Human leukocyte antigen and donor-specific antibodies in liver transplantation

In this article,we comment on an article published in a recent issue of the World Journal of Gastroenterology.We specifically focus on the roles of human leukocyte antigen(HLA)and donor-specific antibodies(DSAs)in pediatric liver transpl-antation(LT),as well as the relationship between immune rejection after LT and DSA.Currently,LT remains the standard of care for pediatric patients with end-stage liver disease or severe acute liver failure.However,acute and chronic re-jection continues to be a significant cause of graft dysfunction and loss.HLA mismatch significantly reduces graft survival and increases the risk of acute rejection.Among them,D→R one-way mismatch at three loci was significantly related to graft-versus-host disease incidence after LT.The adverse impact of HLA-DSAs on LT recipients is already established.Therefore,the evaluation of HLA and DSA is crucial in pediatric LT.

Clinical significance of donor-specific human leukocyte antigen antibodies in liver transplantation

Antibody-mediated rejection(AMR) caused by donorspecific anti-human leukocyte antigen antibodies(DSA) is widely accepted to be a risk factor for decreased graft survival after kidney transplantation. This entity also plays a pathogenic role in other solid organ transplants as it appears to be an increasingly common cause of heart graft dysfunction and an emerging issue in lung transplantation. In contrast, the liver appears relatively resistant to DSA-mediated injury. This "immune-tolerance" liver property has been sustained by a low rate of liver graft loss in patients with preformed DSA and by the intrinsic liver characteristics that favor the absorption and elimination of DSA; however, alloantibody-mediated adverse consequences are increasingly being recognized, and several cases of acute AMR after ABO-compatible liver transplant(LT) have been reported. Furthermore, the availability of new solid-phase assays, allowing the detection of low titers of DSA and the refinement of objective diagnostic criteria for AMR in solid organ transplants and particularly in LT, have improved the recognition and management of this entity. A cost-effective strategy of DSA monitoring, avoidance of class Ⅱ human leukocyte antigen mismatching, judicious immunosuppression attached to a higher level of clinical suspicion of AMR, particularly in cases unresponsive to conventional antirejection therapy, can allow a rational approach to this threat.

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 donorspecific-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 posttransplant 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.

Impact of preformed donor-specific antibodies against HLA class Ⅰ on kidney graft outcomes:Comparative analysis of exclusively anti-Cw vs anti-A and/or-B antibodies

AIM To analyze the clinical impact of preformed antiH LA-Cw vs antiH LA-A and/or-B donor-specific antibodies(DSA) in kidney transplantation.METHODS Retrospective study, comparing 12 patients transplanted with DSA exclusively antiH LA-Cw with 23 patients with preformed DSA antiH LA-A and/or B.RESULTS One year after transplantation there were no differencesin terms of acute rejection between the two groups(3 and 6 cases, respectively in the DSA-Cw and the DSA-A-B groups; P = 1). At one year, eG FR was not significantly different between groups(median 59 mL /min in DSA-Cw group, compared to median 51 mL /min in DSA-A-B group, P = 0.192). Moreover, kidney graft survival was similar between groups at 5-years(100% in DSA-Cw group vs 91% in DSA-A-B group, P = 0.528). The sole independent predictor of antibody mediated rejection(AMR) incidence was DSA strength(HR = 1.07 per 1000 increase in MFI, P = 0.034). AMR was associated with shortened graft survival at 5-years, with 75% and 100% grafts surviving in patients with or without AMR, respectively(Log-rank P = 0.005).CONCLUSION Our data indicate that DSA-Cw are associated with an identical risk of AMR and impact on graft function in comparison with "classical" class I DSA.

Donor-specific cell-free DNA as a biomarker in liver transplantation:A review

Due to advances in modern medicine,liver transplantation has revolutionised the prognosis of many previously incurable liver diseases.This progress has largely been due to advances in immunosuppressant therapy.However,despite the judicious use of immunosuppression,many liver transplant recipients still experience complications such as rejection,which necessitates diagnosis via invasive liver biopsy.There is a clear need for novel,minimally-invasive tests to optimise immunosuppression and improve patient outcomes.An emerging biomarker in this‘‘precision medicine’‘liver transplantation field is that of donorspecific cell free DNA.In this review,we detail the background and methods of detecting this biomarker,examine its utility in liver transplantation and discuss future research directions that may be most impactful.

