Persistent cytomegalovirus infection in kidney allografts is associated with inferior graft function and survival

Urinary Tract Infections: Virus

Although viruses are common in the urinary tract in healthy people, viral infections can become a major concern in immunocompromised individuals. Patients undergoing hematopoietic stem cell or solid organ transplantation may be particularly susceptible to BK and other viruses, and experience a high risk of mortality. The most common presentation in this setting is hemorrhagic cystitis. The treatment is mostly supportive, including the reduction of immunosuppression; a variety of experimental agents has also been proposed. A different context is offered by chronic (HBV, HCV, HIV) or acute/subacute (Dengue, Hantavirus, etc.) infections, where the kidneys can be secondarily involved and suffer from several glomerular syndromes. Many protocols based on different oral direct-acting antivirals and combined antiretrovirals are available, according to the systemic infection. Viral infections can be classified according to the organ involved, i.e. lower (bladder) or upper urinary tract (kidneys, ureters), and to the mechanism of injury. A section is dedicated to the current breakout of SARS-CoV-2, which does not spare the urinary tract, sometimes with serious implications. Even if this topic is mostly the discipline of ultra-dedicated physicians, this overview has a practical approach and could be useful to a wider medical audience, especially in times of viral pandemics.

Rat and human cytomegalovirus ORF116 encodes a virion envelope glycoprotein required for infectivity

Herpesviruses encode multiple glycoproteins required for different stages of viral attachment, fusion, and envelopment. The protein encoded by the human cytomegalovirus (HCMV) open reading frame UL116 forms a stable complex with glycoprotein H that is incorporated into virions. However, the function of this complex remains unknown. Herein, we characterize R116, the rat CMV (RCMV) putative homolog of UL116. Two R116 transcripts were identified in fibroblasts with three proteins expressed with molecular weights of 42, 58, and 82 kDa. R116 is N-glycosylated, expressed with late viral gene kinetics, and is incorporated into the virion envelope. RCMV lacking R116 failed to result in productive infection of fibroblasts and siRNA knockdown of R116 substantially reduced RCMV infectivity. Complementation in trans of an R116-deficient virus restored ability of the virus to infect fibroblasts. Finally, UL116 knockdown also decreased HCMV infectivity indicating that R116 and UL116 both contribute to viral infectivity.

Evaluation of cytomegalovirus prophylaxis in low and intermediate risk kidney transplant recipients receiving lymphocyte-depleting induction

Cytomegalovirus (CMV) is a significant cause of morbidity in kidney transplant recipients (KTR). Historically at our institution, KTR with low and intermediate CMV risk received 6 months of valganciclovir if they received lymphocyte depleting induction therapy. This study evaluates choice and duration of CMV prophylaxis based on donor (D) and recipient (R) CMV serostatus and the incidence of post-transplant CMV viremia in low (D-/R-) and intermediate (R+) risk KTR receiving lymphocyte-depleting induction therapy. A protocol utilizing valacyclovir for 3 months for D-/R- and valganciclovir for 3 months for R+ was evaluated. Adult D-/R- and R+ KTR receiving anti-thymocyte globulin, rabbit or alemtuzumab induction from 8/20/2016 to 9/30/2018 were evaluated through 1 year post-transplant. Patients were excluded if their CMV serostatus was D+/R-, received a multi-organ transplant, or received basiliximab. Seventy-seven subjects met the inclusion criteria: 25 D-/R- (4 historic group, 21 experimental group) and 52 R+ (31 historic, 21 experimental). No D-/R- patients experienced CMV viremia. Among the R+ historic and experimental groups, there was no significant difference in viremia incidence (35.5% vs 52.4%; P = .573). Of these cases, the peak viral load was similar between the groups (median [IQR], 67 [<200-444] vs <50 [<50-217]; P = .711), and there was no difference in the incidence of CMV syndrome (16.1% vs 14.3%; P = 1.000) or CMV related hospitalization (12.9% vs 14.3%; P = 1.000). No patient experienced tissue invasive disease. These results suggest limiting valganciclovir exposure may be possible in low and intermediate risk KTR receiving lymphocyte-depleting induction therapy with no apparent impact on CMV-related outcomes.

The burden of cytomegalovirus infection remains high in high-risk kidney transplant recipients despite six-month valganciclovir prophylaxis

Cytomegalovirus continues to be a concern after transplantation despite prophylaxis regimens. Our aim was to analyse post-prophylaxis primary cytomegalovirus infections among kidney transplant recipients after 6-month valganciclovir prophylaxis and to determine the usefulness of surveillance after prophylaxis. Data from all cytomegalovirus D+/R- kidney transplant recipients from January 2004 to October 2018 at our center who received 6-month prophylaxis with valganciclovir were retrospectively analysed (N = 481). Detailed analyses were performed for 136 patients who were monitored every 2-4 weeks for DNAemia after the discontinuation of prophylaxis. Post-prophylaxis primary cytomegalovirus infection occurred in 182/481 (38%) patients median 264 days after transplantation (IQR: 226-367) and median 84 days after the end of prophylaxis (IQR: 46-187). In 49% patients, cytomegalovirus infection occurred over 3 months after the end of prophylaxis. Cytomegalovirus infection was not associated with lower patient or graft survival and no independent risk factors for infection were found. From patients monitored closely, 71/136 (52%) patients developed post-prophylaxis primary cytomegalovirus infection. Altogether, 52/136 (38%) patients were diagnosed with probable post-prophylaxis cytomegalovirus disease and 19/136 (14%) patients had asymptomatic CMV infection. Recurrent infection occurred in 38/71 (39%) patients. The incidence of post-prophylaxis primary cytomegalovirus infection among D+/R- kidney transplant recipients remains high despite 6-month prophylaxis. Surveillance after prophylaxis was challenging as a considerable portion of the infections occurred late and already symptomatic.

