Pathogenesis of invasive candidiasis

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.

Prophylaxis of Invasive Fungal Infection in Neonates: A Narrative Review for Practical Purposes

Candida albicans is the most frequent cause of invasive fungal disease in preterm and/or low birth weight neonates, followed by Candida parapsilosis, whilst infections from other species are rare. Considering the severity of the disease, associated with poor clinical signs and diagnostic difficulties, primary prophylaxis becomes relevant. This paper summarizes the pathogenesis and clinical presentation of invasive candidiasis in neonates, focusing on prophylaxis. For late onset invasive disease, e.g., those occurring after the 3rd (or 7th according to some definitions) day of life possible approaches are the use of fluconazole, recommended in case of weight <1000 g or <1500 g if the local incidence of invasive candidiasis is higher than 2%, or the use of nystatin (for patients < 1500 g). Micafungin must be used in case of colonization by Candida auris, or in centers with a high prevalence of this pathogen. Concurrently, correct management of the central venous catheter and isolation procedures, with special regard to patients colonized by resistant strains, are fundamental. Other approaches such as reduced use of H₂ blockers and broad-spectrum antibiotics (e.g., 3rd generation cephalosporins or carbapenems) and promotion of breast feeding proved useful. Reduction of early-onset infections (those occurring in the first 3 days of life) can also be obtained by treating maternal vulvo-vaginal candidiasis, which can represent a fastidious problem during pregnancy. In this case, topic azoles (the only recommendable treatment) can represent a kind of "prophylaxis" of early neonatal candidiasis. However, it must always be remembered that prophylaxis reduces the risk of invasive candidiasis but can not completely eliminate its occurrence, with the parallel risk of selecting for antifungal-resistant strains. Clinicians must maintain a high level of suspicion to start an appropriate therapy and strict epidemiological surveillance to identify the occurrence of clusters and the appearance of strains resistant to prophylaxis.

Comparative analysis of Candida spp. isolated from complete denture wearers with and without an HIV diagnosis

STATEMENT OF PROBLEM

Denture-related stomatitis (DRS), an inflammation frequently present in human immunodeficiency virus-positive (HIV+) individuals, can be attributable to colonization by Candida spp., which is considered a main factor. The virulence factors of these species are often modulated by the systemic condition of their hosts.

PURPOSE

The purpose of this clinical study was to evaluate the incidence, virulence, and morphology of Candida spp. isolated from biofilms of complete denture wearers with DRS, with and without an HIV diagnosis. In addition, the interaction of the systemic condition with the ability of Candida spp. to colonize was evaluated.

MATERIAL AND METHODS

Fifty-five complete denture wearers diagnosed with DRS were divided into 2 groups: experimental (HIV+) and control (human immunodeficiency virus-noninfected participants [HIV-]). Biofilm was collected by a standardized method of ultrasonification of prostheses. The incidence was evaluated by a chromogenic method and polymerase chain reaction (PCR). The virulence factors were assessed by using the capacity for biofilm formation by counting colony-forming units (CFUs/mL), biofilm metabolism by tetrazolium salt metabolization, and proteinase and phospholipase production by using a fluorimetric kit. Morphology was verified by using the hyphae-inducing test, and participants' health data were collected with a form. Data were analyzed by using the Student t, Mann-Whitney U, Spearman, and Fisher tests (α=.05).

RESULTS

The results of incidence were related to 55 participants (22 experimental and 33 control); in total, 63 Candida spp. samples were isolated, showing 28 Candida albicans and 36 nonalbicans strains. No significant difference was found between groups in baseline CFU/mL counts, biofilm formation capacity, cell metabolism, and phospholipase production. Proteinase production was higher for C. albicans in the control (P=.031) and for nonalbicans in the experimental (P=.016) groups. Relative to health data, the experimental group showed a moderate negative correlation between the CFU count/mL at baseline for nonalbicans and DRS classification (P=.020).

CONCLUSIONS

C. albicans was the most prevalent species. No difference was found in the Candida spp. of complete denture wearers with DRS, with and without an HIV diagnosis, with regard to virulence factors (except for proteinase production) and morphology.

Genotyping, antifungal susceptibility, enzymatic activity, and phenotypic variation in Candida albicans from esophageal candidiasis

Background

Esophageal candidiasis is the most frequent form of esophagitis. The pathogenicity of Candida spp. is related to a combination of microbial factors, hydrolytic enzyme secretion and phenotypic switching. This study was designed to investigate esophageal candidiasis, antifungal activity, enzymatic activity patterns, phenotyping, and genotyping profiles of Candida albicans species.

Methods

Nine hundred thirty‐three visited patients were evaluated, and esophageal biopsies from patients were included in this study during 2019–2020. Direct smear, Gram staining, and culture on CHROMagar were performed for each sample. Isolated species were identified with conventional procedures and PCR‐RFLP. Susceptibility to antifungals was determined according to CLSI guidelines. ABC typing, phenotype switching, hemolysin, proteinase, phospholipase, and esterase activity were also determined with the appropriate protocols.

Results

Twenty‐three (2.5%) patients (mean age 55.2 years) were diagnosed with esophageal candidiasis. The species isolated were 19(82.6%) C. albicans, 3(13.1%) C. glabrata, and 1(4.3%) C. tropicalis. Genotype A (57.9%) was the predominant type in C. albicans isolates. 50% of C. albicans isolates exhibited a white phenotype. A high level of phospholipase (47.4%), hemolysin (68.4%), and proteinase activity (36.8%) was observed in the C. albicans isolates. Only three C. glabrata isolates displayed non‐wild type susceptibility to voriconazole and itraconazole.

Conclusion

This study shows that C. albicans are still the most frequent isolates from patients with esophageal candidiasis. The predominance of genotype A, the white phenotype, and strong hemolysin activity may indicate a high prevalence of pathogenicity in these isolates. Sensitivity to antifungal drugs was greatest for amphotericin and fluconazole.

Hepatic Candidiasis in an Immunocompetent Patient: A Diagnostic Challenge

Hepatic candidiasis is a manifestation of disseminated candidiasis, which typically presents in immunocompromised patients. Focal hepatic candidiasis in immunocompetent patients, however, is infrequent/extremely rare. We present the case of an immunocompetent female patient who presented with respiratory distress and right-sided pleural effusion. The pleural fluid tap did not grow anything, and a contrast-enhanced computed tomography (CT) scan revealed a right liver lobe subcapsular collection. CT-guided aspiration and culture resulted in Candida albicans growth. The patient responded to oral fluconazole, and a follow-up CT scan demonstrated resolution of the collection. Although hepatic candidiasis rarely occurs in immunocompetent patients, it should be included in the differential diagnosis of hepatic abscesses, as timely diagnosis and management are crucial in conferring a good prognosis.

