Candida albicans and Pseudomonas aeruginosa Interact To Enhance Virulence of Mucosal Infection in Transparent Zebrafish

Abstract

Polymicrobial infections often include both fungi and bacteria and can complicate patient treatment and resolution of infection. Cross-kingdom interactions among bacteria, fungi, and/or the immune system during infection can enhance or block virulence mechanisms and influence disease progression. The fungus Candida albicans and the bacterium Pseudomonas aeruginosa are coisolated in the context of polymicrobial infection at a variety of sites throughout the body, including mucosal tissues such as the lung. In vitro, C. albicans and P. aeruginosa have a bidirectional and largely antagonistic relationship. Their interactions in vivo remain poorly understood, specifically regarding host responses in mediating infection. In this study, we examine trikingdom interactions using a transparent juvenile zebrafish to model mucosal lung infection and show that C. albicans and P. aeruginosa are synergistically virulent. We find that high C. albicans burden, fungal epithelial invasion, swimbladder edema, and epithelial extrusion events serve as predictive factors for mortality in our infection model. Longitudinal analyses of fungal, bacterial, and immune dynamics during coinfection suggest that enhanced morbidity is associated with exacerbated C. albicans pathogenesis and elevated inflammation. The P. aeruginosa quorum-sensingdeficient ΔlasR mutant also enhances C. albicans pathogenicity in coinfection and induces extrusion of the swimbladder. Together, these observations suggest that C. albicans-P. aeruginosa cross talk in vivo can benefit both organisms to the detriment of the host.

Tornadic shear stress induces a transient, calcineurin-dependent hyper-virulent phenotype in Mucorales molds

“…Furthermore, our study in a fungal mono-infection model cannot recapitulate the complexity of trauma-related soft tissue infections that are often polymicrobial in nature (1, 9–15). Cross-kingdom interactions of pathogens have been increasingly recognized as key virulence determinants shaping the outcomes of life-threatening infectious diseases (54–55). Direct physical interaction, inter-kingdom signaling, altered immunopathology, and competition for nutrients or trace elements are considered to play a driving role in the mutual modulation of bacterial and fungal virulence (54, 56).…”

Redundant Trojan horse and endothelial-circulatory mechanisms for host-mediated spread of Candida albicans yeast

“…Overnight cultures were washed twice and resuspended in PBS at 2.5×10 7 cells/ml, then boiled for 10 minutes or placed in an uncovered polystyrene petri dish (60 mm x 15 mm, VWR, Radnor, PA) for exposure. A CL-1000 UV cross-linker was used for UV inactivation of C. albicans [83] (UVP, Vernon Hills, IL) and yeast were exposed four times to 100,000 μJ/cm 2 with swirling between each exposure. Following boiling or UV-inactivation, cells were stained with AlexaFluor 555 by coincubation of cells in PBS with sodium bicarbonate (0.037 M final concentration, pH 8.2) in the dark for 40 minutes with periodic vortexing.…”

“…Using the iScript reverse transcriptase supermix (Bio-Rad, Hercules, CA), cDNA was synthesized from 500 ng RNA per sample. RT-qPCR was done on a CFX96 thermocycler (Bio-Rad, Hercules, CA) using the cycles: 95°C for 30 s, 95°C for 5 s followed by 60°C for 20 s for 39 cycles, then 95°C for 10 s followed by 65°C for 5 s [83]. The Bio-Rad CFX Manager software was used to analyze threshold cycles and dissociation curves.…”

“…The Bio-Rad CFX Manager software was used to analyze threshold cycles and dissociation curves. Larval gene expression was normalized to the gapdh control gene (ΔCT), as done previously [83, 84], and compared to the mock infected PBS controls (ΔΔCT).…”

Conditional antagonism in co-cultures ofPseudomonas aeruginosaandCandida albicans: an intersection of ethanol and phosphate signaling distilled from dual-seq transcriptomics

“…Pseudomonas aeruginosa and Candida albicans are opportunistic pathogens that are frequently isolated from co-infections [1–11]. These pathogens affect each other’s behaviors through competition for nutrients [12–17], physical contact [3, 4, 7, 13, 14], diffusible signaling molecules [18–23] and antimicrobials [18, 21, 24–30]. Studies highlighting the dynamic interactions between P. aeruginosa and C. albicans have contributed to the growing understanding of how microbial interactions influence microbial physiology and behavior as well as microbiological and pathological outcomes.…”