Interaction of the Joining Region in Junctophilin-2 With the L-Type Ca2+ Channel Is Pivotal for Cardiac Dyad Assembly and Intracellular Ca2+ Dynamics.

RATIONALE: Ca2+-induced Ca2+ release (CICR) in normal hearts requires close approximation of L-type calcium channels (LTCCs) within the transverse tubules (T-tubules) and RyR (ryanodine receptors) within the junctional sarcoplasmic reticulum. CICR is disrupted in cardiac hypertrophy and heart failure, which is associated with loss of T-tubules and disruption of cardiac dyads. In these conditions, LTCCs are redistributed from the T-tubules to disrupt CICR. The molecular mechanism responsible for LTCCs recruitment to and from the T-tubules is not well known. JPH (junctophilin) 2 enables close association between T-tubules and the junctional sarcoplasmic reticulum to ensure efficient CICR. JPH2 has a so-called joining region that is located near domains that interact with T-tubular plasma membrane, where LTCCs are housed. The idea that this joining region directly interacts with LTCCs and contributes to LTCC recruitment to T-tubules is unknown. OBJECTIVE: To determine if the joining region in JPH2 recruits LTCCs to T-tubules through direct molecular interaction in cardiomyocytes to enable efficient CICR. METHODS AND RESULTS: Modified abundance of JPH2 and redistribution of LTCC were studied in left ventricular hypertrophy in vivo and in cultured adult feline and rat ventricular myocytes. Protein-protein interaction studies showed that the joining region in JPH2 interacts with LTCC-α1C subunit and causes LTCCs distribution to the dyads, where they colocalize with RyRs. A JPH2 with induced mutations in the joining region (mutPG1JPH2) caused T-tubule remodeling and dyad loss, showing that an interaction between LTCC and JPH2 is crucial for T-tubule stabilization. mutPG1JPH2 caused asynchronous Ca2+-release with impaired excitation-contraction coupling after ß-adrenergic stimulation. The disturbed Ca2+ regulation in mutPG1JPH2 overexpressing myocytes caused calcium/calmodulin-dependent kinase II activation and altered myocyte bioenergetics. CONCLUSIONS: The interaction between LTCC and the joining region in JPH2 facilitates dyad assembly and maintains normal CICR in cardiomyocytes.

Loss of Trex1 in Dendritic Cells Is Sufficient To Trigger Systemic Autoimmunity.

Defects of the intracellular enzyme 3' repair exonuclease 1 (Trex1) cause the rare autoimmune condition Aicardi-Goutières syndrome and are associated with systemic lupus erythematosus. Trex1(-/-) mice develop type I IFN-driven autoimmunity, resulting from activation of the cytoplasmic DNA sensor cyclic GMP-AMP synthase by a nucleic acid substrate of Trex1 that remains unknown. To identify cell types responsible for initiation of autoimmunity, we generated conditional Trex1 knockout mice. Loss of Trex1 in dendritic cells was sufficient to cause IFN release and autoimmunity, whereas Trex1-deficient keratinocytes and microglia produced IFN but did not induce inflammation. In contrast, B cells, cardiomyocytes, neurons, and astrocytes did not show any detectable response to the inactivation of Trex1. Thus, individual cell types differentially respond to the loss of Trex1, and Trex1 expression in dendritic cells is essential to prevent breakdown of self-tolerance ensuing from aberrant detection of endogenous DNA.

Atrial selectivity of antiarrhythmic drugs.

New antiarrhythmic drugs for treatment of atrial fibrillation should ideally be atrial selective in order to avoid pro-arrhythmic effects in the ventricles. Currently recognized atrial selective targets include atrial Nav1.5 channels, Kv1.5 channels and constitutively active Kir3.1/3.4 channels, each of which confers atrial selectivity by different mechanisms. Na(+) channel blockers with potential- and frequency-dependent action preferentially suppress atrial fibrillation because of the high excitation rate and less negative atrial resting potential, which promote drug binding in atria. Kv1.5 channels are truly atrial selective because they do not conduct repolarizing current IKur in ventricles. Constitutively active IK,ACh is predominantly observed in remodelled atria from patients in permanent atrial fibrillation (AF). A lot of effort has been invested to detect compounds which will selectively block Kir3.1/Kir3.4 in their remodelled constitutively active form. Novel drugs which have been and are being developed aim at atrial-selective targets. Vernakalant and ranolazine which mainly block atrial Na(+) channels are clinically effective. Newly designed selective IKur blockers and IK,ACh blockers are effective in animal models; however, clinical benefit in converting AF into sinus rhythm (SR) or reducing AF burden remains to be demonstrated. In conclusion, atrial-selective antiarrhythmic agents have a lot of potential, but a long way to go.

