Role of mTOR inhibitors for the control of viral infection in solid organ transplant recipients

Tristetraprolin mediates immune evasion of mycobacterial infection in macrophages

Immune evasion of Mycobacterium tuberculosis (Mtb) facilitates intracellular bacterial growth. The mechanisms of immune evasion, however, are still not fully understood. In this study, we reveal that tristetraprolin (TTP), one of the best characterized RNA-binding proteins controlling the stability of targeted mRNAs, mediates innate immune evasion of mycobacteria. We found that TTP knockout mice displayed reduced bacterial burden in the early stage after Mtb aerosol challenge. Macrophages deficient in TTP also showed an inhibition in intracellular mycobacterial growth. Live mycobacteria induced TTP protein expression in macrophages, which was blocked by the mTOR inhibitor rapamycin. Rapamycin and AZD8055 specifically blocked 4EBP1 phosphorylation in infected macrophages and suppressed intracellular BCG growth. Rapamycin promoted TTP protein degradation through the ubiquitination pathway, whereas the proteasome inhibitor MG-132 blocked rapamycin function and thus stabilized TTP protein. TTP induction suppressed the expression of iNOS/TNF-α/IL-12/IL-23, and weakened protective immune responses in macrophages, whereas rapamycin enhanced the bactericidal effects through TTP inhibition. Moreover, blocking TTP binding increased the expression of TNF-α and iNOS and suppressed intracellular mycobacterial growth. Overall, our study reveals a novel role for RNA-binding protein TTP in Mtb immune evasion mechanisms and provides a potential target for host-directed therapy against tuberculosis (TB).

Prevention and management of cytomegalovirus infection and disease in kidney transplant: A consensus statement of the Transplantation Society of Taiwan

Kidney transplant recipients have an increased risk of cytomegalovirus (CMV) infection and disease. A strategy for mitigating the risk of CMV infection in kidney transplant recipients has not yet been established in Taiwan. The Transplantation Society of Taiwan aimed to develop a consensus by expert opinion on the prevention and management of CMV infection. Based on the results of Consensus Conference, we suggested low-dose valganciclovir prophylaxis (450 mg once daily) for kidney transplant recipients. The prophylaxis duration was ≥6 months for high-risk (D+/R-) patients and 3 months for moderate-risk (R+) patients. Even for low-risk (D-/R-) patients, prophylaxis for at least 3 months is recommended because of the high seroprevalence of CMV in Taiwan. CMV prophylaxis was suggested after anti-thymocyte globulin treatment but not after methylprednisolone pulse therapy. Routine surveillance after prophylaxis, secondary prophylaxis after CMV disease treatment, and mTOR inhibitors for primary CMV prophylaxis were not recommended. Letermovir and marabavir are emerging CMV agents used for prophylaxis and refractory CMV disease. CMV immunoglobulins have been used to treat refractory CMV disease in Taiwan. We hope this consensus will help professionals manage patients with CMV in Taiwan to improve the quality of care.

Prevention of Cytomegalovirus Infection in Solid Organ Transplant Recipients: Guidelines by the Korean Society of Infectious Diseases and the Korean Society for Transplantation

Cytomegalovirus (CMV) is the most important opportunistic viral pathogen in solid organ transplant (SOT) recipients. The Korean guideline for the prevention of CMV infection in SOT recipients was developed jointly by the Korean Society for Infectious Diseases and the Korean Society of Transplantation. CMV serostatus of both donors and recipients should be screened before transplantation to best assess the risk of CMV infection after SOT. Seronegative recipients receiving organs from seropositive donors face the highest risk, followed by seropositive recipients. Either antiviral prophylaxis or preemptive therapy can be used to prevent CMV infection. While both strategies have been demonstrated to prevent CMV infection post-transplant, each has its own advantages and disadvantages. CMV serostatus, transplant organ, other risk factors, and practical issues should be considered for the selection of preventive measures. There is no universal viral load threshold to guide treatment in preemptive therapy. Each institution should define and validate its own threshold. Valganciclovir is the favored agent for both prophylaxis and preemptive therapy. The evaluation of CMV-specific cell-mediated immunity and the monitoring of viral load kinetics are gaining interest, but there was insufficient evidence to issue recommendations. Specific considerations on pediatric transplant recipients are included.

Cellular Immunobiology and Molecular Mechanisms in Alloimmunity-Pathways of Immunosuppression

Current maintenance immunosuppression commonly comprises a synergistic combination of tacrolimus as calcineurin inhibitor (CNI), mycophenolic acid, and glucocorticoids. Therapy is often individualized by steroid withdrawal or addition of belatacept or inhibitors of the mechanistic target of rapamycin. This review provides a comprehensive overview of their mode of action, focusing on the cellular immune system. The main pharmacological action of CNIs is suppression of the interleukin-2 pathway that leads to inhibition of T cell activation. Mycophenolic acid inhibits the purine pathway and subsequently diminishes T and B cell proliferation but also exerts a variety of effects on almost all immune cells, including inhibition of plasma cell activity. Glucocorticoids exert complex regulation via genomic and nongenomic mechanisms, acting mainly by downregulating proinflammatory cytokine signatures and cell signaling. Belatacept is potent in inhibiting B/T cell interaction, preventing formation of antibodies; however, it lacks the potency of CNIs in preventing T cell-mediated rejections. Mechanistic target of rapamycin inhibitors have strong antiproliferative activity on all cell types interfering with multiple metabolic pathways, partly explaining poor tolerability, whereas their superior effector T cell function might explain their benefits in the case of viral infections. Over the past decades, clinical and experimental studies provided a good overview on the underlying mechanisms of immunosuppressants. However, more data are needed to delineate the interaction between innate and adaptive immunity to better achieve tolerance and control of rejection. A better and more comprehensive understanding of the mechanistic reasons for failure of immunosuppressants, including individual risk/benefit assessments, may permit improved patient stratification.

Human cytomegalovirus-related gastrointestinal disease after kidney transplantation: A systematic review

BACKGROUND

Human-cytomegalovirus (hCMV) infection involving the gastrointestinal tract represents a leading cause of morbidity and mortality among kidney transplant (KT) recipients (KTRs). Signs and symptoms of the disease are extremely variable. Prompt anti-viral therapy administration and immunosuppression modification are key factors for optimizing management. However, complex work-up strategies are generally required to confirm the preliminary diagnosis. Unfortunately, solid evidence and guidelines on this specific topic are not available. We consequently aimed to summarize current knowledge on post-KT hCMV-related gastrointestinal disease (hCMV-GID).

METHODS

We conducted a systematic review (PROSPERO ID: CRD42023399363) about hCMV-GID in KTRs.

