Systemic inflammation and lung function impairment in morbidly obese subjects with the metabolic syndrome

Obesity-related asthma: new insights leading to a different approach

PURPOSE OF REVIEW

Obesity is a growing global health threat that significantly contributes to the burden of asthma by increasing the risk of developing asthma and exerting a distinct effect on lung function and inflammation. The treatment of obesity-related asthma is hindered by a poor response to standard asthma treatments, leading to worse asthma control. Weight loss strategies have a significant effect on asthma symptoms but are not feasible for a large proportion of patients, underscoring the need for a better understanding of the pathophysiology and the development of additional treatment options.

RECENT FINDINGS

Recent literature focusing on pathophysiology particularly delved into nontype 2 inflammatory mechanisms, associations with the metabolic syndrome and small airway impairment. Additionally, several new treatment options are currently investigated, including biologics, weight reduction interventions, and novel antiobesity drugs.

SUMMARY

Obesity-related asthma is a highly prevalent asthma phenotype for which weight loss strategies currently stand as the most specific treatment. Furthermore, novel pharmacological interventions aiming at metabolic processes are on the way.

Association of white blood cell parameters with metabolic syndrome: A systematic review and meta-analysis of 168,000 patients

BACKGROUND

Leukocyte parameters are predicted to be affected in patients with metabolic syndrome (MetS). We conducted a systematic review and meta-analysis to study the association between white blood cell parameters (WBC) in people with and without MetS.

METHODS

PubMed, EMBASE, Scopus and Cochrane Library databases were searched according to the study protocol. The standardized mean difference (SMD) and 95% confidence intervals (CI) of leukocyte markers between individuals with and without MetS were pooled using an inverse variance model. Additionally, a subgroup analysis by sex was performed where possible. Methodological quality assessment was conducted using the Newcastle-Ottawa scale (NOS) for observational studies and the Cochrane Risk of Bias tool 2.0 for Randomized Controlled Trials (RCTs).

RESULTS

Of 6068 articles identified, 63 were eligible for the study. Compared to controls, individuals with MetS showed significantly higher concentrations of total leukocyte count (SMD [95% CI]: 0.60 [0.55-0.65]; P < .00001; I2 = 100%), neutrophil counts (0.32 [0.28-0.37]; P < .00001; I2 = 99%), lymphocyte counts (0.15 [0.07-0.23]; P = .0004; I2 = 100%), basophil counts (0.01 [0.00-0.02]; P = .02; I2 = 98%), monocyte counts (0.05 [0.02-0.09]; P = .003; I2 = 99%), and neutrophil-to-lymphocyte ratio (0.24 [0.15-0.33]; P < .00001; I2 = 98%). There were no significant differences in the eosinophil count (0.02 [-0.01 to 0.05]; P = .19; I2 = 96%) and monocyte-to-lymphocyte ratio (0.06 [-0.05 to 0.17]; P = .27; I2 = 100%) between patients with and without MetS, however, the lymphocyte-to-monocyte ratio (0.52 [-0.81 to -0.23]; P = .0005; I2 = 52%) tended to be significantly lower in patients with MetS.

CONCLUSION

Biomarkers such as total leukocyte count, neutrophil count, lymphocyte count, basophil count, monocyte count and neutrophil-to-lymphocyte ratio are associated with higher levels in patients in MetS and thus can potentially be used for early detection of MetS.

Obesity-related asthma and its relationship with microbiota

Obesity and asthma are global public health problems. Obesity-related asthma is a special phenotype of asthma with a complex pathogenesis. Its occurrence and development are related to mechanical compression, inflammatory response, metabolic regulation, gene regulation, and vitamin D deficiency. Different treatment strategies used in the process of weight loss have a beneficial impact on asthma. Alterations in gut and airway microbial community structure and their metabolites may also contribute to obesity-related asthma. The role of the Th17/Treg balance in the gut microbiota regulating the immune responses and host metabolism is important. Therapeutic measures associated with the gut microbiota variety may contribute to improving chronic inflammation associated with obesity by regulating the Th17/Treg balance. An early reduction in microbial diversity can predict the development of asthma and lead to allergy through an imbalance of Th2/Th1 responses. Short-chain fatty acids (SCFAs) regulate the differentiation and activation of regulatory T cells, thereby regulating immune homeostasis in the lung to suppress allergic inflammation and weight gain. Therefore, clarifying the microbial mechanism of obesity-related asthma has important guiding significance for clinical treatment. In this review, we used the following terms: "asthma and obesity" and "obesity-related asthma", combining "phenotype", "airway inflammation" and "lung function", and reviewed the characteristics and pathogenesis of obesity-related asthma, the relationship between the gut and airway microbiota and obesity-related asthma, and the current treatment measures for the disease.

