Evaluation of adhesion forces of Staphylococcus aureus along the length of Candida albicans hyphae

BACKGROUND: Candida albicans is a human fungal pathogen, able to cause both superficial and serious, systemic diseases and is able to switch from yeast cells to long, tube-like hyphae, depending on the prevailing environmental conditions. Both morphological forms of C. albicans are found in infected tissue, often in combination with Staphylococcus aureus. Although bacterial adhesion to the different morphologies of C. albicans has been amply studied, possible differences in staphylococcal adhesion forces along the length of C. albicans hyphae have never been determined. In this study, we aim to verify the hypothesis that the forces mediating S. aureus NCTC8325-4(GFP) adhesion to hyphae vary along the length of C. albicans SC5314 and MB1 hyphae, as compared with adhesion to yeast cells. RESULTS: C. albicans hyphae were virtually divided into a “tip” (the growing and therefore youngest part of the hyphae), a “middle” and a so-called “head” region (the yeast cell from which germination started). Adhesion forces between S. aureus NCTC8325-4(GFP) and the different regions of C. albicans SC5314 hyphae were measured using atomic force microscopy. Strong adhesion forces were found at the tip and middle regions of C. albicans hyphae (−4.1 nN and −4.0 nN, respectively), while much smaller adhesion forces were measured at the head region (−0.3 nN). Adhesion forces exerted by the head region were comparable with the forces arising from budding yeast cells (−0.5 nN). A similar regional dependence of the staphylococcal adhesion forces was found for the clinical isolate involved in this study, C. albicans MB1. CONCLUSIONS: This is the first time that differences in adhesion forces between S. aureus and different regions of C. albicans hyphae have been demonstrated on a quantitative basis, supporting the view that the head region is different from the remainder of the hyphae. Notably it can be concluded that the properties of the hyphal head region are similar to those of budding yeast cells. These novel findings provide new insights in the intricate interkingdom interaction between C. albicans and S. aureus

Integrated proteogenomic approach identifying a protein signature of COPD and a new splice variant of SORBS1

Translation of genomic alterations to protein changes in chronic obstructive pulmonary disease (COPD) is largely unexplored. Using integrated proteomic and RNA sequencing analysis of COPD and control lung tissues, we identified a protein signature in COPD characterised by extracellular matrix changes and a potential regulatory role for SUMO2. Furthermore, we identified 61 differentially expressed novel, non-reference, peptides in COPD compared with control lungs. This included two peptides encoding for a new splice variant of SORBS1, of which the transcript usage was higher in COPD compared with control lungs. These explorative findings and integrative proteogenomic approach open new avenues to further unravel the pathology of COPD

Use of biomarkers to establish potential role and function of circulating microRNAs in acute heart failure

Background: Circulating microRNAs (miRNAs) emerge as potential heart failure biomarkers. We aimed to identify associations between acute heart failure (AHF)-specific circulating miRNAs and well-known heart failure biomarkers.Methods: Associations between 16 biomarkers predictive for 180 day mortality and the levels of 12 AHF-specific miRNAs were determined in 100 hospitalized AHF patients, at baseline and 48 hours. Patients were divided in 4 pre-defined groups, based on clinical parameters during hospitalization. Correlation analyses between miRNAs and biomarkers were performed and complemented by miRNA target prediction and pathway analysis.Results: No significant correlations were found at hospital admission. However, after 48 hours, 7 miRNAs were significantly negatively correlated to biomarkers indicative for a worse clinical outcome in the patient group with the most unfavorable in-hospital course (n = 21); miR-16-5p was correlated to C-reactive protein (R = -0.66, p-value = 0.0027), miR-106a-5p to creatinine (R = -0.68, p-value = 0.002), miR-223-3p to growth differentiation factor 15 (R = -0.69, p-value = 0.0015), miR-652-3p to soluble ST-2 (R = -0.77, p-value &lt;0.001), miR-199a-3p to procalcitonin (R = -0.72, p-value &lt;0.001) and galectin-3 (R = -0.73, p-value &lt;0.001) and miR-18a-5p to procalcitonin (R = -0.68, p-value = 0.002). MiRNA target prediction and pathway analysis identified several pathways related to cardiac diseases, which could be linked to some of the miRNA-biomarker correlations.Conclusions: The majority of correlations between circulating AHF-specific miRNAs were related to biomarkers predictive for a worse clinical outcome in a subgroup of worsening heart failure patients at 48 hours of hospitalization. The selective findings suggest a time-dependent effect of circulating miRNAs and highlight the susceptibility to individual patient characteristics influencing potential relations between miRNAs and biomarkers. (C) 2016 The Authors. Published by Elsevier Ireland Ltd.</p