RESULTS

Our systematic review includes 52 case-reports and ten case-series, published between 1985 and 2022, collectively reporting 311 cases. The most frequently reported signs and symptoms of hCMV-GID were abdominal pain, diarrhea, epigastric pain, vomiting, fever, and GI bleeding. Esophagogastroduodenoscopy and colonoscopy were the primary diagnostic techniques. In most cases, the preliminary diagnosis was confirmed by histology. Information on anti-viral prophylaxis were extremely limited as much as data on induction or maintenance immunosuppression. Treatment included ganciclovir and/or valganciclovir administration. Immunosuppression modification mainly consisted of mycophenolate mofetil or calcineurin inhibitor minimization and withdrawal. In total, 21 deaths were recorded. Renal allograft-related outcomes were described for 26 patients only. Specifically, reported events were acute kidney injury (n = 17), transplant failure (n = 5), allograft rejection (n = 4), and irreversible allograft dysfunction (n = 3).

CONCLUSIONS

The development of local and national registries is strongly recommended to improve our understanding of hCMV-GID. Future clinical guidelines should consider the implementation of dedicated diagnostic and treatment strategies.

Current Perspectives on the Management of Herpesvirus Infections in Solid Organ Transplant Recipients

Solid organ transplant recipients (SOTRs) are at high risk of human herpesvirus (HHV)-related morbidity and mortality due to the use of immunosuppressive therapy. We aim to increase awareness and understanding of HHV disease burden in SOTRs by providing an overview of current prevention and management strategies as described in the literature and guidelines. We discuss challenges in both prevention and treatment as well as future perspectives.

Combination of everolimus and low-dose tacrolimus controls histological liver allograft injury as sufficiently as high-dose tacrolimus

Introduction

The combination of everolimus (EVR) and low-dose tacrolimus (lowTAC) prevents T cell-mediated rejection of liver grafts as sufficiently as high-dose tacrolimus (highTAC) and mycophenolate, but is associated with a preserved kidney function within the first years after orthotopic liver transplantation (OLT). However, none of the available studies assessed the histological pattern of graft injury or fibrosis in surveillance biopsies (svLbx).

Methods

All svLbx taken under at least one month of stable immunosuppression with either EVR (aim 3-8 ng/ml) combined with lowTAC (aim 3-5 ng/ml) or highTAC (aim 5-8 ng/ml) combined with mycophenolate (500-1500 mg/day) within the first three to four years after OLT at our center were included. Patients who were switched to EVR because of insufficient control of alloreactivity were excluded.

Results

Reasons for switches to EVR were mainly malignancies before or after OLT, or chronic kidney injury. We were able to include 20 svLbx with EVR/lowTAC and 49 with highTAC/mycophenolate. Both groups had similar liver enzymes and similar kidney function. The EVR/lowTAC group exhibited lower TAC trough levels at svLbx (4.4 vs. 6.6 ng/ml; p<.001) in comparison to highTAC/mycophenolate. Histological graft injury quantified by the rejection activity index and hepatitis activity index (Ishak), as well as fibrosis were not significantly different between the EVR/lowTAC and highTAC/mycophenolate groups. Likewise, subclinical TCMR, histological criteria justifying immunosuppression minimization, and steatosis had equal prevalence in both regimens. Immunosuppression was adjusted according to the svLbx findings. Immunosuppression regimens had similarly low rates of rejection after immunosuppression reduction, when relevant graft injury was absent in the biopsy.

Discussion

In conclusion, EVR/lowTAC seems to control alloreactivity and histological graft injury as sufficiently as highTAC/mycophenolate within the first 3-4 years after OLT.

Everolimus Based Immunosuppression Strategies in Adult Lung Transplant Recipients: Calcineurin Inhibitor Minimization Versus Calcineurin Inhibitor Elimination

Everolimus (EVE) provides an alternative to maintenance immunosuppression when conventional immunosuppression cannot be tolerated. EVE can be utilized with a calcineurin inhibitor (CNI) minimization or elimination strategy. To date, clinical studies investigating EVE after lung transplant (LTx) have primarily focused on the minimization strategy to preserve renal function. The primary aim was to determine the preferred method of EVE utilization for lung transplant recipients (LTR). To undertake this aim, we compared the safety and efficacy outcomes of EVE as part of minimization and elimination immunosuppressant regimens. Single center retrospective study of 217 LTR initiated on EVE (120 CNI minimization and 97 CNI elimination). Survival outcomes were calculated from the date of EVE commencement. On multivariate analysis, LTR who received EVE as part of the CNI elimination strategy had poorer survival outcomes compared to the CNI minimization strategy [HR 1.61, 95% CI: 1.11-2.32, p=0.010]. Utilization of EVE for renal preservation was associated with improved survival compared to other indications [HR 0.64, 95% CI: 0.42-0.97, p=0.032]. EVE can be successfully utilized for maintenance immunosuppression post LTx, particularly for renal preservation. However, immunosuppressive regimens containing low dose CNI had superior survival outcomes, highlighting the importance of retaining a CNI wherever possible.

Rescue Everolimus Post Lung Transplantation is Not Associated With an Increased Incidence of CLAD or CLAD-Related Mortality

Everolimus (EVE) has been used as a calcineurin inhibitor (CNI) minimization/ elimination agent or to augment immunosuppression in lung transplant recipients (LTR) with CNI-induced nephrotoxicity or neurotoxicity. The long-term evidence for survival and progression to chronic lung allograft dysfunction (CLAD) is lacking. The primary aim was to compare survival outcomes of LTR starting EVE-based immunosuppression with those remaining on CNI-based regimens. The secondary outcomes being time to CLAD, incidence of CLAD and the emergence of obstructive (BOS) or restrictive (RAS) phenotypes. Single center retrospective study of 91 LTR starting EVE-based immunosuppression matched 1:1 with LTR remaining on CNI-based immunosuppression. On multivariate analysis, compared to those remaining on CNI-based immunosuppression, starting EVE was not associated with poorer survival [HR 1.04, 95% CI: 0.67-1.61, p = 0.853], or a statistically significant faster time to CLAD [HR 1.34, 95% CI: 0.87-2.04, p = 0.182]. There was no difference in the emergence of CLAD (EVE, [n = 57, 62.6%] vs. CNI-based [n = 52, 57.1%], p = 0.41), or the incidence of BOS (p = 0.60) or RAS (p = 0.16) between the two groups. Introduction of EVE-based immunosuppression does not increase the risk of death or accelerate the progression to CLAD compared to CNI-based immunosuppression.

Dengue activates mTORC2 signaling to counteract apoptosis and maximize viral replication

The mechanistic target of rapamycin (mTOR) functions in two distinct complexes: mTORC1, and mTORC2. mTORC1 has been implicated in the pathogenesis of flaviviruses including dengue, where it contributes to the establishment of a pro-viral autophagic state. Activation of mTORC2 occurs upon infection with some viruses, but its functional role in viral pathogenesis remains poorly understood. In this study, we explore the consequences of a physical protein-protein interaction between dengue non-structural protein 5 (NS5) and host cell mTOR proteins during infection. Using shRNA to differentially target mTORC1 and mTORC2 complexes, we show that mTORC2 is required for optimal dengue replication. Furthermore, we show that mTORC2 is activated during viral replication, and that mTORC2 counteracts virus-induced apoptosis, promoting the survival of infected cells. This work reveals a novel mechanism by which the dengue flavivirus can promote cell survival to maximize viral replication.