Impact of donor-specific antibodies on long-term graft survival with pediatric liver transplantation

BACKGROUND In a previous paper,we reported a high prevalence of donor-specific antibody(DSA)in pediatric patients with chronic rejection and expressed the need for confirmation of these findings in a larger cohort.AIM To clarify the importance of DSAs on long-term graft survival in a larger cohort of pediatric patients.METHODS We performed a retrospective analysis of 123 pediatric liver transplantation(LT)recipients who participated in yearly follow-ups including Luminex testing for DSA at our center.The cohort was split into two groups according to the DSA status(DSA-positive n=54,DSA-negative n=69).Groups were compared with regard to liver function,biopsy findings,graft survival,need for re-LT and immunosuppressive medication.RESULTS DSA-positive pediatric patients showed a higher prevalence of chronic rejection(P=0.01),fibrosis(P<0.001)and re-transplantation(P=0.018)than DSA-negative patients.Class II DSAs particularly influenced graft survival.Alleles DQ2,DQ7,DQ8 and DQ9 might serve as indicators for the risk of chronic rejection and/or allograft fibrosis.Mean fluorescence intensity levels and DSA number did not impact graft survival.Previous episodes of chronic rejection might lead to DSA development.CONCLUSION DSA prevalence significantly affected long-term liver allograft performance and liver allograft survival in our cohort of pediatric LT.Screening for class II DSAs in combination with assessment of protocol liver biopsies for chronic antibodymediated rejection improved early identification of patients at risk of graft loss.

Blockade of γc Signals in Combination with Donor-specific Transfusion Induces Cardiac Allograft Acceptance in Murine Models

The γc cytokines play an important role in proliferation and survival of T cells. Blocking the γc signals can cause the activated donor-reactive T cells losing the ability to proliferate, and getting into apoptosis pathway, which contributes to induction of the peripheral tolerance. In this study, we induced the transplant tolerance through blocking the γc in combination with donor-specific transfusion (DST) in the cardiac transplantation. Following DST, on the day 2, 4 and 6, C57BL/6 recipients received anti-γc monoclonal antibodies (mAbs) injection, and those in control group were not given anti-γc mAbs. On the day 7, Balb/c cardiac allografts were transplanted. All recipients in experimental group accepted cardiac allografts over 30 days, and two of them accepted allografts without rejection until sacrifice on the 120 day. Animals only receiving DST rejected grafts within 5 days, and the mice receiving cardiac transplantation alone rejected grafts within 9 days. Our study showed that blockade of γc signaling combined with DST significantly prolonged allograft survival, which was probably associated with inhibition of antigen-specific T-cell proliferation and induction of apoptosis.

Use of donor-specific red blood cell transfusions for patients undergoing liver transplantation during the COVID-19 pandemic

Background:Increased risks have been found for patients undergoing liver transplantation due to the blood supply shortage following the ongoing coronavirus disease 2019(COVID-19)pandemic.Hence,exploring a method to alleviate this dilemma is urgent.This phase I,nonrandomized,prospective trial aimed to evaluate the safety and feasibility of using donor-specific red blood cell transfusion(DRBCT)as an urgent measurement to alleviate the blood supply shortage in deceased donor liver transplantation(DDLT).Methods:The outcomes of 26 patients who received DRBCT and 37 patients in the control group who only received 3rd party packed red blood cells(pRBCs)transfusion between May 2020 and January 2021 were compared.Results:Patients receiving DRBCT did not develop transfusion-related complications,and the incidence of postoperative infection was similar to that in the control group(23.1%vs.18.9%,P=0.688).Because the patients received the red blood cells from organ donors,the median volume of intraoperative allogeneic red blood cell transfusion from blood bank was 4.0 U(IQR 1.1-8.0 U)in the DRBCT group,which is significantly lower than that(7.5 U,IQR 4.0-10.0 U)in the control group(P=0.018).The peak aspartate aminotransferase(AST)level was significantly lower in the DRBCT group than in the control group(P=0.008)and so were the AST levels in the first two days after the operation(P=0.006 and P=0.033).Conclusions:DRBCT is a safe and effective procedure to lower the need for blood supply and is associated with a reduction in AST levels after transplantation.DRBCT is beneficial to patients receiving life-saving transplantation without sufficient blood supply during the COVID-19 pandemic.

