Differences in the paranasal sinuses between germ-free and pathogen-free mice

Area of Science:

• Microbiology
• Immunology
• Otolaryngology

Background:

• The role of bacteria in chronic rhinosinusitis (CRS) pathogenesis is not fully understood.
• Commensal bacteria, similar to their role in the gut, may influence paranasal sinus anatomy and mucosal immunity.
• Germ-free (GF) mouse models offer a unique approach to study the impact of commensal bacteria on sinus development.

Purpose of the Study:

• To investigate the structural and functional effects of commensal microbiota on murine paranasal sinuses.
• To compare the sinus anatomy and mucosal characteristics of germ-free mice with pathogen-free controls.

Main Methods:

• Computed tomography (CT) was used to assess sinus pneumatization and geometry in GF and control mice.
• Histological analysis examined mucosal thickness, epithelial thickness, cilia, collagen, goblet cells, and nasal-associated lymphatic tissue (NALT).

Main Results:

• No significant radiological differences were observed between GF and control mice.
• GF mice displayed significantly thinner mucosa and epithelium, increased collagen deposition, fewer goblet cells, and reduced NALT.
• Regional analysis revealed differences in middle and posterior sinus sections, including thinner mucosa, thinner epithelium, fewer cilia, and more collagen in GF mice.

Conclusions:

• Commensal microbiota are essential for the normal development and structure of murine paranasal sinuses.
• Alterations in commensal microbiota composition could disrupt the host-microbe dialogue, potentially contributing to CRS pathogenesis.