Alternatively activated macrophages; a double-edged sword in allergic asthma

Area of Science:

• Immunology
• Respiratory Medicine

Background:

• Macrophages are key immune cells in innate and adaptive immunity.
• Allergic asthma involves abundant lung macrophages, with M1 and alternatively activated macrophages (AAM) or M2 cells being prominent.
• AAM are subdivided into M2a, M2b, M2c, and M2d subtypes.

Purpose of the Study:

• To review the protective and pathogenic roles of M2a macrophages in allergic asthma.
• To elucidate the functions of specific M2a proteins and markers in asthma pathogenesis.
• To clarify the controversial role of M2a macrophages in asthma.

Main Methods:

• Literature review focusing on IL-4-induced macrophages in asthma.
• Analysis of M2a macrophage functions, including surface markers, enzymes, secreted proteins, chemokines, cytokines, signal transduction proteins, and transcription factors.
• Discussion of the dual role of AAM in allergic asthma.

Main Results:

• IL-4 is a critical cytokine in both alternative macrophage activation and asthma pathogenesis.
• M2a macrophages exhibit both protective and pathogenic functions in allergic asthma.
• Specific M2a proteins and markers contribute to asthma pathogenesis.

Conclusions:

• Alternatively activated macrophages (AAM) present a "double-edged sword" in allergic asthma.
• Further studies should focus on selectively modulating protective and pathogenic M2a markers.
• Targeting M2a macrophage pathways may offer therapeutic strategies for allergic asthma.