SSD1 Is Integral to Host Defense Peptide Resistance in Candida albicans

ABSTRACT Candida albicans is usually a harmless human commensal. Because inflammatory responses are not normally induced by colonization, antimicrobial peptides are likely integral to first-line host defense against invasive candidiasis. Thus, C. albicans must have mechanisms to tolerate or circumvent molecular effectors of innate immunity and thereby colonize human tissues. Prior studies demonstrated that an antimicrobial peptide-resistant strain of C. albicans, 36082R, is hypervirulent in animal models versus its susceptible counterpart (36082S). The current study aimed to identify a genetic basis for antimicrobial peptide resistance in C. albicans. Screening of a C. albicans genomic library identified SSD1 as capable of conferring peptide resistance to a susceptible surrogate, Saccharomyces cerevisiae. Sequencing confirmed that the predicted translation products of 36082S and 36082R SSD1 genes were identical. However, Northern analyses corroborated that SSD1 is expressed at higher levels in 36082R than in 36082S. In isogenic backgrounds, ssd1Δ/ssd1Δ null mutants were significantly more susceptible to antimicrobial peptides than parental strains but had equivalent susceptibilities to nonpeptide stressors. Moreover, SSD1 complementation of ssd1Δ/ssd1Δ mutants restored parental antimicrobial peptide resistance phenotypes, and overexpression of SSD1 conferred enhanced peptide resistance. Consistent with these in vitro findings, ssd1 null mutants were significantly less virulent in a murine model of disseminated candidiasis than were their parental or complemented strains. Collectively, these results indicate that SSD1 is integral to C. albicans resistance to host defense peptides, a phenotype that appears to enhance the virulence of this organism in vivo.

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Bcr1 Functions Downstream of Ssd1 To Mediate Antimicrobial Peptide Resistance in Candida albicans

Eukaryotic Cell ◽

10.1128/ec.00285-12 ◽

2013 ◽

Vol 12 (3) ◽

pp. 411-419 ◽

Cited By ~ 14

Author(s):

Sook-In Jung ◽

Jonathan S. Finkel ◽

Norma V. Solis ◽

Siyang Chaili ◽

Aaron P. Mitchell ◽

...

Keyword(s):

Candida Albicans ◽

Antimicrobial Peptides ◽

Antimicrobial Peptide ◽

Target Genes ◽

Regulatory Protein ◽

Homozygous Deletion ◽

Plasma Membrane Permeability ◽

Host Defense Peptides ◽

Content Type ◽

Antimicrobial Peptide Resistance

ABSTRACTIn order to colonize the host and cause disease,Candida albicansmust avoid being killed by host defense peptides. Previously, we determined that the regulatory protein Ssd1 governs antimicrobial peptide resistance inC. albicans. Here, we sought to identify additional genes whose products govern susceptibility to antimicrobial peptides. We discovered that abcr1Δ/Δ mutant, like thessd1Δ/Δ mutant, had increased susceptibility to the antimicrobial peptides, protamine, RP-1, and human β defensin-2. Homozygous deletion ofBCR1in thessd1Δ/Δ mutant did not result in a further increase in antimicrobial peptide susceptibility. Exposure of thebcr1Δ/Δ andssd1Δ/Δ mutants to RP-1 induced greater loss of mitochondrial membrane potential and increased plasma membrane permeability than with the control strains. Therefore, Bcr1 and Ssd1 govern antimicrobial peptide susceptibility and likely function in the same pathway. Furthermore,BCR1mRNA expression was downregulated in thessd1Δ/Δ mutant, and the forced expression ofBCR1in thessd1Δ/Δ mutant partially restored antimicrobial peptide resistance. These results suggest that Bcr1 functions downstream of Ssd1. Interestingly, overexpression of 11 known Bcr1 target genes in thebcr1Δ/Δ mutant failed to restore antimicrobial peptide resistance, suggesting that other Bcr1 target genes are likely responsible for antimicrobial peptide resistance. Collectively, these results demonstrate that Bcr1 functions downstream of Ssd1 to govern antimicrobial peptide resistance by maintaining mitochondrial energetics and reducing membrane permeabilization.

