Neutrophil Activated by the Famous and Potent PMA (Phorbol Myristate Acetate)

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Neutrophils are key immune cells involved in host defense.
• Phorbol 12-myristate 13-acetate (PMA) is a common tool to study neutrophil activation and functions.
• Neutrophil extracellular traps (NETs) are a crucial component of the innate immune response.

Purpose of the Study:

• To review the major signaling pathways in PMA-activated neutrophils.
• To elucidate the specific roles of protein kinase C (PKC) isoforms in neutrophil functions.
• To propose novel insights into the regulation of NET formation and its relationship with reactive oxygen species (ROS).

Main Methods:

• Literature review of research on PMA-activated neutrophils over the past 31 years.
• Analysis of signaling pathways involving PKC isoforms, ROS production, and cytoskeleton remodeling.
• Investigation of the interplay between peptidylarginine deiminase 4 (PAD4), serine proteases, and NET formation.

Main Results:

• PKC isoforms differentially regulate ROS production (PKC α, β, δ) and cytoskeleton remodeling (PKC βII, ζ).
• Actin polymerization and remodeling are linked to neutrophil chemotaxis and ROS balance.
• A potential regulatory mechanism balancing ROS production and NET formation is suggested.
• Serine proteases may modulate PAD4 activity, influencing IL-1β release and NET formation via gasdermin D cleavage.
• Inhibition of serine proteases leads to NET formation primarily through PAD4-mediated citrullination.

Conclusions:

• PMA activates complex signaling cascades in neutrophils involving distinct PKC isoforms.
• The balance between ROS production and NET formation is tightly regulated.
• Serine proteases and PAD4 play critical, potentially opposing, roles in NET release mechanisms.
• This review offers new interpretations of established findings and highlights areas for future research in neutrophil biology.