Successful Treatment of Sternal Osteomyelitis and Mediastinitis Caused by Rhizopus Following Cardiac Surgery.

Sternal osteomyelitis and mediastinitis are rare yet severe complications post-cardiac surgery, often associated with significant morbidity and mortality. Fungal etiologies, particularly those caused by Rhizopus spp., are infrequent but can lead to aggressive infections. Here, we present the case of a 68-year-old male who developed sternal osteomyelitis and mediastinitis caused by Rhizopus spp. two weeks following coronary artery bypass grafting surgery. Debridement and pectoralis flap reconstruction were performed following clinical identification and confirmation with microbiological examinations and a CT scan. Prompt recognition, aggressive surgical intervention, and targeted antifungal therapy were crucial for successful management. This case underscores the importance of considering fungal pathogens, such as Rhizopus, in the differential diagnosis of post-cardiac surgery infections, as well as aggressive treatment to improve outcomes for affected patients.

Majocchi Granuloma Superinfected With Herpes Zoster.

Herpes zoster (HZ) infection is caused by the reactivation of the varicella-zoster virus (VZV) and has very rarely been reported at the site of a superficial fungal infection. Also, HZ occurring at the site of a deep fungal infection has not been reported in the literature. We discuss a unique case of a 45-year-old male patient presenting with a Majocchi granuloma (MG) superinfected with disseminated HZ.

Specific depletion of myeloid-derived suppressor cells by the chemotherapeutic agent 5-Fluorouracil enhances protective immune response in Paracoccidioidomycosis.

BACKGROUND: Paracoccidioidomycosis (PCM), a systemic mycosis in Latin America, is regulated by suppressive mechanisms mediated by tolerogenic plasmacytoid-dendritic-cells and regulatory T-cells. Our recent studies revealed that myeloid-derived suppressor cells (MDSCs), are important mediators in PCM. Their suppressive activity on Th1/Th17 immunity was shown to be mediated by inhibitory effect of IL-10, IDO-1 and PD-L1. Studies revealed the chemotherapeutic drug 5-Fluorouracil (5-FU) as a selective MDSC apoptosis-inducing agent, but its in vivo effect on infectious processes remains poorly investigated. METHODS: MDSCs and other leukocytes were evaluated in the lungs of 5-FU-treated mice after four, six, and eight weeks of P. brasiliensis infection. Disease severity and immunological response were evaluated in MDSCs-depleted. RESULTS: 5-FU treatment caused a significant reduction of pulmonary MDSCs and fungal loads. The specific depletion of MDSCs by 5-FU reduced all pulmonary CD4+ T-cell populations (Th1, Th2, Th17, and Treg) resulting in improved tissue pathology and increased survival rates. Importantly, this reduction was concomitant with increased frequencies of Th1/Th17 cells and the increased levels of Th1/Th2/Th17 cytokines in the lungs and liver of treated mice suggesting an early and efficient protective effect of these cells. Furthermore, the immuneprotection conferred by the specific depletion of MDSCs by 5FU treatment could be reversed by the adoptive transfer of MDSCs. CONCLUSIONS: 5-FU treatment depletes lung-MDSCs of P. brasiliensis-infected mice resulting in enhanced immunity. The protective effect of 5-FU treatment in pulmonary PCM suggests that the specific depletion of MDSCs can be viewed as a potential immunotherapeutic tool for PCM.

Fully Automated Cassette-Based Synthesis of 2-Deoxy-2-[18F]Fluorocellobiose Using Trasis AllInOne Module.