The Development and Subsequent Elimination of Aberrant Peripheral Axon Projections in Semaphorin3A Null Mutant Mice

AbstractSemaphorin3A (previously known as Semaphorin III, Semaphorin D, or collapsin-1) is a member of the semaphorin gene family, many of which have been shown to guide axons during nervous system development. Semaphorin3A has been demonstrated to be a diffusible chemorepulsive molecule for axons of selected neuronal populations in vitro. Analysis of embryogenesis in two independent lines of Semaphorin3A knockout mice support the hypothesis that this molecule is an important guidance signal for neurons of the peripheral nervous system (M. Taniguchi et al., 1997, Neuron 19, 519–530; E. Ulupinar et al., 1999, Mol. Cell. Neurosci. 13, 281–292). Surprisingly, newborn Semaphorin3A null mutant mice exhibit no significant abnormalities (O. Behar et al., 1996, Nature 383, 525–528). In this study we have tested the hypothesis that guidance abnormalities that occurred during early stages of Semaphorin3A null mice development are corrected later in development. We have found that the extensive abnormalities formed during early developmental stages in the peripheral nervous system are largely eliminated by embryonic day 15.5. We demonstrate further that at least in one distinct anatomical location these abnormalities are mainly the result of aberrant projections. In conclusion, these findings suggest the existence of correction mechanisms that eliminate most sensory axon pathfinding errors early in development

Evaluation of adhesion forces of <it>Staphylococcus aureus</it> along the length of <it>Candida albicans</it> hyphae

Abstract Background Candida albicans is a human fungal pathogen, able to cause both superficial and serious, systemic diseases and is able to switch from yeast cells to long, tube-like hyphae, depending on the prevailing environmental conditions. Both morphological forms of C. albicans are found in infected tissue, often in combination with Staphylococcus aureus. Although bacterial adhesion to the different morphologies of C. albicans has been amply studied, possible differences in staphylococcal adhesion forces along the length of C. albicans hyphae have never been determined. In this study, we aim to verify the hypothesis that the forces mediating S. aureus NCTC8325-4GFP adhesion to hyphae vary along the length of C. albicans SC5314 and MB1 hyphae, as compared with adhesion to yeast cells. Results C. albicans hyphae were virtually divided into a “tip” (the growing and therefore youngest part of the hyphae), a “middle” and a so-called “head” region (the yeast cell from which germination started). Adhesion forces between S. aureus NCTC8325-4GFP and the different regions of C. albicans SC5314 hyphae were measured using atomic force microscopy. Strong adhesion forces were found at the tip and middle regions of C. albicans hyphae (−4.1 nN and −4.0 nN, respectively), while much smaller adhesion forces were measured at the head region (−0.3 nN). Adhesion forces exerted by the head region were comparable with the forces arising from budding yeast cells (−0.5 nN). A similar regional dependence of the staphylococcal adhesion forces was found for the clinical isolate involved in this study, C. albicans MB1. Conclusions This is the first time that differences in adhesion forces between S. aureus and different regions of C. albicans hyphae have been demonstrated on a quantitative basis, supporting the view that the head region is different from the remainder of the hyphae. Notably it can be concluded that the properties of the hyphal head region are similar to those of budding yeast cells. These novel findings provide new insights in the intricate interkingdom interaction between C. albicans and S. aureus.</p

Exchange of adsorbed serum proteins during adhesion of Staphylococcus aureus to an abiotic surface and Candida albicans hyphae: An AFM study

Staphylococcus aureus and Candida albicans are the second and third most commonly isolated microorganisms in hospital-related-infections, that are often multi-species in nature causing high morbidity and mortality. Here, adhesion forces between a S. aureus strain and abiotic (tissue-culture-polystyrene, TCPS) or partly biotic (TCPS with adhering hyphae of C albicans) surfaces were investigated in presence of fetal-bovine-serum or individual serum proteins and related with staphylococcal adhesion. Atomic-force-microscopy was used to measure adhesion forces between S. aureus and the abiotic and biotic surfaces. Adsorption of individual serum proteins like albumin and apo-transferrin to abiotic TCPS surfaces during 60 min, impeded development of strong adhesion forces as compared to fibronectin, while 60 min adsorption of proteins from fetal-bovine-serum yielded a decrease in adhesion force from -5.7 nN in phosphate-buffered-saline to -0.6 nN. Adsorption of albumin and apo-transferrin also decreased staphylococcal adhesion forces to hyphae as compared with fibronectin. During 60 min exposure to fetal-bovine-serum however, initial (5 min protein adsorption) staphylococcal adhesion forces were low (-1.6 nN), but strong adhesion forces of around -5.5 nN were restored within 60 min. This suggests for the first time that in whole fetal-bovine-serum exchange of non-adhesive proteins by fibronectin occurs on biotic C albicans hyphal surfaces. No evidence was found for such protein exchange on abiotic TCPS surfaces. Staphylococcal adhesion of abiotic and biotic surfaces varied in line with the adhesion forces and was low on TCPS in presence of fetal-bovine-serum. On partly biotic TCPS, staphylococci aggregated in presence of fetal-bovine-serum around adhering C albicans hyphae. (c) 2013 Elsevier B.V. All rights reserved

