The impact of cytomegalovirus infection and disease on rejection episodes in renal allograft recipients

High-dimensional mass cytometry identified circulating natural killer T-cell subsets associated with protection from cytomegalovirus infection in kidney transplant recipients

Cytomegalovirus (CMV) infection is associated with poor kidney transplant outcomes. While innate and adaptive immune cells have been implicated in its prevention, an in-depth characterization of the in vivo kinetics of multiple cell subsets and their role in protecting against CMV infection has not been achieved. Here, we performed high-dimensional immune phenotyping by mass cytometry, and functional assays, on 112 serially collected samples from CMV seropositive kidney transplant recipients. Advanced unsupervised deep learning analysis was used to assess immune cell populations that significantly correlated with prevention against CMV infection and anti-viral immune function. Prior to infection, kidney transplant recipients who developed CMV infection showed significantly lower CMV-specific cell-mediated immune (CMI) frequencies than those that did not. A broad diversity of circulating cell subsets within innate and adaptive immune compartments were associated with CMV infection or protective CMV-specific CMI. While percentages of CMV (tetramer-stained)-specific T cells associated with high CMI responses and clinical protection, circulating CD3+CD8midCD56+ NK-T cells overall strongly associated with low CMI and subsequent infection. However, three NK-T cell subsets sharing the CD11b surface marker associated with CMV protection and correlated with strong anti-viral CMI frequencies in vitro. These data were validated in two external independent cohorts of kidney transplant recipients. Thus, we newly describe the kinetics of a novel NK-T cell subset that may have a protective role in post-transplantation CMV infection. Our findings pave the way to more mechanistic studies aimed at understanding the function of these cells in protection against CMV infection.

Renal transplantation using kidneys from a donor with high grade cytomegalovirus viraemia: case report and literature review

Transplanting organs from cytomegalovirus-seropositive donors into cytomegalovirus-seronegative recipients is an accepted practice. However, outcomes following transplantation of organs from donors with active cytomegalovirus disease are unknown. We present a case involving a patient aged 61 years with end-stage renal disease, seropositive for cytomegalovirus, who underwent dual kidney transplant from a donor with high-grade cytomegalovirus viraemia. The donor was on immunosuppressive therapy for systemic lupus erythematosus and interstitial lung disease and had been admitted with respiratory failure. The donor had high-grade cytomegalovirus viraemia with probable cytomegalovirus pneumonitis (cytomegalovirus viral load >100 000 international units [IU]/mL in plasma and 319 000 IU/mL in bronchoalveolar lavage). Renal biopsy at organ procurement showed the absence of cytomegalovirus inclusions. Following transplantation, the recipient had delayed graft function, with renal recovery after 1 week. The patient received basiliximab induction and standard tacrolimus-based maintenance immunosuppression. He received ganciclovir and valganciclovir treatment for 1 month, followed by valganciclovir prophylaxis (or viral load monitoring, when prophylaxis had to be paused) for 2 additional months to prevent donor-derived cytomegalovirus infection. Transient cytomegalovirus viraemia (peaking at 4480 IU/mL) developed at 4 months and resolved with 1 month of valganciclovir treatment. The patient is doing well 1 year after transplantation, with adequate kidney function. This case highlights the successful and safe transplantation of kidneys from a donor with cytomegalovirus disease into a cytomegalovirus-seropositive recipient. Further research is needed to confirm our findings and define post-transplantation management.

Impact of recipient age on mortality among Cytomegalovirus (CMV)-seronegative lung transplant recipients with CMV-seropositive donors

BACKGROUND

Cytomegalovirus (CMV)-seronegative lung transplant recipients (LTRs) with seropositive donors (CMV D+/R-) have the highest mortality of all CMV serostatuses. Due to immunosenescence and other factors, we hypothesized CMV D+/R- status might disproportionately impact older LTRs. Thus, we investigated whether recipient age modified the relationship between donor CMV status and mortality among CMV-seronegative LTRs.

METHODS

Adult, CMV-seronegative first-time lung-only recipients were identified through the Scientific Registry of Transplant Recipients between May 2005 and December 2019. We used adjusted multivariable Cox regression to assess the relationship of donor CMV status and death. Interaction between recipient age and donor CMV was assessed via likelihood ratio testing of nested Cox models and by the relative excess risk due to interaction (RERI) and attributable proportion (AP) of joint effects.

RESULTS

We identified 11,136 CMV-seronegative LTRs. The median age was 59 years; 65.2% were male, with leading transplant indication of idiopathic pulmonary fibrosis (35.6%); and 60.8% were CMV D+/R-. In multivariable modeling, CMV D+/R- status was associated with 27% increased hazard of death (adjusted hazard ratio: 1.27, 95% confidence interval: 1.21-1.34) compared to CMV D-/R-. Recipient age ≥60 years significantly modified the relationship between donor CMV-seropositive status and mortality on the additive scale, including RERI 0.24 and AP 11.4% (p = 0.001), that is, the interaction increased hazard of death by 0.24 and explained 11.4% of mortality in older CMV D+ recipients.

CONCLUSIONS

Among CMV-seronegative LTRs, donor CMV-seropositive status confers higher risk of posttransplant mortality, which is amplified in older recipients. Future studies should define optimal strategies for CMV prevention and management in older D+/R- LTRs.

Anti-Donor T-Cell Responses Are Not Necessarily Attenuated During Cytomegalovirus Infection in Kidney Transplant Recipients

BACKGROUND

Cytomegalovirus (CMV), the most common opportunistic infection of kidney transplantation (KT), is preventable by prophylactic and preemptive antiviral drugs in CMV-immunoglobulin (Ig)G-positive donors. Our preemptive therapy optimized immunosuppressive doses based on mixed lymphocyte response (MLR) results, regardless of preoperative CMV-IgG serostatus pairing. This study used the MLR to compare the anti-donor T-cell responses between CMV antigenemia-positive and -negative cases.

METHODS

One hundred patients underwent KT using a cyclosporine (CsA)-based immunosuppressive regimen at Hiroshima University Hospital. CMV antigenemia-positive cells were defined as 4/50,000 CMVpp65-positive cells. T-cell responses to allo-antigens were measured using MLR assays to evaluate patients' anti-donor immune reactivity. After analyzing the proliferation of CD4+ and CD8+ T-cell subsets, the stimulation indices of CD4+ or CD8+ T cells were quantified. The study used no prisoners, and the participants were neither coerced nor paid. The manuscript was created in compliance with the Helsinki Congress and the Declaration of Istanbul.

RESULTS

Forty-three patients tested positive for CMV antigenemia within 3 months after KT. No significant differences were found between the CMV antigenemia-positive and -negative groups in the stimulation indices for CD4+ and CD8+ T-cell responses to anti-donor stimulation. However, T-cell responses to third-party stimuli during the postoperative month 1 were significantly less in the CMV antigenemia-positive than -negative group.

CONCLUSION

Anti-donor T-cell responses are not necessarily attenuated during CMV infection in KT recipients. In CMV-infected KT recipients, caution should be exercised against inadvertent dose reduction of immunosuppressants.

Five-year single-center analysis of cytomegalovirus viremia in kidney transplant recipients and possible implication for novel prophylactic therapy approaches

BACKGROUND

Cytomegalovirus (CMV) infections are a common complication after kidney transplantation (KTx) and negatively affecting patient outcome. Valganciclovir (VGC) prophylaxis is often limited by drug-induced side effects and dose reduction due to decline in kidney function.

METHOD

In the present study, episodes of CMV viremia in the first year after KTx in a cohort of 316 recipients were analyzed retrospectively to identify risk factors linked to persistent infections.

RESULTS

In the studied cohort, 18.7% of patients showed a high-risk (HR) constellation (D+/R-) for CMV infections. CMV viremia affected 22% of our cohort, with HR patients being the most affected cohort (44.1%). Within this group, most viremic events (65.3%) occurred while patients were still on prophylactic therapy, showing significantly higher viral loads and a longer duration compared to seropositive recipients.

