scholarly journals Jerveratrum-Type Steroidal Alkaloids Inhibit β-1,6-Glucan Biosynthesis in Fungal Cell Walls

2022 ◽  
Author(s):  
Karen Kubo ◽  
Kaori Itto-Nakama ◽  
Shinsuke Ohnuki ◽  
Yoko Yashiroda ◽  
Sheena C. Li ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Cell Walls ◽  
Therapeutic Agents ◽  
Antifungal Drugs ◽  
Steroidal Alkaloids ◽  
Fungal Cell ◽  
Content Type ◽  
Fungal Cell Walls

Non- Candida albicans Candida species (NCAC) are on the rise as a cause of mycosis. Many antifungal drugs are less effective against NCAC, limiting the available therapeutic agents.

scholarly journals Dectin-1-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Suresh Ambati ◽  
Aileen R. Ferarro ◽  
S. Earl Kang ◽  
Jianfeng Lin ◽  
Xiaorong Lin ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Antifungal Drugs ◽  
Beta Glucan ◽  
Fungal Cell ◽  
Content Type ◽  
Current Therapies ◽  
Mammalian Protein ◽  
Fungal Cell Walls

The fungus Aspergillus fumigatus causes pulmonary invasive aspergillosis resulting in nearly 100,000 deaths each year. Patients are often treated with antifungal drugs such as amphotericin B (AmB) loaded into liposomes (AmB-LLs), but all antifungal drugs, including AmB-LLs, have serious limitations due to human toxicity and insufficient fungal cell killing. Even with the best current therapies, 1-year survival among patients with invasive aspergillosis is only 25 to 60%. Hence, there is a critical need for improved antifungal therapeutics. Dectin-1 is a mammalian protein that binds to beta-glucan polysaccharides found in nearly all fungal cell walls. We coated AmB-LLs with Dectin-1 to make DEC-AmB-LLs. DEC-AmB-LLs bound strongly to fungal cells, while AmB-LLs had little affinity. DEC-AmB-LLs killed or inhibited A. fumigatus 10 times more efficiently than untargeted liposomes, decreasing the effective dose of AmB. Dectin-1-coated drug-loaded liposomes targeting fungal pathogens have the potential to greatly enhance antifungal therapeutics.

scholarly journals Screening and Antifungal Activity of a β-Carboline Derivative against Cryptococcus neoformans and C. gattii

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Kátia Santana Cruz ◽  
Emerson Silva Lima ◽  
Marcia de Jesus Amazonas da Silva ◽  
Erica Simplício de Souza ◽  
Andreia Montoia ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antifungal Activity ◽  
Cryptococcus Neoformans ◽  
Active Compound ◽  
Cell Walls ◽  
Human Fibroblasts ◽  
Lead Compound ◽  
Fungal Cell ◽  
Fungal Cell Walls

Background. Cryptococcosis is a fungal disease of bad prognosis due to its pathogenicity and the toxicity of the drugs used for its treatment. The aim of this study was to investigate the medicinal potential of carbazole and β-carboline alkaloids and derivatives against Cryptococcus neoformans and C. gattii. Methods. MICs were established in accordance with the recommendations of the Clinical and Laboratory Standards Institute for alkaloids and derivatives against C. neoformans and C. gattii genotypes VNI and VGI, respectively. A single active compound was further evaluated against C. neoformans genotypes VNII, VNIII, and VNIV, C. gattii genotypes VGI, VGIII, and VGIV, Candida albicans ATCC 36232, for cytotoxicity against the MRC-5 lineage of human fibroblasts and for effects on fungal cells (cell wall, ergosterol, and leakage of nucleic acids). Results. Screening of 11 compounds revealed 8-nitroharmane as a significant inhibitor (MIC 40 μg/mL) of several C. neoformans and C. gattii genotypes. It was not toxic to fibroblasts (IC50 > 50 µg/mL) nor did it alter fungal cell walls or the concentration of ergosterol in C. albicans or C. neoformans. It increased leakage of substances that absorb at 260 nm. Conclusions. The synthetic β-carboline 8-nitroharmane significantly inhibits pathogenic Cryptococcus species and is interesting as a lead compound towards new therapy for Cryptococcus infections.

