The bacterium Staphylococcus (St.) aureus and the opportunistic fungus Candida albicans are currently among the leading nosocomial pathogens, often co-infecting critically ill patients, with high ...morbidity and mortality. Previous investigations have demonstrated preferential adherence of St. aureus to C. albicans hyphae during mixed biofilm growth. In this study, we aimed to characterize the mechanism behind this observed interaction. C. albicans adhesin-deficient mutant strains were screened by microscopy to identify the specific receptor on C. albicans hyphae recognized by St. aureus. Furthermore, an immunoassay was developed to validate and quantify staphylococcal binding to fungal biofilms. The findings from these experiments implicated the C. albicans adhesin agglutinin-like sequence 3 (Als3p) in playing a major role in the adherence process. This association was quantitatively established using atomic force microscopy, in which the adhesion force between single cells of the two species was significantly reduced for a C. albicans mutant strain lacking als3. Confocal microscopy further confirmed these observations, as St. aureus overlaid with a purified recombinant Als3 N-terminal domain fragment (rAls3p) exhibited robust binding. Importantly, a strain of Saccharomyces cerevisiae heterologously expressing Als3p was utilized to further confirm this adhesin as a receptor for St. aureus. Although the parental strain does not bind bacteria, expression of Als3p on the cell surface conferred upon the yeast the ability to strongly bind St. aureus. To elucidate the implications of these in vitro findings in a clinically relevant setting, an ex vivo murine model of co-infection was designed using murine tongue explants. Fluorescent microscopic images revealed extensive hyphal penetration of the epithelium typical of C. albicans mucosal infection. Interestingly, St. aureus bacterial cells were only seen within the epithelial tissue when associated with the invasive hyphae. This differed from tongues infected with St. aureus alone or in conjunction with the als3 mutant strain of C. albicans, where bacterial presence was limited to the outer layers of the oral tissue. Collectively, the findings generated from this study identified a key role for C. albicans Als3p in mediating this clinically relevant fungal-bacterial interaction.
The widespread resistance to antibiotics in pathogenic bacteria makes the development of a new generation of antimicrobials an urgent task. The development of new antibiotics must be accompanied by a ...comprehensive study of all of their biological activities in order to avoid adverse side-effects from their application. Some promising antibiotic prototypes derived from the structures of arenicins, antimicrobial peptides from the lugworm Arenicola marina, have been developed. Previously, we described the ability of natural arenicins -1 and -2 to modulate the human complement system activation in vitro. In this regard, it seems important to evaluate the effect of therapeutically promising arenicin analogues on complement activation. Here, we describe the complement-modulating activity of three such analogues, Ar-1V8R, ALP1, and AA139. We found that the mode of action of Ar-1V8R and ALP1 on the complement was similar to that of natural arenicins, which can both activate and inhibit the complement, depending on the concentration. However, Ar-1V8R behaved predominantly as an inhibitor, showing only a moderate increase in C3a production in the alternative pathway model and no enhancement at all of the classical pathway of complement activation. In contrast, the action of ALP1 was characterized by a marked increase in the complement activation through the classical pathway in the concentration range of 2.5–20 μg/mL. At the same time, at higher concentrations (80–160 μg/mL), this peptide exhibited a complement inhibitory effect characteristic of the other arenicins. Peptide AA139, like other arenicins, exhibited an inhibitory effect on complement at a concentration of 160 μg/mL, but was much less pronounced. Overall, our results suggest that the effect on the complement system should be taken into account in the development of antibiotics based on arenicins.
We recently identified a set of plasma microRNAs (miRNAs) that are downregulated in patients with heart failure in comparison with control subjects. To better understand their meaning and function, ...we sought to validate these circulating miRNAs in 3 different well-established rat and mouse heart failure models, and correlated the miRNAs to parameters of cardiac function.
The previously identified let-7i-5p, miR-16-5p, miR-18a-5p, miR-26b-5p, miR-27a-3p, miR-30e-5p, miR-199a-3p, miR-223-3p, miR-423-3p, miR-423-5p and miR-652-3p were measured by means of quantitative real time polymerase chain reaction (qRT-PCR) in plasma samples of 8 homozygous TGR(mREN2)27 (Ren2) transgenic rats and 8 (control) Sprague-Dawley rats, 6 mice with angiotensin II-induced heart failure (AngII) and 6 control mice, and 8 mice with ischemic heart failure and 6 controls. Circulating miRNA levels were compared between the heart failure animals and healthy controls.
Ren2 rats, AngII mice and mice with ischemic heart failure showed clear signs of heart failure, exemplified by increased left ventricular and lung weights, elevated end-diastolic left ventricular pressures, increased expression of cardiac stress markers and reduced left ventricular ejection fraction. All miRNAs were detectable in plasma from rats and mice. No significant differences were observed between the circulating miRNAs in heart failure animals when compared to the healthy controls (all P>0.05) and no robust associations with cardiac function could be found.
The previous observation that miRNAs circulate in lower levels in human patients with heart failure could not be validated in well-established rat and mouse heart failure models. These results question the translation of data on human circulating miRNA levels to experimental models, and vice versa the validity of experimental miRNA data for human heart failure.
Antimicrobial peptides (AMPs) are not only cytotoxic towards host pathogens or cancer cells but also are able to act as immunomodulators. It was shown that some human and non-human AMPs can interact ...with complement proteins and thereby modulate complement activity. Thus, AMPs could be considered as the base for complement-targeted therapeutics development. Arenicins from the sea polychaete
, the classical example of peptides with a β-hairpin structure stabilized by a disulfide bond, were shown earlier to be among the most prospective regulators. Here, we investigate the link between arenicins' structure and their antimicrobial, hemolytic and complement-modulating activities using the derivative Ar-1-(C/A) without a disulfide bond. Despite the absence of this bond, the peptide retains all important functional activities and also appears less hemolytic in comparison with the natural forms. These findings could help to investigate new complement drugs for regulation using arenicin derivatives.
