Leptin Resistance: A Possible Interface Between Obesity and Pulmonary-Related Disorders

Alpha-2 macroglobulin activity in SARS-CoV-2 induced infection and in the post-COVID-19 period

The universal proteinase inhibitor α2-macroglobulin (α₂-MG) exhibiting antiviral and immunomodulatory activities, is considered as an important participant in the infectious process. The activity of α₂-MG in the new coronavirus infection and post-covid syndrome (long COVID) has not been studied yet. We examined 85 patients diagnosed with community-acquired bilateral polysegmental pneumonia developed under conditions of a new coronavirus infection SARS-CoV-2. For assessment of the post-COVID period, 60 patients were examined 5.0±3.6 months after the coronavirus infection. Among these patients, 40 people had complications, manifested in the form of neurological, cardiological, gastroenterological, dermatological, bronchopulmonary symptoms. The control group included 30 conditionally healthy individuals with a negative PCR result for SARS-CoV-2 RNA and lack of antibodies to the SARS-CoV-2 virus. The α₂-MG activity in serum samples of patients with coronavirus infection dramatically decreased, up to 2.5% of the physiological level. This was accompanied by an increase in the activity of the α₁-proteinase inhibitor, elastase- and trypsin-like proteinases by 2.0-, 4.4- and 2.6-fold respectively as compared with these parameters in conditionally healthy individuals of the control. In the post-COVID period, despite the trend towards normalization of the activity of inhibitors, the activity of elastase-like and especially trypsin-like proteinases in serum remained elevated. In overweight individuals, the increase in the activity of trypsin-like proteinases was most pronounced and correlated with an increase in the antibody titer to the SARS-CoV-2 virus. In the post-COVID period, the α₂-MG activity not only normalized, but also exceeded the control level, especially in patients with dermatological and neurological symptoms. In patients with neurological symptoms or with dermatological symptoms, the α₂-MG activity was 1.3 times and 2.1 times higher than in asymptomatic persons. Low α₂-MG activity in the post-COVID period persisted in overweight individuals. The results obtained can be used to monitor the course of the post-COVID period and identify risk groups for complications.

Cytokines Profile and Lung Function in Children with Obesity and Asthma: A Case Control Study

The existence of common inflammatory biomarkers linking obesity and asthma in children has been hypothesized. Nevertheless, laboratory and clinical characteristics of children with obesity and asthma are still poorly defined. The primary aim of the present study is to investigate the lung function and the cytokine profile, in children with obesity and asthma. In this prospective, cross-sectional pilot study, pulmonary function tests, biochemical parameters, and serum cytokines levels were compared in three groups of 28 children each, matched for age and sex. Obese children showed normal forced spirometry values except an increased distal airway resistance in subjects with obesity and no asthma. Both groups including obese children showed higher leptin and IL-10 levels and lower adiponectin and TNF-alpha levels compared to children with no obesity and asthma. IL-33 and TGF-beta1 levels were higher in children with obesity and asthma vs. children with normal weight and asthma. Finally, IL-6 was undetectable in approximately 70% of obese children with no asthma, in 57% obese asthmatic children and in 100% of children with normal-weight and asthma. Children with obesity and asthma show the most striking cytokine profile, suggesting a pro-inflammatory role of fat mass in asthma development.

Influence of a 12-week physical activity program on leptin resistance in metabolic syndrome: a preliminary study

Purpose

Metabolic syndrome is a condition with clustering of risk factors like insulin resistance, obesity, dyslipidemia, and hypertension. Leptin is a protein of obese gene produced by white adipose tissue. Leptin resistance is the insensitivity of leptin in hypothalamus despite high amounts in blood causing obesity and metabolic syndrome. The study focused on the influence of a 12-week physical activity promotion program on leptin resistance in people with metabolic syndrome

Methods

After approval from institutional ethics committee (IEC 343-2018), 18 participants (males N= 4, females N=14) of age group 45.0±7.6 years with metabolic syndrome according to (NCEP ATP-III) criteria were included in the study. The participants underwent a 12-week physical activity program consisting of 150 min of moderate to vigorous activity per week as per GPAQ domains—work, transport, and recreation. The outcomes were measured at baseline and after 12 weeks.

Results

Out of 18 participants, 10 participants who completed the study were analysed. Twelve-week physical activity showed significant changes in waist circumference (p=0.047), post prandial blood glucose (p=0.0396), triglycerides (p=0.0323), body mass index (p=0.0056), subcutaneous fat (p=0.0354), and basal metabolic rate (p=0.0035). Fasting blood glucose (p=0.254), lipid profiles (total cholesterol (p=0.062)), high-density lipoprotein (p=0.367), low-density lipoprotein (p=0.641), and leptin showed insignificant change (p=0.328). Global physical activity questionnaire showed significant change (p=0.0254) suggesting changes in physical activity behaviors.

Conclusion

From present study, it is concluded that a 12-week physical activity promotion program brought marginal changes in leptin levels and has potential to modify metabolic syndrome parameters and improve physical activity.

