Use of DNA amplification for diagnosis of cytomegalovirus enteritis after intestinal transplantation

BACKGROUND & AIMS

Intestinal transplantation is a feasible therapy for patients with short-bowel syndrome. However, cytomegalovirus (CMV) enteritis can cause complications. The aim of this study was to investigate the value of polymerase chain reaction (PCR)-based detection methods for CMV in the management of patients with small bowel transplants.

METHODS

Comparative evaluation of PCR with histopathology, shell-vial assay, and tube culture of intestinal biopsy specimens was used for the diagnosis of CMV enteritis in 21 patients.

RESULTS

Ten patients experienced 21 episodes of CMV enteritis, diagnosed by histopathology, virology, or both. PCR had a sensitivity and specificity of 96% and 69%, respectively, compared with traditional methods, whereas the positive and negative predictive values were 35% and 99%, respectively. Three+ and 4+ signals corresponded to a specificity of 91% and positive predictive value of 59%, respectively. CMV was detected by PCR a median of 11 days (range, 0-32) earlier than other methods and lasted a median of 40 days (range, 21-80) in the 13 episodes, which became PCR-negative and in those patients who developed asymptomatic infection. In 8 episodes, CMV by PCR never became negative and was associated with a relapse of disease confirmed by other methods.

CONCLUSIONS

PCR is a sensitive method for the early detection of CMV in intestinal biopsy specimens and can be used for preemptive therapy after intestinal transplantation.

Interleukin-2 and interleukin-12 mediate distinct effector mechanisms of liver allograft rejection

Interleukin-2 (IL-2), interleukin-12 (IL-12) or interleukin-4 (IL-4) were administered postoperatively to otherwise spontaneously accepting mouse liver allograft recipients (C57BL/10-->C3H) to test whether TH1 cytokines are critical mediators of rejection in this model. The induction of rejection at days 5 to 7 by exogenously administered IL-2 and IL-12, but not IL-4, suggests that mouse liver allograft rejection can be induced by TH1 cytokines; however, there appeared to be differences in the mechanism by which these cytokines induce liver rejection. IL-2 administration was accompanied by an increased intragraft infiltration of CD4+ and CD8+ cells and an up-regulation of natural killer (NK), lymphokine-activated killer (LAK), allospecific cytotoxic killer (CTL) activity and perforin mRNA when compared with media-treated controls. In contrast, exogenous IL-12 treatment was associated with a suppression of CTL, NK, and LAK activity compared with controls but an enhanced infiltration of F4/80+ macrophages as determined by immunohistochemistry. Determination of cytokine mRNA profiles by semi-quantitative reverse transcription polymerase chain reaction showed the up-regulation of interferon (IFN)-gamma, IL-4, IL-6, and IL-10 mRNA with IL-2 treatment when compared with media-treated controls. Interestingly, IL-2 mRNA was down-regulated in these animals, suggesting a negative feedback mechanism in IL-2 regulation. IL-12 treatment resulted in the up-regulation of IFN-gamma, IL-6, and IL-10 mRNA, but not IL-2 or IL-4 mRNA. Higher complement-directed cytotoxic antibody titers were seen in IL-12-treated recipients compared with controls, whereas IL-2 treatment showed no apparent differences in antibody titers compared with media treatment. These in vivo observations were mimicked in a mixed leukocyte reaction by supplementing the reaction with IL-2, IL-12, or media. These results suggest that rejection of mouse liver allografts may involve more than one distinct cellular immunological effector mechanism. One is mediated by IL-2 and appears to favor alloreactive CTL, whereas the other pathway is mediated by IL-12/IFN-gamma and involves macrophages and cytotoxic antibodies largely resembling a delayed-type hypersensitivity reaction.

