A significant proportion of the Portuguese population suffers from allergies that manifest as runny noses, with nearly a quarter of adults affected. This condition, known as allergic rhinitis, is often associated with asthma. Both diseases, which impact the upper airways, have sparked research into their underlying mechanisms. A global research team has recently uncovered a fascinating finding—patients with allergy-induced rhinitis and asthma exhibit distinct fungal colonies, or mycobiomes, in their nasal passages. This discovery may open new avenues for future treatments of these conditions.
“We showed that allergic rhinitis samples displayed a significantly higher fungal diversity and a different fungal community structure compared to those of healthy controls,” said Dr. Luís Delgado from the University of Porto, Portugal, and one of the study’s authors. “This may suggest that allergic rhinitis increases the diversity and changes the composition of the upper airway’s microbiome.”
Allergic rhinitis, characterized by sneezing, nasal itching, and congestion, often coexists with asthma, which similarly involves airway inflammation and obstruction. These conditions may represent different aspects of the same underlying disease, making it essential to identify their connections and potential causes.
The research team examined the nasal mycobiome in a study involving 214 participants, primarily children and young adults from an immunology and asthma clinic in Porto. Of these, 155 had both allergic rhinitis and asthma, 47 had allergic rhinitis alone, and 12 had asthma without rhinitis. The study also included 125 healthy controls. The researchers collected nasal swabs from participants and sequenced the fungal DNA, focusing on two specific regions to identify various fungal species. The analysis aimed to provide a detailed understanding of each participant’s mycobiome.
Through quality control and sequencing, the team analyzed 306 samples to examine the relationships between fungal genera. They used network analysis to differentiate the fungal communities present in healthy individuals versus those with respiratory diseases. Additionally, the study explored how the fungi affect various metabolic pathways to understand the broader implications of these microbial variations.
The most prevalent fungal families across all samples were Ascomycota and Basidiomycota, with 14 dominant genera present. Among these, certain fungi have been identified as both allergenic and opportunistic pathogens. This supports the idea that the nasal cavity serves as a reservoir for fungi potentially involved in the development of allergic rhinitis and asthma. “The fungi sampled from patients with both allergic rhinitis and asthma also showed more evidence of connections between them than the fungi in the healthy participants’ noses and those who only had allergic rhinitis,” Delgado explained. This suggests that the fungal presence might be influencing the immune environment of the nose.
The researchers also identified an overabundance of three specific metabolic pathways in the mycobiomes of patients with allergic rhinitis and asthma. These pathways are associated with the production of 5-aminoimidazole ribonucleotide (AIR), a building block for DNA and RNA. AIR plays a crucial role in purine production, which is essential for energy metabolism and DNA synthesis. If future studies confirm this link, AIR may become a potential therapeutic target for treating or diagnosing these respiratory diseases.
However, Delgado noted that the study’s cross-sectional design could not account for all patient-specific variables, such as disease severity and treatment levels. “This gives us a broad picture but doesn’t show how the mycobiome changes over time,” he cautioned. Longitudinal studies could provide a clearer understanding of whether fungal presence drives disease progression and, if so, which specific fungi contribute.
The study presents a novel perspective on the role of fungi in allergic rhinitis and asthma. It highlights significant differences in fungal diversity and community structure between patients and healthy individuals, suggesting that nasal mycobiomes may influence disease processes. Further research into these fungi, including studies that address patient-specific variables and examine how mycobiomes evolve over time, will be crucial in determining whether targeting fungal pathways, like AIR, could offer new therapeutic strategies.
As Dr. Delgado emphasizes, “The key data and hypothesis are published here for others to replicate, and to finally link the laboratory bench to the clinic.” Future investigations will be essential for advancing our understanding of the connection between fungal diversity in the nasal cavity and the pathophysiology of allergic diseases.
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