Thomas Jouve

Conversion to mammalian target of rapamycin inhibitors increases risk of de novo donor-specific antibodies

In kidney transplantation, conversion to mammalian target of rapamycin (mTOR) inhibitors may avoid calcineurin inhibitor (CNI) nephrotoxicity, but its impact on post‐transplant allo‐immunization remains largely unexplored. This retrospective cohort study analyzed the emergence of donor‐specific antibodies (DSA) in kidney transplant recipients relative to their immunosuppressive therapy. Among 270 recipients without pretransplant immunization who were screened regularly for de novo DSA, 56 were converted to mTOR inhibitors after CNI withdrawal. DSA emergence was increased in patients who were converted to mTOR inhibitors (HR 2.4; 95% CI 1.06–5.41, P = 0.036). DSA were mainly directed against donor HLA‐DQB1 antigens. The presence of one or two DQ mismatches was a major risk factor for DQ DSA (HR 5.32; 95% CI 1.58–17.89 and HR 10.43; 95% CI 2.29–47.56, respectively; P < 0.01). Rejection episodes were more likely in patients converted to mTOR inhibitors, but this difference did not reach significance (16% vs. 7.9%, P = 0.185). Concerning graft function, no significant change was observed one year after conversion (P = 0.31). In conclusion, conversion to mTOR inhibitors may increase the risk of developing class II DSA, especially in the presence of DQ mismatches: this strategy may favor chronic antibody‐mediated rejection and thus reduce graft survival.

Costimulation Blockade in Kidney Transplantation: An Update

Abstract In the setting of solid-organ transplantation, calcineurin inhibitor (CNI)-based therapy remains the cornerstone of immunosuppression. However, long-term use of CNIs is associated with some degree of nephrotoxicity. This has led to exploring the blockade of some costimulation pathways as an efficient immunosuppressive tool instead of using CNIs. The only agent already in clinical use and approved by the health authorities for kidney transplant patients is belatacept (Nulojix), a fusion protein that interferes with cytotoxic T lymphocyte-associated protein 4. Belatacept has been demonstrated to be as efficient as cyclosporine-based immunosuppression and is associated with significantly better renal function, that is, no nephrotoxicity. However, in the immediate posttransplant period, significantly more mild/moderate episodes of acute rejection have been reported, favored by the fact that cytotoxic T lymphocyte-associated protein pathway has an inhibitory effect on the alloimmune response; thereby its inhibition is detrimental in this regard. This has led to the development of antibodies that target CD28. The most advanced is FR104, it has shown promise in nonhuman primate models of autoimmune diseases and allotransplantation. In addition, research into blocking the CD40-CD154 pathway is underway. A phase II study testing ASK1240, that is, anti-CD40 antibody has been completed, and the results are pending.

Differential impact of glucose levels and advanced glycation end-products on tubular cell viability and pro-inflammatory/ profibrotic functions

High glucose (HG) or synthetic advanced glycation end-products (AGE) conditions are generally used to mimic diabetes in cellular models. Both models have shown an increase of apoptosis, oxidative stress and pro-inflammatory cytokine production in tubular cells. However, the impact of the two conditions combined has rarely been studied. In addition, the impact of glucose level variation due to cellular consumption is not clearly characterized in such experiments. Therefore, the aim of this study was to compare the effect of HG and AGE separately and of both on tubular cell phenotype changes in the HK2 cell line. Moreover, glucose consumption was monitored every hour to maintain the glucose level by supplementation throughout the experiments. We thus observed a significant decrease of apoptosis and H2O2 production in the HK2 cell. HG or AGE treatment induced an increase of total and mitochondrial apoptosis as well as TGF-β release compared to control conditions; however, AGE or HG led to apoptosis preferentially involving the mitochondria pathway. No cumulative effect of HG and AGE treatment was observed on apoptosis. However, a pretreatment with RAGE antibodies partially abolished the apoptotic effect of HG and completely abolished the apoptotic effect of AGE. In conclusion, tubular cells are sensitive to the lack of glucose as well as to the HG and AGE treatments, the AGE effect being more deleterious than the HG effect. Absence of a potential synergistic effect of HG and AGE could indicate that they act through a common pathway, possibly via the activation of the RAGE receptors.

Place of mTOR inhibitors in management of BKV infection after kidney transplantation.

