Acute Rejection Grade Research Articles

Transition from Transbronchial Forceps to Cryobiopsy After Lung Transplantation: A Single-Centre Experience.

The gold standard for histological acute cellular rejection diagnosis is transbronchial forceps biopsy (FB), but in recent years, transbronchial cryobiopsy (CB) has been increasingly used. This study aims to compare the diagnostic rate and safety of FBs and CBs performed in two different periods. We retrospectively reviewed our case history for the two biopsy procedures: 251 FBs (223 for surveillance purposes and 28 for clinical indication) and 218 consecutive CBs (159 for surveillance purposes and 59 for clinical indication). All biopsies were scored according to the ISHLT criteria. Diagnostic yield was higher in the CB group for all the parameters considered: a grade of acute rejection (AR) was detected in 95.0% vs. 84.5% in the CB vs. FB groups (p < 0.001). The diagnostic rate of airway inflammation was 65.1% vs. 51.8% (p = 0.005), and 89.0% vs. 64.9% (p < 0.001) for chronic rejection. Pneumothorax requiring chest drainage occurred in 4% of the CB group and 3% of the FB group. Moderate and severe bleeding complicated CB and FB procedures in seven (3%) and three cases (1%), respectively. Transbronchial cryobiopsies improved the diagnostic yield in the monitoring of the lung allograft. The complication rate did not increase significantly in CBs vs. FBs.

Disulfiram, an Anti-alcoholic Drug, Targets Macrophages and Attenuates Acute Rejection in Rat Lung Allografts.

Macrophages contribute to post-transplant lung rejection. Disulfiram (DSF), an anti-alcoholic drug, has an anti-inflammatory effect and regulates macrophage chemotactic activity. Here, we investigated DSF efficacy in suppressing acute rejection post-lung transplantation. Male Lewis rats (280-300g) received orthotopic left lung transplants from Fisher 344 rats (minor histocompatibility antigen-mismatched transplantation). DSF (0.75mg/h) monotherapy or co-solvent only (50% hydroxypropyl-β-cyclodextrin) as control was subcutaneously administered for 7 days (n = 10/group). No post-transplant immunosuppressant was administered. Grades of acute rejection, infiltration of immune cells positive for CD68, CD3, or CD79a, and gene expression of monocyte chemoattractant protein and pro-inflammatory cytokines in the grafts were assessed 7 days post-transplantation. The DSF-treated group had significantly milder lymphocytic bronchiolitis than the control group. The infiltration levels of CD68+ or CD3+ cells to the peribronchial area were significantly lower in the DSF than in the control groups. The normalized expression of chemokine ligand 2 and interleukin-6 mRNA in allografts was lower in the DSF than in the control groups. Validation assay revealed interleukin-6 expression to be significantly lower in the DSF than in the control groups. DSF can alleviate acute rejection post-lung transplantation by reducing macrophage accumulation around peripheral bronchi and suppressing pro-inflammatory cytokine expression.

P8.052: Long-term Outcomes and Predictors of Graft Function in Living-Donor Preemptive Kidney Transplants

