Your lungs are teeming with fungi. But don’t be alarmed, this doesn’t mean they’re lined with mold, mushrooms, or a nasty infection. Just like microbes living in many organs of the human body, most of these microorganisms are perfectly “friendly” and may possibly play a role in the healthy function of your body.
Lungs were for once considered to be a sterile environment (unless they were infected by a pathogen). However, recent advances in sequencing techniques have revealed that many microbes, most notably bacteria, live in the lungs of healthy individuals, just like the microbiome of the skin, gut, vagina, mouth, and so on.
A new study by the University of Bergen in Norway, reported in the journal PLOS One, has dived it into the so-called “pulmonary mycobiome,” a community of microbes found in human lungs. They collected samples from the lungs and mouths of around 200 people, approximately half of whom were healthy and half who had chronic obstructive pulmonary disease (COPD), then sequenced the samples for fungal DNA. The study authors write that it’s thought to be the first of its kind to investigate the presence of the lung’s microbiome in non-immunocompromised patients with a large healthy control population.
It appears that the composition of fungi found in the mouth was different from the one in the lungs, indicating that lungs do have their own unique fungal environment.
Genera of fungi like Malassezia and Sarocladium were also frequently found in lung samples, but the most dominant fungus was Candida. Candida is a common type of fungus that lives on the skin, the mouth, throat, gut, and vagina, often without causing any problems. However, an overgrowth of certain Candida species is considered an infection, referred to as a yeast infection or thrush. Importantly, they found no differences in compositions of fungi between lungs from healthy people and patients with COPD.
The question is: does the composition of fungi in the lung influence our health? It isn't yet clear, but it’s well-established that the microbiome of other human organs is closely linked to a variety of diseases and health outcomes. The gut microbiome may influence the risk of Parkinson's disease, depression, dementia, and COVID-19, to name just a few examples. There’s even some evidence that gut bacteria may shape your personality.
As for the lung microbiome, some early studies have suggested that microbes may play a role in the maintenance of the lungs. Another intriguing study highlights that severe asthma patients tend to have higher levels of fungi in their lungs. However, the study authors say that more evidence is needed before any firm conclusions can be settled on.
"It would be of great interest to further examine if fungal lung infections are caused by fungi that are already present in the lungs", Einar Marius Hjellestad Martinsen, lead study author and PhD candidate at the University of Bergen, said in a statement.
"If so, emphasis should be placed on these fungi to reveal what triggers are responsible for converting them from being "friendly residents" of our lungs to disease-causing intruders."