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

2015 ◽  
Vol 59 (6) ◽  
pp. 3460-3468 ◽  
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.

scholarly journals Targeted antifungal liposomes

2019 ◽  
Author(s):  
Suresh Ambati ◽  
Aileen R. Ferarro ◽  
S. Earl Khang ◽  
Xiaorong Lin ◽  
Michelle Momany ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Antifungal Drugs ◽  
Human Toxicity ◽  
Beta Glucan ◽  
Fungal Cell ◽  
Order Of Magnitude ◽  
One Year ◽  
Fungal Cell Walls

AbstractAspergillus species cause pulmonary invasive aspergillosis resulting in nearly a hundred thousand deaths each year. Patients at the greatest risk of developing life-threatening aspergillosis have weakened immune systems and/or various lung disorders. Patients are treated with antifungals such as amphotericin B (AmB), casofungin acetate, or triazoles (itraconazole, voriconazole etc.), but these antifungal agents have serious limitations due to lack of sufficient fungicidal effect and human toxicity. Liposomes with AmB intercalated into the lipid membrane (AmBisomes, AmB-LLs), have several-fold reduced toxicity compared to detergent solubilized drug. However, even with the current antifungal therapies, one-year survival among patients is only 25 to 60%. Hence, there is a critical need for improved antifungal therapeutics.Dectin-1 is a mammalian innate immune receptor in the membrane of some leukocytes that binds as a dimer to beta-glucans found in fungal cell walls, signaling fungal infection. Using a novel protocol, we coated AmB-LLs with Dectin-1’s beta-glucan binding domain to make DEC-AmB-LLs. DEC-AmB-LLs bound rapidly, efficiently, and with great strength Aspergillus fumigatus and to Candida albicans and Cryptococcus neoformans, highly divergent fungal pathogens of global importance. By contrast, un-targeted AmB-LLs and BSA-coated BSA-AmB-LLs showed 200-fold lower affinity for fungal cells. DEC-AmB-LLs reduced the growth and viability of A. fumigatus an order of magnitude more efficiently than untargeted control liposomes delivering the same concentrations of AmB, in essence increasing the effective dose of AmB. Future efforts will focus on examining pan-antifungal targeted liposomal drugs in animal models of disease.TweetWe coated anti-fungal drug loaded liposomes to fungal cell walls with a beta-glucan binding protein and thereby increased drug effectiveness by an order of magnitude.ImportanceThe fungus Aspergillus fumigatus causes pulmonary invasive aspergillosis resulting in nearly a hundred thousand deaths each year. Patients are often treated with antifungal drugs such as amphotericin B loaded into liposomes, AmB-LLs, but all antifungal drugs including AmB-LLs have serious limitations due to human toxicity and insufficient fungal cell killing. Even with the best current therapies, one-year survival among patients with invasive aspergillosis is only 25 to 60%. Hence, there is a critical need for improved antifungal therapeutics.Dectin-1 is a mammalian protein that binds to beta-glucan polysaccharides found in nearly all fungal cell walls. We coated AmB-LLs with Dectin-1 to make DEC-AmB-LLs. DEC-AmB-LLs bond strongly to fungal cells, while AmB-LLs had little affinity. DEC-AmB-LLs killed or inhibited A. fumigatus ten times more efficiently than untargeted lipsomes, increasing the effective dose of AmB. Dectin-1 coated liposomes targeting fungal pathogens have the potential to greatly enhance antifungal therapeutics.

scholarly journals Elevated Chitin Content Reduces the Susceptibility of Candida Species to Caspofungin

2012 ◽  
Vol 57 (1) ◽  
pp. 146-154 ◽  
Author(s):  
Louise A. Walker ◽  
Neil A. R. Gow ◽  
Carol A. Munro
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Point Mutations ◽  
Antifungal Drugs ◽  
Cell Wall Polysaccharide ◽  
Chitin Synthesis ◽  
Fungal Cell ◽  
Content Type ◽  
Chitin Content ◽  
Compensatory Increase

ABSTRACTThe echinocandin antifungal drugs inhibit synthesis of the major fungal cell wall polysaccharide β(1,3)-glucan. Echinocandins have good efficacy againstCandida albicansbut reduced activity against otherCandidaspecies, in particularCandida parapsilosisandCandida guilliermondii. Treatment ofCandida albicanswith a sub-MIC level of caspofungin has been reported to cause a compensatory increase in chitin content and to select for sporadic echinocandin-resistantFKS1point mutants that also have elevated cell wall chitin. Here we show that elevated chitin in response to caspofungin is a common response in variousCandidaspecies. Activation of chitin synthesis was observed in isolates ofC. albicans,Candida tropicalis,C. parapsilosis, andC. guilliermondiiand in some isolates ofCandida kruseiin response to caspofungin treatment. However,Candida glabrataisolates demonstrated no exposure-induced change in chitin content. Furthermore, isolates ofC. albicans,C. krusei,C. parapsilosis, andC. guilliermondiiwhich were stimulated to have higher chitin levels via activation of the calcineurin and protein kinase C (PKC) signaling pathways had reduced susceptibility to caspofungin. Isolates containing point mutations in theFKS1gene generally had higher chitin levels and did not demonstrate a further compensatory increase in chitin content in response to caspofungin treatment. These results highlight the potential of increased chitin synthesis as a potential mechanism of tolerance to caspofungin for the major pathogenicCandidaspecies.

