Adipokines and Cysteinyl Leukotrienes in the Pathogenesis of Asthma

Dietary choline intake and its association with asthma: A study based on the National Health and Nutrition Examination Survey database

OBJECTIVE

This work endeavored to examine the correlation between dietary choline intake and the odds of asthma, utilizing data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

Aggregated data from seven cycles (2005-2018) in the NHANES database were utilized. The independent variable was dietary choline intake, and the dependent variable was asthma. The weighted logistic regression method was used to construct a model reflecting the relationship between these two factors. This work employed stratified analysis without adjusting for confounding factors and subgroup analysis with adjusted confounding factors to mine the association between dietary choline intake and asthma. Additionally, restricted cubic spline analysis examined nonlinear associations of the two in age subgroups.

RESULTS

Forty five thousand and seven hundreds ninety seven samples were included here. The model indicating the relationship between dietary choline intake and asthma was constructed (OR: 0.86, 95% CI: 0.79-0.93, p < 0.001). Stratified analysis indicated that the interaction terms of age (p < 0.001) and body mass index (BMI) (p = 0.002) with dietary choline intake significantly influenced the relationship model. In the adjusted models, accounting for demographic characteristics, poverty impact ratio, BMI, exposure to environmental tobacco smoke, and total energy intake, an increase in dietary choline intake significantly reduced the odds of asthma (OR: 0.79, 95% CI: 0.72-0.88, p < 0.001). Subgroup analyses based on age and BMI revealed a significant negative correlation between dietary choline intake and the odds of asthma in the adult population (OR: 0.76, 95% CI: 0.67-0.86, p < 0.001), as well as in individuals with a BMI between 25 and 30 kg/m2 (OR: 0.79, 95% CI: 0.63-0.99, p = 0.042), and those with a BMI >30 kg/m2 (OR: 0.73, 95% CI: 0.60-0.89, p = 0.002).

CONCLUSION

Dietary choline intake was significantly inversely correlated with asthma prevalence, especially in adults and overweight/obese individuals, suggesting that increasing choline intake may reduce asthma risk. Further research is needed to explore this relationship and provide tailored dietary recommendations for different age and BMI groups to enhance asthma prevention and management.

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Effect of obesity on airway and systemic inflammation in adults with asthma: a systematic review and meta-analysis

BACKGROUND

Obesity is associated with more severe asthma, however, the mechanisms responsible are poorly understood. Obesity is also associated with low-grade systemic inflammation; it is possible that this inflammation extends to the airways of adults with asthma, contributing to worse asthma outcomes. Accordingly, the aim of this review was to examine whether obesity is associated with increased airway and systemic inflammation and adipokines, in adults with asthma.

METHODS

Medline, Embase, CINAHL, Scopus and Current Contents were searched till 11 August 2021. Studies reporting measures of airway inflammation, systemic inflammation and/or adipokines in obese versus non-obese adults with asthma were assessed. We conducted random effects meta-analyses. We assessed heterogeneity using the I2 statistic and publication bias using funnel plots.

RESULTS

We included 40 studies in the meta-analysis. Sputum neutrophils were 5% higher in obese versus non-obese asthmatics (mean difference (MD)=5.0%, 95% CI: 1.2 to 8.9, n=2297, p=0.01, I2=42%). Blood neutrophil count was also higher in obesity. There was no difference in sputum %eosinophils; however, bronchial submucosal eosinophil count (standardised mean difference (SMD)=0.58, 95% CI=0.25 to 0.91, p<0.001, n=181, I2=0%) and sputum interleukin 5 (IL-5) (SMD=0.46, 95% CI=0.17 to 0.75, p<0.002, n=198, I2=0%) were higher in obesity. Conversely, fractional exhaled nitric oxide was 4.5 ppb lower in obesity (MD=-4.5 ppb, 95% CI=-7.1 ppb to -1.8 ppb, p<0.001, n=2601, I2=40%). Blood C reactive protein, IL-6 and leptin were also higher in obesity.

CONCLUSIONS

Obese asthmatics have a different pattern of inflammation to non-obese asthmatics. Mechanistic studies examining the pattern of inflammation in obese asthmatics are warranted. Studies should also investigate the clinical relevance of this altered inflammatory response.