Cytomegalovirus renal infection: Rare manifestation of a common post-transplant viral infection-A case series

Cytomegalovirus is the most common viral infection in organ transplant recipients that usually affects the brain, lungs, liver, and gastrointestinal tract. Renal involvement of Cytomegalovirus (CMV) is otherwise rare. We present six cases of biopsy-proven CMV renal infection. Five out of the six patients had detectable CMV viremia. Kidney biopsy revealed glomerulopathy in four cases and tubulointerstitial involvement in two cases. All patients exhibited decline in renal function at the onset of infection. Four out of six patients had improvement of renal function following treatment of CMV disease. To date, this is the largest case series of pure biopsy-proven CMV renal infection described in a single center.

A high level of urinary retinol-binding protein is associated with cytomegalovirus infection in kidney transplantation

The indirect effects of cytomegalovirus (CMV) viremia can be related to chronic changes in renal allograft structure, but its real impact in early and late graft function remains speculative. A total of 159 patients undergoing renal transplantation using a preemptive therapeutic strategy to prevent CMV disease were included in the present study. The patients were prospectively followed, with serial measurements of urinary retinol-binding protein (uRBP), a marker of proximal tubule injury. uRBP levels and their dynamic performance were compared according to CMV viremia and the 5-year estimated glomerular filtration rate (eGFR), as measured with the modification of diet in renal disease (MDRD) equation. CMV viremia was detected in 79.9% of the patients, with high uRBP levels being detected in 76.0% of these patients (compared with 40.7% in CMV-, P=0.005). High uRBP was associated with male recipients (P=0.02), the number of mismatches (P=0.02) and CMV infection (P=0.001). Five-year eGFR was worse in patients with high uRBP levels (50.3 ± 25.8 compared with 59.8 ± 26.4 ml/min, P=0.04). In a multivariate model, eGFR <60 ml/min was associated with donor age (P<0.001), the number of mismatches (P=0.04), thymoglobulin dose (P=0.02), the presence of and time with delayed graft function (DGF) (P=0.005 and P=0.04), 1-month tacrolimus levels (P=0.03), and uRBP levels after CMV treatment (P=0.01). Patients with CMV viremia in whom uRBP levels were normalized up to 3 months after treatment showed significantly better 5-year eGFR than those in whom uRBP remained high: 61.0 ± 24.2 compared with 42.3 ± 23.9 ml/min, P<0.001. CMV viremia was associated with high uRBP levels, which represent a profile of proximal tubule injury, and the dynamic performance of uRBP after treatment was associated with long-term kidney graft function.

New therapies for human cytomegalovirus infections

The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.

CMV-infected kidney grafts drive the expansion of blood-borne CMV-specific T cells restricted by shared class I HLA molecules via presentation on donor cells

We aimed to determine the role of cytomegalovirus (CMV)-infected donor cells in the development of a CMV-specific immune response in kidney transplant recipients. We assessed the CMV pp65-specific immune response by using interferon-ɣ ELISPOT and dextramers in peripheral blood mononuclear cells from 115 recipients (D+R- 31, D+R + 44, D-R + 40) late after transplantation (mean 59 ± 42 months). Receiving a kidney from a D+ donor resulted in a higher number of IFN-ɣ-producing anti-CMV T cells (P = .004). This effect disappeared with the absence of shared HLA class I specificities between donors and recipients (P = .430). To confirm the role of donor cells in stimulating the expansion of newly developed CMV-specific CD8⁺ T cells after transplantation, we compared the number of HLA-A2-restricted CMV-specific CD8⁺ T cells in primo-infected recipients who received an HLA-A2 or non-HLA-A2 graft. The median of anti-CMV pp65 T cells restricted by HLA-A2 was very low for patients who received a non-HLA-A2 graft vs an HLA-A2 graft (300 [0-14638] vs. 17972 [222-85594] anti-CMV pp65 CD8⁺ T cells/million CD8⁺ T cells, P = .001). This adds new evidence that CMV-infected kidney donor cells present CMV peptides and drive an inflation of memory CMV-specific CD8⁺ T cells, likely because of frequent CMV replications within the graft.

Polymorphism in programmed cell death 1 gene is strongly associated with lung and kidney allograft survival in recipients from CMV-positive donors

BACKGROUND

Cytomegalovirus (CMV) has a role in chronic rejection and graft loss in kidney transplant (KTx) and lung transplant (LTx) recipients. In addition, donor CMV seropositivity is an independent risk factor for renal graft loss. The anti-CMV response might modulate this risk. Expression of programmed cell death 1 (PD-1), a receptor involved in viral-specific T-cell exhaustion, is influenced by a single nucleotide polymorphism called PD-1.3 (wild-type allele G, variant allele A).

METHODS

We performed a retrospective study to assess the impact of PD-1.3 on graft outcome in donor CMV seropositive (D+) and donor CMV seronegative (D-) KTx and LTx. We also performed a case-control study to evaluate the anti-CMVpp65 response according to genotype.