Vaccine-Induced Immunological Memory in Invasive Fungal Infections - A Dream so Close yet so Far

The invasive fungal infections (IFIs) are a major cause of mortality due to infectious disease worldwide. Majority of the IFIs are caused by opportunistic fungi including Candida, Aspergillus and Cryptococcus species. Lack of approved antifungal vaccines and the emergence of antifungal drug-resistant strains pose major constraints in controlling IFIs. A comprehensive understanding of the host immune response is required to develop novel fungal vaccines to prevent death from IFIs. In this review, we have discussed the challenges associated with the development of antifungal vaccines. We mentioned how host-pathogen interactions shape immunological memory and development of long-term protective immunity to IFIs. Furthermore, we underscored the contribution of long-lived innate and adaptive memory cells in protection against IFIs and summarized the current vaccine strategies.

Comparative host transcriptome in response to pathogenic fungi identifies common and species-specific transcriptional antifungal host response pathways

Candidiasis, aspergillosis, and mucormycosis cause the majority of nosocomial fungal infections in immunocompromised patients. Using an unbiased transcriptional profiling in PBMCs exposed to the fungal species causing these infections, we found a core host response in healthy individuals that may govern effective fungal clearance: it consists of 156 transcripts, involving canonical and non-canonical immune pathways. Systematic investigation of key steps in antifungal host defense revealed fungal-specific signatures. As previously demonstrated, Candida albicans induced type I and Type II interferon-related pathways. In contrast, central pattern recognition receptor, reactive oxygen species production, and host glycolytic pathways were down-regulated in response to Rhizopus oryzae, which was associated with an ER-stress response. TLR5 was identified to be uniquely regulated by Aspergillus fumigatus and to control cytokine release in response to this fungus. In conclusion, our data reveals the transcriptional profiles induced by C. albicans, A. fumigatus, and R. oryzae, and describes both the common and specific antifungal host responses that could be exploited for novel therapeutic strategies.

Using genetically encoded heme sensors to probe the mechanisms of heme uptake and homeostasis in Candida albicans

Candida albicans is a major fungal pathogen that can utilise hemin and haemoglobin as iron sources in the iron-scarce host environment. While C. albicans is a heme prototroph, we show here that it can also efficiently utilise external heme as a cellular heme source. Using genetically encoded ratiometric fluorescent heme sensors, we show that heme extracted from haemoglobin and free hemin enter the cells with different kinetics. Heme supplied as haemoglobin is taken up via the Common in Fungal Extracellular Membrane (CFEM) hemophore cascade, and reaches the cytoplasm over several hours, whereas entry of free hemin via CFEM-dependent and independent pathways is much faster, less than an hour. To prevent an influx of extracellular heme from reaching toxic levels in the cytoplasm, the cells deploy Hmx1, a heme oxygenase. Hmx1 was previously suggested to be involved in utilisation of haemoglobin and hemin as iron sources, but we find that it is primarily required to prevent heme toxicity. Taken together, the combination of novel heme sensors with genetic analysis revealed new details of the fungal mechanisms of heme import and homeostasis, necessary to balance the uses of heme as essential cofactor and potential iron source against its toxicity.

Simultaneous improvement of ketoconazole solubility, antifungal and antibiofilm activity by multicomponent complexation

Background: A novel multicomponent complex (MC) of ketoconazole (KET) with β-cyclodextrin (β-CD) and N-acetylcysteine (NAC) was developed with the purpose of improving the solubility as well as the antifungal and antibiofilm activity of KET against Candida albicans. Results & methodology: The interactions among the components were studied using nuclear magnetic resonance, thermal analysis, powder x-ray diffraction, infrared spectroscopy and scanning electron microscopy. Phase-solubility studies demonstrated a considerable increase in the solubility of the MC. An enhancement in antibiofilm and antifungal activity of MC was determined against C. albicans by XTT assay and microbiological studies. Conclusion: This MC, with improvements in the drug pharmaceutical performance, might have an important potential in the development of new pharmaceutical formulations of KET.

Recognition of Candida albicans and Role of Innate Type 17 Immunity in Oral Candidiasis

Candida albicans is an opportunistic pathogenic fungus considered to be a common member of the human microflora. Similar to some other opportunistic microbes, C. albicans can invade and benefit from its host when the immune status of that host is weakened. Most often this happens to immunocompromised individuals, leading to the infection of oral and vaginal mucosae or the systemic spread of the pathogen throughout the entire body. Oropharyngeal candidiasis (OPC) occurs in up to 90 percent of patients with acquired immunodeficiency syndrome (AIDS), making it the most frequent opportunistic infection for this group. Upon first signs of fungal invasion, a range of host signaling activates in order to eliminate the threat. Epithelial and myeloid type cells detect C. albicans mainly through receptor tyrosine kinases and pattern-recognition receptors. This review provides an overview of downstream signaling resulting in an adequate immune response through the activation of various transcription factors. The study discusses recent advances in research of the interleukin-17 (IL-17) producing innate cells, including natural T helper 17 (nTh17) cells, γδ T cells, invariant natural killer T (iNKT) cells and type 3 innate lymphoid cells (ILC3) that are involved in response to oral C. albicans infections.

STIM1-mediated calcium influx controls antifungal immunity and the metabolic function of non-pathogenic Th17 cells

Immunity to fungal infections is mediated by cells of the innate and adaptive immune system including Th17 cells. Ca²⁺ influx in immune cells is regulated by stromal interaction molecule 1 (STIM1) and its activation of the Ca²⁺ channel ORAI1. We here identify patients with a novel mutation in STIM1 (p.L374P) that abolished Ca²⁺ influx and resulted in increased susceptibility to fungal and other infections. In mice, deletion of STIM1 in all immune cells enhanced susceptibility to mucosal C. albicans infection, whereas T cell‐specific deletion of STIM1 impaired immunity to systemic C. albicans infection. STIM1 deletion impaired the production of Th17 cytokines essential for antifungal immunity and compromised the expression of genes in several metabolic pathways including Foxo and HIF1α signaling that regulate glycolysis and oxidative phosphorylation (OXPHOS). Our study further revealed distinct roles of STIM1 in regulating transcription and metabolic programs in non‐pathogenic Th17 cells compared to pathogenic, proinflammatory Th17 cells, a finding that may potentially be exploited for the treatment of Th17 cell‐mediated inflammatory diseases.