Background: Beyond the new strategies for dialysis treatment, kidney transplantation has already been associated with better outcomes for patients with advanced kidney chronic disease (CKD), and a preemptive kidney transplant seems to be the preferred option for those patients. Thus, this study purposed to evaluate predictors of long-term graft function and unfavorable outcomes in living-donor preemptive kidney transplant recipients. Methods: Single-center cohort study enrolled 222 living-donor preemptive kidney transplant recipients transplanted between 2011 and 2016 and followed up to 2021. Five-year graft function was estimated by CKD-Epi (5-year-eGFR). The primary outcome was composed of death, graft loss, acute rejection, and 5-year-eGFR < 30 mL/min/1.73m2. The multivariable analysis for 5-year-eGFR was performed by linear regression and logistic regression for the primary outcome. Results: Recipients were 40 (31; 48) years old, 59.9% were male, and 35.1% had CKD due to chronic glomerulonephritis. Donors were 48.5 (41.0; 55.2) years old, being most frequently siblings (50%) or parents (28/8%). One-third of patients received ATG as an induction strategy (30.2%), followed by Tacrolimus + azathioprine (59.5%) or cyclosporin + azathioprine (14.4%) or tacrolimus + mycophenolate (11.3%) as the maintenance immunosuppression. The overall incidence of acute rejection, graft loss, and death was 20.3%, 6.3%, and 0.5%, respectively. The median follow-up time was 88.9 months, and the median 5-year-eGFR was 54.7 mL/min. Sixty-five patients presented the primary outcome (29.2%), significantly associated with the HLA compatibility, not using induction therapy and CMV-related event. Compared with identical HLA matches, the OR was 6.81 for haploidentical (P=0.001) and 11.2 for distinct (P<0.001) HLA matches. In addition, the probability for the primary outcome was reduced by 81% (OR= 0.19, p<0.001) for patients who received ATG as induction therapy and 4-fold higher in those who had CMV-related events (OR=4.09; p=0.001). In the linear regression, the association with 5-yr-eGFR was less evident with HLA matches and AR than donor age. Thus, the identical HLA (B= +6.04; p=0.09) match and AR (B=-6.34; p=0.07) tend to be associated with 5-year-eGFR in the linear regression, while donor age (B= -0,69 per year old; p<0.001) presented a significant and inverse association. Conclusion: In recipients of living-donor preemptive kidney transplants, the HLA matches, thymoglobulin induction therapy, and CMV-related events were predictors of composite outcomes of long-term death, graft loss, acute rejection, and low grade of graft function. In addition, only donor age was independently associated with long-term graft function.

Therapeutic Drug Monitoring of Tacrolimus-Personalized Therapy in Heart Transplantation: New Strategies and Preliminary Results in Endomyocardial Biopsies

Tacrolimus (TAC) is an immunosuppressant drug approved both in the US and in the EU, widely used for the prophylaxis of organ rejection after transplantation. This is a critical dose drug: low levels in whole blood can lead to low exposure and a high risk of acute rejection, whereas overexposure puts patients at risk for toxicity and infection. Both situations can occur at whole-blood concentrations considered to be within the narrow TAC therapeutic range. We assumed a poor correlation between TAC trough concentrations in whole blood and the incidence of acute rejection; therefore, we propose to study TAC concentrations in endomyocardial biopsies (EMBs). We analyzed 70 EMBs from 18 transplant recipients at five scheduled follow-up visits during the first year post-transplant when closer TAC monitoring is mandatory. We observed five episodes of acute rejection (grade 2R) in three patients (2 episodes at 0.5 months, 2 at 3 months, and 1 at 12 months), when TAC concentrations in EMBs were low (63; 62; 59; 31; 44 pg/mg, respectively), whereas concentrations in whole blood were correct. Our results are preliminary and further studies are needed to confirm the importance of this new strategy to prevent acute rejection episodes.

Validation of Systematic Histologic Reporting of Transbronchial Biopsy Eosinophils for Sensitivity of Detection and Associations with Early Outcomes After Lung Transplant

<h3>Purpose</h3> Eosinophils are reported in 8% of transbronchial biopsies (TBBx) and their presence is associated with an increased risk of CLAD and death. We aimed to validate a systematic reporting scheme for the presence, gradation, and pattern of TBBx eosinophils. <h3>Methods</h3> A prospective reporting scheme for TBBx eosinophils was introduced at St Vincent's Sydney in Jan-20. All TBBx were reported by blinded pathologists for the presence of eosinophils, histologic pattern (peribronchial, interstitial, perivascular) and count/high power field (HPF). Standardised reporting was compared with a historic TBBx cohort from Jan-Dec 2019. TBBx were classified for cellular rejection as per ISHLT guidelines and positive bronchoalveolar lavage (BAL) microbiology/eosinophils and blood eosinophil count was recorded. Multivariable logistic regression measured associations with an increased risk of TBBx eosinophils. <h3>Results</h3> A total of 213 TBBx from 93 lung transplant recipients were systematically reviewed, with 61.5% as surveillance procedures. The mean (SD) recipient age was 52 (13), with 96 (45%) males, at median (IQR) 85 (475) days after transplant. TBBx eosinophils were detected in greater proportions with systematic (27.7%) compared to historic reporting (5.6%) p<0.001. When present, eosinophils were detected in median (IQR) 18.0% (19) biopsy specimens with median (IQR) 2 (5) cell/HPF. TBBx eosinophil patterns were reported in the following proportions; Interstitial 64%, perivascular 7%, peribronchial 25%. In univariable analysis, A grade (OR 3.11 p<0.01), blood eosinophils (OR 13.28 p=0.04) and BAL microbiology (OR 2.15 p=0.02) were associated with increased risk of TBBx eosinophils, however BAL eosinophils (OR 1.75 p=0.31) were not. In multivariable analysis, A grade (OR 2.93 95%CI 1.65-5.20) and positive BAL microbiology (OR 2.18 95%CI 1.10-4.31) were associated with an increased risk of TBBx eosinophils. <h3>Conclusion</h3> Systematic reporting of TBBx eosinophils improves sensitivity for detection compared with historic reporting. Acute vascular rejection grades and positive BAL microbiology were independently associated with an increased risk of TBBx eosinophils after adjustment for blood eosinophil count. Systematic reporting of TBBx eosinophils may identify patients at risk of poor outcomes.