RESULTS

PD-1.3 was determined in 1,119 KTx and 181 LTx. In 481 D+ KTx, A allele carriers (24%) experienced significantly less graft failure compared with GG carriers (p = 0.001). Multivariate analysis showed that this association was independent of donor and recipient age, acute rejection episodes, and number of human leukocyte antigen mismatches (hazard ratio, 0.381; 95% confidence interval, 0.209-0.696; p = 0.002). Analysis in 85 D+ LTx showed similar results: A allele carriers had better survival (hazard ratio, 0.302; 95% confidence interval, 0.128-0.716; p = 0.006) and greater 6-month forced expiratory volume (71% ± 17% vs 54% ± 16%, p = 0.001). In D- recipients, PD-1.3 did not affect KTx or LTx outcome. Finally, AA recipients had a stronger anti-CMVpp65 T-cell response than matched GG recipients (p = 0.003).

CONCLUSIONS

The A variant allele in PD-1.3 single nucleotide polymorphism improved graft survival in kidney and lung transplant recipients receiving grafts from CMV-positive donors.

Cytomegalovirus driven immunosenescence-An immune phenotype with or without clinical impact?

The continuous emerging increase in life span has led to vulnerability to a number of different diseases in the elderly. Some of these risks may be attributed to specific changes in the immune system referred to as immunoscenescence. This term aims to describe decreased immune functions among elderly individuals, and is characterized to be harmful age-associated changes in the immune system that lead to its gradual immune dysfunction. An impaired function of the immune system may increase susceptibility to various diseases in the elderly population such as infections, cardiovascular diseases and cancer. Although it is unclear how this immune phenotype develops, emerging evidence suggest that it may reflect an exhaustion of the immune system, possibly caused by one or several chronic infections. The main candidate is human cytomegalovirus (CMV), which can induce immune dysfunctions observed in immunoscenescence. Although the immune system is currently considered to be exhausted in CMV positive elderly individuals, it is not known whether such dysfunction of the immune system is a main reason for increased susceptibility to other diseases, or if direct effects of the virus in disease pathogenesis reflect the increased vulnerability to them. These aspects will be discussed in this review.

Cytomegalovirus in human brain tumors: Role in pathogenesis and potential treatment options

During the last years increasing evidence implies that human cytomegalovirus (CMV) can be attributed to human malignancies arising from numerous tissues. In this perspective, we will review and discuss the potential mechanisms through which CMV infection may contribute to brain tumors by affecting tumor cell initiation, progression and metastasis formation. Recent evidence also suggests that anti-CMV treatment results in impaired tumor growth of CMV positive xenografts in animal models and potentially increased survival in CMV positive glioblastoma patients. Based on these observations and the high tumor promoting capacity of this virus, the classical and novel antiviral therapies against CMV should be revisited as they may represent a great promise for halting tumor progression and lower cancer deaths.

Direct and Indirect Effects of Cytomegalovirus-Induced γδ T Cells after Kidney Transplantation

Despite effective anti-viral therapies, cytomegalovirus (CMV) is still associated with direct (CMV disease) and indirect effects (rejection and poor graft survival) in kidney transplant recipients. Recently, an unconventional T cell population (collectively designated as Vδ2^neg γδ T cells) has been characterized during the anti-CMV immune response in all solid-organ and bone-marrow transplant recipients, neonates, and healthy people. These CMV-induced Vδ2^neg γδ T cells undergo a dramatic and stable expansion after CMV infection, in a conventional “adaptive” manner. Similarly, as CMV-specific CD8+ αβ T cells, they exhibit an effector/memory TEMRA phenotype and cytotoxic effector functions. Activation of Vδ2^neg γδ T cells by CMV-infected cells involves the γδ T cell receptor (TCR) and still ill-defined co-stimulatory molecules such as LFA-1. A multiple of Vδ2^neg γδ TCR ligands are apparently recognized on CMV-infected cells, the first one identified being the major histocompatibility complex-related molecule endothelial protein C receptor. A singularity of CMV-induced Vδ2^neg γδ T cells is to acquire CD16 expression and to exert an antibody-dependent cell-mediated inhibition on CMV replication, which is controlled by a specific cytokine microenvironment. Beyond the well-demonstrated direct anti-CMV effect of Vδ2^neg γδ T cells, unexpected indirect effects of these cells have been also observed in the context of kidney transplantation. CMV-induced Vδ2^neg γδ T cells have been involved in surveillance of malignancy subsequent to long-term immunosuppression. Moreover, CMV-induced CD16+ γδ T cells are cell effectors of antibody-mediated rejection of kidney transplants, and represent a new physiopathological contribution to the well-known association between CMV infection and poor graft survival. All these basic and clinical studies paved the road to the development of a future γδ T cell-based immunotherapy. In the meantime, γδ T cell monitoring should prove a valuable immunological biomarker in the management of CMV infection.

The efficacy and cost-effectiveness of valacyclovir in cytomegalovirus prevention in solid organ transplantation

Prevention of cytomegalovirus infection using antiviral prophylaxis or the pre-emptive therapy approach is an integral part of management of patients after solid organ transplantation. Regarding renal transplantation, valacyclovir is currently the only antiviral agent recommended for prophylaxis as an alternative to valganciclovir. This review article discusses studies documenting the efficacy and safety of valacyclovir prophylaxis as well as those comparing valacyclovir with other prophylactic regimens or with pre-emptive therapy. Also addressed are the economic aspects supporting the cost-effectiveness of valacyclovir prophylaxis and demonstrating lower costs compared with other cytomegalovirus preventive strategies.

