Cerebral Phaeohyphomycosis Caused by Exophiala dermatitidis in a Chinese CARD9-Deficient Patient: A Case Report and Literature Review

Inherited CARD9 Deficiency Due to a Founder Effect in East Asia

Autosomal recessive CARD9 deficiency can underly deep and superficial fungal diseases. We identified two Japanese patients, suffering from superficial and invasive Candida albicans diseases, carrying biallelic variants of CARD9. Both patients, in addition to another Japanese and two Korean patients who were previously reported, carried the c.820dup CARD9 variant, either in the homozygous (two patients) or heterozygous (three patients) state. The other CARD9 alleles were c.104G > A, c.1534C > T and c.1558del. The c.820dup CARD9 variant has thus been reported, in the homozygous or heterozygous state, in patients originating from China, Japan, or South Korea. The Japanese, Korean, and Chinese patients share a 10 Kb haplotype encompassing the c.820dup CARD9 variant. This variant thus originates from a common ancestor, estimated to have lived less than 4,000 years ago. While phaeohyphomycosis caused by Phialophora spp. was common in the Chinese patients, none of the five patients in our study displayed Phialophora spp.-induced disease. This difference between Chinese and our patients probably results from environmental factors. (161/250).

Concurrent infection of Exophiala dermatitidis and Angiostrongylus cantonensis in central nervous system of a child with inherited CARD9 deficiency: A case report and literature review

Exophiala dermatitidis is a relatively common environmental black yeast with a worldwide distribution that rarely causes fungal infection. Here, we report a case of a 6-year-old girl with central nervous system (CNS) encephalitis caused by E. dermatitidis and Angiostrongylus cantonensis. E. dermatitidis was identified by both cerebrospinal fluid culture and metagenomic next-generation sequencing (mNGS). Angiostrongylus cantonensis infection was confirmed by an enzyme linked immunosorbent assay (ELISA). Whole exome sequencing showed that this previously healthy girl carried a homozygous CARD9 mutation for c.820dupG (p.D274Gfs*61) that underlies invasive fungal and parasite infections. We chose glucocortieoid pulse therapy and anti-infective therapy based on the initial results of laboratory examination and cranial MRI images. With the aggravation of the disease and the evidence of the subsequent etiologic test, the combination of antifungal antiparasitic treatments (voriconazole, fluorocytosine and amphotericin B) were actively used. Unfortunately, the girl finally died due to severe systemic infection. mNGS performs a potential value for diagnosing rare CNS infections, and autosomal recessive CARD9 deficiency should be considered in patient with fatal invasive fungal infections.

From Mendel to mycoses: Immuno-genomic warfare at the human-fungus interface

Fungi are opportunists: They particularly require a defect of immunity to cause severe or disseminated disease. While often secondary to an apparent iatrogenic cause, fungal diseases do occur in the absence of one, albeit infrequently. These rare cases may be due to an underlying genetic immunodeficiency that can present variably in age of onset, severity, or other infections, and in the absence of a family history of disease. They may also be due to anti-cytokine autoantibodies. This review provides a background on how human genetics or autoantibodies underlie cases of susceptibility to severe or disseminated fungal disease. Subsequently, the lessons learned from these inborn errors of immunity marked by fungal disease (IEI-FD) provide a framework to begin to mechanistically decipher fungal syndromes, potentially paving the way for precision therapy of the mycoses.

First case of Rhinocladiella mackenziei brain abscess in Turkey: Case report and review of the literature

