C3a receptor antagonism as a novel therapeutic target for chronic rhinosinusitis

Area of Science:

• Immunology
• Complement System Biology
• Rhinology

Background:

• Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory condition with incompletely understood causes.
• Emerging research suggests the complement system plays a role in CRSwNP immunopathology.

Purpose of the Study:

• To investigate the role of the complement system, particularly complement 3 (C3) and its byproduct complement anaphylatoxin 3a (C3a), in the sinonasal mucus of CRSwNP patients.
• To explore the therapeutic potential of targeting the complement 3a receptor (C3aR) in a preclinical model of CRSwNP.

Main Methods:

• Proteomic pathway enrichment analysis of sinonasal mucus from CRSwNP patients and controls.
• Quantification of C3 and C3a in sinonasal epithelial cells and mucus.
• In vitro studies involving Aspergillus fumigatus (Af) extract stimulation of CRSwNP cells.
• In vivo studies using a mouse model of Af-induced chronic rhinosinusitis (CRS), with C3aR deficiency or pharmacological inhibition.

Main Results:

• Complement cascade pathways were enriched in the nasal mucus of CRSwNP patients.
• Sinonasal mucus C3 levels correlated with disease severity, unlike systemic C3 levels.
• CRSwNP epithelial cells released more C3 and C3a upon Af extract exposure.
• C3aR signaling inhibition reduced Af-induced C3 and C3a release in vitro and in vivo.
• C3aR deficiency or inhibition significantly reduced inflammation and CRS development in the mouse model.

Conclusions:

• Local complement activation within the sinonasal tissue is associated with CRSwNP severity.
• Targeting the C3aR pathway demonstrates significant therapeutic potential for ameliorating Af-induced CRS in a preclinical setting.