Immunology of Cryptococcal Infections: Developing a Rational Approach to Patient Therapy

Cryptococcosis

Cryptococcosis is an invasive fungal infection caused by yeasts of the genus Cryptococcus that causes a significant global burden of disease in both immunocompromised and immunocompetent individuals. Over the past several decades, diagnosis and management of cryptococcal disease have moved to focus on rapid, reliable, and cost-effective care delivery, with the advent of new antigen detection assays and novel antifungal treatment strategies.

A spectrum of neurological diseases with elevated cerebrospinal fluid adenosine deaminase levels

OBJECTIVES

This study aimed to investigate cerebrospinal fluid (CSF) adenosine deaminase (ADA) levels in various neurological disorders and examine the relationships between CSF ADA levels and immunological parameters.

METHODS

Overall, 276 patients whose CSF ADA levels were measured for suspected tuberculous meningitis (TBM) were evaluated. Data on baseline characteristics, final diagnoses, CSF ADA levels, and other laboratory parameters were collected. Thereafter, CSF ADA levels were compared based on final diagnoses, and correlations between CSF ADA levels and other CSF and blood laboratory parameters were evaluated.

RESULTS

Five diseases exhibited a significant increase in CSF ADA levels relative to the noninflammatory disease control group (n = 40): (1) TBM (n = 15, p < 0.0001), (2) fungal meningitis (n = 7, p = 0.0400), (3) autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A, n = 7, p < 0.0001), (4) neurosarcoidosis (n = 7, p = 0.0028), and (5) lymphoproliferative disorders (n = 18, p = 0.0001). Strong positive correlations were observed between CSF ADA and CSF parameters, including soluble IL2 receptor (rs = 0.7566, p < 0.0001), albumin (rs = 0.6693, p < 0.0001), lactate dehydrogenase (rs = 0.6452, p < 0.0001), white blood cell count (rs = 0.6035, p < 0.0001), protein (rs = 0.6334, p < 0.0001), and lymphocytes (rs = 0.5954, p < 0.0001).

DISCUSSION

CSF ADA levels were elevated in various inflammatory neurological diseases, especially in TBM, fungal meningitis, GFAP-A, neurosarcoidosis, and lymphoproliferative disorders. CSF ADA levels may reflect T-cell hyperactivation in the central nervous system.

Lactate dehydrogenase-1 may play a key role in the brain energy disturbance caused by cryptococcal meningitis

BACKGROUND

Cryptococcal meningitis (CM) may affect the conversion of lactate to pyruvate in the brain, resulting in abnormal levels of adenosine triphosphate (ATP) throughout the brain. Lactate conversion to pyruvate is mainly caused by lactic dehydrogenase 1 (LDH1), which is composed of four LDHB subunits. However, the underlying mechanism of LDH1 in CM remains unclear.

METHODS

Cerebrospinal fluid (CSF) from 17 patients was collected, including eight patients with non-infectious diseases of the central nervous system and nine patients with CM. Based on clinical data and laboratory reports, data regarding intracranial pressure, CSF white cell counts, lactate dehydrogenase (LDH), adenosine deaminase, glucose, protein, and chloridion were collected. Meanwhile, LDH1, LDH5, lactate, pyruvate, and ATP levels were detected in CSF. Whereafter, the levels of lactate, pyruvate, ATP, and the amplitude and frequency of action potentials in the neurons with low expression of LDHB were explored.

RESULTS

Intracranial pressure and white cell count in CSF were significantly increased in patients with CM. In patients with CM, the LDH1, pyruvate, and ATP levels in the CSF were significantly decreased, and the levels of lactate were found to be increased. Furthermore, pyruvate and ATP levels were decreased, while lactate was increased in the neurons with low expression of LDHB. The amplitude and frequency of APs in the neurons with low expression of LDHB were significantly decreased.

CONCLUSION

Reduced levels of LDH1 in the brain of patients with CM may lead to increased lactate levels, decreased pyruvate and ATP levels, and negatively affect neuronal activity.

Eosinophils as modulators of host defense during parasitic, fungal, bacterial, and viral infections

Eosinophils, traditionally associated as central innate effector cells with type 2 immunity during allergic and helminth parasitic diseases, have recently been revealed to have important roles in tissue homeostasis as well as host defense in a broader variety of infectious diseases. In a dedicated session at the 2023 biennial conference of the International Eosinophil Society titled "Eosinophils in Host Defense," the multifaceted roles eosinophils play against diverse pathogens, ranging from parasites to fungi, bacteria, and viruses, were presented. In this review, the session speakers offer a comprehensive summary of recent discoveries across pathogen classes, positioning eosinophils as pivotal leukocytes in both host defense and pathology. By unraveling the intricacies of eosinophil engagement in host resistance, this exploration may provide valuable insights not only to understand specific underpinnings of eosinophil functions related to each class of pathogens but also to develop novel therapeutics effective against a broad spectrum of infectious diseases.

State of the Field: Cytotoxic Immune Cell Responses in C. neoformans and C. deneoformans Infection

Cryptococcus neoformans is an environmental pathogen that causes life-threatening disease in immunocompromised persons. The majority of immunological studies have centered on CD4+ T-cell dysfunction and associated cytokine signaling pathways, optimization of phagocytic cell function against fungal cells, and identification of robust antigens for vaccine development. However, a growing body of literature exists regarding cytotoxic cells, specifically CD8+ T-cells, Natural Killer cells, gamma/delta T-cells, NK T-cells, and Cytotoxic CD4+ T-cells, and their role in the innate and adaptive immune response during C. neoformans and C. deneoformans infection. In this review, we (1) provide a comprehensive report of data gathered from mouse and human studies on cytotoxic cell function and phenotype, (2) discuss harmonious and conflicting results on cellular responses in mice models and human infection, (3) identify gaps of knowledge in the field ripe for exploration, and (4) highlight how innovative immunological tools could enhance the study of cytotoxic cells and their potential immunomodulation during cryptococcosis.

Cerebrospinal Fluid Lactate Levels as a Prognostic Indicator in Patients With Cryptococcal Meningitis Who Are HIV Negative: A Retrospective Cohort Study

Background

Cryptococcal meningitis (CM) is a severe central nervous system infection. In patients with HIV infections and coexisting CM, elevated baseline cerebrospinal fluid (CSF) lactate levels can predict increased mortality. However, the CSF lactate level's significance in patients with CM who are HIV negative remains unclear, necessitating further investigation to elucidate the potential distinctions and enhance patient management. This study investigated the significance of CSF lactate levels in patients with CM who were HIV negative.

Methods

This retrospective study utilized data from the clinical databases of patients who underwent lumbar punctures at a medical center in Kaohsiung City, southern Taiwan. Demographic data, CSF lactate levels, routine CSF analyses, and hematologic and neurologic findings were evaluated. The optimal CSF lactate threshold value was determined by the Youden index.

Results

This retrospective study included 70 patients with CM, among whom 44 (63%) and 26 (37%) tested negative and positive for HIV, respectively. The group without HIV exhibited higher CSF lactate levels, with an optimal CSF lactate cutoff point of 7.935 mmol/L for predicting 90-day mortality, resulting in significant predictive accuracies (area under the curve, 0.755; sensitivity, 57.1%; specificity, 100%); this value was an independent mortality predictor in patients who were HIV negative. In patients with CM who were HIV negative, CSF lactate levels ≥7.935 mmol/L correlated with higher mortality rates but without statistical significance. All patients with CM who were HIV negative and had CSF lactate levels ≥7.935 mmol/L died within 3 months of admission.

Conclusions

Patients with CM who were HIV negative had elevated CSF lactate levels that correlated with adverse outcomes, enabling early identification of high-risk individuals.

Clinical Characteristics and Risk Factors for Cryptococcal Meningitis in Diverse Patient Populations in New York City

Background

Cryptococcal meningitis (CM) is responsible for 15%-20% of human immunodeficiency virus (HIV)-associated mortalities. CM prevalence has also increased in other immunocompromised populations of transplant recipients, patients with cancer, and individuals on immunomodulatory medication.

Methods

This retrospective review included 51 definitive patients with CM hospitalized at a tertiary academic medical center in New York City between 2010 and 2023. We assessed clinical features and outcomes of CM, with additional analysis of factors related to antiretroviral therapy (ART) adherence in HIV-infected cases and immunomodulatory medication history of HIV-negative cases.

