幽门螺杆菌脂多糖对肠嗜铬样细胞功能的影响

Influence of Helicobacter pylori lipopolysaccharide on the function of enterochromaffin like cells in vitro

目的 通过幽门螺杆菌（Ｈｐ） 的脂多糖抗原对体外大鼠肠嗜铬样细胞功能的影响，深入探讨Ｈｐ 改变胃酸分泌和黏膜增生的病理机制。方法 通过链球蛋白酶消化、淘析法和梯度离心分离出纯化率９５％ 、成活率＞ ９０ ％ 的大鼠胃的肠嗜铬样细胞。短期培养后通过酶标免疫法，ＢｒｄＵ掺入试验分别测定肠嗜铬样细胞基础和刺激后的组胺分泌及ＤＮＡ 增生。结果 脂多糖抗原刺激基础组胺的分泌（ＥＣ５０４ ×１０－１１ ｍｏｌ／Ｌ） ，同时显著增强胃泌素刺激组胺分泌的作用（ＥＣ５０ １０－１０ ｍｏｌ／Ｌ）。生长抑素（１０－１２ ｍｏｌ／Ｌ）能完全抑制这些作用而胃泌素拮抗剂Ｌ３６５２６０ 则无明显抑制作用。脂多糖抗原不能刺激肠嗜铬样细胞的ＤＮＡ合成，但明显增强胃泌素对其ＤＮＡ的合成（ＥＣ５０ １０－１０ ｍｏｌ／Ｌ）。大肠杆菌的脂多糖抗原（１０－ １２ ～１０ －６ ｍｏｌ／Ｌ） 对肠嗜铬样细胞的组胺分泌和ＤＮＡ合成均无明显作用。结论 在体外，Ｈｐ 直接影响肠嗜铬样细胞的增生和分泌。高度提示脂多糖抗原同肠嗜铬样细胞的互相作用参于了Ｈｐ 感染引起的酸分泌异常和胃黏膜的病理改变。

Objective To investigate the relationship between Helicobacter pylori (Hp) infection and pathophysiology of abnormal gastric acid secretion and mucosal proliferation by studying the effect of Hp lipopolysaccharide (LPS) on the function of enterochromaffin like (ECL) cells in vitro. Methods Pure isolated ECL cell preparation with a purity of ±95% was developed by proteinase digestion, elutriation and density gradient centrifugation with viability of >95% as determined by trypan blue exclusion. After a short duration of culture basal and stimulated histamine secretion and DNA synthesis of ECL cells were measured by enzyme immunoassay and bromodeoxyuridine (BrdU) uptake, respectively. Results Hp LPS stimulated basal and gastrin stimulated histamine secretion (EC 50 4×10 -11 mol/L and EC 50 10 -10 mol/L respectively). These effects were completely inhibited by somatostatin (10 -10 mol/L) but not by gastrin receptor antagonist L 365 260 . Hp LPS did not stimulate basal DNA synthesis but significantly increased gastrin stimulated BrdU uptake with EC 50 of 10 -10 mol/L. Escherichia coil LPS had no significant effect on both histamine secretion and DNA synthesis. Conclusion Hp stimulates both ECL cell proliferation and secretion in vitro. An interaction between Hp LPS and ECL cells may contribute to the reported abnormalities in acid secretion and gastric pathophysiology noted in Hp infection.