Assessing the association between genetic and phenotypic features of dilated cardiomyopathy and outcome in patients with coronary artery disease.

AIMS: To examine the relevance of genetic and cardiovascular magnetic resonance (CMR) features of dilated cardiomyopathy (DCM) in individuals with coronary artery disease (CAD). METHODS AND RESULTS: This study includes two cohorts. First, individuals with CAD recruited into the UK Biobank (UKB) were evaluated. Second, patients with CAD referred to a tertiary centre for evaluation with late gadolinium enhancement (LGE)-CMR were recruited (London cohort); patients underwent genetic sequencing as part of the research protocol and long-term follow-up. From 31 154 individuals with CAD recruited to UKB, rare pathogenic variants in DCM genes were associated with increased risk of death or major adverse cardiac events (hazard ratio 1.57, 95% confidence interval [CI] 1.22-2.01, p < 0.001). Of 1619 individuals with CAD included from the UKB CMR substudy, participants with a rare variant in a DCM-associated gene had lower left ventricular ejection fraction (LVEF) compared to genotype negative individuals (mean 47 ± 10% vs. 57 ± 8%, p < 0.001). Of 453 patients in the London cohort, 63 (14%) had non-infarct pattern LGE (NI-LGE) on CMR. Patients with NI-LGE had lower LVEF (mean 38 ± 18% vs. 48 ± 16%, p < 0.001) compared to patients without NI-LGE, with no significant difference in the burden of rare protein altering variants in DCM-associated genes between groups (9.5% vs. 6.7%, odds ratio 1.5, 95% CI 0.4-4.3, p = 0.4). NI-LGE was not independently associated with adverse clinical outcomes. CONCLUSION: Rare pathogenic variants in DCM-associated genes impact left ventricular remodelling and outcomes in stable CAD. NI-LGE is associated with adverse remodelling but is not an independent predictor of outcome and had no rare genetic basis in our study.

Comprehensive Phenotypic Characterization of Late Gadolinium Enhancement Predicts Sudden Cardiac Death in Coronary Artery Disease.

BACKGROUND: Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) offers the potential to noninvasively characterize the phenotypic substrate for sudden cardiac death (SCD). OBJECTIVES: The authors assessed the utility of infarct characterization by CMR, including scar microstructure analysis, to predict SCD in patients with coronary artery disease (CAD). METHODS: Patients with stable CAD were prospectively recruited into a CMR registry. LGE quantification of core infarction and the peri-infarct zone (PIZ) was performed alongside computational image analysis to extract morphologic and texture scar microstructure features. The primary outcome was SCD or aborted SCD. RESULTS: Of 437 patients (mean age: 64 years; mean left ventricular ejection fraction [LVEF]: 47%) followed for a median of 6.3 years, 49 patients (11.2%) experienced the primary outcome. On multivariable analysis, PIZ mass and core infarct mass were independently associated with the primary outcome (per gram: HR: 1.07 [95% CI: 1.02-1.12]; P = 0.002 and HR: 1.03 [95% CI: 1.01-1.05]; P = 0.01, respectively), and the addition of both parameters improved discrimination of the model (Harrell's C-statistic: 0.64-0.79). PIZ mass, however, did not provide incremental prognostic value over core infarct mass based on Harrell's C-statistic or risk reclassification analysis. Severely reduced LVEF did not predict the primary endpoint after adjustment for scar mass. On scar microstructure analysis, the number of LGE islands in addition to scar transmurality, radiality, interface area, and entropy were all associated with the primary outcome after adjustment for severely reduced LVEF and New York Heart Association functional class of >1. No scar microstructure feature remained associated with the primary endpoint when PIZ mass and core infarct mass were added to the regression models. CONCLUSIONS: Comprehensive LGE characterization independently predicted SCD risk beyond conventional predictors used in implantable cardioverter-defibrillator (ICD) insertion guidelines. These results signify the potential for a more personalized approach to determining ICD candidacy in CAD.