Differentiation efficiency of induced pluripotent stem cells depends on the number of reprogramming factors.

Reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) by retroviral overexpression of the transcription factors Oct4, Sox2, Klf4, and c-Myc holds great promise for the development of personalized cell replacement therapies. In an attempt to minimize the risk for chromosomal disruption and to simplify reprogramming, several studies demonstrated that a reduced set of reprogramming factors is sufficient to generate iPSC, albeit at lower efficiency. To elucidate the influence of factor reduction on subsequent differentiation, we compared the efficiency of neuronal differentiation in iPSC generated from postnatal murine neural stem cells with either one (Oct4; iPSC(1F-NSC) ), two (Oct4, Klf4; iPSC(2F-NSC) ), or all four factors (iPSC(4F-NSC) ) with those of embryonic stem cells (ESCs) and iPSC produced from fibroblasts with all four factors (iPSC(4F-MEF) ). After 2 weeks of coculture with PA6 stromal cells, neuronal differentiation of iPSC(1F-NSC) and iPSC(2F-NSC) was less efficient compared with iPSC(4F-NSC) and ESC, yielding lower proportions of colonies that stained positive for early and late neuronal markers. Electrophysiological analyses after 4 weeks of differentiation identified functional maturity in neurons differentiated from ESC, iPSC(2F-NSC) , iPSC(4F-NSC) , and iPSC(4F-MEF) but not in those from iPSC(1F-NSC) . Similar results were obtained after hematoendothelial differentiation on OP9 bone marrow stromal cells, where factor-reduced iPSC generated lower proportions of colonies with hematoendothelial progenitors than colonies of ESC, iPSC(4F-NSC) , and iPSC(4F-MEF) . We conclude that a reduction of reprogramming factors does not only reduce reprogramming efficiency but may also worsen subsequent differentiation and hinder future application of iPSC in cell replacement therapies.

Characterization of 164 patients with NRAS mutated non-small cell lung cancer (NSCLC).

BACKGROUND: NRAS mutations are observed in less than 1% of non-small cell lung cancer (NSCLC). Clinical data regarding this rare subset of lung cancer are scarce and response to systemic treatment such as chemotherapy or immune checkpoint inhibitors (ICI) has never been reported. METHODS: All consecutive patients with an NRAS mutated NSCLC, diagnosed between August 2014 and November 2020 in 14 French centers, were included. Clinical and molecular data were collected and reviewed from medical records. RESULTS: Out of the 164 included patients, 106 (64.6%) were men, 150 (91.5%) were current or former smokers, and 104 (63.4%) had stage IV NSCLC at diagnosis. The median age was 62 years, and the most frequent histology was adenocarcinoma (81.7%). NRAS activating mutations were mostly found in codon 61 (70%), while codon 12 and 13 alterations were observed in 16.5% and 4.9% of patients, respectively. Programmed death ligand-1 expression level <1%/1-49%/≥50% were respectively found in 30.8%/27.1%/42.1% of tumors. With a median follow-up of 12.5 months, median overall survival (OS) of stage IV patients was 15.3 months (95% CI 9.9-27.6). No significant difference in OS was found according to the type of mutation (codon 61 vs. other), HR = 1.12 (95% CI 0.65-1.95). Among stage IV patients treated with platinum-based doublet (n = 66), ICI (n = 48), or combination of both (n = 10), objective response rate, and median progression free survival were respectively 45% and 5.8 months, 35% and 6.9 months, 70% and 8.6 months. CONCLUSION: NRAS mutated NSCLC are characterized by a high frequency of smoking history and codon 61 mutations. Further studies are needed to confirm the encouraging outcome of immunotherapy in combination with chemotherapy.

A new approach to transcription factor screening for reprogramming of fibroblasts to cardiomyocyte-like cells.

The simultaneous overexpression of several transcription factors has emerged as a successful strategy to convert fibroblasts into other cell types including pluripotent cells, neurons, and cardiomyocytes. The selection and screening of factors are critical, and have often involved testing a large pool of transcription factors, followed by successive removal of single factors. Here, to identify a cardiac transcription factor combination facilitating mouse fibroblast reprogramming into cardiomyocytes, we directly screened all triplet combinations of 10 candidate factors combined with a Q-PCR assay reporting induction of multiple cardiac-specific genes. Through this screening method the combination of Tbx5, Mef2c, and Myocd was identified to upregulate a broader spectrum of cardiac genes compared to the combination of Tbx5, Mef2c, and Gata4 that was recently shown to induce reprogramming of fibroblasts into cardiomyocytes. Cells cotransduced with Tbx5, Mef2c, Myocd expressed cardiac contractile proteins, had cardiac-like potassium and sodium currents and action potentials could be elicited. In summary the alternative screening approach that is presented here avoided the elimination of transcription factors whose potency is masked in complex transcription factor mixes. Furthermore, our results point to the importance of verifying multiple lineage specific genes when assessing reprogramming.

