Effect of Candida albicans dsDNA in Gastrointestinal Candida Infection

Neonates are highly sensitive to infections because they are biased to develop Th2 immune responses. When exposed to certain agents, such as DNA vaccines or CpG DNA motifs, neonates are capable to mount adult-like Th1 protective responses. This study investigates the capacity of Candida albicans (C. albicans) dsDNA to induce host resistance in newborn mice against gastrointestinal C. albicans infection. The protective properties of dsDNA are related to an increased number of spleen CD4+ T cells secreting IFN-γ. In infected DNA-treated mice, an enhanced production of IFN-γ by Peyer’s patch cells was observed together with reduced colonization and histopathological changes in the stomach. Our results indicated that C. albicans dsDNA administration in neonates elicited the protective immune response against gastrointestinal Candida infection.     

Influences of Immunosuppressive Agents,FK506 and Cyclosporin on Systemic Candida albicans Infection in Mice

The effects of the immunosuppressive agents FK506 (tacrolimus) and cyclosporin (CyA) on Candida albicans infection in mice were compared with those of cyclophosphamide. FK506 and CyA did not exacerbate C. albicans infection in mice when the effects were determined on the basis of survival ratio and colony forming units (CFU) in the kidney, although cyclophosphamide (CY) impaired the host defence mechanisms of mice against C. albicans infection. The effects of FK506 and CyA on the body weight of mice, histopathological changes of lymphoid tissues and formation of granulomas in kidney were also studied in comparison with those of CY. This revised version was published online in June 2006 with corrections to the Cover Date.     

Candida albicans and HIV-1 Infection

Candida albicans virulence is in part mediated by fibronectin (FN) interaction. We compared the adherence level to FN (using Becton Dickinson FN-coated plates) of several strains of yeast isolated from HIV-1 infected or uninfected subjects affected by candidiasis (30 strains from HIV+ subjects and 18 from HIV- subjects). More adhesive strains were found in HIV+ patients than in HIV- subjects. In particular a mean increase of 120 per cent as regards the total number of adhesive cells and 230 per cent as regards the adhesive cells producing germ tubes was detected in the former group of strains as compared to the latter ( p < 0.001 in both cases). The enhancement of FN expression induced by HIV-1 infection, as we have previously demonstrated, can increase interest in the adherence to FN of C. albicans strains isolated from AIDS-affected patients. Moreover, we also underline the important role played by HIV Nef protein in increasing the C. albicans aggressiveness. In fact a significant inhibitory effect of Nef on the phagocytosis of this yeast by macrophages has been demonstrated and the oxidative processes of these cells seem to be down-regulated by this protein.     

Biomaterial-Associated Infection with Candida albicans in Mice

Candida yeasts are frequently isolated from patients with continuous ambulatory peritoneal dialysis peritonitis or other biomaterial-associated infections. The mouse model of candidal peritonitis was used to study the interaction of Candida cells with end-point attached heparinized polyethylene (H-PE) and with polymorphonuclear leukocytes (PMNs) or macrophages (Mφ). Two Candida strains differing in cell surface hydrophobicity and in expression of fibronectin (Fn) binding were used for the study. Cells of both Candida strains adhered at higher numbers to H-PE surfaces preadsorbed with Fn or with human dialysis fluid (HDF) than to non-modified H-PE, supporting a role of Fn in mediating adhesion. C. albicans 4016 cells expressing low hydrophobicity and low binding of soluble Fn demonstrated stronger adhesion to PMNs than the more hydrophobic C. albicans 3248 yeasts, which express high binding of soluble Fn. However, C. albicans 4016 cells were more resistant to phagocytic killing and were hardly eradicated in intraperitoneally infected mice. The animals depleted in PMNs by treatment with CY were neither able to eradicate C. albicans 3248 (rapidly eliminated by normal mice) nor C. albicans 4016 yeasts (with a tendency to persist in the tissues of normal mice).     

Systemic candidiasis in mice immunized with Candida albicans ribosomes

In view of our previous findings that vaccination of mice with Candida albicans ribosomes protects them against experimental systemic candidiasis, the aim of this study was to investigate the effect of this vaccination on the course of infection in immunized animals. Since the kidney is the maj or target in systemic candidal infection, we concentrated in this research on studying the histopathology and determining quantitatively the candidal colonization of this organ. The experiments were carried out at various time intervals after intravenous inoculation with live C. albicans. The colonization of kidneys in immunized mice was markedly lower than that in controls. The maximal difference in renal colonization between immunized and non immunized animals was observed when relatively low challenge doses were used. The inhibition of candidal multiplication in immunized mice seemed to be correlated to their increased resistance against lethal challenge, as expressed by a significantly higher survival rate. Histopathological changes and fungal elements were found in kidneys of control mice as early as 20 h post infection, while the kidneys of immunized mice did not seem affected by the disease. Moreover, even 3 days post infection, the kidneys of vaccinated animals still seemed normal. In conclusion, apparently the ribosomal vaccination leads to diminished colonization of the major site of infection in candidiasis, thus affording protection to the immunized animals against these infections.     

