Role of TNF-alpha and its 55 and 75 kDa receptors in bronchial hyperreactivity

Association Between Asthma and All-Cause Mortality and Cardiovascular Disease Morbidity and Mortality: A Meta-Analysis of Cohort Studies

Background

Asthma and cardiovascular disease (CVD) share many risk factors. Previous meta-analyses indicated that asthma is associated with an increased risk of CVD and all-cause mortality, but these studies were limited by unstandardized search strategies and the number of articles included.

Objective

We sought to systematically synthesize evidence investigating the impact of asthma on all-cause mortality and CVD morbidity and mortality.

Methods

We searched in PubMed and EMBASE for observational cohort studies (inception dates to November 10, 2021) that had both asthma groups and control groups. We also manually searched the reference lists of correlative articles to include other eligible studies. Data for associations between asthma and all-cause mortality and CVD morbidity and mortality were needed.

Results

We summarized the findings from 30 cohort studies comprising 4,157,823 participants. Asthma patients had increased CVD morbidity [relative risk (RR) = 1.28, 95% confidence interval (CI) = 1.16–1.40] and increased CVD mortality (RR = 1.25, 95% CI = 1.14–1.38). Asthma patients also had increased risk of all-cause mortality (RR = 1.38, 95% CI = 1.07–1.77). In subgroup analyses, female asthma patients had a higher risk of CVD morbidity and all-cause mortality than male asthma patients, and late-onset asthma patients had a higher risk of CVD morbidity than early-onset asthma patients.

Conclusion

Asthma patients have increased risk of all-cause mortality and CVD morbidity and mortality. This information reminds clinicians to be aware of the risk of CVD and all-cause mortality in asthma patients.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, PROSPERO, identifier: CRD 42021290082.

Shared Genetic Architecture and Causal Relationship Between Asthma and Cardiovascular Diseases: A Large-Scale Cross-Trait Analysis

Background: Accumulating evidence has suggested that there is a positive association between asthma and cardiovascular diseases (CVDs), implying a common architecture between them. However, the shared genetic architecture and causality of asthma and CVDs remain unclear.

Methods: Based on the genome-wide association study (GWAS) summary statistics of recently published studies, our study examined the genetic correlation, shared genetic variants, and causal relationship between asthma (N = 127,669) and CVDs (N = 86,995–521,612). Statistical methods included high-definition likelihood (HDL), cross-trait meta-analyses of large-scale GWAS, transcriptome-wide association studies (TWAS), and Mendelian randomization (MR).

Results: First, we observed a significant genetic correlation between asthma and heart failure (HF) (Rg = 0.278, P = 5 × 10⁻⁴). Through cross-trait analyses, we identified a total of 145 shared loci between asthma and HF. Fifteen novel loci were not previously reported for association with either asthma or HF. Second, we mapped these 145 loci to a total of 99 genes whose expressions are enriched in a broad spectrum of tissues, including the seminal vesicle, tonsil, appendix, spleen, skin, lymph nodes, breast, cervix and uterus, skeletal muscle, small intestine, lung, prostate, cardiac muscle, and liver. TWAS analysis identified five significant genes shared between asthma and HF in tissues from the hemic and immune system, digestive system, integumentary system, and nervous system. GSDMA, GSDMB, and ORMDL3 are statistically independent genetic effects from all shared TWAS genes between asthma and HF. Third, through MR analysis, genetic liability to asthma was significantly associated with heart failure at the Bonferroni-corrected significance level. The odds ratio (OR) is 1.07 [95% confidence interval (CI): 1.03–1.12; p = 1.31 × 10⁻³] per one-unit increase in log_e odds of asthma.

Conclusion: These findings provide strong evidence of genetic correlations and causal relationship between asthma and HF, suggesting a shared genetic architecture for these two diseases.

Presentation, management and mortality after a first MI in people with and without asthma: A study using UK MINAP data

