Oropharyngeal Candidiasis Research Articles

Global fungal-host interactome mapping identifies host targets of candidalysin

Candidalysin, a cytolytic peptide toxin secreted by the human fungal pathogen Candida albicans, is critical for fungal pathogenesis. Yet, its intracellular targets have not been extensively mapped. Here, we performed a high-throughput enhanced yeast two-hybrid (HT-eY2H) screen to map the interactome of all eight Ece1 peptides with their direct human protein targets and identified a list of potential interacting proteins, some of which were shared between the peptides. CCNH, a regulatory subunit of the CDK-activating kinase (CAK) complex involved in DNA damage repair, was identified as one of the host targets of candidalysin. Mechanistic studies revealed that candidalysin triggers a significantly increased double-strand DNA breaks (DSBs), as evidenced by the formation of γ-H2AX foci and colocalization of CCNH and γ-H2AX. Importantly, candidalysin binds directly to CCNH to activate CAK to inhibit DNA damage repair pathway. Loss of CCNH alleviates DSBs formation under candidalysin treatment. Depletion of candidalysin-encoding gene fails to induce DSBs and stimulates CCNH upregulation in a murine model of oropharyngeal candidiasis. Collectively, our study reveals that a secreted fungal toxin acts to hijack the canonical DNA damage repair pathway by targeting CCNH and to promote fungal infection.

Holotoxin A1 from Apostichopus japonicus inhibited oropharyngeal and intra-abdominal candidiasis by inducing oxidative damage in Candida albicans.

The holotoxin A1, isolated from Apostichopus japonicus, exhibits potent antifungal activities, but the mechanism and efficacy against candidiasis are unclear. In this study we have studied the antifungal effects and mechanism of holotoxin A1 against Candida albicans and in murine oropharyngeal and intra-abdominal candidiasis. The antifungal effect of holotoxin A1 against C. albicans was tested in vitro. To explore the antifungal mechanism of holotoxin A1, the transcriptome, ROS levels, and mitochondrial function of C. albicans was evaluated. Effectiveness and systematic toxicity of holotoxin A1 in vivo was assessed in the oropharyngeal and intra-abdominal candidiasis models in mice. Holotoxin A1 was a potent fungicide against C. albicans SC5314, clinical strains and drug-resistant strains. Holotoxin A1 inhibited oxidative phosphorylation and induced oxidative damage by increasing intracellular accumulation of ROS in C. albicans. Holotoxin A1 induced dysfunction of mitochondria by depolarizing the mitochondrial membrane potential and reducing the production of ATP. Holotoxin A1 directly inhibited the enzymatic activity of mitochondrial complex I and antagonized with the rotenone, an inhibitor ofcomplex I, against C. albicans. Meanwhile, the complex I subunit NDH51 null mutants showed a decreased susceptibility to holotoxin A1. Furthermore, holotoxin A1 significantly reduced fungal burden and infections with no significant systemic toxicity in oropharyngeal and intra-abdominal candidiasis in murine models. Holotoxin A1 is a promising candidate for the development of novel antifungal agents against both oropharyngeal and intra-abdominal candidiasis, especially when caused by drug-resistant strains.

Nanobody-mediated neutralization of candidalysin prevents epithelial damage and inflammatory responses that drive vulvovaginal candidiasis pathogenesis.

