Treatment Of Antibody-mediated Rejection Research Articles

Therapeutic Effects and Functional Mechanism of Intravenous Immunoglobulin in Preclinical Rat Renal Transplant Model of Antibody-Mediated Rejection

BackgroundIntravenous immunoglobulin (Ig) therapy is used based on empirical findings for treatment of antibody-mediated rejection (AMR) in cases of renal transplantation, although its therapeutic efficacy has not been proven and the functional mechanism of an administered Ig remains elusive. In this study, the therapeutic effects of an Ig were examined in a preclinical rat renal transplant model of AMR to investigate this mechanism. MethodsTo establish an AMR renal graft model, skin graft specimens were obtained from Brown-Norway (BN) rats and transplanted to Lewis rats to produce donor-specific antibodies (DSAs), after which kidney transplantation from the Brown-Norway to Lewis rats was performed. AMR model rats were administered the Ig at a dose of 2 g/kg or saline as a control. Survival period, renal graft histopathology, complement factors, and DSA levels were assessed. ResultsThe survival period of the group administered the Ig was significantly prolonged. Histopathological examinations of renal grafts also showed significant suppression of glomerulitis and peritubular capillaritis in the Ig group, and real-time polymerase chain reaction analysis results demonstrated significantly lower levels of expression of the complement factors C1q and C3. When the Ig was given to rats that underwent skin grafting but not renal transplantation, DSA was decreased after 6 hours and remained lower than the baseline level for at least 7 days. ConclusionIg administration suppressed DSA production. The present results showed that suppression of the complement system contributed to effective Ig treatment for AMR.

Short-term Immunopathological Changes Associated with Pulse Steroids/IVIG/Rituximab Therapy in Late Kidney Allograft Antibody Mediated Rejection.

B-cell depletion is a common treatment of antibody-mediated rejection (ABMR). We sought to determine the specific immunopathologic effects of this therapeutic approach in kidney transplantation. This was a prospective observational study of kidney transplant recipients diagnosed with late ABMR (>3 months after transplant). Patients received treatment with pulse steroids, IVIG, and rituximab. Donor specific HLA antibodies (DSA), kidney allograft pathology, renal function, immune cell phenotypes, and 47 circulating cytokines were assessed at baseline and at three months. We enrolled 23 patients in this study between April 2015 and March 2019. The majority of patients were male (74%) and Caucasian (78%) with an average age of 45.6±13.8 years. ABMR was diagnosed at 6.8±5.9 years (4 months-25 years) post-transplant. Treatment was associated with a significant decline in circulating HLA class I DSA (P=0.003) and class II DSA (P=0.002) and peritubular capillaritis (ptc, P=0.04) compared to baseline. Serum creatinine, BUN, eGFR, and proteinuria (UPC) remained stable. Circulating B-cells were depleted to barely detectable levels (P≤0.001), whereas BAFF (P=0.001), APRIL (P<0.001), and IL-10 (P=0.02), levels increased significantly post-treatment. Notably, there was a significant rise in circulating CD4+ (P=0.02) and CD8+ T-cells (P=0.003). We also noted a significant correlation between circulating cytotoxic CD8+ T-cells and BAFF (P=0.05), regulatory T-cells and IL10 (P=0.002), and HLA class I DSA (P=0.005). Short-term pulse steroids/IVIG/rituximab therapy was associated with inhibition of ABMR (DSA and ptc), stabilization of kidney function, and increased regulatory B-cell and T-cell survival cytokines. Additional studies are needed to understand the implications of B cell-depletion on the crosstalk between T-cells, B-cells, and humoral components that regulate ABMR.

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.

Efficacy and Safety of Tocilizumab in the Treatment of Acute Active Antibody-mediated Rejection in Kidney Transplant Recipients.

Background.Antibody-mediated rejection (AMR) continues to have a deleterious impact on kidney allograft survival. Recent evidence supports use of tocilizumab for treatment of chronic active AMR, but it has not been assessed for treatment of acute active AMR.Methods.We performed a single-center, observational study of kidney transplant recipients who received at least 1 dose of tocilizumab in addition to conventional therapies for acute active AMR between October 2016 and October 2018 with follow-up through August 2019.Results.Seven patients were included. All 7 patients received tocilizumab 8 mg/kg (max dose, 800 mg) monthly. We noted a 50% or greater reduction in immunodominant donor-specific antibodies in 4 of 6 patients. Renal function improved or stabilized in all patients throughout the duration of therapy. One patient developed cytomegalovirus esophagitis and 1 had a potential hypersensitivity reaction. In the extended follow-up, 1 patient had mixed rejection and 2 patients had T-cell–mediated rejection, which occurred 6 to 24 mo after completion of therapy.Conclusions.Tocilizumab may be considered as an addition to conventional therapies for treatment of acute active AMR. More studies are needed to determine which patients may benefit from therapy and to examine the appropriate duration of treatment.