Due to the continuous rise in global incidence and severity of invasive fungal infections (IFIs), particularly among immunocompromised and immunodeficient patients, there is an urgent demand for swift and accurate fungal pathogen diagnosis. Therefore, the need for fungal-specific positron emission tomography (PET) imaging agents that can detect the infection in the early stages is increasing. Cellobiose, a disaccharide, is readily metabolized by fungal pathogens such as Aspergillus species. Recently, our group reported fluorine-18 labeled cellobiose, 2-deoxy-2-[18F]fluorocellobiose ([18F]FCB), for specific imaging of Aspergillus infection. The positive imaging findings with very low background signal on delayed imaging make this ligand a promising fungal-specific imaging ligand. Inspired by this result, the decision was made to automate the radiolabeling procedure for better reproducibility and to facilitate clinical translation. A Trasis AllInOne (Trasis AIO) automated module was used for this purpose. The reagent vials contain commercially available 2-deoxy-2-[18F]fluoroglucose ([18F]FDG), glucose-1-phosphate, and enzyme (cellobiose phosphorylase). A Sep-Pak cartridge was used to purify the tracer. The overall radiochemical yield was 50%-70% (n = 6, decay corrected) in 75-min synthesis time with a radiochemical purity of > 98%. This is a highly reliable protocol to produce current good manufacturing practice (cGMP)-compliant [18F]FCB for clinical PET imaging.

Gut-Derived Short-Chain Fatty Acids and Macrophage Modulation: Exploring Therapeutic Potentials in Pulmonary Fungal Infections.

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, modulate immune cell functions, particularly macrophages. This review explores the potential therapeutic applications of SCFAs in pulmonary fungal infections, a critical concern due to their high mortality rates and antifungal resistance. SCFAs enhance macrophage functions by promoting phagosome-lysosome fusion, increasing reactive oxygen species production, and balancing cytokine responses. Pulmonary fungal infections, caused by pathogens like Aspergillus fumigatus, are prevalent in immunocompromised patients, including those with diabetes, chronic obstructive pulmonary disease, and those on high-dose corticosteroids. SCFAs have shown promise in improving macrophage function in these contexts. However, the application of SCFAs must be balanced against potential side effects, including gut microbiota disruption and metabolic disorders. Further research is needed to optimize SCFA therapy for managing pulmonary fungal infections.

In the flow of molecular miniaturized fungal diagnosis.

The diagnosis of fungal infections presents several challenges and limitations, stemming from the similarities in symptomatology, diversity of underlying pathogenic species, complexity of fungal biology, and scarcity of rapid, affordable, and point-of-care approaches. In this review, we assess technological advances enabling the conversion of cutting-edge laboratory molecular diagnostic methods to cost-effective microfluidic devices. The most promising strategies toward the design of DNA sequence-based fungal diagnostic systems, capable of capturing and deciphering the highly informative DNA of the pathogen and adapted for resource-limited settings, are discussed, bridging fungal biology, molecular genetics, microfluidics, and biosensors.

Radiological differentiation between bacterial orbital cellulitis and invasive fungal sino-orbital infections.

PURPOSE: Invasive fungal orbital infections (IFOI) may be difficult to differentiate from sinogenic bacterial orbital cellulitis (OC). This study investigates the features differentiating OC from IFOI on magnetic resonance imaging (MRI). METHODS: Retrospective study of adult patients with sinogenic OC and IFOI with pre-intervention MRI. Patients without post-septal involvement, non-sinogenic OC (e.g.: secondary to trauma) and poor-quality scans were excluded. Independent Sample's t test and Fisher's exact test were conducted with p < 0.05 deemed statistically significant. RESULTS: Eleven cases each of OC (Mean age: 41.6 ± 18.4 years-old, Male: 10) and IFOI (Mean age: 65.0 ± 16.6 years-old, Male: 9) between 2006 and 2023. IFOI patients were older, more likely immunocompromised and had a lower mean white-cell count (p value = 0.005, 0.035 and 0.017, respectively). The ethmoid and maxillary sinuses were most commonly involved in both entities. Pre-septal and lacrimal gland involvement were more common in OC (p = 0.001 and 0.008, respectively). Infiltrative OC orbital lesions were poorly demarcated, whilst those in IFOI were expansile/mass-like invading the orbit from the adjacent paranasal sinuses. Specific IFOI features included loss-of-contrast-enhancement (LoCE) of paranasal sinus tissues with orbital extension. Extra-orbital and -sinonasal extension indicative of IFOI included contiguous skull base or pterygopalatine fossa involvement, retro-antral and masticator space stranding and vasculitis. CONCLUSION: This study describes the key MRI features of IFOI including differentiating markers from OC. These specific features, such as LoCE of the paranasal and orbital soft tissues, the location and pattern of contiguous soft-tissue involvement, provide expedient identification of IFOI which necessitate early surgical intervention for microbiological confirmation of an invasive fungal pathology.

