Genotypes coding for mannose-binding lectin deficiency correlated with cryptococcal meningitis in HIV-uninfected Chinese patients

Identification of risk factors for disseminated cryptococcosis in non-hiv patients: a retrospective analysis

OBJECTIVE

This study aimed to investigate the potential risk factors associated with disseminated cryptococcosis in HIV-negative individuals.

METHODS

A total of 106 HIV-negative patients with cryptococcal disease were enrolled. The observation group consisted of patients with disseminated cryptococcosis (DC), whereas the control groups included patients with pulmonary cryptococcosis (PC) and cryptococcal meningitis (CM). Univariate and multivariate logistic regression algorithms were used to explore the significant clinical and laboratory characteristics that affect the progression of cryptococcal infections. Finally, receiver operating characteristics (ROC) curves are applied to assess the diagnostic value of identified risk factors.LE: Kindly check the edit made in the title.I agree RESULTS: Of the 106 patients, 57 were diagnosed with pulmonary cryptococcosis, 22 with cryptococcal meningitis, and 27 with disseminated cryptococcosis. The logistic regression equation included five variables: diabetes, decompensated liver cirrhosis, long-term use of immunosuppressive agents, decreased serum albumin level, and elevated plasma cytokine IL-10 level. The ROC curves showed that albumin (AUC > 0.7), IL-10 (AUC > 0.7) and decompensated liver cirrhosis (AUC > 0.6) have relatively high diagnostic capacity in predicting the progression of Cryptococcus.

CONCLUSION

This study identified elevated IL-10 levels as an independent risk factor for developing disseminated cryptococcosis in the control groups. Furthermore, decompensated liver cirrhosis and decreased serum albumin independently affected the progression of cryptococcosis in the CM and PC groups, respectively.

Genetic Susceptibility to Fungal Infections

Reports of fungal infections have increased over the past decades, making them a major threat to human health. In this study, we review the effects of genetic defects on susceptibility to fungal diseases. To identify all relevant literature, we searched Google Scholar, PubMed, and Scopus and profiled studies published between 2008 and 2021. The results of several studies conducted on this subject have shown the significant effects of genetic variations such as hyper-IgE syndrome, Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome, dectin-1 deficiency, CARD9 mutations, STAT1 mutations, and IL17 mutationson the host immune system's response, which has an important impact on susceptibility to fungal infections. The underlying immune system-related genetic profile affects the susceptibility of individuals to different fungal infections; therefore, this subject should be further studied for better treatment of fungal diseases.

Cryptococcal Laryngitis: Three Cases Managed With Potassium-Titanyl-Phosphate Laser and Literature Review

OBJECTIVES

To present three case reports of cryptococcal laryngitis managed with potassium-titanyl-phosphate (KTP) laser, where only one case managed with KTP laser has previously been published to date to our knowledge. Further, to systematically review the medical literature and describe the epidemiology, clinical assessment, treatment, and prognosis of laryngeal cryptococcosis.

METHODS

The PubMed, Embase, and OVID MEDLINE databases were searched using the terms "cryptococcal laryngitis" or "cryptococcus" and "larynx or laryngeal."

RESULTS

Thirty-eight cases were identified. The median age was 65 years with a 1 male:1.2 female ratio. Thirty-six cases (95%) presented with hoarseness. Twenty-one cases (55%) were systemically immunosuppressed and 19 (50%) were taking an inhaled corticosteroid. This paper lists the five clinical features (i. white exudate or lesion; ii. exophytic, verrucous or tumor-like mass; iii. diffuse erythema; iv. mucosal irregularity; v. thickened vocal fold) and four pathologic features or tests (i. Grocott Gomori Methenamine stain; ii. Mucicarmine stain; iii. fungal or yeast organisms; iv. fungal culture) that encompass 97% of cases of cryptococcal laryngitis reported in the medical literature. In 34 cases (89%), antifungal therapy was given. Four cases (11%) had excisional biopsy and 11 (29%) received combined surgery and medical therapy. There was uncomplicated resolution in 24 cases (63%).

CONCLUSION

Cryptococcal laryngitis is a rare cause of hoarseness that may be mistaken for malignancy or may be a manifestation of disseminated cryptococcal infection or underlying immunosuppression. Clinicians should be aware of the diagnostic features of cryptococcal laryngitis to facilitate diagnosis and treatment to prevent complicated disease and overly aggressive treatment.

MBL2 gene variants and susceptibility to meningitis in Egyptian patients

BACKGROUND

Meningitis is inflammation of the membranes enclosing the brain and spinal cord. It is a fatal disease with severe morbidity and mortality. Mannose binding lectin (MBL) encoded by MBL2 gene activates complement system through lectin pathway in innate immunity to defense against the infections.

OBJECTIVE

the current study aimed to investigate the promoter and exon 1 variants of MBL2 gene among Egyptian patients having meningitis to explore their role in disease susceptibility.

PATIENTS AND METHODS

This case-control study, included 53 patients and 50 sex and age matched controls. MBL2 genotyping was done using Sanger sequencing.

RESULTS

The frequency of one promoter (c.-290C>G) and four in exon 1 (c.161G>A, c.170G>A, c.154C>T and c.132C>T) as well as another one located in its 5'utranslated part (c.-66C>T) variants were estimated. The incidence of the four individual exonic variants was not significantly different between cases and healthy individuals (all P> 0.05). The promoter variant, c.-290C>G was found in all examined patients (84.9% of the patients in homozygote state and 15.1% of patients in heterozygous state) with a highly significant variance in the prevalence of this variant between cases and control group (p=0.0001). Additionally, UTR variant (c.-66C>T) was also significantly higher in patients than controls (P=0.033).In comparison with clinical outcome, it was found that c.170G>A variant named C allele was associated with favorable outcome in the studied patients (P=0.025).

CONCLUSION

The results obtained showed that the Promoter (c.-290C>G) and UTR (c.-66 C>T) variants of MBL2 gene may be potential risk factors for disease susceptibility in Egyptian cases with meningitis. Our results also proposed that c.170G>A (C allele and CC genotype) could affect the severity and play a protective role in these patients. The other genetic variants of MBL2 gene, including c.132C>T, c.161G>A (A>B), and c.154C>T (A>D) that were investigated, did not show any association with susceptibility or severity of meningitis.

Cryptococcal Meningitis: Differences between Patients with and without HIV-Infection

Background: Cryptococcal meningitis is one of the most devastating infections, particularly in HIV-infected individuals. The increased use of immunosuppressants led to an increase in the incidence of cryptococcosis in HIV-uninfected individuals. This study aimed to compare the characteristics between groups. Methods: This retrospective cohort study was conducted from 2011 to 2021 in northern Thailand. Individuals diagnosed with cryptococcal meningitis aged ≥15 years were enrolled onto the study. Results: Out of 147 patients, 101 were individuals infected with HIV and 46 were non-infected. Factors associated with being infected with HIV included age < 45 years (OR 8.70, 95% CI 1.78–42.62), white blood cells < 5000 cells/cu.mm. (OR 7.18, 95% CI 1.45–35.61), and presence of fungemia (OR 5.86, 95% CI 1.17–42.62). Overall, the mortality rate was 24% (18% in HIV-infected vs. 37% in HIV-uninfected individuals, p-value = 0.020). Factors associated with mortality included concurrent pneumocystis pneumonia (HR 5.44, 95% CI 1.55–19.15), presence of alteration of consciousness (HR 2.94, 95% CI 1.42–6.10), infection caused by members of C. gattii species complex (HR 4.19, 95% CI 1.39–12.62), and anemia (HR 3.17, 95% CI 1.17–8.59). Conclusions: Clinical manifestations of cryptococcal meningitis differed between patients with and without HIV-infection in some aspects. Increasing awareness in physicians of this disease in HIV-uninfected individuals may prompt earlier diagnosis and timely treatment.