Context: BK virus (BKV) viremia and BKV-associated nephropathy (BKVAN) have become a serious nuisance to kidney transplant (KT) patients since the mid-nineties, when the incidence of this disease has increased significantly. Evidence Acquisition: Directory of open access journals (DOAJ), EMBASE, Google Scholar, PubMed, EBSCO, and Web of Science have been searched. Results: Many hypothesis have been made as to why this phenomenon has developed; it is of general opinion that a more potent immunosuppression is at the core of the problem. The use of the association of tacrolimus (TAC) with mycophenolic acid (MPA) has gained momentum in the same years as the increase in BKV viremia incidence making it seem to be the most likely culprit. m-TOR inhibitors (m-TORIs) have been shown to have antiviral properties in vitro and this fact has encouraged different transplant teams to use these agents when confronted with BKV infection (viremia or nephropathy). However, the results are mitigated. There had been conflicting results for example when converting from TAC-to sirolimus-based immunosuppression in the setting of established BKVAN. Conclusions: In order to prevent BKV infection we have to minimize to some extent immunosuppression, but it is not always possible, e.g. in high immunological risk patients. Conversely, we could use m-TORIs associated with low-dose calcineurin inhibitors (CNIs). This could be actually the key to a safe immunosuppression regimen both from the immunological stand point and from the viral one.

Induction by anti-thymocyte globulins in kidney transplantation: a review of the literature and current usage

Context: Preventing acute rejection (AR) after kidney transplantation is of utmost importance because an AR can have a negative impact on long-term allograft survival. Evidence Acquisition: Directory of Open Access Journals (DOAJ), Google Scholar, PubMed, EBSCO, and Web of Science have been searched. Results: At the moment this can be done by using rabbit anti-thymocyte globulins (rATGs) as an induction therapy. However, because rATGs are associated with some deleterious side-effects, such as the opportunistic infections cytomegalovirus (CMV) and de novo post-transplant cancer, it is very important they are used optimally, i.e., at minimal doses that avoid many side-effects but still retain optimal treatment efficacy. Recent data show that the risk of CMV infection can be minimized using tacrolimus plus everolimus, and not tacrolimus plus mycophenolic acid, as the maintenance immunosuppression. The use of rATG is particularly valuable in; (a) sensitized patients; (b) in recipients from an expanded-criteria donor, thus enabling the introduction of calcineurin inhibitors at reduced doses; and (c) for patients where steroid avoidance is contemplated. However, we also need to consider that rATG may increase the risk of de novo cancer, even though recent data indicate this is unlikely and that any risk can be reduced by using mammalian target of rapamycin (mTOR) inhibitors instead of mycophenolic acid combined with low-dose calcineurin inhibitors. Conclusions: Even though rATGs do not improve long-term kidney-allograft survival, they may help reduce calcineurin-inhibitor dosage during the early post-transplant period and minimize the risk of AR.

New formulations of tacrolimus and prevention of acute and chronic rejections in adult kidney-transplant recipients

ABSTRACT Introduction: As tolerance is not yet achievable, the kidney-transplanted-patients have to take on a daily-basis immunosuppressive drugs in order to avoid acute rejection-AR-. The cornerstone of immunosuppression relies on tacrolimus-therapy which is potentially nephrotoxic. Areas Covered: We identified from the studies published in the recent years those who were reporting on AR in de novo kidney-transplant recipients under tacrolimus-based therapy, as well as those who reported on the attempt to minimize tacrolimus-therapy. Results: There are many formulations of tacrolimus: immediate-release (Prograf®), slow-release (Advagraf®), or extended-release (Envarsus®). All demonstrate a very good efficacy in preventing AR episodes. Studies in which tacrolimus was minimized or even weaned-off have shown that it was unsafe, i.e. in resulting in AR episode and/or de novo donor-specific alloantibodies. Recent data show that Tacrobell®, a generic of tacrolimus, was as efficient as Prograf® in the short- and long-term. Expert-opinion: Tacrolimus-based immunosuppression is very effective in preventing rejection in kidney-transplant recipients. It might be associated with nephrotoxicity, that can be reduced by avoiding tacrolimus trough levels too high in the long-term. Conversely, tacrolimus ultraminimization should not be attempted.