Real-World Treatment Patterns of Antiviral Prophylaxis for Cytomegalovirus Among Adult Kidney Transplant Recipients: A Linked USRDS-Medicare Database Study

Limited data exist on cytomegalovirus (CMV) antiviral treatment patterns among kidney transplant recipients (KTRs). Using United States Renal Database System registry data and Medicare claims (1 January 2011-31 December 2017), we examined CMV antiviral use in 22,878 KTRs who received their first KT from 2011 to 2016. Three-quarters of KTRs started CMV prophylaxis (85.8% of high-, 82.4% of intermediate-, and 32.1% of low-risk KTRs). Median time to prophylaxis discontinuation was 98, 65, and 61 days for high-, intermediate-, and low-risk KTRs, respectively. Factors associated with receiving CMV prophylaxis were high-risk status, diabetes, receipt of a well-functioning kidney graft, greater time on dialysis before KT, panel reactive antibodies ≥80%, and use of antithymocyte globulin, alemtuzumab, and tacrolimus. KTRs were more likely to discontinue CMV prophylaxis if they developed leukopenia/neutropenia, had cardiovascular disease, or received their kidney from a deceased donor. These findings suggest that adherence to the recommended duration of CMV-prophylaxis for high and intermediate-risk patients is suboptimal, and CMV prophylaxis is overused in low-risk patients.

In Vitro Study Evaluating the Effect of Different Immunosuppressive Agents on Human Polyomavirus BK Replication

BACKGROUND

Human polyomavirus BK (BKPyV) is the etiologic agent of polyomavirus-associated nephropathy, a leading cause of kidney transplant dysfunction. Because of the lack of antiviral therapies, immunosuppression minimization is the recommended treatment. This strategy offers suboptimal outcomes and entails a significant risk of rejection. Our aim was to evaluate the effect of different immunosuppressive drugs (leflunomide, tacrolimus, mycophenolic acid, sirolimus, and everolimus) and their combinations in an in vitro model of BKPyV infection.

METHODS

Human renal tubular epithelial cells were infected with BKPyV and treated with leflunomide, tacrolimus, mycophenolic acid, sirolimus, and everolimus, administered alone or in some combination thereof. Viral replication was assessed every 24 hours (up to 72 hours) by BKPyV-specific quantitative real-time polymerized chain reaction for the VIRAL PROTEIN 1 sequence in cell supernatants and by western blot analysis targeting the viral protein 1 and the glyceraldehyde 3-phosphate dehydrogenase on total protein lysates. Results were described as viral copies/mL and compared between treatments at any prespecified time point of the study.

RESULTS

The highest inhibitory effects were observed using leflunomide or everolimus plus mycophenolic acid (mean BKPyV replication log reduction 0.28). The antiviral effect of everolimus persisted when it was used in combination with tacrolimus (mean BKPyV replication log reduction 0.27).

CONCLUSIONS

Our experience confirms that everolimus has anti-BKPyV properties and prompts future research to investigate possible mechanisms of action. It also provides a rational basis for targeted clinical trials evaluating alternative immunosuppressive modification strategies.

Bacterial and Viral Infection and Sepsis in Kidney Transplanted Patients

Kidney transplanted patients are a unique population with intrinsic susceptibility to viral and bacterial infections, mainly (but not exclusively) due to continuous immunosuppression. In this setting, infectious episodes remain among the most important causes of death, with different risks according to the degree of immunosuppression, time after transplantation, type of infection, and patient conditions. Prevention, early diagnosis, and appropriate therapy are the goals of infective management, taking into account that some specific characteristics of transplanted patients may cause a delay (the absence of fever or inflammatory symptoms, the negativity of serological tests commonly adopted for the general population, or the atypical anatomical presentation depending on the surgical site and graft implantation). This review considers the recent available findings of the most common viral and bacterial infection in kidney transplanted patients and explores risk factors and outcomes in septic evolution.

Outcome and safety of a surveillance biopsy guided personalized immunosuppression program after liver transplantation

Graft survival beyond year 1 has not changed after orthotopic liver transplantation (OLT) over the last decades. Likewise, OLT causes comorbidities such as infection, renal impairment and cancer. We evaluated our single-center real-world individualized immunosuppression program after OLT, based on 211 baseline surveillance biopsies (svLbx) without any procedural complications. Patients were classified as low, intermediate and high rejection risk based on graft injury in svLbx and anti-HLA donor-specific antibodies. While 32% of patients had minimal histological inflammation, 57% showed histological inflammation and 23% advanced fibrosis (>F2), which was not predicted by lab parameters. IS was modified in 79% of patients after svLbx. After immunosuppression reduction in 69 patients, only 5 patients showed ALT elevations and three of these patients had a biopsy-proven acute rejection, two of them related to lethal comorbidities. The rate of liver enzyme elevation including rejection was not significantly increased compared to a svLbx control cohort prior to the initiation of our structured program. Immunosuppression reduction led to significantly better kidney function compared to this control cohort. In conclusion, a biopsy guided personalized immunosuppression protocol after OLT can identify patients requiring lower immunosuppression or patients with graft injury in which IS should not be further reduced.

Viral infections in lung transplantation

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.

Epstein-Barr virus posttransplant lymphoproliferative disorder: update on management and outcomes

PURPOSE OF REVIEW

Management of Epstein-Barr virus posttransplant lymphoproliferative disorder (EBV PTLD) is complex, involving risk stratification, prevention and/or preemptive measures involving monitoring EBV DNAemia and balancing treatment options, using a combination of reduction of immune suppression, anti-B cell therapy, and cytotoxic T lymphocytes (CTLs).

RECENT FINDINGS

The highest risk factor for the development of EBV PTLD in hematopoietic cell transplant (HCT) remains T cell depletion, with increasing use of antithymocyte globulin (ATG) or alemtuzumab in conditioning. In solid organ transplantation (SOT), the incidence of PTLD is highest among EBV seronegative recipients who are at risk for primary EBV infection following transplant in the first 12 months. Prevention is a critical component of the management of EBV PTLD. Although preemptive therapy remains standard of care, there continues to be heterogenicity and debate over the optimal choice of EBV DNA quantification and the threshold to use. Novel therapies such as donor-derived multipathogen and EBV specific CTLs for the prevention and third party CTLs for the treatment of EBV PTLD are promising, with rapidly expanding evidence, including large scale Phase III trials currently underway.