Care of suspected long bone fractures in the emergency department: Families' perspectives and priorities.

OBJECTIVE: Despite growing interests in patient-reported outcomes, youth and families are rarely involved in designing quality improvement measures. Few quality indicators exist for the care of children with injuries in the Emergency Department (ED) and extremity fractures are among the most common injuries in children. This study's aim was to identify both parents' and youth's perspectives about ED care in the context of a suspected long-bone fracture. METHODS: Youth (10-18 years old) and their parents were surveyed prospectively during their ED visit. Participants were asked: 1) to identify their main concerns, 2) to identify quality measures that were most important to them, and 3) to evaluate the ED care they received. Descriptive analyses present participants' responses. Continuous data was analyzed using a Student t-test and categorical data using a Chi-square test. RESULTS: Over 15 months, 350 families met eligibility criteria and were approached to participate, of which 300 participants consented and 249 surveys were completed (71% response rate): 148 parents and 101 youth (median age: 12) completed their respective surveys. Participants placed a high importance on several themes: pain management, short length of stay, and quality interactions with ED clinicians. Youth as a group prioritized their overall wellbeing and the ED environment (e.g., waiting room comfort, signage), while parents focused on accurate diagnoses and treatments. The following items were less prioritized: that radiology be close to the ED, to see the radiograph, to have access to a wheelchair, to know the identities of clinicians on the team, and to have access to entertainment. Parents and youth within the same family often did not share the same priorities. Ninety-two percent of parents reported their child's pain was treated, while 81% and 63% of youth reported their pain was treated sufficiently and quickly, respectively. CONCLUSIONS: Parents and youth can identify their priorities for ED care and should be engaged in efforts to improve and report on the quality of care in the ED. Youths' and parents' perspectives are complimentary and may not align, even within families. The priorities identified in this study can help inform quality improvement initiatives and personalized patient care.

Growth Differentiation Factor-15 as a Predictor of Functional Capacity, Frailty, and Ventricular Dysfunction in Patients With Aortic Stenosis and Preserved Left Ventricular Ejection Fraction.

In aortic stenosis (AS), left ventricular (LV) remodeling often occurs before symptom onset, and early intervention may be beneficial. Risk stratification remains challenging and identification of biomarkers may be useful. We evaluated the association between growth differentiation factor-15 (GDF-15) and soluble suppression of tumorigenicity 2 (sST2) and known markers of poor prognosis in AS. Baseline plasma GDF-15 and sST2 levels were measured in 70 patients with moderate-severe AS (aortic valve area <1.5 cm2) and preserved LV ejection fraction (>45%). Patients were categorized into "low GDF-15" versus "high GDF-15" and "low sST2" versus "high sST2" groups. Groups were compared for differences in cardiovascular risk factors, 6-minute walk test, 5 m gait speed, cognitive function (Montreal Cognitive Assessment), and echocardiographic parameters. Overall, 44% of patients were deemed asymptomatic by New York Heart Association class, 61% had severe AS (aortic valve area <1 cm2) and all patients had preserved LV ejection fraction. GDF-15 levels were not predictive of AS severity. However, high GDF-15 (>1,050 pg/ml) was associated with LV dysfunction as shown by lower indexed stroke volume (p <0.01), worse LV global longitudinal strain (p = 0.04), greater mean E/e' (p = 0.02) and indexed left atrial volume (p <0.01). It was also associated with decreased functional capacity with shorter 6-minute walk test (p = 0.01) and slower 5 m gait speed (p = 0.02). Associations between sST2 levels and markers of poor prognosis were less compelling. In this study of patients with moderate to severe AS, elevated GDF-15 levels are associated with impaired functional capacity, poorer performance on fragility testing, and LV dysfunction. In conclusion, GDF-15 may integrate these markers of adverse outcomes into a single biomarker of poor prognosis.

Association Between Right Ventricular Dysfunction and Adverse Outcomes in Peripartum Cardiomyopathy: Insights From the BRO-HF Quebec Cohort Study.

