How do nasal microflora benefit in protecting against dreadful respiratory infections?

Immunity & good health is determined by the collective presence of living symbiotic, and pathogenic microorganisms in the human microbiome system. Throughout the life cycle age accordingly, bacterial community & its characteristics vary.

Nasal microbiota

Nasal cavity mutualistic bacteria compete for space, and nutrients & produce toxic materials, helping repress pathogenic bacteria and inhibit or kill them. Nasal cavity dysbiosis leads to opportunistic pathogenic bacteria presence, spread in the respiratory tract & the development of allergic rhinitis (AR), chronic rhinosinusitis (CRS), acute respiratory tract infections (ARTI), otitis media (OM), and asthma.

Factors affecting nasopharyngeal microbiota complexity

1. Disease exposure
2. Environmental hazards & poor hygiene
3. Vaccinations & healthcare facilities    
4. Delivery type & dietary habituation
5. Lifestyle, smoking, drinking alcohol
6. Socioeconomic conditions, overcrowded living, daycare contact & family size

CRS

Instigates disease progression, nasal polyps’ development, chronic symptoms, and sinus cavity inflammatory response. The prevalent presence of Coagulase-negative Staphylococcus, Pseudomonas aeruginosa, and S. aureus influence & modulate the immune response.

Asthma

Determines asthma onset, advancement, acuteness, metagenomic inference & bacterial glycerolipid metabolism and increase in Prevotella buccalis, Gardnerella vaginalis, P. buccalis, G. vaginalis, Dialister invisus, and Alkanindiges hongkongensis species. Asymptomatic expansion of Streptococcus affects the future possibility, danger & later episodes of asthma and its inflammation symptoms.

In asthma-affected children, Moraxella, Staphylococcus, Corynebacterium, Haemophilus, Fusobacterium, Prevotella, and Dolosigranulum dominate the nasal microbiome environment.

AR

Affects the immune response modulation, pathophysiology & AR growth. In seasonal allergic rhinitis (SAR) patients, pollination season spikes symptoms, nasal eosinophils levels & middle meatus bacterial biodiversity.

ARTI

Controls host’s susceptibility, influenza-specific immunoglobulin A antibody production disparity, taxa richness rise & the surge of Streptococcus pneumoniae, S. aureus, Phyllobacterium, Moraxella, Staphylococcus, Corynebacterium, and Dolosigranulum in the nasal carriage.

Concomitantly S. pneumoniae transmission increases shooting up protease secretion, activates viral hemagglutinins and modulates the innate immune response. Facilitates influenza, A virus (adenovirus, or rhinovirus) infection & associated respiratory virus infection, S. pneumoniae elevation & invasive pneumococcal pneumonia risk.

OM

Regulates Moraxella, Streptococcus, and Pasteurella spp migration from the middle ear to the nose microbiome & leading to OM. S. pneumoniae, Haemophilus, Actinomyces, Rothia, Neisseria, and Veillonella increase in OM-affected children. OM acute episodes escalate abundant increase of otopathogen genera and decrease in Pseudomonas, Myroides, Yersinia, and Sphingomonas.

Probiotic Intervention in Nasal Microbiome Dysbiosis

• Improves nasal itching, sneezing & decreases symptom medication score
• As an adjunctive treatment offers a safe & well-tolerated better immunologic response
• Limits potential pathogen overgrowth & increase in beneficial microorganisms

Conclusion

The nasal passage is colonized with a diverse range of bacteria, fungi, and viruses and it is the first contact point to the external environment exposure. The nasal microbiota profile positively correlates with amplified immune response. Further research is required to reinforce the promising role of probiotic intervention in the supplementary treatment of nasal dysbiosis-connected respiratory infections.

References

1. Allergy & Rhinology,2020;11: 1–10
2. Front Cell Infect Microbiol. 2022; 12: 841995.
3. Clin Exp Pediatr. 2021 Nov; 64(11): 543–551.

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