CONCLUSION

The analysis at hand revealed that detection of viremia under ongoing antiviral prophylaxis bears an increased risk for sustained viral replication and antiviral drug resistance in HR patients. We identified low estimated glomerular filtration rate (eGFR) and lower dose VGC prophylaxis post-KTx as a risk factor for breakthrough infections in HR patients in our single center cohort. These patients might benefit from a closer CMV monitoring or novel prophylactic agents as letermovir.

The role of efferocytosis and transplant rejection: Strategies in promoting transplantation tolerance using apoptotic cell therapy and/or synthetic particles

Recently, efforts have been made to recognize the precise reason(s) for transplant failure and the process of rejection utilizing the molecular signature. Most transplant recipients do not appreciate the unknown length of survival of allogeneic grafts with the existing standard of care. Two noteworthy immunological pathways occur during allogeneic transplant rejection. A nonspecific innate immune response predominates in the early stages of the immune reaction, and allogeneic antigens initiate a donor-specific adaptive reaction. Though the adaptive response is the major cause of allograft rejection, earlier pro-inflammatory responses that are part of the innate immune response are also regarded as significant in graft loss. The onset of the innate and adaptive immune response causes chronic and acute transplant rejection. Currently employed immunosuppressive medications have shown little or no influence on chronic rejection and, as a result, on overall long-term transplant survival. Furthermore, long-term pharmaceutical immunosuppression is associated with side effects, toxicity, and an increased risk of developing diseases, both infectious and metabolic. As a result, there is a need for the development of innovative donor-specific immunosuppressive medications to regulate the allorecognition pathways that induce graft loss and to reduce the side effects of immunosuppression. Efferocytosis is an immunomodulatory mechanism with fast and efficient clearance of apoptotic cells (ACs). As such, AC therapy strategies have been suggested to limit transplant-related sequelae. Efferocytosis-based medicines/treatments can also decrease the use of immunosuppressive drugs and have no detrimental side effects. Thus, this review aims to investigate the impact of efferocytosis on transplant rejection/tolerance and identify approaches using AC clearance to increase transplant viability.

Cytomegalovirus High-risk Kidney Transplant Recipients Show No Difference in Long-term Outcomes Following Preemptive Versus Prophylactic Management

BACKGROUND

Following kidney transplantation (KT), cytomegalovirus (CMV) infection remains an important challenge. Both prophylactic and preemptive antiviral protocols are used for CMV high-risk kidney recipients (donor seropositive/recipient seronegative; D+/R-). We performed a nationwide comparison of the 2 strategies in de novo D+/R- KT recipients accessing long-term outcomes.

METHODS

A nationwide retrospective study was conducted from 2007 to 2018, with follow-up until February 1, 2022. All adult D+/R- and R+ KT recipients were included. During the first 4 y, D+/R- recipients were managed preemptively, changing to 6 mo of valganciclovir prophylaxis from 2011. To adjust for the 2 time eras, de novo intermediate-risk (R+) recipients, who received preemptive CMV therapy throughout the study period, served as longitudinal controls for possible confounders.

RESULTS

A total of 2198 KT recipients (D+/R-, n = 428; R+, n = 1770) were included with a median follow-up of 9.4 (range, 3.1-15.1) y. As expected, a greater proportion experienced a CMV infection in the preemptive era compared with the prophylactic era and with a shorter time from KT to CMV infection ( P  < 0.001). However, there were no differences in long-term outcomes such as patient death (47/146 [32%] versus 57/282 [20%]; P  = 0.3), graft loss (64/146 [44%] versus 71/282 [25%]; P  = 0.5), or death censored graft loss (26/146 [18%] versus 26/282 [9%]; P  = 0.9) in the preemptive versus prophylactic era. Long-term outcomes in R+ recipients showed no signs of sequential era-related bias.

CONCLUSIONS

There were no significant differences in relevant long-term outcomes between preemptive and prophylactic CMV-preventive strategies in D+/R- kidney transplant recipients.

Conversion to mTOR Inhibitor to Reduce the Incidence of Cytomegalovirus Recurrence in Kidney Transplant Recipients Receiving Preemptive Treatment: A Prospective, Randomized Trial

BACKGROUND

Although mammalian target of rapamycin inhibitors (mTORi) are associated with a lower incidence of the first episode of cytomegalovirus (CMV) infection/disease in kidney transplant recipients receiving calcineurin inhibitors (CNIs), the efficacy and safety of the conversion from the antimetabolite to an mTORi for the prevention of CMV recurrence are unknown.

METHODS

In this single-center prospective randomized trial, low-immunological-risk, CMV-positive kidney transplant recipients receiving preemptive therapy were randomized to be converted (sirolimus [SRL]) or not (control [CTR]) immediately after the treatment of the first episode of CMV infection/disease and were followed for 12 mo. A sample size of 72 patients was calculated to demonstrate a 75% reduction in the incidence of CMV recurrence (80% power, 95% confidence level).

RESULTS

Of 3247 adult kidney transplants performed between September 13, 2015, and May 7, 2019, 1309 (40%) were treated for the first CMV infection/disease, and 72 were randomized (35 SRL and 37 CTR). In the SRL group, there were no episodes of CMV recurrence, compared with 16 patients in the CTR group (0% versus 43%; P  < 0.0001). Four patients had a second and 1 a third recurrent CMV event. Three of them were converted to SRL and did not develop any further CMV events. There were no differences in the incidence of acute rejection, drug discontinuation, kidney function, and patient and graft survival at 12 mo.

CONCLUSIONS

These data suggest that, in CMV-positive kidney transplant recipients, the conversion from an antiproliferative drug to SRL after the first CMV episode is an effective and safe strategy for recurrent episodes.

Acquisition of Antibody Against Cytomegalovirus After Kidney Transplantation in Seronegative Recipients

BACKGROUND

Cytomegalovirus (CMV) infection is one of the most important infectious diseases affecting recipients of kidney transplantation (KTx). However, the timing of seroconversion for CMV infection in seronegative recipients remains unclear. We evaluated CMV infections in CMV-seronegative recipients and the time to acquire antibodies against CMV.

METHODS

We conducted a retrospective study of 228 recipients who underwent KTx between March 1988 and February 2018 at the Niigata University Hospital. The anti-CMV IgG antibody profile before and after transplantation was analyzed. Oral acyclovir or valganciclovir was used as prophylactic therapy for at least 6 months after transplantation. Cytomegalovirus infection was defined as CMV viremia detected using the CMV pp65 antigenemia assay.

RESULTS

In this study, 50 cases (21.9%) were CMV-seronegative recipients. Over a median follow-up period of 126.7 months, 68% (34/50) of CMV-seronegative recipients experienced CMV viremia or overt disease symptoms as the first episode of CMV infection. The median duration from transplant to CMV infection was 69.0 days (range, 22-7426). All the recipients who experienced CMV infections acquired seroconversion. The median duration from KTx to seroconversion was 7.2 months (range, 2.8-252.3). Almost all CMV-seronegative recipients could acquire anti-CMV IgG antibodies within 2.5 years. In seronegative recipients whose donors were seronegative, no CMV viremia was found, and none developed anti-CMV IgG antibodies.

CONCLUSIONS

In the clinical practice of CMV-seronegative recipients, we should consider that physicians must closely monitor the occurrence of CMV infection up until 2.5 years after KTx.

Infection, Rejection, and the Connection

Solid organ transplantation is a life-saving treatment for people with end-stage organ disease. Immune-mediated transplant rejection is a common complication that decreases allograft survival. Although immunosuppression is required to prevent rejection, it also increases the risk of infection. Some infections, such as cytomegalovirus and BK virus, can promote inflammatory gene expression that can further tip the balance toward rejection. BK virus and other infections can induce damage that resembles the clinical pathology of rejection, and this complicates accurate diagnosis. Moreover, T cells specific for viral infection can lead to rejection through heterologous immunity to donor antigen directly mediated by antiviral cells. Thus, viral infections and allograft rejection interact in multiple ways that are important to maintain immunologic homeostasis in solid organ transplant recipients. Better insight into this dynamic interplay will help promote long-term transplant survival.

