Gender differences in the adipose secretome system in chronic obstructive pulmonary disease (COPD): A pivotal role of leptin

Proteomic Networks and Related Genetic Variants Associated with Smoking and Chronic Obstructive Pulmonary Disease

Background

Studies have identified individual blood biomarkers associated with chronic obstructive pulmonary disease (COPD) and related phenotypes. However, complex diseases such as COPD typically involve changes in multiple molecules with interconnections that may not be captured when considering single molecular features.

Methods

Leveraging proteomic data from 3,173 COPDGene Non-Hispanic White (NHW) and African American (AA) participants, we applied sparse multiple canonical correlation network analysis (SmCCNet) to 4,776 proteins assayed on the SomaScan v4.0 platform to derive sparse networks of proteins associated with current vs. former smoking status, airflow obstruction, and emphysema quantitated from high-resolution computed tomography scans. We then used NetSHy, a dimension reduction technique leveraging network topology, to produce summary scores of each proteomic network, referred to as NetSHy scores. We next performed genome-wide association study (GWAS) to identify variants associated with the NetSHy scores, or network quantitative trait loci (nQTLs). Finally, we evaluated the replicability of the networks in an independent cohort, SPIROMICS.

Results

We identified networks of 13 to 104 proteins for each phenotype and exposure in NHW and AA, and the derived NetSHy scores significantly associated with the variable of interests. Networks included known (sRAGE, ALPP, MIP1) and novel molecules (CA10, CPB1, HIS3, PXDN) and interactions involved in COPD pathogenesis. We observed 7 nQTL loci associated with NetSHy scores, 4 of which remained after conditional analysis. Networks for smoking status and emphysema, but not airflow obstruction, demonstrated a high degree of replicability across race groups and cohorts.

Conclusions

In this work, we apply state-of-the-art molecular network generation and summarization approaches to proteomic data from COPDGene participants to uncover protein networks associated with COPD phenotypes. We further identify genetic associations with networks. This work discovers protein networks containing known and novel proteins and protein interactions associated with clinically relevant COPD phenotypes across race groups and cohorts.

Reduced Bik expression drives low-grade airway inflammation and increased risk for COPD in females

Chronic low-grade inflammation is increasingly recognized as a subtle yet potent risk factor for a multitude of age-related disorders, including respiratory diseases, cardiovascular conditions, metabolic syndromes, autoimmunity, and cancer. In this issue of the JCI, Mebratu, Jones, and colleagues shed new light on the mechanisms that promote low-grade airway inflammation and how this contributes to the development of chronic obstructive pulmonary disease (COPD). Their finding that Bik deficiency leads to spontaneous emphysema in female mice, but not in males, marks a notable advancement in our understanding of how inflammatory processes can diverge based on biological sex. This finding is of clinical relevance, given the vulnerability of women to developing COPD.

The association between adipokines and pulmonary diseases: a mendelian randomization study

BACKGROUND

The role of adipokines in the development of lung diseases is significant, yet their specific relationship with different lung diseases remains unclear.

METHODS

In our research, we analyzed genetic variations associated with adipokines and various lung conditions such as interstitial lung disease, chronic obstructive pulmonary disease, asthma, lung cancer, sleep apnea, pneumonia, and tuberculosis, using data from public genome-wide studies. We employed Mendelian randomization techniques, including inverse variance weighting, weighted median, and MR-Egger regression methods, and conducted sensitivity checks to validate our findings.

RESULTS

A study using the FinnGen database, which included 198,955 participants, identified 13 SNPs associated with adiponectin. Notably, adiponectin was found to significantly reduce the risk of interstitial lung disease and idiopathic pulmonary fibrosis. However, little evidence was found to establish a direct cause-effect relationship between the six adipokines and several other lung conditions, including sarcoidosis, asthma, chronic obstructive pulmonary disease, lung cancer, tuberculosis, pneumonia, and sleep apnea syndrome.

CONCLUSION

This study reveals a reverse link between adiponectin levels and the likelihood of interstitial lung disease, including idiopathic pulmonary fibrosis.

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.

Lower geriatric nutritional risk index is associated with a higher risk of all-cause mortality in patients with chronic obstructive pulmonary disease: a cohort study from the National Health and Nutrition Examination Survey 2013-2018

OBJECT

Malnutrition negatively affects patients with chronic obstructive pulmonary disease (COPD). This study aimed to explore the potential association between malnutrition, as defined by the Geriatric Nutritional Risk Index (GNRI), and all-cause mortality in patients with COPD using the National Health and Nutrition Examination Survey (NHANES).

METHOD

The data of 579 adults with COPD during NHANES 2013-2018 were analysed. Each patient was assigned to one of the two groups according to GNRI values: normal nutritional status (GNRI>98) and malnutrition status (GNRI≤98). Survival curves and Cox regressions were applied to evaluate the association between nutritional status and mortality.

RESULTS

Overall, the mean age was 63.4±0.5 years, and 53.9% of the patients were women. The prevalence of malnutrition was 6.6%, and the Kaplan-Meier curves for all-cause mortality according to nutritional status showed that malnutrition was associated with a higher incidence of all-cause mortality. The Cox regression analysis found that in the unadjusted model, the HR was 2.30 (95% CI 1.24 to 4.27, p=0.01). In the fully adjusted model, the adjusted HR was 2.47 (95% CI 1.36 to 4.5, p=0.003). Furthermore, subgroup analysis revealed that the risk of death due to malnutrition increased more than threefold in the low education and cancer subgroups.

CONCLUSION

A low GNRI was an independent risk factor for all-cause mortality in patients with COPD.

Bone health in ambulatory male patients with chronic obstructive airway disease - A case control study from India

Objective

Chronic obstructive airway disease (COPD) is characterized by airflow limitation due to airway and/or alveolar abnormalities with significant extra-pulmonary manifestations. Bone health impairment is an extra-pulmonary complication of COPD which is less well studied in India. Moreover, it can contribute to significant morbidity and mortality. Hence, we aim to estimate the prevalence of osteoporosis and metabolic parameters of adverse bone health in patients with COPD.