Candida Biofilms: An Update on Developmental Mechanisms and Therapeutic Challenges

Fungi of the genus Candida are important etiological agents of superficial and life-threatening infections in individuals with a compromised immune system. One of the main characteristics of Candida is its ability to form highly drug tolerance biofilms in the human host. Biofilms are a dynamic community of multiple cell types whose formation over time is orchestrated by a network of transcription regulators. In this brief review, we provide an update of the processes involved in biofilm formation by Candida spp. (formation, treatment, and control), as well as the transcriptional circuitry that regulates its development and interactions with other microorganisms. Candida albicans is known to build mixed species biofilms with other Candida species and with various other bacterial species in different host niches. Taken together, these properties play a key role in Candida pathogenesis. In addition, this review gathers recent studies with new insights and perspectives for the treatment and control of Candida biofilms.

Study of Antifungal Susceptibility, Virulence Genes and Biofilm Formation in Candida albicans

Background:

Candida albicans has emerged as an important nosocomial pathogen. The morbidity and mortality associated with this pathogen are related to the presence of virulence genes and antifungal resistance. The objective of the present study was to investigate the prevalence of antifungal resistance, biofilm formation and some virulence genes such as ALS1, PLB1, INT1, SAP1 and HWP1, among clinical isolates of Candida albicans recovered from immunocompromised patients.

Methods:

The study included one hundred C. albicans isolates identified phenotypically and by a molecular technique using Polymerase Chain Reaction (PCR). The identified C. albicans was further subjected to antifungal study by the microdilution method, biofilm study and molecular study for virulence genes by PCR.

Results:

The resistance to antifungal drugs, fluconazole, caspofungin and itraconazole was 8% for each of them and for amphotericin B, it was 9%. The prevalence of the studied virulence genes was HWP1 77%, INT1 72%, ALS1 65%, SAP1 65% and PLB1 52%. The biofilm capacity was identified by the microplate method in 58% of C. albicans. The OD was intense in 20 isolates, moderate in 21 isolates and mild in 17 isolates. There was a statistically significant increase in the prevalence of the studied virulence genes INT1, ALS1, HWP1, SAP1 and PLB1 among biofilm forming C. albicans as compared to non-biofilm forming isolates (P=0.0001). Additionally, the resistance to fluconazole, itraconazole and caspofungin was statistically, significantly higher in C. albicans with the capacity to form biofilm as compared to non-biofilm forming C. albicans.

Conclusion:

The present study highlights the prevalence of resistance to antifungal drugs among C. albicans which are not uncommon. Moreover, there was a high prevalence of INT1, ALS1, HWP1, SAP1 and PLB1 genes in C. albicans. The resistance to antifungal drugs was common among isolates with the capacity to form the biofilm. There was an association between the biofilm formation and virulence genes.

Clinical impacts of delayed central venous catheter removal according to the severity of comorbidities in patients with candidaemia

BACKGROUND

The effects of early central venous catheter (CVC) removal on the clinical outcomes of patients with candidaemia remain controversial. This study evaluated the impact of delayed CVC removal on mortality according to the severity of comorbidities in patients with candidaemia.

METHODS

Patients with candidaemia in a tertiary care hospital between January 2010 and December 2017 were included retrospectively. The severity of comorbidities was classified as low [Charlson Comorbidity Index (CCI) score ≤3] or high (CCI score ≥4). Cases with removal of CVC >2 days after the onset of candidaemia or without CVC removal were classified as having delayed CVC removal.

RESULTS

In total, 239 patients with candidaemia were included, excluding 18 who died within 2 days of onset of candidaemia. Of these, 149 had low CCI scores and 90 had high CCI scores. Septic shock [adjusted odds ratio (aOR)=9.5] and delayed CVC removal (aOR=4.7) were significantly associated with increased 30-day mortality, whereas Candida parapsilosis infection (aOR=0.2) and cerebrovascular disease (aOR=0.3) were associated with decreased 30-day mortality, in patients with low CCI scores. Septic shock (aOR=13.0) was the only risk factor for 30-day mortality in those with high CCI scores. Delayed CVC removal was associated with increased 30-day mortality in patients with low CCI scores (50.0% vs 20.3%; P=0.001), but not in those with high CCI scores (50.0% vs 47.9%; P=0.87).

CONCLUSION

Early CVC removal may improve the survival of patients with candidaemia and low CCI scores, but no such protective effect was evident in those with high CCI scores.

Chronic disseminated candidiasis manifesting as hepatosplenic abscesses among patients with hematological malignancies

BACKGROUND

The outcomes of deep-seated abscesses attributed to chronic disseminated candidiasis (CDC) in patients with hematological malignancies have rarely been reported in recent years.

METHODS

We retrospectively reviewed and analyzed the data of patients with hematological malignancies who received a diagnosis of CDC at a medical center in Taiwan between 2008 and 2013.

RESULTS

Sixty-one patients (32 men and 29 women) were diagnosed with CDC. The median age was 51 years (range: 18-83). The overall incidence of CDC was 1.53 per 100 patient-years in patients with hematological malignancies between 2008 and 2013. The highest incidence of CDC was 4.3 per 100 patient-years for acute lymphoblastic leukemia, followed by 3.6 for acute myeloid leukemia. We detected 3 (4.9%) proven, 13 (21.3%) probable, and 45 (73.8%) possible cases of CDC. A total of 13 patients had positive blood cultures for Candida species: C. tropicalis (8), C. albicans (2), C. glabrata (2), and C. famata (1). The median duration of antifungal treatment was 96 days (range: 7-796 days). Serial imaging studies revealed that the resolution rate of CDC was 30.0% at 3 months and 54.3% at 6 months. Five patients (8.2%) had residual lesions that persisted beyond one year. A multivariate analysis of the 90-day outcome revealed that shock was the only independent prognostic factor of 90-day survival in patients with CDC.

CONCLUSION

The incidence of CDC did not decrease between 2008 and 2013. Patients with acute leukemia had a higher risk of CDC than those with other hematological malignancies. Imaging studies conducted at 6 months after diagnosis revealed that only half of the patients showed complete resolution. CDC requires prolonged treatment, and serial imaging at 6 months interval is suggested. Shock is the only independent prognostic factor of 90-day survival in patients with CDC.

Histopathology

During the last 30 years, advances in intensive and critical care units, organ transplantation, concomitant use of immunosuppressive drugs, and increasing prevalence of chronic diseases, malnutrition, and other debilitating conditions, as well as the human immunodeficiency virus pandemic, have increased the incidence of systemic mycotic diseases, the most serious form of fungal diseases are the ones that comprise the central nervous system, representing the most dangerous clinical situations. In those cases, starting an adequate therapy through a rapid and assertive diagnosis is absolutely necessary. Considering the fastidious microbiological nature of some fungi (longtime requirement, specific culture conditions, and biohazard issues), as well as the lack of alternative testing availability, a rapid diagnosis is always challenging. When a tissue or liquid specimen is available, its pathological analysis constitutes a rapid and cost-effective way to provide a presumptive or definitive diagnosis of an invasive fungal infection; however, microbiologists, pathologists, and clinicians need to be aware of the limitations of microscopical diagnosis. In this chapter, we review the usual histological presentation of the most frequent central nervous system fungal infections.