Face transplantation: A longitudinal histological study focusing on chronic active and mucosal rejection in a series with long-term follow-up

The 2007 Banff working classification of skin-containing Tissue Allograft Pathology addressed only acute T cell-mediated rejection in skin. We report the longitudinal long-term histological follow-up of six face transplant recipients, focusing on chronic and mucosal rejection. We identified three patterns suggestive of chronic rejection (lichen planus-like, vitiligo-like and scleroderma-like). Four patients presented lichen planus-like and vitiligo-like chronic rejection at 52±17months posttransplant with severe concomitant acute T cell-mediated rejection. After lichen planus-like rejection, two patients developed scleroderma-like alterations. Graft vasculopathy with C4d deposits and de novo DSA led to subsequent graft loss in one patient. Chronic active rejection was frequent and similar patterns were noted in mucosae. Concordance between 124 paired skin and mucosal biopsies acute rejection grades was low (κ=0.2, p=.005) but most grade 0/I mucosal rejections were associated with grade 0/I skin rejections. We defined discordant (grade≥II mucosal rejection and grade 0/I skin rejection) (n=55 [70%]) and concordant (grade≥II rejection in both biopsies) groups. Mucosal biopsies of the discordant group displayed lower intra-epithelial GranzymeB/FoxP3 ratios suggesting a less aggressive phenotype (p=.08). The grading system for acute rejection in mucosa may require phenotyping. Whether discordant infiltrates reflect a latent allo-immune reaction leading to chronic rejection remains an open question.

Early findings after integration of donor-derived cell-free DNA into clinical care following pediatric heart transplantation.

Endomyocardial biopsy (EMB) is costly and discomforting yet remains a key component of surveillance after pediatric heart transplantation (HT). Donor-derived cell-free DNA (dd-cfDNA) has been histologically validated with high negative predictive value, offering an alternative to surveillance EMB (sEMB). We implemented an alternative surveillance protocol using commercially available dd-cfDNA assays in place of sEMB after pediatric HT. Recipients ≧7months post-HT with reassuring clinical assessment were referred for dd-cfDNA. When not elevated above the manufacturers' threshold, sEMB was deferred. Subsequent clinical status and results of follow-up EMB were analyzed. Over 17months, 58 recipients [34% female, median age at HT 3.1years (IQR 0.6-10.6)] had dd-cfDNA assessed per protocol. Median age was 14.8years (8.4-18.3) and time from HT 6.0years (2.2-11.2). Forty-seven (81%) had non-elevated dd-cfDNA and 11 (19%) were elevated. During a median of 8.7months (4.2-15), all are alive without allograft loss/new dysfunction. Among those with non-elevated dd-cfDNA, 24 (51%) had subsequent sEMB at 12.1months (6.9-12.9) with 23showing no acute rejection (AR): grade 0R/pAMR0 (n=16); 1R(1A)/pAMR0 (n=7). One had AR (grade 2R(3A)/pAMR0) on follow-up sEMB after decreased immunosuppression following a diagnosis of PTLD. All 11 with elevated dd-cfDNA had reflex EMB at 19days (12-32) with AR in 4: grade 1R(1B-2)/pAMR0 (n=3); 1R(1B)/pAMR2 (n=1). dd-cfDNA assessment in place of selected, per-protocol EMB decreased surveillance EMB by 81% in our pediatric HT recipient cohort with no short-term adverse outcomes. Individual center approach to surveillance EMB will influence the utility of these findings.

