Extracellular ATP-stimulated macrophages produce macrophage inflammatory protein-2 which is important for neutrophil...

Area of Science:

• Immunology
• Cell Biology
• Inflammation Research

Background:

• Macrophages are primary producers of chemokines like macrophage inflammatory protein-2 (MIP-2) and keratinocyte-derived chemokine (KC), crucial for neutrophil recruitment.
• Extracellular ATP is present in inflammatory tissues and elicits immune responses in macrophages, but its effect on neutrophil migration is not fully understood.

Purpose of the Study:

• To investigate the role of ATP-stimulated macrophages in the production of MIP-2.
• To elucidate the mechanisms underlying ATP-induced MIP-2 production and its impact on neutrophil migration.

Main Methods:

• Mice were injected intraperitoneally with ATP, and peritoneal lavage fluid was analyzed for neutrophils, MIP-2, and KC levels.
• Peritoneal exudate macrophages (PEMs) were treated with ATP in vitro to assess MIP-2 and KC production.
• Receptor involvement (P2X7, P2Y2), reactive oxygen species (ROS) production, and signaling pathways (ERK1/2, p38 MAPK) were investigated using specific inhibitors and antioxidants.

Main Results:

• ATP injection increased neutrophil counts and MIP-2/KC levels in mouse peritoneal cavities.
• In vitro, ATP stimulated MIP-2 production in PEMs via P2X7 and P2Y2 receptors, but not KC production.
• ATP-induced MIP-2 production was linked to ROS generation and activation of ERK1/2 and p38 MAPK pathways; antioxidant and pathway inhibitors reduced MIP-2 levels. MIP-2 neutralization decreased neutrophil influx.

Conclusions:

• Extracellular ATP triggers macrophages to produce MIP-2 through ROS generation and specific kinase signaling pathways.
• ATP-induced MIP-2 production by macrophages is a significant mechanism driving neutrophil migration during inflammation.