Relationship between Cytomegalovirus Viremia and Long-Term Outcomes in Kidney Transplant Recipients with Different Donor Ages

OBJECTIVES

To explore the Cytomegalovirus (CMV) burden on the long-term post-transplant course in different donor ages, we evaluated the incidence and risk factors for CMV in our kidney-transplanted patients (KTs) with extensive adoption of expanded-criteria donors (ECDs).

METHODS

Retrospective evaluation of 929 consecutive first KTs (49.5% receiving an organ from a donor ≥ 60 years) performed between 01-2003 and 12-2013. Overall survival was estimated using Kaplan-Meier curves; cumulative incidence function was additionally analyzed to consider the potential role of death with a functioning graft as a competitive event with graft dysfunction and to avoid overestimation. Apart from regular DNAemia monitoring in all patients, prophylaxis was adopted in high-risk groups (D+/R- or recipients of anti-thymocyte globulin induction), with pre-emptive therapy in the remaining groups.

RESULTS

CMV incidence was 19.5% (4-34.9% according to serostatus combination: D-/R-, D-/R+, D+/R+, D+/R-). Donor and recipient age, recipient pre-transplant hypertension, DR antigen compatibility, cold ischemia time, and post-transplant early complications, including rejection, urologic and renal artery stenosis, and lower renal function and proteinuria ≥ 0.5 g/day at one year after KT were associated with CMV. CMV determined lower death-censored graft survival (DCGS) (p < 0.01), with a prominent effect in R+ (p < 0.01) and without impact in R- (p = 0.32 in D-/R- and p = 0.006 in D+/R-). Interestingly, CMV occurrence influenced DCGS only in KTs who received grafts from donors < 50 or 50-69 years old (p < 0.01), while it was not significant with older donors (p = 0.07). The analysis of the cumulative incidence of graft loss accounting for death as a competing risk confirmed all these findings. In multivariate analysis, CMV replication/disease in the first year was an independent predictor for DCGS (HR 1.73 [1.3-2.3]).

CONCLUSIONS

In a large population with extensive ECD adoption, CMV viremia in the first year demonstrates its harmful effect with an independent role for graft loss and significant impact among R+ recipients and KTs with donors < 70 years.

Plasma proteome perturbation for CMV DNAemia in kidney transplantation

BACKGROUND

Cytomegalovirus (CMV) infection, either de novo or as reactivation after allotransplantation and chronic immunosuppression, is recognized to cause detrimental alloimmune effects, inclusive of higher susceptibility to graft rejection and substantive impact on chronic graft injury and reduced transplant survival. To obtain further insights into the evolution and pathogenesis of CMV infection in an immunocompromised host we evaluated changes in the circulating host proteome serially, before and after transplantation, and during and after CMV DNA replication (DNAemia), as measured by quantitative polymerase chain reaction (QPCR).

METHODS

LC-MS-based proteomics was conducted on 168 serially banked plasma samples, from 62 propensity score-matched kidney transplant recipients. Patients were stratified by CMV replication status into 31 with CMV DNAemia and 31 without CMV DNAemia. Patients had blood samples drawn at protocol times of 3- and 12-months post-transplant. Additionally, blood samples were also drawn before and 1 week and 1 month after detection of CMV DNAemia. Plasma proteins were analyzed using an LCMS 8060 triple quadrupole mass spectrometer. Further, public transcriptomic data on time matched PBMCs samples from the same patients was utilized to evaluate integrative pathways. Data analysis was conducted using R and Limma.

RESULTS

Samples were segregated based on their proteomic profiles with respect to their CMV Dnaemia status. A subset of 17 plasma proteins was observed to predict the onset of CMV at 3 months post-transplant enriching platelet degranulation (FDR, 4.83E-06), acute inflammatory response (FDR, 0.0018), blood coagulation (FDR, 0.0018) pathways. An increase in many immune complex proteins were observed at CMV infection. Prior to DNAemia the plasma proteome showed changes in the anti-inflammatory adipokine vaspin (SERPINA12), copper binding protein ceruloplasmin (CP), complement activation (FDR = 0.03), and proteins enriched in the humoral (FDR = 0.01) and innate immune responses (FDR = 0.01).

CONCLUSION

Plasma proteomic and transcriptional perturbations impacting humoral and innate immune pathways are observed during CMV infection and provide biomarkers for CMV disease prediction and resolution. Further studies to understand the clinical impact of these pathways can help in the formulation of different types and duration of anti-viral therapies for the management of CMV infection in the immunocompromised host.

Transcriptional responses define dysregulated immune activation in Hepatitis C (HCV)-naïve recipients of HCV-infected donor kidneys

Renal transplantation from hepatitis C (HCV) nucleic acid amplification test-positive (NAAT-positive) donors to uninfected recipients has greatly increased the organ donation pool. However, there is concern for adverse outcomes in these recipients due to dysregulated immunologic activation secondary to active inflammation from acute viremia at the time of transplantation. This includes increased rates of cytomegalovirus (CMV) DNAemia and allograft rejection. In this study, we evaluate transcriptional responses in circulating leukocytes to define the character, timing, and resolution of this immune dysregulation and assess for biomarkers of adverse outcomes in transplant patients. We enrolled 67 renal transplant recipients (30 controls, 37 HCV recipients) and performed RNA sequencing on serial samples from one, 3-, and 6-months post-transplant. CMV DNAemia and allograft rejection outcomes were measured. Least absolute shrinkage and selection operator was utilized to develop gene expression classifiers predictive of clinical outcomes. Acute HCV incited a marked transcriptomic response in circulating leukocytes of renal transplant recipients in the acute post-transplant setting, despite the presence of immunosuppression, with 109 genes significantly differentially expressed compared to controls. These HCV infection-associated genes were reflective of antiviral immune pathways and generally resolved by the 3-month timepoint after sustained viral response (SVR) for HCV. Differential gene expression was also noted from patients who developed CMV DNAemia or allograft rejection compared to those who did not, although transcriptomic classifiers could not accurately predict these outcomes, likely due to sample size and variable time-to-event. Acute HCV infection incites evidence of immune activation and canonical antiviral responses in the human host even in the presence of systemic immunosuppression. After treatment of HCV with antiviral therapy and subsequent aviremia, this immune activation resolves. Changes in gene expression patterns in circulating leukocytes are associated with some clinical outcomes, although larger studies are needed to develop accurate predictive classifiers of these events.

Low dose thymoglobulin versus basiliximab in cytomegalovirus positive kidney transplant recipients: Effectiveness of preemptive cytomegalovirus modified strategy

BACKGROUND

We performed a retrospective trial to determine asymptomatic CMV reactivation and CMV disease in kidney allograft recipients with positive CMV serostatus.

METHODS

Preemptive modified strategy under low dose thymoglobulin versus basiliximab induction was evaluated. Patients were monitored by CMV-polymerase chain reaction (PCR); if the viral load was >4000copies/μl, they received valganciclovir adjusted for their renal function.

RESULTS

132 recipients were included in the study, 84 and 48 receiving basiliximab and thymoglobulin induction respectively, and followed up for 12 months. Asymptomatic CMV reactivation was significantly higher for thymoglobulin (77.1% vs. 16.7%, p<0.001). Treatment groups had similar rates of CMV disease (3.6% vs. 2.1%, p 0.538). The significant difference in asymptomatic CMV reactivation between two treatment groups did not have any impact on 1 year graft function (71±26ml/min vs. 74±19ml/min; p=0.475) and no histological differences in protocol biopsies were observed among patients with asymptomatic CMV reactivation vs those without CMV reactivation.

CONCLUSIONS

Due to the high asymptomatic CMV reactivation incidence in patients who received thymoglobulin induction, our results suggest that valganciclovir prophylaxis may be advantageous in CMV seropositive renal transplant recipients after low dose thymoglobulin induction. A preemptive strategy appeared to significantly reduce the likelihood of CMV disease in both groups. Rejection risk and negative impact in renal function associated with asymptomatic CMV reactivation was not found in our series.

Outcomes of Everolimus Plus Standard-Dose Tacrolimus Immunosuppression in De Novo Kidney Transplant: A Retrospective, Single-Center Study of 225 Transplants

OBJECTIVES

In this study, our aim was to compare the outcomes of everolimus versus mycophenolate mofetil plus standard-dose tacrolimus immunosuppression in patients who received de novo kidney transplant at our center in Fukuoka, Japan.

