Pathogenic microbes can recruit to their cell surface human proteins that are components of important proteolytic cascades involved in coagulation, fibrinolysis and innate immune response. Once located at the bacterial or fungal surface, such deployed proteins might be utilized by pathogens to facilitate invasion and dissemination within the host organism by interfering with functionality of these systems or by exploiting specific activity of the bound enzymes. Aim of the study presented here was to characterize this phenomenon in Candida parapsilosis (Ashford) Langeron et Talice - an important causative agent of systemic fungal infections (candidiases and candidemias) in humans. We have investigated the interactions of fungal surface-exposed proteins with plasminogen (HPG) and high-molecular-mass kininogen (HK) - the crucial components of human fibrinolytic system and proinflammatory/procoagulant contact-activated kinin-forming system, respectively. After confirming ability of the fungal surface-exposed proteins to bind HPG and HK, four of them - two agglutinin-like sequence (Als) proteins CPAR2_404780 and CPAR2_404800, a heat shock protein Ssa2 and a moonlighting protein 6-phosphogluconate dehydrogenase 1 - were purified using ion-exchange chromatography, gel filtration and chromatofocusing. Then, their affinities to HPG and HK were characterized with surface plasmon resonance measurements. The determined dissociation constants for the investigated protein-protein complexes were within a 10-7 M order for the HPG binding and in a range of 10-8-10-9 M for the HK binding. Detailed characterization of adsorption of these two important plasma proteins on the fungal cell surface may help to increase our understanding of molecular mechanisms of C. parapsilosis-dependent candidiasis.
Cell wall proteins of Candida albicans, besides their best known role in the adhesion of this fungal pathogen to host's tissues, also bind some soluble proteins, present in body fluids and involved in maintaining the biochemical homeostasis of the human organism. In particular, three plasma factors - high-molecular-mass kininogen (HK), factor XII (FXII) and prekallikrein (PPK) - have been shown to adhere to candidal cells. These proteins are involved in the surface-contact-catalyzed production of bradykinin-related peptides (kinins) that contribute to inflammatory states associated with microbial infections. We recently identified several proteins, associated with the candidal cell walls, and probably involved in the binding of HK. In our present study, a list of potential FXII- and PPK-binding proteins was proposed, using an affinity selection (on agarose-coupled FXII or PPK) from a whole mixture of β-1,3-glucanase-extrated cell wall-associated proteins and the mass-spectrometry protein identification. Five of these fungal proteins, including agglutinin-like sequence protein 3 (Als3), triosephosphate isomerase 1 (Tpi1), enolase 1 (Eno1), phosphoglycerate mutase 1 (Gpm1) and glucose-6-phosphate isomerase 1 (Gpi1), were purified and characterized in terms of affinities to the human contact factors, using the surface plasmon resonance measurements. Except Gpm1 that bound only PPK, and Als3 that exhibited an affinity to HK and FXII, the other isolated proteins interacted with all three contact factors. The determined dissociation constants for the identified protein complexes were of 10-7 M order, and the association rate constants were in a range of 104-105 M-1s-1. The identified fungal pathogen-host protein interactions are potential targets for novel anticandidal therapeutic approaches.
Candida albicans species is the most common yeast isolated from the candidiasis, however the number of fungal infections caused by non-albicans Candida (Candida glabrata, Candida tropicalis, Candida parapsilosis, Candida krusei) has increased in recent years. Fluconazole is an eff ective and well tolerated the antifungal azole drug with parenteral and oral forms. This agent directed to 14--demethylase lanosterol (the product of the ERG11 gene) – the enzyme important in the biosynthesis of ergosterol – the major constituent of fungal membranes. Antifungal drug resistance is associated with the molecular mechanisms, especially with the point mutations of the ERG11 gene and the expression of genes CDR1, CDR2, MDR1 encoding so called effl ux-pumps, the system of transport fl uconazole across the plasma membrane. The aim of this study was the review of the research in various medical centres and the evaluation of the susceptibility of Candida albicans strains and other Candida spp. to fluconazole. These strains obtained from the clinical samples of the patients hospitalized. The fluconazole activity against the yeasts isolates was evaluated in vitro using the reference methods according by the CLSI, predominantly by the broth dilution methods with the determination the minimum inhibitory concentration MIC. Here are the conclusions obtained on the basis of the presented research: 1. The isolates of Candida spp. showed diff erent levels of susceptibility to fluconazole. 2. It’s important to determine the susceptibility of Candida spp. to fluconazole before beginning of treatment to improve the treatment outcome.