Skeletal muscle stem cells propagated as myospheres display electrophysiological properties modulated by culture conditions.

In cardiac regenerative therapy, transplantation of stem cells to form new myocardium is limited by their inability to integrate into host myocardium and conduct cardiac electrical activity. It is now hypothesized that refining cell sorting could upgrade the therapeutic result. Here we characterized a subpopulation of skeletal muscle stem cells with respect to their electrophysiological properties. The aim of our study was to determine whether electrophysiological parameters are compatible with cardiac function and can be influenced by culture conditions. Low-adherent skeletal muscle stem cells were isolated from the hind legs of 12-20 week old mice. After 6 days of culture the cells were analysed using patch-clamp techniques and RT-PCR, and replated in different media for skeletal muscle or cardiac differentiation. The cells generated action potentials (APs) longer than skeletal muscle APs, expressed functional cardiac Na(+) channels (~46% of the total channel fraction), displayed fast activating and inactivating L-type Ca(2+) currents, possibly conducted through cardiac channels and did not show significant Cl(-) conductance. Moreover, a fraction of cells expressed muscarinic acetylcholine receptors. Conditioning the cells for skeletal muscle differentiation resulted in upregulation of skeletal muscle-specific Na(+) and Ca(2+) channel expression, shortening of AP duration and loss of functional cardiac Na(+) channels. Cardiomyogenic conditions however, promoted the participation of cardiac Na(+) channels (57% of the total channel fraction). Nevertheless the cells retained properties of myoblasts such as the expression of nicotinic acetylcholine receptors. We conclude that skeletal muscle stem cells display several electrophysiological properties similar to those of cardiomyocytes. Culture conditions modulated these properties but only partially succeeded in further driving the cells towards a cardiac phenotype. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".

Rheumatic and musculoskeletal disorders induced by immune checkpoint inhibitors: Consequences on overall survival.

OBJECTIVES: Immune checkpoint inhibitors (ICIs) frequently induce immune related adverse events (irAEs) that may be associated with more favorable clinical outcomes. We aimed to evaluate the impact of all types of rheumatic adverse events (AEs) on overall survival (OS) and tumor response in patients treated with ICIs. METHODS: We performed a single-center retrospective observational study to analyze the OS and tumor response in patients receiving ICIs who experienced a rheumatic AE compared to those who did not experience any AE. RESULTS: From December 2010 to September 2018, 264 patients with any cancer type were included. Forty-three patients (16.3%) presented with at least one rheumatic AE. The median OS of patients with rheumatic AEs was significantly higher than that of patients without AEs, with 132 weeks (95% CI [69.3-not reached]) and 42.7 weeks (95% CI [25.6-not reached]), respectively (P<0.01). This result remained significant after multivariate analysis (HR 0.54, 95% CI [0.30-0.97], P<0.05). Also, tumor response was better in patients with rheumatic AEs. CONCLUSION: The occurrence of rheumatic AEs in patients treated with ICIs is associated with better survival and tumor response. Therefore, it seems essential to detect rheumatic AEs as early as possible to allow rapid and optimal management, given the long-term response potential of these patients.

Salvage Immunotherapy With Pembrolizumab in Patients Hospitalized for Life-Threatening Complications of NSCLC.

INTRODUCTION: It is not known whether patients with NSCLC who are hospitalized because of cancer-related complications are liable to benefit from salvage immunotherapy. METHODS: This is a multicenter observational study including five centers, which involve all patients with advanced-stage NSCLC exhibiting a level of programmed death-ligand 1 (PD-L1) greater than or equal to 1%, having been hospitalized because of complications attributed to the evolution of the NSCLC, and having started pembrolizumab treatment during their hospitalization because of a risk of clinical deterioration in the short term. The analysis measured overall survival (OS) and the rate of discharge to home at 3 months. RESULTS: The study included 33 patients, including 28 (85%) with metastatic NSCLC and 27 (82%) under first-line treatment. The main causes of hospitalization were deterioration of the general condition (52%), acute respiratory failure (18%), and an uncontrolled infection owing to the tumor (15%). A total of 20 patients (60%) had a performance status greater than or equal to 2 and 15 (45%) were under oxygen therapy. A total of 29 patients (88%) had a PD-L1 greater than or equal to 50%. Five patients (15%) started pembrolizumab in the intensive care unit. The median OS was 4.3 months (95% confidence interval [CI]: 0.9-not reached), and the 6-month and 1-year OS rates were 41.5% (95% CI: 27.5%-62.6%) and 32.6% (95% CI: 19.0%-55.9%), respectively. The home discharge rate at 3 months was 39% (95% CI: 23%-58%). CONCLUSIONS: Even when initiated in patients hospitalized for a life-threatening clinical deterioration, pembrolizumab seems to prolong the survival of certain patients with high PD-L1 NSCLC. Prospective, controlled data are necessary to confirm these results.

