M2 macrophages coexist with a Th1-driven profile in periapical cysts

Area of Science:

• Oral pathology
• Immunology
• Inflammation research

Background:

• Periapical cysts are inflammatory lesions.
• The immune response in these cysts involves T-helper (Th) cells.
• Understanding the balance between Th1 and Th2 responses is crucial for managing these lesions.

Purpose of the Study:

• To investigate the roles of Th1 and Th2 immune responses in periapical cysts.
• To assess the presence and significance of M2 macrophages and specific cytokines (IL-1β, TNF-α, IL-6) in periapical cyst tissues.

Main Methods:

• Analysis of 24 periapical cyst cases.
• Immunohistochemical assessment of IL-1β, IL-6, TNF-α, and CD163 (a marker for M2 macrophages) in cystic tissues.
• Statistical analysis using paired Wilcoxon test and Spearman correlation.

Main Results:

• Higher expression of IL-1β, IL-6, TNF-α, and M2 macrophages was observed in the superficial regions of the cystic capsules.
• Significant positive correlations were found among the acute cytokines.
• CD163 expression correlated positively with TNF-α and IL-6 in superficial regions.

Conclusions:

• M2 macrophages are actively involved in the inflammatory response of periapical cysts.
• The findings suggest a coexistence of acute Th1-related cytokine activity and a chronic Th2-driven immune response.
• M2 macrophages, despite promoting healing, do not suffice for periapical cyst regression in the presence of active infection.