Background: Peripartum cardiomyopathy (PPCM) is associated with severe morbidity and mortality, and the significance of right ventricular (RV) involvement is unclear. We sought to determine whether RV systolic dysfunction or dilatation is associated with adverse clinical outcomes in women with PPCM. Methods: We conducted a multicentre retrospective cohort study examining the association between echocardiographic RV systolic dysfunction or dilatation at the time of PPCM diagnosis and clinical outcomes. Clinical endpoints of interest were the need for mechanical support, recovery of left ventricular ejection fraction at follow-up, and a combined endpoint of hospitalization for heart failure, cardiac transplant, or death. Results: A total of 67 women, median age 30 years (interquartile range: 7), were diagnosed with PPCM between 1994 and 2015 in 17 participating centres. Twin pregnancies occurred in 11%; 62% of women were multiparous; and 24% had preeclampsia. RV systolic function was impaired in 18 (27%) and dilated in 8 (12%). Seven women required ventricular assistance, and 8 experienced the composite outcome during follow-up (25 [interquartile range 61] months). RV dysfunction was associated with the need for mechanical support (odds ratio 10.10 (95% confidence interval: 1.86-54.81), P = 0.007), but neither RV dysfunction nor dilatation was associated with left ventricular ejection fraction recovery, the need for cardiac transplant, heart failure hospitalization, or death. Conclusions: RV dysfunction is associated with the need for mechanical support in women with PPCM. These findings may improve risk stratification of complications and clinical management.

Introduction: La cardiomyopathie du péripartum (CMP-PP) est associée à la morbidité grave et à la mortalité, mais on ignore l'importance de l'atteinte ventriculaire droite (VD). Nous avons cherché à déterminer si la dysfonction systolique ou la dilatation VD sont associées aux résultats cliniques défavorables chez les femmes atteintes de CMP-PP. Méthodes: Nous avons mené une étude de cohorte rétrospective multicentrique sur l'association entre la dysfonction systolique ou la dilatation VD à l'échographie au moment du diagnostic de CMP-PP et les résultats cliniques. Les critères cliniques d'intérêt étaient la nécessité d'une assistance mécanique, la récupération de la fraction d'éjection ventriculaire gauche (FEVG) au suivi et un critère combiné d'hospitalisation liée à l'insuffisance cardiaque (IC), la transplantation cardiaque ou la mort. Résultats: Un total de 67 femmes, dont l'âge médian était de 30 ans (écart interquartile [EI] : 7), ont reçu un diagnostic de CMP-PP entre 1994 et 2015 dans 17 centres participants. Les grossesses gémellaires sont survenues chez 11 % ; 62 % de femmes étaient multipares ; et 24 % souffraient de prééclampsie. La fonction systolique VD était compromise chez 18 (27 %) femmes et le VD, dilaté, chez huit (12 %) femmes. Sept femmes ont eu besoin d'une assistance ventriculaire, et huit ont subi le critère composite durant le suivi (25 [EI : 61] mois). La dysfonction VD a été associée à la nécessité d'une assistance mécanique (rapport de cotes 10,10 [intervalle de confiance à 95 % : 1,86-54,81], P = 0,007), mais ni la dysfonction ni la dilatation VD n'ont été associées à la récupération de la FEVG, à la nécessité d'une transplantation cardiaque, à une hospitalisation liée à l'IC ou à la mort. Conclusions: La dysfonction VD est associée à la nécessité d'une assistance mécanique chez les femmes atteintes de CMP-PP. Ces conclusions peuvent permettre d'améliorer la stratification des risques de complications et la prise en charge clinique.

Sex as a main determinant of bi-atrial acute and chronic adaptation to exercise.

