Ganciclovir Transiently Attenuates Murine Cytomegalovirus-Associated Renal Allograft Inflammation

Abstract

Background. Prophylactic ganciclovir (GCV) is used in high-risk renal transplant patients to prevent acute cytomegalovirus (CMV) disease, but its impact on inflammation within the allograft itself remains undefined. Methods. To study the effect of GCV prophylaxis on allograft inflammation, murine CMV (MCMV)-infected allo-grafts were analyzed in a murine donor positive/recipient negative allogeneic renal transplantation model by flow cytometry and immunofluorescent staining. Results. By flow cytometry, CD45+ leukocyte infiltrates were more abundant in MCMV-infected allografts at 14 days posttransplant compared with uninfected grafts (P<0.01) and decreased in the presence of GCV (P<0.05). CD11c+ dendritic cells, Gr-1+ myeloid cells, CD204+ macrophages, and CD49b+ natural killer cells were reduced in GCV-treated allografts compared with MCMV-infected grafts without GCV treatment (P<0.05). However, GCV failed to reduce these cell types to levels found in MCMV-uninfected allografts. By day 7 after cessation of GCV prophylaxis, dendritic cells, macrophages, and natural killer cells increased in number and became statistically indistinguishable from numbers of cells found in MCMV-infected allografts without GCV. GCV treatment did not affect the numbers of CD4+, CD8+, or CD19+/B220+ lymphocytes infiltrating the allografts. Infiltrates were confirmed histologically by immunofluorescent staining for CD3+ and CD11b+ cells. Conclusions. In this model, MCMV-infected allografts developed significantly greater innate and adaptive leukocytic infiltrates compared with uninfected grafts. GCV attenuated the MCMV-associated innate leukocyte infiltrates in infected allo-grafts but not the lymphocytic infiltrates. The attenuated innate response was limited to the period of GCV prophylaxis.

Ganciclovir Prophylaxis Improves Late Murine Cytomegalovirus-Induced Renal Allograft Damage

“…Analysis of grafts after GCV prophylaxis showed histologic findings resembling the uninfected grafts, with patchy leukocyte infiltrates and areas of relatively preserved tubules and glomeruli, and presence of CD4+ and CD8+ lymphocytes but continued modulation of NK and myeloid infiltrates after GCV prophylaxis. These results are consistent with findings previously described at day 14 post-transplant using this same model, in that GCV prophylaxis did not reduce early CD4+ and CD8+ infiltration into MCMV infected allografts (10), but was associated with reduced NK and Gr-1+ myeloid infiltrates during prophylaxis and a moderate increase in these cell types at 1 week after cessation of GCV prophylaxis (10). It is now shown in the current study that the infiltration of NK and myeloid cells into the infected allograft was still moderated in the grafts receiving GCV prophylaxis, even at late times after cessation of antiviral administration.…”

“…In contrast, the frequencies of CD4+ and CD8+ T lymphocytes (Figure 2C) in the CD45+ leukocyte population did not show statistically significant differences between uninfected, MCMV infected, and GCV treated grafts at day 42 post-transplant. These results resemble those found in allografts at 14 days during GCV prophylaxis (10), with an induction of NK and myeloid infiltrates in MCMV infected grafts compared to uninfected grafts, and attenuation of these infiltrates (but not T cells) by GCV treatment. These results indicate that the reduction in NK and myeloid cells in the GCV treated grafts is durable beyond the period of antiviral prophylaxis.…”

“…Ganciclovir (GCV) antiviral prophylaxis has been correlated with improved survival in clinical studies (5). In animal models, murine CMV (MCMV) and rat CMV (RCMV) accelerate both acute and late kidney transplant rejection (6–10). …”

“…Early lymphocytic infiltration is described in both uninfected and CMV infected grafts, consistent with an allogeneic response, but is more abundant in the CMV infected animals, suggesting a potential role for antiviral lymphocyte activation. Mononuclear infiltrates are recruited preferentially to CMV infected grafts compared to uninfected grafts at both early and late times post-transplant, as well as NK cells, Gr-1+ myeloid cells, and antigen-presenting CD11c+ cells at early times post-transplant (6, 7, 9, 10). CMV infection is also associated with augmented induction of adhesion molecules, lymphoid activation markers, pro-inflammatory chemokine profiles, and fibrogenic molecules within infected allografts.…”

“…In cardiac and renal transplant models of CMV infection, treatment with GCV improves histopathologic manifestations of rejection (10, 11). In the cardiac allograft model, 30 days of GCV prophylaxis improves cardiac allograft vasculopathy at 90 days post-transplant.…”