Detecting donor-specific antibodies: the importance of sorting the wheat from the chaff

Human leukocyte antigen(HLA)compatibility is very important for successful transplantation of solid organs.In this paper,we focused on the humoral arm of immunity in the clinical setting of organ transplantation:how HLA antibodies develop,how they can be detected,and what they can do to injure organ transplants.Specifically,we explore the technical perspectives of detecting donor-specific antibodies(DSA)in HLA laboratories,and use real-life clinical cases to explain the principles.Currently there are many tools in our HLA antibody detection toolbox:conventional cytotoxicity cross match,flow cross match,and solid phase assays using beads conjugated with single or multiple HLA antigens.Single antigen bead(SAB)assay is the most sensitive tool available for detecting HLA antibodies and assessing the immunological risk for organ transplant.However,there are intrinsic limitations to solid-phase assays and they are prone to both false negativity and importantly,false positivity.Denatured antigens on single antigen beads might be the most prominent source of false positive reactivity,and may have been underestimated by many HLA experts.No single assay is perfect and therefore multiple methods,including the less sensitive assays,should be employed to determine the clinical relevance of detected HLA antibodies.Thoughtful process,including knowledge of HLA systems,cross reactivity,epitopes,and the patient's clinical history should be employed to correctly interpret data.The clinical team should work closely with HLA laboratories to ensure accurate interpretation of information and optimal management of patients before and after organ transplantation.

Donor-specific antibodies,glomerulitis,and human leukocyte antigen B eplet mismatch are risk factors for peritubular capillary C4d deposition in renal allografts

Background:The complement system plays an important role in the immune response to transplantation,and the diagnostic significance of peritubular capillary(PTC)C4d deposition(C4d+)in grafts is controversial.The study aimed to fully investigate the risk factors for PTC C4d+and analyze its significance in biopsy pathology of kidney transplantation.Methods:This retrospective study included 124 cases of kidney transplant with graft biopsy and donor-specific antibody(DSA)testing from January 2017 to December 2019 in a single center.The effects of recipient pathological indicators,eplet mismatch(MM),and DSAs on PTC C4d+were examined using univariate and multivariate logistic regression analyses.Results:In total,35/124(28%)were PTC C4d+,including 21 with antibody-mediated rejection(AMR),eight with renal tubular injury,three with T cell-mediated rejection,one with glomerular disease,and two others.Univariate analysis revealed that DSAs(P<0.001),glomerulitis(P<0.001),peritubular capillaritis(P<0.001),and human leukocyte antigen(HLA)B eplet MM(P=0.010)were the influencing factors of PTC C4d+.According to multivariate analysis,DSAs(odds ratio[OR]:9.608,95%confidence interval[CI]:2.742–33.668,P<0.001),glomerulitis(OR:3.581,95%CI:1.246–10.289,P=0.018),and HLA B eplet MM(OR:1.166,95%CI:1.005–1.353,P=0.042)were the independent risk factors for PTC C4d+.In receiver operating characteristic curve analysis,the area under the curve was increased to 0.831 for predicting PTC C4d+when considering glomerulitis,DSAs,and HLA B eplet MM.The proportions of HLA I DSAs and PTC C4d+in active antibody-mediated rejection were 12/17 and 15/17,respectively;the proportions of HLA class II DSAs and PTC C4d+in chronic AMR were 8/12 and 7/12,respectively.Furthermore,the higher the PTC C4d+score was,the more serious the urinary occult blood and proteinuria of recipients at the time of biopsy.Conclusions:PTC C4d+was mainly observed in AMR cases.DSAs,glomerulitis,and HLA B eplet MM are the independent risk factors for PTC C4d+.