Cryptococcal Antigenemia in Advanced Human Immunodeficiency Virus Disease: Pathophysiology, Epidemiology, and Clinical Implications

Cryptococcal antigen (CrAg) is detectable in blood prior to the onset of symptomatic cryptococcal meningitis (CM), a leading cause of death among people with advanced human immunodeficiency virus (HIV) disease globally. Highly sensitive assays can detect CrAg in blood, and screening people with HIV with low CD4 counts, followed by preemptive antifungal treatment, is recommended and widely implemented as part of a global strategy to prevent CM and end cryptococcal-related deaths. Cryptococcal antigenemia encompasses a spectrum of conditions from preclinical asymptomatic infection (cerebrospinal fluid [CSF] CrAg-negative) through subclinical (CSF CrAg-positive without overt meningism) to clinical symptomatic cryptococcal disease, usually manifesting as CM. In this review, we summarize current understanding of the pathophysiology, risk factors for, and clinical implications of cryptococcal antigenemia within this spectrum. We also provide an update on global prevalence, recommended screening and treatment strategies, and future considerations for improving outcomes among patients with cryptococcal antigenemia.

Management of long-term cryptococcal meningitis neoformans in a surviving patient: A case report

Cryptococcal meningitis is a common fungal infection of the central nervous system with high mortality and disability rates. A prominent clinical manifestation is persistent and severe cranial hypertension, which is one of the most critical outcome determinants in patients with cryptococcal meningoencephalitis. Herein, we report and discuss a case of cryptococcal meningitis treated by an inadequate course of medical therapy and placement of a ventriculoperitoneal shunt in a patient who survived for more than 10 years.

Understanding the genetic basis of immune responses to fungal infection

INTRODUCTION

Fungal infections represent a global public health problem that affect millions of people. Despite remarkable advances achieved over the last decades, available diagnostic and therapeutic tools remain insufficient for the optimal management of these diseases. The clinical course of fungal infection is highly variable, and evidence accumulated from patients with rare mutations and cohort-based studies suggests that the trajectory of disease is largely defined by patient genetics and its impact on immune responses. Therefore, there is an urgent need to elucidate the precise mechanisms by which which genetic variants influence the risk, progression, and outcome of fungal infection.

AREAS COVERED

In this review, we highlight recent advances in our understanding of the genetic factors that influence antifungal immune responses based on candidate gene studies and genome-wide approaches performed in different experimental and clinical models.

EXPERT OPINION

Research on genetics of susceptibility to infection is expected to lead to a detailed knowledge framework for the pathogenesis of human fungal infections and unveil novel targets and pathways amenable to clinical intervention.

Human immune polymorphisms associated with the risk of cryptococcal disease

Cryptococcus neoformans is an opportunistic fungal pathogen that can cause lethal cryptococcal meningitis in immunocompromised individuals such as those with HIV/AIDS. In addition, cryptococcal infections occasionally arise in immunocompetent individuals or those with previously undiagnosed immunodeficiencies. The course of cryptococcosis is highly variable in both patient groups, and there is rapidly growing evidence that genetic polymorphisms may have a significant impact on the trajectory of disease. Here, we review what is currently known about the nature of these polymorphisms and their impact on host response to C. neoformans infection. Thus far, polymorphisms in Fc gamma receptors, mannose‐binding lectin, Dectin‐2, Toll‐like receptors and macrophage colony‐stimulating factor have been associated with susceptibility to cryptococcal disease. Notably, however, in some cases the impact of these polymorphisms depends on the genetic background of the population; for example, the FCGR3A 158 F/V polymorphism was associated with an increased risk of cryptococcal disease in both HIV‐positive and HIV‐negative white populations, but not in Han Chinese patients. In most cases, the precise mechanism by which the identified polymorphisms influence disease progression remains unclear, although impaired fungal recognition and phagocytosis by innate immune cells appears to play a major role. Finally, we highlight outstanding questions in the field and emphasize the need for future research to include more diverse populations in their genetic association studies.

Associations between Cryptococcus Genotypes, Phenotypes, and Clinical Parameters of Human Disease: A Review

The genus Cryptococcus contains two primary species complexes that are significant opportunistic human fungal pathogens: C. neoformans and C. gattii. In humans, cryptococcosis can manifest in many ways, but most often results in either pulmonary or central nervous system disease. Patients with cryptococcosis can display a variety of symptoms on a spectrum of severity because of the interaction between yeast and host. The bulk of our knowledge regarding Cryptococcus and the mechanisms of disease stem from in vitro experiments and in vivo animal models that make a fair attempt, but do not recapitulate the conditions inside the human host. To better understand the dynamics of initiation and progression in cryptococcal disease, it is important to study the genetic and phenotypic differences in the context of human infection to identify the human and fungal risk factors that contribute to pathogenesis and poor clinical outcomes. In this review, we summarize the current understanding of the different clinical presentations and health outcomes that are associated with pathogenicity and virulence of cryptococcal strains with respect to specific genotypes and phenotypes.

PTX3 gene polymorphism associated with cryptococcosis in HIV-uninfected Chinese patients

BACKGROUND

For Chinese Han populations, cryptococcosis are more likely to occur in HIV-uninfected patients instead of HIV-infected patients compared with other countries and regions, implying that there may be genetic predisposing factors for cryptococcosis in the Chinese Han populations. However, the retail mechanism has not been clarified.

OBJECTIVES

We aimed to conduct an association analysis between the single nucleotide polymorphisms (SNPs) of pattern recognition receptors (PRR) genes and the susceptibility to cryptococcosis in HIV-uninfected Chinese patients, which may provide new genetic predisposing factors for early-risk prediction of disease, individualised treatment and prognosis monitoring.

PATIENTS/METHODS

Using the SNaPshot SNP typing technique, eight SNPs of PRR genes (Dectin-2, Dectin-1, PTX3, CXCL8, IL12B, IFIH1, TLR1 and CD209) were typed on 97 HIV-uninfected cryptococcosis patients and 120 healthy controls who admitted to West China Hospital, Sichuan University, China, from 1 March 2018 to 30 December 2018. The results were analysed by the SHEsis software and SPSS 20.0 software.

RESULTS

It was found that that PTX3 rs2305619 polymorphism was associated with cryptococcosis in HIV-uninfected patients. Compared with the GG genotype, AA genotype increased the risk of cryptococcosis in HIV-uninfected patients (p = .015, OR, 2.579; 95% CI, 1.202-5.535). In the immunocompetent patients, the AA genotype had a higher risk (p = .002, OR, 4.399; 95% CI, 1.745-11.088). Further verification found that the plasma PTX3 level of the AA genotype was significantly higher than the GA or GG genotype (60.28 ± 16.12 vs 7.32 ± 0.79, p < .001).

CONCLUSIONS

PTX3 rs2305619 polymorphism was associated with cryptococcosis in HIV-uninfected Chinese patients. The AA genotype increased the risk of cryptococcosis, and its plasma PTX3 level was significantly higher than that of GA or GG genotype.

Dormancy in Cryptococcus neoformans: 60 years of accumulating evidence

Cryptococcus neoformans is an opportunistic yeast that is present worldwide and interacts with various organisms. In humans, it is responsible for cryptococcosis, a deadly invasive fungal infection that represents around 220,000 cases per year worldwide. Starting from the natural history of the disease in humans, there is accumulating evidence on the capacity of this organism to enter dormancy. In response to the harsh host environment, the yeast is able to adapt dramatically and escape the vigilance of the host's immune cells to survive. Indeed, the yeast exposed to the host takes on pleiotropic phenotypes, enabling the generation of populations in heterogeneous states, including dormancy, to eventually survive at low metabolic cost and revive in favorable conditions. The concept of dormancy has been validated in C. neoformans from both epidemiological and genotyping data, and more recently from the biological point of view with the characterization of dormancy through the description of viable but nonculturable cells.

