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

Leptin and Insulin in COPD: Unveiling the Metabolic-Inflammatory Axis-A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a progressive and debilitating condition characterized by airflow limitations and systemic inflammation. The interaction between the metabolic and inflammatory pathways plays a key role in disease progression, with leptin and insulin emerging as pivotal metabolic regulators. Leptin, an adipokine that regulates energy homeostasis, and insulin, the primary regulator of glucose metabolism, are both altered in COPD patients. This narrative review provides an in-depth examination of the roles of leptin and insulin in COPD pathogenesis, focusing on the molecular mechanisms through which these metabolic regulators interact with inflammatory pathways and how their dysregulation contributes to a spectrum of extrapulmonary manifestations. These disturbances not only exacerbate COPD symptoms but also increase the risk of comorbidities such as metabolic syndrome, diabetes, cardiovascular disease, or muscle wasting. By exploring the underlying mechanisms of leptin and insulin dysregulation in COPD, this review underscores the significance of the metabolic-inflammatory axis, suggesting that restoring metabolic balance through leptin and insulin modulation could offer novel therapeutic strategies for improving clinical outcomes.

Uteroplacental insufficiency decreases leptin expression and impairs lung development in growth-restricted newborn rats

BACKGROUND

The study aimed to analyze the effect of uteroplacental insufficiency (UPI) on leptin expression and lung development of intrauterine growth restriction (IUGR) rats.

METHODS

On day 17 of pregnancy, time-dated Sprague-Dawley rats were randomly divided into either an IUGR group or a control group. Uteroplacental insufficiency surgery (IUGR) and sham surgery (control) were conducted. Offspring rats were spontaneously delivered on day 22 of pregnancy. On postnatal days 0 and 7, rats' pups were selected at random from the control and IUGR groups. Blood was withdrawn from the heart to determine leptin levels. The right lung was obtained for leptin and leptin receptor levels, immunohistochemistry, proliferating cell nuclear antigen (PCNA), western blot, and metabolomic analyses.

RESULTS

UPI-induced IUGR decreased leptin expression and impaired lung development, causing decreased surface area and volume in offspring. This results in lower body weight, decreased serum leptin levels, lung leptin and leptin receptor levels, alveolar space, PCNA, and increased alveolar wall volume fraction in IUGR offspring rats. The IUGR group found significant relationships between serum leptin, radial alveolar count, von Willebrand Factor, and metabolites.

CONCLUSION

Leptin may contribute to UPI-induced lung development during the postnatal period, suggesting supplementation as a potential treatment.

IMPACT

The neonatal rats with intrauterine growth restriction (IUGR) caused by uteroplacental insufficiency (UPI) showed decreased leptin expression and impaired lung development. UPI-induced IUGR significantly decreased surface area and volume in lung offspring. This is a novel study that investigates leptin expression and lung development in neonatal rats with IUGR caused by UPI. If our findings translate to IUGR infants, leptin may contribute to UPI-induced lung development during the postnatal period, suggesting supplementation as a potential treatment.

Obesity and Insulin Resistance in Asthma Pathogenesis and Clinical Outcomes

Common inflammatory ground links obesity, insulin resistance, and asthma. As recognition of their interplay, one worsening the natural course of the other, is recognised, questions remain about how to adequately address them altogether to improve clinical outcomes. The present manuscript sheds light on the problem, describing possible pathophysiological links, clinical views, and therapeutic challenges, raising questions about what remains to be done, and calling for multidisciplinary treatment of these patients to detect diseases early and adequately address them before they become full-blown and deteriorate their health and quality of life.

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.

Screening of Lipid Metabolism-Related Genes as Diagnostic Indicators in Chronic Obstructive Pulmonary Disease

Objective

It has been observed that local and systemic disorders of lipid metabolism occur during the development of chronic obstructive pulmonary disease (COPD), but no specific mechanism has yet been identified.

Methods

The mRNA microarray dataset GSE76925 of COPD patients was downloaded from the Gene Expression Omnibus database and screened for differentially expressed genes (DEGs). Lipid metabolism-related genes (LMRGs) were extracted from the Kyoto Encyclopedia of Genes and Genomes database and Molecular Signature Database. The DEGs were intersected with LMRGs to obtain differentially expressed lipid metabolism-related genes (DeLMRGs). GO enrichment analysis and KEGG pathway analysis were performed on DeLMRGs, and protein-protein interaction networks were constructed and screened to identify hub genes. The GSE8581 validation set and further ELISA experiments were used to validate key DeLMRG expression.

Results

Differential analysis of dataset GSE76925 identified 587 DEGs, of which 62 genes were up-regulated and 525 were down-regulated. Taking the intersection of 587 DEGs with 1102 LMRGs, 20 DeLMRGs were obtained, including 1 up-regulated gene and 19 down-regulated genes. 10 hub genes were screened by cytohubba plugin, including 9 down-regulated genes PLA2G4A, HPGDS, LEP, PTGES3, LEPR, PLA2G2D, MED21, SPTLC1 and BCHE, as well as the only up-regulated gene PLA2G7. Validation of the identified 10 DeLMRGs using the validation set GSE8581 revealed that BCHE and PLA2G7 expression levels differed between the two groups. We further constructed the ceRNA network of BCHE and PLA2G7. Cell experiments also showed that PLA2G7 expression was up-regulated and BCHE expression was down-regulated in CSE-treated RAW264.7 and THP-1 cells.

Conclusion

Based on a comprehensive bioinformatic analysis of lipid metabolism genes, we identified BCHE and PLA2G7 as potentially significant biomarkers of COPD. These biomarkers may represent promising targets for COPD diagnosis and treatment.

Obesity dysregulates the pulmonary antiviral immune response

Obesity is a well-recognized risk factor for severe influenza infections but the mechanisms underlying susceptibility are poorly understood. Here, we identify that obese individuals have deficient pulmonary antiviral immune responses in bronchoalveolar lavage cells but not in bronchial epithelial cells or peripheral blood dendritic cells. We show that the obese human airway metabolome is perturbed with associated increases in the airway concentrations of the adipokine leptin which correlated negatively with the magnitude of ex vivo antiviral responses. Exogenous pulmonary leptin administration in mice directly impaired antiviral type I interferon responses in vivo and ex vivo in cultured airway macrophages. Obese individuals hospitalised with influenza showed dysregulated upper airway immune responses. These studies provide insight into mechanisms driving propensity to severe influenza infections in obesity and raise the potential for development of leptin manipulation or interferon administration as novel strategies for conferring protection from severe infections in obese higher risk individuals.

Correlations between serum leptin levels and classical biomarkers in SARS-CoV-2 infection, in critically ill patients

BACKGROUND

Altered levels of some blood markers might be linked with the degree of severity and mortality of patients with SARS-CoV-2 infection. This study aimed to find out if there are correlations between serum leptin levels and classical biomarkers.

MATERIALS AND METHODS

We present a single-center observational cohort study on SARS-CoV-2 infected patients. The study was conducted at Infectious Diseases Clinic of Academic Emergency Hospital Sibiu, from May through November 2020. In this study, we retrospectively analyzed 54 patients, all with confirmed SARS-CoV-2 infection.

