The role of TNF-α in a murine model of Kawasaki disease arteritis induced with a Candida albicans cell wall polysaccharide

The Candida parapsilosis genome encodes for five agglutinin-like sequence (Als) cell-wall glycoproteins involved in adhesion to biotic and abiotic surfaces. The work presented here is aimed at analyzing the role of the two still uncharacterized ALS genes in C. parapsilosis, CpALS4790 and CpALS0660, by the generation and characterization of CpALS4790 and CpALS066 single mutant strains. Phenotypic characterization showed that both mutant strains behaved as the parental wild type strain regarding growth rate in liquid/solid media supplemented with cell-wall perturbing agents, and in the ability to produce pseudohyphae. Interestingly, the ability of the CpALS0660 null mutant to adhere to human buccal epithelial cells (HBECs) was not altered when compared with the wild-type strain, whereas deletion of CpALS4790 led to a significant loss of the adhesion capability. RT-qPCR analysis performed on the mutant strains in co-incubation with HBECs did not highlight significant changes in the expression levels of others ALS genes. In vivo experiments in a murine model of vaginal candidiasis indicated a significant reduction in CFUs recovered from BALB/C mice infected with each mutant strain in comparison to those infected with the wild type strain, confirming the involvement of CpAls4790 and CpAls5600 proteins in C. parapsilosis vaginal candidiasis in mice.

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Inducible Expression of Human β-Defensin 2 byFusobacterium nucleatum in Oral Epithelial Cells: Multiple Signaling Pathways and Role of Commensal Bacteria in Innate Immunity and the Epithelial Barrier

Infection and Immunity ◽

10.1128/iai.68.5.2907-2915.2000 ◽

2000 ◽

Vol 68 (5) ◽

pp. 2907-2915 ◽

Cited By ~ 284

Author(s):

Suttichai Krisanaprakornkit ◽

Janet R. Kimball ◽

Aaron Weinberg ◽

Richard P. Darveau ◽

Brian W. Bainbridge ◽

...

Keyword(s):

Innate Immunity ◽

Cell Wall ◽

Epithelial Cells ◽

Signaling Pathways ◽

Inducible Expression ◽

Periodontal Pathogen ◽

Gingival Tissue ◽

Necrosis Factor Alpha ◽

Tnf Α

ABSTRACT Human gingival epithelial cells (HGE) express two antimicrobial peptides of the β-defensin family, human β-defensin 1 (hBD-1) and hBD-2, as well as cytokines and chemokines that contribute to innate immunity. In the present study, the expression and transcriptional regulation of hBD-2 was examined. HBD-2 mRNA was induced by cell wall extract of Fusobacterium nucleatum, an oral commensal microorganism, but not by that of Porphyromonas gingivalis, a periodontal pathogen. HBD-2 mRNA was also induced by the proinflammatory cytokine tumor necrosis factor alpha (TNF-α) and phorbol myristate acetate (PMA), an epithelial cell activator. HBD-2 mRNA was also expressed in 14 of 15 noninflamed gingival tissue samples. HBD-2 peptide was detected by immunofluorescence in HGE stimulated with F. nucleatum cell wall, consistent with induction of the mRNA by this stimulant. Kinetic analysis indicates involvement of multiple distinct signaling pathways in the regulation of hBD-2 mRNA; TNF-α and F. nucleatum cell wall induced hBD-2 mRNA rapidly (2 to 4 h), while PMA stimulation was slower (∼10 h). In contrast, each stimulant induced interleukin 8 (IL-8) within 1 h. The role of TNF-α as an intermediary in F. nucleatum signaling was ruled out by addition of anti-TNF-α that did not inhibit hBD-2 induction. However, inhibitor studies show that F. nucleatum stimulation of hBD-2 mRNA requires both new gene transcription and new protein synthesis. Bacterial lipopolysaccharides isolated from Escherichia coli andF. nucleatum were poor stimulants of hBD-2, although they up-regulated IL-8 mRNA. Collectively, our findings show inducible expression of hBD-2 mRNA via multiple pathways in HGE in a pattern that is distinct from that of IL-8 expression. We suggest that different aspects of innate immune responses are differentially regulated and that commensal organisms have a role in stimulating mucosal epithelial cells in maintaining the barrier that contributes to homeostasis and host defense.

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Physiologic Expression of the Candida albicans Pescadillo Homolog Is Required for Virulence in a Murine Model of Hematogenously Disseminated Candidiasis

Eukaryotic Cell ◽

10.1128/ec.00171-12 ◽

2012 ◽

Vol 11 (12) ◽

pp. 1552-1556 ◽

Cited By ~ 5

Author(s):

Priya Uppuluri ◽

Ashok K. Chaturvedi ◽

Niketa Jani ◽

Read Pukkila-Worley ◽

Carlos Monteagudo ◽

...