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Candida albicans to najczęściej izolowany gatunek w przypadku kandydoz, jednakże liczba infekcji grzybiczych z udziałem non-albicans Candida (Candida glabrata, Candida tropicalis, Candida parapsilosis, Candida krusei) w ostatnich latach wyraźnie wzrosła. Flukonazol jest skutecznym i dobrze tolerowanym lekiem przeciwgrzybiczym – azolem, stosowanym w formie parenteralnej lub doustnej. Lek ten celuje w 14--demetylazę lanosterolu (produkt genu ERG11), enzym istotny w biosyntezie ergosterolu będącego głównym składnikiem błony komórkowej grzyba. Oporność na flukonazol jest związana z istnieniem molekularnych mechanizmów, szczególnie z punktowymi mutacjami w genie ERG11 i ekspresją genów CDR1,CDR2, MDR1 kodujących tzw. effl ux-pumps, tj. system transportu niezbędny do wyrzutu fl ukonazolu przez błonę komórkową. Celem niniejszej pracy było dokonanie przeglądu badań z różnych ośrodków medycznych, dotyczących oceny wrażliwości na fl ukonazol szczepów Candida albicans i innych Candida spp. wyizolowanych z materiałów klinicznych pobranych od hospitalizowanych pacjentów. Aktywność flukonazolu wobec izolatów drożdżaków była oceniana referencyjnymi metodami zgodnymi z zaleceniami CLSI, z przewagą metod rozcieńczeniowych, pozwalających na określenie minimalnego stężenia hamującego MIC. Na podstawie wyników analizowanych badań można sformułować następujące wnioski: 1. Kliniczne szczepy Candida spp. cechują się zróżnicowanym poziomem wrażliwości na flukonazol. 2. Istotne wydaje się oznaczanie wrażliwości Candida spp. na flukonazol przed rozpoczęciem leczenia, w celu uzyskania pozytywnych wyników terapii.
The frequency of severe systemic fungal diseases has increased in the last few decades. The clinical use of antibacterial drugs, immunosuppressive agents after organ transplantation, cancer chemotherapy, and advances in surgery are associated with increasing risk of fungal infections. Opportunistic pathogens from the genera Candida and Aspergillus as well as pathogenic fungi from the genus Cryptococcus can invade human organism and may lead to mucosal and skin infections or to deep-seated mycoses of almost all inner organs, especially in immunocompromised patients. Nowadays, there are some effective antifungal agents, but, unfortunately, some of the pathogenic species show increasing resistance. The identification of fungal virulence factors and recognition of mechanisms of pathogenesis may lead to development of new efficient antifungal therapies. This review is focused on major virulence factors of the most common fungal pathogens of humans: Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans. The adherence to host cells and tissues, secretion of hydrolytic enzymes, phenotypic switching and morphological dimorphism contribute to C. albicans virulence. The ability to grow at 37°C, capsule synthesis and melanin formation are important virulence factors of C. neoformans. The putative virulence factors of A. fumigatus include production of pigments, adhesion molecules present on the cell surface and secretion of hydrolytic enzymes and toxins.
Candida albicans, belonging to the most common fungal pathogens of humans, exploits many virulence factors to infect the host, of which the most important is a family of ten secreted aspartic proteases (Saps) that cleave numerous peptides and proteins, often deregulating the host's biochemical homeostasis. It was recently shown that C. albicans cells can inactivate histatin5 (His5), a salivary histidine-rich anticandidal peptide, through the hydrolytic action of Saps. However, the current data on this subject are incomplete as only four out of ten Saps have been studied with respect to hydrolytic processing of His5 (Sap2, Sap5, Sap9-10). The aim of the study was to investigate the action of all Saps on His5 and to characterize this process in terms of peptide chemistry. It was shown that His5 was degraded by seven out of ten Saps (Sap1-4, Sap7-9) over a broad range of pH. The cleavage rate decreased in an order of Sap2>Sap9>Sap3>Sap7>Sap4>Sap1>Sap8. The degradation profiles for Sap2 and Sap9 were similar to those previously reported; however, in contrast to the previous study, Sap10 was shown to be unable to cleave His5. On a long-time scale, the peptide was completely degraded and lost its antimicrobial potential but after a short period of Sap treatment several shorter peptides (His1-13, His1-17, His1-21) that still decreased fungal survival were released. The results, presented hereby, provide extended characteristics of the action of C. albicans extracellular proteases on His5. Our study contribute to deepening the knowledge on the interactions between fungal pathogens and the human host.