SUMMARY

With an increasing number of risk groups for developing EBV PTLD in HCT and SOT, management strategies using prophylaxis or preemptive therapy remain standard of care, however the use of prophylactic or preemptive EBV specific or multipathogen CTLs show promising results and safety profiles.

Evaluation of Cytomegalovirus Infections in Liver Transplant Recipients Under Universal Prophylaxis: A Single Centre Experience

Background: Cytomegalovirus (CMV) is one of the leading viral agents that can pave the way for serious complications and organ damage in solid organ transplant (SOT) recipients after transplantation. Strategies have been developed to protect at-risk patients from CMV infection following transplantation. Since more than 90% of adults in Turkey were positive for CMV IgG, universal CMV prophylaxis was applied, and the results were evaluated. Objectives: This study aimed to evaluate the results of universal CMV prophylaxis after liver transplantation in the long term. Methods: A total of 1,090 liver transplant patients were evaluated in terms of CMV infection in the Organ Transplantation Institute of Inonu University, Malatya, Turkey, from October 2014 to December 2019. In order to identify the CMV infections, quantitative nucleic acid amplification (QNAT) was used to detect potential CMV DNA. The cut-off value of CMV DNA was determined to be 1000 copies/mL after transplantation. Results: According to the clinical and laboratory assessments, 33 (3%) patients were diagnosed with CMV infection, and 25 (2.3%) patients were evaluated as possibly having CMV syndrome. Also, eight of the 33 patients were assessed as having end-organ CMV disease and 25 as probable CMV syndrome. In the late period following prophylaxis, CMV infection was observed in 10 (0.9%) cases. The infection rate after prophylaxis (0.9%) was lower than the infection rate (2.1%) seen during prophylaxis. Conclusions: Close clinical follow-up with CMV prophylaxis and strict monitoring of CMV DNA by determining a specific cut-off point are important in the follow-up of liver transplant patients.

Follicle inhibition at the primordial stage without increasing apoptosis, with a combination of everolimus, verapamil

The aim of the present study was to test whether inhibition of ovarian primordial follicles and subsequent activation can be achieved by transient mTOR inhibition. In this preclinical investigation, forty-five female immature Wistar rats were randomized in 5 groups. The control group received subcutaneous saline injections. The other groups received Everolimus, Everolimus plus Verapamil, Everolimus plus Fisetin, and Fisetin alone. Primary and secondary outcomes were measured in the left ovary after a treatment period of 8 weeks. Ten days later, animals received 35 IU FSH for 4 days and 35 IU of hCG on the 5th day. The same parameters were examined in the right ovary. AMH, estradiol, and progesterone levels were assessed at the end of both interventions. Significantly, more primordial and less atretic follicles were observed in the Everolimus plus Verapamil group. AMH and progesterone levels were substantially lower in the Everolimus group. Interestingly, after ovarian stimulation higher levels of AMH and progesterone were observed in the Everolimus plus Verapamil group. Immunoblot analysis of ovarian extracts revealed that the administration of Everolimus led to a significant reduction in the mTORC1-mediated phosphorylation of the 70-kDa ribosomal protein S6 kinase 1. This decrease was reversed in the presence of FSH after stopping drug administration. The expression of the anti-apoptotic molecule Bcl2 as well as of LC3-II and ATG12 was increased after removal of the Everolimus plus Verapamil combination, indicating reduced apoptosis and increased autophagy, whereas the levels of the proliferation marker PCNA in the granulosa cells were elevated, consistent with initiation of follicular growth.Thus, the combination of Everolimus plus Verapamil is capable of increasing the number of competent primordial follicles while reducing atresia.

Regulation of RLR-Mediated Antiviral Responses of Human Dendritic Cells by mTOR

To detect replicating viruses, dendritic cells (DCs) utilize cytoplasmic retinoic acid inducible gene-(RIG) I-like receptors (RLRs), which play an essential role in the subsequent activation of antiviral immune responses. In this study, we aimed to explore the role of the mammalian target of rapamycin (mTOR) in the regulation of RLR-triggered effector functions of human monocyte-derived DCs (moDCs) and plasmacytoid DCs (pDCs). Our results show that RLR stimulation increased the phosphorylation of the mTOR complex (mTORC) 1 and mTORC2 downstream targets p70S6 kinase and Akt, respectively, and this process was prevented by the mTORC1 inhibitor rapamycin as well as the dual mTORC1/C2 kinase inhibitor AZD8055 in both DC subtypes. Furthermore, inhibition of mTOR in moDCs impaired the RLR stimulation-triggered glycolytic switch, which was reflected by the inhibition of lactate production and downregulation of key glycolytic genes. Blockade of mTOR diminished the ability of RLR-stimulated moDCs and pDCs to secret type I interferons (IFNs) and pro-inflammatory cytokines, while it did not affect the phenotype of DCs. We also found that mTOR blockade decreased the phosphorylation of Tank-binding kinase 1 (TBK1), which mediates RLR-driven cytokine production. In addition, rapamycin abrogated the ability of both DC subtypes to promote the proliferation and differentiation of IFN-y and Granzyme B producing CD8 + T cells. Interestingly, AZD8055 was much weaker in its ability to decrease the T cell proliferation capacity of DCs and was unable to inhibit the DC-triggered production of IFN-y and Granyzme B by CD8 + T cells. Here we demonstrated for the first time that mTOR positively regulates the RLR-mediated antiviral activity of human DCs. Further, we show that only selective inhibition of mTORC1 but not dual mTORC1/C2 blockade suppresses effectively the T cell stimulatory capacity of DCs that should be considered in the development of new generation mTOR inhibitors and in the improvement of DC-based vaccines.

Cytomegalovirus infection after liver transplantation

Human cytomegalovirus (CMV) represents the most common opportunistic infection in liver transplant recipients. CMV infections in post liver transplant patients cause significant morbidity and mortality, directly affecting post-transplant outcomes. This review will provide the framework for the surveillance, diagnosis, prophylaxis and treatment of CMV in the liver transplant population.

Prevention and Management of CMV Infections after Liver Transplantation: Current Practice in German Transplant Centers

Human cytomegalovirus (CMV) remains a major cause of mortality and morbidity in human liver transplant recipients. Anti-CMV therapeutics can be used to prevent or treat CMV in liver transplant recipients, but their toxicity needs to be balanced against the benefits. The choice of prevention strategy (prophylaxis or preemptive treatment) depends on the donor/recipient sero-status but may vary between institutions. We conducted a series of consultations and roundtable discussions with German liver transplant center representatives. Based on 20 out of 22 centers, we herein summarize the current approaches to CMV prevention and treatment in the context of liver transplantation in Germany. In 90% of centers, transient prophylaxis with ganciclovir or valganciclovir was standard of care in high-risk (donor CMV positive, recipient CMV naive) settings, while preemptive therapy (based on CMV viremia detected during (bi) weekly PCR testing for circulating CMV-DNA) was preferred in moderate- and low-risk settings. Duration of prophylaxis or intense surveillance was 3-6 months. In the case of CMV infection, immunosuppression was adapted. In most centers, antiviral treatment was initiated based on PCR results (median threshold value of 1000 copies/mL) with or without symptoms. Therefore, German transplant centers report similar approaches to the prevention and management of CMV infection in liver transplantation.