Pulmonary Function in Metabolic Syndrome: A Meta-Analysis

Background: This study aims to systematically evaluate the association between metabolic syndrome (MS) and pulmonary function through meta-analysis. Methods: Electronic databases, including PubMed, Embase, Web of Science, and Cochrane Library, were systematically searched to obtain articles associated with MS and lung function published before December 31, 2021. According to the including and excluding criteria, certain studies were obtained and data were extracted. The Newcastle Ottawa Scale was used to evaluate the quality of the studies. A pooled standardized mean difference (SMD) was calculated by means of random-effects meta-analysis. Different effect models were used according to the heterogeneity. Meta-regression and sensitivity analyses were performed to examine the possible sources of heterogeneity. The Begg's funnel plot and Egger's test were used to evaluate publication bias. Analyses were performed using Stata MP, version14.0 (StataCorp LP, College Station, TX, USA). Results: A total of 15 studies, involving 10,285 cases of MS and 25,416 cases of control, were included in this meta-analysis on the relationship between MS and forced vital capacity (FVC). The pooled SMD for FVC was -0.247 (95% CI = -0.327 to -0.2167, P < 0.001) using random effect model, indicating the decrease of FVC in the patients with MS. In the same studies, the pooled SMD for forced expiratory volume in 1 sec (FEV₁) was -0.205 (95% CI = -0.3278 to -0.133, P < 0.001), indicating the decrease of FEV₁ also existed in the MS cases. A total of 13 studies, involving 8167 cases of MS and 19,788 cases of control, were included in this meta-analysis on the relationship between MS and FEV₁/FVC. The pooled SMD for FEV₁/FVC was 0.011 (95% CI = -0.072 to 0.093, P = 0.798) using random effect model, indicating that there was no significant difference between the patients with MS and the control. After introducing the diastolic blood pressure and glycemia into the regression model of the relationship between MS and FVC, the variance of the studies (tau2) decreased from 0.0190 to 0.006694 and 0.007205, which could explain 66.70% and 78.04% of the sources of heterogeneity, and the P values were 0.038 and 0.023. The results suggested that hypertension (diastolic pressure) and hyperglycemia were the factors linked to the heterogeneity among the included studies on both FVC and FEV₁. The Begg's funnel plot and Egger's test both showed no evidence of publication bias. Conclusions: Our results show that FVC and FEV₁ decrease in MS patients, while FEV₁/FVC has no significant difference compared with the control group. It indicates that the patients with MS have restrictive ventilatory functional disturbance. Meta-regression analysis suggests that hypertension (diastolic pressure) and hyperglycemia are the factors linked to the heterogeneity among the included studies on both FVC and FEV₁.

Influence of cardiovascular risk burden on pulmonary function trajectory: role of physical and social activities

The impact of cardiovascular risk burden on long-term trajectories of pulmonary function (PF) remains unclear. We examined the association of cardiovascular risk burden assessed by Framingham general cardiovascular risk score (FGCRS) with PF decline and explored whether cardiovascular diseases (CVD), physical and social activities play a role in the association. Within the Rush Memory and Aging Project, 1,442 participants (mean age:79.83) were followed up to 22 years. FGCRS at baseline was calculated and categorized into tertiles. Composite PF was measured annually based on peak expiratory flow, forced expiratory volume in one second, and forced vital capacity. We found that the highest FGCRS was associated with faster PF decline (β: -0.013, 95% CI: -0.023 to -0.003) compared with the lowest FGCRS. There were significant interactions between higher FGCRS and low level of physical/social activity (β: -0.014, 95% CI: -0.026 to -0.003)/(β: -0.020, 95% CI:-0.031 to -0.009) or CVD(β: -0.023, 95% CI:-0.034 to -0.011) compared to the low FGCRS with high level of physical/social activity or without CVD (P-interaction<0.05). Our results suggest that higher cardiovascular risk burden is associated with a faster PF decline, especially among people with CVD. High level of physical activity and social activity appears to mitigate this association.

Clinical Characteristics and Management Strategies for Adult Obese Asthma Patients

The rates of asthma and obesity are increasing concurrently in the United States. Epidemiologic studies demonstrate that the incidence of asthma increases with obesity. Furthermore, obese individuals have asthma that is more severe, harder to control, and resistant to standard medications. In fact, specific asthma-obesity phenotypes have been identified. Various pathophysiologic mechanisms, including mechanical, inflammatory, metabolic and microbiome-associated, are at play in promulgating the obese-asthma phenotypes. While standard asthma medications, such as inhaled corticosteroids and biologics, are currently used to treat obese asthmatics, they may have limited effectiveness. Targeting the underlying aberrant processes, such as addressing steroid resistance, microbiome, metabolic and weight loss approaches, may be helpful.

Determinants of Longitudinal Change of Lung Function in Different Gender in a Large Taiwanese Population Follow-Up Study Categories: Original Investigation

Chronic lung disease is associated with tremendous social and economic burden worldwide. The aim of this study was to investigate the sex-specific risk factors for changes in lung function in a large longitudinal study. We included 9059 participants from the Taiwan Biobank. None of the participants had a history of smoking, asthma, emphysema or bronchitis. Lung function was assessed using spirometry measurements of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). Change in the FEV1/FVC (ΔFEV1/FVC) was calculated as a follow-up FEV1/FVC minus baseline FEV1/FVC. Linear regression analysis was used to identify associations between variables and ΔFEV1/FVC in the male and female participants. After multivariable adjustments, the male participants (vs. females; p = 0.021) were significantly associated with a low ΔFEV1/FVC. In addition, the male participants with low aspartate aminotransferase (AST) (p = 0.003), high alanine aminotransferase (ALT) (p = 0.006) and a low estimated glomerular filtration rate (eGFR) (p = 0.003) were significantly associated with a low ΔFEV1/FVC. For the female participants, low systolic blood pressure (p = 0.005), low diastolic blood pressure (p = 0.031), low AST (p < 0.001), high ALT (p < 0.001) and a low eGFR (p = 0.001) were significantly associated with a low ΔFEV1/FVC. In this large follow-up study, we found that the male participants had a faster decrease in the FEV1/FVC than the female participants. In addition, liver and renal functions were correlated with changes in lung function in both the male and female participants. Our findings provide useful information on sex-specific changes in lung function.