Case series of dogs with blastomycosis managed with high-flow nasal oxygen therapy (2019-2023): 19 cases.

Objective: To describe the clinical presentation, progression, treatment, and outcome of dogs with blastomycosis treated with high-flow nasal oxygen therapy (HFNOT). Design: Retrospective case review. Setting: University veterinary teaching hospital. Animals: Nineteen client-owned dogs with strongly suspected or confirmed blastomycosis treated with HFNOT. Measurements and main results: The medical records of dogs with strongly suspected or confirmed blastomycosis between October 2019 and May 2023 that received HFNOT were evaluated. Nineteen dogs were included. Nine dogs were started directly on high-flow nasal oxygen therapy. The remaining 10 dogs first received traditional oxygen therapy and were then transitioned to HFNOT 3-142 h later. Of the 19 dogs, 1 survived to discharge from hospital, 12 were euthanized due to progression of disease, and 6 died during the hospitalization period. Conclusions and clinical importance: The prognosis for survival of dogs with severe blastomycosis requiring therapy beyond traditional oxygen methods was poor to grave in this population. This is the first known documented report of HFNOT use in dogs with confirmed or suspected blastomycosis.

Tinea Incognito: Challenges in Diagnosis and Management.

Tinea incognito is a dermatophyte infection with atypical features, due to the use of topical or systemic steroids or other immunosuppressive medications. Delayed diagnosis, spread of the infection to critical body surfaces, resistance to antifungal drugs, and increased costs due to prolonged hospitalization and multiple treatment regimens often complicate tinea incognito. It can affect individuals of all ages and genders, but it is more common in children. Atypical clinical appearance often necessitates differentiation from other diseases such as eczema, seborrheic dermatitis, lupus erythematosus, psoriasis, or other non-fungal skin conditions. The treatment of tinea incognito usually involves discontinuation of topical steroids or other immunosuppressive medications. Preventive measures and management of the underlying fungal infection are necessary and can be achieved with antifungal drugs. Patients should wear loose cotton clothes, use boiling water for laundry, and iron their clothing before wearing them. Additionally, they should avoid sharing bed linens, towels, clothes, and shoes. This review aims to raise awareness of tinea incognito among health practitioners, provide tips for detecting the disorder, include it in the differentials, and evaluate the available diagnostic procedures.

Biomarker Driven Antifungal Stewardship (BioDriveAFS) in acute leukaemia-a multi-centre randomised controlled trial to assess clinical and cost effectiveness: a study protocol for a randomised controlled trial.