Candida albicans can cause mucosal infections in humans. This includes oropharyngeal candidiasis, which is commonly observed in human immunodeficiency virus infected patients, and vulvovaginal candidiasis (VVC), which is the most frequent manifestation of candidiasis. Epithelial cell invasion by C. albicans hyphae is accompanied by the secretion of candidalysin, a peptide toxin that causes epithelial cell cytotoxicity. During vaginal infections, candidalysin-driven tissue damage triggers epithelial signaling pathways, leading to hyperinflammatory responses and immunopathology, a hallmark of VVC. Therefore, we proposed blocking candidalysin activity using nanobodies to reduce epithelial damage and inflammation as a therapeutic strategy for VVC. Anti-candidalysin nanobodies were confirmed to localize around epithelial-invading C. albicans hyphae, even within the invasion pocket where candidalysin is secreted. The nanobodies reduced candidalysin-induced damage to epithelial cells and downstream proinflammatory responses. Accordingly, the nanobodies also decreased neutrophil activation and recruitment. In silico mathematical modeling enabled the quantification of epithelial damage caused by candidalysin under various nanobody dosing strategies. Thus, nanobody-mediated neutralization of candidalysin offers a novel therapeutic approach to block immunopathogenic events during VVC and alleviate symptoms.IMPORTANCEWorldwide, vaginal infections caused by Candida albicans (VVC) annually affect millions of women, with symptoms significantly impacting quality of life. Current treatments are based on anti-fungals and probiotics that target the fungus. However, in some cases, infections are recurrent, called recurrent VVC, which often fails to respond to treatment. Vaginal mucosal tissue damage caused by the C. albicans peptide toxin candidalysin is a key driver in the induction of hyperinflammatory responses that fail to clear the infection and contribute to immunopathology and disease severity. In this pre-clinical evaluation, we show that nanobody-mediated candidalysin neutralization reduces tissue damage and thereby limits inflammation. Implementation of candidalysin-neutralizing nanobodies may prove an attractive strategy to alleviate symptoms in complicated VVC cases.

Powder diet exacerbates oropharyngeal candidiasis in a mouse model.

This study reports on the influence of a powder diet in a mouse model of oropharyngeal candidiasis (OPC), a significant health concern caused primarily by Candida albicans. Despite identical nutritional composition, we found that a powdered diet significantly increased Candida burdens and oral lesions, and aggravated weight loss compared to a standard pelleted diet. High fungal burdens and severe oral lesions were accomplished within 48 hours after infection with only one dose of cortisone. Moreover, mice on a powder diet recovered a week after infection. Using a powder diet, we thus modified the cortisone OPC murine model in a way that simplifies the infection process, enhances reproducibility, and facilitates studies investigating both pathogenesis and recovery processes. Our findings also underscore the pivotal role of the physical form of the diet in the progression and severity of oral Candida infection in this model. Future research should investigate this relationship further to broaden our understanding of the underlying mechanisms, potentially leading to novel prevention strategies and improved disease management.IMPORTANCEOropharyngeal candidiasis (OPC) is a multifactorial disease and a significant health concern. We found that the physical form of the diet plays a critical role in the severity and progression of OPC. We developed a modified cortisone OPC murine model that facilitates studies investigating pathogenesis and recovery processes.

The Efficacy and Safety of Bimekizumab for Plaque Psoriasis: An Expert Consensus Panel.

Psoriasis is a chronic inflammatory condition affecting the skin, joints, and several other organ systems with significant disease burden. Bimekizumab is the first monoclonal antibody targeting both interleukin (IL)-17A and interleukin-17F and has demonstrated efficacy for treating moderate to severe psoriasis. Limited guidelines exist for incorporating this drug into clinical practice. The purpose of this study was for a panel of experts in psoriasis management to synthesize current literature and provide consensus statements with guidance on use of bimekizumab. A comprehensive literature search of PubMed, Scopus, and Google Scholar was completed for English-language original research articles on the use of bimekizumab for moderate to severe psoriasis and psoriatic arthritis. A panel of nine dermatologists with significant expertise in treatment of psoriasis gathered to review the articles and create consensus statements on this new medication. A modified Delphi process was used to approve each statement and a strength of recommendation was assigned using Strength of Recommendation Taxonomy criteria. The literature search produced 102 articles that met criteria. A thorough screening of the studies for relevance to the research question resulted in 19 articles. These were distributed to all panelists for review prior to a roundtable discussion. The panel unanimously voted to adopt 14 consensus statements and recommendations, 12 of which were given a strength of "A", one of which was given a strength of "B", and one of which was given a strength of "C". Bimekizumab results in rapid and long-lasting clinical improvement for patients with moderate to severe plaque psoriasis and psoriatic arthritis. It has demonstrated superior efficacy when compared to several other biologics. The safety profile is consistent with other biologics, except for an increased incidence of oropharyngeal candidiasis.