Clinical predictors of candidemia in medical non-neutropenic, non-ICU patients. The CaMed score

INTRODUCTION

Candida species are the leading cause of invasive fungal infections in hospitalised patients and are the fourth most common isolates recovered from patients with bloodstream infection. Few data exist on risk factors for candidemia in non-ICU patients. We performed a population-based case-control study to evaluate the main predictors for candidemia in non-ICU patients.

METHODS AND FINDINGS

We included all non-neutropenic, non-critically ill and non-surgical adult patients with candidemia between January 2010 and June 2014. Patients with positive, non-candidal blood culture obtained at the same day (±2 days) were selected as controls. Cases and controls were matched according to hospital ward and clinical characteristics. Risk factors for candidemia were identified through a logistic regression. We included 56 candidemic and 512 bacteriemic non-candidemic patients. Most of candidemic patients (52) had received antibiotics prior to candidemia. Among them, the 30-day mortality rate was 34% (19/56). Multivariate analysis identified male sex, prior use of steroids, prior use of antibiotics, total parenteral nutrition and urinary catheterisation as independent predictors of candidemia. To develop the CaMed score, we rounded up weights of different risk factors as follows; total parenteral nutrition (+2), prior antibiotic therapy (+5), each of the other risk factors (+1). A score ≥ 7 identified patients at high risk of candidemia (P < 0.001; RR 29.805; CI 95% 10.652-83.397; sensitivity 79.2, specificity 82.6%, Youden index 0,62).

CONCLUSIONS

Our set of easy independent predictors of candidemia in non-neutropenic, non-ICU, non-surgical patients provide a rationale for early initiation of antifungals and could reduce candidemia-related mortality.

Invasive Candidiasis in Critically Ill Patients: A Prospective Cohort Study in Two Tertiary Care Centers

Background:

Invasive candidiasis is not uncommon in critically ill patients but has variable epidemiology and outcomes between intensive care units (ICUs). This study evaluated the epidemiology, characteristics, management, and outcomes of patients with invasive candidiasis at 6 ICUs of 2 tertiary care centers.

Methods:

This was a prospective observational study of all adults admitted to 6 ICUs in 2 different hospitals between August 2012 and May 2016 and diagnosed to have invasive candidiasis by 2 intensivists according to predefined criteria. The epidemiology of isolated Candida and the characteristics, management, and outcomes of affected patients were studied. Multivariable logistic regression analyses were performed to identify the predictors of non-albicans versus albicans infection and hospital mortality.

Results:

Invasive candidiasis was diagnosed in 162 (age 58.4 ± 18.9 years, 52.2% males, 82.1% medical admissions, and admission Acute Physiology and Chronic Health Evaluation II score 24.1 ± 8.4) patients at a rate of 2.6 cases per 100 ICU admissions. On the diagnosis day, the Candida score was 2.4 ± 0.9 in invasive candidiasis compared with 1.6 ± 0.9 in Candida colonization (P < .01). The most frequent species were albicans (38.3%), tropicalis (16.7%), glabrata (16%), and parapsilosis (13.6%). In patients with candidemia, antifungal therapy was started on average 1 hour before knowing the culture result (59.6% of therapy initiated after). Resistance to fluconazole, caspofungin, and amphotericin B occurred in 27.9%, 2.9%, and 3.1%, respectively. The hospital mortality was 58.6% with no difference between albicans and non-albicans infections (61.3% and 54.9%, respectively; P = .44). The independent predictors of mortality were renal replacement therapy after invasive candidiasis diagnosis (odds ratio: 5.42; 95% confidence interval: 2.16-13.56) and invasive candidiasis leading/contributing to ICU admission versus occurring during critical illness (odds ratio: 2.87; 95% confidence interval: 1.22-6.74).

Conclusions:

In critically ill patients with invasive candidiasis, non-albicans was responsible for most cases, and mortality was high (58.6%). Antifungal therapy was initiated after culture results in 60% suggesting low preclinical suspicion. Study registration: NCT01490684; registered in ClinicalTrials.gov on February 11, 2012.

The Utility of the Candida Score in Patients With Sepsis

BACKGROUND

Candida is a leading cause of infection in the intensive care unit. Colonization versus infection remains a challenge. A Candida Score (CS) of 3 or greater has been used to target antifungal therapy in surgical patients at risk of candidemia but has not been well evaluated in medical patients with sepsis.

OBJECTIVES

The aim of this study was to assess utility of the CS in detecting candidemia early in patients with sepsis.

METHODS

This was a secondary analysis of patients with sepsis (n = 77) who were followed up for development of new infections. Patients with known fungal infection at admission were excluded. Candida colonization was defined as Candida cultured from any baseline culture, except blood, as a part of routine clinical care.

RESULTS

Candidemia was detected in 8 of 77 participants (10.4%; 4 [15.4%] with a CS ≥3 and 4 [7.8%] with a CS <3). Demographic variables (age, race, sex) were similar among those who did and did not develop candidemia. Using the recommended CS of 3 or greater, sensitivity was (4/8) 50%, specificity was (47/69) 68.1%, positive predictive value was (4/26) 15.4%, and negative predictive value was (47/51) 92.2%. Baseline colonization was significantly higher among those who developed candidemia (50% vs 11.6%; P = .02), but no significant differences were observed among CS components or total scores.

CONCLUSIONS

Despite a relatively poor sensitivity, a reasonable specificity with a strong negative predictive value makes this tool a viable option for screening medically ill patients who may require antifungal agents. The CS should be evaluated in a larger, more inclusive, medical population.

Other Forms of Esophagitis: It Is Not Gastroesophageal Reflux Disease, So Now What Do I Do?

Esophagitis results from diverse causes, including gastroesophageal reflux, immune-mediated or allergic reactions, therapeutic complications, and infections. The appropriate clinical management differs in each of these situations and is often guided by pathologic interpretation of endoscopic mucosal biopsy specimens. This review summarizes the diagnostic features of unusual forms of esophagitis, including eosinophilic esophagitis, lymphocytic esophagitis, esophagitis dissecans superficialis, drug-induced esophageal injury, and bullous disorders. Differential diagnoses and distinguishing features are emphasized.

Disseminated Candidiasis in a Young, Previously Healthy, Dog and Review of Literature

Background

The reports on disseminated candidiasis in dogs so far describe at least one predisposing factor. This case report, however, highlights candidiasis in a dog without any known predisposition.

