Risk of asthma in adult twins with type 2 diabetes and increased body mass index

Unraveling the Link between Ιnsulin Resistance and Bronchial Asthma

Evidence from large epidemiological studies has shown that obesity may predispose to increased Th2 inflammation and increase the odds of developing asthma. On the other hand, there is growing evidence suggesting that metabolic dysregulation that occurs with obesity, and more specifically hyperglycemia and insulin resistance, may modify immune cell function and in some degree systemic inflammation. Insulin resistance seldom occurs on its own, and in most cases constitutes a clinical component of metabolic syndrome, along with central obesity and dyslipidemia. Despite that, in some cases, hyperinsulinemia associated with insulin resistance has proven to be a stronger risk factor than body mass in developing asthma. This finding has been supported by recent experimental studies showing that insulin resistance may contribute to airway remodeling, promotion of airway smooth muscle (ASM) contractility and proliferation, increase of airway hyper-responsiveness and release of pro-inflammatory mediators from adipose tissue. All these effects indicate the potential impact of hyperinsulinemia on airway structure and function, suggesting the presence of a specific asthma phenotype with insulin resistance. Epidemiologic studies have found that individuals with severe and uncontrolled asthma have a higher prevalence of glycemic dysfunction, whereas longitudinal studies have linked glycemic dysfunction to an increased risk of asthma exacerbations. Since the components of metabolic syndrome interact with one another so much, it is challenging to identify each one's specific role in asthma. This is why, over the last decade, additional studies have been conducted to determine whether treatment of type 2 diabetes mellitus affects comorbid asthma as shown by the incidence of asthma, asthma control and asthma-related exacerbations. The purpose of this review is to present the mechanism of action, and existing preclinical and clinical data, regarding the effect of insulin resistance in asthma.

Type 2 Diabetes Mellitus and Asthma: Pathomechanisms of Their Association and Clinical Implications

Type 2 diabetes mellitus (T2DM) and asthma are chronic illnesses concomitantly present in a significant percentage of the population. Their comorbidity is associated with poor disease control and lower quality of life, thus imposing a substantial medical and economic burden worldwide. This review investigates the association between asthma and T2DM, in terms of pathogenesis, clinical outcomes, and therapeutic opportunities. Our review found an increased risk of asthma among diabetics, and vice versa. Having diabetes and poor glycemic control is associated with an increased rate of asthma exacerbations and increased mortality among those hospitalized for asthma exacerbations. The mechanisms postulated for the diabetes-asthma association include chronic low-grade inflammation, obesity, hyperinsulinemia, and possibly diabetic pneumopathy. Usage of metformin, which is the first-line drug for type 2 diabetes, was found to be associated with a decreased asthma occurrence, asthma exacerbations, and asthma-related hospitalizations. Glucagon-like peptide 1 receptor agonists were also found to be associated with a lower occurrence of asthma exacerbations. Thiazolidinediones are also associated with lower rates of asthma exacerbations, but their clinical efficacy for the same was suggested to be limited. This literature review supports a partly causative association between asthma and diabetes. This comorbidity leads to poor patient compliance, worse disease outcomes, and poor quality of life. Thus, further studies are warranted to explore the prognostic implications, therapeutic opportunities, and specific clinical practice algorithms for patients with concurrent asthma and type 2 diabetes mellitus.

Multi-ancestry meta-analysis of asthma identifies novel associations and highlights the value of increased power and diversity

Asthma is a complex disease that varies widely in prevalence across populations. The extent to which genetic variation contributes to these disparities is unclear, as the genetics underlying asthma have been investigated primarily in populations of European descent. As part of the Global Biobank Meta-analysis Initiative, we conducted a large-scale genome-wide association study of asthma (153,763 cases and 1,647,022 controls) via meta-analysis across 22 biobanks spanning multiple ancestries. We discovered 179 asthma-associated loci, 49 of which were not previously reported. Despite the wide range in asthma prevalence among biobanks, we found largely consistent genetic effects across biobanks and ancestries. The meta-analysis also improved polygenic risk prediction in non-European populations compared with previous studies. Additionally, we found considerable genetic overlap between age-of-onset subtypes and between asthma and comorbid diseases. Our work underscores the multi-factorial nature of asthma development and offers insight into its shared genetic architecture.

