Subclinical Pancreas Rejection on Protocol Biopsy Within the First Year of Simultaneous Pancreas Kidney Transplant.

This single-center retrospective study investigated subclinical rejection prevalence and significance in simultaneous pancreas and kidney transplant (SPKT) recipients. We analyzed 352 SPKT recipients from July 2003 to April 2022. Our protocol included pancreas allograft surveillance biopsies at 1, 4, and 12months post-transplant. After excluding 153 patients unable to undergo pancreas biopsy, our study cohort comprised 199 recipients. Among the 199 patients with protocol pancreas biopsies, 107 had multiple protocol pancreas biopsies in the first year, totaling 323. Subclinical rejection was identified in 132 episodes (41%). Of these, 72% were Grade 1, 20% were indeterminate, and 8% were Banff Grade 2 or higher. All episodes of subclinical rejection were treated. Rates of pancreas graft loss (10% vs. 7%) and clinical rejection (21% vs. 20%) at 3 years were similar between those with and without subclinical rejection. Subclinical rejection Banff Grade 2 or more was associated with poor pancreas graft survival HR of 5.5 (95% CI: 1.24-24.37, p = 0.025). Of 236 simultaneous protocol kidney and pancreas biopsies, 102 (43%) showed pancreas subclinical rejection, while only 17% had concurrent kidney subclinical rejection. Our findings suggest limited predictive value of pancreatic enzymes and euglycemia in detecting pancreas rejection. Furthermore, poor concordance existed between pancreas and kidney subclinical rejection.

Outcome and safety of a surveillance biopsy guided personalized immunosuppression program after liver transplantation.

Graft survival beyond year 1 has not changed after orthotopic liver transplantation (OLT) over the last decades. Likewise, OLT causes comorbidities such as infection, renal impairment and cancer. We evaluated our single-center real-world individualized immunosuppression program after OLT, based on 211 baseline surveillance biopsies (svLbx) without any procedural complications. Patients were classified as low, intermediate and high rejection risk based on graft injury in svLbx and anti-HLA donor-specific antibodies. While 32% of patients had minimal histological inflammation, 57% showed histological inflammation and 23% advanced fibrosis (>F2), which was not predicted by lab parameters. IS was modified in 79% of patients after svLbx. After immunosuppression reduction in 69 patients, only 5 patients showed ALT elevations and three of these patients had a biopsy-proven acute rejection, two of them related to lethal comorbidities. The rate of liver enzyme elevation including rejection was not significantly increased compared to a svLbx control cohort prior to the initiation of our structured program. Immunosuppression reduction led to significantly better kidney function compared to this control cohort. In conclusion, a biopsy guided personalized immunosuppression protocol after OLT can identify patients requiring lower immunosuppression or patients with graft injury in which IS should not be further reduced.

Economic analysis of screening for subclinical rejection in kidney transplantation using protocol biopsies and noninvasive biomarkers.

Subclinical rejection (SCR) screening in kidney transplantation (KT) using protocol biopsies and noninvasive biomarkers has not been evaluated from an economic perspective. We assessed cost-effectiveness from the health sector perspective of SCR screening in the first year after KT using a Markov model that compared no screening with screening using protocol biopsy or biomarker at 3 months, 12 months, 3 and 12 months, or 3, 6, and 12 months. We used 12% subclinical cellular rejection and 3% subclinical antibody-mediated rejection (SC-ABMR) for the base-case cohort. Results favored 1-time screening at peak SCR incidence rather than repeated screening. Screening 2 or 3 times was favored only with age <35 years and with high SC-ABMR incidence. Compared to biomarkers, protocol biopsy yielded more quality-adjusted life years (QALYs) at lower cost. A 12-month biopsy cost $13 318/QALY for the base-case cohort. Screening for cellular rejection in the absence of SC-ABMR was less cost effective with 12-month biopsy costing $46 370/QALY. Screening was less cost effective in patients >60 years. Using biomarker twice or thrice was cost effective only if biomarker cost was <$700. In conclusion, in KT, screening for SCR more than once during the first year is not economically reasonable. Screening with protocol biopsy was favored over biomarkers.

