The utility of splenectomy as rescue treatment for severe acute antibody mediated rejection

Characteristics of Early Antibody Mediated Rejection in Antibody Incompatible Living Donor Kidney Transplantation

Antibody incompatible transplantation (AIT) may be an only option for highly sensitized patients. Severe form of early antibody mediated rejection (AMR) adversely affects graft survival after AIT. The aim of this study was to identify individuals at risk of AMR. We analyzed 213 living donor AITs performed at our center. Among 120 ABOi, 58 HLAi and 35 DSA + FCXM-negative cases, the rates of early AMR were 6%, 31%, and 9%, respectively (p < 0.001). On multivariate analysis for graft loss, early AMR had a HR of 3.28 (p < 0.001). The HLAi group had worse death-censored graft survival (p = 0.003). In the HLAi group, Patients with aggressive variant AMR (AAMR) had greater percentage of C3d complement fixing DSA, higher baseline class I and total DSA MFI levels and B-cell FCXM RMF. C1q and C3d complement fixing DSA and strong positivity of baseline B- or T-cell FXCM as predictors of AAMR had 100% sensitivity. Early AMR is of significant clinical concern in AIT as it results in poor graft survival and is not well described in literature. An aggressive variant is characterized by massive rise in DSA levels at rejection. Baseline DSA, C1q, and C3d and baseline FCXM values can be used to risk-stratify candidates for AIT.

Including the liver in the visceral allograft: Impact on donor-specific anti-HLA antibodies and long-term outcomes

Humoral immunity emerges as a risk factor for graft failure after visceral transplantation (VTx) and development of donor-specific anti-HLA antibodies (DSAs) has been linked with poor outcomes. In most cases, a simultaneous liver transplant can be safely performed in sensitized patients with DSA and appears protective against lymphocytotoxic antibodies. We investigated the incidence of acute (AR) and chronic rejection (CR) in 32 VTx without any B cell-depleting pre-treatment (6 isolated intestinal transplants (IT) and 26 liver-containing, multivisceral transplants (MVT) and assessed the presence of donor-specific antibodies (DSA) pre- and post-transplantation. Twenty-one patients (65 %) developed AR, 15 (57 %) of the MVT and 6 (100 %) of the IT (p = 0.05). CR occurred in 4 IT (60 %, p < 0.001). At one month, de novo DSA were present in 71 % of VTx (66 % MVT vs 100 % IT, p = 0.09). At the last available follow-up, 69 % of the MVT and 50 % of the IT patients were DSA-free. De novo DSA seemed more persistent (7/19, 37 %) than pre-Tx DSA (1/6, 17 %; p = n.s.), de novo DSA were more frequently specific for HLA class II than class I, 16/19 (84 %) vs. 7/19 (37 %; p = 0.003), and HLA-DQ was their most frequent target HLA. DQ mismatches appeared to be a risk factor for developing de novo DSA. In conclusion, liver-containing visceral allografts have superior short- and long-term outcomes compared with liver-free allografts. De novo DSA develop early and frequently after VTx performed without B cell-depleting induction therapy, but the exact role of DSA in the pathogenesis of rejection remains unclear.

Current Therapies in Kidney Transplant Rejection

Despite significant advancements in immunosuppressive therapies, kidney transplant rejection continues to pose a substantial challenge, impacting the long-term survival of grafts. This article provides an overview of the diagnosis, current therapies, and management strategies for acute T-cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR). TCMR is diagnosed through histological examination of kidney biopsy samples, which reveal the infiltration of mononuclear cells into the allograft tissue. Corticosteroids serve as the primary treatment for TCMR, while severe or steroid-resistant cases may require T-cell-depleting agents, like Thymoglobulin. ABMR occurs due to the binding of antibodies to graft endothelial cells. The most common treatment for ABMR is plasmapheresis, although its efficacy is still a subject of debate. Other current therapies, such as intravenous immunoglobulins, anti-CD20 antibodies, complement inhibitors, and proteasome inhibitors, are also utilized to varying degrees, but their efficacy remains questionable. Management decisions for ABMR depend on the timing of the rejection episode and the presence of chronic changes. In managing both TCMR and ABMR, it is crucial to optimize immunosuppression and address adherence. However, further research is needed to explore newer therapeutics and evaluate their efficacy.

Therapy in the Course of Kidney Graft Rejection-Implications for the Cardiovascular System-A Systematic Review

Kidney graft failure is not a homogenous disease and the Banff classification distinguishes several types of graft rejection. The maintenance of a transplant and the treatment of its failure require specific medications and differ due to the underlying molecular mechanism. As a consequence, patients suffering from different rejection types will experience distinct side-effects upon therapy. The review is focused on comparing treatment regimens as well as presenting the latest insights into innovative therapeutic approaches in patients with an ongoing active ABMR, chronic active ABMR, chronic ABMR, acute TCMR, chronic active TCMR, borderline and mixed rejection. Furthermore, the profile of cardiovascular adverse effects in relation to the applied therapy was subjected to scrutiny. Lastly, a detailed assessment and comparison of different approaches were conducted in order to identify those that are the most and least detrimental for patients suffering from kidney graft failure.

Prognosis and Treatment for Active and Chronic Antibody-Mediated Rejection in Renal Transplant Recipients; Single Center Experience

BACKGROUND

The aim of the study was to evaluate the prognostic factors and treatment alternatives of antibody-mediated rejection (ABMR) in renal transplant patients.