Keyword(s):

Candida Albicans ◽

Murine Model ◽

Critical Role ◽

Growth Defect ◽

Mammalian Host ◽

Developmental Cycle ◽

Yeast Growth ◽

Content Type ◽

Disseminated Candidiasis

ABSTRACT Morphogenetic conversions contribute to the pathogenesis of Candida albicans invasive infections. Many studies to date have convincingly demonstrated a link between filamentation and virulence; however, relatively little is known regarding the role of the filament-to-yeast transition during the pathogenesis of invasive candidiasis. We previously identified the C. albicans pescadillo homolog ( PES1 ) as essential during yeast growth and growth of lateral yeast on hyphae but not during hyphal growth. Furthermore, we demonstrated that PES1 is required for virulence in vivo in a Galleria mellonella larva model of candidiasis. Here, we have used a regulatable tetO-PES1 / pes1 strain to assess the contribution of C. albicans PES1 to pathogenesis in the commonly used and clinically relevant murine model of hematogenously disseminated candidiasis. Our results indicate that a physiologically controlled level of PES1 expression is required for full virulence in this animal model, with virulence defects observed both when PES1 is overexpressed and and when it is depleted. The pathogenetic defect of cells depleted of PES1 is not due to a general growth defect, as demonstrated by the fact that PES1 -depleted cells still kill Caenorhabditis elegans as efficiently as the wild type due to hyphal outgrowth through worm tissues. Our results suggest a critical role of lateral yeast growth in the ability of C. albicans to normally proliferate within tissues, as well as a pivotal role for Pes1 in the normal developmental cycle of C. albicans within the mammalian host during infection.

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Nanoscopic cell-wall architecture of an immunogenic ligand in Candida albicans during antifungal drug treatment

Molecular Biology of the Cell ◽

10.1091/mbc.e15-06-0355 ◽

2016 ◽

Vol 27 (6) ◽

pp. 1002-1014 ◽

Cited By ~ 19

Author(s):

Jia Lin ◽

Michael J. Wester ◽

Matthew S. Graus ◽

Keith A. Lidke ◽

Aaron K. Neumann

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Cell Walls ◽

Innate Immune ◽

Immune Recognition ◽

Cell Wall Polysaccharide ◽

Stochastic Optical Reconstruction Microscopy ◽

Before And After ◽

Antifungal Chemotherapy ◽

Optical Reconstruction

The cell wall of Candida albicans is composed largely of polysaccharides. Here we focus on β-glucan, an immunogenic cell-wall polysaccharide whose surface exposure is often restricted, or “masked,” from immune recognition by Dectin-1 on dendritic cells (DCs) and other innate immune cells. Previous research suggested that the physical presentation geometry of β-glucan might determine whether it can be recognized by Dectin-1. We used direct stochastic optical reconstruction microscopy to explore the fine structure of β-glucan exposed on C. albicans cell walls before and after treatment with the antimycotic drug caspofungin, which alters glucan exposure. Most surface-accessible glucan on C. albicans yeast and hyphae is limited to isolated Dectin-1–binding sites. Caspofungin-induced unmasking caused approximately fourfold to sevenfold increase in total glucan exposure, accompanied by increased phagocytosis efficiency of DCs for unmasked yeasts. Nanoscopic imaging of caspofungin-unmasked C. albicans cell walls revealed that the increase in glucan exposure is due to increased density of glucan exposures and increased multiglucan exposure sizes. These findings reveal that glucan exhibits significant nanostructure, which is a previously unknown physical component of the host– Candida interaction that might change during antifungal chemotherapy and affect innate immune activation.

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Mannan molecular sub-structures control nanoscale glucan exposure in Candida

10.1101/215632 ◽

2017 ◽

Author(s):

Matthew S. Graus ◽

Michael J. Wester ◽

Douglas W. Lowman ◽

David L. Williams ◽

Michael D. Kruppa ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Super Resolution ◽

Ligand Interaction ◽

Interaction Sites ◽

Single Receptor ◽

Labile N ◽

Innate Immune Evasion ◽

Acid Labile

AbstractN-linked mannans (N-mannans) in the cell wall of Candida albicans are thought to mask β-(1,3)-glucan from recognition by Dectin-1, contributing to innate immune evasion. Lateral cell wall exposures of glucan on Candida albicans are predominantly single receptor-ligand interaction sites and are restricted to nanoscale geometries. Candida species exhibit a range of basal glucan exposures and their mannans also vary in size and complexity at the molecular level. We used super resolution fluorescence imaging and a series of protein mannosylation mutants in C. albicans and C. glabrata to investigate the role of specific N-mannan features in regulating the nanoscale geometry of glucan exposure. Decreasing acid labile mannan abundance and α-(1,6)-mannan backbone length correlated most strongly with increased density and nanoscopic size of glucan exposures in C. albicans and C. glabrata, respectively. Additionally, a C. albicans clinical isolate with high glucan exposure produced similarly perturbed N-mannan structures and exhibited similar changes to nanoscopic glucan exposure geometry. We conclude that acid labile N-mannan controls glucan exposure geometry at the nanoscale. Furthermore, variations in glucan nanoexposure characteristics are clinically relevant and are likely to impact the nature of the pathogenic surface presented to innate immunocytes at dimensions relevant to receptor engagement, aggregation and signaling.

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