Macrophage cytokine response to particles and lipopolysaccharide in vitro

Area of Science:

• Biomaterials Science
• Immunology
• Cell Biology

Background:

• Biologic molecules adsorbed onto particles are hypothesized to be critical in macrophage response.
• Adsorbed endotoxins, a type of bacterial debris, are ubiquitous and bind strongly to various materials, suggesting their importance.

Purpose of the Study:

• To investigate the in vitro macrophage response to particles with and without adsorbed lipopolysaccharide (LPS) endotoxin.
• To determine the influence of particle material (high-density polyethylene and Co-Cr-Mo alloy) and surface contaminants on macrophage cytokine secretion.

Main Methods:

• Utilized murine-transformed peritoneal macrophages (IC-21) in an in vitro system.
• Measured secretions of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) as indicators of macrophage response.
• Exposed particles and experimental chambers to lipopolysaccharide (LPS) or cleaned them with ethanol and saline.

Main Results:

• Minimal cytokine secretion was observed in response to cleaned particles and polypropylene chambers without LPS exposure.
• High levels of cytokine secretion occurred when chambers and particles were exposed to LPS, even after rinsing.
• Distinct cytokine secretion patterns emerged based on the presence of particles and whether they were polymer or metal.

Conclusions:

• Adsorbed molecules on material surfaces profoundly impact macrophage responses.
• Particle surface chemistry and microstructure influence the adsorption and configuration of molecules, thereby modulating interactions with macrophage surface receptors.