Rhinocladiella mackenziei is a highly neurotropic fungus, mainly reported from the Middle East. However, in recent years, there have been some cases from outside this region. We described an additional fatal case of R. mackenziei cerebral infection for the first time from Turkey and made a literature review of all previously reported cases. During 34 years (1988-2022), there have been 42 R. mackenziei brain abscess cases. Most patients have been reported from Saudi Arabia (n = 14, 33.3%). It is noteworthy that 40.5% of patients, including our case, were immunocompetent at initial diagnosis and mostly presented with a single lesion (n = 10, 23.8%). The most frequent comorbidities were solid organ transplant (n = 9, 21.4%), diabetes mellitus (n = 6, 14.3%), malignancy (n = 6, 14.3%) and prior surgery (n = 3, 7.1%). The most commonly used initial antifungal regimen were amphotericin B together with itraconazole (n = 9, 21.4%), combinations of lipid preparations of amphotericin B, voriconazole and/or posaconazole (n = 9, 21.4%) and amphotericin B alone (n = 8, 19%). Although both surgical procedures and antifungal medication in the majority of patients were performed, mortality rates remained high (90.4%). The area at risk of R. mackenziei cerebral abscess cases extends to other countries. Clinicians should be aware of this emerging disease and take a detailed travel history in patients with atypical and undocumented brain abscesses. Our case confirms the hypothesis that this fungus might spread more widely than previously predicted regions.

In Vitro and In Vivo Evaluation of Synergistic Effects of Everolimus in Combination with Antifungal Agents on Exophiala dermatitidis

To investigate the combined function of the novel oral mTOR inhibitor, everolimus, with antifungal agents and their potential mechanisms against Exophiala dermatitidis, the CLSI microliquid-based dilution method M38-A2, chequerboard technique, and disk diffusion testing were performed. The efficacy of everolimus was evaluated in combination with itraconazole, voriconazole, posaconazole, and amphotericin B against 16 clinically isolated strains of E. dermatitidis. The synergistic effect was determined by measuring the MIC and fractional inhibitory concentration index. Dihydrorhodamine 123 was used for the quantification of ROS levels. The differences in the expression of antifungal susceptibility-associated genes were analyzed following different types of treatment. Galleria mellonella was used as the in vivo model. While everolimus alone showed minimal antifungal effects, combinations with itraconazole, voriconazole, posaconazole, or amphotericin B resulted in synergy in 13/16 (81.25%), 2/16 (12.5%), 14/16 (87.75%), and 5/16 (31.25%) of isolates, respectively. The disk diffusion assay revealed that the combination of everolimus and antifungal drugs showed no significant increase in the inhibition zones compared with the single agent, but no antagonistic effects were observed. Combination of everolimus and antifungal agents resulted in increased ROS activity (everolimus + posaconazole versus posaconazole [P < 0.05], everolimus + amphotericin B versus amphotericin B [P < 0.002]). Simultaneously, compared to mono-treatment, the combination of everolimus + itraconazole suppressed the expression of MDR2 (P < 0.05) and the combination of everolimus + amphotericin B suppressed the expression of MDR3 (P < 0.05) and CDR1B (P < 0.02). In vivo, combinations of everolimus and antifungal agents improved survival rates, particularly the combination of everolimus + amphotericin B (P < 0.05). In summary, the in vivo and in vitro experiments performed in our study suggest that the combination of everolimus with azoles or amphotericin B can have synergistic effects against E. dermatitidis, potentially due to the induction of ROS activity and inhibition of efflux pumps, providing a promising new approach for the treatment of E. dermatitidis infections. IMPORTANCE Cancer patients with E. dermatitidis infection have high mortality if untreated. Clinically, the conventional treatment of E. dermatitidis is poor due to the long-term use of antifungal drugs. In this study, we have for the first time investigated the interaction and action mechanism of everolimus combined with itraconazole, voriconazole, posaconazole, and amphotericin B on E. dermatitidis in vitro and in vivo, which provided new ideas and direction for further exploring the mechanism of drug combination and clinical treatment of E. dermatitidis.

Challenges towards management of CARD9-deficient patients with phaeohyphomycosis: A case report and case series study

BACKGROUND

A number of recalcitrant phaeohyphomycosis cases with a life-threatening prognosis have been observed in CARD9-deficient patients, but little is known about the long-term management strategies that are effective for such intractable individuals.

OBJECTIVES

To study the genetic and immunological mechanisms underlying recalcitrant phaeohyphomycosis and to share our clinical experiences regarding its treatment.

PATIENTS/METHODS

Ten CARD9-deficient patients with recalcitrant phaeohyphomycosis admitted to our centre in the past two decades were followed-up, and their clinical presentations, laboratory findings, treatment and prognoses were analysed; one of them was a novel case of recalcitrant phaeohyphomycosis harbouring CARD9 mutations. Innate and adaptive immunological responses of patient-derived peripheral blood mononuclear cells were evaluated using ELISA and flow cytometry.