METHODS

Three thousand renal transplant patients were included in the study. The patients were first divided into 2 groups. Group 1: ABMR [-] recipients (n = 2871), Group 2: ABMR (+) recipients (n = 129). ABMR patients were compared among themselves by dividing them into 3 subgroups (early-active, late-active, chronic-active). The study was performed retrospectively. Different combinations of methylprednisolone, intravenous immunoglobulin (IVIG), rituximab, plasmapheresis (PP), anti-thymocyte globulin (ATG) were used in the treatment and the results were compared.

RESULTS

Graft survival and functions were worse and the rates of CAD, delayed graft function, BK virus, and cytomegalovirus higher in patients with ABMR. Also, graft survival was lower in patients with serum creatinine ≥3 (P = 0.001), GFR <30 (P <0.001), and spot urine protein to creatinine ratio ≥1 (P = 0.042) at the time of diagnosis. High interstitial fibrosis and tubular atrophy scores in chronic ABMR cases and high intimal arteritis scores in active ABMR cases were poor prognostic factors.

CONCLUSIONS

The study showed that ABMR has a poor prognosis in terms of clinical parameters, and treatment should be individualized according to pathologic findings and graft functions at the time of diagnosis. Pulse methylprednisolone and IVIG should be used in the treatment of all ABMR patients, but PP, rituximab, and ATG should be used in selected cases. ABMR has a poor prognosis and treatment should be individualized.

Helper T Cell (CD4+) Targeted Tacrolimus Delivery Mediates Precise Suppression of Allogeneic Humoral Immunity

Antibody-mediated rejection (ABMR) is a major cause of dysfunction and loss of transplanted kidney. The current treatments for ABMR involve nonspecific inhibition and clearance of T/B cells or plasma cells. However, the prognosis of patients following current treatment is poor. T follicular helper cells (Tfh) play an important role in allograft-specific antibodies secreting plasma cell (PC) development. Tfh cells are therefore considered to be important therapeutic targets for the treatment of antibody hypersecretion disorders, such as transplant rejection and autoimmune diseases. Tacrolimus (Tac), the primary immunosuppressant, prevents rejection by reducing T cell activation. However, its administration should be closely monitored to avoid serious side effects. In this study, we investigated whether Tac delivery to helper T (CD4+) cells using functionalized mesoporous nanoparticles can block Tfh cell differentiation after alloantigen exposure. Results showed that Tac delivery ameliorated humoral rejection injury in rodent kidney graft by suppressing Tfh cell development, PC, and donor-specific antibody (DSA) generation without causing severe side effects compared with delivery through the drug administration pathway. This study provides a promising therapeutic strategy for preventing humoral rejection in solid organ transplantation. The specific and controllable drug delivery avoids multiple disorder risks and side effects observed in currently used clinical approaches.

Desensitization Regimen Consisting of High-Dose Intravenous Immunoglobulin, Plasmapheresis, and Rituximab (an Anti-CD20 Antibody), Without Eculizumab and/or Bortezomib, in 41 Highly Sensitized Kidney Transplant Recipients

OBJECTIVES

Antibody-mediated rejection in patients with positive crossmatches can be severe and result in sudden onset of oliguria, leading to graft loss. In an attempt to prevent posttransplant oliguria, we adopted a preoperative desensitization protocol involving the use of high-dose intravenous immunoglobulin/plasmapheresis and the anti-CD20 antibody, rituximab, in 41 transplant recipients with positive crossmatch test results.

MATERIALS AND METHODS

We retrospectively examined the clinical courses of the 41 kidney transplant recipients, paying special attention to renal graft function, urine volume, and changes in the titers of donor-specific antibodies.

RESULTS

Four grafts were lost during an average of 4.5-year follow-up. Average graft function was excellent, with a serum creatinine level of 1.3 ± 0.4 mg/dL. Sufficient urine output, with no oliguria or anuria, was achieved postoperatively in 40 of the 41 patients. However, among the 34 patients who underwent graft biopsies, the biopsies revealed acute antibody-mediated rejection in 21 patients (62%), and chronic antibodymediated rejection in 10 patients (30%).

CONCLUSIONS

The high-dose intravenous immunoglobulin treatment included in our desensitization protocol was shown to be safe and effective for achieving successful transplant outcomes and allowed the avoidance of more aggressive B-cell-targeted treatments, such as C5 inhibitors and/or proteosome inhibitors, for preventing posttransplant oliguria and anuria.

Case Report: Splenic Irradiation for the Treatment of Chronic Active Antibody-Mediated Rejection in Kidney Allograft Recipients With De Novo Donor-Specific Antibodies

Chronic active antibody-mediated rejection (AMR) in renal transplantation is usually refractory to current conventional treatment with rituximab, plasmapheresis (PP), and intravenous immunoglobulins (IVIG). Splenic irradiation has been reported to be effective in the rescue of early severe acute AMR after kidney transplantation; however, its effect in chronic active AMR has not been reported to date. In order to reduce donor-specific antibody (DSA) and prevent the progression of chronic AMR, we used repetitive low-dose splenic irradiation, together with rituximab and PP/IVIG, in two living-related kidney transplant recipients with pathologically diagnosed chronic active AMR and the presence of long-term class II-de novo DSA. DSA monitoring and repeated renal biopsy revealed significantly reduced DSA levels as well as alleviated glomerulitis and peritubular capillaritis in both patients after treatment, and these therapies may have played a role in delaying the progression of chronic AMR. Although DSA levels in both patients eventually rebounded to some extent after treatment, serum creatinine increased slowly in one patient during the 16-month follow-up period and remained stable in the other during the 12-month follow-up period. Given the poor efficacy of conventional treatment at present, splenic irradiation may still be one of the treatment options for chronic active AMR.