Cytomegalovirus-responsive γδ T cells: novel effector cells in antibody-mediated kidney allograft microcirculation lesions

Human cytomegalovirus infection in transplant recipients has been associated with adverse renal allograft outcome and with a large γδ T-cell response, but whether both mechanisms are connected is unknown. We previously showed that most expanded circulating cytomegalovirus-responsive γδ T cells express the Fcγ-receptor CD16, suggesting that γδ T cells may participate in allograft lesions mediated by donor-specific antibodies through antibody-dependent cellular cytotoxicity. Here, we show that cytomegalovirus-specific CD16(pos) γδ T cells can perform antibody-dependent cellular cytotoxicity against stromal cells coated with donor-specific antibodies in vitro. In vivo, graft-infiltrating γδ T cells localized in close contact with endothelial cells only in patients who experienced cytomegalovirus infection and were more frequent within peritubular capillaries and glomeruli from antibody-mediated acute rejections than within those from T cell-mediated acute rejections. Finally, a persistently increased percentage of circulating cytomegalovirus-induced γδ T cells correlated inversely with the 1-year eGFR only in kidney recipients with donor-specific antibodies. Collectively, these data support the conclusion that cytomegalovirus-induced γδ T cells are involved in, and may serve as a clinical biomarker of, antibody-mediated lesions of kidney transplants. Moreover, these findings offer a new physiopathologic link between cytomegalovirus infection and allograft dysfunction in recipients with donor-specific antibodies.

Human cytomegalovirus inhibits erythropoietin production

Anemia is a feature of CKD and a complication of renal transplantation, often caused by impaired production of erythropoietin. The kidney is a target organ for human cytomegalovirus (hCMV) in such patients, but it is not known whether hCMV effects erythropoietin production. We found that kidneys from patients with CKD were positive for hCMV protein and that blood levels of hCMV IgG inversely correlated with red blood cell count. In mice, systemic murine cytomegalovirus infection decreased serum erythropoietin levels. In human erythropoietin-producing cells, hCMV inhibited hypoxia-induced expression of erythropoietin mRNA and protein. hCMV early gene expression was responsible, as ultraviolet-inactivated virus had no effect and valganciclovir treatment showed that late gene expression was nonessential. Hypoxia-induced gene transcription is controlled by the transcription factors hypoxia-inducible transcription factor (HIF)-1α and HIF2α, which are constitutively produced but stable only under low oxygen conditions. We found that hCMV inhibited constitutive production of HIF2α mRNA. HIF2α is thought to be the master regulator of erythropoietin transcription. Single-cell analysis revealed that nuclear accumulation of HIF2α was inhibited in hCMV-infected cells, and the extent of inhibition correlated with hCMV protein expression. Our findings suggest that renal hCMV infection could induce or exacerbate anemia in patients.

CMV infection in the donor and increased kidney graft loss: impact of full HLA-I mismatch and posttransplantation CD8(+) cell reduction

Despite a large body of literature, the impact of chronic cytomegalovirus (CMV) infection in donor on long-term graft survival remains unclear, and factors modulating the effect of CMV infection on graft survival are presently unknown. In this retrospective study of 1279 kidney transplant patients, we analyzed long-term graft survival and evolution of CD8(+) cell population in donors and recipients by CMV serology and antigenemia status. A positive CMV serology in the donor was an independent risk factor for graft loss, especially among CMV-positive recipients (R(+) ). Antigenemia was not a risk factor for graft loss and kidneys from CMV-positive donors remained associated with poor graft survival among antigenemia-free recipients. Detrimental impact of donor's CMV seropositivity on graft survival was restricted to patients with full HLA-I mismatch, suggesting a role of CD8(+) cells. In R(+) patients with positive CMV antigenemia during the first year, CD8(+) cell count did not increase at 2 years posttransplantation, in contrast to R(-) recipients. In addition, marked CD8(+) -cell decrease was a risk factor of graft failure in these patients. This study identifies HLA-I full mismatch and a decrease of CD8(+) cell count at 2 years as important determinants of CMV-associated graft loss.

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

Recent evidence suggesting a potential anti-CMV effect of mTORis is of great interest to the transplant community. However, the concept of an immunosuppressant with antiviral properties is not new, with many accounts of the antiviral properties of several agents over the years. Despite these reports, to date, there has been little effort to collate the evidence into a fuller picture. This manuscript was developed to gather the evidence of antiviral activity of the agents that comprise a typical immunosuppressive regimen against viruses that commonly reactivate following transplant (HHV1 and 2, VZV, EBV, CMV and HHV6, 7, and 8, HCV, HBV, BKV, HIV, HPV, and parvovirus). Appropriate immunosuppressive regimens posttransplant that avoid acute rejection while reducing risk of viral reactivation are also reviewed. The existing literature was disparate in nature, although indicating a possible stimulatory effect of tacrolimus on BKV, potentiation of viral reactivation by steroids, and a potential advantage of mammalian target of rapamycin (mTOR) inhibition in several viral infections, including BKV, HPV, and several herpesviruses.

Six-month low-dose valganciclovir prophylaxis in cytomegalovirus D+/R- kidney transplant patients receiving thymoglobulin induction

BACKGROUND

The use of T-cell-depleting antibody, such as thymoglobulin, is a risk factor for cytomegalovirus (CMV) infection. We studied the effectiveness of 6 months of low-dose valganciclovir prophylaxis in CMV-naive kidney transplant recipients of CMV-positive donor kidney (D+/R-) receiving thymoglobulin induction.

