Metabolic syndrome is a common extrapulmonary comorbidity in patients with chronic obstructive pulmonary disease (COPD). However, the reported relationship of COPD with dyslipidemia, an important component of metabolic syndrome, is ambiguous. The aim of this meta-analysis is to investigate the association between COPD and the serum levels of high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), total cholesterol (TC), and triglyceride (TG). The PubMed and Embase databases were searched to find potential studies using the search terms of (“dyslipidemia” or “HDL” or “LDL” or “cholesterol” or “triglyceride”) and COPD. We also performed subgroup analysis enrolling patients who were not receiving treatment for dyslipidemia. Mean differences (MD) with 95% confidence intervals (CI) were estimated with random effects models. A total of 11 studies comprising 615 cases and 471 controls were included in the study. No significant differences were found in the HDL (MD = −2.55, 95% CI [−6.03, 0.93], P = 0.15), LDL (MD = −2.25, 95% CI [−13.36, 8.86], P = 0.69), TC (MD = −2.69, 95% CI [−13.30, 7.92], P = 0.62), and TG (MD = 6.90, 95% CI [−2.81, 16.60], P = 0.16) levels of the 2 groups. However, subgroup analysis enrolling patients who were not receiving treatment for dyslipidemia showed that TG levels were higher in patients with stable COPD than in healthy individuals (MD = 16.35, 95% CI [5.90, 26.80], P = 0.002). Excluding the impact of hypolipidemic treatment on serum lipid profile, TG levels were higher in patients with COPD than in healthy individuals. This meta-analysis suggested that physicians should screen COPD patients for elevated TG levels to reduce the risk of cardiovascular morbidity and mortality.

Background: Ceramide, a bioactive lipid, plays an essential role in the development of several pulmonary inflammatory diseases. Matrix metallopeptidase 9 (MMP-9) regulates the synthesis and degradation of extracellular matrix, and is associated with airway remodeling and tissue injury. This study was conducted to investigate the effects and underlying mechanisms of ceramide on MMP-9 expression in airway epithelium. Methods: BEAS-2B cells, normal human bronchial epithelium cell lines, were pretreated with AG490, a selective janus tyrosine kinase 2 (JAK2) inhibitor, or Stattic, a selective signal transducer and activator of transcription 3 (STAT3) inhibitor. The cells were then stimulated with C6-ceramide. The levels of MMP-9 were determined by ELISA and real-time quantitative PCR (RT-qPCR). JAK2, phosphorylated JAK2 (p-JAK2), STAT3, and phosphorylated STAT3 (p-STAT3) expression was examined by Western blotting. BALB/c mice were pretreated with AG490 or Stattic before intratracheally instillated with C6-ceramide. Pathological changes in lung tissues were examined by Hematoxylin and Eosin staining, Periodic-acid Schiff staining, and Masson’s trichrome staining. MMP-9, JAK2, p-JAK2, STAT3, and p-STAT3 expression in the lung tissues was examined by Western blotting. Results: The expression of MMP-9, p-JAK2 and p-STAT3 in BEAS-2B cells was significantly increased after the treatment of C6-ceramide. Furthermore, the increased expression of MMP-9 induced by C6-ceramide was inhibited by AG490 and Stattic. Similar results were obtained in the lung tissues of C6-ceramide-exposed mice which were treated with AG490 or Stattic. Conclusions: Ceramide could up-regulate MMP-9 expression through the activation of the JAK2/STAT3 pathway in airway epithelium. Targeted modulation of the ceramide signaling pathway may offer a potential therapeutic approach for inhibiting MMP-9 expression. This study points to a potentially novel approach to alleviating airway remodeling in inflammatory airway diseases.

Introduction: Obesity is a well-established risk factor for asthma pathogenesis. However, the underlying mechanisms remain incompletely understood, and effective therapeutic interventions are currently lacking, making asthma management in obese individuals particularly challenging. Asthma is characterized by chronic airway inflammation, eosinophilic infiltration, and airway hyperresponsiveness (AHR). In this study, we investigated the novel role of fibroblast growth factor 21 (FGF21), a stress-inducible hepatokine with pleiotropic metabolic regulatory functions, in obesity-associated AHR using a diet-induced obesity mouse model (n = 10). Material and Methods: Serum samples were collected from obese and lean asthma patients, along with relevant clinical indicators, including body mass index (BMI), forced expiratory volume in 1 second (FEV1%), and the FEV1/forced vital capacity (FVC) ratio, to facilitate the investigation. Moreover, diet-induced obese mice with innate AHR (male, n = 10) were employed to clarify the effects of FGF21 and FGF21-neutralizing antibody on obesity induced AHR. In vitro, LAD2 human mast cells and P815 murine mast cells activated by compound 48/80 were used to elucidate the underlying mechanisms. Results: Our findings demonstrate that serum FGF21 levels exhibit reportedly elevated in participants with obesity and are associated with impaired pulmonary function. In diet-induced obese (DIO) mice, FGF21 levels were increased in both serum and bronchoalveolar lavage fluid (BALF). In vivo investigations demonstrate that administration of recombinant FGF21 exacerbated AHR in DIO mice, whereas FGF21-neutralizing antibody treatment ameliorated obesity-induced AHR and suppressed mast cell infiltration. Mechanistically, FGF21 was found to potentiate mast cell activation through cholesterol biosynthesis modulation. Crucially, pharmacological inhibition of FGFR1 abrogated FGF21-induced mast cell hyperactivity and cholesterol synthesis, indicating FGFR1-dependent signaling in this process. Conclusion: These findings may represent the FGF21/FGFR1 axis as a potential therapeutic target for obesity-related AHR and asthma.