RESULTS

Our results revealed that there is a negative correlation between serum leptin and Interleukin-6 levels and a positive correlation between serum leptin and blood glucose levels. A positive correlation between ferritin and lactate dehydrogenase levels was also observed. No correlation was found between leptin and other biomarkers such as ferritin, neutrophil/lymphocyte ratio, lactate dehydrogenase, C-reactive protein, fibrinogen, erythrocyte sedimentation rate, or D-dimer.

CONCLUSIONS

Further studies need to be conducted to investigate the role of leptin in SARS-CoV-2 infection. The results of this research could contribute to the introduction of the determination of serum leptin levels in the routine evaluation of patients with critical illness.

The relationship between obstructive sleep apnea and asthma severity and vice versa: a systematic review and meta-analysis

BACKGROUND

There is a great association between the prevalence of obstructive sleep apnea (OSA) and asthma. Nonetheless, whether OSA impacts lung function, symptoms, and control in asthma and whether asthma increases the respiratory events in OSA are unknown. This meta-analysis aimed to examine the relationship between obstructive sleep apnea and asthma severity and vice versa.

METHODS

We carried out a systematic search of PubMed, EMBASE, and Scopus from inception to September 2022. Primary outcomes were lung function, parameters of polysomnography, the risk of OSA in more severe or difficult-to-control asthmatic patients, and the risk of asthma in patients with more severe OSA. Heterogeneity was examined with the Q test and I² statistics. We also performed subgroup analysis, Meta-regression, and Egger's test for bias analysis.

RESULTS

34 studies with 27,912 subjects were totally included. The results showed that the comorbidity of OSA aggravated lung function in asthmatic patients with a consequent decreased forced expiratory volume in one second %predicted (%FEV1) and the effect was particularly evident in children. %FEV1 tended to decrease in adult asthma patients complicated with OSA, but did not reach statistical significance. Interestingly, the risk of asthma seemed to be slightly lower in patients with more severe OSA (OR = 0.87, 95%CI 0.763-0.998). Asthma had no significant effect on polysomnography, but increased daytime sleepiness assessed by the Epworth Sleepiness Scale in OSA patients (WMD = 0.60, 95%CI 0.16-1.04). More severe asthma or difficult-to-control asthma was independently associated with OSA (odds ratio (OR) = 4.36, 95%CI 2.49-7.64).

CONCLUSION

OSA was associated with more severe or difficult-to-control asthma with decreased %FEV₁ in children. The effect of OSA on lung function in adult patients should be further confirmed. Asthma increased daytime sleepiness in OSA patients. More studies are warranted to investigate the effect of asthma on OSA severity and the impact of different OSA severity on the prevalence of asthma. It is strongly recommended that people with moderate-to-severe or difficult-to-control asthma screen for OSA and get the appropriate treatment.

The Effect of Serum Leptin Concentration and Leptin Receptor Expression on Colorectal Cancer

INTRODUCTION

The level of leptin in the blood shows a positive, strong correlation with the mass of adipose tissue. Being overweight and having metabolic disorders increase the risk of developing colorectal cancer.

AIM OF THE PAPER

The aim of the study was to assess the concentration of leptin in the blood serum as well as the expression of the leptin receptor in colorectal cancer cells. In addition, the effect of serum leptin concentration and leptin receptor expression on clinical and pathological parameters such as BMI, obesity, TNM, and tumor size was assessed.

METHODS

The study included 61 patients diagnosed with colorectal cancer and treated with surgery.

RESULTS

Strong leptin receptor expression and the prevalence of overweight and obesity are factors influencing the occurrence of excessive leptin concentrations.

CONCLUSION

Leptin may be involved in the development and progression of colorectal cancer. More research is needed to better elucidate the role of leptin in the development and progression of the disease.

Diet-induced obesity worsens allergen-induced type 2/type 17 inflammation in airways by enhancing DUOX1 activation

More than 50% of people with asthma in the United States are obese, and obesity often worsens symptoms of allergic asthma and impairs response to treatment. Based on previously established roles of the epithelial NADPH oxidase DUOX1 in allergic airway inflammation, we addressed the potential involvement of DUOX1 in altered allergic inflammation in the context of obesity. Intranasal house dust mite (HDM) allergen challenge of subjects with allergic asthma induced rapid secretion of IL-33, then IL-13, into the nasal lumen, responses that were significantly enhanced in obese asthmatic subjects (BMI >30). Induction of diet-induced obesity (DIO) in mice by high-fat diet (HFD) feeding similarly enhanced acute airway responses to intranasal HDM challenge, particularly with respect to secretion of IL-33 and type 2/type 3 cytokines, and this was associated with enhanced epithelial DUOX1 expression and was avoided in DUOX1-deficient mice. DIO also enhanced DUOX1-dependent features of chronic HDM-induced allergic inflammation. Although DUOX1 did not affect overall weight gain by HFD feeding, it contributed to glucose intolerance, suggesting a role in glucose metabolism. However, glucose intolerance induced by short-term HFD feeding, in the absence of adiposity, was not sufficient to alter HDM-induced acute airway responses. DIO was associated with enhanced presence of the adipokine leptin in the airways, and leptin enhanced DUOX1-dependent IL-13 and mucin production in airway epithelial cells. In conclusion, augmented inflammatory airway responses to HDM in obesity are associated with increases in airway epithelial DUOX1, and by increased airway epithelial leptin signaling.

Leptin and Asthma: What Are the Interactive Correlations?

Leptin is an adipokine directly correlated with the proinflammatory obese-associated phenotype. Leptin has been demonstrated to inhibit adipogenesis, promote fat demarcation, promote a chronic inflammatory state, increase insulin sensitivity, and promote angiogenesis. Leptin, a regulator of the immune response, is implicated in the pathology of asthma. Studies involved in the key cell reaction and animal models of asthma have provided vital insights into the proinflammatory role of leptin in asthma. Many studies described the immune cell and related cellular pathways activated by leptin, which are beneficial in asthma development and increasing exacerbations. Subsequent studies relating to animal models support the role of leptin in increasing inflammatory cell infiltration, airway hyperresponsiveness, and inflammatory responses. However, the conclusive effects of leptin in asthma are not well elaborated. In the present study, we explored the general functions and the clinical cohort study supporting the association between leptin and asthma. The main objective of our review is to address the knowns and unknowns of leptin on asthma. In this perspective, the arguments about the different faces of leptin in asthma are provided to picture the potential directions, thus yielding a better understanding of asthma development.

Contribution of obesity to breathlessness in a large nationally representative sample of Australian adults

BACKGROUND AND OBJECTIVE

Breathlessness is prevalent and associated with medical consequences. Obesity is related to breathlessness. However, the magnitude of its contribution has not been clearly documented. This investigation aimed to determine the contribution of obesity to breathlessness by estimating the population attributable fraction (PAF) in a representative sample of Australian adults.

METHODS

A cross-sectional, nationally representative survey of Australian residents aged ≥18 years was conducted in October 2019. Breathlessness was defined as modified Medical Research Council (mMRC) dyspnoea scale grade ≥2. BMI was calculated from self-reported height and weight. Adjusted relative risks (aRRs) were estimated using a generalized linear model with Poisson distribution, adjusted for age group and/or participant-reported diagnosed illnesses. Adjusted PAFs were estimated using aRR and obesity prevalence in Australian adults.