Romidepsin(FK228) improves the survival of allogeneic skin grafts through downregulating the production of donor-specific antibody via suppressing the IRE1α-XBP1 pathway

Antibody-mediated rejection(AMR)is one of the major causes of graft loss after transplantation.Recently,the regulation of B cell differentiation and the prevention of donor-specific antibody(DSA)production have gained increased attention in transplant research.Herein,we established a secondary allogeneic in vivo skin transplant model to study the effects of romidepsin(FK228)on DSA.The survival of grafted skins was monitored daily.The serum levels of DSA and the number of relevant immunocytes in the recipient spleens were evaluated by flow cytometry.Then,we isolated and purified B cells from B6mouse spleens in vitro by magnetic bead sorting.The B cells were cultured with interleukin-4(IL-4)and anti-clusters of differentiation 40(CD40)antibody with or without FK228 treatment.The immunoglobulin G1(IgG1)and IgM levels in the supernatant were evaluated by enzyme-linked immunosorbent assay(ELISA).Quantitative reverse transcription-polymerase chain reaction(RT-q PCR)and western blotting were conducted to determine the corresponding levels of messenger RNA(mRNA)and protein expression in cultured cells and the recipient spleens.The results showed that FK228 significantly improved the survival of allogeneic skin grafts.Moreover,FK228 inhibited DSA production in the serum along with the suppression of histone deacetylase 1(HADC1)and HDAC2 and the upregulation of the acetylation of histones H2A and H3.It also inhibited the differentiation of B cells to plasma cells,decreased the transcription of positive regulatory domain-containing 1(Prdm1)and X-box-binding protein 1(Xbp1),and decreased the expression of phosphorylated inositol-requiring enzyme 1α(p-IRE1α),XBP1,and B lymphocyte-induced maturation protein-1(Blimp-1).In conclusion,FK228 could decrease the production of antibodies by B cells via inhibition of the IRE1α-XBP1 signaling pathway.Thus,FK228 is considered as a promising therapeutic agent for the clinical treatment of AMR.

Human leukocyte antigen compatibility and incidence of donorspecific antibodies in pediatric liver transplant recipients

BACKGROUND Antibody-mediated rejection following liver transplantation(LT)has been increasingly recognized,particularly with respect to the emergence of de novo donor-specific antibodies(DSAs)and their impact on graft longevity.While substantial evidence for adult populations exists,research focusing on pediatric LT outcomes remains limited.AIM To investigate the prevalence of human leukocyte antigen(HLA)mismatches and DSA and evaluate their association with rejection episodes after pediatric LT.METHODS A cohort of pediatric LT recipients underwent HLA testing at Santa Casa de Porto Alegre,Brazil,between December 2013 and December 2023.Only patients who survived for>30 days after LT with at least one DSA analysis were included.DSA classes I and II and cross-matches were analyzed.The presence of de novo DSA(dnDSA)was evaluated at least 3 months after LT using the Luminex®single antigen bead method,with a positive reaction threshold set at 1000 MFI.Rejection episodes were confirmed by liver biopsy.RESULTS Overall,67 transplanted children were analyzed;61 received grafts from living donors,85%of whom were related to recipients.Pre-transplant DSA(class I or II)was detected in 28.3%of patients,and dnDSA was detected in 48.4%.The median time to DSA detection after LT was 19.7[interquartile range(IQR):4.3-35.6]months.Biopsyproven rejection occurred in 13 patients at follow-up,with C4d positivity observed in 5/13 Liver biopsies.The median time to rejection was 7.8(IQR:5.7-12.8)months.The presence of dnDSA was significantly associated with rejection(36%vs 3%,P<0.001).The rejection-free survival rates at 12 and 24 months were 76%vs 100%and 58%vs 95%for patients with dnDSA anti-DQ vs those without,respectively.CONCLUSION Our findings highlight the importance of incorporating DSA assessment into pre-and post-transplantation protocols for pediatric LT recipients.Future implications may include immunosuppression minimization strategies based on this analysis in pediatric LT recipients.

