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Inhibition of nitric oxide synthesis reduces bacterial translocation during graft-versus-host disease after small bowel transplantation
Inhibition of Nitric Oxide Synthesis Reduces Bacterial Translocation During Graft-Versus-Host Disease After Small Bowel Transplantation J.M. Langrehr, C. Machens, E. Zill, K. Leder, and P.J. Neuhaus
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ECENT REPORTS indicate that increased nitric oxide (NO) production may contribute to intestinal barrier dysfunction and increases bacterial translocation.1,2 Since bacterial translocation has been implicated to play a major role in graft-versus-host disease (GVHD) after small bowel transplantation (SBTx),3 we used the competitive inhibitor of NO production, aminoguanidine,4 to evaluate the role of NO production in GVHD after SBTx. MATERIALS AND METHODS Using the standard model of semiallogenic SBTx in the rat, we prepared three experimental groups.5 Recipients in group 1 received syngeneic (LBNF1-LBNF1) small bowel transplants and were treated with aminoguanidine (200 mg/kg per day divided in three doses). Recipients in group 2 received semiallogenenic (Lewis-LBNF1) SBTx and were injected with saline in a similar fashion. Recipients in group 3 also received semiallogeneic SBTx and aminoguanidine (200 mg/kg per day divided in three doses). Six animals per group were followed until death and three animals per day and group were killed on postoperative day (POD) 3, 6, and 9. Urine nitrite/nitrate levels were measured daily and bacterial translocation was determined by culturing peritoneal swabs, donor and recipient mesenteric lymph nodes, spleen, liver, and blood using standard methods. Statistical analysis was performed using the Mann-Whitney-U test, accepting statistical significance at P , .05.
RESULTS
Animals in group 1 showed indefinite survival with normal histology and only rare detection of bacterial translocation. In group 2, the animals reached a mean survival of 10.5 6 1.1 days and showed the typical histological features of acute GVHD. The animals in group 3 showed a mean survival of 14.8 6 0.6 days (P , .02) and also histological features of acute GVHD; however, the animals in group 3 had a prolonged time course. Comparing NO production and bacterial translocation between groups 2 and 3 we
0041-1345/99/$–see front matter PII S0041-1345(98)01560-7
detected significantly reduced NO production on POD 2–9 (P , .03) and significantly decreased BT on POD 3 and 9 in the mesenteric lymph nodes (P , .03) and into the spleen (POD 9; P , .03). DISCUSSION
Inhibition of inducible NO synthesis with aminoguanidine significantly reduced NO production, decreased bacterial translocation, and prolonged survival during GVHD after semiallogenic SBTx in the rat. As shown previously by Price et al., acute GVHD leads to an overgrowth of potentially pathogenic bacteria in the transplanted bowel and may therefore be an important pathogenetic factor in the development of a fatal sepsis of the recipient.3 The inhibition of NO by aminoguanidine did not impair the regulation of vascular tonus mediated by the constitutive NO synthase and, therefore, may be useful addition to standard treatment protocols for GVHD after SBTx. REFERENCES 1. Sorrells DL, Friend C, Koltuksuz U, et al: Arch Surg 131: 1155, 1996 2. Unno N, Wang H, Menconi MJ, et al: Gastroenterology 113:1246, 1997 3. Price BA, Cumberland NS, Ingham-Clark CL, et al: Transplantation 56:1072, 1993 4. Hoffman RA, Nu ¨ssler NC, Gleixner SL, et al: Transplantation 63:94, 1997 5. Langrehr JM, Hoffman RA, Banner B, et al: Transplantation 52:399, 1991 From the Departments of Surgery, Microbiology, and Pathology, Charite´ Campus Virchow-Klinikum, Humboldt University Berlin, Berlin, Germany. Address reprint requests to Dr Langrehr, Department of Surgery, Charite´ Campus Virchow-Klinikum, Humboldt University Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
574
Transplantation Proceedings, 31, 574 (1999)
R
ECENT REPORTS indicate that increased nitric oxide (NO) production may contribute to intestinal barrier dysfunction and increases bacterial translocation.1,2 Since bacterial translocation has been implicated to play a major role in graft-versus-host disease (GVHD) after small bowel transplantation (SBTx),3 we used the competitive inhibitor of NO production, aminoguanidine,4 to evaluate the role of NO production in GVHD after SBTx. MATERIALS AND METHODS Using the standard model of semiallogenic SBTx in the rat, we prepared three experimental groups.5 Recipients in group 1 received syngeneic (LBNF1-LBNF1) small bowel transplants and were treated with aminoguanidine (200 mg/kg per day divided in three doses). Recipients in group 2 received semiallogenenic (Lewis-LBNF1) SBTx and were injected with saline in a similar fashion. Recipients in group 3 also received semiallogeneic SBTx and aminoguanidine (200 mg/kg per day divided in three doses). Six animals per group were followed until death and three animals per day and group were killed on postoperative day (POD) 3, 6, and 9. Urine nitrite/nitrate levels were measured daily and bacterial translocation was determined by culturing peritoneal swabs, donor and recipient mesenteric lymph nodes, spleen, liver, and blood using standard methods. Statistical analysis was performed using the Mann-Whitney-U test, accepting statistical significance at P , .05.
RESULTS
Animals in group 1 showed indefinite survival with normal histology and only rare detection of bacterial translocation. In group 2, the animals reached a mean survival of 10.5 6 1.1 days and showed the typical histological features of acute GVHD. The animals in group 3 showed a mean survival of 14.8 6 0.6 days (P , .02) and also histological features of acute GVHD; however, the animals in group 3 had a prolonged time course. Comparing NO production and bacterial translocation between groups 2 and 3 we
0041-1345/99/$–see front matter PII S0041-1345(98)01560-7
detected significantly reduced NO production on POD 2–9 (P , .03) and significantly decreased BT on POD 3 and 9 in the mesenteric lymph nodes (P , .03) and into the spleen (POD 9; P , .03). DISCUSSION
Inhibition of inducible NO synthesis with aminoguanidine significantly reduced NO production, decreased bacterial translocation, and prolonged survival during GVHD after semiallogenic SBTx in the rat. As shown previously by Price et al., acute GVHD leads to an overgrowth of potentially pathogenic bacteria in the transplanted bowel and may therefore be an important pathogenetic factor in the development of a fatal sepsis of the recipient.3 The inhibition of NO by aminoguanidine did not impair the regulation of vascular tonus mediated by the constitutive NO synthase and, therefore, may be useful addition to standard treatment protocols for GVHD after SBTx. REFERENCES 1. Sorrells DL, Friend C, Koltuksuz U, et al: Arch Surg 131: 1155, 1996 2. Unno N, Wang H, Menconi MJ, et al: Gastroenterology 113:1246, 1997 3. Price BA, Cumberland NS, Ingham-Clark CL, et al: Transplantation 56:1072, 1993 4. Hoffman RA, Nu ¨ssler NC, Gleixner SL, et al: Transplantation 63:94, 1997 5. Langrehr JM, Hoffman RA, Banner B, et al: Transplantation 52:399, 1991 From the Departments of Surgery, Microbiology, and Pathology, Charite´ Campus Virchow-Klinikum, Humboldt University Berlin, Berlin, Germany. Address reprint requests to Dr Langrehr, Department of Surgery, Charite´ Campus Virchow-Klinikum, Humboldt University Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
574
Transplantation Proceedings, 31, 574 (1999)