Adult but not childhood onset asthma is associated with the metabolic syndrome, independent from body mass index

INTRODUCTION

Adult-onset asthma (AOA) is usually more severe compared to childhood onset asthma (CoA). Given the increasing evidence that AoA is associated with obesity, we investigated the relationship of other related metabolic comorbid conditions with AoA compared to CoA.

STUDY DESIGN AND METHODS

This cross-sectional study compared the metabolic syndrome and lipid derived inflammatory markers in patients with AoA, CoA and age- and sex-matched control subjects without asthma. Participants were asthma patients visiting the outpatient clinic of two teaching hospitals in Rotterdam, The Netherlands. All participants underwent lung function tests, blood tests and physical activity tracking. AoA was defined as asthma age of onset after the age of 18 years. Metabolic syndrome was defined according to the international joint interim statement criteria.

RESULTS

Eighty-one participants were included (27 AoA, 25 CoA, 29 controls). AoA was associated with the metabolic syndrome (Odds Ratio = 3.64 95% CI (1.16-11.42) p = 0.03, Nagelkerke R² = 0.26), adjusted for age, sex, body mass index and smoking habits. AoA patients had higher median serum IL-6 and leptin-adiponectin (LA) ratio compared to controls (IL-6 (pg/mL): 3.10 [1.11-4.30] vs. 1.13 [0.72-1.58], p = 0.002 and LA ratio (pg/mL): 6.21 [2.45-14.11] vs. 2.24 [0.67-4.71], p = 0.0390). This was not observed in CoA and controls.

CONCLUSION

AoA was associated with the metabolic syndrome and its related pro-inflammatory endocrine and cytokine status. This may suggest adipose tissue derived inflammatory markers play a role in the pathophysiology of AoA.

Pulmonary function changes in older adults with and without metabolic syndrome

The low-grade inflammation associated with metabolic syndrome (MS) triggers functional and structural alterations in several organs. Whereas lung function impairment is well reported for older adult population, the effect of MS on functional and immunological responses in the lungs remains unclear. In this cross-sectional study we determined whether MS alters pulmonary function, and immunological responses in older adults with MS. The study sample consisted of older adults with MS (68 ± 3 years old; n = 77) and without MS (67 ± 3 years old; n = 77). Impulse oscillometry was used to evaluate airway and tissue resistance, and reactance. Biomarkers of inflammation and fibrosis were assessed in the blood and in breath condensate. The total resistance of the respiratory system (R5Hz; p < 0.009), and the resistance of the proximal (R20Hz; p < 0.001) and distal (R5Hz–R20Hz; p < 0.004) airways were higher in MS individuals compared to those without MS. Pro-inflammatory (leptin, IL-1beta, IL-8, p < 0.001; TNF-alpha, p < 0.04) and anti-inflammatory cytokines (adiponectin, IL-1ra, IL-10, p < 0.001), anti-fibrotic (relaxin 1, relaxin 3, Klotho, p < 0.001) and pro-fibrotic (VEGF, p < 0.001) factors were increased in sera and in breath condensate individuals with MS. The results show that MS adversely affect lung mechanics, function, and immunological response in older adults. The data offer a metabolic basis for the inflammaging of the lungs and suggest the lungs as a potential therapeutic target for controlling the immune response and delaying the onset of impaired lung function in older adults with MS.

A Comparison of Length of Hospitalization and Costs in Obese and Non-Obese Pediatric Patients at a Single Hospital in Honolulu

The association of obesity with increased hospital costs and length of stay among hospitalized pediatric patients identified by ICD-9 coding may be underestimated due to underreporting of appropriate ICD-9 coding for obesity status. The objective of this study was to compare these lengths of stay and hospital costs. A retrospective chart review was conducted of pediatric patients admitted from May 2009 to January 2012 at Kapi'olani Medical Center, Honolulu, Hawai'i, with the 20 most common primary admission diagnosis ICD-9 codes. Length of hospital stay and total hospital costs were compared for obese, overweight, and normal-weight patients based on body mass index (BMI), controlling for age, sex, ethnicity, insurance type, diagnosis, and calendar year using logistic regression. Analysis of 730 patients showed 1% of overweight patients and 35% of obese patients were correctly coded with the corresponding ICD-9 code for weight status. Obese patients had 15% longer hospital stays and 19% higher hospital costs than normal weight patients, when controlled for age, sex, ethnicity, insurance type, calendar year, and primary diagnosis. Subgroup analyses of the top 3 most common primary admission diagnoses showed obese patients with asthma had significantly higher hospital costs than normal weight patients. Obesity is an independent risk factor for increasing hospital resource utilization in hospitalized pediatric patients. Documentation of ICD-9 codes for overweight and obesity in this cohort drastically underrepresented the true prevalence of obesity and overweight status in this sample of hospitalized children. Further research is needed to better understand the complex role of obesity in pediatric inpatients, particularly among those with asthma.