Early plasmapheresis and rituximab for acute humoral rejection after ABO-compatible liver transplantation

Acute humoral rejection （AHR） is uncommon after ABO- compatible liver transplantation. Herein, we report two cases of AHR treated with plasmapheresis and rituximab in two ABO-compatible liver-transplant patients with preformed anti-human leukocyte antigen donor-specific antibodies. Patient 1 experienced a biopsy-proven AHR at day 10 post-transplant. She was treated by steroid pulses, and OKT3. Because of persisting signs of biopsy-proven AHR at day 26, she was treated by plasmapheresis and rituximab. Uver enzyme levels did not improve, and she died on day 41. Patient 2 experienced a biopsy-proven AHR on day 10 post-transplant. She was treated by steroid pulses, plasmapheresis, and rituximab. Liver enzymes returned to within normal range 18 d after diagnosis. Uver biopsies, at 3 and 9 mo post-transplant, showed complete resolution of AHR. We conclude that plasmapheresis should be started as soon as AHR is diagnosed, and be associated with a B-cell depleting agent. Rituximab may be considered as a first-line therapy.

Chronic rejection after liver transplantation:Opening the Pandora’s box

Chronic rejection(CR)of liver allografts causes damage to intrahepatic vessels and bile ducts and may lead to graft failure after liver transplantation.Although its prevalence has declined steadily with the introduction of potent immunosuppressive therapy,CR still represents an important cause of graft injury,which might be irreversible,leading to graft loss requiring re-transplantation.To date,we still do not fully appreciate the mechanisms underlying this process.In addition to T cell-mediated CR,which was initially the only recognized type of CR,recently a new form of liver allograft CR,antibody-mediated CR,has been identified.This has indeed opened an era of thriving research and renewed interest in the field.Liver biopsy is needed for a definitive diagnosis of CR,but current research is aiming to identify new non-invasive tools for predicting patients at risk for CR after liver transplantation.Moreover,the minimization or withdrawal of immunosuppressive therapy might influence the establishment of subclinical CR-related injury,which should not be disregarded.Therapies for CR may only be effective in the“early”phases,and a tailored management of the immunosuppression regimen is essential for preventing irreversible liver damage.Herein,we provide an overview of the current knowledge and research on CR,focusing on early detection,identification of non-invasive biomarkers,immunosuppressive management,re-transplantation and future perspectives of CR.

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(dn AIH) when studied. In its latest update, the Banff Working Group for liver allograft pathology proposed replacing the term dn AIH 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 diseasespecific 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 Ig G4+. New data on the relevance of GSTT1-specific T lymphocytes to PC-rich rejection will be discussed in this review.

Acute antibody-mediated rejection after intestinal transplantation

AIM To investigate the incidence, risk factors and clinical outcomes of acute antibody-mediated rejection(ABMR) after intestinal transplantation(ITx).METHODS A retrospective single-center analysis was performed to identify cases of acute ABMR after ITx, based on the presence of donor-specific antibody(DSA), acute tissue damage, C4 d deposition, and allograft dysfunction.RESULTS Acute ABMR was identified in 18(10.3%) out of 175 intestinal allografts with an average occurrence of 10 d(range, 4-162) after ITx. All acute ABMR cases were presensitized to donor human leukocyte antigens class Ⅰand/or Ⅱ antigens with a detectable DSA. A positive cross-match was seen in 14(77.8%) cases and twelve of 18 patients(66.7%) produced newly-formed DSA following ITx. Histological characteristics of acute ABMR include endothelial C4 d deposits, interstitial hemorrhage, and severe congestion with focal fibrin thrombin in the lamina propria capillaries. Multivariate analysis identified a liver-free graft and high level of panel reactive antibodyas a significant independent risk factor. Despite initial improvement after therapy, eleven recipients(61.1%) lost transplant secondary to rejection. Of those, 9(50%) underwent graft removal and 4(22.2%) received second transplantation following acute ABMR. At an average follow-up of 32.3 mo(range, 13.3-76.4), 8(44.4%) recipients died.CONCLUSION Our results indicate that acute ABMR is an important cause of intestine graft dysfunction, particularly in a liver-exclusive graft and survivors are at an increased risk of developing refractory acute rejection and chronic rejection. More effective strategies to prevent and manage acute ABMR are needed to improve outcomes.