Deficiency of mannose-binding lectin is a risk of Pneumocystis jirovecii pneumonia in a natural history cohort of people living with HIV/AIDS in Northern Thailand

Background

Mannose-binding lectin (MBL) plays a pivotal role in innate immunity; however, its impact on susceptibility to opportunistic infections (OIs) has not yet been examined in a natural history cohort of people living with HIV/AIDS.

Methods

We used archived samples to analyze the association between MBL expression types and risk of major OIs including Pneumocystis jirovecii pneumonia (PCP), cryptococcosis, talaromycosis, toxoplasmosis, and tuberculosis in a prospective cohort in Northern Thailand conducted from 1 July 2000 to 15 October 2002 before the national antiretroviral treatment programme was launched.

Results

Of 632 patients, PCP was diagnosed in 96 (15.2%) patients, including 45 patients with new episodes during the follow-up period (1006.5 person-years). The total history of PCP was significantly associated with low MBL expression type: high/intermediate (81/587, 13.8%), low (10/33, 30.3%) and deficient (5/12, 41.7%) (p = 0.001), whereas the history of other OIs showed no relation with any MBL expression type. Kaplan–Meier analysis (n = 569; log-rank p = 0.011) and Cox’s proportional hazards model revealed that deficient genotype dramatically increased the risk of PCP, which is independent upon sex, age, CD4 count, HIV-1 viral load and hepatitis B and C status (adjusted hazard ratio 7.93, 95% confidence interval 2.19–28.67, p = 0.002).

Conclusions

Deficiency of MBL expression is a strong risk factor determining the incidence of PCP but not other major OIs.

Genome-Wide Association Study Identifies Novel Colony Stimulating Factor 1 Locus Conferring Susceptibility to Cryptococcosis in Human Immunodeficiency Virus-Infected South Africans

Background

Cryptococcus is the most common cause of meningitis in human immunodeficiency virus (HIV)-infected Africans. Despite universal exposure, only 5%-10% of patients with HIV/acquired immune deficiency syndrome and profound CD4⁺ T-cell depletion develop disseminated cryptococcosis: host genetic factors may play a role. Prior targeted immunogenetic studies in cryptococcosis have comprised few Africans.

Methods

We analyzed genome-wide single-nucleotide polymorphism (SNP) genotype data from 524 patients of African descent: 243 cases (advanced HIV with cryptococcal antigenemia and/or cryptococcal meningitis) and 281 controls (advanced HIV, no history of cryptococcosis, negative serum cryptococcal antigen).

Results

Six loci upstream of the colony-stimulating factor 1 (CSF1) gene, encoding macrophage colony-stimulating factor (M-CSF) were associated with susceptibility to cryptococcosis at P < 10^-6 and remained significantly associated in a second South African cohort (83 cases; 128 controls). Meta-analysis of the genotyped CSF1 SNP rs1999713 showed an odds ratio for cryptococcosis susceptibility of 0.53 (95% confidence interval, 0.42-0.66; P = 5.96 × 10^-8). Ex vivo functional validation and transcriptomic studies confirmed the importance of macrophage activation by M-CSF in host defence against Cryptococcus in HIV-infected patients and healthy, ethnically matched controls.

Conclusions

This first genome-wide association study of susceptibility to cryptococcosis has identified novel and immunologically relevant susceptibility loci, which may help define novel strategies for prevention or immunotherapy of HIV-associated cryptococcal meningitis.

Cryptococcus Neoformans Meningitis Cases Among China's HIV-Infected Population may have been Severely Under-Reported

Cryptococcal meningitis (CM) is the leading fungal infection of the central nervous system. Globally, most CM cases have been reported from patients with compromised immunities, especially those infected with HIV. However, reports from China have shown that most CM infections were from HIV-negative, immunocompetent hosts. Here, we reviewed the published reports and found those studies were almost exclusively based on patients from hospitals associated with Chinese universities but not from specialized infectious diseases hospitals where most Chinese HIV-infected patients have been treated. Thus, we believe CM cases among China’s HIV-infected population may have been severely under-reported. Analyses of CM cases in specialized infectious diseases hospitals are needed to identify the true epidemiological pattern of CM in China.

HIV Infection Does Not Increase 10-Week Mortality of Chinese Cryptococcal Meningitis Patients

The role of HIV infection in precipitating different clinical features in cryptococcal meningitis (CM) patients remains controversial. One hundred twelve CM patients living with HIV/AIDS (CM+HIV+ patients) and 112 CM patients living without HIV/AIDS (CM+HIV- patients) were enrolled after propensity score matching. Demographic characteristics, symptoms, routine blood tests, and biochemical and cerebrospinal fluid (CSF) profiles were compared between the two groups. Kaplan-Meier analysis and Cox proportional hazards model was used to assess 10-week mortality. CM+HIV+ patients frequently occurred in young (mean age 40.3 ± 10.5) and male (89.3%) populations who also experienced leukopenia, neutropenia, lymphocytopenia, thrombocytopenia, and hypoalbuminemia, less headaches (66.9%), and higher cryptococcemia (23.2%) (all p < .050); they also had higher glucose (2.6 ± 1.1 mmol/L), increased smear positivity (78.8%), and decreased white blood cells [8.0 (2.0-28.0) × 10⁶/L] in initial CSF assay (all p < .050). The 10-week cumulative survival rate was 84.6% for CM+HIV+ patients and 88.5% for CM+HIV- patients (p = .345). Age <35.0 years (hazard ratio (HR) 3.0 (1.0-8.9), p = .046), intracranial pressure (ICP) >250.0 mmH₂O (HR: 4.8 (1.1-21.6), p = .041), and treatment lacking amphotericin B [HR: 6.5 (1.9-21.4), p = .003] were independent risk factors for 10-week mortality in CM+HIV+ patients. There are significant clinical differences in CM patients living with or without HIV/AIDS. However, the 10-week survival rate was similar between the two groups. Younger population, high ICP, and treatment lacking amphotericin B were independent risk factors for 10-week mortality of Chinese CM+HIV+ patients.

Clinical analysis in immunocompetent and immunocompromised patients with pulmonary cryptococcosis in western China

Cryptococcosis is a systemic infection and it may occur in immunocompromised and immunocompetent hosts. In order to better understand the clinical characteristics of patients with PC in different immune status, we retrospectively investigated the clinical, radiological, and treatment profiles of immunocompetent and immunocompromised patients with PC during a 10-year period (2008–2017). As a result, out of 136 patients, 94 (69.1%) were immunocompromised hosts. For the PC patients without CNS involvement, higher percentage of immunocompetent patients (39.5%, 15/38) had asymptomatic presentation than immunocompromised patients (6.3%, 3/48) (P < 0.05). Multiple pulmonary nodules (72.7%, 56/77), ground-glass attenuation/interstitial changes (94.4%, 17/18) and cavitation (88.6%, 31/35) were significantly frequent in immunocompromised patients (P < 0.05). A total of 47 patients were misdiagnosed as tuberculosis or tumors based on CT signs. PC was likely to be misdiagnosed as tuberculosis in immunocompromised patients (88.2%, 15/17), and tumor was more likely to be considered in immunocompetent patients (43.3%, 13/30). Immunocompetent patients accounted for 80% (24/30) of patients with definite diagnosis on surgical lung biopsy. Fluconazole monotherapy can achieve good clinical outcome in most PC patients without central nervous system (CNS) involvement (91.5%, 54/59). After 3 months of treatment, 92.7% (38/41) patients have improved imaging findings. In conclusion, PC has diverse imaging manifestations and it is easily misdiagnosed. Lobectomy should be carefully selected in immunocompetent patients with a single lung lesion. Fluconazole monotherapy is preferred for PC patients without CNS involvement.