Metabolic syndrome and lung function in Korean children and adolescents: A cross-sectional study

This study aimed to investigate whether obesity and metabolic syndrome (MetS) are associated with pulmonary function in Korean children and adolescents. Data from the 2009–2011 Korea National Health and Nutrition Examination Survey which is cross-sectional, nationwide, and representative survey were used. Adjusted regression analysis was performed to evaluate the association of obesity and MetS with lung function in children and adolescents. A total of 763 children and adolescents aged 10–18 years were evaluated. We found no significant difference in FEV₁% predicted, FVC% predicted, and FEV₁/FVC ratio among the obesity groups. Subjects with MetS showed a significantly lower FEV₁ predicted (91.54 ± 0.74% vs 94.64 ± 0.73%, P = 0.004), lower FVC% predicted (91.86 ± 0.63% vs 95.20 ± 0.63%, P < 0.001), and lower FEV₁/FVC ratio (76.76 ± 0.43% vs 80.13 ± 0.43%, P < 0.001) than those without MetS. Elevated waist circumference (WC), systolic blood pressure, fasting glucose, and lower high-density lipoprotein cholesterol (HDL-C) were independently associated with lower FEV₁/FVC ratio (all P < 0.05, respectively). Among MetS components, increased WC was the most important factor influencing lower FEV₁/FVC ratio. In conclusion, lung function in MetS patients was significantly lower, and the MetS component was independently associated.

A possible association between fructose consumption and pulmonary emphysema

Chronic Obstructive Pulmonary Disease (COPD) is a syndrome that comprises several distinct and overlapping phenotypes. In addition to persistent airflow limitation and respiratory symptoms, COPD is also characterized by chronic systemic inflammation. Epidemiological studies have shown that dietary fibers, fruits and vegetables intake protects against the COPD development, while fructose-loading is associated with increased risk of asthma and chronic bronchitis. Since dietary factors might affect susceptibility to COPD by modulating oxidative stress and inflammatory responses, we evaluated how fructose feeding might affect the smoking-induced emphysema in mice. We found that chronic fructose intake induced destruction and remodeling of lung parenchyma and impairment of respiratory mechanics, which are associated with distinctive cytokine profiles in bronchoalveolar lavage fluid, blood plasma and skeletal muscle. The combined effects of chronic fructose intake and cigarette smoking on destruction of lung parenchyma are more pronounced than the effects of either alone. Excessive intake of fructose might directly cause pulmonary emphysema in mice rather than just altering its natural history by facilitating the installation of a low-grade systemic inflammatory milieu.

Systemic Inflammation in Metabolic Syndrome: Increased Platelet and Leukocyte Activation, and Key Role of CX3CL1/CX3CR1 and CCL2/CCR2 Axes in Arterial Platelet-Proinflammatory Monocyte Adhesion

BACKGROUND

Metabolic syndrome is associated with low-grade systemic inflammation, which is a key driver of premature atherosclerosis. We characterized immune cell behavior in metabolic syndrome, its consequences, and the potential involvement of the CX₃CL1/CX₃CR1 and CCL2/CCR2 chemokine axes.

METHODS

Whole blood from 18 patients with metabolic syndrome and 21 age-matched controls was analyzed by flow cytometry to determine the leukocyte immunophenotypes, activation, platelet-leukocyte aggregates, and CX₃CR1 expression. ELISA determined the plasma marker levels. Platelet-leukocyte aggregates adhesion to tumor necrosis factor-α (TNFα)-stimulated arterial endothelium and the role of CX₃CL1/CX₃CR1 and CCL2/CCR2 axes was investigated with the parallel-plate flow chamber.

RESULTS

When compared with the controls, the metabolic syndrome patients presented greater percentages of eosinophils, CD3⁺ T lymphocytes, Mon2/Mon3 monocytes, platelet-eosinophil and -lymphocyte aggregates, activated platelets, neutrophils, eosinophils, monocytes, and CD8⁺ T cells, but lower percentages of Mon1 monocytes. Patients had increased circulating interleukin-8 (IL-8) and TNFα levels and decreased IL-4. CX₃CR1 up-regulation in platelet-Mon1 monocyte aggregates in metabolic syndrome patients led to increased CX₃CR1/CCR2-dependent platelet-Mon1 monocyte adhesion to dysfunctional arterial endothelium.

CONCLUSION

We provide evidence of generalized immune activation in metabolic syndrome. Additionally, CX₃CL1/CX₃CR1 or CCL2/CCR2 axes are potential candidates for therapeutic intervention in cardiovascular disorders in metabolic syndrome patients, as their blockade impairs the augmented arterial platelet-Mon1 monocyte aggregate adhesiveness, which is a key event in atherogenesis.

