macrophage activation

Definition

Target type: biologicalprocess

A change in morphology and behavior of a macrophage resulting from exposure to a cytokine, chemokine, cellular ligand, or soluble factor. [GOC:mgi_curators, ISBN:0781735149, PMID:14506301]

Macrophage activation is a complex biological process that involves a series of steps leading to the transformation of resting macrophages into highly active phagocytic cells capable of eliminating pathogens and cellular debris. This process is initiated by the recognition of pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) by pattern recognition receptors (PRRs) expressed on the surface of macrophages. Upon recognition of these danger signals, macrophages undergo a series of signaling events that culminate in the activation of transcription factors such as NF-κB and AP-1, which in turn regulate the expression of a wide range of genes involved in macrophage activation. These genes encode for proteins that contribute to the enhanced phagocytic capacity of activated macrophages, the production of various cytokines and chemokines that recruit and activate other immune cells, and the expression of antimicrobial molecules that directly kill pathogens. There are two main pathways of macrophage activation:

**Classical Activation:** This pathway is primarily triggered by exposure to pro-inflammatory stimuli such as lipopolysaccharide (LPS), interferon-gamma (IFN-γ), or tumor necrosis factor-alpha (TNF-α). Classical activation results in the differentiation of macrophages into M1 macrophages, characterized by their robust production of pro-inflammatory cytokines like TNF-α, IL-1β, and IL-6, and their enhanced ability to kill intracellular pathogens.

**Alternative Activation:** This pathway is induced by anti-inflammatory stimuli like IL-4 or IL-13, leading to the differentiation of macrophages into M2 macrophages. M2 macrophages are characterized by their production of anti-inflammatory cytokines such as IL-10, their role in tissue repair and wound healing, and their ability to suppress inflammation.

In summary, macrophage activation is a dynamic process involving the recognition of danger signals, signaling events, and the expression of a wide range of genes that transform macrophages into highly functional effector cells capable of both fighting infections and promoting tissue repair.'
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Proteins (6)

Compounds (85)