Bram van den Borst

Pulmonary Function in Diabetes: A Metaanalysis

BACKGROUND Research into the association between diabetes and pulmonary function has resulted in inconsistent outcomes among studies. We performed a metaanalysis to clarify this association. METHODS From a systematic search of the literature, we included 40 studies describing pulmonary function data of 3,182 patients with diabetes and 27,080 control subjects. Associations were summarized pooling the mean difference (MD) (standard error) between patients with diabetes and control subjects of all studies for key lung function parameters. RESULTS For all studies, the pooled MD for FEV(1), FVC, and diffusion of the lungs for carbon monoxide were -5.1 (95% CI, -6.4 to -3.7; P < .001), -6.3 (95% CI, -8.0 to -4.7; P < .001), and -7.2 (95% CI, -10.0 to -4.4; P < .001) % predicted, respectively, and for FEV(1)/FVC 0.1% (95% CI, -0.8 to 1.0; P = .78). Metaregression analyses showed that between-study heterogeneity was not explained by BMI, smoking, diabetes duration, or glycated hemoglobin (all P > .05). CONCLUSIONS Diabetes is associated with a modest, albeit statistically significant, impaired pulmonary function in a restrictive pattern. Since our results apply to the diabetic subpopulation free from overt pulmonary disease, it would next be interesting to investigate the potential clinical implications in those patients with diabetes who carry a pulmonary diagnosis, such as COPD or asthma.

Loss of quadriceps muscle oxidative phenotype and decreased endurance in patients with mild-to-moderate COPD

Being well-established in advanced chronic obstructive pulmonary disease (COPD), skeletal muscle dysfunction and its underlying pathology have been scarcely investigated in patients with mild-to-moderate airflow obstruction. We hypothesized that a loss of oxidative phenotype (oxphen) associated with decreased endurance is present in the skeletal muscle of patients with mild-to-moderate COPD. In quadriceps muscle biopsies from 29 patients with COPD (forced expiratory volume in 1 s [FEV1] 58 ± 16%pred, body mass index [BMI] 26 ± 4 kg/m(2)) and 15 controls (BMI 25 ± 3 kg/m(2)) we assessed fiber type distribution, fiber cross-sectional areas (CSA), oxidative and glycolytic gene expression, OXPHOS protein levels, metabolic enzyme activity, and levels of oxidative stress markers. Quadriceps function was assessed by isokinetic dynamometry, body composition by dual-energy X-ray absorptiometry, exercise capacity by an incremental load test, and physical activity level by accelerometry. Compared with controls, patients had comparable fat-free mass index, quadriceps strength, and fiber CSA, but quadriceps endurance was decreased by 29% (P = 0.002). Patients with COPD had a clear loss of muscle oxphen: a fiber type I-to-II shift, decreased levels of OXPHOS complexes IV and V subunits (47% and 31%, respectively; P < 0.05), a decreased ratio of 3-hydroxyacyl-CoA dehydrogenase/phosphofructokinase (PFK) enzyme activities (38%, P < 0.05), and decreased peroxisome proliferator-activated receptor-γ coactivator-1α (40%; P < 0.001) vs. increased PFK (67%; P < 0.001) gene expression levels. Within the patient group, markers of oxphen were significantly positively correlated with quadriceps endurance and inversely with the increase in plasma lactate relative to work rate during the incremental test. Levels of protein carbonylation, tyrosine nitration, and malondialdehyde protein adducts were comparable between patients and controls. However, among patients, oxidative stress levels were significantly inversely correlated with markers of oxphen and quadriceps endurance. Reduced muscle endurance associated with underlying loss of muscle oxphen is already present in patients with mild-to-moderate COPD without muscle wasting.

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.

Characterization of the inflammatory and metabolic profile of adipose tissue in a mouse model of chronic hypoxia

In both obesity and chronic obstructive pulmonary disease (COPD), altered oxygen tension in adipose tissue (AT) has been suggested to evoke AT dysfunction, subsequently contributing to metabolic complications. Studying the effects of chronic hypoxia on AT function will add to our understanding of the complex pathophysiology of alterations in AT inflammation, metabolism, and mass observed in both obesity and COPD. This study investigated the inflammatory and metabolic profile of AT after chronic hypoxia. Fifty-two-week-old C57Bl/6J mice were exposed to chronic hypoxia (8% O2) or normoxia for 21 days, after which AT and plasma were collected. Adipocyte size, AT gene expression of inflammatory and metabolic genes, AT macrophage density, and circulating adipokine concentrations were measured. Food intake and body weight decreased upon initiation of hypoxia. However, whereas food intake normalized after 10 days, lower body weight persisted. Chronic hypoxia markedly reduced AT mass and adipocyte size. AT macrophage density and expression of Emr1, Ccl2, Lep, and Tnf were decreased, whereas Serpine1 and Adipoq expression levels were increased after chronic hypoxia. Concomitantly, chronic hypoxia increased AT expression of regulators of oxidative metabolism and markers of mitochondrial function and lipolysis. Circulating IL-6 and PAI-1 concentrations were increased, and leptin concentration was decreased after chronic hypoxia. Chronic hypoxia is associated with decreased rather than increased AT inflammation, and markedly decreased fat mass and adipocyte size. Furthermore, our data indicate that chronic hypoxia is accompanied by significant alterations in AT metabolic gene expression, pointing toward an enhanced AT metabolic rate.

The Prevalence of Metabolic Syndrome In Chronic Obstructive Pulmonary Disease: A Systematic Review.

