Circulating leptin concentrations in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

Integrative Analyses of Mendelian Randomization and Transcriptomic Data Reveal No Association between Leptin and Chronic Obstructive Pulmonary Disease

As a key adipokine, leptin has been extensively investigated for its potential role in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, concordant conclusions have not been attained. In this study, we investigated the relationship between leptin and COPD using an integrative analysis that combined a Mendelian randomization (MR) study with transcriptomic data analysis. Here, the MR analysis was performed on the online platform MR-Base, and the bioinformatics analyses were performed with the aid of R Bioconductor packages. No evidence was found by the integrative analysis to support the association of the two attributes. All methods detected a null causal effect of leptin on COPD in the MR analysis. In particular, when the genetically predicted leptin level increased one unit, the risk of developing COPD was estimated as 0.999 (p = 0.943), 0.920 (p = 0.516), 1.002 (p = 0.885), and 1.002 (p = 0.906) by the Inverse Variance Weighted (IVW), MR-Egger, weighted median, and weighted mode method, respectively. Furthermore, no leptin-associated genes except one were identified as being differentially expressed between COPD and control in bioinformatics analysis. The observed association between leptin and COPD in previous observational studies may be attributable to unmeasured confounding effects or reverse causation.

Respiratory diseases and obesity: special phenotype or independent events: Review

A combination of factors, including Western European eating habits, physical inactivity and genetic predisposition, lead to a dramatic increase in adipose tissue mass. A special place is occupied by abdominal obesity, in which there is an accumulation of adipose tissue in the mesentery of the small intestine and the omentum. Developing in conditions of visceral obesity, insulin resistance, dyslipidemia and systemic inflammation are one of the key components of the pathogenesis of type 2 diabetes mellitus, cardiovascular diseases, non-alcoholic fatty liver and pancreas disease, polycystic ovary disease, some forms of cancer (breast cancer, endometrial cancer, colonic and direct intestines). At the same time, the pathogenetic role of adipose tissue is not limited to its participation in the formation of the cardiometabolic continuum and oncogenesis. The most important role of metabolically active fat in the pathogenesis of many respiratory diseases is known, including bronchial asthma, obstructive sleep apnea and pulmonary hypertension. This paper presents an overview of current data on immunological, pathophysiological and clinical features of the phenotype of the combination of respiratory diseases with overweight and obesity.

Changes in Body Weight and Serum Albumin Levels in Patients Requiring Home Long-term Oxygen Therapy

Purpose: To investigate the long-term changes in body weight and serum albumin levels in patients with respiratory failure, and those with chronic heart failure, who were treated with home long-term oxygen therapy (LTOT) to understand the current status and contribute to future measures.

Methods: Patients with chronic obstructive pulmonary disease (COPD), those with interstitial pneumonia (IP), and those with chronic heart failure (CHF) undergoing home LTOT for 6 months or more between January 2011 and January 2019 were included in the study. Body weight and serum albumin levels were assessed at the start of home LTOT and at the end of the observation period, a minimum of 6 months after commencing home LTOT.

Results: Sixty-two patients (29 COPDs, 23 IPs, and 10 CHFs) were included. In COPD patients and IP patients, body weight decreased (P = 0.0017, P = 0.0018, respectively, Wilcoxon signed-rank test). Serum albumin levels decreased in IP patients (P = 0.0185) but not in COPD patients. There was neither significant decrease in body weight nor serum albumin levels in patients with CHF.

Conclusion: Chronic respiratory failure patients who have home LTOT were likely to have a decreased nutritional status. In order to provide prolonged home LTOT, medical staff need to pay close attention to the nutritional status of patients receiving home LTOT.

Serum Leptin in Hospitalized Community-Acquired Pneumonia Children under the Age of Five Years

Background

Community-acquired pneumonia (CAP) accounts for 19% of the world’s total deaths among all age groups yearly, with highest rates in children less than 5 years. This study is designed to evaluate the serum leptin level in hospitalized children under the age of 5 years with CAP.

Results

This prospective cross-sectional study included CAP children under the age of 5 years. Forty-one patients admitted to pediatric intensive care unit (PICU) and 41 patients admitted to general ward were enrolled. Patients with any other cause that may elevate serum leptin were excluded. Serum leptin was measured on the day of admission. The PICU patients had a significantly higher median serum leptin than that of the ward patients (p < 0.001). C-reactive protein (CRP) level was significantly higher in patients with elevated serum leptin than in patients with normal serum leptin (p = 0.001). There was a significant association between high serum leptin and positive sputum cultures (p < 0.001), particularly cultures growing more than one organism (p < 0.001). There was a positive, weak correlation between serum leptin and length of stay (r = 0.30, p = 0.007). Serum leptin showed good discrimination between PICU admissions and inpatient ward admissions (AUC = 0.777, p < 0.001); at a cut-off value of > 29.6 pg/ml, serum leptin had a sensitivity of 70.7% and a specificity of 87.8%

Conclusion

We may conclude that CAP patients with a serum leptin level above 29.6 pg/ml should be considered for PICU admission.

IL-26 in the induced sputum is associated with the level of systemic inflammation, lung functions and body weight in COPD patients

Background

Chronic inflammatory process is the main link in COPD pathogenesis, which causes structural changes in the respiratory tract and lungs. In overweight patients, an adipose tissue could contribute to activation of the inflammatory process. Therefore, it is highly important to identify potential biomarkers of inflammation for patients with COPD and obesity. The aim of this study was to investigate the role of interleukin-26 (IL-26) and evaluate the relationship between the level of systemic inflammation, lung function, and body mass index (BMI) in patients with COPD.

