TIPE2 Inhibits MGD Inflammation by Regulating Macrophage Polarization

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• Meibomian gland dysfunction (MGD) is a common eyelid condition.
• The role of macrophage polarization in MGD pathogenesis is not fully understood.
• Tumor necrosis factor-α (TNF-α)-induced protein 8-like 2 (TIPE2) is implicated in inflammatory processes.

Purpose of the Study:

• To investigate the role of TIPE2-regulated macrophage polarization in MGD.
• To determine the specific macrophage subtypes involved in MGD inflammation.
• To explore TIPE2 as a potential therapeutic target for MGD.

Main Methods:

• Utilized apolipoprotein E knockout (ApoE-/-) mice as an MGD model.
• Assessed meibomian gland secretory function using oil red staining.
• Quantified M1 and M2 macrophage markers via immunofluorescence in mice and human MGD tissues.
• Analyzed TIPE2 expression and its correlation with macrophage polarization.
• Induced M1 and M2 macrophage polarization in vitro using lipopolysaccharide (LPS) and interleukin-4 (IL-4), respectively, and measured TIPE2 mRNA levels.

Main Results:

• MGD mice exhibited more severe eyelid fat congestion and M1 macrophage infiltration compared to normal mice.
• M1 macrophages were the dominant inflammatory cell type in MGD mouse models and human MGD tissues, with higher M1 counts in severe MGD.
• TIPE2 expression positively correlated with M2 macrophage markers in MGD tissues.
• TIPE2 mRNA levels decreased in LPS-induced M1 macrophages but increased in IL-4-induced M2 macrophages.

Conclusions:

• M1 macrophages are the primary infiltrating inflammatory cells in the meibomian glands of MGD patients and mouse models.
• TIPE2 plays a role in regulating macrophage polarization in MGD.
• TIPE2 represents a potential anti-inflammatory target for MGD treatment by promoting M2 macrophage polarization.