The Interaction of Food Allergy and Diabetes: Food Allergy Effects on Diabetic Mice by Intestinal Barrier Destruction and Glucagon-like Peptide 1 Reduction in Jejunum

The increase in food allergies and diabetes leads to the assumption that they are related. This study aimed to (1) verify the interaction between food allergy and diabetes and (2) explore the potential mechanisms by which food allergy promotes diabetes. Female BALB/c mice were grouped into a control group (CK), an ovalbumin-sensitized group (OVA), a diabetes group (STZ), and a diabetic allergic group (STZ + OVA) (Mice were modeled diabetes with STZ first, then were given OVA to model food allergies), and an allergic diabetic group (OVA + STZ) (Mice were modeled food allergies with OVA first, then were given STZ to model diabetes). The results showed that OVA + STZ mice exhibited a more serious Th2 humoral response, and they were more susceptible to diabetes. Furthermore, when the OVA + STZ mice were in the sensitized state, the intestinal barrier function was severely impaired, and mast cell activation was promoted. Moreover, we found that the effect of food allergy on diabetes is related to the inhibition of GLP-1 secretion and the up-regulation of the PI3K/Akt/mTOR/NF-κB P65 signaling pathway in the jejunum. Overall, our results suggest that food allergies have interactions with diabetes, which sheds new light on the importance of food allergies in diabetes.

Metformin and the Development of Asthma in Patients with Type 2 Diabetes

We conducted this study to compare the risks of asthma development and exacerbation between metformin users and nonusers. Overall, 57,743 propensity score-matched metformin users and nonusers were identified from Taiwan’s National Health Insurance Research Database between 1 January 2000, and 31 December 2017. We used the Cox proportional hazards model with robust standard error estimates to compare the risks of asthma onset, exacerbation, and hospitalization for asthma in participants with type 2 diabetes (T2D). Compared with metformin nonuse, the aHRs (95% CI) for metformin use in asthma development, exacerbation, and hospitalization for asthma were 1.13 (1.06−1.2), 1.62 (1.35−1.95), and 1.5 (1.22−1.85), respectively. The cumulative incidences of asthma development, exacerbation, and hospitalization for asthma were significantly higher in metformin users than nonusers (p < 0.001). A longer cumulative duration of metformin use for more than 728 days was associated with significantly higher risks of outcomes than metformin nonuse. Our study demonstrated that metformin users showed significantly higher risks of asthma development, exacerbation, and hospitalization for asthma than metformin nonusers. Moreover, metformin use for more than 728 days was associated with higher risks of outcomes. A randomized control study is warranted to verify our results.

Asthma in Youth and Early-onset Type 2 Diabetes: A Nationwide Study of 1.72 Million Israeli Adolescents

BACKGROUND

The prevalence of both asthma and early-onset diabetes is on the rise; however, the association between them remains unclear. We examined a possible association of asthma at adolescence with type 2 diabetes in young adulthood.

METHODS

This is a nationwide, population-based study of 1 718 541 Israeli adolescents (57% males; mean age 17.3 years; range 16-19 years), examined before compulsory military service between 1992 and 2016, with data linked to the Israeli National Diabetes Registry. Asthma diagnosis and severity were determined by a board-certified pulmonologist and based on spirometry tests.

RESULTS

Type 2 diabetes developed in 58/9090 (0.64%), 507/97 059 (0.52%), 114/23 332 (0.49%), and 7095/1 589 060 (0.44%) persons with moderate-to-severe, mild, inactive, and no history of asthma, respectively, during a mean follow-up >13 years. The respective odds ratios (ORs) were 1.33 (95% CI, 1.02-1.74), 1.17 (1.06-1.28), and 1.09 (0.9-1.31), considering those without asthma history as the reference, in a model adjusted for birth year, sex, body mass index, and other sociodemographic variables. The association persisted when the analysis accounted for coexisting morbidities, and when persons without asthma, individually matched by age, sex, birth year, and body mass index were the reference. Both mild and moderate-to-severe asthma were associated with type 2 diabetes before age 35 years: ORs 1.18 (1.05-1.34) and 1.44 (1.05-2.00), respectively. The strength of the association was accentuated over time. The effect was unchanged when adjusted for oral and inhaled glucocorticoid use.

CONCLUSION

Adolescents with active asthma have higher risk to develop type 2 diabetes. This seems related to disease severity, independent of adolescent obesity status, apparent before age 35 years, and more pronounced in recent years.

Diabetes, insulin resistance, and asthma: a review of potential links

PURPOSE OF REVIEW

Disorders of glucose metabolism, including insulin resistance, prediabetes, and diabetes, have been identified as risk factors for worsened asthma. This review summarizes emerging evidence for their role as modifiable risk factors in asthma, including the potential benefit of diabetes medications on asthma outcomes.