Junctophilin-2 tethers T-tubules and recruits functional L-type calcium channels to lipid rafts in adult cardiomyocytes.

AIM: In cardiomyocytes, transverse tubules (T-tubules) associate with the sarcoplasmic reticulum (SR), forming junctional membrane complexes (JMCs) where L-type calcium channels (LTCCs) are juxtaposed to Ryanodine receptors (RyR). Junctophilin-2 (JPH2) supports the assembly of JMCs by tethering T-tubules to the SR membrane. T-tubule remodelling in cardiac diseases is associated with downregulation of JPH2 expression suggesting that JPH2 plays a crucial role in T-tubule stability. Furthermore, increasing evidence indicate that JPH2 might additionally act as a modulator of calcium signalling by directly regulating RyR and LTCCs. This study aimed at determining whether JPH2 overexpression restores normal T-tubule structure and LTCC function in cultured cardiomyocytes. METHODS AND RESULTS: Rat ventricular myocytes kept in culture for 4 days showed extensive T-tubule remodelling with impaired JPH2 localization and relocation of the scaffolding protein Caveolin3 (Cav3) from the T-tubules to the outer membrane. Overexpression of JPH2 restored T-tubule structure and Cav3 relocation. Depletion of membrane cholesterol by chronic treatment with methyl-ß-cyclodextrin (MßCD) countered the stabilizing effect of JPH2 overexpression on T-tubules and Cav3. Super-resolution scanning patch-clamp showed that JPH2 overexpression greatly increased the number of functional LTCCs at the plasma membrane. Treatment with MßCD reduced LTCC open probability and activity. Proximity ligation assays showed that MßCD did not affect JPH2 interaction with RyR and the pore-forming LTCC subunit Cav1.2, but strongly impaired JPH2 association with Cav3 and the accessory LTCC subunit Cavß2. CONCLUSIONS: JPH2 promotes T-tubule structural stability and recruits functional LTCCs to the membrane, most likely by directly binding to the channel. Cholesterol is involved in the binding of JPH2 to T-tubules as well as in the modulation of LTCC activity. We propose a model where cholesterol and Cav3 support the assembly of lipid rafts which provide an anchor for JPH2 to form JMCs and a platform for signalling complexes to regulate LTCC activity.

Impact of the corticosteroid indication and administration route on overall survival and the tumor response after immune checkpoint inhibitor initiation.

BACKGROUND: Based on their indications, systemic corticosteroids appear to negatively affect clinical outcomes in immune checkpoint inhibitor (ICI)-treated patients. There are few data on the influence of topical and inhaled corticosteroids on the ICIs' effectiveness. METHODS: In a single-center study, we retrospectively investigated the impact of systemic corticosteroids according to their indication [an immune-related adverse event (irAE) or another indication] on overall survival (OS) and the tumor response in all consecutive patients after initiation of ipilimumab, nivolumab or pembrolizumab over a 9-year period. The impacts of topical and inhaled corticosteroids were also examined. RESULTS: Three hundred and seventy-two patients were included. The mean ± standard deviation age was 64.0 ± 12.1 years. The most frequently prescribed ICI was nivolumab (in 58.3% of the patients) and the most frequent indications were lung cancer (44.6%) and melanoma (29.6%). Systemic corticosteroid use for an irAE did not have a negative impact on OS [adjusted hazard ratio (HR) [95% confidence interval (CI)] 1.04 (0.56-1.95), p = 0.902] or the best overall tumor response [adjusted odds ratio (OR) (95% CI) 1.69 (0.52-6.56), p = 0.413], while systemic corticosteroid use for another indication was associated with shorter OS [adjusted HR (95% CI) 1.34 (1.05-2.03), p = 0.046] and a poor best overall tumor response [adjusted OR (95% CI) 2.04 (1.07-5.80), p = 0.039] with a cumulative dose cut-off of 3215 mg prednisolone equivalent (specificity 71.4%; sensitivity 65.3%) and a time cut-off of 132 days (specificity 71.4%; sensitivity 89.8%). The use of topical corticosteroids was associated with a longer OS; this was probably due to dermatological irAEs. Inhaled corticosteroid use did not influence OS. CONCLUSION: Systemic corticosteroid use for an irAE does not impact OS or the tumor response, whereas use for other indications (themselves often associated with a worse prognosis) does. Topical and inhaled steroids do not have a negative impact on OS.