Results

The cohort had a mean (standard deviation) age of 47.1 ± 15.1 years, and was predominantly male (37, 72.5%). Of 32 patients with HIV, 3 (9.4%) were newly diagnosed with HIV at the time of CM hospitalization, 5 (15.6%) had recurrent CM, and 2 (6.3%) had a CM relapse. The majority (30, 93.8%) of patients with HIV were ART nonadherent. Of 19 HIV-negative patients, 8 (42.1%) were solid-organ transplant recipients, 5 (26.3%) had autoimmune conditions of sarcoidosis or systemic lupus erythematosus, and 3 (15.8%) had chronic lymphocytic leukemia. Six (11.8%) patients died during hospitalization, 4 of whom had HIV.

Conclusions

The burden of CM in people with HIV and immunocompromised patients continues even in settings with accessible standard antifungal treatment though interventions of increased ART adherence for those with HIV and antifungal prophylaxis may improve morbidity and mortality.

The emerging links between immunosenescence in innate immune system and neurocryptococcosis

Immunosenescence refers to the age-related progressive decline of immune function contributing to the increased susceptibility to infectious diseases in older people. Neurocryptococcosis, an infectious disease of central nervous system (CNS) caused by Cryptococcus neoformans (C. Neoformans) and C. gattii, has been observed with increased frequency in aged people, as result of the reactivation of a latent infection or community acquisition. These opportunistic microorganisms belonging to kingdom of fungi are capable of surviving and replicating within macrophages. Typically, cryptococcus is expelled by vomocytosis, a non-lytic expulsive mechanism also promoted by interferon (IFN)-I, or by cell lysis. However, whereas in a first phase cryptococcal vomocytosis leads to a latent asymptomatic infection confined to the lung, an enhancement in vomocytosis, promoted by IFN-I overproduction, can be deleterious, leading the fungus to reach the blood stream and invade the CNS. Cryptococcus may not be easy to diagnose in older individuals and, if not timely treated, could be potentially lethal. Therefore, this review aims to elucidate the putative causes of the increased incidence of cryptococcal CNS infection in older people discussing in depth the mechanisms of immunosenscence potentially able to predispose to neurocryptococcosis, laying the foundations for future research. A deepest understanding of this relationship could provide new ways to improve the prevention and recognition of neurocryptococcosis in aged frail people, in order to quickly manage pharmacological interventions and to adopt further preventive measures able to reduce the main risk factors.

Cryptococcosis Associated With Biologic Therapy: A Narrative Review

Cryptococcus is an opportunistic fungal pathogen that can cause disseminated infection with predominant central nervous system involvement in patients with compromised immunity. Biologics are increasingly used in the treatment of neoplasms and autoimmune/inflammatory conditions and the prevention of transplant rejection, which may affect human defense mechanisms against cryptococcosis. In this review, we comprehensively investigate the association between cryptococcosis and various biologics, highlighting their risks of infection, clinical manifestations, and clinical outcomes. Clinicians should remain vigilant for the risk of cryptococcosis in patients receiving biologics that affect the Th1/macrophage activation pathways, such as tumor necrosis factor α antagonists, Bruton tyrosine kinase inhibitors, fingolimod, JAK/STAT inhibitors (Janus kinase/signal transducer and activator of transcription), and monoclonal antibody against CD52. Other risk factors-such as age, underlying condition, and concurrent immunosuppressants, especially corticosteroids-should also be taken into account during risk stratification.

Protection against experimental cryptococcosis elicited by Cationic Adjuvant Formulation 01-adjuvanted subunit vaccines

The fungal infection, cryptococcosis, is responsible for >100,000 deaths annually. No licensed vaccines are available. We explored the efficacy and immune responses of subunit cryptococcal vaccines adjuvanted with Cationic Adjuvant Formulation 01 (CAF01). CAF01 promotes humoral and T helper (Th) 1 and Th17 immune responses and has been safely used in human vaccine trials. Four subcutaneous vaccines, each containing single recombinant Cryptococcus neoformans protein antigens, partially protected mice from experimental cryptococcosis. Protection increased, up to 100%, in mice that received bivalent and quadrivalent vaccine formulations. Vaccinated mice that received a pulmonary challenge with C. neoformans had an influx of leukocytes into the lung including robust numbers of polyfunctional CD4+ T cells which produced interferon gamma (IFNγ), tumor necrosis factor alpha (TNFα), and interleukin (IL)-17 upon ex vivo antigenic stimulation. Cytokine-producing lung CD8+ T cells were also found, albeit in lesser numbers. A significant, durable IFNγ response was observed in the lungs, spleen, and blood. Moreover, IFNγ secretion following ex vivo stimulation directly correlated with fungal control in the lungs. Thus, we have developed multivalent cryptococcal vaccines which protect mice from experimental cryptococcosis using an adjuvant which has been safely tested in humans. These preclinical studies suggest a path towards human cryptococcal vaccine trials.

A Retrospective Analysis of Central and Peripheral Metabolic Characteristics in Patients with Cryptococcal Meningitis

INTRODUCTION

Most current treatment strategies and investigations on cryptococcal meningitis (CM) focus primarily on the central nervous system (CNS), often overlooking the complex interplay between the CNS and the peripheral system. This study aims to explore the characteristics of central and peripheral metabolism in patients with CM.

METHODS

Patients diagnosed with CM as per the hospital records of the Fourth People's Hospital of Nanning were retrospectively analyzed. Patients were divided into two groups, non-structural damage of the brain (NSDB) and structural damage of the brain (SDB), according to the presence of brain lesions as detected with imaging. Based on the presence of enlarged cerebral ventricles, the cases in the SDB group were classified into non-ventriculomegaly (NVM) and ventriculomegaly (VM). Various parameters of cerebrospinal fluid (CSF) and peripheral blood (PB) were analyzed.

RESULTS

A significant correlation was detected between CSF and PB parameters. The levels of CSF-adenosine dehydrogenase (ADA), CSF-protein, CSF-glucose, and CSF-chloride ions were significantly correlated with the levels of PB-aminotransferase, PB-bilirubin, PB-creatinine (Cr), PB-urea nitrogen, PB-electrolyte, PB-protein, and PB-lipid. Compared with NSDB, the levels of CSF-glucose were significantly decreased in the SDB group, while the levels of CSF-lactate dehydrogenase (LDH) and CSF-protein were significantly increased in the SDB group. In the SDB group, the levels of PB-potassium, PB-hemoglobin(Hb), and PB-albumin were significantly decreased in the patients with VM, while the level of PB-urea nitrogen was significantly increased in these patients.

CONCLUSION

Metabolic and structural alterations in the brain may be associated with peripheral metabolic changes.

Protection against experimental cryptococcosis elicited by Cationic Adjuvant Formulation 01-adjuvanted subunit vaccines

The fungal infection, cryptococcosis, is responsible for >100,000 deaths annually. No licensed vaccines are available. We explored the efficacy and immune responses of subunit cryptococcal vaccines adjuvanted with Cationic Adjuvant Formulation 01 (CAF01). CAF01 promotes humoral and T helper (Th) 1 and Th17 immune responses and has been safely used in human vaccine trials. Four subcutaneous vaccines, each containing single recombinant Cryptococcus neoformans protein antigens, partially protected mice from experimental cryptococcosis. Protection increased, up to 100%, in mice that received bivalent and quadrivalent vaccine formulations. Vaccinated mice that received a pulmonary challenge with C. neoformans had an influx of leukocytes into the lung including robust numbers of polyfunctional CD4+ T cells which produced Interferon gamma (IFNγ), tumor necrosis factor alpha (TNFα), and interleukin (IL)-17 upon ex vivo antigenic stimulation. Cytokine-producing lung CD8+ T cells were also found, albeit in lesser numbers. A significant, durable IFNγ response was observed in the lungs, spleen, and blood. Moreover, IFNγ secretion following ex vivo stimulation directly correlated with fungal clearance in the lungs. Thus, we have developed multivalent cryptococcal vaccines which protect mice from experimental cryptococcosis using an adjuvant which has been safely tested in humans. These preclinical studies suggest a path towards human cryptococcal vaccine trials.

