Histatin 5 Metallopeptides and Their Potential against Candida albicans Pathogenicity and Drug Resistance

Usually caused by Candida albicans, buccal candidiasis begins with the morphological transition between yeast and hyphal cells. Over time and without the correct treatment, it can be disseminated through the bloodstream becoming a systemic infection with high mortality rates. C. albicans already shows resistance against antifungals commonly used in treatments. Therefore, the search for new drugs capable of overcoming antifungal resistance is essential. Histatin 5 (Hst5) is an antimicrobial peptide of the Histatin family, that can be found naturally in human saliva. This peptide presents high antifungal activity against C. albicans. However, Hst5 action can be decreased for interaction with enzymes and metal ions present in the oral cavity. The current work aims to bring a brief review of relevant aspects of the pathogenesis and resistance mechanisms already reported for C. albicans. In addition, are also reported here the main immune responses of the human body and the most common antifungal drugs. Finally, the most important aspects regarding Histatin 5 and the benefits of its interaction with metals are highlighted. The intention of this review is to show the promising use of Hst5 metallopeptides in the development of effective drugs.

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Efficacy of Novel Schiff base Derivatives as Antifungal Compounds in Combination with Approved Drugs Against Candida Albicans

Medicinal Chemistry ◽

10.2174/1573406415666181203115957 ◽

2019 ◽

Vol 15 (6) ◽

pp. 648-658 ◽

Cited By ~ 1

Author(s):

Manzoor Ahmad Malik ◽

Shabir Ahmad Lone ◽

Parveez Gull ◽

Ovas Ahmad Dar ◽

Mohmmad Younus Wani ◽

...

Keyword(s):

Schiff Base ◽

Candida Albicans ◽

Antifungal Activity ◽

Fungal Infections ◽

Total Sterol ◽

Antifungal Drugs ◽

New Drugs ◽

Ergosterol Biosynthesis ◽

Dependent Manner ◽

Schiff Base Derivatives

Background: The increasing incidence of fungal infections, especially caused by Candida albicans, and their increasing drug resistance has drastically increased in recent years. Therefore, not only new drugs but also alternative treatment strategies are promptly required. Methods: We previously reported on the synergistic interaction of some azole and non-azole compounds with fluconazole for combination antifungal therapy. In this study, we synthesized some non-azole Schiff-base derivatives and evaluated their antifungal activity profile alone and in combination with the most commonly used antifungal drugs- fluconazole (FLC) and amphotericin B (AmB) against four drug susceptible, three FLC resistant and three AmB resistant clinically isolated Candida albicans strains. To further analyze the mechanism of antifungal action of these compounds, we quantified total sterol contents in FLC-susceptible and resistant C. albicans isolates. Results: A pyrimidine ring-containing derivative SB5 showed the most potent antifungal activity against all the tested strains. After combining these compounds with FLC and AmB, 76% combinations were either synergistic or additive while as the rest of the combinations were indifferent. Interestingly, none of the combinations was antagonistic, either with FLC or AmB. Results interpreted from fractional inhibitory concentration index (FICI) and isobolograms revealed 4-10-fold reduction in MIC values for synergistic combinations. These compounds also inhibit ergosterol biosynthesis in a concentration-dependent manner, supported by the results from docking studies. Conclusion: The results of the studies conducted advocate the potential of these compounds as new antifungal drugs. However, further studies are required to understand the other mechanisms and in vivo efficacy and toxicity of these compounds.

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Candida albicans Cek1 Mitogen-Activated Protein Kinase Signaling Enhances Fungicidal Activity of Salivary Histatin 5

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00214-15 ◽

2015 ◽

Vol 59 (6) ◽

pp. 3460-3468 ◽

Cited By ~ 7

Author(s):

Rui Li ◽

Sumant Puri ◽

Swetha Tati ◽

Paul J. Cullen ◽

Mira Edgerton

Keyword(s):

