Cytomegalovirus and solid organ transplantation: an update:

Gastroenterological complications in kidney transplant patients

Kidney transplantation is the surgical operation by which one of the two original kidneys is replaced with another healthy one donated by a compatible individual. In most cases, donors are recently deceased. There is the possibility of withdrawing a kidney from a consenting living subject. Usually, living donors are direct family members, but they could be volunteers completely unrelated to the recipient. A much-feared complication in case of kidney transplantation is the appearance of infections. These tend to arise due to immune-suppressor drugs administered as anti-rejection therapy. In this review, we describe the gastrointestinal complications that can occur in subjects undergoing renal transplantation associated with secondary pathogenic microorganisms or due to mechanical injury during surgery or to metabolic or organic toxicity correlated to anti-rejection therapy. Some of these complications may compromise the quality of life or pose a significant risk of mortality; fortunately, many of them can be prevented and treated without the stopping the immunosuppression, thus avoiding the patient being exposed to the risk of rejection episodes.

Gastrointestinal complications in renal transplant recipients detected by endoscopic biopsies in a developing country

BACKGROUND

Renal transplantation is the treatment of choice for patients with end-stage renal disease. The renal transplant recipients are susceptible to a variety of gastrointestinal (GI) complications such as infections, ulcer disease, and malignancies.

OBJECTIVES

We aimed to determine the frequency of pathological lesions in GI endoscopic biopsies in recipients of live related renal transplantation in our setting.

METHODS

This retrospective survey was carried out at Histopathology Department of Sindh Institute of Urology and Transplantation, Karachi, from December 2010 to January 2011. All consecutive renal transplant patients of all ages and both genders on regular follow up, presenting with GI complaints and in whom GI endoscopic biopsies were performed, were included. The demographic, clinical, and laboratory data were retrieved from case files and the pathological diagnoses from the original biopsy reports.

RESULTS

A total of 200 consecutive renal transplant patients were enrolled. The biopsies comprised of 19 (9.5 %) esophageal biopsies, 119 (59.5 %) gastric biopsies, 148 (74 %) duodenal biopsies, and 66 (33 %) colorectal biopsies. The main pathological lesions included cytomegalovirus infection in 22 (11 %) of all patients, Helicobacter pylori in 11 (9.2 %) of gastric biopsies, cryptosporidium in 4 (1.6 %), giardiasis in 30 (15 %), immunoproliferative small intestinal disease in 5 (3.4 %), tropical sprue in 33 (15 %), tuberculosis in 3 (2 %) of the small intestinal biopsies, and gastric adenocarcinoma in 1 (1.7 %) gastric biopsy.

CONCLUSION

A wide spectrum of pathological lesions including opportunistic infections was seen in GI endoscopic biopsies in renal transplant patients. Endoscopic biopsies play an important role in the diagnosis and management of GI disease in renal transplant patients.

CMV infection, diagnosis and antiviral strategies after liver transplantation

Cytomegalovirus (CMV) is a significant pathogen complicating the post-transplant course of organ recipients. In liver transplant patients, the febrile clinical illness caused by CMV may be associated with end-organ disease, such as hepatitis or infection of the gastrointestinal tract. In addition to direct effects, CMV may have indirect effects including the risk of other infections or graft rejection. Recently, major advances in the management of CMV infection have been achieved through the development of new diagnostic techniques and antiviral strategies to prevent CMV disease. Quantitative nucleic acid testing to monitor viral load is now commonly used to diagnose and guide the treatment of CMV infections. The standardization of the testing, however, needs to be improved. There are two main strategies to prevent CMV disease after liver transplantation: prophylaxis and pre-emptive therapy. Both strategies are effective, but also have disadvantages. The disadvantages of prophylaxis include prolonged drug exposure, the development of resistance and, most of all, the development of delayed and late-onset CMV disease. On the other hand, the pre-emptive strategy is based on frequent laboratory monitoring of viral loads, and some patients may develop symptomatic infection before the diagnosis of CMV. This overview summarizes the current status of CMV in liver transplantation.

Cytomegalovirus Infections in Cardiac Transplant Patients: An Experience at a Clinical Hospital, University of Chile

BACKGROUND

Since cytomegalovirus (CMV) infects between 20% and 50% of heart transplant patients, we reviewed our experience in 7 cases of this infection.

