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Anti-inflammatory effects of HDL revealed

By jeremyc | August 19, 2010

High-density lipoprotein (HDL) particles interfere with the binding of T-cell microparticles (MPs) to human monocytes, new research suggests.

The net result is to inhibit the production of pro-inflammatory cytokines, meaning this is one mechanism by which HDL cholesterol exerts an anti-inflammatory effect.

The findings are reported by an Italian team in the open-access journal PLoS One.

Rakel Carpintero (University of Geneva, Austria) and team have previously shown that HDL inhibits the production of interleukin (IL)-1β by T-cells in response to direct cellular contact or the generation of microparticles by stimulated T-cells (MPT).

However, HDL does not inhibit the production of its natural inhibitor, the secreted form of IL-1 receptor antagonist (sIL-1Ra).

In this study, the team used labeled MPs to assess their interaction with monocytes and the effects of HDL.

They found that MPT, but not MP generated by activated endothelial cells, bound to monocytes and triggered the production of cytokines. MPT did not bind T-cells, however.

In addition, HDL-induced inhibition of interleukin (IL)-1β production correlated with the inhibition of MPT binding to monocytes, and HDL interacted with MPTrather than with monocytes, suggesting that they bound the activating factor(s) of T-cell surface.

Furthermore, the production of pro-inflammatory cytokines and chemokines was induced by MPT and inhibited by HDL.

Taken together, these observations suggest that MP generated by stimulated T-cells bind monocytes but not T-lymphocytes, and that HDL inhibits the interaction of MPT with monocytes.

“Therefore, HDL may inhibit cytokine production in human monocytes by interfering with the binding of the activating factor(s) at the surface of stimulated T cells to receptor(s) at the surface of monocytes,” say Carpinteroet al.

These results therefore “shed new light on the mechanism by which HDL [particles] display their anti-inflammatory functions,” they conclude.

Topics: | Cholesterol |

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