RESULTS

Among those who completed the National Breathlessness Survey, 9769 participants (51.4% female) were included in the analysis; 28.1% of participants were obese. The prevalence of breathlessness was 9.54%. The aRR of obesity for breathlessness was 2.04, adjusted for age. Adjusting for various co-morbid conditions, the aRR was slightly attenuated to around 1.85-1.98. The PAF, adjusted only for age, was 24.6% (95% CI 20.1-29.1) and after further adjustment for co-morbid conditions, the PAF ranged from 21.1% to 23.6%. Obesity accounted for a higher proportion of breathlessness in women than in men.

CONCLUSION

Our results demonstrate that obesity accounts for around a quarter of breathlessness symptoms in Australian adults. This has important implications for health policy in light of the global trend in increasing obesity.

Obesity, leptin and host defence of Streptococcus pneumoniae: the case for more human research

Pneumococcal pneumonia is the leading cause of community-acquired pneumonia. Obesity is a risk factor for pneumonia. Host factors play a critical role in susceptibility to pulmonary pathogens and outcome from pulmonary infections. Obesity impairs innate and adaptive immune responses, important in the host defence against pneumococcal disease. One area of emerging interest in understanding the complex relationship between obesity and pulmonary infections is the role of the hormone leptin. There is a substantive evidence base supporting the associations between obesity, leptin, pulmonary infections and host defence mechanisms. Despite this, there is a paucity of research that specifically focuses on Streptococcus pneumoniae (pneumococcal) infections, which are the leading cause of community-acquired pneumonia hospitalisations and mortality worldwide. Much of the evidence examining the role of leptin in relation to S. pneumoniae infections has used genetically mutated mice. The purpose of this mini review is to explore the role leptin plays in the host defence of S. pneumoniae in subjects with obesity and posit an argument for the need for more human research.

Interplay Between the Immune and Endocrine Systems in the Lung: Implications for TB Susceptibility

The role of the endocrine system on the immune response, especially in the lung, remains poorly understood. Hormones play a crucial role in the development, homeostasis, metabolism, and response to the environment of cells and tissues. Major infectious and metabolic diseases, such as tuberculosis and diabetes, continue to converge, necessitating the development of a clearer understanding of the immune and endocrine interactions that occur in the lung. Research in bacterial respiratory infections is at a critical point, where the limitations in identifying and developing antibiotics is becoming more profound. Hormone receptors on alveolar and immune cells may provide a plethora of targets for host-directed therapy. This review discusses the interactions between the immune and endocrine systems in the lung. We describe hormone receptors currently identified in the lungs, focusing on the effect hormones have on the pulmonary immune response. Altered endocrine responses in the lung affect the balance between pro- and anti-inflammatory immune responses and play a role in the response to infection in the lung. While some hormones, such as leptin, resistin and lipocalin-2 promote pro-inflammatory responses and immune cell infiltration, others including adiponectin and ghrelin reduce inflammation and promote anti-inflammatory cell responses. Furthermore, type 2 diabetes as a major endocrine disease presents with altered immune responses leading to susceptibility to lung infections, such as tuberculosis. A better understanding of these interactions will expand our knowledge of the mechanisms at play in susceptibility to infectious diseases and may reveal opportunities for the development of host-directed therapies.

Inflammation and Oxidative Stress as Common Mechanisms of Pulmonary, Autonomic and Musculoskeletal Dysfunction after Spinal Cord Injury

Simple Summary

When a spinal cord injury occurs, the neurons that regulate our voluntary movements, those involved in environment and somatic perception and those that regulate vegetative functions are affected. Once neuronal damage is established, the cells of other tissues are also affected in their functions, altering the interaction between organs and altering the proper functioning of the organism. Multiple studies in animal models, as well as in humans, have recognized as factors involved in organ damage the imbalance between the formation of highly reactive molecules called pro-oxidants and defensive mechanisms called antioxidants. Closely associated with this phenomenon, the inflammatory response is also pathologically activated. In this narrative review, we have analyzed the information involving these pathological processes at the level of the lung, the autonomic nervous system and the skeletal musculature after spinal cord injury. Knowing the abnormal functioning mechanisms that occur after a spinal cord injury not only offers a better understanding of the organic events but also offers future possibilities for therapeutic interventions that may benefit the thousands of patients suffering this pathology.

Abstract

One of the etiopathogenic factors frequently associated with generalized organ damage after spinal cord injury corresponds to the imbalance of the redox state and inflammation, particularly of the respiratory, autonomic and musculoskeletal systems. Our goal in this review was to gain a better understanding of this phenomenon by reviewing both animal and human studies. At the respiratory level, the presence of tissue damage is notable in situations that require increased ventilation due to lower thoracic distensibility and alveolar inflammation caused by higher levels of leptin as a result of increased fatty tissue. Increased airway reactivity, due to loss of sympathetic innervation, and levels of nitric oxide in exhaled air that are similar to those seen in asthmatic patients have also been reported. In addition, the loss of autonomic control efficiency leads to an uncontrolled release of catecholamines and glucocorticoids that induce immunosuppression, as well as a predisposition to autoimmune reactions. Simultaneously, blood pressure regulation is altered with vascular damage and atherogenesis associated with oxidative damage. At the muscular level, chronically elevated levels of prooxidants and lipoperoxidation associated with myofibrillar atrophy are described, with no reduction or reversibility of this process through antioxidant supplementation.

Leptin in the Respiratory Tract: Is There a Role in SARS-CoV-2 Infection?

Leptin is a pleiotropic adipocytokine involved in several physiologic functions, with a known role in innate and adaptive immunity as well as in tissue homeostasis. Long- and short-isoforms of leptin receptors are widely expressed in many peripheral tissues and organs, such as the respiratory tract. Similar to leptin, microbiota affects the immune system and may interfere with lung health through the bidirectional crosstalk called the “gut-lung axis.” Obesity leads to impaired protective immunity and altered susceptibility to pulmonary infections, as those by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although it is known that leptin and microbiota link metabolism and lung health, their role within the SARS-CoV2 coronavirus disease 2019 (COVID-19) deserves further investigations. This review aimed to summarize the available evidence about: (i) the role of leptin in immune modulation; (ii) the role of gut microbiota within the gut-lung axis in modulating leptin sensitivity; and (iii) the role of leptin in the pathophysiology of COVID-19.

Plasma Leptin Is Increased in Intensive Care Patients with COVID-19-An Investigation Performed in the PronMed-Cohort

COVID-19 has shaken the world and intensive care units (ICU) have been challenged by numerous patients suffering from a previously unknown disease. Leptin is a polypeptide pleiotropic hormone, mainly expressed by adipocytes. It acts as a proinflammatory cytokine and is associated with several conditions, known to increase the risk of severe COVID-19. Very little is known about leptin in severe viral disorders. Plasma leptin was analyzed in 222 out of 229 patients with severe COVID-19 on admission to an ICU at Uppsala University Hospital, a tertiary care hospital in Sweden, and compared to plasma leptin in 25 healthy blood donors. COVID-19 was confirmed by positive PCR. Leptin levels were significantly higher in patients with COVID-19 (18.3 ng × mL⁻¹; IQR = 30.4), than in healthy controls (7.8 ng × mL⁻¹; IQR = 6.4). Women had significantly higher leptin values (22.9 ng × mL⁻¹; IQR = 29.8) than men (17.5 ng × mL⁻¹; IQR = 29.9). Mortality at 30 days was 23% but was not associated with increased leptin levels. Neither median duration of COVID-19 before admission to ICU (10 days; IQR = 4) or median length of ICU stay (8 days; IQR = 11) correlated with the plasma leptin levels. Leptin levels in COVID-19 were higher in females than in males. Both treatment (e.g., use of corticosteroids) and prophylaxis (vaccines) have been improved since the start of the COVID-19 pandemic, which may contribute to some difficulties in deciphering relations between COVID-19 and leptin.