Candida Albicans ◽

Protein Kinase ◽

Antifungal Drugs ◽

Mitogen Activated Protein Kinase ◽

Fungal Cell ◽

Content Type ◽

Histatin 5 ◽

Mitogen Activated Protein ◽

Hyphal Formation ◽

Sensor Proteins

ABSTRACTCandida albicansis a major etiological organism for oropharyngeal candidiasis (OPC), while salivary histatin 5 (Hst 5) is a human fungicidal protein that protects the oral cavity from OPC.C. albicanssenses its environment by mitogen-activated protein kinase (MAPK) activation that can also modulate the activity of some antifungal drugs, including Hst 5. We found that phosphorylation of the MAPK Cek1, induced either byN-acetylglucosamine (GlcNAc) or serum, or its constitutive activation by deletion of its phosphatase Cpp1 elevated the susceptibility ofC. albicanscells to Hst 5. Cek1 phosphorylation but not hyphal formation was needed for increased Hst 5 sensitivity. Interference with the Cek1 pathway by deletion of its head sensor proteins, Msb2 and Sho1, or by addition of secreted aspartyl protease (SAP) cleavage inhibitors, such as pepstatin A, reduced Hst 5 susceptibility under Cek1-inducing conditions. Changes in fungal cell surface glycostructures also modulated Hst 5 sensitivity, and Cek1-inducing conditions resulted in a higher uptake rate of Hst 5. These results show that there is a consistent relationship between activation of Cek1 MAPK and increased Hst 5 susceptibility inC. albicans.

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Disruption of the Candida albicans TPS2 Gene Encoding Trehalose-6-Phosphate Phosphatase Decreases Infectivity without Affecting Hypha Formation

Infection and Immunity ◽

10.1128/iai.70.4.1772-1782.2002 ◽

2002 ◽

Vol 70 (4) ◽

pp. 1772-1782 ◽

Cited By ~ 82

Author(s):

Patrick Van Dijck ◽

Larissa De Rop ◽

Karolina Szlufcik ◽

Elke Van Ael ◽

Johan M. Thevelein

Keyword(s):

Candida Albicans ◽

High Throughput Screening ◽

Deletion Mutant ◽

Systemic Infection ◽

Homozygous Deletion ◽

Antifungal Drugs ◽

Gene Encoding ◽

Complete Inactivation ◽

Hypha Formation ◽

Stress Protectant

ABSTRACT Deletion of trehalose-6-phosphate phosphatase, encoded by TPS2, in Saccharomyces cerevisiae results in accumulation of trehalose-6-phosphate (Tre6P) instead of trehalose under stress conditions. Since trehalose is an important stress protectant and Tre6P accumulation is toxic, we have investigated whether Tre6P phosphatase could be a useful target for antifungals in Candida albicans. We have cloned the C. albicans TPS2 (CaTPS2) gene and constructed heterozygous and homozygous deletion strains. As in S. cerevisiae, complete inactivation of Tre6P phosphatase in C. albicans results in 50-fold hyperaccumulation of Tre6P, thermosensitivity, and rapid death of the cells after a few hours at 44°C. As opposed to inactivation of Tre6P synthase by deletion of CaTPS1, deletion of CaTPS2 does not affect hypha formation on a solid glucose-containing medium. In spite of this, virulence of the homozygous deletion mutant is strongly reduced in a mouse model of systemic infection. The pathogenicity of the heterozygous deletion mutant is similar to that of the wild-type strain. CaTPS2 is a new example of a gene not required for growth under standard conditions but required for pathogenicity in a host. Our results suggest that Tre6P phosphatase may serve as a potential target for antifungal drugs. Neither Tre6P phosphatase nor its substrate is present in mammals, and assay of the enzymes is simple and easily automated for high-throughput screening.

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BAR Domain Proteins Rvs161 and Rvs167 Contribute to Candida albicans Endocytosis, Morphogenesis, and Virulence

Infection and Immunity ◽

10.1128/iai.00683-09 ◽

2009 ◽

Vol 77 (9) ◽

pp. 4150-4160 ◽

Cited By ~ 37

Author(s):