Methods

In this case control study, male subjects aged 40-70 years with COPD attending the respiratory outpatient clinic in a tertiary care hospital were recruited over a period of 2 years and the control population were derived from the historical cohort who were apparently healthy with no obvious diseases. Metabolic parameters of bone health measured from fasting blood samples were calcium, albumin, alkaline phosphatase, phosphorous, parathormone, creatinine, 25-hydroxy vitamin D, and testosterone. Bone mineral density (BMD) was estimated using DXA scan and the World Health Organization (WHO) criteria was used to categorize into osteoporosis, osteopenia, and normal BMD based on the T-score at femoral neck, lumbar spine and distal forearm. Pulmonary function tests and 6 minute walk test were performed if they had not been done in the previous 3 months. The associations of COPD with osteoporosis were analyzed using linear regression analysis and effect size are presented as beta with 95% confidence interval.

Results

Of the 67 participants with COPD enrolled in the study, osteoporosis was present in 61% (41/67) and osteopenia in an additional 33% (22/67) of the cases, which was higher when compared to the control population (osteoporosis 20% [50/252] and osteopenia 58% [146/252]). In regression modeling, there was a trend toward adverse bone health with advanced age, low body mass index, low forced expiratory volume in 1 second and testosterone deficiency in COPD.

Conclusion

Individuals with COPD have a substantially higher prevalence of osteoporosis and osteopenia, up to almost twice that of the general population, with a significant number demonstrating at least one parameter of adverse metabolic bone health on assessment. Hence, bone health assessment should be a part of comprehensive COPD care to prevent adverse consequences due to poor bone health.

Novel Applications of Biomarkers in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is an important health problem and an increasing cause of morbidity and mortality worldwide. Currently, COPD is considered a multisystem disease. Although it primarily affects the lungs, structural and functional changes occur in other organs due to systemic inflammation. It is stated that in patients with COPD, airway and systemic inflammatory markers are increased and that these markers are high are associated with a faster decline in lung functions. In recent years, numerous articles have been published on the discovery and evaluation of biomarkers in COPD. Many markers have also been studied to accurately assess COPD exacerbations and provide effective treatment. However, based on the evidence from published studies, a single molecule has not been adequately validated for broad clinical use.

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.

Sex and Gender Omic Biomarkers in Men and Women With COPD: Considerations for Precision Medicine

Sex and gender differences in lung health and disease are imperative to consider and study if precision pulmonary medicine is to be achieved. The development of reliable COPD biomarkers has been elusive, and the translation of biomarkers to clinical care has been limited. Useful and effective biomarkers must be developed with attention to clinical heterogeneity of COPD; inherent heterogeneity exists related to grouping women and men together in the studies of COPD. Considering sex and gender differences and influences related to -omics may represent progress in susceptibility, diagnostic, prognostic, and therapeutic biomarker development and clinical innovation to improve the lung health of men and women.

Sex differences in COPD management

Introduction: A growing body of evidence indicates that prevalence of chronic obstructive pulmonary disease (COPD) has been increasing more rapidly among women compared to men, but the available data on the differences between the sexes in the responses to the various COPD therapies are still scarce.Areas covered: The aim of this narrative review is to provide an overview of current knowledge on sex differences in COPD management.Expert opinion: There is no solid evidence of sex differences in response to usual COPD treatments but there are sex-related differences in management of patients with a clinical diagnosis of COPD. It is difficult to explain the reason for these differences, but most likely they are due to local prescribing habits, rather than solid scientific reasons. However, there are also signals of different sex-related responses, the qualification and quantification of which is difficult with the information currently available. These signals should lead to the inclusion of more women in clinical trials, but also to the design of prospective clinical studies to assess the possible differences linked to sex in COPD treatment responses, whose identification is an important step toward the definition of personalized COPD therapy.

Chronic hypoxaemia and gender status modulate adiponectin plasmatic level and its multimer proportion in severe COPD patients: new endotypic presentation?

BACKGROUND

Disease progression in COPD patient is associated to lung function decline, leading to a higher risk of hypoxaemia and associated comorbidities, notably cardiovascular diseases (CVD). Adiponectin (Ad) is an adipokine with cardio-protective properties. In COPD patients, conflicting results were previously reported regarding Ad plasmatic (Adpl) level, probably because COPD is a heterogeneous disease with multifactorial influence. Among these factors, gender and hypoxaemia could interact in a variety of ways with Ad pathway. Therefore, we postulated that these components could influence Adpl level and its multimers in COPD patients and contribute to the appearance of a distinct endotype associated to an altered CVD risk.

METHODS

One hundred COPD patients were recruited: 61 were men and 39 were women. Patients who were not severely hypoxemic were allocated to non-hypoxemic group which included 46 patients: 27 men and 19 women. Hypoxemic group included 54 patients: 34 men and 20 women. For all patients, Adpl level and proportion of its different forms were measured. Differences between groups were evaluated by Rank-Sum tests. The relationship between these measures and BMI, blood gas analysis (PaO2, PaCO2), or lung function (FEV1, FEV1/FVC, TLCO, TLC, RV) were evaluated by Pearson correlation analysis.

RESULTS

Despite similar age, BMI and obstruction severity, women had a higher TLC and RV (median: TLC = 105%; RV = 166%) than men (median: TLC = 87%; RV = 132%). Adpl level was higher in women (median = 11,152 ng/ml) than in men (median = 10,239 ng/ml) and was negatively associated with hyperinflation (R = - 0,43) and hypercapnia (R = - 0,42). The proportion of the most active forms of Ad (HMW) was increased in hypoxemic women (median = 10%) compared with non-hypoxemic women (median = 8%) but was not modulated in men.

CONCLUSION

COPD pathophysiology seemed to be different in hypoxemic women and was associated to Ad modulations. Hyperinflation and air-trapping in association with hypercapnia and hypoxaemia, could contribute to a modulation of Adpl level and of its HMW forms. These results suggest the development of a distinct endotypic presentation, based on gender.