Regulatory Peptides in Asthma

Numerous regulatory peptides play a critical role in the pathogenesis of airway inflammation, airflow obstruction and hyperresponsiveness, which are hallmarks of asthma. Some of them exacerbate asthma symptoms, such as neuropeptide Y and tachykinins, while others have ameliorating properties, such as nociception, neurotensin or β-defensin 2. Interacting with peptide receptors located in the lungs or on immune cells opens up new therapeutic possibilities for the treatment of asthma, especially when it is resistant to available therapies. This article provides a concise review of the most important and current findings regarding the involvement of regulatory peptides in asthma pathology.

Serum leptin level as a diagnostic and prognostic marker in infectious diseases and sepsis: A comprehensive literature review

BACKGROUND

Infections and sepsis are common causes of morbidity and mortality, with an increasing incidence worldwide. Leptin is involved in the inflammatory process and may modulate the cytokine production, immune cell proliferation and endothelial function. There are conflicting results regarding alterations of leptin levels in infectious diseases and the outcome from sepsis.The aim of the current article is to provide an overview of the medical literature on the correlations between variations of leptin levels and infectious diseases and sepsis.

METHODS

We performed an extensive literature search in PubMed and Google Scholar databases, using keywords to identify articles related to leptin in infectious diseases and sepsis. Searches were referenced using medical subject headings that included "leptin," "adipokines," "sepsis," "infectious diseases," "leptin deficiency," "leptin resistance" or "hyperleptinemia." The language of publication, journal, or country were not included as limitation criteria.Articles or abstracts containing adequate information, such as age, sex, anthropometric indices, clinical presentation, comorbidities, and management were included in the study, whereas articles with insufficient clinical and demographic data were excluded. We assessed the quality of the studies selected.The final review of all databases was conducted on June 18, 2020.

RESULTS

We find the results from the current review to be of great importance due to the possible therapeutic role of leptin analogs in states of leptin deficiency associated with infectious diseases or sepsis.In hyperleptinemia, a therapeutic plan for obtaining leptin neutralization also needs further investigations. This could lead to the reduction of proinflammatory responses.There is a need for further studies to demonstrate the specificity and sensitivity of leptin in the early diagnosis of sepsis and the need to measure serum leptin levels in routine evaluation of the critical patient.

CONCLUSION

The multiple effects of leptin are of growing interest, but further studies are needed to elucidate the role of leptin signalling in infectious diseases and sepsis. Because very few human studies are reported, we recommend the need for further research.Better understanding of the pathophysiology of sepsis and the implication of circulating total leptin in this process could help physicians in managing this life-threatening condition.

Contribution of comorbidities to obesity-related asthma in children

Children with obesity are at increased risk for developing asthma that is difficult to control. A complicating factor to asthma management among these children is likely the commonplace co-morbidities that also result from obesity. We discuss three common obesity-related comorbidities which appear to complicate the effective management of asthma, including hypovitaminosis D, obstructive sleep apnea and gastro-esophageal reflux. Each conditions requires more research to understand their effects on asthma management.

Obesity, Nutrients and the Immune System in the Era of COVID-19

The past year has shown that obesity is a risk factor for severe complications of SARS-CoV-2 infection. Excess fat mass during obesity is known to be a risk factor for chronic diseases but also for severe infections and infectious complications. We have focused here on the elements responsible for this particular susceptibility to infections and more specifically to COVID-19. Excess fat is, in itself, responsible for alterations of the immune system by disrupting the production and function of immune cells. Indeed, hypertrophic adipocytes produce more pro-inflammatory adipokines (including cytokines). The increase in their apoptosis induces a release of pro-inflammatory compounds into the circulation and a recruitment of pro-inflammatory macrophages into the adipose tissue. A chronic systemic inflammatory state is then observed. In addition, diet, apart from its role in the development of adipose tissue, can also affect the immune system, with excess simple sugars and saturated fats exerting pro-inflammatory effects. This inflammation, the adipokines released by the adipocytes, and the infiltration of lipids into the lymphoid organs affects the production of immune cells and, directly, the functions of these cells. The alteration of the immune system increases the risk of infection as well as complications, including secondary bacterial infections and septic states, and increases infection-related mortality. During COVID-19, the chronic inflammatory state promotes the cytokine shock, characteristic of severe forms, caused in particular by excessive activation of the NLRP3 inflammasome. Furthermore, in obese subjects, the already present endothelial dysfunction will render endothelial inflammation (endotheliitis) due to viral infiltration all the more severe. Added to this is a state of hypercoagulability and a decrease in respiratory capacity, leading to a risk of severe COVID-19 with cardiovascular complications, acute respiratory distress syndrome, and disseminated intravascular coagulation, which can lead to multiple organ failure and even death.

PPAR Gamma: From Definition to Molecular Targets and Therapy of Lung Diseases

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily that regulate the expression of genes related to lipid and glucose metabolism and inflammation. There are three members: PPARα, PPARβ or PPARγ. PPARγ have several ligands. The natural agonists are omega 9, curcumin, eicosanoids and others. Among the synthetic ligands, we highlight the thiazolidinediones, clinically used as an antidiabetic. Many of these studies involve natural or synthetic products in different pathologies. The mechanisms that regulate PPARγ involve post-translational modifications, such as phosphorylation, sumoylation and ubiquitination, among others. It is known that anti-inflammatory mechanisms involve the inhibition of other transcription factors, such as nuclear factor kB(NFκB), signal transducer and activator of transcription (STAT) or activator protein 1 (AP-1), or intracellular signaling proteins such as mitogen-activated protein (MAP) kinases. PPARγ transrepresses other transcription factors and consequently inhibits gene expression of inflammatory mediators, known as biomarkers for morbidity and mortality, leading to control of the exacerbated inflammation that occurs, for instance, in lung injury/acute respiratory distress. Many studies have shown the therapeutic potentials of PPARγ on pulmonary diseases. Herein, we describe activities of the PPARγ as a modulator of inflammation, focusing on lung injury and including definition and mechanisms of regulation, biological effects and molecular targets, and its role in lung diseases caused by inflammatory stimuli, bacteria and virus, and molecular-based therapy.

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.

Systematic review of marine-derived omega-3 fatty acid supplementation effects on leptin, adiponectin, and the leptin-to-adiponectin ratio

Increasing evidence suggests that adipokines, leptin and adiponectin, produced and secreted by adipocytes, are involved in regulating systemic inflammation and may be important targets for interventions to reduce the chronic systemic inflammation linked to some conditions common in aging (e.g., atherosclerosis). Lower leptin levels and higher adiponectin levels in peripheral circulation have been associated with less systemic inflammation. While some studies have shown that marine-derived omega-3 fatty acids (eicosapentaenoic acid [EPA] and/or docosahexaenoic acid [DHA]) have effects on leptin and adiponectin in the context of inflammation, the extent of their effects remain unclear. The purpose of this systematic review was to summarize findings from randomized, controlled trials that measured effects of EPA+DHA supplementation on circulating levels of leptin and adiponectin to determine the state of the science. PubMed, CINAHL, Web of Science, Scopus, and Cochrane Trials were searched up to June 2018 for studies meeting inclusion criteria. Thirty-one studies included in this review were conducted in 16 countries. Eighteen studies reported lower leptin and/or higher adiponectin levels with EPA+DHA supplementation versus placebo at study end point (9 reported statistically significant differences), but doses, supplementation duration, and population characteristics varied across studies. In 9 studies reporting significantly lower leptin and/or higher adiponectin levels the EPA+DHA dose was 0.52 to 4.2 g/day for 4 to 24 weeks. Additional studies are warranted which assess dose parameters and patient populations similar to studies reporting significant effects of EPA+DHA on leptin or adiponectin in order to evaluate the extent of reproducibility before recommending EPA+DHA as a therapy to target these adipokines.