RESULTS

We identified a total of seven CARD9 mutations in the ten analysed patients. Moreover, patient-derived cells exhibited a significant impairment of innate and adaptive immune responses upon fungus-specific stimulation. All the patients experienced recurrence and exacerbation; four of them died, two exhibited continued disease progress with unsatisfactory therapeutic efficacy, three showed obvious improvement under maintenance therapy, and only one achieved a clinical cure.

CONCLUSIONS

Our study highlighted that otherwise healthy patients diagnosed with early-onset, unexplained and recalcitrant phaeohyphomycosis should be analysed for CARD9 mutations and immune deficiency. Thereafter, the length and choice of management remain challengeable and must be adjusted based on the clinical presentations and responses of patients over their lifetimes. Although continued posaconazole treatment may be the promising first-line therapy at present, novel strategies are worth exploring.

Of Mycelium and Men: Inherent Human Susceptibility to Fungal Diseases

In medical mycology, the main context of disease is iatrogenic-based disease. However, historically, and occasionally, even today, fungal diseases affect humans with no obvious risk factors, sometimes in a spectacular fashion. The field of “inborn errors of immunity” (IEI) has deduced at least some of these previously enigmatic cases; accordingly, the discovery of single-gene disorders with penetrant clinical effects and their immunologic dissection have provided a framework with which to understand some of the key pathways mediating human susceptibility to mycoses. By extension, they have also enabled the identification of naturally occurring auto-antibodies to cytokines that phenocopy such susceptibility. This review provides a comprehensive update of IEI and autoantibodies that inherently predispose humans to various fungal diseases.

Mouse Models of Phaeohyphomycosis

Infections by dematiaceous fungi especially phaeohyphomycosis are an emerging group of infectious diseases worldwide with a variety of clinical presentations. The mouse model is a useful tool for studying phaeohyphomycosis, which can mimic dematiaceous fungal infections in humans. Our laboratory has successfully constructed a mouse model of subcutaneous phaeohyphomycosis and found significant phenotypic differences between Card9 knockout and wild-type mice, mirroring the increased susceptibility to this infection observed in CARD9-deficient humans. Here we describe construction of the mouse model of subcutaneous phaeohyphomycosis and related experiments. We hope that this chapter can be beneficial for the study of phaeohyphomycosis and facilitate the development of new diagnostic and therapeutic approaches.

Exophiala dermatitidis Central Line-Associated Bloodstream Infection in a Child with Ewing's Sarcoma: Case Report and Literature Review on Paediatric Infections

Exophiala dermatitidis is a dematiaceous, ubiquitous, dimorphic fungus, which can cause a wide range of invasive diseases in both immunocompromised and immunocompetent hosts. Bloodstream infections due to E. dermatitidis are rarely encountered in clinical practice, especially in pediatric patients. We describe a case of central line-associated bloodstream infection due to E. dermatitidis in a 4.5-year-old boy with Ewing's sarcoma. The fungus was isolated from blood specimens taken from the Hickman line. The isolate was identified by its phenotypic characteristics, by MALDI-TOF and by using molecular methods. The infection was successfully treated with voriconazole and catheter removal. The literature was also reviewed on pediatric infections caused by E. dermatitidis, focusing on clinical manifestations and challenges associated with diagnosis and management.

Phaeohyphomycosis in China

Background

Due to more attentions paid to melanized fungi over the past few decades and under the background of the global coronavirus disease 2019 pandemic (COVID-19) the fact that the virus itself and the immunosuppressive agents such as glucocorticoids can further increase the risk of infections of deep mycoses, the number of patients with phaeohyphomycosis (PHM) has a substantial increase. Their spectrum is broad and the early diagnosis and treatments are extremely sticky. This study aims to more comprehensively understand the clinical features of phaeohyphomycosis in China over 35 years and to establish a more applicable systematical classification and severity grades of lesions to guide treatments and prognosis.