Preclinical Models for Cryptococcosis of the CNS and Their Characterization Using In Vivo Imaging Techniques

Infections caused by Cryptococcus neoformans and Cryptococcus gattii remain a challenge to our healthcare systems as they are still difficult to treat. In order to improve treatment success, in particular for infections that have disseminated to the central nervous system, a better understanding of the disease is needed, addressing questions like how it evolves from a pulmonary to a brain disease and how novel treatment approaches can be developed and validated. This requires not only clinical research and research on the microorganisms in a laboratory environment but also preclinical models in order to study cryptococci in the host. We provide an overview of available preclinical models, with particular emphasis on models of cryptococcosis in rodents. In order to further improve the characterization of rodent models, in particular the dynamic aspects of disease manifestation, development, and ultimate treatment, preclinical in vivo imaging methods are increasingly used, mainly in research for oncological, neurological, and cardiac diseases. In vivo imaging applications for fungal infections are rather sparse. A second aspect of this review is how research on models of cryptococcosis can benefit from in vivo imaging methods that not only provide information on morphology and tissue structure but also on function, metabolism, and cellular properties in a non-invasive way.

Vaccine Strategies for Cryptococcus neoformans

Cryptococcus neoformans infections are a major worldwide concern as current treatment strategies are becoming less effective in alleviating the infection. The most extreme and fatal cases are those of immunocompromised individuals. Clinical treatments for cryptococcosis are limited to a few classes of approved drugs, and due to a rise in drug resistance, these drugs are becoming less effective. Therefore, it is essential to develop innovative ways to control this infection. Vaccinations have emerged as a safe, viable, and cost-effective solution to treat a number of diseases over the years. Currently, there are no clinically available vaccines to treat cryptococcal infections, but a number of studies have shown promising results in animal models. Here, we present step-by-step experimental protocols using live-attenuated or heat-killed C. neoformans cells as a vaccination strategy in a preventive or in a therapeutic murine model of cryptococcosis.

Antibody Isolation in C. neoformans

The importance of humoral immunity to fungal infections remains to be elucidated. In cryptococcosis, patients that fail to generate antibodies against antigens of the fungus Cryptococcus neoformans are more susceptible to the disease, demonstrating the importance of these molecules to the antifungal immune response. Historically, antibodies against C. neoformans have been applied in diagnosis, therapeutics, and as important research tools to elucidate fungal biology. Throughout the process of generating monoclonal antibodies (mAbs) from a single B-cell clone and targeting a single epitope, several immunization steps might be required for the detection of responsive antibodies to the antigen of interest in the serum. This complex mixture of antibodies comprises the polyclonal antibodies. To obtain mAbs, B-lymphocytes are harvested (from spleen or peripheral blood) and fused with tumor myeloma cells, to generate hybridomas that are individually cloned and specifically screened for mAb production. In this chapter, we describe all the necessary steps, from the immunization to polyclonal antibody harvesting, hybridoma generation, and mAb production and purification. Additionally, we discuss new cutting-edge approaches for generating interspecies mAbs, such as humanized mAbs, or for similar species in distinct host backgrounds.

Divergent neuroimmune signatures in the cerebrospinal fluid predict differential gender-specific survival among patients with HIV-associated cryptococcal meningitis

Introduction

Survival among people with HIV-associated cryptococcal meningitis (CM) remains low, particularly among women, despite the currently optimal use of antifungal drugs. Cryptococcus dissemination into the central nervous system [brain, spinal cord, and cerebrospinal fluid (CSF)] elicits the local production of cytokines, chemokines, and other biomarkers. However, no consistent diagnostic or prognostic neuroimmune signature is reported to underpin the risk of death or to identify mechanisms to improve treatment and survival. We hypothesized that distinct neuroimmune signatures in the CSF would distinguish survivors from people who died on antifungal treatment and who may benefit from tailored therapy.

Methods

We considered baseline clinical features, CSF cryptococcal fungal burden, and CSF neuroimmune signatures with survival at 18 weeks among 419 consenting adults by "gender" (168 women and 251 men by biological sex defined at birth).

Results

Survival at 18 weeks was significantly lower among women than among men {47% vs. 59%, respectively; hazard ratio (HR) = 1.4 [95% confidence interval (CI), 1.0 to 1.9; p = 0.023]}. Unsupervised principal component analysis (PCA) demonstrated divergent neuroimmune signatures by gender, survival, and intragender-specific survival. Overall, women had lower levels of programmed death ligand 1, Interleukin (IL) (IL-11RA/IL-1F30, and IL-15 (IL-15) than men (all p < 0.028). Female survivors compared with those who died expressed significant elevations in levels of CCL11 and CXCL10 chemokines (both p = 0.001), as well as increased T helper 1, regulatory, and T helper 17 cytokines (all p < 0.041). In contrast, male survivors expressed lower levels of IL-15 and IL-8 compared with men who died (p < 0.044).

Conclusions

Survivors of both genders demonstrated a significant increase in the levels of immune regulatory IL-10. In conclusion, the lower survival among women with CM was accompanied by distinct differential gender-specific neuroimmune signatures. These female and male intragender-specific survival-associated neuroimmune signatures provide potential targets for interventions to advance therapy to improve the low survival among people with HIV-associated CM.

GXMR-CAR containing distinct GXM-specific single-chain variable fragment (scFv) mediated the cell activation against Cryptococcus spp. And had difference in the strength of tonic signaling

Cryptococcus spp. has a polysaccharide capsule composed of glucuronoxylomannan-GXM, a major virulence factor that can prevent the recognition of fungi by immune cells. Chimeric Antigen Receptor (CAR) redirects T cells to target Cryptococcus spp. as previously demonstrated by a CAR specific to GXM, GXMR-CAR. The current study evaluated the strength of the signal transduction triggered by GXMR-CAR, composed of a distinct antigen-binding domain sourced from a single-chain variable fragment (scFv). GXM-specific scFv derived from mAbs 2H1 and 18B7, 2H1-GXMR-CAR and 18B7-GXMR-CAR, respectively, were designed to express CD8 molecule as hinge/transmembrane, and the costimulatory molecule CD137 (4-1BB) coupled to CD3ζ. The 2H1-GXMR-CAR or 18B7-GXMR-CAR Jurkat cells recognized soluble GXM from C. gattii and C. neoformans, and the levels of IL-2 released by the modified cells did not differ between the GXMR-CAR constructs after exposure to Cryptococcus spp. 18B7-GXMR-CAR triggered tonic signaling was more pronounced in modified Jurkat cells, and a protein kinase inhibitor of the Src family (dasatinib) significantly reduced GXMR-CAR tonic signaling and inhibited cell activation against ligands. 18B7 scFv showed a structural modification of the variable heavy (VH) chain that clarified the difference in the strength of tonic signaling and the level of cell activation between 2H1-GXMR-CAR and 18B7-GXMR-CAR. GXMR-CAR constructs induced T-cell activation against clinical isolates of Cryptococcus spp. and serum from patients with cryptococcosis induced high levels of IL-2, mainly in cells modified with 18B7-GXMR-CAR. Thus, 18B7-GXMR-CAR and 2H1-GXMR-CAR mediated T cell activation against Cryptococcus spp. and 18B7 and 2H1 scFv influenced the strength of tonic signaling.

Disseminated Cryptococcus neoformans presenting with an isolated pleural effusion in a patient receiving temozolomide and long-term steroids

Cryptococcus neoformans is a ubiquitous environmental organism found worldwide. Infection with this organism occurs predominantly in immunocompromised hosts, including persons living with HIV or those with impaired cellular immunity. Cryptococcal pleural effusions have been described in cases with extensive pulmonary involvement. Here we present the case of a woman receiving temozolomide and steroids for glioblastoma multiforme, who developed cough and dyspnoea and was found to have an uncomplicated pleural effusion. Pleural fluid culture grew Cryptococcus neoformans with negative culture on bronchoalveolar lavage. High serum cryptococcal antigen titre of 1:64 prompted lumbar puncture which demonstrated positive cerebrospinal fluid for Cryptococcus neoformans She was treated with liposomal amphotericin B and flucytosine, followed by consolidation and maintenance therapy with fluconazole. Pleural involvement in the absence of pulmonary involvement has rarely been reported. We review pulmonary and radiographic manifestations of cryptococcal infection, when to assess for disseminated infection, and management principles.

