Sparing of the heart facilitates recovery from cardiopulmonary side effects after thoracic irradiation.

INTRODUCTION: When irradiating thoracic tumors, dose to the heart or lung has been associated with survival. We previously showed in a rat model that in addition to known side-effects such as pericarditis, pneumonitis and fibrosis, heart and/or lung irradiation also impaired diastolic function and increased pulmonary artery pressure. Simultaneous irradiation of both organs strongly intensified these effects. However, the long-term consequences of this interactions are not yet known. Therefore, here we investigate the long-term effects of combined heart and lung irradiation. MATERIAL AND METHODS: Different regions of the rat thorax containing the heart and/or 50% of the lungs were irradiated with protons. Respiratory rate (RR) was measured bi-weekly as an overall parameter for cardiopulmonary function. Echocardiography of the heart was performed at 8, 26 and 42 weeks after irradiation. Tissue remodeling and vascular changes were assessed using Masson Trichrome and Verhoeff-stained lung and LV tissue collected at 8 and 42 weeks after irradiation. RESULTS: During the entire experimental period RR was consistently increased after combined heart/lung irradiation. This coincided with persistent effects on lung vasculature and reduced right ventricle contraction. In contrast, recovery of RR, pulmonary remodeling and right ventricle contraction was observed after sparing of the heart. These corresponding temporal patterns suggest that the reduction of right ventricle (RV) function is related to vascular remodeling in the lung. CONCLUSION: Combined irradiation of lung and heart leads to an intensified, persistent reduction of cardiopulmonary function. Recovery of the pulmonary vasculature and right ventricle function requires heart-sparing.

Heart failure-induced microbial dysbiosis contributes to colonic tumour formation in mice.

AIMS: Heart failure (HF) and cancer are the leading causes of death worldwide. Epidemiological studies revealed that HF patients are prone to develop cancer. Preclinical studies provided some insights into this connection, but the exact mechanisms remain elusive. In colorectal cancer (CRC), gut microbial dysbiosis is linked to cancer progression and recent studies have shown that HF patients display microbial dysbiosis. This current study focussed on the effects of HF-induced microbial dysbiosis on colonic tumour formation. METHODS AND RESULTS: C57BL/6J mice were subjected to myocardial infarction (MI), with sham surgery as control. After six weeks faeces were collected, processed for 16 s rRNA sequencing, and pooled for faecal microbiota transplantation. CRC tumour growth was provoked in germ-free mice by treating them with Azoxymethane/Dextran sodium sulphate. The CRC mice were transplanted with faeces from MI or sham mice. MI-induced HF resulted in microbial dysbiosis, characterized by a decreased α-diversity and microbial alterations on the genus level, several of which have been associated with CRC. We then performed faecal microbiota transplantation with faeces from HF mice in CRC mice, which resulted in a higher endoscopic disease score and an increase in the number of tumours in CRC mice. CONCLUSION: We demonstrated that MI-induced HF contributes to colonic tumour formation by altering the gut microbiota composition, providing a mechanistic explanation for the observed association between HF and increased risk for cancer. Targeting the microbiome may present as a tool to mitigate HF-associated co-morbidities, especially cancer.

DWORF Extends Life Span in a PLN-R14del Cardiomyopathy Mouse Model by Reducing Abnormal Sarcoplasmic Reticulum Clusters.

BACKGROUND: The p.Arg14del variant of the PLN (phospholamban) gene causes cardiomyopathy, leading to severe heart failure. Calcium handling defects and perinuclear PLN aggregation have both been suggested as pathological drivers of this disease. Dwarf open reading frame (DWORF) has been shown to counteract PLN regulatory calcium handling function in the sarco/endoplasmic reticulum (S/ER). Here, we investigated the potential disease-modulating action of DWORF in this cardiomyopathy and its effects on calcium handling and PLN aggregation. METHODS: We studied a PLN-R14del mouse model, which develops cardiomyopathy with similar characteristics as human patients, and explored whether cardiac DWORF overexpression could delay cardiac deterioration. To this end, R14Δ/Δ (homozygous PLN-R14del) mice carrying the DWORF transgene (R14Δ/ΔDWORFTg [R14Δ/Δ mice carrying the DWORF transgene]) were used. RESULTS: DWORF expression was suppressed in hearts of R14Δ/Δ mice with severe heart failure. Restoration of DWORF expression in R14Δ/Δ mice delayed cardiac fibrosis and heart failure and increased life span >2-fold (from 8 to 18 weeks). DWORF accelerated sarcoplasmic reticulum calcium reuptake and relaxation in isolated cardiomyocytes with wild-type PLN, but in R14Δ/Δ cardiomyocytes, sarcoplasmic reticulum calcium reuptake and relaxation were already enhanced, and no differences were detected between R14Δ/Δ and R14Δ/ΔDWORFTg. Rather, DWORF overexpression delayed the appearance and formation of large pathogenic perinuclear PLN clusters. Careful examination revealed colocalization of sarcoplasmic reticulum markers with these PLN clusters in both R14Δ/Δ mice and human p.Arg14del PLN heart tissue, and hence these previously termed aggregates are comprised of abnormal organized S/ER. This abnormal S/ER organization in PLN-R14del cardiomyopathy contributes to cardiomyocyte cell loss and replacement fibrosis, consequently resulting in cardiac dysfunction. CONCLUSIONS: Disorganized S/ER is a major characteristic of PLN-R14del cardiomyopathy in humans and mice and results in cardiomyocyte death. DWORF overexpression delayed PLN-R14del cardiomyopathy progression and extended life span in R14Δ/Δ mice, by reducing abnormal S/ER clusters.