Analysis of chronic rejection and obliterative arteriopathy. Possible contributions of donor antigen-presenting cells and lymphatic disruption

Sequential analysis of changes that lead to chronic rejection was undertaken in an animal model of chronic rejection and obliterative arteriopathy. Brown Norway rats are pretreated with a Lewis bone marrow infusion or a Lewis orthotopic liver allograft and a short course of immunosuppression. They are challenged 100 days later with a Lewis heterotopic heart graft without immunosuppression. The heart grafts in both groups undergo a transient acute rejection, but all rats are operationally tolerant; the heart grafts are accepted and remain beating for more than 100 days. Early arterial remodeling, marked by arterial bromodeoxyuridine incorporation, occurred in both groups between 5 and 30 days during the transient acute rejection. It coincided with the presence of interstitial (but not arterial intimal) inflammation and lymphatic disruption and resulted in mild intimal thickening. Significant arterial narrowing occurred only in the bone-marrow-pretreated rats between 60 and 100 days. It was associated with T lymphocyte and macrophage inflammation of the heart graft that accumulated in the endocardium and arterial intima and adventitia near draining lymphatics. There also was loss of passenger leukocytes from the heart graft, up-regulation of cytokine mRNA and major histocompatibility class II on the endothelium, and focal disruption of lymphatics. In contrast, long-surviving heart grafts from the Lewis orthotopic liver allograft pretreated group are near normal and freedom from chronic rejection in this group was associated with persistence of donor major histocompatibility class-II-positive hematolymphoid cells, including OX62+ donor dendritic cells. This study offers insights into two different aspects of chronic rejection: 1) possible mechanisms underlying the persistent immunological injury and 2) the association between immunological injury and the development of obliterative arteriopathy. Based on the findings, it is not unreasonable to raise the testable hypothesis that direct presentation of alloantigen by donor antigen-presenting cells is required for long-term, chronic-rejection-free allograft acceptance. In addition, chronic intermittent lymphatic disruption is implicated as a possible mechanism for the association between chronic interstitial allograft inflammation and the development of obliterative arteriopathy.

Tacrolimus rescue therapy for renal allograft rejection--five-year experience

Over the 5 year period from 7/14/1989 until 5/24/1994, we have attempted graft salvage with tacrolimus conversion in a total of 169 patients (median age 33 years, range 2-75 years) with ongoing rejection on baseline CsA immunosuppression after failure of high dose corticosteroids and/or antilymphocyte preparations to reverse rejection. The indications for conversion to tacrolimus were ongoing, biopsy confirmed rejection in all patients. The median interval to tacrolimus conversion was 2 months (range 2 days to 55 months; mean 4.3+/-2.6 months) after transplantation. All patients had failed high dose corticosteroid therapy and 144 (85%) of the 169 patients had received at least one course of an antilymphocyte preparation plus high dose corticosteroid therapy prior to conversion. Twenty-eight patients (17%) were dialysis-dependent at the time of conversion owing to the severity of rejection. With a mean follow-up of 30.0+/-2.4 months (median 36.5 months, range 12-62 months), 125 of 169 patients (74%) have been successfully rescued and still have functioning grafts with a mean serum creatinine (SCR) of 2.3+/-1.1 mg/dl. Of the 144 patients previously treated with antilymphocyte preparations, 117 (81%) were salvaged. Of the 28 patients on dialysis at the time of conversion to tacrolimus, 13 (46%) continue to have functioning grafts (mean SCR 2.15+/-0.37 mg/dl) at a mean follow-up of 37.3+/-16.7 months. In the 125 patients salvaged, prednisone doses have been lowered from 28.0+/-9.0 mg/d (median 32, range 4-60 mg/d) preconversion to 8.5+/-4.1 mg/d (median 12 mg/d, range 2.5-20 mg/d) postconversion. Twenty-eight patients (22.4%) are currently receiving no steroids. This 5 year experience demonstrates that tacrolimus has sustained efficacy as a rescue agent for ongoing renal allograft rejection. Based on these data, we recommend that tacrolimus be used as an alternative to the conventional drugs used for antirejection therapy in renal transplantation.

