American Journal of Respiratory Cell and Molecular Biology最新文献

Cough variant asthma (CVA), a common reason for chronic cough, is a globally prevalent and burdensome condition. The heterogeneity of CVA and a lack of knowledge concerning the exact molecular pathogenesis has hampered its clinical management. This study presents the first sputum metabolome of patients with CVA, revealing the dynamic change during treatment and exploring biomarkers related to the occurrence and treatment response of CVA. We found that arginine biosynthesis, purine metabolism, and pyrimidine metabolism pathways were enriched in CVA compared with healthy controls. Part of the metabolic disturbances could be reversed by antiasthmatic medication. The levels of dipeptides/tripeptides (alanyl tyrosine, Gly-Tyr-Ala, Ala-Leu, and Thr-Leu) were significantly associated with sputum neutrophil or eosinophil percentages in patients with CVA. Differential metabolites before treatment between effective and ineffective treatment groups were enriched in purine metabolism, thiamine metabolism, and arginine metabolism. 2-Isopropylmalate was downregulated in CVA and increased after treatment, and the effective treatment group had a lower 2-isopropylmalate level before treatment. Random forest and logistic regression models identified glutathione, thiamine phosphate, alanyl tyrosine, and 2'-deoxyadenosine as markers for distinguishing CVA from healthy controls (all areas under the curve >0.8). Thiamine phosphate might also be promising for predicting therapy responsiveness (area under the curve, 0.684). These findings imply that disturbed mitochondrial energy metabolism and imbalanced oxidation-reduction homeostasis probably underlay the metabolic pathogenesis of CVA.

The coronavirus disease (COVID-19) pandemic has underscored the impact of viral infections on individuals with cystic fibrosis (CF). Initial observations suggested lower COVID-19 rates among CF populations; however, subsequent clinical data have presented a more complex scenario. This study aimed to investigate how bronchial epithelial cells from individuals with and without CF, including various CFTR (CF transmembrane conductance regulator) mutations, respond to in vitro infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and SARS-CoV. Comparisons with the influenza A virus (IAV) were included based on evidence that patients with CF experience heightened morbidity from IAV infection. Our findings showed that CF epithelial cells exhibited reduced replication of SARS-CoV-2, regardless of the type of CFTR mutation or SARS-CoV-2 variant, as well as the original 2003 SARS-CoV. In contrast, these cells displayed more efficient IAV replication than non-CF cells. Interestingly, the reduced susceptibility to SARS-CoV-2 in CF was not linked to the expression of ACE2 (angiotensin-converting enzyme 2) receptor or to CFTR dysfunction, as pharmacological treatments to restore CFTR function did not normalize the viral response. Both SARS-CoV-2 infection and CFTR function influenced the concentrations of certain cytokines and chemokines, although these effects were not correlated. Overall, this study reveals a unique viral response in CF epithelial cells, characterized by reduced replication for some viruses like SARS-CoV-2, while showing increased susceptibility to others, such as IAV. This research offers a new perspective on CF and viral interactions, emphasizing the need for further investigation into the mechanisms underlying these differences.

Cystic fibrosis (CF) is the most common inherited disorder and is characterized by an inflammatory phenotype. We found that in bronchial epithelium reconstituted form lung tissue biopsies from patients with CF, the RNA-binding protein tristetraprolin (TTP), a key regulator of inflammation, is dysregulated in cells that strongly express cytokines and ILs. TTP activity is regulated by extensive posttranslational modifications, particularly phosphorylation. We found that, in addition to mRNA downregulation, phosphorylated TTP (which cannot bind to mRNA) accumulated in CF cultures, suggesting that the imbalance in TTP phosphorylation status could contribute to the inflammatory phenotype in CF. We confirmed TTP's destabilizing role on IL8 mRNA through its 3' UTR sequence in CF cells. We next demonstrated that TTP phosphorylation is mainly regulated by MK2 through the activation of ERK, which also was hyperphosphorylated. TTP is considered a mRNA decay factor with some exception, and we present a new positive role of TTP in CF cultures. We determined that TTP binds to specific adenylate-uridylate-rich element motifs on the 3' UTR of mRNA sequences and also, for the first time to our knowledge, to the 3' UTR of the cystic fibrosis transmembrane conductance regulator (CFTR), where TTP binding stabilizes the mRNA level. This study identified new partners that can be targeted in CF and proposes a new way to control CFTR gene expression.