Immunity to pathogenic mucosal C. albicans infections mediated by oral megakaryocytes activated by IL-17 and candidalysin

The fungus Candida albicans can cause mucosal infections including oropharyngeal candidiasis (OPC) in immunocompromised patients. In humans, an increased risk of fungal infections correlates with thrombocytopenia. However, our understanding of platelets and megakaryocytes in mucosal fungal infections is almost entirely unknown. When megakaryocyte- and platelet-depleted mice were infected with OPC, the tongue showed higher fungal burden, due to decreased neutrophil accumulation. Protection depended on a distinct population of oral-resident megakaryocytes. Interleukin-17, important in antifungal immunity, was required since mice lacking the IL-17 receptor had decreased circulating platelets and their oral megakaryocytes did not expand during OPC. The secretion of the peptide toxin candidalysin activated human megakaryocytes to release platelets with antifungal capacity. Infection with a candidalysin-deficient strain resulted in decreased expansion of tongue megakaryocytes during OPC. This is the first time that a distinct megakaryocyte population was identified in the oral mucosa that is critical for immunity against fungal infection.

Distribution and antifungal susceptibility profile of oropharyngeal Candida species isolated from people living with HIV in the era of universal test and treat policy in Uganda.

Despite the increased frequency of oropharyngeal candidiasis among people living with human immunodeficiency virus (HIV), its management is no longer effective due to empirical treatment and emergence of antifungal resistance (AFR). This study sought to investigate the prevalence of oropharyngeal candidiasis and assess the antifungal susceptibility profile of oropharyngeal Candida species isolated from people living with human immunodeficiency virus. Additionally, we evaluated the correlation between oropharyngeal candidiasis and CD4 T cell as well as viral load counts. A descriptive cross-sectional study was carried out from April to October 2023 in which 384 people living with HIV underwent clinical examination for oral lesions. Oropharyngeal swabs were collected and cultured on Sabouraud Dextrose agar to isolate Candida species which were identified using the matrix assisted laser desorption ionization time of flight mass spectrometry. Additionally, the antifungal susceptibility profile of Candida isolates to six antifungal drugs was determined using VITEK® (Marcy-l'Étoile, France) compact system. Data on viral load were retrieved from records, and CD4 T cell count test was performed using Becton Dickinson Biosciences fluorescent antibody cell sorter presto. The prevalence of oropharyngeal candidiasis was 7.6%. Oropharyngeal candidiasis was significantly associated with low CD4 T cell count and high viral load. A total of 35 isolates were obtained out of which Candida albicans comprised of 20 (57.1%) while C. tropicalis and C. glabrata comprised 4 (11.4%) each. C. parapsilosis, C. dubliniensis and C. krusei accounted for 2 (5.7%) each. Additionally, 7 (20%) isolates were resistant to fluconazole, 1 (2.9%) to flucytocine and 0.2 (5.7%) isolates were intermediate to caspofungin. However, specific specie isolates like C. albicans showed 20% (4/20), C. glabrata 50% (2/4) and C. krusei 50% (1/2) resistance to fluconazole. Additionally, C. krusei showed 50% resistance to flucytosine. The prevalence of oropharyngeal candidiasis (OPC) among people living with HIV was low, and there was a significant association between OPC and CD4 T cell count as well as viral load. C. albicans was the most frequently isolated oropharyngeal Candida species. C. glabrata and C. krusei exhibited the highest AFR among the non-albicans Candida species. The highest resistance was demonstrated to fluconazole.

