CD95L concatemers highlight different stoichiometries of CD95-mediated apoptotic and nonapoptotic pathways

To better understand the stoichiometry of CD95L required to trigger apoptotic and nonapoptotic signals, we generated several CD95L concatemers from dimer to hexamer conjugated via a flexible link (GGGGS)2 . These ligands reveal that although the hexameric structure is the best stoichiometry to trigger cell death, a dimer is sufficient to induce the apoptotic response in CD95-sensitive Jurkat cells. Interestingly, only trimeric and hexameric forms can implement a potent Ca2+ response, suggesting that while CD95 aggregation controls the implementation of the apoptotic signal, both aggregation and conformation are required to implement the Ca2+ pathway.

CD95 (Fas) and CD95L (FasL)-mediated non-canonical signaling pathways

Although the interaction of CD95L (also known as FasL) with its so-called death receptor CD95 (Fas) induces an apoptotic signal responsible for the elimination of infected and cancer cells and maintenance of tissue homeostasis, this receptor can also implement non apoptotic signaling pathways. This latter signaling is involved in metastatic dissemination in certain cancers and the severity of auto-immune disorders. The signaling complexity of this pair is increased by the fact that CD95 expression itself seems to contribute to oncogenesis via a CD95L-independent manner and, that both ligand and receptor might interact with other partners modulating their pathophysiological functions. Finally, CD95L itself can trigger cell signaling in immune cells rendering complex the interpretation of mouse models in which CD95 or CD95L are knocked out. Herein, we discuss these non-canonical responses and their biological functions.

Role of metalloproteases in the CD95 signaling pathways

CD95L (also known as FasL or CD178) is a member of the tumor necrosis family (TNF) superfamily. Although this transmembrane ligand has been mainly considered as a potent apoptotic inducer in CD95 (Fas)-expressing cells, more recent studies pointed out its role in the implementation of non-apoptotic signals. Accordingly, this ligand has been associated with the aggravation of inflammation in different auto-immune disorders and in the metastatic occurrence in different cancers. Although it remains to decipher all key factors involved in the ambivalent role of this ligand, accumulating clues suggest that while the membrane bound CD95L triggers apoptosis, its soluble counterpart generated by metalloprotease-driven cleavage is responsible for its non-apoptotic functions. Nonetheless, the metalloproteases (MMPs and ADAMs) involved in the CD95L shedding, the cleavage sites and the different stoichiometries and functions of the soluble CD95L remain to be elucidated. To better understand how soluble CD95L triggers signaling pathways from apoptosis to inflammation or cell migration, we propose herein to summarize the different metalloproteases that have been described to be able to shed CD95L, their cleavage sites and the biological functions associated with the released ligands. Based on these new findings, the development of CD95/CD95L-targeting therapeutics is also discussed.

Ex vivo potential of a quinoline-derivative nail lacquer as a new alternative for dermatophytic onychomycosis treatment

Introduction. Onychomycosis infections currently show a significant increase, affecting about 10 % of the world population. Trichophyton rubrum is the main agent responsible for about 80 % of the reported infections. The clinical cure for onychomycosis is extremely difficult and effective new antifungal therapy is needed.Hypothesis/Gap Statement. Ex vivo onychomycosis models using porcine hooves can be an excellent alternative for evaluating the efficacy of new anti-dermatophytic agents in a nail lacquer.Aim. Evaluation of the effectiveness of a nail lacquer containing a quinoline derivative on an ex vivo onychomycosis model using porcine hooves, as well as the proposal of a plausible antifungal mechanism of this derivative against dermatophytic strains.Methodology. The action mechanism of a quinoline derivative was evaluated through the sorbitol protection assay, exogenous ergosterol binding, and the determination of the dose-response curves by time-kill assay. Scanning electron microscopy evaluated the effect of the derivative in the fungal cells. The efficacy of a quinoline-derivative nail lacquer on an ex vivo onychomycosis model using porcine hooves was evaluated as well.Results. The quinoline derivative showed a time-dependent fungicidal effect, demonstrating reduction and damage in the morphology of dermatophytic hyphae. In addition, the ex vivo onychomycosis model was effective in the establishment of infection by T. rubrum.Conclusion. Treatment with the quinoline-derivative lacquer showed a significant inhibitory effect on T. rubrum strain in this infection model. Finally, the compound presents high potential for application in a formulation such as nail lacquer as a possible treatment for dermatophytic onychomycosis.