Lois M. Douglas ◽

Stephen W. Martin ◽

James B. Konopka

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Plasma Membrane ◽

Antifungal Drugs ◽

Host Immune System ◽

Membrane Function ◽

Histatin 5 ◽

Essentially Normal ◽

Altered Cell

ABSTRACT The Candida albicans plasma membrane plays critical roles in growth and virulence and as a target for antifungal drugs. Three C. albicans genes that encode Bin-Amphiphysin-Rvs homology domain proteins were mutated to define their roles in plasma membrane function. The deletion of RVS161 and RVS167, but not RVS162, caused strong defects. The rvs161Δ mutant was more defective in endocytosis and morphogenesis than rvs167Δ, but both were strongly defective in polarizing actin patches. Other plasma membrane constituents were still properly localized, including a filipin-stained domain at the hyphal tips. An analysis of growth under different in vitro conditions showed that the rvs161Δ and rvs167Δ mutants grew less invasively in agar and also suggested that they have defects in cell wall synthesis and Rim101 pathway signaling. These mutants were also more resistant to the antimicrobial peptide histatin 5 but showed essentially normal responses to the drugs caspofungin and amphotericin. Surprisingly, the rvs161Δ mutant was more sensitive to fluconazole, whereas the rvs167Δ mutant was more resistant, indicating that these mutations cause overlapping but distinct effects on cells. The rvs161Δ and rvs167Δ mutants both showed greatly reduced virulence in mice. However, the mutants were capable of growing to high levels in kidneys. Histological analyses of infected kidneys revealed that these rvsΔ mutants grew in a large fungal mass that was walled off by leukocytes, rather than forming disseminated microabscesses as seen for the wild type. The diminished virulence is likely due to a combination of the morphogenesis defects that reduce invasive growth and altered cell wall construction that exposes proinflammatory components to the host immune system.

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The vesicle transport protein Vac1p is required for virulence of Candida albicans

Microbiology ◽

10.1099/mic.0.29115-0 ◽

2006 ◽

Vol 152 (10) ◽

pp. 3111-3121 ◽

Cited By ~ 23

Author(s):

Kathrin Franke ◽

Monika Nguyen ◽

Albert Härtl ◽

Hans-Martin Dahse ◽

Georgia Vogl ◽

...

Keyword(s):

Candida Albicans ◽

Mutant Strain ◽

Protein Transport ◽

Systemic Infection ◽

Hyphal Growth ◽

Transport Protein ◽

Vesicle Transport ◽

Antifungal Drugs ◽

Null Mutant ◽

Pathogenic Yeast

The putative vesicle transport protein Vac1p of the human pathogenic yeast Candida albicans plays an important role in virulence. To determine the cellular functions of Vac1p, a null mutant was generated by sequential disruption of both alleles. The vac1 null mutant strain showed defective endosomal vesicle transport, demonstrating a role of Vac1p in protein transport to the vacuole. Vac1p also contributes to resistance to metal ions, as the null mutant strain was hypersensitive to Cu2+, Zn2+ and Ni2+. In addition, the loss of Vac1p affected several virulence factors of C. albicans. In particular, the vac1 null mutant strain showed defective hyphal growth, even when hyphal formation was induced via different pathways. Furthermore, Vac1p affects chlamydospore formation, adherence to human vaginal epithelial cells, and the secretion of aspartyl proteinases (Saps). Avirulence in a mouse model of systemic infection of the vac1 null mutant strongly suggests that Vac1p of C. albicans is essential for pathogenicity. In summary, the Vac1p protein is required for several cellular pathways, in particular those that control virulence and pathogenicity. Consequently, Vac1p is a novel and interesting target for antifungal drugs.

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Drug Repurposing in Medical Mycology: Identification of Compounds as Potential Antifungals to Overcome the Emergence of Multidrug-Resistant Fungi

Pharmaceuticals ◽

10.3390/ph14050488 ◽

2021 ◽

Vol 14 (5) ◽

pp. 488

Author(s):

Lucie Peyclit ◽

Hanane Yousfi ◽

Jean-Marc Rolain ◽

Fadi Bittar

Keyword(s):

Opportunistic Infections ◽

Fungal Infections ◽

Drug Repurposing ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Antifungal Drugs ◽

New Drugs ◽

Medical Community ◽

Medical Mycology ◽

Candida Auris

Immunodepression, whether due to HIV infection or organ transplantation, has increased human vulnerability to fungal infections. These conditions have created an optimal environment for the emergence of opportunistic infections, which is concomitant to the increase in antifungal resistance. The use of conventional antifungal drugs as azoles and polyenes can lead to clinical failure, particularly in immunocompromised individuals. Difficulties related to treating fungal infections combined with the time required to develop new drugs, require urgent consideration of other therapeutic alternatives. Drug repurposing is one of the most promising and rapid solutions that the scientific and medical community can turn to, with low costs and safety advantages. To treat life-threatening resistant fungal infections, drug repurposing has led to the consideration of well-known and potential molecules as a last-line therapy. The aim of this review is to provide a summary of current antifungal compounds and their main resistance mechanisms, following by an overview of the antifungal activity of non-traditional antimicrobial drugs. We provide their eventual mechanisms of action and the synergistic combinations that improve the activity of current antifungal treatments. Finally, we discuss drug repurposing for the main emerging multidrug resistant (MDR) fungus, including the Candida auris, Aspergillus or Cryptococcus species.