Study of prescription pattern of antifungal drugs from tertiary care hospital

Background: The most common superficial fungal infections are tinea corporis, tinea cruris, tinea capitis, tinea pedis, tinea unguium, and tinea facie and cutaneous Candida albicans infections such as oral thrush, oropharyngeal candidiasis, vaginal candidiasis, and onychomycosis. Aims and Objectives: (i) Analysis of prescription pattern of antifungal drugs and (ii) to study common adverse effects. Materials and Methods: A retrospective, observational study conducted in B. K. L. Walawalkar Hospital, Sawarde, Ratnagiri. A total of 993 case papers were analyzed after getting approval from the institutional ethics committee and permission from dermatology department. The frequency with percentage was used for the analysis of data. Results: In 993 patients with superficial fungal infections, 523 (52.7%) were males and 470 (47.3%) were females. Majority of patients were belonged to 21–40-year age group, i.e., 439 (44.2%) followed by 41–60 years, i.e., 244 (24.6%). Our study shows that the most common superficial fungal infections with single lesion were tinea corporis (22.3%), tinea cruris (14.6%), and pityriasis versicolor (13.9%). In Candida albicans, the most common infection was onychomycosis 14 (1.4%). The most common antifungal prescribed was luliconazole (20.84%) followed by itraconazole (20.58%). The most common route was topical route (68.26%). Combination of drugs was not prescribed. Different prescription indicators were that the average number of drugs prescribed per encounter was 3.4 and average number of drugs prescribed per encounter was 2.7. Conclusion: Most commonly prescribed newer antifungal was luliconazole. Next most commonly prescribed by oral route was itraconazole. No use of combination of drugs and many drugs selected from essential medicinal list. Based on these finding we concluded prescriptions where rational approach.

FEATURES OF HIV-INFECTION IN PATIENTS WITH LATE PRESENTATION WHO RECEIVE DTG-BASED ANTIRETROVIRAL THERAPY REGIMENS

Late presentation of HIV-infection is one of the most serious challenges in providing medical care to HIV-infected patients, because delay in detection and treatment of HIV-infection leads to a gradual decrease in the number of CD4+lymphocytes and the threat of infectious complications and tumor processes.
 Objective of this study is to find out the features of HIV-infection in people with late presentation of the disease, to evaluate the effectiveness of treatment and factors influencing the emergence of severe opportunistic infections on the background of dolutegravir-based antiretroviral therapy regimens. To achieve this goal, a cohort retrospective study was conducted, during which data from 210 outpatient records were analyzed.
 Analysis of opportunistic infections depending on the level of lymphocytes at the time of registration showed that in 123 (58.6%) of 210 late presenters, opportunistic infections were diagnosed at lymphocytes level below 200 cells/mL, in 22 people, while severe opportunistic infections were registered at a lymphocytes level above 500 cells/mL.
 Analysis of the clinical effectiveness of antiretroviral therapy showed that while taking the drugs, some patients continued to develop severe opportunistic infections such as tuberculosis, oropharyngeal candidiasis and severe bacterial diseases. An analysis of the Kaplan-Meier survival curve showed that there is a significant relationship between low baseline lymphocytes counts and the development of late opportunistic infections during treatment.
 Thus, the majority of HIV-infected patients were diagnosed with wasting syndrome, profound immunosuppression, severe opportunistic infections, and their combination at the time of registration. In some patients, severe late opportunistic infections were diagnosed with a satisfactory lymphocytes count above 500 cells/mL and subsequently on antiretroviral treatment. A low baseline lymphocytes count was identified as a risk factor for the development of severe opportunistic infections on antiretroviral therapy.

Prevalence, Risk Factors, Treatment, Outcome, and Diagnosis of COVID-19-Associated Pulmonary Aspergillosis Using a Serum Galactomannan Assay

Background: Coronavirus-associated pulmonary aspergillosis (CAPA) is defined as invasive pulmonary aspergillosis (IPA) occurring in patients with COVID-19 infection. Objectives: This study aimed to identify CAPA patients and describe their clinical-epidemiological characteristics in Ahvaz, Iran, from the third to the fifth COVID-19 waves. Methods: The serum galactomannan (GM) antigen assay was used to detect CAPA in 257 COVID-19 hospitalized patients according to the EORTC/MSGERC (European Organization for Research and Treatment of Cancer and the Mycoses Study Group Education and Research Consortium) 2020 criteria. The demographic and clinical data, host risk factors, lung radiographic imaging, laboratory findings, antifungal agents used, and the outcomes of the patients were extracted in cases that were available. All findings were statistically analyzed. Results: Of the 257 patients, 114 (44.35%) were positive for GM levels (CAPA cases). The demographic and clinical information of 51 cases showed that diabetes mellitus (25.5%) was the most common underlying condition, followed by oropharyngeal candidiasis (22%) and hypertension (21.6%). In both surviving and deceased patients, the frequency of CAPA in older ages was statistically significant (r = 0.519; P < 0.0001). In surviving individuals, GM had a significant relationship with age (r = 0.520; P = 0.032), blood glucose (BS; r = 0.497; P = 0.043), diagnosis of hyperglycemia during hospitalization (P = 0.039), and diabetes mellitus (P = 0.039). In deceased patients, the frequency of CAPA in older ages was statistically significant (r = 0.503; P = 0.002). Galactomannan had a significant association with the variables of age (r = 0.503; P = 0.002) and suspicion of fungal infection (P = 0.003). Conclusions: The prevalence of CAPA was high in critically ill patients with COVID-19. Diabetes mellitus, hyperglycemia, and old age are the main factors that predispose COVID-19 patients to IPA.