Clinical and Radiological Features of Patients With Pulmonary Cryptococcosis in a Hospital of North China

Objective: The increasing incidence has led to more focus on pulmonary cryptococcosis in HIV-negative patients. We conducted a retrospective analysis of pulmonary cryptococcosis to understand the clinical characteristics, imaging features, diagnosis, treatment and prognosis of this disease in HIV-negative patients in respiratory department of a tertiary hospital in north China.

Method: We identified retrospectively those diagnosed with pulmonary cryptococcosis in the first medical center of Chinese People’s Liberation Army General Hospital since 2009 to 2019. The clinical and image data were collected and analyzed.

Results: The study involved 34 patients with pulmonary cryptococcosis. All patients were diagnosed by histopathology. It accounted for 0.93‰ of the total number of patients admitted to respiratory department in the same period. The mean age was 49 years; 26 patients (76.5%) were male. Patients were predominantly immunocompetent (30, 88.2%), and there was no underlying disease for most patients (26, 76.5%). The most frequent symptoms were cough and expectoration. Fourteen (41.2%) patients showed no symptom or sign. Multiple lesions (21, 61.8%) and subpleural lesions (23, 67.6%) were the most common. Nodule was the most common abnormality on chest computed tomography image. Eight (23.5%) patients received serum Cryptococcus capsular polysaccharide antigen test, and seven patients showed positive result. All patients recovered after antifungal treatment.

Conclusions: Most patients of HIV-negative pulmonary cryptococcosis were mainly immunocompetent patients younger than 60 years without underlying diseases. There was lack of specificity in clinical manifestations and imaging findings. The prognosis of pulmonary cryptococcosis in HIV-negative patients was good.

Pathogen and host genetics underpinning cryptococcal disease

Cryptococcosis is a severe fungal disease causing 220,000 cases of cryptococcal meningitis yearly. The etiological agents of cryptococcosis are taxonomically grouped into at least two species complexes belonging to the genus Cryptococcus. All of these yeasts are environmentally ubiquitous fungi (often found in soil, leaves and decaying wood, tree hollows, and associated with bird feces especially pigeon guano). Infection in a range of animals including humans begins following inhalation of spores or aerosolized yeasts. Recent advances provide fundamental insights into the factors from both the pathogen and its hosts which influence pathogenesis and disease. The complex interactions leading to disease in mammalian hosts have also updated from the availability of better genomic tools and datasets. In this review, we discuss recent genetic research on Cryptococcus, covering the epidemiology, ecology, and evolution of Cryptococcus pathogenic species. We also discuss the insights into the host immune response obtained from the latest genetic modified host models as well as insights from monogenic disorders in humans. Finally we highlight outstanding questions that can be answered in the near future using bioinformatics and genomic tools.

Cryptococcal infections in children: retrospective study and review from Australia

Aim: Cryptococcosis causes significant morbidity and mortality worldwide, but pediatric data are limited. Methods: A retrospective literature review of Australian pediatric cryptococcosis and additional 10-year audit of cases from a large pediatric network. Results: 22 cases of cryptococcosis in children were identified via literature review: median age was 13.5 years (IQR 7.8-16 years), 18/22 (82%) had meningitis or central nervous system infection. Where outcome was reported, 11/18 (61%) died. Of six audit cases identified from 2008 to 2017, 5 (83%) had C. gattii disease and survived. One child with acute lymphoblastic leukemia and C. neoformans infection died. For survivors, persisting respiratory or neurological sequelae were reported in 4/6 cases (67%). Conclusion: Cryptococcosis is uncommon in Australian children, but is associated with substantial morbidity.

MiR-30c-5p mediates inflammatory responses and promotes microglia survival by targeting eIF2α during Cryptococcus neoformans infection

Cryptococcosis is a disease predominantly caused by Cryptococcus neoformans in China and C. neoformans is the main form that causes cryptococcal meningitis. In this study, we examined the influence of MiR-30c-5p during Cryptococcus neoformans infection. microRNAs were extracted from Cerebrospinal fluid and sera of patients. To identify pathogenic microRNAs, RNASeq were performed. The results were confirmed with quantitative real-time PCR (qRT-PCR), transient transfection of siRNAs or microRNA mimics into cultured BV2 cell, flow cytometry, immunoblotting, luciferase assay and immunohistochemistry. In this study we found that miR-30c expression was downregulated and that inflammation, apoptosis, and autophagy were activated. The overexpression of miR-30c-5p significantly inhibited inflammation and autophagic activity and decreased apoptosis, and treatment with sieIF2α resulted in a significant decrease in inflammation, apoptosis. In addition, clinical samples of cerebrospinal fluid and serum of patients with cryptococcal meningitis who have undergone standard antifungal treatment showed that the expression of miR-30c-5p was increased while that of eIF2α was decreased, which was in accordance with the in vitro experiments. These studies demonstrated that miRNA-30c-5p can inhibit inflammatory, apoptotic, and autophagic activity through the eIF2α/ATF4 pathway, and it is thus a potential target for the diagnosis, treatment, and detection of cryptococcal meningitis.

Unique clinical features of cryptococcal meningitis among Chinese patients without predisposing diseases against patients with predisposing diseases

The clinical features of cryptococcal meningitis (CM) in patients without predisposing diseases (PD) remain unclear. In sum, 162 of the 167 patients without PD and 162 of the 309 patients with PD were enrolled after propensity score matching. Demographic characteristics, symptoms, blood, and cerebrospinal fluid (CSF) characteristics were compared between the two groups. Kaplan-Meier curves and a Cox proportional hazards model were used to assess the factors associated with 10-week mortality. In total, approximately 35.1% of CM patients were without PD. CM patients without PD had blood profiles of higher white blood cells (WBC) [8.9(6.7-11.0) × 109/l], hemoglobin (128.4 ± 20.9 g/l), platelets [(226.2 ± 64.1) × 109/l], and serum albumin (41.2 ± 5.8 g/l) (all P ≤ .001) and CSF profiles of lower glucose (2.0 ± 1.2 mmol/l), pleocytosis [65.0 (18.0-160.0) × 106/l] and higher total protein [0.9 (0.7-1.4)g/l] (all P < .05). CM patients without PD had lower Cryptococcus culture positivity in CSF (62.5% vs. 74.1%, P = .039) but higher 2-week of CSF culture sterilization rates (69.4% vs. 51.3%, P = .031). The overall 10-week survival rate was 84.7% in patients without PD and 81.1% in patients with PD (Log-rank P = .439). CSF glucose <1.5 mmol/l, CSF fungal burden >20 cells/high power field and treatment lacking amphotericin B had a 3-4 times higher risk of death in patients without PD, whereas serum albumin <35 g/l, CSF glucose < 1.5 mmol/l, and CSF WBC <55 × 106 cell/l were risk factors for patients with PD. CM patients without PD had unique blood and CSF profiles, especially, had lower Cryptococcus culture positivity in CSF, and higher 2-week CSF culture sterilization. Low CSF glucose levels, higher fungal burden, and treatment without amphotericin B were risk factors for 10-week mortality.

Pulmonary cryptococcosis characteristics in immunocompetent patients-A 20-year clinical retrospective analysis in China

Background

Pulmonary cryptococcosis (PC) is not considered an rare, opportunistic infection anymore. The immunocompetent population accounts for an increasing proportion of the morbidity.

