Role In Antibody-mediated Rejection Research Articles

New treatment for antibody-mediated rejection: interleukin-6 inhibitors.

Following kidney transplantation, antibody-mediated rejection (AMR) occurs when the antibodies of the immune system attack the transplanted organ, leading to damage of the kidney tissue. De novo human leukocyte antigen donor-specific antibodies (HLA-DSAs) play a key role in AMR. Current therapeutic approaches include intravenous immunoglobulin, anti-CD20 antibodies, and plasmapheresis. In cases resistant to treatment, proteasome inhibitors and C5 inhibitors may be employed. Nevertheless, a pressing need exists for new medications to improve transplant survival and reduce complications. In the context of AMR, interleukin (IL)-6 is instrumental in the development and maturation of B cells into plasma cells, which then produce HLA-DSAs targeting the allograft. IL-6 inhibitors are currently under investigation and show promise due to the essential role of IL-6 in the immune response; however, additional research is necessary.

Successful Use of Bortezomib for Recurrent Progressive Familial Intrahepatic Cholestasis Type II After Liver Transplantation: A Pediatric Case with a 9-Year Follow-Up.

Recurrence of progressive familial intrahepatic cholestasis (PFIC) type II poses challenges during postoperative liver transplant care. Posttransplant patients with PFIC type II risk developing recurrent cholestasis with normal gamma-glutamyl transferase activity, which mimics the original bile salt export pump (BSEP) protein deficiency and is related to a form of immunoglobulin G antibody (anti-BSEP)-mediated rejection. Bortezomib effectively induces apoptosis of actively antibody-producing plasma cells that may have a role in antibody-mediated rejection. In this case, we used bortezomib to treat PFIC type II recurrence after liver transplantation in a child.

Antibody-mediated rejection in heart transplantation

The role of antibody-mediated rejection in predicting survival among heart recipients has been studied in clinical transplantology for over 20 years. This condition is a significant risk factor for heart failure and graft vasculopathy. Antibody-mediated rejection results from activation of the humoral immune system and production of donorspecific antibodies that cause myocardial injury through the complement system. The presence of donor-specific antibodies is associated with lower allograft survival. Treatment of antibody-mediated rejection should take into account the rejection category and the presence or absence of graft dysfunction. The main principle of treatment is to suppress humoral immunity at different levels. World clinical practice has made significant inroads into the study of this issue. However, further research is required to identify and develop optimal treatment regimens for patients with humoral rejection in cardiac transplantation.

Sensitization and Desensitization in Vascularized Composite Allotransplantation.

Vascularized composite allotransplantation (VCA) is a field under research and has emerged as an alternative option for the repair of severe disfiguring defects that result from severe tissue loss in a selected group of patients. Lifelong immunosuppressive therapy, immunosuppression associated complications, and the effects of the host immune response in the graft are major concerns in this type of quality-of-life transplant. The initial management of extensive soft tissue injury can lead to the development of anti-HLA antibodies through injury-related factors, transfusion and cadaveric grafting. The role of antibody-mediated rejection, donor-specific antibody (DSA) formation and graft rejection in the context of VCA still remain poorly understood. The most common antigenic target of preexisting alloantibodies are MHC mismatches, though recognition of ABO incompatible antigens, minor histocompatibility complexes and endothelial cells has also been shown to contribute to rejection. Mechanistically, alloantibody-mediated tissue damage occurs primarily through complement fixation as well as through antibody-dependent cellular toxicity. If DSA exist, activation of complement and coagulation cascades can result in vascular thrombosis and infarction and thus rejection and graft loss. Both preexisting DSA but especially de-novo DSA are currently considered as main contributors to late allograft injury and graft failure. Desensitization protocols are currently being developed for VCA, mainly including removal of alloantibodies whereas treatment of established antibody-mediated rejection is achieved through high dose intravenous immunoglobulins. The long-term efficacy of such therapies in sensitized VCA recipients is currently unknown. The current evidence base for sensitizing events and outcomes in reconstructive transplantation is limited. However, current data show that VCA transplantation has been performed in the setting of HLA-sensitization.