Metal-Phenolic Network with Pd Nanoparticle Nodes Synergizes Oxidase-Like and Photothermal Properties to Eradicate Oral Polymicrobial Biofilm-Associated Infections.

Designing an effective treatment strategy to combat oral diseases caused by complex polymicrobial biofilms remains a great challenge. Herein, a series of metal-phenolic network with Pd nanoparticle nodes using polyphenols as stabilizers and reducing agents is constructed. Among them, sulfonated lignin-Pd (SLS-Pd) with ultrafine size palladium nanoparticles and broadband near infrared absorption exhibit excellent oxidase-like activity and stable photothermal effect. In vitro experiments demonstrate that the superoxide radical generated by SLS-Pd oxidase-like activity exhibits selective antibacterial effects, while its photothermal effect induced hyperthermia exhibits potent antifungal properties. This difference is further elucidated by RNA-sequencing analysis and all-atom simulation. Moreover, the SLS-Pd-mediated synergistic antimicrobial system exhibits remarkable efficacy in combating various biofilms and polymicrobial biofilms. By establishing a root canal model and an oropharyngeal candidiasis model, the feasibility of the synergistic antimicrobial system in treating oral biofilm-related infections is further validated. This system provides a promising therapeutic approach for polymicrobial biofilm-associated infections in the oral cavity.

Adherence of Candida Species Isolated from Patients with Head and Neck Cancer Presented for Radiation Therapy and its Correlation with Hemogram

The objective of the current study was to quantify the adherence property of Candida species causing infections in head and neck cancer patients on radiation therapy (RT) or chemoradiotherapy (CRT). Additionally, the study aimed to establish a correlation between adherence properties and patients’ hemograms. A prospective cohort study was done on head and neck cancer (HNC) patients with oropharyngeal candidiasis. All patients received radiation doses ranging from 60 to 70 Gy using Intensity Modulated Radiation Therapy. Inoperable patients received concurrent chemotherapy with cisplatin 40mg/m2 once weekly during the course of RT. Swabs were collected from patients with signs and symptoms of candidiasis and microbiological confirmation and speciation were done according to standard protocol. An in vitro adherence test was done. Hemogram of all the patients at the start of infection was compared with the adherence. Candidiasis was detected in 58(35.3%) out of a total of 164 patients (Age 36-85). Candida albicans was the most prevalent 39(67.2%) species isolated. C.albicans showed the highest adherence which was statistically significant. The hemogram at the start of treatment and with C. albicans infection showed a statistically significant decrease in the absolute lymphocyte count (p-value 0.0001), RBC count (p-value 0.004) and haemoglobin level (p-value 0.003). Less adherence was seen with non-albicans Candida infection when compared to C.albicans (Odds 0.894, 95% CI -0.818-0.977), significant at 5 % (0.013). C. albicans showed significant adherence, which indicates the severity of infection. The occurrence of oral candidiasis is strongly associated with low lymphocyte count and severity of mucositis. Absolute lymphocyte count needs to be monitored in HNC patients who are undergoing RT or CRT.

Repurposing a human acetyl-CoA carboxylase inhibitor firsocostat to treat fungal candidiasis alone and in combination.