Immunosuppression, BK polyomavirus infections, and BK polyomavirus-specific T cells after pediatric kidney transplantation

BACKGROUND

After kidney transplantation, immunosuppressive therapy increases risk of BK polyomavirus-associated nephropathy (BKPyVAN). Outcomes of BKPyV viremia are various and prognostic markers are missing. The impact of different immunosuppressive regimens on BKPyV infections is currently under discussion.

METHODS

We analyzed immunosuppressive therapy and BKPyV-specific cellular immunity to distinguish patients at risk of BKPyVAN from those with self-limiting viremia for purposes of risk-stratified BKPyV management. In a retrospective analysis, 46 pediatric kidney recipients with BKPyV viremia were analyzed with regard to duration of BKPyV viremia and immunosuppressive therapy; in addition, in 37/46 patients, BKPyV-specific CD4 and CD8 T cells were measured.

RESULTS

Nine patients showed persistent BKPyV viremia and BKPyVAN, and required therapeutic intervention, while 37 patients had asymptomatic, self-limiting viremia. At onset of viremia, 78% of patients with persistent viremia and BKPyVAN were treated with tacrolimus, whereas tacrolimus therapy was significantly less frequent in patients with self-limiting viremia (14%). The majority of patients with transient, self-limiting viremia received cyclosporine A (81%) and/or mTOR inhibitors (81%). Patients with persistent BKPyV viremia and BKPyVAN showed lack of BKPyV-specific CD4 and CD8 T cells (6/6), whereas the majority of patients with self-limiting viremia (27/31) had detectable BKPyV-specific CD4 and/or CD8 T cells ≥ 0.5 cells/μl (p < 0.001).

CONCLUSIONS

These results indicate that tacrolimus enhances risk of BKPyVAN with need of therapeutic intervention, whereas under cyclosporine A and mTOR inhibitors, the majority of pediatric kidney recipients showed self-limiting viremia. In patients at risk of BKPyV infections, combination of cyclosporine A and mTOR inhibitor may be advantageous.

Diagnostics, treatment, and immune response in BK polyomavirus infection after pediatric kidney transplantation

After pediatric kidney transplantation BK polyomavirus (BKPyV) infections are associated with an increased risk of graft loss by BKPyV-associated nephropathy (BkPyVAN). However, suitable prognostic markers for the individual outcome of BKPyV infections are missing and the management of therapeutic interventions remains a challenge to the success of pediatric kidney transplantation. This review gives an overview on current diagnostic and therapeutic strategies in the field of BKPyV infections after pediatric kidney transplantation. Methods determining the individual immune response to BKPyV are described and their usability is discussed. There is growing evidence that BKPyV-specific T cells (BKPyV-Tvis) may serve as prognostic markers in order to steer immunosuppressive therapy in pediatric kidney recipients with BKPyV viremia in future. Prospective randomized trials in viremic kidney recipients comparing Tvis-steered therapeutic intervention with standard reduction of immunosuppression are needed before implementation of BKPyV-Tvis monitoring in routine care of BKPyV infections.

Pretransplant adaptive NKG2C+ NK cells protect against cytomegalovirus infection in kidney transplant recipients

Cytomegalovirus (CMV) infection constitutes a complication for kidney transplant recipients (KTR) and CMV-specific T cells reduce the risk of viral replication in seropositive patients. CMV promotes the adaptive differentiation and expansion of an NK cell subset, hallmarked by expression of the CD94/NKG2C receptor with additional characteristic features. We previously reported an association of pretransplant NKG2C+ NK cells with a reduced incidence of CMV infection. We have strengthened the analysis in cryopreserved peripheral blood mononuclear cells from an enlarged KTR cohort (n = 145) with homogeneous immunosuppression, excluding cases at low risk of infection (ie, CMV D-R-) or receiving antiviral prophylaxis. Moreover, adaptive NKG2C+ NK cell-associated markers (ie, NKG2A, CD57, Immunoglobulin-like transcript 2 [LIR1 or LILRB1], FcεRI γ chain, and Prolymphocytic Leukemia Zinc Finger transcription factor) as well as T lymphocyte subsets were assessed by multicolor flow cytometry. The relation of NKG2C+ NK cells with T cells specific for CMV antigens was analyzed in pretransplant patients (n = 29) and healthy controls (n = 28). Multivariate Cox regression and Kaplan-Meier analyses supported that NKG2C+ NK cells bearing adaptive markers were specifically associated with a reduced incidence of posttransplant symptomatic CMV infection; no correlation between NKG2C+ NK cells and CMV-specific T cells was observed. These results support that adaptive NKG2C+ NK cells contribute to control CMV infection in KTR.

Rapamycin for longevity: opinion article

From the dawn of civilization, humanity has dreamed of immortality. So why didn't the discovery of the anti-aging properties of mTOR inhibitors change the world forever? I will discuss several reasons, including fear of the actual and fictional side effects of rapamycin, everolimus and other clinically-approved drugs, arguing that no real side effects preclude their use as anti-aging drugs today. Furthermore, the alternative to the reversible (and avoidable) side effects of rapamycin/everolimus are the irreversible (and inevitable) effects of aging: cancer, stroke, infarction, blindness and premature death. I will also discuss why it is more dangerous not to use anti-aging drugs than to use them and how rapamycin-based drug combinations have already been implemented for potential life extension in humans. If you read this article from the very beginning to its end, you may realize that the time is now.

Safety considerations with current and emerging antiviral therapies for cytomegalovirus infection in transplantation

Introduction: Human cytomegalovirus (HCMV) is a major contributor of morbidity and mortality, and its management is essential for the successful outcome of solid organ and hematopoietic stem cell transplantation. Areas covered: This review discusses the safety profiles of currently available and emerging antiviral drugs and the other strategies for HCMV prevention and treatment after transplantation. Expert opinion: Strategies for management of HCMV rely largely on the use of antiviral agents that inhibit viral DNA polymerase (ganciclovir/valganciclovir, foscarnet, and cidofovir/brincidofovir) and viral terminase complex (letermovir), with different types and degrees of adverse effects. An investigational agent, maribavir, exerts its anti-CMV effect through UL97 inhibition, and its safety profile is under clinical evaluation. In choosing the antiviral medication to use, it is important to consider these safety profiles in addition to overall efficacy. In addition to antiviral drugs, reduction of immunosuppression is often generally needed in the management of HCMV infection, but with a potential risk of allograft rejection or graft-versus-host disease. The use of HCMV-specific or non-specific intravenous immunoglobulins remains debated, while adoptive HCMV-specific T cell therapy remains investigational, and associated with unique set of adverse effects.

