Graft Biopsy Research Articles

Study protocol: the TRAnsplant BIOpsies (TRABIO) study – a prospective, observational, multicentre cohort study to assess the treatment of kidney graft rejections

IntroductionDespite continued efforts, long-term outcomes of kidney transplantation remain unsatisfactory. Kidney graft rejections are independent risk factors for graft failure. At the participating centres of the TRAnsplant BIOpsies study group,...

Delayed Graft Function Under the Microscope: Surveillance Biopsies in Kidney Transplantation.

Delayed graft function (DGF) is a common complication of kidney transplantation and frequently leads to the necessity of surveillance biopsies. The purpose of this study is to describe the histological findings in surveillance biopsies of deceased donor kidney transplant recipients and evaluate the risk factors for graft outcomes. This is a monocentric, retrospective study including kidney transplant recipients that underwent a graft biopsy during the DGF period between January 2006 and July 2019. 356 biopsies were performed in 335 deceased donor transplant recipients. Biopsies were analyzed according to the Banff classification. The main histological findings were: acute tubular necrosis in 150 biopsies (42.1%), acute rejection in 96 biopsies (26.9%), and borderline findings in 91 biopsies (25.5%). In the multivariate analysis, recipient age (p = 0.028) and DGF duration (p = 0.005) were associated with rejection, antibody-induction with anti-thymocyte globulin (ATG) was protective (p = 0.001). The occurrence of rejection was associated with lower death-censored graft survival (log-rank; p = 0.009). Surveillance biopsies of kidney grafts experiencing DGF remain an essential tool for the care of kidney transplant recipients. The recipient's age and duration of DGF are independent risk factors for acute rejection, while antibody-induction therapy with ATG is associated with protection from its occurrence.

Low Levels of Hepatocyte-Specific Methylation in Cell-Free DNA Are a Strong Negative Predictor for Acute T Cell-Mediated Rejection Requiring Treatment Following Liver Transplantation.

Graft-derived cell-free DNA (gdcfDNA) quantification is a promising, minimally invasive tool for detecting acute T cell-mediated rejection (ATCMR) following liver transplantation (LT). We investigated the utility of measuring hepatocyte-specific methylation in cfDNA (HS-cfDNA) to quantify gdcfDNA, examining its accuracy in detecting ATCMR in a prospective, cross-sectional study. Blood was collected from LT recipients immediately prior to graft biopsy for suspected rejection. HS-cfDNA was quantified using droplet-digital polymerase chain reaction. Prebiopsy liver function tests (LFTs) and HS-cfDNA levels were correlated with biopsy results and the primary outcome of treated biopsy-proven acute rejection (tBPAR). A total of 51 patients were recruited; 37 had evidence of rejection on biopsy and 20 required treatment. As much as 11 patients needed inpatient treatment for rejection. HS-cfDNA significantly outperformed LFTs in identifying patients with tBPAR, particularly those needing inpatient treatment (area under the curve, 73.0%; 95% confidence interval, 55.4%-90.6%; P = 0.01). At a threshold of <33.5% of the total cfDNA fraction, HS-cfDNA had a specificity of 97%, correctly excluding tBPAR in 30/31 patients. Quantifying graft-specific methylation in cfDNA has a major advantage over previous gdcfDNA techniques: it does not require genotyping/sequencing, lending it greater feasibility for translation into transplantation care. Low levels of HS-cfDNA were a strong negative predictor for tBPAR (negative predictive value, 86%) and may have a future role in triaging patients prior to invasive graft biopsies.

Primary Focal Segmental Glomerulosclerosis Recurrence After Pediatric Renal Transplantation.

Focal segmental glomerulosclerosis recurrence after renal transplant occurs frequently in pediatric patients and is associated with poor graft survival when patients reach adulthood. We investigated recurrence rates, recurrence risk factors, management strategies, and long-term graft function among pediatric renal transplant recipients with focal segmental glomerulosclerosis as primary disease. We retrospectively evaluated medical records of 34 pediatric patients with primary focal segmental glomerulosclerosis who had undergone renal transplant between 2004 and 2019 at our center. Focal segmental glomerulosclerosis recurrence was diagnosed by the presence of nephrotic range proteinuria after transplant and confirmed by graft biopsy. Preoperative prophylactic plasma exchange was administered to pediatric renal transplant recipients with primary focal segmental glomerulosclerosis. Plasma exchange was also used to treat focal segmental glomerulosclerosis recurrence, with rituximab added if the patient did not respond to plasma exchange. All patients (male-to-female ratio of 19:15) in our group underwent renal transplant. Mean patient age at the time of transplant was 12.72 ± 5.46 years. Twenty-nine patients received living- related donor allografts (85.3%) and 5 received organs from deceased donors (14.7%). We identified focal segmental glomerulosclerosis recurrence in 5 recipients (14.7%). Time from focal segmental glomerulosclerosis diagnosis to end-stage renal disease and duration of dialysis were shorter in the recurrence group than in the nonrecurrence group (48.4 months [range, 2-90 mo] vs 65.1 months [range, 8-123 mo] and 1.41 ± 0.82 vs 3.18 ± 1.88 years, respectively; P < .05). Donor type and transplant age were similar in both groups. Of those with recurrence who had received plasma exchange and rituximab, 3 patients (75%) had complete remission and 1 patient (25%) had partial remission. Prophylactic plasma exchange and the combined plasma exchange-rituximab regimen for treatment of focal segmental glomerulosclerosis recurrence resulted in low recurrence and good remission rates in our pediatric cohort.