Restoration of normal sinus rhythm in atrial fibrillation: impact of reverse remodelling of right chambers on tricuspid regurgitation severity

Background

The severity of tricuspid regurgitation (TR) in patients with restored normal sinus rhythm (SR) after atrial fibrillation (AF) has been poorly assessed.

Purpose

Our study aimed to assess (1) right chamber remodelling and (2) TR severity in patients with AF who have had their rhythms restored to normal sinus.

Methods

We prospectively evaluated 94 consecutive patients hospitalized for AF who received either ablation, direct current cardioversion, or pharmacological therapy. Patients were divided into two groups according to their cardiac rhythm at 6 months follow up (6M): restoration to SR (SR group, n=54), persistence of AF (AF group, n=40). TR vena contracta (VC), TR grade severity was divided into 4 grades using an integrated approach (0: none or trace; 1: mild; 2: moderate; 3: severe TR). Two dimensional (2D) end diastolic (ED) tricuspid annulus (TA) diameter in the apical 4 chambers view, three-dimensional (3D) indexed volumes (3D Vi) of the right atrium (RA) and right ventricle (RV) in end systole (ES) and ED were acquired using transthoracic echocardiography at admission and at 6M.

Results

At 6M, in the SR group a significant improvement in TR VC (Figure A) and TR grade (Figure B) were noted, whereas there was no differences in the AF group (0.41 vs. 0.42cm, p=0.24 for TR VC; 1.70 vs. 1.76, p=0.16 for mean TR grade). In the SR group a significant reduction in 3D ES RV Vi, 2D ED TA diameter, 3D ES and ED Vi of the RA (Table) were observed. Regression of TR VC was correlated with regression of right cavities parameters (ρ=0.47, p<0.001 for 2D ED TA diameter; ρ=0.34, p<0.005 for 3D ES RA Vi; ρ=0.33, p<0.005 for 3D ED RV Vi; ρ=0.29, p<0.005 for 3D ES RV Vi).

Conclusion

Restoration of normal SR in patients with AF results in beneficial remodelling of right cavities at 6M of follow-up which were associated with a significant decrease in TR severity. Strategies for normal SR restoration in patients with AF and TR should be vigorously attempted.

TR Evolution

Funding Acknowledgement

Type of funding source: None

Impact of rhythm in non-valvular atrial fibrillation on four cardiac chamber deformation imaging

Background

Few studies have assessed the evolution of cardiac chambers deformation imaging in patients with atrial fibrillation (AF) according to cardiac rhythm outcome.

Purpose

To evaluate cardiac chamber deformation imaging in patients admitted for AF and the evolution at 6-month follow-up (M6).

Methods

In forty-one consecutive patients hospitalised for AF two-dimensional transthoracic echocardiography was performed at admission (M0) and after six months (M6) of follow up. In addition to the usual parameters of chamber size and function, chamber deformation imaging was obtained including global left atrium (LA) and right atrium (RA) reservoir strain, global left ventricular (LV) and right ventricular (RV) free wall longitudinal strain. Patients were divided into three groups according to their cardiac rhythm at M0 and M6: AF at M0 and sinus rhythm (SR) at M6 (AF-SR) (n=23), AF at M0 and AF at M6 (AF-AF) (n=11), SR at M0 (spontaneous conversion before the first echocardiography exam) and SR in M6 (SR-SR) (n=7)

Results

In comparison with SR patients (n=7), at M0, AF patients (n=34)) had lower global LA reservoir strain (+5.2 (+0.4 to 12.8) versus +33.2 (+27.0 to +51.5)%; p<0.001), lower global RA reservoir strain (+8.6 (−5.4 to 11.6) versus +24.3 (+12.3 to +44.9)%; p<0.001), lower global LV longitudinal strain (respectively −12.8 (−15.2 to −10.4) versus −19.1 (−21.8 to −18.3)%; p<0.001) and lower global RV longitudinal strain (respectively −14.2 (−17.3 to −10.7) versus −23.8 (−31.1 to −16.2)%; p=0.001). When compared with the AF-SR group at M0 the AF-AF group had no significant differences with regard to global LA and RA reservoir strain, global LV and RV longitudinal strain (Table). Between M0 and M6 there was a significant improvement in global longitudinal strain of the four chambers in the AF-SR group whereas no improvements were noted in the AF-AF and SR-SR group (Figure).