Candida tropicalis is one of the most frequent causes of serious disseminated candidiasis in human patients infected by non-albicans Candida species, but still relatively little is known about its virulence mechanisms. In our current study, the interactions between the cell surface of this species and a multifunctional human protein - high-molecular-mass kininogen (HK), an important component of the plasma contact system involved in the development of the inflammatory state - were characterized at the molecular level. The quick release of biologically active kinins from candidal cell wall-adsorbed HK was presented and the HK-binding ability was assigned to several cell wall-associated proteins. The predicted hyphally regulated cell wall protein (Hyr) and some housekeeping enzymes exposed at the cell surface (known as "moonlighting proteins") were found to be the major HK binders. Accordingly, after purification of selected proteins, the dissociation constants of the complexes of HK with Hyr, enolase, and phosphoglycerate mutase were determined using surface plasmon resonance measurements, yielding the values of 2.20 × 10-7 M, 1.42 × 10-7 M, and 5.81 × 10-7 M, respectively. Therefore, in this work, for the first time, the interactions between C. tropicalis cell wall proteins and HK were characterized in molecular terms. Our findings may be useful for designing more effective prevention and treatment approaches against infections caused by this dangerous fungal pathogen.
Bezoars are foreign bodies in the form of round balls typically found in the alimentary tract, in the area of the stomach. They are created from residual material, e.g. from accidentally swallowed objects (buttons, coins) or some medicines as well as hair and vegetable fibres. Bezoars increase in size as the result of accumulation of undigested food wastes and are unable to pass through the subsequent alimentary tack sections. Bezoars mostly cause nonspecific abdominal pain. In rarer cases, they can be found in the urinary tract. In this case, they develop in the course of a fungal infection within the urinary tract or generalised infection. Their mass is usually made of Candida albicans hyphae. The major factor strongly predisposing to severe fungal infections is host immunosuppression caused by iatrogenic action of medicines that block the immune system as well as different diseases that weaken immunity. In this review, the authors present selected clinical cases of urinary tract bezoars along with the diagnostic and therapeutic management.
PL
Bezoary to ciała obce, kuliste twory występujące zazwyczaj w przewodzie pokarmowym, w obrębie żołądka. Powstają najczęściej z zalegającego w nim materiału, tj. połkniętych przypadkowo przedmiotów (guziki, monety) lub niektórych leków, a oprócz tego włosów i włókien roślinnych. Na skutek odkładania się na ich powierzchni niestrawionych resztek pokarmowych bezoary powiększają swoje rozmiary i nie przedostają się do kolejnego odcinka przewodu pokarmowego. Pod względem klinicznym jednym z symptomów tej patologii są niespecyficzne dolegliwości bólowe brzucha. W znacznie rzadszych przypadkach bezoary mogą występować w obrębie układu moczowego. Jednak wówczas powstają one wskutek trwającej infekcji grzybiczej dróg moczowych lub uogólnionego procesu, a masa bezoaru składa się najczęściej ze strzępek grzybni, głównie Candida albicans. Do czynników wysoce predysponujących do poważnych infekcji grzybiczych należy przede wszystkim stan immunosupresji organizmu, wywołany jatrogennym działaniem leków hamujących aktywność układu immunologicznego lub różnych stanów chorobowych, w których dochodzi do obniżenia odporności. W niniejszej pracy przedstawione zostały wybrane przypadki kliniczne występowania bezoarów w obrębie dróg moczowych wraz z zastosowanym postępowaniem diagnostycznym i terapeutycznym.
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