scholarly journals A Competitive Infection Model of Hematogenously Disseminated Candidiasis in Mice Redefines the Role ofCandida albicans IRS4in Pathogenesis

2013 ◽  
Vol 81 (5) ◽  
pp. 1430-1438 ◽  
Author(s):  
Suresh B. Raman ◽  
M. Hong Nguyen ◽  
Shaoji Cheng ◽  
Hassan Badrane ◽  
Kenneth A. Iczkowski ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Infection Model ◽  
Polymorphonuclear Cells ◽  
Single Strain ◽  
Disseminated Candidiasis ◽  
Ofcandida Albicans ◽  
Mouse Macrophages ◽  
Competition Assays ◽  
Increased Susceptibility

ABSTRACTCandida albicans IRS4encodes a protein that regulates phosphatidylinositol-(4,5)-bisphosphate, which was shown to contribute to hematogenously disseminated candidiasis (DC) after several days in the standard mouse model. Our objective was to more accurately define the temporal contributions ofIRS4to pathogenesis. During competition assaysin vitro, anirs4-null (Δirs4) mutant exhibited wild-type fitness. In DC experiments, mice were infected intravenously with the Δirs4mutant, strain CAI-12 (1 × 105CFU), or a mixture of the strains (0.5 × 105CFU each). In single-strain infections, quantitative PCR revealed reduced Δirs4mutant burdens within kidneys at days 1, 4, and 7 but not 6 h. In competitive infections, the Δirs4mutant was outcompeted by CAI-12 in each mouse at ≥6 h (competitive indices,P≤ 0.0001). At 4 and 7 days, the Δirs4mutant burdens during competitive infections were significantly lower than those during single-strain infections (P= 0.01 andP< 0.001, respectively), suggesting increased susceptibility to inflammatory responses. Phagocytic infiltration of kidneys in response to CAI-12 or competitive infections was significantly greater than that in response to Δirs4mutant infection at days 1 and 4 (P< 0.001), and the Δirs4mutant was more susceptible to phagocytosis and killing by human polymorphonuclear cells (P= 0.01 andP= 0.006, respectively) and mouse macrophagesin vitro(P= 0.04 andP= 0.01, respectively). Therefore,IRS4contributes to tissue invasion at early stages of DC and mediates resistance to phagocytosis as DC progresses. Microarray analysis revealed remarkably similar gene expression by the Δirs4mutant and reference strain CAI-12 within blood, suggesting thatIRS4is not significantly involved in the hematogenous stage of disease. A competitive DC model detects attenuated virulence that is not evident with the standard model.

scholarly journals Effect of Gold Nanoparticles on the TLR2-Mediated Inflammatory Responses Induced by Leptospira in TLR2-Overexpressed HEK293 Cells

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2522
Author(s):  
Kanidta Sooklert ◽  
Chawikan Boonwong ◽  
Pattama Ekpo ◽  
Rojrit Rojanathanes ◽  
Kanitha Patarakul ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Proinflammatory Cytokines ◽  
Inflammatory Responses ◽  
Hek293 Cells ◽  
Infection Model ◽  
Tlr2 Expression ◽  
Inflammatory Parameters ◽  
Factor Α ◽  
20 Nm

Leptospira infection can cause potential hazards to human health by stimulating inflammation, which is mediated mainly through the Toll-like receptor 2 (TLR2) pathway. Gold nanoparticles (AuNPs) are promising for medical applications, as they display both bioinert and noncytotoxic characteristics. AuNPs have been shown to have the ability to modify immune responses. To understand the in vitro immunomodulatory effect of AuNPs in a Leptospira infection model, the activation of TLR2 expression was examined in HEK-Blue-hTLR2 cells treated with Leptospira serovars and/or AuNPs (10 and 20 nm). The ability of AuNPs to modulate an inflammatory response induced by Leptospira was examined in terms of transcript expression level modulation of three proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1β and IL-6) using two-stage quantitative real-time reverse transcriptase PCR. The results revealed that the administration of 10 nm AuNPs could augment the Leptospira-induced TLR2 signaling response and upregulate the expression of all three cytokine gene transcripts, whereas the 20 nm AuNPs attenuated the TLR2 activation and expression of proinflammatory cytokines. This indicates that AuNPs can modulate inflammatory parameters in Leptospira infection and different-sized AuNPs had different immunomodulatory functions in this model.

scholarly journals Characterization and Quantitation of the Pharmacodynamics of Fluconazole in a Neutropenic Murine Disseminated Candidiasis Infection Model

