Type 2 inflammation in chronic rhinosinusitis without nasal polyps: Another relevant endotype

Area of Science:

• Immunology
• Otorhinolaryngology

Background:

• Chronic rhinosinusitis without nasal polyps (CRSsNP) is typically viewed as a type 1 immune-mediated condition.
• The role of type 2 immune responses in CRSsNP has been under-investigated, despite evidence suggesting a subgroup with type 2 inflammation.

Purpose of the Study:

• To investigate the presence and clinical significance of type 2 immune responses in patients diagnosed with CRSsNP.

Main Methods:

• Endotyping 240 CRSsNP patients based on cytokine expression.
• Collecting clinical data including recurrence, asthma, allergy, and blood cell counts.
• Analyzing mucosal biopsies for eosinophils, Charcot-Leyden crystals, and eosinophil extracellular traps in a subset of patients.

Main Results:

• Nearly half (49%) of CRSsNP patients exhibited a type 2 immune response, characterized by elevated IL-4, IL-5, IgE, and eosinophils.
• This type 2 CRSsNP subgroup showed increased eosinophilic inflammation, Charcot-Leyden crystals, and eosinophil extracellular traps.
• Patients with type 2 CRSsNP had a higher prevalence of asthma and disease recurrence compared to non-type 2 CRSsNP patients.

Conclusions:

• A significant portion of CRSsNP cases involve a type 2 immune response, distinct from the typical type 1 profile.
• This type 2 inflammation in CRSsNP, though less pronounced than in CRSsNP with nasal polyps, has a notable clinical impact, including increased asthma association and recurrence.