MATERIALS AND METHODS

In this retrospective, observational, single-center, inverse probability of treatment weighting analysis study, 225 recipients who underwent kidney transplant at our center between January 2013 and December 2018 were included. The variables considered were recipient age/sex, duration of dialysis, cytomegalovirus mismatch (seronegative recipient and seropositive donor), cause of end-stage renal disease, donor age/sex, and number of HLA mismatches.

RESULTS

Our analyses included 85 transplant recipients in the everolimus group and 141 transplant recipients in the mycophenolate mofetil group (n = 226 overall). There were no significant differences between the groups at 1 year for incidence of patient death and allograft loss, biopsy-proven acute rejection, BK virus-associated nephropathy, surgical complications, delayed graft function, and posttransplant diabetes mellitus. Incidence of cytomegalovirus infection and estimated glomerular filtration rate were significantly lower in the everolimus group than in the mycophenolate mofetil group. Posttransplant triglyceride and low-density lipoprotein were higher in the everolimus group than in the mycophenolate mofetil group. Multivariate ordered logistic analysis showed that older donor age and an acute rejection episode, but not induction with everolimus or mean tacrolimus trough concentration throughoutthe firstpostoperative year,were significant risk factors for severity of interstitial fibrosis/tubular atrophy at the 1-year protocol biopsy (P = .004 and P < .001,respectively).

CONCLUSIONS

Short-term outcomes with everolimus plus standard-dose tacrolimus in recipients of de novo kidney transplant were comparable to those with mycophenolate mofetil plus standard-dose tacrolimus.

Effects of antirejection therapies for early subclinical acute rejection in renal transplant protocol biopsies

Background

Although recently strengthened immunosuppression protocols have decreased the incidence of clinical acute rejection of renal transplants, subclinical acute rejection and borderline changes remain problematic. This study was performed to evaluate the effects of antirejection therapies for early subclinical acute rejection and borderline changes.

Methods

In total, 269 renal transplant patients who received 3-month and 1-year protocol biopsies after renal transplantation were enrolled this study and divided into those with normal findings (Group A) and those with ≥ borderline changes (Group B) according to the 3-month pathological results. Pathological changes, graft function, and graft survival were evaluated at 1 year.

Results

The 3-month protocol biopsy revealed normal findings in 166 patients (Group A) and borderline changes and subclinical acute rejection in 103 patients (Group B). In Group A, 65.1% (n = 108) of the patients maintained normal findings at 1 year, while 30.1% (n = 50) deteriorated to ≥ borderline changes. In Group B, 52.4% (n = 54) of patients improved to normal. Among patients with subclinical acute rejection, 25.0% (n = 5) maintained subclinical acute rejection at 1 year despite antirejection therapy. The mean estimated glomerular filtration rate decreased from 60.4 ± 24.5 to 58.3 ± 19.0 mL/min/1.73 m2 in Group A and from 57.2 ± 28.2 to 53.7 ± 20.3 mL/min/1.73 m2 in Group B (p = 0.417). The 3-, 5-, and 7-year graft survival rates were 99.4%, 99.4%, and 97.6% in Group A and 100.0%, 98.6%, and 98.6% in Group B, respectively (p = 0.709).

Conclusions

Subclinical acute rejection is likely to recur. However, intervention for subclinical acute rejection in the early period after transplantation may help to prevent subsequent histological changes.

Deletion of the Natural Killer Cell Receptor NKG2C Encoding KLR2C Gene and Kidney Transplant Outcome

Natural killer (NK) cells may contribute to antibody-mediated rejection (ABMR) of renal allografts. The role of distinct NK cell subsets in this specific context, such as NK cells expressing the activating receptor NKG2C, is unknown. Our aim was to investigate whether KLRC2 gene deletion variants which determine NKG2C expression affect the pathogenicity of donor-specific antibodies (DSA) and, if so, influence long-term graft survival. We genotyped the KLRC2^wt/del variants for two distinct kidney transplant cohorts, (i) a cross-sectional cohort of 86 recipients who, on the basis of a positive post-transplant DSA result, all underwent allograft biopsies, and (ii) 1,860 recipients of a deceased donor renal allograft randomly selected from the Collaborative Transplant Study (CTS) database. In the DSA+ patient cohort, KLRC2^wt/wt (80%) was associated with antibody-mediated rejection (ABMR; 65% versus 29% among KLRC2^wt/del subjects; P=0.012), microvascular inflammation [MVI; median g+ptc score: 2 (interquartile range: 0-4) versus 0 (0-1), P=0.002], a molecular classifier of ABMR [0.41 (0.14-0.72) versus 0.10 (0.07-0.27), P=0.001], and elevated NK cell-related transcripts (P=0.017). In combined analyses of KLRC2 variants and a functional polymorphism in the Fc gamma receptor IIIA gene (FCGR3A-V/F158), ABMR rates and activity gradually increased with the number of risk genotypes. In DSA+ and CTS cohorts, however, the KLRC2^wt/wt variant did not impact long-term death-censored graft survival, also when combined with the FCGR3A-V158 risk variant. KLRC2^wt/wt may be associated with DSA-triggered MVI and ABMR-associated gene expression patterns, but the findings observed in a highly selected cohort of DSA+ patients did not translate into meaningful graft survival differences in a large multicenter kidney transplant cohort not selected for HLA sensitization.

Associations of high anti-CMV IgG titer with renal function decline and allograft rejection in kidney transplant patients

BACKGROUND

An anti-cytomegalovirus (CMV) immunoglobulin G (IgG) antibody is produced after primary CMV infection and generally persists after the primary infection. However, it is not well-known about the relationship between anti-CMV IgG titer and outcomes in kidney transplant recipients. We, therefore, aimed to explore the role of anti-CMV IgG titer on the risks of CMV disease development, allograft rejection, renal function decline, and mortality.

METHODS

In a hospital-based study, we identified 179 CMV-seropositive kidney transplant recipients between January 2013 and December 2017. These patients were divided into low and high anti-CMV IgG titer groups, respectively. The cutoff level of anti-CMV IgG titer was determined by receiver operating characteristic curve analysis. The outcomes evaluated included CMV disease, decrease of ≥15% in estimated glomerular filtration rate (eGFR), biopsy-proven allograft rejection, and all-cause mortality.

RESULTS

The high anti-CMV IgG titer group (≥846.2 AU/mL) exhibited a higher risk of CMV disease (adjusted hazard ratio [aHR], 3.77; 95% CI, 1.47-9.68; p = 0.006), eGFR decline ≥15% (aHR, 2.00; 95% CI, 1.19-3.35; p = 0.009), and renal allograft rejection (aHR, 2.95; 95% CI, 1.11-7.87; p = 0.030) than the low titer group (<846.2 AU/mL).

CONCLUSION

In kidney transplant recipients, a high anti-CMV IgG titer was associated with higher risks for developing CMV disease, undergoing allograft rejection, and eGFR decline.

Occurrence of de novo Donor Specific Antibodies after Covid-19 in kidney transplant recipients is low despite immunosuppression modulation

Introduction

Methods

Results

Conclusion

Cytomegalovirus Exposure and the Risk of Overall Infection After Kidney Transplantation: A Cohort Study on the Indirect Effects Attributable to Viral Replication

Previous reports hypothesized that cytomegalovirus (CMV) may predispose to non-CMV infection after kidney transplantation (KT). We analysed the incidence of non-CMV infection (overall, bacterial and opportunistic) in 291 KT recipients according to the previous development of any level or high-level (≥1,000 IU/ml) CMV viremia. Exposure to CMV replication was assessed throughout fixed intervals covering first the 30, 90, 180 and 360 post-transplant days (cumulative exposure) and non-overlapping preceding periods (recent exposure). Adjusted Cox models were constructed for each landmark analysis. Overall, 67.7 and 50.5% patients experienced non-CMV and CMV infection, respectively. Patients with cumulative CMV exposure had higher incidence of non-CMV infection beyond days 30 (p-value = 0.002) and 90 (p-value = 0.068), although these associations did not remain after multivariable adjustment. No significant associations were observed for the remaining landmark models (including those based on high-level viremia or recent CMV exposure), or when bacterial and opportunistic infection were separately analysed. There were no differences in viral kinetics (peak CMV viremia and area under curve of CMV viral load) either. Our findings do not support the existence of an independent association between previous CMV exposure and the overall risk of post-transplant infection, although results might be affected by power limitations.