Evaluation of Carfilzomib for Antibody Mediated Rejection in Lung Transplant Recipients

Though definition and recognition of antibody mediated rejection (AMR) in lung transplant (LTx) has improved over the past few years, treatment of AMR remains poorly defined. Data supporting use of carfilzomib (CFZ) for treatment of AMR in combination with plasmapheresis and intravenous immunoglobulin (IVIG) suggest positive outcomes through donor specific antibody (DSA) depletion or conversion to noncomplement-activating antibodies. The aim of this retrospective analysis was to describe our center's experience treating AMR with CFZ. All adult LTx recipients who received CFZ for AMR from 2014-2018 were included. Patients were excluded if they received CFZ prior to transplant for desensitization. Per institution protocol, all patients received induction with basiliximab followed by maintenance immunosuppression with tacrolimus, mycophenolate, and prednisone. Acute rejection was diagnosed on trans-bronchial lung biopsy at week 2 and months 1, 2, 3, 6, 8, and 12 post-transplant, or when bronchoscopy was performed for clinical indication. Frequency of DSA checks and decision to use CFZ was per clinician discretion. A positive response to CFZ was defined as: 1) loss of DSA C1q-fixing ability after last CFZ dose, 2) clearance of de novo DSA (dnDSA) or 3) decrease in dnDSA MFI of >3000. Data on pulmonary function, infections, and incidence of acute kidney injury were also collected. During the study period, 21 patients with 24 AMR episodes were treated with CFZ in combination with plasmapheresis and IVIG. A positive response to CFZ was observed in 70.8% of AMR episodes and 76.1% of patients. This response was driven by loss of C1q-fixation (69.2%), elimination of class I DSAs (60.0%), and reduction in class II DSA MFI (median 3621, 26% reduction from baseline). Analysis of responders to CFZ revealed that delaying therapy with CFZ for ≥30 days after dnDSA development was associated with lack of response to therapy (p=0.002). Our cohort is the largest to date describing use of CFZ for treatment of AMR in LTx. The positive response the majority of our patients experienced was determined by decrease in both class I and II DSA MFI, elimination of dnDSAs, and reversal of C1q positivity. Larger prospective studies investigating the ideal time from dnDSA development to initiating AMR treatment, and defining the most appropriate time to utilize CFZ are needed.

Immunoadsorption for Treatment of Antibody Mediated Rejection after Lung Transplantation

Antibody mediated rejection (AMR) has recently emerged as an important risk factor for lung allograft dysfunction and mortality. Several clinical protocols have been proposed to try to remove donor specific antibodies (DSA) and prevent their future development, including intravenous immunoglobulin (IVIG), therapeutic plasma exchange (TPE), rituximab and other. Unlike traditional TPE, immunoadsorption (IAS) is a blood-purification technique that enables the selective removal of immunoglobulins from separated plasma through high-affinity adsorbers; advantageously, IAS does not remove other plasma components such as fibrinogen and compounds of the coagulation cascade, reducing potential adverse effects. Our centre implemented a multimodality strategy including steroids, immunoadsorbption, IVIG and Rituximab. All adult lung transplant (LuTx) recipients receiving a diagnosis of AMR (based on 2016 ISHLT consensus definition), were considered eligible to receive this treatment: pulsed methylprednisolone (10 mg/Kg), 5 cycles of IAS, IVIG (2 g/Kg) and rituximab (375 mg/m^2). Of note, C4d staining is not currently available at our institution. Between 2016 and 2018, four patients received multimodality antibody directed therapy for AMR after LuTx. Details can be found in table 1. 2 out of the 4 patients qualified for chronic lung allograft dysfunction (CLAD) prior to protocol start (patient 1 and 3). No adverse events were registered during IAS procedures, but patient 3 suffered transfusion related acute lung injury while receiving IVIG. However, patient 3's death was attributed to progressive allograft failure and not to the therapy itself. Following this treatment, while the total number of the original DSA and the value of MFI of the originally observed DSA decreased, clinical outcomes were variable: 2 patients are experiencing long term clinical stability, but the others rapidly progressed to severe CLAD.

