Tumor necrosis factor-alpha hyporesponsiveness of rat intestinal mononuclear cells and whole portal venous blood after hemorrhagic shock

Abstract

Objective: To determine the effect of hemorrhagic shock on spontaneous and endotoxin-induced cytokine release from intestinal mononuclear cells compared with whole portal venous blood and splenic macrophages.

Design: Random assignment to either unmanipulated control group, sham operation group, or hemorrhagic shock group.

Setting: University animal laboratory.

Subjects: Male Wistar rats, weighing between 300 and 350 g.

Interventions: Rats were bled to 30 mm Hg for 30 mins by withdrawal/reinfusion of shed blood and Ringer's lactate equivalent to the shed blood volume.

Measurements: Rats were killed immediately, 4 hrs, or 24 hrs after reperfusion. Portal venous blood, splenic macrophages, and small bowel mononuclear cells were obtained and spontaneous (unstimulated) and endotoxin-induced supernatant tumor necrosis factor (TNF)-alpha (WEHI 164 subclone 13) and interleukin (IL)-6 (B 13-29 clone 9) release was measured by bioassay.

Main results: Increased endotoxin-induced TNF release from gut mononuclear cells and portal venous blood was suppressed 4 and 24 hrs after reperfusion compared with sham operated animals (p < .05). TNF release from splenic macrophages could be significantly increased (p < .05) by addition of endotoxin in all groups with no difference between control, sham, and shock animals. In shock animals, endotoxin-stimulated IL-6 release was significantly greater (p < .05) than control and sham operated rats 4 hrs after reperfusion in portal blood and from splenic macrophages. In contrast to splenic macrophages, gut mononuclear cells and portal venous blood demonstrated high spontaneous IL-6 concentrations without further stimulation by endotoxin.

Conclusions: Hemorrhagic shock induced a hyporesponsiveness from gut mononuclear cells and whole portal venous blood 4 and 24 hrs after reperfusion. Spontaneous and endotoxin-induced stimulation of IL-6 indicates a different modulation of cytokines in gut, portal vein and spleen. The differences of gut mononuclear cells and portal blood compared with the splenic macrophages indicate a compartmentalized cytokine response.