.

Taxonomy of fungi causing mucormycosis and entomophthoramycosis (zygomycosis) and nomenclature of the disease: molecular mycologic perspectives.

Molecular phylogenetic analysis confirmed the phylum Zygomycota to be polyphyletic, and the taxa conventionally classified in Zygomycota are now distributed among the new phylum Glomeromycota and 4 subphyla incertae sedis (uncertain placement). Because the nomenclature of the disease zygomycosis was based on the phylum Zygomycota (Zygomycetes) in which the etiologic agents had been classified, the new classification profoundly affects the name of the disease. Zygomycosis was originally described as a convenient and inclusive name for 2 clinicopathologically different diseases, mucormycosis caused by members of Mucorales and entomophthoramycosis caused by species in the order Entomophthorales of Zygomycota. Without revision of original definition, the name "zygomycosis," however, has more often been used as a synonym only for mucormycosis. This article reviews the progress and changes in taxonomy and nomenclature of Zygomycota and the disease zygomycosis. The article also reiterates the reasons why the classic names "mucormycosis" and "entomophthoramycosis" are more appropriate than "zygomycosis."

Hematogenously disseminated skin disease caused by Mucor velutinosus in a patient with acute myeloid leukemia.

We report here a case of disseminated skin infection caused by Mucor velutinosus, a recently described new species. We believe this to be the first published report of a clinical case of mucormycosis due to M. velutinosus, as well as a rare case of dissemination from a deep site to skin.

Human leukocytes kill Aspergillus nidulans by reactive oxygen species-independent mechanisms.

Invasive aspergillosis is a major threat for patients suffering from chronic granulomatous disease (CGD). Although Aspergillus fumigatus is the most commonly encountered Aspergillus species, the presence of A. nidulans appears to be disproportionately high in CGD patients. The purpose of this study was to investigate the involvement of the NADPH oxidase and the resulting reactive oxygen species (ROS) in host defense against fungi and to clarify their relationship toward A. nidulans. Murine CGD alveolar macrophages (AM) and polymorphonuclear leukocytes (PMN) and peripheral blood mononuclear cells (PBMC) from healthy controls and CGD patients were challenged with either A. fumigatus or A. nidulans. Analysis of the antifungal effects of ROS revealed that A. nidulans, in contrast to A. fumigatus, is not susceptible to ROS. In addition, infection with live A. nidulans did not result in any measurable ROS release. Remarkably, human CGD PMN and PBMC and murine CGD AM were at least equipotent at arresting conidial germination compared to healthy controls. Blocking of the NADPH oxidase resulted in significantly reduced damage of A. fumigatus but did not affect A. nidulans hyphae. Furthermore, the microbicidal activity of CGD PMN was maintained toward A. nidulans but not A. fumigatus. In summary, antifungal resistance to A. nidulans is not directly ROS related. The etiology of A. nidulans infections in CGD cannot be explained by the simple absence of the direct microbicidal effect of ROS. In vivo, the NADPH oxidase is a critical regulator of innate immunity whose unraveling will improve our understanding of fungal pathogenesis in CGD.

Prevalence of the VNIc genotype of Cryptococcus neoformans in non-HIV-associated cryptococcosis in the Republic of Korea.

PCR fingerprinting and multilocus sequence typing were applied to determine the major molecular types of the Cryptococcus neoformans/Cryptococcus gattii species complex in the Republic of Korea. Of the 78 strains isolated from patients diagnosed with cryptococcosis between 1990 and 2008, 96% were C. neoformans serotype A, mating type MATalpha and molecular type VNI. The remaining 4% were C. gattii, serotype B, mating type MATalpha and either molecular type VGIIb or VGIII. Of the 62 strains with known HIV status, only 14 (22.6%) were isolated from HIV-positive patients and belonged to molecular type VNI. Remarkably, 93% of the C. neoformans isolates had identical PCR fingerprint profiles with the VNIc genotype that has been identified recently as the major genotype among C. neoformans strains in China. Most strains (81.8%) of the VNIc genotype were associated with non-HIV patients compared with strains of the non-VNIc genotype (20%) (P=0.009). Unlike the Chinese strains, a majority (60%) of the non-HIV patients infected with strains of the VNIc genotype in the Republic of Korea had serious underlying conditions, with cancer and liver disease being the most common. This study affirms VNIc to be the most prevalent genotype of C. neoformans isolated from non-HIV patients with cryptococcosis.

Sexual reproduction in Aspergillus species of medical or economical importance: why so fastidious?

Heterothallism is dependent upon the obligatory cross-mating between self-sterile homokaryotic individuals and represents a common pattern of sexuality in yeasts and molds. Heterothallic reproductive cycles have recently been discovered in three Aspergillus species of medical and economic importance, namely Aspergillus fumigatus,A. parasiticus and A. flavus. Together with Aspergillus udagawae (Neosartorya udagawae), heterothallism has now been discovered in a total of four aspergilli that affect human health or economy. These fungi appear to express relatively low levels of fertility compared to other heterothallic or homothallic aspergilli and require unusually fastidious environmental parameters to complete the sexual cycle. Because the purpose of sex is to reproduce, we favor the hypothesis that while fertility of these species is on the decline this is compensated by their proficiency to reproduce asexually in a wider range of environmental conditions. Heterothallism in these species could provide an invaluable tool for the recombinational analysis of factors relevant to pathogenicity or toxin production. There is concern, however, whether extensive recombinational analysis can be very practical in light of the fact that formation of ascospores in these species requires a long period of time and the construction of genetically marked strains is likely to decrease fertility even further.