1999 ◽  
Vol 43 (9) ◽  
pp. 2116-2120 ◽  
Author(s):  
D. Andes ◽  
M. van Ogtrop
Keyword(s):  
Time Course ◽  
Infection Model ◽  
Maximal Effect ◽  
Time Curve ◽  
In Vitro Susceptibility ◽  
Disseminated Candidiasis ◽  
Wide Range ◽  
Dosing Intervals ◽  
Dose Dependent

ABSTRACT We determined the pharmacodynamic parameter and the magnitude of that parameter that was predictive of the efficacy of fluconazole in the treatment of disseminated candidiasis. We used a neutropenic murine model of disseminated Candida albicans infection to characterize the time course of activity of fluconazole. Quantitation of colony counts in kidneys after 24 h of therapy with a wide range of doses and three dosing intervals was used to determine the dose required to achieve 50% of the maximal effect (ED50). The ED50 was similar for each of the dosing intervals studied, supporting the area under the concentration-time curve (AUC) MIC ratio as the parameter that predicts the efficacy of fluconazole. Similar studies were performed with C. albicans strains for which fluconazole MICs are in the susceptible-dose-dependent range (MICs, 16 to 32 mg/liter). We found that the magnitude of the AUC/MIC ratio required to reach the ED50 was similar for all three organisms studied, ranging from 12 to 25. When the pharmacokinetics of fluconazole in humans are considered, these AUC/MIC ratios would support in vitro susceptibility breakpoints of 8 mg/liter for dosages of 200 mg/day and susceptibility breakpoints of 16 to 32 mg/liter for dosages of 400 to 800 mg/day.

scholarly journals Simulated Antibiotic Exposures in anIn VitroHollow-Fiber Infection Model Influence Toxin Gene Expression and Production in Community-Associated Methicillin-Resistant Staphylococcus aureus Strain MW2

2011 ◽  
Vol 56 (1) ◽  
pp. 140-147 ◽  
Author(s):  
Solen Pichereau ◽  
Madhulatha Pantrangi ◽  
William Couet ◽  
Cedric Badiou ◽  
Gerard Lina ◽  
...  
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Hollow Fiber ◽  
Aureus Strain ◽  
Enzyme Linked Immunosorbent Assay ◽  
Infection Model ◽  
Toxin Gene ◽  
Polymorphonuclear Cells ◽  
Methicillin Resistant

ABSTRACTCommunity-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) strain MW2 harbors a plethora of toxins to mediate its virulence. However, toxin expression and regulation with simulated clinical antimicrobial exposures are unclear. This study evaluated these relationships using anin vitropharmacodynamic hollow-fiber infection model. Clinical doses of clindamycin, linezolid, minocycline, trimethoprim-sulfamethoxazole (SXT), and vancomycin were simulated over 72 h against MW2 in the hollow fiber model. Expression levels oflukSF-PVand enterotoxin genessec4,sek,seq, andsel2were quantified by real-time PCR. Panton-Valentine leukocidin (PVL) was quantified by enzyme-linked immunosorbent assay (ELISA), and cytotoxicity was determined on polymorphonuclear cells (PMNs). Vancomycin produced the maximum MW2 killing (2.53 log10CFU/ml) after the first dose, but the greatest sustained killing over 72 h occurred with linezolid and clindamycin. Vancomycin and minocycline induced gene upregulation from 0 to 8 h, followed by downregulation for the remaining simulation period. Clindamycin decreased gene expression in the first 24 h, followed by moderate increases (2.5-fold) thereafter. Linezolid increased gene expression 11.4- to 200.4-fold but inhibited PVL production (0.6 ± 0.3 versus 5.9 ± 0.2 μg/ml, linezolid versus control at 72 h;P< 0.05). Similar effects on PVL production occurred with clindamycin and minocycline. SXT increased PVL production at 48 h (2.8-fold) and 72 h (4.9-fold) of treatment (P< 0.05), resulting in increased PVL cytotoxicity on PMNs. Linezolid, clindamycin, and minocycline were the most effective agents on decreasing the virulence potential in CA-MRSA, notably after 8 h of treatment. SXT had minimal effects on toxin gene regulation, but it increased production and cytotoxicity of PVL toxin in the model and may enhance virulence when it is used to treat severe infections.

scholarly journals Between Amyloids and Aggregation Lies a Connection with Strength and Adhesion