Inbred SJL mice recapitulate human resistance to Cryptococcus infection due to differential immune activation

IMPORTANCE

Cryptococcosis studies often utilize the common C57BL/6J mouse model. Unfortunately, infection in these mice fails to replicate the basic course of human disease, particularly hampering immunological studies. This work demonstrates that SJL/J mice can recapitulate human infection better than other mouse strains. The immunological response to Cryptococcus infection in SJL/J mice was markedly different from C57BL/6J and much more productive in combating this infection. Characterization of infected mice demonstrated strain-specific genetic linkage and differential regulation of multiple important immune-relevant genes in response to Cryptococcus infection. While our results validate many of the previously identified immunological features of cryptococcosis, we also demonstrate limitations from previous mouse models as they may be less translatable to human disease. We concluded that SJL/J mice more faithfully recapitulate human cryptococcosis serving as an exciting new animal model for immunological and genetic studies.

Cryptococcal Meningoencephalitis in Phenotypically Normal Patients

Cryptococcosis is an invasive fungal infection found worldwide that causes significant morbidity and mortality among a broad range of hosts. There are approximately 223,000 new cases of cryptococcosis annually throughout the world, and at least 180,000 deaths are attributed to this infection each year. Most of these are due to complications of cryptococcal meningoencephalitis among HIV-infected patients in resource-limited environments. The majority of individuals diagnosed with cryptococcosis have underlying conditions associated with immune dysfunction such as HIV, solid organ transplant, hematologic malignancy, organ failure syndromes, and/or the use of immunosuppressive agents such as glucocorticosteroids and biologic agents. In most clinical series, there is a small proportion of patients with cryptococcosis who are phenotypically normal; that is, they have no clinically obvious predisposition to disease. Cryptococcal meningoencephalitis (CME) presentation and management differ substantially between these normal individuals and their immunocompromised counterparts. In this review, we will focus on CME in the phenotypically normal host and underscore differences in the clinical presentation, management, outcome, and potential risk factors for these patients compared to immunocompromised persons who develop this potential devastating invasive fungal infection.

BIOMOLECULAR ACTIVITY OF CRYPTOCOCCUS DURING CRYPTOCOCCOSIS: A REVIEW OF MOLECULAR INTERACTIONS OF CRYPTOCOCCUS WITH HUMAN IMMUNE SYSTEM AND BLOOD-BRAIN-BARRIER

Global mycosis is still a problem. One of these is the cryptococcal disease. A systemic mycosis brought on by Cryptococcus is called cryptococcosis. Host immunological conditions influence infection with Cryptococcosis. When environmental spores are inhaled by the host, the spores get to the lungs, an infection is created. Alveolar macrophages and other immune cells recognize Cryptococcus in the lung. The initial line of defense against pathogens in the phagolysosome is provided by alveolar macrophages found in the lungs. When the immune system is weak, Cryptococcus uses the evasion system as a molecular interaction with the immune system and persists in the lungs without causing any symptoms such as Factor Transcription, Cell masking, N-glycan structure, Extracellular molecule, and Antioxidant system. The evasion mechanism protects and makes Cryptococcus disseminate throughout the other organs, especially CNS. If Cryptococcus escapes against the host immune system, it will disseminate to other organs, especially Cerebrospinal System by Three mechanisms. There are Trojan Horse, Paracellular, and Transcellular interactions with Blood-Brain Barrier. Disease severity is determined by the Interaction between the host's immune system and the fungus.

Naphthylthiazoles: a class of broad-spectrum antifungals

Cryptococcal infections remain a major cause of mortality worldwide due to the ability of Cryptococci to pass through the blood-brain barrier (BBB) causing lethal meningitis. The limited number of available therapeutics, which exhibit limited availability, severe toxicity and low tolerability, necessitates the development of new therapeutics. Investigating the antifungal activity of a novel series of naphthylthiazoles provided trans-diaminocyclohexyl derivative 18 with many advantageous attributes as a potential therapeutic for cryptococcal meningitis. Briefly, the antimycotic activity of 18 against cryptococcal strains was highly comparable to that of amphotericin-B and fluconazole with MIC values as low as 1 μg mL-1. Moreover, compound 18 possessed additional advantages over fluconazole; it significantly reduced the intracellular burden of Cryptococci and markedly inhibited cryptococcal biofilm formation. Initial PK assessment of 18 indicated its ability to reach the CNS after oral administration with high permeability, and it maintained therapeutic plasma concentrations for 18 h. Its antifungal activity extended to other clinically relevant strains, such as fluconazole-resistant C. auris.

A severe case of disseminated cryptococcosis in a young French bulldog living in South-East Queensland caused by Cryptococcus gattii VGII

BACKGROUND

Cryptococcus is one of the most common systemic mycosis worldwide, infecting young adults of the large to giant breed dogs. Infection is commonly acquired from the environment via the sinonasal cavity as the main portal of entry. It either remains there, or spreads to the central nervous system (CNS) and the eye (optic nerve and retina) by penetration of the cribriform plate, or haematogenously to other viscera. Lung involvement is uncommon in cats and dogs in contrast to human and equine patients. Whilst there is a wide genetic diversity amongst Cryptococcus neoformans and Cryptococcus gattii isolates along the West Coast and Northern parts of Australia, the molecular diversity of C. gatti is considered very low on the East Coast of Australia, with a huge preponderance of VGI cases. We report on a young small breed brachycephalic dog that presented with extreme gastrointestinal and respiratory signs, but no CNS involvement. It is the first reported case of C. gattii VGII genotype in a companion animal from Queensland.

CASE REPORT

A 9-month old female entire French Bulldog presented initially for diarrhoea. Clinical progression was accompanied by the development of respiratory signs, so the patient was referred to a 24 h care facility. Following hospitalisation, the patient became hypoxemic requiring mechanical ventilation. A bronchoalveolar lavage performed antemortem confirmed abundant Cryptococcal spp. Further culturing and genotyping identified the species as Cryptococcus gattii VGII. Post-mortem findings indicated gross gastrointestinal and mesenteric involvement, with possible dissemination to the local mesenteric lymph node and lungs.

CONCLUSION

This case describes a rare example of a Cryptococcus spp suspected of disseminating from the gastrointestinal tract to the lungs, without involvement of the CNS. The observation of this finding in a small brachycephalic breed is unusual, and the finding of genotype VGII on the East Coast of Queensland is extremely unusual as there is no prior travel history of the dog or owners. The presence of a miliary lung pattern with primary gastrointestinal disease in a small breed dog warrants adding cryptococcosis to the differential diagnosis.

Detrimental impact of the IL-33/ST2 axis in an animal infection model with Cryptococcus neoformans

Cryptococcus neoformans and Cryptococcus gattii are pathogenic fungi that infect the human respiratory system and cause life-threatening pulmonary cryptococcosis. The immunopathology of cryptococcosis is completely different from that of other fungal allergies. In murine cryptococcal infection models, cryptococcal cells are usually injected via nasal or intratracheal routes. After the infection, the alveolar epithelial cells are impaired and release IL-33, an IL-1 family cytokine that functions as an alarmin. This cytokine detrimentally amplifies allergic responses, and also induces a protective immune response against parasitic infection. In the pulmonary cryptococcosis model, type-II alveolar epithelial cells are the major source of IL-33, and the alveolar epithelial cells, ILC2, and Th2 cells express the IL-33 receptor (ST2). In IL-33- or ST2-deficient mice, allergy-like immune responses are attenuated after the C. neoformans infection. The numbers of ILC2 and Th2 cells and the levels of type 2 cytokines, including IL-4, IL-5, and IL-13, are decreased in the mouse lungs in both models. In association with these changes, total blood IgE, bronchus mucus production, and the number of eosinophils are decreased. Conversely, lung neutrophils and M1-type macrophages are increased. These are protective immune subsets suppressing cryptococcal growth. As a result, the lung fungal burden of IL-33- and ST2-deficient mice is decreased post-infection, and both deficient mice show significantly improved mortality. This pathogenesis varies depending on the cryptococcal and murine strains used in the animal experiments. Here, we overview and discuss the itmmunopathology of the IL-33/ST2 axis in a murine lethal cryptococcal infection model.