Cytomegalovirus infection after renal transplantation

Renal transplant patients show a high prevalence of cytomegalovirus (CMV) infection after the procedure. This study was conducted to assess the prevalence and factors associated with the incidence of CMV infection among renal transplant patients. A total of 100 patients were recruited in this study. The CMV load in the blood of each patient was assessed using the technique of polymerase chain reaction (PCR). The serostatus of all recipients and donors was examined preoperatively and those of the recipients again postoperatively. The association of CMV load was assessed with the following factors: age, gender, alanine aminotransferase (ALT) and serum creatinine levels, types of immunosuppressive and induction regimens, preoperative diabetes status, and serological virologic response (SVR) at 12 weeks postoperatively. Our findings showed that CMV incidence was significantly higher in middle-aged patients (62 of 66 patients, 93.9%; p=0.0001). Furthermore, about 88.2% of patients induced by anti-thymocyte globulin (ATG) showed a high viral load, significantly higher than the proportion of CMV-positive patients induced by basiliximab (p=0.001). In addition, a higher proportion of CMV-negative recipients who received the graft from CMV-positive donors and vice-versa were CMV-positive postoperatively. Administration of Valcyte 450 showed 100% efficiency in decreasing the CMV load in the patients. Among all the assessed factors, only the age of the recipients, type of induction therapy used, and the preoperative serostatus of both donors and recipients were significantly associated with the postoperative CMV incidence among the patients.

Efficacy and safety of conventional antiviral agents in preventive strategies for cytomegalovirus infection after kidney transplantation: a systematic review and network meta-analysis

Cytomegalovirus (CMV) infection is common in kidney transplantation (KT). Antiviral-agents are used as universal prophylaxis. Our purpose aimed to compare and rank efficacy and safety. MEDLINE, Embase, SCOPUS, and CENTRAL were used from inception to September 2020 regardless language restriction. We included randomized clinical trials (RCTs) comparing the CMV infection/disease prophylaxis among antiviral-agents in adult KT recipients. Of 24 eligible RCTs, prophylactic valganciclovir (VGC) could significantly lower the overall CMV infection and disease risks than placebo with pooled risk differences (RDs) [95% confidence interval (CI)] of -0.36 (-0.54, -0.18) and -0.28 (-0.48, -0.08), respectively. Valacyclovir (VAC) and ganciclovir (GC) significantly decreased risks with the corresponding RDs of -0.25 (-0.32, -0.19) and -0.30 (-0.37, -0.22) for CMV infection and -0.26 (-0.40, -0.12) and -0.22 (-0.31, -0.12) for CMV disease. For subgroup analysis by seropositive-donor and seronegative-recipient (D+/R-), VGC and GC significantly lowered the risk of CMV infection/disease with RDs of -0.42 (-0.84, -0.01) and -0.35 (-0.60, -0.12). For pre-emptive strategies, GC lowered the incidence of CMV disease significantly with pooled RDs of -0.33 (-0.47, -0.19). VGC may be the best in prophylaxis of CMV infection/disease follow by GC. VAC might be an alternative where VGC and GC are not available.

Cytomegalovirus nephritis in kidney transplant recipients: Epidemiology and outcomes of an uncommon diagnosis

BACKGROUND

Data on epidemiology and outcomes of cytomegalovirus (CMV) nephritis in kidney transplant patients are limited due to the rarity of this condition.

METHODS

A retrospective review of all kidney transplant recipients (KTR) (n = 6490) and biopsy-proven CMV nephritis between 1/1997 and 12/2020 was performed.

RESULTS

The prevalence of CMV nephritis was low: 13/6490 (0.2%). The diagnosis was made at a median of 7.0 months (range 2.6-15.6 months) after transplant. 6 of 13 (46%) patients were CMV (D+/R-). Median CMV DNA load at biopsy was 376,000, IU/mL (range 87,000-6,460,000 IU/mL). Main biopsy features were CMV glomerulitis (n = 7/13, 54%) followed by CMV tubulointerstitial nephritis (6/13; 46%). Mean eGFR at biopsy (22.7 ± 12 mL/min/1.73 m² ) was significantly decreased compared to baseline eGFR (38.7 ± 18.5 mL/min/1.73 m² , p = 0.02). The vast majority, 11 of 13 (85%), experienced graft failure including 5 of 13 (38%) death-censored. 5 of 13 (38%) patients were diagnosed with acute rejection: three had concurrent acute rejection, and two had rejection within 3 months of index biopsy, respectively. Patients with tubulointerstitial CMV nephritis were significantly more likely to have rejection at the time of biopsy (50% vs. 0%, p < 0.05) compared to those with glomerular CMV nephritis. There were no significant differences between these groups in terms of eGFR at all time points, death, graft failure, immunosuppression changes or rejection after biopsy.

CONCLUSION

CMV nephritis is rare but appears to be associated with poor patient/allograft outcomes. Early identification and timely treatment of CMV infection may prevent end-organ involvement and improve patient and allograft-related outcomes.

Donor and Recipient Matching in Facial Vascularized Composite Allotransplantation: A Closer Look at the Donor Pool

BACKGROUND

Identifying a donor for facial vascularized composite allotransplant recipients can be a lengthy, emotionally challenging process. Little is known about the relative distribution of key donor characteristics among potential donors. Data on actual wait times of patients are limited, making it difficult to estimate wait times for future recipients.

METHODS

The authors retrospectively reviewed charts of nine facial vascularized composite allotransplant patients and provide data on transplant wait times and patient characteristics. In addition, they analyzed the United Network for Organ Sharing database of dead organ donors. After excluding donors with high-risk characteristics (e.g., active cancer or risk factors for blood-borne disease transmission), the authors calculated the distribution of relevant donor-recipient matching criteria (i.e., ethnicity, body mass index, age, ABO blood group, cytomegalovirus, Epstein-Barr virus, hepatitis C virus) among 65,201 potential donors.

RESULTS

The median wait time for a transplant was 4 months (range, 1 day to 17 months). The large majority of United Network for Organ Sharing-recorded deaths from disease were white (63 percent) and male (58 percent). Female donors of black, Hispanic, or Asian descent are underrepresented, with 7, 5, and 1 percent of all recorded deaths from disease, respectively. Potential donors show cytomegalovirus and Epstein-Barr virus seropositivity of 65 and 95 percent, respectively. The number of annual hepatitis C-positive donors increased over time.

CONCLUSIONS

Actual facial vascularized composite allotransplant wait times vary considerably. Although most patients experience acceptable wait times, some with underrepresented characteristics exceed acceptable levels. Cytomegalovirus-seropositive donors present a large portion of the donor pool, and exclusion for seronegative patients may increase wait time. Hepatitis C-seropositive donors may constitute a donor pool for underrepresented patient groups in the future.

Cellular Immunity to Predict the Risk of Cytomegalovirus Infection in Kidney Transplantation: A Prospective, Interventional, Multicenter Clinical Trial

BACKGROUND

Improving cytomegalovirus (CMV) immune-risk stratification in kidney transplantation is highly needed to establish guided preventive strategies.

METHODS

This prospective, interventional, multicenter clinical trial assessed the value of monitoring pretransplant CMV-specific cell-mediated immunity (CMI) using an interferon-γ release assay to predict CMV infection in kidney transplantation. One hundred sixty donor/recipient CMV-seropositive (D+/R+) patients, stratified by their baseline CMV (immediate-early protein 1)-specific CMI risk, were randomized to receive either preemptive or 3-month antiviral prophylaxis. Also, 15-day posttransplant CMI risk stratification and CMI specific to the 65 kDa phosphoprotein (pp65) CMV antigen were investigated. Immunosuppression consisted of basiliximab, tacrolimus, mycophenolate mofetil, and corticosteroids in 80% of patients, whereas 20% received thymoglobulin induction therapy.