Conclusion

Initial atrial and ventricular deformations were not associated with rhythm outcome at six-month follow up in AF. The improvement in strain in all four chambers strain suggests global reverse remodelling all cardiac cavities with the restoration of sinus rhythm.

Evolution of strain between M0 and M6

Funding Acknowledgement

Type of funding source: None

Quinolines derivatives as promising new antifungal candidates for the treatment of candidiasis and dermatophytosis

Fungal infections have emerged as a current serious global public health problem. The main problem involving these infections is the expansion of multidrug resistance. Therefore, the prospection of new compounds with efficacy antifungal becomes necessary. Thus, this study evaluated the antifungal profile and toxicological parameters of quinolines derivatives against Candida spp. and dermatophyte strains. As a result, a selective anti-dermatophytic action was demonstrated by compound 5 (geometric means (GM = 19.14 μg ml⁻¹)). However, compounds 2 (GM = 50 μg ml⁻¹) and 3 (GM = 47.19 μg ml⁻¹) have presented only anti-Candida action. Compounds 3 and 5 did not present cytotoxic action. Compound 5 did not produce dermal and mucosal toxicity. In addition, this compound showed the absence of genotoxic potential, suggesting safety for topical and systemic use. Quinolines demonstrated a potent anti-dermatophytic and anti-yeast action. Moreover, compound 5 presented an excellent toxicological profile, acting as a strong candidate for the development of a new effective and safe compound against dermatophytosis of difficult treatment.

CD95 Structure, Aggregation and Cell Signaling

CD95 is a pre-ligand-associated transmembrane (TM) receptor. The interaction with its ligand CD95L brings to a next level its aggregation and triggers different signaling pathways, leading to cell motility, differentiation or cell death. This diversity of biological responses associated with a unique receptor devoid of enzymatic property raises the question of whether different ligands exist, or whether the fine-tuned control of CD95 aggregation and conformation, its distribution within certain plasma membrane sub-domains or the pattern of post-translational modifications account for this such broad-range of cell signaling. Herein, we review how the different domains of CD95 and their post-translational modifications or the different forms of CD95L can participate in the receptor aggregation and induction of cell signaling. Understanding how CD95 response goes from cell death to cell proliferation, differentiation and motility is a prerequisite to reveal novel therapeutic options to treat chronic inflammatory disorders and cancers.

Probing the side chain tolerance for inhibitors of the CD95/PLCγ1 interaction

Proceeding our effort to study protein-protein interaction between the death receptor CD95 and phospholipase PLCγ1, we present in the current work chameleon-like traits of peptidomimetic inhibitors. Minute analysis of the interaction suggests that most of the binding energy relies on van der Waals contacts rather than more specific features, such as hydrogen bonds or salt bridges. The two most important positions of the peptoid for its interaction with PLCγ1 (Arg184 and Arg187) were modified to test this hypothesis. While Arg184 proves to be exchangeable for Trp, with no alteration in affinity, the nature of the amino acid replacing Arg187 is more dependent on its positive charge. However, affinity can be partially recovered by increasing van der Waals interactions. Overall, this study shows that for both positions, a subtle balance exists between hydrophobicity, surface contacts and affinity for CD95/PLCγ1, and provides information for the generation of new therapeutic compounds toward this druggable target.

Synthesis of peptidomimetics and chemo-biological tools for CD95/PLCγ1 interaction analysis

The death receptor CD95 (also known as Fas) induces apoptosis through protein/protein association and the formation of the death-inducing signaling complex. On the other hand, in certain biological conditions, this receptor recruits different proteins and triggers the formation of another complex designated motility-inducing signaling complex, which promotes cell migration and inflammation. This pathway relies on a short sequence of CD95, called calcium-inducing domain (CID), which interacts with the phospholipase PLCγ1. To better understand how CID/PLCγ1 interaction occurs, we synthesized different α-AA peptides mimicking CID. Some of these peptidomimetics are as potent as the natural peptide to disrupt the CID/PLCγ1 interaction and cell migration, and showed improved pharmacokinetic properties. We also generated biotinyl- and palmitoyl-labelled peptidomimetics, useful chemico-biological tools to further explore the pro-inflammatory signal of CD95, which plays an important role in the pathogenesis of lupus and other autoimmune diseases.