Recommended Treatment for Antibody-mediated Rejection After Kidney Transplantation: The 2019 Expert Consensus From the Transplantion Society Working Group

With the development of modern solid-phase assays to detect anti-HLA antibodies and a more precise histological classification, the diagnosis of antibody-mediated rejection (AMR) has become more common and is a major cause of kidney graft loss. Currently, there are no approved therapies and treatment guidelines are based on low-level evidence. The number of prospective randomized trials for the treatment of AMR is small, and the lack of an accepted common standard for care has been an impediment to the development of new therapies. To help alleviate this, The Transplantation Society convened a meeting of international experts to develop a consensus as to what is appropriate treatment for active and chronic active AMR. The aim was to reach a consensus for standard of care treatment against which new therapies could be evaluated. At the meeting, the underlying biology of AMR, the criteria for diagnosis, the clinical phenotypes, and outcomes were discussed. The evidence for different treatments was reviewed, and a consensus for what is acceptable standard of care for the treatment of active and chronic active AMR was presented. While it was agreed that the aims of treatment are to preserve renal function, reduce histological injury, and reduce the titer of donor-specific antibody, there was no conclusive evidence to support any specific therapy. As a result, the treatment recommendations are largely based on expert opinion. It is acknowledged that properly conducted and powered clinical trials of biologically plausible agents are urgently needed to improve patient outcomes.

Upfront use of eculizumab to treat early acute antibody-mediated rejection after kidney allotransplantation and relevance for xenotransplantation

Acute antibody-mediated rejection (AMR) early after transplant remains a challenge, both in allotransplantation and in xenotransplantation. We report the case of an early and severe acute AMR episode in a kidney transplant recipient that was successfully treated with upfront eculizumab. A 58-year-old woman had been on dialysis since 2014. She underwent a first kidney transplant in 2018 with primary non-function and received several blood transfusions. Postoperatively, she developed anti-HLA antibodies. One year later, she received a second allograft from a deceased donor. At day 0, there was only one preformed low-level donor-specific antibody (DSA) anti-DQ7. After initial excellent allograft function, serum creatinine increased on days 7-9, and this was associated with oligo-anuria. On day 7, there was an increase in her DSA anti-DQ7 and 4 de novo DSA had developed at high MFI values. Allograft biopsy showed severe active AMR with diffuse C4d deposits in peritubular capillaries. The early acute AMR episode was treated with upfront eculizumab administration (2 doses) with efficient CH50 blockade (< 10% CH50). Rituximab was also administered on day 12, and intravenous immunoglobulin (IVIG) was given over the following days. There was an excellent clinical response to eculizumab administration. Eculizumab administration rapidly reversed the acute AMR episode without the need for plasmapheresis. Rituximab and IVIG were also used as B-cell immunomodulators to decrease DSA. Blocking efficiently the terminal complement pathway may become a useful strategy to treat acute AMR in sensitized recipients of allografts, and possibly in recipients of discordant xenografts.

Favorable Short-Term Outcome of Living Donor Kidney Transplantations in Flow Cytometry Crossmatch Positive Cases by Pretransplant Splenectomy: A Case Report

BACKGROUND

The introduction of rituximab has contributed to successful living donor kidney transplantations in ABO-incompatible recipients and has replaced splenectomy for desensitization. However, several reports still suggest that postoperative splenectomy may be effective in preventing graft failure in patients with acute antibody-mediated kidney transplant rejection (AAMR) in kidney transplantation. Therefore, we aim to assess if preoperative splenectomy also could be an alternative practical choice to avoid AAMR in high-risk rejection cases such as flow cytometry crossmatch (FCXM)-positive cases.

MATERIAL AND METHOD

We carried out 4 living donor kidney transplantations in FCXM-positive cases: 3 underwent pretransplant splenectomy, and 1 did not.

RESULTS

All 3 cases in whom pretransplant splenectomy was performed were discharged without rejection. On the contrary, in the case where pretransplant splenectomy was not performed, there was graft rejection and additional desensitization therapies were needed.

CONCLUSION

While larger clinical studies with longer observation periods are needed, our report suggested that pretransplant splenectomy may lead to successful short-term kidney transplantation outcomes in FCXM-positive cases.

Long-term outcomes of eculizumab-treated positive crossmatch recipients: Allograft survival, histologic findings, and natural history of the donor-specific antibodies

We aimed to determine the long-term outcomes of eculizumab-treated, positive crossmatch (+XM) kidney transplant recipients compared with +XM and age-matched negative crossmatch (-XM) controls. We performed an observational retrospective study and examined allograft survival, histologic findings, long-term B-cell flow cytometric XM (BFXM), and allograft-loss-associated factors. The mean (SD) posttransplant follow-up was 6.3 (2.5) years in the eculizumab group; 7.6 (3.5), +XM control group; 7.9 (2.5), -XM control group. The overall and death-censored allograft survival rates were similar in +XM groups (P = .73, P = .48) but reduced compared with -XM control patients (P < .001, P < .001). In the eculizumab-treated group, 57.9% (11/19) of the allografts had chronic antibody-mediated rejection, but death-censored allograft survival was 76.6%, 5 years; 75.4%, 7 years. Baseline IgG3 positivity and BFXM ≥300 were associated with allograft loss. C1q positivity was also associated with allograft loss but did not reach statistical significance. Donor-specific antibodies appeared to decrease in eculizumab-treated patients. After excluding patients with posttransplant plasmapheresis, 42.3% (9/21) had negative BFXMs; 31.8% (7/22), completely negative single-antigen beads 1 year posttransplant. Eculizumab-treated +XM patients had reduced allograft survival compared with -XM controls but similar survival to +XM controls. BFXM and complement-activating donor-specific antibodies (by IgG3 and C1q testing) may be used for risk stratification in +XM transplantation.