Characterization of the inflammatory-metabolic phenotype of heart failure with a preserved ejection fraction: a hypothesis to explain influence of sex on the evolution and potential treatment of the disease

Accumulating evidence points to the existence of an inflammatory-metabolic phenotype of heart failure with a preserved ejection fraction (HFpEF), which is characterized by biomarkers of inflammation, an expanded epicardial adipose tissue mass, microvascular endothelial dysfunction, normal-to-mildly increased left ventricular volumes and systolic blood pressures, and possibly, altered activity of adipocyte-associated inflammatory mediators. A broad range of adipogenic metabolic and systemic inflammatory disorders - e.g. obesity, diabetes and metabolic syndrome as well as rheumatoid arthritis and psoriasis - can cause this phenotype, independent of the presence of large vessel coronary artery disease. Interestingly, when compared with men, women are both at greater risk of and may suffer greater cardiac consequences from these systemic inflammatory and metabolic disorders. Women show disproportionate increases in left ventricular filling pressures following increases in central blood volume and have greater arterial stiffness than men. Additionally, they are particularly predisposed to epicardial and intramyocardial fat expansion and imbalances in adipocyte-associated proinflammatory mediators. The hormonal interrelationships seen in inflammatory-metabolic phenotype may explain why mineralocorticoid receptor antagonists and neprilysin inhibitors may be more effective in women than in men with HFpEF. Recognition of the inflammatory-metabolic phenotype may improve an understanding of the pathogenesis of HFpEF and enhance the ability to design clinical trials of interventions in this heterogeneous syndrome.

Chronic Obstructive Pulmonary Disease in Women: A Biologically Focused Review with a Systematic Search Strategy

Purpose

Evidence suggests that chronic obstructive pulmonary disease (COPD) symptoms and progression may differ between men and women. However, limited information is currently available on the pathophysiological and biological factors that may underlie these sex-related differences. The objective of this review is to systematically evaluate reports of potential sex-related differences, including genetic, pathophysiological, structural, and other biological factors, that may influence COPD development, manifestation, and progression in women.

Patients and Methods

A PubMed literature search was conducted from inception until January 2020. Original reports of genetic, hormonal, and physiological differences, and biological influences that could contribute to COPD development, manifestation, and progression in women were included.

Results

Overall, 491 articles were screened; 29 articles met the inclusion criteria. Results from this analysis demonstrated between-sex differences in inflammatory, immune, genetic, structural, and physiological factors in patients with COPD.

Conclusion

Various biological differences are observed between men and women with COPD including differences in inflammatory and metabolic pathways related to obesity and fat distribution, immune cell function and autophagy, extent and distribution of emphysema and airway wall remodeling. An enhanced understanding of these differences has the potential to broaden our understanding of how COPD develops and progresses, thereby providing an opportunity to ultimately improve diagnosis, treatment, and monitoring of COPD in both men and women.

Association between tumor necrosis factor-α and chronic obstructive pulmonary disease: a systematic review and meta-analysis

Background:

Patients diagnosed with chronic obstructive pulmonary disease (COPD) have increased risks for a series of physical and mental illnesses. Tumor necrosis factor-α (TNF-α) has been reported to participate in the development of COPD and its complications. However, the values of blood TNF-α level used in the diagnosis of COPD remains controversial. In view of this, we performed a systematic review and meta-analysis to evaluate the correlation between TNF-α level and COPD.

Methods:

We searched PubMed, Web of Science, Embase and CNKI up to May 2018. The selection criteria were set according to the PICOS framework. A random-effects model was then applied to evaluate the overall effect sizes by calculating standard mean difference (SMD) and its 95% confidence intervals (CIs).

Results:

A total of 40 articles containing 4189 COPD patients and 1676 healthy controls were included in this meta-analysis. The results indicated a significant increase in TNF-α level in the COPD group compared with the control group (SMD: 1.24, 95% CI: 0.78–1.71, p < 0.00001). According to the subgroup analyses, we noted that TNF-α level was associated with predicted first second of forced expiration (FEV₁) (%) and study region. However, no association between TNF-α level and COPD was found when the participants were nonsmokers, and the mean age was less than 60 years.

Conclusions:

Our results indicated that TNF-α level was increased in COPD patients when compared with healthy controls. Illness progression and a diagnosis of COPD might contribute to higher TNF-α levels. However, the underlying mechanism still remains unknown and needs further investigation.

The reviews of this paper are available via the supplemental material section.

Leptin and adiponectin levels in major depressive disorder: A systematic review and meta-analysis

OBJECTIVES

To explore differences in adipokine levels (i.e., leptin and adiponectin levels) between adults with Major Depressive Disorder (MDD) and healthy controls (HC), and to discuss the possible role of adipokine regulation in the development and progression of MDD.

METHODS

A systematic review and meta-analysis were conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. A systematic search was conducted for all English and Chinese peer-reviewed articles from inception to November 2017. A random effects model was used to calculate the standardized mean difference (SMD) of leptin and/or adiponectin levels in subjects diagnosed with MDD versus HC within a 95% confidence interval (CI).

RESULTS

Thirty-three studies were included in this meta-analysis. In total, 4,372 (52.3%) subjects with MDD and 3,984 (47.7%) HC were compared. We identified significant lower adiponectin levels in MDD compared to HC with a small effect size (ES) (SMD = -0.25; 95% CI: -0.48, -0.02; P < 0.001). However, no significant difference was observed in leptin levels between MDD subjects and HC (SMD = 0.13; 95% CI: -0.06, 0.31; P = 0.170). The heterogeneity in the results of our meta-analysis could not be completely explained by dividing subjects into subgroups. Results from subgroup analyses suggested that studies involving samples with BMI ≥ 25 had lower adiponectin levels in subjects with MDD compared to HC, and older age samples (i.e., age ≥ 40) with BMI ≥ 25 had both higher leptin levels and lower adiponectin levels in MDD subjects as compared to HC.

LIMITATIONS

The heterogeneity of included studies, small sample sizes, and potential publication bias were significant limitations.

CONCLUSIONS

The current systematic review and meta-analysis indicated that lower adiponectin levels may be associated with MDD. Moreover, the results suggest that males expressing lower adiponectin and leptin levels have an increased likelihood of developing MDD. Future studies should aim to investigate the manifestation of depressive phenotypes in older, obese populations with altered metabolic profiles resulting from adipokine dysregulation. The review has been registered with PROSPERO (registration number CRD42018082733).