PROSPERO REGISTERATION NUMBER

CRD42021254525.

Predictive and prognostic value of leptin status in asthma

Asthma is closely associated with inflammation. We evaluated the predictive and prognostic value of leptin status in asthma. We searched the electronic databases for articles that determined the leptin level in asthma cases through May 2020. We compared the differences of leptin level between asthma and non-asthma controls, as well as between severe and mild asthma cases. We also investigated the impact of age and gender on these differences by using meta-regression analysis. 59 studies were included in our pooled analysis. Asthma cases demonstrated significantly higher leptin level than that in non-asthma controls among overall populations (SMD:1.061, 95% CI: 0.784-1.338, p < 10^-4), Caucasians (SMD:0.287, 95% CI: 0.125-0.448, p = 0.001), Asians (SMD:1.500, 95% CI: 1.064-1.936, p < 10^-4) and Africans (SMD: 8.386, 95% CI: 6.519-10.253, p < 10^-4). Severe asthma cases showed markedly higher leptin level than that in mild asthma cases among overall populations (SMD:1.638, 95% CI: 0.952-2.323, p < 10^-4) and Asians (SMD:2.600, 95% CI: 1.854-3.345, p < 10^-4). No significant difference of leptin level between severe and mild asthma was observed in Caucasians (SMD:-0.819, 95% CI: -1.998-0.360, p = 0.173). Cumulative analyses yielded similar results regarding the difference of leptin status between asthma and non-asthma controls, as well as between severe and mild asthma cases among overall populations. Age and male/ female ratio were not associated with the difference of leptin status between asthma and non-asthma controls (coefficient:-0.031, 95% CI: -0.123-0.061, p = 0.495; coefficient:0.172, 95% CI: -2.445-2.789, p = 0.895), as well as between severe and mild asthma cases among overall populations (coefficient:-0.072, 95% CI: -0.208-0.063, p = 0.279; coefficient: 2.373, 95% CI: -0.414-5.161, p = 0.090). Asthma demonstrated significantly higher level of leptin than that in non-asthma controls among overall populations, Caucasians, Asians and Africans. Severe asthma cases showed markedly higher leptin level than that in mild cases among overall populations and Asians. Leptin may be a risk predictor and prognostic marker of asthma. Early monitoring and intervention of leptin may be needed for asthma.

Evaluating the safety and efficacy of the leukotriene receptor antagonist montelukast as adjuvant therapy in obese patients with type 2 diabetes mellitus: A double-blind, randomized, placebo-controlled trial

Background: Type 2 diabetes mellitus (T2DM) is common with obesity. Metformin is a first-line therapy for this condition. However, it has only a minor impact on weight loss in some patients. Aim: This study aimed to evaluate the effectiveness, tolerability, and safety of combining montelukast therapy with metformin in obese diabetic patients. Methods: One hundred obese diabetic adult patients were recruited and randomized into two equal groups. Group 1 received placebo plus metformin 2 g/d, and Group 2 received 2 g/d metformin plus 10 mg/d montelukast. Demographic, anthropometric measurements (e.g., body weight, body mass index [BMI], and visceral adiposity index), lipid profile, diabetes control measures (fasting blood glucose, glycated hemoglobin [HbA1c], and homeostatic model assessment for insulin resistance [HOMA-IR]), adiponectin, and inflammatory markers (e.g., TNF-α, IL-6, and leukotriene B4) were assessed and reported for each group at baseline and after 12 weeks of treatment. Results: Both interventions significantly reduced all the measured parameters, except for adiponectin and HDL-C, levels of which increased compared to baseline data (p < 0.001). The montelukast group significantly improved in all parameters compared to the placebo group (ANCOVA test p < 0.001). The percentage changes in BMI, HbA1c, HOMA-IR, and inflammatory markers were 5%, 9%, 41%, and 5%-30%, respectively, in the placebo group compared to 8%, 16%, 58%, and 50%-70%, respectively, in the montelukast group. Conclusion: Montelukast adjuvant therapy was superior to metformin-only therapy in diabetes control and weight loss, most likely due to its increased insulin sensitivity and anti-inflammatory properties. The combination was tolerable and safe throughout the study duration. Clinical Trial Registration: [Clinicaltrial.gov], identifier [NCT04075110].