METHODS

We included all D+/R- kidney transplant patients between October 2005 and December 2010 who received valganciclovir 450 mg daily for 6 months as per center protocol. CMV infection was confirmed by positive viremia. Kaplan-Meier and multivariate Cox proportional regression analyses were employed to compare the risk of CMV infection between patients with and without the use of thymoglobulin induction.

RESULTS

Out of 170 D+/R- kidney transplant patients, 42 cases of CMV infection (24.6%) were diagnosed after a median follow-up of 3.2 years: six patients from the noninduction (9.4%) and 36 from the induction cohort (34.0%). The induction with thymoglobulin was associated with four times greater risk of developing CMV infection (adjusted hazard ratio: AHR 4.15, 95% 1.75, 9.86, P = .001). The use of thymoglobulin was associated with leukopenia but not neutropenia.

CONCLUSIONS

Additional measures are needed to reduce the elevated incidence of CMV infection in D+/R- kidney transplant patients receiving induction with thymoglobulin.

Latent cytomegalovirus infection is an independent risk factor for late graft failure in renal transplant recipients

Background

Cytomegalovirus (CMV) is a risk factor for rejection and mortality soon after renal transplantation. Little is known about its consequences longer after transplantation. We prospectively investigated whether latent CMV infection is a risk factor for graft failure and mortality long after transplantation.

Material/Methods

Our study included 606 renal transplant recipients (RTR) with a functioning graft for >1 year. CMV serology was determined using ELISA. RTRs were divided into CMV-seronegative and latent CMV (seropositive + seroconverted).

Results

We measured CMV IgG at 6.0 [2.6–11.4] years post-transplant. During follow-up (7.0 [6.2–7.5] years), 54 (9%) RTRs experienced graft failure and 137 (23%) RTRs died. Risk for graft failure and mortality was significantly higher in RTRs with latent CMV compared to CMV-seronegative RTRs (HR=3.1, P=0.005 and HR=2.0, P=0.002, respectively). After adjustment for potential confounders, latent CMV infection remained an independent risk factor for graft failure (HR=4.6, P=0.001), but not for mortality (HR=1.4, P=0.2).

Conclusions

Latent CMV is an independent risk factor for graft failure long after renal transplantation and carries a higher risk for graft failure than for mortality. These findings confirm the notion that latent CMV can be harmful in transplanted kidneys.

Valganciclovir to prevent or treat cytomegalovirus disease in organ transplantation

Cytomegalovirus (CMV) is generally considered the most significant pathogen to infect patients following organ transplantation. Significant improvements have been achieved in the management of CMV disease over recent years, especially since the introduction of oral drugs such as oral ganciclovir followed by valganciclovir (VGC), a prodrug of ganciclovir with enhanced bioavailability. Several randomized controlled trials have shown that VGC is an efficacious and convenient oral drug to prevent or treat CMV disease in solid-organ transplant recipients. In this article, we discuss the clinical and pharmacological experience with the use of VGC for the management of CMV in solid-organ transplant recipients. Finally, novel strategies to further reduce the incidence of CMV disease after transplantation are also reviewed.

Intragraft cytomegalovirus protein expression is associated with reduced renal allograft survival

BACKGROUND

Cytomegalovirus (CMV) infection is a risk factor for acute and chronic rejection of transplanted organs and is thought to mediate rejection indirectly.

METHODS

In this retrospective observational cohort study, early- and end-stage biopsies from renal allografts lost because of chronic allograft dysfunction (n = 29) were examined for CMV antigens and DNA using immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction.

RESULTS

CMV immediate-early and late proteins were present in 27 (93%) of 29 of the end-stage chronic allograft dysfunction biopsies and in 64% of the corresponding early biopsies but not in pretransplant biopsies from CMV-seronegative donors (n = 3). Graft survival time was reduced in patients with moderate or high CMV levels in the graft soon after transplantation compared with that in patients with no or low CMV levels in the graft. No significant difference was observed in serum creatinine obtained at the time of early biopsies.

CONCLUSIONS

We provide evidence that intragraft CMV protein expression is associated with end-stage chronic renal allograft dysfunction, that intragraft CMV levels increase as graft function deteriorates, and that CMV protein expression in the grafts soon after transplant is associated with reduced graft survival. Thus, CMV may have a pathological role in chronic renal allograft dysfunction.

Strategies for managing cytomegalovirus in transplant recipients

IMPORTANCE OF THE FIELD

Cytomegalovirus (CMV) is the most important pathogen that affects transplant recipients, by directly causing clinical disease and by indirectly reducing patient and allograft survival.

AREAS COVERED IN THIS REVIEW

This review provides a brief overview of the direct and indirect effects of CMV disease and the traditional and newly described factors that increase the risk of disease after transplantation. Newly acquired data in the diagnostics, prevention and treatment of CMV infection are discussed, with emphasis on guidelines for management as recently endorsed by the American Society of Transplantation and the Transplantation Society.

WHAT THE READER WILL GAIN

The reader will gain up-to-date insights into the contemporary management of CMV after solid organ transplantation. Practical aspects of its diagnosis, prevention and treatment are discussed. Emerging concerns of late-onset CMV disease and antiviral resistance are also highlighted to emphasize the need to optimize CMV-prevention strategies.

TAKE HOME MESSAGE

Prevention of CMV disease is an important goal in the management of solid organ transplant recipients. The efficacy of CMV prevention should be measured not only by the significant reduction in CMV incidence but, as importantly, by the improvement in long-term allograft and patient survival.