Force microscopic and thermodynamic analysis of the adhesion between Pseudomonas aeruginosa and Candida albicans

Pseudomonas aeruginosa expresses a plethora of virulence factors and many species have developed warning systems to detect and evade P. aeruginosa. Candida albicans detects P. aeruginosa by sensing the secreted bacterial quorum sensing molecule 3OC(12)HSL and responds by reverting to the yeast morphology, resistant to killing by P. aeruginosa. The aim of this study was to investigate the nature of the adhesion forces between P. aeruginosa and different C. albicans morphologies, based on surface thermodynamics and atomic force microscopy. Adhesion of P. aeruginosa to hyphae was always accompanied by strong adhesion forces, but did not occur to yeast cells. Surface thermodynamics and Poisson analyses of adhesion forces indicated that the outermost mannoprotein-layer on hyphal surfaces created favorable acid-base conditions for adhesion, allowing close approach of P. aeruginosa. Removal of these proteins caused unfavorable acid-base conditions, preventing adhesion of P. aeruginosa. Yet, favorable acid-base conditions alone are insufficient for mediating adhesion of P. aeruginosa to hyphae. P. aeruginosa PA14 lasI, unable to produce 3OC(12)HSL, showed favorable acid-base conditions, but was considerably less adherent to hyphae. However, growth in the presence of 3OC(12)HSL restored adhesion. Concluding, the mannoprotein-layer on the hyphal surface ensures favorable interaction conditions through attractive Lifshitz-Van der Waals and acid-base forces, allowing P. aeruginosa to closely approach the hyphal surface and interact stereo-chemically with the fungal cell wall for actual adhesion forces to occur. Interestingly, whereas on the one hand 3OC(12)HSL allows the bacterium to interact with hyphae, the same molecule induces changes in acid-base properties of the fungal outermost mannoprotein-layer during transition from hyphal to yeast morphology, preventing this interaction and allowing C. albicans to co-exist with P. aeruginosa

Surface Thermodynamic and Adhesion Force Evaluation of the Role of Chitin-Binding Protein in the Physical Interaction between Pseudomonas aeruginosa and Candida albicans

<p>Candida albicans and Pseudomonas aeruginosa are able to form pathogenic polymicrobial communities. P. aeruginosa colonizes and kills hyphae but is unable to attach to yeast. It is unknown why the interaction of P. aeruginosa is different with yeast than with hyphae. Here we aim to evaluate the role of P. aeruginosa chitin-binding protein (CbpD) in its physical interaction with C. albicans hyphae or yeast, based on surface thermodynamic and atomic force microscopic analyses. A P. aeruginosa mutant lacking CbpD was unable to express strong adhesion forces with hyphae (-2.9 nN) as compared with the parent strain P. aeruginosa PAO1 (-4.8 nN) and showed less adhesion to hyphae. Also blocking of CbpD using N-acetyl-glucosamine yielded a lower adhesion force (-4.3 nN) with hyphae. Strong adhesion forces were restored after complementing the expression of CbpD in P. aeruginosa PA01 Delta cbpD yielding an adhesion force of -5.1 nN. These observations were confirmed with microscopic evaluation of adhesion tests. Regardless of the absence or presence of CbpD on the bacterial cell surfaces, or their blocking, P. aeruginosa experienced favorable thermodynamic conditions for adhesion with hyphae, which were absent with yeast. In addition, adhesion forces with yeast were less than 0.5 nN in all cases. Concluding, CbpD in P. aeruginosa is responsible for strong physical interactions with C. albicans hyphae. The development of this interaction requires time due to the fact that CbpDs have to invade the outermost mannoprotein layer on the hyphal cell surfaces. In order to do this, thermodynamic conditions at the outermost cell surfaces have to be favorable.</p>