Leptin induces a contracting effect on guinea pig tracheal smooth muscle via the Ob-R receptor mechanism: novel evidence

The purpose of this study was to explore the potential contracting effect of leptin on isolated guinea pig tracheal smooth muscle (TSM), the possible mechanism, and the impact of epithelium denudation or allergen sensitization, respectively. An in vitro experiment investigated the effect of leptin at a concentration of 250-1000 nmol/L on isolated guinea pig TSM with an intact or denuded epithelium. Ovalbumin and IgE were used to test the impact of active and passive sensitization. The isolated TSM strips were incubated in Krebs solution and aerated with carbogen (95% O₂ and 5% CO₂) via an automated tissue organ bath system (n = 4 for each group). Isometric contractions were recorded digitally using iox2 data acquisition software. The possible mechanism of leptin-induced TSM contraction was examined by preincubation with leptin receptor (Ob-R) antagonist. Leptin had significant concentration-dependent contraction effects on guinea pig TSM (p < 0.05). Epithelium denuding and active or passive sensitization significantly increased the potency of the leptin. Preincubation with a leptin receptor (Ob-R) antagonist significantly reduced the contraction effects, suggesting an Ob-R-mediated mechanism. Leptin had a contracting effect on airway smooth muscles potentiated by either epithelium denuding or sensitization, and the Ob-R mechanism was a possible effect mediator.

Leptin contributes to the taxol chemoresistance in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is a gynecological malignancy with high morbidity. Treating EOC remains a challenge, as the pathogenesis of this disease remains unclear and chemoresistance is a common occurrence. A number of previous studies have revealed that obesity is closely associated with cancer and leptin, as a link between cancer and obesity, has become a focus of research in recent years. In the present study, survival database analysis demonstrated that leptin expression was associated with poor prognoses in patients treated with platinum and paclitaxel/docetaxel. A cell activity assay demonstrated that leptin reduced the chemosensitivity of ovarian cancer cells to paclitaxel/docetaxel. Furthermore, flow cytometry results revealed that treatment with exogenous leptin reduced the proportion of ovarian cancer cells in G2/M phase, which was significantly elevated following paclitaxel/docetaxel chemotherapy. It was also verified that transcription factor CCAAT/Enhancer Binding Protein α can bind to the upstream promoter region of leptin and activate its transcription in ovarian cancer cells. Together, these results suggest that leptin serves an important role in chemoresistance and may serve as a novel therapeutic target for ovarian cancer in patients treated with platinum and paclitaxel chemotherapy.

Notch-1 decreased expression contributes to leptin receptor downregulation in nasal epithelium from allergic turbinates

BACKGROUND

Allergic rhinitis is characterized by a remodeling of nasal epithelium. Since the Notch and TGF-β signaling pathways are known to be involved in cell differentiation and remodeling processes and leptin adipokine has already been identified as a marker for homeostasis in human bronchial and nasal epithelial cells of asthmatics, roles played by these pathways have been investigated for chronic allergic rhinitis.

METHODS

The leptin/leptin receptor expression has been investigated in a study with 40 biopsies from allergic (AR, n = 18) and non-allergic (C, n = 22) inferior turbinates, using immunohistochemistry, immunofluorescence staining and RT-PCR. In addition, extracts from in vitro samples prepared from primary cells of inferior turbinates as well as in vitro cultured human nasal epithelial RPMI 2650 cells (ATCC-CCL-30) were also tested for leptin expression and activation of the Notch-1 pathway.

RESULTS

With regards to AR, in vivo expression levels of both leptin and its receptor significantly decreased in comparison to C. Furthermore, leptin receptor mRNA was significantly reduced in AR as compared to C. Immunofluorescence showed an apparent co-expression of leptin receptor with Notch-1, which was not seen with TGF-β. In vitro, in primary turbinate epithelial cells, the expression of leptin receptor and Notch-1 significantly decreased in AR as compared to C. Moreover, in RPMI 2650 cells, leptin receptor expression was shown to be induced by Notch-1 ligand signaling.

CONCLUSION

Thus, both the leptin and Notch-1 pathways appear to represent markers for epithelial homeostasis in allergic rhinitis.

Leptin Functions in Infectious Diseases

Leptin, a pleiotropic protein has long been recognized to play an important role in the regulation of energy homeostasis, metabolism, neuroendocrine function, and other physiological functions through its effects on the central nervous system (CNS) and peripheral tissues. Leptin is secreted by adipose tissue and encoded by the obese (ob) gene. Leptin acts as a central mediator which regulates immunity as well as nutrition. Importantly, leptin can modulate both innate and adaptive immune responses. Leptin deficiency/resistance is associated with dysregulation of cytokine production, increased susceptibility toward infectious diseases, autoimmune disorders, malnutrition and inflammatory responses. Malnutrition induces a state of immunodeficiency and an inclination to death from communicable diseases. Infectious diseases are the disease of poor who invariably suffer from malnutrition that could result from reduced serum leptin levels. Thus, leptin has been placed at the center of many interrelated functions in various pathogenic conditions, such as bacterial, viruses and parasitic infections. We review herein, the recent advances on the role of leptin in malnutrition in pathogenesis of infectious diseases with a particular emphasis on parasitic diseases such as Leishmaniasis, Trypanosomiasis, Amoebiasis, and Malaria.

Obesity and Metabolic Abnormalities in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) and obesity are major causes of morbidity and mortality worldwide, and a relationship between COPD and obesity is increasingly recognized. The nature and underlying mechanisms of the link between obesity and COPD are still largely unknown. Obesity, and abdominal adiposity in particular, is linked to metabolic syndrome. Hypertension, hyperglycemia, and abdominal adiposity seem to be the most prevalent components of metabolic syndrome in COPD. Adipose tissues function as a source of a variety of signaling molecules in the pathobiology of respiratory diseases. Computed tomography allows measurement of various fat depots and allows better understanding of the impact of abdominal visceral fat in the pathophysiology of COPD. Innovative statistical methodology has identified obesity as a relevant and distinguishing characteristic in patients with COPD. Integrated research combining COPD and its multimorbidity network may unravel underlying endotypes to direct future interventions in this specific COPD cluster.

Aerobic exercise inhibits obesity-induced respiratory phenotype

PURPOSE

Obesity results in decreased lung function and increased inflammation. Moderate aerobic exercise (AE) reduced lung inflammation and remodeling in a variety of respiratory disease models. Therefore, this study investigated whether AE can attenuate a diet-induced obesity respiratory phenotype; including airway hyper-responsiveness (AHR), remodeling and inflammation.

