Effects of Acute Cytomegalovirus Infection on Rat Islet Allograft Survival

Abstract

Transplantation of pancreatic islets is a promising therapy for the treatment of type 1 diabetes mellitus. However, long-term islet graft survival rates are still unsatisfactory low. In this study we investigated the role of cytomegalovirus (CMV) in islet allograft failure. STZ-diabetic rats received an allogenic islet graft in combination with either an acute CMV infection or control infection. A third group received ganciclovir treatment in addition to the CMV infection. Graft function was assessed by measuring basal blood glucose levels. After sacrifice, the islet grafts were retrieved for analysis of infection and leukocyte infiltration. CMV-infected recipients demonstrated accelerated islet graft failure compared to noninfected controls. CMV infection of the graft was only observed prior to complete graft failure. Quantification of the leukocyte infiltration demonstrated increased CD8 + T-cell and NK cell infiltration in the CMV-infected grafts compared to the controls. This suggests that CMV infection accelerates immune-mediated graft destruction. Antiviral ganciclovir treatment did not prevent accelerated graft failure, despite effectively decreasing the grade of infection. Our data confirm the recently published CITR data, which state that CMV is an independent risk factor for failure of islet grafts. Also, our data demonstrate that new approaches for preventing virus-induced islet allograft failure may be required.Key words: Islet transplantation; Cytomegalovirus (CMV) infection; Graft failure; CD8 + ; T cells; NK cells INTRODUCTIONof these factors may lie at the basis of declining graft function (21,46). It is surprising that the role of cytomegalovirus (CMV) After more than three decades of research into the principle applicability of clinical islet transplantation has gained only minor attention as a contributing factor to islet graft failure. This is despite the strong correlation (3,37), a major breakthrough was achieved in 2000 by Shapiro et al. (47), who demonstrated that insulin indebetween this viral infection and solid organ graft rejection (1,13,17,24,32,48). CMV is a widely spread, persispendence could be achieved by applying a glucocorticoid-free immunosuppressive regimen after grafting the tent infection, which develops asymptomatic in healthy, immunocompetent individuals (16). In immunocompromislets into the liver of diabetic patients. This success has led to a tremendous growth in the number of clinical ized individuals, the virus may reactivate and cause mild to severe CMV disease. A secondary feature of the virus islet transplantations performed worldwide. In spite of this optimism, a number of critical issues remain to be is that its reactivation is strongly associated with allograft rejection. In solid organ transplantation, this risk solved. Islets from more than one donor are required to supply patients with sufficient graft volume (46). Anon CMV-induced graft failure highly depends on the serostatus of both donor and recipient. The highest risk other important issue is that graft ...

Impaired glucose tolerance in rat islet isograft recipients after cytomegalovirus infection

“…In a previous study, we showed that only a few cells in the graft are infected but responsible for enhancement of the immunogenicity of the graft as a whole . So we show that not only enhancement of allogenic CD8+ and NK cell responses is involved in islet grafts failure but also more direct effects on the grafts, as allograft responses were excluded in the present experimental set up. Possibly, RCMV‐specific T and NK cells are involved.…”

“…RCMV‐specific R44 protein was demonstrated in the grafts by immunohistochemistry, as described . We inspected the grafts for RCMV R44 protein, but, as also shown in our previous study, infected cells were rare or absent . Only a small portion of the cells are infected, but are responsible for dysfunction, as we showed for human and rat islets .…”

“…We found evidence that the accelerated allograft failure could be explained by CMV‐induced enhancement of allogeneic CD8+ and NK cells responses . A question that could not be addressed in our previous studies was whether RCMV also has direct effects on the grafts in vivo . Therefore, we undertook this study, in which we determined the direct effect of RCMV on the functional survival of islets by performing infections in isografts, thus, in the absence of confounding allogeneic immune responses.…”

Belatacept and Sirolimus Prolong Nonhuman Primate Islet Allograft Survival: Adverse Consequences of Concomitant Alefacept Therapy

“…Infecting rats with CMV has been shown to accelerate islet graft failure compared to control animals, and this effect was not abrogated by infection control with ganciclovir(20). This suggests that CMV viremia, even if controlled by treatment with antiviral therapy, may be an independent risk factor for early islet allograft failure.…”

Stimulation of vascularization of a subcutaneous scaffold applicable for pancreatic islet‐transplantation enhances immediate post‐transplant islet graft function but not long‐term normoglycemia

“…Briefly, sections were oxidized by 2.5% KMnO 4 (Sigma‐Aldrich) and 5% H 2 SO 4 (Merck) in demineralized water for 90 s and cleaned with 2% oxalic acid (Sigma‐Aldrich) for 2 min. After an incubation of 2 min with 70% ethanol, sections were incubated with aldehyde fuchsin solution32, 33 for 10 min. An incubation of 6 min with Halmi [0.2% Lightgreen SF (Sigma‐Aldrich) + 1% Orange G (Sigma‐Aldrich) + 0.5% Chromotrope 2 R (Sigma‐Aldrich) + 0.5% H 2 WO 4 (Sigma‐Aldrich) + 1% CH 3 COOH 100% (Merck Millipore) in demi water] was used as counterstain.…”