Outcome of Extracorporeal Photopheresis as Add-On Therapy in Patients for Antibody-Mediated Rejection after Lung Transplantation

The diagnosis and treatment of antibody-mediated rejection (AMR) after LTx has gained increasing recognition within the transplant community. Extracorporeal photopheresis (ECP) modulates various pathways of the immune system and is currently used to treat CLAD. In AMR, adding ECP to established AMR treatments could potentially prevent rebound of DSA. This study aimed to analyze the role of ECP as adjunct treatment of AMR. Patients who developed antibody-mediated rejection between 2009 and 2019 were included in this single-center retrospective analysis. The following parameters were evaluated: DSAs, C4d deposition and lung histology. A total of 39 patients developed clinical AMR during follow-up. Nineteen (48%) patients had positive DSA against HLA Class I and eighteen (46%) HLA Class II. Median time to diagnosis of AMR was 180 days (IQR: 2-2477). First line treatment was immunoadsorption (IA) in 34 (87%) patients, intravenous immunoglobulins with concomitant immunoadsorption in 3 (8%) patients and in 2 cases ATG. Twenty (51%) patients primarily treated with IA and the two patients treated with ATG received ECP. Among the patients treated with ECP, 12 had DSA against HLA Class I and 13 against HLA Class II. ECP treatment was initially performed twice a week. After stabilization of lung function and improvement of clinical situation, ECP was then performed once a month for a minimum of 6 months. Median length of treatment was 12 months. Patients who received ECP after first line treatment had 1-year survival rate of 62% compared to 27% of other AMR patients. In all patients treated with IA followed by ECP, DSA disappeared or MFI reduced below our institutional threshold of 5000. Extracorporeal photopheresis is associated with a reduction of de novo DSA after antibody-mediated rejection. Prospective studies are necessary to confirm the beneficial effect of ECP as an add-on therapy after AMR.

Treatment and Pattern of Resolution of Antibody-Mediated Rejection with Hemodynamic Compromise Resistant to Standard Therapy after Heart Transplantation with a Positive Virtual Crossmatch

Antibody-mediated rejection (AMR) with hemodynamic compromise (HC, heart failure requiring inotropic support) after heart transplantation (HT) confers a significant risk of allograft failure and poor survival. Standard therapy (plasmapheresis and thymoglobulin) to mitigate and/or treat AMR has been variably effective. In January 2018, we embarked on a prospective treatment strategy using Bortezomib, Eculizumab, and consolidation therapy using total lymphoid irradiation (TLI) for standard therapy-resistant AMR (ST-R AMR) with HC. Bortezomib was given in conjunction with plasmapheresis every 3 days x5 doses over 2 weeks and Eculizumab was given weekly x4 doses then spaced to monthly. Consolidation therapy with TLI (2x/week for 5 weeks) was started when rejection episode was resolving defined as improving hemodynamics (filling pressures and echocardiogram) and improvement in histological features of AMR. Total protocol duration was 44-68 days. Donor-specific antibody (DSA) specificity and mean-fluorescence intensity (MFI) was determined using Luminex. Antibody strength was assessed by change in neat and 1:25 dilution MFI. Four virtual crossmatch-positive patients with ST-R AMR and HC were treated. Three of four patients were CDC-crossmatch positive. Median time to AMR diagnosis was 6 days (4-13) and initiation of the protocol was 13 days (8-22) post-HT. Median times to reduction in DSA was 27 days (27-29), improvement in cardiac function was 31 days (7-42), and time to start of TLI was 38 days (21-56). Median time to resolution C4d staining was 64 days (50-69). Three of four patients survived and underwent consolidation with TLI and none have had recurrence of AMR after treatment (6-19 months post-HT). One patient who died 38 days post-HT had persistent histological evidence of endothelial damage on biopsy despite clearance of C4d deposition, persistently elevated filling pressures, progressive systolic dysfunction, rebound increase in DSA, and multi-organ failure. This pilot study shows this protocol may be an effective treatment of ST-R AMR with lasting effects many months post-HT. Initial improvement in DSA and cardiac function can be seen in weeks, but complete resolution of C4d staining may take additional weeks to months.