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Augmentation of Innate Host Defense by Expression of a Cathelicidin Antimicrobial Peptide

Infection and Immunity ◽

10.1128/iai.67.11.6084-6089.1999 ◽

1999 ◽

Vol 67 (11) ◽

pp. 6084-6089 ◽

Cited By ~ 197

Author(s):

Robert Bals ◽

Daniel J. Weiner ◽

A. David Moscioni ◽

Rupalie L. Meegalla ◽

James M. Wilson

Keyword(s):

Antimicrobial Peptides ◽

Antimicrobial Peptide ◽

Intravenous Injection ◽

Host Defense ◽

Recombinant Adenovirus ◽

Bacterial Load ◽

Survival Rates ◽

Innate Immune

ABSTRACT Antimicrobial peptides, such as defensins or cathelicidins, are effector substances of the innate immune system and are thought to have antimicrobial properties that contribute to host defense. The evidence that vertebrate antimicrobial peptides contribute to innate immunity in vivo is based on their expression pattern and in vitro activity against microorganisms. The goal of this study was to investigate whether the overexpression of an antimicrobial peptide results in augmented protection against bacterial infection. C57BL/6 mice were given an adenovirus vector containing the cDNA for LL-37/hCAP-18, a human cathelicidin antimicrobial peptide. Mice treated with intratracheal LL-37/hCAP-18 vector had a lower bacterial load and a smaller inflammatory response than did untreated mice following pulmonary challenge with Pseudomonas aeruginosa PAO1. Systemic expression of LL-37/hCAP-18 after intravenous injection of recombinant adenovirus resulted in improved survival rates following intravenous injection of lipopolysaccharide with galactosamine or Escherichia coli CP9. In conclusion, the data demonstrate that expression of an antimicrobial peptide by gene transfer results in augmentation of the innate immune response, providing support for the hypothesis that vertebrate antimicrobial peptides protect against microorganisms in vivo.

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Mechanistic Fingerprinting Reveals Kinetic Signatures of Resistance to Daptomycin and Host Defense Peptides in Streptococcus mitis-oralis

Antibiotics ◽

10.3390/antibiotics10040404 ◽

2021 ◽

Vol 10 (4) ◽

pp. 404

Author(s):

Michael R. Yeaman ◽

Liana C. Chan ◽

Nagendra N. Mishra ◽

Arnold S. Bayer

Keyword(s):

Flow Cytometry ◽

Host Defense ◽

Durable Resistance ◽

Cross Resistance ◽

Streptococcus Mitis ◽

Host Defense Peptides ◽

Strain Pair ◽

Defense Peptides

Streptococcus mitis-oralis (S. mitis-oralis) infections are increasingly prevalent in specific populations, including neutropenic cancer and endocarditis patients. S. mitis-oralis strains have a propensity to evolve rapid, high-level and durable resistance to daptomycin (DAP-R) in vitro and in vivo, although the mechanism(s) involved remain incompletely defined. We examined mechanisms of DAP-R versus cross-resistance to cationic host defense peptides (HDPs), using an isogenic S. mitis-oralis strain-pair: (i) DAP-susceptible (DAP-S) parental 351-WT (DAP MIC = 0.5 µg/mL), and its (ii) DAP-R variant 351-D10 (DAP MIC > 256 µg/mL). DAP binding was quantified by flow cytometry, in-parallel with temporal (1–4 h) killing by either DAP or comparative prototypic cationic HDPs (hNP-1; LL-37). Multicolor flow cytometry was used to determine kinetic cell responses associated with resistance or susceptibility to these molecules. While overall DAP binding was similar between strains, a significant subpopulation of 351-D10 cells hyper-accumulated DAP (>2–4-fold vs. 351-WT). Further, both DAP and hNP-1 induced cell membrane (CM) hyper-polarization in 351-WT, corresponding to significantly greater temporal DAP-killing (vs. 351-D10). No strain-specific differences in CM permeabilization, lipid turnover or regulated cell death were observed post-exposure to DAP, hNP-1 or LL-37. Thus, the adaptive energetics of the CM appear coupled to the outcomes of interactions of S. mitis-oralis with DAP and selected HDPs. In contrast, altered CM permeabilization, proposed as a major mechanism of action of both DAP and HDPs, did not differentiate DAP-S vs. DAP-R phenotypes in this S. mitis-oralis strain-pair.

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An iron-regulated LysR-type element mediates antimicrobial peptide resistance and virulence in Yersinia pseudotuberculosis

Microbiology ◽

10.1099/mic.0.026690-0 ◽

2009 ◽

Vol 155 (7) ◽

pp. 2168-2181 ◽

Cited By ~ 10

Author(s):

Sonia Arafah ◽

Marie-Laure Rosso ◽

Linda Rehaume ◽

Robert E. W. Hancock ◽

Michel Simonet ◽

...