scholarly journals Dectin-2-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Suresh Ambati ◽  
Emma C. Ellis ◽  
Jianfeng Lin ◽  
Xiaorong Lin ◽  
Zachary A. Lewis ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Aspergillus Fumigatus ◽  
Effective Dose ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Antifungal Drugs ◽  
Extracellular Matrices ◽  
Content Type ◽  
Order Of Magnitude ◽  
Life Threatening

ABSTRACT Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus cause life-threatening candidiasis, cryptococcosis, and aspergillosis, resulting in several hundred thousand deaths annually. The patients at the greatest risk of developing these life-threatening invasive fungal infections have weakened immune systems. The vulnerable population is increasing due to rising numbers of immunocompromised individuals as a result of HIV infection or immunosuppressed individuals receiving anticancer therapies and/or stem cell or organ transplants. While patients are treated with antifungals such as amphotericin B, all antifungals have serious limitations due to lack of sufficient fungicidal effect and/or host toxicity. Even with treatment, 1-year survival rates are low. We explored methods of increasing drug effectiveness by designing fungicide-loaded liposomes specifically targeted to fungal cells. Most pathogenic fungi are encased in cell walls and exopolysaccharide matrices rich in mannans. Dectin-2 is a mammalian innate immune membrane receptor that binds as a dimer to mannans and signals fungal infection. We coated amphotericin-loaded liposomes with monomers of Dectin-2’s mannan-binding domain, sDectin-2. sDectin monomers were free to float in the lipid membrane and form dimers that bind mannan substrates. sDectin-2-coated liposomes bound orders of magnitude more efficiently to the extracellular matrices of several developmental stages of C. albicans, C. neoformans, and A. fumigatus than untargeted control liposomes. Dectin-2-coated amphotericin B-loaded liposomes reduced the growth and viability of all three species more than an order of magnitude more efficiently than untargeted control liposomes and dramatically decreased the effective dose. Future efforts focus on examining pan-antifungal targeted liposomal drugs in animal models of fungal diseases. IMPORTANCE Invasive fungal diseases caused by Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus have mortality rates ranging from 10 to 95%. Individual patient costs may exceed $100,000 in the United States. All antifungals in current use have serious limitations due to host toxicity and/or insufficient fungal cell killing that results in recurrent infections. Few new antifungal drugs have been introduced in the last 2 decades. Hence, there is a critical need for improved antifungal therapeutics. By targeting antifungal-loaded liposomes to α-mannans in the extracellular matrices secreted by these fungi, we dramatically reduced the effective dose of drug. Dectin-2-coated liposomes loaded with amphotericin B bound 50- to 150-fold more strongly to C. albicans, C. neoformans, and A. fumigatus than untargeted liposomes and killed these fungi more than an order of magnitude more efficiently. Targeting drug-loaded liposomes specifically to fungal cells has the potential to greatly enhance the efficacy of most antifungal drugs.

scholarly journals Altered Dynamics of Candida albicans Phagocytosis by Macrophages and PMNs When Both Phagocyte Subsets Are Present

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Fiona M. Rudkin ◽  
Judith M. Bain ◽  
Catriona Walls ◽  
Leanne E. Lewis ◽  
Neil A. R. Gow ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Immune System ◽  
Innate Immune System ◽  
Video Microscopy ◽  
Innate Immune ◽  
Live Cell ◽  
Yeast Cells ◽  
Polymorphonuclear Cells ◽  
Fungal Cell ◽  
Content Type