Opportunistic fungal infections, particularly caused by Candida albicans, remain a common cause of high morbidity and mortality in immunocompromised patients. The escalating prevalence of antifungal drug resistance necessitates the immediate exploration of alternative treatment strategies to combat these life-threatening fungal diseases. In this study, we investigated the antifungal efficacy of firsocostat, a human acetyl-CoA carboxylase (ACC) inhibitor, against C. albicans. Firsocostat alone displayed moderate antifungal activity, while combining it with voriconazole, itraconazole, or amphotericin B exhibited synergistic effects across almost all drug-sensitive and drug-resistant C. albicans strains tested. These observed synergies were further validated in two mouse models of oropharyngeal and systemic candidiasis, where the combination therapies demonstrated superior fungicidal effects compared to monotherapy. Moreover, firsocostat was shown to directly bind to C. albicans ACC and inhibit its enzymatic activity. Sequencing spontaneous firsocostat-resistant mutants revealed mutations mapping to C. albicans ACC, confirming that firsocostat has retained its target in C. albicans. Overall, our findings suggest that repurposing firsocostat, either alone or in combination with other antifungal agents, holds promising potential in the development of antifungal drugs and the treatment of candidiasis.

An Observational Study of Clinical and Microbiological Profile of Esophageal Candidiasis in a Tertiary Care Center, Madras City, India

Back Ground: Esophageal candidiasis, previously believed to be limited to immunocompromised individuals, is now on the rise among those with healthy immune systems. This condition can be severely debilitating, and if not managed effectively, it can lead to persistent and enduring infections.The clinical spectrum,predisposing factors and microbiological profile of esophageal candidiasis has not been evaluated previously in our hospital. Aim: To analyze the clinical and microbiological profile of patients with esophageal candidiasis. Methods: The study conducted at Madras Medical College in Chennai during 2021-2022 is an observational study centered at a single institution. It involved a cohort of 100 patients diagnosed with candida esophagitis who met the specified inclusion criteria. The diagnosis of candida esophagitis (EC) in the study was established through the identification of characteristic candidal plaques during endoscopy. Biopsies were taken using standard biopsy forceps, and the diagnosis was confirmed through pathological examination, which revealed the presence of yeast forms typical for candida invading the esophageal mucosa. Results: During the study period, around 16,000 upper endoscopies were performed in our endoscopy unit. The main findings of our study was that the prevalence of EC was less observed (0.62%, 100/16000).One fourth (26%) of our cases were presented with dysphagia followed by nausea (15%), dyspepsia (15%), asymptomatic (11%), regurgitation (9%), chest discomfort (8%), vomiting (6%), odynophagia (5%) and hiccups (5%). More than half (59%) of cases during endoscopy were grade 1 esophageal candidiasis followed by grade 2 EC (32%), grade 3 EC (8%) & oropharyngeal candidiasis observed in (1%). More than one third (39%) of cases candida lesions observed in distal esophagus followed by entire esophagus in (27%), mid esophagus in (24%) and upper esophagus in (10%). KOH mount positive in 56% cases and more than 2/3rd (67%) of EC were due to candida albicans species & one fifth (20%) showed resistance to fluconazole. Conclusion: In conclusion, Candida esophagitis may be more common than previously suspected. Neither the presenting symptoms nor the endoscopy findings are always classic for this disease. Large-size prospective studies are needed to further identify the clinical & microbiological profile of esophageal candidiasis.

Ethyl caffeate combined with fluconazole exhibits efficacy against azole-resistant oropharyngeal candidiasis via the EFGR/JNK/c-JUN signaling pathway.

Ethyl caffeate (EC) is a phenylpropanoid compound derived from Elephantopus scaber. In our previous work, EC was investigated to have a strong synergistic antifungal effect against azole-resistant strains of Candida albicans when combined with fluconazole (FLU). However, the protective effect and mechanism of EC+FLU on oropharyngeal candidiasis (OPC) caused by drug-resistant strains of C. albicans has not been investigated. This study aimed to investigate the protective effect and mechanism of EC combined with FLU against C. albicans-resistant strains that lead to OPC. An OPC mouse model revealed that EC+FLU treatment reduced fungal load and massive hyphal invasion of tongue tissues, and ameliorated the integrity of the tongue mucosa. PAS staining results showed more structural integrity of the tongue tissues and reduced inflammatory cell infiltration after EC+FLU treatment. Phosphorylation of EGFR and other proteins in the EFGR/JNK/c-JUN signaling pathway was significantly downregulated by EC+FLU. EGFR and S100A9 mRNA expression was also reduced. The above results were verified in FaDu cells. ELISA results showed that the concentration of inflammatory factors in the cell supernatant was significantly reduced after EC combined with FLU treatment. Molecular docking revealed that EC exhibited high binding energy to EGFR. In conclusion, EC enhances the susceptibility of azole-resistant C. albicans to FLU, and the underlying mechanism is related to the inhibition of the EGFR/JNK/c-JUN signaling pathway. This result suggests that EC has potential to be developed as an antifungal sensitizer to treat OPC caused by azole-resistant C. albicans.

