A previously unrecognized protein-protein interaction between TWEAK and CD163: potential biological implications.

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• TWEAK (TNF-like weak inducer of apoptosis) is a TNF superfamily member involved in various biological processes.
• Fibroblast growth factor inducible 14 (Fn14)/TweakR is known as a TWEAK receptor, but other molecules may modulate its function.

Purpose of the Study:

• To identify novel TWEAK-binding proteins.
• To investigate the role of CD163 in TWEAK binding and function.

Main Methods:

• Combinatorial peptide library screening to identify TWEAK-binding motifs.
• Flow cytometry and immunofluorescence assays to detect TWEAK binding to monocytes.
• Competition assays using soluble CD163, Fn14/TweakR, and anti-CD163 antibodies.

Main Results:

• Cyclic peptides mimicking CD163's natural ligand (haptoglobin-hemoglobin) bound specifically to TWEAK.
• TWEAK demonstrated dose-dependent binding to CD163 on human monocytes.
• Monocytes expressing CD163 but not Fn14/TweakR could bind TWEAK, sequester it, and prevent tumor cell apoptosis.

Conclusions:

• CD163 functions as an alternative receptor for TWEAK on monocytes.
• CD163 may act as a TWEAK scavenger in pathological conditions, influencing TWEAK-mediated apoptosis.
• These findings reveal a novel interaction between TWEAK and the innate immune system via CD163.