Abstract Body (Do not enter title and authors here): Introduction. Endotrophin, a collagen type VI–derived signaling peptide, has been linked to cardiac metabolic dysregulation, inflammation, and fibrosis. Several matrix metalloproteinases (MMPs), incl. MMP2 and MMP9, have been shown to cleave collagen 6A3 and release endotrophin. Baseline plasma endotrophin levels in heart failure with preserved ejection fraction (HFpEF) patients were shown to be strongly and independently associated with increased risk of poor outcomes (death or HF-admissions).
VS-041 is a novel drug candidate for HFpEF that inhibits key MMPs implicated in cardiac fibrosis and diastolic dysfunction. Previously, VS-041 demonstrated robust efficacy in the Dahl Salt Sensitive rat model of hypertension and HFpEF, improving diastolic function and dose-proportionally reducing left ventricle (LV) fibrosis.
Hypothesis. Inhibition of endotrophin release by VS-041 could contribute to its anti-fibrotic mechanism and serve as a potential biomarker of MMP inhibition (target engagement) in patients.
Methods and Results. The effect of VS-041 on production of endotrophin was investigated in a “Scar-in-a-Jar” model using primary human cardiac fibroblasts isolated from adult healthy ventricles. Fibroblasts were treated with 10 ng/mL platelet-derived growth factor (PDGF) AB in the presence of 0.03, 0.3, or 3 µM VS-041, or DMSO control. The concentration of endotrophin in the medium was assessed via the ELISA nordicPRO-C6^TM (Nordic Bioscience A/S). After 4 days of treatment, VS-041 at 0.3 µM and 3 µM significantly inhibited PDGF AB-stimulated production of endotrophin. Cumulative inhibitory effects of VS-041 could still be observed after 12 days of culture. The antifibrotic activity of VS-041 was also tested in a model of extensive cardiac fibrosis in 16-months old C57BL/6 mice exacerbated by angiotensin II infusion at 1 mg/kg/day for 28 days. Oral treatment with VS-041 at 75 mg/kg BID resulted in a 62% reduction (p<0.01) of LV fibrosis as assessed by morphometry of Masson trichrome stained sections. VS-041 also improved the diastolic echocardiography parameters IVRT and E/a ratio.
Conclusions. The production of endotrophin by fibroblasts is diminished by VS-041 and, therefore, its plasma levels could be explored as a biomarker of in vivo MMP inhibition by VS-041. Additionally, the inhibition of endotrophin release by VS-041 could be causatively linked to reduction of cardiac fibrosis and potentially translate into improved clinical outcomes in HFpEF patients.