Inflammatory Endotypes and Tissue Remodeling Features in Antrochoanal Polyps

Area of Science:

• Otorhinolaryngology
• Immunology
• Pathology

Background:

• Antrochoanal polyps (ACPs) are sinonasal inflammatory masses with poorly understood pathogenesis.
• Inflammatory patterns and tissue remodeling in ACPs require detailed characterization to differentiate them from other nasal polyps (NPs).

Purpose of the Study:

• To investigate and characterize the specific inflammatory endotypes and tissue remodeling features in ACPs.
• To compare these features with those found in eosinophilic and noneosinophilic nasal polyps.

Main Methods:

• Immunohistochemistry and immunofluorescence staining were used to assess inflammatory cell infiltration, edema, and fibrin deposition.
• Cytokine levels were quantified using the Bio-Plex assay, and coagulation/fibrinolytic markers were measured via RT-PCR and ELISA.
• Principle component and multiple correspondence analyses were employed to identify inflammatory patterns.

Main Results:

• ACPs showed significantly higher neutrophil infiltration and elevated levels of myeloperoxidase (MPO), interleukin-8 (IL-8), and interferon-gamma (IFN-γ) compared to control and other NP types.
• A distinct neutrophilic and type 1 inflammation pattern was identified in ACPs, with a low eosinophil cationic protein/MPO ratio.
• Increased edema and fibrin deposition, alongside decreased d-dimer and tissue plasminogen activator (tPA) levels, were observed in ACPs, more prominently than in eosinophilic NPs.

Conclusions:

• Antrochoanal polyps are characterized by a unique neutrophilic and type 1 inflammation endotype.
• Neutrophil-derived IFN-γ plays a role in the pathogenesis of ACPs by potentially reducing tPA production.
• Understanding these distinct inflammatory mechanisms may guide future therapeutic strategies for ACPs.