O40: PRE-OPERATIVE MANAGEMENT AND SENSITISATION IN VASCULARIZED COMPOSITE ALLOTRANSPLANTATION: A SYSTEMATIC REVIEW

Abstract Introduction Vascularised composite allotransplantation (VCA) permits like-for-like reconstruction following extensive soft tissue injuries. The initial management of extensive soft tissue injury can lead to the development of anti-HLA antibodies through injury, transfusion and cadaveric grafting. The role of antibody-mediated rejection, donor-specific antibodies and graft rejection in the context of VCA remains unclear. This systematic review aimed to determine whether pre-operative management strategies influence immunological outcome following VCA. Method A systematic review of MEDLINE, EMBASE and CINAHL using a PRISMA-compliant methodology up to February 2019 was conducted. Pre-operative, procedural and long-term outcome data were collected and recorded for all VCA recipients on an individual patient basis. Result The search revealed 3,847 records of which 114 met inclusion criteria and reported clinical data related to 100 patients who underwent 129 VCA transplants. Trauma (50%) and burns (15%) were the most frequent indications for VCA. Of all 114 studies, only one reported acute resuscitative management. Fifteen patients (14.7%) were sensitized prior to reconstructive transplantation with an 80% incidence of acute rejection in the first post-operative year. Seven patients demonstrated graft vasculopathy, only one of whom had demonstrated panel reactive antibodies. Conclusion Currently employed acute management strategies predispose to the development of anti-HLA antibodies, adding to the already complex immunological challenge of VCA. Early appropriate care is warranted in patients with extensive soft tissue loss where the resuscitative needs should be balanced against strategies to mitigate the immunological burden, particularly as reconstructive transplantation becomes a feasible option for future soft tissue coverage. Take-home message Acute resuscitative management may sensitise potential transplant recipients following major soft tissue injury. Early appropriate care is warranted.

IgE-Mediated Immune Response and Antibody-Mediated Rejection.

Active antibody-mediated rejection is the main cause of kidney transplant loss, sharing with SLE the alloimmune response and the systemic activation of the IFN-α pathway. IgE-mediated immune response plays a key role in the development of SLE nephritis and is associated with IFN-α secretion. The aim of our study was to investigate IgE-mediated immune response in antibody-mediated rejection. This was a cross-sectional study of 56 biopsy-proven antibody-mediated rejection study participants, 80 recipients with normal graft function/histology (control), 16 study participants with interstitial fibrosis/tubular atrophy, and six participants with SLE. We evaluated graft IgE deposition, tryptase (a mast cell marker), and CD203 (a specific marker of activated basophils) by immunofluorescence/confocal microscopy. In addition, we measured serum concentration of human myxovirus resistance protein 1, an IFN-α-induced protein, and anti-HLA IgE. We observed a significantly higher IgE deposition in tubules and glomeruli in antibody-mediated rejection (1766±79 pixels) and SLE (1495±43 pixels) compared with interstitial fibrosis/tubular atrophy (582±122 pixels) and control (253±50 pixels). Patients with antibody-mediated rejection, but not control patients and patients with interstitial fibrosis/tubular atrophy, presented circulating anti-HLA IgE antibodies, although with a low mean fluorescence intensity. In addition, immunofluorescence revealed the presence of both mast cells and activated basophils in antibody-mediated rejection but not in control and interstitial fibrosis/tubular atrophy. The concentration of circulating basophils was significantly higher in antibody-mediated rejection compared with control and interstitial fibrosis/tubular atrophy. MxA serum levels were significantly higher in antibody-mediated rejection compared with control and correlated with the extent of IgE deposition. Our data suggest that IgE deposition and the subsequent recruitment of basophils and mast cells within the kidney transplant might play a role in antibody-mediated rejection.

Development and outcomes of de novo donor-specific antibodies in low, moderate, and high immunological risk kidney transplant recipients.

