Letter to the editor: fasting decreases expression of microRNAs linked to endothelial pathophysiology in mononuclear cells of healthy subjects

This study explores how 14-15 h fasting or acute exercise affects immune cell epigenetics, specifically focusing on miRNAs in mononuclear cells. Findings suggest fasting significantly impacts microRNAs associated with endothelial metabolism compared to exercise, but does not directly connect these changes to cell apoptosis or autophagy. This enhances comprehension of cellular self-consumption under health-promoting interventions.

R-miniCHOP versus R-CHOP in elderly patients with diffuse large B-cell lymphoma: A propensity matched population-based study

For elderly frail patients with diffuse large B-cell lymphoma (DLBCL), an attenuated chemo-immunotherapy strategy of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R-miniCHOP) was introduced as a treatment option as from 2014 onward in the Netherlands. Although R-miniCHOP is more tolerable, reduction of chemotherapy could negatively affect survival compared to R-CHOP. The aim of this analysis was to assess survival of patients treated with R-miniCHOP compared to R-CHOP. DLBCL patients ≥65 years, newly diagnosed in 2014-2020, who received ≥1 cycle of R-miniCHOP or R-CHOP were identified in the Netherlands Cancer Registry, with survival follow-up through 2022. Patients were propensity-score-matched for baseline characteristics. Main endpoints were progression-free survival (PFS), overall survival (OS), and relative survival (RS). The use of R-miniCHOP in DLBCL increased from 2% in 2014 to 15% in 2020. In total, 384 patients treated with R-miniCHOP and 384 patients treated with R-CHOP were included for comparison (median age; 81 years, stage 3-4; 68%). The median number of R-(mini)CHOP cycles was 6 (range, 1-8). The 2-year PFS, OS and RS were inferior for patients treated with R-miniCHOP compared to R-CHOP (PFS 51% vs. 68%, p < .01; OS 60% vs. 75%, p < .01; RS 69% vs. 86%, p < .01). In multivariable analysis, patients treated with R-miniCHOP had higher risk of all-cause mortality compared to patients treated with R-CHOP (HR 1.73; 95%CI, 1.39-2.17). R-miniCHOP is effective for most elderly patients. Although survival is inferior compared to R-CHOP, the use of R-miniCHOP as initial treatment is increasing. Therefore, fitness needs to be carefully weighed in treatment selection.

A MYC-rearrangement is a negative prognostic factor in stage II, but not in stage I diffuse large B-cell lymphoma

MYC oncogene rearrangements (MYC-R) negatively affect survival in patients with Ann Arbor stage III-IV diffuse large B-cell lymphoma (DLBCL), but their impact in limited stage (LS) I-II is unclear. Therefore, we assessed the impact of MYC-R on progression-free survival (PFS) and overall survival (OS) in LS DLBCL patients at the population level. We identified 1,434 LS DLBCL patients with known MYC-R status diagnosed between 2014 and 2020, who received R-CHOP(-like) regimens using the Netherlands Cancer Registry, with survival follow-up until February 2022. Stage I patients with (n = 83, 11%) and without (n = 650, 89%) a MYC-R had similar 2-years PFS (89% and 93%, p = 0.63) and OS (both 95%, p = 0.22). Conversely, stage II DLBCL patients with a MYC-R (n = 90, 13%) had inferior survival outcomes compared to stage II patients without a MYC-R (n = 611, 87%) (PFS 70% vs. 89%, p = 0.001; OS 79% vs. 94%, p < 0.0001). Both single MYC-R (single hit, n = 36) and concurrent BCL2 and/or BCL6 rearrangements (double/triple hit, n = 39) were associated with increased mortality and relapse risk. In conclusion, in stage II DLBCL a MYC-R is negatively associated with survival. In stage I DLBCL, however, survival outcomes are excellent irrespective of MYC-R status. This challenges the diagnostic assessment of MYC-R in stage I DLBCL patients.

Lymphocytes are less sensitive to autophagy than monocytes during fasting and exercise conditions

The concomitant investigation of apoptosis (a regulated cell death) and autophagy (a conserved cell survival mechanism) in immune cells is rare. More detailed knowledge of these two types of self-consumption in circulating lymphocytes and monocytes would be important, since conditions such as fasting and acute exercise could promote health by a coordinated/linked modulation of autophagy and apoptosis in these mononuclear cells. In this study we performed flow cytometry to quantify numbers of apoptotic and autophagic mononuclear cells, lymphocytes and monocytes in fasting, standardized fed, and exercise conditions, using Annexin V, LC3B, and p62, respectively. We show that within total mononuclear cells lymphocytes are less apoptotic and autophagic than monocytes during fasting (p < 0.001, p < 0.05, respectively) and after acute exercise (p < 0.01, p < 0.05, respectively). Fasting increased circulating autophagic monocyte concentrations, but not lymphocytes compared to the fed control condition. Acute exercise elevated circulating autophagic lymphocyte concentrations, but not monocytes. Interestingly, Western blotting analysis of the fasting samples showed that higher LC3BII/I ratios were correlated with lower numbers of autophagic mononuclear cells (r = − 0.74, p = 0.02, n = 8), which could be attributed to the monocyte subgroup, but not lymphocytes. These results extend the current knowledge of the two types of self-consumption in circulating immune cells and underline their possible importance in pro-inflammatory monocytes during fasting and exercise as health promoting interventions.