RESULTS

Patients at high risk for CMV based on pretransplant CMI developed significantly higher CMV infection rates than those deemed to be at low risk with both preemptive (73.3% vs 44.4%; odds ratio [OR], 3.44 [95% confidence interval {CI}, 1.30-9.08]) and prophylaxis (33.3% vs 4.1%; OR, 11.75 [95% CI, 2.31-59.71]) approaches. The predictive capacity for CMV-specific CMI was only found in basiliximab-treated patients for both preemptive and prophylaxis therapy. Fifteen-day CMI risk stratification better predicted CMV infection (81.3% vs 9.1%; OR, 43.33 [95% CI, 7.89-237.96]).

CONCLUSIONS

Pretransplant CMV-specific CMI identifies D+/R+ kidney recipients at high risk of developing CMV infection if not receiving T-cell-depleting antibodies. Monitoring CMV-specific CMI soon after transplantation further defines the CMV infection prediction risk. Monitoring CMV-specific CMI may guide decision making regarding the type of CMV preventive strategy in kidney transplantation.

CLINICAL TRIALS REGISTRATION

NCT02550639.

Apoptotic Donor Cells in Transplantation

Despite significant advances in prevention and treatment of transplant rejection with immunosuppressive medications, we continue to face challenges of long-term graft survival, detrimental medication side effects to both the recipient and transplanted organ together with risks for opportunistic infections. Transplantation tolerance has so far only been achieved through hematopoietic chimerism, which carries with it a serious and life-threatening risk of graft versus host disease, along with variability in persistence of chimerism and uncertainty of sustained tolerance. More recently, numerous in vitro and in vivo studies have explored the therapeutic potential of silent clearance of apoptotic cells which have been well known to aid in maintaining peripheral tolerance to self. Apoptotic cells from a donor not only have the ability of down regulating the immune response, but also are a way of providing donor antigens to recipient antigen-presenting-cells that can then promote donor-specific peripheral tolerance. Herein, we review both laboratory and clinical evidence that support the utility of apoptotic cell-based therapies in prevention and treatment of graft versus host disease and transplant rejection along with induction of donor-specific tolerance in solid organ transplantation. We have highlighted the potential limitations and challenges of this apoptotic donor cell-based therapy together with ongoing advancements and attempts made to overcome them.

Among CMV-positive renal transplant patients receiving non-T-cell depleting induction, the absence of CMV disease prevention is a safe strategy: A retrospective cohort of 372 patients

Cytomegalovirus (CMV) is the most common opportunistic pathogen affecting renal transplant recipients, especially in the first months. CMV-seropositive renal transplant recipients (CMV R+) are at intermediate risk for CMV disease, but this risk is enhanced among CMV R+ receiving T-cell depleting induction, compared to CMV R+ receiving non-depleting induction. In this second group, data in favor of prophylactic antiviral treatment with valganciclovir to reduce CMV disease is sparse. In this retrospective and multicentric trial, we included 372 CMV R+ transplanted between January 2012 and April 2015 and receiving non-depleting induction. During the first year following transplantation, CMV disease occurred in 5/222 patients (2.25%) in the prophylaxis group and 9/150 (6%) in the no-prophylaxis group (difference +3.7; 95% CI: 0.5-8; P = .002 for non-inferiority). The incidence of allograft rejection and other infectious diseases was similar between the two groups. Graft and patient survival were similar at the end of follow-up. In conclusion, the absence of prophylaxis did not appear to have a deleterious effect for CMV diseases among CMV R+ receiving non-depleting induction.

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.

Impact and outcomes of primary cytomegalovirus disease in seronegative abdominal solid organ transplant recipients of cytomegalovirus unexposed donors (D-/R-)

BACKGROUND

Primary cytomegalovirus (CMV) disease in high-risk (D+/R-) abdominal solid organ transplant recipients (aSOTRs) is well described, however, little is known of primary CMV disease in low-risk (D-/R-) patients.

METHODS

Observational study of adult aSOTRs between 1/1/2009 and 9/1/2019 screened based on serostatus at transplant; D-/R- and D+/R- patients were included.

PRIMARY OBJECTIVE

Describe epidemiology of primary CMV in D-/R- aSOTRs.

SECONDARY OBJECTIVE

Compare infectious and transplant-related outcomes of primary CMV disease in the first 90 days (early CMV) between D-/R- and D+/R-.

RESULTS

Of 782 D-/R- aSOTRs in the study period, 13 developed CMV at any time after transplant to last follow-up. Of 671 D+/R- patients, 186 developed CMV. Early CMV disease was significantly more common in the D-/R- group (54% vs 15.6%, P = .0005) despite populations being similar demographically, including allograft subtype. D-/R- patients with early CMV disease had median viral load >100 000 IU/mL and 42.9% had end-organ manifestations; 71.4% required hospital admission. Immunosuppressive therapy was adjusted in 100% of patients, there was an approximately 14.3% rate of antiviral resistance and 28.6% had concomitant opportunistic infection. These findings were similar to D+/R- patients. There was no difference in risk of rejection or all-cause mortality associated with early CMV disease, however, graft loss was significantly higher in D-/R-.

CONCLUSION

D-/R- aSOTRs infrequently develop CMV, however, when it occurs, they present with disease manifestations similar to and graft outcomes inferior to D+/R- with CMV. Additionally, the majority of CMV disease in D-/R- occurs in the first 90 days after transplant, suggesting possible donor subclinical infection or transfusion source. The complicated course in D-/R- is likely caused by low clinical suspicion. Awareness of disease severity and aggressive upfront management may promote positive outcomes.

Association between cytomegalovirus infection and allograft rejection in a large contemporary cohort of heart transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection remains a common complication after heart transplantation (HTx). The association between CMV infection and allograft rejection is debated in the era of efficient prophylactic antiviral therapies.

METHODS

This single-center cohort study utilized a highly phenotyped database of HTx recipients (2012-2016). The primary endpoint was the analysis of the association between CMV infection (CMV load ≥ 500 IU/mL whole blood) and the risk of allograft rejection (cellular rejection ≥ 1R1B, antibody-mediated rejection ≥ pAMR1). Secondary endpoints included the analysis of a higher CMV load threshold (≥10 000 IU/mL) and different risk periods after PCR positivity. A mixed-effect logistic regression model with a random intercept was applied. Results were adjusted for important risk factors of rejection.

RESULTS

Overall, 384 patients were included and 6388 CMV loads and 3,494 endomyocardial biopsies were analyzed. CMV infections ≥ 500 IU/mL were diagnosed on 1223 (19.2%) blood samples from 284 (72.1%) patients and allograft rejections on 246 biopsies (7%) from 149 patients (38.8%). We did not find any association between CMV infection ≥ 500 IU/mL and rejection (univariable: OR 0.94, 95% CI [0.61, 1.45], P = .78, multivariable: OR 0.86, 95% CI [0.55, 1.33], P = .85). These results were consistent when analyzing a higher CMV load threshold and different periods of risk, reinforced by internal validation procedures and a posteriori calculation of the power (primary endpoint: power = 0.82, 95% CI [0.79-0.84]) and reproducible across different clinical scenarios.

CONCLUSIONS

CMV infection was not associated with an increased risk of rejection in a contemporary cohort of HTx recipients.

Post-transplant absolute lymphocyte count predicts early cytomegalovirus infection after heart transplantation

Immunosuppressive therapy can decrease rejection episodes and increase the risk of severe and fatal infections in heart transplantation (HT) recipients. Immunosuppressive therapy can also decrease the absolute lymphocyte count (ALC), but the relationship between early post-transplant ALC and early cytomegalovirus (CMV) infection is largely unknown, especially in HT. We retrospectively analyzed 58 HT recipients who tested positive for CMV IgG antibody and received basiliximab induction therapy. We collected preoperative and 2-month postoperative data on ALC and CMV load. The CMV load > 1200 IU/mL was used as the cutoff value to define early CMV infection. Post-transplant lymphopenia was defined as an ALC of < 500 cells/μL at postoperative day (POD) #7. On POD #7, 29 (50.0%) patients had post-transplant lymphopenia and 29 (50.0%) patients did not. The incidence of CMV infection within 1 or 2 months of HT was higher in the post-transplant lymphopenia group than in the non-lymphopenia group (82.8% vs. 48.3%, P = 0.013; 89.7% vs. 65.5%, P = 0.028, respectively). ALC < 500 cells/μL on POD #7 was an independent risk factor for early CMV infection within 1 month of HT (odds ratio, 4.14; 95% confidence interval, 1.16-14.77; P = 0.029). A low ALC after HT was associated with a high risk of early CMV infection. Post-transplant ALC monitoring is simple and inexpensive and can help identify patients at high risk of early CMV infection.