Neuropeptides and breathing in health and disease

Regulatory neuropeptides control and regulate breathing in physiological and pathophysiological conditions. While they have been identified in the neurons of major respiratory areas, they can be active not only at the central level, but also at the periphery via chemoreceptors, vagal afferents, or locally within lungs and airways. Some neuropeptides, such as leptin or substance P, are respiratory stimulants; others, such as neurotensin, produce variable effects on respiration depending on the site of application. Some neuropeptides have been implicated in pathological states, such as obstructive sleep apnea or asthma. This article provides a concise review of the possible role and functions of several selected neuropeptides in the process of breathing in health and disease and in lung pathologies.

Metabolic Disorder in Chronic Obstructive Pulmonary Disease (COPD) Patients: Towards a Personalized Approach Using Marine Drug Derivatives

Metabolic disorder has been frequently observed in chronic obstructive pulmonary disease (COPD) patients. However, the exact correlation between obesity, which is a complex metabolic disorder, and COPD remains controversial. The current study summarizes a variety of drugs from marine sources that have anti-obesity effects and proposed potential mechanisms by which lung function can be modulated with the anti-obesity activity. Considering the similar mechanism, such as inflammation, shared between obesity and COPD, the study suggests that marine derivatives that act on the adipose tissues to reduce inflammation may provide beneficial therapeutic effects in COPD subjects with high body mass index (BMI).

Obesity Is Associated With Increased Morbidity in Moderate to Severe COPD

BACKGROUND

Obesity is prevalent in the United States; however, the impact of obesity on COPD morbidity is unclear. We hypothesized that obesity is associated with worse outcomes in COPD.

METHODS

We examined 3,631 participants from the multicenter prospective cohort study Genetic Epidemiology of COPD (COPDGene) who had spirometry-confirmed COPD, a postbronchodilator FEV₁ < 80% predicted, and a BMI ≥ 18.5 kg/m². We conducted logistic and linear regression analyses to determine the association between COPD outcomes and obesity class, adjusting for relevant confounders. The referent for obesity classes included normal/overweight individuals (BMI range, 18.5-29.9 kg/m²).

RESULTS

Overall, 35% of participants were obese, with 21% class I (BMI range, 30-34.9 kg/m²), 9% class II (BMI range, 35-39.9 kg/m²), and 5% class III (BMI ≥ 40 kg/m²). The number of comorbidities increased with increasing obesity class (P < .001). Increasing obesity class was independently associated with worse respiratory-specific and general quality of life (QOL) (St. George's Respiratory Questionnaire score and Short Form-36 score version 2, respectively), reduced 6-min walk distance (6MWD), increased dyspnea (Modified Medical Research Council score ≥ 2), and greater odds of severe acute exacerbation of COPD (AECOPD). The associations between obesity and worse outcomes were independent of the presence of comorbidities, except in the case of SF-36 and severe exacerbations.

CONCLUSIONS

Obesity is prevalent among individuals with COPD and associated with worse COPD-related outcomes, ranging from QOL and dyspnea to 6MWD and severe AECOPD. These associations were strengthened when obesity was analyzed as a dose-dependent response. Obesity in patients with COPD may contribute to a worse COPD-related course.

Evaluation of Individuals at Risk for COPD: Beyond the Scope of the Global Initiative for Chronic Obstructive Lung Disease

The Global initiative for chronic Obstructive Lung Disease (GOLD) Strategy is a valuable tool for clinicians in the diagnosis and management of patients with established chronic obstructive pulmonary disease (COPD). However, there are no recommendations for the evaluation of individuals, exposed to risk factors, who are most likely to develop COPD. Consequently, it is necessary to consider all of the factors that may play a role in the pathogenesis of COPD: genetic factors, gender, socioeconomic status, disadvantageous factors in childhood, lung diseases and exposure to risk factors such as smoking, biomass fuel smoke, occupational hazards and air pollution. Along with the clinical assessment, periodic spirometry should be performed to evaluate lung function and make possible early detection of individuals who will develop the disease through the rate of forced expiratory volume in 1 second (FEV₁) decline. The first spirometry, periodicity, and clinically significant decline in FEV₁ will encompass the cornerstones of clinical follow up. This approach allows the implementation of important interventions in order to help individuals to cease contact with risk factors and prevent progressive respiratory impairment with the consequent deterioration of quality of life and increased morbidity and mortality.

Gender difference in plasma fatty-acid-binding protein 4 levels in patients with chronic obstructive pulmonary disease

Plasma FABP4 levels were higher in females with COPD compared with both males with COPD and healthy females. FABP4 levels correlated inversely with lung function, and positively with adiponectin and TNFα in COPD.

COPD (chronic obstructive pulmonary disease) is characterized by airway inflammation and increases the likelihood of the development of atherosclerosis. Recent studies have indicated that FABP4 (fatty-acid-binding protein 4), an intracellular lipid chaperone of low molecular mass, plays an important role in the regulation of inflammation and atherosclerosis. We carried out a preliminary clinical study aiming at investigating the relationships between circulating FABP4 levels in patients with COPD and inflammation and lung function. We enrolled 50 COPD patients and 39 healthy controls in the study. Lung function tests were performed in all subjects. Plasma levels of FABP4 and adiponectin, TNFα (tumour necrosis factor α) and CRP (C-reactive protein) were measured. The correlations between FABP4 and lung function, adipokine (adiponectin), inflammatory factors and BMI (body mass index) were analysed. Compared with both males with COPD and healthy females, plasma FABP4 levels in females with COPD were significantly increased. Adiponectin and CRP levels were significantly higher in patients with COPD. Furthermore, we found that FABP4 levels were inversely correlated with FEV₁% predicted (FEV₁ is forced expiratory volume in 1 s) and positively correlated with adiponectin and TNFα in COPD patients. In addition, a positive correlation between plasma FABP4 and CRP was found in females with COPD. However, FABP4 levels were not correlated with BMI. Our results underline a gender difference in FABP4 secretion in stable COPD patients. Further studies are warranted to clarify the exact role of FABP4 in the pathogenesis of COPD.