Temporal (1970-2016) changes in human pressures and wetland response in the St. Lawrence River (Québec, Canada)

Temporal changes (1970-2016) in St. Lawrence River wetlands were assessed between Cornwall and Québec (≈400 km) to assess wetland response to cumulative anthropogenic pressures in the watershed. Emergent wetlands area and biomass of submerged aquatic vegetation (SAV) were contrasted among five regions subjected to sharply different water level/discharge regime (stabilized, semi-natural, tidal), nutrient concentrations and shoreline use (rural to urbanized). Between 1970 and 2016, over the growing season (April-Sept.), St. Lawrence River mean water level at Sorel dropped by ≈1 m and mean water temperature increased by ≈3 °C. Reductions in phosphorus concentrations (by ≈2-fold) were observed over time both in water and in SAV tissues, in phase with improvements of urban wastewater treatment and P-reduction in upstream Lake Ontario. Nitrate concentrations in water increased and SAV biomass decreased between the 1970s and 2008 in the downstream regions of Lake Saint-Pierre and fluvial corridor subjected to the cumulative impacts from urban centers and intensively farmed watersheds. Over the 1970-2010 period, dropping water levels yielded slightly increasing wetland areas, owing to the downslope colonization of emergent and submerged plants. In urbanized regions, emergent wetlands shifted towards drier assemblages dominated by invasive reed species. Encroachment of wetlands by agriculture accounted for most wetland losses in rural Lake Saint-Pierre, which holds the single largest area (197 km²) of continuous wetland habitat of the entire watershed. Our results highlight the strong response of riverine wetlands to a wide range of human pressures, including dropping water levels, changing nutrient concentrations, rising population and intensifying agriculture.

Diagnostic delay of pyogenic vertebral osteomyelitis and its associated factors

OBJECTIVES

Pyogenic vertebral osteomyelitis (PVO) is a rare disease with possible severe complications (e.g. sepsis and spinal cord injury). In the 1990s, diagnostic delay (DD) was often extensive as PVO has a non-specific clinical spectrum, mostly afebrile with back pain, and access to magnetic resonance imaging (MRI) was not straightforward. Our aim was to perform a new study focusing on the clinical spectrum and DD of PVO and its associated factors.

METHOD

This study examined a prospective cohort of 88 patients having PVO with microbiological identification between 15 November 2006 and 15 November 2010.

RESULTS

The 88 patients included in the study (female:male ratio 1:8) had a mean age of 64.1 years. The mean (sd) DD was 45.5 (50.4) days (range 2-280), and 46 patients (52.2%) were febrile at diagnosis. The main microorganism involved was Staphylococcus (n = 45; 51.1%). In univariate and multivariate analyses, age > 75 years, antecedent back pain, involvement of bacteria, topography of PVO, and anti-inflammatory drug intake did not affect the DD, unlike a C-reactive protein (CRP) value > 63 mg/L or a positive blood culture (DD lowered from 73 to 17 days and from 90 to 30 days, respectively). Conversely, X-ray investigation was associated with a longer DD (from 14 to 34.7 days). Severity at diagnosis was not significantly different depending on the intake of anti-inflammatory drugs.

CONCLUSIONS

Despite easier access to MRI, the DD for PVO remains long. One shortening factor is a high CRP value, which could be a useful diagnostic tool in case of back pain. Anti-inflammatory drugs seem to have no impact on DD and severity at diagnosis.

A Novel Covalent mTOR Inhibitor, DHM25, Shows in Vivo Antitumor Activity against Triple-Negative Breast Cancer Cells

Constitutive activation of the PI3K/mTOR signaling pathway contributes to carcinogenesis and metastasis in most, if not all, breast cancers. From a chromene backbone reported to inhibit class I PI3K catalytic subunits, several rounds of chemical syntheses led to the generation of a new collection of chromologues that showed enhanced ability to kill PI3K-addicted cancer cells and to inhibit Akt phosphorylation at serine 473, a hallmark of PI3K/mTOR activation. This initial screen uncovered a chromene designated DHM25 that exerted potent antitumor activity against breast tumor cell lines. Strikingly, DHM25 was shown to be a selective and covalent inhibitor of mTOR using biochemical and cellular analyses, modeling, and a large panel of kinase activity assays spanning the human kinome (243 kinases). Finally, in vivo, this novel drug was an efficient inhibitor of growth and metastasis of triple-negative breast cancer cells, paving the way for its clinical application in oncology.

