Related Experiment Video
Updated: May 5, 2026
Assessing Anti-fungal Activity of Isolated Alveolar Macrophages by Confocal Microscopy
Published on: July 9, 2014
High M2/M1 Macrophage Ratio Observed in Nasal Polyps Formed in Allergic Fungal Rhinosinusitis
Eiichi Kato1,2, Akifumi Muramoto1, Natsumi Yonemoto1
1Department of Tumor Pathology, Faculty of Medical Sciences, University of Fukui, Eiheiji, Japan.
Abstract:
Allergic fungal rhinosinusitis (AFRS) shares similarities with eosinophilic chronic rhinosinusitis (ECRS), both characterized by intractable nasal polyps. The key distinction lies in the presence of fungal infection within the nasal cavity. While ECRS nasal polyps are known for significant infiltration of M2 macrophages and eosinophils, as well as an increase in high endothelial venule (HEV)-like vessels, these features are less commonly reported in AFRS. This study compared clinicopathological findings between AFRS (n=10), ECRS (n=12), and non-ECRS (n=10) patients' nasal polyps using immunohistochemical analysis for CD163 and CD68 to assess the M2/M1 macrophage ratio, and peripheral lymph node addressin (PNAd) and CD34 to evaluate the proportion of HEV-like vessels. AFRS showed a significantly higher number of CD163-positive M2 macrophages and an increased M2/M1 ratio compared with ECRS. However, the percentage of HEV-like vessels and the number of eosinophils infiltrating the nasal polyps were similar in both AFRS and ECRS. The observed increase in M2 macrophages in AFRS nasal polyps is presumed to be induced by fungal infection in the nasal cavity, in comparison with ECRS. These results highlight the distinctive immunological profiles of AFRS and ECRS, emphasizing the role of macrophage polarization in their pathogenesis.
Insights
Allergic fungal rhinosinusitis (AFRS) shows more M2 macrophages than eosinophilic CRS (ECRS). Fungal infection likely drives this macrophage difference in AFRS nasal polyps.
Area of Science:
- Immunology
- Pathology
- Otolaryngology
Background:
- Allergic fungal rhinosinusitis (AFRS) and eosinophilic chronic rhinosinusitis (ECRS) present with difficult-to-treat nasal polyps.
- ECRS polyps typically feature M2 macrophages, eosinophils, and high endothelial venule (HEV)-like vessels.
- These features are less consistently documented in AFRS, suggesting distinct underlying mechanisms.
Purpose of the Study:
- To compare clinicopathological findings in nasal polyps from patients with AFRS, ECRS, and non-ECRS.
- To investigate differences in macrophage polarization and HEV-like vessel presence between AFRS and ECRS.
Main Methods:
- Immunohistochemical analysis of nasal polyp tissues from AFRS (n=10), ECRS (n=12), and non-ECRS (n=10) patients.
- Assessment of M2/M1 macrophage ratio using CD163 and CD68.
- Evaluation of HEV-like vessels using peripheral lymph node addressin (PNAd) and CD34.
Main Results:
- AFRS nasal polyps exhibited significantly higher CD163-positive M2 macrophages and an increased M2/M1 ratio compared to ECRS.
- The proportion of HEV-like vessels and eosinophil infiltration were similar between AFRS and ECRS groups.
- These findings suggest fungal infection may induce M2 macrophage polarization in AFRS.
Conclusions:
- AFRS and ECRS possess distinct immunological profiles, particularly concerning macrophage polarization.
- Increased M2 macrophages in AFRS are likely a response to fungal presence.
- Macrophage polarization plays a crucial role in the pathogenesis of AFRS and ECRS.