High Grade Primary Graft Dysfunction after Lung Transplantation is Associated with Acute Rejection but Not Chronic Allograft Dysfunction

Purpose Evidence suggests that high grade primary graft dysfunction after lung transplantation (LTx) is a major threat for early and late outcomes. Herein, we aim to examine the risk factors and clinical impact of PGD in a contemporary cohort at a single center. Methods From 1/2008 to 7/2018, 1147 LTx procedures were performed at our institution. Clinical data was prospectively collected and PGD defined according to ISHLT criteria. Median follow up was 3.3 years (interquartile range 1.2 - 7.4). Multi-variable analysis utilizing recipient, donor, and LTx procedure variables was performed to assess risk factors for PGD, acute rejection, chronic lung allograft dysfunction (CLAD), early mortality, and late survival. Results Out of 1147 LTx procedures, 61% were bilateral. The incidence of PGD (grade II & III) was 13% & 15% at 24 hr , 12% & 14% at 48 hr , and 12% & 14% at 72 hr, respectively. Multi-variable analysis identified cardiopulmonary bypass usage/duration, single LTx, recipient pulmonary arterial hypertension, longer ischemic time, earlier year of LTx, older donor, higher Lung Allocation Score, and higher ratio of recipient/donor weight as risk factors for high grade PGD (grade II or III at 48-72 hr). Notably, recipient body mass index, donor smoking history, and diabetes were not significant risk factors for high grade PGD. Further analysis demonstrated that PGD II or III at 48-72 hr were independent significant risk factors for early mortality and higher acute rejection grades, while not significantly associated with CLAD or late survival. PGD grade II or III at 24 hr were not significant risk factors for early mortality, acute rejection, CLAD, or late survival. Conclusion This single-center data analysis of > 1000 contemporary lung transplants identified risk factors for high grade PGD. While high grade PGD at 48-72 hr was associated with higher risk of early mortality and acute rejection, in contrast to previous studies, it was not associated with a higher risk of CLAD or late survival, perhaps due to evolving management strategies.

Combined Immunotherapy With Belatacept and BTLA Overexpression Attenuates Acute Rejection Following Kidney Transplantation.

BackgroundCostimulatory blockade provides new therapeutic opportunities for ensuring the long-term survival of kidney grafts. The adoption of the novel immunosuppressant Belatacept has been limited, partly due to concerns regarding higher rates and grades of acute rejection in clinical trials. In this study, we hypothesized that a combined therapy, Belatacept combined with BTLA overexpression, may effectively attenuate acute rejection after kidney transplantation.Materials and MethodsThe rat kidney transplantation model was used to investigate graft rejection in single and combined therapy. Graft function was analyzed by detecting serum creatinine. Pathological staining was used to observe histological changes in grafts. The expression of T cells was observed by immunohistochemistry and flow cytometry. In vitro, we constructed an antigen-stimulated immune response by mixed lymphocyte culture, treated with or without Belatacept and BTLA-overexpression adenovirus, to observe the proliferation of receptor cells and the expression of cytokines. In addition, western blot and qRT-PCR analyses were performed to evaluate the expression of CTLA-4 and BTLA at various time points during the immune response.ResultsIn rat models, combined therapy reduced the serum creatinine levels and prolonged graft survival compared to single therapy and control groups. Mixed acute rejection was shown in the allogeneic group and inhibited by combination treatment. Belatacept reduced the production of DSA and the deposition of C4d in grafts. Belatacept combined with BTLA overexpression downregulated the secretion of IL-2 and IFN-γ, as well as increasing IL-4 and IL-10 expression. We also found that Belatacept combined with BTLA overexpression inhibited the proliferation of spleen lymphocytes. The duration of the elevated expression levels of CTLA-4 and BTLA differentially affected the immune response.ConclusionBelatacept combined with BTLA overexpression attenuated acute rejection after kidney transplantation and prolonged kidney graft survival, which suggests a new approach for the optimization of early immunosuppression after kidney transplantation.