RECENT FINDINGS

Experimental studies show that hyperinsulinemia associated with insulin resistance is associated with airway smooth muscle proliferation and promotes contractility. Epidemiologic studies have identified a higher prevalence of glycemic dysfunction among those with severe and uncontrolled asthma, and longitudinal studies have associated prediabetes and diabetes with higher risk of asthma exacerbations. The potential benefits of thiazolidinediones (TZDs), glucagon-like peptide-1 agonists, and metformin being investigated in asthma, but thus far interventional studies of TZDs have reported null results. On the contrary, observational studies have inconsistently controlled for relevant confounders which leaves conclusions vulnerable to misattribution of relationships due to corelated metabolic disorders, including dyslipidemia.

SUMMARY

Developing evidence suggests that disorders of glucose metabolism may be associated with worsening asthma. However, these conditions arise within a network of obesity-related metabolic diseases that may themselves worsen asthma. Few interventional trials have not identified a benefit, but data have been limited. Additional research is needed to define the potential independent impact of disorders of glucose metabolism in asthma.

Association between Asthma and Type 2 Diabetes Mellitus: Mechanisms and Impact on Asthma Control-A Literature Review

The study aimed to analyze the scientific production on the association between asthma and type 2 diabetes mellitus (T2DM) in adults, the mechanisms that explain this association, and its impact on asthma control. A literature review of scientific articles indexed in the MEDLINE/PUBMED, BVS, CINAHL, Cochrane Library, and Web of Science databases was carried out, considering publications from January 2009 to December 2019, using the following descriptors: "asthma", "type 2 diabetes", "adult," and "association". Of 962 articles found, 18 were included because they met the eligibility criteria. It is suggested that the association between asthma and T2DM is caused by low-grade systemic inflammation (7 articles) or the use of corticosteroids (7 articles). It is noticed that there is a limited scientific production regarding the consequences of this association for the control of asthma (5 articles). It is concluded that asthma and T2DM are two common chronic conditions of increasing prevalence and that often coexist in the same patient. It is suggested that this coexistence worsens asthma control. Therefore, the study may support public policies and clinical health practices that value the approach of comorbidities associated with asthma such as T2DM, in order to minimize additional health risks and reduce the quality of life.

Epigenome-wide association study identifies DNA methylation markers for asthma remission in whole blood and nasal epithelium

BACKGROUND

Asthma is a chronic respiratory disease which is not curable, yet some patients experience spontaneous remission. We hypothesized that epigenetic mechanisms may be involved in asthma remission.

METHODS

Clinical remission (ClinR) was defined as the absence of asthma symptoms and medication for at least 12 months, and complete remission (ComR) was defined as ClinR with normal lung function and absence of airway hyperresponsiveness. We analyzed differential DNA methylation of ClinR and ComR comparing to persistent asthma (PersA) in whole blood samples (n = 72) and nasal brushing samples (n = 97) in a longitudinal cohort of well characterized asthma patients. Significant findings of whole blood DNA methylation were tested for replication in two independent cohorts, Lifelines and Epidemiological study on the Genetics and Environment of Asthma (EGEA).

RESULTS

We identified differentially methylated CpG sites associated with ClinR (7 CpG sites) and ComR (129 CpG sites) in whole blood. One CpG (cg13378519, Chr1) associated with ClinR was replicated and annotated to PEX11 (Peroxisomal Biogenesis Factor 11 Beta). The whole blood DNA methylation levels of this CpG were also different between ClinR and healthy subjects. One ComR-associated CpG (cg24788483, Chr10) that annotated to TCF7L2 (Transcription Factor 7 Like 2) was replicated and associated with expression of TCF7L2 gene. One out of seven ClinR-associated CpG sites and 8 out of 129 ComR-associated CpG sites identified from whole blood samples showed nominal significance (P < 0.05) and the same direction of effect in nasal brushes.

CONCLUSION

We identified DNA methylation markers possibly associated with clinical and complete asthma remission in nasal brushes and whole blood, and two CpG sites identified from whole blood can be replicated in independent cohorts and may play a role in peroxisome proliferation and Wnt signaling pathway.