Methods

We reviewed 174 cases of proven phaeohyphomycosis reported in Chinese and English language literature from 1987 to 2021 and we also made the accurate classification definitions and detailed information about the epidemiology, species of clinical dematiaceous fungi, minimum inhibitory concentration values, clinical features, treatments, and prognosis.

Results

The mortality of cerebral, disseminated and pulmonary phaeohyphomycosis are 55%, 36%, and 25%. Nearly 19% of patients had poor quality of life caused by the complications such as disability, disfigurements, and blindness. The overall misdiagnosis rate of phaeohyphomycosis was 74%. Moderate to severe rashes are accounting for 82% of subcutaneous phaeohyphomycosis. The areas of the head and face are mostly affected accounting for 16% of severe rashes. Nearly 30% of invasive infections of phaeohyphomycosis are triggered by recurrent lesions. Voriconazole, itraconazole, amphotericin B deoxycholate (AmB-DOC), and terbinafine were most commonly used but diagnosis and treatments of phaeohyphomycosis remain challenging in reality.

Conclusions

Our classifications are likely to be more practical and easier to popularize, and there are still also plenty of characteristics in these non-specific lesions. There’re no significant variations in cure rates, or death rates between three grades of lesions. But patients with severe rashes have longer courses and lower effective rates.

Invasive Rhinosinusitis Caused by Alternaria infectoria in a Patient with Autosomal Recessive CARD9 Deficiency and a Review of the Literature

Phaeohyphomycoses comprise a heterogeneous group of fungal infections caused by dematiaceous fungi and have primarily been reported in patients with underlying acquired immunodeficiencies, such as hematological malignancies or solid-organ transplants. Over the past decade, a growing number of patients with phaeohyphomycosis but otherwise healthy were reported with autosomal recessive (AR) CARD9 deficiency. We report a 28-year-old woman who presented with invasive rhinosinusitis caused by Alternaria infectoria. Following a candidate gene sequencing approach, we identified a biallelic loss-of-function mutation of CARD9, thereby further broadening the spectrum of invasive fungal diseases found in patients with inherited CARD9 deficiency. In addition, we reviewed 17 other cases of phaeohyphomycosis associated with AR CARD9 deficiency. Physicians should maintain a high degree of suspicion for inborn errors of immunity, namely CARD9 deficiency, when caring for previously healthy patients with phaeohyphomycosis, regardless of age at first presentation.

Case report and literature review: double jeopardy – Exophiala dermatitidis and Mycobacterium canariasense central line-associated bloodstream infection in a patient

Central line-associated bloodstream infection (CLABSI) is the most common nosocomial-acquired infection, affecting 38 000 patients in the USA annually. Approximately 8–10 % of inserted catheters lead to bloodstream infections, and ~25–30 % of infections are associated with mortality. Although proper line maintenance is essential to prevent infection, it is quite a challenge to avoid infection in patients with a long-term catheter. We present a case of a female in her 40s with a previous history of irritable bowel syndrome (IBS) who has had a central line for total parenteral nutrition for the past 2 years. The patient recently visited the emergency room with fever and generalized fatigue. Blood cultures sent to microbiology were positive for black mould, Exophiala dermatitidis. However, after a few days, microbiology reported an additional micro-organism, Mycobacterium canariasense, a pathogen rarely associated with bacteraemia. The patient was administered voriconazole and moxifloxacin for black mould and mycobacterium infection, respectively. We present an unusual case of rare opportunistic organisms causing bacteraemia and fungaemia in a patient with a long-term catheter. CLABSI remains a serious challenge for clinical facilities. Implementation and monitoring of effective strategies can prevent catheter-related bloodstream infections in patients with long-term catheters and can reduce the morbidity and mortality associated with CLABSI.