Clinical potential of resistin as a novel prognostic biomarker for cellulitis

Cellulitis is an acute, subacute or chronic inflammation of the dermis and subdermal tissues, which is typically caused by bacteria, although other causes are possible. The present study aimed to evaluate the association between resistin levels and the recovery time of patients with cellulitis. In addition, the effect of resistin and insulin resistance on the prognosis of cellulitis was investigated. In total, 52 patients with cellulitis (male, 21; female, 31) and an age-matched group of 42 healthy individuals (male, 18; female, 24) were included in the study. The levels of serum resistin, fasting plasma glucose (FPG), homeostasis model assessment-insulin resistance (HOMA-IR), C-reactive protein (CRP) and other biochemical parameters were compared between the groups. The mean resistin levels in the cellulitis and control groups were 9.4±5.3 and 5.8±3.1 ng/ml, respectively. The levels of resistin, FPG, HOMA-IR and CRP were significantly higher in the cellulitis group compared with the control group (P<0.001). Furthermore, the mean recovery time of the patients with cellulitis was 21.2±5.6 days. Thus, increased levels of resistin (P=0.002) and HOMA-IR (P=0.005) could be used as predictive factors for the recovery time. The enhanced levels of resistin and HOMA-IR were shown to correlate with the high CRP levels in the cellulitis group. Therefore, the results indicated that increased levels of resistin may function as a prognostic marker for cellulitis.

Clinical potential of resistin as a novel prognostic biomarker for cellulitis

Cellulitis is an acute, subacute or chronic inflammation of the dermis and subdermal tissues, which is typically caused by bacteria, although other causes are possible. The present study aimed to evaluate the association between resistin levels and the recovery time of patients with cellulitis. In addition, the effect of resistin and insulin resistance on the prognosis of cellulitis was investigated. In total, 52 patients with cellulitis (male, 21; female, 31) and an age-matched group of 42 healthy individuals (male, 18; female, 24) were included in the study. The levels of serum resistin, fasting plasma glucose (FPG), homeostasis model assessment-insulin resistance (HOMA-IR), C-reactive protein (CRP) and other biochemical parameters were compared between the groups. The mean resistin levels in the cellulitis and control groups were 9.4±5.3 and 5.8±3.1 ng/ml, respectively. The levels of resistin, FPG, HOMA-IR and CRP were significantly higher in the cellulitis group compared with the control group (P<0.001). Furthermore, the mean recovery time of the patients with cellulitis was 21.2±5.6 days. Thus, increased levels of resistin (P=0.002) and HOMA-IR (P=0.005) could be used as predictive factors for the recovery time. The enhanced levels of resistin and HOMA-IR were shown to correlate with the high CRP levels in the cellulitis group. Therefore, the results indicated that increased levels of resistin may function as a prognostic marker for cellulitis.

Relationship between serum leptin and chronic obstructive pulmonary disease in US adults: results from the third National Health and Nutrition Examination Survey

BACKGROUND

Recent studies suggest an important role for leptin in respiratory immune responses and pathogenesis of inflammatory respiratory diseases. There has been an interest to explore whether leptin plays any role in the pathogenesis of chronic obstructive pulmonary disease (COPD).

OBJECTIVE

We conducted a population-based study to evaluate the relationship between serum leptin and COPD in the third US National Health and Nutrition Examination Survey participants.

PARTICIPANTS AND DESIGN

Our study group was constituted by 6415 adults who had fasting serum leptin and underwent spirometry measurement.

MAIN OUTCOME MEASURES

Serum leptin levels were compared (1) between subjects with normal lung function and those with COPD and (2) among COPD subjects with different severities.

RESULTS

Among male participants, 2257 were controls, and 680 had COPD. Compared with controls, COPD subjects were older (62 vs 43 years) and had higher prevalence of smokers (78% vs 58%), lower body mass index (BMI) (26.3 vs 26.9), and higher serum leptin levels (6.6 vs 5.9). For female participants, 2918 were controls, and 560 had COPD. Those with COPD were older (60 vs 43 years) and had lower BMI (26.9 vs 27.7). No differences in serum leptin levels were observed. The independent predictors of COPD in both sexes were age, BMI, and smoking, but not serum leptin. There were no differences in serum leptin among COPD subjects with different severities.

CONCLUSIONS

We did not find any significant difference in the levels of serum leptin in subjects with COPD. Our data provide indirect evidence against a major role for serum leptin in the pathogenesis of COPD in humans.

Nutritional status of an elderly population in Southwest China: a cross-sectional study based on comprehensive geriatric assessment

OBJECTIVE

Few data is available on the nutritional status of old Chinese. The present study aimed to describe the nutritional status and clinical correlates for malnutrition risk in the older people.

DESIGN

Cross-sectional study.

SETTING

Hospital- and community-based older people were recruited in the region of Chongqing, China.

PARTICIPANTS

558 individuals aged 60 years old or over between April 2011 and October 2012.

MEASUREMENTS

Comprehensive geriatric assessment was performed and nutritional status was assessed by the Mini Nutritional Assessment Short Form (MNA-SF). Nutrition-associated factors were analyzed, including health status (chronic diseases, depression, cognition, function impaired), social factors (education status, marital status, the type of work before 60 years old) and life style factors (smoking, drinking, diet).

RESULTS

The mean age was 73.1±8.0 years and 43.9% were men. Prevalence of malnutrition and risk for malnutrition were 3.2% and 19.3 %, respectively. Several factors increased poor nutrition independently including self-rated health, comorbidity, chronic obstructive pulmonary disease, gastrointestinal disease and cognitive impairment. Fish decreased the risk of poor nutrition.

CONCLUSIONS

The prevalence was relatively low in older people of Chongqing, Southwest China. Poor nutrition was found to be increased due to the common health problems. Thus the patients with these problems should pay more attention on nutritional status. The older people should often have fish because of their nutritional benefit.

Chest CT measures of muscle and adipose tissue in COPD: gender-based differences in content and in relationships with blood biomarkers

RATIONALE AND OBJECTIVES

Computed tomography (CT) of the chest can be used to assess pectoralis muscle area (PMA) and subcutaneous adipose tissue (SAT) area. Adipose tissue content is associated with inflammatory mediators in chronic obstructive pulmonary disease (COPD) subjects. Based on gender differences in body composition, we aimed to assess the hypothesis that in subjects with COPD, the relationships between PMA, SAT, and blood biomarkers of inflammation differ by gender.

MATERIALS AND METHODS

We compared chest CT measures of PMA and SAT on a single slice at aortic arch and supraesternal notch levels from 73 subjects (28 women) with COPD between genders. The relationships of PMA and SAT area to biomarkers were assessed using within-gender regression models.