BACKGROUND: Acute leukaemias (AL) are life-threatening blood cancers that can be potentially cured with treatment involving myelosuppressive, multiagent, intensive chemotherapy (IC). However, such treatment is associated with a risk of serious infection, in particular invasive fungal infection (IFI) associated with prolonged neutropenia. Current practice guidelines recommend primary antifungal (AF) prophylaxis to be administered to high-risk patients to reduce IFI incidence. AFs are also used empirically to manage prolonged neutropenic fever. Current strategies lead to substantial overuse of AFs. Galactomannan (GM) and ß-D-glucan (BG) biomarkers are also used to diagnose IFI. Combining both biomarkers may enhance the predictability of IFI compared to administering each test alone. Currently, no large-scale randomised controlled trial (RCT) has directly compared a biomarker-based diagnostic screening strategy without AF prophylaxis to AF prophylaxis (without systematic biomarker testing). METHODS: BioDriveAFS is a multicentre, parallel, two-arm RCT of 404 participants from UK NHS Haematology departments. Participants will be allocated on a 1:1 basis to receive either a biomarker-based antifungal stewardship (AFS) strategy, or a prophylactic AF strategy, which includes existing standard of care (SoC). The co-primary outcomes will be AF exposure in the 12-month post randomisation and the patient-reported EQ-5D-5L measured at 12-month post randomisation. Secondary outcomes will include total AF exposure, probable/proven IFI, survival (all-cause mortality and IFI mortality), IFI treatment outcome, AF-associated adverse effects/events/complications, resource use, episodes of neutropenic fever requiring hospital admission or outpatient management, AF resistance in fungi (non-invasive and invasive) and a Desirability of Outcome Ranking. The trial will have an internal pilot phase during the first 9 months. A mixed methods process evaluation will be integrated in parallel to the internal pilot phase and full trial, aiming to robustly assess how the intervention is delivered. Cost-effectiveness analysis will also be performed. DISCUSSION: The BioDriveAFS trial aims to further the knowledge of strategies that will safely optimise AF use through comparison of the clinical and cost-effectiveness of a biomarker-led diagnostic strategy versus prophylactic AF to prevent and manage IFI within acute leukaemia. The evidence generated from the study will help inform global clinical practice and approaches within antifungal stewardship. TRIAL REGISTRATION: ISRCTN11633399. Registered 24/06/2022.

Features and global impact of invasive fungal infections caused by Pneumocystis jirovecii: A systematic review to inform the World Health Organization fungal priority pathogens list.

This systematic review evaluates the current global impact of invasive infections caused by Pneumocystis jirovecii (principally pneumonia: PJP), and was carried out to inform the World Health Organization Fungal Priority Pathogens List. PubMed and Web of Science were used to find studies reporting mortality, inpatient care, complications/sequelae, antifungal susceptibility/resistance, preventability, annual incidence, global distribution, and emergence in the past 10 years, published from January 2011 to February 2021. Reported mortality is highly variable, depending on the patient population: In studies of persons with HIV, mortality was reported at 5%-30%, while in studies of persons without HIV, mortality ranged from 4% to 76%. Risk factors for disease principally include immunosuppression from HIV, but other types of immunosuppression are increasingly recognised, including solid organ and haematopoietic stem cell transplantation, autoimmune and inflammatory disease, and chemotherapy for cancer. Although prophylaxis is available and generally effective, burdensome side effects may lead to discontinuation. After a period of decline associated with improvement in access to HIV treatment, new risk groups of immunosuppressed patients with PJP are increasingly identified, including solid organ transplant patients.

Observational study on the clinical profile and treatment outcome on long-term follow-up of COVID-19 associated mucormycosis.

MATERIALS AND METHODS: Patients diagnosed with COVID-19 associated mucormycosis were followed up for 6 months to study the clinical profile, readmissions, long-term treatment outcome and the mortality rate. RESULTS: Among 37 patients with COVID-19 associated mucormycosis, the mortality rate was 33.3 %, 42.9% and 100 % among patients with mild, moderate and severe COVID-19 infection. One month after discharge, among the 20 patients who survived, 10 (50 %) patients had worsening symptoms and required readmission. Nine patients required readmission for amphotericin and 1 patient was admitted for surgical intervention. On follow-up at 1 month, 30 % (6/20) patients became asymptomatic. However, at 3 months, 45 % (9/20) of the patients were asymptomatic. At 6 months of follow-up, 80 % (16/20) were asymptomatic. At 6 months, one each had residual abnormalities like visual loss in one eye, visual field deficit, change in voice and residual weakness of the limbs along with cranial nerve paresis. CONCLUSION: The follow-up study revealed that a significant number of patients required readmission within the first month, but most of the patients became asymptomatic by 6 months. The readmission rate was higher in patients who received a shorter duration of amphotericin.

Implementation of effective strategies to prevent Candida auris transmission in a Quaternary Care Center, Riyadh, Saudi Arabia.

