Immune complexes induce monocyte survival through defined intracellular pathways.

Area of Science:

• Immunology
• Cell Biology
• Molecular Medicine

Background:

• Monocyte recruitment and survival are crucial for persistent inflammation.
• Immune complexes (ICs) activate monocytes, promoting inflammation and inhibiting apoptosis, contributing to autoimmune diseases.

Purpose of the Study:

• To elucidate the intracellular signaling pathways involved in IC-mediated monocyte apoptosis inhibition.
• To investigate the roles of PI3K/Akt pathway, MAP kinases, NF-kappaB, and caspases in IC-activated monocytes.

Main Methods:

• Utilized selective inhibitors (LY294002, PD98059, SB203580, SN50, BMS345541) to block specific signaling molecules.
• Employed Western blot analysis to detect protein phosphorylation and expression (Akt, ERK1/2, p38, XIAP).
• Used electrophoretic mobility shift assay (EMSA) to assess NF-kappaB activation.

Main Results:

• IC-activated monocytes showed reduced apoptosis when PI3K/Akt, ERK1/2, p38, or NF-kappaB pathways were inhibited.
• Western blot confirmed IC-triggered phosphorylation of Akt, ERK1/2, and p38, and increased XIAP expression.
• EMSA demonstrated increased NF-kappaB activation, indicating its crucial role in IC-mediated apoptosis protection.

Conclusions:

• Monocyte apoptosis protection by ICs is dependent on the NF-kappaB signaling pathway.
• The identified signaling route offers potential therapeutic targets for IC-mediated inflammatory and autoimmune diseases.