POS0245 PROTEIN PROFILING IN PRE-SYMPTOMATIC ANCA-ASSOCIATED VASCULITIS INDIVIDUALS

Background

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare chronic relapsing condition, with unknown etiology.

Objectives

This study was undertaken to gain insight to the molecular processes and to find potential biomarkers in blood samples collected prior to the onset of symptoms of AAV.

Methods

The National Patient Register and Cause of Death register were searched for AAV-ICD codes and linked to the registers of five biobanks. Eighty-five AAV cases were identified (34 males, 51 females) with samples >1month <10years from AAV symptom onset. For each case two controls matched for sex, age, and sampling date were included. Samples were analyzed using ELISAs for PR3- or MPO-ANCA specificities. Ninety-two protein markers were analyzed using Olink Inflammation panel, (OLINK, Uppsala, Sweden) with 73 eligible after quality control.

Results

Eight protein markers were significantly altered between pre-AAV and controls, with higher levels of CCL23, CXCL5 (p< 0.01-0.05) and lower levels of Flt3L, STAMBP, ADA, TNFB, CX3CL1 and IL-15RA (p< 0.01-0.05) in the pre-AAV individuals. Nine protein markers were found significantly associated with time to symptom onset; CXCL9, CD244, VEGFA, CXCL1, TNFSF9, OPG, CSF-1, IFN-gamma and CD40 (p< 0.01-0.05). In pre-AAV individuals, six proteins were associated with MPO-ANCA-positivity compared with the MPO-ANCA-negative pre-AAV individuals which showed no overlap with the seven proteins related to PR3-ANCA-positivity.

Conclusion

To our knowledge our study is the first to analyze for and identify protein markers before symptom onset in AAV. This allowed for further studies of underlying cellular and molecular mechanisms in AAV pathogenesis as well as the diversification into PR3-ANCA and MPO-ANCA subphenotypes.

Disclosure of Interests

Mikael Brink: None declared, Ewa Berglin: None declared, Aladdin J Mohammad Speakers bureau: Roche, Gsk, AMGEN; Vifor, Lilly, Consultant of: Roche & AMGEN, Andrey Alexeyenko: None declared, Kristina Lejon: None declared, Solbritt Rantapää Dahlqvist: None declared

OP0307 PULMONARY FIBROSIS IN EARLY RHEUMATOID ARTHRITIS IN RELATION TO GENETIC LOCI AND INDIVIDUAL ACPA SPECIFICITIES

Background

Pulmonary manifestations in rheumatoid arthritis (RA) are common comorbidities but the underlying mechanisms are largely unknown. We found in a previous study 3 SNPs associated with pulmonary fibrosis (PF); rs35705950 (MUC5B), rs111521887 (TOLLIP), and rs2609255 (FAM13A) besides age, rheumatoid factor positivity and methotrexate treatment.

Objectives

To evaluate for the added value of a multiplex of anti-citrullinated peptide antibodies (ACPA) for the development of pulmonary fibrosis (PF) in an inception cohort of RA patients.

Methods

A total of 1184 patients with early RA were consecutively included and followed prospectively from the date of diagnosis (index date) until death or until 31 December 2016. The diagnosis of PF was based on high resolution tomography. The presence of 21 ACPA fine specificities were analysed in plasma sampled at index date, using a custom-made microarray chip (Thermo Fisher Scientific, Uppsala, Sweden). Data on both ACPA and genetic data was available for 841 RA patients, of whom 50 developed PF. Associations were analysed using logistic regression analysis and presented as the odds ratio (OR) with the 95% confidence interval (CI). Models were adjusted for sex, age, DAS28 and presence of RF at RA diagnosis, smoking ever, and HLA-SE and in a second step for the three SNPs (.rs35705950, rs111521887 and rs2609255), respectively.

Results

In unadjusted analyses eight ACPA reactivities were found associated with PF development (p< 0.05-0.001). The number of ACPA reactivities was related to PF development, both in crude and adjusted models (p<0.05 for both). In models concomitantly adjusted for the three SNPs (rs35705950, rs111521887 and rs2609255) respectively, in addition to mentioned adjustments the number of ACPA reactivities (p<0.05 for all three nmodels), Vim60-75 (p<0.05, in all three models), Fibβ62–78 (72) (p<0.001-p<0.05) and F4-CIT-R (p<0.01-p<0.05) were all found significantly associated to PF development irrespective of the SNPs.