De novo donor-specific antibodies (dnDSA) play an important role in antibody-mediated rejection (ABMR) and graft failure, yet their development in kidney transplant recipients (KTx) of higher immunological risk has not been characterized. We prospectively determined the incidence of dnDSA at 3 and 12months posttransplant and assessed their associations with outcomes in recipients stratified by low, moderate, and high immunological risk. Adult KTx were screened for DSA pretransplant, months 3 and 12 posttransplant, and when clinically indicated. Outcomes included incidence of dnDSA, death-censored graft survival (DCGS), and ABMR. Of 371 recipients, 154 (42%) were transplanted across a pretransplant DSA that became undetectable by 12months posttransplant in 78% of cases. dnDSA were detected in 16% (95% confidence interval [CI]: 12-20%) by 3months and 23% (95% CI: 18-29%) by 12months posttransplant. Incidence at 12months was higher in the moderate (30%) and high-risk groups (29%) compared to the low-risk group (16%). dnDSA were associated with an increased risk of ABMR (hazard ratio [HR] 2.2; 95% CI: 1.1-4.4; P=.04) but were not an independent risk factor for DCGS. In conclusion, dnDSA were more frequent in transplant recipients of higher immune risk and associated with an increased risk of ABMR.

The multifaceted role of complement in kidney transplantation.

Increasing evidence indicates an integral role for the complement system in the deleterious inflammatory reactions that occur during critical phases of the transplantation process, such as brain or cardiac death of the donor, surgical trauma, organ preservation and ischaemia-reperfusion injury, as well as in humoral and cellular immune responses to the allograft. Ischaemia is the most common cause of complement activation in kidney transplantation and in combination with reperfusion is a major cause of inflammation and graft damage. Complement also has a prominent role in antibody-mediated rejection (ABMR) owing to ABO and HLA incompatibility, which leads to devastating damage to the transplanted kidney. Emerging drugs and treatment modalities that inhibit complement activation at various stages in the complement cascade are being developed to ameliorate the damage caused by complement activation in transplantation. These promising new therapies have various potential applications at different stages in the process of transplantation, including inhibiting the destructive effects of ischaemia and/or reperfusion injury, treating ABMR, inducing accommodation and modulating the adaptive immune response.

Rethinking de novo immune hepatitis, an old concept for liver allograft rejection: Relevance of glutathione S-transferase T1 mismatch

Antibody-mediated rejection (AMR) in liver transplantation has long been underestimated. The concept of the liver as an organ susceptible to AMR has emerged in recent years, not only in the context of the major histocompatibility complex with the presence of HLA donor-specific antibodies, but also with antigens regarded as “minor”, whose role in AMR has been demonstrated. Among them, antibodies against glutathione S-transferase T1 have been found in 100% of patients with de novo autoimmune hepatitis (dnAIH) when studied. In its latest update, the Banff Working Group for liver allograft pathology proposed replacing the term dnAIH with plasma cell (PC)-rich rejection. Antibodies to glutathione S-transferase T1 (GSTT1) in null recipients of GSTT1 positive donors have been included as a contributory but nonessential feature of the diagnosis of PC-rich rejection. Also in this update, non-organ-specific anti-nuclear or smooth muscle autoantibodies are no longer included as diagnostic criteria. Although initially found in a proportion of patients with PC-rich rejection, the presence of autoantibodies is misleading since they are not disease-specific and appear in many different contexts as bystanders. The cellular types and proportions of the inflammatory infiltrates in diagnostic biopsies have been studied in detail very recently. PC-rich rejection biopsies present a characteristic cellular profile with a predominance of T lymphocytes and a high proportion of PCs, close to 30%, of which 16.48% are IgG4+. New data on the relevance of GSTT1-specific T lymphocytes to PC-rich rejection will be discussed in this review.

Phosphorylated P70 S6 Kinase and S6 Ribosomal Protein Value as Diagnostic Marker of Antibody-mediated Rejection in Lung Allografts: A Multicenter Study

Antibody-mediated rejection (AMR) is emerging as an important cause of solid organ transplantation failure. The role of AMR in lung allografts is a source of ongoing investigation, as well as the identification of more sensitive and accurate diagnostic features. The mammalian target of rapamycin (mTOR) pathway, in particular phosphorylated P70 S6 kinase (S6K) and S6 ribosomal protein (S6RP), is reported to be associated with AMR in heart and kidney transplantation. The main goal of the study was to evaluate S6K and S6RP expression in lung transplanted (LT) patients with AMR from different LT centers.