Objective

This study investigated the clinical characteristics of PC patients spanning 20 years, in a referral centre of China.

Patients/Methods

We retrospectively investigated the clinical data of 99 patients with PC who were diagnosed at Peking Union Medical College Hospital (PUMCH) from January 1998 to December 2017.

Results

Pulmonary cryptococcosis incidence in PUMCH has seen sharp increase in two decades. There were 40.4% (40/99), 17.2% (17/99) and 42.4% (42/99) immunocompetent, mildly immunocompromised and severe immunocompromised patients, respectively. Significantly higher (P = .035) male predominance in immunocompetent and mildly immunocompromised groups (68.4%, 39/57) compared with severe immunocompromised group (45.2%, 19/42) was found. Overall, 27.5% (11/40) immunocompetent patients reported a significant difference (P = .02) in history of more than weekly drinking, higher than mildly or severe immunocompromised. No significant difference occurred in symptoms and radiographic characteristics among the groups. In pulmonary computerised tomography findings, the non‐air pathway feature was the dominant distribution characteristics in all patients with PC (P = .002). The gap in body dissemination frequency between immunocompetent combined with mildly immunocompromised (5.26%, 3/57) and severe immunocompromised (19.0%, 8/42) was marginally significant (P = .05).

Conclusions

Gender and alcohol drinking could be PC risk factors of concern in patients without severe immunodeficiency. No significant difference occurred in symptoms or radiographic characteristics between patients with different levels of immune status. The unique radiographic non‐air pathway distribution in the lung may be the feature of Cryptococcus invasion that may enhance accurate diagnosis.

How Environmental Fungi Cause a Range of Clinical Outcomes in Susceptible Hosts

Environmental fungi are globally ubiquitous and human exposure is near universal. However, relatively few fungal species are capable of infecting humans, and among fungi, few exposure events lead to severe systemic infections. Systemic infections have mortality rates of up to 90%, cost the US healthcare system $7.2 billion annually, and are typically associated with immunocompromised patients. Despite this reputation, exposure to environmental fungi results in a range of outcomes, from asymptomatic latent infections to severe systemic infection. Here we discuss different exposure outcomes for five major fungal pathogens: Aspergillus, Blastomyces, Coccidioides, Cryptococcus, and Histoplasma species. These fungi include a mold, a budding yeast, and thermal dimorphic fungi. All of these species must adapt to dramatically changing environments over the course of disease. These dynamic environments include the human lung, which is the first exposure site for these organisms. Fungi must defend themselves against host immune cells while germinating and growing, which risks further exposing microbe-associated molecular patterns to the host. We discuss immune evasion strategies during early infection, from disruption of host immune cells to major changes in fungal cell morphology.

Risk factors of laryngeal cryptococcosis: A case report

Cryptococcal infections are acquired by inhalation of encapsulated yeast cells or basidiospores. While Cryptococcus has a propensity to invade the lungs and central nervous system, other sites can be affected. Laryngeal cryptococcosis is rare with less than 30 previously reported cases, which commonly occurred in apparently immunocompetent hosts on inhaled corticosteroids. We present a case of laryngeal cryptococcosis with a long-term inhaled corticosteroid use, co-infection of pulmonary Mycobacterium avium-intracellulare, and mannose-binding lectin deficiency.

Impact of MBL2 gene polymorphisms on the risk of infection in solid organ transplant recipients: A systematic review and meta-analysis

Mannose-binding lectin (MBL) is a soluble pattern recognition molecule involved in complement activation. Single nucleotide polymorphisms (SNPs) in the MBL2 gene have been associated with susceptibility to infection, although data in solid organ transplant recipients remains inconclusive. This meta-analysis was primarily aimed at investigating the association between posttransplant bacterial and fungal infection and variant alleles of MBL2 gene SNPs in the promoter/5' untranslated region and exon 1. Cytomegalovirus (CMV) infection and/or disease were considered secondary outcomes. PubMed, EMBASE, and Web of Knowledge were searched for relevant articles up to August 2018. Eleven studies (comprising 1858 patients) were included, with liver transplant (LT) recipients accounting for 80.4% of the pooled population. As compared to high-MBL expression haplotypes (YA/YA, YA/XA), any MBL-deficient haplotype was associated with an increased risk of posttransplant bacterial and fungal infections (risk ratio [RR]: 1.30; P = .04). Low/null-MBL expression haplotypes (XA/O, O/O) also increased the risk of primary outcome (RR: 1.51; P = .008) and CMV events (RR: 1.50; P = .006). No effect was observed for individual promoter SNPs. In conclusion, MBL-deficient haplotypes are associated with a significant, albeit moderate, increase in the risk of posttransplant infection, with this association being mainly restricted to LT recipients.

Genetic influence of Toll-like receptors on non-HIV cryptococcal meningitis: An observational cohort study

Background

Cryptococcal meningitis (CM) is a significant source of mortality, the pathogenesis of which has not been fully understood, especially in non-HIV infected populations. We aimed to explore the potential genetic influence of Toll-like receptor (TLR) on non-HIV CM.

Methods

This observational cohort study was done in two stages: a discovery stage and a validation stage. A case-control genetic association study was conducted between 159 non-HIV CM patients and 468 healthy controls. TLR SNPs significantly related to susceptibility went further validation in a second cohort of 583 subjects from a certain district. Associations among TLR SNPs, cerebrospinal fluid (CSF) cytokine concentrations, and clinical severity were explored in a third cohort of 99 previously untreated non-HIV CM patients. Logistic regression model was used to determine the independent predictors for disease severity.

Findings

In the discovery stage, eight TLR SNPs exhibited significant genetic susceptibility to non-HIV CM, one of which was validated in a population validation of HIV-infected cases while none survived in non-HIV cases. CSF cytokine detections showed that 18 cytokines were significantly over-expressed in severely ill patients. Two of the 8 SNPs (rs5743604 and rs3804099) were also significantly associated with disease severity. Specifically, the rs3804099 C/T genotype was further found to be correlated to 12 of the 18 up-regulated cytokines in severe patients. In addition, high levels of interleukin (IL)-10 in CSF (OR 2·97, 95% CI 1·49–5·90; p = 0·002) was suggested as an independent predictor for severity after adjusted for possible confounders.

Interpretation

TLR participates in both the occurrence and the pathogenesis of non-HIV CM. The in situ immune responses of CM were under genetic influence of TLR and contributed to disease severity.

Fund

National Natural Science Foundation of China and National Key Basic Research Program of China (973 Program).

A Call to Arms: Quest for a Cryptococcal Vaccine

Cryptococcosis remains a significant cause of morbidity and mortality world-wide, particularly among AIDS patients. Yet, to date, there are no licensed vaccines clinically available to treat or prevent cryptococcosis. In this review, we provide a rationale to support continued investment in Cryptococcus vaccine research, potential challenges that must be overcome along the way, and a literature review of the current progress underway towards developing a vaccine to prevent cryptococcosis.

Ventriculoperitoneal shunts in non-HIV cryptococcal meningitis

Background

Persistent and uncontrollable intracranial hypertension (ICH) and difficulty in reducing Cryptococcus count are severe problems in cryptococcal meningitis (CM) patients. The therapeutic effects of ventriculoperitoneal shunts (VPS) in non-HIV CM patients are not fully known, and the procedure is somewhat unusual. Here, our study offers a review to investigate the role of VPS in non-HIV CM.

Methods

We retrospectively collected data on 23 non-HIV CM patients with and without ventriculomegaly from 2010 to 2016. Their demographic data, clinical manifestations, cerebrospinal fluid (CSF) features and outcomes were analysed.