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Liposomes functionalized with fungi-targeting peptide demonstrate increased interaction with Candida albicans

Access Microbiology ◽

10.1099/acmi.cc2021.po0180 ◽

2021 ◽

Vol 3 (12) ◽

Author(s):

Ronnie LaMastro ◽

Noel Vera-Gonzalez ◽

Kayla Campbell ◽

Anita Shukla

Keyword(s):

Candida Albicans ◽

Water Solubility ◽

Solid Phase ◽

Fungal Infections ◽

Solid Phase Peptide Synthesis ◽

Antifungal Drugs ◽

Histatin 5 ◽

Delivery Platform ◽

Targeting Peptide ◽

Nih 3T3

Candida albicans infections can be challenging to treat, as current antifungal drugs exhibit poor water solubility and host toxicity. To overcome these issues, new methods of drug delivery are needed. Liposomes have been shown to be an effective method for administrating antifungals and can increase bioavailability and solubility while decreasing toxicity. However, existing antifungal liposomal formulations lack infection specificity. For example, AmBisome, a liposomal formulation of amphotericin B, relies on passive accumulation to infection sites. We have developed antifungal liposomes that display fungi-targeting moieties to promote interaction with Candida;we predict that these formulations can increase fungal eradication and decrease off-site toxicity. Here, the C. albicans-targeting peptide P-113Q2.10 (AQRHHGYKRQFH), a derivative of the antifungal peptide histatin 5, was incorporated into liposomes via conjugation to palmitic acid (PA). PA-P-113Q2.10 conjugates were synthesized using solid phase peptide synthesis, confirmed by liquid-chromatography-mass spectrometry. Liposomes composed of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine and cholesterol with 1% w/w PA-P-113Q2.10 were formed via thin film-hydration and extrusion, yielding ∼100 nm liposomes with a polydispersity index of ∼0.1. Flow cytometry demonstrated that interaction with C. albicans SC5314 was enhanced for P-113Q2.10 liposomes, increasing from ∼60% in cells incubated with liposomes lacking peptide to ∼79%. These liposomes preferentially interact with C. albicans compared to NIH 3T3 murine fibroblasts; on average, only ∼15% of fibroblasts incubated with liposomes (with and without peptide) showed positive liposome interaction. This liposome formulation has the potential to serve as an antifungal delivery platform that selectively targets C. albicans cells for increased efficacy in treatment of fungal infections.

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Effects of histatin 5 and derived peptides on Candida albicans

Biochemical Journal ◽

10.1042/bj3560361 ◽

2001 ◽

Vol 356 (2) ◽

pp. 361-368 ◽

Cited By ~ 49

Author(s):

Anita L. A. RUISSEN ◽

Jasper GROENINK ◽

Eva J. HELMERHORST ◽

Els WALGREEN-WETERINGS ◽

Wim van't HOF ◽

...

Keyword(s):

Candida Albicans ◽

Mitochondrial Membrane ◽

Cytoplasmic Membrane ◽

Human Saliva ◽

Mitochondrial Activity ◽

Complete Protection ◽

Destructive Effect ◽

Histatin 5 ◽

Killing Activity ◽

Anti Fungal

Three anti-microbial peptides were compared with respect to their killing activity against Candida albicans and their ability to disturb its cellular and internal membranes. Histatin 5 is an anti-fungal peptide occurring naturally in human saliva, while dhvar4 and dhvar5 are variants of its active domain, with increased anti-microbial activity. dhvar4has increased amphipathicity compared with histatin 5, whereas dhvar5has amphipathicity comparable with that of histatin 5. All three peptides caused depolarization of the cytoplasmic and/or mitochondrial membrane, indicating membranolytic activity. For the variant peptides both depolarization and killing occurred at a faster rate. With FITC-labelled peptides, no association with the cytoplasmic membrane was observed, contradicting the formation of permanent transmembrane multimeric peptide pores. Instead, the peptides were internalized and act on internal membranes, as demonstrated with mitochondrion- and vacuole-specific markers. In comparison with histatin 5, the variant peptides showed a more destructive effect on mitochondria. Entry of the peptides and subsequent killing were dependent on the metabolic state of the cells. Blocking of the mitochondrial activity led to complete protection against histatin 5 activity, whereas that of dhvar4 was hardly affected and that of dhvar5 was affected only intermediately.

