'The Gut-Lung Axis: Is the intestinal microbiome impacting respiratory health?'
sponsored by Bio-Kult

Please note, this is a transcript of the questions received and have been reproduced verbatim in relation to any grammatical errors.

Do you think that sinusitis is also linked to the gut?

Causes of sinusitis include a combination of environmental and host factors. Acute sinusitis is most commonly due to viruses and is usually self-limiting. Those with atopy commonly get sinusitis. It can be caused by allergens, irritants, viruses, fungi, and bacteria. Popular irritants are animal dander, polluted air, smoke, and dust. Inflammation is the major cause of chronic rhinosinusitis (CRS) rather than bacterial infection. Fungi have emerged as a possible pathogenic agent that drives CRS.

The prevalence of fungal sinus disease is thought to have been increasing in recent decades. There is speculation that this may be due to increased awareness, antibiotic overuse and increased use of immunosuppressant medications. Added to this, there is some evidence that Candida may be one of the fungi genera described as a potential causative organism in chronic rhinosinusitis. In normal conditions, fungi that are inhaled form part of the normal sino-nasal flora. These fungi are then destroyed by normal functioning immunological cascades. However, following the prolonged use of antibiotics, poor ventilation, dark and moist environments as well as those who are immunocompromised, these immunological pathways may be disrupted, making fungal infections more likely.

In one longitudinal study where the nasal microbiome was analysed, a distinct sino-nasal bacterial signature was observed in healthy individuals throughout the year; the fungal community composition was more influenced by seasonal parameters. ‘The underlying reasons for these shifts are likely a combination of changes in environmental climate for fungi, and changes within the host for bacterial communities’: https://www.nature.com/articles/s41598-019-53975-9.  Another study found that those with chronic rhinosinusitis had an over-representation of E. coli in their sinuses, with an association of Corynebacterium and Dolosigranulum found in the control group (generally found to be beneficial in the upper respiratory tract of healthy patients): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5836553/.

With this in mind, it could be a logical suggestion that benefits could be found with supporting the nasal microbiome, particularly when we consider some of the confirmed mechanisms of action that beneficial bacteria have; production of bacteriocins and reducing pH levels etc that were discussed in the webinar. However, although there is some evidence for the association between the viral, fungal and bacterial organisms with chronic sinusitis, the exact nature and importance of the relationship is still unclear.

Again, as discussed in the webinar, live bacteria may influence the systemic immune system by supporting the gut lining, which may in turn benefit cells lining other parts of the body such as the nasal and sinus mucosa. In addition, sinusitis is often treated with steroid sprays or anti-fungal preparations (for fungal sinusitis), which may damage the resident mucosal bacteria in the respiratory tract and gut, leading to increased risk of overgrowth of candida (due to the gut-lung axis). Therefore although more research is needed in this area, it may be beneficial to support the gut microbiome, in aid of supporting the microbiome of other body systems.

Would probiotics benefit someone with Sarcoidosis?

Sarcoidosis is a rare disease caused by inflammation. It usually occurs in the lungs and lymph nodes, but it can occur in almost any organ. It is one of a group of respiratory diseases called interstitial lung disease (ILD). Sarcoidosis in the lungs is called pulmonary sarcoidosis and it causes small lumps of inflammatory cells in the lungs. These lumps, called granulomas, can affect how the lungs work. The granulomas generally heal and disappear on their own. But, if they don’t heal, the lung tissue can remain inflamed and become scarred and stiff, called pulmonary fibrosis. It changes the structure of the lungs and can affect breathing. Bronchiectasis can also occur. This is when pockets form in the air tubes of the lung and become infected. But these problems are not common.

There is a growing body of literature supporting dysbiosis of the microbiome as a contributor to ILD.  Numerous studies have implicated an altered lung microbiome in the pathogenesis of interstitial lung diseases, such as idiopathic pulmonary fibrosis (IPF) and sarcoidosis. (Chioma et al 2021 is a good paper to read). Another paper by Nasiri et al. in 2020 using a sarcoidosis mouse model, found that their microbiomes showed a significant reduction in the population of Bifidobacteria in faecal and cecum samples.  

Therefore although more research is needed in this area, it may be beneficial to support the gut microbiome, in aid of supporting the microbiome of the lungs.

Chioma OS, Hesse LE, Chapman A, Drake WP. Role of the Microbiome in Interstitial Lung Diseases. Front Med (Lausanne). 2021;8:595522. Published 2021 Jan 28. doi:10.3389/fmed.2021.595522 https://www.frontiersin.org/articles/10.3389/fmed.2021.595522/full

10. Nasiri, C. Zhang, R. Tian, S. Banerjee, M. Mirsaeidi. Bifidobacterium: The Most Sensitive Member of Gut Microbiota That Interacts with Pulmonary Sarcoidosis. American Journal of Respiratory and Critical Care Medicine 2020;201:A1552 https://doi.org/10.1164/ajrccm-conference.2020.201.1_MeetingAbstracts.A1552

Can you email me your Jafari study on the PXN strains?

You can find the research here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4025125/

Jafari SA, Mehdizadeh-Hakkak A, Kianifar HR, Hebrani P, Ahanchian H, Abbasnejad E. 2013. Effects of probiotics on quality of life in children with cystic fibrosis; a randomized controlled trial. Iran J Pediatr 23:669–674