American Journal of Respiratory Cell and Molecular Biology最新文献

Pulmonary hypertension (PH) is an incurable disease characterized by pulmonary vascular remodeling. Endothelial injury and inflammation are the key triggers of disease initiation. Recent findings suggest that STING (stimulator of IFN genes) activation plays a critical role in endothelial dysfunction and IFN signaling. Here, we investigated the involvement of STING in the pathogenesis of PH. Patients with PH and rodent PH model samples, a Sugen 5416/hypoxia PH model, and pulmonary artery endothelial cells (PAECs) were used to evaluate the hypothesis. We found that the cyclic guanosine monophosphate-AMP synthase-STING signaling pathway was activated in lung tissues from rodent PH models and patients with PH and in TNF-α-induced PAECs in vitro. Specifically, STING expression was significantly elevated in the endothelial cells in PH disease settings. In the Sugen 5416/hypoxia mouse model, genetic knockout or pharmacological inhibition of STING prevented the progression of PH. Functionally, knockdown of STING reduced the proliferation and migration of PAECs. Mechanistically, STING transcriptionally regulates its binding partner F2RL3 (F2R-like thrombin or trypsin receptor 3) through the STING-NF-κB axis, which activated IFN signaling and repressed BMPR2 (bone morphogenetic protein receptor 2) signaling both in vitro and in vivo. Further analysis revealed that F2RL3 expression was increased in PH settings and identified negative feedback regulation of F2RL3/BMPR2 signaling. Accordingly, a positive correlation of expression amounts between STING and F2RL3/IFN-stimulated genes was observed in vivo. Our findings suggest that STING activation in PAECs plays a critical role in the pathobiology of PH. Targeting STING may be a promising therapeutic strategy for preventing the development of PH.

Numerous studies have demonstrated that endostatin (ES), a potent angiostatic peptide derived from collagen type XVIII α 1 chain and encoded by COL18A1, is elevated in pulmonary arterial hypertension (PAH). It is important to note that elevated ES has consistently been associated with altered hemodynamics, poor functional status, and adverse outcomes in adult and pediatric PAH. This study used serum samples from patients with Group I PAH and plasma and tissue samples derived from the Sugen/hypoxia rat pulmonary hypertension model to define associations between COL18A1/ES and disease development, including hemodynamics, right ventricle (RV) remodeling, and RV dysfunction. Using cardiac magnetic resonance imaging and advanced hemodynamic assessments with pressure-volume loops in patients with PAH to assess RV-pulmonary arterial coupling, we observed a strong relationship between circulating ES levels and metrics of RV structure and function. Specifically, RV mass and the ventricular mass index were positively associated with ES, whereas RV ejection fraction and RV-pulmonary arterial coupling were inversely associated with ES levels. Our animal data demonstrate that the development of pulmonary hypertension is associated with increased COL18A1/ES in the heart as well as the lungs. Disease-associated increases in COL18A1 mRNA and protein were most pronounced in the RV compared with the left ventricle and lung. COL18A1 expression in the RV was strongly associated with disease-associated changes in RV mass, fibrosis, and myocardial capillary density. These findings indicate that COL18A1/ES increases early in disease development in the RV and implicates COL18A1/ES in pathologic RV dysfunction in PAH.

Right ventricular (RV) fibrosis is associated with RV dysfunction in a variety of RV pressure-loading conditions where RV mechanical stress is increased, but the underlying mechanisms driving RV fibrosis are incompletely understood. In pulmonary and cardiovascular diseases characterized by elevated mechanical stress and transforming growth factor - beta-1 (TGF-β1) signaling, myocardin-related transcription factor A (MRTF-A) is a mechanosensitive protein critical to driving myofibroblast transition and fibrosis. Here we investigated whether MRTF-A inhibition improves RV pro-fibrotic remodeling and function in response to a pulmonary artery banding (PAB) model of RV pressure-loading. Rats were assigned into either 1) sham or 2) PAB groups. MRTF-A inhibitor CCG-1423 was administered daily at 0.75mg/kg in a subset of PAB animals. Echocardiography and pressure-volume hemodynamics were obtained at a terminal experiment 6-weeks later. RV myocardial samples were analyzed for fibrosis, cardiomyocyte hypertrophy, and pro-fibrotic signaling. MRTF-A inhibition slightly reduced systolic dysfunction in PAB rats reflected by increased lateral tricuspid annulus peak systolic velocity, while diastolic function parameters were not significantly improved. RV remodeling was attenuated in PAB rats with MRTF-A inhibition, displaying reduced fibrosis. This was accompanied with a reduction in PAB-induced upregulation of yes-associated protein (YAP) and its paralog transcriptional co-activator with PDZ-binding motif (TAZ). We also confirmed using a second-generation MRTF-A inhibitor CCG-203971 that MRTF-A is critical in driving RV fibroblast expression of TAZ and markers of myofibroblast transition in response to TGF-β1 stress and RhoA activation. These studies identify RhoA, MRTF-A, and YAP/TAZ as interconnected regulators of pro-fibrotic signaling in RV pressure-loading, and as potential targets to improve RV pro-fibrotic remodeling.

C-X-C motif chemokine ligand 14 (CXCL14) is expressed in the airway epithelial cells of patients with asthma. However, the mechanisms of CXCL14 secretion and its effects on asthma pathogenesis remain unclear. Here, we investigated the role of CXCL14 in allergic airway inflammation and its effects on eosinophil infiltration. Our findings showed that Alternaria alternata, a major environmental allergen, stimulated CXCL14 secretion from airway epithelial cells via reactive oxygen species (ROS) generated in mitochondrial oxidative phosphorylation (OXPHOS) complexes, especially in OXPHOS complex II. In vivo, in a mouse model of allergic airway inflammation, intranasal administration of anti-CXCL14 antibody suppressed eosinophil and dendritic cell infiltration into the airways and goblet cell hyperplasia. In vitro, in human eosinophil-like cells, CXCL14 promoted cell migration through C-X-C chemokine receptor type 4 (CXCR4) binding. Eosinophil CXCR4 expression was upregulated by Alternaria stimulation via ROS production. These findings suggest that the crosstalk between Alternaria-stimulated airway epithelial CXCL14 secretion and eosinophil CXCR4 upregulation plays an important role in eosinophil infiltration into the lungs during allergic airway inflammation. In summary, this study demonstrates that CXCL14 could be a therapeutic target for allergic airway inflammation.