Exophiala dermatitidis

Exophiala is a genus comprising several species of opportunistic black yeasts, which belongs to Ascomycotina. It is a rare cause of fungal infections. However, infections are often chronic and recalcitrant, and while the number of cases is steadily increasing in both immunocompromised and immunocompetent people, detailed knowledge remains scarce regarding infection mechanisms, virulence factors, specific predisposing factors, risk factors, and host response. The most common manifestations of Exophiala infection are skin infections, and the most frequent type of deep infection is pulmonary infection due to inhalation. The invasive disease ranges from cutaneous or subcutaneous infection to systemic dissemination to internal organs. The final identification of the causative organism should be achieved through a combination of several methods, including the newly introduced diagnostic analysis, matrix-assisted laser desorption/ ionization-time-of-flight mass spectrometry, together with sequencing of the ribosomal ribonucleic acid internal transcribed spacer region of the fungi, and histological and culture findings. Regarding treatment, because anti-infective agents and natural compounds exhibited poor antibiofilm activity, few treatments have ultimately been found to be effective for specific antifungal therapy, so the optimal antifungal therapy and duration of therapy for these infections remain unknown. Therefore, most forms of disease caused by Exophiala dermatitidis require aggressive combination therapies: Both surgical intervention and aggressive antifungal therapy with novel compounds and azoles are necessary for effective treatment.

A fatal case of Exophiala dermatitidis meningoencephalitis in an immunocompetent host: A case report and literature review

BACKGROUND

Central nervous system (CNS) infection due to Exophiala dermatitidis is rare and fatal, and primarily reported in immunocompromised patients or those with caspase recruitment domain-containing protein 9 deficiency. Herein, we describe a case of an otherwise healthy person (without underlying disease or gene deficiency) diagnosed with Exophiala dermatitidis meningoencephalitis. The patient achieved clinical remission under high-dose antifungal therapy in the first 14 months but died after 2 years of the therapy.

CASE PRESENTATION

A 15-year-old student with headache and fever was admitted to our department. Lumbar puncture showed increased cerebrospinal fluid (CSF) pressure, moderately high CSF protein levels and cell counts, and a remarkable decrease in CSF glucose and chloride. Magnetic resonance imaging of the brain revealed multiple lesions and cerebral pia mater enhancement. CSF culture confirmed E. dermatitidis infection. We administered 4-week antifungal therapy of amphotericin B, but his CSF culture remained positive. After receiving the 12-week standard dose of voriconazole (200 mg q12h), the patient's CSF culture became negative, but his condition deteriorated with intracranial lesion enlargement. We administered a high-dose voriconazole therapy (600-800 mg per day) for 12 months, which led to clinical remission. The voriconazole dose was reduced due to adverse effects including hepatic dysfunction and hypokalemia, and the disease progressed with high intracranial pressure and epileptic seizures.

CONCLUSIONS

CNS infection caused by E. dermatitidis is fatal and the most serious form of fungal infection. Initially, high-dose and long-term antifungal therapy could be effective. Gene defect and related antifungal immunodeficiency may be the most important pathogenic and lethal factor.

Inherited CARD9 Deficiency in a Child with Invasive Disease Due to Exophiala dermatitidis and Two Older but Asymptomatic Siblings

PURPOSE

Autosomal recessive CARD9 deficiency predisposes patients to invasive fungal disease. Candida and Trichophyton species are major causes of fungal disease in these patients. Other CARD9-deficient patients display invasive diseases caused by other fungi, such as Exophiala spp. The clinical penetrance of CARD9 deficiency regarding fungal disease is surprisingly not complete until adulthood, though the age remains unclear. Moreover, the immunological features of genetically confirmed yet asymptomatic individuals with CARD9 deficiency have not been reported.

METHODS

Identification of CARD9 mutations by gene panel sequencing and characterization of the cellular phenotype by quantitative PCR, immunoblot, luciferase reporter, and cytometric bead array assays were performed.

RESULTS

Gene panel sequencing identified compound heterozygous CARD9 variants, c.1118G>C (p.R373P) and c.586A>G (p.K196E), in a 4-year-old patient with multiple cerebral lesions and systemic lymphadenopathy due to Exophiala dermatitidis. The p.R373P is a known disease-causing variant, whereas the p.K196E is a private variant. Although the patient's siblings, a 10-year-old brother and an 8-year-old sister, were also compound heterozygous, they have been asymptomatic to date. Normal CARD9 mRNA and protein expression were found in the patient's CD14⁺ monocytes. However, these cells exhibited markedly impaired pro-inflammatory cytokine production in response to fungal stimulation. Monocytes from both asymptomatic siblings displayed the same cellular phenotype.

