Tag: asthma

Surprising Finding Links Asthma Risk to Meat Consumption as Infants

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Researchers looking for post-breastfeeding dietary patterns in two prospective birth cohorts, were surprised to discover meat consumption as a predictive factor.

Alexander Hose, MA, MPH, of Ludwig Maximilian University in Munich presented the study’s findings at the virtual European Respiratory Society annual meeting

After switching from breast milk, babies up to age 1 whose protein intake came largely from meat products, rather than dairy, fish, or egg proteins, had a more than eight-fold greater chance of developing asthma by age 6 versus non-meat protein consumption. Asthma prevalence reached 30% in some subgroups.

Wheezing was more common in this diet pattern, which Hose and colleagues termed “unbalanced meat consumption” (UMC); this continued up to age 10, with a five times higher odds.

The duration of breastfeeding was an important factor, likely because switching to baby foods prolonged the exposure. Odds of developing asthma by age 6 increased nearly 12-fold in UMC-fed infants whose breastfeeding stopped by week 19, versus about four-fold in those continuing longer on breast milk.

In addition, UMC was also linked to a certain intestinal microbiome profile featuring unusually high levels of Lactococcus, Granulicatella, and Acinetobacter species.

This type of microbiome scavenges iron in the gut, Hose said, which could explain why the children became especially susceptible to asthma. Additionally, milk proteins may exert an opposite effect on asthma risk by generating a type of “nutritional immunity.”

While the mechanism connecting the gut microbiome to respiratory disease is unknown, the existence of a ‘gut-lung axis‘ is well established; a recent trial showed that probiotics can prevent coughs and wheezing in older adults. The phenomenon has also been considered for COVID’s gastrointestinal symptoms.

A pair of European birth cohort studies, PASTURE and LUKAS2, provided the data for the study. In these, about 1400 infants were followed through age 10 and parents kept detailed records of their infants’ feeding, and other environmental factors, and children’s medical records were accessed as well.

However, a key limitation is the cohorts being from rural areas since investigating asthma’s relationship to animal exposure was a key goal for the studies. Partly because of this, Hose and colleagues were able to separate out ‘industrial’ meat, milk, and yoghurt from that produced at home. A trend toward greater asthma risk was observed with store-bought protein products.

Source: MedPage Today

Circadian Rhythm Contributes to Asthma Severity

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By pinning down the influence of the circadian system on nocturnal asthma, researchers have uncovered a key role for the biological clock in asthma.

Asthma severity has long been observed to worsen in the nighttime. Lung function is highest at around 4pm and worst around 4am. One longstanding question has been to what degree the body’s internal circadian clock contributes to worsening of asthma severity, as opposed to behaviours such as sleep. Using two circadian protocols, researchers have delineated the influence of the circadian system. Understanding the mechanisms behind asthma severity could have important implications for both studying and treating asthma. 

“This is one of the first studies to carefully isolate the influence of the circadian system from the other factors that are behavioral and environmental, including sleep,” said co-corresponding author Frank AJL Scheer, PhD, director of the Medical Chronobiology Program in the Division of Sleep and Circadian Disorders at the Brigham.

As many as 75 percent of people with asthma report experiencing worsening asthma severity at night. Asthma severity is influenced by behavioural and environmental factors, such as exercise, air temperature, posture, and sleep environment. The researcher sought to understand the internal circadian system’s contributions to this problem. The circadian system is composed of a central pacemaker in the brain (the suprachiasmatic nucleus) and “clocks” throughout the body and is critical for the coordination of bodily functions and to anticipate the daily cycling environmental and behavioral demands.

To isolate the influence of the circadian system from that of sleep and other behavioural and environmental factors, the researchers enrolled 17 participants with asthma into two complementary laboratory protocols where lung function, asthma symptoms and bronchodilator use were continuously assessed. In the “constant routine” protocol, participants spent 38 hours continuously awake, in a constant posture, and under dim light conditions, with identical snacks every two hours. In the “forced desynchrony” protocol, participants were placed on a recurring 28-hour sleep/wake cycle for a week under dim light conditions, with all behaviours scheduled evenly across the cycle.

