Abstract:Aim To investigate the role and molecular mechanism of phosphofurin acidic cluster sorting protein-2 (PACS-2) in hypertension-related cardiac remodeling and dysfunction. Methods A mouse hypertension model was established by continuous infusion of angiotensinⅡ(AngⅡ), combined with PACS-2 knockout mice for group comparison.Systolic blood pressure (SBP) and echocardiography were used to evaluate cardiac function. Myocardial hypertrophy was assessed by heart weight/body weight ratio (HW/BW), heart weight/tibia length ratio (HW/TL), and cardiomyocyte cross-sectional area. Masson staining and immunohistochemistry staining were performed to assess myocardial fibrosis. Immunofluorescence was used to detect macrophage subsets, Western blot was used to detect myocardial fibrosis- and inflammation-related protein expression, and qPCR was used to measure inflammatory and fibrotic gene expression. In parallel, an in vitro AngⅡ-induced macrophage model combined with PACS-2 siRNA transfection was used to evaluate M1/M2 polarization and related functions. Results Compared with the control group, PACS-2 and the macrophage marker gene Mac-2 were significantly upregulated in the hypertension group, showing co-localization with Mac-2 (P＜0.05). SBP was elevated (P＜0.05), left ventricular ejection fraction (EF) and fractional shortening (FS) increased (P＜0.05), HW/BW, HW/TL and cardiomyocyte cross-sectional area were enlarged, and the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) was increased (P＜0.05). Myocardial fibrosis analysis revealed significant collagen deposition and increased α-smooth muscle actin (α-SMA) expression, accompanied by elevated transforming growth factor-β (TGF-β) and p-Smad2 protein levels (P＜0.05). Inflammatory assessment showed an increase in M1 macrophages, upregulation of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) mRNA, and enhanced phosphorylation of IκB kinase α (IKKα) and p65 (P＜0.05), whereas M2 macrophage-related factors arginase 1 (Arg1), chitinase 3-like protein 3 (Ym1) and interleukin-10 (IL-10) remained unchanged. PACS-2 knockout significantly reduced SBP, EF, FS, myocardial hypertrophy and fibrosis indices, suppressed M1 polarization and pro-inflammatory cytokine secretion, and downregulated TGF-β/Smad and nuclear factor-κB (NF-κB) signaling (P＜0.05). In vitro, AngⅡ induced an increase in M1 macrophages and inflammatory cytokine expression, while PACS-2 knockout effectively inhibited these effects (P＜0.05) without significantly affecting M2 macrophage-related factors. Moreover, PACS-2 knockout reduced macrophage adhesion to and migration toward human umbilical vein endothelial cells (P＜0.05). Conclusions PACS-2 aggravates hypertension-related myocardial hypertrophy and fibrosis by promoting M1 macrophage polarization and inflammatory cytokine production and co-activating the TGF-β/Smad and NF-κB pathways. Inhibition of PACS-2 markedly attenuates cardiac remodeling and inflammatory responses, highlighting its potential as a therapeutic target.