Interleukin-6 blockade with tocilizumab increases Tregs and reduces T effector cytokines in renal graft inflammation: A randomized controlled trial.

Interleukin-6 (IL-6) is a proinflammatory cytokine and key regulator of Treg: T effector cell (Teff) balance. We hypothesized that IL-6 blockade with tocilizumab, a monoclonal antibody to IL-6R, would increase Tregs, dampen Teff function, and control graft inflammation. We conducted a randomized controlled clinical trial (2014-2018) of clinically stable kidney transplant recipients on calcineurin inhibitor, mycophenolate mofetil, and prednisone, with subclinical graft inflammation noted on surveillance biopsies during the first year posttransplant. Subjects received tocilizumab (8 mg/kg IV every 4 weeks; 6 doses; n = 16) or no treatment (controls; n = 14) on top of usual maintenance immunosuppression. Kidney biopsies pre- and post-treatment were analyzed using Banff criteria. Blood was analyzed for serum cytokines, Treg frequencies, and T cell effector molecule expression (IFN-γ, IL-17, granzyme B) post-stimulation ex vivo. Tocilizumab-treated subjects were more likely to show improved Banff ti-score (62.5% vs. 21.4%, p = .03), increased Treg frequency (7.1% ± 5.55% vs. 3.6% ± 1.7%, p = .0168), and a blunted Teff cytokine response compared to controls. Changes in Banff i- and t-scores were not significantly different. The treatment was relatively well tolerated with no patient deaths or graft loss. Blockade of IL-6 is a novel and promising treatment option to regulate the T cell alloimmune response in kidney transplant recipients. NCT02108600.

Diagnostic yield of 18 F-FDG PET/CT imaging and urinary CXCL9/creatinine levels in kidney allograft subclinical rejection.

Subclinical kidney allograft acute rejection (SCR) corresponds to "the unexpected histological evidence of acute rejection in a stable patient." SCR detection relies on surveillance biopsy. Noninvasive approaches may help avoid biopsy-associated complications. From November 2015 to January 2018, we prospectively performed positron emission tomography/computed tomography (PET/CT) after injection of F18 -fluorodeoxyglucose (18 F-FDG) in adult kidney transplant recipients with surveillance biopsy at ~3 months posttransplantation. The Banff-2017 classification was used. The ratio of the mean standard uptake value (mSUVR) between kidney cortex and psoas muscle was measured. Urinary levels of CXCL-9 were concomitantly quantified. Our 92-patient cohort was categorized upon histology: normal (n = 70), borderline (n = 16), and SCR (n = 6). No clinical or biological difference was observed between groups. The mSUVR reached 1.87 ± 0.55, 1.94 ± 0.35, and 2.41 ± 0.54 in normal, borderline, and SCR groups, respectively. A significant difference in mSUVR was found among groups. Furthermore, mSUVR was significantly higher in the SCR vs normal group. The area under the receiver operating characteristic curve (AUC) was 0.79, with 83% sensitivity using an mSUVR threshold of 2.4. The AUC of urinary CXCL-9/creatinine ratios comparatively reached 0.79. The mSUVR positively correlated with ti and acute composite Banff scores. 18 F-FDG-PET/CT helps noninvasively exclude SCR, with a negative predictive value of 98%. External validations are required.

IgG4 donor-specific HLA antibody profile is associated with subclinical rejection in stable pediatric liver recipients.