Resistance of the Candida albicans filamentous cycle to environmental change.

The filamentous growth cycle in C. albicans was resistant to changes in environment brought about either by the serial transfer of growing cells to fresh nutrients or by sudden changes of temperature after the first h of growth. In further experiments older culture filtrates, exhausted of their ability to induce mycelial growth, were reactivated by addition of fresh nutrients or water. The data provided evidence against the existence of both a mycelial stimulatory and inhibitory compound in the growth medium. It is concluded that although the environment initially dictates what proportion of blastospores are committed to filamentation it has no further effect on the process.     

Commensal Candida albicans Positively Calibrates Systemic Th17 Immunological Responses

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Resistance of the stationary-phase plasma membrane of Candida albicans to filipin-induced deformation

Abstract Yeast cells of Candida albicans were treated with the polyene antibiotic filipin which specifically binds with sterol and induces morphological lesions in membranes. The plasma membrane in the exponential phase revealed numerous filipin-induced deformations. In contrast, most areas of the plasma membrane in the stationary phase resisted filipin-induced deformation, even though the cell wall did not prevent the entrance of filipin. These facts suggest that the organisation or physicochemical properties of the plasma membrane in the stationary phase is different from that in the exponential phase.     

Humoral Immunity Links Candida albicans Infection and Celiac Disease

Objective

The protein Hwp1, expressed on the pathogenic phase of Candida albicans, presents sequence analogy with the gluten protein gliadin and is also a substrate for transglutaminase. This had led to the suggestion that C. albicans infection (CI) may be a triggering factor for Celiac disease (CeD) onset. We investigated cross-immune reactivity between CeD and CI.

Methods

Serum IgG levels against recombinant Hwp1 and serological markers of CeD were measured in 87 CeD patients, 41 CI patients, and 98 healthy controls (HC). IgA and IgG were also measured in 20 individuals from each of these groups using microchips sensitized with 38 peptides designed from the N-terminal of Hwp1.

Results

CI and CeD patients had higher levels of anti-Hwp1 (p=0.0005 and p=0.004) and anti-gliadin (p=0.002 and p=0.0009) antibodies than HC but there was no significant difference between CeD and CI patients. CeD and CI patients had higher levels of anti-transglutaminase IgA than HC (p=0.0001 and p=0.0039). During CI, the increase in anti-Hwp1 paralleled the increase in anti-gliadin antibodies. Microchip analysis showed that CeD patients were more reactive against some Hwp1 peptides than CI patients, and that some deamidated peptides were more reactive than their native analogs. Binding of IgG from CeD patients to Hwp1 peptides was inhibited by γIII gliadin peptides.

Conclusions

Humoral cross-reactivity between Hwp1 and gliadin was observed during CeD and CI. Increased reactivity to Hwp1 deamidated peptide suggests that transglutaminase is involved in this interplay. These results support the hypothesis that CI may trigger CeD onset in genetically-susceptible individuals.     

TOS9 regulates white-opaque switching in Candida albicans

In Candida albicans, the a1-alpha2 complex represses white-opaque switching, as well as mating. Based upon the assumption that the a1-alpha2 corepressor complex binds to the gene that regulates white-opaque switching, a chromatinimmunoprecipitation-microarray analysis strategy was used to identify 52 genes that bound to the complex. One of these genes, TOS9, exhibited an expression pattern consistent with a "master switch gene." TOS9 was only expressed in opaque cells, and its gene product, Tos9p, localized to the nucleus. Deletion of the gene blocked cells in the white phase, misexpression in the white phase caused stable mass conversion of cells to the opaque state, and misexpression blocked temperature-induced mass conversion from the opaque state to the white state. A model was developed for the regulation of spontaneous switching between the opaque state and the white state that includes stochastic changes of Tos9p levels above and below a threshold that induce changes in the chromatin state of an as-yet-unidentified switching locus. TOS9 has also been referred to as EAP2 and WOR1.     