Non-invasive cardiac allograft rejection surveillance: reliability and clinical value for prevention of heart failure.

Allograft rejection-related acute and chronic heart failure (HF) is a major cause of death in heart transplant recipients. Given the deleterious impact of late recognized acute rejection (AR) or non-recognized asymptomatic antibody-mediated rejection on short- and long-term allograft function improvement of AR surveillance and optimization of action strategies for confirmed AR can prevent AR-related allograft failure and delay the development of cardiac allograft vasculopathy, which is the major cause for HF after the first posttransplant year. Routine non-invasive monitoring of cardiac function can improve both detection and functional severity grading of AR. It can also be helpful in guiding the anti-AR therapy and timing of routine surveillance endomyocardial biopsies (EMBs). The combined use of EMBs with non-invasive technologies and methods, which allow detection of subclinical alterations in myocardial function (e.g., tissue Doppler imaging and speckle-tracking echocardiography), reveal alloimmune activation (e.g., screening of complement-activating donor-specific antibodies and circulating donor-derived cell-free DNA) and help in predicting the imminent risk of immune-mediated injury (e.g., gene expression profiling, screening of non-HLA antibodies, and circulating donor-derived cell-free DNA), can ensure the best possible surveillance and management of AR. This article gives an overview of the current knowledge about the reliability and clinical value of non-invasive cardiac allograft AR surveillance. Particular attention is focused on the potential usefulness of non-invasive tools and techniques for detection and functional grading of early and late ARs in asymptomatic patients. Overall, the review aimed to provide a theoretical and practical basis for those engaged in this particularly demanding up-to-date topic.

Development of a Pre-Implantation Regulatory T Cell-Permissive Immunosuppression Protocol in a Rat Model of Ex Vivo Lung Perfusion Followed by Lung Transplantation

CD4+CD25highFoxp3+ regulatory T cells (Treg) can establish immunologic tolerance in animal models. We have developed a method to deliver recipient-derived Tregs to donor lungs during ex-vivo lung perfusion (EVLP). Our goal is to maximize the effectiveness of this therapy by developing a Treg-permissive post transplant immunosuppression protocol. We hypothesized that combination therapy with interleukin-2 (IL-2)/anti-IL-2 antibody complexes (IL-2c) and tacrolimus (Tac) would facilitate the expansion of endogenous Tregs and attenuate acute rejection, thus creating an environment permissive to Treg therapy. We performed rat left lung transplantation (LTx) experiments using Fischer 344 (F344, RT-1lv1) donors and Wistar Kyoto (WKy, RT-1l) recipients with or without antecedent 3h EVLP. Animals received: no treatment (NT); IL-2c (a single low [30ug] or high [60ug] dose) alone; Tac (0.1mg/kg/day, 7 doses) alone; or both IL-2c and Tac, intraperitoneally starting on the day of transplantation. Allografts that underwent EVLP had lower acute rejection grades in IL-2c/Tac-treated rats than in NT and Tac-treated rats (A Grade p = 0.046; B Grade p = 0.064; Fig1). In contrast, there were no differences among these groups in allografts that had not undergone EVLP. In the grafts, the frequency of CD4+CD25highFoxp3+ cells increased in both low and high dose IL-2c/Tac groups compared with Tac group, regardless of EVLP (p = 0.012, p = 0.107; Fig 2). Although the frequency of CD4+CD25+Foxp3- effector T cells also increased with high dose IL-2c in the non-EVLP group, this was not seen with EVLP (p = 0.804) (Fig 2). Despite the presence of Tac, IL-2c increased Tregs in the graft after transplantation and attenuated acute rejection in EVLP-treated lungs. This work lays the groundwork for pre-implantation allograft-directed regulatory T cell therapy.