The impact of donor-specific HLA antibody (DSA) following liver transplantation remains controversial. We hypothesized DSA IgG subclass characteristics, compared to total DSA IgG, might correlate with specific histopathological phenotype(s) of subclinical graft injury. We therefore studied 129 stable, arguably "clinically ideal," pediatric liver recipients at the time of a screening biopsy to enter an immunosuppression withdrawal trial. Sixty-five (50%) subjects tested positive for class II DSA. IgG subclass profile was characterized by mean fluorescence intensity (MFI) and normalized subclass composition (>5%). A prominent IgG4 DSA profile was strongly correlated with greater HLA mismatch, a histopathological phenotype characterized by the presence of interface activity (with variable degrees of fibrosis), and a transcriptional profile of attenuated T cell-mediated rejection. Specifically, compared to those without class II DSA, those with IgG4 class II DSA MFI sum >2000 exhibited an odds ratio (OR) of 20.79 (95% confidence interval [CI] 4.38-98.69) and IgG4 subclass composition >5% exhibited an OR of 8.99 (95% CI 2.70-29.9). Our data suggest that IgG4 DSA may serve as a useful biomarker to identify, among clinically and biochemically stable liver transplant recipients, a subset with histological and transcriptional features indicative of an active, suboptimally controlled alloimmune response.

The impact of first untreated subclinical minimal acute rejection on risk for chronic lung allograft dysfunction or death after lung transplantation.

Acute cellular rejection (ACR) is a significant risk factor for chronic lung allograft dysfunction (CLAD). Although clinically manifest and higher grade (≥A2) ACR is generally treated with augmented immunosuppression, management of minimal (grade A1) ACR remains controversial. In our program, patients with subclinical and spirometrically stable A1 rejection (StA1R) are routinely not treated with augmented immunosuppression. We hypothesized that an untreated first StA1R does not increase the risk of CLAD or death compared to episodes of spirometrically stable no ACR (StNAR). The cohort was drawn from all consecutive adult, first, bilateral lung transplantations performed between 1999 and 2017. Biopsies obtained in the first-year posttransplant were paired with (forced expiratory volume in 1 second FEV1 ). The first occurrence of StA1R was compared to a time-matched StNAR. The risk of CLAD or death was assessed using univariable and multivariable Cox proportional hazards models. The analyses demonstrated no significant difference in risk of CLAD or death in patients with a first StA1R compared to StNAR. This largest study to date shows that, in clinically stable patients, an untreated first A1 ACR in the first-year posttransplant is not significantly associated with an increased risk for CLAD or death. Watchful-waiting approach may be an acceptable tactic for stable A1 episodes in lung transplant recipients.

Development and clinical validity of a novel blood-based molecular biomarker for subclinical acute rejection following kidney transplant.

Noninvasive biomarkers are needed to monitor stable patients after kidney transplant (KT), because subclinical acute rejection (subAR), currently detectable only with surveillance biopsies, can lead to chronic rejection and graft loss. We conducted a multicenter study to develop a blood-based molecular biomarker for subAR using peripheral blood paired with surveillance biopsies and strict clinical phenotyping algorithms for discovery and validation. At a predefined threshold, 72% to 75% of KT recipients achieved a negative biomarker test correlating with the absence of subAR (negative predictive value: 78%-88%), while a positive test was obtained in 25% to 28% correlating with the presence of subAR (positive predictive value: 47%-61%). The clinical phenotype and biomarker independently and statistically correlated with a composite clinical endpoint (renal function, biopsy-proved acute rejection, ≥grade 2 interstitial fibrosis, and tubular atrophy), as well as with de novo donor-specific antibodies. We also found that <50% showed histologic improvement of subAR on follow-up biopsies despite treatment and that the biomarker could predict this outcome. Our data suggest that a blood-based biomarker that reduces the need for the indiscriminate use of invasive surveillance biopsies and that correlates with transplant outcomes could be used to monitor KT recipients with stable renal function, including after treatment for subAR, potentially improving KT outcomes.

Short-term adverse effects of early subclinical allograft inflammation in kidney transplant recipients with a rapid steroid withdrawal protocol.