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Peter N. Lipke ◽  
Caleen Ramsook ◽  
Melissa C. Garcia-Sherman ◽  
Desmond N. Jackson ◽  
Cho X. J. Chan ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Human Infection ◽  
Fiber Formation ◽  
Host Responses ◽  
Infection Model ◽  
High Avidity ◽  
Force Microscopy ◽  
Atomic Force ◽  
Fungal Adhesins

We tell of a journey that led to discovery of amyloids formed by yeast cell adhesins and their importance in biofilms and host immunity. We begin with the identification of the adhesin functional amyloid-forming sequences that mediate fiber formation in vitro. Atomic force microscopy and confocal microscopy show 2-dimensional amyloid “nanodomains” on the surface of cells that are activated for adhesion. These nanodomains are arrays of adhesin molecules that bind multivalent ligands with high avidity. Nanodomains form when adhesin molecules are stretched in the AFM or under laminar flow. Treatment with anti-amyloid perturbants or mutation of the amyloid sequence prevents adhesion nanodomain formation and activation. We are now discovering biological consequences. Adhesin nanodomains promote formation and maintenance of biofilms, which are microbial communities. Also, in abscesses within candidiasis patients, we find adhesin amyloids on the surface of the fungi. In both human infection and a Caenorhabditis elegans infection model, the presence of fungal surface amyloids elicits anti-inflammatory responses. Thus, this is a story of how fungal adhesins respond to extension forces through formation of cell surface amyloid nanodomains, with key consequences for biofilm formation and host responses.

scholarly journals Acetylcholine Protects against Candida albicans Infection by Inhibiting Biofilm Formation and Promoting Hemocyte Function in a Galleria mellonella Infection Model

2015 ◽  
Vol 14 (8) ◽  
pp. 834-844 ◽  
Author(s):  
Ranjith Rajendran ◽  
Elisa Borghi ◽  
Monica Falleni ◽  
Federica Perdoni ◽  
Delfina Tosi ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Inflammatory Responses ◽  
Fungal Infections ◽  
Infection Model ◽  
Content Type

ABSTRACT Both neuronal acetylcholine and nonneuronal acetylcholine have been demonstrated to modulate inflammatory responses. Studies investigating the role of acetylcholine in the pathogenesis of bacterial infections have revealed contradictory findings with regard to disease outcome. At present, the role of acetylcholine in the pathogenesis of fungal infections is unknown. Therefore, the aim of this study was to determine whether acetylcholine plays a role in fungal biofilm formation and the pathogenesis of Candida albicans infection. The effect of acetylcholine on C. albicans biofilm formation and metabolism in vitro was assessed using a crystal violet assay and phenotypic microarray analysis. Its effect on the outcome of a C. albicans infection, fungal burden, and biofilm formation were investigated in vivo using a Galleria mellonella infection model. In addition, its effect on modulation of host immunity to C. albicans infection was also determined in vivo using hemocyte counts, cytospin analysis, larval histology, lysozyme assays, hemolytic assays, and real-time PCR. Acetylcholine was shown to have the ability to inhibit C. albicans biofilm formation in vitro and in vivo . In addition, acetylcholine protected G. mellonella larvae from C. albicans infection mortality. The in vivo protection occurred through acetylcholine enhancing the function of hemocytes while at the same time inhibiting C. albicans biofilm formation. Furthermore, acetylcholine also inhibited inflammation-induced damage to internal organs. This is the first demonstration of a role for acetylcholine in protection against fungal infections, in addition to being the first report that this molecule can inhibit C. albicans biofilm formation. Therefore, acetylcholine has the capacity to modulate complex host-fungal interactions and plays a role in dictating the pathogenesis of fungal infections.

scholarly journals Detection of Als Proteins on the Cell Wall ofCandida albicans in Murine Tissues

1999 ◽  
Vol 67 (8) ◽  
pp. 4251-4255 ◽  
Author(s):  
L. L. Hoyer ◽  
J. Clevenger ◽  
J. E. Hecht ◽  
E. J. Ehrhart ◽  
F. M. Poulet
Keyword(s):  
Cell Wall ◽  
Protein Production ◽  
Strain Differences ◽  
Immunohistochemical Analysis ◽  
Disseminated Candidiasis ◽  
Host Pathogen Interaction ◽  
Ofcandida Albicans ◽  
Wall Position