When Leptin Is Not There: A Review of What Nonsyndromic Monogenic Obesity Cases Tell Us and the Benefits of Exogenous Leptin

Obesity is a pandemic condition of complex etiology, resulting from the increasing exposition to obesogenic environmental factors combined with genetic susceptibility. In the past two decades, advances in genetic research identified variants of the leptin-melanocortin pathway coding for genes, which are related to the potentiation of satiety and hunger, immune system, and fertility. Here, we review cases of congenital leptin deficiency and the possible beneficial effects of leptin replacement therapy. In summary, the cases presented here show clinical phenotypes of disrupted bodily energy homeostasis, biochemical and hormonal disorders, and abnormal immune response. Some phenotypes can be partially reversed by exogenous administration of leptin. With this review, we aim to contribute to the understanding of leptin gene mutations as targets for obesity diagnostics and treatment strategies.

[Obesity and asthma: Mechanisms and therapeutic options]

Asthma and obesity are both common conditions, which lead to a substantial public health burden. The obese-asthma phenotype is characterized by poor asthma control, impaired lung function and decreased efficacy of inhaled treatment. However, this phenotype is highly heterogeneous and involves numerous mechanisms, including systemic inflammation and adipokines. A role for microbiota modifications and genetics has been suggested. Obese-asthma patient management currently consists in weight loss and usual anti-asthmatic treatment. New therapeutic options are being evaluated.

Association between glycemic state and pulmonary function and effect of walking as a protective factor in subjects with diabetes mellitus

Background

Several population-based studies have shown that individuals with type 2 diabetes mellitus (T2DM) have decreased pulmonary function. Moreover, impaired pulmonary function is associated with all-cause mortality in T2DM. We investigated the association between glycemic state and pulmonary function and evaluated the role of walking as protective factor in subjects with diabetes using a nationwide, population-based, cross-sectional survey.

Methods

The study included 17,542 subjects: 2,195 with diabetes, 4,042 with prediabetes, and 11,305 with normal glucose tolerance. Furthermore, 1,770 subjects with available data on walking exercise were divided into three groups according to weekly exercise time: <150, 150-300, and ≥ 300 min/week.

Results

The diabetes group had reduced pulmonary function, particularly forced vital capacity (FVC) (P<0.001), and a decrease in pulmonary function was observed in the subjects with prediabetes (P<0.001). The walking exercise analysis revealed that the percentage of predicted FVC (P=0.001) and percentage of predicted forced expiratory volume in 1 s (P=0.021) were highest in the subjects with diabetes who walked ≥300 min/week after adjustment for age, sex, body mass index, and waist circumference (WC) measurements.

Conclusions

Pulmonary function was significantly associated with walking exercise in diabetic patients, and walking ≥300 min/week may have a preventive effect against pulmonary dysfunction in subjects with diabetes.

Participation of NADPH Oxidase-Related Reactive Oxygen Species in Leptin-Promoted Pulmonary Inflammation: Regulation of cPLA2α and COX-2 Expression

Obesity is a worldwide epidemic problem and correlates to varieties of acute or chronic lung diseases such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis. An increase of leptin, a kind of adipokine, in lean mice plasma has been found to impair immune responses and facilitate the infection of Klebsiella pneumoniae, resulting in increased pneumonia severity. Also, a higher leptin level is found in exhaled breath condensates of obese or asthmatic subjects, compared to healthy ones, suggesting that leptin is involved in the occurrence or exacerbation of lung injury. In previous studies, we showed that leptin stimulated cytosolic phospholipase A2-α (cPLA2α) gene expression in lung alveolar type II cells via mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB)-activated coactivator p300. Herein, we show that the in vivo application of leptin in the respiratory system upregulated the expression of inflammatory proteins cPLA2α and cyclooxygenase-2 (COX-2) together with leukocyte infiltration. Treatment with an ROS scavenger (N-acetylcysteine, NAC), an NADPH oxidase inhibitor (apocynin), or an activating protein (AP)-1 inhibitor (tanshinone IIA) attenuated leptin-mediated cPLA2α/COX-2 expression and leukocyte recruitment in the lung. Leptin increased intracellular oxidative stress in a leptin receptor (OB-R) and NADPH oxidase-dependent manner, leading to the phosphorylation of the AP-1 subunit c-Jun. In summation, leptin increased lung cPLA2α/COX-2 expression and leukocyte recruitment via the NADPH oxidase/ROS/AP-1 pathway. Understanding the inflammatory effects of leptin on the pulmonary system provides opportunities to develop strategies against lung injury related to metabolic syndrome or obesity.

Leptin resistance: underlying mechanisms and diagnosis

Leptin and its receptors have been identified as key regulators of body weight and energy homeostasis. A decrease in tissue sensitivity to leptin leads to the development of obesity and metabolic disorders, such as insulin resistance and dyslipidemia. Mechanisms underlying the development of leptin resistance include mutations in the genes encoding leptin and its receptors, as well as proteins involved in self-regulation of leptin synthesis and blood-brain barrier permeability. Leptin resistance encompasses a complex pathophysiological phenomenon with a number of potential research lines. In this review, we analyze the existing data on the methods used to diagnose leptin resistance.