Tailoring tacrolimus therapy in kidney transplantation

ABSTRACT Introduction: The prevalence of end-stage renal disease is increasing worldwide. The best treatment is kidney transplantation, although life-long immunosuppressive therapy is then mandatory. Currently, the cornerstone immunosuppressive therapy relies on tacrolimus (Tac), a calcineurin inhibitor that is nephrotoxic but whose exposition can be minimized in a delicate balance. Area covered: We addressed whether, in the setting of kidney transplantation, Tac-based therapy can be tailored to medical needs: to achieve this, we searched for suitable articles in PubMed. Expert commentary: Too over-minimization of Tac, when associated with mycophenolic acid (MPA), may cause the development of de novo donor-specific alloantibodies (DSA). However, Tac minimization, in the context of everolimus-associated therapy instead of MPA, does not increase DSA formation as demonstrated in the TRANSFORM study and, in addition, can prevent cytomegalovirus (CMV) infection/reactivation. Nonetheless, Tac therapy, regardless of its formulation (immediate or extended release) compared to cyclosporine A, increases the risk of posttransplant diabetes mellitus; this increase is not affected by steroid therapy. Tac-based immunosuppression remains the best immunosuppressive therapy in kidney-transplant recipients and can be tailored according to patients’ need.

Negative Impact of CMV and BKV Infections on Kidney-Allograft Function at 1-Year Post-Transplantation: Can it Be Changed by Modifying Immunosuppression?

Kidney transplantation is a well-established therapy for end-stage kidney disease and provides very good long-term kidney-allograft survival provided there is adequate immunosuppression. However, transplantation [4]. This BKV replication has a major negative impact on the kidney allograft, i.e., it induces BKV-associated nephropathy every attempt to minimize immunosuppression substantially has been disastrous and has resulted in acute rejection episodes and/or the de novo occurrence of donor-specific alloantibodies, causing antibodymediated rejection [1]. Conventional immunosuppression includes a first phase where patients receive an induction therapy (lymphocyte-depleting agents or basiliximab therapy) in addition to, in most cases, high doses of a calcineurin inhibitor (CNI: cyclosporine A or tacrolimus), plus an antimetabolite (mycophenolic acid [MPA] or azathioprine), and high doses of steroids. At three to six months post-transplantation, lower doses of CNI are needed (plus an antimetabolite), with or without very low doses of steroids. Chronic immunosuppression has many drawbacks such as opportunistic infections over the short term, mostly viral infections (i.e., cytomegalovirus [CMV], BK virus [BKV] infections), and de novo cancers in the longer term, which are mostly driven by viruses such as Epstein-Barr virus (EBV), human papilloma virus (HPV), and human herpes 8 (HHV8). Until two decades ago, themajor concernwasCMV-associated infection or disease that caused direct and indirect effects such as decreased patient and graft survival, post-transplant de novo diabetes, cardiovascular morbidity, etc. [2]. However, when efficacious anti-CMV agents became available, i.e., ganciclovir and valganciclovir, the burden of CMV infection was decreased significantly. Nonetheless, the cost of anti-CMV agents is very high, and in countries where it is not reimbursed (e.g., Brazil), the incidence of CMV infection/disease within the first year post-transplantation can be as high as 37.6% in kidneytransplant patients that have had no CMV prophylaxis and where immunosuppression has relied on tacrolimus + MPA+ steroids [3]. Because CMV infection became of lesser concern,we havewitnessed an increase in BKV infection (e.g., BKV viruria and BKV viremia), which

Aortic bypass surgery for asymptomatic patients awaiting a kidney transplant: A word of caution

In the presence of severe aorto‐iliac calcification, aortic bypass surgery can be mandatory to allow kidney transplantation. The aim of our study was to evaluate the safety and outcomes of this strategy among asymptomatic patients.

Reducing Fibrinogen and Factor XIII Using Double-Filtration Plasmapheresis for Antibody-Mediated Rejection: Predictive Models

Background/Aims: Antibody-mediated rejection (AMR) is related to circulating donor-specific anti-human leukocyte antigen alloantibodies (DSAs). DSAs can be removed by apheresis, for example, double-filtration plasmapheresis (DFPP). However, DFPP removes some clotting factors (fibrinogen and factor XIII [FXIII]). Methods: This was a prospective trial including 6 DSA-mediated AMR kidney transplant recipients. Patients received 2 cycles of 3–4 consecutive DFPP sessions followed by 1 injection of rituximab (break of 4–5 days between the 2 cycles). We monitored fibrinogen and FXIII levels before and after each session of DFPP. Results: Overall, fibrinogen and FXIII levels were significantly decreased after each session, and were significantly reduced between the very first and very last sessions. In addition, we established a model that predicted fibrinogen and FXIII values after each session and after 2 cycles. Conclusion: We established a model in order to predict fibrinogen and FXIII depletion after DFPP sessions; it may help clinicians supplement fibrinogen and/or FXIII when appropriate.