Co-corresponding author Steven A. Shea, Ph.D., professor and director at Oregon Institute of Occupational Health Sciences said, “We observed that those people who have the worst asthma in general are the ones who suffer from the greatest circadian-induced drops in pulmonary function at night, and also had the greatest changes induced by behaviours, including sleep. We also found that these results are clinically important because, when studied in the laboratory, symptom-driven bronchodilator inhaler use was as much as four times more often during the circadian night than during the day.”  

The study was published in Proceedings of the National Academy of Sciences.

Source: Medical Xpress

CT Scans Reveal Lung Destruction in Asthmatics

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A new study using CT scans have revealed significant changes indicating lung destruction in some asthmatics.

Clinicians have long thought that some people with asthma experience declines in their lung function, called fixed airflow obstruction (FAO), due to changes to their airways. In this study published in The Journal of Allergy and Clinical Immunologyresearchers have found that this issue could extend to the surrounding lung tissue.

Respirologist Kaoruko Shimizu at Hokkaido University said, “Bronchial asthma is considered to be mainly due to inflammation and remodeling of the larger respiratory airways. But not all asthmatics improve with the typical treatments prescribed to alleviate this condition. We wanted to know if changes to the surrounding lung tissue induced a decline in pulmonary function over time in this subgroup of patients.”

Shimizu and her colleagues applied a novel computer tomography (CT)-based approach to detect changes in lung tissue. In this approach, the scientists examined CT scans employing an index called “exponent D” for areas of reduced lung density with increasing coalescence of neighbouring airspaces, which indicates emphysema, or the destruction of air sacs. Airway obstruction was measured by testing the ability of people with asthma to forcefully exhale air in one second. This ability is reduced when the airways are narrower.

The tests examined around 200 smokers and non-smokers with varying degrees of asthma, who were then followed up annually for five years.

People with asthma who experienced persistent airflow limitation, regardless of the severity of their asthma or their smoking status, exhibited constricted airways and also showed signs of lung tissue destruction, the researchers found.

The observed changes to lung tissue in this subgroup of asthmatic patients were not associated with the typical inflammatory markers linked to bronchial asthma. This is important, because it could explain why conventional anti-inflammatory treatments are not as successful in this group.

Future studies should investigate lung destruction in asthma, enabling more personalised management, said Shimizu.

Source: Hokkaido University

80% of Childhood Asthma Hospital Presentations are Preventable

Image by Bob Williams from Pixabay
Image by Bob Williams from Pixabay

Based on a comprehensive Australian survey, approximately 80 percent of asthma-related hospital presentations in school-aged children are potentially avoidable through a standardised comprehensive care pathway for children with asthma.

These preventative measures include using evidence-based clinical guidelines, ensuring that there is an asthma action plan in place; regular follow-up with GP; provision of asthma education to parents/carers; and establishing a community-based approach for continuity of care.

Senior author Dr Nusrat Homaira, respiratory epidemiologist at UNSW Sydney said, “During our research, we surveyed 236 nurses and 266 doctors across 37 hospitals in all 15 local health districts (LHDs) across New South Wales (NSW) to identify the existing care pathway following discharge from hospital for children with asthma.”

This study by researchers at UNSW Sydney identified major variations in the existing asthma care pathway, including:

Use of asthma clinical guidelines and Asthma Action Plan: Although clinical guidelines and Asthma Action Plans (AAPs) were used across all hospitals, on average, there were four to six different types of documents used in each (LHD), between hospitals in the same LHD and within departments in the same hospital. Such variations can be confusing for clinicians, as noted by a survey participant: “Conflicting advice given to asthma patients between general practitioners, emergency departments and sometimes paediatricians; patients are then confused about what to do in exacerbation of symptoms.”

GP follow-up: In most LHDs (75 percent) parents/carers were advised to have their child followed up with their GP within two to three days after hospital discharge, but in some areas, follow-up appointments could be recommended for over six days post-hospitalisation. Parents/carers were reportedly responsible for organising follow-up with their GP with no system to ensure they in fact attended.

Asthma education for parents/carers of asthmatic children: Formal asthma education (27 percent of respondents) were seldom provided to parents/carers during hospital stays; limited to asthma device techniques and rarely involved key topics such as basic knowledge of asthma, asthma control and the importance of regular medical review.

Communication with schools/childcare services: When children with asthma were discharged from hospitals, only four percent of the surveyed staff reported that schools or childcare services were notified of the child’s recent hospital presentation.