LC-MS-based metabolomics reveals the in vivo effect of Shegan Mahuang Decoction in an OVA-induced rat model of airway hyperresponsiveness

The traditional Chinese medicine (TCM) formula Shegan Mahuang Decoction (SMD) has been used for treating asthma with significant clinical efficacy, but its mechanism of action has not been well investigated. This study aimed to investigate the anti-asthma effects of SMD on ovalbumin (OVA)-induced airway hyperresponsiveness (AHR) in rats and its potential mechanisms using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics combined with Gene Expression Omnibus (GEO) data mining. The results showed that the administration of SMD significantly attenuated OVA-induced lung histopathological changes. OVA-induced elevation of the immunoglobulin (IgE) and interleukin-4 (IL-4) levels was also inhibited by SMD. A total of 28 significantly changed metabolites in plasma were selected from metabolomics analysis. After treatment with SMD, 24 of them were negatively regulated and the related metabolisms were involved in multiple metabolic pathways such as sphingolipid metabolism and arachidonic acid metabolism. The differentially expressed genes (DEGs) were obtained by GEO data mining. The integrated pathway analysis highlighted 11 signaling pathways that were associated with the anti-asthma effect of SMD. Among them, the metabolite-gene-pathway network showed that the peroxisome proliferator-activated receptors (PPAR) signaling pathway might be the most significant one. This study revealed that SMD exerted an anti-asthma effect against OVA-induced AHR via comprehensively modulating the sphingolipid metabolism, arachidonic acid metabolism, and PPAR signaling, which indicated the synergistic effect of multi-component, multi-target, and multi-pathway of TCM in the treatment of the disease. This study expands our understanding of SMD in the treatment of asthma from a metabolomics perspective.

Shotgun Lipidomics for Differential Diagnosis of HPV-Associated Cervix Transformation

A dramatic increase in cervical diseases associated with human papillomaviruses (HPV) in women of reproductive age has been observed over the past decades. An accurate differential diagnosis of the severity of cervical intraepithelial neoplasia and the choice of the optimal treatment requires the search for effective biomarkers with high diagnostic and prognostic value. The objective of this study was to introduce a method for rapid shotgun lipidomics to differentiate stages of HPV-associated cervix epithelium transformation. Tissue samples from 110 HPV-positive women with cervicitis (n = 30), low-grade squamous intraepithelial lesions (LSIL) (n = 30), high-grade squamous intraepithelial lesions (HSIL) (n = 30), and cervical cancers (n = 20) were obtained. The cervical epithelial tissue lipidome at different stages of cervix neoplastic transformation was studied by a shotgun label-free approach. It is based on electrospray ionization mass spectrometry (ESI-MS) data of a tissue extract. Lipidomic data were processed by the orthogonal projections to latent structures discriminant analysis (OPLS-DA) to build statistical models, differentiating stages of cervix transformation. Significant differences in the lipid profile between the lesion and surrounding tissues were revealed in chronic cervicitis, LSIL, HSIL, and cervical cancer. The lipids specific for HPV-induced cervical transformation mainly belong to glycerophospholipids: phosphatidylcholines, and phosphatidylethanolamines. The developed diagnostic OPLS-DA models were based on 23 marker lipids. More than 90% of these marker lipids positively correlated with the degree of cervix transformation. The algorithm was developed for the management of patients with HPV-associated diseases of the cervix, based on the panel of 23 lipids as a result. ESI-MS analysis of a lipid extract by direct injection through a loop, takes about 25 min (including preparation of the lipid extract), which is significantly less than the time required for the HPV test (several hours for hybrid capture and about an hour for PCR). This makes lipid mass spectrometric analysis a promising method for express diagnostics of HPV-associated neoplastic diseases of the cervix.