Polymorphisms in genes related to the complement system and antibody-mediated cardiac allograft rejection

Heart transplantation (HT) is a life-saving treatment for patients with end-stage heart failure. One of the main problems after HT is the humoral response termed antibody-mediated rejection (AMR). Complement activation plays a key role in AMR contributing to graft damage. The aim of this study was to analyze genetic variants in genes related to the complement pathways that could be associated with the development of AMR. Analysis of 51 genes related to the complement pathway was performed by next-generation sequencing in 46 HT recipients, 23 with and 23 without AMR. Statistical analysis was performed with SNPstats and R. We identified 2 single nucleotide polymorphisms, 1 in the mannose-binding lectin 2 gene (p.Gly54Asp-MBL2) and 1 in the complement factor properdin gene (p.Asn428(p=)-CFP), that showed significant association with the absence and development of AMR, respectively. Moreover, the presence of the rare allele in p.Gly54Asp-MBL2 control patients correlated with an immunodeficiency of mannose-binding lectin (6.24 ng/ml vs 207.50 ng/ml, p < 0.01), whereas the presence of the rare allele p.Asn428(p=)-CFP in patients with AMR correlated with higher levels of properdin protein (14.65 μg/ml vs 10.77 μg/ml, p < 0.05). AMR is a complex phenotype affected by many recipient factors. Variants in p.Gly54Asp-MBL2 and p.Asn428(p=)-CFP genes, encoding mannose-binding lectin 2 and properdin, may influence the risk of AMR.

The XIIIth Banff Conference on Allograft Pathology: The Banff 2015 Heart Meeting Report: Improving Antibody-Mediated Rejection Diagnostics: Strengths, Unmet Needs, and Future Directions.

The 13th Banff Conference on Allograft Pathology was held in Vancouver, British Columbia, Canada from October 5 to 10, 2015. The cardiac session was devoted to current diagnostic issues in heart transplantation with a focus on antibody‐mediated rejection (AMR) and small vessel arteriopathy. Specific topics included the strengths and limitations of the current rejection grading system, the central role of microvascular injury in AMR and approaches to semiquantitative assessment of histopathologic and immunophenotypic indicators, the role of AMR in the development of cardiac allograft vasculopathy, the important role of serologic antibody detection in the management of transplant recipients, and the potential application of new molecular approaches to the elucidation of the pathophysiology of AMR and potential for improving the current diagnostic system. Herein we summarize the key points from the presentations, the comprehensive, open and wide‐ranging multidisciplinary discussion that was generated, and considerations for future endeavors.

Inflammation Causes Resistance to Anti-CD20-Mediated B Cell Depletion.

B cells play a central role in antibody-mediated rejection and certain autoimmune diseases. However, B cell-targeted therapy such as anti-CD20 B cell-depleting antibody (aCD20) has yielded mixed results in improving outcomes. In this study, we investigated whether an accelerated B cell reconstitution leading to aCD20 depletion resistance could account for these discrepancies. Using a transplantation model, we found that antigen-independent inflammation, likely through toll-like receptor (TLR) signaling, was sufficient to mitigate B cell depletion. Secondary lymphoid organs had a quicker recovery of B cells when compared to peripheral blood. Inflammation altered the pharmacokinetics (PK) and pharmacodynamics (PD) of aCD20 therapy by shortening drug half-life and accelerating the reconstitution of the peripheral B cell pool by bone marrow-derived B cell precursors. IVIG (intravenous immunoglobulin) coadministration also shortened aCD20 drug half-life and led to accelerated B cell recovery. Repeated aCD20 dosing restored B cell depletion and delayed allograft rejection, especially B cell-dependent, antibody-independent allograft rejection. These data demonstrate the importance of further clinical studies of the PK/PD of monoclonal antibody treatment in inflammatory conditions. The data also highlight the disconnect between B cell depletion on peripheral blood compared to secondary lymphoid organs, the deleterious effect of IVIG when given with aCD20 and the relevance of redosing of aCD20 for effective B cell depletion in alloimmunity.