Associations between dysbiosis-inducing drugs, overall survival and tumor response in patients treated with immune checkpoint inhibitors.

BACKGROUND: There are conflicting data on the effects of dysbiosis-inducing drugs, and especially antibiotics (ATBs), on clinical outcomes in patients treated with immune checkpoint inhibitors (ICIs). There is a particular lack of data for patients with melanoma. METHODS: We performed a single-center retrospective study of the associations between ATBs and other drugs known to modify the gut microbiota (proton pump inhibitors, nonsteroidal anti-inflammatory drugs, statins, opioids, anti-vitamin K, levothyroxine, vitamin D3, antiarrhythmics, metformin and phloroglucinol), overall survival (OS) and tumor response in consecutive cancer patients (particularly those with melanoma) treated with an ICI (ipilimumab, nivolumab or pembrolizumab) over a 9-year period. RESULTS: A total of 372 patients were included. The mean ± standard deviation age was 64.0 ± 12.1 years. The most frequently prescribed ICI was nivolumab (in 58.3% of patients) and the most frequent indications were lung cancer (44.6%) and melanoma (29.6%). Overall, 112 patients (30.1%) had received ATBs. ATB use was associated with (1) shorter OS in the study population as a whole [adjusted hazard ratio [95% confidence interval (CI)]: 1.38 (1.00-1.90), p = 0.048] and in patients with melanoma [adjusted hazard ratio (95% CI): 2.60 (1.06-6.39), p = 0.037], and (2) a lower response rate in the study population as a whole [8.1%, versus 31.1% in patients not treated with ATBs; adjusted odds ratio (95% CI): 6.06 (2.80-14.53), p < 0.001] and in patients with melanoma [adjusted odds ratio (95% CI): 4.41 (1.04-22.80), p = 0.045]. Sensitivity analyses that minimized the indication bias did not reveal an association between OS and the presence of an infection requiring ATBs (quantified as the severity of infection, hospitalization for an infection, or ICI discontinuation). Other dysbiosis-inducing drugs were not associated with a difference in OS. CONCLUSION: Unlike other dysbiosis-inducing drugs, ATBs were associated with poorer clinical outcomes in ICI-treated patients overall and in the subset of patients with melanoma.

Nanoscale regulation of L-type calcium channels differentiates between ischemic and dilated cardiomyopathies.

BACKGROUND: Subcellular localization and function of L-type calcium channels (LTCCs) play an important role in regulating contraction of cardiomyocytes. Understanding how this is affected by the disruption of transverse tubules during heart failure could lead to new insights into the disease. METHODS: Cardiomyocytes were isolated from healthy donor hearts, as well as from patients with cardiomyopathies and with left ventricular assist devices. Scanning ion conductance and confocal microscopy was used to study membrane structures in the cells. Super-resolution scanning patch-clamp was used to examine LTCC function in different microdomains. Computational modeling predicted the impact of these changes to arrhythmogenesis at the whole-heart level. FINDINGS: We showed that loss of structural organization in failing myocytes leads to re-distribution of functional LTCCs from the T-tubules to the sarcolemma. In ischemic cardiomyopathy, the increased LTCC open probability in the T-tubules depends on the phosphorylation by protein kinase A, whereas in dilated cardiomyopathy, the increased LTCC opening probability in the sarcolemma results from enhanced phosphorylation by calcium-calmodulin kinase II. LVAD implantation corrected LTCCs pathophysiological activity, although it did not improve their distribution. Using computational modeling in a 3D anatomically-realistic human ventricular model, we showed how LTCC location and activity can trigger heart rhythm disorders of different severity. INTERPRETATION: Our findings demonstrate that LTCC redistribution and function differentiate between disease aetiologies. The subcellular changes observed in specific microdomains could be the consequence of the action of distinct protein kinases. FUNDING: This work was supported by NIH grant (ROI-HL 126802 to NT-JG) and British Heart Foundation (grant RG/17/13/33173 to JG, project grant PG/16/17/32069 to RAC). Funders had no role in study design, data collection, data analysis, interpretation, writing of the report.

ß3-Adrenoceptor redistribution impairs NO/cGMP/PDE2 signalling in failing cardiomyocytes.