Alternative oxidase promotes high iron tolerance in Candida albicans.

Although crucial for cellular functioning, iron is toxic when present in excess. Iron overload can create a labile iron pool (LIP) that harms the mitochondrion, resulting in disruption of oxidative respiration. Fungal pathogen C. albicans possesses an unconventional terminal oxidase [alternative oxidase (AOX)] that can disrupt the electron transport chain to remove excess electrons, generated from various stressors, to shield the respiratory apparatus. Here, we identify a novel role for AOX under high iron, whereby it works as "safety valve" to protect the mitochondrion from high iron-induced reactive oxygen species (ROS). C. albicans showed pronounced metabolic flexibility to environmental iron, ranging from 1 to 500 µM. High iron significantly increased intracellular iron, LIP, and levels of cellular ROS. Expression of both AOX1/2 was induced by iron, and cells lacking Aox1/2 showed high levels of mitochondrial ROS as well as significant growth defect under high iron. Thus, Aox1/2 helps mitigate the negative effects of iron. Furthermore, iron-induced expression of AOX1/2 was intermittent, thus preventing ATP loss despite AOX being non-proton motive. Mitochondrial oxygen consumption rate (OCR) was significantly higher (62.8%) under high iron conditions. Contribution of Aox1/2 was greater toward this high OCR, compared to their contribution in low iron conditions. Lastly, enhanced virulence of C. albicans that is observed for wild-type cells under high iron was lost when fungal cells lacking AOX1/2 were used for murine infection. Thus, AOX is crucial for preserving mitochondrial function for survival in a high iron host.IMPORTANCEThe yeast C. albicans exhibits metabolic flexibility for adaptability to host niches with varying availability of nutrients including essential metals like iron. For example, blood is iron deplete, while the oral cavity and the intestinal lumen are considered iron replete. We show here that C. albicans can tolerate very high levels of environmental iron, despite an increase in high iron-induced reactive oxygen species (ROS) that it mitigates with the help of a unique oxidase, known as alternative oxidase (AOX). High iron induces AOX1/2 that limits mitochondrial accumulation of ROS. Genetic elimination of AOX1/2 resulted in diminished virulence during oropharyngeal candidiasis in high iron mice. Since human mitochondria lack AOX protein, it represents a unique target for treatment of fungal infections.

Severe combined immunodeficiency with a homozygous c.464T>C (p.Leu155Pro) mutation in the RAG2 gene in a country without neonatal screening: Report of two clinical cases

Introduction: Severe combined immunodeficiency (SCID) is a disorder belonging to the broad spectrum of inborn errors of immunity (IEI), characterized by a predisposition to develop recurrent, severe, difficult-to-treat opportunistic infections. This disorder is associated with abnormalities in genes of the adaptive immune system and should be suspected in patients with infections during the first months of life, mainly due to fungal pathogens and intracellular agents. Case Presentation: Two cases of SCID diagnosed at the General Hospital with Specialties "Juan María de Salvatierra” in Baja California Sur (BCS), México in 2022 are described. The first patient presented persistent candidiasis stomatitis with no response to oral treatment. The second patient presented mycotic dermatitis and oropharyngeal candidiasis compatible with Candida albicans and multiple episodes of multi-treated airway infection with partial remission. The diagnosis was completed with a genetic panel that showed a mutation in RAG2 homozygous variant c.464T>C (p.Leu155Pro) in both patients. Conclusions: SCID should be considered in patients with recurrent and difficult-to-treat infectious diseases in the first months of life. For its timely detection, implementing neonatal screening quantifying of T-cell receptor excision circles (TRECs) is recommended. This method is not available in Mexico, so it has been relevant to have physicians trained in the timely clinical identification of the disease. Thanks to the prompt referral of both patients to our hospital, we could treat the comorbidities associated with SCID, provide a specific molecular diagnosis, and transfer the patients to a hospital specialized in bone marrow transplantation for definitive treatment.