Evaluation of polyreactive monoclonal antibodies using HLA solid phase assays

It is well established that HLA antibodies play an important role in antibody-mediated rejection (AMR) and there is a growing body of literature demonstrating that non-HLA antibodies may also contribute to AMR. To study the source of non-donor specific HLA antibodies and self-reactive antibodies in patients with kidney graft loss, Porcheray et al. (Am J Transplant 2012; 12: 2088–2097) expanded immortalized polyreactive B-cell clones from a patient with kidney graft rejection and showed that some of these natural antibodies are cross-reactive to HLA and self-antigens. Gao et al. (Am J Transplant 2014; 14:1581–1591) also showed that the presence of IgG natural antibodies, with activity to apoptotic cells, correlates with late kidney allograft loss even after excluding patients with high reactivity to HLA. We have further characterized the HLA reactivity of 4 polyreactive B-cell clones isolated by Porcheray, Gao et al. using solid phase assays (Immucor, Inc.). We report here that while these clones do not react with HLA on the Immucor single antigen beads, they react to other HLA products, with some variation between different solid phase assays. Their reactivity appears to be enhanced upon denaturation, as judged by the monoclonal antibody 210.4, which reacts with denatured antigen, suggesting that they primarily react to cryptic epitopes. B. Ray: Employee; Company/Organization; Immucor.

Clinical Implications of Angiotensin II Type 1 Receptor Antibodies in Antibody-mediated Rejection Without Detectable Donor-specific HLA Antibodies After Renal Transplantation

BackgroundSolid-phase immunoassays have improved detection sensitivity for donor-specific HLA antibody (DSHA) and permitted the accurate diagnosis of antibody-mediated rejection (AMR). However, DSHA is not always sufficient to explain the cause of AMR. Consequently, a means of assessing non-HLA antibodies is required to determine the cause of AMR. The aim of the present study was to evaluate the clinical implications of antibodies (Abs) targeting angiotensin II type I receptor (AT1R) in recipients with AMR but without serum DSHA. MethodsNon-HLA AMR cases diagnosed between January 2011 and June 2014 were included. Levels of anti-AT1R Abs (U/mL) were quantified by using AT1R assay kits (One Lambda, Calif, United States) with collected sera pretransplantation and at biopsy (cut-off value: 15 U/mL). ResultsSeventy-two patients were diagnosed with AMR during the above-mentioned period. Of them, 12 recipients (16.7%) had no DSHA. The sera of these 12 patients were tested (2 patients were only checked at time of biopsy). Nine patients (9/10) were presensitized for anti-AT1R Abs (median, 25.0 U/mL; range, 12.9 to 50.0 U/mL). Ten patients (10/12) were anti-AT1R− positive at time of biopsy (median, 23.2 U/mL; range, 11.4 to 50.0 U/mL). The mean time from transplantation to biopsy was 73 months. Eight patients experienced acute AMR, and 4 developed chronic AMR. Four patients showed negative C4d staining in peritubular capillaries (4/12). Patients were treated with plasmapheresis, low-dose intravenous immunoglobulin, and/or rituximab. ConclusionsAT1R Abs may play a significant role in AMR without detectable DSHA. Pretransplantation detection of AT1R Abs may be helpful for assessing the risk for non-HLA AMR.

Identification and Long-Term Consequences of Antibodies Which Bound C1q in 118 Kidney Transplant Recipients With Donor Specific Antibodies.