RESULTS

Women had a lesser PMA and a greater SAT area than men (difference range for PMA, 13.3-22.8 cm²; for SAT, 11.8-12.4 cm²; P < .05 for all comparisons) at both anatomic levels. These differences in PMA and SAT remained significant after adjustment for age and body mass index. Within-gender regression models adjusted for age showed that SAT was directly associated with C-reactive protein (for aortic arch level, P = .04) and fibrinogen (for both anatomic locations, P = .003) only in women, whereas PMA was not associated with any biomarkers in either gender.

CONCLUSIONS

It appears that in subjects with COPD, there are gender-based differences in the relationships between subcutaneous adipose tissue and inflammatory biomarkers.

Interleukin-6 and interleukin-8 blood levels' poor association with the severity and clinical profile of ex-smokers with COPD

Background

The role of interleukins in the severity and clinical profile of chronic obstructive pulmonary disease (COPD) is not known, but evidence supports the contribution of systemic inflammation to disease pathophysiology. This study evaluated the relationship of serum biomarkers to the severity and clinical parameters of COPD.

Methods and findings

Serum levels of high-sensitivity C-reactive protein, interleukin-6 (IL-6), and interleukin-8 (IL-8) were measured in 50 patients with stable COPD and in 16 controls. The levels of these biomarkers were compared with parameters of severity, such as the grading of flow obstruction using the recommendations of the Global initiative for chronic Obstructive Lung Disease, the BMI (body mass index), obstruction, dyspnea, exercise capacity (health index) index, the number of exacerbations within the last year, and peripheral oxygen saturation after the six-minute walk test, and with clinical parameters, such as bronchitis and non-bronchitis phenotypes, the number of associated comorbidities, and the smoking burden. COPD patients exhibited higher levels of IL-6 and IL-8 compared to the control group. Higher levels of IL-6 occurred in COPD groups with body mass index <21 kg/m², with more than two exacerbations in the past year, with a higher smoking burden, and with bronchitis. The increase in serum IL-8 was found only in the group with the highest number of exacerbations within the previous year.

Conclusion

Increased IL-6 was mainly associated with smoking burden, in patients who had smoked for more than 30 pack-years and exhibited a bronchitis phenotype. No direct association was observed for both IL-6 and IL-8 blood levels with the severity of COPD in ex-smokers.

Lungs, bone marrow, and adipose tissue. A network approach to the pathobiology of chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) often suffer other concomitant disorders, such as cardiovascular diseases and metabolic disorders, that influence significantly (and independently of lung function) their health status and prognosis. Thus, COPD is not a single organ condition, and disturbances of a complex network of interorgan connected responses occur and modulate the natural history of the disease. Here, we propose a novel hypothesis that considers a vascularly connected network with (1) the lungs as the main external sensor of the system and a major source of "danger signals"; (2) the endothelium as an internal sensor of the system (also a potential target tissue); and (3) two key responding elements, bone marrow and adipose tissue, which produce both inflammatory and repair signals. According to the model, the development of COPD, and associated multimorbidities (here we focus on cardiovascular disease as an important example), depend on the manner in which the vascular connected network responds, adapts, or fails to adapt (dictated by the genetic and epigenetic background of the individual) to the inhalation of particles and gases, mainly in cigarette smoke. The caveats and limitations of the hypothesis, as well as the experimental and clinical research needed to test and explore the proposed model, are also briefly discussed.

The association of adiponectin with computed tomography phenotypes in chronic obstructive pulmonary disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disorder associated with systemic manifestations that contribute to its morbidity and mortality. Recent work suggests that biomarker signatures in the blood may be useful in evaluating COPD phenotypes and may provide insight into the pathophysiology of systemic manifestations. Adiponectin, primarily produced by fat cells, has been implicated in the pathophysiology of emphysema.

OBJECTIVES

To investigate the association of adiponectin with clinical and radiologic COPD phenotypes.

METHODS

Adiponectin levels were determined in 633 individuals, including 432 individuals with COPD from a cohort of former or current smokers enrolled in the COPDGene study. Univariate and multiple regression analysis were used to examine the association of adiponectin with clinical and physiologic data together with quantitative high-resolution computed tomography parameters.

MEASUREMENTS AND MAIN RESULTS

Multiple regression analysis confirmed that higher plasma adiponectin levels were independently associated with emphysema, decreasing body mass index, female sex, older age, and lower percentage change in prebronchodilator/post-bronchodilator FEV1.

CONCLUSIONS

The association between plasma adiponectin and computed tomography-assessed emphysema suggests a contribution of adiponectin to the development of emphysema and highlights a role for metabolic derangements in the pathophysiology of emphysema.

Adiponectin is associated with dynamic hyperinflation and a favourable response to inhaled glucocorticoids in patients with COPD

OBJECTIVES

Adipokines are protein mediators first described as products of adipose tissue regulating energy metabolism and appetite. Recently, adipokines have also been found to modulate inflammation and smooth muscle cell responses. Therefore we investigated the association of two adipokines, adiponectin and leptin, with the degree of emphysema, pulmonary function, symptoms and glucocorticoid responsiveness in patients with COPD.

METHODS

Plasma adiponectin and leptin levels, spirometry, body plethysmography and symptoms were measured in 43 male COPD patients with smoking history ≥ 20 pack-years, post bronchodilator FEV1/FVC < 0.7 and pulmonary emphysema on HRCT. The measurements were repeated in a subgroup of patients after 4 weeks' treatment with inhaled fluticasone.

RESULTS

In patients with COPD, plasma adiponectin levels correlated positively with airway resistance (Raw) (r = 0.362, p = 0.019) and functional residual capacity (FRC) (r = 0.355, p = 0.046). Furthermore, the baseline adiponectin concentration correlated negatively with the fluticasone induced changes in St George's Respiratory questionnaire (SGRQ) symptom score (r = -0.413, p = 0.040) and in FRC % pred (r = -0.428, p = 0.003), i.e. a higher baseline plasma adiponectin level was associated with more pronounced alleviation of symptoms and dynamic hyperinflation. Plasma leptin levels were not related to the measures of lung function, symptoms or glucocorticoid responsiveness.

