Cardiovascular Pulmonary Research Laboratories, Department of Pediatrics and Medicine, University of Colorado School of Medicine, Denver, USA.
Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Denver, USA.
Vascul Pharmacol. 2023 Apr;149:107157. doi: 10.1016/j.vph.2023.107157. Epub 2023 Feb 26.
Sildenafil, a well-known vasodilator known to interfere with purinergic signaling through effects on cGMP, is a mainstay in the treatment of pulmonary hypertension (PH). However, little is known regarding its effects on the metabolic reprogramming of vascular cells, which is a hallmark of PH. Purine metabolism, especially intracellular de novo purine biosynthesis is essential for vascular cell proliferation. Since adventitial fibroblasts are critical contributors to proliferative vascular remodeling in PH, in this study we aimed to investigate if sildenafil, beyond its well-known vasodilator role in smooth muscle cells, impacts intracellular purine metabolism and proliferation of fibroblasts derived from human PH patients.
Integrated omics approaches (plasma and cell metabolomics) and pharmacological inhibitor approaches were employed in plasma samples and cultured pulmonary artery fibroblasts from PH patients.
Plasma metabolome analysis of 27 PH patients before and after treatment with sildenafil, demonstrated a partial, but specific effect of sildenafil on purine metabolites, especially adenosine, adenine, and xanthine. However, circulating markers of cell stress, including lactate, succinate, and hypoxanthine were only decreased in a small subset of sildenafil-treated patients. To better understand potential effects of sildenafil on pathological changes in purine metabolism (especially purine synthesis) in PH, we performed studies on pulmonary fibroblasts from PAH patients (PH-Fibs) and corresponding controls (CO-Fibs), since these cells have previously been shown to demonstrate stable and marked PH associated phenotypic and metabolic changes. We found that PH-Fibs exhibited significantly increased purine synthesis. Treatment of PH-Fibs with sildenafil was insufficient to normalize cellular metabolic phenotype and only modestly attenuated the proliferation. However, we observed that treatments which have been shown to normalize glycolysis and mitochondrial abnormalities including a PKM2 activator (TEPP-46), and the histone deacetylase inhibitors (HDACi), SAHA and Apicidin, had significant inhibitory effects on purine synthesis. Importantly, combined treatment with HDACi and sildenafil exhibited synergistic inhibitory effects on proliferation and metabolic reprogramming in PH-Fibs.
While sildenafil alone partially rescues metabolic alterations associated with PH, treatment with HDACi, in combination with sildenafil, represent a promising and potentially more effective strategy for targeting vasoconstriction, metabolic derangement and pathological vascular remodeling in PH.
西地那非是一种众所周知的血管扩张剂，已知通过对 cGMP 的作用干扰嘌呤能信号，是肺动脉高压（PH）治疗的主要药物。然而，关于其对血管细胞代谢重编程的影响知之甚少，这是 PH 的一个标志。嘌呤代谢，特别是细胞内从头合成嘌呤，对血管细胞增殖至关重要。由于外膜成纤维细胞是 PH 中增殖性血管重塑的关键贡献者，因此在这项研究中，我们旨在研究西地那非除了在平滑肌细胞中众所周知的血管扩张作用外，是否会影响源自 PH 患者的成纤维细胞的细胞内嘌呤代谢和增殖。
采用整合组学方法（血浆和细胞代谢组学）和药理学抑制剂方法对 PH 患者的血浆样本和培养的肺动脉成纤维细胞进行研究。
对 27 例 PH 患者在接受西地那非治疗前后的血浆代谢组进行分析，结果表明西地那非对嘌呤代谢物（尤其是腺苷、腺嘌呤和黄嘌呤）具有部分但特异性的影响。然而，仅在一小部分接受西地那非治疗的患者中，循环细胞应激标志物（包括乳酸盐、琥珀酸盐和次黄嘌呤）才降低。为了更好地了解西地那非对 PH 中嘌呤代谢（特别是嘌呤合成）病理变化的潜在影响，我们对来自肺动脉高压患者的肺成纤维细胞（PH-Fibs）和相应对照（CO-Fibs）进行了研究，因为这些细胞之前已显示出稳定和明显的 PH 相关表型和代谢变化。我们发现 PH-Fibs 表现出明显增加的嘌呤合成。西地那非治疗 PH-Fibs 不足以使细胞代谢表型正常化，仅能适度抑制增殖。然而，我们观察到，已经显示出可使糖酵解和线粒体异常正常化的治疗方法，包括 PKM2 激活剂（TEPP-46）和组蛋白去乙酰化酶抑制剂（HDACi）SAHA 和 Apicidin，对嘌呤合成具有显著的抑制作用。重要的是，HDACi 与西地那非联合治疗对 PH-Fibs 的增殖和代谢重编程具有协同抑制作用。
虽然西地那非单独部分挽救了与 PH 相关的代谢改变，但联合使用 HDACi 和西地那非治疗代表了一种有前途且更有效的策略，可用于靶向 PH 中的血管收缩、代谢紊乱和病理性血管重塑。