Antibody-mediated rejection: New approaches in prevention and management

Despite the success of desensitization protocols, antibody-mediated rejection (AMR) remains a significant contributor to renal allograft failure in patients with donor-specific antibodies. Plasmapheresis and high-dose intravenous immunoglobulin have proved to be effective treatments to prevent and treat AMR, but irreversible injury in the form of transplant glomerulopathy can commonly manifest months to years later. There is an unmet need to improve the outcomes for patients at risk for AMR. Updated Banff criteria now take into account the increasing understanding of the complex and heterogeneous nature of AMR phenotypes, including the timing of rejection, subclinical and chronic AMR, C4d-negative AMR, and antibody-mediated vascular rejection. Treatment for AMR is not standardized, and there is little in the way of evidence-based treatment guidelines. Refining more precisely the mechanisms of injury responsible for different AMR phenotypes and establishing relevant surrogate endpoints to facilitate more informative studies will likely allow for more accurate determination of prognosis and efficacious intervention using new therapeutic approaches. In addition to plasma exchange and intravenous immunoglobulin, a number of other add-on therapies have been tried in small studies without consistent benefit, including anti-CD20, proteasome inhibitors, complement inhibitors, anti-interleukin-6 receptor blockers, and immunoglobulin G-degrading enzyme of Streptococcus pyogenes (called IdeS).

Pharmacologic Complement Inhibition in Clinical Transplantation

Purpose of Review

Over the past two decades, significant strides made in our understanding of the etiology of antibody-mediated rejection (AMR) in transplantation have put the complement system in the spotlight. Here, we review recent progress made in the field of pharmacologic complement inhibition in clinical transplantation and aim to understand the impact of this therapeutic approach on outcomes in transplant recipients.

Recent Findings

Encouraged by the success of agents targeting the complement cascade in disorders of unrestrained complement activation like paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS), investigators are testing the safety and efficacy of pharmacologic complement blockade in mitigating allograft injury in conditions ranging from AMR to recurrent post-transplant aHUS, C3 glomerulopathies and antiphospholipid anti-body syndrome (APS). A recent prospective study demonstrated the efficacy of terminal complement inhibition with eculizumab in the prevention of acute AMR in human leukocyte antigen (HLA)-incompatible living donor renal transplant recipients. C1 esterase inhibitor (C1-INH) was well tolerated in two recent studies in the treatment of AMR and was associated with improved renal allograft function.

Summary

Pharmacologic complement inhibition is emerging as valuable therapeutic tool, especially in the management of highly sensitized renal transplant recipients. Novel and promising agents that target various elements in the complement cascade are in development. Graphical Abstractᅟ.

Early Versus Late Acute Antibody-Mediated Rejection Among Renal Transplant Recipients in Terms of Response to Rituximab Therapy: A Single Center Experience

OBJECTIVES

There are no comparable trials concerning the use of rituximab among renal transplant recipients with acute antibody-mediated rejection. Here, we compared early and late acute antibody-mediated rejection in renal transplant recipients in terms of response to rituximab therapy.

MATERIALS AND METHODS

Of 1230 kidney transplants performed at Hamed Al-Essa Organ Transplant Center (Kuwait) over the past 10 years, 103 recipients developed acute antibody-mediated rejections and were subcategorized into 4 groups according to the onset of rejection and rituximab treatment. All patients received the standard treatment for acute antibody-mediated rejection according to our protocol (plasma exchange and intravenous immunoglobulin). We added rituximab to the treatment regimen in 2 groups of patients: 27 patients with early rejection (group 1) and 38 patients with late rejection (group 2). Groups 3 and 4 represented nonrituximab groups, with 20 patients with early (group 3) and 18 patients with late rejection (group 4). We compared the 4 groups regarding graft and patient outcomes.

RESULTS

All patients were comparable regarding patient age, sex, pretransplant type of dialysis, viral profile, type of induction, donor criteria, and pretransplant comorbidities. We observed that delayed and slow graft function were significantly higher in groups 1 and 3 (P = .016); however, we found no significant differences in the 4 groups regarding new-onset diabetes after transplant, BK viral infection, and malignancy. Graft outcomes were significantly better in groups 1 and 2 than in groups 3 and 4 (P = .028). However, patient outcomes were comparable in the 4 groups (P > .05).

CONCLUSIONS

Early acute antibody-mediated rejection in renal transplant recipients had significantly better outcomes when rituximab was added to the standard treatment regimen.

Splenic Irradiation for the Treatment of Severe Antibody-Mediated Rejection

Patients requiring desensitization prior to renal transplantation are at risk for developing severe antibody-mediated rejection (AMR) refractory to treatment with plasmapheresis and intravenous immunoglobulin (PP/IVIg). We have previously reported success at graft salvage, long-term graft survival and protection against transplant glomerulopathy with the use of eculizumab and splenectomy in addition to PP/IVIg. Splenectomy may be an important component of this combination therapy and is itself associated with a marked reduction in donor-specific antibody (DSA) production. However, splenectomy represents a major operation, and some patients with severe AMR have comorbid conditions that substantially increase their risk of complications during and after surgery. In an effort to spare recipients the morbidity of a second operation, we used splenic irradiation in lieu of splenectomy in two incompatible live donor kidney transplant recipients with severe AMR in addition to PP/IVIg, rituximab and eculizumab. This novel approach to the treatment of severe AMR was associated with allograft salvage, excellent graft function and no short- or medium-term adverse effects of the radiation therapy. One-year surveillance biopsies did not show transplant glomerulopathy (tg) on light microscopy, but microcirculation inflammation and tg were present on electron microscopy.