CONCLUSIONS

Plasma adiponectin levels were associated with peripheral airway obstruction and dynamic hyperinflation in patients with COPD. A higher adiponectin level predicted more favourable relief of symptoms and hyperinflation during glucocorticoid treatment. Adiponectin may have a role in the COPD pathogenesis; it may also be a biomarker of disease severity and treatment responses in this disease.

Leptin as regulator of pulmonary immune responses: involvement in respiratory diseases

Leptin is an adipocyte-derived hormone, recognized as a critical mediator of the balance between food intake and energy expenditure by signalling through its functional receptor (Ob-Rb) in the hypothalamus. Structurally, leptin belongs to the long-chain helical cytokine family, and is now known to have pleiotropic functions in both innate and adaptive immunity. The presence of the functional leptin receptor in the lung together with evidence of increased airspace leptin levels arising during pulmonary inflammation, suggests an important role for leptin in lung development, respiratory immune responses and eventually pathogenesis of inflammatory respiratory diseases. The purpose of this article is to review our current understanding of leptin and its functional role on the different resident cell types of the lung in health as well as in the context of three major respiratory conditions being chronic obstructive pulmonary disease (COPD), asthma, and pneumonia.

Sex and race factors in early-onset COPD

PURPOSE OF REVIEW

Unlike other major diseases, mortality for chronic obstructive pulmonary disease (COPD) continues to increase. In recent years, COPD has evolved to increasingly affect women, minorities, and individuals from low socioeconomic groups. In women and African-Americans, evidence exists supporting the earlier development of COPD after less lifetime smoking. This review highlights new information on racial and sex differences in COPD.

RECENT FINDINGS

Sex and related hormonal changes affect T-cell phenotypes, immunity, and smoking-related metabolism of toxic intermediate metabolites. Alterations in the bronchoalveolar lavage proteome of women, but not of men, have allowed the differentiation of healthy female smokers from smokers with COPD. Sex significantly influences levels of inflammatory cytokines and correlates with different clinical and physiological parameters in female COPD patients. African-Americans with COPD are younger, smoke less, are more likely to currently smoke, and have worse health-related quality of life (QOL). African-Americans are more likely to report hospitalized exacerbations that impact QOL. African-Americans with COPD and asthma are nearly four times more likely to experience exacerbations.

SUMMARY

There are sex-specific and race-related differences in the manifestation of COPD. These differences warrant further physiologic, biologic, and genetic investigations.

Undernutrition in patients with COPD and its treatment

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disorder of the lung and whole body caused mainly by tobacco smoking. Patients with advanced COPD are in a state of undernutrition, referred to as pulmonary cachexia; the exercise performance and quality of life (QOL) of these patients are deteriorated, the vital prognosis is unfavorable, and the medico-economic burden posed by poorly nourished COPD patients is high. The mainstays of COPD treatment are pharmacotherapy, mainly with bronchodilators, and non-pharmacotherapeutic approaches such as respiratory rehabilitation and nutrition counseling. Nutritional supplement therapy, consisting primarily of high calorie intake, has been demonstrated to be effective for maintaining and improving the muscle strength and exercise tolerance in poorly nourished COPD patients. The efficacy of intake of various nutrients, besides a high calorie intake, for amelioration of the disease state of COPD has also been reported. The roles of adipokines in the pathophysiology of COPD have begun to receive attention recently, and not only their regulatory effects on appetite and nutritional status, but also their influence on systemic inflammation have been increasingly clarified. We review the papers on COPD and nutrition and discuss the role of nutritional supplement therapy in the treatment of COPD.

Circulatory and Adipose Tissue Leptin and Adiponectin in Relationship to Resting Energy Expenditure in Patients With Chronic Obstructive Pulmonary Disease

Increases in resting energy expenditure (REE) likely contribute to weight loss in various chronic diseases. In chronic obstructive pulmonary disease (COPD), relationships between the ventilatory impairment and increased REE, and between disturbances in adipokines and weight loss were previously described. Therefore, we investigated serum levels and adipose tissue expression of leptin and adiponectin, and their relationships to REE in patients with COPD. In 44 patients with stable COPD (38 male; age 62.3±7.2 years), REE was assessed using indirect calorimetry. Subcutaneous adipose tissue samples were analyzed using real-time PCR. From underweight [n=9; body mass index (BMI) <20.0 kg.m−2], to normal weight-overweight (n=24, BMI=20.0-29.9 kg.m−2) and obese patients (n=11; BMI≥30 kg.m−2), REE adjusted for body weight decreased (32.9±6.1 vs. 26.2±5.8 vs. 23.9±6.6 kcal.kg−1.24 h−1, p=0.006), serum levels and adipose tissue expression of leptin increased (p<0.001 for both), and serum and adipose tissue adiponectin decreased (p<0.001; p=0.004, respectively). REE was inversely related to serum and adipose tissue leptin (R=−0.547, p<0.001; R=−0.458, p=0.002), and directly to serum adiponectin (R=0.316, p=0.039). Underweight patients had increased REE compared to normal weight-overweight patients, in association with reductions in serum and adipose tissue leptin, and increased serum adiponectin, suggesting a role of adipokines in energy imbalance in COPD-related cachexia.

The influence of abdominal visceral fat on inflammatory pathways and mortality risk in obstructive lung disease

BACKGROUND

Low-grade systemic inflammation, particularly elevated IL-6, predicts mortality in chronic obstructive pulmonary disease (COPD). Although altered body composition, especially increased visceral fat (VF) mass, could be a significant contributor to low-grade systemic inflammation, this remains unexplored in COPD.

OBJECTIVE

The objective was to investigate COPD-specific effects on VF and plasma adipocytokines and their predictive value for mortality.

DESIGN

Within the Health, Aging, and Body Composition (Health ABC) Study, an observational study in community-dwelling older persons, we used propensity scores to match n = 729 persons with normal lung function to n = 243 persons with obstructive lung disease (OLD; defined as the ratio of forced expiratory volume in 1 s to forced vital capacity < lower limit of normal). Matching was based on age, sex, race, clinic site, BMI, and smoking status. Within this well-balanced match, we compared computed tomography-acquired visceral fat area (VFA) and plasma adipocytokines, analyzed independent associations of VFA and OLD status on plasma adipocytokines, and studied their predictive value for 9.4-y mortality.