Conclusion

The development of PF in an inception cohort of RA patients was associated both with risk genes and, independently of the risk genes, the presence of certain ACPA, and the number of ACPA reactivities.

References

[1]Jönsson E, et al. Pulmonary fibrosis in relation to genetic loci in an inception cohort of patients with early rheumatoid arthritis from northern Sweden. Rheumatology (Oxford). 2021 May 16:keab441. doi: 10.1093/rheumatology/keab441.

Acknowledgements

I have no acknowledgements to declare. The staff and patients at the departments of rheumatology in northern Sweden.

Disclosure of Interests

None declared

Ultrahigh vacuum packaging and surface cleaning for quantum devices

We describe design, implementation, and performance of an ultra-high vacuum (UHV) package for superconducting qubit chips or other surface sensitive quantum devices. The UHV loading procedure allows for annealing, ultra-violet light irradiation, ion milling, and surface passivation of quantum devices before sealing them into a measurement package. The package retains vacuum during the transfer to cryogenic temperatures by active pumping with a titanium getter layer. We characterize the treatment capabilities of the system and present measurements of flux tunable qubits with an average T₁ = 84 µs and T₂ ^echo=134μs after vacuum-loading these samples into a bottom loading dilution refrigerator in the UHV-package.

Secretory antibodies to citrullinated peptides in plasma and saliva from rheumatoid arthritis patients and their unaffected first-degree relatives

The aim of this study was to evaluate secretory antibodies to citrullinated proteins (ACPA) in plasma and immunoglobulin (Ig)A ACPA in saliva from patients with rheumatoid arthritis (RA) and their unaffected first‐degree relatives (FDRs). Patients with RA (n = 194) and first‐degree relatives unaffected by RA (n = 191) were recruited for analysis of secretory antibodies to second‐generation cyclic citrullinated peptides (anti‐CCP) in plasma. From a subpopulation (25 RA patients, 21 first‐degree relatives and 11 controls), saliva samples were obtained for IgA anti‐CCP analysis. The presence of secretory ACPA was compared between subject categories, and related to genetic and environmental risk factors. Secretory ACPA occurred in 37 (19%) plasma samples from patients with RA, but only in two (1%) of FDRs. IgA ACPA in saliva was found in three of 25 (12%) patients with RA, but not in any of the 21 FDRs (< 5%). No significant associations were seen between the presence of secretory ACPA and SE or smoking, either among RA patients or among FDRs. Despite occurring in 19% of RA plasma, secretory ACPA was rare in both saliva and plasma among FDRs, even among those positive for conventional ACPA of non‐mucosal origin. Longitudinal studies are warranted to determine whether circulating secretory ACPA occurs before or in parallel with the development of clinical arthritis.

Mechanisms of the Multitasking Endothelial Protein NRG-1 as a Compensatory Factor During Chronic Heart Failure

Heart failure is a complex syndrome whose phenotypic presentation and disease progression depends on a complex network of adaptive and maladaptive responses. One of these responses is the endothelial release of NRG (neuregulin)-1—a paracrine growth factor activating ErbB2 (erythroblastic leukemia viral oncogene homolog B2), ErbB3, and ErbB4 receptor tyrosine kinases on various targets cells. NRG-1 features a multitasking profile tuning regenerative, inflammatory, fibrotic, and metabolic processes. Here, we review the activities of NRG-1 on different cell types and organs and their implication for heart failure progression and its comorbidities. Although, in general, effects of NRG-1 in heart failure are compensatory and beneficial, translation into therapies remains unaccomplished both because of the complexity of the underlying pathways and because of the challenges in the development of therapeutics (proteins, peptides, small molecules, and RNA-based therapies) for tyrosine kinase receptors. Here, we give an overview of the complexity to be faced and how it may be tackled.

Metagenomic assessment of body surface bacterial communities of the sea urchin, Tripneustes gratilla

Sea urchins, including Tripneustes gratilla, are susceptible to a disease known as bald sea urchin disease, which has the potential to lead to economic losses in this emerging aquaculture industry in South Africa. This disease is characterized by lesions that form on sea urchin exoskeletal surfaces. This study aimed to characterize the body surface bacterial communities associated with T. gratilla, using a 16S rDNA gene metagenomics approach, to provide insight into the bacterial agents associated with this aquaculture species, as well as with this balding disease. Bacterial samples were collected from non-lesioned healthy animals obtained from natural locations along the eastern coast of South Africa, as well as from different cultured cohorts: non-lesioned healthy-, lesioned diseased- and non-lesioned stressed animals. A total of 1,067,515 individual bacterial operational taxonomic units (OTUs) were identified, belonging to 133 family-, 123 genus- and 113 species level OTU groups. Alpha diversity analyses, based on Chao1, Shannon and Simpson indices, showed that there were no statistically significant differences (ANOVA; P > 0.05) between the respective cohorts, as all cohorts displayed a high degree of bacterial diversity. Similarly, beta diversity analyses (Non-metric multidimensional scaling) showed a large degree of overlapping OTUs across the four cohorts. Within each cohort, various OTUs commonly associated with marine environments were found, predominantly belonging to the families Vibrionaceae, Saprospiraceae, Flavobacteriaceae and Sphingomonadaceae. Differential abundance analysis (DESeq2) revealed that OTUs that are differentially abundant across cohorts were likely not responsible for this balding disease, suggesting that complex bacterial agents, rather than a specific pathogenic agent, are likely causing this disease. Furthermore, the putative metabolic functions assigned to the bacterial communities showed that heterotrophic bacteria appear to be responsible for tissue lysis of degrading animal matter. The results from this study, obtained through univariate and multivariate-based approaches, contributes to future management strategies of this emerging aquaculture species by providing insight into the bacterial communities associated with both natural and cultured environments.

