Enhanced release of elastase is not concomitant with increased secretion of granulocyte-activating cytokines in whole blood from patients with sepsis
W. Ertel, D. Jarrar, M. Jochum, V. Thiele, J. Kenney, E. Faist and F. W. Schildberg
Department of Surgery, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
BACKGROUND: The proteolytic enzyme elastase released by granulocytes
(polymorphonuclear leukocytes [PMN]) in high concentrations during sepsis
causes degradation of essential plasma proteins, endothelial damage, and
tissue edema. This may result in organ dysfunction and organ failure during
sepsis, since increased elastase plasma levels correlate with the mortality
rate of patients with sepsis. In vitro studies demonstrated a regulatory
role of inflammatory cytokines (tumor necrosis factor-alpha [TNF-alpha],
interleukin 1 beta [IL-1 beta], IL-8]) upregulating protease release by
PMN. In this light, the interactions between cytokine release by
macrophages and altered elastase secretion during sepsis remain to be
determined. METHODS: An ex vivo model consisting of lipopolysaccharide
stimulation of human whole blood as a relevant physiological milieu was
used. Heparinized blood was obtained from 20 patients with sepsis syndrome
(APACHE II [Acute Physiology and Chronic Health Evaluation II] score 28.5
+/- 1.2 points [mean +/- SD]) on days 0 through 3, 5, 7, and 10 after
sepsis diagnosis and from 20 control patients without infection. Blood was
incubated with lipopolysaccharide (1 mg/L) for 8 hours. Plasma levels of
elastase, TNF-alpha, IL-1 beta, and IL-8 were determined using
enzyme-linked immunosorbent assay or bioassay (TNF-alpha), respectively.
RESULTS: Elastase plasma levels in whole blood from patients with sepsis
were increased up to 188% (P < .01) above normal, while the release of
TNF-alpha (-87%), IL-1 beta (-91%), and IL-8 (-51%) was markedly (P <
.01) decreased compared with control patients. Neutralization of TNF-alpha
or IL-1 beta did not attenuate the increased release of elastase.
CONCLUSIONS: These data indicate an increased release of elastase by PMN
despite a reduced secretion of PMN-activating cytokines. Although priming
effects of TNF-alpha, IL-1 beta, and IL-8 on protease secretion in vivo
cannot be excluded completely, other mediators or mechanisms may be
involved in the upregulation of detrimental protease release during sepsis.