PURPOSE: Athlete's heart encompasses multiple physiological cardiac adaptations, although less is known at atrial level. How sex may influence the type and extent of atrial adaptations to exercise stimuli is also unknown. Our objective was to compare gender differences of echocardiographic atrial function indices in response to exercise in endurance athletes (EAs). METHODS: Highly trained (> 10 h/week) endurance athletes performed a maximal cardiopulmonary exercise test (CPET). Echocardiographic evaluation was performed at rest and immediately after exercise. Atria analysis consisted of standard and speckle-tracking echocardiographic assessment of atrial dimensions and contractile, reservoir, and conduit functions with myocardial deformation. RESULTS: 80 EAs (55% women) were enrolled and performed excellent CPET (129.6% of predicted VO2 maximal consumption). At rest, left atrial (LA) volumes and strain were similar between men and women. Women had lower right atrial (RA) volumes (26.7 vs 32.9 ml/m2, p < 0.001) and higher reservoir and conduit strain absolute values. After exercise, women exhibited a larger improvement in reservoir and conduit LA strain, and the same trend was observed for the RA. In EAs with LA dilatation on baseline (~ 50%), women persistently showed higher increase in reservoir and conduit strain profile with exercise compared to men. CONCLUSION: In highly trained EAs, women have similar or even lower atrial dimensions remodelling compared to men, but better function based on reservoir and conduit strain values both at rest and in response to exercise. This phenomenon should be confirmed in larger studies and its potential role in the development of supraventricular arrhythmias, addressed in a specifically designed protocol.

Cardiopulmonary Rehabilitation in Long-COVID-19 Patients with Persistent Breathlessness and Fatigue: The COVID-Rehab Study.

(1) Background: Cardiopulmonary and brain functions are frequently impaired after COVID-19 infection. Exercise rehabilitation could have a major impact on the healing process of patients affected by long COVID-19. (2) Methods: The COVID-Rehab study will investigate the effectiveness of an eight-week cardiopulmonary rehabilitation program on cardiorespiratory fitness (V˙O2max) in long-COVID-19 individuals. Secondary objectives will include functional capacity, quality of life, perceived stress, sleep quality (questionnaires), respiratory capacity (spirometry test), coagulation, inflammatory and oxidative-stress profile (blood draw), cognition (neuropsychological tests), neurovascular coupling and pulsatility (fNIRS). The COVID-Rehab project was a randomised clinical trial with two intervention arms (1:1 ratio) that will be blindly evaluated. It will recruit a total of 40 individuals: (1) rehabilitation: centre-based exercise-training program (eight weeks, three times per week); (2) control: individuals will have to maintain their daily habits. (3) Conclusions: Currently, there are no specific rehabilitation guidelines for long-COVID-19 patients, but preliminary studies show encouraging results. Clinicaltrials.gov (NCT05035628).

Hemisynthesis and Biological Evaluation of Cinnamylated, Benzylated, and Prenylated Dihydrochalcones from a Common Bio-Sourced Precursor.

Several families of naturally occurring C-alkylated dihydrochalcones display a broad range of biological activities, including antimicrobial and cytotoxic properties, depending on their alkylation sidechain. The catalytic Friedel-Crafts alkylation of the readily available aglycon moiety of neohesperidin dihydrochalcone was performed using cinnamyl, benzyl, and isoprenyl alcohols. This procedure provided a straightforward access to a series of derivatives that were structurally related to natural balsacones, uvaretin, and erioschalcones, respectively. The antibacterial and cytotoxic potential of these novel analogs was evaluated in vitro and highlighted some relations between the structure and the pharmacological properties of alkylated dihydrochalcones.

Assessment of myocardial deformation with CMR: a comparison with ultrasound speckle tracking.