Importance of human leukocyte antigen antibodies and leukocyte antigen/killer-cell immunoglobulin-like receptor genes in liver transplantation

Many mechanisms have been proposed to explain the hypothetical state of hepatic tolerance,which is described by eventual imbalances or deregulation in the balance of cytokines,mediators,effectors,and regulatory cells in the complex milieu of the liver.In this section,we will comment on the importance of donorspecific anti-human leukocyte antigen(HLA)antibodies(DSA)as well as the compatibility and pairings of HLA and killer-cell immunoglobulin-like receptor(KIR)genotypes in the evolution of liver transplantation.Thus,HLA compatibility,viral infections,and HLA-C/KIR combinations have all been linked to liver transplant rejection and survival.There have been reports of increased risk of acute and chronic rejection with ductopenia,faster graft fibrosis,biliary problems,poorer survival,and even de novo autoimmune hepatitis when DSAs are present in the recipient.Higher mean fluorescence intensity(MFI)values of the DSAs and smaller graft size were associated with poorer patient outcomes,implying that high-risk patients with preformed DSAs should be considered for selecting the graft placed and desensitization methods,according to the investigators.Similarly,in a combined kidney-liver transplant,a pretransplant with a visible expression of several DSAs revealed that these antibodies were resistant to treatment.The renal graft was lost owing to antibody-mediated rejection(AMR).The HLA antigens expressed by the transplanted liver graft influenced antibody elimination.Pathologists are increasingly diagnosing AMR in liver transplants,and desensitization therapy has even been employed in situations of AMR,particularly in patients with DSAs in kidney-hepatic transplants and high-class II MFI due to Luminex.In conclusion,after revealing the negative impacts of DSAs with high MFI,pretransplant virtual crossmatch techniques may be appropriate to improve evolution;however,they may extend cold ischemia periods by requiring the donor to be typed.

Minimization vs tailoring:Where do we stand with personalized immunosuppression during renal transplantation in 2015?

The introduction of novel immunosuppressive agents over the last two decades and the improvement of our diagnostic tools for early detection of antibodymediated injury offer us an opportunity, if not a mandate, to better match the immunosuppression needs of the individual patients with side effects of the therapy. However, immunosuppressive regimens in the majority of programs remain mostly protocol-driven, with relatively little inter-program heterogeneity in certain areas of the world. Emerging data showing different outcomes with a particular immunosuppressive strategy in populations with varying immunological risks underscore a real potential for "personalized medicine" in renal transplantation. Studies demonstrating marked differences in the adverse-effect profiles of individual drugs including the risk for viral infections, malignancy and renal toxicity call for a paradigm shift away from a "one size fits all" approach to an individually tailored immunosuppressive therapy for renal transplant recipients, assisted by both screening for predictors of graft loss and paying close attention to dose or class-related adverse effects. Our paper explores some of the opportunities during the care of these patients. Potential areas of improvements may include:(1) a thorough assessment of immunological and metabolic risk profile of each renal transplant recipient;(2) screening for predictors of graft loss and early signs of antibody-mediated rejection with donor-specific antibodies, protocol biopsies and proteinuria(including close follow up of adverse effects with dose adjustments or conversions as necessary); and(3) increased awareness of the possible link between poor tolerance of a given drug at a given dose and non-adherence with the prescribed regimen. Altogether, these considerations may enable the most effective use of the drugs we already have.

Treatment with plasmapheresis, immunoglobulins and rituximab for chronic-active antibody-mediated rejection in kidney transplantation: Clinical, immunological and pathological results

