Cardiac fibrosis can be attenuated by blocking the activity of transglutaminase 2 using a selective small-molecule inhibitor

Cardiac fibrosis is implicit in all forms of heart disease but there are no effective treatments. In this report, we investigate the role of the multi-functional enzyme Transglutaminase 2 (TG2) in cardiac fibrosis and assess its potential as a therapeutic target. Here we describe the use a highly selective TG2 small-molecule inhibitor to test the efficacy of TG2 inhibition as an anti-fibrotic therapy for heart failure employing two different in vivo models of cardiac fibrosis: Progressively induced interstitial cardiac fibrosis by pressure overload using angiotensin II infusion: Acutely induced focal cardiac fibrosis through myocardial infarction by ligation of the left anterior descending coronary artery (AMI model). In the AMI model, in vivo MRI showed that the TG2 inhibitor 1–155 significantly reduced infarct size by over 50% and reduced post-infarct remodelling at 20 days post insult. In both models, Sirius red staining for collagen deposition and levels of the TG2-mediated protein crosslink ε(γ-glutamyl)lysine were significantly reduced. No cardiac rupture or obvious signs of toxicity were observed. To provide a molecular mechanism for TG2 involvement in cardiac fibrosis, we show that both TGFβ1-induced transition of cardiofibroblasts into myofibroblast-like cells and TGFβ1- induced EndMT, together with matrix deposition, can be attenuated by the TG2 selective inhibitor 1–155, suggesting a new role for TG2 in regulating TGFβ1 signalling in addition to its role in latent TGFβ1 activation. In conclusion, TG2 has a role in cardiac fibrosis through activation of myofibroblasts and matrix deposition. TG2 inhibition using a selective small-molecule inhibitor can attenuate cardiac fibrosis

Clinical and echocardiographic predictors of mortality in acute pulmonary embolism

Purpose: The aim of this study was to evaluate the utility of adding quantitative assessments of cardiac function from echocardiography to clinical factors in predicting the outcome of patients with acute pulmonary embolism (PE). Methods: Patients with a diagnosis of acute PE, based on a positive ventilation perfusion scan or computed tomography (CT) chest angiogram, were identified using the Duke University Hospital Database. Of these, 69 had echocardiograms within 24–48 h of the diagnosis that were suitable for offline analysis. Clinical features that were analyzed included age, gender, body mass index, vital signs and comorbidities. Echocardiographic parameters that were analyzed included left ventricular (LV) ejection fraction (EF), regional, free wall and global RV speckle-tracking strain, RV fraction area change (RVFAC), Tricuspid Annular Plane Systolic Excursion (TAPSE), pulmonary artery acceleration time (PAAT) and RV myocardial performance (Tei) index. Univariable and multivariable regression statistical analysis models were used. Results: Out of 69 patients with acute PE, the median age was 55 and 48 % were female. The median body mass 2 index (BMI) was 27 kg/m . Twenty-nine percent of the cohort had a history of cancer, with a significant increase in cancer prevalence in non-survivors (57 % vs 29 %, p = 0.02). Clinical parameters including heart rate, respiratory rate, troponin T level, active malignancy, hypertension and COPD were higher among non-survivors when compared to survivors (p ≤ 0.05). Using univariable analysis, NYHA class III symptoms, hypoxemia on presentation, tachycardia, tachypnea, elevation in Troponin T, absence of hypertension, active malignancy and chronic obstructive pulmonary disease (COPD) were increased in non-survivors compared to survivors (p ≤ 0.05). In multivariable models, RV Tei Index, global and free (lateral) wall RVLS were found to be negatively associated with survival probability after adjusting for age, gender and systolic blood pressure (p ≤ 0.05). Conclusion: The addition of echocardiographic assessment of RV function to clinical parameters improved the prediction of outcomes for patients with acute PE. Larger studies are needed to validate these findings

Activation of Thiazide-Sensitive Co-Transport by Angiotensin II in the cyp1a1-Ren2 Hypertensive Rat