The Development and Evaluation of Linalool-loaded Liposomal Gel for Oral Candida Infections: Characterization, Skin Permeation, Dermal Retention, and In Vitro Anti-microbial Studies

Background: Linalool is a known anti-fungal molecule. It could be a good candidate against oropharyngeal candidiasis if its retention in deeper skin layers, specifically at body tempera-ture, can be extended for a long duration. Aim: We aimed to develop and evaluate a linalool liposome-based mucoadhesive gel. Objective: The objective of this study is to improvise localization in oral mucosa by achieving sus-tained release, ensuring less volatility of linalool and less permeability into the systemic circulation through the mucosa. Methods: The liposomes were prepared by film formation and hydration method and characterized for particle size, polydispersity index, encapsulation efficiency, and morphological characteristics. The lipid carriers were dispersed into the gel matrix of carbopol 934 and HPMC. Results: The gel was characterized and evaluated for in vitro drug release, ex vivo drug permeation through the goat mucosa and ex vivo dermal retention studies. The particle size and entrapment effi-ciency were 201 nm and 79.8%, respectively, with 0.300 PDI. Transmission Electron Microscopy revealed the spherical shape of the particles with a well-identified surface. The gel pH (6.8) was close to oral mucosal pH and had desired adhesiveness and rheological properties. The latter portrayed a slow linalool release (74.75% in 12 hours), low permeation (28.80% in 24 hours) through the mucosa and high retention (45%) compared to simple linalool gel, ensuring its improvised anti-microbial effectiveness against candida. Conclusion: A mucoadhesive liposomal gel offers a suitable medium for ensuring modified release, improved mucosal retention, and the ability to achieve the desired therapeutic effectiveness locally in mucosa for other drugs of volatile nature.

The Candida albicans reference strain SC5314 contains a rare, dominant allele of the transcription factor Rob1 that modulates filamentation, biofilm formation, and oral commensalism.

Candida albicans is a commensal fungus that colonizes the human oral cavity and gastrointestinal tract but also causes mucosal as well as invasive disease. The expression of virulence traits in C. albicans clinical isolates is heterogeneous and the genetic basis of this heterogeneity is of high interest. The C. albicans reference strain SC5314 is highly invasive and expresses robust filamentation and biofilm formation relative to many other clinical isolates. Here, we show that SC5314 derivatives are heterozygous for the transcription factor Rob1 and contain an allele with a rare gain-of-function SNP that drives filamentation, biofilm formation, and virulence in a model of oropharyngeal candidiasis. These findings explain, in part, the outlier phenotype of the reference strain and highlight the role heterozygosity plays in the strain-to-strain variation of diploid fungal pathogens.

IκBζ is an essential mediator of immunity to oropharyngeal candidiasis

Fungal infections are a global threat; yet, there are no licensed vaccines to any fungal pathogens. Th17 cells mediate immunity to Candida albicans, particularly oropharyngeal candidiasis (OPC), but essential downstream mechanisms remain unclear. In the murine model of OPC, IκBζ (Nfkbiz, a non-canonical NF-κB transcription factor) was upregulated in an interleukin (IL)-17-dependent manner and was essential to prevent candidiasis. Deletion of Nfkbiz rendered mice highly susceptible to OPC. IκBζ was dispensable in hematopoietic cells and acted partially in the suprabasal oral epithelium to control OPC. One prominent IκBζ-dependent gene target was β-defensin 3 (BD3) (Defb3), an essential antimicrobial peptide. Human oral epithelial cells required IκBζ for IL-17-mediated induction of BD2 (DEFB4A, human ortholog of mouse Defb3) through binding to the DEFB4A promoter. Unexpectedly, IκBζ regulated the transcription factor Egr3, which was essential for C.albicans induction of BD2/DEFB4A. Accordingly, IκBζ and Egr3 comprise an antifungal signaling hub mediating mucosal defense against oral candidiasis.