Angiotensin II Type 1 Receptor Antibody Mediated Rejection Following Orthotopic Heart Transplant: A Single Center Experience

Antibody mediated rejection (AMR) following heart transplant (OTHx) causes significant morbidity and mortality. In particular, diagnosis and management of non-HLA AMR remains challenging. Antibodies to the angiotensin II type 1 receptor (AT1R) causing rejection after kidney transplant have been described, but there is limited data on AT1R-Ab mediated rejection following OHTx. Here, we present our single center experience. We retrospectively reviewed all OHTx cases from the past 2 years with clinically suspected AMR without evidence of canonical donor-specific AMR who had a positive AT1R-Ab titer. Clinical and pathological features were documented. We identified 7 patients, the majority were female (71%), African American (71%), and had prior LVAD support (71%). All patients had NICM pretransplant. Patients presented both early (∼2 weeks) and late (∼7 years) with heart failure; 3 patients presented within 1 year post OHTx. Echocardiography showed progressive graft dysfunction, primarily decreased EF, ventricular wall thickening, and diastolic dysfunction. The average AT1R-Ab titer was 22U/mL at 1:100 dilution (range: 3 to >40 U/mL). Biopsies showed reactive endothelium and increased interstitial macrophages, without pathologic AMR features (negative C4d and <10% intravascular macrophages by CD68). Five patients were empirically treated with plasmapheresis, IVIG and rituximab. One patient did not tolerate plasmapheresis, and treatment was deferred on one patient given low titers and clinical improvement with standard heart failure treatment. All patients were started on an angiotensin receptor blocker (ARB). There were no deaths, and the majority of patients had clinically significant improvement in symptoms and graft function following treatment with an ARB at an average 6 months of follow-up. AT1R-Ab mediated rejection is an underdiagnosed and emerging entity following OHTx that remains ill-defined; it requires a high index of suspicion and should be considered for all OHTx recipients with evidence of graft dysfunction or decompensation. Empiric AMR treatment followed by oral ARB therapy anecdotally improves patient outcomes; however, future studies are needed to better define the pathophysiology, long-term clinical sequelae, and optimal treatment modalities of this disease.

Antibody-Mediated Rejection Treatment With Bortezomib in Renal Transplant Recipients: A Single-Center 24-Month Follow-up Case Report

IntroductionAntibody-mediated rejection (AMR) is related to a poor prognosis in graft survival, with 27% to 40% of patients experiencing graft loss within the first year. The mechanism of damage in AMR is mediated by donor-specific antibodies (DSA). No standard treatment for AMR exists, and conventional management includes high doses of steroids, plasmapheresis, intravenous immunoglobulin, and either rituximab or bortezomib. Because of the high cost of these medications and the lack of prospective studies to evaluate their efficacy and safety, their routine use is limited. In the following study, we describe the use of bortezomib for the treatment of AMR in 5 renal transplant recipients with a 24-month follow-up and compare this case with the reviewed literature. Material and MethodsFive cases of AMR diagnosed by biopsy are reported, and these patients received bortezomib at a rate of 1.3 mg/m2 on days 1, 4, 8, and 11; plasmapheresis; and 1 patient received 30 g of intravenous immunoglobulin. ResultsAll patients received his or her first transplant; 4 were from a cadaveric donor, and 1 patient received thymoglobulin at a standard dose. All patients had maintenance therapy based on cyclosporine, mycophenolate mofetil, and prednisone, with an average baseline creatinine level of 1.3 mg/dL. The average days until rejection event were 952 days. Discussion and ConclusionAMR treatment with bortezomib was effective, showing stable renal function at 24 months. Patients had adequate tolerance for administration. So far, these results contrast with the literature reviewed, so additional studies and follow-up are required for a new evaluation.