Association of Metformin Initiation and Risk of Asthma Exacerbation. A Claims-based Cohort Study

Rationale: Diabetes and metabolic syndrome have been associated with worsened asthma control. Metformin improves insulin resistance and metabolic function. Experimental studies suggest that metformin may improve pathologic features of asthma, but evidence of clinical benefit is limited.Objectives: To determine if treatment with metformin in a cohort of individuals with asthma and diabetes is associated with lower risk of asthma exacerbation.Methods: A 6-year retrospective cohort of individuals over age 18 with asthma and diabetes was assembled from a national administrative claims database. New users of metformin were matched to nonusers by propensity score on the basis of demographic, comorbidity, and medication-use characteristics. An exacerbation was defined as an asthma-related hospitalization, emergency department visit, or filling of a systemic corticosteroid prescription within 14 days of an asthma-related ambulatory visit. Cox proportional hazards estimated the change in hazard of asthma exacerbation associated with metformin initiation.Results: In a cohort of 23,920 individuals with asthma and diabetes, metformin initiation was associated with lower hazard of asthma exacerbation (hazard ratio [HR], 0.92; 95% confidence interval [CI], 0.86-0.98), driven by lower hazards of asthma-related emergency department visits (HR, 0.81; 95% CI, 0.74-0.88) and hospitalization (HR, 0.67; 95% CI, 0.50-0.91), without differences in corticosteroid use (HR, 0.96; 95% CI, 0.86-1.03).Conclusions: In an administrative cohort of individuals with asthma and diabetes, metformin initiation was associated with a lower hazard of asthma-related emergency department visits and hospitalizations. These findings suggest a possible benefit of metformin in more severe asthma exacerbations. Investigation within cohorts with more detailed participant characterization is necessary.

[Asthma and obesity in adults]

Asthma is a chronic inflammatory airway disorder characterized by a multitude of phenotypes. Epidemiological studies show an increase in asthma prevalence in obese patients regardless of age. The association of asthma and obesity is now considered as a phenotype with its own clinical, biological and functional characteristics. Regarding the pathophysiology of asthma and obesity, numerous factors such as nutrition, genetic predisposition, microbiome, ventilatory mechanics and the role of adipose tissue have been identified to explain the heterogeneous characteristics of patients with asthma and obesity. In adult patients with asthma and obesity, respiratory symptoms are particularly prominent and atopy and eosinophilic inflammation is uncommon compared to normal weight asthma patients. Obese asthma patients experience more hospitalizations and use more rescue medications than normal weight asthmatics. Management of asthma in obese patients is complex because these patients have less response to the usual anti-asthmatic treatments. Weight loss through caloric restriction combined with exercise is the main intervention to obtain improvement of asthma outcomes. Bariatric surgery is an invasive procedure with interesting results.

Metabolic aspects of the relationship of asthma and obesity

Asthma and obesity are serious medical and social world problems, and their combined course is characterized by a decrease in the quality of life, an increase in the frequency and duration of hospitalization. The present review summarizes the current views on the mechanisms of formation of asthma phenotype combined with obesity, role of leptin and adiponectin imbalance in the development of systemic inflammation in obesity in the pathophysiology of asthma, its interrelations with metabolic syndrome. We present data that shows that syndrome is closely related not only to the debut of asthma, but also to a decrease in its control. Along with obesity, the role of other components of metabolic syndrome, in particular insulin resistance, as a predictor of asthma development is considered. Insulin resistance may be the most likely factor in the relationship between asthma and obesity, independent of other components of the metabolic syndrome. Insulin resistance associated with obesity can lead to disruption of nitric oxide synthesis. We reveal common mechanism of metabolic disorders of nitric oxide and arginine in metabolic syndrome and asthma and show that insulin resistance treatment can be therapeutically useful in patients with asthma in combination with obesity.

Interactive effects of adiposity and insulin resistance on the impaired lung function in asthmatic adults: cross-sectional analysis of NHANES data

BACKGROUND

Obesity is considered a risk factor for both asthma and insulin resistance in adults. Insulin resistance (IR) also influences pulmonary function in the non-obese population.

AIM

To investigate the modifying effect of insulin resistance on the predictive role of anthropometric measures in the estimation of impaired lung function among asthmatic adults.

SUBJECTS AND METHODS

A cross-sectional study of 1276 adults extracted from the NHANES 2009-2012 database was performed. Adjusted multiple linear regression was conducted to analyse the contributory role of obesity and IR in predicting lung function among asthmatic adults.

RESULTS

BMI, waist circumference (WC) and waist-to-height ratio (WHtR) showed significantly negative correlations with FVC (r=-0.24, -0.18, -0.39, respectively; p < 0.001), FEV1(r=-0.24, -0.21, -0.40, respectively; p < 0.001) and FEF 25-75% (r=-0.15, -0.18, -0.27, respectively; p < 0.001). Even after adjustment for the covariates (age, gender, smoking history and standing height), BMI and HOMA-IR had significant relationships with FVC (β= -10.3; p < 0.01 and β= -16.0; p < 0.05) and FEV1 (β= -8.7; p < 0.01 and β= -11.7; p < 0.05). BMI could significantly predict the decreased FVC (β= -13.7; p < 0.01) and FEV1 (β= -10.7; p < 0.01) only in the insulin resistant asthmatics.

