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      Fischer rats exhibit maladaptive structural and molecular right ventricular remodelling in severe pulmonary hypertension: a genetically prone model for right heart failure

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          Abstract

          Aims

          The ability of the right ventricle (RV) to adapt to increased afterload is the major determinant of survival in patients with pulmonary hypertension (PH). In this study, we explored the effect of genetic background on RV adaptation and survival in a rat model of severe pulmonary arterial hypertension (PAH).

          Methods and results

          PH was induced by a single injection of SU5416 (SU) in age-matched Sprague Dawley (SD) or Fischer rats, followed by a 3-week exposure to chronic hypoxia (SUHx). SD and Fischer rats exhibited similar elevations in RV systolic pressure, number of occlusive pulmonary vascular lesions, and RV hypertrophy (RV/LV+S) in response to SUHx. However, no Fischer rats survived beyond 7 weeks compared with complete survival for SD rats. This high early mortality of Fischer rats was associated with significantly greater RV dilatation and reduced ejection fraction, cardiac output, and exercise capacity at 4 weeks post-SU. Moreover, microarray analysis revealed that over 300 genes were uniquely regulated in the RV in the severe PAH model in the Fischer compared with SD rats, mainly related to angiogenesis and vascular homoeostasis, fatty acid metabolism, and innate immunity. A focused polymerase chain reaction array confirmed down-regulation of angiogenic genes in the Fischer compared with SD RV. Furthermore, Fischer rats demonstrated significantly lower RV capillary density compared with SD rats in response to SUHx.

          Conclusion

          Fischer rats are prone to develop RV failure in response to increased afterload. Moreover, the high mortality in the SUHx model of severe PAH was caused by a failure of RV adaptation associated with lack of adequate microvascular angiogenesis, together with metabolic and immunological responses in the hypertrophied RV.

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          Most cited references 33

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          Survival in patients with primary pulmonary hypertension. Results from a national prospective registry.

          To characterize mortality in persons diagnosed with primary pulmonary hypertension and to investigate factors associated with survival. Registry with prospective follow-up. Thirty-two clinical centers in the United States participating in the Patient Registry for the Characterization of Primary Pulmonary Hypertension supported by the National Heart, Lung, and Blood Institute. Patients (194) diagnosed at clinical centers between 1 July 1981 and 31 December 1985 and followed through 8 August 1988. At diagnosis, measurements of hemodynamic variables, pulmonary function, and gas exchange variables were taken in addition to information on demographic variables, medical history, and life-style. Patients were followed for survival at 6-month intervals. The estimated median survival of these patients was 2.8 years (95% Cl, 1.9 to 3.7 years). Estimated single-year survival rates were as follows: at 1 year, 68% (Cl, 61% to 75%); at 3 years, 48% (Cl, 41% to 55%); and at 5 years, 34% (Cl, 24% to 44%). Variables associated with poor survival included a New York Heart Association (NYHA) functional class of III or IV, presence of Raynaud phenomenon, elevated mean right atrial pressure, elevated mean pulmonary artery pressure, decreased cardiac index, and decreased diffusing capacity for carbon monoxide (DLCO). Drug therapy at entry or discharge was not associated with survival duration. Mortality was most closely associated with right ventricular hemodynamic function and can be characterized by means of an equation using three variables: mean pulmonary artery pressure, mean right atrial pressure, and cardiac index. Such an equation, once validated prospectively, could be used as an adjunct in planning treatment strategies and allocating medical resources.
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            Decidual NK cells regulate key developmental processes at the human fetal-maternal interface.

            Human CD56(bright) NK cells accumulate in the maternal decidua during pregnancy and are found in direct contact with fetal trophoblasts. Several mechanisms have been proposed to explain the inability of NK cells to kill the semiallogeneic fetal cells. However, the actual functions of decidual NK (dNK) cells during pregnancy are mostly unknown. Here we show that dNK cells, but not peripheral blood-derived NK subsets, regulate trophoblast invasion both in vitro and in vivo by production of the interleukin-8 and interferon-inducible protein-10 chemokines. Furthermore, dNK cells are potent secretors of an array of angiogenic factors and induce vascular growth in the decidua. Notably, such functions are regulated by specific interactions between dNK-activating and dNK-inhibitory receptors and their ligands, uniquely expressed at the fetal-maternal interface. The overall results support a 'peaceful' model for reproductive immunology, in which elements of innate immunity have been incorporated in a constructive manner to support reproductive tissue development.
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              Peroxisome proliferator-activated receptor gamma coactivator 1 coactivators, energy homeostasis, and metabolism.

              Many biological programs are regulated at the transcriptional level. This is generally achieved by the concerted actions of several transcription factors. Recent findings have shown that, in many cases, transcriptional coactivators coordinate the overall regulation of the biological programs. One of the best-studied examples of coactivator control of metabolic pathways is the peroxisome proliferator-activated receptor coactivator 1 (PGC-1) family. These proteins are strong activators of mitochondrial function and are thus dominant regulators of oxidative metabolism in a variety of tissues. The PGC-1 coactivators themselves are subject to powerful regulation at the transcriptional and posttranslational levels. Recent studies have elucidated the function of the PGC-1 coactivators in different tissues and have highlighted the implications of PGC-1 dysregulation in diseases such as diabetes, obesity, cardiomyopathy, or neurodegeneration.
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                Author and article information

                Journal
                Cardiovasc Res
                Cardiovasc. Res
                cardiovascres
                Cardiovascular Research
                Oxford University Press
                0008-6363
                1755-3245
                15 March 2019
                24 October 2018
                24 October 2018
                : 115
                : 4
                : 788-799
                Affiliations
                [1 ]Sinclair Centre for Regenerative Medicine, Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada
                [2 ]Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada
                Author notes
                Corresponding author. Tel: +1 613 737 8899 x 79017; fax: +1 613 739 6294, E-mail: djstewart@ 123456ohri.ca
                Article
                cvy258
                10.1093/cvr/cvy258
                6432055
                30357319
                © The Author(s) 2018. Published by Oxford University Press on behalf of the European Society of Cardiology

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

                Page count
                Pages: 12
                Product
                Funding
                Funded by: Canadian Health Research Institute
                Funded by: CIHR 10.13039/501100000024
                Award ID: FDN-143291
                Funded by: Northern Therapeutics Inc.
                Funded by: Heart and Stroke Foundation of Canada and Scholar
                Funded by: Canadian Vascular Network
                Funded by: CIHR 10.13039/501100000024
                Categories
                Original Articles
                Right Ventricle and Pulmonary Circulation

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