Serum dilutions as a predictive biomarker for peri-operative desensitization: An exploratory approach to transplanting sensitized heart candidates

Antibody-mediated rejection (AMR) of cardiac allografts mediated by anti-HLA Donor Specific Antibodies (DSA) is one of the major barriers to successful transplantation for the treatment of end-stage heart failure. Therapeutic plasma exchange (TPE) is a first-line treatment for pre-transplant desensitization. However, indications for treatment regimens and treatment end-points have not been well established. In this study, we investigated how sera dilutions could guide TPE regimens for effective peri-operative desensitization and early AMR treatment. Our data show that 1:16 dilutions of EDTA-treated sera and 1.5 volume TPE reduce anti-HLA class I and class II antibody levels in the same manner and, therefore, allows to predict which antibodies would respond to peri-operative TPE. We successfully applied this approach to transplanting three highly sensitized cardiac recipients (CPRA 85–93%) with peri-operative desensitization based on a virtual crossmatch performed on 1:16 diluted serum. Furthermore, we have used sera dilutions to guide DSA treatment post-transplant. Although these findings have to be confirmed in a larger prospective study, our data suggest that serum dilutions can serve as a predictive biomarker to guide peri-operative desensitization and post-transplant immunologic management.

Complement-Based Therapy in the Management of Antibody-Mediated Rejection.

Antibody-mediated rejection (AMR) is one of the leading causes of kidney allograft failure and is usually mediated by anti-human leukocyte antigen donor-specific antibodies (DSAs). Activation of classical pathway of the complement system is responsible for downstream effects of DSA and account for significant manifestations of AMR. Currently, the treatment of AMR is based on strategies to remove preformed antibodies or to prevent their production; however, these strategies are often unsuccessful. It is theoretically possible to inhibit complement activity to prevent the effect of DSA on kidney allograft function. Complement inhibitors such as eculizumab, a complement 5 monoclonal antibody, and complement 1 esterase inhibitors (C1 INHs) have been used in prevention and treatment of AMR with variable success. Eculizumab and C1 INH seem to reduce the incidence of early AMR and allow transplantation in highly sensitized kidney transplant recipients, but data on their long-term effect on kidney allograft function are limited. Several case reports described the successful use of eculizumab in the treatment of AMR, but there are no randomized controlled studies that showed efficacy. Treatment of AMR with C1 INH, in addition to standard of care, did not change short-term outcome but long-term studies are underway.

Antibody-mediated rejection after lung transplantation.

Antibody-mediated rejection (AMR) has been identified as a significant form of acute allograft dysfunction in lung transplantation. The development of consensus diagnostic criteria has created a uniform definition of AMR; however, significant limitations of these criteria have been identified. Treatment modalities for AMR have been adapted from other areas of medicine and data on the effectiveness of these therapies in AMR are limited. AMR is often refractory to these therapies, and graft failure and death are common. AMR is associated with increased rates of chronic lung allograft dysfunction (CLAD) and poor long-term survival. In this review, we discuss the history of AMR and describe known mechanisms, application of the consensus diagnostic criteria, data for current treatment strategies, and long-term outcomes. In addition, we highlight current gaps in knowledge, ongoing research, and future directions to address these gaps. Promising diagnostic techniques are actively being investigated that may allow for early detection and treatment of AMR. We conclude that further investigation is required to identify and define chronic and subclinical AMR, and head-to-head comparisons of currently used treatment protocols are necessary to identify an optimal treatment approach. Gaps in knowledge regarding the epidemiology, mechanisms, diagnosis, and treatment of AMR continue to exist and future research should focus on these aspects.

Evaluation and Treatment of Acute Rejection in Kidney Allografts.

Advances in immunosuppressive therapy have drastically improved acute rejection rates in kidney transplant recipients over the past five decades. Nevertheless, it should remain high on any differential diagnosis of unexplained graft dysfunction because of the potential negative effect on graft longevity. Understanding the pre- and post-transplant risk factors for acute rejection can help estimate the probability of immunologic graft damage, and accurate identification of the type and severity of acute rejection will guide appropriate treatment. Tissue biopsy remains the gold standard for evaluating immunologic graft damage, and the histologic definition of acute rejection has evolved in recent years. Intravenous steroids and T cell depletion remain the standard therapy for T cell-mediated rejection and are effective in reversing most cases. Plasma exchange and intravenous Ig, with or without rituximab, are most commonly used for the treatment of antibody-mediated rejection and several newer agents have recently been investigated for severe cases. This review aims to provide the general nephrologist caring for transplant recipients with an approach to immunologic risk assessment and a summary of recent advances in the diagnosis and treatment of acute graft rejection.

The Preliminary Results of Bortezomib Used as A Primary Treatment for An Early Acute Antibody-Mediated Rejection after Kidney Transplantation-A Single-Center Case Series.