Association between Serum Total and Specific Immunoglobulin E Levels and Body Height: A Cross-Sectional Study of Children and Adolescents

Background: The atopy rate in children has increased significantly. Atopy and growth are connected in a multifactorial manner and are important health issues for children around the world. The principal research question in this cross-sectional investigation concerned the association between serum total, specific immunoglobulin E (IgE) levels, and body height (BH)/weight (BW)/body mass index (BMI). Methods: A total of 993 subjects were enrolled for analysis retrospectively with allergic diseases and aged from 6 months to 18 years during the years 2015−2016. A complete panel of 36 allergen-specific IgE was taken from each participant using the MAST allergen test as well as their BH, BW, BMI, and total IgE levels. Results: There was a statistically significant positive association between the total IgE levels with BH (N = 348) and BW (N = 623) in the preschool age group (<6 years old, p-values of 0.009 and 0.034, respectively). In the preschool group, the total IgE levels showed a positive association with house dust (p < 0.001), cockroach mix (p < 0.001), Dermatophagoides farina (p < 0.001), and Dermatophagoides pteronyssinus (p < 0.001). After performing a general linear model followed by a backward selection of variables with age, sex, specific IgE, and total IgE, egg white sensitization demonstrated a significant negative association with BH (p = 0.009), and Dermatophagoides farina sensitization showed a significant positive association with BH (p = 0.006). The analysis showed that, in this model, the level of total IgE was not associated with BH. Conclusions: The results of this study indicate that the level of total IgE was not associated with BH in the preschool age group. Future studies are needed to replicate the results in outcome with follow-up allergic cohorts.

Metformin Alleviates Airway Hyperresponsiveness in a Mouse Model of Diet-Induced Obesity

Obese asthma is a unique phenotype of asthma characterized by non-allergic airway hyperresponsiveness (AHR) and inflammation which responds poorly to standard asthma therapy. Metformin is an oral hypoglycemic drug with insulin-sensitizing and anti-inflammatory properties. The objective of the current study was to test the effect of metformin on AHR in a mouse model of diet-induced obesity (DIO). We fed 12-week-old C57BL/6J DIO mice with a high fat diet for 8 weeks and treated them with either placebo (control, n = 10) or metformin (n = 10) added in drinking water (300 mg/kg/day) during the last 2 weeks of the experiment. We assessed AHR, metabolic profiles, and inflammatory markers after treatments. Metformin did not affect body weight or fasting blood glucose, but significantly reduced serum insulin (p = 0.0117). Metformin reduced AHR at 30 mg/ml of methacholine challenge (p = 0.0052) without affecting baseline airway resistance. Metformin did not affect circulating white blood cell counts or lung cytokine mRNA expression, but modestly decreased circulating platelet count. We conclude that metformin alleviated AHR in DIO mice. This finding suggests metformin has the potential to become an adjuvant pharmacological therapy in obese asthma.

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.

Effects of weight loss on dynamic hyperinflation in obese women asthmatics

Obese adults with asthma are more likely to develop dynamic hyperinflation (DH) and expiratory flow limitation (EFL) than nonobese asthmatics, and weight-loss seems to improve the breathing mechanics during exercise. However, studies evaluating the effect of weight loss on DH in obese adults with asthma have not been performed. We sought to evaluate the effect of a weight loss program on DH in obese adults with asthma. Forty-two asthma patients were enrolled in a weight loss program (diet, psychological support, and exercise) and were subsequently divided into two groups according to the percentage of weight loss: a ≥5% group ( n = 19) and a <5% group ( n = 23). Before and after the intervention, DH and EFL (constant load exercise), health-related quality of life (HRQoL), asthma control, quadriceps muscle strength and endurance, body composition, and lung function were assessed. Both groups exhibited a decrease of ≥10% in inspiratory capacity (DH) before intervention, and only the ≥5% group showed clinical improvement in DH compared with the <5% group postintervention (-9.1 ± 14.5% vs. -12.5 ± 13.5%, respectively). In addition, the ≥5% group displayed a significant delay in the onset of both DH and EFL and a clinically significant improvement in HRQoL and asthma control. Furthermore, a correlation was observed between reduced waist circumference and increased inspiratory capacity ( r = -0.45, P = 0.05) in the ≥5% group. In conclusion, a weight-loss of ≥5% of the body weight improves DH, which is associated with waist circumference in obese adults with asthma. In addition, the group with greater weight-loss showed a delayed onset of DH and EFL during exercise and improved asthma clinical control and HRQoL. NEW & NOTEWORTHY This is the first study to evaluate dynamic hyperinflation (DH) after a weight loss program in obese patients with asthma. Our results demonstrate that moderate weight loss can improve DH in obese patients with asthma that is associated with a decrease in abdominal fat. Moreover, a minimum of 5% in weight loss delays the onset of DH and expiratory flow limitation besides inducing a clinical improvement in asthma quality of life and clinical control.

