Role of expression of toll-like receptor 4 (TLR4) on medullary system cell and endothelial cell surface in rats with acute necrotizing pancreatitis

Abstract

Objective To investigate the role of expression of tall-like receptor 4 (TLR4) on medullary system cell (neutrophii, platelet) and endothelial cell surface in polymorphonuclear neutrophils (PMN) recruitment in rata with acute necrotizing pancreatitis. Methods C3H/He-J mice and C3H/He-N mice were divided into 4 groups by bone marrow transplantation: mosaic of medullary system cell TLR4-/- and endothelial cell TLR4 +/+ ; mosaic of medullary system cell TLR4 +/+ and endothelial cell TLR4-/-; mosaic of medullary system cell TLR4 +/+ and endothelial cell TLR4 -/-; mosaic of medullary system cell TLR4-/- and endothelial cell TLR4-/-, another control group was also established. ANP was induced in all these groups by intraperitoneal injection of cerulein and caudal vein injection of lipopolysaccharide. Serum amylase, pancreatic tissue naphthol AS-D chloroacetate esterase, MPO activity, TRL4 mRNA expression in peripheral blood granuloeyte was determined by RT-PCR, TRL4 protein expression in pancreatic tissue was measured by immunohistochemisty. Results Compared with that of control group, the levels of serum amylase in the 4 groups all significantly elevated and there was no difference among these 4 groups. Pathological scores of pancreas in the 4 groups were 5.52 ± 1.21, 5.18 ± 1.02, 2.03 ± 0. 82, 1.92 ± 0. 78, respectively; MPO activities were (1.834 ± 0. 170) U/g, (2. 596 ±0. 138) U/g, (0. 367 ±0. 018) U/g, (0. 202 ±0. 018) U/G, respectively; AS-D counts were 66.88 ± 2.17, 75.00 ± 2.43, 21.50 ± 2.38, 20.00 ± 2.19, respectively ; the expressions of TLR4mRNA of granular cell in peripheral blood were 0. 037 ± 1. 047 E-2, 1. 489 ± 8. 084 E-2, 1.470 ± 5. 210E-2, 0. 017 ± 6. 668 E-3, respectively; the 2 groups with endothelial eel1 TLR4 +/+ had strongly positive expression of TLR4 protein in vascular endothelial cell ; while the 2 groups with endothelial cell TLR4-/- had no expression; the pancreatic injuries, MPO activities, AS-D counts and TLR4 protein in the 2 groups with endothelial cell TLR4 +/+ were significantly higher than those in the 2 groups with endothelial cell TLR4-/-. Conclusions It was endothelial cell, not peripheral blood granulocyte, which played a key role in the process of neutrophil recruitment and pathological injure of ANP. Key words: Pancreatitis, acute necrotizing; Endotoxins; Chimera; Toll-like receptors