Histological changes associated with early and late renal allograft dysfunction in a large three-center transplant program in Iraq

Introduction: Transplantation is the sole viable option for the long-term survival of patients with end-stage renal disease (ESRD) in low-resourced countries. Objectives: To report the histopathological characteristics of kidney graft dysfunction in a large transplant program of a developing country. Patients and Methods: Renal transplant biopsies were analyzed by the Banff 2017 classification and subdivided into early (≤1 year) or late (&gt;1 year) post-engraftment periods during the 12 months of 2019. Results: Here, 290 satisfactory graft biopsies were obtained on 290 patients for graft failure and/ or proteinuria. The median age of the recipient was 39 years (interquartile range 28-47), where 77% were male and 5.5% had been previously transplanted and 84% of donors were unrelated. Histological diagnosis was as follow; acute T-cell mediated rejection (A-TCMR; 23.1%), acute tubular necrosis (ATN; 14.8%), interstitial fibrosis and tubular atrophy (IFTA; 11.4%), recurrent or de novo kidney disease (R/DKD; 8.6%), transplant glomerulopathy (TG; 7.6%), calcineurin inhibitor toxicity (CNI; 6.9%), and active antibody-mediated rejection (A-AMR; 8.6%). Early graft dysfunctions were A-TCMR (29%) and ATN (22.4%). Late graft dysfunction included IF/TA, (20.2%), TG (20.2%), R/DRD (17%), and A-TCMR (9.5%). C4d+AMR was equally represented in early (5.6%) and late (6.3%) biopsies. Conclusion: A-TCMR was the most common cause of early graft dysfunction and was replaced by chronic conditions as the cause of 57.8% of late graft biopsies. The causes of graft dysfunction are not remarkably different from the west and TG will be a major cause of late graft failure in Iraq.

Research in Brief

Normothermic machine perfusion preservation of deceased donor livers should be considered instead of ischaemic cold storage because it reduces both post-transplant early allograft dysfunction and ischaemic biliary complications, according to the results of the PROTECT trial. James Markmann and colleagues randomly assigned patients awaiting liver donation to receive donor livers preserved by either conventional ischaemic cold storage (control; n=147) or normothermic machine perfusion (n=153). The incidence of early allograft dysfunction was significantly decreased in the normothermic machine perfusion group compared with the control group (27 [18%] of 150 vs 44 [31%] of 141; p=0·01). Histopathological assessment of liver graft biopsies showed that donor livers in the normothermic machine perfusion group had significantly less lobular inflammation, a marker of ischaemia-reperfusion injury. Patient survival at hospital discharge and at day 30 were similar between groups. Use of a Cytosponge biomarker panel to prioritise endoscopic Barrett's oesophagus surveillance: a cross-sectional study followed by a real-world prospective pilotCytosponge atypia, p53 overexpression, and clinical risk factors (age, sex, and segment length) could be used to prioritise patients for endoscopy. Further investigation could validate their use in clinical practice and lead to a substantial reduction in endoscopy procedures compared with current surveillance pathways. Full-Text PDF Open Access

Biomarkers of rejection in liver transplantation.

Liver transplantation is a lifesaving therapy for thousands of individuals with end-stage liver disease across the world. Allograft rejection, which is traditionally detected through an invasive graft biopsy, is a major complication for liver transplant recipients in the postoperative period. Biomarkers represent a relatively newer and safer means of detecting and predicting transplant rejection when compared with the current standard of care: liver biopsy. This review serves to compile recent progress in the field of biomarker discovery in liver allograft rejection. Several promising biomarkers exist in the field of liver transplant rejection. Recent developments include blood genomic assays measuring miRNA, mRNA and donor-derived cell-free DNA. Additionally, serum levels of cytokines, proteoforms, donor-specific antibodies and immunophenotyping have shown promising results in predicting rejection pre and/or posttransplant. Biomarkers represent a novel method of predicting the risk of developing allograft rejection. The findings discussed in the studies outlined in this review are promising in the potential to improve patient management, reduce complications from over- or under-immunosuppression, and ultimately enhance outcomes.