Microbiome Dependent Regulatory T Cell Generation Correlates with Acute and Chronic Lung Allograft Rejection in a Murine Model

Purpose Despite the growing experience in lung transplantation a significant number of patients rapidly succumb to chronic rejection in the form of bronchiolitis obliterans (OB). The reasons for such discrepancies are unknown but have been suspected to relate to individual variability in gut and lung microbiome. Methods To study the role of the microbiome in controlling lung immunology we transplanted C57BL/10 lungs to C57BL/6 recipients from either Jackson Lab, Maine or Envigo facilities in Maryland vs Indiana. Histological grading of acute and chronic rejection, in the form of OB was performed on days 7 and 21 respectively with flow cytometric analysis of the lungs in parallel. Results Recipients from the Maine facility rapidly rejected lung grafts with high ISHLT rejection grades (2.8±0.37) by day 7 while Maryland recipients were rejection-free (0.25±0.25). Delayed histologic evaluation on day 21 post-engraftment revealed evidence of OB in 40% of Indiana recipients while 0% in Maine or Maryland mice(Fig.1A). Flow cytometric analysis revealed a high prevalence of CD4+Foxp3+ Tregs in Maryland recipients (29.56±2.32%) but lower in Maine and Indiana mice while T cell IL-17 levels were also different between them. Systemic different TGF-β levels were also observed. Treatment of Maryland recipients with broad-spectrum antibiotics affected TGF-β levels, decreased the Treg proportion (14.24±1.47%, p Conclusion Our data demonstrate that mice from different origins mount different lung allograft-specific microbiome-related immune responses. Furthermore it suggests that microbiome-dependent TGF beta levels may contribute to the generation of protective Tregs and ameliorate both acute and chronic rejection. Such data puts into question the notion that TGF-β contributes to lung fibrosis and opens up therapeutic avenues of microbiome manipulation to augment the TGF-β -Treg axis.

3281 Management of Acute Rejection in Penile Allotransplantation

3281 Management of Acute Rejection in Penile Allotransplantation

A novel combined ex vivo and in vivo lentiviral interleukin-10 gene delivery strategy at the time of transplantation decreases chronic lung allograft rejection in mice

ObjectiveOur objective was to develop a rapid-onset and durable gene-delivery strategy that is applicable at the time of transplant to determine its effects on both acute rejection and chronic lung allograft fibrosis using a mouse orthotopic lung transplant model. MethodsC57BL/6 mice received an orthotopic left lung transplant from syngeneic donors or C57BL/10 donors. By using syngeneic lung transplantation, we established a novel gene transfer protocol with lentivirus luciferase intrabronchial administration to the donor lung ex vivo before transplantation. This strategy was applied in allogeneic lung transplantation with lentivirus engineering expression of human interleukin-10 or lentivirus luciferase (control). ResultsBioluminescent imaging revealed that the highest early transgene expression was achieved when lentivirus luciferase was administered both directly into the donor lung graft ex vivo before implantation and subsequently to the recipient in vivo daily on post-transplant days 1 to 4, compared with post-transplant in vivo administration only (days 0 to 4). Our previous work with adenoviral interleukin-10 gene therapy indicates that early interleukin-10 expression in the allograft is desirable. Therefore, we selected the combined protocol for human interleukin-10 encoding lentiviral vector therapy. In the allogeneic transplant setting, ex vivo and in vivo human interleukin-10 encoding lentiviral vector therapy reduced acute rejection grade (2.0 vs 3.0, P < .05) at day 28. The percentage of fibrotic obliterated airways was reduced in the human interleukin-10 encoding lentiviral vector–treated group (10.9% ± 7.7% vs 40.9% ± 9.3%, P < .05). ConclusionsDelivery of lentiviral interleukin-10 gene therapy, using a novel combined ex vivo and in vivo delivery strategy, significantly improves acute and chronic rejection in the mouse lung transplant model.

Donor pretreatment with nebulized complement C3a receptor antagonist mitigates brain-death induced immunological injury post-lung transplant.