Acute and Chronic Allograft Dysfunction in Kidney Transplant Recipients

Allograft dysfunction after a kidney transplant is often clinically asymptomatic and is usually detected as an increase in serum creatinine level with corresponding decrease in glomerular filtration rate. The diagnostic evaluation may include blood tests, urinalysis, transplant ultrasonography, radionuclide imaging, and allograft biopsy. Whether it occurs early or later after transplant, allograft dysfunction requires prompt evaluation to determine its cause and subsequent management. Acute rejection, medication toxicity from calcineurin inhibitors, and BK virus nephropathy can occur early or later. Other later causes include transplant glomerulopathy, recurrent glomerulonephritis, and renal artery stenosis.

Successful treatment of severe acute antibody-mediated rejection of renal allografts with bortezomib--a report of two pediatric cases

aAMR in renal allografts is uncommon and remains a challenge as it is often refractory to treatment modalities. Aggressive therapy is essential to reverse the rejection as it results in renal allograft loss in approximately 27-40% of cases. There are anecdotal case reports of use of bortezomib, a proteasome inhibitor in the treatment of resistant AMR cases in solid organ transplant recipients; however, the experience is limited. We herein report successful reversal of resistant aAMR in two pediatric patients with bortezomib. Patients were initially treated with IV methylprednisolone pulse therapy with IVIG and PP three times weekly for a total of 10 treatments. After the standard therapy used at our institution persistence of DSA associated with graft dysfunction prompted the use of bortezomib to further treat the rejection. We did not have any neurologic side effects, but one patient did experience significant infections after bortezomib infusions requiring prolonged antimicrobial therapy. The long-term outcome of both children was excellent with preservation of normal renal function and persistent reduction in DSA titers.

Eculizumab and splenectomy as salvage therapy for severe antibody-mediated rejection after HLA-incompatible kidney transplantation

BACKGROUND

Incompatible live donor kidney transplantation is associated with an increased rate of antibody-mediated rejection (AMR) and subsequent transplant glomerulopathy. For patients with severe, oliguric AMR, graft loss is inevitable without timely intervention.

METHODS

We reviewed our experience rescuing kidney allografts with this severe AMR phenotype by using splenectomy alone (n=14), eculizumab alone (n=5), or splenectomy plus eculizumab (n=5), in addition to plasmapheresis.

RESULTS

The study population was 267 consecutive patients with donor-specific antibody undergoing desensitization. In the first 3 weeks after transplantation (median=6 days), 24 patients developed sudden onset oliguria and rapidly rising serum creatinine with marked rebound of donor-specific antibody, and a biopsy that showed features of AMR. At a median follow-up of 533 days, 4 of 14 splenectomy-alone patients experienced graft loss (median=320 days), compared to four of five eculizumab-alone patients with graft failure (median=95 days). No patients treated with splenectomy plus eculizumab experienced graft loss. There was more chronic glomerulopathy in the splenectomy-alone and eculizumab-alone groups at 1 year, whereas splenectomy plus eculizumab patients had almost no transplant glomerulopathy.

CONCLUSION

These data suggest that for patients manifesting early severe AMR, splenectomy plus eculizumab may provide an effective intervention for rescuing and preserving allograft function.

Better understanding of transplant glomerulopathy secondary to chronic antibody-mediated rejection

Transplant glomerulopathy (TG) is generally accepted to result from repeated episodes of endothelial activation, injury and repair, leading to pathological abnormalities of double contouring or multi-layering of the glomerular basement membrane. TG is a major sequel of chronic active antibody-mediated rejection (cABMR), from pre-existing or de novo anti-HLA antibodies. Hepatitis C infection, thrombotic microangiopathy or other factors may also contribute to TG development. TG prevalence is 5-20% in most series, reaching 55%, in some high-risk cohorts, and is associated with worse allograft outcomes. Despite its prevalence and clinical significance, few well-studied treatment options have been proposed. Similar to desensitization protocols, plasmapheresis with or without immunoabsorption, high-dose intravenous immunoglobulin, rituximab, bortezomib and eculizumab have been proposed in the treatment of TG due to cABMR individually or in various combinations. Robust clinical trials are urgently needed to address this major cause of allograft loss. This review summarizes the current knowledge of the epidemiology, etiology, pathology, and the preventive and treatment options for TG secondary to cABMR.

Early clinical complications after ABO-incompatible live-donor kidney transplantation: a national study of Medicare-insured recipients

BACKGROUND

Descriptions of the sequelae of ABO-incompatible (ABOi) kidney transplantation are limited to single-center reports, which may lack power to detect important effects.

METHODS

We examined U.S. Renal Data System registry data to study associations of ABOi live-donor kidney transplantation with clinical complications in a national cohort. Among 14,041 Medicare-insured transplants in 2000 to 2007, 119 non-donor-A2 ABOi transplants were identified. A2-incompatible (n=35) transplants were categorized separately. Infection and hemorrhage events were identified by diagnosis codes on billing claims. Associations of ABO incompatibility with complications were assessed by multivariate Cox regression.

RESULTS

Recipients of ABOi transplants experienced significantly (P<0.05) higher incidence of wound infections (12.7% vs. 7.3%), pneumonia (7.6% vs. 3.8%), and urinary tract infections (UTIs) or pyelonephritis (24.5% vs. 15.3%) in the first 90 days compared with ABO-compatible recipients. In adjusted models, ABO incompatibility was associated with twice the risk of pneumonia (adjusted hazard ratio [aHR], 2.22; 95% confidence interval [CI], 1.14-4.33) and 56% higher risk of UTIs or pyelonephritis (aHR, 1.56; 95% CI, 1.05-2.30) in the first 90 posttransplantation days, and 3.5 times the relative risk of wound infections in days 91 to 365 (aHR, 3.55; 95% CI, 1.92-6.57). ABOi recipients, 19% of whom underwent pre- or peritransplant splenectomy, experienced twice the adjusted risk of early hemorrhage (aHR, 1.96; 95% CI, 1.19-3.24). A2-incompatible transplantation was associated only with early risk of UTIs or pyelonephritis.