Human chromosomal anomalies, notably trisomies, disrupt gene expression, leading to diverse cellular and organ phenotypes. Increased cellular senescence (SEN) and oxidative stress in trisomies have gained recent attention. We assessed SEN, senescence-associated secretory phenotype (SASP) and oxidative stress on trisomy 13, 18, and 21 (T13, T18, T21) human fetal lung tissues and isolated primary human fetal lung fibroblasts. Telomerase associated foci (TAF) staining showed DNA damage primarily within T21 and T18 lungs. These results were confirmed by RT-qPCR showing an increase of the SEN marker CDKN2B and SASP markers IL-6 and CXCL8. In contrast, lung tissues from T13 showed an upregulation of CDKN2A, while no significant changes in SASP marker genes were observed. γ-H2AX was upregulated in each genotype, particularly in T21. Isolated fibroblasts demonstrated a strong association between T21 and several SEN markers. An increase of γ-H2AX positive cells were observed in fibroblasts from T21, T18 and T13, but only T21 exhibited an elevation in P21 expression. Solely T21 fibroblasts displayed a significant increase in reactive oxygen species (ROS) levels, as indicated by MitoSOX and CellROX. This study provides the first evidence of a link between SEN and trisomy anomalies during prenatal human lung development, particularly in T21.

Pulmonary hypertension (PH) patients typically present with a diminished platelet count, but the role of platelets in the development and progression of PH remains unclear. Our research has uncovered that within animal models of PH, platelet depletion or transfusion of platelets from healthy donors reduced pulmonary vascular thickening. In contrast, the transfusion of platelets from PH-affected subjects into healthy animals led to an augmentation of pulmonary vascular thickening. Transcriptomic analysis revealed that platelets from PH patients exhibited an upregulation of genes associated with cellular adhesion, platelet activation, and adhesion. Notably, the hub genes, glycoprotein IIb/IIIa (GP IIb/IIIa), were implicated in mediating platelet-endothelium adhesion through their interaction with intercellular adhesion molecule-1 (ICAM-1) on pulmonary arterial endothelial cells, triggering platelet activation and the subsequent release of platelet-derived growth factor BB (PDGF-BB). This release increased the proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). The pharmacological targeting of ICAM-1 has been shown to mitigate PH in a murine model under hypoxic conditions; however, this ameliorative effect was not observed in thrombocytopenic mice under analogous conditions. In summary, the adhesion of platelets to the endothelium, facilitated by GP IIb/IIIa and ICAM-1, exacerbates PH by intensifying the thickening of the pulmonary vascular wall through platelet activation and PDGF-BB secretion.

Hypoxia-inducible factors (HIF-1/2) are fundamental to the development of pulmonary hypertension (PH). Prolonged hypoxia can trigger the shift from HIF-1 to HIF-2 activity, which is critical in PH progression. Ubiquitin ligases regulate HIF activity through protein degradation. However, little is known about if or how these ligases control the HIF-1/2 switch associated with PH progression. We demonstrate that STIP1 homology and U-box containing protein1 (Stub1), an E3 ubiquitin ligase, influences HIF response to hypoxia by suppressing HIF-2 and enhancing HIF-1 mRNA, protein stability, and activity. Stub1 transgenic mice exposed to prolonged hypoxia exhibited significant decreases in pulmonary vessel and right ventricular remodeling, resulting from a failure of chronic hypoxia to trigger the transition from HIF-1α to HIF-2α and activate HIF-2α. Specifically, acute hypoxia-induced the acetylation of Stub1 at lysine-287, promoting its translocation into the nucleus and selectively suppressing HIF-2 activity. Despite the deceased total Stub1 expression, the marginal increase in Stub1^K287Ac levels was sufficient for suppressing chronic hypoxia-induced HIF-2 activity in Stub1 transgenic mice. Our findings established that Stub1 acetylation regulates the putative HIF-1/2α switch driving PH progression in hypoxic and pseudohypoxic conditions.