Immunoadsorption-Based HLA Desensitization in Patients Awaiting Deceased Donor Kidney Transplantation: An Interventional, Non-Randomised, Single Cohort Study

Whether immunoadsorption (IADS) as part of desensitization protocols could facilitate deceased donor kidney transplantation (KT) in highly sensitized (HS) patients remains to be proven. We retrospectively analyzed our IADS based desensitization protocol for deceased donor KTs between 2013 and 2018. Fifteen HS patients (age 52 years [40-56]) were included. Waiting time before IADS was 6 years [5-10] and the interval between IADS initiation and KT was 5 months [1-12] for the 14 transplanted patients. Nine patients had prior KT. Calculated panel reactive antibody decreased significantly during the protocol (99.3% [92.5-99.9] vs. 79.4% [56.7-81.9]; p = 0.004). Death-censored graft survival was 85.7% at 1 and 2 years post-transplantation. One-year median plasma creatinine level was 135 µmol/L [111-202]. Six developed active antibody mediated rejection (ABMR) at 1 year, with a median delay of 13 days [11-26]. Eight patients developed severe infections, including two fatal outcomes. Finally, compared to 93% of patients who received desensitization receiving a KT, only 43% of a control with similar characteristics underwent transplantation. However, no difference was found in overall probability of being alive with a functioning graft at the end of follow-up. The results indicate that our IADS-based desensitization strategy was not effective due to a high rate of ABMR and severe infectious complications which pose a challenge to its universalization.

Divergent Neuroimmune Signatures in the Cerebrospinal Fluid Predict Differential Gender-Specific Survival Among Patients With HIV-Associated Cryptococcal Meningitis

Survival among people with HIV-associated cryptococcal meningitis (CM) remains low, exceptionally among women with the increased threat of death on current optimal use of antifungal drugs. Cryptococcus dissemination into the central nervous system (CNS) prompts a neuroimmune reaction to activate pathogen concomitant factors. However, no consistent diagnostic or prognostic immune-mediated signature is reported to underpin the risk of death or mechanism to improve treatment or survival. We theorized that the distinct neuroimmune cytokine or chemokine signatures in the cerebrospinal fluid (CSF), distinguish survivors from people who died on antifungal treatment, who may benefit from tailored therapy. We considered the baseline clinical disease features, cryptococcal microbiologic factors, and CSF neuroimmune modulated signatures among 419 consenting adults by gender (biological sex assigned at birth) (168 females and 251 males) by 18 weeks of survival on antifungal management. Survival at 18 weeks was inferior among females than males (47% vs. 59%; hazard ratio HR=1.4, 95% CI: 1.0 to 1.9, and p=0.023). Unsupervised principal component analysis (PCA) demonstrated the divergent neuroimmune signatures by gender, survival, and intragender-specific survival. Overall, females displayed lower levels of PD-L1, IL-1RA, and IL-15 than males (all p≤0.028). Female survivors compared with those who died, expressed significant fold elevations in levels of CSF (CCL11 - myeloid and CXCL10 - lymphoid chemokine (in both p=0.001), and CSF Th1, Th2, and Th17 cytokines. In contrast, male survivors expressed distinctly lower levels of CSF IL-15 and IL-8 compared with those who died. Survivors of either gender demonstrated a significant increase in the levels of immune regulatory element, IL-10. In the finale, we classified divergent neuroimmune key signatures in CSF by gender, survival, and intragender-specific survival among people with HIV-associated cryptococcal meningitis. These intragender-specific survival associated-neuroimmune signatures, suggests the discrete role of gender immune regulating mechanisms as the possible targets for interventions to advance therapy to improve survival among people with HIV-associated cryptococcal meningitis.

TheiaEuk: a species-agnostic bioinformatics workflow for fungal genomic characterization

Introduction

The clinical incidence of antimicrobial-resistant fungal infections has dramatically increased in recent years. Certain fungal pathogens colonize various body cavities, leading to life-threatening bloodstream infections. However, the identification and characterization of fungal isolates in laboratories remain a significant diagnostic challenge in medicine and public health. Whole-genome sequencing provides an unbiased and uniform identification pipeline for fungal pathogens but most bioinformatic analysis pipelines focus on prokaryotic species. To this end, TheiaEuk_Illumina_PE_PHB (TheiaEuk) was designed to focus on genomic analysis specialized to fungal pathogens.

Methods

TheiaEuk was designed using containerized components and written in the workflow description language (WDL) to facilitate deployment on the cloud-based open bioinformatics platform Terra. This species-agnostic workflow enables the analysis of fungal genomes without requiring coding, thereby reducing the entry barrier for laboratory scientists. To demonstrate the usefulness of this pipeline, an ongoing outbreak of C. auris in southern Nevada was investigated. We performed whole-genome sequence analysis of 752 new C. auris isolates from this outbreak. Furthermore, TheiaEuk was utilized to observe the accumulation of mutations in the FKS1 gene over the course of the outbreak, highlighting the utility of TheiaEuk as a monitor of emerging public health threats when combined with whole-genome sequencing surveillance of fungal pathogens.

Results

A primary result of this work is a curated fungal database containing 5,667 unique genomes representing 245 species. TheiaEuk also incorporates taxon-specific submodules for specific species, including clade-typing for Candida auris (C. auris). In addition, for several fungal species, it performs dynamic reference genome selection and variant calling, reporting mutations found in genes currently associated with antifungal resistance (FKS1, ERG11, FUR1). Using genome assemblies from the ATCC Mycology collection, the taxonomic identification module used by TheiaEuk correctly assigned genomes to the species level in 126/135 (93.3%) instances and to the genus level in 131/135 (97%) of instances, and provided zero false calls. Application of TheiaEuk to actual specimens obtained in the course of work at a local public health laboratory resulted in 13/15 (86.7%) correct calls at the species level, with 2/15 called at the genus level. It made zero incorrect calls. TheiaEuk accurately assessed clade type of Candida auris in 297/302 (98.3%) of instances.

Discussion

TheiaEuk demonstrated effectiveness in identifying fungal species from whole genome sequence. It further showed accuracy in both clade-typing of C. auris and in the identification of mutations known to associate with drug resistance in that organism.

Efficacy and safety of lenalidomide in HIV-associated cryptococcal meningitis patients with persistent intracranial inflammation: an open-label, single-arm, prospective interventional study

BACKGROUND

Patients with human immunodeficiency virus-associated cryptococcal meningitis (HIV-CM) have persistent intracranial inflammation despite negative cerebrospinal fluid (CSF) fungal cultures after optimal treatment for CM, which could be devastating for the central nervous system. However, a definitive treatment strategy for persistent intracranial inflammation despite optimal antifungal therapies is undefined.

METHODS

We identified 14 HIV-CM patients with persistent intracranial inflammation and conducted a 24-week, prospective, interventional study. All participants received lenalidomide (25 mg, p.o.) on days 1 to 21 of a 28-day cycle. Follow-up lasted for 24 weeks with visits at baseline and weeks 4, 8, 12, and 24. The primary endpoint was the change in clinical manifestations, routine CSF parameters, and MRI findings after lenalidomide treatment. An exploratory analysis was made on changes in cytokine levels in CSF. Safety and efficacy analyses were undertaken in patients who received at least one dose of lenalidomide.

RESULTS

Of 14 participants, 11 patients completed the 24 weeks of follow-up. Rapid clinical remission following lenalidomide therapy was observed. Clinical manifestations (fever, headache, altered mentation) were reversed fully by week-4 and remained stable during follow-up. A significant reduction in white blood cell (WBC) count in CSF was noted occurred at week-4 (P = 0.009). The median protein concentration in CSF decreased from 1.4 (0.7-3.2) g/L at baseline to 0.9 (0.6-1.4) at week-4 (P = 0.004). The median albumin concentration in CSF decreased from 79.2 (48.4-149.8) mg/L at baseline to 55.3 (38.3-89.0) mg/L at week-4 (P = 0.011). The WBC count, protein level, and albumin level in CSF remained stable and approached a normal range through week-24. There was no significant change in immunoglobulin-G, intracranial pressure (ICP), or chloride-ion concentration at each visit. Brain MRI demonstrated multiple lesions to be absorbed post-therapy. Levels of tumor necrosis factor-α granulocyte colony stimulating factor, interleukin (IL)-6, and IL-17A decreased significantly during 24-week follow-up. Two (14.3%) patients had mild skin rash, which resolved spontaneously. Lenalidomide-related serious adverse events were not observed.

CONCLUSION

Lenalidomide could improve persistent intracranial inflammation in HIV-CM patients significantly and was well tolerated without serious adverse events observed. And the additional randomized controlled study is required to further validate the finding.

