Adiponectin: the link between obesity and asthma in women?

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

Resistin is a predictor of asthma risk and resistin:adiponectin ratio is a negative predictor of lung function in asthma

BACKGROUND

Adipokines, such as resistin and adiponectin, modify inflammation and may contribute to increased asthma risk and severity in obese people.

OBJECTIVE

To examine plasma resistin and resistin:adiponectin ratio (i) in asthmatics compared to healthy controls, (ii) according to asthma severity, obesity and gender (iii) following weight loss in obese asthmatics.

METHODS

In a cross-sectional observational study of asthmatic adults (n = 96) and healthy controls (n = 46), plasma resistin and adiponectin were measured. In a separate intervention study, obese asthmatic adults (n = 27) completed a 10-week weight loss intervention and plasma resistin and adiponectin concentrations were analysed.

RESULTS

Plasma resistin and resistin:adiponectin ratio were higher in asthma compared to controls and were higher again in subjects with a severe vs. mild-to-moderate asthma pattern. Amongst asthmatic subjects, resistin was not modified by gender or obesity, while adiponectin was lower in males and obese subjects. As a result, resistin:adiponectin ratio was higher in obese males, non-obese males and obese females, compared to non-obese females. In a logistic regression model, plasma resistin concentration was a predictor of asthma risk. In a multiple linear regression model, plasma resistin:adiponectin ratio was a negative predictor of FEV1 in asthma. Following weight loss, neither resistin, adiponectin nor resistin:adiponectin ratio was changed. However, the change (∆) in %body fat was associated with ∆ resistin:adiponectin ratio. Post-intervention ∆ resistin was negatively correlated with both ∆FRC and ∆RV.

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrates that resistin and resistin:adiponectin ratio are higher in asthma and are higher again in subjects who have more severe disease. Resistin:adiponectin ratio is highest in obese male asthmatics. As resistin is a predictor of asthma risk and resistin:adiponectin is a predictor of FEV1 in asthma, these adipokines may be contributing to the obese asthma phenotype, thus providing a potential therapeutic target for obese asthma.

Influence of Anthropometric Measurements in Lung Function in Patients With Asthma

Background:

Obesity is commonly regarded as a risk factor for asthma development, poor asthma control, and poor response to asthma therapy.

Methods:

In a cross-sectional study, 85 asthmatics (37 male and 48 female) participated. Pulmonary function tests (PFTs) and anthropometric parameters were measured for each patient.

Results:

Mean age and median duration were 43.9 ± 10.61 and 6 (3–14) years, respectively. Among anthropometric parameters, only waist-to-hip ratio (WHR) indicated significant correlation with PFTs in both sex (P < 0.05). There were negative associations between waist circumference, hip circumference and WHR with PFTs only in overweight and obese women (P < 0.05).

Conclusions:

Some anthropometric parameters affected lung function, and it seems that gender differentially contributes to this effect.

Nutrition and respiratory health--feature review

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

Obesity and asthma

There is a global epidemic of asthma and obesity that is concentrated in Westernized and developed countries. A causal association in some people with asthma is suggested by observations that obesity precedes the onset of asthma and that bariatric surgery for morbid obesity can resolve asthma. The obese asthma phenotype features poor asthma control, limited response to corticosteroids, and an exaggeration of the physiological effects of obesity on lung function, which includes a reduction in expiratory reserve volume and airway closure occurring during tidal breathing. Obesity has important implications for asthma treatment. Increasing corticosteroid doses based on poor asthma control, as currently recommended in guidelines, may lead to overtreatment with corticosteroids in obese asthma. Enhanced bronchodilation, particularly of the small airways, may reduce the component of airway closure due to increased bronchomotor tone and suggests that greater emphasis should be placed on long-acting bronchodilators in obese asthma. The societal implications of this are important: with increasing obesity there will be increasing asthma from obesity, and the need to identify successful individual and societal weight-control strategies becomes a key goal.

Immunometabolism in obese asthmatics: are we there yet?

Obesity is now recognised as a worldwide epidemic. The recent International Association for the Study of Obesity/International Obesity Taskforce (IASO/IOTF) analysis estimates that approximately 1.0 billion adults are currently overweight and a further 475 million are obese. Obesity has huge psychosocial impact with obese children and adolescents facing discrimination and stigmatization in many areas of their lives leading to body dissatisfaction, low self-esteem and depression. Indeed, obesity is recognised as an important risk factor for the development of several chronic diseases such as hypertension, cancer, asthma and metabolic syndrome. Chronic low grade systemic inflammation is considered as a hallmark of obesity and may possibly explain the link between obesity and chronic disease, in particular the increased incidence, prevalence and severity of asthma in obese individuals. There is now strong evidence for infiltration of immune and inflammatory cells into adipose tissue that drives systemic inflammation and subsequent end organ damage. In addition to adipocytes, the key adipose tissue resident immune cells are macrophages and mast cells. Immunometabolism, as an emerging field of investigation, explores the pivotal role of these immune cells in translating immunological changes to metabolic effects in obesity. Abundance of free fatty acids, along with other inflammatory cytokines shift the balance of metabolic homeostasis to pro-inflammatory status by influencing the development of inflammatory cell lineage, which, further exhibits distinct functional phenotypes. There is emerging evidence for macrophage activation and functional polarization of an anti-inflammatory M₂ phenotype towards a pro-inflammatory M₁ phenotype of macrophages in obese adipose tissue. Similarly, studies in both obese humans and murine models reveal the pathognomic presence of an increased number of mast cells in visceral adipose tissue. These suggest a possible contribution of mast cells to the unique metabolome of obese asthma. This review examines proposed multilevel interactions between metabolic and immune systems in obese asthmatics that underlie the negative effects of obesity and may offer significant therapeutic promise.