METHODS

Sixty C57Bl/6 male mice were distributed into four groups: control lean (CL), exercise lean (EL), obese (O) and obese exercise (OE) groups (2 sets of 7 and 8 mice per group; n = 15). A classical model of diet-induced obesity (DIO) over 12 weeks was used. AE was performed 60 min/day, 5 days/week for 5 weeks. Airway hyperresponsiveness (AHR), lung inflammation and remodeling, adipokines and cytokines in bronchoalveolar lavage (BAL) was determined.

RESULTS

A high fat diet over 18 weeks significantly increased body weight (p < .0001). Five weeks of AE significantly reduced both AHR and pulmonary inflammation. AHR in obese mice that exercised was reduced at the basal level (p < .05), vehicle (PBS) (p < .05), 6.25 MCh mg/mL (p < .05), 12.5 MCh mg/mL (p < .01), 25 MCh mg/mL (p < .01) and 50 MCh mg/mL (p < .05). Collagen (p < .001) and elastic (p < .001) fiber deposition in airway wall and also smooth muscle thickness (p < .001) were reduced. The number of neutrophils (p < .001), macrophages (p < .001) and lymphocytes (p < .01) were reduced in the peribronchial space as well as in the BAL: lymphocytes (p < .01), macrophages (p < .01), neutrophils (p < .001). AE reduced obesity markers leptin (p < .001), IGF-1 (p < .01) and VEGF (p < .001), while increased adiponectin (p < .01) in BAL. AE also reduced pro-inflammatory cytokines in the BAL: IL-1β (p < .001), IL-12p40 (p < .001), IL-13 (p < .01), IL-17 (p < .001, IL-23 (p < .05) and TNF-alpha (p < .05), and increased anti-inflammatory cytokine IL-10 (p < .05).

CONCLUSIONS

Aerobic exercise reduces high fat diet-induced obese lung phenotype (AHR, pulmonary remodeling and inflammation), involving anti-inflammatory cytokine IL-10 and adiponectin.

Obesity and risk of respiratory tract infections: results of an infection-diary based cohort study

BACKGROUND

Respiratory tract infections (RTIs) are a major morbidity factor contributing largely to health care costs and individual quality of life. The aim of the study was to test whether obesity (BMI ≥ 30 kg/m2) is one of the risk factors underlying frequent RTIs in the German adult population.

METHODS

We recruited 1455 individuals between 18 to 70 years from a cross-sectional survey on airway infections in Germany and invited them to self-report in diaries incident RTIs experienced during three consecutive winter/spring seasons. RTIs reported in these 18 months and summary measures adding-up individual RTIs were the outcomes of interest.

RESULTS

Compared to individuals with normal weight, obese individuals reported a consistently higher frequency of upper and lower RTIs and predominantly fell in the upper 10% group of a diary sumscore adding-up 10 different RTI symptoms over time. Obesity was associated both with lower RTIs (adjustedOR = 2.02, 95%CI = 1.36-3.00) and upper RTIs (adjustedOR = 1.55, 95%CI = 1.22-1.96). Adjusting for demographic and lifestyle variables did only marginally affect ORs. Stratified analyses suggested a stronger association for women and effect modifications by sports activity and dietary habits.

CONCLUSIONS

We confirm the association of obesity with infection burden and present evidence for putative interaction with sports activity and dietary patterns.

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.

Serum and exhaled breath condensate leptin levels in asthmatic and obesity children: a pilot study

BACKGROUND

Recent studies have highlighted the possible involvement of leptin in inflammation. The leptin receptor is also expressed by alveolar macrophages, T lymphocytes and bronchial epitelial cells, suggesting a possible role in the cascade of airway inflammation.

OBJECTIVES

The aim of the study was to evaluate the levels of leptin in exhaled breath condensate (EBC) from asthmatic, normal- and overweight children, in relationship with airway inflammation.

METHODS

15 asthmatic non-obese children, 15 healthy non-asthmatic non-obese children, 11 obese children with asthma (OA) and 20 obese children without asthma (ONA) were enrolled. Body impedance of body weight, EBC collection, FeNO, spirometry and a blood sampling for serum leptin were assessed.

RESULTS

Leptin EBC levels were significantly higher (3.9 ng ml^-1 ± 1.3) in overweight children than those obese with asthma (3.6 ng ml^-1 ± 1.6; p = 0.97), non-owerweight asthmatics (2.2 ng ml^-1 ± 1.2; p < 0.0001) and in healthy children (0.9 ng ml^-1 ± 0.6; p < 0.001). Leptin EBC levels in asthmatic children were significantly higher than in healthy children (p = 0.05). Leptin serum levels were significantly higher in the overweight children compared with the asthmatics (12.7 ng ml^-1 ± 13.2; p < 0.001) and the healthy group (11.1 ng ml^-1 ± 11.2; p < 0.001). We observed a significant correlation between EBC-leptin levels and the serum-leptin levels (p = 0.001). No correlations were found between EBC-leptin levels, FeNO and lung function.

CONCLUSIONS

This study shows that leptin is measurable in EBC in children and that EBC-leptin levels are significantly higher in the obese subjects and in asthmatic ones compared with healthy subjects. Leptin may therefore represent a non-invasive marker of non-specific airway inflammation in children.

Plasma Leptin and Reduced FEV1 and FVC in Chronic Spinal Cord Injury

BACKGROUND

Adipose tissue produces leptin, which is pro-inflammatory, and adiponectin, which has anti-inflammatory properties. Participants with chronic spinal cord injury (SCI) have increased body fat and are at increased risk for respiratory illness.

OBJECTIVE

To assess the associations between leptin and adiponectin with pulmonary function in a chronic SCI cohort.

DESIGN

Cross-sectional study.

SETTING

Veterans Affairs Medical Center.

PARTICIPANTS

A total of 285 participants (237 men and 48 women) with chronic SCI with mean (standard deviation) injury duration 17.8 (13.2) years from the VA Boston and the community participating in an epidemiologic study assessing factors associated with respiratory health.

METHODS

Participants (24.6% cervical American Spinal Injury Association Impairment Scale (AIS) level A, B, and C; 33.6% other AIS A, B, and C; 41.8% AIS D) provided a blood sample, completed a respiratory health questionnaire, and underwent spirometry. Linear regression methods were used to assess cross-sectional associations between plasma leptin and adiponectin with spirometric measures of pulmonary function adjusted for age, race, gender, and height. Level and severity of SCI, mobility mode, body mass index, smoking, chronic obstructive pulmonary disease, asthma, chest injury history, laboratory batch, and other potential confounders were also considered.

MAIN OUTCOME MEASUREMENTS

forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC.

RESULTS

There was a statistically significant inverse relationship between plasma leptin assessed in quartiles or as a continuous covariate with FEV₁ and FVC. In fully adjusted models, each interquartile range (16,214 pg/mL) increase in leptin was associated with a significant decrease in FEV₁ (-93.1 mL; 95% confidence interval = -166.2, -20.0) and decrease in FVC (-130.7 mL; 95% confidence interval = -219.4, -42.0). There were no significant associations between leptin and FEV₁/FVC or between plasma adiponectin with FEV₁, FVC, or FEV₁/FVC.

CONCLUSION

Plasma leptin in individuals with chronic SCI is inversely associated with FEV₁ and FVC, independently of SCI level and severity and other covariates. This finding suggests that plasma leptin may contribute to reduced pulmonary function in chronic SCI.