Immunological correlates of protection following vaccination with glucan particles containing Cryptococcus neoformans chitin deacetylases

Vaccination with glucan particles (GP) containing the Cryptococcus neoformans chitin deacetylases Cda1 and Cda2 protect mice against experimental cryptococcosis. Here, immunological correlates of vaccine-mediated protection were explored. Studies comparing knockout and wild-type mice demonstrated CD4⁺ T cells are crucial, while B cells and CD8⁺ T cells are dispensable. Protection was abolished following CD4⁺ T cell depletion during either vaccination or infection but was retained if CD4⁺ T cells were only partially depleted. Vaccination elicited systemic and durable antigen-specific immune responses in peripheral blood mononuclear cells (PBMCs), spleens, and lungs. Following vaccination and fungal challenge, robust T-helper (Th) 1 and Th17 responses were observed in the lungs. Protection was abrogated in mice congenitally deficient in interferon (IFN) γ, IFNγ receptor, interleukin (IL)-1β, IL-6, or IL-23. Thus, CD4⁺ T cells and specific proinflammatory cytokines are required for GP-vaccine-mediated protection. Importantly, retention of protection in the setting of partial CD4⁺ T depletion suggests a pathway for vaccinating at-risk immunocompromised individuals.

Emerging and re-emerging fungal threats in Africa

The emergence of deadly fungal infections in Africa is primarily driven by a disproportionately high burden of human immunodeficiency virus (HIV) infections, lack of access to quality health care, and the unavailability of effective antifungal drugs. Immunocompromised people in Africa are therefore at high risk of infection from opportunistic fungal pathogens such as Cryptococcus neoformans and Pneumocystis jirovecii, which are associated with high morbidity, mortality, and related socioeconomic impacts. Other emerging fungal threats include Emergomyces spp., Histoplasma spp., Blastomyces spp., and healthcare-associated multi-drug resistant Candida auris. Socioeconomic development and the Covid-19 pandemic may influence shifts in epidemiology of invasive fungal diseases on the continent. This review discusses the epidemiology, clinical manifestations, and current management strategies available for these emerging fungal diseases in Africa. We also discuss gaps in knowledge, policy, and research to inform future efforts at managing these fungal threats.

Adjuvant Pam3CSk4 does not improve the immunization against Cryptococcus gattii infection in C57BL/6 mice

Background

Cryptococcosis is a relevant invasive fungal infection that affects immunocompromised and immunocompetent individuals when caused by Cryptococcus gattii. Host innate and adaptive immune responses can be subverted by C. gattii, that blocks the differentiation of T helper (Th) 1 and Th17 cells, which are involved in the protection against cryptococcosis. Moreover, the macrophage polarization is modulated by C. gattii infection that requires a balance in the macrophage subsets to control the C. gattii infection. Toll-like receptor (TLR) 2 agonists are important immunomodulators favoring a pro-inflammatory response with potential fungicidal activity, and TLR2 agonists have been used as adjuvants in vaccines against infections caused by bacteria or viruses. Therefore, this work aimed to evaluate the immunomodulatory effect of the tripalmitoyl lipopeptide S-glycerol cysteine (Pam3CSK4 or P3C4), a TLR2 agonist, as an adjuvant in the vaccination against C. gattii infection.

Methods and Results

C57BL/6 mice were immunized with 2 × 10⁷ inactivated yeasts of C. gattii via intranasal route on day 1, 14 and 28 (Immunized group). Immunization was associated with 1µg or 10µg of adjuvant P3C4 (Immunized+P3C4-1µg or Immunized+P3C4-10 µg), followed by C. gattii infection on day 42 after the immunization protocol. Immunized+P3C4-1 µg group had reduced levels of IgG1, IgG2a and IgA and no significant difference in the IgG and IgM anti-GXM antibody titer was detected, compared to the Immunized group. High levels of IL-17 and IL-1β in lung tissue of mice from the Immunized+P3C4-1µg group did not promote a predominance of Th17 cells, in contrast, the frequency of TLR2⁺ cells was increased in immunized mice that received 1 µg of P3C4. The reduction in the relative expression of T-bet and high levels of Foxp3 detected in the lungs of the Immunized+P3C4-1µg group suggest a prevalence of regulatory T cells in the tissue, which did not contribute to the control of C. gattii infection. The immunization protocol associated with 10 µg of adjuvant P3C4 induced high levels of IL-17 in the lung tissue, whereas the levels of pro-inflammatory cytokines were downregulated. To evaluate the effect of adjuvant P3C4 in the control of C. gattii infection, quantification of the fungal burden in the lungs was performed by the CFU assay, and the groups with adjuvant P3C4 showed a pulmonary C. gattii burden that was not significantly altered when compared with the immunized group. The mice that received 1 µg of adjuvant P3C4 had a lower percentage of inflammatory infiltrate in the lungs.

Conclusion

The immunomodulatory effect of P3C4, associated with the immunization protocol, plays an imbalance between pro- and anti-inflammatory response in the lungs that did not favor a protection against C. gattii infection, which is related to the immune response characterized by a suppressive/regulatory profile in the pulmonary microenvironment after C. gattii infection.

What's New in Cryptococcus gattii: From Bench to Bedside and Beyond

Cryptococcus species are a major cause of life-threatening infections in immunocompromised and immunocompetent hosts. While most disease is caused by Cryptococcus neoformans, Cryptococcus gattii, a genotypically and phenotypically distinct species, is responsible for 11-33% of global cases of cryptococcosis. Despite best treatment, C. gattii infections are associated with early mortality rates of 10-25%. The World Health Organization's recently released Fungal Priority Pathogen List classified C. gattii as a medium-priority pathogen due to the lack of effective therapies and robust clinical and epidemiological data. This narrative review summarizes the latest research on the taxonomy, epidemiology, pathogenesis, laboratory testing, and management of C. gattii infections.

Modification of Hinge/Transmembrane and Signal Transduction Domains Improves the Expression and Signaling Threshold of GXMR-CAR Specific to Cryptococcus spp

Chimeric antigen receptors (CARs) redirect T cells to recognize a specific target. CAR components play a pivotal role in antigen specificity, structure stability, expression on cell surface, and induction of cellular activation, which together determine the success of CAR T-cell therapy. CAR products targeting B-cell lymphoma encouraged the development of new CAR applications beyond cancer. For example, our group developed a CAR to specifically target glucuronoxylomannan (GXM) in the capsule of Cryptococcus species, called GXMR-CAR or GXMR-IgG4-28ζ. Cryptococcus are fungi that cause the life-threatening disease cryptococcosis, and GXMR-IgG4-28ζ redirected T cells to target yeast and titan cell forms of Cryptococcus spp. Here, we replaced the IgG4-hinge and CD28-transmembrane domains from GXMR-CAR with a CD8α molecule as the hinge/transmembrane and used CD28 or 4-1BB molecules as co-stimulatory domains, creating GXMR-8-28ζ and GXMR-8-BBζ, respectively. Jurkat cells expressing GXMR-CAR containing CD8α as the hinge/transmembrane improved the CAR expression and induced a tonic signaling. GXMR-8-28ζ and GXMR-8-BBζ induced high levels of IL-2 and up-regulation of CD69 expression in the presence of reference strains of C. neoformans and C. gattii. Moreover, GXMR-8-28ζ and GXMR-8-BBζ showed increased strength in response to incubation with clinical isolates of Cryptococcuss spp., and 4-1BB co-stimulatory domain triggered a more pronounced cellular activation. Dasatinib, a tyrosine kinase inhibitor, attenuated the GXMR-CAR signaling cascade's engagement in the presence or absence of its ligand. This study optimized novel second-generation GXMR-CARs containing the CD8-hinge/transmembrane domain that improved CAR expression, antigen recognition, and signal strength in T-cell activation.

Cryptococcus escapes host immunity: What do we know?

Cryptococcus is an invasive fungus that seriously endangers human life and health, with a complex and well-established immune-escaping mechanism that interferes with the function of the host immune system. Cryptococcus can attenuate the host’s correct recognition of the fungal antigen and escape the immune response mediated by host phagocytes, innate lymphoid cells, T lymphocytes, B lymphocytes with antibodies, and peripheral cytokines. In addition, the capsule, melanin, dormancy, Titan cells, biofilm, and other related structures of Cryptococcus are also involved in the process of escaping the host’s immunity, as well as enhancing the ability of Cryptococcus to infect the host.

Immunological Predictors of Post Infectious Inflammatory Response Syndrome in HIV-Negative Immunocompetent Cryptococcal Meningitis

Objective

This research aims to study the correlation between serum immune factors and post-infectious inflammatory response syndrome (PIIRS) in immunocompetent cryptococcal meningitis (CM), and explore whether serum immune factors could be used to predict the development of PIIRS.