CONCLUSIONS

CARD9 deficiency should be considered in previously healthy patients with invasive Exophiala dermatitidis disease. Asymptomatic relatives of all ages should be tested for CARD9 deficiency. Detecting cellular defects in asymptomatic individuals is useful for diagnosing CARD9 deficiency.

Comparative genomics of opportunistic Phialophora species involved in divergent disease types

BACKGROUND

Black opportunists Phialophora verrucosa complex species can cause different disease types in competent and in immunocompromised individuals, but are remarkably overrepresented in CARD9-related infections.

OBJECTIVES

To better understand the ecology and potential pathogenicity of opportunistic Phialophora species and reveal eventual genetic parameters associated with the behaviour in vivo and genetic profiles in patients with CARD9 immunodeficiency.

METHODS

Genomes of 26 strains belonging to six species of the Phialophora verrucosa complex were sequenced. Using multilocus analysis, all environmental and clinical strains were identified correctly. We compared the genomes of agents from different disease types among each other including CARD9 immunodeficiency.

RESULTS

We obtained genome sizes of the 26 Phialophora strains ranged between 32 and 37 MB. Some species showed considerable intraspecific genomic variation. P americana showed the highest degree of variability. P verrucosa was variable in CAZy enzymes, whereas P americana varied in PKS-related genes. Phialophora species, particularly P verrucosa, are relatively frequent in patients with CARD9-related immunodeficiency. Different mutations in the CARD9 gene seem to increase susceptibility for infection by different groups of species, that is either Candida, dermatophytes or black fungi. A number of patients with chromoblastomycosis revealed an as yet unknown CARD9 mutation. TNFα impairment was prevalent in patients with CARD9 infections, while CBM patients were invariably IFNγ.

CONCLUSIONS

From genomic investigations, the known virulence factors between clinical and environmental strains did not reveal any significant difference. Phialophora complex has an equal chance to cause infection in humans, either healthy or CARD9-impaired.

The role and mechanism of CARD9 gene polymorphism in diseases

CARD9 is a cytosolic adaptor in myeloid cells, has a critical role in inflammatory disorders, and provides a protective function against microbial pathogen, especially fungal infection. Recently, CARD9 polymorphisms are of interest, showing a positive correlation with the elevated risk of fungal infection, inflammatory bowel disease, and other autoimmune diseases. Mechanistically, CARD9 polymorphisms impair the activation of RelB, a subunit of non-canonical NF-κB, which lead to the reduced cytokine and chemokine production by innate immune cells. In addition, CARD9 polymorphisms show a defective neutrophil accumulation in infectious sites. Furthermore, CARD9 polymorphisms could alter the composition of the gut microbiome. In this review, we summarize the latest findings of CARD9 polymorphisms with respect to inflammatory diseases.

Primary Cutaneous Aspergillosis in a Patient with CARD9 Deficiency and Aspergillus Susceptibility of Card9 Knockout Mice

PURPOSE

We describe a case of primary cutaneous aspergillosis caused by Aspergillus fumigatus, and elucidate the underlying genetic and immunological mechanisms.

MATERIALS AND METHODS

Routine clinical and laboratory investigations were performed. Whole-exome sequencing of the patient's DNA suggested the presence of a CARD9 mutation, which was confirmed by Sanger sequencing. Innate and adaptive immunological responses of patient-derived CARD9-deficient cells were evaluated with ELISA and flow cytometry. Cutaneous and pulmonary aspergillosis models were established in Card9 knockout (KO) mice, which were compared with wild-type and immunosuppressed mice, to explore the pathogenesis and Aspergillus susceptibility.

