We have millions of all sorts of microbes living throughout our respiratory tract (nose, sinuses, mouth, lungs, etc.). A recent study looked at the microbes in the lungs and found that fungi normally live in healthy lungs, including fungi that are usually thought of as harmful. Surprisingly, the fungi found in lungs of people with COPD (chronic obstructive pulmonary disease) are basically similar to those in healthy people.
The fungi living in different parts of the body is the mycobiome. The lung (pulmonary) microbiome is unique, meaning it is different than in other parts of the respiratory tract, such as the mouth. It used to be thought that the lungs were sterile (unless there was an infection). But now we know that is not true - we normally have fungi, bacteria, and viruses living in our lungs.
University of Bergen researchers analyzed both the oral (mouth) mycobiome and lung mycobiome of 93 persons with COPD and 100 healthy persons (the control group). Surprisingly, both the oral and lung mycobiomes of both healthy and COPD groups were dominated by Candida fungi, with more Candida in the mouth, than in the lungs for both groups. Finding that Candida resides in the lungs of heathy individuals was surprising because it can be a "fungal pathogen" (thus harmful and invasive) in different parts of the body.
One piece of good news - using inhaled steroids didn't seem to affect the lung mycobiome.
Keep in mind that fungi are all around us, both indoors and outdoors, and we are constantly breathing in fungal spores. Our bodies have evolved to handle normal amounts just fine. As the researchers wrote: "Healthy airways possess effective removal of such spores". It's when a person is immunocompromised or has COPD that problems can develop.
From Medical Xpress: Fungi are present in your lungs
The lungs were for a long time considered to be sterile in health, while in diseases like chronic obstructive pulmonary disease (COPD) failure in immune mechanisms were thought to allow microorganisms to proliferate and persist. New sequencing techniques have shown that several microorganisms reside in the lungs of healthy individuals, as well. Few studies have examined the fungal community in COPD and compared it to healthy controls using such techniques.
The Bergen COPD Microbiome study (short name "MicroCOPD") is the world's largest single-center study on the fungal community in lungs of persons with COPD. The Bergen Respiratory Research Group collected samples from the lungs of 233 individuals with and without COPD using bronchoscopy. Lung and mouth samples from 193 of these individuals were subsequently sequenced to detect residing fungi.
"Results showed that both healthy and diseased lungs had a different fungal composition than the mouth, suggesting that lungs have a unique fungal environment," says Ph.D. candidate Einar Marius Hjellestad Martinsen.
The lungs were dominated by the fungus Candida. Interestingly, there were no differences in compositions between lungs from healthy individuals and patients with COPD. Furthermore, patients with COPD using inhaled steroids did not have any differences in the fungal community of their lungs compared to those not using inhaled steroids.
The prevalence and severity of fungal infections have increased in recent years. The finding that Candida is frequently found in healthy lungs could thus be of special importance. Candida is found as part of the normal flora on several mucous membranes, and is capable of causing disease, for instance thrush in the mouth or vagina.
We know that use of inhaled steroids can have immunosuppressive effects, which can predispose to fungal outgrowth. The observation that inhaled steroids did not seem to affect the composition of the fungal environments in the lungs is interesting in this regard.