Moderate Modulation of Cardiac PGC-1α Expression Partially Affects Age-Associated Transcriptional Remodeling of the Heart

Aging is associated with a decline in cardiac function due to a decreased myocardial reserve. This adverse cardiac remodeling comprises of a variety of changes, including a reduction in mitochondrial function and a decline in the expression of the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a central regulator of mitochondrial biogenesis and metabolic adaptation in the myocardium. To study the etiological involvement of PGC-1α in cardiac aging, we used mouse models mimicking the modest down- and upregulation of this coactivator in the old and the exercised heart, respectively. Young mice with reduced cardiac expression of PGC-1α recapitulated part of the age-related impairment in mitochondrial gene expression, but otherwise did not aggravate the aging process. Inversely however, moderate overexpression of PGC-1α counteracts numerous key age-related remodeling changes, e.g., by improving blood pressure, age-associated apoptosis, and collagen accumulation, as well as in the expression of many, but not all cardiac genes involved in mitochondrial biogenesis, dynamics, metabolism, calcium handling and contractility. Thus, while the reduction of PGC-1α in the heart is insufficient to cause an aging phenotype, moderate overexpression reduces pathological remodeling of older hearts and could thereby contribute to the beneficial effects of exercise on cardiac function in aging.

Abstract 270: mTORC1 is Essential for Cardiomyocyte Homeostasis and Female Sex Related Cardioprotection

Mechanistic target of rapamycin (mTOR) kinase operates in two functionally and structurally distinct protein complexes mTORC1 and mTORC2. Raptor is a defining mTORC1 protein critical for cardiac growth in response to stress. Our previous studies showed sexual dimorphism in LV remodeling of normotensive DOCA-salt mice, where females retain normal LV architecture and males developed maladaptive LV hypertrophy. We hypothesized involvement of mTORC1 in regulation of this sexual dimorphism and induced cardiomyocyte (CM) specific raptor deletion (ra-cKO) in our model of normotensive mineralocorticoid challenge. Deletion of raptor in CM lead to decreased mTORC1 downstream target activation of 4E-BP1 and strong compensatory hyperactivation of mTORC2 target AKT in both sexes.

In contrast to healthy wild type females, female DOCA-salt ra-cKO mice developed severe dilative phenotype with tremendous interstitial fibrosis (15fold increase vs. WT) of similar extent as males. Functionally, ra-cKO females had stronger decrease in EF (51 vs. 26%) than ra-cKO males (50 vs. 32%). Greater loss of sarcomeric ultrastructure and mitochondrial morphology in transmission electron microscopy was observed in male ra-cKOs. Analysis of label-free proteomics and transcriptomics approaches revealed genotype and sex-specific clustering and identified significantly regulated single proteins or gene sets. Concordant to observed ultrastructural changes, down-regulation of genes for Z-disc, t-tubule and sarcomere organization was prominent in male hearts, whereas females displayed up-regulation of gene sets for inflammation, angiogenesis and mitochondrial function.

Intact mTORC1 is indispensible for CM homeostasis of both sexes as reflected by development of severe phenotype even by a mild stressor in our model. More specific, female sex-specific cardioprotection is completely lost in absence of mTORC1. Despite similar phenotypic changes in both sexes, sex-specific differences in regulation of gene expression points toward sex-specific functional selectivity of mTORC1 in regulation of CM homeostasis. Given the broad indications for mTOR inhibitors and especially used high concentration in oncology, one could anticipate adverse cardiac side effects.

