Sarcopenia has become a leading cause of disability and mortality in the elderly. It has been reported that programmed cell death (PCD) is associated with the development of sarcopenia that is characterized by reduction of muscle fiber size and number. TNF-α is also validated to play a prominent role in sarcopenia through its complex signaling pathways including cell death signaling. However, it is still unclear whether TNF-α contributes to sarcopenia by mediating pyroptosis, one type of PCD. Here, we first established naturally aged mice with sarcopenia model and confirmed an inflammatory state represented by TNF-α in aged mice. Evidence of GSDME-mediated pyroptosis and activation of apoptotic caspase-8/-3 were also found in skeletal muscle cells of aged mice with sarcopenia. We demonstrated that TNF-α triggered GSDME-mediated pyroptosis in myotubes through activating caspase-8 and caspase-3 by using caspase-8 and caspase-3 inhibitors. Comparing the activation of caspase-8 and GSDME expression between TNF Complex IIa and TNF Complex IIb, TNF-α was found to be more inclined to assemble TNF Complex IIb in activating caspase-8 and triggering pyroptosis. Moreover, pyroptotic myotubes were validated to result in decreased expression of MHC1 and finally loss of myotubes by knockdown of GSDME. Our work reveals a novel mechanism that TNF-ɑ/caspase-8/caspase-3/GSDME signaling-mediated pyroptosis contributes to the development of sarcopenia. Caspase-3/GSDME signaling-mediated pyroptosis may be a promising therapeutic target for sarcopenia.

Inflammation and immunity play a causal role in the pathogenesis of pulmonary vascular remodelling and pulmonary arterial hypertension (PAH). However, the pathways and mechanisms by which inflammation and immunity contribute to pulmonary vascular remodelling remain unknown. RNA sequencing was used to analyse the transcriptome in control and rats injected with monocrotaline (MCT) for various weeks. Using the transcriptional profiling of MCT‐induced PAH coupled with bioinformatics analysis, we clustered the differentially expressed genes (DEGs) and chose the increased expression patterns associated with inflammatory and immune response. We found the enrichment of Toll‐like receptor (TLR) and Nod‐like receptor (NLR) pathways and identified NF‐κB‐mediated inflammatory and immune profiling in MCT‐induced PAH. Pathway‐based data integration and visualization showed the dysregulated TLR and NLR pathways, including increased expression of TLR2 and NLRP3, and their downstream molecules. Further analysis revealed that the activation of TLR and NLR pathways was associated with up‐regulation of damage‐associated molecular patterns (DAMPs) and RIPK3‐mediated necroptosis was involved in the generation of DAMPs in MCT‐induced PAH. Collectively, we identify RIPK3‐mediated necroptosis and its triggered TLR and NLR pathways in the progression of pulmonary vascular remodelling, thus providing novel insights into the mechanisms underlying inflammation and immunity in the pathogenesis of PAH.

Introduction: Microalbuminuria is a risk factor for cardiovascular morbidity and mortality in hypertensive patients. However, the relationship between low-grade albuminuria, a higher level of albuminuria below microalbuminuria threshold, and hypertension-related organ damage is unclear. Left ventricular (LV) hypertrophy (LVH) is well recognized to be a subclinical organ damage of hypertension, and LV diastolic dysfunction is also reported to be an early functional cardiac change of hypertension that predicts heart failure. The present study aimed to investigate the association of low-grade albuminuria with LVH and LV diastolic dysfunction in hypertensive patients. Methods: This cross-sectional observational clinical study was retrospectively performed in 870 hypertensive patients admitted to our hospital. Urinary albumin to creatinine ratio (UACR) was calculated to assess the levels of albuminuria: macroalbuminuria (≥300 mg/g), microalbuminuria (≥30 mg/g, but <300 mg/g), and normal albuminuria (<30 mg/g). Low-grade albuminuria was defined as sex-specific highest tertile within normal albuminuria (8.1–29.6 mg/g in males and 11.8–28.9 mg/g in females). LVH and LV diastolic dysfunction were identified as recommended by American Society of Echocardiography. Results: Of the 870 patients, 765 (87.9%) had normal albuminuria, 77 (8.9%) had microalbuminuria, and 28 (3.2%) had macroalbuminuria. Percentage of LVH and LV diastolic dysfunction was increased with ascending UACR. UACR was independently associated with LVH and LV diastolic dysfunction, even in patients with normal albuminuria. Multivariable logistic regression showed that the patients with the highest tertile within normal albuminuria had nearly 80% increase in LVH and nearly 60% increase in LV diastolic dysfunction (adjusted OR for LVH 1.788, 95% CI 1.181–2.708, p = 0.006; adjusted OR for LV diastolic dysfunction 1.567, 95% CI 1.036–2.397, p = 0.034). After further stratification analyses in patients with normal albuminuria, it was shown that this independent association persisted in female patients, those who were younger than 70 years old, and those with duration of hypertension <15 years. Conclusion: Low-grade albuminuria was associated with LVH and LV diastolic dysfunction in hypertensive patients, especially in patients younger than 70 years old, and those with duration of hypertension <15 years.