Impact assessment and investigation of factors associated with herpesviruses viremia in the first year of renal transplantation

The increased risk for opportunistic infections after a renal transplant requires monitoring of viral infections to avoid future complications. Our goal was to investigate the impact and factors associated with Epstein-Barr virus (EBV), human cytomegalovirus (HCMV) and human herpesvirus type 6 (HHV-6) viremia in renal transplant recipients. Whole blood samples were collected monthly from 82 patients during the first semester and then quarterly up to 1 year after transplantation. EBV, HCMV, and HHV-6 were detected and quantified by TaqMan real-time polymerase chain reaction. The results showed that EBV and HCMV viremia were detected in 32 patients (39% each), while HHV-6 viremia in only 3 patients (3.7%). EBV was significantly associated with age (P = .050), thymoglobuline induction (P = .019), mTOR inhibitor-based therapy (P = .003), and female gender (P = .044). HCMV was significantly associated with basiliximab induction (P = .015), mycophenolate mofetil (MMF)-based therapy (P = .003) and allograft acute rejection (P = .033). Moreover, HCMV-disease was correlated with MMF-based therapy (P = .021) and female gender (P = .003). In conclusion, EBV and HCMV viremia were associated with different immunosuppressive induction and maintenance strategies. Additionally, higher HCMV viremia (> 10 ⁴ copies/mL) was related to acute allograft rejection.

Utility of neonatal donors in pediatric liver transplantation: A single-center experience

BACKGROUND

The lack of age- and size-matched organs result in higher waiting list mortality in pediatric recipients than adults. Organs from deceased newborns and infants are a valuable source to increase donor pool in pediatric liver transplantation. However, the feasibility and safety of using neonatal donors have not been well evaluated.

METHODS

From 2014 to 2016, 48 deceased donor pediatric liver transplantations with donor age younger than 1 year old in our center were enrolled in this study. The recipients were divided into three groups based on the donor age (<1 month, 1 month ≤ to <3 months, and 3 months ≤ to <1 year). Recipient's characteristics, perioperative data, and postoperative complications were compared.

RESULTS

Two-year patient survival rates were 87.5%, 94.4%, and 95.5%, and 2-year graft survival rates were 75%, 94.4%, and 95.5%, respectively, without significant difference. The liver grafts from donors younger than 3 months were more advantageous in terms of acute rejection and virus infection, while the young grafts were related to slight higher incidence of hepatic artery thrombosis and SFSS. Those complications could be effectively prevented or treated by our perioperative care strategies. In addition, eight recipients who received neonatal livers achieved comparable outcomes with recipients with older livers.

CONCLUSION

Our data revealed that the application of liver grafts from donors younger than 1 year old could achieve excellent outcome. In particular, neonatal donors could be safely used in well-selected patients.

Post-transplant lymphoproliferative disorders, Epstein-Barr virus infection, and disease in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

PTLD with the response-dependent sequential use of RIS, rituximab, and cytotoxic chemotherapy is recommended. Evidence gaps requiring future research and alternate treatment strategies including immunotherapy are highlighted.

Remission of Epstein-Barr virus-positive post-transplant lymphoproliferative disorder by conversion to everolimus in a kidney transplant recipient

Post-transplant lymphoproliferative disorder (PTLD) is a fatal complication of transplantation. There is no clear consensus on the treatment of PTLD. In most cases, the pathogenetic mechanism of PTLD involves the Epstein-Barr virus (EBV). We report the case of an elderly kidney transplant recipient who developed EBV-positive monomorphic T-cell PTLD 14 years after transplantation. Conversion from conventional immunosuppressants to everolimus induced complete remission of PTLD accompanied by a decrease in blood EBV-DNA level without chemotherapy.

Cytomegalovirus in solid organ transplant recipients-Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice

Cytomegalovirus (CMV) is one of the most common opportunistic infections that affect the outcome of solid organ transplantation. This updated guideline from the American Society of Transplantation Infectious Diseases Community of Practice provides evidence-based and expert recommendations for screening, diagnosis, prevention, and treatment of CMV in solid organ transplant recipients. CMV serology to detect immunoglobulin G remains as the standard method for pretransplant screening of donors and transplant candidates. Antiviral prophylaxis and preemptive therapy are the mainstays of CMV prevention. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is highlighted, as a result of variability of CMV nucleic acid testing, even in the contemporary era when calibrators are standardized. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management. Strategies for managing drug-resistant CMV infection are presented. There is an increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, but their role in optimizing CMV prevention and treatment efforts has yet to be demonstrated. Specific issues related to pediatric transplant recipients are discussed.

AMPK-Targeted Effector Networks in Mycobacterial Infection

AMP-activated protein kinase (AMPK), a key metabolic regulator, plays an essential role in the maintenance of energy balance in response to stress. Tuberculosis (TB), primarily caused by the pathogen Mycobacterium tuberculosis (Mtb), remains one of the most important infectious diseases worldwide, characterized by both high incidence and mortality. Development of new preventive and therapeutic strategies against TB requires a profound understanding of the various host-pathogen interactions that occur during infection. Emerging data suggest that AMPK plays an essential regulatory role in host autophagy, mitochondrial biogenesis, metabolic reprogramming, fatty acid β-oxidation, and the control of pathologic inflammation in macrophages during Mtb infection. As described in this review, recent studies have begun to define the functional properties of AMPK modulators capable of restricting intracellular bacteria and promoting host defenses. Several host defense factors in the context of AMPK activation also participate in autophagic and non-autophagic pathways in a coordinated manner to enhance antimicrobial responses against Mtb infection. A better understanding of these AMPK-targeted effector networks offers significant potential for the development of novel therapeutics for human TB and other infectious diseases.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.