CONCLUSION

WHtR and IR predict impaired lung function in overweight/obese asthmatic adults independently. IR also modifies the association between excessive adiposity and respiratory function in asthmatic adults.

Diabetes and Lung Disease: A Neglected Relationship

BACKGROUND

Diabetes mellitus is a systemic disorder associated with inflammation and oxidative stress which may target many organs such as the kidney, retina, and the vascular system. The pathophysiology, mechanisms, and consequences of diabetes on these organs have been studied widely. However, no work has been done on the concept of the lung as a target organ for diabetes and its implications for lung diseases.

AIM

In this review, we aimed to investigate the effects of diabetes and hypoglycemic agent on lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis, pulmonary hypertension, and lung cancer. We also reviewed the potential mechanisms by which these effects may affect lung disease patients.

RESULTS

Our results suggest that diabetes can affect the severity and clinical course of several lung diseases.

CONCLUSIONS

Although the diabetes-lung association is epidemiologically and clinically well-established, especially in asthma, the underlying mechanism and pathophysiology are not been fully understood. Several mechanisms have been suggested, mainly associated with the pro-inflammatory and proliferative properties of diabetes, but also in relation to micro- and macrovascular effects of diabetes on the pulmonary vasculature. Also, hypoglycemic drugs may influence lung diseases in different ways. For example, metformin was considered a potential therapeutic agent in lung diseases, while insulin was shown to exacerbate lung diseases; this suggests that their effects extend beyond their hypoglycemic properties.

Type 2 Diabetes and Asthma: Systematic Review of the Bidirectional Relationship

BACKGROUND AND OBJECTIVE

Obesity is an important contributor to the risk of both asthma and Type 2 Diabetes (T2DM). However, it has been suggested that T2DM and asthma are also independently associated. The aim of this systematic review was to synthesize the evidence for an independent relationship between T2DM and asthma.

METHODS

MEDLINE and EMBASE were searched for studies reporting the relationship between asthma and T2DM in adults. Given a potential bidirectional relationship, articles relating to T2DM as a risk factor for asthma, and asthma as a risk factor for T2DM were examined separately.

RESULTS

Eight studies were identified for inclusion in the review (n=2,934,399 participants). Four studies examined incident diabetes in those with asthma. The pooled (random effects model) adjusted hazard ratio for incident T2DM in asthma was 1.37 (95%CI 1.12-1.69; p <0.001) after controlling for BMI. Four studies reported prevalence or incidence rates of asthma in people with T2DM; higher rates of asthma in those with T2DM were reported in all four studies. Meta-analysis of results was not possible due to methodological heterogeneity. The quality of included studies was good, but due to small numbers, publication bias cannot be excluded.

CONCLUSION

The published literature suggests a bidirectional independent relationship between T2DM and asthma, although we cannot exclude publication bias.

Relationship between diabetes and respiratory diseases-Clinical and therapeutic aspects

Diabetes is a common metabolic disorder affecting the entire body with high morbidity and mortality worldwide. The major complications related to diabetes are mostly due to the macrovascular and microvascular bed impairment due to metabolic, hemodynamic and inflammatory factors. However, studies over the past decades have added also the lung as a target organ in both type 1 and type 2 diabetes. Diabetes has always been addressed as a major comorbidity conditioning the disease behaviour and the natural history of several respiratory diseases. Increased interest has recently focused on the pathophysiology of the metabolic glycaemic disorder and the respiratory diseases suggesting a similar background shared by the two conditions. The true relationship between pulmonary diseases and diabetes mellitus has not been clarified, this review aims to summarize the link between diabetes and coexisting respiratory diseases such as asthma, chronic obstructive pulmonary disease, respiratory infections, cystic fibrosis, lung cancer and obstructive sleep apnea from a pathogenetic and therapeutic point of view.

Association between diabetes and asthma: Evidence from a nationwide Korean study

BACKGROUND

Type 2 diabetes and asthma share a common pathophysiology: "chronic inflammation." However, it is unclear whether patients with type 2 diabetes are at increased risk of asthma.

OBJECTIVE

To investigate the effect of type 2 diabetes on asthma using data from a large population-based study in Korea.