This study outlines the results of an investigation of a large C. auris outbreak at King Saud Medical City (KSMC), a quaternary hospital in Saudi Arabia. We identified 122 cases of C. auris (colonization, 74; infection, 48) from June 2021 to June 2022. The mean patient age was 48.4 years, and the median duration of stay before diagnosis was 32.7 days. A significant proportion of patients (87.70%) were diagnosed with C. auris more than 3 days after admission to KSMC. The source of exposure was either nosocomial (from KSMC, 28.68%; from other hospitals, 16.39%) or unknown (54.91%). The hospitalization mortality rate was 45.90%. This report highlights the challenges in investigating and managing C. auris outbreaks, emphasizing the need for a comprehensive approach incorporating strategies for screening and early identification, effective environmental cleaning, and the implementation of stringent infection control measures such as hand hygiene, isolation of patient, standard and contact precaution and decolonization.

Investigating the Influence of Temperature and Supplementation Timing on Antifungal Efficacy in Storage Medium for Corneal Transplantation.

INTRODUCTION: Although antifungal supplementation reduces the fungal load in the corneal storage medium, consensus is lacking on the influence of dosing and temperature. The study aims to evaluate the impact of eye bank warming protocol and timing of antifungal supplements on efficacy in Optisol-GS and tissue. METHODS: Corneoscleral rims contaminated with Candida albicans (C. albicans) were incubated in Optisol-GS, either without antifungal agents or with the addition of amphotericin B or voriconazole at various concentrations (2 ×, 5 ×, 10 ×, and 20 × MIC), at different time points, and under various preservation temperatures (2-8 °C versus 2 h-room temperature exposure). Antifungal efficacy was evaluated by counting viable yeast colonies cultured from Optisol-GS samples. Tissue sterility was determined through direct tissue culture and histological examination of the contaminated rims after a 14-day incubation period. RESULTS: Room temperature exposure did not increase colony growth at the same multiple MIC of antifungal agents. Although antifungal addition reduced C. albicans growth in a concentration-dependent manner, yeast growth was still observed in all Optisol-GS samples with a single supplementation after a 14-day incubation. Only groups with additional antifungal supplementation on either day 2 or day 6 showed a 99% or greater reduction of C. albicans growth in Optisol-GS samples and yielded negative results in direct tissue culture. CONCLUSIONS: The eye bank warming protocol did not compromise antifungal efficacy. To sustain the required concentration and effectively reduce C. albicans growth in Optisol-GS and contaminated tissue, additional antifungal supplementation on either day 2 or day 6 was necessary during a 2-week preservation period.

Unveiling the Uncommon: Gastrointestinal Basidiobolomycosis of the Colon and its Distinctive Splendore-Hoeppli Phenomenon.

BACKGROUND: Basidiobolomycosis is a rare fungal infection caused by Basidiobolus ranarum. CASE PRESENTATION: A 53-year-old man from Saudi Arabia with a known history of diverticulosis presented with severe abdominal pain and diarrhea. A CT scan revealed circumferential wall thickening of the descending and sigmoid colon with surrounding fat stranding, suggesting a diagnosis of complicated diverticulitis. Additional thick fluid was observed around the affected area. Surgical excision was pursued. A gross examination of two received large bowel segments disclosed marked ulcerated mucosa and wall thickening with exudate-covered serosal surfaces and adhesions. Microscopic examination unveiled significant infiltration by eosinophils, polymorphonuclear leukocytes, and granulomatous inflammation. Thin-walled, broad fungal hyphae of Basidiobolus, surrounded by eosinophilic material, were identified. Granulomas displayed abundant multinucleated giant cells and palisading histiocytes around central necrosis or abscess formation. Thin-walled, broad fungal hyphae of Basidiobolus, with sparse septations, are surrounded by a radiating, intensely eosinophilic cuff (Splendore-Hoeppli phenomenon). These hyphae, visible with hematoxylin and eosin staining, were further highlighted with periodic acid-Schiff and Gomori methenamine silver staining. DISCUSSION: Basidiobolomycosis may mimic neoplastic lesions. Histologically, the characteristic features include broad, thin-walled septate hyphae surrounded by eosinophilic material, a finding that is accentuated by the Splendore-Hoeppli phenomenon. Microscopic examination, along with special stains such as periodic acid-Schiff (PAS) and Gomori methenamine silver, is essential for accurate diagnosis. CONCLUSION: Prompt recognition and appropriate antifungal therapy are vital for favorable patient outcomes. This report highlights the distinctive features of Basidiobolomycosis to raise awareness and understanding of this infrequent yet clinically significant fungal infection.

