Probiotic for the nose
If there are enough lactobacilli in our nose, it will be healthy
The microbiome, a symbiotic microbial community of humans, has been the subject of intensive research in recent years. In addition to gaining fundamental knowledge, the study of the microbiome can be of great benefit to practical medicine. This time, the microorganisms living in our nose – the first natural barrier to pathogenic viruses, bacteria and allergens that enter the body "by air" - turned out to be under the "gun" of scientists.
Article by De Boeck et al. Lactobacilli Have a Niche in the Human Nose is published in the journal Cell Reports.
Our "neighbors" in the body are many microorganisms (microbiome), the total weight of which is calculated in kilograms. Most of them bring us undoubted benefits, performing important functions in the body. For example, bacteria living in the intestine are involved in the digestion of food and the synthesis of many compounds we need, and those living on the skin are protected from pathogens (by the way, we kill them using disinfectants and antibacterial soap).
To date, the gut microbiome has been best studied, but surprisingly little is known about the smallest inhabitants of the mucous membranes of the upper respiratory tract. Meanwhile, knowledge about them can be very important, since chronic diseases of the nasopharynx account for a considerable proportion of human diseases.
For example, today about 11% of the European population suffers from chronic rhinosinusitis – inflammation of the nasal mucosa and paranasal sinuses, while antibiotics are not always effective in this case. The fact is that the participation of specific pathogenic bacteria in the development of this disease remains controversial: there is an opinion that it is rather the result of a complex of violations of the composition of the microbiome than the "aggressive activity" of individual microorganisms. If this is the case, then the use of probiotics that contribute to the normalization of the bacterial community may be more effective.
Belgian scientists, having studied samples taken from 100 healthy volunteers and 225 patients with chronic rhinosinusitis, found an order of magnitude more lactobacilli (Lactobacillus, lactic acid bacteria) in the nasal mucosa of healthy people – one of the most common symbiotic microorganisms of the human body, primarily the gastrointestinal tract.
During the fermentation of sugar, lactobacilli produce lactic acid, which suppresses the growth of pathogenic microorganisms. They prefer an oxygen-free environment or one where there is very little oxygen, so the researchers were surprised to find representatives of this genus in a well-aerated organ. To make sure that they are not dealing with a random find (lactobacilli could get into the nose from the oral cavity), they carefully studied the characteristics that could help lactobacilli exist in such uncharacteristic conditions for them.
It turned out that some bacterial strains carry genes encoding catalase enzymes, with which they can neutralize the harmful effects of oxygen – the so-called oxidative stress. In addition, they were found to have fimbria – villi that help to securely attach to the cells of the nasal mucosa.
Cultivation of selected strains together with Staphylococcus aureus, Hemophilus bacillus and bacterium Moraxella catarrhalis – the key pathogens of the upper respiratory tract, has shown that the bacterium L.casei suppresses the growth of all these dangerous microorganisms.
Considering that the nose of laboratory rodents is too different from the human nose, and L.casei has long been successfully used in probiotics to restore the intestinal and vaginal microflora, scientists conducted preliminary tests on humans at once. Twenty healthy volunteers were injected with a spray containing these lactobacilli twice a day for two weeks. It turned out that the procedure did not cause negative side effects, and the bacterium itself successfully colonized the mucous membranes, remaining in them for a long time: even two weeks after the introduction of the spray, L.casei could be detected in 10-35% of the samples studied.
Ultimately, scientists hope to create a nasal spray based on lactobacilli, which can become an effective means of treating chronic diseases of the human upper respiratory tract.
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