Asthma has been associated with a higher incidence of myocardial infarction (MI), higher prevalence of MI risk factors and higher burden of cardiovascular diseases. However, detailed associations between the presentation and initial management at the time of MI and post-MI outcomes in people with asthma compared to the general population have not been studied. A total of 300,161 people were identified with a first MI over the period 2003-2013 in the Myocardial Ischaemia National Audit Project database, of whom 8922 (3%) had asthma. Logistic regression was used to compare presentation, in-hospital care, in-hospital and 180-day post-discharge all-cause mortality in people with and without asthma adjusting for demographics and comorbidities, diagnosis on arrival and secondary prevention. People with asthma were more likely to have a delay in their MI diagnosis following an STEMI (ST-elevation myocardial infarction; odds ratio (OR) 1.38, confidence interval CI 1.06-1.79) but not an nSTEMI (non-ST-elevation myocardial infarction; OR 1.04, CI 0.92-1.17) compared to people without asthma and a delay in reperfusion (OR 1.19, CI 1.09-1.30) following an STEMI. They were much less likely to be discharged on a beta blocker following an STEMI or nSTEMI (OR 0.24, CI 0.21-0.28 and OR 0.27, CI 0.24-0.30, respectively). There was no difference in in-hospital or 180-day mortality (OR 0.98, CI 0.59-1.62 and OR 0.99, CI 0.72-1.36) following an STEMI or nSTEMI (OR 0.89, CI 0.47-1.68 and OR 1.05, CI 0.85-1.28). Although people with asthma were more likely to have a delay in diagnosis following an STEMI but not an nSTEMI compared to the general population, were more likely to have a delay in reperfusion therapy and were much less likely to receive beta blockers following an STEMI or nSTEMI, there was no difference in the prescriptions of other secondary prevention medications. None of the differences in presentation or management were associated with an increase in all-cause in-hospital or 180-day mortality in people with asthma compared to the general population.

Arterial inflammation in bronchial asthma

BACKGROUND

Bronchial asthma is a chronic inflammatory condition associated with increased cardiovascular (CV) events. Here, we assess arterial inflammation, using 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging (FDG-PET/CT), in patients with bronchial asthma and low to intermediate Framingham risk scores (FRS).

METHODS

A total of 102 patients underwent FDG-PET/CT imaging for clinical indications. Thirty-four patients (mean age 54.9 ± 16.1) with mild asthma and no known atherosclerotic disease were compared to 2 non-asthmatic groups. The first control group (n = 34) were matched by age, gender, and FRS. The second control group (n = 34) had clinical atherosclerosis and were matched by gender. Thereafter, arterial FDG uptake on PET images was determined, while blinded to patient identifiers.

RESULTS

Target-to-background-ratio (TBR) in the aorta was higher in asthmatics vs non-asthmatic FRS-matched controls (1.96 ± 0.26 vs 1.76 ± 0.20; P < .001). The aortic TBR remained elevated in asthmatics vs non-asthmatic controls after adjusting traditional CV risk factors (P < .001). An inverse correlation was observed between FDG uptake and lung function, FEV1 (P = .02) and peak flow (P = .03).

CONCLUSIONS

Bronchial asthma is associated with increased arterial inflammation beyond that estimated by current risk stratification tools. Further studies are required to evaluate whether attenuation of systemic inflammation will decrease CV events.

Adult asthma and risk of coronary heart disease, cerebrovascular disease, and heart failure: a prospective study of 2 matched cohorts

Asthma has been associated with increased cardiovascular disease (CVD) risk. The authors ascertained the association of asthma with CVD and the roles that sex, concurrent allergy, and asthma medications may play in this association. They assembled a cohort of 203,595 Northern California adults with asthma and a parallel asthma-free referent cohort (matched 1:1 on age, sex, and race/ethnicity); both cohorts were followed for incident nonfatal or fatal CVD and all-cause mortality from January 1, 1996, through December 31, 2008. Each cohort was 66% female and 47% white. After adjustment for age, sex, race/ethnicity, cardiac risk factors, and comorbid allergy, asthma was associated with a 1.40-fold (95% confidence interval (CI): 1.35, 1.45) increased hazard of coronary heart disease, a 1.20-fold (95% CI: 1.15, 1.25) hazard of cerebrovascular disease, a 2.14-fold (95% CI: 2.06, 2.22) hazard of heart failure, and a 3.28-fold (95% CI: 3.15, 3.41) hazard of all-cause mortality. Stronger associations were noted among women. Comorbid allergy predicted CVD but did not synergistically increase the CVD risk associated with asthma. Only asthma patients using asthma medications (particularly those on oral corticosteroids alone or in combination) were at enhanced risk of CVD. In conclusion, asthma was prospectively associated with increased risk of major CVD. Modifying effects were noted for sex and asthma medication use but not for comorbid allergy.

The obesity phenotype in children with asthma

Asthma and obesity have been increasing in prevalence internationally among children. Evidence points to an association between these chronic morbidities, suggesting the development of an 'obese asthma' phenotype in childhood. This review summarises the evidence that the proinflammatory environment created by excess adiposity may provide a mechanism leading to obese asthma in children and adolescents. Weight loss studies conducted in children without asthma have demonstrated a reduction in systemic inflammation. However, the impact of weight loss in the obese paediatric population with asthma has not been investigated. The paucity of information highlights the need for high quality randomised controlled trials of weight loss in this population that include assessment of systemic and airway inflammation, and clinical asthma outcomes. This will lead to refinements in management approaches for these patients.