Keyword(s):

Antimicrobial Peptide ◽

Yersinia Pseudotuberculosis ◽

Polymyxin B ◽

Uptake System ◽

Mesenteric Lymph Nodes ◽

Iron Starvation ◽

Iron Deprivation ◽

Genes Encoding ◽

Antimicrobial Peptide Resistance

During the course of its infection of the mammalian digestive tract, the entero-invasive, Gram-negative bacterium Yersinia pseudotuberculosis must overcome various hostile living conditions (notably, iron starvation and the presence of antimicrobial compounds produced in situ). We have previously reported that in vitro bacterial growth during iron deprivation raises resistance to the antimicrobial peptide polymyxin B; here, we show that this phenotype is mediated by a chromosomal gene (YPTB0333) encoding a transcriptional regulator from the LysR family. We determined that the product of YPTB0333 is a pleiotropic regulator which controls (in addition to its own expression) genes encoding the Yfe iron-uptake system and polymyxin B resistance. Lastly, by using a mouse model of oral infection, we demonstrated that YPTB0333 is required for colonization of Peyer's patches and mesenteric lymph nodes by Y. pseudotuberculosis.

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Human β-Defensin 3 Inhibits Cell Wall Biosynthesis in Staphylococci

Infection and Immunity ◽

10.1128/iai.00688-09 ◽

2010 ◽

Vol 78 (6) ◽

pp. 2793-2800 ◽

Cited By ~ 164

Author(s):

Vera Sass ◽

Tanja Schneider ◽

Miriam Wilmes ◽

Christian Körner ◽

Alessandro Tossi ◽

...

Keyword(s):

Electron Microscopy ◽

Cell Wall ◽

Host Defense ◽

Transcriptional Response ◽

Cell Wall Biosynthesis ◽

Host Defense Peptides ◽

Lipid Ii ◽

Transmission Electron ◽

Host Defense Peptide

ABSTRACT Human β-defensin 3 (hBD3) is a highly charged (+11) cationic host defense peptide, produced by epithelial cells and neutrophils. hBD3 retains antimicrobial activity against a broad range of pathogens, including multiresistant Staphylococcus aureus, even under high-salt conditions. Whereas antimicrobial host defense peptides are assumed to act by permeabilizing cell membranes, the transcriptional response pattern of hBD3-treated staphylococcal cells resembled that of vancomycin-treated cells (V. Sass, U. Pag, A. Tossi, G. Bierbaum, and H. G. Sahl, Int. J. Med. Microbiol. 298:619-633, 2008) and suggested that inhibition of cell wall biosynthesis is a major component of the killing process. hBD3-treated cells, inspected by transmission electron microscopy, showed localized protrusions of cytoplasmic contents, and analysis of the intracellular pool of nucleotide-activated cell wall precursors demonstrated accumulation of the final soluble precursor, UDP-MurNAc-pentapeptide. Accumulation is typically induced by antibiotics that inhibit membrane-bound steps of cell wall biosynthesis and also demonstrates that hBD3 does not impair the biosynthetic capacity of cells and does not cause gross leakage of small cytoplasmic compounds. In in vitro assays of individual membrane-associated cell wall biosynthesis reactions (MraY, MurG, FemX, and penicillin-binding protein 2 [PBP2]), hBD3 inhibited those enzymes which use the bactoprenol-bound cell wall building block lipid II as a substrate; quantitative analysis suggested that hBD3 may stoichiometrically bind to lipid II. We report that binding of hBD3 to defined, lipid II-rich sites of cell wall biosynthesis may lead to perturbation of the biosynthesis machinery, resulting in localized lesions in the cell wall as demonstrated by electron microscopy. The lesions may then allow for osmotic rupture of cells when defensins are tested under low-salt conditions.

