Graham M F, Bryson G R, Diegelmann R F
Division of Pediatric Gastroenterology (Children's Medical Center), Medical College of Virginia, Richmond.
Gastroenterology. 1990 Aug;99(2):447-53. doi: 10.1016/0016-5085(90)91028-5.
Intestinal smooth muscle cells play a major role in the stricture formation that complicates chronic intestinal inflammation, by proliferating and producing collagen. Transforming growth factor beta 1 has been identified as an important inflammatory mediator in the fibrotic response of human tissue to inflammation. To determine whether this mediator might be involved in intestinal fibrosis, the effect of transforming growth factor beta 1 on collagen production and proliferation by human intestinal smooth muscle cells was studied in vitro. Cells in the second passage were grown to subconfluence in medium containing 10% Nu-Serum (Collaborative Research Inc., Bedford, MA), after which the concentration of Nu-Serum was decreased. Forty-eight hours later, transforming growth factor beta 1 was added to the culture medium to achieve concentrations of 1-500 pmol/L. After 24 hours exposure to the transforming growth factor beta 1, cellular collagen synthesis was determined by the uptake of [3H]proline into collagenase-sensitive protein. Transforming growth factor beta 1 caused a 100% increase in collagen production and a 40% increase in noncollagen protein production per cell, reflecting an increase in relative collagen synthesis of 58%. This effect was maximal at a concentration of 10 pmol/L. Epidermal growth factor, by comparison, had no significant effect on relative collagen synthesis. Transforming growth factor beta 1 caused a significant increase in the uptake of methylaminoisobutyric acid, a nonmetabolized amino acid analog, into the cells at 10 pmol/L. However, this effect was small (20% increase) compared with the effect on the uptake of proline into collagen (100% increase) at this concentration. When cell proliferation was examined by the uptake of [3H]thymidine, transforming growth factor beta 1 had no effect, whereas epidermal growth factor (1000 pmol/L) caused a 94% increase. Transforming growth factor beta 1 selectively augments collagen production by human intestinal smooth muscle cells in vitro. This effect is potent and is not related to effects on either cell proliferation or amino acid uptake. These data suggest that transforming growth factor beta 1 has an important role as an inflammatory mediator in the pathogenesis of intestinal fibrosis.
肠道平滑肌细胞通过增殖和产生胶原蛋白，在使慢性肠道炎症复杂化的狭窄形成过程中起主要作用。转化生长因子β1已被确定为人体组织对炎症的纤维化反应中的一种重要炎症介质。为了确定这种介质是否可能参与肠道纤维化，在体外研究了转化生长因子β1对人肠道平滑肌细胞胶原蛋白产生和增殖的影响。第二代细胞在含有10% Nu - 血清（协作研究公司，马萨诸塞州贝德福德）的培养基中生长至亚汇合状态，之后降低Nu - 血清的浓度。48小时后，向培养基中加入转化生长因子β1，使其浓度达到1 - 500 pmol/L。在暴露于转化生长因子β1 24小时后，通过[3H]脯氨酸掺入对胶原酶敏感的蛋白质来测定细胞胶原蛋白合成。转化生长因子β1使每个细胞的胶原蛋白产生增加100%，非胶原蛋白产生增加40%，反映出相对胶原蛋白合成增加58%。这种效应在浓度为10 pmol/L时最大。相比之下，表皮生长因子对相对胶原蛋白合成没有显著影响。转化生长因子β1在10 pmol/L时导致一种非代谢性氨基酸类似物甲基氨基异丁酸进入细胞的摄取量显著增加。然而，与该浓度下对脯氨酸掺入胶原蛋白的影响（增加100%）相比，这种效应较小（增加20%）。当通过[3H]胸腺嘧啶核苷的摄取来检测细胞增殖时，转化生长因子β1没有作用，而表皮生长因子（1000 pmol/L）导致增加94%。转化生长因子β1在体外选择性地增强人肠道平滑肌细胞的胶原蛋白产生。这种效应很强，且与对细胞增殖或氨基酸摄取的影响无关。这些数据表明，转化生长因子β1作为一种炎症介质在肠道纤维化的发病机制中起重要作用。