METHODS

A prospective analysis of CMV infection was performed in heart transplant patients who received cyclosporine, azathioprine, or mycophenolate mofetil, and prednisone. An elevated creatinine de novo was managed with antibody induction.

RESULTS

Between August 2001 and December 2005, we performed 22 heart transplants and 1 heart plus kidney transplant. Twenty-two patients were positive for CMV before transplantation. One patient died early because of graft failure. Immunosuppression included cyclosporine and prednisone (100%), azathioprine (52%), or mycophenolate (47%). Two recipients were induced with thymoglobulin and 13 with Daclizumab, while 8 did not receive any antibody. Nineteen patients received prophylaxis for CMV. Seven patients (30%) showed CMV infection, 6 of whom had received prophylaxis. Symptoms started at an average of 107 days posttransplantation in patients with prophylaxis. Three patients had gastritis, 2 pneumonia, and 1 colitis. One patient had concomitant lung aspergillosis. The two patients who received ATG developed CMV infections; 3 of the 12 with Daclizumab; and 2 who did not receive antibody. Of the CMV-infected subjects, 5 were on azathioprine and 2 on mycophenolate. All patients were treated with gancyclovir. The 1 patient with concomitant aspergillosis died.

CONCLUSIONS

The incidence of infection by CMV was 30%. Prophylaxis seemed to delay infection. Daclizumab induction did not increase the risk for CMV.

National serosurvey of cytomegalovirus in Australia

In anticipation of the development of a vaccine against cytomegalovirus (CMV), we conducted a large, nationally representative serosurvey to examine the seroprevalence of CMV in Australia. Sera were collected opportunistically from laboratories around Australia. Age- and gender-representative samples were tested for CMV antibody. The population-weighted rate of CMV seropositivity in subjects between 1 and 59 years of age was 57% (95% confidence interval, 55.2 to 58.6%). An association between CMV seroprevalence and increasing age was recognized; however, little overall difference in seroprevalence between the sexes was found. The finding that high levels of CMV exposure occur in the first few years of life suggests that for a universal vaccination program to have maximal impact, the vaccine would need to be delivered to infants and have a long duration of protective efficacy. This is the first national serosurvey looking at cytomegalovirus in the Australian community. This study provides valuable information that can be used to examine the incidence of infection in the community and help focus the administration of a future CMV vaccine to appropriate target populations.

The impact of cytomegalovirus disease and asymptomatic infection on acute renal allograft rejection

BACKGROUND

Cytomegalovirus (CMV) disease is a risk factor for allograft rejection in renal transplant (RTx) recipients. However, the role of asymptomatic CMV infection remains controversial.

OBJECTIVES

To determine the impact of CMV disease and asymptomatic infection on biopsy-proven acute rejection (BPAR) during 12 months post-RTx.

STUDY DESIGN

A total of 106 consecutive RTx recipients at risk for CMV (donor and/or recipient CMV seropositive) were followed prospectively for 12 months post-RTx. CMV activity was monitored using nested PCR from whole blood. Three-month prophylaxis with valacyclovir or ganciclovir was given to 94 patients. BPAR episodes were classified according to the Banff 97 criteria. Multivariate Cox proportional hazards model was used to estimate the effect of CMV disease, asymptomatic infection, and other covariates on BPAR.

RESULTS

Asymptomatic CMV infection occurred in 23% of the patients and 10% developed CMV disease. The incidence of BPAR was 29%. CMV disease was an independent risk factor for BPAR (HR=3.0, P=0.014), while asymptomatic CMV infection was not (P=0.987). In addition to CMV disease, expanded criteria donor and donor age were independent predictors for BPAR. In univariate analysis, valacyclovir (HR=0.26, P=0.008) decreased the risk of BPAR. A similar trend was observed with ganciclovir (HR=0.42, P=0.058). Only valacyclovir remained significant in multivariate analysis (HR=0.18, P=0.044).

CONCLUSIONS

CMV disease, but not asymptomatic infection, is an independent risk factor for BPAR during the first 12 months post-RTx.

Signs and symptoms of cytomegalovirus disease in kidney transplant recipients

PURPOSE

To investigate the range of clinical presentations of cytomegalovirus (CMV) disease in kidney transplant recipients.

MATERIALS AND METHODS

We retrospectively reviewed the records of hundred kidney recipients who developed CMV disease between 1984 and December 2002 for demographic characteristics, laboratory findings, and presenting signs and symptoms.