Cardiomyocyte ß3-adrenoceptors (ß3-ARs) coupled to soluble guanylyl cyclase (sGC)-dependent production of the second messenger 3',5'-cyclic guanosine monophosphate (cGMP) have been shown to protect from heart failure. However, the exact localization of these receptors to fine membrane structures and subcellular compartmentation of ß3-AR/cGMP signals underpinning this protection in health and disease remain elusive. Here, we used a Förster Resonance Energy Transfer (FRET)-based cGMP biosensor combined with scanning ion conductance microscopy (SICM) to show that functional ß3-ARs are mostly confined to the T-tubules of healthy rat cardiomyocytes. Heart failure, induced via myocardial infarction, causes a decrease of the cGMP levels generated by these receptors and a change of subcellular cGMP compartmentation. Furthermore, attenuated cGMP signals led to impaired phosphodiesterase two dependent negative cGMP-to-cAMP cross-talk. In conclusion, topographic and functional reorganization of the ß3-AR/cGMP signalosome happens in heart failure and should be considered when designing new therapies acting via this receptor.

Weekly paclitaxel plus bevacizumab versus docetaxel as second- or third-line treatment in advanced non-squamous non-small-cell lung cancer: Results of the IFCT-1103 ULTIMATE study.

PURPOSE: Second-line chemotherapy regimens have demonstrated poor benefit after failure of platinum-based chemotherapy in advanced non-squamous non-small-cell lung cancer (nsNSCLC). METHODS: In this multicentre, open-label phase III trial, patients with advanced nsNSCLC treated with one or two prior lines, including one platinum-based doublet, were centrally randomised to receive 90 mg/m2 of paclitaxel (D1, D8, D15) plus 10 mg/kg of bevacizumab (D1, D15) every 28 days or docetaxel (75 mg/m2) every 21 days; crossover was allowed after disease progression. Primary end-point was progression-free survival (PFS). ClinicalTrials.gov registration number: NCT01763671. RESULTS: One hundred sixty six patients were randomised (paclitaxel plus bevacizumab: 111, docetaxel: 55). The median PFS was longer in patients receiving paclitaxel plus bevacizumab than in patients receveing docetaxel [5·4 months versus 3·9 months, adjusted hazard ratio (HR) 0·61 (95% confidence interval [CI]: 0·44-0·86); p = 0·005]. Objective response rates (ORRs) were 22·5% (95% CI: 14·8-30·3) and 5·5% (95% CI: 0·0-11·5) (p = 0·006), respectively. Median overall survivals were similar (adjusted HR 1·17; p = 0·50). Crossover occurred in 21 of 55 (38·2%) docetaxel-treated patients. Grade III-IV adverse events (AEs) were reported in 45·9% and 54·5% of patients treated with paclitaxel and bevacizumab or docetaxel, respectively (p = NS), including neutropenia (19·3% versus 45·4%), neuropathy (8·3% versus 0·0%) and hypertension (7·3% versus 0·0%). Three patients died due to treatment-related AEs (1·8% in each group). CONCLUSION: Weekly paclitaxel plus bevacizumab as second- or third-line improves PFS and ORR compared with docetaxel in patients with nsNSCLC, with an acceptable safety profile. These results place weekly paclitaxel plus bevacizumab as a valid option in this population. CLINICAL TRIALS REGISTRATION NUMBER: ClinicalTrials.gov Identifier: NCT01763671.

Partial Mechanical Unloading of the Heart Disrupts L-Type Calcium Channel and Beta-Adrenoceptor Signaling Microdomains.

Introduction: We investigated the effect of partial mechanical unloading (PMU) of the heart on the physiology of calcium and beta-adrenoceptor-cAMP (ßAR-cAMP) microdomains. Previous studies have investigated PMU using a model of heterotopic-heart and lung transplantation (HTHAL). These studies have demonstrated that PMU disrupts the structure of cardiomyocytes and calcium handling. We sought to understand these processes by studying L-Type Calcium Channel (LTCC) activity and sub-type-specific ßAR-cAMP signaling within cardiomyocyte membrane microdomains. Method: We utilized an 8-week model of HTHAL, whereby the hearts of syngeneic Lewis rats were transplanted into the abdomens of randomly assigned cage mates. A pronounced atrophy was observed in hearts after HTHAL. Cardiomyocytes were isolated via enzymatic perfusion. We utilized Förster Resonance Energy Transfer (FRET) based cAMP-biosensors and scanning ion conductance microscopy (SICM) based methodologies to study localization of LTCC and ßAR-cAMP signaling. Results: ß2AR-cAMP responses measured by FRET in the cardiomyocyte cytosol were reduced by PMU (loaded 28.51 ± 7.18% vs. unloaded 10.84 ± 3.27% N,n 4/10-13 mean ± SEM ∗ p < 0.05). There was no effect of PMU on ß2AR-cAMP signaling in RII_Protein Kinase A domains. ß1AR-cAMP was unaffected by PMU in either microdomain. Consistent with this SICM/FRET analysis demonstrated that ß2AR-cAMP was specifically reduced in t-tubules (TTs) after PMU (loaded TT 0.721 ± 0.106% vs. loaded crest 0.104 ± 0.062%, unloaded TT 0.112 ± 0.072% vs. unloaded crest 0.219 ± 0.084% N,n 5/6-9 mean ± SEM ∗∗ p < 0.01, ∗∗∗ p < 0.001 vs. loaded TT). By comparison ß1AR-cAMP responses in either TT or sarcolemmal crests were unaffected by the PMU. LTCC occurrence and open probability (Po) were reduced by PMU (loaded TT Po 0.073 ± 0.011% vs. loaded crest Po 0.027 ± 0.006% N,n 5/18-26 mean ± SEM ∗ p < 0.05) (unloaded TT 0.0350 ± 0.003% vs. unloaded crest Po 0.025 N,n 5/20-30 mean ± SEM NS # p < 0.05 unloaded vs. loaded TT). We discovered that PMU had reduced the association between Caveolin-3, Junctophilin-2, and Cav1.2. Discussion: PMU suppresses' ß2AR-cAMP and LTCC activity. When activated, the signaling of ß2AR-cAMP and LTCC become more far-reaching after PMU. We suggest that a situation of 'suppression/decompartmentation' is elicited by the loss of refined cardiomyocyte structure following PMU. As PMU is a component of modern device therapy for heart failure this study has clinical ramifications and raises important questions for regenerative medicine.