Comparison of Cardiac miRNA Transcriptomes Induced by Diabetes and Rapamycin Treatment and Identification of a Rapamycin-Associated Cardiac MicroRNA Signature

Rapamycin (Rap), an inhibitor of mTORC1, reduces obesity and improves lifespan in mice. However, hyperglycemia and lipid disorders are adverse side effects in patients receiving Rap treatment. We previously reported that diabetes induces pansuppression of cardiac cytokines in Zucker obese rats (ZO-C). Rap treatment (750 μg/kg/day for 12 weeks) reduced their obesity and cardiac fibrosis significantly; however, it increased their hyperglycemia and did not improve their cardiac diastolic parameters. Moreover, Rap treatment of healthy Zucker lean rats (ZL-C) induced cardiac fibrosis. Rap-induced changes in ZL-C's cardiac cytokine profile shared similarities with that of diabetes-induced ZO-C. Therefore, we hypothesized that the cardiac microRNA transcriptome induced by diabetes and Rap treatment could share similarities. Here, we compared the cardiac miRNA transcriptome of ZL-C to ZO-C, Rap-treated ZL (ZL-Rap), and ZO (ZO-Rap). We report that 80% of diabetes-induced miRNA transcriptome (40 differentially expressed miRNAs by minimum 1.5-fold in ZO-C versus ZL-C; p ≤ 0.05) is similar to 47% of Rap-induced miRNA transcriptome in ZL (68 differentially expressed miRNAs by minimum 1.5-fold in ZL-Rap versus ZL-C; p ≤ 0.05). This remarkable similarity between diabetes-induced and Rap-induced cardiac microRNA transcriptome underscores the role of miRNAs in Rap-induced insulin resistance. We also show that Rap treatment altered the expression of the same 17 miRNAs in ZL and ZO hearts indicating that these 17 miRNAs comprise a unique Rap-induced cardiac miRNA signature. Interestingly, only four miRNAs were significantly differentially expressed between ZO-C and ZO-Rap, indicating that, unlike the nondiabetic heart, Rap did not substantially change the miRNA transcriptome in the diabetic heart. In silico analyses showed that (a) mRNA-miRNA interactions exist between differentially expressed cardiac cytokines and miRNAs, (b) human orthologs of rat miRNAs that are strongly correlated with cardiac fibrosis may modulate profibrotic TGF-β signaling, and (c) changes in miRNA transcriptome caused by diabetes or Rap treatment include cardioprotective miRNAs indicating a concurrent activation of an adaptive mechanism to protect the heart in conditions that exacerbate diabetes.

Viral infections in the biologic therapy era

INTRODUCTION

The development of biologic therapies for treating patients with rheumatic, hematologic, or oncological diseases has increased in the last few years, spreading their use in clinical practice. Areas covered: Clinical experience has evidenced substantial risks for some viral infections and/or reactivations such as viral hepatitis, herpetic infections, and other viruses, as a consequence of specific immune pathway blockages. Biological therapies produce a variable risk of reactivation of viral infections, which is particularly uncertain in the case of the most recently introduced agents. Here we make an extensive review of the viral infections associated with the use of biological drugs and provide a series of recommendations for its prevention and management. Expert commentary: To prevent these infections/reactivations, the practitioner must be aware of the infection-risk profile, performing accurate screening during and after the use of any biologic agent. In some instances, expert recommendations are made for some therapies, while in other scenarios recommendations have not yet been defined making experimental and clinical research an essential approach to elucidate multiple issues yet not resolved in this field.

Introduction of everolimus in kidney transplant recipients at a late posttransplant stage

This minireview focuses on the current knowledge about the introduction of everolimus (EVL), a mammalian target of rapamycin inhibitor, with calcineurin inhibitor (CNI) elimination or minimization in kidney transplant recipients at a late posttransplant stage. Within, we have summarized two major clinical trials, ASCERTAIN and APOLLO, and seven other retrospective or nonrandomized studies. In the open-label multicenter ASCERTAIN study, the estimated glomerular filtration rate (eGFR) at 24 mo after conversion was not significantly different between three groups-EVL with CNI elimination, CNI minimization and continued CNI unchanged-at a mean of 5.4 years after transplantation. However, recipients with baseline creatinine clearance higher than 50 mL/min had a greater increase in measured GFR after CNI elimination. In the open-label multicenter APOLLO study, adjusted eGFR within the on-treatment population was significantly higher in the EVL continuation group than in the CNI continuation group at 12 mo after conversion at a mean of 7 years posttransplantation. Other studies on recipients without adverse events and already having satisfactory renal function showed favorable graft function by EVL late-induction with CNI elimination or reduction. These studies showed that chronic allograft nephropathy, CNI nephrotoxicity, CNI arteriolopathy, cancer and viral infection (especially cytomegalovirus infection) may be good indications for late conversion to EVL.

Antiviral activity of maribavir in combination with other drugs active against human cytomegalovirus

The human cytomegalovirus (CMV) UL97 kinase inhibitor maribavir is in Phase III clinical trials as antiviral therapy, including use for infections refractory or resistant to standard therapy. To assess its activity in combination with approved and experimental CMV antivirals, and with the mTor inhibitor rapamycin (sirolimus), drug effects were tested by in vitro checkerboard assays and the data were analyzed using a three dimensional model based on an independent effects definition of additive interactions. Baseline virus and representative drug-resistant mutants were tested. According to the volume of synergy at 95% confidence, maribavir showed additive interactions with foscarnet, cidofovir, letermovir and GW275175X when tested against wild type and mutant viruses, strong antagonism with ganciclovir, and strong synergy with rapamycin, the latter suggesting a potentially useful therapeutic combination.

Effect of conversion from calcineurin inhibitors to everolimus on hepatitis C viremia in adult kidney transplant recipients

Introduction:

Currently, there is no specific immunosuppressive protocol for hepatitis C (HCV)-positive renal transplants recipients. Thus, the aim of this study was to evaluate the conversion effect to everolimus (EVR) on HCV in adult kidney recipients.

Method:

This is an exploratory single-center, prospective, randomized, open label controlled trial with renal allograft recipients with HCV-positive serology. Participants were randomized for conversion to EVR or maintenance of calcineurin inhibitors.

Results:

Thirty patients were randomized and 28 were followed-up for 12 months (conversion group, Group 1 =15 and control group, Group 2 =13). RT-PCR HCV levels reported in log values were comparable in both groups and among patients in the same group. The statistical analysis showed no interaction effect between time and group (p value G*M= 0.852), overtime intra-groups (p-value M=0.889) and between group (p-value G=0.286). Group 1 showed a higher incidence of dyslipidemia (p=0.03) and proteinuria events (p=0.01), while no difference was observed in the incidence of anemia (p=0.17), new onset of post-transplant diabetes mellitus (p=1.00) or urinary tract infection (p=0.60). The mean eGFR was similar in both groups.

Conclusion:

Our study did not show viral load decrease after conversion to EVR with maintenance of antiproliferative therapy.

Human polyomavirus-7-associated eruption successfully treated with acitretin

Advances in molecular technologies have led to the discovery of several novel human polyomaviruses (HPyVs), including human polyomavirus-7 (HPyV-7). Although low levels of HPyV-7 are shed from apparently normal skin, recent reports have described clinically significant cutaneous infection in immunocompromised patients that manifests as generalized pruritic plaques. The pruritus can be severe, and treatment options have not been described. Herein we report HPyV-7 cutaneous infection in a heart transplant patient who experienced temporary improvement with intravenous cidofovir, and complete remission with acitretin. We report a case of HPyV-7 cutaneous infection demonstrating a good response to treatment.

