Abstract Body (Do not enter title and authors here): Background
Fibrosis is a hallmark of heart disease, yet direct antifibrotic therapies remain limited. We identified ANTXR1, a master regulator of fibrosis, overexpressed in diseased cardiac tissue and explored therapeutic targeting using T8Ab, a cross-species neutralizing anti-ANTXR1 monoclonal antibody initially developed for cancer therapy.
Methods
ANTXR1 expression was evaluated in human cardiac tissues and murine models of myocardial infarction (MI) and hypertension. Antxr1 knockout (KO) mice and T8Ab (15 mg/kg, 3x/week) were used to assess ANTXR1 function post-MI. T8Ab was administered intraperitoneally starting 1 d post-MI. For the hypertension models, T8Ab treatment was initiated concurrently with angiotensin II and phenylephrine (ANGII/PE) (prevention model) or following damage (reparative model). T8Ab was also tested in a prevention model of heart failure with preserved ejection fraction (HFpEF) induced by a high-fat diet (HFD) and N^[ω]-nitro-L-arginine methyl ester (L-NAME). Cardiac function was monitored via echocardiography, and mechanistic insights were obtained through single-cell RNA sequencing, histology, and biochemical analyses.
Results
ANTXR1 was highly expressed in cardiac fibroblasts of injured hearts from both humans and mice. Antxr1 KO mice displayed improved cardiac function post-MI (EF%: WT = 28.4±3.7 vs. KO = 50.1±2.5) and reduced scar size. In Antxr1KO mice, echocardiography 28 days post-MI showed improved cardiac function (WT EF% = 28.4±3.7 vs. Antxr1 KO EF% = 50.1±2.5) and reduced left ventricular scar size (n= 5-6). T8Ab treatment significantly improved cardiac function in multiple models: Post-MI (d 42): EF% = 20.1±1.9 (WT) vs. 48.0±2.5 (WT+T8Ab), n= 17–18 mice/group: Hypertension (ANGII/PE, day 28): EF% = 41.9±2.7 (WT) vs. 54.8±2.1 (WT+T8Ab), n= 15–19 mice/group: HFpEF (HFD/L-NAME, day 35): e/E′ = 22.6±0.4 (control), 32.5±1.0 (HFD/L-NAME), and 25.4±0.6 (HFD/L-NAME+T8Ab), n= 10 mice/group. Single-cell transcriptomics revealed that T8Ab suppressed expression of fibrosis-related genes (e.g., Ccn2, Ccn4, Comp, Cthrc1, Pdgfa, Meox1) and reduced maladaptive TGF-β-driven ECM remodeling. Immunofluorescent staining confirmed that T8Ab reduced late-stage aberrant collagen turnover.
Conclusions
ANTXR1 contributes to cardiac fibrosis and dysfunction. Treatment with function blocking T8Ab improved cardiac function in diverse cardiac disease models, supporting its potential use as a novel antifibrotic and cardioprotective therapy.