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Cardioprotective Actions of Relaxin

Martin, Brian (2019) Cardioprotective Actions of Relaxin. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Relaxin, a hormone of pregnancy, has shown broad cardioprotective effects including anti-fibrotic (reversed excess TGFβ signaling), anti-arrhythmic (Nav1.5 and INa upregulation and Cx43 phosphorylation and trafficking to intercalated disks) and anti-inflammatory properties (reduced IL-1β and IL-6). While relaxin’s anti-fibrotic effects are thought to occur through the SMAD2/3/TGFβ pathway, there is a general lack of understanding of relaxin’s mode of action to increase sodium current and alter connexin43 localization to suppress arrhythmias. Based on a rat model of aging, we tested the hypothesis that relaxin acts through activation of Wnt/β-catenin signaling to mediate its effects on Nav1.5 and Cx43 and to regulate collagen expression. We show for the first time that relaxin activates canonical Wnt signaling (increased nuclear β-catenin) to increase Nav1.5 in isolated cardiomyocytes. Block of canonical Wnt signaling (via Dikkopf-1) abrogated relaxin’s effect on both Nav1.5 in cardiomyocytes and suppression of excess collagen from fibroblasts. Further, we show that relaxin significantly suppressed expression of Dikkopf-1 in isolated cardiomyocytes and whole LV tissue. In addition, show that relaxin suppressed the age-associated genetic upregulation in inflammatory markers in a sex-dependent manner. Finally, we tested the hypothesis that relaxin would be an effective therapy in a rat model of pulmonary arterial hypertension and show that it reduced occlusion of small pulmonary arteries, myocardial and lung fibrosis and reversed the cardiac phenotype of ventricular arrhythmia or arrest. These results suggest that relaxin signals through multiple pathways to achieve its myriad effects and that relaxin has great potential as a therapy for multiple cardiopulmonary diseases.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Martin, Brianbmartin027@gmail.combjm118
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSalama, Guygsalama@pitt.edu
Committee MemberRomero, Guillermoggr@pitt.edu
Committee MemberShroff, Sanjeevsshroff@pitt.edu
Committee MemberRoy, Parthapartha.roy@pitt.edu
Date: 18 June 2019
Date Type: Publication
Defense Date: 13 March 2019
Approval Date: 18 June 2019
Submission Date: 1 April 2019
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 126
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Atrial Fibrillation, Relaxin, Heart Failure, Wnt Signaling, Inflammation, Pulmonary Hypertension
Date Deposited: 18 Jun 2019 19:32
Last Modified: 18 Jun 2019 19:32
URI: http://d-scholarship.pitt.edu/id/eprint/36187

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