ABSTRACT An important first line of defense against Candida albicans infections is the killing of fungal cells by professional phagocytes of the innate immune system, such as polymorphonuclear cells (PMNs) and macrophages. In this study, we employed live-cell video microscopy coupled with dynamic image analysis tools to provide insights into the complexity of C. albicans phagocytosis when macrophages and PMNs were incubated with C. albicans alone and when both phagocyte subsets were present. When C. albicans cells were incubated with only one phagocyte subtype, PMNs had a lower overall phagocytic capacity than macrophages, despite engulfing fungal cells at a higher rate once fungal cells were bound to the phagocyte surface. PMNs were more susceptible to C. albicans-mediated killing than macrophages, irrespective of the number of C. albicans cells ingested. In contrast, when both phagocyte subsets were studied in coculture, the two cell types phagocytosed and cleared C. albicans at equal rates and were equally susceptible to killing by the fungus. The increase in macrophage susceptibility to C. albicans-mediated killing was a consequence of macrophages taking up a higher proportion of hyphal cells under these conditions. In the presence of both PMNs and macrophages, C. albicans yeast cells were predominantly cleared by PMNs, which migrated at a greater speed toward fungal cells and engulfed bound cells more rapidly. These observations demonstrate that the phagocytosis of fungal pathogens depends on, and is modified by, the specific phagocyte subsets present at the site of infection. IMPORTANCE Extensive work investigating fungal cell phagocytosis by macrophages and PMNs of the innate immune system has been carried out. These studies have been informative but have examined this phenomenon only when one phagocyte subset is present. The current study employed live-cell video microscopy to break down C. albicans phagocytosis into its component parts and examine the effect of a single phagocyte subset, versus a mixed phagocyte population, on these individual stages. Through this approach, we identified that the rate of fungal cell engulfment and rate of phagocyte killing altered significantly when both macrophages and PMNs were incubated in coculture with C. albicans compared to the rate of either phagocyte subset incubated alone with the fungus. This research highlights the significance of studying pathogen-host cell interactions with a combination of phagocytes in order to gain a greater understanding of the interactions that occur between cells of the host immune system in response to fungal invasion.

scholarly journals Melanin Externalization in Candida albicans Depends on Cell Wall Chitin Structures

2010 ◽  
Vol 9 (9) ◽  
pp. 1329-1342 ◽  
Author(s):  
Claire A. Walker ◽  
Beatriz L. Gómez ◽  
Héctor M. Mora-Montes ◽  
Kevin S. Mackenzie ◽  
Carol A. Munro ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Cell Walls ◽  
Chitin Synthesis ◽  
Melanin Production ◽  
Content Type ◽  
Encoding Gene ◽  
Chitinase Genes

ABSTRACT The fungal pathogen Candida albicans produces dark-pigmented melanin after 3 to 4 days of incubation in medium containing l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. Expression profiling of C. albicans revealed very few genes significantly up- or downregulated by growth in l-DOPA. We were unable to determine a possible role for melanin in the virulence of C. albicans. However, we showed that melanin was externalized from the fungal cells in the form of electron-dense melanosomes that were free or often loosely bound to the cell wall exterior. Melanin production was boosted by the addition of N-acetylglucosamine to the medium, indicating a possible association between melanin production and chitin synthesis. Melanin externalization was blocked in a mutant specifically disrupted in the chitin synthase-encoding gene CHS2. Melanosomes remained within the outermost cell wall layers in chs3Δ and chs2Δ chs3Δ mutants but were fully externalized in chs8Δ and chs2Δ chs8Δ mutants. All the CHS mutants synthesized dark pigment at equivalent rates from mixed membrane fractions in vitro, suggesting it was the form of chitin structure produced by the enzymes, not the enzymes themselves, that was involved in the melanin externalization process. Mutants with single and double disruptions of the chitinase genes CHT2 and CHT3 and the chitin pathway regulator ECM33 also showed impaired melanin externalization. We hypothesize that the chitin product of Chs3 forms a scaffold essential for normal externalization of melanosomes, while the Chs8 chitin product, probably produced in cell walls in greater quantity in the absence of CHS2, impedes externalization.

Rapid determination of binding parameters of chitin binding domains using chitin-coated quartz crystal microbalance sensor chips

The Analyst ◽  
2018 ◽  
Vol 143 (21) ◽  
pp. 5255-5263 ◽  
Author(s):  
Stephan Vogt ◽  
Marco Kelkenberg ◽  
Tanja Nöll ◽  
Benedikt Steinhoff ◽  
Holger Schönherr ◽  
...  
Keyword(s):  
Cell Walls ◽  
Quartz Crystal ◽  
Fungal Infections ◽  
Rapid Determination ◽  
Binding Parameters ◽  
Fungal Cell ◽  
Binding Domains ◽  
Quartz Crystal Microbalance Sensor ◽  
Fungal Cell Walls

Chitin present in fungal cell walls has been considered as a diagnostic polymer for the detection of fungal infections.

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