The DNA methylation of FOXO3 and TP53 as a blood biomarker of late-onset asthma

Background

Late-onset asthma (LOA) is beginning to account for an increasing proportion of asthma patients, which is often underdiagnosed in the elderly. Studies on the possible relations between aging-related genes and LOA contribute to the diagnosis and treatment of LOA. Forkhead Box O3 (FOXO3) and TP53 are two classic aging-related genes. DNA methylation varies greatly with age which may play an important role in the pathogenesis of LOA. We supposed that the differentially methylated sites of FOXO3 and TP53 associated with clinical phenotypes of LOA may be useful biomarkers for the early screening of LOA.

Methods

The mRNA expression and DNA methylation of FOXO3 and TP53 in peripheral blood of 43 LOA patients (15 mild LOA, 15 moderate LOA and 13 severe LOA) and 60 healthy controls (HCs) were determined. The association of methylated sites with age was assessed by Cox regression to control the potential confounders. Then, the correlation between differentially methylated sites (DMSs; p-value < 0.05) and clinical lung function in LOA patients was evaluated. Next, candidate DMSs combining with age were evaluated to predict LOA by receiver operating characteristic (ROC) analysis and principal components analysis (PCA). Finally, HDM-stressed asthma model was constructed, and DNA methylation inhibitor 5-Aza-2′-deoxycytidine (5-AZA) were used to determine the regulation of DNA methylation on the expression of FOXO3 and TP53.

Results

Compared with HCs, the mRNA expression and DNA methylation of FOXO3 and TP53 vary significantly in LOA patients. Besides, 8 DMSs from LOA patients were identified. Two of the DMSs, chr6:108882977 (FOXO3) and chr17:7591672 (TP53), were associated with the severity of LOA. The combination of the two DMSs and age could predict LOA with high accuracy (AUC values = 0.924). In HDM-stressed asthma model, DNA demethylation increased the expression of FOXO3 and P53.

Conclusions

The mRNA expression of FOXO3 and TP53 varies significantly in peripheral blood of LOA patients, which may be due to the regulation of DNA methylation. FOXO3 and TP53 methylation is a suitable blood biomarker to predict LOA, which may be useful targets for the risk diagnosis and clinical management of LOA.

Obesity, but not metabolic syndrome, as a risk factor for late-onset asthma in Japanese women

BACKGROUND

Several cross-sectional studies have suggested an association between obesity and asthma. However, few studies have investigated this relationship longitudinally, especially in middle-aged subjects. Although metabolic syndrome is a well-known risk factor for many non-communicable diseases, its contribution to asthma remains controversial.

METHODS

From 2008, specific health checkups for metabolic syndrome have been conducted throughout Japan. To seek relationships of obesity and metabolic syndrome with late-onset asthma in Japan, we analyzed data collected from health insurance claims and specific health checkups for metabolic syndrome at three large health insurance societies. Among subjects aged 40-64 years (n = 9888), multivariate logistic regression analyses were performed to investigate the relationships of obesity and metabolic syndrome in fiscal year 2012 (from April 2012 to March 2013) with the incidence of late-onset asthma in the following two years (from April 2013 to March 2015).

RESULTS

In women, BMI 25-29.9 kg/m² or ≥30 kg/m², waist circumference ≥90 cm, and waist-to-height ratio ≥0.5 were shown to be significant risk factors for asthma, with adjusted odds ratios (95% CI) of 1.92 (1.35-2.75), 2.24 (1.23-4.09), 1.89 (1.30-2.75), and 1.53 (1.15-2.03), respectively. Significance was retained even after adjustment for metabolic syndrome, and there were no significant relationships between metabolic syndrome itself and the incidence of asthma in men or women.

CONCLUSIONS

Only the obesity measures, not metabolic syndrome, were shown to be significant risk factors for the incidence of late-onset asthma but only in middle-aged Japanese women, and not in men.

The Severe Asthma Network in Italy: Findings and Perspectives

BACKGROUND

Severe Asthma Network in Italy (SANI) is a registry of patients recruited by accredited centers on severe asthma.

OBJECTIVE

To analyze epidemiological, clinical, inflammatory, functional, and treatment characteristics of severe asthmatics from the SANI registry.

METHODS

All consecutive patients with severe asthma were included into the registry, without exclusion criteria to have real-life data on demographics, asthma control, treatments (including biologics), inflammatory biomarkers, and comorbidities.

RESULTS

A total of 437 patients (mean age: 54.1 years, 57.2% females, 70.7% atopics, 94.5% in Global Initiative for Asthma severity step V) were enrolled into the study. The mean annual exacerbation rate was 3.75. The mean blood eosinophil level was 536.7 cells/mcL, and the average serum total IgE was 470.3 kU/L. Approximately 64% of patients were on regular oral corticosteroid treatment, 57% with omalizumab and 11.2% with mepolizumab. Most common comorbidities were rhinitis, nasal polyposis, and bronchiectasis. Patients with nasal polyposis had higher age of disease onset, higher blood eosinophil count, and lower frequency of atopy and atopic eczema. Bronchiectasis was associated with more frequent severe exacerbations, higher blood eosinophils, and total IgE. Stratifying patients, those with late-onset asthma were less frequently atopic (with less frequent allergic rhinitis and food allergy), and more frequently with nasal polyposis and higher serum total IgE levels.

CONCLUSIONS

This study revealed a high frequency of relevant comorbidities and that a substantial proportion of patients have late-onset asthma; all these features define specific different disease phenotypes. Severe asthma complexity and comorbidities require multidisciplinary approaches, led by specifically trained pulmonologists and allergists.

Regulatory tone and mucosal immunity in asthma

The lung is constantly exposed to a variety of inhaled foreign antigens, many of which are harmless to the body. Therefore, the mucosal immune system must not only have the capacity to distinguish self from non-self, but also harmless versus dangerous non-self. To address this, mucosal immune cells establish an anti-inflammatory steady state in the lung that must be overcome by inflammatory signals in order to mount an effector immune response. In the case of inhaled allergens, the false detection of dangerous non-self results in inappropriate immune activation and eventual allergic asthma. Both basic and clinical studies suggest that the balance between tolerogenic and inflammatory immune responses is a key feature in the outcome of health or disease. This review is focused on what we term 'regulatory tone': the immunosuppressive environment in the lung that must be overcome to induce inflammatory responses. We will summarize the current literature on this topic, with a particular focus on the role of regulatory T cells in preventing allergic disease of the lung. We propose that inter-individual differences in regulatory tone have the potential to not only establish the threshold for immune activation in the lung, but also shape the quality of resulting effector responses following tolerance breakdown.