An RYR1 mutation associated with malignant hyperthermia is also associated with bleeding abnormalities

Malignant hyperthermia is a potentially fatal hypermetabolic disorder triggered by halogenated anesthetics and the myorelaxant succinylcholine in genetically predisposed individuals. About 50% of susceptible individuals carry dominant, gain-of-function mutations in RYR1 [which encodes ryanodine receptor type 1 (RyR1)], though they have normal muscle function and no overt clinical symptoms. RyR1 is predominantly found in skeletal muscle but also at lower amounts in immune and smooth muscle cells, suggesting that RYR1 mutations may have a wider range of effects than previously suspected. Mild bleeding abnormalities have been described in patients with malignant hyperthermia carrying gain-of-function RYR1 mutations. We sought to determine the frequency and molecular basis for this symptom. We found that some patients with specific RYR1 mutations had abnormally high bleeding scores, whereas their healthy relatives did not. Knock-in mice with the malignant hyperthermia susceptibility RYR1 mutation Y522S (MHS RYR1Y522S) had longer bleeding times than their wild-type littermates. Primary vascular smooth muscle cells from RYR1Y522S knock-in mice exhibited a higher frequency of subplasmalemmal Ca(2+) sparks, leading to a more negative resting membrane potential. The bleeding defect of RYR1Y522S mice and of one patient was reversed by treatment with the RYR1 antagonist dantrolene, and Ca(2+) sparks in primary vascular smooth muscle cells from the MHS RYR1Y522S mice were blocked by ryanodine or dantrolene. Thus, RYR1 mutations may lead to prolonged bleeding by altering vascular smooth muscle cell function. The reversibility of the bleeding phenotype emphasizes the potential therapeutic value of dantrolene in the treatment of such bleeding disorders.

Neuregulin-1β promotes glucose uptake via PI3K/Akt in neonatal rat cardiomyocytes

Nrg1β is critically involved in cardiac development and also maintains function of the adult heart. Studies conducted in animal models showed that it improves cardiac performance under a range of pathological conditions, which led to its introduction in clinical trials to treat heart failure. Recent work also implicated Nrg1β in the regenerative potential of neonatal and adult hearts. The molecular mechanisms whereby Nrg1β acts in cardiac cells are still poorly understood. In the present study, we analyzed the effects of Nrg1β on glucose uptake in neonatal rat ventricular myocytes and investigated to what extent mTOR/Akt signaling pathways are implicated. We show that Nrg1β enhances glucose uptake in cardiomyocytes as efficiently as IGF-I and insulin. Nrg1β causes phosphorylation of ErbB2 and ErbB4 and rapidly induces the phosphorylation of FAK (Tyr(861)), Akt (Thr(308) and Ser(473)), and its effector AS160 (Thr(642)). Knockdown of ErbB2 or ErbB4 reduces Akt phosphorylation and blocks the glucose uptake. The Akt inhibitor VIII and the PI3K inhibitors LY-294002 and Byl-719 abolish Nrg1β-induced phosphorylation and glucose uptake. Finally, specific mTORC2 inactivation after knockdown of rictor blocks the Nrg1β-induced increases in Akt-p-Ser(473) but does not modify AS160-p-Thr(642) or the glucose uptake responses to Nrg1β. In conclusion, our study demonstrates that Nrg1β enhances glucose uptake in cardiomyocytes via ErbB2/ErbB4 heterodimers, PI3Kα, and Akt. Furthermore, although Nrg1β activates mTORC2, the resulting Akt-Ser(473) phosphorylation is not essential for glucose uptake induction. These new insights into pathways whereby Nrg1β regulates glucose uptake in cardiomyocytes may contribute to the understanding of its regenerative capacity and protective function in heart failure.

mTOR, cardiomyocytes and inflammation in cardiac hypertrophy

Mammalian target of rapamycin (mTOR) is an evolutionary conserved kinase that senses the nutrient and energy status of cells, the availability of growth factors, stress stimuli and other cellular and environmental cues. It responds by regulating a range of cellular processes related to metabolism and growth in accordance with the available resources and intracellular needs. mTOR has distinct functions depending on its assembly in the structurally distinct multiprotein complexes mTORC1 or mTORC2. Active mTORC1 enhances processes including glycolysis, protein, lipid and nucleotide biosynthesis, and it inhibits autophagy. Reported functions for mTORC2 after growth factor stimulation are very diverse, are tissue and cell-type specific, and include insulin-stimulated glucose transport and enhanced glycogen synthesis. In accordance with its cellular functions, mTOR has been demonstrated to regulate cardiac growth in response to pressure overload and is also known to regulate cells of the immune system. The present manuscript presents recently obtained insights into mechanisms whereby mTOR may change anabolic, catabolic and stress response pathways in cardiomocytes and discusses how mTOR may affect inflammatory cells in the heart during hemodynamic stress. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

Abstract 442: Cardiomyocyte Specific mTORC1 Deletion Precipitates Interstitial Fibrosis, Heart Failure And Loss Of Female Cardio Protection

