Bronchial responsiveness, spirometry and mortality in a cohort of adults

Metformin Alleviates Airway Hyperresponsiveness in a Mouse Model of Diet-Induced Obesity

Obese asthma is a unique phenotype of asthma characterized by non-allergic airway hyperresponsiveness (AHR) and inflammation which responds poorly to standard asthma therapy. Metformin is an oral hypoglycemic drug with insulin-sensitizing and anti-inflammatory properties. The objective of the current study was to test the effect of metformin on AHR in a mouse model of diet-induced obesity (DIO). We fed 12-week-old C57BL/6J DIO mice with a high fat diet for 8 weeks and treated them with either placebo (control, n = 10) or metformin (n = 10) added in drinking water (300 mg/kg/day) during the last 2 weeks of the experiment. We assessed AHR, metabolic profiles, and inflammatory markers after treatments. Metformin did not affect body weight or fasting blood glucose, but significantly reduced serum insulin (p = 0.0117). Metformin reduced AHR at 30 mg/ml of methacholine challenge (p = 0.0052) without affecting baseline airway resistance. Metformin did not affect circulating white blood cell counts or lung cytokine mRNA expression, but modestly decreased circulating platelet count. We conclude that metformin alleviated AHR in DIO mice. This finding suggests metformin has the potential to become an adjuvant pharmacological therapy in obese asthma.

Long-term predictors of severe exacerbations and mortality in a cohort of well-characterised adults with asthma

Background

We aimed to explore long-term predictors of severe exacerbations and mortality in adults with well-characterised asthma.

Study design and methods

Adults (aged ≥ 15) with an objectively verified diagnosis of asthma were recruited from a Danish respiratory outpatient clinic between 1974 and 1990. All individuals were followed in Danish registries for vital status, hospital admissions for asthma and cause of death until end of 2017. Predictors of exacerbations were obtained from a repeated measures model. Standardised mortality rates (SMR) for all-causes were compared with the Danish background population. Hazard ratios for mortality were obtained from a cox proportional hazards model in a two-step process.

Results

At baseline, the cohort comprised 1071 patients (mean age 38, SD 16, 61% women), of whom 357 (33%) died during follow-up, with 93 (26%) dying from asthma (primary diagnosis). We found an SMR of 1.24 (95% CI 1.11–1.37, p < 0.001) for all-cause mortality. Baseline predictors for asthma-related death and repeated severe exacerbations were increasing age, ever smoker, FEV₁ < 80% pred., high blood eosinophils, longer duration of symptoms and use of SABA > twice daily. Being non-atopic, having a positive histamine challenge test and symptoms more than twice a week were also predictors of repeated exacerbations.

Conclusions

Markers of poor asthma control, including high use of SABA, are predictors of long-term exacerbation rate and mortality over 30 years in patients with well-characterised asthma. Improving asthma control, including lung function and reducing use of reliever medication, is vital for improving the long-term outcome of asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01864-z.

Polymorphism Analysis of Ch1 and Ch2 Genes in the Siberian Cat

Cats are usually spreaders of allergens that are critical for sensitive people; the Siberian cat is a breed supposed to be low level allergenic, according to some breeders' statements. The sequence of the two genes, namely Ch1 and Ch2, that code for the allergen Fel d 1, the major allergen responsible for outbreaks of allergy symptoms, is not yet known in the Siberian cat, and finding this was the aim of our investigation. Notably, our work is the first survey of the genetic structure of these genes in Siberian cats. The comparison of the sequences of Siberian cats, non-Siberian cats, and sequences present in the National Center for Biotechnology Information database revealed a considerable number of mutations; some of those detected in the Siberian cat, due to their position in exon regions, could affect the Fel d 1 allergenic properties. Therefore, further investigations are recommended to assess if the identified mutations can be responsible for a reduced-allergen synthesis and can be used as markers for selection of low level allergenic cats.

Polymorphism Analysis of Ch1 and Ch2 Genes in the Siberian Cat

Cats are usually spreaders of allergens that are critical for sensitive people; the Siberian cat is a breed supposed to be low level allergenic, according to some breeders' statements. The sequence of the two genes, namely Ch1 and Ch2, that code for the allergen Fel d 1, the major allergen responsible for outbreaks of allergy symptoms, is not yet known in the Siberian cat, and finding this was the aim of our investigation. Notably, our work is the first survey of the genetic structure of these genes in Siberian cats. The comparison of the sequences of Siberian cats, non-Siberian cats, and sequences present in the National Center for Biotechnology Information database revealed a considerable number of mutations; some of those detected in the Siberian cat, due to their position in exon regions, could affect the Fel d 1 allergenic properties. Therefore, further investigations are recommended to assess if the identified mutations can be responsible for a reduced-allergen synthesis and can be used as markers for selection of low level allergenic cats.