Metabolic Syndrome and Pulmonary Function Indices

Background and aims: Metabolic syndrome (MetS) is a collection of metabolic risk factors including increased waist circumference (WC), elevated blood pressure (BP), increased triglyceride (TG), decreased high density lipoprotein (HDL-C) and increased fasting blood sugar (FBS). We aimed to examine the relevance between the MetS and its components with reduced lung functions in adult men.

Material and method: A total of 3899 adult men underwent screening examination between 2015-2016 in a cross-sectional survey.

Results: The mean (± SD) age of our population was 37.25 (± 4.9) years. The overall prevalence of MetS was 7.6%. The total prevalence of reduced lung function in men with MetS was 13.8%. The most common type of reduced lung function was the restrictive pattern (7.1%). The forced expiratory volume of first second (FEV1) and forced vital capacity (FVC) values were significantly lower in men with MetS (both p<0.001). Also these values were significantly lower in diabetic men compared to non-diabetics and those with impaired fasting glucose (IFG). WC and HDL were the most potent predictors of reduced FEV1 and FVC.

Conclusions: We obtained a positive independent association between MetS and reduced lung function in adult men which may be related mainly due to increased WC and decreased HDL.

High Concentration of Insulin Induces MUC5AC Expression via Phosphoinositide 3 Kinase/AKT and Mitogen-activated Protein Kinase Signaling Pathways in Human Airway Epithelial Cells

Background Insulin is involved in a glucose homeostatic regulation and a cellular metabolism via phosphorylation of phosphoinositide 3 kinase (PI3K) pathway and mitogen-activated protein kinase (MAPK) pathway. Hyperinsulinemia reduces insulin sensitivity and is an obvious potential factor affecting airway inflammation in chronic airway diseases. MUC5AC is a major secreted mucin, which plays a critical role in inflammatory response in the respiratory tract. However, the relationship between insulin and MUC5AC expression has not been studied. Objective This study investigated the effect and the brief signaling pathway of high concentration of insulin (HI) on MUC5AC expression in human airway epithelial cell. Methods In NCI-H292 cells and primary cultures of normal nasal epithelial cells, the effect and signaling pathway of HI on MUC5AC expression were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with several specific inhibitors and small interfering RNA (siRNA). Results HI significantly increased MUC5AC expression and activated PI3K/AKT, extracellular signal-related kinase 1/2 (ERK1/2) and p38 MAPKs. The specific PI3K and AKT inhibitor as well as knockdown of AKT1 and AKT2 by the respective siRNAs significantly blocked HI-mediated expression of MUC5AC. Meanwhile, the specific ERK1/2 MAPK and p38 MAPK inhibitor as well as knockdown of ERK1, ERK2, and p38 MAPK by the respective siRNAs also attenuated HI-induced expression of MUC5AC. Conclusion The results of this study suggest that HI induces MUC5AC expression via PI3K/AKT and MAPK signaling pathways in human airway epithelial cells.

Pediatric metabolic outcome comparisons based on a spectrum of obesity and asthmatic symptoms

RATIONALE

Asthma and obesity are 2 of the most prevalent public health issues for children in the U.S. Trajectories of both have roughly paralleled one another over the past several decades causing many to explore their connection to one another and to other associated health issues such as diabetes and dyslipidemia. Earlier models have commonly designated obesity as the central hub of these associations; however, more recent models have argued connections between pediatric asthma and other obesity-related metabolic conditions regardless of children's obesity risk.

OBJECTIVES

To examine the relationships between asthma, obesity, and abnormal metabolic indices.

METHODS

We conducted a cross-sectional study of 179 children ages 7 to 12 years recruited from a rural, Appalachian region. Our model controlled for children's smoke exposure, body mass index percentile, and gender to examine the association between children's asthma (based on pulmonary function tests, medical history, medications, and parent report of severity), lipids (fasting lipid profile), and measures of altered glucose metabolism (glycosylated hemoglobin and homeostatic model assessment 2-insulin resistance).

RESULTS

Our findings revealed a statistically significant model for low density lipids, high density lipids, log triglyceride, and homeostatic model assessment 2-insulin resistance; however, Asthma had a significant effect for the mean triglycerides. We also found an asthma-obesity interaction effect on children's glycosylated hemoglobin with asthmatic obese children revealing significantly higher glycosylated hemoglobin values than non-asthmatic obese children.

CONCLUSIONS

Our findings support a connection between asthma and children's glycosylated hemoglobin values; however, this association remains entwined with obesity factors.