A Preliminary Investigation of Individual Differences in Subjective Responses to D-Amphetamine,Alcohol, and Delta-9-Tetrahydrocannabinol Using a Within-Subjects Randomized Trial

Polydrug use is common, and might occur because certain individuals experience positive effects from several different drugs during early stages of use. This study examined individual differences in subjective responses to single oral doses of d-amphetamine, alcohol, and delta-9-tetrahydrocannabinol (THC) in healthy social drinkers. Each of these drugs produces feelings of well-being in at least some individuals, and we hypothesized that subjective responses to these drugs would be positively correlated. We also examined participants’ drug responses in relation to personality traits associated with drug use. In this initial, exploratory study, 24 healthy, light drug users (12 male, 12 female), aged 21–31 years, participated in a fully within-subject, randomized, counterbalanced design with six 5.5-hour sessions in which they received d-amphetamine (20mg), alcohol (0.8 g/kg), or THC (7.5 mg), each paired with a placebo session. Participants rated the drugs’ effects on both global measures (e.g. feeling a drug effect at all) and drug-specific measures. In general, participants’ responses to the three drugs were unrelated. Unexpectedly, “wanting more” alcohol was inversely correlated with “wanting more” THC. Additionally, in women, but not in men, “disliking” alcohol was negatively correlated with “disliking” THC. Positive alcohol and amphetamine responses were related, but only in individuals who experienced a stimulant effect of alcohol. Finally, high trait constraint (or lack of impulsivity) was associated with lower reports of liking alcohol. No personality traits predicted responses across multiple drug types. Generally, these findings do not support the idea that certain individuals experience greater positive effects across multiple drug classes, but instead provide some evidence for a “drug of choice” model, in which individuals respond positively to certain classes of drugs that share similar subjective effects, and dislike other types of drugs.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT02485158","term_id":"NCT02485158"}}NCT02485158     

白色念珠菌氟康唑耐药相关基因的差异显示研究

采用差异显示PCR技术 (DifferentialDisplay PCR ,DD PCR)寻找白色念珠菌的氟康唑耐药相关基因。体外用含氟康唑的酵母培养基 (YEPD)诱导培养临床白色念珠菌氟康唑敏感株 4 35 (对咪康唑耐药 ) ,诱导 80d后得到氟康唑耐药子代 4 35 2 (MIC =1 2 8μg mL)。DD PCR比较 4 35 2、4 35分别在含氟康唑、不含药的YEPD液基中的基因表达 ,找到 3个明显差异片段 ,分别与数据库中白色念珠菌的醇脱氢酶基因ADH1、多药耐药基因CDR1及拓扑异构酶基因TOP2有高度同源性。半定量RT PCR中证实了ADH1、CDR1在氟康唑耐药株中的差异表达 ;对已知氟康唑耐药基因MDR1作半定量RT PCR时发现MDR1在氟康唑耐药株 4 35 2中无表达 ,而在氟康唑敏感株 4 35中有表达。结果表明 ,ADH1、CDR1基因的高表达与白色念珠菌氟康唑耐药性形成相关 ,ADH1可能是新的耐药基因 ;MDR1的表达可能在氟康唑敏感株或其它唑类耐药株中也存在     

Zebrafish Egg Infection Model for Studying Candida albicans Adhesion Factors

Disseminated candidiasis is associated with 30–40% mortality in severely immunocompromised patients. Among the causal agents, Candida albicans is the dominant one. Various animal models have been developed for investigating gene functions in C. albicans. Zebrafish injection models have increasingly been applied in elucidating C. albicans pathogenesis because of the conserved immunity, prolific fecundity of the zebrafish and the low costs of care systems. In this study, we established a simple, noninvasive zebrafish egg bath infection model, defined its optimal conditions, and evaluated the model with various C. albicans mutant strains. The deletion of SAP6 did not have significant effect on the virulence. By contrast, the deletion of BCR1, CPH1, EFG1, or TEC1 significantly reduced the virulence under current conditions. Furthermore, all embryos survived when co-incubated with bcr1/bcr1, cph1/cph1 efg1/efg1, efg1/efg1, or tec1/tec1 mutant cells. The results indicated that our novel zebrafish model is time-saving and cost effective.     

Effect of calcium ion uptake on Candida albicans morphology

In liquid culture using a synthetic medium, added magnesium but not calcium was required for exponential growth of Candida albicans yeast cells. However, medium without added divalent cations supported 2-3 generations of yeast growth or germ tube induction. The addition of calcium ions (1.0 mM) at any stage during the induction of germ tube formation caused reversion to a yeast mode of growth, in contrast to the effect of zinc and cobalt ions which were toxic to all growth. Inhibition of germ tube formation by calcium was not observed in the presence of either magnesium (10 microM) or manganese (100 microM). The presence of either of these ions caused inhibition of 45Ca uptake in yeast cultures. We conclude that unrestricted calcium uptake resulted in the specific inhibition of C. albicans mycelial growth, indicating a critical role for calcium in the regulation of C. albicans morphogenesis.