Revisiting the effects of CMV on long-term transplant outcome

PURPOSE OF THE REVIEW

Indirect effects of cytomegalovirus (CMV) in transplantation are of three types: increase in systemic immunosuppression, increased risk of malignancy (especially Epstein-Barr virus-related B-cell lymphoproliferative disease), and the possible contribution to allograft injury. Despite modern and potent antiviral drugs, the real impact of CMV in transplantation, especially kidney transplantation, remains a challenge because many confounding factors arise when analyzing this question.This review will fuel the discussion and review some of the recent data.

RECENT FINDINGS

A recent study on cardiac allograft in mice has shown that CMV in latently infected recipients could break graft acceptance. Although the exact nature of response was not addressed, this study suggested that CMV reactivation inside the graft played an important part in graft losses. Other recent results suggest that the quality of immune response against CMV influences graft outcome in both cardiac and kidney transplant patients. Other evidence suggests the link between CMV infection, immune senescence and vascular disease in the whole population. Studies have opened the perspective for new strategies to prevent indirect effects of CMV.

SUMMARY

Although a causal relationship between CMV reactivation and graft injury is supported by a large body of experimental and clinical data, definitive proof in clinical transplantation is still lacking to exclude an associative relationship. Large randomized clinical trials analyzing long-term graft survival and comparing prophylaxis with preemptive, especially D/R, is probably an efficient way to establish a causal relationship. Research on new antiviral strategies applicable over the long term is important.

Primary CMV infections are common in kidney transplant recipients after 6 months valganciclovir prophylaxis

Prolonging cytomegalovirus (CMV) prophylaxis in CMV seronegative recipients of a kidney from CMV seropositive donor (D+/R-) may reduce the incidence of late infections. We analyzed late-onset primary CMV infections after 6 months valganciclovir prophylaxis. Data from all CMV D+/R- kidney transplant recipients between January 2004 and December 2008 at our center were analyzed. Patients with a functioning graft at 6 months after transplantation who received 6 months of valganciclovir prophylaxis 900 mg once daily were included (N = 127). CMV was diagnosed with quantitative PCR. Prophylaxis was completed in 119 patients. Prophylaxis was stopped at 3-5 months due to leukopenia or gastrointestinal side effects in eight patients. Late-onset primary CMV infection developed in 47/127 (37%) patients median 244 days after transplantation (range 150-655) and median 67 days after the cessation of prophylaxis (range 1-475). Four infections were asymptomatic. In others, symptoms included fever (N = 28), gastrointestinal symptoms (nausea, vomiting, diarrhea) (N = 24), respiratory tract symptoms (N = 12), and hepatopathy (N = 6). Median peak viral load was 13500 copies/mL (range 400-2,831,000). Recurrent CMV infection developed in 9/47 (19%) patients. No significant risk factors for CMV infection were identified. Symptomatic primary CMV infections were commonly detected also after prolonged valganciclovir prophylaxis.

New developments in the management of cytomegalovirus infection after solid organ transplantation

Despite remarkable advances in the diagnostic and therapeutic modalities for its management, cytomegalovirus (CMV) remains one of the most important pathogens impacting on the outcome of transplantation. Not only does CMV directly cause morbidity and occasional mortality, it also influences many short-term and long-term indirect effects that collectively contribute to reduced allograft and patient survival. Prevention of CMV infection and disease is therefore key in ensuring the successful outcome of solid organ transplantation (SOT). In this regard, antiviral prophylaxis and pre-emptive therapy are similarly effective in preventing CMV disease after transplantation. However, current guidelines prefer antiviral prophylaxis over pre-emptive therapy in preventing CMV disease in high-risk SOT recipients, such as CMV-seronegative recipients of organs from CMV-seropositive donors (CMV D+/R-), and lung, intestinal and pancreas transplant recipients. Antiviral prophylaxis has the benefits of reducing not only the incidence of CMV disease, but also the indirect effects of CMV on allograft and patient survival. The major drawback of antiviral prophylaxis is delayed-onset CMV disease, which occurs in 15-38% of CMV D+/R- SOT recipients who received 3 months of prophylaxis. Allograft rejection, over-immunosuppression and lack of CMV-specific immunity are factors that predispose patients to delayed-onset CMV disease. A recent randomized trial in CMV D+/R- kidney recipients demonstrates a significant reduction in the incidence of CMV disease when valganciclovir prophylaxis is extended to 200 days (compared with the standard 100 days) after transplantation; however, the safety and cost of this prolonged approach has yet to be assessed. In some studies, delayed-onset CMV disease has been significantly associated with allograft loss and mortality. In the vast majority of patients, CMV disease responds to treatment with intravenous ganciclovir. Recently, oral valganciclovir was demonstrated to have an efficacy that is comparable to intravenous ganciclovir in treating mild to moderate cases of CMV disease in SOT recipients. Reduction in the degree of immunosuppression should complement antiviral treatment of CMV disease. Although it remains rare, ganciclovir-resistant CMV disease is increasingly seen in clinical practice, potentially fostered by the prolonged use of antivirals in high-risk over-immunosuppressed transplant recipients. Treatment of drug-resistant CMV is currently non-standardized and may include foscarnet, cidofovir, CMV hyperimmune globulins or leflunomide. The investigational drug marivabir had the potential to treat ganciclovir-resistant CMV disease as it acts through a different mechanism. However, the recent phase III clinical trial in allogeneic bone marrow transplant recipients showed that maribavir was not significantly better than placebo for the prevention of CMV disease. Similarly, the preliminary data in a liver transplant population suggests that maribavir was inferior to oral ganciclovir for the prevention of CMV disease. This article reviews the recent data and other developments in the management of CMV infection after SOT.