A population-based cohort of adults with asthma: mortality and participation in a long-term follow-up

Background and objective: Asthma is a major public health concern. The aim of this study was to characterize a large population-based cohort of adults with asthma, and to study factors associated with all-cause mortality and non-participation in a long-term follow-up. Design: Random and stratified samples from five population-based cohorts were clinically examined during 1986-2001, and all subjects with asthma were included in the study (n = 2055, age 19-72 years, 55% women). Independent associations between different risk factors and (i) mortality and (ii) non-participation in a clinical follow-up in 2012-2014 were estimated. Results: In 1986-2001, 95% reported any wheeze and/or attacks of shortness of breath in the past 12 months, and/or asthma medication use. Over the up to 28 years of follow-up time, the cumulative mortality was 22.7%. Male gender, current smoking, and lower forced expiratory volume in 1 sec of predicted (FEV₁% of predicted) were independent risk factors for mortality, while obesity was associated with non-participation in the follow-up. Older ages, ischemic heart disease, and low socioeconomic status were associated with both mortality and non-participation. Conclusions: The risk factors associated with mortality in this adult population-based asthma cohort were similar to those commonly identified in general population samples, i.e. male gender, current smoking, and lower FEV₁% of predicted, while obesity was associated with non-participation in a long-term follow-up. Ischemic heart disease, low socioeconomic status, and older ages were associated with both mortality and non-participation.

Impact of asthma on mortality in older women: An Australian cohort study of 10,413 women

BACKGROUND

Comorbid conditions frequently coexist with asthma in older adults and can alter the natural history of asthma, complicating management and affecting overall prognosis and survival.

OBJECTIVES

This study investigates the impact of asthma on mortality among older women, with a specific interest in influence of comorbidities and social factors on survival of older women with asthma.

DESIGN

Participants were from the Australian Longitudinal Study on Women's Health and were born between 1921 and 1926. Cox proportional hazards were used to evaluate mortality rates for women with and without asthma, after adjustment for comorbidities and other factors.

RESULTS

Of 10,413 women aged 73-78, 829 (8%) reported having been diagnosed by a doctor for asthma. Women with asthma had a higher likelihood of heart disease, hypertension, thrombosis, bronchitis/emphysema, osteoporosis and major illnesses (p < 0.0001). Asthma was associated with increased risk of death (HR = 1.31, 95%CI 1.18-1.45, p < 0.0001). After adjusting for age, demographic factors, comorbidities, risk factors, residential area and social support, women with asthma retained a 17% increased risk of death compared to women without asthma (HR = 1.17, 95%CI 1.03-1.32, p = 0.016).

CONCLUSION

Older women with asthma have a higher rate of mortality compared with other women of the same age. This increased risk of death remains after age, demographic factors, comorbidities, risk factors, residential area and social support have been taken into account.

Identification and characterization of major cat allergen Fel d 1 mimotopes on filamentous phage carriers

Cat allergy is one of the most prevalent allergies worldwide and can lead to the development of rhinitis and asthma. Thus far, only allergen extracts from natural sources have been used for allergen-specific immunotherapy. However, extracts and whole allergens in immunotherapy present an anaphylaxis risk. Identification of allergen epitopes or mimotopes has an important role in development of safe and effective allergen-specific immunotherapy. Moreover, with a suitable immunogenic carrier, the absence of sufficient immune response elicited by short peptides could be surmounted. In this study, we identified five structural mimotopes of the major cat allergen Fel d 1 by immunoscreening with random peptide phage libraries. The mimotopes were computationally mapped to the allergen surface, and their IgE reactivity was confirmed using sera from cat-allergic patients. Importantly, the mimotopes showed no basophil activation of the corresponding cat-allergic patients, which makes them good candidates for the development of hypoallergenic vaccine. As bacteriophage particles are becoming increasingly recognized as immunogenic carriers, we constructed bacteriophage particles displaying multiple copies of each selected mimotope on major phage coat protein. These constructed phages elicited T cell-mediated immune response, which was predominated by the type 1 T cell response. Mimotopes alone contributed to the type 1 T cell response by promoting IL-2 production. Fel d 1 mimotopes, as well as their filamentous phage immunogenic carriers, represent promising candidates in the development of hypoallergenic vaccine against cat allergy.