Patient

A 1.5-year-old intact female Hovawart dog was presented with subcutaneous nodules and polyuria/polydipsia. An excisional biopsy revealed a chronic pyogranulomatous and necrotizing inflammation with mycotic structures. The patient became febrile and lethargic, and developed lameness.

Methods

A physical examination, blood tests, urinalysis, thoracic radiographs, abdominal ultrasonography of the abdomen, fine-needle aspiration biopsies, and a culture of a subcutaneous nodule aspirate were obtained. Selected sections of multiple organs were collected for routine histology postmortem. The isolate and a subcutaneous mass were subjected to molecular identification and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF–MS) analysis.

Results

Clinical, laboratory, and radiological findings were consistent with a granulomatous chronic systemic inflammation. Cytology and histology showed a pyogranulomatous and necrotizing inflammation with myriads of intra- and extra-cellular yeasts and extracellular hyphae. Culture yielded numerous yeast colonies, which appeared Candida albicans–like, but showed a negative serum test and a low identification in API 20 C AUX. Nucleic acid sequences showed homology with the C. albicans-type strain CBS 562. Multilocus sequence typing (MLST) resulted in a new type with designation DST121. The identification of the isolates was confirmed by MALDI-TOF–MS analysis.

Conclusion and Clinical Importance

Future MLST typing and investigation of virulence can provide further evidence whether this MLST-type is associated with clinical cases of disseminated candidiasis without an apparent predisposing condition.

Exploring the anti-biofilm activity of cinnamic acid derivatives in Candida albicans

Some compounds, characterized by phenylethenyl moiety, such as methyl cinnamate and caffeic acid phenethyl ester, are able to inhibit C. albicans biofilm formation. On these bases, and as a consequence of our previous work, we synthesized a series of cinnamoyl ester and amide derivatives in order to evaluate them for the activity against C. albicans biofilm and planktonically grown cells. The most active compounds 7 and 8 showed ⩾50% biofilm inhibition concentrations (BMIC₅₀) of 2μg/mL and 4μg/mL respectively, against C. albicans biofilm formation; otherwise, 7 showed an interesting activity also against mature biofilm, with BMIC₅₀ of 8μg/mL.

The interplay between inflammasome activation and antifungal host defense

Fungal infections cause significant morbidity and mortality in humans, and they are a growing problem due to the increased usage of broad-spectrum antibiotics and immunosuppressive therapies. The equilibrium between the commensal microbial flora and the immune system that protects the host against invasive fungal infection is disturbed during disease, and understanding this disturbed balance is important to develop new therapeutic interventions for the treatment of fungal infection. In the context of tolerating fungi during colonization and eliciting a vigorous immune response to eliminate invading fungal pathogens when needed, the inflammasome has been identified as an integral component of antifungal host defense. It contributes to mucosal host defense by regulating T-helper 17 (Th17) cell responses, and contributes to protective responses such as neutrophil influx during fungal sepsis. Several aspects are important for understanding the role of the inflammasome for antifungal host defense, such as the role of fungal cell wall morphology and its components in triggering the inflammasome, the pattern recognition pathways and downstream signaling cascades involved in the activation of the inflammasome, and the effects of inflammasome activation during fungal infection. The future perspectives of inflammasome research in fungal immunology, with emphasis on targeting the inflammasome for the design of future immunotherapies, is also discussed.

Neutrophils influx and proinflammatory cytokines inhibition by sodium salicylate, unlike aspirin, in Candida albicans-induced peritonitis model

Sodium salicylate (NaS) and aspirin (ASA) are known to have a variety of effects on microorganisms, such as fungus (C. albicans and C. neoformans), moreover, it have effects in leukocyte adhesion and migration in vitro. In this report, we investigated the effect of ASA and NaS in neutrophil migration and cytokine production in C. albicans-induced peritonitis murine model. For this, mice were treated intraperitoneally (i.p) or orally (po) with NaS or ASA; after they were stimulated i.p. with C. albicans, the cellular migration was evaluated 24 h after stimulation. NaS, in mice treated i.p., unlike ASA, was able to inhibit the neutrophil migration and proinflammatory cytokine production induced by C. albicans, such as TNF-α, IL-1, IFN-γ, IL-12, and IL-10, but did not alter the IL-4 levels in these animals. However, the po treatment with same the dose of NaS or ASA did not affect the influx of this cell for inflammatory site. These results suggest that the NaS inhibits cellular migration and proinflammatory cytokine by different anti-inflammatory mechanism compared to ASA.

Novel strategies against Candida biofilms: interest of synthetic compounds

A biofilm is a consortium of microbial cells that are attached to a substratum or an interface. It should be considered a reservoir that may induce serious infections. Indeed, Candidaspp. biofilms may be involved in the persistence or worsening of some chronic inflammatory diseases as well as in systemic infections, which may lead to high morbidity and mortality rates. New strategies are currently being explored, utilizing several synthetic compounds to prevent or fight these Candida biofilms. This article focuses on active synthetic compounds classified with regards to their modes of action: inhibition of early adherence phase, inhibition or control of biofilm maturation and finally elimination of already formed biofilms. Some of them show promise in fighting biofilm.

Sphingolipids as Regulators of the Phagocytic Response to Fungal Infections

Fungal infections pose a significant risk for the increasing population of individuals who are immunocompromised. Phagocytes play an important role in immune defense against fungal pathogens, but the interactions between host and fungi are still not well understood. Sphingolipids have been shown to play an important role in many cell functions, including the function of phagocytes. In this review, we discuss major findings that relate to the importance of sphingolipids in macrophage and neutrophil function and the role of macrophages and neutrophils in the most common types of fungal infections, as well as studies that have linked these three concepts to show the importance of sphingolipid signaling in immune response to fungal infections.

How to treat fungal infections in ICU patients

Fungal infections represent a major burden in the critical care setting with increasing morbidity and mortality. Candidiasis is the leading cause of such infections, with C. albicans being the most common causative agent, followed by Aspergillosis and Mucormycosis. The diagnosis of such infections is cumbersome requiring increased clinical vigilance and extensive laboratory testing, including radiology, cultures, biopsies and other indirect methods. However, it is not uncommon for definitive evidence to be unavailable. Risk and host factors indicating the probability of infections may greatly help in the diagnostic approach. Timely and adequate intervention is important for their successful treatment. The available therapeutic armamentarium, although not very extensive, is effective with low resistance rates for the newer antifungal agents. However, timely and prudent use is necessary to maximize favorable outcomes.

