The World Asthma Foundation (WAF). WAF is a nonprofit organization dedicated to improving the lives of people with asthma through education, research, and advocacy. In this blog post, I want to share with you some exciting findings from a recent study on the microbiome and asthma, published by Spanish researchers in the journal Nutrients.
The microbiome is the collection of microorganisms that live in and on our bodies, such as bacteria, fungi, viruses, and parasites. The microbiome plays an important role in our health and immunity, and can also influence our susceptibility and response to various diseases, including asthma.
Asthma is a chronic inflammatory disease of the airways that affects millions of people worldwide. Asthma can be triggered by different factors, such as allergens, infections, pollution, stress, and diet. Asthma can also have different phenotypes (characteristics), such as allergic or non-allergic, eosinophilic or non-eosinophilic, mild or severe.
What is the microbiome and how does it affect asthma?
The study by Valverde-Molina and García-Marcos reviews the current evidence and challenges on the relationship between the microbiome and asthma, specifically how microbial dysbiosis (an imbalance of the microbial communities in the body) can influence the origins, phenotypes, persistence, and severity of asthma.
How different factors can influence the microbiome and asthma
The study explores how different factors, such as diet, environment, genetics, and infections, can affect the microbiome and asthma, and how modulating the microbiome could be a potential strategy for preventing or treating asthma. The study also reviews the different methods and techniques used to study the microbiome and its interactions with the immune system and the respiratory system.
The gut-lung axis: a key connection between the microbiome and asthma
One of the key points of the study is the importance of the gut-lung axis in the origin and persistence of asthma. The gut-lung axis is the concept that describes how the gut and lung microbiomes communicate with each other through various pathways, such as metabolites, cytokines, antibodies, and immune cells. The gut-lung axis can modulate inflammation and allergic responses in both organs.
The study shows that the process of microbial colonization in the first three years of life is fundamental for health, with the first hundred days of life being critical. Different factors are associated with early microbial dysbiosis, such as caesarean delivery, artificial lactation and antibiotic therapy, among others.
How microbial dysbiosis can lead to different asthma phenotypes and severity
Longitudinal cohort studies on gut and airway microbiome in children have found an association between microbial dysbiosis and asthma at later ages of life. A low ?-diversity (the number of different species) and relative abundance of certain commensal gut bacterial genera in the first year of life are associated with the development of asthma. Gut microbial dysbiosis, with a lower abundance of Phylum Firmicutes (a group of bacteria that includes lactobacilli), could be related with increased risk of asthma.
Upper airway microbial dysbiosis, especially early colonization by Moraxella spp. (a type of bacteria that can cause respiratory infections), is associated with recurrent viral infections and the development of asthma. Moreover, the bacteria in the respiratory system produce metabolites (substances produced by metabolism) that may modify the inception of asthma and its progression.
The role of the lung microbiome in asthma development has yet to be fully elucidated. Nevertheless, the most consistent finding in studies on lung microbiome is
the increased bacterial load (the number of bacteria) and the predominance of proteobacteria (a group of bacteria that includes Haemophilus spp. and Moraxella catarrhalis), especially in severe asthma.
Candida albicans: a fungal culprit in asthma development and exacerbation
The study also mentions Candida albicans (a type of fungus that can cause infections) as one of the fungal genera that can affect the gut and lung microbiome and asthma. Candida albicans can trigger inflammation and autoimmune responses in the body. Candida albicans can also induce a Th17 response (a type of immune response) in the gut and lungs. Candida albicans can also increase lung bacterial load and exacerbate airway inflammation.
This study is very relevant to our own research and findings on Candida’s role in inflammation and autoimmune response: implications for severe asthma. We published an article on this topic on our website on October 13th 2021 which features findings from Mayo Clinic researchers who examined how intestinal fungal microbiota affects lung resident memory CD4+ T cells (a type of immune cell) in patients with asthma.
You can find our article here: https://worldasthmafoundation.org/candidas-role-in-inflammation-and-autoimmune-response-implications-for-severe-asthma.htm
How modulating the microbiome could be a promising strategy for asthma prevention and treatment
We think that these studies complement each other well and provide valuable insights into this important and emerging topic. We believe that understanding the microbiome and its impact on asthma is crucial for developing new and effective strategies for prevention, diagnosis, and treatment of this chronic disease.