CONCLUSION

ABOi transplantation offers patients with potential live donors an additional transplant option but with higher risks of infectious and hemorrhagic complications. Awareness of these complications may help improve protocols for the management of ABOi transplantation.

Transplanting the highly sensitized patient: trials and tribulations

PURPOSE OF REVIEW

Humoral sensitization to antigens of the human leukocyte antigen and ABO systems remains one of the largest barriers to further expansion in renal transplantation. This barrier translates into prolonged waiting time and a greater likelihood of death. The number of highly sensitized patients on the renal transplant waiting list continues to increase. This review focuses on the options available to these patients and speculates on future directions for incompatible transplantation.

RECENT FINDINGS

Desensitization protocols (to remove antibodies), kidney-paired donation (to circumvent antibodies) or a hybrid technique involving a combination of both have broadened the access to transplantation for patients disadvantaged by immunologic barriers. However, the risk of antibody-mediated rejection may be increased and warrants caution. Technical advances in antibody characterization using sensitive bead immunoassays and the C1q assay and therapeutic modalities such as complement inhibitors and proteasome inhibitors have been used to avoid or confront these antibody incompatibilities.

SUMMARY

A growing body of knowledge and literature indicates that these diagnostic and therapeutic modalities can facilitate a safer and more successful treatment course for these difficult-to-treat patients. Rigorous investigations into newer interventions will help in broadening the options for these patients and also expand the living donor pool.

ABO incompatible renal transplants: Good or bad?

ABO incompatible kidney transplantation (ABOi-KT) was previously considered to be an absolute contraindication for patients with end-stage kidney disease (ESKD) due to hyperacute rejection related to blood type barrier. Since the first successful series of ABOi-KT was reported, ABOi-KT is performed increasingly all over the world. ABOi-KT has led to an expanded donor pool and reduced the number of patients with ESKD awaiting deceased kidney transplantation (KT). Intensified immunosuppression and immunological understanding has helped to shape current desensitization protocols. Consequently, in recent years, ABOi-KT outcome is comparable to ABO compatible KT (ABOc-KT). However, many questions still remain unanswered. In ABOi-KT, there is an additional residual immunological risk that may lead to allograft damage, despite using current diverse but usually intensified immunosuppressive protocols at the expense of increasing risk of infection and possibly malignancy. Notably, in ABOi-KT, desensitization and antibody reduction therapies have increased the cost of KT. Reassuringly, there has been an evolution in ABOi-KT leading to a simplification of protocols over the last decade. This review provides an overview of the history, outcome, protocol, advantages and disadvantages in ABOi-KT, and focuses on whether ABOi-KT should be recommended as a therapeutic option of KT in the future.

Impact of donor-specific antibodies on the outcomes of kidney graft: Pathophysiology, clinical, therapy

Allo-antibodies, particularly when donor specific, are one of the most important factors that cause both early and late graft dysfunction. The authors review the current state of the art concerning this important issue in renal transplantation. Many antibodies have been recognized as mediators of renal injury. In particular donor-specific-Human Leukocyte Antigens antibodies appear to play a major role. New techniques, such as solid phase techniques and Luminex, have revealed these antibodies from patient sera. Other new techniques have uncovered alloantibodies and signs of complement activation in renal biopsy specimens. It has been acknowledged that the old concept of chronic renal injury caused by calcineurine inhibitors toxicity should be replaced in many cases by alloantibodies acting against the graft. In addition, the number of patients on waiting lists with preformed anti-human leukocyte antigens (HLA) antibodies is increasing, primarily from patients with a history of renal transplant failure already been sensitized. We should distinguish early and late acute antibody-mediated rejection from chronic antibody-mediated rejection. The latter often manifets late during the course of the post-transplant period and may be difficult to recognize if specific techniques are not applied. Different therapeutic strategies are used to control antibody-induced damage. These strategies may be applied prior to transplantation or, in the case of acute antibody-mediated rejection, after transplantation. Many new drugs are appearing at the horizon; however, these drugs are far from the clinic because they are in phase I-II of clinical trials. Thus the pipeline for the near future appears almost empty.

Acute Antibody-Mediated Rejection in Renal Transplantation: Current Clinical Management

Acute antibody mediated rejection (AMR) is recognized as a major cause of graft loss in renal transplant recipients. Early acute AMR in the first few days after transplantation occurs primarily in sensitized renal transplant recipients with donor-specific alloantibody at the time of transplant and is a relatively "pure" form of acute AMR. Late acute AMR occurs months to years after transplantation and is commonly a mixed cellular and humoral rejection. While there is no consensus regarding optimum treatment, we contend that rational therapeutic approaches are emerging and the acute episode can be managed in most instances. However, new therapies are needed to prevent ongoing chronic injury in these patients.

Late kidney dysfunction in a kidney transplant recipient

Late kidney transplant dysfunction may be a harbinger of graft failure. For many years, calcineurin inhibitor toxicity was felt to be the main cause for graft dysfunction with fibrosis and transplant loss. Recently this idea has come into question. With the observation that peritubular capillary C4d staining in kidney allografts may indicate antibody-mediated injury in conjunction with biopsy study findings, an appreciation for antibody-mediated rejection as a major cause of late graft dysfunction and loss has emerged. Twenty percent to 30% of patients develop de novo donor-specific antibodies after kidney transplantation. There are no US Food and Drug Administration-approved treatments for antibody-mediated rejection, nor have any randomized controlled trials assessed efficacy. Off-label treatment strategies include some combination of plasma exchange, intravenous immunoglobulin, and rituximab. Other approaches, including splenectomy, bortezomib, and eculizumab, have also been tried.