Candida albicans morphology and dendritic cell subsets determine T helper cell differentiation

Candida albicans is a dimorphic fungus responsible for chronic mucocutaneous and systemic infections. Mucocutaneous immunity to C. albicans requires T helper 17 (Th17) cell differentiation that is thought to depend on recognition of filamentous C. albicans. Systemic immunity is considered T cell independent. Using a murine skin infection model, we compared T helper cell responses to yeast and filamentous C. albicans. We found that only yeast induced Th17 cell responses through a mechanism that required Dectin-1-mediated expression of interleukin-6 (IL-6) by Langerhans cells. Filamentous forms induced Th1 without Th17 cell responses due to the absence of Dectin-1 ligation. Notably, Th17 cell responses provided protection against cutaneous infection while Th1 cell responses provided protection against systemic infection. Thus, C. albicans morphology drives distinct T helper cell responses that provide tissue-specific protection. These findings provide insight into compartmentalization of Th cell responses and C. albicans pathogenesis and have critical implications for vaccine strategies.

A role of Candida albicans CDC4 in the negative regulation of biofilm formation

The CDC4 gene is nonessential in Candida albicans and plays a role in suppressing filamentous growth, in contrast to its homologues, which are involved in the G1-S transition of the cell cycle. While characterizing the function of C. albicans CDC4 (CaCDC4), we found that the loss of CaCDC4 resulted in a reduction in cell flocculation, indicating a possible role for CaCDC4 in biofilm formation. To elucidate the role of CaCDC4 in biofilm formation, Cacdc4 null mutant strains were constructed by using the mini-Ura-blaster method. To create a CaCDC4 rescued strain, the plasmid p6HF-ACT1p-CaCDC4 capable of constitutively expressing CaCDC4 was introduced into the Cacdc4 homozygous null mutant. To determine the biofilm formation ability, an in vitro XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium-5-carboxanilide) reduction assay was used. Compared with the parental auxotrophic strain BWP17, the Cacdc4 homozygous null mutant was able to enhance biofilm formation significantly. This enhancement of biofilm formation in the Cacdc4 homozygous null mutant could be reversed by constitutively expressing CaCDC4. We conclude that CaCDC4 has a role in suppressing biofilm formation in C. albicans.

Protection from systemic Candida albicans infection by inactivation of the Sts phosphatases

The human fungal pathogen Candida albicans causes invasive candidiasis, characterized by fatal organ failure due to disseminated fungal growth and inflammatory damage. The suppressor of TCR signaling 1 (Sts-1) and Sts-2 are two homologous phosphatases that negatively regulate signaling pathways in a number of hematopoietic cell lineages, including T lymphocytes, mast cells, and platelets. Functional inactivation of both Sts enzymes leads to profound resistance to systemic infection by C. albicans, such that greater than 80% of mice lacking Sts-1 and -2 survive a dose of C. albicans (2.5 × 10(5) CFU/mouse) that is uniformly lethal to wild-type mice within 10 days. Restriction of fungal growth within the kidney occurs by 24 h postinfection in the mutant mice. This occurs without induction of a hyperinflammatory response, as evidenced by the decreased presence of leukocytes and inflammatory cytokines that normally accompany the antifungal immune response. Instead, the absence of the Sts phosphatases leads to the rapid induction of a unique immunological environment within the kidney, as indicated by the early induction of a proinflammatory cytokine (CXL10). Mice lacking either Sts enzyme individually display an intermediate lethality phenotype. These observations identify an opportunity to optimize host immune responses toward a deadly fungal pathogen.

Platelet immunology in fungal infections

Up to date, perception of platelets has changed from key players in coagulation to multitaskers within the immune network, connecting its most diverse elements and crucially shaping their interplay with invading pathogens such as fungi. In addition, antimicrobial effector molecules and mechanisms in platelets enable a direct inhibitory effect on fungi, thus completing their immune capacity. To precisely assess the impact of platelets on the course of invasive fungal infections is complicated by some critical parameters. First, there is a fragile balance between protective antimicrobial effects and detrimental reactions that aggravate the fungal pathogenesis. Second, some platelet effects are exerted indirectly by other immune mediators and are thus difficult to quantify. Third, drugs such as antimycotics, antibiotics, or cytostatics, are commonly administered to the patients and might modulate the interplay between platelets and fungi. Our article highlights selected aspects of the complex interactions between platelets and fungi and the relevance of these processes for the pathogenesis of fungal infections.

Candida colonization index and subsequent infection in critically ill surgical patients: 20 years later

Introduction

For decades, clinicians dealing with immunocompromised and critically ill patients have perceived a link between Candida colonization and subsequent infection. However, the pathophysiological progression from colonization to infection was clearly established only through the formal description of the colonization index (CI) in critically ill patients. Unfortunately, the literature reflects intense confusion about the pathophysiology of invasive candidiasis and specific associated risk factors.

Methods

We review the contribution of the CI in the field of Candida infection and its development in the 20 years following its original description in 1994. The development of the CI enabled an improved understanding of the pathogenesis of invasive candidiasis and the use of targeted empirical antifungal therapy in subgroups of patients at increased risk for infection.

Results

The recognition of specific characteristics among underlying conditions, such as neutropenia, solid organ transplantation, and surgical and nonsurgical critical illness, has enabled the description of distinct epidemiological patterns in the development of invasive candidiasis.

Conclusions

Despite its limited bedside practicality and before confirmation of potentially more accurate predictors, such as specific biomarkers, the CI remains an important way to characterize the dynamics of colonization, which increases early in patients who develop invasive candidiasis.

Distinct roles of Candida albicans-specific genes in host-pathogen interactions

Human fungal pathogens are distributed throughout their kingdom, suggesting that pathogenic potential evolved independently. Candida albicans is the most virulent member of the CUG clade of yeasts and a common cause of both superficial and invasive infections. We therefore hypothesized that C. albicans possesses distinct pathogenicity mechanisms. In silico genome subtraction and comparative transcriptional analysis identified a total of 65 C. albicans-specific genes (ASGs) expressed during infection. Phenotypic characterization of six ASG-null mutants demonstrated that these genes are dispensable for in vitro growth but play defined roles in host-pathogen interactions. Based on these analyses, we investigated two ASGs in greater detail. An orf19.6688Δ mutant was found to be fully virulent in a mouse model of disseminated candidiasis and to induce higher levels of the proinflammatory cytokine interleukin-1β (IL-1β) following incubation with murine macrophages. A pga16Δ mutant, on the other hand, exhibited attenuated virulence. Moreover, we provide evidence that secondary filamentation events (multiple hyphae emerging from a mother cell and hyphal branching) contribute to pathogenicity: PGA16 deletion did not influence primary hypha formation or extension following contact with epithelial cells; however, multiple hyphae and hyphal branching were strongly reduced. Significantly, these hyphae failed to damage host cells as effectively as the multiple hypha structures formed by wild-type C. albicans cells. Together, our data show that species-specific genes of a eukaryotic pathogen can play important roles in pathogenicity.

