Do fungi in the nose play a role in rhinitis and asthma?

Itchy and runny nose, sneezing, and conjunctivitis in the case of allergic rhinitis. Shortness of breath, wheezing, coughing, and chest tightness in the case of asthma.

Are these typical symptoms of chronic respiratory diseases familiar to you? If so, it might interest you to know that the populations of microscopic fungi in the nose (i.e. mycobiota) of healthy people are probably very different from those in the nose of chronic respiratory disease patients. This difference could be very good news for the diagnosis of such conditions and for the development of new treatments.

Delving into the mysterious world of nasal fungi

It has long been known that dysbiosis of the microbiota, in particular the ear, nose, and throat (ENT) microbiota, plays a role in the onset and progression of respiratory diseases such as allergic rhinitis (hay fever) and asthma. Numerous studies have looked at the bacterial component of the ENT microbiota. But what about its fungal component?

To answer this question, a team led by immunologist Dr Luis Delgado at the University of Porto in Portugal recruited 339 children and young adults, 125 of whom were in good health and 214 suffered from either rhinitis, asthma, or both conditions. The scientists then took nasal microbiota samples from all participants to specifically analyze the nature and organization of the fungal communities.

Firstly, they found the mycobiota of participants suffering from respiratory diseases to be very different (considerably richer and more diversified) from that of healthy people.

Among the genera common to all participants, sick or otherwise, the researchers found certain fungi known to be opportunistic pathogens, such as Aspergillus and Candida, among others. For the researchers, this may be evidence that the nasal cavities act as a reservoir of potentially harmful fungi that promote rhinitis and asthma, similar to what we know about bacteria.

Potential treatment options

In those suffering from both rhinitis and asthma, and therefore particularly affected by inflammation, it appeared that the fungal networks were more interconnected than in those suffering from rhinitis only or those who had no health problems. This indicates that fungi are very likely to be sensitive to the immune environment.

While this work has enabled Dr Delgado’s team to identify potential targets for future diagnostic or treatment tools, a crucial question remains: is the presence of a specific fungal population the result of inflammation of the nasal mucosa or the cause of this inflammation? Longer-term studies that place greater emphasis on patient profiles will be needed to answer this question. This initial study is nonetheless a big step in the right direction.