LEVEL OF EVIDENCE

II.

Immunomodulatory effects of anesthetics in obese patients

Anesthesia and surgery have an impact on inflammatory responses, which influences perioperative homeostasis. Inhalational and intravenous anesthesia can alter immune-system homeostasis through multiple processes that include activation of immune cells (such as monocytes, neutrophils, and specific tissue macrophages) with release of pro- or anti-inflammatory interleukins, upregulation of cell adhesion molecules, and overproduction of oxidative radicals. The response depends on the timing of anesthesia, anesthetic agents used, and mechanisms involved in the development of inflammation or immunosuppression. Obese patients are at increased risk for chronic diseases and may have the metabolic syndrome, which features insulin resistance and chronic low-grade inflammation. Evidence has shown that obesity has adverse impacts on surgical outcome, and that immune cells play an important role in this process. Understanding the effects of anesthetics on immune-system cells in obese patients is important to support proper selection of anesthetic agents, which may affect postoperative outcomes. This review article aims to integrate current knowledge regarding the effects of commonly used anesthetic agents on the lungs and immune response with the underlying immunology of obesity. Additionally, it identifies knowledge gaps for future research to guide optimal selection of anesthetic agents for obese patients from an immunomodulatory standpoint.

In obese mice, exercise training increases 11β-HSD1 expression, contributing to glucocorticoid activation and suppression of pulmonary inflammation

Exercise training is advocated for treating chronic inflammation and obesity-related metabolic syndromes. Glucocorticoids (GCs), the anti-inflammatory hormones, are synthesized or metabolized in extra-adrenal organs. This study aims to examine whether exercise training affects obesity-associated pulmonary inflammation by regulating local GC synthesis or metabolism. We found that sedentary obese (ob/ob) mice exhibited increased levels of interleukin (IL)-1β, IL-18, monocyte chemotactic protein (MCP)-1, and leukocyte infiltration in lung tissues compared with lean mice, which was alleviated by 6 wk of exercise training. Pulmonary corticosterone levels were decreased in ob/ob mice. Exercise training increased pulmonary corticosterone levels in both lean and ob/ob mice. Pulmonary corticosterone levels were negatively correlated with IL-1β, IL-18, and MCP-1. Immunohistochemical staining of the adult mouse lung sections revealed positive immunoreactivities for the steroidogenic acute regulatory protein, the cholesterol side-chain cleavage enzyme (CYP11A1), the steroid 21-hydroxylase (CYP21), 3β-hydroxysteroid dehydrogenase (3β-HSD), and type 1 and type 2 11β-hydroxysteroid dehydrogenase (11β-HSD) but not for 11β-hydroxylase (CYP11B1). Exercise training significantly increased pulmonary 11β-HSD1 expression in both lean and ob/ob mice. In contrast, exercise training per se had no effect on pulmonary 11β-HSD2 expression, although pulmonary 11β-HSD2 levels in ob/ob mice were significantly higher than in lean mice. RU486, a glucocorticoid receptor antagonist, blocked the anti-inflammatory effects of exercise training in lung tissues of obese mice and increased inflammatory cytokines in lean exercised mice. These findings indicate that exercise training increases pulmonary expression of 11β-HSD1, thus contributing to local GC activation and suppression of pulmonary inflammation in obese mice.NEW & NOTEWORTHY Treadmill training leads to a significant increase in pulmonary corticosterone levels in ob/ob mice, which is in parallel with the favorable effects of exercise on obesity-associated pulmonary inflammation. Exercise training increases pulmonary 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) expression but has no significant effect on 11β-HSD2 expression in both lean and ob/ob mice. These findings indicate that exercise training increases pulmonary expression of 11β-HSD1, thus contributing to local glucocorticoid activation and suppression of pulmonary inflammation in obese mice.

Sex differences in the association between neck circumference and asthma

INTRODUCTION

The association between obesity and asthma control/quality of life commonly relies on body mass index (BMI) as the anthropomorphic measure. Due to limitations of BMI and the existence of alternative measures, such as neck circumference (NC), we examined the association between NC and asthma control/quality of life, with particular attention to male-female differences.

MATERIALS AND METHODS

The AsthMaP-2 Project is an observational study of youth with physician-diagnosed asthma. NC was stratified according to age- and sex-specific cutoffs and associated with asthma control (via Asthma Control Test [ACT]) and quality of life (via Integrated Therapeutics Group [ITG]-Asthma Short Form).

RESULTS

The mean ± SD age was 11.9 ± 3.6 years, and 53% were male (N = 116). The mean BMI percentile was at the 71 ± 28 percentile. Thirty-one participants (27%) met criteria for high NC. Males with high NC had significantly worse asthma control (P = 0.02) and lower quality of life than those with low NC. No similar association was found for females and the proportion of variability in ACT and ITG was best explained by BMI percentile. Conversely, for males, the proportion of variability in these scores explained by NC was larger than BMI percentile alone (Cohen's f(2)  = 0.04-0.09, a small to medium effect size).

DISCUSSION

Among male youth with asthma, combined use of NC and BMI percentile explained asthma control and quality of life better than BMI alone. Future studies of asthma should include measurement of NC and other anthropogenic measures of regional adiposity to clarify sex differences in asthma. Pediatr Pulmonol. 2016; 51:893-900. © 2016 Wiley Periodicals, Inc.

Emerging Comorbidities in Adult Asthma: Risks, Clinical Associations, and Mechanisms

Asthma is a heterogeneous disease with many phenotypes, and age at disease onset is an important factor in separating the phenotypes. Most studies with asthma have been performed in patients being otherwise healthy. However, in real life, comorbid diseases are very common in adult patients. We review here the emerging comorbid conditions to asthma such as obesity, metabolic syndrome, diabetes mellitus type 2 (DM2), and cardiac and psychiatric diseases. Their role as risk factors for incident asthma and whether they affect clinical asthma are evaluated. Obesity, independently or as a part of metabolic syndrome, DM2, and depression are risk factors for incident asthma. In contrast, the effects of comorbidities on clinical asthma are less well-known and mostly studies are lacking. Cross-sectional studies in obese asthmatics suggest that they may have less well controlled asthma and worse lung function. However, no long-term clinical follow-up studies with these comorbidities and asthma were identified. These emerging comorbidities often occur in the same multimorbid adult patient and may have in common metabolic pathways and inflammatory or other alterations such as early life exposures, systemic inflammation, inflammasome, adipokines, hyperglycemia, hyperinsulinemia, lung mechanics, mitochondrial dysfunction, disturbed nitric oxide metabolism, and leukotrienes.

Advances in asthma pathophysiology: stepping forward from the Maurizio Vignola experience

Maurizio Vignola was a superb and innovative researcher, who wrote seminal papers on the biology of airway epithelium in asthma. Inflammation and remodelling were the main topics of his research, mostly conducted in biopsy specimens from patients with asthma of variable severity, encompassing the entire spectrum of the disease from mild to severe asthma. His observations contributed to define the biology of asthma as we know it today, and opened the way to the personalised treatment of asthma. His group has successfully continued to investigate the biology and clinical aspects of bronchial asthma, with major interest in the clinical use of biomarkers to monitor disease activity, and in the development of new therapeutic perspectives. This review summarises the latest work on these topics proudly conducted by Maurizio's closest collaborators. The results indicate significant progress in our understanding of asthma in the last 10 years, in particular increased knowledge of the complex interaction between inflammatory and remodelling pathways, improved recognition of biological and clinical asthma phenotypes, and development of new treatment strategies, especially for patients with severe corticosteroid-resistant asthma.