Proteasome inhibitor bortezomib has been used in the treatment of refractory cases of acute and chronic antibody-mediated rejection (AMR) in kidney transplant recipients. However, its efficacy and safety as a primary treatment for early AMR has been scarcely investigated. We herein present our preliminary experience with bortezomib- and plasmapheresis-based primary treatment for early AMR. Thirteen patients transplanted between October 2015 and September 2019 were treated (starting at median 19th post-transplant day) with bortezomib/plasmapheresis protocol for early biopsy-proven AMR. Twelve out of thirteen patients received 4 doses and one patient recieved 3 doses of bortezomib (1.3 mg/m2 per dose). In 11/13 patients, 4–7 concomitant plasmapheresis sessions were performed, with or without intravenous immunoglobulin (IVIG). Of note, rituximab was not used in all study patients. The kidney graft and patient survival were 100%. The mean 3-month estimated glomerular filtration rate (eGFR) was 55.3 (95%CI: 44.9–65.8) mL/min/1.73m2, 8/13 patients completed 12-month follow-up with mean eGFR 60.4 (45.4–75.4) mL/min/1.73m2, and 6/13 patients completed a 24-month follow-up period with mean eGFR 73.9 (56.7–91.1) mL/min/1.73m2. Neutropenia < 1 G/L was observed in one patient, third or fourth grade thrombocytopenia in two patients, and eleven patients needed a blood transfusion (median: 2 units/patient). The mid-term results of a primary bortezomib-based treatment for kidney AMR showed its non-inferiority as compared to preceding regimens and acceptable safety. However, our data should be validated in a multicenter randomized trial.

Precise treatment of acute antibody-mediated cardiac allograft rejection in rats using C4d-targeted microbubbles loaded with nitric oxide

Antibody-mediated rejection (AMR) constitutes an important cause of cardiac allograft loss; however, all current therapeutic strategies represent systemic applications with unsatisfactory efficacy. Previously, we successfully non-invasively detected C4d, a specific marker for AMR diagnosis, in allografts using C4d-targeted microbubbles (MBC4d). In this study, we extended this approach by incorporating nitric oxide (NO), as high NO levels manifest immunosuppressive and anti-thrombotic effects. We designed novel MBC4d loaded with NO (NO-MBC4d). A rat model of AMR was established by pre-sensitization with skin transplantation. Contrast-enhanced ultrasound (CEUS) images were obtained and quantitatively analyzed following NO-MBC4d injection. Allograft survival and histologic features were analyzed to evaluate the therapeutic effect and underlying mechanism of NO-MBC4d toward AMR. We successfully obtained CEUS images following NO-MBC4d injection and demonstrated that the ultrasound signal intensity of the myocardial area and clearance time of NO-MBC4d both increased with increased C4d grade, thereby realizing non-invasive diagnosis of AMR. Furthermore, allograft survival was significantly prolonged, and rejection was obviously attenuated following NO-MBC4d injection through significant suppression of thrombosis and reduction of inflammatory cell infiltrates. Overall, the therapeutic efficacy was significantly improved in the NO-MBC4d group compared with the control NO-MB group, demonstrating that precise treatment could significantly improve the therapeutic efficacy compared with that afforded by systemic applications. This study presented a novel tool to provide simultaneous non-invasive diagnosis and precise treatment of AMR using NO-MBC4d CEUS imaging, which may be expected to provide a better option for recipients with AMR in clinic.

Outcome of Extracorporeal Photopheresis as an Add-On Therapy for Antibody-Mediated Rejection in Lung Transplant Recipients