Progress and Challenges in the Prevention, Diagnosis, and Management of Cytomegalovirus Infection in Transplantation

Hosts with compromised or naive immune systems, such as individuals living with HIV/AIDS, transplant recipients, and fetuses, are at the highest risk for complications from cytomegalovirus (CMV) infection. Despite substantial progress in prevention, diagnostics, and treatment, CMV continues to negatively impact both solid-organ transplant (SOT) and hematologic cell transplant (HCT) recipients. In this article, we summarize important developments in the field over the past 10 years and highlight new approaches and remaining challenges to the optimal control of CMV infection and disease in transplant settings.

Population Pharmacokinetics and Bayesian Estimation of the Area Under the Concentration-Time Curve for Ganciclovir in Adult Chinese Renal Allograft Recipients After Valganciclovir Administration

Valganciclovir (VGCV) is the prodrug of ganciclovir (GCV). The objective of this study was to establish a population pharmacokinetic model (PPK) of GCV to investigate the PK characteristics of GCV after administration of VGCV in adult Chinese renal allograft recipients. Seventy Chinese renal allograft recipients were given 450 mg (n = 41) or 900 mg (n = 29) VGCV daily. Blood samples were drawn 0-24 hours after 5 days' therapy, and GCV plasma levels were determined. The PPK model was constructed using nonlinear mixed-effects modeling, and the Bayesian estimation of AUC_0-24h was constructed for an individual patient based on limited plasma samples. The PK of GCV was best described by a 2-compartment model with a first-order absorption process. The CL/F, V₂ /F, Q/F, V₃ /F, K_a , and lag time of GCV were 15.8 ± 0.71 L/h, 10.9 ± 2.38 L, 3.98 ± 0.40 L/h, 167 ± 44.0 L, 0.23 ± 0.0078 1/h, and 0.93 ± 0.017 hours, respectively. Clearance of creatinine was found to have a significant impact on the CL/F of GCV (P < .01). Sampling strategies consisted of plasma concentrations 0 and 2 and 0, 2, and 4 hours after VGCV administration were shown to be suitable for the estimation of the GCV AUC_0-24h . The PPK model was acceptable and can describe the PK of GCV in Chinese renal transplant patients administered VGCV. The AUC_0-24h of GCV in Chinese renal transplant patients can be calculated by a limited sampling strategy method.

MCMV Dissemination from Latently-Infected Allografts Following Transplantation into Pre-Tolerized Recipients

Transplantation tolerance is achieved when recipients are unresponsive to donor alloantigen yet mobilize against third-party antigens, including virus. After transplantation, cytomegalovirus (CMV) reactivation in latently-infected transplants reduces allograft viability. To determine if pre-tolerized recipients are resistant to viral dissemination in this setting, we transfused chemically-fixed donor splenocytes (1-ethyl-3- (3′-dimethyl-aminopropyl)-carbo-diimide (ECDI)-treated splenocytes (ECDIsp)) to induce donor antigen tolerance without immunosuppression. In parallel, we implanted donor islet cells to validate operational tolerance. These pre-tolerized recipients were implanted with murine CMV (MCMV) latently-infected donor kidneys (a validated model of CMV latency) to monitor graft inflammation and viral dissemination. Our results indicate that tolerance to donor islets was sustained in recipients after implantation of donor kidneys. In addition, kidney allografts implanted after ECDIsp and islet implantation exhibited low levels of fibrosis and tubulitis. In contrast, kidney cellular and innate immune infiltrates trended higher in the CMV group and exhibited increased markers of CD8⁺ T cell activation. Tolerance induction was unable to prevent increases in MCMV-specific CD8⁺ T cells or dissemination of viral IE-1 DNA. Our data suggest that latently-infected allografts are inherently more susceptible to inflammation that is associated with viral dissemination in pre-tolerized recipients. Thus, CMV latently-infected allografts require enhanced strategies to protect allograft integrity and viral spread.

Clinical consequences of primary CMV infection after renal transplantation: a case-control study

The impact of primary cytomegalovirus infection (pCMV) on renal allograft function and histology is controversial. We evaluated the influence on incidence of acute rejection, allograft loss, allograft function and interstitial fibrosis/tubular atrophy (IF/TA). Retrospective case-control study, recipients transplanted between 2000 and 2014. Risk of acute rejection and allograft loss for those who experienced pCMV infection compared with those who did not, within an exposure period of two months after transplantation. Besides, its influence on allograft function and histology at one to three years after transplantation. Of 113 recipients experienced pCMV infection, 306 remained CMV seronegative. pCMV infection in the exposure period could not be proven as increasing the risk for acute rejection [HR = 2.18 (95% CI 0.80-5.97) P = 0.13] or allograft loss [HR = 1.11 (95%CI 0.33-3.72) P = 0.87]. Combination of pCMV infection and acute rejection posed higher hazard for allograft loss than acute rejection alone [HR = 3.69 (95% CI 1.21-11.29) P = 0.02]. eGFR(MDRD) values did not significantly differ at years one [46 vs. 50], two [46 vs. 51] and three [46 vs. 52]. No association between pCMV infection and IF/TA could be demonstrated [OR = 2.15 (95%CI 0.73-6.29) P = 0.16]. pCMV infection was not proven to increase the risk for acute rejection or allograft loss. However, it increased the risk for rejection-associated allograft loss. In remaining functioning allografts, it was not significantly associated with decline in function nor with presence of IF/TA.

Cytomegalovirus myocarditis in solid organ transplant recipients: A case series and review of literature

Cytomegalovirus (CMV) is a DNA virus of the Herpesviridae family and is estimated to affect 15%-30% of high-risk solid organ transplant recipients. Typical manifestations of CMV end-organ disease in this population include colitis, esophagitis, and pneumonitis, and myocarditis is a rarely reported manifestation. We describe two cases of CMV myocarditis in solid organ transplant recipients and review the literature regarding previously published cases of CMV myocarditis.

The establishment of CMV antigen-specific enzyme-linked immunospot assay among Chinese: A pilot study

BACKGROUND

The prevalence of cytomegalovirus in China is high and the infection could result in disastrous consequences. Cellular immunity is the main mechanism for virus controlling. We explored the performance of cytomegalovirus antigen-specific enzyme-linked immunospot assay in patients with different infection states in endemic area.

METHODS

Twenty-eight patients with reliable results were included in statistical analysis. Peripheral blood mononuclear cells were extracted and were stimulated by cytomegalovirus phosphoprotein 65 or immediate early protein-1 antigen respectively. Spot forming cells (SFCs) were counted to evaluate the cellular immune response elicited by antigens.

RESULTS

Spots could be clearly displayed, and evenly dispersed with a clean background. The numbers of SFCs were 0 [0-0], 426 [210-601] and 230 [57-513] for uninfected individuals (n = 7), latently infected patients (n = 11) and actively infected patients (n = 10) respectively, which were statistically different. The number of SFCs stimulated by phosphoprotein 65 was significantly higher than that by immediate early protein-1.

CONCLUSIONS

The number of SFCs was significantly different among patients with different infection state. The stimulatory effect of phosphoprotein 65 was better than that of immediate early protein-1.

