Adiponectin: a novel link between adipose tissue and chronic obstructive pulmonary disease

Relationship between chronic obstructive pulmonary disease and adiponectin concentrations: An updated meta-analysis and single-cell RNA sequencing

BACKGROUND

Adipose tissue, being an organ of the endocrine system, can influence the severity of chronic obstructive pulmonary disease (COPD). Even though several inflammatory markers can potentially significantly influence lung function, the precise function of adipokines, like adiponectin, in COPD is still disputed. To analyze the association of COPD with adiponectin concentrations, a meta-analysis of the most recent literature and single-cell sequencing data were conducted.

METHODS

Studies in Embase, PubMed, Cochrane Library, and Web of Science were browsed to obtain relevant data, which were then assessed with the aid of R 4.1.3 and STATA 11.0 software. Standardized mean differences and correlation coefficients aided the analysis of effect values. Moreover, a single-cell sequencing GSE136831 dataset was retrieved to ascertain the mRNA expression of adiponectin gene (ADIPOQ) in the lung tissue of COPD patients to confirm the difference in the expression of adiponectin between the case and control groups.

RESULTS

This meta-analysis comprised 18 publications involving 24 studies. The overall combined data established the concentration of plasma/serum adiponectin as significantly higher in patients with COPD compared to healthy subjects. Subgroup analyses based on disease status, specimen type, ethnicity, study design method, measurement method, and age of COPD patients demonstrated that all patients with COPD had elevated levels of adiponectin compared to healthy controls. When subgroup analysis was performed for gender alone, the results depicted that male COPD patients had significantly higher adiponectin than healthy males, while female patients of COPD had elevated adiponectin compared to healthy females. Furthermore, it was found that plasma/serum adiponectin appeared to be positively correlated with tumor necrosis factor-α, and it was negatively correlated with FEV1% and FEV1/FVC. The results of single-cell sequencing data suggested that ADIPOQ mRNA was mainly expressed in alveolar epithelial cells, and the level of ADIPOQ mRNA was higher in lung tissues of patients with COPD than in lung tissues of healthy subjects.

CONCLUSION

This meta-analysis suggests that the levels of plasma/serum adiponectin are significantly elevated in patients with COPD versus controls. Tumor necrosis factor-α, FEV1/FVC, and FEV1% may all be associated with the concentrations of adiponectin.

Association between serum adiponectin concentrations and chronic obstructive pulmonary disease: a meta-analysis

Background: Adiponectin has been implicated to play a role in the pathophysiology of chronic obstructive pulmonary disease (COPD). Many studies have assessed serum adiponectin concentrations in COPD patients. However, results from different reports were not consistent. To assess the association of serum adiponectin concentrations and COPD, a meta-analysis was performed.

Methods: PubMed, Embase, Web of Science and Cochrane Library were searched for eligible studies. Data were extracted, and then standard mean differences (SMDs) and 95% confidence intervals (CI) were calculated.

Results: Thirteen studies involving a total of 1131 cases and 689 controls were included in this meta-analysis. Combined data indicated that the serum adiponectin levels were higher in COPD patients than those in controls (SMD: 1.09, 95% CI [0.73–1.45], P < 0.001). In the subgroup analyses by disease period, there were similar results in stable COPD patients (SMD: 0.77, 95% CI [0.47–1.07], p <0.001; I² = 83.9%, P < 0.001), AECOPD patients (SMD: 2.51, 95% CI [0.71–4.30], P = 0.006; I² = 95.2%, P < 0.001) and mixed COPD patients (SMD: 1.21, 95% CI [0.67–1.75], P < 0.001). Furthermore, the serum adiponectin levels were higher in AECOPD patients than those in stable COPD patients (SMD: 1.06, 95% CI [0.13–1.99], P = 0.026).

Conclusions: This meta-analysis indicates that patients with COPD have higher serum adiponectin concentration than healthy controls.

Plasminogen activator inhibitor-1 is elevated in patients with COPD independent of metabolic and cardiovascular function

INTRODUCTION

Plasminogen activator inhibitor-1 (PAI-1), a major inhibitor of fibrinolysis, is associated with thrombosis, obesity, insulin resistance, dyslipidemia, and premature aging, which all are coexisting conditions of chronic obstructive pulmonary disease (COPD). The role of PAI-1 in COPD with respect to metabolic and cardiovascular functions is unclear.

METHODS

In this study, which was nested within a prospective cohort study, the serum levels of PAI-1 were cross-sectionally measured in 74 stable COPD patients (Global Initiative for Chronic Obstructive Lung Disease [GOLD] Stages I-IV) and 18 controls without lung disease. In addition, triglycerides, high-density lipoprotein cholesterol, fasting plasma glucose, waist circumference, blood pressure, smoking status, high-sensitive C-reactive protein (hs-CRP), adiponectin, ankle-brachial index, N-terminal pro-B-type natriuretic peptide, and history of comorbidities were also determined.

RESULTS

The serum levels of PAI-1 were significantly higher in COPD patients than in controls, independent of a broad spectrum of possible confounders including metabolic and cardiovascular dysfunction. A multivariate regression analysis revealed triglyceride and hs-CRP levels to be the best predictors of PAI-1 within COPD. GOLD Stages II and III remained independently associated with higher PAI-1 levels in a final regression analysis.

CONCLUSION

The data from the present study showed that the serum levels of PAI-1 are higher in patients with COPD and that moderate-to-severe airflow limitation, hypertriglyceridemia, and systemic inflammation are independent predictors of an elevated PAI-1 level. PAI-1 may be a potential biomarker candidate for COPD-specific and extra-pulmonary manifestations.

Associations of lifelong cigarette consumption and hypertension with airflow limitation in primary care clinic outpatients in Japan

BACKGROUND

Underdiagnosis is a critical problem in the management of chronic obstructive pulmonary disease (COPD). It is important to screen patients at risk for COPD among those with lifestyle-related diseases such as hypertension, diabetes mellitus, and dyslipidemia, since these diseases promote the development of cardiovascular diseases closely associated with increased COPD mortality.

METHODS

Thirteen primary care clinics in a suburb of Tokyo participated in the current study. A total of 950 patients from these clinics were enrolled in the study between 2010 and 2012; the patients ranged in age from 40 to 79 years, and they had no diagnosed respiratory diseases at the time of enrollment. Patients fulfilling the selection criteria were recruited to undergo spirometry and then completed a self-report questionnaire about comorbid diseases and smoking habits. Spirometry was performed 15 min after inhalation of 200 μg of salbutamol sulfate.

RESULTS

The prevalence of airflow limitation was 12.7% in the 950 primary care clinic patients. Lifelong cigarette consumption was the most significant risk factor for airflow limitation, e.g., patients who smoked 60 pack-years or more had a 40% likelihood of airflow limitation. Among common lifestyle-related diseases, hypertension was associated with the severity of airflow limitation (p=0.03), whereas dyslipidemia appeared to be inversely correlated with the severity of airflow limitation (p=0.004) on multiple regression analysis including lifelong cigarette consumption as a factor.

CONCLUSIONS

Undiagnosed airflow limitation was detected in 12.7% of outpatients at the primary care clinics. Since most patients with lifestyle-related diseases are treated by primary care physicians, it is essential for the physicians to obtain an accurate history of smoking and comorbid diseases to screen patients for COPD.