Novel immunosuppressive agents in kidney transplantation

Excellent outcomes have been achieved in the field of renal transplantation. A significant reduction in acute rejection has been attained at many renal transplant centers using contemporary immunosuppressive, consisting of an induction agent, a calcineurin inhibitor, an antiproliferative agent plus or minus a corticosteroid. Despite improvements with these regimens, chronic allograft injury and adverse events still persist. The perfect immunosuppressive regimen would limit or eliminate calcineurin inhibitors and/or corticosteroid toxicity while providing enhanced allograft outcomes. Potential improvements to the calcineurin inhibitor class include a prolonged release tacrolimus formulation and voclosporin, a cyclosporine analog. Belatacept has shown promise as an agent to replace calcineurin inhibitors. A novel, fully-human anti-CD40 monoclonal antibody, ASKP1240, is currently enrolling patients in phase 2 trials with calcineurin minimization and avoidance regimens. Another future goal of transplant immunosuppression is effective and safe treatment of allograft rejection. Novel treatments for antibody mediated rejection include bortezomib and eculizumab. Several investigational agents are no longer being pursed in transplantation including the induction agents, efalizumab and alefacept, and maintenance agents, sotrastaurin and tofacitinib. The purpose of this review is to consolidate the published evidence of the effectiveness and safety of investigational immunosuppressive agents in renal transplant recipients.

Late and chronic antibody-mediated rejection: main barrier to long term graft survival

Antibody-mediated rejection (AMR) is an important cause of graft loss after organ transplantation. It is caused by anti-donor-specific antibodies especially anti-HLA antibodies. C4d had been regarded as a diagnosis marker for AMR. Although most early AMR episodes can be successfully controlled or reversed, late and chronic AMR remains the leading cause of late graft loss. The strategies which work in early AMR have limited effect on late/chronic episodes. Here, we reviewed the lines of evidence that late/chronic AMR is the leading cause of late graft loss, characteristics of late AMR, and current strategies in managing late/chronic AMR. More effort should be put on the management of late/chronic AMR to make a better long term graft survival.

Management of antibody-mediated rejection in transplantation

Despite intensive traditional immunosuppressive therapy, rates of graft loss have approximated 15% to 20% at 1 year following antibody-mediated rejection (AMR) in solid organ transplant recipients. Therefore, the development of antihumoral therapies that provide prompt elimination of donor-specific anti-HLA antibodies and improve allograft survival is an important goal. Traditional treatment modalities for AMR deplete B-cell populations but not the cell at the source of antibody production, the mature plasma cell. Plasma cell-targeted therapies using proteasome inhibition is a novel approach to treating AMR. This review discusses current and emerging treatment modalities used for AMR.

Kidney transplantation across HLA and ABO antibody barriers

PURPOSE OF REVIEW

A significant number of kidney transplantations in industrialized countries is currently performed over human leukocyte antigen (HLA) or ABO antibody barriers after living donation to encounter the increasing shortage of organs from deceased donors. Although patients with moderate titers of anti-A/B antibodies may easily be desensitized with no negative impact on allograft survival, recipients with high titers and HLA sensitized patients demonstrate a substantial risk for antibody-mediated rejection, limiting long-term outcomes.

RECENT FINDINGS

The use of powerful desensitization strategies including plasmapheresis and immunoadsorption, extended therapeutic options such as the application of the recently introduced complement inhibitors, and refined antibody detection techniques may further facilitate transplantations, especially in the HLA-sensitized kidney transplant recipient. On the contrary, special strategies such as the Eurotransplant Acceptable Mismatch Program or kidney paired exchange help improving long-term outcomes in these difficult to transplant patients by circumventing the HLA (or ABO) antibody barrier.

SUMMARY

As compared with waiting for a compatible deceased donor organ, HLA and ABO incompatible transplantations performed in experienced centers have become a reasonable alternative for end-stage kidney disease patients with an incompatible live donor. Whenever possible, however, the transplantation should be performed between ABO compatible donor-recipient pairs in the absence of positive crossmatch results.

Treatment of Late Class II Antibody-Mediated Rejection Status Postkidney Transplantation: Two Case Reports

We are describing the successful treatment of two cases of late Class II antibody mediated rejection status postkidney transplantation. The first patient was treated with a combination of plasmapheresis, intravenous immunoglobulin (IVIG), and stenting of the transplanted renal artery. The second was treated with IVIG and pulse steroids.

The use of bortezomib as a rescue treatment for acute antibody-mediated rejection: report of three cases and review of literature

Antibody-mediated rejection (AMR) typically occurs early after transplantation in approximately 5%-7% of recipients. The literature reports suggest that 12%-37% of kidney transplant recipients with acute AMR do not respond to treatment and eventually lose their grafts. The proteasome inhibitor bortezomib is currently approved by the Food and Drug Administration for the treatment of multiple myeloma. It has been demonstrated both in vitro and in vivo to possess apoptotic properties against mature plasma cells. Herein we have described a series of 3 patients with positive cross-matches who developed early AMR after kidney transplantation. Bortezomib rescue treatment was administered after the patients failed to respond to plasmapheresis/intravenous immunoglobulin and splenectomy. All 3 patients responded with full, durable recovery of renal function. In conclusion, bortezomib is useful to treat refractory AMR after kidney transplantation.