Introduction: The diagnosis and treatment of antibody-mediated rejection (AMR) after lung transplantation has recently gained recognition within the transplant community. Extracorporeal photopheresis (ECP), currently used to treat chronic lung allograft dysfunction, modulates various pathways of the immune system known to be involved in AMR. We hypothesize that adding ECP to established AMR treatments could prevent the rebound of donor-specific antibodies (DSA). Objectives: This study aimed to analyze the role of ECP as an add-on therapy to prevent the rebound of DSA. Methods: Lung transplant recipients who received ECP as an add-on therapy for pulmonary AMR between January 2010 and January 2019 were included in this single-center retrospective analysis. Baseline demographics of the patients, as well as their immunological characteristics and long-term transplant outcomes, were analyzed. Results: A total of 41 patients developed clinical AMR during the study period. Sixteen patients received ECP as an add-on therapy after first-line AMR treatment. Among the 16 patients, 2 (13%) had pretransplant DSA, both against human leukocyte antigen (HLA) class I (B38, B13, and C06). Fifteen patients (94%) developed de novo DSA (dnDSA), i.e., 10 (63%) against class I and 14 (88%) against class II. The median time to dnDSA after lung transplantation was 361 days (range 25–2,548). According to the most recent International Society of Heart and Lung Transplantation (ISHLT) consensus report, 2 (13%) patients had definite clinical AMR, 6 (38%) had probable AMR, and 7 (44%) had possible AMR. The median mean fluorescence intensity (MFI) of dnDSA at the time of clinical diagnosis was 4,220 (range 1,319–10,552) for anti-HLA class I and 10,953 (range 1,969–27,501) for anti-HLA class II antibodies. ECP was performed for a median of 14 cycles (range 1–64). MFI values of dnDSA against HLA classes I and II were significantly reduced over the treatment period (for anti-class I: 752; range 70–2,066; for anti-class II: 5,612; range 1,689–21,858). The 1-year survival rate was 55%. No adverse events related to ECP were reported in any of the patients. Conclusions: ECP is associated with a reduction of dnDSA in lung transplant recipients affected by AMR. Prospective studies are warranted to confirm the beneficial effects of ECP in the setting of AMR.

Results of a nationwide survey in Japan on the status of antibody-mediated rejection treatment and the use of rituximab in that treatment

Results of a nationwide survey in Japan on the status of antibody-mediated rejection treatment and the use of rituximab in that treatment

Imlifidase Inhibits HLA Antibody-mediated NK Cell Activation and Antibody-dependent Cell-mediated Cytotoxicity (ADCC) In Vitro.

Antibody-dependent cell-mediated cytotoxicity (ADCC) is an important pathway responsible for antibody-mediated rejection (AMR). Imlifidase (IdeS) cleaves human IgG into F(ab')2 and Fc fragments, potentially inhibiting ADCC. Here we examined the effect of IdeS on allo-antibody-mediated NK cell activation (Allo-CFC) and ADCC in vitro. For Allo-CFC, normal whole blood was incubated with third-party peripheral blood mononuclear cells (PBMCs) pretreated with anti-HLA antibody positive (HS) or negative (NC) sera to measure IFNγ+ NK cell%. For ADCC, normal PBMCs were incubated with Farage B (FB) cells with HS or NC sera to measure 7-AAD+ lysed FB cell%. To assess the effect of IdeS on these assays, serum-treated PBMCs (Allo-CFC-1) and serum used for PBMC pretreatment (Allo-CFC-2) in Allo-CFC, and serum used for ADCC were preincubated with IdeS. Sera from IdeS-treated patients were also tested for Allo-CFC (Allo-CFC-3). IFNγ+ NK cell% were significantly elevated in HS versus NC sera in Allo-CFC-1 (10 ± 3% versus 2 ± 1%, P = 0.001), Allo-CFC-2 (20 ± 10% versus 4 ± 2%, P = 0.01) and 7AAD+ FB cell% (11 ± 3% versus 4 ± 2%, P = 0.02) in ADCC. These were significantly reduced by IdeS treatment. Patient sera with significantly reduced anti-HLA antibody levels at 1 day postimlifidase lost the capacity to activate NK cells in Allo-CFC-3, but those at 1-3 months postimlifidase regained the capacity. IdeS inhibited NK cell activation and ADCC in vitro and in treated patients. These results and reported inhibition of complement activating anti-HLA antibodies by IdeS suggest its possible role in treatment of AMR.

Therapeutic Apheresis in Prevention and Treatment of Antibody-Mediated Rejection of Renal Allografts

Antibody-mediated rejection represents a significant barrier to favourable long-term outcomes after kidney transplantation and is the most common cause of allograft failure. Therapeutic apheresis techniques associated with other treatments, such as immunosuppressive drugs, are commonly used in the prevention and treatment of antibody-mediated injury in pre- and post-transplant protocols. The rationale is related to the removal of donor-specific antibodies as well as other inflammatory mediators, including cytokines, chemokines, complement degradation molecules, and immunomodulatory effects also which determine an increased susceptibility of cell-mediated and humoral immunity to immunosuppressive agents. In this review article, we discuss current knowledge in the use of therapeutic apheresis in the prevention and management of antibody-mediated rejection, in combination with known and other emerging biological immunosuppressive therapies.