Community services integration: The majority of participants (55 percent) were unaware of any community services for children with asthma in their local areas.

The survey identified marked variations in asthma care and management for children within different health districts, different hospitals in the same district and different departments within the same hospital in. The findings highlight opportunities to improve the health outcomes in children with asthma and reduce unnecessary burden on health systems from preventable asthma hospital presentations.

Source: EurekAlert!

Journal information: Chan, M., et al. (2021) Assessment of Variation in Care Following Hospital Discharge for Children with Acute Asthma. Journal of Asthma and Allergy. doi.org/10.2147/JAA.S311721.

A Step Towards an Asthma Vaccine

Researchers have tested a newly developed vaccine that could confer long-term protection against allergic asthma, reducing the severity of its symptoms. 

Their research in animals has been published in the journal Nature Communications.

Asthma affects 340 million worldwide. It is a chronic disease of the air passages characterised by inflammation and narrowing of the airways in response to allergens such as dust mites. Symptoms of asthma include shortness of breath, cough, and wheezing. 

Exposure to dust mites and other allergens leads to the production of antibodies called immunoglobulin E (IgE) and type 2 cytokines (such as interleukin-4 (IL-4) and IL-13) in the airways. This leads to a cascade of reactions resulting in hyperresponsiveness of the respiratory tract, excessive mucus production, and eosinophilia (when there are too many eosinophils, a type of white blood cell, in the airways).

Currently, inhaled corticosteroids are the gold standard for controlling asthma — but in the case of severe asthma, this treatment is not enough. Then, it is necessary to use therapeutic monoclonal antibodies that target IgE or the IL-4 and IL-13 pathways. These are costly treatments, however, requiring long-term or even lifelong administration of injections.

To solve this, the researchers developed a conjugate vaccine, called a kinoid, by coupling the recombinant cytokines IL-4 and IL-13 with a carrier protein called CRM197 (a non-pathogenic mutated form of the diphtheria toxin, used in many conjugate vaccines).

The preclinical results from animal models demonstrate that this vaccine induces the sustained production of antibodies specifically directed against IL-4 and IL-13. The vaccine was so effective that six weeks after the first injection of the conjugate vaccine, 90% of the mice presented high levels of antibodies. Over one year after primary immunisation, 60% of them still had antibodies capable of neutralising IL-4 and IL-13 activity.

The vaccine was also shown to strongly reduce levels of IgE, eosinophilia, mucus production and airway hyperresponsiveness in a model of dust mite allergic asthma. This study therefore suggests both the prophylactic and therapeutic efficacy of the vaccine in this model of asthma and no adverse effects were observed in the animals. The next step for the researchers will be to test these findings in a clinical trial setting.

Source: Medical Xpress

Journal information: Eva Conde et al, Dual vaccination against IL-4 and IL-13 protects against chronic allergic asthma in mice, Nature Communications (2021). DOI: 10.1038/s41467-021-22834-5

Healthy Country Childhood: The Protective “Farm Effect” on Asthma

The presence of a diverse gut microbiome appears to exert a protective effect against asthma, which may explain the largely protective “farm effect” on asthma.

European researchers analysed faecal samples from over 700 infants raised on farms, and found a strong environmental effect. It was anticipated that nutrition would be a strong contributor to gut microbiome maturation, but there were unanticipated environmental effects such as exposure to animal sheds.

Researchers found that faecal butyrate (related to butyrate, a short-chain fatty acid), which is already known to protect against asthma in mice, had an inverse association with asthma. They ascribed this to gut bacteria such as Roseburia and Coprococcus which have the potential of producing short chain fatty acids. Children with more matured gut microbiomes had Roseburia and Coprococcus present.

“Our study provides further evidence that the gut may have an influence on the health of the lung. A mature gut microbiome with a high level of short chain fatty acids had a protective effect on the respiratory health of the children in this study. This suggests the idea of a relevant gut-lung axis in humans,” said Dr. Markus Ege, professor for clinical-respiratory epidemiology at the Dr. von Hauner Children’s Hospital. “This also means, however, that an immature gut microbiome may contribute to the development of diseases. This emphasizes the need for prevention strategies in the first year of life, when the gut microbiome is highly plastic and amenable to modification.”

Source: News-Medical.Net