Mechanistic target of rapamycin (mTOR) kinase operates in two functionally and structurally distinct multiprotein complexes mTORC1 and mTORC2. mTORC1 including its defining raptor protein is a critical mediator of myocardial growth. We induced cardiomyocyte specific raptor-KO (cKO) deletion to investigate a sex specific role of mTORC1 during cardiac adaptation in normotensive DOCA-salt mice. Untypical for this mild cardiac stress model, raptor-cKO females had sharper decrease in EF (51 vs. 26%) than males (50 vs. 32%) already at 3 weeks after start of DOCA-salt challenge. Male raptor-cKO mice mounted eccentric hypertrophic response upon DOCA-salt indicated by heart weight/tibia length ratios (6.7 to 8.0) as compared to their WT litters (6.6 to 7.6). In contrast female raptor-cKO (5.8 to 6.4) minimally differed from their litters (5.8 to 6.6). Severe dilative phenotype was detected in both sexes regardless of DOCA-salt challenge. In addition, we found tremendous diffuse left ventricular fibrosis which was also more prominent in raptor-cKO females. Collagen depositions in the LV visualized by Sirius red staining increased 10fold in males (1.0 to 10.6%) and 15fold in females (0.9 to 15.7%), respectively. Expression of raptor protein in the heart was diminished by 80% in raptor cKO mice of both sexes what lead to similar extent of decreased activity of direct mTORC1 downstream targets phospho-S6 ribosomal protein and phospho-4E-BP1Ser65 (68% reduction in males vs. 61% in females. Over-compensatory mTORC2 activation in cKO animals via phospho-AKTSer473 (12fold increase) and induction of anti-apoptotic signaling was similar in both sexes. However, raptor-cKO females failed to up-regulate expression of mitochondrial genes such as Mtnd1 (ND1), mt-Co1 (COX1) and Atp5i (ATP5k), stressing sex differences in mTORC1 dependent mitochondrial adaptation. In addition, transmission electron microscopy (TEM) points towards structural alterations of mitochondrial morphology.

Intact mTORC1 function is important for myocardial adaptation in both sexes. More severe phenotype in females further implicates mTORC1 to be essential for intrinsic female cardio protection.

New methods for using computer-aided detection information for the detection of lung nodules on chest radiographs

OBJECTIVE

To investigate two new methods of using computer-aided detection (CAD) system information for the detection of lung nodules on chest radiographs. We evaluated an interactive CAD application and an independent combination of radiologists and CAD scores.

METHODS

300 posteroanterior and lateral digital chest radiographs were selected, including 111 with a solitary pulmonary nodule (average diameter, 16 mm). Both nodule and control cases were verified by CT. Six radiologists and six residents reviewed the chest radiographs without CAD and with CAD (ClearRead +Detect™ 5.2; Riverain Technologies, Miamisburg, OH) in two reading sessions. The CAD system was used in an interactive manner; CAD marks, accompanied by a score of suspicion, remained hidden unless the location was queried by the radiologist. Jackknife alternative free response receiver operating characteristics multireader multicase analysis was used to measure detection performance. Area under the curve (AUC) and partial AUC (pAUC) between a specificity of 80% and 100% served as the measure for detection performance. We also evaluated the results of a weighted combination of CAD scores and reader scores, at the location of reader findings.

RESULTS

AUC for the observers without CAD was 0.824. No significant improvement was seen with interactive use of CAD (AUC = 0.834; p = 0.15). Independent combination significantly improved detection performance (AUC = 0.834; p = 0.006). pAUCs without and with interactive CAD were similar (0.128), but improved with independent combination (0.137).

CONCLUSION

Interactive CAD did not improve reader performance for the detection of lung nodules on chest radiographs. Independent combination of reader and CAD scores improved the detection performance of lung nodules.

ADVANCES IN KNOWLEDGE

(1) Interactive use of currently available CAD software did not improve the radiologists' detection performance of lung nodules on chest radiographs. (2) Independently combining the interpretations of the radiologist and the CAD system improved detection of lung nodules on chest radiographs.

A proton leak current through the cardiac sodium channel is linked to mixed arrhythmia and the dilated cardiomyopathy phenotype

Cardiac Na⁺ channels encoded by the SCN5A gene are essential for initiating heart beats and maintaining a regular heart rhythm. Mutations in these channels have recently been associated with atrial fibrillation, ventricular arrhythmias, conduction disorders, and dilated cardiomyopathy (DCM).

We investigated a young male patient with a mixed phenotype composed of documented conduction disorder, atrial flutter, and ventricular tachycardia associated with DCM. Further family screening revealed DCM in the patient's mother and sister and in three of the mother's sisters. Because of the complex clinical phenotypes, we screened SCN5A and identified a novel mutation, R219H, which is located on a highly conserved region on the fourth helix of the voltage sensor domain of Na_v1.5. Three family members with DCM carried the R219H mutation.

The wild-type (WT) and mutant Na⁺ channels were expressed in a heterologous expression system, and intracellular pH (pHi) was measured using a pH-sensitive electrode. The biophysical characterization of the mutant channel revealed an unexpected selective proton leak with no effect on its biophysical properties. The H⁺ leak through the mutated Na_v1.5 channel was not related to the Na⁺ permeation pathway but occurred through an alternative pore, most probably a proton wire on the voltage sensor domain.