ABSTRACT A murine model of disseminated candidiasis was utilized to determine whether Candida albicans Als proteins are produced in vivo. The kidneys, spleen, heart, liver, and lungs were collected from mice inoculated with one of three C. albicans strains (SC5314, B311, or WO-1). Immunohistochemical analysis of murine tissues by using a rabbit polyclonal anti-Als serum indicated that Als proteins were produced by each C. albicans cell in the tissues examined. Patterns of staining with the anti-Als serum were similar among the C. albicansstrains tested. These data indicated that Als protein production was widespread in disseminated candidiasis and that, despite strain differences in ALS gene expression previously noted in vitro, Als protein production in vivo was similar among C. albicans strains. The extensive production of Als proteins in vivo and their presence on the C. albicans cell wall position these proteins well for a role in host-pathogen interaction.

scholarly journals Sugar administration is an effective adjunctive therapy in the treatment ofPseudomonas aeruginosapneumonia

2013 ◽  
Vol 305 (5) ◽  
pp. L352-L363 ◽  
Author(s):  
Iwona Bucior ◽  
Jason Abbott ◽  
Yuanlin Song ◽  
Michael A. Matthay ◽  
Joanne N. Engel
Keyword(s):  
Antibiotic Therapy ◽  
Adjunctive Therapy ◽  
Bacterial Resistance ◽  
Inflammatory Responses ◽  
Ex Vivo ◽  
Bacterial Attachment ◽  
Lung Damage ◽  
Infection Model ◽  
Sugar Mixture

Treatment of acute and chronic pulmonary infections caused by opportunistic pathogen Pseudomonas aeruginosa is limited by the increasing frequency of multidrug bacterial resistance. Here, we describe a novel adjunctive therapy in which administration of a mix of simple sugars—mannose, fucose, and galactose—inhibits bacterial attachment, limits lung damage, and potentiates conventional antibiotic therapy. The sugar mixture inhibits adhesion of nonmucoid and mucoid P. aeruginosa strains to bronchial epithelial cells in vitro. In a murine model of acute pneumonia, treatment with the sugar mixture alone diminishes lung damage, bacterial dissemination to the subpleural alveoli, and neutrophil- and IL-8-driven inflammatory responses. Remarkably, the sugars act synergistically with anti- Pseudomonas antibiotics, including β-lactams and quinolones, to further reduce bacterial lung colonization and damage. To probe the mechanism, we examined the effects of sugars in the presence or absence of antibiotics during growth in liquid culture and in an ex vivo infection model utilizing freshly dissected mouse tracheas and lungs. We demonstrate that the sugar mixture induces rapid but reversible formation of bacterial clusters that exhibited enhanced susceptibility to antibiotics compared with individual bacteria. Our findings reveal that sugar inhalation, an inexpensive and safe therapeutic, could be used in combination with conventional antibiotic therapy to more effectively treat P. aeruginosa lung infections.

scholarly journals Mast Cell and Eosinophil Activation Are Associated With COVID-19 and TLR-Mediated Viral Inflammation: Implications for an Anti-Siglec-8 Antibody

2021 ◽  
Vol 12 ◽  
Author(s):  
Simon Gebremeskel ◽  
Julia Schanin ◽  
Krysta M. Coyle ◽  
Melina Butuci ◽  
Thuy Luu ◽  
...  
Keyword(s):  
Cell Activation ◽  
Viral Infections ◽  
Immune Cell ◽  
Inflammatory Responses ◽  
Protease Production ◽  
Infection Model ◽  
Health Crisis ◽  
Eosinophil Activation

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection represents a global health crisis. Immune cell activation via pattern recognition receptors has been implicated as a driver of the hyperinflammatory response seen in COVID-19. However, our understanding of the specific immune responses to SARS-CoV-2 remains limited. Mast cells (MCs) and eosinophils are innate immune cells that play pathogenic roles in many inflammatory responses. Here we report MC-derived proteases and eosinophil-associated mediators are elevated in COVID-19 patient sera and lung tissues. Stimulation of viral-sensing toll-like receptors in vitro and administration of synthetic viral RNA in vivo induced features of hyperinflammation, including cytokine elevation, immune cell airway infiltration, and MC-protease production—effects suppressed by an anti-Siglec-8 monoclonal antibody which selectively inhibits MCs and depletes eosinophils. Similarly, anti-Siglec-8 treatment reduced disease severity and airway inflammation in a respiratory viral infection model. These results suggest that MC and eosinophil activation are associated with COVID-19 inflammation and anti-Siglec-8 antibodies are a potential therapeutic approach for attenuating excessive inflammation during viral infections.

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