Abstract 142: Nr3c1-Sfrp1 Axis Regulates The Adipogenic Differentiation Of Vcam1+ Fibro-adipogenic Progenitors In Chronic Limb Threatening Ischemia

Abstract

Introduction: Skeletal muscle health and function is a critical determinant of clinical outcomes in peripheral arterial disease (PAD). Fatty infiltration, the ectopic deposition of adipose tissue within skeletal muscle, is a histologic hallmark of end-stage PAD, also known as chronic limb threatening ischemia (CLTI). This process not only impairs ambulatory function, but is also associated with adverse clinical outcomes. Fatty infiltration is mediated by the adipogenic differentiation of a mesenchymal stromal population known as fibro-adipogenic progenitors (FAPs). We previously identified Vcam1+ FAPs as the dominant adipogenic population in CLTI patients. However, the mechanisms which govern the adipogenic differentiation of Vcam1+ FAPs remain unknown. Herein, we sought to identify the intracellular mechanisms that drive Vcam1+ FAPs into an adipogenic cellular fate. Methods: We analyzed the transcriptomes and epigenomes of FAPs in a murine PAD model to identify Sfrp1 and Nr3c1 as regulators of Vcam1+ FAP mediated adipogenesis. Next, to determine the necessity of Sfrp1 and Nr3c1 we silenced both genes with siRNA constructs and assessed in-vitro adipogenesis. Results: We show in a murine PAD model and human CLTI patients that Sfrp1 is enriched in Vcam1+ FAPs. Next, we use in silico analysis of our single cell RNA-sequencing dataset to identify Nr3c1 as a putative transcriptional regulator of Vcam1+ FAP adipogenic differentiation. Next, we demonstrate that inhibition of both Sfrp1 and Nr3c1 abrogates the adipogenic differentiation of Vcam1+ FAPs. Conclusions: Our results reveal a novel signaling axis for fatty infiltration in the ischemic limb. These findings lay the foundation for future studies to target maladaptive muscle regeneration in PAD patients.