The impact of subclinical inflammation (SCI) noted on early kidney allograft biopsies remains unclear. This study evaluated the outcome of SCI noted on 3-month biopsy. A total of 273/363 (75%) kidney transplant recipients with a functioning kidney underwent allograft biopsies 3-months posttransplant. Among those with stable allograft function at 3 months, 200 biopsies that did not meet the Banff criteria for acute rejection were identified. These were Group I: No Inflammation (NI, n = 71) and Group II: Subclinical Inflammation (SCI, n = 129). We evaluated differences in kidney function at 24-months and allograft histology score at 12-month biopsy. SCI patients had a higher serum creatinine (1.6 ± 0.7 vs 1.38 ± 0.45; P = .02) at 24-months posttransplant, and at last follow-up at a mean of 42.5 months (1.69 ± 0.9 vs 1.46 ± 0.5 mg/dL; P = .027). The allograft chronicity score (ci + ct + cg + cv) at 12-months posttransplant was higher in the SCI group (2.4 ± 1.35 vs 1.9 ± 1.2; P = .02). The incidence of subsequent rejections within the first year in SCI and NI groups was 24% vs 10%, respectively (P = .015). De novo donor-specific antibody within 12 months was more prevalent in the SCI group (12/129 vs 1/71, P = .03). SCI is likely not a benign finding and may have long-term implications for kidney allograft function.

Subclinical inflammation phenotypes and long-term outcomes after pediatric kidney transplantation.

The implementation of surveillance biopsies in pediatric kidney transplantation remains controversial. Surveillance biopsies detect subclinical injury prior to clinical dysfunction, which could allow for early interventions that prolong allograft survival. We conducted a single-center retrospective cohort study of 120 consecutive pediatric kidney recipients, of whom 103 had surveillance biopsies ≤6 months posttransplant. We tested the hypothesis that subclinical inflammation (borderline or T cell-mediated rejection without clinical dysfunction) is associated with a 5-year composite endpoint of acute rejection and allograft failure. Overall, 36% of subjects had subclinical inflammation, which was associated with increased hazard for the composite endpoint (adjusted hazard ratio 2.89 [1.27, 6.57]; P < .01). Subjects with treated vs untreated subclinical borderline rejection had a lower incidence of the composite endpoint (41% vs 67%; P < .001). Subclinical vascular injury (subclinical inflammation with Banff arteritis score > 0) had a 78% incidence of the composite endpoint vs 11% in subjects with no major surveillance abnormalities (P < .001). In summary, we showed that subclinical inflammation phenotypes were prevalent in pediatric kidney recipients without clinical dysfunction and were associated with increased acute rejection and allograft failure. Once prospectively validated, our data would support implementation of surveillance biopsies as standard of care in pediatric kidney transplantation.

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.

The Banff 2015 Kidney Meeting Report: Current Challenges in Rejection Classification and Prospects for Adopting Molecular Pathology.

The XIII Banff meeting, held in conjunction the Canadian Society of Transplantation in Vancouver, Canada, reviewed the clinical impact of updates of C4d-negative antibody-mediated rejection (ABMR) from the 2013 meeting, reports from active Banff Working Groups, the relationships of donor-specific antibody tests (anti-HLA and non-HLA) with transplant histopathology, and questions of molecular transplant diagnostics. The use of transcriptome gene sets, their resultant diagnostic classifiers, or common key genes to supplement the diagnosis and classification of rejection requires further consensus agreement and validation in biopsies. Newly introduced concepts include the i-IFTA score, comprising inflammation within areas of fibrosis and atrophy and acceptance of transplant arteriolopathy within the descriptions of chronic active T cell-mediated rejection (TCMR) or chronic ABMR. The pattern of mixed TCMR and ABMR was increasingly recognized. This report also includes improved definitions of TCMR and ABMR in pancreas transplants with specification of vascular lesions and prospects for defining a vascularized composite allograft rejection classification. The goal of the Banff process is ongoing integration of advances in histologic, serologic, and molecular diagnostic techniques to produce a consensus-based reporting system that offers precise composite scores, accurate routine diagnostics, and applicability to next-generation clinical trials.