T-tubule remodelling disturbs localized ß2-adrenergic signalling in rat ventricular myocytes during the progression of heart failure.

AIMS: Cardiomyocyte ß2-adrenergic receptor (ß2AR) cyclic adenosine monophosphate (cAMP) signalling is regulated by the receptors' subcellular location within transverse tubules (T-tubules), via interaction with structural and regulatory proteins, which form a signalosome. In chronic heart failure (HF), ß2ARs redistribute from T-tubules to the cell surface, which disrupts functional signalosomes and leads to diffuse cAMP signalling. However, the functional consequences of structural changes upon ß2AR-cAMP signalling during progression from hypertrophy to advanced HF are unknown. METHODS AND RESULTS: Rat left ventricular myocytes were isolated at 4-, 8-, and 16-week post-myocardial infarction (MI), ß2ARs were stimulated either via whole-cell perfusion or locally through the nanopipette of the scanning ion conductance microscope. cAMP release was measured via a Förster Resonance Energy Transfer-based sensor Epac2-camps. Confocal imaging of di-8-ANNEPS-stained cells and immunoblotting were used to determine structural alterations. At 4-week post-MI, T-tubule regularity, density and junctophilin-2 (JPH2) expression were significantly decreased. The amplitude of local ß2AR-mediated cAMP in T-tubules was reduced and cAMP diffused throughout the cytosol instead of being locally confined. This was accompanied by partial caveolin-3 (Cav-3) dissociation from the membrane. At 8-week post-MI, the ß2AR-mediated cAMP response was observed at the T-tubules and the sarcolemma (crest). Finally, at 16-week post-MI, the whole cell ß2AR-mediated cAMP signal was depressed due to adenylate cyclase dysfunction, while overall Cav-3 levels were significantly increased and a substantial portion of Cav-3 dissociated into the cytosol. Overexpression of JPH2 in failing cells in vitro or AAV9.SERCA2a gene therapy in vivo did not improve ß2AR-mediated signal compartmentation or reduce cAMP diffusion. CONCLUSION: Although changes in T-tubule structure and ß2AR-mediated cAMP signalling are significant even at 4-week post-MI, progression to the HF phenotype is not linear. At 8-week post-MI the loss of ß2AR-mediated cAMP is temporarily reversed. Complete disorganization of ß2AR-mediated cAMP signalling due to changes in functional receptor localization and cellular structure occurs at 16-week post-MI.

Altered physiological functions and ion currents in atrial fibroblasts from patients with chronic atrial fibrillation.