Characterization of Humicola pulvericola First Isolated from a Patient with Keratitis Clinical Case.

Infection caused by the Humicola sp is extremely rare. We report the first case of fungal keratitis caused by Humicola pulvericola (H. pulvericola) in a 63-year-old man with a history of exposed to hot oil two weeks ago who developed keratitis. Direct examination of confocal microscopy and corneal scrapings showed fungal hyphae and isolates were identified by morphology and by sequencing the internal transcribed spacer region of ribosomal DNA. The in vitro antifungal susceptibilities of the case strain were tested for five antifungal agents. The results showed that the infectious agent was resistant towards fluconazole, caspofungin and amphotericin B; itraconazole and voriconazole were highly effective against H. pulvericola. He was diagnosed with H. pulvericola keratitis and treated with oral itraconazole and natamycin eyedrops. After one month of treatment, the lesion gradually improved, with the best-corrected visual acuity improving to 0.8.

Histoplasmosis Causing Overt Inflammation Presenting as Pericarditis: A Case Report.

Histoplasma capsulatum is a well-known cause of pulmonary infections, but in the right patient population or host environment, it can cause a vast array of symptoms. The fungus possesses a special set of virulence factors that allows it to evade host immunity and cause infection, particularly in immunosuppressed hosts. Pericarditis is a known presentation of histoplasmosis, but it can be difficult to diagnose and is often treated based on suspicion. We present a case of a healthy young male who mounted a robust inflammatory response to histoplasmosis resulting in pericarditis.

Efficacy and Safety of Amorolfine Lotion 0.25% w/v Compared to Amorolfine Cream 0.25% w/w in Patients With Superficial Fungal Infections of the Skin: A Multi-center, Randomized, Open-Label, Active-Controlled, Non-inferiority Phase III Clinical Trial.

BACKGROUND: Dermatophytosis, a major cause of superficial fungal infections, requires topical and systemic antifungals. Amorolfine, a morpholine derivative, is a new topical antifungal available in cream and lotion formulations. OBJECTIVE: To evaluate the efficacy and safety of amorolfine lotion 0.25% compared to amorolfine cream 0.25% in patients with dermatophytosis. METHODS: A multi-center randomized, two-arm, active-controlled, parallel, non-inferiority phase III clinical trial involving 284 dermatophytosis patients was conducted, with the test arm using amorolfine lotion and the reference arm using amorolfine cream. The study drugs were applied once daily in the evening for four weeks and patients were followed up for another two weeks. The primary endpoint was clinical cure, while secondary endpoints included mycological cure, composite cure, global efficacy assessment, and post-treatment relapse. Safety and tolerability were assessed. RESULTS: Amongst the enrolled patients, 69.9% and 68.1% of patients had tinea corporis, while 30.1% and 31.9% had tinea cruris. The majority of patients in both groups (99.3% test and 97% reference) achieved a clinical cure at the end of treatment. Mycological cure was achieved by 98.6% and 96.3% respectively. A composite cure was achieved by 98.6% in the test arm versus 96.3% in the reference arm. A total of two AEs were reported in two (1.4%) patients in the test group and three AEs were reported in three (2.1%) patients in the reference group, all of the AEs were mild and resolved within three days without supportive medication. No severe adverse effects were reported in any of the study subjects. CONCLUSION: Amorolfine lotion 0.25% w/v showed a non-inferior clinical, mycological, and composite cure in dermatophytosis patients, was well-tolerated, and had a similar safety profile to amorolfine cream 0.25% w/w.

Fungal vaccines and adjuvants: a tool to reveal the interaction between host and fungi.

