Andrea R. Mueller

Nephrotoxicity following orthotopic liver transplantation : a comparison between cyclosporine and FK506

Nephrotoxicity represents a serious side effect of immunosuppression following liver transplantation. In order to compare the nephrotoxic action of CsA and FK506 in a clinical setting, we evaluated the incidence of early and late nephrotoxicity in 121 patients, 60 of whom were randomly assigned to CsA- and 61 to FK506-based immunosuppression. Early postoperative renal insufficiency (between PODs 0 and 30; SCr 1.5-3 mg/dl) was observed to a similar extent in patients treated with CsA (38.3%) and FK506 (42.6%). Early postoperative acute renal failure (ARF) (SCr > 3 mg/dl) was observed in 18.0% of patients in the FK506 treatment group and 18.3% of patients receiving CsA therapy. Approximately half the patients with ARF required hemodialysis (CsA: 11.7%; and FK506: 8.2%). All patients with early postoperative ARF requiring hemodialysis survived for more than one year. New onset of late ARF (between PODs 30 and 365) was observed in 6.6% of patients receiving FK506 therapy and in 1.7% in the CsA treatment group as a result of severe infection with multiple organ failure syndrome (MOFS). There was 100% mortality in patients with late ARF requiring hemodialysis. Etiology and prognosis of early and late ARF seem to be completely different. Early ARF was associated with severe coagulopathy and a rise in bilirubin and free hemoglobin, and was accompanied by impaired liver function. Mean onset of hemodialysis in CsA-treated patients was POD 1 and in FK506-treated patients POD 6, which disclosed a different time course of drug-specific nephrotoxicity of CsA and FK506 in early ARF. In contrast, late ARF occurred in both treatment groups only as a part of the MOFS in association with severe infections, an observation consistent with the assumption of overimmunosuppression rather than a primary nephrotoxic effect. Late renal insufficiency appeared in 23.3% of CsA- and in 29.4% of FK506-treated patients, and represented a slowly progressing form of drug-specific nephrotoxicity of CsA and FK506. These preliminary results demonstrate a similar outcome in terms of both early and late nephrotoxicity, but longer follow-up will delineate the overall efficacy and toxicity in humans.

Neurotoxicity after orthotopic liver transplantation : a comparison between cyclosporine and FK506

Neurotoxicity represents a serious complication following orthotopic liver transplantation. Neurotoxicity may be evoked by various perioperative factors or develop due to drug-specific toxicity of immunosuppression. We evaluated the incidence of neurotoxicity in 121 patients, 61 randomly assigned to FK506 and 60 to CsA-based immunosuppression. The incidence of moderate or severe neurotoxicity was markedly higher in patients treated with FK506 in the early postoperative period (21.3% vs. 11.7% in patients receiving CsA), after retransplantation (100% vs. 0% in patients receiving CsA), and late (8 of 10 patients; P < or = 0.05 vs. CsA). Furthermore late neurotoxicity was highly associated with severe infections and MOFS, which had a lethal outcome in more than 50% of the patients. Patients who subsequently died developed neurologic symptoms in 67% of the cases. These patients also experienced moderate or severe neurotoxicity significantly more often in the early postoperative period compared with patients with a successful outcome (50% vs. 17.3%; P < or = 0.01). However, various blood and serum parameters, including ALT, bilirubin, urea, creatinine and glucose, when analyzed alone or in multivariate fashion, also correlated significantly with the incidence and severity of early postoperative neurotoxicity, indicating that neurotoxicity following LTX may be caused by various factors and is not exclusively a drug-specific side effect of immunosuppression.

Comparison of FK506- and cyclosporine-based immunosuppression in primary orthotopic liver transplantation : a single center experience