Patients and methods

Eighty-three patients with COPD in the stable condition (stage 2 according to the 2016 Global Initiative for Chronic Obstructive Lung Disease recommendations), aged 40-70 years, were included in the study. All patients were divided into 2 groups: obese (n=53) (BMI - 30.0-39.9 kg/m2) and non-obese (n=30) (BMI - 18.5-24.9 kg/m2). We conducted patients' examination, spirometry, induced the sputum, determined the level of C-reactive protein (CRP), leptin in serum and IL-26 in sputum.

Results

Obese and non-obese COPD patients had a significant increase in IL-26 compared with healthy subjects by 2.3 and 2.6 (P=0.0003). We also observed a higher level of CRP by 1.38 times (P=0.0008), compared with the rate in non-obese COPD patients, and by 1.8 times (P=0.015) higher concentration level of leptin compared with healthy subjects. The sputum IL-26 level had positive correlation with BMI, CRP, and leptin, and a negative - with forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity. Leptin level had positive correlation with BMI and CRP, and negative with FEV1, FEV1/forced vital capacity.

Conclusion

Obese COPD patients had a higher level of persistent systemic inflammation than non-obese ones, which is confirmed by a significant increase of CRP and leptin in serum. The data confirm that IL-26 can be considered as a perspective marker to detect the inflammation level in lung tissue of COPD patients.

Evaluation of plasma leptin, tumor necrosis factor-α, and prealbumin as prognostic biomarkers during clinical recovery from acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Inflammatory and nutritional biomarkers have an important bearing on outcomes of acute exacerbations of chronic obstructive pulmonary disease (AECOPD), but the temporal profile of these compounds during an acute episode is unclear.

PATIENTS AND METHODS

Plasma leptin, prealbumin, and tumor necrosis factor-alpha (TNF-α) were estimated at baseline and before hospital discharge in patients with AECOPD.

RESULTS

A total of 82 patients were evaluated (66 males; mean (standard deviation) age, 61.6 (10.1) years. Of these, 74 subjects (90.2%) were current or former smokers, with median (range) pack-years of 15 (0-96), duration of COPD of 8 years (range, 2-25 years) and duration of current symptoms being 5 days (range, 1-30 days). Majority (41.5%) had type I (severe) exacerbation. During the current episode, 46 patients (58.9%) required mechanical ventilation for a median of 6 days (range, 1-34). The median duration of hospital stay was 13 days, (range, 1-110). At discharge, significant reduction was observed in dyspnea, total leukocyte count, erythrocyte sedimentation rate (ESR), partial pressure of carbon dioxide, hemoglobin, urea, creatinine, potassium, aspartate transferase, and TNF-α levels compared to baseline, whereas arterial pH, PO₂, serum albumin, prealbumin, and leptin significantly improved. No difference was seen in leptin, prealbumin, and TNF-α between patients with mild/moderate and severe exacerbation, or between patients who required or did not require mechanical ventilation. Change in leptin correlated with body mass index and change in ESR; no associations were observed between leptin, prealbumin, and TNF-α with other clinico-laboratory variables.

CONCLUSION

Plasma levels of novel inflammatory and nutritional biomarkers, i.e., leptin, TNF-α, and prealbumin are altered in AECOPD episodes and lag behind other parameters during recovery. These biomarkers are not reliable predictors of clinical outcomes in these patients.

The role of leptin in the sporadic form of Alzheimer's disease. Interactions with the adipokines amylin, ghrelin and the pituitary hormone prolactin

Leptin (Lep) is emerging as a pivotal molecule involved in both the early events and the terminal phases of Alzheimer's disease (AD). In the canonical pathway, Lep acts as an anorexigenic factor via its effects on hypothalamic nucleus. However, additional functions of Lep in the hippocampus and cortex have been unravelled in recent years. Early events in the sporadic form of AD likely involve cellular level alterations which can have an effect on food intake and metabolism. Thus, AD can be conceivably interpreted as a multiorgan pathology that not only results in a dramatic neuronal loss in brain areas such as the hippocampus and the cortex (ultimately leading to a significant cognitive impairment) but as a disease which also affects body-weight homeostasis. According to this view, body-weight control disruptions are to be expected in both the early- and late-stage AD, concomitant with changes in serum Lep content, alterations in Lep transport across the blood-brain barrier (BBB) and Lep receptor-related signalling abnormalities. Lep is a member of the adipokine family of molecules, while the Lep receptor belongs to the class I cytokine receptors. Since cellular response to adipokine signalling can be either potentiated or diminished as a result of specific ligand-receptor interactions, Lep interactions with other members of the adipokine family including amylin, ghrelin and hormones such as prolactin require further investigation. In this review, we provide a general perspective on the functions of Lep in the brain, with a particular focus on the sporadic AD.

Nutrition and respiratory health--feature review

Diet and nutrition may be important modifiable risk factors for the development, progression and management of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). This review examines the relationship between dietary patterns, nutrient intake and weight status in obstructive lung diseases, at different life stages, from in-utero influences through childhood and into adulthood. In vitro and animal studies suggest important roles for various nutrients, some of which are supported by epidemiological studies. However, few well-designed human intervention trials are available to definitively assess the efficacy of different approaches to nutritional management of respiratory diseases. Evidence for the impact of higher intakes of fruit and vegetables is amongst the strongest, yet other dietary nutrients and dietary patterns require evidence from human clinical studies before conclusions can be made about their effectiveness.