Fungal infections are incurring high risks in a range from superficial mucosal discomforts (such as oropharyngeal candidiasis and vulvovaginal candidiasis) to disseminated life-threatening diseases (such as invasive pulmonary aspergillosis and cryptococcal meningitis) and becoming a global health problem in especially immunodeficient population. The major obstacle to conquer fungal harassment lies in the presence of increasing resistance to conventional antifungal agents used in newly clinically isolated strains. Although recombinant cytokines and mono-/poly-clonal antibodies are added into antifungal armamentarium, more effective antimycotic drugs are exceedingly demanded. It is comforting that the development of fungal vaccines and adjuvants opens up a window to brighten the prospective way in the diagnosis, prevention and treatment of fungal assaults. In this review, we focus on the progression of several major fungal vaccines devised for the control of Candida spp., Aspergillus spp., Cryptococcus spp., Coccidioides spp., Paracoccidioides spp., Blastomyces spp., Histoplasma spp., Pneumocystis spp. as well as the adjuvants adopted. We then expound the interaction between fungal vaccines/adjuvants and host innate (macrophages, dendritic cells, neutrophils), humoral (IgG, IgM and IgA) and cellular (Th1, Th2, Th17 and Tc17) immune responses which generally experience immune recognition of pattern recognition receptors, activation of immune cells, and clearance of invaded fungi. Furthermore, we anticipate an in-depth understanding of immunomodulatory properties of univalent and multivalent vaccines against diverse opportunistic fungi, providing helpful information in the design of novel fungal vaccines and adjuvants.

Sirtulin-Ypk1 regulation axis governs the TOR signaling pathway and fungal pathogenicity in Cryptococcus neoformans.

Cryptococcus neoformans is a life-threatening fungal pathogen that is a causative agent for pulmonary infection and meningoencephalitis in both immunocompetent and immunodeficient individuals. Recent studies have elucidated the important function of the target of rapamycin (TOR) signaling pathway in the modulation of C. neoformans virulence factor production and pathogenicity in animal infection models. Herein, we discovered that Ypk1, a critical component of the TOR signaling pathway, acts as a critical modulator in fungal pathogenicity through post-translational modifications (PTMs). Mass spectrometry analysis revealed that Ypk1 is subject to protein acetylation at lysines 315 and 502, and both sites are located within kinase functional domains. Inhibition of the C. neoformans TOR pathway by rapamycin activates the deacetylation process for Ypk1. The YPK1Q strain, a hyper-acetylation of Ypk1, exhibited increased sensitivity to rapamycin, decreased capsule formation ability, reduced starvation tolerance, and diminished fungal pathogenicity, indicating that deacetylation of Ypk1 is crucial for responding to stress. Deacetylase inhibition assays have shown that sirtuin family proteins are critical to the Ypk1 deacetylation mechanism. After screening deacetylase mutants, we found that Dac1 and Dac7 directly interact with Ypk1 to facilitate the deacetylation modification process via a protein-protein interaction. These findings provide new insights into the molecular basis for regulating the TORC-Ypk1 axis and demonstrate an important function of protein acetylation in modulating fungal pathogenicity. IMPORTANCE: Cryptococcus neoformans is an important opportunistic fungal pathogen in humans. While there are currently few effective antifungal treatments, the absence of novel molecular targets in fungal pathogenicity hinders the development of new drugs. There is increasing evidence that protein post-translational modifications (PTMs) can modulate the pathogenicity of fungi. In this study, we discovered that the pathogenicity of C. neoformans was significantly impacted by the dynamic acetylation changes of Ypk1, the immediate downstream target of the TOR complex. We discovered that Ypk1 is acetylated at lysines 315 and 502, both of which are within kinase functional domains. Deacetylation of Ypk1 is necessary for formation of the capsule structure, the response to the TOR pathway inhibitor rapamycin, nutrient utilization, and host infection. We also demonstrate that the sirtuin protein family is involved in the Ypk1 deacetylation mechanism. We anticipate that the sirtuin-Ypk1 regulation axis could be used as a potential target for the development of antifungal medications.