Acute Anti-A/B Antibody-Mediated Rejection After ABO-Incompatible Kidney Transplantation Treated With Bortezomib and Plasmapheresis: A Case Report

ABO-incompatible kidney transplantation (KTP) is effective for avoiding transplantation-related issues. It is a viable alternative to ABO-compatible KTP, as both techniques have similar patient and graft survival rates. However, anti-A/B antibody-mediated rejection (AMR) can occur, resulting in poor long-term graft survival. A 45-year-old man with end-stage renal disease presented with a serum creatinine level of 10.2 mg/dL. We decided to perform KTP with spousal donation. He had panel-reactive antibody class I and II and cross matching test negativity, a 3/6 mismatch on human leukocyte antigen typing, an ABO antibody titer of 1:256, and no donor-specific antibodies. The patient and donor blood types were O+ and A+, respectively. The anti-A/B antibody titer was reduced preoperatively with rituximab (200 mg/body), plasmapheresis, and intravenous immunoglobulin (0.2 mg/kg). Basiliximab and methylprednisolone were used for induction immunosuppression, and tacrolimus, mycophenolate mofetil, and prednisolone were used for maintenance immunosuppression. KTP was successful, and graft function was initially normal. On postoperative day (POD) 5, the serum creatinine level and anti-A/B antibody titer increased from 0.9 mg/dL to 1.9 mg/dL and 1:16 to 1:64, respectively. Graft biopsy revealed acute AMR and tubular injury. We started steroid pulse therapy, plasmapheresis, and subcutaneous bortezomib (2.6 mg, twice a day, every 3 days) with no side effects. The serum creatinine level decreased from 5.7 mg/dL to 1.5 mg/dL on POD 28. Graft biopsy showed no rejection, and normal function was maintained for 40 months. Acute, early anti-A/B AMR was successfully treated with plasmapheresis and bortezomib.

Outcomes of Living Kidney Transplantation for Mitochondrial Disease Patients: A Case Series

Mitochondrial disease can affect many organs, including the brain, nerves, heart, liver, eyes, ears, pancreas, and kidneys. Kidney transplantation is a treatment option for renal failure due to mitochondrial disease; however, the prognosis of patients who undergo kidney transplantation for mitochondrial disease is unknown. Here we evaluated the outcomes of kidney transplant recipients with mitochondrial disease. Clinical data were obtained from 4 kidney transplantation recipients who were followed at our department. Of the 4 transplantations, 3 were performed in our department: 2 patients received kidneys from their fathers, and a third from his wife. The fourth recipient received a kidney from her mother-who had a mitochondrial genetic abnormality-at another hospital. Of the 4 recipients, 3 were diagnosed with mitochondrial disease before the transplantation, and the fourth was diagnosed after. All recipients had sensorineural deafness and diabetes mellitus, and only 1 had a history of encephalopathy and stroke-like episodes before the transplantation. One patient died 2 years after transplantation due to encephalopathy progression with stable kidney function. The grafted kidney of the patient who received it from her mother lost function at 5 years post-transplantation. A graft biopsy revealed focal segmental glomerular sclerosis due to mitochondrial disease. The other patients' kidney functions remained stable. None of the recipients experienced rejection. In kidney transplantation for mitochondrial disease, attention should be paid to the exacerbation of comorbidities, while careful consideration should be given to donors with a mitochondrial genetic abnormality.

Perioperative kidney injury in liver transplantation: a prospective study with renal histology and measured glomerular filtration rates

Background Acute kidney injury (AKI) is frequent after liver transplantation (LT), with impact on graft function, morbidity and mortality. Although multifactorial, the pathophysiology of perioperative kidney injury remains unclear. Our aims were to analyze the frequency, evolution and risk factors for kidney impairment during the peri- and early post-operative period. Methods In a prospective, single-center study of 27 adult patients undergoing first single-organ LT, we analyzed measured glomerular filtration rate (mGFR) pre-transplant, at post-operative day (POD) 10, and at 1, 3, 12 and 36 months. Kidney and liver graft biopsies were performed during LT. Results A median mGFR decline of 45% was detected from pre-transplant to POD 10, correlating strongly with the mGFR evolution from baseline to 12 months (rs = 0.80, p<.001) and baseline to 36 months (rs = 0.82, p<.001). AKI occurred in 59% of recipients within 48 h of LT, notably before the introduction of calcineurin inhibitors on POD 3. AKI was strongly associated with mGFR at 12 and 36 months. Kidney and liver graft biopsies showed only minor histological changes. Donor and recipient body mass index, recipient age, model of end-stage liver disease score, diagnosis of hepatitis C, donor cause of death, as well as bleeding, transfusions and duration of the anhepatic phase correlated with early kidney dysfunction. Conclusion The greatest decline in mGFR was evident within 10 days and AKI within hours of LT, irrespective of baseline mGFR and before introduction of calcineurin inhibitors. Very early post-LT kidney injury has substantial consequences for long-term kidney function.