Methods

A cohort of 30 patients with PIIRS and 87 patients without PIIRS was selected from 347 CM patients. We analyzed the general clinical information and immunological indexes (cytokines, complement, immunoglobulin, inflammation, related cytological and biochemical indexes). Spearman correlation analysis and principal component analysis were used to explore the effects of the variables on PIIRS. Additionally, the variables were identified by a random forest-based classifier for predicting the development of PIIRS. The clinical value of predictors was verified by survival analysis.

Results

Compared with patients without PIIRS, patients with PIIRS had lower baseline serum interleukin-6 (IL-6, P = 0.006), immunoglobulin M (IgM, P = 0.004), and a higher baseline neutrophil ratio (P <0.001). The baseline neutrophil ratio (r = 0.359, P = 0.001), IgM (r = −0.272, P = 0.025), and IL-6 (r = −0.259, P = 0.027) were significantly correlated with PIIRS. Combining principal component analysis and random forest results, neutrophil ratio, neutrophil count, IgM, IL-6, and D-dimer were useful predictors. The accuracy of random forest prediction was 75.00%, AUC, and sensitivity were 0.76 and 70%, respectively. Further survival analysis of the time from treatment to PIIRS revealed that the development of PIIRS was associated with IgM (more than 98 days of treatment) and neutrophil ratio/count.

Conclusion

Baseline neutrophils ratio, neutrophil count, IgM, IL-6, and D-dimer may be clinically useful predictors of PIIRS in HIV-negative immunocompetent CM patients.

Synergistic combination of duloxetine hydrochloride and fluconazole reduces the cell growth and capsule size of Cryptococcus neoformans

This study aimed to evaluate the effect of duloxetine hydrochloride (DH) on Cryptococcus neoformans. DH minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were 18.5 µg/mL, and the combination with fluconazole (FLZ) reduced the MIC value by 16-and 4-fold for DH and FLZ, respectively. The capsule size decreased by 67% ​​and 16% when treated with DH and DH with FLZ, respectively. Therefore, this study showed that DH is active against C. neoformans alone and in combination with FLZ, leading to the reduction of the capsule size of this yeast.

Three Models of Vaccination Strategies Against Cryptococcosis in Immunocompromised Hosts Using Heat-Killed Cryptococcus neoformans Δsgl1

Vaccines are one of the greatest medical accomplishments to date, yet no fungal vaccines are currently available in humans mainly because opportunistic mycoses generally occur during immunodeficiencies necessary for vaccine protection. In previous studies, a live, attenuated Cryptococcus neoformans Δsgl1 mutant accumulating sterylglucosides was found to be avirulent and protected mice from a subsequent lethal infection even in absence of CD4⁺ T cells, a condition most associated with cryptococcosis (e.g., HIV). Here, we tested three strategies of vaccination against cryptococcosis. First, in our preventative model, protection was achieved even after a 3-fold increase of the vaccination window. Second, because live C. neoformans Δsgl1-vaccinated mice challenged more than once with WT strain had a significant decrease in lung fungal burden, we tested C. neoformans Δsgl1 as an immunotherapeutic. We found that therapeutic administrations of HK C. neoformans Δsgl1 post WT challenge significantly improves the lung fungal burden. Similarly, therapeutic administration of HK C. neoformans Δsgl1 post WT challenge resulted in 100% or 70% survival depending on the time of vaccine administration, suggesting that HK Δsgl1 is a robust immunotherapeutic option. Third, we investigated a novel model of vaccination in preventing reactivation from lung granuloma using C. neoformans Δgcs1. Remarkably, we show that administration of HK Δsgl1 prevents mice from reactivating Δgcs1 upon inducing immunosuppression with corticosteroids or by depleting CD4⁺ T cells. Our results suggest that HK Δsgl1 represents a clinically relevant, efficacious vaccine that confers robust host protection in three models of vaccination against cryptococcosis even during CD4-deficiency.

Lenalidomide Improves Cognitive Function and Reduces Immune Reconstitution Inflammatory Syndrome in HIV-1-Related Cryptococcal Meningitis

Cryptococcal meningitis (CM) is a common opportunistic infection in patients with acquired immune deficiency syndrome. Although there is a standardized treatment for CM, some patients still have CM-associated immune reconstitution inflammatory syndrome (IRIS) after anti-cryptococcal and antiretroviral therapy, which manifests as cognitive impairment. We report two cases of CM-associated IRIS in human immunodeficiency virus (HIV) patients that were treated with lenalidomide. The treatment yielded a rapid clinical remission and improved cognitive function in both patients; their Montreal Cognitive Assessment (MoCA) and International HIV Dementia Scale (IHDS) scores improved. Furthermore, we evaluated changes in 32 cytokines in the cerebrospinal fluid of two patients and found that both MoCA and IHDS were significantly negatively correlated with inflammation-related factors (growth-related oncogene, interleukin [IL]-10, IL-2, IL-8, macrophage inflammatory protein-1β, tumor necrosis factor [TNF]-α) and significantly positively correlated with dementia-related factors (αβ42 and total tau). Our study reveals the potential of lenalidomide in treating cognitive impairment caused by immune-mediated inflammation in patients with HIV-CM. Moreover, we speculate that lenalidomide improves cognitive function by regulating intracranial inflammation via multiple pathways, not only by TNF-α blocking.

Fungal infections: Pathogenesis, antifungals and alternate treatment approaches

Increasing incidence of fungal infections of recent times requires immediate intervention. Fungal infections are seldom construed at initial stages that intensify the severity of infections and complicate the treatment procedures. Fungal pathogens employ various mechanisms to evade the host immune system and to progress the severity of infections. For the treatment of diverse superficial and systemic infections, antifungal drugs from the available repertoire are administered. However, well documented evidence of fungal resistance to most of the antifungal drugs hampers disease control and poses challenges in antifungal therapy. Several physiological adaptations and genetic mutations followed by their selection in presence of antifungal agents drive the resistance development in fungi. The availability of limited antifungal arsenal, emergence of resistance and biofilm-conferred resistance drives the need for development of novel drugs and alternate approaches for the better treatment outcome against mycoses. This graphical review explicitly shed light on various fungal infections and causative organisms, pathogenesis, different antifungal drugs and resistance mechanisms including host immune response and evasion strategies. Here, we have highlighted recent developments on novel antifungal agents and other alternate approaches for fighting against fungal infections.

Missed opportunities to identify cryptococcosis in COVID-19 patients: a case report and literature review

SARS-CoV-2 may activate both innate and adaptive immune responses ultimately leading to a dysregulated immune response prompting the use of immunomodulatory therapy. Although viral pneumonia increases the risk of invasive fungal infections, it remains unclear whether SARS-CoV-2 infection, immunomodulatory therapy, or a combination of both are responsible for the increased recognition of opportunistic infections in COVID-19 patients. Cases of cryptococcosis have previously been reported following treatment with corticosteroids, interleukin (IL)-6 inhibitors, and Janus kinase (JAK) inhibitors, for patients with autoimmune diseases, but their effect on the immunologic response in patients with COVID-19 remains unknown. Herein, we present the case of a patient with COVID-19 who received high-dose corticosteroids and was later found to have cryptococcosis despite no traditional risk factors. As our case and previous cases of cryptococcosis in patients with COVID-19 demonstrate, clinicians must be suspicious of cryptococcosis in COVID-19 patients who clinically deteriorate following treatment with immunomodulatory therapies.

Cryptococcosis in a patient with multiple myeloma receiving pomalidomide: a case report and literature review

While overall survival with multiple myeloma (MM) has improved, patients suffer from overwhelming tumor burden, MM-associated comorbidities, and frequent relapses requiring administration of salvage therapies. As a result, this vicious cycle is often characterized by cumulative immunodeficiency stemming from a combination of disease- and treatment-related factors leading to neutropenia, T-cell deficiency, and hypogammaglobulinemia. Infectious etiologies differ based on the duration of MM and treatment-related factors, such as number of previous treatments and cumulative dose of corticosteroids. Herein, we present the case of a patient who was receiving pomalidomide without concomitant corticosteroids for MM and was later found to have cryptococcosis, as well as findings from a literature review. Most cases of cryptococcosis are reported in patients with late-stage MM, as well as those receiving novel anti-myeloma agents, such as pomalidomide, in combination with corticosteroids or following transplantation. However, it is likely cryptococcosis may be underdiagnosed in this population. Due to the cumulative immunodeficiency present in patients with MM, clinicians must be suspicious of cryptococcosis at any stage of MM.