Results

We found that non-HIV CM patients without ventriculomegaly were older, had earlier treatment times and had shorter symptom durations than CM patients with ventriculomegaly. In both groups, headache, vomiting, fever and loss of vision were the most common clinical features. CSF pressure and Cryptococcus count were significantly decreased after operation. VPS could provide sustained relief from ICH symptoms such as headache. 13% of patients had poor outcomes because of serious underlying disease, while 87% of patients had good outcomes.

Conclusions

The use of a VPS is helpful in decreasing ICH and fungal overload in non-HIV CM patients, and VPS should be performed before CM patients present with symptoms of severe neurological deficit.

Variability in innate host immune responses to cryptococcosis

Cryptococcosis is an invasive fungal disease caused by Cryptococcus neoformans and the closely related species C. gattii. The severe form of the disease, cryptococcal meningitis (CM), is rapidly fatal without treatment. Although typically a disease of immunocompromised (especially HIV-positive) individuals, there is growing awareness of cryptococcal disease amongst non-immunocompromised patients. Whilst substantial progress has been made in understanding the pathogenicity of C. neoformans in HIV patients, prospective data on cryptococcosis outside the context of HIV remains lacking. Below we review how innate immune responses vary between hosts depending on immunological status, and discuss risk factors and predictors of disease outcome in different groups.

Immune-Mediated Damage Completes the Parabola: Cryptococcus neoformans Pathogenesis Can Reflect the Outcome of a Weak or Strong Immune Response

Cryptococcosis occurs most frequently in immunocompromised individuals. This has led to the prevailing view that this disease is the result of weak immune responses that cannot control the fungus. However, increasingly, clinical and experimental studies have revealed that the host immune response can contribute to cryptococcal pathogenesis, including the recent study of L. M. Neal et al. (mBio 8:e01415-17, 2017, https://doi.org/10.1128/mBio.01415-17) that reports that CD4⁺ T cells mediate tissue damage in experimental murine cryptococcosis. This finding has fundamental implications for our understanding of the pathogenesis of cryptococcal disease; it helps explain why immunotherapy has been largely unsuccessful in treatment and provides insight into the paradoxical observation that HIV-associated cryptococcosis may have a better prognosis than cryptococcosis in those with no known immune impairment. The demonstration that host-mediated damage can drive cryptococcal disease provides proof of concept that the parabola put forth in the damage-response framework has the flexibility to depict complex and changing outcomes of host-microbe interaction.

Antibody and B Cell Subset Perturbations in Human Immunodeficiency Virus-Uninfected Patients With Cryptococcosis

The importance of antibody immunity in protection against Cryptococcus neoformans remains unresolved. We measured serum C neoformans-specific and total antibody levels and peripheral blood B cell subsets of 12 previously healthy patients with cryptococcosis (cases) and 21 controls. Before and after adjustment for age, sex, and race, cryptococcal capsular polysaccharide immunoglobulin G was higher in cases than controls, whereas total B and memory B cell levels were lower. These associations parallel previous findings in patients with human immunodeficiency virus-associated cryptococcosis and suggest that B cell subset perturbations may also associate with disease in previously normal individuals with cryptococcosis.

Clinical characteristics and prognosis of pediatric cryptococcosis in Beijing Children's Hospital, 2002-2014

Cryptococcosis is a rare pediatric disease. The aim of the study is to describe clinical characteristics and prognosis of pediatric cryptococcosis from 2002 to 2014 in Beijing Children's Hospital. A total of 53 cases of cryptococcosis were identified, 69.8% of which were males. The mean age was 7 years. Forty-one (77.4%) patients had no underlying conditions. Fever, headache, and vomiting were the most common symptoms. The most common sites were the central nervous system (CNS), followed by the lungs. Most patients received a combination of amphotericin B and fluconazole with or without flucytosine as their initial regimen. Twenty-seven patients received a follow-up and six patients (22.2%) had died. The factors associated with neurological complications or death were headache (P = 0.008), seizures (P = 0.006), visual impairment (P = 0.011), neck stiffness (P = 0.008), low erythrocyte sedimentation rate (ESR) (P = 0.024), and a cerebral spinal fluid (CSF) cryptococcal antigen titer ≥ 1:1024 (P = 0.038).

CONCLUSIONS

The majority of cryptococcosis cases in China occurred in children without underlying conditions, causing multiple organ damage. The CNS was the most common site. Patients who had headaches, seizures, or high CSF antigen titers experienced neurological complications or died. What is known: • Cryptococcosis is a rare cause of infection in children. What is new: • This review gives a brief overview over pediatric cryptococcosis in China.

Clinical characteristics of disseminated cryptococcosis in previously healthy children in China

Background

Disseminated cryptococcosis is a rare and fatal disease, and limited data exist regarding it in children. This study aimed to investigate the clinical characteristics of disseminated cryptococcosis in previously healthy children in China.

Methods

Hospitalized patients with disseminated cryptococcosis were enrolled during January 1996 to December 2015 in Beijing Children’s Hospital, Capital Medical University, China. Data on clinical manifestations, laboratory tests, treatment, and prognosis were evaluated.

Results

A total of 52 pediatric patients with no underlying disease were enrolled, including 38 boys and 14 girls. Only 10 cases had a history of exposure to pigeon droppings. Fever, cough, and hepatomegaly were 3 main manifestations of disseminated cryptococcosis. However, headache was more common in patients with central nervous system (CNS) invasion than in patients with non-CNS invasion (P < 0.05). Lung (96.2%, 50/52) was the most commonly invaded organ, but only 9.6% (5/52) of patients had respiratory signs. The most common findings on chest imaging were hilar or mediastinal lymphadenopathy (46.8%, 22/47), and nodules (44.7%, 21/47), including small nodules in a scattered distribution (57.1%, 12/21) or miliary distribution (42.9%, 9/25), especially localized in subpleural area. Subsequent invasion occurred in the CNS, abdomen lymph nodes, liver, spleen, peripheral lymph nodes, and skin. In all patients, 42.3% (22/52) and 51.9% (27/52) had elevated eosinophils or IgE, respectively. The positive rate of serum cryptococcal antigen was higher, especially in patients with CNS invasion (approximately 83.3%), than with other primary methods used for pathogen detection, including cerebrospinal fluid (CSF) cryptococcal antigen, cultures of blood, bone marrow, or CSF, and CSF ink staining. The overall mortality rate of pediatric patients in our study was 11.5% (6/52). Some cases had long-term sequela, including hydrocephalus, cirrhosis, or blindness.

Conclusions

Disseminated cryptococcosis can occur in previously healthy or immunocompetent children in China. Lung and CNS were most commonly invaded by this disease. Furthermore, most cases usually showed no obvious or specific symptoms or signs, and therefore pediatricians should pay more careful attention to identify this disease.

Increased activity of the complement system in cerebrospinal fluid of the patients with Non-HIV Cryptococcal meningitis

Backgrounds

Cryptococcal meningitis (CM) has been known to lead to significant morbidity and mortality. The relative contribution of the complement system in protection and pathogenesis during CM remains largely unknown. The purpose of this study was to evaluate the baseline complement component profiles in human cerebrospinal fluid (CSF) and plasma from non-HIV patients with CM, and therefore to provide insights of possible roles of the complement system in CM.

Methods

CSF and blood samples from forty two CM patients not infected with HIV and thirteen non-CM control patients (Ctrl) were retrospectively selected and evaluated from the patients admitted to the hospital with a suspected diagnosis of CM. CSF and blood samples were collected at the admission. Enzyme-linked immunosorbent assay (ELISA) for complement components, cytokine IL-12 and western blot for C3 activation were performed on CSF and plasma samples. The levels of complement C1q, factor B (FB), mannose binding lectin (MBL), C2, C3, C4, C5, C4 binding protein (C4BP), Factor I (FI), Factor H (FH), sC5b-9 in CSF and plasma samples were compared. Pearson’s correlation coefficients were calculated on variables between complement components and the levels of total protein in the CSF samples.