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Anti-Inflammatory Effects of Vitamin E in Response to Candida albicans

Microorganisms ◽

10.3390/microorganisms8060804 ◽

2020 ◽

Vol 8 (6) ◽

pp. 804

Author(s):

Silvana Barros ◽

Ana Paula D. Ribeiro ◽

Steven Offenbacher ◽

Zvi G. Loewy

Keyword(s):

Candida Albicans ◽

Vitamin E ◽

Inflammatory Responses ◽

Arachidonic Acid Metabolism ◽

Experimental Conditions ◽

Mrna Extraction ◽

Anti Inflammatory ◽

Nf Kappab ◽

Pathway Analyses

Oral mucositis, inflammation, and ulceration that occur in the oral cavity can manifest in significant pain. A formulation was designed to investigate the potential of vitamin E to ameliorate inflammation resulting from Candida albicans in cell-based systems. Human gingival fibroblasts and THP1 cells were stimulated with heat killed C. albicans and Porphyromonas gingivalis LPS (agonists). Unstimulated cells were included as controls. Cells were also simultaneously treated with a novel denture adhesive formulation that contains vitamin E (antagonist). The experimental conditions included cells exposed to the experimental formulation or the vehicle for 2 h for mRNA extraction and analysis, and cells left for 24 h under those experimental conditions for analysis of protein expression by ELISA. ssAffymetrix expression microarray pathway analyses demonstrated that the tested formulation exhibited a statistically significant (p < 0.05) inhibition of the following key inflammatory pathways: TLR 6, IL-1 signaling (IRAK, A20), NF-kappaB, IL-6 signaling (gp130, JK2 and GRB2), TNF signaling (TNF receptor) and Arachidonic acid metabolism (PLA2). Quantitative PCR array analysis confirmed the downregulation of key inflammatory genes when cells under adhesive treatment were challenged with heat killed C. albicans. PGE2 secretion was inhibited by the tested formulation only on THP1 cells after 24 h stimulation with C. albicans. These results suggest that the active formulation containing vitamin E acetate can modulate inflammatory responses, through anti-inflammatory actions as indicated by in vitro experimental conditions.

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Lipocalin 2: A New Antimicrobial in Mast Cells

International Journal of Molecular Sciences ◽

10.3390/ijms20102380 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2380 ◽

Cited By ~ 2

Author(s):

Yu-Ling Chang ◽

Zhenping Wang ◽

Satomi Igawa ◽

Jae Eun Choi ◽

Tyler Werbel ◽

...

Keyword(s):

Mast Cells ◽

Antimicrobial Peptides ◽

Antimicrobial Peptide ◽

Bacterial Growth ◽

Immune Defense ◽

Lipocalin 2 ◽

Vitro Assay ◽

E Coli ◽

Sphingosine 1 Phosphate

Mast cells (MCs) play a significant role in the innate immune defense against bacterial infection through the release of cytokines and antimicrobial peptides. However, their antimicrobial function is still only partially described. We therefore hypothesized that MCs express additional antimicrobial peptides. In this study, we used FANTOM 5 transcriptome data to identify for the first time that MCs express lipocalin 2 (LCN2), a known inhibitor of bacterial growth. Using MCs derived from mice which were deficient in LCN2, we showed that this antimicrobial peptide is an important component of the MCs’ antimicrobial activity against Escherichia coli (E. coli). Since sphingosine-1-phosphate receptors (S1PRs) on MCs are known to regulate their function during infections, we hypothesized that S1P could activate LCN2 production in MCs. Using an in vitro assay, we demonstrated that S1P enhances MCs antimicrobial peptide production and increases the capacity of MCs to directly kill S. aureus and E. coli via an LCN2 release. In conclusion, we showed that LCN2 is expressed by MCs and plays a role in their capacity to inhibit bacterial growth.

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Host Defense Peptides in the Oral Cavity and the Lung: Similarities and Differences

Journal of Dental Research ◽

10.1177/154405910808701011 ◽

2008 ◽

Vol 87 (10) ◽

pp. 915-927 ◽

Cited By ~ 99

Author(s):

G. Diamond ◽

N. Beckloff ◽

L.K. Ryan

Keyword(s):

Oral Cavity ◽

Host Defense ◽

Gingival Crevicular Fluid ◽

Immune Defense ◽

The Body ◽

Microbial Colonization ◽

Host Defense Peptides ◽

Innate Defense ◽

Defense Peptides

Peptides with broad-spectrum antimicrobial activity are found in the mucosal surfaces at many sites in the body, including the airway, the oral cavity, and the digestive tract. Based on their in vitro antimicrobial and other immunomodulatory activities, these host defense peptides have been proposed to play an important role in the innate defense against pathogenic microbial colonization. The genes that encode these peptides are up-regulated by pathogens, further supporting their role in innate immune defense. However, the differences in the local microbial environments between the generally sterile airway and the highly colonized oral cavity suggest a more complex role for these peptides in innate immunity. For example, β-defensin genes are induced in the airway by all bacteria and Toll-like receptor (TLR) agonists primarily through an NF-κB-mediated pathway. In contrast, the same genes are induced in the gingival epithelium by only a subset of bacteria and TLR ligands, via different pathways. Furthermore, the environments into which the peptides are secreted—specifically saliva, gingival crevicular fluid, and airway surface fluid—differ greatly and can effect their respective activities in host defense. In this review, we examine the differences and similarities between host defense peptides in the oral cavity and the airway, to gain a better understanding of their contributions to immunity.

