Plasma lipid concentrations correlate inversely with CPB-induced interleukin-6 release.
OBJECTIVE
Cardiopulmonary bypass (CPB) is characterized by translocation of intestinal endotoxin and subsequent endogenous production of the pro-inflammatory cytokine interleukin-6 (IL-6). Plasma lipid fractions, especially high density lipoproteins, bind and neutralize endotoxin and, therefore, inhibit endotoxin-induced macrophage cytokine production, including IL-6. Increased IL-6 plasma levels have been implicated in adverse consequences associated with CPB. Previous studies demonstrated large interpatient variability in IL-6 plasma levels after CPB. The purpose of this study was to evaluate the relationship between plasma lipid concentrations and the concentrations of IL-6 following CPB in humans.


METHODS
In a prospective study, a group of 15 patients selected to exclude variables known to influence post-CPB plasma levels of IL-6 (preoperative left ventricular ejection fraction > 45%, similar durations of aortic cross clamping and total CPB time, similar temperature control during CPB, and avoidance of platelet transfusion and shed mediastinal blood re-infusion), IL-6 was measured at baseline, one and 24 hr post-CPB.


RESULTS
Interleukin-6 plasma concentrations (mean +/- SD) increased at one (142 +/- 89 pg.ml-1, P < 0.05) and 24 (129 +/- 82 pg.ml-1, P < 0.05) hr post-CPB compared with baseline (1.5 +/- 1 pg.ml-1) concentrations. An inverse correlation was found between IL-6 plasma concentrations at one hour post-CPB and plasma cholesterol concentrations (r = -0.592, P = 0.02), high density lipoprotein (r = -0.595, P = 0.02), and low density lipoprotein (r = -0.656, P = 0.01).


CONCLUSIONS
These results suggest that plasma lipids attenuate the production of IL-6 during CPB and may partly explain the variability of interpatient levels of IL-6 reported post-CPB by others.
Department of Anesthesiology, University of Nebraska Medical Center, Omaha 68198-4455, USA.
G E
GE
Hill
R
R
Pohorecki
C W
CW
Whitten
D000368:Aged; D001804:Blood Transfusion, Autologous; D001831:Body Temperature; D002315:Cardiopulmonary Bypass; D002784:Cholesterol / Q000097:blood; D004731:Endotoxins / Q000037:antagonists & inhibitors / Q000378:metabolism; D005500:Follow-Up Studies; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D007413:Intestinal Mucosa / Q000378:metabolism; D008074:Lipoproteins / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D017713:Platelet Transfusion; D011446:Prospective Studies; D012044:Regression Analysis; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left; D000093242:Interleukin-6 Inhibitors
D002784:Cholesterol; D004731:Endotoxins; D015850:Interleukin-6; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D000093242:Interleukin-6 Inhibitors