RESULTS

A 45-year-old man presented with a 37-year history of skin lesions on his face. A diagnosis of primary cutaneous aspergillosis was made through histopathology, immunohistochemistry, and tissue culture. Sanger sequencing of CARD9 showed a homozygous frame-shift mutation (c.819_820insG, p.D274fsX60), which led to the lack of CARD9 expression. Peripheral blood mononuclear cells from the patient showed selective impairment of proinflammatory cytokines, and Th1-, Th17-, and Th22-associated responses upon fungus-specific stimulation. The cutaneous aspergillosis model established in Card9 KO mice presented with persistent infection, with fungal germs and short hyphae in tissue, consistent with the patient's lesions. Skin lesions in immunosuppressed mice were more severe, and led to death. Unlike our patient, Card9 KO mice were relatively susceptible to pulmonary aspergillosis, with reasons to be investigated.

CONCLUSIONS

This is, to our knowledge, the first report that links cutaneous aspergillosis to CARD9 mutation. This work enriches both the phenotypic spectrum of CARD9 deficiencies and the genetic background of cutaneous aspergillosis.

In vitro and in vivo Study of Antifungal Effect of Pyrvinium Pamoate Alone and in Combination With Azoles Against Exophiala dermatitidis

Infections of Exophiala dermatitidis are often chronic and recalcitrant. Combination therapies with novel compounds and azoles could be an effective solution. Previously, we have demonstrated that pyrvinium pamoate exerted antifungal activity alone and favorable synergy with azoles against planktonic E. dermatitidis. Herein, the underlying antifungal mode of action were investigated. Pyrvinium alone showed sessile MIC50 (SMIC50) of 8->16 μg/ml against E. dermatitidis biofilms. However, synergism of PP with itraconazole, voriconazole, and posaconazole were observed against 16 (88.9%), 9 (50%), and 13 (72.2%) strains of E. dermatitidis biofilms. In accordance with in vitro susceptibilities, pyrvinium alone at concentration of 2 μg/ml resulted in significant growth restriction of planktonic E. dermatitidis. Pyrvinium alone resulted in reduction of biofilm formation. Higher concentration of pyrvinium was associate with more progressive reduction of biofilm mass. The in vivo activity of pyrvinium alone and combined with azoles was evaluated using Galleria mellonella model. Pyrvinium alone significantly improved the survival rate of larvae (P < 0.0001). The combination of pyrvinium and voriconazole or posaconazole acted synergistically in vivo (P < 0.05). Fungal burden determination revealed significant reduction of numbers of colony forming unit (CFU) in larvae treated with pyrvinium-itraconazole and pyrvinium-posaconazole compared to itraconazole or posaconazole alone group, respectively. The effect of pyrvinium on apoptosis, expression of TOR and HSP90, and drug efflux reversal were evaluated by PI/Annexin V staining, Real-Time Quantitative PCR and Rhodamine 6G assay, respectively. Pyrvinium alone or combined with azoles significantly (P < 0.05) increased late apoptosis or necrosis of E. dermatitidis cells. Pyrvinium combined with posaconazole significantly decreased the expression of TOR and Hsp90 compared to posaconazole alone group (P < 0.05). Pyrvinium resulted in significant (P < 0.05) decrease of the efflux of Rhodamine 6G. These findings suggested pyrvinium could be a promising synergist with azoles. The underlying mechanisms could be explained by inducing apoptosis/necrosis, inhibition of drug efflux pumps, and signaling pathways related with stress response and growth control.

USP15 Deubiquitinates CARD9 to Downregulate C-Type Lectin Receptor-Mediated Signaling

Posttranslational modifications are efficient means to rapidly regulate protein function in response to a stimulus. Although ubiquitination events and the E3 ubiquitin ligases involved are increasingly characterized in many signaling pathways, their regulation by deubiquitinating enzymes remains less understood. The C-type lectin receptor (CLR) signaling adaptor CARD9 was previously reported to be activated via TRIM62-mediated ubiquitination. In this study, we identify the deubiquitinase USP15 as a novel regulator of CARD9, demonstrating that USP15 constitutively associates with CARD9 and removes TRIM62-deposited ubiquitin marks. Furthermore, USP15 knockdown and knockout specifically enhance CARD9-dependent CLR signaling in both mouse and human immune cells. Altogether, our study identifies a novel regulator of innate immune signaling and provides a blueprint for the identification of additional deubiquitinases that are likely to control these processes.