Results

Our data demonstrated that the CSF levels of complement components of C1q, FB, MBL as well as complement pathway factors sC5b-9 and complement regulator FH were all elevated in patients with CM as compared to the controls, CSF C3 breakdown products iC3b were found in both CSF and plasma samples of the CM patients. A positive correlation was found between the levels of CSF protein and MBL, C1q or FB.

Conclusions

The activity of the complement system in CSF was increased in non-HIV patients with CM. C1q, MBL and FB are the important participants in the complement activation in CM. The relative contribution of each of the specific complement pathways and complement cascades in protection and inflammation resolution against CM warrant further investigation.

Characteristics and outcomes of cryptococcal meningitis in HIV seronegative children in Beijing, China, 2002-2013

Background

Data regarding HIV-seronegative pediatric patients with cryptococcal meningitis (CM) have been very limited.

Methods

We retrospectively reviewed non-HIV-infected in patients with CM from January 2002 through December 2013 in Beijing Children’s Hospital. Records of the all patients were obtained and compared.

Results

The 34 children had a median age of 5.6 years. Most of the patients were male (67.6 %). Only 23.5 % of the cases had identifiable underlying diseases. The sensitivity of the CSF cryptococcal antigen, India ink smear and CSF culture in our study were 81.5, 85.3 and 82.4 %, respectively. And the sensitivity of combinations of these tests was 91.2 %. Out of the 34 patients, 16 (47.1 %) had other organs involvement in addition to the brain. The main abnormal features via magnetic resonance imaging (MRI) were Virchow-Robin space dilatation (44.4 %), hydrocephalus (38.9 %), gelatinous pseudocysts (33.3 %), brain atrophy (33.3 %), meningeal enhancement (27.8 %) and local lesions (27.8 %). In total, 64.7 % of the patients were successfully treated at discharge, whereas treatment failed in 35.3 % of the patients.

Conclusions

Cryptococcal meningitis is an infrequent disease with a high fatality rate in children in China. The majority of patients were apparently healthy. Clinicians should consider cryptococcal infection as a potential pathogen of pediatric meningitis. Cryptococcal antigen, India ink smear and culture tests are recommended for diagnosis.

Genetic Susceptibility to Fungal Infections: What is in the Genes?

The development of severe fungal infections has long been associated with traditional risk factors such as profound immunosuppression, yet it remains challenging to understand why under similar conditions only some patients will develop these infections while others will not. Recent studies have demonstrated the importance of host genetic variation in influencing the severity and susceptibility to invasive fungal infections (IFIs). In this review, we examine selected primary immunodeficiencies characterized by their vulnerability to a narrow range of fungal pathogens, and then focus on recently identified genetic polymorphisms associated with an increased susceptibility to IFIs.

Host immunity to Cryptococcus neoformans

Cryptococcosis is caused by the fungal genus Cryptococcus. Cryptococcosis, predominantly meningoencephalitis, emerged with the HIV pandemic, primarily afflicting HIV-infected patients with profound T-cell deficiency. Where in use, combination antiretroviral therapy has markedly reduced the incidence of and risk for disease, but cryptococcosis continues to afflict those without access to therapy, particularly in sub-Saharan Africa and Asia. However, cryptococcosis also occurs in solid organ transplant recipients and patients with other immunodeficiencies as well as those with no known immunodeficiency. This article reviews innate and adaptive immune responses to C. neoformans, with an emphasis on recent studies on the role of B cells, natural IgM and Fc gamma receptor polymorphisms in resistance to cryptococcosis.

Cryptococcus: from environmental saprophyte to global pathogen

Cryptococcosis is a globally distributed invasive fungal infection that is caused by species within the genus Cryptococcus which presents substantial therapeutic challenges. Although natural human-to-human transmission has never been observed, recent work has identified multiple virulence mechanisms that enable cryptococci to infect, disseminate within and ultimately kill their human host. In this Review, we describe these recent discoveries that illustrate the intricacy of host-pathogen interactions and reveal new details about the host immune responses that either help to protect against disease or increase host susceptibility. In addition, we discuss how this improved understanding of both the host and the pathogen informs potential new avenues for therapeutic development.

The Cnes2 locus on mouse chromosome 17 regulates host defense against cryptococcal infection through pleiotropic effects on host immunity

The genetic basis of natural susceptibility to progressive Cryptococcus neoformans infection is not well understood. Using C57BL/6 and CBA/J inbred mice, we previously identified three chromosomal regions associated with C. neoformans susceptibility (Cnes1, Cnes2, and Cnes3). To validate and characterize the role of Cnes2 during the host response, we constructed a congenic strain on the C57BL/6 background (B6.CBA-Cnes2). Phenotypic analysis of B6.CBA-Cnes2 mice 35 days after C. neoformans infection showed a significant reduction of fungal burden in the lungs and spleen with higher pulmonary expression of gamma interferon (IFN-γ) and interleukin-12 (IL-12), lower expression of IL-4, IL-5, and IL-13, and an absence of airway epithelial mucus production compared to that in C57BL/6 mice. Multiparameter flow cytometry of infected lungs also showed a significantly higher number of neutrophils, exudate macrophages, CD11b(+) dendritic cells, and CD4(+) cells in B6.CBA-Cnes2 than in C57BL/6 mice. The activation state of recruited macrophages and dendritic cells was also significantly increased in B6.CBA-Cnes2 mice. Taken together, these findings demonstrate that the Cnes2 interval is a potent regulator of host defense, immune responsiveness, and differential Th1/Th2 polarization following C. neoformans infection.

Gene polymorphisms of mannose-binding lectin confer susceptibility to Pneumocystis pneumonia in HIV-infected patients

BACKGROUND

Mannose-binding lectin (MBL) plays an important role in innate immunity. The aim of this study was to determine whether genetic variants of MBL confer susceptibility to Pneumocystis pneumonia (PCP) in patients with advanced human immunodeficiency virus (HIV) infections.

OBJECTIVE

HIV patients (n = 53) having CD4 counts <200/μL who were admitted to our hospital were analyzed. Of these 53 patients, 30 had PCP at admission, and 23 did not. Genotypes at six single nucleotide polymorphisms (SNP) in MBL2 gene and serum MBL levels were determined for each patient, and compared between patients with or without PCP. We also examined whether MBL enhances phagocytosis of macrophages against rat-type Pneumocystis organism in vitro.

RESULTS

Genotypes associated with low production of MBL were significantly more common in the PCP group than in the non-PCP group (P = 0.049, odds ratio 2.17, 95% CI 1.02-4.63). Serum MBL levels were significantly higher in the non-PCP group (P = 0.039). Findings from in vitro experiments indicated that MBL act as a direct opsonin enhancing macrophage-mediated phagocytosis of Pneumocystis organisms.

CONCLUSION

Genetic variation of MBL production influences susceptibility to PCP in patients with advanced HIV infection, and can be regarded as a risk factor for PCP.

