Aim: To determine the in vivo effects of phagocytic blockade of Kupffer cell (KC) on the release of proinflammatory cytokines in small intestinal lesion and on the integrity of intestinal tract by using gadolinium chloride (GdCl(3)) during early endotoxemia.
Methods: Wistar rats were divided into three groups: Group A, rats were injected with endotoxin (E. coli O111:B(4), a dose of 12 mg x kg(-1)) only; Group B, rats were pretreated intravenously with 25 mg of GdCl(3) per kg 24 h are given endotoxin; and Group C, sham operation only. All animals were sacrificed 4 h after endotoxin injection. In portion of the rats of three groups, bile duct was cannulated, which the bile was collected externally. Morphological changes of ileum were observed under light microscopy and electronic microscopy. The KC were isolated from rats by collagenase perfusion and in KC, expression of TNF-alpha and IL-6 mRNA were determined by RT-PCR analysis. Plasma and bile TNF-alpha and IL-6 Levels were determined by enzyme-linked immunosorbent assay (ELISA).
Results: In group A, there were neutrophil infiltration and superficial epithelial necrosis of the ileal villi, sloughing of mucosal epithelium, and disappearance of some villi. In group B, the ileal mucosal damage was much reduced. which in group C, no significant morphological changes were seen. GdCl(3) pretreatment decreased significantly the expression of TNF-alpha and IL-6 mRNA in group B (4.32+/-0.47 and 4.05+/-0.43) when compared to group A (9.46+/-1.21 and 9.04+/-1.09) (P<0.05). There was no significant expression of TNF-alpha and IL-6 mRNA in group C (1.03+/-0.14 and 10.4+/-0.13). In rats of group A, the levels of TNF-alpha and IL-6 in bile and plasma were 207+/-29 ng x L(-1), 1032+/-107 ng x L(-1), 213+/-33 ng x L(-1), and 1185+/-127 ng x L(-1), respectively. In group B, they were 113+/-18 ng x L(-1), 521+/-76 ng x L(-1), 147+/-22 ng x L(-1), and 572+/-54 ng x L(-1), respectively. In group C, they were 67+/-10 ng x L(-1), 72+/-13 ng x L(-1), 109+/-18 ng x L(-1), and 118+/-22 ng x L(-1) respectively. There were significant difference between the three group (P<0.05).
Conclusion: KC release cytokines TNF-alpha and IL-6 causing damage to the integrity of intestinal epithelium and play a crucial role in the initiation and progression of intestinal mucosal damage during early endotoxemia.