Abstract Type 2 Diabetes Mellitus (T2DM) and cardiovascular diseases (CVD) are common in patients with chronic obstructive pulmonary disease (COPD). Prevention of these co-morbidities in COPD requires knowledge on their risk factors. Metabolic syndrome (MetS) predisposes to the development of T2DM and CVD but its prevalence in COPD remains unclear. The aim of this review was to assess the prevalence of MetS and its components in COPD patients compared to controls and to investigate the contribution of clinical characteristics to MetS prevalence. We systematically searched PubMed and EMBASE for original studies in COPD that have investigated the prevalence of MetS and its components. In total, 19 studies involving 4208 COPD patients were included. The pooled MetS prevalence was 34%. Compared to controls, the prevalence was higher in COPD (10 studies, 32% and 30%, p = 0.001). The three most prevalent components in both COPD and controls were arterial hypertension (56% and 51%), abdominal obesity (39% and 38%) and hyperglycemia (44% and 47%). Compared to COPD patients without MetS, those with MetS had higher body mass index (BMI) (29.9 and 24.6 kg/m2, p < 0.001), higher forced expiratory volume in 1 second (FEV1) % predicted (54 and 51, p < 0.001) and were more frequently female (31% and 25%, p = 0.011). In conclusion, the prevalence of MetS in COPD patients is high and hypertension, abdominal obesity and hyperglycemia are the most prevalent components. Further studies are needed to evaluate the impact of lifestyle factors and medications on MetS in COPD.

Dietary fibre and fatty acids in chronic obstructive pulmonary disease risk and progression: a systematic review.

Dietary intake attracts increasing interest in the risk for and progression of chronic obstructive pulmonary disease (COPD). In particular, dietary fibre and fatty acids have drawn specific attention for their immunomodulating potential. The study aimed to review the current evidence on the potential roles of dietary fibre or fatty acid intake in the risk and progression of COPD. Pubmed, EMBASE, Cochrane Collaboration Database and conference databases for original studies in adults addressing the association between fibre or fatty acid intake and COPD in terms of risk, lung function and respiratory symptoms were searched. Nine articles were included of which four reported on dietary fibre and five on fatty acids. Data of studies could not be pooled because of methodological diversity. Greater intake of dietary fibre has been consistently associated with reduced COPD risk, better lung function and reduced respiratory symptoms. Results on the associations between fatty acids and COPD are inconsistent. Dietary quality deserves further attention in developing COPD prevention and management programs.

Genetics of maximally attained lung function: A role for leptin?

OBJECTIVES To estimate the heritabilities of maximally attained lung function in young adult twins, and to examine whether circulating leptin, leptin (LEP) and leptin receptor (LEPR) gene polymorphisms are associated with maximally attained lung function. METHODS Measures on forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC) were available of 578 twins recruited from the East Flanders Prospective Twin Survey (165 monozygotic (MZ) and 73 dizygotic (DZ) complete pairs and 102 single twins). Twin model fitting and (genetic) association analyses were performed. RESULTS Intra-pair correlations of FEV(1) and FVC did not differ significantly between MZ monochorionic and MZ dichorionic pairs. Heritability estimates of FEV(1) and FVC were 69% and 63%, respectively. The A allele of the LEP 19G>A SNP was significantly associated with a lower FEV(1) (p(Additive) = 0.01) and FVC (p(Dominant) = 0.047), while the LEPR K109R and Q223R SNPs showed no associations. Accounting for body mass index, serum leptin was negatively associated with FVC (p = 0.02) in men, but not in women. CONCLUSIONS More than 60% of variation in maximally attained FEV(1) and FVC is explained by genetic factors. Moreover, these results suggest that leptin may be important in the determination of maximally attainable lung function.

The Muscle Oxidative Regulatory Response to Acute Exercise Is Not Impaired in Less Advanced COPD Despite a Decreased Oxidative Phenotype

Already in an early disease stage, patients with chronic obstructive pulmonary disease (COPD) are confronted with impaired skeletal muscle function and physical performance due to a loss of oxidative type I muscle fibers and oxidative capacity (i.e. oxidative phenotype; Oxphen). Physical activity is a well-known stimulus of muscle Oxphen and crucial for its maintenance. We hypothesized that a blunted response of Oxphen genes to an acute bout of exercise could contribute to decreased Oxphen in COPD. For this, 28 patients with less advanced COPD (age 65±7 yrs, FEV1 59±16% predicted) and 15 age- and gender-matched healthy controls performed an incremental cycle ergometry test. The Oxphen response to exercise was determined by the measurement of gene expression levels of Oxphen markers in pre and 4h-post exercise quadriceps biopsies. Because exercise-induced hypoxia and oxidative stress may interfere with Oxphen response, oxygen saturation and oxidative stress markers were assessed as well. Regardless of oxygen desaturation and absolute exercise intensities, the Oxphen regulatory response to exercise was comparable between COPD patients and controls with no evidence of increased oxidative stress. In conclusion, the muscle Oxphen regulatory response to acute exercise is not blunted in less advanced COPD, regardless of exercise-induced hypoxia. Hence, this study provides further rationale for incorporation of exercise training as integrated part of disease management to prevent or slow down loss of muscle Oxphen and related functional impairment in COPD.

Body Composition Abnormalities

Chronic obstructive pulmonary disease (COPD) is a complex and debilitating disease. Although the degree of airflow limitation is currently the main clinical determinant used for disease staging, patients within the same stage have widely varying symptoms and mortality risks. In this Chapter, we discuss the observation that body composition plays an important role in the heterogeneity of COPD. Using clinical examples, we elaborate on cachexia, obesity and aging-related changes in body composition, and how these body composition phenotypes are related to disease burden and COPD progression. Potential mechanisms contributing to a changing body composition are discussed on the level of skeletal muscle, adipose tissue and bone tissue. Finally, an overview is presented on the potential of lifestyle and drug interventions on optimizing body composition in COPD.