Pulmonary arterial hypertension (PAH) is a serious disease characterized by elevated pulmonary artery pressure, inflammatory cell infiltration and pulmonary vascular remodeling. However, little is known about the pathogenic mechanisms underlying the disease onset and progression. RNA sequencing (RNA-seq) was used to identify the transcriptional profiling in control and rats injected with monocrotaline (MCT) for 1, 2, 3 and 4 weeks. A total of 23200 transcripts and 280, 1342, 908 and 3155 differentially expressed genes (DEGs) were identified at the end of week 1, 2, 3 and 4, of which Svop was the common top 10 DEGs over the course of PAH progression. Functional enrichment analysis of DEGs showed inflammatory/immune response occurred in the early stage of PAH development. KEGG pathway enrichment analysis of DEGs showed that cytokine-cytokine receptor interaction and neuroactive ligand-receptor interaction were in the initiation and progression of PAH. Further analysis revealed impaired expression of cholinergic receptors, adrenergic receptors including alpha1, beta1 and beta2 receptor, and dysregulated expression of γ-aminobutyric acid receptors. In summary, the dysregulated inflammation/immunity and neuroactive ligand receptor signaling pathways may be involved in the onset and progression of PAH.

Metal responsive transcription factor 1 (MTF-1) is a zinc-dependent transcription factor involved in the development of pulmonary arterial hypertension (PAH), which is a life-threatening disease characterized by elevated pulmonary artery pressure and pulmonary vascular remodeling. However, little is known about the role and regulatory signaling of MTF-1 in PAH. This study aimed to investigate the effect and mechanism of MTF-1 on the proliferation of pulmonary arterial smooth muscle cells (PASMCs). Several techniques including intracellular-free zinc detected by fluorescent indicator-fluozinc-3-AM, western blot, luciferase reporter, and cell proliferation assay were conducted to perform a comprehensive analysis of MTF-1 in proliferation of PASMCs in PAH. Increased cytosolic zinc was shown in monocrotaline (MCT)-PASMCs and ZnSO₄-treated PASMCs, which led to overexpression and overactivation of MTF-1, followed by the up-regulation of placental growth factor (PlGF). Elevated MTF-1 and PlGF were observed in western blot, and high transcriptional activity of MTF-1 was confirmed by luciferase reporter in ZnSO₄-treated cells. Further investigation of cell proliferation revealed a favorable impact of zinc ions on PASMCs proliferation, with the deletion of Mtf-1/Plgf attenuating ZnSO₄-induced proliferation. Flow cytometry analysis showed that blockade of PKC signaling inhibited the cell cycle of MCT-PASMCs and ZnSO4-treated PASMCs. The Zinc/PKC/MTF-1/PlGF pathway is involved in the up-regulatory effect on the PASMCs proliferation in the process of PAH. This study provided novel insight into zinc homeostasis in the pathogenesis of PAHs, and the regulation of MTF-1 might be a potential target for therapeutic intervention in PAH.

Background: Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure, with complex etiology, difficult treatment and poor prognosis. The objective of this study was to investigate the potential biomarkers for PAH based on bioinformatics analysis. Methods: The GSE117261 datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified by screening PAH patients and controls. Then the DEGs were analyzed using a Weighted Gene Co-expression Network Analysis (WGCNA) and the key modules were determined, and to further explore their potential biological functions via Gene Ontology analysis (GO), Kyoto Encyclopedia of Genes and Genomes Pathway analysis (KEGG), and Gene Set Enrichment Analysis (GSEA). Moreover, Protein–protein interaction (PPI) networks were constructed to identify hub gene candidates in the key modules. Finally, real-time quantitative polymerase chain reaction was supplied to detect the expressions of hub genes in human pulmonary arterial smooth cells treated with cobalt chloride (COCl₂) which was used to mimic hypoxia. Results: There were 2299 DEGs identified. WGCNA indicated that yellow module was the key one correlated with PAH. GO and KEGG analysis demonstrated that genes in the yellow module were mainly enriched in ‘Pathways in cancer’. GSEA revealed that ‘HALLMARK_MYC_TARGETS_V1’ was remarkably enriched in PAH. Based on the PPI network, vascular endothelial growth factor A, proto-oncogene receptor tyrosine kinase (KIT), PNN interacting serine and arginine rich protein (PNISR) and heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1) were identified as the hub genes. Additionally, the PCR indicated that the elevated expressions of PNISR and HNRNPH1 were in line with the bioinformatics analysis. ROC analysis determined that PNISR and HNRNPH1 may be potential biomarkers to provide better diagnosis of PAH. Conclusion: PNISR and HNRNPH1 were potential biomarkers to diagnosis PAH. In summary, the identified DEGs, modules, pathways, and hub genes provide clues and shed light on the potential molecular mechanisms of PAH.