Prenatal exposure to endotoxin in rats attenuates the allergic airways eosinophil infiltration in the adult offspring: role of inducible nitric oxide synthase activation

A correlation between stressful events experienced by the mother during pregnancy and progression of respiratory disease in descendants has been reported. Prenatal exposure to lipopolyssacharide (LPS) reduces allergic airway inflammation in mice offspring. In this study we investigated whether reduction of airways inflammation by maternal LPS exposure involves activation of inducible nitric oxide synthase (iNOS) at prenatal life. Since LPS also induces the release of TNF-alpha, and that this cytokine has been implicated in pathogenesis of asthma, we also evaluated whether TNF-alpha plays a role in the allergic airways inflammation by maternal LPS exposure. Pregnant rats were pretreated with the iNOS inhibitor aminoguanidine (50mg/rat per day; given from day 13 of gestation up to delivery) before exposure to LPS (7mug/kg, given at day 17 of gestation). At adult ages, female and male offspring were sensitized with ovalbumin (OVA), and 14 days later they were challenged with this allergen. OVA challenge in sensitized offspring increased markedly the eosinophil number in bronchoalveolar lavage (BAL) fluid at 48h compared with the non-sensitized group. However, the eosinophil number was largely reduced in offspring from maternal LPS exposure, irrespective of offspring gender. Maternal pretreatment with aminoguanidine fully reversed the eosinophil suppression by LPS. The maternal LPS exposure also reduced the eosinophil number in bone marrow and peripheral blood of offspring, but this was not affected by aminoguanidine. No differences in TNF-alpha levels in BAL fluid were found. In conclusion, our study shows that maternal LPS exposure markedly reduces allergic airways eosinophil recruitment in adult offspring by mechanisms possibly involving iNOS activation.

Mast cells in the promotion and limitation of chronic inflammation

Observations of increased numbers of mast cells at sites of chronic inflammation have been reported for over a hundred years. Light and electron microscopic evidence of mast cell activation at such sites, taken together with the known functions of the diverse mediators, cytokines, and growth factors that can be secreted by appropriately activated mast cells, have suggested a wide range of possible functions for mast cells in promoting (or suppressing) many features of chronic inflammation. Similarly, these and other lines of evidence have implicated mast cells in a variety of adaptive or pathological responses that are associated with persistent inflammation at the affected sites. Definitively characterizing the importance of mast cells in chronic inflammation in humans is difficult. However, mice that genetically lack mast cells, especially those which can undergo engraftment with wildtype or genetically altered mast cells, provide a means to investigate the importance of mast cells and specific mast cell functions or products in diverse models of chronic inflammation. Such work has confirmed that mast cells can significantly influence multiple features of chronic inflammatory responses, through diverse effects that can either promote or, perhaps more surprisingly, suppress aspects of these responses.

Mast cell-derived TNF contributes to airway hyperreactivity, inflammation, and TH2 cytokine production in an asthma model in mice

BACKGROUND

Mast cells, IgE, and TNF, which have been implicated in human atopic asthma, contribute significantly to the allergic airway inflammation induced by ovalbumin (OVA) challenge in mice sensitized with OVA without alum. However, it is not clear to what extent mast cells represent a significant source of TNF in this mouse model.

OBJECTIVE

We investigated the importance of mast cell-derived TNF in a mast cell-dependent model of OVA-induced airway hyperreactivity (AHR) and allergic airway inflammation.

METHODS

Features of this model of airway inflammation were analyzed in C57BL/6J-wild-type mice, mast cell-deficient C57BL/6J-Kit(W-sh)(/W-sh) mice, and C57BL/6J Kit(W-sh/W-sh) mice that had been systemically engrafted with bone marrow-derived cultured mast cells from C57BL/6J-wild-type or C57BL/6J-TNF(-/-) mice.

RESULTS

Ovalbumin-induced AHR and airway inflammation were significantly reduced in mast cell-deficient Kit(W-sh/W-sh) mice versus wild-type mice. By contrast, Kit(W-sh/W-sh) mice that had been engrafted with wild-type but not with TNF(-/-) bone marrow-derived cultured mast cells exhibited responses very similar to those observed in wild-type mice. Mast cells and mast cell-derived TNF were not required for induction of OVA-specific memory T cells in the sensitization phase, but significantly enhanced lymphocyte recruitment and T(H)2 cytokine production in the challenge phase.

CONCLUSION

Mast cell-derived TNF contributes significantly to the pathogenesis of mast cell-dependent and IgE-dependent, OVA-induced allergic inflammation and AHR in mice, perhaps in part by enhancing lymphocyte recruitment and T(H)2 cytokine production.

CLINICAL IMPLICATIONS

Our findings in mice support the hypothesis that mast cell-derived TNF can promote allergic inflammation and AHR in asthma.