Value of posttransplant protocol biopsies in 2 biliary autoimmune liver diseases: A step toward personalized immunosuppressive treatment.

The value of protocol liver graft biopsies with good liver function was evaluated in patients with primary sclerosing cholangitis (PSC) or primary biliary cholangitis (PBC).A total of 250 protocol liver biopsy reports from 182 PSC and PBC patients were compared. Overall histopathological findings and those leading to changes in immunosuppression therapy were retrospectively analyzed.The mean time to first protocol biopsy after transplantation was 5.5 (±4.5) years for PSC patients and 9.3 (±6.6) years for PBC patients. More than 1 abnormal histopathological parameter was found in 43% and 62% of PSC and PBC patients, respectively. However, the histology was interpreted as normal by the pathologist in 78% of PSC and 60% of PBC patients. Immunosuppression therapy was reduced in 10% and increased in 6% patients due to protocol biopsy findings. Biopsies leading to increased immunosuppression therapy had more portal (P = .004), endothelial (P = .008), interphase (P = .021), and lobular (P = .000) inflammation.Mild histopathological findings were frequently found in the protocol biopsies despite the normal biochemistry. PBC patients had more histological abnormalities than those transplanted due to PSC; however, PBC patients had longer follow-up times. Immunosuppression therapy could be safely increased or decreased according to protocol biopsy findings after multidisciplinary meeting discussions.

Intra-Liver Allograft C3d-Binding Donor-Specific Anti-HLA Antibodies Predict Rejection After Liver Transplantation

There is no doubt that antibody-mediated rejection (AMR) due to donor-specific anti-HLA antibodies (DSA) brings a poor outcome for liver transplant recipients. However, the relationship between intragraft DSA (g-DSA), complement-binding abilities, and AMR remains unknown. We enrolled a total of 20 liver transplant recipients who underwent protocol or episode graft biopsies in the mid to long term after liver transplant (median 48.5, range 6-198 months), and their status of g-DSA and complement 3d (C3d)-binding abilities was assessed with the graft immunocomplex capture fluorescence analysis (ICFA) technique. The prevalence of g-DSA was 15.0 % in liver transplant recipients (3/20), and serum DSA (s-DSA) also existed in 15.0% of recipients. The number of g-DSA+/s-DSA+, g-DSA+/s-DSA-, g-DSA-/s-DSA+, and g-DSA-/s-DSA- cases are 1, 2, 2, and 15, respectively. The g-DSA+ group demonstrated a significant high rejection activity index: 3.67 ± 1.53, compared with the g-DSA- group: 1.24 ± 1.15 (P=.0045). Moreover, C3d-binding reaction was notably higher in the g-DSA+ group (C3d index: 1.87 ± 0.38 vs 0.76 ± 0.35) (P < .0001). Overall, the g-DSA+ group was more associated with liver allograft rejection-not only AMR, but also T cell-mediated rejection (P=.031). These results suggest that the existence of g-DSA and intragraft C3d-binding reaction had a negative impact on the liver allografts, but in contrast s-DSA did not have any significant impact.

Split-Combine Click-SELEX Reveals Ligands Recognizing the Transplant Rejection Biomarker CXCL9.

Renal rejection is a major incidence in patients after kidney transplantation and associated with allograft scarring and function loss, especially in antibody-mediated rejection. Regular clinical monitoring of kidney-transplanted patients is thus necessary, but measuring donor-specific antibodies is not always predictive, and graft biopsies are time-consuming and costly and may come up with a histological result unsuspicious for rejection. Therefore, a noninvasive diagnostic approach to estimate an increased probability of kidney graft rejection by measuring specific biomarkers is highly desired. The chemokine CXCL9 is described as an early indicator of rejection. In this work, we identified clickmers and an aptamer by split-combine click-SELEX (systematic evolution of ligands by exponential enrichment) that bind CXLC9 with high affinity. The aptamers recognize native CXCL9 and maintain binding properties under urine conditions. These features render the molecules as potential binding and detector probes for developing point-of-care devices, e.g., lateral flow assays, enabling the noninvasive monitoring of CXCL9 in renal allograft patients.