Predictors of renal dysfunction at 1 year in heart transplant patients

BACKGROUND

Renal dysfunction (RD) is one of the most significant long-term complications of heart transplantation (HT). Although RD is generally attributed to a direct effect of calcineurin inhibitors, it is more probable that multiple factors contribute to its development. The aim of this study was to search for predictor variables of RD at 1 year after HT.

METHODS

Three hundred sixteen consecutive HT patients were evaluated. The relationship between RD at 1 year (glomerular filtration rate <60 mL/min/1.73 m2), and pretransplant and 1-year follow-up variables was analyzed.

RESULTS

At 1 year following HT, 181 patients (57%) had a glomerular filtration rate of <60 mL/min/1.73 m2. On multivariate analysis, pretransplant serum creatinine values (odds ratio [OR] 5.106, 95% confidence interval [CI]: 2.35-11.09, P=0.0001) and cytomegalovirus (CMV) infection (OR 2.04, 95% CI: 1.08-3.83, P=0.027) were significant predictors of RD, and diabetes mellitus was almost significant (OR 1.65, 95% CI: 0.98-2.76, P=0.055). Variables protective against RD were induction therapy with interleukin-2 receptor antagonists versus muromonab-CD3 (OR 0.389, 95% CI: 0.24-0.61, P=0.0001), maintenance treatment with mycophenolate mofetil versus azathioprine (OR 0.42, 95% CI: 0.26-0.68, P=0.0001), and CMV antiviral prophylaxis (OR 0.38, 95% CI: 0.17-0.68, P=0.021).

CONCLUSIONS

Fifty-seven percent of HT patients had RD at 1 year posttransplant. RD was associated with pretransplant serum creatinine values, CMV infection, and diabetes mellitus. Induction with interleukin-2 receptor antagonists, treatment with mycophenolate mofetil, and antiviral prophylaxis for CMV infection all helped maintain renal function in this cohort of HT patients.

Defining the risks for cytomegalovirus infection and disease after solid organ transplantation

Cytomegalovirus continues to be one of the most clinically significant infections after solid organ transplantation. Classic definitions of patients at high risk for infection and tissue-invasive disease are focused on recipient-donor serostatus, type of organ transplanted, and overall level of immunosuppression. However, recent trends in clinical practice call for a reevaluation of cytomegalovirus infection risks after solid organ transplantation. Indeed, whereas early-onset cytomegalovirus infection is usually controlled by antiviral prophylaxis with ganciclovir and derivatives, delayed- and late-onset cytomegalovirus infection can develop after the completion of a course of preventive therapy. In addition, indirect effects of cytomegalovirus infection may occur as a result of persistent low-level viremia. Suboptimal dosing of antiviral drugs due to specific drug toxicities may result in the development of ganciclovir-resistant cytomegalovirus disease. The relationship between organ allograft rejection and cytomegalovirus infection and disease has been recognized for some time. Transplantation of increasing numbers of extended-criteria donor organs increases the risk of delayed graft function and acute rejection, prompting the use of more intensive immunosuppression. In addition, the trend to spare long-term exposure to calcineurin inhibitors has contributed to a resurgence in the use of polyclonal T-cell induction immunosuppressive agents, which may reduce host anticytomegalovirus immunity. We discuss the current trends in solid organ transplantation that provide a foundation for defining risks for cytomegalovirus infection and disease, including identification of patients who would benefit from more aggressive cytomegalovirus monitoring and prevention strategies.

Treatment strategies to minimize or prevent chronic allograft dysfunction in pediatric renal transplant recipients: an overview