Maleylated-BSA suppresses lipopolysaccharide-induced IL-6 production by activating the ERK-signaling pathway in murine RAW264.7 cells

Macrophages are well known for their ability to induce diverse beneficial immune responses, especially in the defense against pathogens. However, an excessive activation of macrophages may cause harmful inflammation. In this context, the suppression of excessive macrophage activation would be a promising therapeutic strategy for treating inflammatory diseases. We have previously found that maleylated-bovine serum albumin (maleylated-BSA) suppresses the production of inflammatory mediators in murine macrophages. However, the immunosuppressive effects and underlying mechanism(s) of maleylated-BSA remain unclear. Here, we report that pretreatment with maleylated-BSA strongly inhibited the production of interleukin 6 (IL-6) induced by bacterial lipopolysaccharide (LPS) in murine RAW264.7 cells. This inhibitory effect of maleylated-BSA on LPS-induced IL-6 production was eliminated by treatment with an extracellular signal-regulated kinase (ERK) inhibitor, U0126, indicating the involvement of ERK pathways. Taken together, we have shown that maleylated-BSA suppresses LPS-induced production of IL-6 via the activation of an ERK signaling pathway in murine macrophages. The findings of this study imply the possibility of a novel therapeutic strategy for inflammatory diseases.

NDV-3 protects mice from vulvovaginal candidiasis through T- and B-cell immune response

We have previously reported that vaccination with rAls3p-N protein of Candida albicans, formulated with alum adjuvant (also designated as NDV-3) protects immunocompetent mice from, lethal disseminated candidiasis and mucosal oropharyngeal candidiasis. NDV-3 vaccine was recently, tested in a Phase 1 clinical trial and found to be safe, well-tolerated, and induced robust humoral and, cellular immune responses with increased interferon (IFN)-gamma and interleukin (IL)-17 secretion. In preparation for a Phase 2 clinical trial against vulvovaginal candidiasis (VVC), we evaluated NDV-3, efficacy in a murine VVC model. Here, NDV-3 induced a strong immune response characterized by high, anti-rAls3p-N serum IgG and vaginal IgA titers. Furthermore, moderate doses of the vaccine (a range of 1-30μg given subcutaneously [SQ] or 0.3-10μg given intramuscularly [IM]) elicited a 10-1000 fold, decrease in vaginal fungal burden vs. control (mice injected with alum adjuvant alone) in both inbred, and outbred mice infected with different clinical C. albicans isolates. Additionally, NDV-3 required both, T and B lymphocytes for efficacy in reducing C. albicans tissue burden, which is followed by a reduction, in neutrophil influx to the affected site. Finally, anti-rAls3p-N antibodies enhanced the ex vivo killing, of C. albicans by neutrophils primed with IFN-gamma. These data indicate that NDV-3 protects mice, from VVC by a mechanism that involves the concerted priming of both humoral and adaptive immune, responses.

Cryptococcus gattii induces a cytokine pattern that is distinct from other cryptococcal species

Understanding more about the host's immune response to different Cryptococcus spp. will provide additional insight into the pathogenesis of cryptocococcis. We hypothesized that the ability of C. gattii to cause disease in immunocompetent humans depends on a distinct innate cytokine response of the host to this emerging pathogen. In the current study we assessed the cytokine profile of human peripheral blood mononuclear cells (PBMCs) of healthy individuals, after in vitro stimulation with 40 different well-defined heat-killed isolates of C. gattii, C. neoformans and several hybrid strains. In addition, we investigated the involvement of TLR2, TLR4 and TLR9 in the pro-inflammatory cytokine response to C. gattii. Isolates of C. gattii induced higher concentrations of the pro-inflammatory cytokines IL-1β, TNF-α and IL-6 and the Th17/22 cytokine IL-17 and IL-22 compared to C. neoformans var neoformans and C. neoformans var grubii. In addition, clinical C. gattii isolates induced higher amounts of cytokines than environmental isolates. This difference was not observed in C. neoformans var. grubii isolates. Furthermore, we demonstrated a likely contribution of TLR4 and TLR9, but no role for TLR2, in the host's cytokine response to C. gattii. In conclusion, clinical heat-killed C. gattii isolates induced a more pronounced inflammatory response compared to other Cryptococcus species and non-clinical C. gattii. This is dependent on TLR4 and TLR9 as cellular receptors.

Deletion of vacuolar proton-translocating ATPase V(o)a isoforms clarifies the role of vacuolar pH as a determinant of virulence-associated traits in Candida albicans

Vacuolar proton-translocating ATPase (V-ATPase) is a central regulator of cellular pH homeostasis, and inactivation of all V-ATPase function has been shown to prevent infectivity in Candida albicans. V-ATPase subunit a of the Vo domain (Voa) is present as two fungal isoforms: Stv1p (Golgi) and Vph1p (vacuole). To delineate the individual contribution of Stv1p and Vph1p to C. albicans physiology, we created stv1Δ/Δ and vph1Δ/Δ mutants and compared them to the corresponding reintegrant strains (stv1Δ/ΔR and vph1Δ/ΔR). V-ATPase activity, vacuolar physiology, and in vitro virulence-related phenotypes were unaffected in the stv1Δ/Δ mutant. The vph1Δ/Δ mutant exhibited defective V1Vo assembly and a 90% reduction in concanamycin A-sensitive ATPase activity and proton transport in purified vacuolar membranes, suggesting that the Vph1p isoform is essential for vacuolar V-ATPase activity in C. albicans. The vph1Δ/Δ cells also had abnormal endocytosis and vacuolar morphology and an alkalinized vacuolar lumen (pHvph1Δ/Δ = 6.8 versus pHvph1Δ/ΔR = 5.8) in both yeast cells and hyphae. Secreted protease and lipase activities were significantly reduced, and M199-induced filamentation was impaired in the vph1Δ/Δ mutant. However, the vph1Δ/Δ cells remained competent for filamentation induced by Spider media and YPD, 10% FCS, and biofilm formation and macrophage killing were unaffected in vitro. These studies suggest that different virulence mechanisms differentially rely on acidified vacuoles and that the loss of both vacuolar (Vph1p) and non-vacuolar (Stv1p) V-ATPase activity is necessary to affect in vitro virulence-related phenotypes. As a determinant of C. albicans pathogenesis, vacuolar pH alone may prove less critical than originally assumed.

Oral nystatin prophylaxis in surgical/trauma ICU patients: a randomised clinical trial

Introduction

Candida prophylaxis in ICU is still a matter of debate. Oral chemoprophylaxis has been advocated to reduce the incidence of Candida colonisation and infection.

Methods

We performed a randomised trial studying a single drug (nystatin) versus control in surgical/trauma ICU patients. Multiple-site testing for fungi was performed in each patient on ICU admission (T0) and subsequently every 3 days (T3, T6, T9, and so forth). The primary evaluation criterion was the time course of the corrected colonisation index.

