Medley M M, Hooker R L, Rabinowitz S, Holton R, Jaffe B M
Department of Surgery, Tulane University School of Medicine, New Orleans, Louisiana 70012.
Am J Surg. 1995 Jan;169(1):20-7. doi: 10.1016/s0002-9610(99)80105-6.
Crigler-Najjar syndrome, type I, is a disease characterized by complete absence of hepatic bilirubin glucuronidation. The congenital indirect hyperbilirubinemia is due to an autosomal recessive deficiency of the enzyme, uridine diphosphate glucuronosyl transferase (UDPGT). The inbred homozygous Gunn rat is also deficient in UDPGT, exhibits unconjugated hyperbilirubinemia, and is an excellent animal model of the Crigler-Najjar syndrome. This study was performed to test the ability of transplanted intestine from normal Wistar rat donors to correct the deficiency in hepatic bilirubin conjugation.
In phase 1, Gunn rats underwent 40-cm heterotopic small-bowel transplants from either Wistar (experimental) or Gunn (control) rats. In phase 2, 15- to 20-cm Wistar-to-Gunn jejunal transplants were placed either heterotopically or orthotopically (in intestinal continuity). All rats were treated with cyclosporin A (CsA), 5 mg/kg per day. Serum bilirubin levels were determined spectrophotometrically at weekly intervals posttransplantation. In phase 2, UDPGT activity was quantitated at 0, 2, 4, and 8 weeks using known quantities of bilirubin as substrate.
Total bilirubin levels decreased significantly in the 40-cm heterotopic transplant recipient rats. From the initial values of 7.12 +/- 0.59 mg/dL, levels reached the nadir of 4.23 +/- 0.27 mg/dL. A parallel drop in serum levels of indirect bilirubin was noted (5.04 +/- 0.54 mg/dL to 2.74 +/- 0.23 mg/dL). After 6 weeks, bilirubin levels began to rise toward pretransplant values. In contrast, there was no significant change in bilirubin levels in the control Gunn-to-Gunn rats. Fifteen- to 20-cm heterotopic Wistar-to-Gunn transplants caused a qualitatively similar drop in total and indirect bilirubin levels. Orthotopic (in continuity) Wistar-to-Gunn transplants lowered serum bilirubin levels more rapidly, and the effect was sustained throughout the 8-week study period. By 1 week posttransplantation, total bilirubin levels dropped from 5.11 +/- 0.48 mg/dL to 2.41 +/- 0.16 mg/dL (P < 0.05); data at 8 weeks averaged 1.84 +/- 0.35 mg/dL. Respective data for indirect bilirubin levels were 4.81 +/- 0.45 mg/dL, 2.26 +/- 0.18 mg/dL, and 1.35 +/- 0.39 mg/dL. Wistar rat UDPGT activity in intestine and liver averaged 0.61 +/- 0.05 and 1.88 +/- 0.06 mg bilirubin conjugated/mg tissue per hour, respectively. Enzyme activity in the transplanted intestine persisted throughout the course of the study.
Transplants of small intestine with known UDPGT activity partially corrected the deficiency in Gunn rats and allayed the hyperbilirubinemia. Since the small intestine is known to contain small but significant amounts of a large number of predominantly hepatic enzymes, bowel transplantation may be an appropriate treatment for this and other similar genetic enzyme deficiencies.
Ⅰ型克里格勒 - 纳贾尔综合征是一种以肝脏胆红素葡萄糖醛酸化完全缺失为特征的疾病。先天性间接高胆红素血症是由于尿苷二磷酸葡萄糖醛酸基转移酶（UDPGT）的常染色体隐性缺乏所致。近亲繁殖的纯合子冈恩大鼠也缺乏UDPGT，表现为非结合性高胆红素血症，是克里格勒 - 纳贾尔综合征的优良动物模型。本研究旨在测试正常Wistar大鼠供体的移植肠纠正肝脏胆红素结合缺陷的能力。
在第1阶段，冈恩大鼠接受了来自Wistar大鼠（实验组）或冈恩大鼠（对照组）的40厘米异位小肠移植。在第2阶段，将15至20厘米的Wistar大鼠到冈恩大鼠的空肠移植到异位或原位（保持肠道连续性）。所有大鼠每天接受5毫克/千克环孢素A（CsA）治疗。移植后每周用分光光度法测定血清胆红素水平。在第2阶段，以已知量的胆红素为底物，在0、2、4和8周时对UDPGT活性进行定量。
40厘米异位移植受体大鼠的总胆红素水平显著下降。从初始值7.12±0.59毫克/分升降至最低点4.23±0.27毫克/分升。间接胆红素的血清水平也出现平行下降（从5.04±0.54毫克/分升降至2.74±0.23毫克/分升）。6周后，胆红素水平开始回升至移植前水平。相比之下，对照组冈恩大鼠到冈恩大鼠的移植中胆红素水平无显著变化。15至20厘米的异位Wistar大鼠到冈恩大鼠的移植导致总胆红素和间接胆红素水平出现类似性质的下降。原位（保持连续性）Wistar大鼠到冈恩大鼠的移植使血清胆红素水平下降更快，且在整个8周研究期内效果持续。移植后1周，总胆红素水平从5.11±0.48毫克/分升降至2.41±0.16毫克/分升（P<0.05）；8周时的数据平均为1.84±0.35毫克/分升。间接胆红素水平的相应数据分别为4.81±0.45毫克/分升、2.26±0.18毫克/分升和1.35±0.39毫克/分升。Wistar大鼠小肠和肝脏中的UDPGT活性分别平均为0.61±0.05和1.88±0.06毫克胆红素结合/毫克组织/小时。移植肠中的酶活性在整个研究过程中持续存在。
具有已知UDPGT活性的小肠移植部分纠正了冈恩大鼠的缺陷并减轻了高胆红素血症。由于已知小肠含有少量但大量主要为肝脏的酶，肠道移植可能是治疗此类及其他类似遗传性酶缺乏症的合适方法。
