Endotoxin decreases circulating EPC

Vienna, Austria -

Circulating endothelial progenitor cell levels have been reported to increase with exercise, smoking cessation, as well as taking statin drugs...amongst other things.

In a recent paper it was demonstrated that endotoxin induces a temporary (24 hr) decrease in the number of circulating endothelial progenitors (Mayr et al. Effects of low dose endotoxemia on endothelial progenitor cells in humans. Atherosclerosis. 2007 May 8).

The investigators administered 2ng/kg LPS intravenously to 32 healthy volunteers and observed the level of circulating blood endothelial cells. At 6 hours a nadir endothelial progenitor cells was reached, at which timepoint the average reduction in circulating endothelial progenitors cells was 62% as compared to baseline values.

The question here is "what causes this decrease?". It is not likely to be the result of decreased endothelial precursor cells from the marrow but actually a sequestration of the circulating endothelial precursor cells. What causes this sequestration is unknown to us right now but we appreciated any comments or thoughts that the reader may have.