Evaluation of C1q Status and Titer of De Novo Donor-Specific Antibodies as Predictors of Allograft Survival.

De novo donor-specific antibodies (dnDSAs) that develop after renal transplantation are independent predictors of allograft loss. However, it is unknown if dnDSA C1q status or titer at the time of first detection can independently predict allograft loss. In a consecutive cohort of 508 renal transplant recipients, 70 developed dnDSAs. Histologic and clinical outcomes were correlated with the C1q assay or dnDSA titer. C1q positivity correlated with dnDSA titer (p < 0.01) and mean fluorescence intensity (p < 0.01) and was more common in class II versus class I dnDSAs (p < 0.01). C1q status correlated with tubulitis (p = 0.02) and C4d status (p = 0.03) in biopsies at the time of dnDSA development, but not T cell-mediated rejection (TCMR) or antibody-mediated rejection (ABMR). De novo DSA titer correlated with Banff g, i, t, ptc, C4d scores, TCMR (p < 0.01) and ABMR (p < 0.01). Post-dnDSA graft loss was observed more frequently in recipients with C1q-positve dnDSA (p < 0.01) or dnDSA titer ≥ 1:1024 (p ≤ 0.01). However, after adjustment for clinical phenotype and nonadherence in multivariate models, neither C1q status nor dnDSA titer were independently associated with allograft loss, questioning the utility of these assays at the time of dnDSA development.

Polyclonal Regulatory T Cell Therapy for Control of Inflammation in Kidney Transplants.

Early subclinical inflammation in kidney transplants is associated with later graft fibrosis and dysfunction. Regulatory T cells (Tregs) can reverse established inflammation in animal models. We conducted a pilot safety and feasibility trial of autologous Treg cell therapy in three kidney transplant recipients with subclinical inflammation noted on 6-month surveillance biopsies. Tregs were purified from peripheral blood and polyclonally expanded ex vivo using medium containing deuterated glucose to label the cells. All patients received a single infusion of ~320 × 106 (319, 321, and 363.8 × 106 ) expanded Tregs. Persistence of the infused Tregs was tracked. Graft inflammation was monitored with follow-up biopsies and urinary biomarkers. Nearly 1 × 109 (0.932, 0.956, 1.565 × 109 ) Tregs were successfully manufactured for each patient. There were no infusion reactions or serious therapy-related adverse events. The infused cells demonstrated patterns of persistence and stability similar to those observed in non-immunosuppressed subjects receiving the same dose of Tregs. Isolation and expansion of Tregs is feasible in kidney transplant patients on immunosuppression. Infusion of these cells was safe and well tolerated. Future trials will test the efficacy of polyclonal and donor alloantigen-reactive Tregs for the treatment of inflammation in kidney transplants.

Low serum testosterone is associated with impaired graft function early after heart transplantation.

BACKGROUND: We sought to investigate a correlation between serum testosterone levels and graft function early after heart transplantation. METHODS: In a cross-sectional study, we measured serum testosterone levels 4 weeks after heart transplantation in 49 consecutive male recipients. Echocardiography was carried out to evaluate graft function. Low serum testosterone was defined as <11 nmol/L. RESULTS: Low serum testosterone was present in 21 (43%) recipients (Group A), and 28 (57%) had normal testosterone levels (Group B). The two groups did not differ in age and presence of renal dysfunction, arterial hypertension, diabetes, or hyperlipidemia. Donor age and allograft ischemic time were not different between the two groups. Both groups had comparable tacrolimus through levels, dose of mycophenolate mophetil, and methylprednisolone. Patients in Group A had significantly lower LVEF (58±5% vs 65±6% vs Group B, P=.001) and TAPSE (1.3±0.3 cm vs 1.6±0.3 cm in Group B, P=.01). In comparison with Group B, more patients in Group A were found to have low grade (1R) rejection (25% vs 3%; P=.02). CONCLUSION: Low serum testosterone levels appear to be associated with impaired graft function and an increased incidence of low-grade rejection episodes early after heart transplantation.