OBJECTIVES: Myocardial deformation integrated with cardiac dimensions provides a comprehensive assessment of cardiac function, which has proven useful to differentiate cardiac pathology from physiological adaptation to situations such as chronic intensive training. Feature tracking (FT) can measure myocardial deformation from cardiac magnetic resonance (CMR) cine sequences; however, its accuracy is not yet fully validated. Our aim was to compare the accuracy and reproducibility of FT with speckle tracking echocardiography (STE) in highly trained endurance athletes. METHODS: Ninety-three endurance athletes (> 12-h training/week during the last 5 years, 52% male, 35 ± 5.1 years old) and 72 age-matched controls underwent resting CMR and transthoracic echocardiography to assess biventricular exercise-induced remodeling and biventricular global longitudinal strain (GLS) by CMR-FT and STE. RESULTS: Strain values were significantly lower when assessed by CMR-FT compared to STE (p < 0.001), with good reproducibility for the left ventricle (bias = 3.94%, limit of agreement [LOA] = ± 4.27 %) but wider variability for right ventricle strain. Strain values by both techniques proportionally decreased with increasing ventricular volumes, potentially depicting the functional biventricular reserve that characterizes athletes' hearts. CONCLUSIONS: Biventricular longitudinal strain values were lower when assessed by FT as compared to STE. Both methods were statistically comparable when measuring LV strain but not RV strain. These differences might be justified by the lower in-plane spatial and temporal resolution of FT, which is particularly relevant for the complex anatomy of the RV. KEY POINTS: • Strain values were significantly lower when assessed by FT as compared to STE, which was expected due to the lower in-plane spatial and temporal resolution of FT versus STE. • Both methods were statistically comparable when measuring LV strain but not for RV strain analysis. • Characterizing the normal ranges and reproducibility of strain metrics by FT is an important step toward its clinical applicability, since it can be assessed offline and applied to routinely acquired cine CMR images.

Balsacone C, a New Antibiotic Targeting Bacterial Cell Membranes, Inhibits Clinical Isolates of Methicillin-Resistant Staphylococcus aureus (MRSA) Without Inducing Resistance.

New options are urgently needed for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Balsacone C is a new dihydrochalcone extracted from Populus balsamifera that has been reported previously as being active against Staphylococcus aureus. Here, we evaluate the antibacterial activity of balsacone C against MRSA. Thirty-four (34) MRSA isolates were obtained from hospitalized patients; these isolates were then characterized for their resistance. Most of these MRSA (>85%) were resistant to penicillin, amoxicillin/clavulanic acid, ciprofloxacin, moxifloxacin, levofloxacin, clindamycin, erythromycin, and cefoxitin as well as being sensitive to linezolid, trimethoprim/sulfamethoxazole, rifampicin, and gentamicin. When tested against all MRSA isolates and various gram-positive bacteria, the antibacterial activity of balsacone C produced a MIC of 3-11.6 mg/mL. We observed no resistant isolates of MRSA (against balsacone C) even after 30 passages. Microscopy fluorescence showed that bacteria cell membrane integrity was compromised by low concentrations of balsacone C. Scanning electron microscope (SEM) confirmed balsacone C-provoked changes in the bacterial cell membrane and we find a dose-dependent release of DNA and proteins. This loss of cellular integrity leads to cell death and suggests a low potential for the development of spontaneous resistance.

Dihydrochalcone Derivatives from Populus balsamifera L. Buds for the Treatment of Psoriasis.

Psoriasis is a skin disorder characterized by epidermal hyperplasia, hyperkeratosis, and inflammation. The treatments currently available on the market only improve patients' quality of life and are associated with undesirable side effects. Thus, research leading to the development of new, effective, and safer therapeutic agents is still relevant. Populus balsamifera L. buds were used traditionally by Native Americans to treat various skin pathologies such as eczema and psoriasis. In this study, the antipsoriatic activities of dihydrochalcone derivatives from Populus balsamifera L. buds, known as balsacones, were investigated. The experiments were performed in vitro using a psoriatic skin substitute model. Also, anti-inflammatory and antioxidant activities were investigated. The tested balsacones showed promising antipsoriatic properties by slowing down cell growth and by regulating the expression of involucrin, loricrin, and Ki67 better than methotrexate in psoriatic substitutes. All five tested compounds could be an effective topical treatment for psoriasis, with promising anti-inflammatory and antioxidant actions that may contribute to clinical improvement in patients with psoriasis.