Transgenic rats with inducible expression of the mouse Ren2 gene were used to elucidate mechanisms leading to the development of hypertension and renal injury. Ren2 transgene activation was induced by administration of a naturally occurring aryl hydrocarbon, indole-3-carbinol (100 mg/kg/day by gastric gavage). Blood pressure and renal parameters were recorded in both conscious and anesthetized (butabarbital sodium; 120 mg/kg IP) rats at selected time-points during the development of hypertension. Hypertension was evident by the second day of treatment, being preceded by reduced renal sodium excretion due to activation of the thiazide-sensitive sodium-chloride co-transporter. Renal injury was evident after the first day of transgene induction, being initially limited to the pre-glomerular vasculature. Mircoalbuminuria and tubuloinsterstitial injury developed once hypertension was established. Chronic treatment with either hydrochlorothiazide or an AT1 receptor antagonist normalized sodium reabsorption, significantly blunted hypertension and prevented renal injury. Urinary aldosterone excretion was increased ∼20 fold, but chronic mineralocorticoid receptor antagonism with spironolactone neither restored natriuretic capacity nor prevented hypertension. Spironolactone nevertheless ameliorated vascular damage and prevented albuminuria. This study finds activation of sodium-chloride co-transport to be a key mechanism in angiotensin II-dependent hypertension. Furthermore, renal vascular injury in this setting reflects both barotrauma and pressure-independent pathways associated with direct detrimental effects of angiotensin II and aldosterone

OBESITY ACCELERATED TUMORIGENESIS AND DID NOT PROTECT AGAINST MURINE CANCER CACHEXIA

Thomas D. Cardaci, Brandon N. VanderVeen, Sierra J. McDonald, Brooke M. Bullard, Sarah S. Madero, Kandy T. Velazquez, FACSM, E. Angela Murphy. University of South Carolina School of Medicine, Columbia, SC. BACKGROUND: Cancer cachexia is the unintentional loss of lean mass and directly contributes to functional dependency, poor treatment outcomes, and decreased survival in cancer patients. Obesity has been suggested to protect against the severity of cachexia due to having ‘more to spare’; however, mechanistic support is lacking to promote obesity’s benefit. Further, obesity increases cancer risk contributing to the likelihood that cancer patients will be overweight or obese. Thus, the purpose of this study is to investigate the impact of obesity on cancer-induced skeletal muscle loss and function, survival, along with mitochondrial dysfunction and loss using the Lewis Lung Carcinoma (LLC) model of cancer cachexia. METHODS: Lean and obese C57/BL6 male mice (n=49) were implanted with LLC cells [1x106 cells] in the right flank or underwent sham surgery. Skeletal muscle was excised for transmission electron microscopy (TEM), histology, protein analysis, and cellular respiration 25 days following implantation or sham surgery. Cage activity and grip strength were assessed at day 0, 14, and 24. T-tests and mixed effects models were used to assess statistical differences. RESULTS: Obese LLC mice had increased tumor area (+Δ83%; p\u3c.001) and mass (+Δ176%; p\u3c.001), reduced survival (-Δ40%;p=.018), along with identical decreases in body weight (-Δ12%; p\u3c.001) and skeletal muscle mass loss (-Δ21%; p\u3c.001) compared to lean LLC mice. Preliminary TEM analysis unveils obese mice had greater evidence of mitochondrial dysfunction [auto(mito)phagic, altered cristae, contact area] (+Δ299%) regardless of LLC implantation, and identical decreases in mitochondrial content (-Δ47%) and area (-Δ53%) in obese and lean LLC mice. Cellular respiration (-Δ43%; p=.007), cage activity (-Δ66%; p\u3c.001), and relative grip strength (-Δ56%; p\u3c.001) were decreased in obese mice compared to lean mice but were not impacted by LLC implantation. CONCLUSIONS: Collectively, these data demonstrate obese mice had decreased survival and were not protected against skeletal muscle loss or mitochondrial perturbations associated with the LLC model of cancer cachexia. Moreover, our data highlight distinct obesity-dependent changes in muscle function and mitochondrial health which need to be explored further due their relevance in cancer-associated muscle wasting