The Role of GM-CSF Autoantibodies in Infection and Autoimmune Pulmonary Alveolar Proteinosis: A Concise Review

Autoantibodies to multiple cytokines have been identified and some, including antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF), have been associated with increased susceptibility to infection. High levels of GM-CSF autoantibodies that neutralize signaling cause autoimmune pulmonary alveolar proteinosis (aPAP), an ultrarare autoimmune disease characterized by accumulation of excess surfactant in the alveoli, leading to pulmonary insufficiency. Defective GM-CSF signaling leads to functional deficits in multiple cell types, including macrophages and neutrophils, with impaired phagocytosis and host immune responses against pulmonary and systemic infections. In this article, we review the role of GM-CSF in aPAP pathogenesis and pulmonary homeostasis along with the increased incidence of infections (particularly opportunistic infections). Therefore, recombinant human GM-CSF products may have potential for treatment of aPAP and possibly other infectious and pulmonary diseases due to its pleotropic immunomodulatory actions.

Coinfection of disseminated cryptococcosis and BK Virus, a casualty of missed diagnosis during the COVID-19 Pandemic: A case report and review of the literature

Background and Purpose

The COVID-19 pandemic resulted in an overload of health services and healthcare professionals. The result is a setback in health promotion and prevention, delays in diagnosis, and deaths from other diseases that are currently receiving inadequate attention. This article illustrates the risk of this negligence.

Case report

This study aimed to report a case of coinfection of disseminated cryptococcosis and BK virus in a patient without a previous diagnosis of human immunodeficiency virus infection and COVID-19 negative in the context of the COVID-19 pandemic. Despite receiving antifungal therapy, the patient died.

Conclusion

This fatal case is a warning regarding delay of diagnosis and neglect of other serious illnesses owing to the current pandemic, including fungal diseases and neglected diagnoses.

Cryptococcal Meningitis and Post-Infectious Inflammatory Response Syndrome in a Patient With X-Linked Hyper IgM Syndrome: A Case Report and Review of the Literature

The hyper IgM syndromes are a rare group of primary immunodeficiency. The X-linked Hyper IgM syndrome (HIGM), due to a gene defect in CD40L, is the commonest variant; it is characterized by an increased susceptibility to a narrow spectrum of opportunistic infection. A few cases of HIGM patients with Cryptococcal meningoencephalitis (CM) have been described in the literature. Herein we report the case of a young male diagnosed in infancy with HIGM who developed CM complicated by a post-infectious inflammatory response syndrome (PIIRS), despite regular immunoglobulin replacement therapy and appropriate antimicrobial prophylaxis. The patient was admitted because of a headache and CM was diagnosed through detection of Cryptococcus neoformans in the cerebrospinal fluid. Despite the antifungal therapy resulting to negative CSF culture, the patient exhibited persistent headaches and developed diplopia. An analysis of inflammatory cytokines on CSF, as well as the brain MRI, suggested a diagnosis of PIIRS. Therefore, a prolonged corticosteroids therapy was started obtaining a complete resolution of symptoms without any relapse.

The prevalence and mortality of cryptococcal meningitis in patients with autoimmune diseases: a systematic review and meta-analysis

Growing evidence suggests that autoimmune diseases (AIDs) are risk factors for cryptococcal meningitis (CM). Therefore, understanding the epidemiological and clinical profile of CM in patients with AIDs is important. This meta-analysis assessed the prevalence, clinical profiles, and clinical outcomes of CM in AIDs. Studies on CM in patients with AIDs were searched for in PubMed, EMBASE, Web of Science, and China National Knowledge Infrastructure, and meta-analyses were performed using the statistical program of R. Nineteen studies with 36,631 patients with AIDs were analyzed. The overall pooled CM prevalence was 0.4% (95% confidence interval [CI], 0.3-0.6%), 90.7% of which occurred in female patients. Thirteen studies with 77 patients with AIDs diagnosed with CM were analyzed, and the mortality rate was 26.7% (95% CI, 9.5-47.2%). Of patients with systemic lupus erythematosus, 30.1% of CM cases were initially misdiagnosed (95% CI, 0-65.6%). The primary symptom of CM with AIDs was headache (99.4%; 95% CI, 92.1-100%), followed by fever (93.7%; 95% CI, 82.8-100%) and vomiting (37.2%; 95% CI, 13.2-61.2%). The prevalence of CM infections among patients with AIDs should not be underestimated despite non-specific clinical presentations as there were fatal outcomes. Our results suggest that more research is needed to understand the relationship between AIDs and CM, and clinical trials are necessary to improve treatment strategies.

Cryptococcosis

Cryptococcosis is an invasive fungal infection of global significance caused by yeasts of the genus Cryptococcus. The prevalence of HIV in certain areas of the world and the expanding population of immunocompromised patients contribute to the ongoing global disease burden. Point-of-care serologic testing has allowed for more rapid diagnosis and implementation of screening programs in resource-limited settings. Management involves therapy aimed at reduction in fungal burden, maintenance of intracranial pressure, and optimization of host immunity. Despite diagnostic and therapeutic advances, cryptococcosis continues to be a disease with unacceptably high incidence and mortality, particularly in resource-limited settings.

Case Report: Central Nervous System Immune Reconstitution Inflammatory Syndrome Related to Bacterial Meningitis

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) describes clinical characteristics that may be observed in previously immunocompromised patients during rapid restoration of immunity function in the presence of a pathogen. There have been no reports about CNS-IRIS related to bacterial meningitis so far. Here, we report a 24-year-old pregnant female patient with bacterial meningitis. Her clinical and neuroradiological condition worsened after induced labor despite great effective anti-infective therapy. CNS-IRIS was considered. Corticosteroids were administered, and the patient gradually recovered. We present the first case of CNS-IRIS associated with bacterial meningitis.

Central Nervous System Histoplasma-Associated Post-infectious Inflammatory Response Syndrome (Histo-PIIRS)

We present a case of central nervous system (CNS) histoplasmosis in a previously healthy adult with hepatitis C (HCV) presenting with neurological symptoms refractory to antifungal therapy and ventriculoperitoneal (VP) shunting 4 months after initial diagnosis. Persistent symptoms were thought to be inflammatory rather than infectious given negative cerebrospinal fluid (CSF) and serum fungal antigens. The patient promptly improved after initiation of corticosteroid therapy. Elevated CSF cytokines and regional enhancement on brain MRI resolved with corticosteroid treatment. This is the first case of Histoplasma-associated post-infectious inflammatory response syndrome (Histo-PIIRS) documented by CSF cytokine reduction in response to corticosteroid therapy.

Outcomes in Previously Healthy Cryptococcal Meningoencephalitis Patients treated with Pulse - Taper Corticosteroids for Post-infectious Inflammatory Syndrome

BACKGROUND

Cryptococcal meningoencephalitis (CM) is a major cause of mortality in immunosuppressed patients and previously healthy individuals. In the latter, a post-infectious inflammatory response syndrome (PIIRS) is associated with poor clinical response despite antifungal therapy and negative CSF cultures. Data on effective treatment are limited.

METHODS

Between March 2015 and March 2020, 15 consecutive previously healthy patients with CM and PIIRS were treated with adjunctive pulse corticosteroid taper therapy (PCT) consisting of intravenous methylprednisolone 1 gm daily for 1 week followed by oral prednisone 1 mg/kg/d, tapered based on clinical and radiological response plus oral fluconazole. Montreal Cognitive Assessments (MOCA), Karnofsky Performance scores, MRI brain scanning, ophthalmic and audiologic exams, CSF parameters including cellular and soluble immune responses were compared at PIIRS diagnosis and after methylprednisolone completion.

RESULTS

The median time from antifungal treatment to steroid initiation was 6 weeks. The most common symptoms at PIIRS diagnosis were altered mental status and vision changes. All patients demonstrated significant improvements in MOCA and Karnofsky scores at 1 month (p<0.0003), which was accompanied by improvements in CSF glucose, WBC, protein, cellular and soluble inflammatory markers 1 week after receiving corticosteroids (CS) (p<0.003). All patients with papilledema and visual field deficits also exhibited improvement (p<0.0005). Five out of 7 patients who underwent audiological testing demonstrated hearing improvement. Brain MRI showed significant improvement of radiological findings (p=0.001). CSF cultures remained negative.

CONCLUSIONS

PCT in this small cohort of PIIRS was associated with improvements in CM-related complications with minimal toxicity in the acute setting.