Antisense Therapy Attenuates Phospholamban p.(Arg14del) Cardiomyopathy in Mice and Reverses Protein Aggregation.

Inherited cardiomyopathy caused by the p.(Arg14del) pathogenic variant of the phospholamban (PLN) gene is characterized by intracardiomyocyte PLN aggregation and can lead to severe dilated cardiomyopathy. We recently reported that pre-emptive depletion of PLN attenuated heart failure (HF) in several cardiomyopathy models. Here, we investigated if administration of a Pln-targeting antisense oligonucleotide (ASO) could halt or reverse disease progression in mice with advanced PLN-R14del cardiomyopathy. To this aim, homozygous PLN-R14del (PLN-R14 Δ/Δ) mice received PLN-ASO injections starting at 5 or 6 weeks of age, in the presence of moderate or severe HF, respectively. Mice were monitored for another 4 months with echocardiographic analyses at several timepoints, after which cardiac tissues were examined for pathological remodeling. We found that vehicle-treated PLN-R14 Δ/Δ mice continued to develop severe HF, and reached a humane endpoint at 8.1 ± 0.5 weeks of age. Both early and late PLN-ASO administration halted further cardiac remodeling and dysfunction shortly after treatment start, resulting in a life span extension to at least 22 weeks of age. Earlier treatment initiation halted disease development sooner, resulting in better heart function and less remodeling at the study endpoint. PLN-ASO treatment almost completely eliminated PLN aggregates, and normalized levels of autophagic proteins. In conclusion, these findings indicate that PLN-ASO therapy may have beneficial outcomes in PLN-R14del cardiomyopathy when administered after disease onset. Although existing tissue damage was not reversed, further cardiomyopathy progression was stopped, and PLN aggregates were resolved.

The effects of liraglutide and dapagliflozin on cardiac function and structure in a multi-hit mouse model of heart failure with preserved ejection fraction.

AIMS: Heart failure with preserved ejection fraction (HFpEF) is a multifactorial disease that constitutes several distinct phenotypes, including a common cardiometabolic phenotype with obesity and type 2 diabetes mellitus. Treatment options for HFpEF are limited, and development of novel therapeutics is hindered by the paucity of suitable preclinical HFpEF models that recapitulate the complexity of human HFpEF. Metabolic drugs, like glucagon-like peptide receptor agonist (GLP-1 RA) and sodium-glucose co-transporter 2 inhibitors (SGLT2i), have emerged as promising drugs to restore metabolic perturbations and may have value in the treatment of the cardiometabolic HFpEF phenotype. We aimed to develop a multifactorial HFpEF mouse model that closely resembles the cardiometabolic HFpEF phenotype, and evaluated the GLP-1 RA liraglutide (Lira) and the SGLT2i dapagliflozin (Dapa). METHODS AND RESULTS: Aged (18-22 months old) female C57BL/6J mice were fed a standardized chow (CTRL) or high-fat diet (HFD) for 12 weeks. After 8 weeks HFD, angiotensin II (ANGII), was administered for 4 weeks via osmotic mini pumps. HFD + ANGII resulted in a cardiometabolic HFpEF phenotype, including obesity, impaired glucose handling, and metabolic dysregulation with inflammation. The multiple hit resulted in typical clinical HFpEF features, including cardiac hypertrophy and fibrosis with preserved fractional shortening but with impaired myocardial deformation, atrial enlargement, lung congestion, and elevated blood pressures. Treatment with Lira attenuated the cardiometabolic dysregulation and improved cardiac function, with reduced cardiac hypertrophy, less myocardial fibrosis, and attenuation of atrial weight, natriuretic peptide levels, and lung congestion. Dapa treatment improved glucose handling, but had mild effects on the HFpEF phenotype. CONCLUSIONS: We developed a mouse model that recapitulates the human HFpEF disease, providing a novel opportunity to study disease pathogenesis and the development of enhanced therapeutic approaches. We furthermore show that attenuation of cardiometabolic dysregulation may represent a novel therapeutic target for the treatment of HFpEF.