Surfactant Protein D in Respiratory and Non-Respiratory Diseases

Surfactant protein D (SP-D) is a multimeric collectin that is involved in innate immune defense and expressed in pulmonary, as well as non-pulmonary, epithelia. SP-D exerts antimicrobial effects and dampens inflammation through direct microbial interactions and modulation of host cell responses via a series of cellular receptors. However, low protein concentrations, genetic variation, biochemical modification, and proteolytic breakdown can induce decomposition of multimeric SP-D into low-molecular weight forms, which may induce pro-inflammatory SP-D signaling. Multimeric SP-D can decompose into trimeric SP-D, and this process, and total SP-D levels, are partly determined by variation within the SP-D gene, SFTPD. SP-D has been implicated in the development of respiratory diseases including respiratory distress syndrome, bronchopulmonary dysplasia, allergic asthma, and chronic obstructive pulmonary disease. Disease-induced breakdown or modifications of SP-D facilitate its systemic leakage from the lung, and circulatory SP-D is a promising biomarker for lung injury. Moreover, studies in preclinical animal models have demonstrated that local pulmonary treatment with recombinant SP-D is beneficial in these diseases. In recent years, SP-D has been shown to exert antimicrobial and anti-inflammatory effects in various non-pulmonary organs and to have effects on lipid metabolism and pro-inflammatory effects in vessel walls, which enhance the risk of atherosclerosis. A common SFTPD polymorphism is associated with atherosclerosis and diabetes, and SP-D has been associated with metabolic disorders because of its effects in the endothelium and adipocytes and its obesity-dampening properties. This review summarizes and discusses the reported genetic associations of SP-D with disease and the clinical utility of circulating SP-D for respiratory disease prognosis. Moreover, basic research on the mechanistic links between SP-D and respiratory, cardiovascular, and metabolic diseases is summarized. Perspectives on the development of SP-D therapy are addressed.

Association between body mass index (BMI) and vital capacity of college students of Zhuang nationality in China: a cross-section study

Objective

Our study is to evaluate the association between body mass index (BMI) and vital capacity of college students of Zhuang Nationality in China.

Methods

463 college students of Zhuang Nationality from Guangxi Medical University were selected. Basic information, body composition and vital capacity of college students were measured. According to the level of BMI, college students were divided into four groups (BMI<18.5, 18.5≤BMI<23.9, 23.9≤BMI<27.9 and BMI≥27.9). Multivariate logistic regression analysis was performed to assess the association between BMI and vital capacity.

Results

In male college students, there was no significant difference in vital capacity between the four groups (3029.54±869.25, 3347.06±784.54, 3540.00±805.35 and 3966.50±350.2, P=0.0727, respectively). Multivariate regression analysis showed that after adjusting for confounding factors, no significant association was observed between BMI and vital capacity (OR=115.02, 95% CI: -555.58∼785.63; OR=-166.58, 95% CI: -1684.56∼1351.41; OR=-484.01, 95% CI:-3504.53, 2536.51, respectively. BMI<18.5 group served as reference group). In female college students, there was also no significant difference in vital capacity between the four groups (2455.15±574.4, 2555.06±637.03, 2750.33±1224.05 and 2473.00±159.06, P=0.4011, respectively). Multivariate regression analysis showed that after adjusting for confounding factors, no significant association was observed between BMI and vital capacity (OR=-88.88, 95% CI: -333.59∼155.84; OR=20.00, 95% CI: -694.39∼734.39; OR=2.86, 95% CI: -1830.58, 1836.3, respectively. BMI<18.5 group served as reference group).

Conclusion

There was no evidence that BMI is associated with vital capacity in college students of Zhuang Nationality.

Obesity and Asthma: A Missing Link

Obesity and asthma are two chronic conditions that affect millions of people. Genetic and lifestyle factors such as diet, physical activity, and early exposure to micro-organisms are important factors that may contribute to the escalating prevalence of both conditions. The prevalence of asthma is higher in obese individuals. Recently, two major phenotypes of asthma with obesity have been described: one phenotype of early-onset asthma that is aggravated by obesity, and a second phenotype of later-onset asthma that predominantly affects women. Systemic inflammation and mechanical effect, both due to the expansion of the adipose tissue, have been proposed as the main reasons for the association between obesity and asthma. However, the mechanisms involved are not yet fully understood. Moreover, it has also been suggested that insulin resistance syndrome can have a role in the association between these conditions. The intestinal microbiota is an important factor in the development of the immune system, and can be considered a link between obesity and asthma. In the obese state, higher lipopolysaccharide (LPS) serum levels as a consequence of a microbiota dysbiosis have been found. In addition, changes in microbiota composition result in a modification of carbohydrate fermentation capacity, therefore modifying short chain fatty acid (SCFA) levels. The main objective of this review is to summarize the principal findings that link obesity and asthma.

Metabolic Syndrome Is Associated with Increased Oxo-Nitrative Stress and Asthma-Like Changes in Lungs