Asthma, GERD and Obesity: Triangle of Inflammation

There is increasing prevalence of both asthma and obesity in children globally in recent years. Various epidemiological studies link obesity as a risk factor for asthma and suggest a possible causal association. Obesity asthma phenotype is considered as distinct in view of greater severity and poor asthma control. Various mechanisms underlying this phenotype have been suggested including mechanical effects of obesity and systemic inflammation, but still the exact mechanism is unclear. Also, the comorbidities like gastroesophageal reflux disease (GERD) and sleep disordered breathing (SDB) lead to inflammation in airways and contribute to asthma obesity association. A better understanding of mechanisms by which obesity and GERD lead to inflammation in airways and increase the risk of asthma may provide insight towards targeted treatment approach of these patients.

Lipid mediator Leukotriene D4-induces airway epithelial cells proliferation through EGFR/ERK1/2 pathway

BACKGROUND

Cysteinyl leukotrienes (CysLTs), the potent lipid inflammatory mediators, are elevated in many pathological conditions and implicated in various inflammatory diseases including asthma, however their role in airway epithelial cells modulation is not clearly understood. We have investigated the effects of a CysLT, Leukotriene D₄ (LTD₄) on human airway epithelial cells, and assessed its role and mode of action in these cells.

METHODOLOGY

Human small airway epithelial cells (SAECs) and A549 cells were incubated with different concentrations of LTD₄ for different time intervals. Subsequently trypan blue dye exclusion assay, MTT assay, Western blotting, RT-PCR and immunofluorescence experiments were performed to examine the effects of LTD₄ on proliferation and related molecular changes in the airway epithelial cells.

RESULTS

The treatment of human airway epithelial cells with LTD₄ resulted in a significant increase in cell proliferation and modulation in the expression of receptors, CysLT₁R and CysLT₂R in SAECs as well as A549 cells. In both types of cells, LTD₄ increased the expression levels of PCNA and c-myc, and trans-activated EGF receptor and increased the activation of ERK1/2. When treated along with epidermal growth factor (EGF), LTD₄ showed a marginal additive effect in ERK1/2 and EGFR phosphorylation compared to LTD₄ alone in both types of airway epithelial cells.

CONCLUSION

In conclusion, these results suggest that sustained presence of lipid inflammatory mediator LTD₄ could induce human airway epithelial cell proliferation through ERK1/2 phosphorylation, either directly via CysLT₁ receptor or by transactivating EGFR.

Asthma in reproductive-aged women with polycystic ovary syndrome and association with obesity

Recent research suggests that women with polycystic ovary syndrome (PCOS) may have a higher prevalence of asthma. However, there are no epidemiological studies aimed primarily at exploring the relationship between PCOS and asthma, and the effect of body mass index (BMI) on this association.This study is a cross-sectional analyses of data from the Australian Longitudinal Study on Women's Health, a large, community-based, prospective study to examine the association between PCOS and asthma in women aged 28-33 years (n=478 PCOS and n=8134 controls).The prevalence of asthma was 15.2% in women with PCOS and 10.6% in women without PCOS (p=0.004). Women with PCOS who had asthma had a trend for a higher BMI compared with women without asthma (29.9±0.9 versus 27.7±0.4 kg·m^-2; p=0.054). Women without PCOS who had asthma had a higher BMI compared with women without asthma (26.4±0.2 versus 24.9±0.1 kg·m^-2; p<0.001). After adjusting for age, BMI and smoking status, PCOS was associated with increased odds of asthma (odds ratio 1.34, 95% CI 1.004-1.79; p=0.047).This study showed both PCOS status and overweight/obese status were independently associated with asthma. Further prospective studies are required to explore the possible mechanisms underpinning the association between asthma and PCOS.