Sex differences in cardiac fibroblast response to transient angiotensin-converting enzyme inhibition

Hypertension-induced heart failure is more prevalent in women and women commonly present with more cardiac fibrosis than men. Hypertension-induced pressure overload increases the activation of cardiac fibroblasts (CFs) and extracellular matrix (ECM) production, leading to fibrosis. Sex influences ECM remodeling yet the underlying mechanisms for these sex differences are poorly understood. Treatment of spontaneously hypertensive rats (SHR) with angiotensin-converting enzyme inhibitors (ACEi) has been shown to produce long-term protection against future fibrosis after cessation of drug treatment in males, but not females. This study identifies sex differences in the CF transcriptome at baseline and after transient ACEi treatment in SHR. Male and female adult SHR were treated with +/- ACEi for two weeks, followed by a two-week washout. CD31 - , non-cardiomyocyte cells from the left ventricle (LV) were isolated and subjected to single-nucleus RNA sequencing. We found that CFs from control male SHR display significantly higher gene expression of ECM components and genes related to epidermal growth factor receptor (EGFR) signaling than control females. CFs isolated and cultured from male SHR display a higher proliferation rate than female SHR CFs. After transient ACEi treatment, CFs from female SHR exhibit a transcriptome that suggests a higher degree of ECM remodeling and EGFR signaling. The collagen-containing ECM was the top GO term associated with genes significantly upregulated following transient ACEi in females (Benjamini p-value = 3.1E-5), including Col1a1, Col3a1, and Col4a1. The significantly upregulated KEGG pathways with the most significantly upregulated genes in CFs from female SHR after transient ACEi were pathways in cancer, ras signaling, and PI3K-AKT signaling (Benjamini p-values = 8.2E-3, 8.2E-3, and 6.5E-3, respectively). A significantly increased gene expression of Egfr and its downstream targets Sos2, Rasa2, Pik3r1, and Akt3 were observed within each pathway. In contrast, the top GO term associated with significantly downregulated genes after transient ACEi in males was the extracellular space (Benjamin p-value = 6.9E-5) with significantly reduced gene expression of several ECM components including Col4a2, Lama2, and Actn1. The findings reveal significant sex differences in CFs from SHR at baseline and following transient ACEi treatment and suggest that transient ACEi elicits a sexually dimorphic response. Increased EGFR-related gene expression in female CFs potentially contributes to their reduced protection against fibrosis compared to males. Funding source: R01HL153112 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.