We propose that acidification of cardiac myocytes and/or downstream events may cause the DCM phenotype and other electrical problems in affected family members. The identification of this clinically significant H⁺ leak may lead to the development of more targeted treatments.

Abstract P117: Does Mammalian Target of Rapamycin Complex-2 Regulate Protein Degradation Pathways in the Heart?

Background: Mammalian target of rapamycin (mTOR) occurs in the cell in two distinct multiprotein complexes called mTOR complex 1 (mTORC1) and mTORC2, which contain raptor and rictor, respectively. We have recently demonstrated that mTORC1 activity is required for the hypertrophic response to aortic constriction and for the normal cardiac homeostasis. Moreover, we showed that raptor deletion causes Akt hyperphosphorylation and lower gene expression of Atrogin-1 and MuRF1, two muscle specific E3 enzymes part of the proteasomal degradation pathway. These results suggested that, as a counter-regulatory response to mTORC1 inactivation, mTORC2 reduces protein degradation via phosphorylation of Akt at Ser473. It has previously been shown that the phosphorylation state of Akt regulates Atrogin-1 and MuRF1 gene expression at the transcriptional level via FoxO. In the present study, we have tested whether mTORC2 inactivation induces the ubiquitin-proteasomal degradation pathway.

Methods and results: In 10 week-old male mice, transgenic for MerCreMer driven by the α-MHC promoter and homozygous for floxed rictor, deletion of the rictor gene was induced by tamoxifen. Protein and RNA extracts were analyzed at three weeks after tamoxifen by Western blotting and qPCR, respectively. The rictor gene was efficiently ablated from the heart as its protein levels were reduced. Phosphorylation of Akt and PKC-α, direct targets of mTORC2, was abolished, identifying these signaling molecules as downstream targets of mTORC2 in the heart. However, the reduced Akt phosphorylation was not associated with any changes in the mRNA levels of Atrogin-1, MuRF1, and MuRF3.

Conclusion: Our study suggests that mTORC2-induced phosphorylation of Akt is not required for the maintenance of low expression levels of these genes. Further studies are ongoing to identify the factors that modulate Atrogin-1 and MuRF1 gene transcription in the heart.

β1-Integrin is up-regulated via Rac1-dependent reactive oxygen species as part of the hypertrophic cardiomyocyte response

β(1)-Integrin mediates cardiomyocyte growth and survival and its proper regulation is essential for the structural and functional integrity of the heart. β(1)-Integrin expression is enhanced in hypertrophy, but the mechanism and significance of its up-regulation are unknown. Because reactive oxygen species (ROS) are important mediators of myocardial remodeling we examined their role in regulated β(1)-integrin expression. Hypertrophy was induced in neonatal cardiomyocytes by endothelin-1 (ET-1), which activated the regulatory NADPH oxidase subunit Rac1, evoked ROS, and enhanced fetal gene expression and cardiomyocyte size. ET-1 also enhanced cell adhesion and FAK phosphorylation and inhibited oxidative stress-induced cardiomyocyte apoptosis. Further, ET-1 increased β(1)-integrin mRNA and protein expression via Rac1-ROS-dependent MEK/ERK and EGF receptor-PI3K/Akt activation as shown by adenoviral dominant-negative Rac1 or overexpression of copper/zinc-superoxide dismutase. The relevance of regulated β(1)-integrin expression was examined in cardiomyocytes, in which targeting siRNA impeded the ET-1-induced β(1)-integrin up-regulation. In these cells, ET-1-induced cell adhesion, FAK phosphorylation, and hypertrophic response were significantly blunted, whereas its antiapoptotic effect was predominantly unchanged, suggesting at least partial dissociation of prohypertrophic and prosurvival signaling elicited by ET-1. In conclusion, β(1)-integrin up-regulation in response to ET-1 is mediated via Rac1-ROS-dependent activation of prohypertrophic pathways and is mandatory for ET-1-induced FAK activation, cell adhesion, and hypertrophic response.

Cardiac raptor ablation impairs adaptive hypertrophy, alters metabolic gene expression, and causes heart failure in mice

BACKGROUND

Cardiac hypertrophy involves growth responses to a variety of stimuli triggered by increased workload. It is an independent risk factor for heart failure and sudden death. Mammalian target of rapamycin (mTOR) plays a key role in cellular growth responses by integrating growth factor and energy status signals. It is found in 2 structurally and functionally distinct multiprotein complexes called mTOR complex (mTORC) 1 and mTORC2. The role of each of these branches of mTOR signaling in the adult heart is currently unknown.