Laparoscopic splenectomy to salvage renal transplants from severe acute antibody-mediated rejection

Purpose. Acute antibody-mediated rejection, a complication of cross match positive and sensitized renal transplants, occurs despite the use of standard desensitization protocols. Rescue therapy consists of plasmapheresis and intravenous immunoglobulin (IVIg). In patients with preformed donor specific antibodies, rejection can be aggressive. We report here a case in which laparoscopic splenectomy was added to the standard rescue regimen. Case Report and Results. A 40-year-old Hispanic female with end stage renal disease had been receiving hemodialysis. The patient had numerous class 1 unacceptable antigens. She was scheduled to undergo an incompatible 1-1-1 mismatch living related donor kidney transplant. Preoperatively, the patient received plasmapheresis, IVIG, and thymoglobulin. There was good graft function until postoperative day 5. At that point, worsening renal function was noted. Renal biopsy was consistent with AMR. The patient became anuric and dialysis was initiated. To salvage the transplant, the patient underwent laparoscopic splenectomy. Postoperatively, renal function improved. Two years after transplant, the patient continues to have excellent graft function. Conclusion. In a small but significant number of renal transplants, antibody production occurs at a rate that traditional treatments are unable to reduce effectively. Based on our experience, the addition of splenectomy to standard rescue therapy can salvage renal transplants.

Human leukocyte antigen antibody incompatible renal transplantation

Anti-human leukocyte antigen (HLA) antibodies are recognized as an important problem in organ transplant recipients. This is because antibodies formed against a graft months or years after implantations are the major cause of late allograft failure, and also because protocols allow the transplantation of some grafts across pre-formed HLA antibodies. Advances in our understanding of anti-HLA antibody- mediated rejection (AMR) have occurred because of a better understanding of the histological findings during AMR; more sensitive and specific methods to measure anti-HLA antibodies; and through clinical investigation of patients transplanted across an HLA barrier. Despite advances in therapy and investigation, AMR remains a major problem and treatment protocols often fail to treat it successfully. This review aims to describe the issues in each of these areas and to suggest how clinicians may be able to improve the management of patients with anti-HLA antibodies.

The role of splenectomy in the setting of refractory humoral rejection after kidney transplantation

Living donor kidney transplantation remains the best option for presensitized recipients to avoid excessive time on the waiting list. However, the possibility for a positive crossmatch with a potential living donor is high. A desensitization protocol may be required to avoid antibody-mediated rejection (AMR). Current protocols are not always effective to prevent AMR and in some cases fail to convert subjects to a negative crossmatch before transplantation. From March 2006 to January 2011, the 11 presensitized patients who displayed AMR after living donor kidney transplantation underwent splenectomy as a rescue procedure due to failure of standard rejection treatments. Splenectomy was considered to be effective in six recipients who normalized their renal function without the need for other immunomodulating therapy. Our analysis suggested that splenectomy can be successfully performed alone or in association with other treatments like bortezomib or rituximab to overcome severe AMR.

Case report: Eculizumab rescue of severe accelerated antibody-mediated rejection after ABO-incompatible kidney transplant

ABO-incompatible (ABOI) living donor kidney transplantation has become a well-accepted practice with standard protocols using perioperative antibody-depleting therapies to lower blood group titers to an acceptable threshold for transplantation. However, a subset of patients will experience accelerated antibody-mediated rejection (AMR) after ABOI kidney transplantation and require aggressive intervention to prevent allograft loss. Here in we report the successful use of terminal complement inhibition with eculizumab to rescue an ABOI kidney allograft with accelerated AMR refractory to salvage splenectomy and daily plasmapheresis. This case emphasizes the fact that, despite close postoperative surveillance and aggressive intervention, graft loss from accelerated AMR after ABOI kidney transplantation remains a very real risk. Eculizumab may offer a graft-saving therapeutic option for isolated cases of severe AMR after ABOI kidney transplantation refractory to standard treatment.

Chain transplantation: initial experience of a large multicenter program

We report the results of a large series of chain transplantations that were facilitated by a multicenter US database in which 57 centers pooled incompatible donor/recipient pairs. Chains, initiated by nondirected donors, were identified using a computer algorithm incorporating virtual cross-matches and potential to extend chains. The first 54 chains facilitated 272 kidney transplants (mean chain length = 5.0). Seven chains ended because potential donors became unavailable to donate after their recipient received a kidney; however, every recipient whose intended donor donated was transplanted. The remaining 47 chains were eventually closed by having the last donor donate to the waiting list. Of the 272 chain recipients 46% were ethnic minorities and 63% of grafts were shipped from other centers. The number of blood type O-patients receiving a transplant (n = 90) was greater than the number of blood type O-non-directed donors (n = 32) initiating chains. We have 1-year follow up on the first 100 transplants. The mean 1-year creatinine of the first 100 transplants from this series was 1.3 mg/dL. Chain transplantation enables many recipients with immunologically incompatible donors to be transplanted with high quality grafts.

Current state of renal transplant immunosuppression: Present and future

For kidney transplant recipients, immunosuppression commonly consists of combination treatment with a calcineurin inhibitor, an antiproliferative agent and a corticosteroid. Many medical centers use a sequential immunosuppression regimen where an induction agent, either an anti-thymocyte globulin or interleukin-2 receptor antibody, is given at the time of transplantation to prevent early acute rejection which is then followed by a triple immunosuppressive maintenance regimen. Very low rejection rates have been achieved at many transplant centers using combinations of these agents in a variety of protocols. Yet, a large number of recipients suffer chronic allograft injury and adverse events associated with drug therapy. Regimens designed to limit or eliminate calcineurin inhibitors and/or corticosteroid use are actively being pursued. An ideal immunosuppressive regimen limits toxicity and prolongs the functional life of the graft. This article contains a critical analysis of clinical data on currently available immunosuppressive strategies and an overview of therapeutic moieties in development.