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Susceptibility to Thrombin-Induced Platelet Microbicidal Protein Is Associated with Increased Fluconazole Efficacy against Experimental Endocarditis Due to Candida albicans

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.8.3051-3056.2004 ◽

2004 ◽

Vol 48 (8) ◽

pp. 3051-3056 ◽

Cited By ~ 18

Author(s):

Michael R. Yeaman ◽

Darwin Cheng ◽

Bhavesh Desai ◽

Leon I. Kupferwasser ◽

Yan-Qiong Xiong ◽

...

Keyword(s):

Candida Albicans ◽

Host Defense ◽

Rabbit Model ◽

Fungal Burden ◽

Treatment Groups ◽

Time Points ◽

Platelet Microbicidal Protein ◽

The Relationship

ABSTRACT Platelet microbicidal proteins (PMPs) are believed to be integral to host defense against endovascular infection. We previously demonstrated that susceptibility to thrombin-induced PMP 1 (tPMP-1) in vitro negatively influences Candida albicans virulence in the rabbit model of infective endocarditis (IE). This study evaluated the relationship between in vitro tPMP-1 susceptibility (tPMP-1s) or resistance (tPMP-1r) and efficacy of fluconazole (FLU) therapy of IE due to C. albicans. Candida IE was established in rabbits with either tPMP-1s or tPMP-1r strains. Treatment groups received FLU (100 mg/kg/day) intraperitoneally for 7 or 14 days; control animals received no therapy. At these time points, cardiac vegetations, kidneys, and spleens were quantitatively cultured to assess fungal burden. At both 7 and 14 days and in all target tissues, the extent of candidal clearance by FLU was greater in animals infected with the tPMP-1s strain than in those infected with the tPMP-1r strain. These differences were statistically significant in the spleen and kidney. Corroborating these in vivo data, FLU (a candidastatic agent), in combination with tPMP-1, exerted an enhanced fungicidal effect in vitro against tPMP-1s and tPMP-1r C. albicans, with the extent of this effect greatest against the tPMP-1s strain. Collectively, these results support the concept that tPMP-1 susceptibility contributes to the net efficacy of FLU against C. albicans IE in vivo, particularly in tissues in which platelets and tPMP-1 likely play significant roles in host defense.

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A Paneth cell analogue in Xenopus small intestine expresses antimicrobial peptide genes: conservation of an intestinal host-defense system.

Journal of Histochemistry & Cytochemistry ◽

10.1177/42.6.8189032 ◽

1994 ◽

Vol 42 (6) ◽

pp. 697-704 ◽

Cited By ~ 30

Author(s):

D S Reilly ◽

N Tomassini ◽

C L Bevins ◽

M Zasloff

Keyword(s):

Small Intestine ◽

Antimicrobial Peptides ◽

Antimicrobial Peptide ◽

Host Defense ◽

Cellular Localization ◽

Paneth Cell ◽

Host Defense System ◽

A Cell ◽

Peptide Gene ◽

A Site

Antimicrobial peptides are a widespread component of host defense. We characterized the tissue distribution and cellular localization of expression of the magainin family of antimicrobial peptide genes in Xenopus laevis. Two genes from this family, magainin and PGLa, are expressed at high levels in the skin and throughout the gastrointestinal tract. Magainin and PGLa mRNAs are synthesized in the granular multinucleated cell (GMC) of the gastric mucosa, a cell shown previously to contain magainin and PGLa peptides by immunohistochemical methods. In addition, we have localized magainin and PGLa mRNAs to distinct cells of Xenopus small intestine. Further characterization of this large, granule-filled cell by electron microscopy demonstrates features in common with the Paneth cell of mammalian small intestine, previously identified as a site of expression of antimicrobial peptide genes of the defensin family in mouse and human. Our identification of granule-laden, eosinophilic intestinal cells in Xenopus as a site of magainin and PGLa antimicrobial peptide gene expression suggests that these cells are functional analogues of mammalian Paneth cells and further supports a conserved role of antimicrobial peptides in host defense of the vertebrate small intestine.

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