Donor brain death (BD) is an inherent part of lung transplantation (LTx) and a key contributor to ischemia-reperfusion injury (IRI). Complement activation occurs as a consequence of BD in other solid organ Tx and exacerbates IRI, but the role of complement in LTx has not been investigated. Here, we investigate the utility of delivering nebulized C3a receptor antagonist (C3aRA) pretransplant to BD donor lungs in order to reduce post-LTx IRI. BD was induced in Balb/c donors, and lungs nebulized with C3aRA or vehicle 30minutes prior to lung procurement. Lungs were then cold stored for 18hours before transplantation into C57Bl/6 recipients. Donor lungs from living donors (LD) were removed and similarly stored. At 6hours and 5days post-LTx, recipients of BD donor lungs had exacerbated IRI and acute rejection (AR), respectively, compared to recipients receiving LD lungs, as determined by increased histopathological injury, immune cells, and cytokine levels. A single pretransplant nebulized dose of C3aRA to the donor significantly reduced IRI as compared to vehicle-treated BD donors, and returned IRI and AR grades to that seen following LD LTx. These data demonstrate a role for complement inhibition in the amelioration of IRI post-LTx in the context of donor BD.

Bone marrow mesenchymal stromal cells protect allograft lung transplants from acute rejection via the PD-L1/IL-17A axis.

Using a rat model of allograft lung transplantation, we investigated the effectiveness of mesenchymal stromal cells (MSCs) as prophylactic and therapeutic agents against the acute rejection of lung grafts. Lung grafts were harvested from donor rats and transplanted orthotopically into major histocompatibility complex-mismatched rats. MSCs were administered to the recipients once (on day 0) or twice (on days 0 and 3) after transplantation. The grade of acute rejection was evaluated both macroscopically and microscopically 6days after transplantation. To elucidate the related mechanism, mRNA levels of inflammatory cytokines and immunomodulatory receptors in the transplanted grafts were measured using quantitative RT-PCR. The lung graft tissue from the rats that received MSCs post-surgically was protected from acute rejection significantly better than that from the untreated controls. Notably, the rats administered MSCs twice after surgery exhibited the least signs of rejection, with a markedly upregulated mRNA level of PD-L1 and a downregulated mRNA level of IL-17A. This study assessed MSC protection of lung allografts from acute rejection by modulating T cell activity via enforced expression of PD-L1 in transplants and downregulation of IL-17A.

Selective CD28 Inhibition Modulates Alloimmunity and Cardiac Allograft Vasculopathy in Anti-CD154-Treated Monkeys.

Selective CD28 inhibition is actively pursued as an alternative to B7 blockade using cytotoxic T lymphocyte antigen 4 Ig based on the hypothesis that the checkpoint immune regulators cytotoxic T lymphocyte antigen 4 and programmed death ligand 1 will induce tolerogenic immune signals. We previously showed that blocking CD28 using a monovalent nonactivating reagent (single-chain anti-CD28 Fv fragment linked to alpha-1 antitrypsin [sc28AT]) synergizes with calcineurin inhibitors in nonhuman primate (NHP) kidney and heart transplantation. Here, we explored the efficacy of combining a 3-week "induction" sc28AT treatment with prolonged CD154 blockade. Cynomolgus monkey heterotopic cardiac allograft recipients received sc28AT (10 mg/kg, d0-20, n = 3), hu5C8 (10-30 mg/kg, d0-84, n = 4), or combination (n = 6). Graft survival was monitored by telemetry. Protocol biopsies and graft explants were analyzed for International Society of Heart and Lung Transplantation acute rejection grade and cardiac allograft vasculopathy score. Alloantibody, T-cell phenotype and regulatory T cells were analyzed by flow cytometry. Immunochemistry and gene expression (NanoString) characterized intra-graft cellular infiltration. Relative to modest prolongation of median graft survival time with sc28AT alone (34 days), hu5C8 (133 days), and sc28AT + hu5C8 (141 days) prolonged survival to a similar extent. CD28 blockade at induction, added to hu5C8, significantly attenuated the severity of acute rejection and cardiac allograft vasculopathy during the first 3 months after transplantation relative to hu5C8 alone. These findings were associated with decreased proportions of circulating CD8 and CD3CD28 T cells, and modulation of inflammatory gene expression within allografts. Induction with sc28AT promotes early cardiac allograft protection in hu5C8-treated NHPs. These results support further investigation of prolonged selective CD28 inhibition with CD40/CD154 blockade in NHP transplants.