Weaning of immunosuppression in liver transplant recipients

Immunosuppression has been sporadically discontinued by noncompliant liver allograft recipients for whom an additional 4 1/2 years of follow-up is provided. These anecdotal observations prompted a previously reported prospective drug withdrawal program in 59 liver recipients. This prospective series has been increased to 95 patients whose weaning was begun between June 1992 and March 1996, 8.4+/-4.4 (SD) years after liver replacement. A further 4 1/2 years follow-up was obtained of the 5 self-weaned patients. The prospectively weaned recipients (93 livers; 2 liver/kidney) had undergone transplantation under immunosuppression based on azathioprine (AZA, through 1979), cyclosporine (CsA, 1980-1989), or tacrolimus (TAC, 1989-1994). In patients on CsA or TAC based cocktails, the adjunct drugs were weaned first in the early part of the trial. Since 1994, the T cell-directed drugs were weaned first. Three of the 5 original self-weaned recipients remain well after drug-free intervals of 14 to 17 years. A fourth patient died in a vehicular accident after 11 years off immunosuppression, and the fifth patient underwent retransplantation because of hepatitis C infection after 9 drug-free years; their allografts had no histopathologic evidence of rejection. Eighteen (19%) of the 95 patients in the prospective series have been drug free for from 10 months to 4.8 years. In the total group, 18 (19%) have had biopsy proved acute rejection; 7 (7%) had a presumed acute rejection without biopsy; 37 (39%) are still weaning; and 12 (13%, all well) were withdrawn from the protocol at reduced immunosuppression because of noncompliance (n=8), recurrent PBC (n=2), pregnancy (n=1), and renal failure necessitating kidney transplantation (n=1). No patients were formally diagnosed with chronic rejection, but 3 (3%) were placed back on preexisting immunosuppression or switched from cyclosporine (CsA) to tacrolimus (TAC) because of histopathologic evidence of duct injury. Two patients with normal liver function died during the trial, both from complications of prior chronic immunosuppression. No grafts suffered permanent functional impairment and only one patient developed temporary jaundice. Long surviving liver transplant recipients are systematically overimmunosuppressed. Consequently, drug weaning, whether incomplete or complete, is an important management strategy providing it is done slowly under careful physician surveillance. Complete weaning from CsA-based regimens has been difficult. Disease recurrence during drug withdrawal was documented in 2 of 13 patients with PBC and could be a risk with other autoimmune disorders.

Liver transplantation for acute liver failure: outcome analysis

Acute liver failure (ALF) remains a major cause of morbidity and mortality. Before the availability of liver transplantation only 20% of patients with ALF survived. The clinical dilemma relates to the prognostication of these patients, as early liver transplantation has been associated with better outcomes. The eligibility for liver transplantation must therefore be quickly established. The patient's age, aetiology of disease, interval between the onset of jaundice and encephalopathy, blood pH, prothrombin time, serum bilirubin and serum creatinine levels has been identified as useful prognostic markers. The degree of hepatocyte necrosis on liver biopsy and estimated hepatic volume by computed tomography may also be valuable predictors of survival; however, further studies are needed.

Hepatic transplantation during pregnancy and the puerperium

Liver transplantation is the treatment of choice for many patients with acute and chronic hepatic failure. Although uncommon, hepatic failure may occur during pregnancy or after delivery, and liver transplantation may be life-saving. We report a case of a liver transplant performed during pregnancy in a patient with decompensated cirrhosis from chronic autoimmune hepatitis. A patient with chronic autoimmune hepatitis developed decompensated cirrhosis at approximately 18 weeks' gestation. Despite attempts at medical stabilization, her condition worsened, and an orthotopic liver transplant was performed at 23 weeks. The procedure was complicated by transient hypotension, and fetal death was diagnosed postoperatively. Her postoperative course was complicated by hypotension, infection, oliguric renal failure, anemia, thrombocytopenia, and rejection. She spontaneously labored on the 6th postoperative day and delivered without difficulty a 560-g stillborn male. The patient recovered and was discharged 31 days after surgery on prednisone, tacrolimus, mycostatin, erythropoietin, and iron. Liver transplantation may be a valuable therapeutic option for treatment of pregnant or puerperal women with hepatic failure.

Internal hernia and volvulus of the small bowel following liver transplantation

Internal herniation with volvulus of the small intestine is an uncommon, but potentially fatal, complication after liver transplantation. We present here four cases in which the herniation occurred around the Roux-en-Y loop used for the biliary reconstruction. One patient died due to intestinal and liver allograft necrosis; another lost almost the entire small intestine and has since undergone successful intestinal transplantation. Two patients survived following surgery that involved reduction of the hernia and closure of the mesenteric defect. Clinical diagnostic implications emphasize early diagnosis and appropriate operative intervention.