RESULTS

Whereas whole-body fat mass was comparable between groups, persons with OLD had increased VFA and higher plasma IL-6, adiponectin, and plasminogen activator inhibitor 1 (PAI-1). Both OLD status and VFA were independently positively associated with IL-6. Adiponectin was positively associated with OLD status but negatively associated with VFA. PAI-1 was no longer associated with OLD status after VFA was accounted for. Participants with OLD had increased risk of all-cause, respiratory, and cardiovascular mortality, of which IL-6 was identified as an independent predictor.

CONCLUSION

Our data suggest that excessive abdominal visceral fat contributes to increased plasma IL-6, which, in turn, is strongly associated with all-cause and cause-specific mortality in older persons with OLD.

Dysregulated adipokine metabolism in chronic obstructive pulmonary disease

BACKGROUND

Research concerning the involvement of body composition and systemic inflammatory markers in adipokine metabolism in chronic obstructive pulmonary disease (COPD) is still limited. Therefore, we primarily aimed to investigate the adipokine metabolism in relation to these systemic inflammatory biomarkers and to evaluate possible gender-related differences in the adipokine metabolism in patients with COPD.

MATERIALS AND METHODS

One hundred and eighty-six subjects with COPD [mean (SD) FEV(1) %pred: 50 (±16)] and 113 controls, matched for age, gender and body composition were selected from the ECLIPSE cohort. The following serological data were collected: serum levels of leptin, adiponectin and systemic inflammatory biomarkers such as C-reactive protein (CRP), Interleukin-6 (IL-6) and fibrinogen.

RESULTS

Compared with controls, patients with COPD had higher levels of CRP, IL-6, fibrinogen and adiponectin. After stratification for gender, men with COPD had higher CRP, IL6 and fibrinogen levels compared with male controls, while women with COPD had higher levels of CRP and fibrinogen compared with the female controls. Moreover, in both female controls and patients with COPD, leptin correlated with CRP and fibrinogen, while leptin only correlated with CRP in male controls. Adiponectin correlated negatively with CRP, only in patients with COPD. Body mass index and gender were the strongest determinants for both leptin and adiponectin.

CONCLUSIONS

This study shows a gender-dependent dysregulation of adipokine metabolism in patients with COPD compared with BMI-matched controls. Furthermore, results from this study suggest a more prominent role of adiponectin in the systemic response to COPD.

Leptin, adiponectin and pulmonary diseases

Adipose tissue produces leptin and adiponectin - energy-regulating adipokines that may also play a role in inflammatory pulmonary conditions, as suggested by some murine studies. Leptin and adiponectin and their respective receptors are expressed in the human lung. The association between systemic or airway leptin and asthma in humans is currently controversial, particularly among adults. The majority of the evidence among children however suggests that systemic leptin may be associated with greater asthma prevalence and severity, particularly among prepubertal boys and peripubertal/postpubertal girls. Systemic and airway leptin concentrations may also be disproportionately higher in chronic obstructive pulmonary disease (COPD) patients, particularly among women, and reflect greater airway inflammation and disease severity. Quite like leptin, the association between systemic and airway adiponectin and asthma in humans is also controversial. Some but not all studies, demonstrate that serum adiponectin concentrations are protective against asthma among premenopausal women and peripubertal girls. On the other hand, serum adiponectin concentrations are inversely associated with asthma severity among boys but positively associated among men. Further, systemic and airway adiponectin concentrations are higher in COPD patients than controls, as demonstrated by case-control studies of men. Systemic adiponectin is also positively associated with lung function in healthy adults but inversely associated with lung function in subjects with COPD. It is therefore possible that pro-inflammatory effects of adiponectin dominate under certain physiologic conditions and anti-inflammatory effects under others. The adipokine-lung disease literature has critical gaps that include a lack of adequately powered longitudinal or weight-intervention studies; inadequate adjustment for confounding effect of obesity; and unclear understanding of potential sex interactions. It is also uncertain whether adipokine derangements precede pulmonary disease or are a consequence of it. Future research will determine whether modulation of adipokines, independent of BMI, may allow novel ways to prevent or treat inflammatory pulmonary conditions.

Low-grade adipose tissue inflammation in patients with mild-to-moderate chronic obstructive pulmonary disease

BACKGROUND

Low-grade systemic inflammation is common in chronic obstructive pulmonary disease (COPD), but its source remains unclear. Adipose tissue is a potent producer of inflammatory mediators and may contribute to systemic inflammation in COPD, possibly via hypoxia.

OBJECTIVE

We studied the influence of COPD and exercise-induced oxygen desaturation on adipose tissue inflammation (ATI) and its contribution to systemic inflammation.

DESIGN

Subcutaneous adipose tissue biopsies were investigated in 28 clinically stable COPD patients [forced expiratory volume in 1 s: 58 ± 16% predicted; BMI (in kg/m(2)): 24.9 ± 2.9] and 15 age-, sex-, and body composition-matched healthy control subjects. Fat mass was measured with dual-energy X-ray absorptiometry. Patients were prestratified by oxygen desaturation assessed by incremental cycle ergometry. The adipocyte size and adipose tissue expression of 19 inflammatory and hypoxia-related genes were measured, and adipose tissue macrophages (ATMs) were histologically quantified. Systemic inflammatory markers included C-reactive protein (CRP) and a panel of 20 adipokines.

RESULTS

COPD patients had comparable fat mass but higher CRP and HOMA-IR than did control subjects. COPD patients and control subjects had comparable adipose tissue gene expression, adipocyte size, ATM infiltration, and systemic adipokine concentrations. Desaturating COPD patients had no different ATI status than did nondesaturating COPD patients. COPD patients with high CRP had significantly greater ATM infiltration than did patients with low CRP, which was independent of BMI and fat mass.

CONCLUSIONS

In COPD patients, mild-to-moderate COPD, per se, does not enhance ATI or its contribution to systemic inflammation compared with in well-matched healthy control subjects. However, to our knowledge, our study provides a first indication for a possible role of ATMs in the systemic inflammatory response in COPD that requires additional investigation. This trial was registered at www.trialregister.nl as NTR1402.