METHODS

Data from the Korean National Health Insurance Service identified 13,154,348 participants who underwent regular health checkups from 2005 to 2008. Subjects were classified according to status of diabetes mellitus (DM) and diabetic retinopathy (DR), and followed until the date of asthma development, death, or December 31, 2013. Cox proportional hazard regression analysis was used to evaluate the effect of diabetes, with or without retinopathy, on asthma development.

RESULTS

The incidences of asthma in the non-DM, DM without DR, and DR groups were 27.1, 30.1, and 38.4 per 1,000 person-years, respectively. Cox proportional hazard multiple regression models revealed that diabetic patients without retinopathy had a significantly lower risk of developing asthma than non-DM subjects (hazard ratio, 0.943; 95% confidence interval, 0.939-0.948). By contrast, diabetic patients with retinopathy had a higher risk of developing asthma (hazard ratio, 1.067; 95% confidence interval, 1.053-1.081).

CONCLUSION

Type 2 diabetes without retinopathy is not a risk factor for asthma development. However, patients with DR are at a greater risk of incident asthma, supporting the notion that the lung is a target organ for diabetic injury. Future studies will address whether proper glycemic control mitigates the risk of asthma.

Pleiotropic effects of hypoglycemic agents: implications in asthma and COPD

Diabetes mellitus (DM) is a complex multifactorial disease due to the interaction between environmental noxae and genetic predisposition. Furthermore, an increased association between DM, especially Type 2 diabetes mellitus (T2DM), and the onset of pulmonary function impairment with a bronchial hyperresponsiveness has been documented. DM is a risk factor for accelerated decline in FEV₁ and the development of asthma and COPD. The increased blood glucose concentrations along with higher levels of oxidative stress and inflammation can influence the pulmonary function and, since hypoglycemic drugs can act on these different defects we can hypothesize their direct effect on obstructive pulmonary diseases. Metformin, a biguanide, is the molecule having several evidences of its action on asthma and COPD in patients with T2DM. In this population, Metformin can ameliorate pulmonary outcomes reducing high glucose concentrations, inflammation through the activation of the AMP-activated protein kinase, leading to the decreased production of pro-inflammatory cytokines and blunting allergic eosinophilic airway inflammation. There are evidences of Pioglitazone role on asthma, since the activation of PPARγ Pioglitazone might inhibit the synthesis and release of pro-inflammatory cytokines. Indeed, Pioglitazone can improve symptoms associated with asthma reducing episodes of exacerbation and oral steroid prescription. Finally, randomized clinical trials using hypoglycemic agents on patients with asthma and COPD with and without DM should be proposed as well as the implementation of a new formulation of hypoglycemic agents to make it possible to administer it via aerosol.

Insulin use increases risk of asthma but metformin use reduces the risk in patients with diabetes in a Taiwanese population cohort

OBJECTIVE

Recent reports have suggested that insulin promotes airway smooth muscle contraction and enhances airway hyperresponsiveness, which are cardinal features of asthma. In contrast, metformin can reduce both airway inflammatory and remodeling properties. However, these results are all from in vitro and animal studies. This study investigated whether diabetes and various antidiabetic agents associate with the risk of asthma.

METHODS

We used a retrospective population-based cohort study using Taiwan's National Health Insurance claim database from 2000 to 2010 and a Cox proportional hazards regression model to compare the incidence of asthma between patients with diabetes (n = 19,428) and a matched non-diabetic group (n = 38,856). We also used a case-control study nested from the above cohort including 1,982 incident cases of asthma and 1,982 age- and sex-matched controls. A time density sampling technique was used to assess the effects of various antidiabetic agents on the risk of asthma.

RESULTS

The incidence of asthma was significantly higher in the diabetic cohort than that in the non-diabetic cohort after adjustment for age, sex, and obesity, with a hazard ratio of 1.30 (95% confidence interval [CI]: 1.24-1.38). Insulin was found to increase the risk of asthma among diabetic patients (odds ratio [OR] 2.23; 95% CI: 1.52-3.58). In contrast, the use of metformin correlated with a decreased risk of asthma (OR 0.75; 95% CI: 0.60-0.95).

CONCLUSIONS

Individuals with diabetes are at an increased risk of asthma. Insulin may further increase the risk of asthma, but the risk could possibly be reduced by using metformin.

Differential association of plasma monocyte chemoattractant protein-1 with systemic inflammatory and airway remodeling biomarkers in type-2 diabetic patients with and without asthma

BACKGROUND

Chronic inflammation is a hallmark of type-2 diabetes (T2D) and asthma. Monocyte chemoattractant protein (MCP)-1 or CCL-2 is a key regulator of monocytic infiltration into the sites of inflammation. The changes in systemic MCP-1 levels and its relationship with other inflammatory/immune markers in T2D patients with asthma remain unclear and have been addressed in this study.