FK506 has been proven effective for prevention and treatment of liver allograft rejection. Herein, we compare FK506-based immunosuppression with an effective quadruple immunosuppressive regimen, including cyclosporine and antithymocyte globulin. The results of a single center participating in the European multicenter FK506 study are reported, including immunosuppressive efficacy as well as toxicity. One-year patient and graft survival was 96.7% and 90.0% for the CsA group and 90.2% and 88.5% for the FK506 group, which is not statistically different. The incidence and severity of acute rejection episodes during the first postoperative year was similar in both treatment groups with 34.4% and 33.3% for the FK506 and CsA treatment group, respectively. Immunosuppressive potency was better for the FK506 group compared with the CsA group according to the incidence of chronic rejection. Furthermore, 5 patients (8.3%) required conversion to FK506 for immunological reasons, i.e., refractory acute or chronic rejection. The incidence of moderate and severe neurotoxicity during the early postoperative period was higher in the FK506 group (21.3%) compared with the CsA group (11.7%), while the incidence of renal insufficiency and acute renal failure was similar (18.0% and 18.3% for the FK506 and CsA treatment groups, respectively). The incidence of CMV infection was significantly higher under treatment with CsA (25.0%) than with FK506 (6.6%) (P < or = 0.05), while the incidence of pneumonia (13.1% and 13.3%), cholangitis (29.5% and 26.7%), and urinary tract infection (39.3% and 28.3% for the FK506 and CsA treatment groups, respectively) was similar in both treatment groups. However, infection was more serious in some cases treated with FK506, and evolved as the main cause of death in the FK506 treatment group. Therefore, caution should be paid to over immunosuppression and toxicity in FK506-treated patients. Regarding the monitoring of FK506, FK506 plasma level failed to be a reliable indicator, and therefore we recommend measurement of whole blood FK506 levels. Our data indicate that immunosuppressive potency of FK506 is greater than that of CsA, especially concerning the incidence of chronic rejection.

The release of cytokines, adhesion molecules, and extracellular matrix parameters during and after reperfusion in human liver transplantation

Poor initial graft function may increase postoperative morbidity including the risk of early allograft rejection. Various mediators, including immunostimulatory cytokines, may be released during reperfusion in relation to the extent of preservation and reperfusion injury. For this purpose, 81 patients with 85 liver transplants were monitored for cytokines, adhesion molecules, extracellular matrix (ECM) parameters, and neopterin at predefined time-points during and after transplantation. To estimate the origin of cytokine release, blood was obtained central and hepatic venously for the first 48 hr after reperfusion and subsequently from a peripheral vein. One-year patient survival was 88.9%; no relation to initial graft function was observed. Poor initial graft function failed to increase the risk for subsequent infectious complications but was associated with an increased risk of early allograft rejection. The incidence of steroid-resistant rejection was significantly increased in patients with poor initial graft function (35.7% versus 12.7% in patients with good and moderate initial graft function; P < or = 0.05). Various cytokines, adhesion molecules, and ECM parameters including sTNF-RII, sIL-2R, IL-8, IL-10, sVCAM-1, E-selectin, hyaluronic acid, sialic acid, and laminin correlated significantly with the extent of preservation and reperfusion injury. Although none of these parameters was more appropriate in determining the extent of preservation and reperfusion injury than currently established parameters (AST, ALT, and color and amount of bile production), the combined increase in these parameters may not only promote tissue repair but may also perpetuate liver allograft injury and thereby cause significant morbidity. Besides cytokines and adhesion molecules, the ECM may play a pivotal role in determining repair or ongoing tissue injury. Ongoing changes at the microvasculature and basement membrane may result in an increase of local and circulating cytokines and adhesion molecules, which increase the risk of subsequent early allograft rejection. Furthermore, the increase in sTNF-RII, E-selectin, and laminin during reperfusion was predictive of subsequent development of acute allograft rejection. These observations may be of value for further strategies to decrease reperfusion injury and prevent early allograft rejection.

Cytokine pattern during rejection and infection after liver transplantation--improvements in postoperative monitoring?

