Abstract Fri018: Itaconate Supplementation Attenuates Bioprosthetic Calcification via Macrophage Metabolic Reprogramming: A Preclinical Proof of Concept

Introduction: Bioprosthetic heart valves (BHV) are commonly used to replace diseased heart valves but face limited durability due to calcification. Deleterious immune responses are involved in BHV calcification, but the underlying mechanisms remain poorly understood. This study aims to elucidate the unrevealed mechanisms and explore new therapeutic strategies. Hypothesis: Immune-modulatory target engagement through precision therapeutic strategies could constitute a novel paradigm for addressing BHV Calcification Methods: Infiltration of immune cells was determined in clinical calcified BHV specimens and mouse models. Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST-seq) were integrated to resolve cellular heterogeneity and pathological progression in BHV calcification. Immunodeficient mouse models were employed to identify pivotal immune subsets. Conditional knockout mice and cell experiments were used to validate mechanistic pathways. Two clinically translatable therapeutic strategies were developed: a local sustained drug release system using layer-by-layer assembly was developed for clinical translation. Results: The spatiotemporal cell atlas revealed macrophages as the dominant immune population in calcified BHVs. Depletion of macrophages alleviated BHV calcification, while the absence of T and B cells had no significant effect. A novel Acod1lo pro-calcification macrophage subset was identified, exhibiting diminished itaconate production. The loss of Acod1/itaconate exacerbated macrophage apoptosis, oxidative stress, and extracellular matrix disruption through the HIF-1α-glycolysis pathway, ultimately leading to BHV calcification. Restoring itaconate via localized release systems suppressed BHV calcification in mouse models. Conclusions: This study pioneers the application of scRNA-seq and ST-seq to decode the immune landscape of BHV calcification, identifying Acod1lo macrophages as central mediators. Itaconate supplementation effectively suppresses calcification via modulating macrophage metabolism, leading to the development of novel strategies to reduce BHV calcification by modulating the immune response.