Objective
Circulating microRNAs (miRNAs) have been implicated in both heart failure and atherosclerotic disease. The aim of this study was to examine associations between heart failure specific ...circulating miRNAs, atherosclerotic disease and cardiovascular-related outcome in patients with heart failure.
Methods
The levels of 11 heart failure-specific circulating miRNAs were compared in plasma of 114 heart failure patients with and without different manifestations of atherosclerotic disease. We then studied these miRNAs in relation to biomarkers associated to atherosclerosis and to cardiovascular-related rehospitalizations during 18 months of follow-up.
Results
At least one manifestation of atherosclerotic disease was found in 70 (61%) of the heart failure patients. A consistent trend was found between an increasing number of manifestations of atherosclerosis (peripheral arterial disease in specific), and lower levels of miR-18a-5p, miR-27a-3p, miR-199a-3p, miR-223-3p and miR-652-3p (all
P
< 0.05). Target prediction and network analyses identified several interactions between miRNA targets and biomarkers related to inflammation, angiogenesis and endothelial dysfunction. Lower miRNA levels were associated with higher levels of these atherosclerosis-related biomarkers. In addition, lower miRNA levels were significantly associated with rehospitalizations due to cardiovascular causes within 18 months, with let-7i-5p as strongest predictor HR 2.06 (95% CI 1.29–3.28), C-index 0.70,
P
= 0.002.
Conclusions
A consistent pattern of lower levels of circulating miRNAs was found in heart failure patients with atherosclerotic disease, in particular peripheral arterial disease. In addition, lower levels of miRNAs were associated with higher levels of biomarkers involved in atherosclerosis and an increased risk of a cardiovascular-related rehospitalization.
Aims
Our aim was to identify circulating microRNAs (miRNAs) associated with acute heart failure (AHF).
Methods and results
Plasma miRNA profiling included 137 patients with AHF from 3 different ...cohorts, 20 with chronic heart failure (CHF), 8 with acute exacerbation of COPD, and 41 healthy controls. Levels of circulating miRNAs were measured using quantitative reverse transcription–polymerase chain reaction (qRT–PCR). Plasma levels of miRNAs in patients with AHF were decreased compared with CHF patients or healthy subjects, whereas no significant changes were observed between acute COPD patients and controls. Fifteen miRNAs found in the discovery phase to differ most significantly between healthy controls and patients with AHF were further investigated in an extended cohort of 100 AHF patients at admission and a separate cohort of 18 AHF patients at different time points. Out of these 15 miRNAs, 12 could be confirmed in an additional AHF validation cohort and 7 passed the Bonferroni correction threshold (miR‐18a‐5p, miR‐26b‐5p, miR‐27a‐3p, miR‐30e‐5p, miR‐106a‐5p, miR‐199a‐3p, and miR‐652‐3p, all P < 0.00005). A further drop in miRNA levels within 48 h after AHF admission was associated with an increased risk of 180‐day mortality in a subset of the identified miRNAs.
Conclusions
Declining levels of circulating miRNAs were associated with increasing acuity of heart failure. Early in‐hospital decreasing miRNA levels were predictive for mortality in a subset of miRNAs in patients with AHF. The discovered miRNA panel may serve as a launch‐pad for molecular pathway studies to identify new pharmacological targets and miRNA‐based therapies.
In response to heart failure (HF), the heart reacts by repressing adult genes and expressing fetal genes, thereby returning to a more fetal-like gene profile. To identify genes involved in this ...process, we carried out transcriptional analysis on murine hearts at different stages of development and on hearts from adult mice with HF. Our screen identified
, encoding for 5-oxoprolinase, a member of the γ-glutamyl cycle that functions by scavenging 5-oxoproline. OPLAH depletion occurred as a result of cardiac injury, leading to elevated 5-oxoproline and oxidative stress, whereas OPLAH overexpression improved cardiac function after ischemic injury. In HF patients, we observed elevated plasma 5-oxoproline, which was associated with a worse clinical outcome. Understanding and modulating fetal-like genes in the failing heart may lead to potential diagnostic, prognostic, and therapeutic options in HF.
Antimicrobial peptides from marine invertebrates are known not only to act like cytotoxic agents, but they also can display some additional activities in mammalian organisms. In particular, these ...peptides can modulate the complement system as was described for tachyplesin, a peptide from the horseshoe crab. In this work, we investigated the influence on complement activation of the antimicrobial peptide arenicin-1 from the marine polychaete
. To study effects of arenicin on complement activation in human blood serum, we used hemolytic assays of two types, with antibody sensitized sheep erythrocytes and rabbit erythrocytes. Complement activation was also assessed, by the level of C3a production that was measured by ELISA. We found that the effect of arenicin depends on its concentration. At relatively low concentrations the peptide stimulates complement activation and lysis of target erythrocytes, whereas at higher concentrations arenicin acts as a complement inhibitor. A hypothetical mechanism of peptide action is proposed, suggesting its interaction with two complement proteins, C1q and C3. The results lead to the possibility of the development of new approaches for therapy of diseases connected with complement dysregulation, using peptide regulators derived from natural antimicrobial peptides of invertebrates.
Abstract 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 < 0.001), miR-199a-3p to procalcitonin (R =-0.72, p-value < 0.001) and galectin-3 (R =-0.73, p-value < 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.
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.
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.
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.
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