The effect of bromocriptine on left ventricular functional recovery in peripartum cardiomyopathy: insights from the BRO-HF retrospective cohort study.

AIMS: Bromocriptine is thought to facilitate left ventricular (LV) recovery in peripartum cardiomyopathy (PPCM) through inhibition of prolactin secretion. However, this potential therapeutic effect remains controversial and was incompletely studied in diverse populations. METHODS AND RESULTS: Consecutive women with new-onset PPCM (n = 76) between 1994 and 2015 in Quebec, Canada, were classified according to treatment (n = 8, 11%) vs. no treatment (n = 68, 89%) with bromocriptine. We assessed LV functional recovery at mid-term (6 months) and long-term (last follow-up) and compared outcomes among groups. Women treated with bromocriptine experienced better mid-term left ventricular ejection fraction (LVEF) recovery from 23 ± 10% at baseline to 55 ± 12% at 6 months, compared with a change from 30 ± 12% at baseline to 45 ± 13% at 6 months in women treated with standard medical therapy (P interaction < 0.01). At long-term, a similar positive association was found with bromocriptine (9% greater LVEF variation, P interaction < 0.01). In linear regressions adjusted for obstetrical, clinical, echocardiographic, and pharmacological variables, treatment with bromocriptine was associated with a greater improvement in LVEF [ß coefficient (standard error), 14.1 (4.4); P = 0.03]. However, there was no significant association between bromocriptine use and the combined occurrence of all-cause death and heart failure events (hazard ratio, 1.18; 95% confidence interval, 0.15 to 9.31), using univariable Cox regressions based over a cumulative follow-up period of 285 patient-years. CONCLUSIONS: In women newly diagnosed with PPCM, treatment with bromocriptine was independently associated with greater LV functional recovery.

Understanding the patient perspective on research access to national health records databases for conduct of randomized registry trials.

BACKGROUND: Use of health administrative databases is proposed for screening and monitoring of participants in randomized registry trials. However, access to these databases raises privacy concerns. We assessed patient's preferences regarding use of personal information to link their research records with national health databases, as part of a hypothetical randomized registry trial. METHODS AND RESULTS: Cardiology patients were invited to complete an anonymous self-reported survey that ascertained preferences related to the concept of accessing government health databases for research, the type of personal identifiers to be shared and the type of follow-up preferred as participants in a hypothetical trial. A total of 590 responders completed the survey (90% response rate), the majority of which were Caucasians (90.4%), male (70.0%) with a median age of 65years (interquartile range, 8). The majority responders (80.3%) would grant researchers access to health administrative databases for screening and follow-up. To this end, responders endorsed the recording of their personal identifiers by researchers for future record linkage, including their name (90%), and health insurance number (83.9%), but fewer responders agreed with the recording of their social security number (61.4%, p<0.05 with date of birth as reference). Prior participation in a trial predicted agreement for granting researchers access to the administrative databases (OR: 1.69, 95% confidence interval: 1.03-2.90; p=0.04). CONCLUSION: The majority of Cardiology patients surveyed were supportive of use of their personal identifiers to access administrative health databases and conduct long-term monitoring in the context of a randomized registry trial.

Description of the immune microenvironment of chondrosarcoma and contribution to progression.

Chondrosarcoma (CHS) is a rare bone malignancy characterized by its resistance to conventional systemic and radiation therapies. Whether immunotherapy targeting immune checkpoints may be active in these tumors remains unknown. To explore the role of the immune system in this tumor, we analyzed the immune environment of chondrosarcomas both in human sample, and in a syngeneic rat model, and tested the contribution of T lymphocytes and macrophages in chondrosarcoma progression. Immunohistochemical stainings were performed on human chondrosarcoma samples and on Swarm rat chondrosarcoma (SRC) model. Selective immunodepletion assays were performed in SRC to evaluate immune population's involvement in tumor progression. In human and rat chondrosarcoma, immune infiltrates composed of lymphocytes and macrophages were identified in the peritumoral area. Immune infiltrates composition was found correlated with tumors characteristics and evolution (grade, invasiveness and size). In SRC, selective depletion of T lymphocytes resulted in an accelerated growth rates, whereas depletion of CD163+ macrophages slowed down tumor progression. Splenocytes isolated from CHS-bearing SRC showed a specific cytotoxicity directed against chondrosarcoma cells (27%), which significantly decreased in CD3-depleted SRC (11%). The immune environment contributes to CHS progression in both human and animal models, suggesting that immunomodulatory approaches could be tested in bone chondrosarcoma.