TNF can contribute to multiple features of ovalbumin-induced allergic inflammation of the airways in mice

BACKGROUND

TNF is thought to contribute to airway hyperreactivity (AHR) and airway inflammation in asthma. However, studies with TNF-deficient or TNF receptor-deficient mice have not produced a clear picture of the role of TNF in the AHR associated with allergic inflammation in the mouse.

OBJECTIVE

We used a genetic approach to investigate the contributions of TNF to antigen-induced AHR and airway inflammation in mice on the C57BL/6 background.

METHODS

We analyzed features of airway allergic inflammation, including antigen-induced AHR, in C57BL/6 wild-type and TNF(-/-) mice, using 2 different methods for sensitizing the mice to ovalbumin (OVA).

RESULTS

In mice sensitized to OVA administered with the adjuvant aluminum hydroxide (alum), which develop IgE-independent and mast cell-independent allergic inflammation and AHR, we found no significant differences in OVA-induced AHR in C57BL/6-TNF(-/-) versus wild-type mice. By contrast, in mice sensitized to OVA without alum, which develop allergic inflammation that is significantly mast cell-dependent, C57BL/6-TNF(-/-) mice exhibited significant reductions versus wild-type mice in OVA-induced AHR to methacholine; numbers of lymphocytes, neutrophils, and eosinophils in bronchoalveolar lavage fluid; levels of myeloperoxidase, eosinophil peroxidase, and the cytokines IL-4, IL-5, and IL-17 in lung tissue; and histologic evidence of pulmonary inflammation.

CONCLUSION

In pulmonary allergic inflammation induced in mice immunized with OVA without alum, TNF significantly contributes to several features of the response, including antigen-induced inflammation and AHR.

CLINICAL IMPLICATIONS

Our findings in mice support the hypothesis that TNF can promote the allergic inflammation and AHR associated with asthma.

Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma

Asthma is an increasingly common disorder responsible for considerable morbidity and mortality. Although obesity is a risk factor for asthma and weight loss can improve symptoms, many patients do not adhere to low calorie diets and the impact of dietary restriction on the disease process is unknown. A study was designed to determine if overweight asthma patients would adhere to an alternate day calorie restriction (ADCR) dietary regimen, and to establish the effects of the diet on their symptoms, pulmonary function and markers of oxidative stress, and inflammation. Ten subjects with BMI>30 were maintained for 8 weeks on a dietary regimen in which they ate ad libitum every other day, while consuming less than 20% of their normal calorie intake on the intervening days. At baseline, and at designated time points during the 8-week study, asthma control, symptoms, and Quality of Life questionnaires (ACQ, ASUI, mini-AQLQ) were assessed and blood was collected for analyses of markers of general health, oxidative stress, and inflammation. Peak expiratory flow (PEF) was measured daily on awakening. Pre- and postbronchodilator spirometry was obtained at baseline and 8 weeks. Nine of the subjects adhered to the diet and lost an average of 8% of their initial weight during the study. Their asthma-related symptoms, control, and QOL improved significantly, and PEF increased significantly, within 2 weeks of diet initiation; these changes persisted for the duration of the study. Spirometry was unaffected by ADCR. Levels of serum beta-hydroxybutyrate were increased and levels of leptin were decreased on CR days, indicating a shift in energy metabolism toward utilization of fatty acids and confirming compliance with the diet. The improved clinical findings were associated with decreased levels of serum cholesterol and triglycerides, striking reductions in markers of oxidative stress (8-isoprostane, nitrotyrosine, protein carbonyls, and 4-hydroxynonenal adducts), and increased levels of the antioxidant uric acid. Indicators of inflammation, including serum tumor necrosis factor-alpha and brain-derived neurotrophic factor, were also significantly decreased by ADCR. Compliance with the ADCR diet was high, symptoms and pulmonary function improved, and oxidative stress and inflammation declined in response to the dietary intervention. These findings demonstrate rapid and sustained beneficial effects of ADCR on the underlying disease process in subjects with asthma, suggesting a novel approach for therapeutic intervention in this disorder.

The relationship of psychologic stress with childhood asthma

The psychologic influence on childhood asthma has long been a subject of investigation and controversy. This article illustrates the evidence that psychologic stress is related to children with asthma. Individual experience, the impact of family and neighborhood, the effect of caregiver mental status, and the presence of negative psychologic events affect symptoms and management. The pathways through which these factors influence asthma are mediated through cognitive and biologic mechanisms, with evidence indicating changes in behavior and alteration in immune response as underlying mechanisms. Psychologic issues are important in the patient with severe asthma. The mind-body paradigm that links psychologic stress to disease is necessary when considering the global evaluation of childhood asthma.