Epidemiological studies have shown an increased obesity-related risk of asthma. In support, obese mice develop airway hyperresponsiveness (AHR). However, it remains unclear whether the increased risk is a consequence of obesity, adipogenic diet, or the metabolic syndrome (MetS). Altered L-arginine and nitric oxide (NO) metabolism is a common feature between asthma and metabolic syndrome that appears independent of body mass. Increased asthma risk resulting from such metabolic changes would have important consequences in global health. Since high-sugar diets can induce MetS, without necessarily causing obesity, studies of their effect on arginine/NO metabolism and airway function could clarify this aspect. We investigated whether normal-weight mice with MetS, due to high-fructose diet, had dysfunctional arginine/NO metabolism and features of asthma. Mice were fed chow-diet, high-fat-diet, or high-fructose-diet for 18 weeks. Only the high-fat-diet group developed obesity or adiposity. Hyperinsulinemia, hyperglycaemia, and hyperlipidaemia were common to both high-fat-diet and high-fructose-diet groups and the high-fructose-diet group additionally developed hypertension. At 18 weeks, airway hyperresponsiveness (AHR) could be seen in obese high-fat-diet mice as well as non-obese high-fructose-diet mice, when compared to standard chow-diet mice. No inflammatory cell infiltrate or goblet cell metaplasia was seen in either high-fat-diet or high-fructose-diet mice. Exhaled NO was reduced in both these groups. This reduction in exhaled NO correlated with reduced arginine bioavailability in lungs. In summary, mice with normal weight but metabolic obesity show reduced arginine bioavailability, reduced NO production, and asthma-like features. Reduced NO related bronchodilation and increased oxo-nitrosative stress may contribute to the pathogenesis.

Alveolar-capillary adaptation to chronic hypoxia in the fatty lung

AIM

Obese diabetic (ZDF fa/fa) rats with genetic leptin resistance suffer chronic lipotoxicity associated with age-related lung restriction and abnormal alveolar ultrastructure. We hypothesized that these abnormalities impair adaptation to ambient hypoxia.

METHODS

Male fa/fa and lean (+/+) ZDF rats (4-months old) were exposed to 21 or 13% O2 for 3 weeks. Lung function was measured under anaesthesia. Lung tissue was assayed for DNA damage and ultrastructure measured by morphometry.

RESULTS

In normoxia, lung volume, compliance and diffusing capacity were lower, while blood flow was higher in fa/fa than +/+ rats. In hypoxia, fa/fa animals lost more weight, circulating hematocrit rose higher, and lung volume failed to increase compared to +/+. In fa/fa, the hypoxia-induced increase in post-mortem lung volume was attenuated (19%) vs. +/+ (39%). Alveolar ducts were 35% smaller in normoxia but enlarged twofold more in hypoxia compared to +/+. Hypoxia induced broad increases (90-100%) in the volumes and surface areas of alveolar septal components in +/+ lungs; these increases were moderately attenuated in fa/fa lungs (58-75%), especially that of type II epithelium volume (16 vs. 61% in +/+). In fa/fa compared to +/+ lungs, oxidative DNA damage was greater with increased hypoxia induced efflux of alveolar macrophages. Harmonic mean thickness of the diffusion barrier was higher, indicating higher structural resistance to gas transfer.

CONCLUSION

Chronic lipotoxicity impaired hypoxia-induced lung expansion and compensatory alveolar growth with disproportionate effect on resident alveolar progenitor cells. The moderate structural impairment was offset by physiological adaptation primarily via a higher hematocrit.

Insulin resistance, metabolic syndrome, and lung function in US adolescents with and without asthma

BACKGROUND

Obesity increases both the risk of asthma and asthma severity and is a well-known risk factor for insulin resistance and the metabolic syndrome (MS) in children and adolescents.

OBJECTIVE

We aimed to examine the association among obesity, insulin sensitivity, MS, and lung function in US adolescents with and without asthma.

METHODS

We performed a cross-sectional study of 1429 adolescents aged 12 to 17 years in the 2007-2010 National Health and Nutrition Examination Survey. Adjusted regression was used to assess the relationships among obesity, insulin sensitivity/resistance, MS, and lung function in children with and without asthma.

RESULTS

Insulin resistance was negatively associated with FEV1 and forced vital capacity (FVC) in adolescents with and without asthma, whereas MS was associated with lower FEV1/FVC ratios, with a more pronounced decrease found among asthmatic patients; these associations were driven by overweight/obese adolescents. Higher body mass index was associated with a decrease in FEV1/FVC ratios among adolescents with insulin resistance. Compared with healthy participants, adolescents with MS had an approximately 2% decrease in FEV1/FVC ratios, adolescents with asthma had an approximately 6% decrease, and those with MS and asthma had approximately 10% decreased FEV1/FVC ratios (P < .05).

CONCLUSION

Insulin resistance and MS are associated with worsened lung function in overweight/obese adolescents. Asthma and MS synergistically decrease lung function, as do obesity and insulin resistance. These factors might contribute to the pathogenesis of asthma severity in obese patients and warrant further investigation.

Association of metabolic syndrome and surgical factors with pulmonary adverse events, and longitudinal mortality in bariatric surgery

BACKGROUND

Postoperative pulmonary complications (PPC) in bariatric surgery have not been well studied. Additionally, many bariatric patients suffer from the metabolic syndrome (MetS), contributing to surgical risk. We examined the incidence of PPC and MetS in a large national bariatric database. Furthermore, we analysed the relationships between morbidity, mortality, PPC, MetS, and several other comorbidities and also surgical factors.

METHODS

The Bariatric Outcomes Longitudinal Database (BOLD™) is a registry that includes up to 365 day outcomes. We analysed data between January 2008 and October 2010. The PPC tracked included pneumonia, atelectasis, pleural effusion, pneumothorax, adult respiratory distress syndrome, and respiratory failure. A composite pulmonary adverse event (CPAE) included the occurrence of any of these. MetS was defined as the combination of hypertension, dyslipidaemia, and diabetes mellitus. The association of MetS and additional comorbibities, procedural data, and patient characteristics with CPAEs was examined with appropriate statistical tests.