The contribution of human atrial fibroblasts to cardiac physiology and pathophysiology is poorly understood. Fibroblasts may contribute to arrhythmogenesis through fibrosis, or by directly altering electrical activity in cardiomyocytes. The objective of our study was to uncover phenotypic differences between cells from patients in sinus rhythm (SR) and chronic atrial fibrillation (AF), with special emphasis on electrophysiological properties. We isolated fibroblasts from human right atrial tissue for patch-clamp experiments, proliferation, migration, and differentiation assays, and gene expression profiling. In culture, proliferation and migration of AF fibroblasts were strongly impaired but differentiation into myofibroblasts was increased. This was associated with a higher number of AF fibroblasts expressing functional Nav1.5 channels. Strikingly Na(+) currents were considerably larger in AF cells. Blocking Na(+) channels in culture with tetrodotoxin did not affect proliferation, migration, or differentiation in neither SR nor AF cells. While freshly isolated fibroblasts showed mostly weak rectifier currents, fibroblasts in culture developed outward rectifier K(+) currents of similar amplitude between the SR and AF groups. Adding the K(+) channel blockers tetraethylammonium and 4-aminopyridin in culture reduced current amplitude and inhibited proliferation in the SR group only. Analysis of gene expression revealed significant differences between SR and AF in genes encoding for ion channels, collagen, growth factors, connexins, and cadherins. In conclusion, this study shows that under AF conditions atrial fibroblasts undergo phenotypic changes that are revealed in culture. Future experiments should be performed in situ to understand the nature of those changes and whether they affect cardiac electrical activity.

Surface Chemistry and Microtopography of Parylene C Films Control the Morphology and Microtubule Density of Cardiac Myocytes.

Cell micropatterning has certainly proved to improve the morphological and physiological properties of cardiomyocytes in vitro; however, there is little knowledge on the single cell-scaffold interactions that influence the cells' development and differentiation in culture. In this study, we employ hydrophobic/hydrophilic micropatterned Parylene C thin films (2-10 µm) as cell microscaffolds that can control the morphology and microtubule density of neonatal rat ventricular myocytes (NRVM) by regulating their adhesion area on Parylene through a thickness-dependent hydrophobicity. Structured NRVM on thin films tend to bridge across the hydrophobic areas, demonstrating a more spread-out shape and sparser microtubule organization, while cells on thicker films adopt a cylindrical (in vivo-like) shape (contact angles at the level of the nucleus are 64.51° and 84.73°, respectively) and a significantly (p < 0.05) denser microtubule structure. Ion scanning microscopy on NRVM revealed that cells on thicker membranes were significantly (p < 0.05) smaller in volume, but more elongated. The cylindrical shape and a significantly denser microtubule structure indicate the ability to influence cardiomyocyte phenotype using patterning and manipulation of hydrophilicity. These combined bioengineering strategies are promising tools in the generation of more representative cardiomyocytes in culture.

The protective effect of ursodeoxycholic acid in an in vitro model of the human fetal heart occurs via targeting cardiac fibroblasts.

Bile acids are elevated in the blood of women with intrahepatic cholestasis of pregnancy (ICP) and this may lead to fetal arrhythmia, fetal hypoxia and potentially fetal death in utero. The bile acid taurocholic acid (TC) causes abnormal calcium dynamics and contraction in neonatal rat cardiomyocytes. Ursodeoxycholic acid (UDCA), a drug clinically used to treat ICP, prevents adverse effects of TC. During development, the fetus is in a state of relative hypoxia. Although this is essential for the development of the heart and vasculature, resident fibroblasts can transiently differentiate into myofibroblasts and form gap junctions with cardiomyocytes in vitro, resulting in cardiomyocyte depolarization. We expanded on previously published work using an in vitro hypoxia model to investigate the differentiation of human fetal fibroblasts into myofibroblasts. Recent evidence shows that potassium channels are involved in maintaining the membrane potential of ventricular fibroblasts and that ATP-dependent potassium (KATP) channel subunits are expressed in cultured fibroblasts. KATP channels are a valuable target as they are thought to have a cardioprotective role during ischaemic and hypoxic conditions. We investigated whether UDCA could modulate fibroblast membrane potential. We established the isolation and culture of human fetal cardiomyocytes and fibroblasts to investigate the effect of hypoxia, TC and UDCA on human fetal cardiac cells. UDCA hyperpolarized myofibroblasts and prevented TC-induced depolarisation, possibly through the activation of KATP channels that are expressed in cultured fibroblasts. Also, similar to the rat model, UDCA can counteract TC-induced calcium abnormalities in human fetal cultures of cardiomyocytes and myofibroblasts. Under normoxic conditions, we found a higher number of myofibroblasts in cultures derived from human fetal hearts compared to cells isolated from neonatal rat hearts, indicating a possible increased number of myofibroblasts in human fetal hearts. Hypoxia further increased the number of human fetal and rat neonatal myofibroblasts. However, chronically administered UDCA reduced the number of myofibroblasts and prevented hypoxia-induced depolarisation. In conclusion, our results show that the protective effect of UDCA involves both the reduction of fibroblast differentiation into myofibroblasts, and hyperpolarisation of myofibroblasts, most likely through the stimulation of potassium channels, i.e. KATP channels. This could be important in validating UDCA as an antifibrotic and antiarrhythmic drug for treatment of failing hearts and fetal arrhythmia.