Long-term allograft survival poses a major problem in pediatric renal transplantation, with allograft nephropathy being the principal cause of graft failure after the first post-transplant year. The mechanisms of nephron loss resulting in graft dysfunction are multiple, comprising both immunologic factors such as acute and chronic antibody- or T-cell-mediated rejection and non-immunologic components. The latter include peri-transplant injuries and renovascular lesions (renal artery stenosis, thrombosis) as well as cardiovascular risk factors such as arterial hypertension and hyperlipidemia. Another relevant issue leading to progressive nephron loss and declining kidney transplant function is acute and chronic nephrotoxicity induced by the calcineurin inhibitors (CNIs) ciclosporin (cyclosporine microemulsion) and tacrolimus. Furthermore, the presence of an abnormal lower urinary tract as well as bacterial (recurrent pyelonephritis) and viral (cytomegalovirus [CMV], polyomavirus [BK virus; BKV]) infections are crucial factors involved in the incidence of chronic allograft dysfunction and graft failure. Renovascular lesions and lower urinary tract obstruction are typical indicators for surgical intervention. The aim of treatment in pediatric patients with renal failure secondary to a dysfunctional lower urinary tract is to create a sterile, continent, and nonrefluxive reservoir. Surgical techniques such as bladder augmentation and the introduction of intermittent catheterization and anticholinergic therapy have significantly improved graft outcome. Arterial hypertension, another factor responsible for graft function deterioration in pediatric renal transplant recipients, is controlled preferably by the use of angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor antagonists, which are known to possess nephroprotective properties in addition to their potent antihypertensive effects. Although treatment of subclinical rejection with augmented immunosuppression has been associated with better graft survival, an increase of the immunosuppressive level to avoid subclinical rejection should be weighed against the risk of infection. The majority of viral infections affecting kidney allografts are caused by CMV and BKV. Antiviral CMV prophylaxis or pre-emptive therapy with ganciclovir has been shown to have beneficial effects in the pediatric renal transplant population. Treatment of BKV-induced nephropathy is based on reduction of the immunosuppressant therapy, although specific antiviral agents such as cidofovir and leflunomide are known to inhibit BKV. However, cidofovir itself is nephrotoxic and should therefore be administered cautiously to pediatric renal transplant patients. Since CNIs are likewise known for their nephrotoxic effects, especially with long-term use, alteration of the immunosuppressant regimen is necessary in case of deteriorating graft function due to CNI-induced histopathologic changes. Complete CNI avoidance seems inappropriate because, in this situation in pediatric renal transplant recipients, other relatively potent immunosuppressant agents such as lymphocyte-depleting antibodies, which are frequently accompanied by a higher incidence of infections, are needed for rejection prophylaxis. CNI withdrawal and switching of the immunosuppressant regimen from CNI therapy to sirolimus may be an option for some pediatric renal transplant patients with less advanced graft function deterioration. Nevertheless, potential adverse events such as aggravation of proteinuria, hyperlipidemia, myelosuppression, and hypergonadotropic hypogonadism have to be considered, and controlled studies are lacking. At present, an immunosuppressant maintenance therapy composed of low-dose tacrolimus or ciclosporin (CNI minimization) and mycophenolate mofetil with low-dose corticosteroids appears to be the most promising strategy to adopt in pediatric renal transplant recipients at low or normal immunologic risk.

Chlamydia pneumoniae infection in patients after kidney transplantation treated with spiramycin

INTRODUCTION

Previous research has pointed to a role of Chlamydia pneumoniae infection in the development of chronic renal allograft dysfunction, chronic liver rejection, and vasculopathy in the transplanted heart. The aim of this study was to evaluate the presence of C. pneumoniae prior to and after kidney transplantation as well as to determine the role of spiramycin therapy among kidney transplant recipients.

MATERIALS AND METHODS

The study group consisted of 50 patients (25 pairs) who received kidney transplants from cadaveric donors. One of the 2 kidneys from a donor was transplanted to a patient randomized to spiramycin (2 x 3 million U/d orally for 3 months; group S) and the other to a patient assigned as control (group C). Markers of infection were assessed on day 1 posttransplantation and 3 months later (average, 94 days). All 50 patients were examined for the presence of bacterial DNA in peripheral blood leukocytes using real-time polymerase chain reaction (PCR) and for titers of serum anti C. pneumoniae immunoglobulin (IgG) and IgA antibodies using microimmunofluorescence (MIF). C. pneumoniae infection was diagnosed by the presence of C. pneumoniae DNA in peripheral blood leukocytes or positive antibodies of both classes.

RESULTS

C. pneumoniae infection was initially diagnosed in 14 patients among group S and 8 patients among group C (P = not significant [ns]) and after 3 months in 12 and 9 patients, respectively (P = ns). Conversion from positive to negative C. pneumoniae status occured in 7 patients among group S and 1 patient among group C (P = .04). Conversion from negative to positive C. pneumoniae status occured in 5 patients from group S and 2 patients from group C (P = ns).

CONCLUSIONS

These results suggest a possible role for spiramycin treatment of C pneumoniae infection in kidney allograft recipients. C. pneumoniae infection diagnosis and treatment should be considered to be routine for every patient awaiting transplantation.

Manifestations of human cytomegalovirus infection: proposed mechanisms of acute and chronic disease

Infections with human cytomegalovirus (HCMV) are a major cause of morbidity and mortality in humans with acquired or developmental deficits in innate and adaptive immunity. In the normal immunocompetent host, symptoms rarely accompany acute infections, although prolonged virus shedding is frequent. Virus persistence is established in all infected individuals and appears to be maintained by both a chronic productive infections as well as latency with restricted viral gene expression. The contributions of the each of these mechanisms to the persistence of this virus in the individual is unknown but frequent virus shedding into the saliva and genitourinary tract likely accounts for the near universal incidence of infection in most populations in the world. The pathogenesis of disease associated with acute HCMV infection is most readily attributable to lytic virus replication and end organ damage either secondary to virus replication and cell death or from host immunological responses that target virus-infected cells. Antiviral agents limit the severity of disease associated with acute HCMV infections, suggesting a requirement for virus replication in clinical syndromes associated with acute infection. End organ disease secondary to unchecked virus replication can be observed in infants infected in utero, allograft recipients receiving potent immunosuppressive agents, and patients with HIV infections that exhibit a loss of adaptive immune function. In contrast, diseases associated with chronic or persistent infections appear in normal individuals and in the allografts of the transplant recipient. The manifestations of these infections appear related to chronic inflammation, but it is unclear if poorly controlled virus replication is necessary for the different phenotypic expressions of disease that are reported in these patients. Although the relationship between HCMV infection and chronic allograft rejection is well known, the mechanisms that account for the role of this virus in graft loss are not well understood. However, the capacity of this virus to persist in the midst of intense inflammation suggests that its persistence could serve as a trigger for the induction of host-vs-graft responses or alternatively host responses to HCMV could contribute to the inflammatory milieu characteristic of chronic allograft rejection.