Strategy of total synthesis based on the use of Rh-catalyzed stereoselective 1,4-addition

In 1998, Hayashi and Miyaura reported the first asymmetric conjugate addition of aryl- and alkenyl-boronic acids to α,β-unsaturated ketones using chiral rhodium complexes as catalysts.

Synthesis of new bioisosteric hemiasterlin analogues with extremely high cytotoxicity

In this Letter, the synthesis and the evaluation of the cytotoxicity of new hemiasterlin analogues were reported. The indole moiety was replaced respectively by benzofurane, naphthalene and 4-bromobenzene groups. Most of these derivatives possess strong cytotoxic activity on two human tumour cell lines (KB and Hep-G2), and some analogues showed comparable cytotoxic activity to that observed for paclitaxel and ellipticine, against KB and Hep-G2 cancer cell lines.

Synthesis of new simplified hemiasterlin derivatives with α,β-unsaturated carbonyl moiety

In this Letter, we report a convenient and efficient method for the synthesis of new simplified derivatives of hemiasterlin in which the α,α-dimethylbenzylic moiety A is replaced by α,β-unsaturated aryl groups as Michael acceptor. Most of these derivatives have a strong cytotoxic activity on three human tumor cell lines (KB, Hep-G2 and MCF7). Analogs 17b and 17f showed a high cytotoxicity against KB and Hep-G2 cancer cell lines comparable to paclitaxel and ellipticine.

Synthesis of stachybotrin C and all of its stereoisomers: structure revision

We disclose the first total synthesis of stachybotrin C, a potent neuroprotective natural compound. All of the four stereoisomers have been prepared and fully characterized with the aim to attribute the absolute configuration of the two adjacent stereocenters of the stachybotrin C.

Measurement and modelling of radioxenon plumes in the Ottawa Valley

Since 2001 a real-time radiation monitoring network of Canadian nuclear facilities and major population centres has been implemented for response to nuclear incidents including a possible terrorist attack. Unshielded NaI(Tl) spectroscopic detectors are employed to measure gamma radiation from airborne radioactivity and radioactivity deposited on the ground. These detectors are composed of a standard 3''x3'' cylindrical NaI(Tl) spectrometers with data storage and integrated telemetry. Some of the detectors have been deployed in the Ottawa Valley near Chalk River Laboratories and Ottawa, which has a complex radioxenon environment due to the proximity of nuclear power reactors, and medical isotope facilities. Although not a health threat, these releases have provided an opportunity for the Canadian Meteorological Centre and the Commissariat à l'Energie Atomique to validate their meteorological models. The meteorological models of the two organizations are in good agreement on the origin and the source terms of these releases.

Biofilms of As(III)-oxidising bacteria: formation and activity studies for bioremediation process development

The formation and activity of an As(III)-oxidising biofilm in a bioreactor, using pozzolana as bacterial growth support, was studied for the purpose of optimising fixed-bed bioreactors for bioremediation. After 60 days of continuous functioning with an As(III)-contaminated effluent, the active biofilm was found to be located mainly near the inflow rather than homogeneously distributed. Biofilm development by the CAsO1 bacterial consortium and by Thiomonas arsenivorans was then studied both on polystyrene microplates and on pozzolana. Extra-cellular polymeric substances (EPS) and yeast extract were found to enhance bacteria attachment, and yeast extract also appears to increase the kinetics of biofilm formation. Analysis of proteins, sugars, lipids and uronic acids indicate that sugars were the main EPS components. The specific As(III)-oxidase activity of T. arsenivorans was higher (by ninefold) for planktonic cells than for sessile ones and was induced by As(III). All the results suggest that the biofilm structure is a physical barrier decreasing As(III) access to sessile cells and thus to As(III)-oxidase activity induction. The efficiency of fixed-bed reactors for the bioremediation of arsenic-contaminated waters can be thus optimised by controlling different factors such as temperature and EPS addition and/or synthesis to increase biofilm density and activity.