Different effects of adiponectin isoforms in human monocytic cells

Area of Science:

• Immunology
• Endocrinology
• Cell Biology

Background:

• Adiponectin (APM) is an adipokine with known immunosuppressive, antidiabetic, and antiatherosclerotic effects.
• Serum APM exists in low molecular weight (LMW) and higher molecular weight (HMW) forms, activating distinct signaling pathways.
• Understanding isoform-specific functions in monocytic cells is crucial for targeted therapeutic strategies.

Purpose of the Study:

• To investigate and compare the effects of LMW-APM and HMW-APM on monocytic cells, focusing on apoptosis and inflammation.
• To elucidate the distinct molecular mechanisms underlying the actions of different APM isoforms in immune cells.

Main Methods:

• Utilized recombinant LMW-APM (produced in insect cells) and APM from higher eukaryotic cells (containing HMW forms).
• Assessed apoptosis, macrophage scavenger receptor A (MSR A) mRNA expression, and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in THP-1 cells and human monocytes.
• Measured interleukin (IL)-6 and IL-10 secretion, and analyzed nuclear factor-kappaB (NF-kappaB) pathway components.

Main Results:

• Both LMW-APM and HMW-APM induced apoptosis, reduced MSR A mRNA, and stimulated AMPK phosphorylation in monocytic cells.
• HMW-APM increased IL-6 secretion but did not suppress lipopolysaccharide (LPS)-induced IL-6 release.
• LMW-APM suppressed LPS-mediated IL-6 release, stimulated IL-10 secretion, and reduced NF-kappaB pathway activation.

Conclusions:

• Adiponectin isoforms share common effects on monocytic cells, including apoptosis induction, AMPK activation, and MSR reduction.
• LMW-APM demonstrates specific anti-inflammatory properties by modulating cytokine secretion and NF-kappaB signaling, distinct from HMW-APM.
• Isoform-specific actions of adiponectin offer potential for targeted therapeutic interventions in inflammatory and metabolic diseases.