METHODS AND RESULTS

We generated mice with deficient myocardial mTORC1 activity by targeted ablation of raptor, which encodes an essential component of mTORC1, during adulthood. At 3 weeks after the deletion, atrial and brain natriuretic peptides and β-myosin heavy chain were strongly induced, multiple genes involved in the regulation of energy metabolism were altered, but cardiac function was normal. Function deteriorated rapidly afterward, resulting in dilated cardiomyopathy and high mortality within 6 weeks. Aortic banding-induced pathological overload resulted in severe dilated cardiomyopathy already at 1 week without a prior phase of adaptive hypertrophy. The mechanism involved a lack of adaptive cardiomyocyte growth via blunted protein synthesis capacity, as supported by reduced phosphorylation of ribosomal S6 kinase 1 and 4E-binding protein 1. In addition, reduced mitochondrial content, a shift in metabolic substrate use, and increased apoptosis and autophagy were observed.

CONCLUSIONS

Our results demonstrate an essential function for mTORC1 in the heart under physiological and pathological conditions and are relevant for the understanding of disease states in which the insulin/insulin-like growth factor signaling axis is affected such as diabetes mellitus and heart failure or after cancer therapy.

Proteome analysis in cardiovascular pathophysiology using Dahl rat model

Dahl salt-sensitive (DS) and salt-resistant (DR) inbred rat strains represent a well established animal model for cardiovascular research. Upon prolonged administration of high-salt-containing diet, DS rats develop systemic hypertension, and as a consequence they develop left ventricular hypertrophy, followed by heart failure. The aim of this work was to explore whether this animal model is suitable to identify biomarkers that characterize defined stages of cardiac pathophysiological conditions. The work had to be performed in two stages: in the first part proteomic differences that are attributable to the two separate rat lines (DS and DR) had to be established, and in the second part the process of development of heart failure due to feeding the rats with high-salt-containing diet has to be monitored. This work describes the results of the first stage, with the outcome of protein expression profiles of left ventricular tissues of DS and DR rats kept under low salt diet. Substantial extent of quantitative and qualitative expression differences between both strains of Dahl rats in heart tissue was detected. Using Principal Component Analysis, Linear Discriminant Analysis and other statistical means we have established sets of differentially expressed proteins, candidates for further molecular analysis of the heart failure mechanisms.

The effects of railway noise on sleep medication intake: results from the ALPNAP-study

In the 1980s/90s, a number of socio-acoustic surveys and laboratory studies on railway noise effects have observed less reported disturbance/interference with sleep at the same exposure level compared with other modes of transportation. This lower grade of disturbance has received the label "railway bonus", was implemented in noise legislation in a number of European countries and was applied in planning and environmental impact assessments. However, majority of the studies investigating physiological outcomes did not find the bespoke difference. In a telephone survey (N=1643) we investigated the relationship between railway noise and sleep medication intake and the impact of railway noise events on motility parameters during night was assessed with contact-free high resolution actimetry devices. Multiple logistic regression analysis with cubic splines was applied to assess the probability of sleep medication use based on railway sound level and nine covariates. The non-linear exposure-response curve showed a statistically significant leveling off around 60 dB (A), Lden. Age, health status and trauma history were the most important covariates. The results were supported also by a similar analysis based on the indicator "night time noise annoyance". No railway bonus could be observed above 55 dB(A), Lden. In the actimetry study, the slope of rise of train noise events proved to be almost as important a predictor for motility reactions as was the maximum sound pressure level - an observation which confirms similar findings from laboratory experiments and field studies on aircraft noise and sleep disturbance. Legislation using a railway bonus will underestimate the noise impact by about 10 dB (A), Lden under the conditions comparable with those in the survey study. The choice of the noise calculation method may influence the threshold for guideline setting.

Acute effects of urocortin 2 on cardiac function and propensity for arrhythmias in an animal model of hypertension-induced left ventricular hypertrophy and heart failure

AIMS

To test acute effects of the corticotropin-releasing factor-related peptide urocortin 2 (Ucn2) on left ventricular (LV) function and the propensity for ventricular arrhythmias in the isolated heart of an animal model of hypertension-induced heart failure.

METHODS AND RESULTS

Hearts from Dahl salt-sensitive rats with severe LV dysfunction were perfused according to Langendorff. Left ventricular developed pressure and the positive and negative derivatives of LV pressure were analysed before and after perfusion with Ucn2 (n = 15) or normal perfusion solution (control, n = 9). Intracellular calcium cycling parameters were assessed by surface fluorometry. Furthermore, monophasic action potential duration (MAPD) and ventricular fibrillation threshold (VFT) were determined, the latter by a train-of-pulses method at increasing voltage to scan the vulnerable period of repolarization. Urocortin 2 significantly affected intracellular calcium cycling and improved LV contractile function and relaxation. Compared with baseline values, Ucn2 significantly decreased MAPD at 30, 50, and 90% repolarization and significantly increased VFT compared with baseline values. No changes were observed in control experiments.

CONCLUSION

Administration of Ucn2 rapidly improves LV function and increases VF threshold in failing, isolated rat hearts with increased propensity for ventricular arrhythmias. These observations suggest a potential use of Ucn2 as a safe and novel agent for the treatment of acute heart failure.