Structure elucidation of anti-methicillin resistant Staphylococcus aureus (MRSA) flavonoids from balsam poplar buds.

There is nowadays an urgent need for developing novel generations of antibiotic agents due to the increased resistance of pathogenic bacteria. As a rich reservoir of structurally diverse compounds, plant species hold promise in this regard. Within this framework, we isolated a unique series of antibacterial flavonoids, named balsacones N-U, featuring multiple cinnamyl chains on the flavan skeleton. The structures of these compounds, isolated as racemates, were determined using extensive 1D and 2D NMR analysis in tandem with HRMS. Balsacones N-U along with previously isolated balsacones A-M were evaluated for their antibacterial activity against clinical isolates of methicillin resistant Staphylococcus aureus (MRSA). Several of the tested balsacones were potent anti-MRSA agents showing MIC values in the low micromolar range. Structure-activity relationships study highlighted some important parameters involved in the antibacterial activity of balsacones such as the presence of cinnamyl and cinnamoyl chains at the C-3 and C-8 positions of the flavan skeleton, respectively. These results suggest that balsacones could represent a potential novel class of naturally occurring anti-MRSA agents.

Activation of TAK1 by Chemotactic and Growth Factors, and Its Impact on Human Neutrophil Signaling and Functional Responses.

The MAP3 kinase, TAK1, is known to act upstream of IKK and MAPK cascades in several cell types, and is typically activated in response to cytokines (e.g., TNF, IL-1) and TLR ligands. In this article, we report that in human neutrophils, TAK1 can also be activated by different classes of inflammatory stimuli, namely, chemoattractants and growth factors. After stimulation with such agents, TAK1 becomes rapidly and transiently activated. Blocking TAK1 kinase activity with a highly selective inhibitor (5z-7-oxozeaenol) attenuated the inducible phosphorylation of ERK occurring in response to these stimuli but had little or no effect on that of p38 MAPK or PI3K. Inhibition of TAK1 also impaired MEKK3 (but not MEKK1) activation by fMLF. Moreover, both TAK1 and the MEK/ERK module were found to influence inflammatory cytokine expression and release in fMLF- and GM-CSF-activated neutrophils, whereas the PI3K pathway influenced this response independently of TAK1. Besides cytokine production, other responses were found to be under TAK1 control in neutrophils stimulated with chemoattractants and/or GM-CSF, namely, delayed apoptosis and leukotriene biosynthesis. Our data further emphasize the central role of TAK1 in controlling signaling cascades and functional responses in primary neutrophils, making it a promising target for therapeutic intervention in view of the foremost role of neutrophils in several chronic inflammatory conditions.

MEK-independent ERK activation in human neutrophils and its impact on functional responses.