Steroid Withdrawal Using Everolimus in ABO-Incompatible Kidney Transplant Recipients With Post-Transplant Diabetes Mellitus

BACKGROUND

The effectiveness of everolimus (EVR) for ABO-incompatible (ABOi) kidney transplantation is unknown. We evaluated outcomes of conversion from steroid to EVR in ABOi kidney transplant recipients.

METHODS

We performed a retrospective observational cohort study of 33 de novo consecutive adult ABOi living donor kidney transplant recipients. Desensitization was performed using 0 to 4 sessions of plasmapheresis and 1 to 2 doses of 100 mg rituximab according to the anti-A/B antibody titer. ABOi recipients were administered a combination of tacrolimus, mycophenolate mofetil, and methylprednisolone. Diabetic patients were converted from methylprednisolone to EVR at 1 to 15 months post-transplantation to prevent diabetes progression. Graft outcomes, hemoglobin A1c (HbA1c) levels, and cytomegalovirus infection rates were compared between the EVR (n = 11) and steroid (n = 22) groups.

RESULTS

Mean postoperative duration was 814 and 727 days in the EVR and steroid groups, respectively (P = .65). Between the 2 groups, graft survival rate (100% vs 95.5%, P > .99), acute rejection rate (9.1% vs 18.2%, P = .64), and serum creatinine levels (1.46 mg/dL vs 1.68 mg/dL, P = .66) were comparable. Although HbA1c levels were elevated in the steroid group (5.47%, 5.87%; P = .003), no significant deterioration was observed in the EVR group without additional insulin administration (6.10%, 6.47%; P = .21). Cytomegalovirus infection rate was significantly lower in the EVR group than in the steroid group (18.2% vs 63.6%, P = .026).

CONCLUSION

Conversion from steroid to EVR in ABOi kidney transplant recipients maintained excellent graft outcomes and avoided diabetes progression and cytomegalovirus infection.

Enzyme-Linked Immunospot Assay as a Complementary Method to Assess and Monitor Cytomegalovirus Infection in Kidney Transplant Recipients on Pre-emptive Antiviral Therapy: A Single-Center Experience

BACKGROUND

Cytomegalovirus (CMV) disease represents a major cause of post-transplantation morbidity and mortality. To estimate the risk of infection and monitor response to antiviral therapy, current guidelines suggest combination of viral load monitoring with direct assessment of CMV-specific immune response. We used enzyme-linked immunospot (ELISpot) for the evaluation of CMV-specific T-cell response in kidney transplant recipients with CMV viremia and investigated how information gained could help manage CMV infection.

METHODS

Seventeen patients on pre-emptive antiviral therapy and CMV quantitative polymerase chain reaction (qPCR) ≥500 copies/mL (first episode after transplantation) were assessed using ELISpot and divided into Weak (9 patients with baseline ELISpot <25 spot-forming colonies [SFCs]/200,000 peripheral blood mononuclear cells [PBMCs]) and Strong Responders (8 patients with baseline ELISpot ≥25 SFCs/200,000 PBMCs). CMV-specific T-cell response, infection severity, viral load, and antiviral therapy were prospectively recorded and compared between groups at 1, 2, and 24 months of follow-up.

RESULTS

Demographic and transplant characteristics of Weak and Strong Responders were similar. No episodes of CMV disease were observed. Weak Responders were more likely to experience CMV syndrome (56% vs 36.5%) and late virus reactivation (56% vs 25%) than Strong Responders. Weak Responders showed higher baseline median viral loads (19,700 vs 9265 copies/mL) and needed antiviral therapy for longer (179 vs 59.5 days). T-cell response showed 2 main patterns: early and delayed.

CONCLUSIONS

ELISpot provides prognostic information about infection severity, risk of late reactivation, and response to therapy. Randomized trials, evaluating the need for antiviral therapy in kidney transplant recipients with asymptomatic infection and effective virus-specific T-cell immune response, are warranted.

ESCMID Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biological therapies: an infectious diseases perspective (Intracellular signaling pathways: tyrosine kinase and mTOR inhibitors)

BACKGROUND

The present review is part of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biologic therapies.

AIMS

To review, from an infectious diseases perspective, the safety profile of therapies targeting different intracellular signaling pathways and to suggest preventive recommendations.

SOURCES

Computer-based Medline searches with MeSH terms pertaining to each agent or therapeutic family.

CONTENT

Although BCR-ABL tyrosine kinase inhibitors modestly increase the overall risk of infection, dasatinib has been associated with cytomegalovirus and hepatitis B virus reactivation. BRAF/MEK kinase inhibitors do not significantly affect infection susceptibility. The effect of Bruton tyrosine kinase inhibitors (ibrutinib) among patients with B-cell malignancies is difficult to distinguish from that of previous immunosuppression. However, cases of Pneumocystis jirovecii pneumonia (PCP), invasive fungal infection and progressive multifocal leukoencephalopathy have been occasionally reported. Because phosphatidylinositol-3-kinase inhibitors (idelalisib) may predispose to opportunistic infections, anti-Pneumocystis prophylaxis and prevention strategies for cytomegalovirus are recommended. No increased rates of infection have been observed with venetoclax (antiapoptotic protein Bcl-2 inhibitor). Therapy with Janus kinase inhibitors markedly increases the incidence of infection. Pretreatment screening for chronic hepatitis B virus and latent tuberculosis infection must be performed, and anti-Pneumocystis prophylaxis should be considered for patients with additional risk factors. Cancer patients receiving mTOR inhibitors face an increased incidence of overall infection, especially those with additional risk factors (prior therapies or delayed wound healing).

IMPLICATIONS

Specific preventive approaches are warranted in view of the increased risk of infection associated with some of the reviewed agents.

Epstein-Barr virus lymphoproliferative disease after solid organ transplantation

Epstein-Barr virus (EBV) was the first identified human oncovirus and is also one of the most ubiquitous viral infections known with established infections in more than 90% of individuals by early adulthood. EBV establishes latency by controlling expression of the viral genome making it silent to immune surveillance. In immunocompetent individuals, up to 1% of circulating T cells are directed at maintaining control over EBV replication. In addition to being involved in oncogenesis of lymphoid and epithelial tumors in immune-competent individuals, loss of immune surveillance over EBV predisposes individuals to EBV malignancies. Lymphoid proliferations from EBV-infected B cells arise in up to 20% of recipients of solid organ transplants (SOTs). One question not answered is why, when EBV requires such active immune surveillance, EBV malignancies are not even more prevalent in severely immune-compromised individuals. A better understanding of who develops complications related to EBV and what the immunologic risks are will ultimately make it feasible to perform prophylactic trials in those at highest risk. This review summarizes our current understanding of factors in SOT recipients that predispose them to the development of an EBV malignancy and that predict response to initial therapy. We then review the current landscape of those therapies, focusing on the goal of restoring long-term EBV-directed immunity to patients at risk.