Cardiovascular Research Centre, Department of Pediatrics, Faculty of Medicine and Dentistry, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada.
Division of Cardiovascular Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Am J Physiol Heart Circ Physiol. 2021 Jan 1;320(1):H432-H446. doi: 10.1152/ajpheart.00737.2020. Epub 2020 Nov 13.
Following cardiac injury, increased adrenergic drive plays an important role in compensating for reduced cardiac function. However, chronic excess adrenergic stimulation can be detrimental to cardiac pathophysiology and can also affect other organs including adipose tissue, leading to increased lipolysis. Interestingly, inhibition of adipose triglyceride lipase (ATGL), a rate-limiting enzyme in lipolysis, in adipocytes ameliorates cardiac dysfunction in a heart failure model. Thus, we investigated whether inhibition of adipocyte ATGL can mitigate the adverse cardiac effects of chronic adrenergic stimulation and explored the underlying mechanisms. To do this, isoproterenol (ISO) was continuously administered to C57Bl/6N mice for 2 wk with or without an ATGL inhibitor (Atglistatin). We found that Atglistatin alleviated ISO-induced cardiac remodeling and reduced ISO-induced upregulation of galectin-3, a marker of activated macrophages and a potent inducer of fibrosis, in white adipose tissue (WAT), heart, and the circulation. To test whether the beneficial effects of Atglistatin occur via inhibition of adipocyte ATGL, adipocyte-specific ATGL knockout (atATGL-KO) mice were utilized for similar experiments. Subsequently, the same cardioprotective effects of atATGL-KO following ISO administration were observed. Furthermore, Atglistatin and atATGL-KO abolished ISO-induced galectin-3 secretion from excised WAT. We further demonstrated that activation of cardiac fibroblasts by the conditioned media of ISO-stimulated WAT is galectin-3-dependent. In conclusion, the inhibition of adipocyte ATGL ameliorated ISO-induced cardiac remodeling possibly by reducing galectin-3 secretion from adipose tissue. Thus, inhibition of adipocyte ATGL might be a potential target to prevent some of the adverse effects of chronic excess adrenergic drive. The reduction of lipolysis by adipocyte ATGL inhibition ameliorates cardiac remodeling induced by chronic β-adrenergic stimulation likely via reducing galectin-3 secretion from adipose tissue. Our findings highlight that suppressing lipolysis in adipocytes may be a potential therapeutic target for patients with heart failure whose sympathetic nervous system is activated. Furthermore, galectin-3 might be involved in the mechanisms by which excessive lipolysis in adipose tissues influences remote cardiac pathologies and thus warrants further investigation.
在心脏损伤后,肾上腺素能驱动的增加在补偿心脏功能降低方面起着重要作用。然而,慢性过度的肾上腺素刺激可能对心脏病理生理学有害,也会影响包括脂肪组织在内的其他器官,导致脂肪分解增加。有趣的是,脂肪细胞中脂肪甘油三酯脂肪酶 (ATGL) 的抑制,脂肪分解的限速酶,可改善心力衰竭模型中的心脏功能障碍。因此,我们研究了抑制脂肪细胞 ATGL 是否可以减轻慢性肾上腺素刺激的不良心脏影响,并探讨了潜在的机制。为此,用异丙肾上腺素 (ISO) 连续处理 C57Bl/6N 小鼠 2 周,并用或不用 ATGL 抑制剂 (Atglistatin)。我们发现 Atglistatin 缓解了 ISO 诱导的心脏重构,并降低了 ISO 在白色脂肪组织 (WAT)、心脏和循环中诱导的半乳糖凝集素-3 的上调,半乳糖凝集素-3 是活化巨噬细胞的标志物,也是纤维化的有效诱导剂。为了测试 Atglistatin 的有益效果是否通过抑制脂肪细胞 ATGL 发生,我们利用脂肪细胞特异性 ATGL 敲除 (atATGL-KO) 小鼠进行了类似的实验。随后,在 ISO 给药后观察到 atATGL-KO 的相同的心脏保护作用。此外,Atglistatin 和 atATGL-KO 消除了 ISO 诱导的 WAT 中半乳糖凝集素-3 的分泌。我们进一步证明,由 ISO 刺激的 WAT 的条件培养基激活心肌成纤维细胞是半乳糖凝集素-3 依赖性的。总之,脂肪细胞 ATGL 的抑制通过减少脂肪组织中半乳糖凝集素-3 的分泌改善 ISO 诱导的心脏重构。因此,抑制脂肪细胞 ATGL 可能是预防慢性过度肾上腺素能驱动的一些不良影响的潜在靶点。脂肪细胞 ATGL 抑制减少脂肪分解通过减少脂肪组织中半乳糖凝集素-3 的分泌改善由慢性β-肾上腺素刺激诱导的心脏重构。我们的研究结果表明,抑制脂肪细胞中的脂肪分解可能是交感神经系统激活的心力衰竭患者的潜在治疗靶点。此外,半乳糖凝集素-3 可能参与脂肪组织中过度脂肪分解影响远程心脏病理学的机制,因此值得进一步研究。