METHODS

Plasma samples from 10 asthmatic T2D patients (Group I: BMI = 37.82 ± 9.75 kg/m²), 13 non-asthmatic T2D patients (Group II: BMI = 32.68 ± 4.63 kg/m²), 23 asthma patients without T2D (Group III: BMI = 30.14 ± 6.74 kg/m²), and 25 non-asthmatic non-diabetic controls (Group IV: BMI = 27.99 ± 5.86 kg/m²) were used to measure levels of MCP-1 and multiple cytokine/chemokine biomarkers with bead-based multiplex assays using Luminex technology. IgE/ECP were measured using commercial ELISA kits. Data (mean ± SEM) were compared using unpaired Student's t-test and linear dependence between two variables was assessed by Pearson's correlation coefficient (r) and P ≤ 0.05 was considered as significant.

RESULTS

Plasma MCP-1 levels were significantly higher in Group I (337.95 ± 46.40 pg/mL) as compared with Group II (216.69 ± 17.30 pg/mL), Group III (251.76 ± 19.80 pg/mL), and Group IV (223.52 ± 133.36 pg/mL). MCP-1 showed differential association with tested biomarkers by correlating positively with: (i) IFN-α2, IL-10, fractalkine, and VEGF in T2D patients with asthma; (ii) IL-6 and GRO-α in T2D patients without asthma; (iii) MDC, IP-10, GM-CSF, FGF-2, and PDGF-AA/BB in patients with asthma only; and (iv) FPG and TG in non-asthmatic non-diabetic controls. MCP-1 associated with IL-1RA only in subjects with asthma.

CONCLUSION

The systemic MCP-1 levels were significantly elevated in T2D patients with asthma as compared with those without asthma and/or diabetes while these changes correlated differentially with important biomarkers of inflammation and airway remodeling.

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

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

Hyperinsulinemia adversely affects lung structure and function

There is limited knowledge regarding the consequences of hyperinsulinemia on the lung. Given the increasing prevalence of obesity, insulin resistance, and epidemiological associations with asthma, this is a critical lacuna, more so with inhaled insulin on the horizon. Here, we demonstrate that insulin can adversely affect respiratory health. Insulin treatment (1 μg/ml) significantly (P < 0.05) increased the proliferation of primary human airway smooth muscle (ASM) cells and induced collagen release. Additionally, ASM cells showed a significant increase in calcium response and mitochondrial respiration upon insulin exposure. Mice administered intranasal insulin showed increased collagen deposition in the lungs as well as a significant increase in airway hyperresponsiveness. PI3K/Akt mediated activation of β-catenin, a positive regulator of epithelial-mesenchymal transition and fibrosis, was observed in the lungs of insulin-treated mice and lung cells. Our data suggests that hyperinsulinemia may have adverse effects on airway structure and function. Insulin-induced activation of β-catenin in lung tissue and the contractile effects on ASM cells may be causally related to the development of asthma-like phenotype.

The contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases

The prevalence of asthma and other atopic diseases has increased markedly during the past decades and the reasons for this are not fully understood. Asthma is still increasing in many parts of the world, notably in developing countries, and this emphasizes the importance of continuing research aimed at studying the aetiological factors of the disease and the causes of its increase in prevalence. Twin studies enable investigations into the genetic and environmental causes of individual variation in multifactorial diseases such as asthma. Thorough insight into these causes is important as this will ultimately guide the development of preventive strategies and targeted therapies. This review explores the contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases.

Comorbidities of asthma: current knowledge and future research needs

PURPOSE OF REVIEW

Asthma is often associated with different comorbidities, mainly gastro-oesophageal reflux disease and allergic rhinitis, but also obesity, depression, diabetes mellitus and cardiovascular disease, which may affect its clinical intensity and severity. The prevalence of these comorbidities varies tremendously between studies. Nevertheless, it imposes a significant reflection on the need to explore the phenomenon in depth.

RECENT FINDINGS

Both clinical and basic studies have established that inflammation plays a vital role in the initiation and progression of several comorbidities. However, the role of systemic inflammation in asthma is still unclear. Understanding mechanism(s) that link(s) asthma and its comorbid diseases is essential to design an effective therapeutic approach.