Introduction: Donor specific antibodies (DSA) play an important role in antibody-mediated rejection (ABMR) and graft dysfunction. Newer antibody detection assay Luminex® is highly sensitive but not accurately predictive of clinical outcomes. A more precise characterization of potentially harmful DSA is still a matter of concern. Patients and Methods: 118 recipients (8%) among 947 adult kidney transplant followed in Universitary Strasbourg Hospital had a functional graft and DSA in 2011. We identified DSA by Single Antigen Beads (SAB), and analyzed their potential to activate the complement by binding C1q using a Luminex® C1q assay (One Lambda). We correlate these results with the presence of ABMR, kidney biopsy morphological features, C4d staining and graft function. Results: Median follow up of sensitized patients was 8.5±6.5 years (3 months to 31 years). 65/118 patients (55%) were sensitized before transplantation. DSA identified by SAB were mainly class II (72%). 55 patients (47%) had antibodies that bound C1q (DSA C1q+). DSA C1q+ were de novo in 45 patients. Eighty of the 118 patients underwent one or several kidney allograft biopsies for cause (n=135). Mean delay between DSA apparition and kidney biopsy was 4.5±5.4 years.77 biopsies met criteria for ABMR, 29 with lesions of acute rejection and 48 with chronic lesions. 64% of patients with ABMR had DSA C1q+. 76% of patients who did not have ABMR had DSA C1q-. Microcirculation inflammation and chronic lesions were more pronounced in patients with DSA C1q+ than in patients with DSA C1q-, particularly when biopsies were done more than 5 years after DSA occurrence (cg score 1.98±1.3 vs. 0.55±1.1, p=0.0001). C4d staining was positive in 64% of patients with DSA C1q+ and negative in 64% of patients with DSA C1q-. Patients with DSA C1q+ had a poorer graft function (SCr 164 ± 75μmol/l) compared to those with DSA C1q- (SCr 146 ± 57μmol/l). Conclusion:DSA that bound C1q are mainly HLA class II and de novo DSA. Our data suggest that these DSA, as determined by the C1q assay, are associated with greater risk of ABMR, severe chronic tissue injury and allograft dysfunction.

Characterization of a Specific Mechanism for Late Loss of Cardiac Allograft: The Role of Antibody-Mediated Rejection.

Characterization of a Specific Mechanism for Late Loss of Cardiac Allograft: The Role of Antibody-Mediated Rejection.

The Important Roles of C4d in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of various autoantibodies and the injury of multiple systems. It is well known that the complement system plays an important role in the pathogenesis of SLE. Complement activation product C4d is a marker of the classical complement activation and hence can be used to reflect the tissue injury as well as therapeutic effects. Besides its important role in antibody-mediated rejection, C4d has been increasingly recognized as a potential biomarker in SLE. Here we will summarize the recent advances of C4d in SLE.

Rituximab is associated with improved survival in cardiac allograft patients with antibody‐mediated rejection: a single center review

Antibody-mediated rejection (AMR) after cardiac transplantation is associated with significant mortality, and the optimal treatment of this condition is poorly defined. Rituximab has been used successfully for the treatment for antibody-mediated diseases; however, its role in AMR is unclear. We review our experience with rituximab in patients with cardiac allograft AMR. We conducted a retrospective analysis of cardiac transplant patients with a diagnosis of AMR from 2001 to 2011. Inclusion criteria were clinical suspicion of rejection with the presence of C4d complement staining on endomyocardial biopsy and the absence of cellular rejection of grade 2R or greater. Patients were divided into Rituximab and NoRituximab groups. The primary endpoint was all-cause mortality. Secondary endpoints were infection, change in ejection fraction (EF), and rehospitalization. Thirty-three patients met inclusion criteria, of whom 13 received rituximab and 20 did not. Baseline characteristics were similar between groups. Kaplan-Meier curves for a three-yr follow-up period demonstrate improved survival in the Rituximab group (p = 0.0089). There were no differences in secondary endpoints. We found that rituximab therapy was associated with improved survival in cardiac allograft AMR. Further prospective, randomized studies in larger patient populations are needed to confirm this finding and to define ideal timing for rituximab administration.

Unilateral Humoral Rejection After Reoperative Single-Lung Transplant

The role of antibody-mediated rejection in acute and chronic rejection after lung transplantation is poorly understood. We report the case of a prior single-lung transplant recipient undergoing an acute antibody-mediated rejection isolated to her new, contralateral single-lung transplant. A 44-year-old woman 6 years after undergoing a single-lung transplant for idiopathic pulmonary fibrosis underwent a second single-lung transplant for bronchiolitis obliterans syndrome. Despite a negative crossmatch, she subsequently exhibited severe antibody-mediated rejection to her new allograft within 6 days of transplantation. The process of allograft sensitization is dynamic, and further study is warranted to better understand this process.