RESULTS

A total of 158 405 patients had a low incidence of PPC (0.91%) and a low mortality (0.6%) after bariatric surgery. MetS was prevalent in 12.7%, and was a significant risk factor for CPAE and mortality. Age, BMI, ASA physical status classification, surgical duration, procedure type, MetS (P<0.001), and additional comorbidities were significantly associated with CPAEs.

CONCLUSIONS

The incidence of PPC was low after bariatric surgery. Increasing age, BMI, ASA status, MetS, obstructive sleep apnoea, asthma, congestive heart failure, surgical duration, and procedure type were independently significantly associated with PPC. Pulmonary complications and MetS were significantly associated with increased postoperative mortality.

The systemic inflammome of severe obesity before and after bariatric surgery

Introduction

Obesity is associated with low-grade systemic inflammation. The “inflammome” is a network layout of the inflammatory pattern. The systemic inflammome of obesity has not been described as yet. We hypothesized that it can be significantly worsened by smoking and other comorbidities frequently associated with obesity, and ameliorated by bariatric surgery (BS). Besides, whether or not these changes are mirrored in the lungs is unknown, but obesity is often associated with pulmonary inflammation and bronchial hyperresponsiveness.

Objectives

We sought to: (1) describe the systemic inflammome of morbid obesity; (2) investigate the effects of sex, smoking, sleep apnea syndrome, metabolic syndrome and BS upon this systemic inflammome; and, (3) determine their interplay with pulmonary inflammation.

Methods

We studied 129 morbidly obese patients (96 females; age 46±12 years; body mass index [BMI], 46±6 kg/m²) before and one year after BS, and 20 healthy, never-smokers, (43±7 years), with normal BMI and spirometry.

Results

Before BS, compared with controls, all obese subjects displayed a strong and coordinated (inflammome) systemic inflammatory response (adiponectin, C-reactive protein, interleukin (IL)-8, IL-10, leptin, soluble tumor necrosis factor-receptor 1(sTNF-R1), and 8-isoprostane). This inflammome was not modified by sex, smoking, or coexistence of obstructive sleep apnea and/or metabolic syndrome. By contrast, it was significantly ameliorated, albeit not completely abolished, after BS. Finally, obese subjects had evidence of pulmonary inflammation (exhaled condensate) that also decreased after BS.

Conclusions

The systemic inflammome of morbid obesity is independent of sex, smoking status and/or comorbidities, it is significantly reduced by BS and mirrored in the lungs.

Effect of exercise test on pulmonary function of obese adolescents

OBJECTIVE

to investigate the pulmonary response to exercise of non-morbidly obese adolescents, considering the gender.

METHODS

a prospective cross-sectional study was conducted with 92 adolescents (47 obese and 45 eutrophic), divided in four groups according to obesity and gender. Anthropometric parameters, pulmonary function (spirometry and oxygen saturation [SatO2]), heart rate (HR), blood pressure (BP), respiratory rate (RR), and respiratory muscle strength were measured. Pulmonary function parameters were measured before, during, and after the exercise test.

RESULTS

BP and HR were higher in obese individuals during the exercise test (p = 0.0001). SatO2 values decreased during exercise in obese adolescents (p = 0.0001). Obese males had higher levels of maximum inspiratory and expiratory pressures (p = 0.0002) when compared to obese and eutrophic females. Obese males showed lower values of maximum voluntary ventilation, forced vital capacity, and forced expiratory volume in the first second when compared to eutrophic males, before and after exercise (p = 0.0005). Obese females had greater inspiratory capacity compared to eutrophic females (p = 0.0001). Expiratory reserve volume was lower in obese subjects when compared to controls (p ≤ 0,05).

CONCLUSION

obese adolescents presented changes in pulmonary function at rest and these changes remained present during exercise. The spirometric and cardiorespiratory values were different in the four study groups. The present data demonstrated that, in spite of differences in lung growth, the model of fat distribution alters pulmonary function differently in obese female and male adolescents.

Female asthma has a negative effect on fertility: what is the connection?

Reproductive changes such as impaired fertility and adverse pregnancy outcomes have been related to female asthma. We recently found that time to pregnancy is prolonged in asthmatic females especially in women with moderate to severe asthma and in those above 30 years of age. Despite their reproductive difficulties the asthmatics ultimately conceived just as many biological children as healthy throughout their reproductive lives. This knowledge therefore raises questions about how asthma affects fertility pathophysiologically. The purpose of this review is to describe the existing knowledge in this field and suggest hypotheses of causal relationships, which may form the basis for future studies in this field. The aim is, in particular, in the literature to examine whether there is any evidence to suggest that the systemic inflammation that characterizes asthma, can affect fertility. The issue is potentially clinically important for asthmatic, infertile individuals and society because treatment of the general systemic inflammation associated with the asthmatic disease combined with hormone stimulation might be the optimal target for an effective infertility therapy, possibly decreasing the need for in vitro fertilization.