Dectin-2 polymorphism associated with pulmonary cryptococcosis in HIV-uninfected Chinese patients

Dectin-2 is a C-type lectin receptor that can recognize critical structures of fungi and involve in the host immune response after pulmonary fungal infections. We aimed to investigate the association between Dectin-2 genetic polymorphisms and cryptococcosis among a series of human immunodeficiency virus (HIV)-uninfected Chinese patients. In this case control study, a total of 251 patients with cryptococcosis and 464 healthy controls were included. One tag-single nucleotide polymorphism (SNP) (rs11045418) located at 5'-flanking region of Dectin-2 gene was selected and genotyped in this study. Among 251 patients, there were 108 (43%) meningitis patients including 73 (67.7%) healthy ones, 74 (29.5%) pulmonary infected patients including 49 (66.2%) healthy ones, and 69 (27.5%) patients with both neural and pulmonary infection including 38 (55.1%) immunocompetent ones. One hundred and forty-three (74 plus 69) patients with pulmonary cryptococcosis and 177 (108 plus 69) patients with cryptococcal meningitis were compared with controls, respectively. Three samples from 143 pulmonary infected patients failed in genotyping. There was a significant difference between 86 immunocompetent pulmonary infected patients and controls in the overdominant model (C/T vs. T/T + C/C; OR, 0.59; 95%CI, 0.37-0.94; P, .026). Similar but not significant difference was found between the overall pulmonary infected patients and the controls in the overdominant model (OR, 0.77; 95%CI, 0.52-1.12; P, .17). No such difference was found between controls and patients with cryptococcal meningitis. Our study firstly showed a genetic association between Dectin-2 and pulmonary cryptococcosis.

Cryptococcus neoformans host adaptation: toward biological evidence of dormancy

Cryptococcosis is an opportunistic infection due to the ubiquitous yeast Cryptococcus neoformans. This yeast interacts closely with innate immune cells, leading to various fates, including fungal persistence within cells, making possible the dissemination of the yeast cells with monocytes via a Trojan horse strategy. In humans, the natural history of the infection begins with primoinfection during childhood, which is followed by dormancy and, in some individuals, reactivation upon immunosuppression. To address the question of dormancy, we studied C. neoformans infection at the macrophage level (in vitro H99-macrophage interaction) and at the organ level in a murine model of cryptococcosis. We analyzed the diversity of yeast adaptation to the host by characterizing several C. neoformans populations with new assays based on flow cytometry (quantitative flow cytometry, multispectral imaging flow cytometry, sorting), microscopy (dynamic imaging), and gene expression analysis. On the basis of parameters of multiplication and stress response, various populations of yeast cells were observed over time in vivo and in vitro. Cell sorting allowed the identification of a subpopulation that was less prone to grow under standard conditions than the other populations, with growth enhanced by the addition of serum. Gene expression analysis revealed that this population had specific metabolic characteristics that could reflect dormancy. Our data suggest that dormant yeast cells could exist in vitro and in vivo. C. neoformans exhibits a huge plasticity and adaptation to hosts that deserves further study. In vitro generation of dormant cells is now the main challenge to overcome the limited number of yeast cells recovered in our models.

IMPORTANCE

Cryptococcus neoformans is a sugar-coated unicellular fungus that interacts closely with various cells and organisms, including amoebas, nematodes, and immune cells of mammals. This yeast is able to proliferate and survive in the intracellular environment. C. neoformans causes cryptococcosis, and yeast dormancy in humans has been suggested on the basis of epidemiological evidence obtained years ago. By studying an in vitro model of yeast-macrophage interaction and murine models of cryptococcosis, we observed that yeast cells evolve in heterogeneous populations during infection on the basis of global metabolic activity. We compared the growth ability and gene expression of yeast cells belonging to various populations in those two models. We eventually found a population of yeast cells with low metabolism that fit some of the criteria for dormant cells. This paves the way for further characterization of dormancy in C. neoformans.

Epidemiology of Cryptococcus and cryptococcosis in China

Cryptococcosis is a significant invasive fungal infection with noteworthy morbidity and mortality, primarily caused by Cryptococcus neoformans and Cryptococcus gattii. In China, C. neoformans var. grubii (especially molecular type VNI) is the most common variety in the environment and responsible for the majority of cryptococcal infections. C. gattii infections are quite rare in China and the primary molecular type is VGI, which is closely related to C. gattii isolates in Australia. Interestingly, the majority of cryptococcosis in China were reported in the HIV-uninfected patients (especially immunocompetent hosts). This unique phenomenon may be attributed to multiple polymorphisms in the genes encoding mannose-binding lectin (MBL) and Fc-gamma receptor 2B (FCGR2B) in the Han population, the major ethnic group in China. Compared to immunocompromised patients, immunocompetent patients with cryptococcal meningitis often presented with more intense inflammatory responses and more severe neurological complications, but less fungal burdens and disseminated infection. The overall prognosis, which is independently associated with amphotericin B-based initial therapy, is similar between immunocompetent and immunocompromised patients. In addition, intrathecal administration of amphotericin B has been proved to be an effective adjunctive treatment for cryptococcosis in China.

Genetic variants of innate immune receptors and infections after liver transplantation

Infection is the leading cause of complication after liver transplantation, causing morbidity and mortality in the first months after surgery. Allograft rejection is mediated through adaptive immunological responses, and thus immunosuppressive therapy is necessary after transplantation. In this setting, the presence of genetic variants of innate immunity receptors may increase the risk of post-transplant infection, in comparison with patients carrying wild-type alleles. Numerous studies have investigated the role of genetic variants of innate immune receptors and the risk of complication after liver transplantation, but their results are discordant. Toll-like receptors and mannose-binding lectin are arguably the most important studied molecules; however, many other receptors could increase the risk of infection after transplantation. In this article, we review the published studies analyzing the impact of genetic variants in the innate immune system on the development of infectious complications after liver transplantation.

How does mother-to-child transmission of HIV differ among African populations? Lessons from MBL2 genetic variation in Zimbabweans

Mannose binding lectin (MBL) is a pathogen pattern recognition protein involved in antimicrobial activities. Variation in MBL2 gene has been extensively implicated in differential outcomes of infectious diseases in studies conducted outside Africa, but virtually very little is known on the role of this candidate gene in the African continent. We investigated human genetic variations in MBL2 in a Zimbabwean pediatric population and their putative associations with HIV infection in perinatally exposed children. One hundred and four children aged 7 to 9 years comprising 68 perinatally exposed to HIV (32 who were born infected and 36 who were uninfected) and 36 unexposed controls were recruited. DNA samples were genotyped for MBL2 polymorphisms using PCR-RFLP and sequencing. HIV infected children had markedly variable and significantly lower mean height (p=0.03) and weight (p=0.005) when compared to the uninfected children. Using all samples, frequencies for MBL2 genetic variants for the Zimbabwean population were calculated. Twelve single nucleotide polymorphisms were observed and minor alleles occurred with the following frequencies: -550C>G (G: 0.02), -435G>A (A: 0.08), -428A>C (C: 0.39), -394A>G (A: 0.39), -328AGAGAA ins/del (AGAGAA ins: 0.44), -245G>A (A: 0.05), -221C>G (C: 0.12), -111A>T (T: 0.10), -70C>T (C: 0.46), +4C>T (C: 0.45), novel -595G>A (A: 0.02), and 170G>A (0.24). We found that the MBL2 +4T variant displayed a trend for association with reduced risk of HIV transmission from mother-to-child but the remaining vast majority of the genetic markers did not show a significant association. We conclude (1) the MBL2 gene is highly polymorphic in the Zimbabwean population, and (2) MBL2 genetic variation does not appear to play a major role in influencing the risk of mother-to-child HIV transmission in our study sample. These observations contest the hitherto significant role of this candidate gene for HIV transmission from mother-to-child in non-African populations and thus, further speak to the limits of extrapolating genomic association studies directly to the African populations from studies conducted elsewhere. It is hoped that more OMICS research in a diverse set of African countries can shed further light on the putative role (or the lack thereof ) of this candidate gene in HIV transmission in the continent, a major global health burden in Africa.