Results

Ninety-nine patients were enrolled. At admission, 69 patients exhibited Candida colonisation: the most frequently colonised body sites were the stomach and the pharynx. The most frequent isolated species was Candida albicans. The corrected colonisation index was similar in the two groups at T0 (P = 0.36), while a significant statistical difference was observed between the treatment and control groups at T6 (median 0.14 and 0.33, respectively; P = 0.0016), at T9 (median 0.00 and 0.28, respectively; P = 0.0001), at T12 (median 0.00 and 0.41, respectively; P = 0.0008), and at T15 (median 0.00 and 0.42, respectively; P <0.0003). The same results were obtained in the subgroup of patients already colonised at ICU admission.

Conclusion

This trial shows that nystatin prophylaxis significantly reduces fungal colonisation in surgical/trauma ICU patients, even if already colonised.

Trial registration

ClinicalTrials.gov: NCT01495039

Antagonistic effect of Candida albicans and IFNγ on E-cadherin expression and production by human primary gingival epithelial cells

Caused mainly by Candida albicans, oropharyngeal candidiasis is the most common oral complication associated with HIV disease worldwide. Host defenses against C. albicans essentially fall into two categories: specific immune mechanisms and local oral mucosal epithelial cell defenses. Since oral mucosa is the first line of defense in the form of a physical barrier against C. albicans invasion, and since epithelial cells are involved in anti-Candida innate immunity through different cytokines, we wanted to determine whether C. albicans alters E-cadherin expression and production, and whether interferon-γ (INFγ), a TH1 cytokine, is involved in the anti-Candida defense. Using primary human gingival epithelial cells, we demonstrated that C. albicans significantly decreased E-cadherin mRNA expression and protein production. This effect was basically obtained at later infective periods (24 and 48h). Interestingly, when IFNγ was added to C. albicans infected epithelial cell cultures, it prevented the side effect of C. albicans on E-cadherin mRNA expression and protein production and deposition. All together, these results suggested concomitant interactions between oral epithelial cells and IFNγ against C. albicans infection.

Urea amidolyase (DUR1,2) contributes to virulence and kidney pathogenesis of Candida albicans

The intracellular enzyme urea amidolyase (Dur1,2p) enables C. albicans to utilize urea as a sole nitrogen source. Because deletion of the DUR1,2 gene reduces survival of C. albicans co-cultured with a murine macrophage cell line, we investigated the role of Dur1,2p in pathogenesis using a mouse model of disseminated candidiasis. A dur1,2Δ/dur1,2Δ strain was significantly less virulent than the wild-type strain, showing significantly higher survival rate, better renal function, and decreased and less sustained fungal colonization in kidney and brain. Complementation of the mutant restored virulence. DUR1,2 deletion resulted in a milder host inflammatory reaction. Immunohistochemistry, flow cytometry, and magnetic resonance imaging showed decreased phagocytic infiltration into infected kidneys. Systemic cytokine levels of wild-type mice infected with the dur1,2 mutant showed a more balanced systemic pro-inflammatory cytokine response. Host gene expression and protein analysis in infected kidneys revealed parallel changes in the local immune response. Significant differences were observed in the kidney IL-1 inflammatory pathway, IL-15 signaling, MAP kinase signaling, and the alternative complement pathway. We conclude that Dur1,2p is important for kidney colonization during disseminated candidiasis and contributes to an unbalanced host inflammatory response and subsequent renal failure. Therefore, this Candida-specific enzyme may represent a useful drug target to protect the host from kidney damage associated with disseminated candidiasis.

New features of invasive candidiasis in humans: amyloid formation by fungi and deposition of serum amyloid P component by the host

BACKGROUND

Invasive candidiasis occurs in the gastrointestinal tract, especially in neutropenic patients. We were interested in determining whether invasive fungi formed amyloid in humans as they are known to do in vitro. We also sought to characterize the consequence(s) of such amyloid formation.

METHODS

Tissue from 25 autopsy patients with invasive candidiasis of the gastrointestinal tract was stained with amyloidophilic dyes and for the presence of serum amyloid P component (SAP). Confirmation of the interaction of SAP and Candida was demonstrated using Candida albicans and mutants for amyloid formation.

RESULTS

Amyloid was present on the cellular surface of fungi invading gut tissue. Moreover, SAP bound to the fungal cell walls, confirming the presence of amyloid. In vitro observations showed SAP bound avidly to fungi when amyloid formed in fungal cell walls. An unexpected result was the lack of host neutrophils in response to the invading fungi, not only in neutropenic patients but also in patients with normal or increased white blood counts.

CONCLUSIONS

We report the first demonstration of functional fungal amyloid in human tissue and the binding of SAP to invading fungi. It is postulated that fungal amyloid, SAP, or a complex of the proteins may inhibit the neutrophil response.

Macrophage autophagy in immunity to Cryptococcus neoformans and Candida albicans

Autophagy is used by eukaryotes in bulk cellular material recycling and in immunity to intracellular pathogens. We evaluated the role of macrophage autophagy in the response to Cryptococcus neoformans and Candida albicans, two important opportunistic fungal pathogens. The autophagosome marker LC3 (microtubule-associated protein 1 light chain 3 alpha) was present in most macrophage vacuoles containing C. albicans. In contrast, LC3 was found in only a few vacuoles containing C. neoformans previously opsonized with antibody but never after complement-mediated phagocytosis. Disruption of host autophagy in vitro by RNA interference against ATG5 (autophagy-related 5) decreased the phagocytosis of C. albicans and the fungistatic activity of J774.16 macrophage-like cells against both fungi, independent of the opsonin used. ATG5-knockout bone marrow-derived macrophages (BMMs) also had decreased fungistatic activity against C. neoformans when activated. In contrast, nonactivated ATG5-knockout BMMs actually restricted C. neoformans growth more efficiently, suggesting that macrophage autophagy plays different roles against C. neoformans, depending on the macrophage type and activation. Interference with autophagy in J774.16 cells also decreased nonlytic exocytosis of C. neoformans, increased interleukin-6 secretion, and decreased gamma interferon-induced protein 10 secretion. Mice with a conditionally knocked out ATG5 gene in myeloid cells showed increased susceptibility to intravenous C. albicans infection. In contrast, these mice manifested no increased susceptibility to C. neoformans, as measured by survival, but had fewer alternatively activated macrophages and less inflammation in the lungs after intratracheal infection than control mice. These results demonstrate the complex roles of macrophage autophagy in restricting intracellular parasitism by fungi and reveal connections with nonlytic exocytosis, humoral immunity, and cytokine signaling.