Plasma irisin levels are associated with hemodynamic and clinical outcome in idiopathic pulmonary arterial hypertension patients

Skeletal muscle-derived musclin attenuates glycolysis, oxidative stress, and pulmonary hypertension through the NPR3/AKT/mTORC1 pathway

Exercise ameliorates pulmonary hypertension (PH) progression. However, the underlying mechanisms are largely unclear. Musclin is an exercise-responsive myokine that exerts protective effects on cardiovascular diseases. The current study aims to explore the role of musclin in the development of PH. A monocrotaline (MCT)-induced mouse PH model is established. Adeno-associated virus serotype 6 (AAV6)-mediated gene transfer is used to induce musclin overexpression in skeletal muscle. Ultrasound and morphological analyses are utilized to assess the severity of PH. Cell viability assay, Ki-67 immunofluorescence staining, wound healing assay, and transwell assay are used to evaluate the proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). We find that the musclin levels in both plasma and skeletal muscle are decreased in MCT-treated mice. The external expression of musclin in skeletal muscle ameliorates pulmonary arterial remodeling and right ventricular dysfunction. In vitro, musclin treatment suppresses hypoxia-induced glycolysis, oxidative stress, proliferation, and migration. Further experiments reveal that musclin inhibits mechanistic target of rapamycin complex 1 (mTORC1) activity in hypoxia-stimulated PASMCs and pulmonary arteries of MCT-treated mice. Reactivating mTORC1 abolishes the protective role of musclin against PH. Additionally, musclin enhances its interaction with natriuretic peptide receptor 3 (NPR3) in PASMCs. Silencing of NPR3 reverses the inhibitory effects of musclin on AKT phosphorylation, mTORC1 activity, glycolysis, oxidative stress, proliferation, and migration in hypoxia-challenged PASMCs. In conclusion, our study highlights the inhibitory role of musclin in the proliferation and migration of PASMCs and PH progression, thereby providing a novel potent therapeutic strategy for treating PH and partly clarifying the mechanism of exercise-mediated protection against PH.

Potential role of irisin in lung diseases and advances in research

Irisin, a myokine, is secreted by the movement of skeletal muscles. It plays an important role in metabolic homeostasis, insulin resistance, anti-inflammation, oxidative stress, and bone metabolism. Several studies have reported that irisin-related signaling pathways play a critical role in the treatment of various diseases, including obesity, cardiovascular disease, diabetes, and neurodegenerative disorders. Recently, the potential role of irisin in lung diseases, including chronic obstructive pulmonary disease, acute lung injury, lung cancer, and their associated complications, has received increasing attention. This article aims to explore the role of irisin in lung diseases, primarily focusing on the underlying molecular mechanisms, which may serve as a marker for the diagnosis as well as a potential target for the treatment of lung diseases, thus providing new strategies for their treatment.

Clinical and hemodynamic features of acute pulmonary embolism patients diagnosed in cold weather predicts adverse clinical outcome

Background

Acute pulmonary embolism (APE) is associated with peak incidence and mortality rate in winter. The present study sought to characterize the clinical and hemodynamic features of cold weather on APE patients.

Methods

All enrolled 224 APE patients underwent clinical and hemodynamic evaluation and baseline parameters were collected. Recruited patients were grouped by weather pattern on admission into cold and warm weather group. The correlation and prognostic values among cold weather and other variables were analyzed.

Results

Compared to warm weather group, patients in cold weather group present with more severe cardiac function, with adverse WHO-functional class (P = 0.032) and higher NT-proBNP concentration [1,853.0 (398.0, 5,237.0) pg/ml vs. 847.5 (56.8, 3,090.5) pg/ml, P = 0.001]. The cold weather group also displayed much critical hemodynamic status and heavier thrombosis load, with higher mPAP (29.1 ± 11.2mmHg vs. 25.6 ± 14.2mmHg, P = 0.045), higher PVR [3.3 (1.7, 6.0) wood units vs. 1.8 (0.9, 3.8) wood units, P < 0.001], higher Miller index (21.4 ± 5.9 vs. 19.1 ± 8.0, P = 0.024), and higher D-dimer levels [2,172.0 (854.5, 3,072.5) mg/L vs. 1,094.5 (210.5, 2,914.5) mg/L, P = 0.008]. Besides, cold weather showed well correlation with the above variables. Survival analysis showed APE patients in cold weather had significantly higher clinical worsening event rate (P = 0.010) and could be an independent predictor of adverse clinical outcome in the multivariate analysis (HR 2.629; 95% CI 1.127, 6.135; P = 0.025).

Conclusion

APE patients in cold weather were associated with thrombus overload, cardiac dysfunction, hemodynamic collapse and higher clinical worsening event rate. Cold weather proves to be an independent predictor of adverse clinical outcome.

Irisin: A Promising Target for Ischemia-Reperfusion Injury Therapy

Ischemia-reperfusion injury (IRI) is defined as the total combined damage that occurs during a period of ischemia and following the recovery of blood flow. Oxidative stress, mitochondrial dysfunction, and an inflammatory response are factors contributing to IRI-related damage that can each result in cell death. Irisin is a polypeptide that is proteolytically cleaved from the extracellular domain of fibronectin type III domain-containing protein 5 (FNDC5). Irisin acts as a myokine that potentially mediates beneficial effects of exercise by reducing oxidative stress, improving mitochondrial fitness, and suppressing inflammation. The existing literature also suggests a possible link between irisin and IRI, involving mechanisms similar to those associated with exercise. This article will review the pathogenesis of IRI and the potential benefits and current limitations of irisin as a therapeutic strategy for IRI, while highlighting the mechanistic correlations between irisin and IRI.

Role of Irisin in Myocardial Infarction, Heart Failure, and Cardiac Hypertrophy

Irisin is a myokine derived from the cleavage of fibronectin type III domain-containing 5. Irisin regulates mitochondrial energy, glucose metabolism, fatty acid oxidation, and fat browning. Skeletal muscle and cardiomyocytes produce irisin and affect various cardiovascular functions. In the early phase of acute myocardial infarction, an increasing irisin level can reduce endothelial damage by inhibiting inflammation and oxidative stress. By contrast, higher levels of irisin in the later phase of myocardial infarction are associated with more cardiovascular events. During different stages of heart failure, irisin has various influences on mitochondrial dysfunction, oxidative stress, metabolic imbalance, energy expenditure, and heart failure prognosis. Irisin affects blood pressure and controls hypertension through modulating vasodilatation. Moreover, irisin can enhance vasoconstriction via the hypothalamus. Because of these dual effects of irisin on cardiovascular physiology, irisin can be a critical therapeutic target in cardiovascular diseases. This review focuses on the complex functions of irisin in myocardial ischemia, heart failure, and cardiac hypertrophy.