The impact of fetal umbilical artery Doppler pulsatility index on childhood respiratory function and atopy: a prospective case-control study

Objective: To determine if an elevated fetal umbilical artery Doppler pulsatility index is associated with abnormal respiratory function and atopy in children aged 12 years.Methods: This prospective case-control study compared children that had an elevated fetal umbilical artery Doppler pulsatility index (>90th centile) to those with a normal pulsatility index (<90th centile). All subjects were delivered at full-term and with appropriate growth for gestational age. Outcome measures included; (i) presence of asthma and/or atopy; (ii) spirometry measurements and (iii) serum C-reactive protein and leptin. Multiple regression was used to account for parental smoking, childhood age, gender and socioeconomic status.Results: 174 children with an average age of 12.1 (±0.6 SD), 48% of who were male were included in the analysis. Of the 174, 99 (57%) were in the normal umbilical artery Doppler pulsatility index group and 75 (43%) elevated umbilical artery Doppler pulsatility index groups. The overall proportion of subjects with asthma was 28% (48/174) and atopy 56% (98/174). No association was found between elevated fetal umbilical artery Doppler pulsatility index and asthma (p = .47) or atopy (p = .75) at age 12 years. Similarly there was no association between FEV1(%) (p = .96), forced vital capacity (FVC)(%) (p = .98), elevated serum C-reactive protein (p = .69) or leptin (p = .20) and an elevated fetal umbilical artery Doppler pulsatility index.Conclusions: An elevated umbilical artery Doppler at 28-weeks gestation in the absence of prematurity or fetal growth restriction is not associated with altered respiratory function or the presence of atopy in children aged 12 years. These findings support the theory that such disease has a multifactorial pathophysiology.

Pulmonary Function and Sleep Breathing: Two New Targets for Type 2 Diabetes Care

Population-based studies showing the negative impact of type 2 diabetes (T2D) on lung function are overviewed. Among the well-recognized pathophysiological mechanisms, the metabolic pathways related to insulin resistance (IR), low-grade chronic inflammation, leptin resistance, microvascular damage, and autonomic neuropathy are emphasized. Histopathological changes are exposed, and findings reported from experimental models are clearly differentiated from those described in humans. The accelerated decline in pulmonary function that appears in patients with cystic fibrosis (CF) with related abnormalities of glucose tolerance and diabetes is considered as an example to further investigate the relationship between T2D and the lung. Furthermore, a possible causal link between antihyperglycemic therapies and pulmonary function is examined. T2D similarly affects breathing during sleep, becoming an independent risk factor for higher rates of sleep apnea, leading to nocturnal hypoxemia and daytime sleepiness. Therefore, the impact of T2D on sleep breathing and its influence on sleep architecture is analyzed. Finally, the effect of improving some pathophysiological mechanisms, primarily IR and inflammation, as well as the optimization of blood glucose control on sleep breathing is evaluated. In summary, the lung should be considered by those providing care for people with diabetes and raise the central issue of whether the normalization of glucose levels can improve pulmonary function and ameliorate sleep-disordered breathing. Therefore, patients with T2D should be considered a vulnerable group for pulmonary dysfunction. However, further research aimed at elucidating how to screen for the lung impairment in the population with diabetes in a cost-effective manner is needed.

Myeloid ATG16L1 does not affect adipose tissue inflammation or body mass in mice fed high fat diet

BACKGROUND

An influx of lipid-loaded macrophages characterizes visceral adipose tissue (VAT) inflammation, which is an important factor in the development of insulin resistance (IR) in obesity. Depletion of macrophage lipids accompanies increased whole body insulin sensitivity, but the underlying mechanism is unknown. Deficiency of autophagy protein ATG16L1 is associated with increases in inflammatory diseases and lipid metabolism, but the connection between ATG16L1, IR, and obesity remains elusive. We hypothesize that myeloid ATG16L1 contributes to lipid loading in macrophages and to IR.

METHODS

Wild-type (WT) bone marrow derived macrophages (BMDMs) were treated with fatty acids and assessed for markers of autophagy. Myeloid-deficient Atg16l1 and littermate control male mice were fed high fat diet (HFD) or low fat diet (LFD) for 3 months starting at 8 weeks of age. Mice were assessed for body mass, fat and lean mass, glucose and insulin sensitivity, food consumption and adipose inflammation. Fluorescence-activated cell sorted VAT macrophages were assessed for lipid content and expression of autophagy related genes.

RESULTS

VAT and VAT macrophages from HFD-fed WT mice did not show differences in autophagy protein and gene expression compared to tissue from LFD-fed mice. Fatty acid-treated BMDMs increased neutral lipid content but did not change autophagy protein expression. HFD-fed Atg16l1 myeloid-deficient and littermate mice demonstrated no differences in body mass, glucose or insulin sensitivity, food consumption, fat or lean mass, macrophage lipid content, or adipose tissue inflammation.

CONCLUSION

ATG16L1 does not contribute to obesity, IR, adipose tissue inflammation or lipid loading in macrophages in mice fed HFD.