HLA-E Polymorphism Determines Susceptibility to BK Virus Nephropathy after Living-Donor Kidney Transplant

Human leukocyte antigen (HLA)-E is important for the regulation of anti-viral immunity. BK polyomavirus (BKPyV) reactivation after kidney transplant is a serious complication that can result in BKPyV-associated nephropathy (PyVAN) and subsequent allograft loss. To elucidate whether HLA-E polymorphisms influence BKPyV replication and nephropathy, we determined the HLA-E genotype of 278 living donor and recipient pairs. A total of 44 recipients suffered from BKPyV replication, and 11 of these developed PyVAN. Homozygosity of the recipients for the HLA-E*01:01 genotype was associated with the protection against PyVAN after transplant (p = 0.025, OR 0.09, CI [95%] 0.83-4.89). Considering the time course of the occurrence of nephropathy, recipients with PyVAN were more likely to carry the HLA-E*01:03 allelic variant than those without PyVAN (Kaplan-Meier analysis p = 0.03; OR = 4.25; CI (95%) 1.11-16.23). Our findings suggest that a predisposition based on a defined HLA-E genotype is associated with an increased susceptibility to develop PyVAN. Thus, assessing HLA-E polymorphisms may enable physicians to identify patients being at an increased risk of this viral complication.

CMV-specific Cell-mediated Immunity at 3-month Prophylaxis Withdrawal Discriminates D+/R+ Kidney Transplants at Risk of Late-onset CMV Infection Regardless the Type of Induction Therapy

BACKGROUND

Whether cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) at prophylaxis cessation predicts D+/R+ kidney transplants at risk of late-onset CMV infection after receiving distinct induction therapies is still not well characterized.

METHODS

We prospectively assessed CMV-specific CMI predicting late-onset CMV infection at prophylaxis withdrawal and at earlier time-points, in 96 consecutive D+/R+ patients receiving either anti-interleukin 2-receptor antibody (anti-IL2RA; n = 50) or rabbit antithymoglobulin (n = 46). CMV-specific CMI was evaluated against CMV antigens (IE-1, pp65) using an IFN-γ ELISpot assay.

RESULTS

Fourteen (14.6%) of 96 patients developed late-onset CMV infection and 2 (2.1%) of 96 displayed disease. At 3 months, CMV-specific CMI frequencies were significantly lower in patients developing late-onset CMV infection (P < 0.001 for IE-1, P = 0.030 for pp65), regardless the type of induction therapy. Receiver operating characteristic curve analyses showed accurate CMV-specific CMI cutoffs (25 and 130 IFN-γ spots for IE-1 and pp65, respectively) classifying patients into high risk, intermediate risk, or low risk (log-rank = 0.006; hazard ratio, 4.084; 95% confidence interval, 1.431-11.651; P = 0.009), being IE-1 CMI the strongest predictor (odds ratio, 5.554; 95% confidence interval, 1.486-20.766; P = 0.011). Although the profound posttransplant CMV-specific CMI inhibition among rabbit antithymocyte globulin-treated patients precludes its use for risk stratification both before and early after kidney transplant, a similar proportion of at-risk patients could be identified before month 3 within anti-interleukin 2-receptor antibody-treated patients.

CONCLUSIONS

Monitoring CMV-specific CMI at 3-month prophylaxis cessation discriminates kidney transplant recipient at risk of late-onset CMV infection, regardless the type of induction therapy.

Human Vascular Pericytes and Cytomegalovirus Pathobiology

Pericytes are multipotent cells of the vascular system with cytoplasmic extensions proximal to endothelial cells that occur along the abluminal surface of the endothelium. The interactions between endothelial cells and pericytes are essential for proper microvascular formation, development, stabilization, and maintenance. Pericytes are essential for the regulation of paracellular flow between cells, transendothelial fluid transport, angiogenesis, and vascular immunosurveillance. They also influence the chemical composition of the surrounding microenvironment to protect endothelial cells from potential harm. Dysregulation or loss of pericyte function can result in microvascular instability and pathological consequences. Human pericytes have been shown to be targets for human cytomegalovirus (HCMV) infection and lytic replication that likely contribute to vascular inflammation. This review focuses on human vascular pericytes and their permissiveness for HCMV infection. It also discusses their implication in pathogenesis in the blood⁻brain barrier (BBB), the inner blood⁻retinal barrier (IBRB), the placenta⁻blood barrier, and the renal glomerulus as well as their potential role in subclinical vascular disease.

Usefulness of valacyclovir prophylaxis for cytomegalovirus infection after anti-thymocyte globulin as rejection therapy

BACKGROUND/AIMS

Anti-thymocyte globulin (ATG) treatment for acute T-cell mediated rejection (TCMR) can increase the risk of cytomegalovirus (CMV) infection. We aimed to evaluate the effect of valacyclovir prophylaxis against CMV infection after ATG administration as anti-rejection therapy.

METHODS

We retrospectively analyzed 55 kidney transplant recipients (KTRs) receiving ATG for steroid resistant TCMR. In all KTRs, we used intravenous ganciclovir during ATG injection. In 34 KTRs treated before July 2013, we performed preemptive therapy for CMV infection after ATG therapy. They were regarded as the historic control group (CONT). After July 2013, we used valacyclovir maintenance for 1 month after ATG therapy in 21 patients (VAL). The primary outcome was the incidence of CMV infection, and the secondary outcomes were subsequent acute rejection, and graft and patient outcome.

RESULTS

Valacyclovir prophylaxis significantly reduced the incidence of CMV infection (VAL, 9.6% vs. CONT, 67.6%; p < 0.001), and CMV-free survival rate was higher in the VAL group compared to the CONT group (p = 0.009). In the VAL group, two cases of CMV infection were limited to CMV viremia, but CMV disease or syndrome (n = 3) was detected in the CONT group. There was no difference in graft failure (CONT, 70.5% vs. VAL, 47.6%; p = 0.152), incidence of subsequent rejection after ATG treatment (CONT, 41.1% vs. VAL, 33.3%; p = 0.776), and graft or patient survival between the two groups. There were no major adverse events associated with valacyclovir prophylaxis.

CONCLUSION

In conclusion, valacyclovir prophylaxis is effective in the prevention of CMV infection after ATG treatment for steroid resistant TCMR.

Valganciclovir Prophylaxis Versus Preemptive Therapy in Cytomegalovirus-Positive Renal Allograft Recipients: Long-term Results After 7 Years of a Randomized Clinical Trial

BACKGROUND

The VIPP study compared valganciclovir prophylaxis with preemptive treatment regarding efficacy, safety, and long-term graft outcome in cytomegalovirus (CMV)-positive (R+) renal transplant recipients.

METHODS

Multicenter, open-label, randomized clinical study with a 12-month study phase and a follow-up of up to 84 months. Patients in the prophylaxis group received 2 × 450 mg/d oral valganciclovir for 100 days adjusted to renal function. Preemptive treatment with 2 × 900 mg/d valganciclovir was initiated at a viral load of 400 CMV copies/mL or greater (polymerase chain reaction) and maintained over ≥14 days, followed by secondary prophylaxis. Patients were stratified by donor CMV IgG serostatus (donor CMV IgG positive [D+]/R+, donor CMV IgG negative [D-]/R+).

RESULTS

The 12-month results were reported previously (Witzke et al Transplantation 2012). The intent-to-treat/safety population comprised 148 patients in the prophylaxis (61.5% D+/R+) and 151 patients in the preemptive group (52.3% D+/R+). Overall, 47% patients completed the follow-up. Significantly fewer patients in the prophylaxis compared with preemptive group experienced a CMV infection or disease up to month 84 (11.5%; 95% confidence interval [95% CI], 6.8-17.8%] vs 39.7%; 95% CI, 31.9-48.0%; P < 0.0001 and 4.7%; 95% CI, 1.9-9.5% vs 15.9%; 95% CI, 10.5-22.7%; P = 0.002). Incidences of graft loss (7.4% vs 8.6%), death (9.5% vs 11.3%), rejection (29.1% vs 28.5%), and renal function (estimated glomerular filtration rate [mean ± SD]: 58.2 ± 26.3 vs 59.9 ± 25.7 mL/min per 1.73 m) were not significantly different between prophylaxis and preemptive treatment. Tolerability was comparable between groups.

CONCLUSIONS

Prophylaxis was more effective than the preemptive approach, applying a low-intense surveillance protocol in preventing CMV infection and disease in intermediate-risk patients. Both strategies were similarly effective in preventing graft loss and death under the conditions of this long-term trial with a threshold of 400 copies/mL for initiation of anti-CMV treatment.