Chronic Rhinosinusitis-Could Phenotyping or Endotyping Aid Therapy?

Area of Science:

• Otolaryngology
• Immunology
• Genetics

Background:

• Chronic rhinosinusitis (CRS) is a complex upper airway inflammatory disease.
• Current phenotyping of CRS, typically with (CRSwNP) or without (CRSsNP) nasal polyps, has limitations due to disease progression and overlapping inflammatory patterns.
• Inflammatory patterns in CRS range from eosinophilic (CRSwNP) to neutrophilic (CRSsNP), but this is a spectrum rather than a dichotomy.

Purpose of the Study:

• To review the current understanding of chronic rhinosinusitis (CRS) phenotyping and endotyping.
• To explore various treatment modalities for CRS based on its endotype.
• To highlight the importance of endotype-directed therapies for improved patient outcomes.

Main Methods:

• Comprehensive literature search of PubMed, Google, Google Scholar, and Proquest Central Database.
• Review of studies focusing on CRS phenotyping, endotyping, and treatment strategies.
• Analysis of different classification systems for CRS endotypes based on immune responses and biomarkers.

Main Results:

• CRS can be phenotyped based on the presence of nasal polyps and inflammatory cell predominance (eosinophilic vs. neutrophilic).
• Endotyping classifies CRS into distinct pathobiological mechanisms, including Th2 immune responses (non-type, moderate, severe) and type 2 cytokine, eosinophil, IgE, or leukotriene-based approaches.
• Specific CRSwNP subtypes include nonsteroidal anti-inflammatory drug-exacerbated respiratory disease, allergic fungal sinusitis, and eosinophilic arteritis.
• General treatments include nasal douching; surgery requires careful consideration.
• Endotype-directed therapies encompass glucocorticosteroids, antibiotics, aspirin, antifungals, anticytokines, and immunoglobulin replacement.

Conclusions:

• Endotyping CRS enables the identification of patient subgroups with a higher probability of successful treatment.
• Patients with moderate type 2 immune reactions or acquired immune deficiency are examples of groups likely to benefit from endotype-directed therapies.
• Integrated endotyping of upper and lower airways is recommended, especially in cases of CRSwNP with severe asthma, to optimize therapeutic strategies.