RESULTS

The most common presentations were elevated serum creatinine in 74 patients, fever in 71, thrombocytopenia in 43, nausea in 32, vomiting in 25, elevated alkaline phosphatase in 24, leukocytosis in 22, and leukopenia in 21. Tissue involvement was relatively rare, but six patients had pneumonia, two had conjunctivitis, and one had vascular dermatitis. Four percent of the patients had received intravenous ganciclovir prophylaxis, and 7% had received oral ganciclovir prophylaxis. Fever was associated with number of hospitalizations (P = .006), elevated creatinine (P = .006), nausea (P = .017), vomiting (P = .031), and previous posttransplantation infections (P < .001). All the patients with conjunctivitis, pneumonia, pulmonary symptoms, and abnormal heart sounds and most of those with arthralgia, nausea, and vomiting were febrile during their CMV disease course.

CONCLUSION

Our findings showed that leukocytosis should be considered as much as leukopenia when CMV disease is suspected. CMV-induced pneumonia is not common in renal transplant recipients compared to other organ transplant recipients. CMV invasion to other tissues is also rare. Finally, fever is a common symptom and important in assessing the severity and prognosis of the disease.

Preferential depletion of blood myeloid dendritic cells during acute cardiac allograft rejection under controlled immunosuppression

Allo-Ag presentation to Ag-specific T-lymphocytes by donor or recipient dendritic cells (DCs) induces acute rejection (AR) after solid organ transplantation. It is postulated that myeloid (mDC) and plasmacytoid (pDC) subsets circulate differentially between bone marrow, heart and lymphoid tissues after cardiac transplantation (HTx). We investigated peripheral blood DC subset distribution, maturation and lymphoid homing properties in relation to endomyocardial biopsy (EMB) rejection grade after clinical HTx. Twenty-one HTx recipients under standard immunosuppression were studied in a 9-month follow-up. mDC and pDC numbers were analyzed by flow cytometry in fresh venous whole blood samples collected during the EMB procedures and before histological diagnosis of AR. Subsets were further characterized for maturation marker CD83 and lymphoid homing chemokine receptor CCR7. Although numbers of both DC subsets remained low for the whole post-HTx period, we observed a negative association of mDCs with rejection grade. Repeated measurements analysis revealed that only mDCs decreased during AR episodes. Rejectors had lower mDC numbers after a 3-month follow-up compared to nonrejectors. Furthermore, patients during AR exhibited low proportions of mDCs positive for CD83 or CCR7. These findings suggest peripheral blood mDC depletion in association with selective lymphoid homing of this subset during AR after clinical HTx.

Valacyclovir for Cytomegalovirus Prophylaxis Reduces the Risk of Acute Renal Allograft Rejection

BACKGROUND

Both oral ganciclovir and valacyclovir decrease the incidence of cytomegalovirus (CMV) disease after renal transplantation. Moreover, valacyclovir has been shown to reduce the risk of acute rejection. Our study was designed to compare the efficacy and safety of oral ganciclovir and valacyclovir in the prophylaxis of CMV disease after renal transplantation.

METHODS

A total of 83 patients were prospectively randomized to 3-month treatment with oral ganciclovir (3 g/day, n=36, GAN) or oral valacyclovir (8 g/day, n=35, VAL). A control group (DEF, n=12) was managed by deferred therapy.

RESULTS

No differences were found in demography, immunosuppression, or donor/recipient CMV serology. The 12-month incidence of CMV disease was 67% in the DEF group compared with 6% in the GAN group and 3% in the VAL group (P<0.001 GAN or VAL vs. DEF; P=0.575 GAN vs. VAL). The biopsy-confirmed acute rejection rate at 12 months was 12% in the VAL group compared with 34% in the GAN group (P=0.030) and 58% in the DEF group (P<0.001). The difference between the GAN and DEF groups was not significant (P=0.087). The average CMV-associated costs per patient were $3,072, $2,906, and $4,906 in the GAN, VAL, and DEF groups, respectively.

CONCLUSIONS

Valacyclovir and oral ganciclovir are equally effective in the prevention of CMV disease after renal transplantation. Both regimens are cost-effective. Valacyclovir is associated with a significantly reduced risk of acute rejection compared with both ganciclovir prophylaxis and deferred therapy.