CARD9 Deficiency in a Chinese Man with Cutaneous Mucormycosis, Recurrent Deep Dermatophytosis and a Review of the Literature

Deficiency of caspase recruitment domain-containing protein 9 (CARD9) is an autosomal recessive primary immunodeficiency disorder, which typically predisposes immunocompetent individuals to single fungal infections and multiple fungal infections are very rare. We study an otherwise healthy 48-year-old man, who had been admitted to our hospital diagnosed with deep dermatophytosis caused by Trichophyton rubrum for three times at 29, 33 and 48 years old, respectively. At the age of 39 years, he suffered from cutaneous mucormycosis due to Mucor irregularis. Moreover, he had a long history of superficial fungal diseases and occasional oral candidiasis. Whole-exome sequencing revealed two compound heterozygous splicing variants in CARD9 gene, c. 184 + 5 G > T and c. 951G > A, confirmed by Sanger sequencing. Patients with recurrent fungal infections especially invasive fungal infections in the absence of known immunodeficiencies should be tested for CARD9 mutations.

Genomics and Virulence of Fonsecaea pugnacius, Agent of Disseminated Chromoblastomycosis

Among agents of chromoblastomycosis, Fonsecaea pugnacius presents a unique type of infection because of its secondary neurotropic dissemination from a chronic cutaneous case in an immunocompetent patient. Neurotropism occurs with remarkable frequency in the fungal family Herpotrichiellaceae, possibly associated with the ability of some species to metabolize aromatic hydrocarbons. In an attempt to understand this new disease pattern, were conducted genomic analysis of Fonsecaea pugnacius (CBS 139214) performed with de novo assembly, gene prediction, annotation and mitochondrial genome assembly, supplemented with animal infection models performed with Tenebrio molitor in Mus musculus lineages BALB/c and C57BL/6. The genome draft of 34.8 Mb was assembled with a total of 12,217 protein-coding genes. Several proteins, enzymes and metabolic pathways related to extremotolerance and virulence were recognized. The enzyme profiles of black fungi involved in chromoblastomycosis and brain infection were analyzed with the Carbohydrate-Active Enzymes (CAZY) and peptidases database (MEROPS). The capacity of the fungus to survive inside Tenebrio molitor animal model was confirmed by histopathological analysis and by presence of melanin and hyphae in host tissue. Although F. pugnacius was isolated from brain in a murine model following intraperitoneal infection, cytokine levels were not statistically significant, indicating a profile of an opportunistic agent. A dual ecological ability can be concluded from presence of metabolic pathways for nutrient scavenging and extremotolerance, combined with a capacity to infect human hosts.

The Neurotropic Black Yeast Exophiala dermatitidis Induces Neurocytotoxicity in Neuroblastoma Cells and Progressive Cell Death

The neurotropic and extremophilic black yeast Exophiala dermatitidis (Herpotrichellaceae) inhabits diverse indoor environments, in particular bathrooms, steam baths, and dishwashers. Here, we show that the selected strain, EXF-10123, is polymorphic, can grow at 37 °C, is able to assimilate aromatic hydrocarbons (toluene, mineral oil, n-hexadecane), and shows abundant growth with selected neurotransmitters (acetylcholine, gamma-aminobutyric acid, glycine, glutamate, and dopamine) as sole carbon sources. We have for the first time demonstrated the effect of E. dermatitidis on neuroblastoma cell model SH-SY5Y. Aqueous and organic extracts of E. dermatitidis biomass reduced SH-SY5Y viability by 51% and 37%, respectively. Melanized extracellular vesicles (EVs) prepared from this strain reduced viability of the SH-SY5Y to 21%, while non-melanized EVs were considerably less neurotoxic (79% viability). We also demonstrated direct interactions of E. dermatitidis with SH-SY5Y by scanning electron and confocal fluorescence microscopy. The observed invasion and penetration of neuroblastoma cells by E. dermatitidis hyphae presumably causes the degradation of most neuroblastoma cells in only three days. This may represent a so far unknown indirect or direct cause for the development of some neurodegenerative diseases such as Alzheimer’s.