SUMMARY

In the future, researchers must identify the weight of any comorbidity in patients with asthma, find the true mechanism(s) that link(s) it to asthma and act on these mechanisms that probably create a vicious circle. Conversely, we do not think it reasonable that the generalization of treatment with a holistic approach might affect the link(s) between asthma and its comorbidities.

Relationship between asthma and cognition: the Cooper Center Longitudinal Study

BACKGROUND

Minimal data are available on the relationship between asthma and cognitive performance. In this report, we examine the relationship between asthma and cognitive performance in older adults, a subpopulation with elevated risk of cognitive impairment.

METHODS

We conducted a cross-sectional, retrospective analysis of 1380 participants age ≥55 who completed preventive health examinations at the Cooper Clinic in Dallas, TX. Cognition was assessed using the Montreal Cognitive Assessment (MoCA), a brief test for mild cognitive impairment. Data were analyzed in a multiple logistic regression using MoCA scores suggestive of cognitive impairment as the dependent variable.

RESULTS

When controlling for demographic characteristics, self-rated health status, inhaled corticosteroid use, and FEV1 /FVC, asthma were associated with 78% increased risk of cognitive impairment (P = 0.02) as defined by MoCA score.

CONCLUSIONS

In the largest sample examined to date, we have identified a significant relationship between asthma and cognitive impairment in older people.

The relationship of serum triglycerides, serum HDL, and obesity to the risk of wheezing in 85,555 adults

BACKGROUND

Asthma has been linked to obesity and the presence of the metabolic syndrome.

OBJECTIVE

To explore which components of the metabolic syndrome that were associated with wheezing, a main symptom of asthma. Further, to explore whether these associations were different in individuals with and without rhinitis symptoms.

METHODS

We used data from the Ibermutuamur Cardiovascular Risk Assessment Plan (ICARIA) including 85,555 Spanish workers (median age = 34, range = 16-75 years) with assessments of self reported wheezing and rhinitis symptoms. Fasting blood samples were analysed for serum triglyceride (s-TG), HDL (s-HDL) and glucose; blood pressure, waist circumference (WC) and body mass index (BMI) were measured.

RESULTS

In mutually adjusted analyses including all components of the metabolic syndrome and possible confounders, elevated WC (or BMI), elevated s-TG and low s-HDL were significantly associated with wheezing. Odds ratio (OR) with confidence interval (CI) were: elevated WC = 1.54 (1.46-1.62), elevated s-TG = 1.24 (1.18-1.30), low s-HDL = 1.17 (1.12-1.22). These associations were stronger in individuals without than in those with rhinitis symptoms, OR's (CI's) were WC = without rhinitis 1.70 (1.57-1.85) vs. with rhinitis 1.47 (1.37-1.58). Elevated s-TG = without rhinitis 1.36 (1.26-1.46) vs. with rhinitis 1.21 (1.13-1.29). Low s-HDL = without rhinitis 1.24 (1.15-1.34) vs. with rhinitis 1.11 (1.04-1.18).

CONCLUSIONS

High s-TG and low s-HDL were associated with wheezing after adjustment for adiposity. This may substantiate elevated s-TG and lowered s-HDL as markers or inducers of inflammation associated disease. The study supports the notion that these biochemical markers have differential effects on different types of wheezing.

Rate and risk predictors for development of self-reported type-2 diabetes mellitus over a 5-year period: the SHIELD study

AIMS

This investigation determined the proportion of adults newly diagnosed as having type-2 diabetes mellitus (T2DM), and ascertained risk predictors for development of self-reported T2DM.

METHODS

The US Study to Help Improve Early evaluation and management of risk factors Leading to Diabetes (SHIELD) survey was a 5-year longitudinal study of adults with and without diabetes mellitus. Adults completed a baseline health questionnaire in 2004 and ≥1 annual follow-up survey through 2009. Respondents with no self-reported diagnosis of diabetes at baseline were followed to measure rate of and assess risk factors for development of T2DM over 5 years.

RESULTS

Among 8582 respondents without diabetes at baseline, 622 (7.2%) reported a diagnosis of T2DM over the subsequent 5 years. Increasing age, family history of T2DM, body mass index ≥30 kg/m(2), abdominal obesity, excessive thirst, asthma, gestational diabetes and 'high blood sugar without diabetes' significantly increased the risk of developing T2DM (p < 0.05 for each). Good to excellent health status and self-reported circulatory problems decreased the risk (p < 0.05 for each).

CONCLUSIONS

Among this representative US adult population, the rate of developing T2DM was 7.2% over 5 years. Predictors of T2DM diagnosis identified in this analysis were readily obtainable via self-report.