Neutrophils influence innate and adaptative immunity, notably through the generation of numerous cytokines and chemokines and through the modulation of their constitutive apoptosis. Several signaling cascades are known to control neutrophil responses, including the MEK pathway, which is normally coupled to ERK. However, we show here that in human neutrophils stimulated with cytokines or TLR ligands, MEK and ERK are activated independently of each other. Pharmacological blockade of MEK had no effect on the induction of ERK kinase activity and vice versa. In autologous PBMC exposed to the same stimuli or in neutrophils exposed to chemoattractants, this uncoupling of MEK and ERK was not observed. Whereas we had shown before that MEK inhibition impairs cytokine generation translationally in LPS- or TNF-stimulated neutrophils, ERK inhibition affected this response transcriptionally and translationally. Transcriptional targets or ERK include the mitogen- and stress-activated protein kinase 1 (MSK-1) and its substrates, C/EBPß and CREB, whereas translational targets include the S6 kinase and its substrate, the S6 ribosomal protein. In addition to affecting cytokine production, ERK inhibition interfered with how LPS or TNF promotes neutrophil survival and levels of the myeloid cell leukemia 1 (Mcl-1) antiapoptotic protein. Whereas the ERK-activating kinase was not identified, we found that the MAP3K, TGF-ß-activated kinase 1 (TAK1), acts upstream of ERK and MEK in neutrophils. Our results document a functional uncoupling of the MEK/ERK module under certain stimulatory conditions and suggest that therapeutic strategies based on MEK inhibition might benefit from being complemented by ERK inhibition, particularly in chronic inflammatory conditions featuring a strong neutrophilic component.

Antibacterial Balsacones J-M, Hydroxycinnamoylated Dihydrochalcones from Populus balsamifera Buds.

A phytochemical investigation of buds from the hardwood tree Populus balsamifera led to the isolation of six new cinnamoylated dihydrochalcones as pairs of racemates and one as a racemic mixture along with the known compound iryantherin-D (2), the absolute configuration of which was determined for the first time. The structures of balsacones J (1), K (3), L (4), and M (5) were elucidated on the basis of spectroscopic data (1D and 2D NMR, IR, and MS). Chiral HPLC separations were carried out, and the absolute configuration of the isolated enantiomers unambiguously established via X-ray diffraction analyses and electron circular dichroism spectroscopic data. Each of the purified enantiomers exhibited potent in vitro antibacterial activity against Staphylococcus aureus with IC50 values ranging from 0.61 to 6 µM.

Balsacones D-I, dihydrocinnamoyl flavans from Populus balsamifera buds.

A phytochemical investigation of an ethanolic extract from Populus balsamifera L. buds resulted in the isolation and characterization of twelve new flavan derivatives consisting of six pairs of enantiomers. Structures of (+) and (-)-balsacones D-I were elucidated based on spectroscopic data (1D and 2D NMR, MS) and their absolute configurations were established using X-ray single crystal diffraction analysis and ECD computational calculations. Antibacterial activity and cytotoxicity of all purified enantiomers were evaluated in vitro against Staphylococcus aureus and human skin fibroblast cells, respectively.

The p38-MSK1 signaling cascade influences cytokine production through CREB and C/EBP factors in human neutrophils.

Neutrophils influence innate and adaptative immunity by generating numerous cytokines and chemokines whose regulation largely depends on transcriptional activators such as NF-κB and C/EBP factors. In this study, we describe the critical involvement of CREB transcription factors (CREB1 and activating transcription factor-1) in this functional response as well as relevant upstream signaling components. Neutrophil stimulation with LPS or TNF led to the phosphorylation, DNA binding activity, and chemokine promoter association of CREB1 and activating transcription factor-1. These responses occurred downstream of the p38-MSK1 signaling axis, as did the phosphorylation and promoter association of another bZIP factor, C/EBPß. Conversely, inhibition of RSK1 failed to alter the phosphorylation of either CREB1 or C/EBPß in neutrophils. From a more functional standpoint, the inhibition of p38 MAPK or MSK1 interfered with cytokine generation in neutrophils. Likewise, overexpression of a dominant-negative CREB1 mutant (K-CREB) or of a point mutant (S133A) resulted in a decreased ability of human neutrophil-like PLB-985 cells to generate inflammatory cytokines (CXCL8, CCL3, CCL4, and TNF-α). Collectively, our data show the involvement of CREB1 in neutrophil cytokine production, the key role of its S133 residue, important upstream signaling events, and the parallel activation of another bZIP factor. These are all potential molecular targets that could be exploited in the context of several chronic inflammatory diseases that prominently feature neutrophils and their products.