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Interaction between Fluconazole and Amphotericin B in Mice with Systemic Infection Due to Fluconazole-Susceptible or -Resistant Strains of Candida albicans

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.43.12.2841 ◽

1999 ◽

Vol 43 (12) ◽

pp. 2841-2847 ◽

Cited By ~ 32

Author(s):

Arnold Louie ◽

Partha Banerjee ◽

George L. Drusano ◽

Mehdi Shayegani ◽

Michael H. Miller

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

Resistant Strain ◽

Antifungal Agents ◽

Survival Rates ◽

Systemic Infection ◽

Antifungal Drugs ◽

Antifungal Drug ◽

Quantitative Culture ◽

Resistant Strains

ABSTRACT The interaction between fluconazole (Flu) and amphotericin B (AmB) was evaluated in a murine model of systemic candidiasis for one Flu-susceptible strain (MIC, 0.5 μg/ml), two strains with intermediate Flu resistance (Flu mid-resistant strains) (MIC, 64 and 128 μg/ml), and one highly Flu-resistant strain (MIC, 512 μg/ml) ofCandida albicans. Differences in fungal densities in kidneys of infected mice after 24 h of therapy and in survival rates at 62 days of mice treated with an antifungal drug or a combination of antifungal drugs for 4 days were compared. For the Flu-susceptible and Flu mid-resistant strains, the combination of Flu and AmB was antagonistic, as shown by both quantitative culture results and survival. The interaction was additive for the highly Flu-resistant strain. These results suggest that the combination of Flu and AmB should be used with caution in infections due to fungi that are usually susceptible to both antifungal agents and as empirical antifungal drug therapy.

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Effects of citrus limon essential oil (Citrus limon L.) on cytomorphometric changes of Candida albicans

Dental Journal (Majalah Kedokteran Gigi) ◽

10.20473/j.djmkg.v50.i1.p43-48 ◽

2017 ◽

Vol 50 (1) ◽

pp. 43 ◽

Cited By ~ 2

Author(s):

Rina Prabajati ◽

Iwan Hernawan ◽

Hening Tuti Hendarti

Keyword(s):

Candida Albicans ◽

Essential Oil ◽

Incubation Period ◽

Oral Candidiasis ◽

Antifungal Drugs ◽

New Drugs ◽

Control Group ◽

Citrus Limon ◽

Control Group Design ◽

Antifungal Activities

Background: The most common fungal infection found in oral cavity is oral candidiasis, largely caused by Candida species, particularly Candida albicans (C. albicans). Candida infection can get worse since it is difficult to be treated and resistant with antifungal drugs. Therefore, new drugs and compounds as well as alternative therapies involving natural sources that have antifungal activities have continually been developed. Limonene, β-pinene, and ɣ-terpinene contained in Citrus limon essential oil have been known to have quite good antifungal activities against C. albicans. Purpose: This research aimed to examine and analyze the effects of Citrus limon essential oil on cytomorphometric changes of C. albicans. Method: The research used post test only control group design. Based on the results of the pre-elementary research on antifungal activities of Citrus limon essential oil against C. albicans, Citrus limon essential oil used in this research was on concentrations of 1.56%, 1.37%, 1.17%, 0.98%, and 0.78%. Citrus limon essential oil by C. albicans inoculum and incubated for 24 hours and 48 hours. After the incubation, those C. albicans cells were fixed, dried, and then observed using a scanning electron microscopy. Result: The most effective concentrations of Citrus limon essential oil triggering cytomorphometric changes of Candida albicans were at 1.37% and 1.56% with the incubation period of 48 hours. Conclusion: C. albicans can undergo necrosis process through cytomorphometric changes after the administration of Citrus limon essential oil at concentrations of 1.56% and 1.37% with the incubation period of 48 hours.

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