Belatacept Combined With Transient Calcineurin Inhibitor Therapy Prevents Rejection and Promotes Improved Long-Term Renal Allograft Function.

Belatacept, a T cell costimulation blocker, demonstrated superior renal function, lower cardiovascular risk, and improved graft and patient survival in renal transplant recipients. Despite the potential benefits, adoption of belatacept has been limited in part due to concerns regarding higher rates and grades of acute rejection in clinical trials. Since July 2011, we have utilized belatacept-based immunosuppression regimens in clinical practice. In this retrospective analysis of 745 patients undergoing renal transplantation at our center, we compared patients treated with belatacept (n = 535) with a historical cohort receiving a tacrolimus-based protocol (n = 205). Patient and graft survival were equivalent for all groups. An increased rate of acute rejection was observed in an initial cohort treated with a protocol similar to the low-intensity regimen from the BENEFIT trial versus the historical tacrolimus group (50.5% vs. 20.5%). The addition of a transient course of tacrolimus reduced rejection rates to acceptable levels (16%). Treatment with belatacept was associated with superior estimated GFR (belatacept 63.8 mL/min vs. tacrolimus 46.2 mL/min at 4 years, p < 0.0001). There were no differences in serious infections including rates of cytomegalovirus or BK viremia. We describe the development of a costimulatory blockade-based strategy that ultimately allows renal transplant recipients to achieve calcineurin inhibitor-free immunosuppression.

Systematic pathological component scores for skin-containing vascularized composite allografts

ABSTRACTClinical management of skin-containing vascularized composite allografts (VCA) requires accurate assessment of the graft status, typically based on skin biopsies. The Banff 2007 Working Classification proposed 4 grades of acute rejection, but did not score individual features or include vascular rejection. Here we report a systematic scoring system developed from MHC-mismatched porcine skin-containing VCA. Biopsies from 20 VCA, 9 autologous skin flaps and 9 normal skin were analyzed to optimize the methodology and set thresholds. The components quantified were: perivascular cells/dermal vessel (pc), perivascular dermal infiltrate area (pa), luminal leukocytes/capillary or venule (c), epidermal infiltrate (ei), epidermal apoptosis or necrosis (e), endarteritis (v), and chronic allograft vasculopathy (cav). To evaluate prognostic value, we scored a separate group of 28 serial biopsies from 8 recipients (4 that were ultimately accepted and 4 that rejected. Parameters on the initial biopsies predictin...

The value of contrast-enhanced ultrasound in diagnosis of acute rejection after pancreas transplantation

Objective To investigate the clinical value of contrast-enhanced ultrasound (CEUS) in the diagnosis and grading of acute rejection of the transplanted pancreas after simultaneous pancreas-kidney transplantation. Methods Seventy cases pancreas grafts underwent gray scale ultrasound, color Doppler flow imaging(CDFI) and CEUS examination, the contrast agent perfusion processes were observed, and the parameters of time intensity curves(time-intensity curve, TIC) were calculated. The CEUS results were compared with the pathological findings. Results Twenty-one cases were acute rejection in 70 cases, of which 10 cases were mild, 8 cases were moderate and 3 cases were severe; and 49 cases were non-rejection. ①Gray scale and CDFI ultrasound: The pancreatic grafts of acute rejection were edema and enlarged, the parenchyma echo were decreased. The artery resistance index(RI) were significant different between acute rejection group and non-rejection group(0.77±0.05 vs 0.74±0.10, P 0.05). ②CEUS: TIC curves showed a significantly longer time to reach peak [TTP, (21.7±4.3)s vs (13.0±2.9)s, P 0.05) but statistically difference was found when the severe group compared with the other two groups (P<0.05). Conclusions CEUS can be used to observe the perfusion of the vascular and parenchyma of the pancreas, the results also can be quantitative analyzed. It is an effective method for the diagnosis of pancreas acute rejection of simultaneous pancreas-kidney transplantation. Key words: Contrast-enhanced ultrasound; Pancreas transplantation; Kidney transplantation; Graft rejection