Despite improvements in immunosuppression, rejection occurs in 50% of liver transplant patients and may cause significant morbidity. The most frequent cause of death after liver transplantation is severe infection. Determination of the cytokine network may lead to earlier detection of patients at risk for severe rejection and infection. For this purpose, 81 patients with 85 liver transplants were monitored for cytokines and neopterin on a daily basis. During the first postoperative month, 28 patients (34.6%) developed acute rejection; 14 patients were successfully treated with methylprednisolone (steroid-sensitive rejection), while 14 patients required additional treatment with FK506 and OKT3 (steroid-resistant rejection). Ten patients developed severe infections, and 11 patients experienced asymptomatic cholangitis. Patients with an uneventful postoperative course (n=37) were the control group. One-year patient survival was 88.9%: 1 patient died because of chronic rejection and Pseudomonas urosepsis; a further 4 patients died of aspergillus pneumonia and bacterial sepsis. Soluble TNF-RII, sIL-2R-, and IL-10 levels were significantly elevated 3 days prior to or at the onset of acute steroid-resistant rejection (P < or = 0.01 versus steroid-sensitive rejection and on uneventful postoperative course). An increase in IL-8, neopterin, and sTNF-RII was indicative of severe infection 3 days prior to onset of infection. In this group of patients, a simultaneous increase in IL-10 indicated a lethal outcome of severe infection. During the second week of acute steroid-resistant rejection and lethal infection, a significant rise in IL-1beta, IFN-gamma, and IL-6 was observed (P < or = 0.01 versus control groups). The different patterns in neopterin- and cytokine-increase could differentiate between severe rejection and severe infection. Furthermore, the increase in these parameters indicated severe rejection--i.e., steroid resistance at the onset of acute rejection--which could prompt us to initiate rescue therapy immediately. The ability to detect patients at risk for severe or lethal infection may result in intensified infectious screening and more aggressive antiinfectious treatment. Therefore, routine monitoring of these parameters may lead to changes in therapeutic management of severe acute rejection and infection after liver transplantation.

Evidence that small bowel preservation causes primarily basement membrane and endothelial rather than epithelial cell injury

The main site of injury induced during small bowel preservation is perceived to be the basement membrane and the endothelium of the highly vascularized mucosa, an aspect evaluated here in further detail. The effects of preservation were studied using a specific basement membrane stain (laminin antibody), an endothelial cell stain (factor 8 antibody) and standard histology. In addition, mucosal glutaminase activity reflecting entero-cyte integrity was measured as monitor of the extent of preservation injury. Using a rat model, small bowel grafts were harvested, the vascular bed and bowel lumen were flushed, and the grafts were stored (4°C) for 1, 6, 9, and 12 hr and transplanted into syngeneic hosts. After cold storage prior to transplantation, full-thickness small bowel biopsies were obtained for the various tissue preparations. Histologic evaluation at the end of the preservation period revealed separation of the vil-lous epithelium from the lamina propria that increased with extending preservation time. Tissue staining with the laminin antibody disclosed progressive changes with increasing preservation intervals. Staining with the factor 8 antibody demonstrated also progressive changes, but failed to reflect in a gradual fashion increasing endothelial cell injury. Histologic injury became more pronounced after transplantation and reperfusion, then showing destruction of epithelial cells; the extent of injury correlated with the duration of preservation. Glutaminase activity was maintained after cold storage, indicating that the enterocytes remained intact during this period, but when assayed after reperfusion, glutaminase decreased with increasing preservation intervals and increasing histologic mucosal damage. We conclude that cold ischemic injury involves primarily the endothelium and the basement membrane, which progresses to global mucosal impairment with reperfusion.

Successful infliximab treatment of steroid and OKT3 refractory acute cellular rejection in two patients after intestinal transplantation

Acute rejection resistant to established immunosuppressive rescue protocols remains the most prominent risk factor after intestinal transplantation. In two patients presenting with steroid-resistant severe acute cellular rejection 9 months and 2 years after intestinal transplantation, complete resolution was not achieved despite 5 and 10 days of OKT3 treatment, respectively, and high-dose triple baseline immunosuppression with tacrolimus, rapamycin, and steroids. There was a dissociated course of rejection with persistent moderate to severe rejection in the terminal portion of the graft despite complete recovery from rejection in the proximal parts. Both patients were treated with four subsequent infusions of infliximab (3 mg/kg body weight), a chimeric anti-tumor necrosis factor-&agr; antibody. There was an immediate response regarding macroscopic appearance, graft histology, and clinical symptoms. Both patients recovered. In conclusion, infliximab has proven to be an effective rescue therapy in a selected group of patients with steroid and OKT3 refractory severe acute rejection after intestinal transplantation.

