# Deletion of Cd248 in Postn+ myofibroblast fails to attenuate pressure-overload induced cardiac remodeling and fibrosis in mice

## TL;DR

Deleting Cd248 in heart myofibroblasts does not reduce heart disease or fibrosis in mice under pressure overload, despite affecting cell movement in lab tests.

## Contribution

The study reveals that Cd248's role in fibrosis is context-dependent and ineffective in vivo under pressure overload despite in vitro effects.

## Key findings

- Cd248 deletion in Postn+ myofibroblasts failed to reduce cardiac fibrosis or improve heart function in mice with pressure overload.
- Cd248 regulates cytoskeletal dynamics in cultured fibroblasts but is not essential for matrix production in vivo under pressure overload.
- Immune cell infiltration remained low in Cd248-deleted mice, suggesting its immunomodulatory role is redundant in this context.

## Abstract

Cardiac fibrosis driven by activated myofibroblasts is a central feature of pressure-overload heart disease. CD248 (Endosialin/TEM1) has been implicated as a pro-fibrotic marker in ischemic cardiac injury, but its role in pressure overload remains unclear. Here, we tested whether selective deletion of Cd248 in Periostin-expressing (Postn+) myofibroblasts mitigates pressure-overload cardiomyopathy induced by transverse aortic constriction (TAC). We generated inducible PostnMCM+/−;Cd248fl/fl mice and validated tamoxifen-driven recombination specifically in Postn+ interstitial cells. In vitro, Cd248 knockdown in primary adult mouse cardiac fibroblasts reduced TGF-β1–induced migration and the expression of actomyosin contractile markers; however, it notably failed to suppress the expression of key matrix genes (Col1a1, Postn), indicating a molecular uncoupling of cytoskeletal dynamics from collagen synthesis. Consistent with this, Postn-restricted Cd248 deletion in vivo produced no significant differences in survival, echocardiographic indices, histological fibrosis, or cardiomyocyte hypertrophy compared to controls at 8 weeks post-TAC. Furthermore, while Cd248+ fibroblasts in the TAC model were enriched for chemotactic signaling programs, immune cell infiltration remained negligible, rendering this immunomodulatory function redundant. These data indicate that while CD248 regulates fibroblast cytoskeletal dynamics in vitro, it is dispensable for matrix production and fibrosis in vivo during pressure overload. Our results highlight the profound context-dependence of CD248 as an anti-fibrotic target.

In pressure‑overloaded mouse hearts, deleting Cd248 specifically in Postn+ myofibroblasts fails to improve cardiac remodeling or fibrosis, despite clear cell-autonomous effects on cultured primary cardiac fibroblast migration and activation in vitro. Single‑cell and transcriptomic analyses reveal that while CD248 regulates actomyosin-related cytoskeletal dynamics, it is dispensable for extracellular matrix production in this specific hemodynamic context. These findings highlight the profound context‑dependent efficacy of CD248‑targeted antifibrotic strategies across different etiologies of heart disease.

Unlabelled Image

•Cd248 deletion in Postn+ cells fails to blunt pressure-overload induced fibrosis despite regulating cytoskeletal dynamics.

Cd248 deletion in Postn+ cells fails to blunt pressure-overload induced fibrosis despite regulating cytoskeletal dynamics.