AIM To evaluate the role of a therapeutic regimen with plasma exchange, intravenous immunoglobulins and rituximab in chronic-active antibody-mediated rejection(c AMR) settings.METHODS We compared 21 kidney transplant recipients(KTRs) with a diagnosis of c AMR in a retrospective casecontrol analysis: nine KTRs treated with plasmapheresis, intravenous immunoglobulins and rituximab(PE-IVIGRTX group) vs 12 patients(control group) not treated with antibody-targeted therapies. We examined kidney survival and functional outcomes 24 mo after diagnosis. Histological features and donor-specific antibody(DSA) characteristics(MFI and C1 q-fixing ability) were also investigated.RESULTS No difference in graft survival between the two groups was noted: three out of nine patients in the PE-IVIG-RTX group(33.3%) and 4/12 in the control group(33.3%) experienced loss of allograft function at a median time after diagnosis of 14 mo(min 12-max 18) and 15 mo(min 7-max 22), respectively. Kidney functional tests and proteinuria 24 mo after cA MR diagnosis were also similar in both groups. Only microvascular inflammation(glomerulitis + peritubular capillaritis score) was significantly reduced after PE-IVIG-RTX in seven out of eight patients(87.5%) in the PE-IVIG-RTX group(median score 3 in pre-treatment biopsy vs 1.5 in post-treatment biopsy; P = 0.047), without any impact on kidney survival and/or DSA characteristics. No functional or histological parameter at diagnosis was predictive of clinical outcome.CONCLUSION Our data showed no difference in the two year posttreatment outcome of kidney grafts treated with PE-IVIGRTX for c AMR diagnosis, however there were notable improvements in microvascular inflammation in posttherapy protocol biopsies. Further studies, especially involving innovative therapeutic approaches, are required to improve the management and long-term results of this severe condition.

ICOS-Ig combined with CsA induces long term survival of cardiac allografts in mouse

Objective： To study the synergistic effect of ICOS-Ig combined with cyclosporine （CsA） on mouse heart transplantation and explore its therapeutic potential. Methods： ICOS-Ig fusion protein was generated by fusing the extraeellular portion of human ICOS and Fc portion of human IgG. To investigate the effect of ICOS-Ig on T-cell proliferation in vitro, ICOS-Ig or IgG was added to the primary MLR cultures （BALB/c spleen T cells as responder cells and irradiated C57BL/6 spleen cells as stimulator cells）. The cells responsiveness rates were detected by 3H-TdR methods. Then the T cells of each group in primary MLR were cultured as responder cells for secondary MLR, and irradiated C57BL/6 （donor） or C3H （third party） spleen cells as stimulator cells. To study the effect of ICOS-Ig on T-cell proliferation in vivo, CFSE-labeled C57BL/6 spleen cells were transferred to irradiated BALB/c mice. Mice were then treated with IgG, ICOS-Ig or CsA. Seventy two hours after transfer, the spleen cells of the mice were harvested for the detection of CD4^＋CFSE^＋ and CD8^＋CFSE^＋ by FACS. C57BL/6 mouse underwent transplantation of the hearts of BALB/c mouse and were then randomly divided into five equal groups： no treatment group, control lgG treated group （250 gg i.p. d2, 4, 6）, ICOS-Ig treated group （250 μg i.p. d2, 4, 6）, CsA treated group （10 mg/kg i.p. d0-6）, ICOS-Ig combined with CsA group. The cardiac allograft survival was monitored by daily palpation. Results： In primary MLR, ICOS-Ig inhibited T-cell proliferation, （inhibition ratio 58i8.2% in 50 μg/ml）. In secondary MLR, ICOS-Ig specifically inhibited donor spleen cells, which suggested ICOS-Ig could induce donor-specific hyporesponsiveness. In the CFSE dye assay, CD4^＋CFSE^＋ and CD8^＋CFSE^＋ in ICOS-Ig and CsA group was stronger than those in control group, which showed ICOS-Ig and CsA could inhibit the proliferation of allo-reactive T cells in vivo. In mouse heart transplantation model, survival was significantly prolonged in animals treated with ICOS-Ig or CsA as compared with controls. Moreover, ICOS-Ig combined with CsA group had even longer engraftment （〉100 d） than ICOS-Ig or CsA used alone. In histological examination, it was found that there were congestions and edemas in no treatment and IgG treated recipients, together with a lot of inflammatory cells infiltrated. Allogeneic hearts from ICOS-Ig and/or CsA immunized recipients revealed milder histological changes. It was revealed in mechanical analysis that splenic T cells from recipients also exhibited depressed mixed leukocyte reactions （MLR） and cytotoxic lymphocyte reactions （CTL）. Conclusion： These data suggest that ICOS-Ig combined with CsA induces a long-term survival of mouse cardiac allografts, whereas monotherapy is less effective in this regard. Thus, ICOS-Ig combined with CsA treatment may be a novel regimen to combat allograft rejection.