The extracellular matrix : An early target of preservation/reperfusion injury and acute rejection after small bowel transplantation

BACKGROUND Endothelial cells are known to be an early target of preservation/reperfusion injury and acute rejection, whereas the extracellular matrix (ECM) may also play an equally important role in the sequelae of both events. METHODS Syngeneic and allogeneic rat small bowel transplantations (SBTX) were performed after 6 hr of preservation. Animals were subsequently killed at defined time points for determination of ECM parameters within the graft and in plasma. RESULTS Laminin levels were significantly increased 20 min after reperfusion (syngeneic SBTX: 357+/-65.9 ng/ml; allogeneic SBTX: 361+/-79.6 ng/ml; P< or =0.01). After syngeneic transplantation, laminin levels normalized by postoperative day (POD) 7, whereas there was a rejection-induced increase after allogeneic SBTX (POD 7: 179+/-60.1 ng/ml; POD 9: 333+/-13.6 ng/ml; P< or =0.01 vs. syngeneic SBTX). This increase was accompanied by an increase in tumor necrosis factor-alpha levels at POD 9. Hyaluronic acid levels were significantly elevated after 24 hr (syngeneic SBTX: 1086+/-176 microg/L; allogeneic SBTX: 918+/-108 microg/L; P< or =0.01). After syngeneic SBTX, hyaluronic acid levels normalized by POD 7, whereas persistently higher levels were observed after allogeneic SBTX. Immunohistochemistry confirmed early changes (20 min after reperfusion) at the ECM. Anti-laminin and anti-CD44 staining normalized at POD 5 after syngeneic SBTX. After allogeneic SBTX, rejection-specific changes were evident with anti-laminin staining commencing on POD 5 and progressing until POD 9. At similar time points, increased expression of fibronectin- and interferon-gamma-positive material was evident. CONCLUSIONS The ECM can be considered to be an early target of preservation/reperfusion injury and acute rejection. Plasma parameters reliably reflected the changes observed within the graft. Laminin and hyaluronic acid levels may be used as indicators of initial graft function. Furthermore, the increase in laminin levels was an early indicator of acute rejection. Determination of these parameters may significantly improve monitoring after SBTX.

Hyaluronic acid and purine nucleoside phosphorylase in vascular and luminal effluents of small bowel grafts as parameters of preservation injury.

Reliable parameters reflecting the degree of graft injury after small bowel preservation are currently not established. We investigated hyaluronic acid (HA) and purine nucleoside phosphorylase (PNP) as indicators of preservation injury before small bowel transplantation. In the first part of the study, intestinal grafts were harvested, perfused with saline, and flushed either immediately or after 1, 6, 12, 24, and 48 hr of cold storage (n=6/group). HA and PNP were assayed in vascular and luminal effluents. In the second part of the study, 24 grafts were transplanted after preservation periods of 1, 6, 9, and 12 hr (n=6/group) to assess if HA and PNP are predictors of postoperative graft survival. HA levels in vascular effluents and PNP activities in luminal effluents correlated with duration of preservation time and predicted graft survival. Utilizing both parameters significantly increased the predictive accuracy.

Stickstoffmonoxyd-Produktion nach Dünndarmtransplantation der Ratte

In der Dunndarmkonservierung nimmt Stickstoffmonoxyd (·N=O) offensichtlich eine zweideutige Rolle ein. Die durch das konstitutive Enzym regulierte ·N=O Produktion vermindert unter physiologischen und pathophysiologischen Bedingungen die Epithelund Endothelzellpermeabilitat des Darmes und verringert somit den Plasmaaustritt, die Bakterientranslokation und Endotoxinamie [1,2]. Daruberhinaus bewirkt die konstitutive ·N=O Synthase in der Reperfusionsphase eine lokale Erhohung des ·N=O Gehaltes in der Mukosa und Submukosa, was seinerseits eine Gegenregulation verschiedener, zum Teil unerwunschter Effekte in der fruhen Reperfusionsphase hervorruft [3]. So vermindert ·N=O die durch Superoxid-Anionen erzeugte Vasokonstriktion (O2- -Scavanger) und inhibiert die Neutrophilenadhasion und Thrombozytenaggregation, Effekte, die zusammengefast als ”No-Reflow-Phanomen” bekannt sind. Aus der Sepsisforschung ist bekannt, das die Stimulation des induzierbaren Enzyms zur Hypotension und Inhibierung wichtiger eisenhaltiger Enzyme fuhrt und somit eher negative Auswirkungen auf den Konservierungs- und Reperfusionsschaden haben konnte. Im Dunndarm-Transplantationsmodell der Ratte wurde daher die ·N=O Produktion und deren Auswirkung auf die Transplantatfunktion zu verschiedenen Zeitpunkten der Reperfusionsphase bestimmt.