Biomarkers may help to define disease phenotypes and new treatment strategies for asthmahttp://ow.ly/G2Fl6

Phenotypes, Risk Factors, and Mechanisms of Adult-Onset Asthma

Asthma is a heterogeneous disease with many phenotypes, and age at disease onset is an important factor in separating the phenotypes. Genetic factors, atopy, and early respiratory tract infections are well-recognized factors predisposing to childhood-onset asthma. Adult-onset asthma is more often associated with obesity, smoking, depression, or other life-style or environmental factors, even though genetic factors and respiratory tract infections may also play a role in adult-onset disease. Adult-onset asthma is characterized by absence of atopy and is often severe requiring treatment with high dose of inhaled and/or oral steroids. Variety of risk factors and nonatopic nature of adult-onset disease suggest that variety of mechanisms is involved in the disease pathogenesis and that these mechanisms differ from the pathobiology of childhood-onset asthma with prevailing Th2 airway inflammation. Recognition of the mechanisms and mediators that drive the adult-onset disease helps to develop novel strategies for the treatment. The aim of this review was to summarize the current knowledge on the pathogenesis of adult-onset asthma and to concentrate on the mechanisms and mediators involved in establishing adult-onset asthma in response to specific risk factors. We also discuss the involvement of these mechanisms in the currently recognized phenotypes of adult-onset asthma.

Obesity-induced adipokine imbalance impairs mouse pulmonary vascular endothelial function and primes the lung for injury

Obesity is a risk factor for the development of acute respiratory distress syndrome (ARDS) but mechanisms mediating this association are unknown. While obesity is known to impair systemic blood vessel function, and predisposes to systemic vascular diseases, its effects on the pulmonary circulation are largely unknown. We hypothesized that the chronic low grade inflammation of obesity impairs pulmonary vascular homeostasis and primes the lung for acute injury. The lung endothelium from obese mice expressed higher levels of leukocyte adhesion markers and lower levels of cell-cell junctional proteins when compared to lean mice. We tested whether systemic factors are responsible for these alterations in the pulmonary endothelium; treatment of primary lung endothelial cells with obese serum enhanced the expression of adhesion proteins and reduced the expression of endothelial junctional proteins when compared to lean serum. Alterations in pulmonary endothelial cells observed in obese mice were associated with enhanced susceptibility to LPS-induced lung injury. Restoring serum adiponectin levels reversed the effects of obesity on the lung endothelium and attenuated susceptibility to acute injury. Our work indicates that obesity impairs pulmonary vascular homeostasis and enhances susceptibility to acute injury and provides mechanistic insight into the increased prevalence of ARDS in obese humans.

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.

The many faces of asthma in obesity

Obesity is a major risk factor for the development of asthma, and causes severe, uncontrolled disease that responds poorly to therapy. The obese state alters early onset allergic asthma, and leads to the development of a novel form of late onset asthma secondary to obesity. The presentation of early onset allergic asthma is altered through effects on immune function. Factors such as mechanical loading, effects of adipokines on airways, altered diet, insulin resistance and altered metabolism of nitric oxide likely all contribute to increased airway reactivity in obesity, causing late onset asthma in obesity. Obesity also alters responses to environmental factors such as ozone and particulate matter. Focused studies to understand the importance of these factors in the pathogenesis of airway disease in obesity will be essential to develop therapies to intervene in this new epidemic of airway disease.

Fluticasone furoate maintains epithelial homeostasis via leptin/leptin receptor pathway in nasal cells

Leptin is involved in the lung epithelial homeostasis. Its role in the nasal tract is largely unknown. Allergic rhinitis (AR) is induced by the allergen exposure leading to consequential structural abnormalities in the nasal epithelium. Topical corticosteroids are recommended as first-line therapy in AR. Parietaria pollen is one of the most important allergenic sources in the southern Europe. In vitro, in human nasal epithelial cell line RPMI 2650, we aimed to determine whether allergen stimulation acts on leptin/leptin receptor pathway and how fluticasone furoate (FF) influences this pathway. The effects of the major allergen recombinant Par j 1 (rPar j 1), of FF, of leptin, and of TGF-β1 on cell proliferation, on leptin/leptin receptor expression and modulation (by clonogenic test, by RT-q-RT-PCR, by immunocytochemistry and by flow-cytometry), and on STAT-3 activation (assessing nuclear translocation by western blot analysis) were assessed. We found that rPar j 1 and TGF-β1 significantly decreased cell proliferation and down-regulated the leptin/leptin receptor pathway, whereas FF and leptin reverted them, both alone and in combination. Furthermore, rPar j 1 reduced, while leptin and FF increased STAT-3 activation. In conclusion, FF and leptin itself are able to preserve nasal epithelial homeostasis restoring the leptin/leptin receptor pathway altered by rPar j 1 exposure.

Scleroderma-related lung disease: are adipokines involved pathogenically?

Scleroderma is a systemic autoimmune disease of unknown etiology whose characteristic features include endothelial cell dysfunction, fibroblast proliferation, and immune dysregulation. Although almost any organ can be pathologically involved in scleroderma, lung complications including interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are the leading cause of death in patients with this condition. Currently, the molecular mechanisms leading to development of scleroderma-related lung disease are poorly understood; however, the systemic nature of this condition has led many to implicate circulating factors in the pathogenesis of some of its organ impairment. In this article we focus on a new class of circulating factors derived from adipose-tissue called adipokines, which are known to be altered in scleroderma. Recently, the adipokines adiponectin and leptin have been found to regulate biological activity in endothelial, fibroblast, and immune cell types in lung and in many other tissues. The pleiotropic nature of these circulating factors and their functional activity on many cell types implicated in the pathogenesis of ILD and PAH suggest these hormones may be mechanistically involved in the onset and/or progression of scleroderma-related lung diseases.

Leptin as a marker for severity and prognosis of aneurysmal subarachnoid hemorrhage

Leptin has been identified as a plasma marker for outcomes in traumatic brain injury and intracerebral hemorrhage. We further investigated whether leptin might serve as a marker for severity and prognosis in aneurysmal subarachnoid hemorrhage. One hundred and eight consecutive patients and 108 sex and age - matched healthy subjects were recruited. Plasma leptin levels were measured by enzyme-linked immunosorbent assay. Clinical severity was assessed using World Federation of Neurological Surgeons score and Fisher score. Mortality and poor long-term outcome (Glasgow outcome scale scores of 1-3) at 6 months were recorded. Plasma leptin levels on admission were substantially higher in patients than in healthy controls, and were significantly associated with the clinical severity. There was also a significant association between leptin levels and clinical outcomes at 6 months in multivariate logistic regression analysis. Using receiver operating characteristic curves, we calculated areas under the curve for clinical outcomes at 6 months. The predictive performance of leptin was similar to, but did not obviously improve those of World Federation of Neurological Surgeons score and Fisher score. Thus, leptin may indicate clinical severity of the initial bleeding and also have prognostic value for clinical outcomes in aneurysmal subarachnoid hemorrhage and may therefore help in guiding treatment decisions in the setting of aneurysmal subarachnoid hemorrhage.