Assessment of hepatic steatosis based on needle biopsy images from deceased donor livers.

Assessment of hepatic steatosis (HS) before transplantation requires the pathologist to read a graft biopsy. A simple method based on the evaluation of images from tissue samples with a smartphone could expedite and facilitate the liver selection. This study aims to assess the degree of HS by analysing photographic images from liver needle biopsy samples. Thirty-three biopsy-images were acquired with a smartphone. Image processing was carried out using ImageJ: background subtraction, conversion to HSB colour space, segmentation of the biopsy area, and evaluation of statistical features of Hue, Saturation, Brightness, Red, Green, and Blue channels on the biopsy area. After feature extraction, correlations were made with gold standard HS percentage assessed at two levels (frozen-section vs glass-slide). Sensitivity, specificity, and accuracy were calculated for each feature. Correlations were found for H, S, R. The sensitivity, specificity, and accuracy of the final classifier based on the K* algorithm were 94%, 92%, 94%. Accuracy assessment was performed considering macrovesicular steatosis on specimens with mostly < 30% HS. The steatosis assessment based on needle biopsy images, proved to be an effective and promising method. Deep learning approaches could also be experimented with a larger set of images.

Missed diagnosis of oxalosis with disastrous consequences. Case reports of a father and daughter

Background: Hyperoxalosis is a rare disease that originates from a defect in a liver enzyme and results in renal failure, if not diagnosed in time. Once end-stage renal disease is established, a transplant is the treatment of choice. But a kidney-only transplant can fail due to the mobilization of the excess oxalates in the tissue, and many authorities recommend a combined kidney-liver transplant. Case Presentation: We describe a case where the diagnosis of oxalosis was missed, resulting in renal transplant failure and excision of the graft. The diagnosis was made only on noting florid heterotopic calcification. A renal transplant was performed due to end-stage renal disease, but graft failure occurred and had to be excised due to recurrent oxalosis, again without diagnosis, despite imaging and graft biopsy. It was only when muscle calcification was noted for an unrelated indication that a diagnosis was made. The case highlights the importance of excluding all causes of nephrocalcinosis, including rare ones like oxalosis, in the management of chronic renal disease. Conclusion: We hope to alert the physician to consider primary hyperoxalosis as a differential diagnosis in renal failure patients with recurrent calcium oxalate renal stones and/or nephrocalcinosis.

Long-Term Management of Post-Transplant Ureteral Stricture with Surgical Reconstruction: A Case Series and Literature Review

Introduction: Ureteral stricture is the most common complication after kidney transplant and is largely responsible for graft dysfunction. Surgical intervention is the definitive treatment if conservative management with stenting and percutaneous nephrostomy tube placement fails and has been shown to have comparable long-term survival rates and limited post-operative complications. Methods: This is a single-center retrospective study following seven patients who received a kidney or a kidney and pancreas transplant between August 2012 and January 2021. These patients underwent surgical ureteral reconstruction after failed conservative management of a ureteral stricture. The reconstruction procedures performed were native ureter to transplanted kidney ureteropyelostomy, native bladder to transplanted renal pelvis vesicopyelostomy, non-transecting side-to-side ureteroneocystostomy, and a Boari flap creation. Data collected from electronic medical records included recipient age, gender, delayed post-transplant complications, ureteral reconstruction technique, and post-reconstruction outcomes. Renal ultrasound (RUS), renogram, nephrostogram, serum creatinine (Cr), and graft biopsy were used to assess for severity of hydronephrosis, ureteral stricture, and graft dysfunction. Serum Cr and RUS were used to assess renal function after the ureteral reconstruction. Results: Six out of seven cases resulted in reduced or resolved hydronephrosis and preserved graft function without future nephrostomy or ureteral stenting. One case required immediate revision due to persistent obstruction, and this patient had concomitant rejection leading to intrarenal stricture requiring ureterocalycostomy. Conclusions: Formal ureteral reconstruction is the definitive treatment for many cases of ureteral strictures after transplant. The surgical technique chosen for these procedures must consider the physical and functional state of the bladder, ureter, and kidney. Our series outlines multiple surgical approaches that should be considered early in the management of post-transplant ureteral strictures to limit graft dysfunction.

406.2: Utility of Donor-derived Cell-free DNA in Assessing Simultaneous Pancreas-Kidney Transplantation Rejection

Introduction: Among solid organ transplants, pancreas transplantation has one of the highest rates of acute rejection within the first 12 months. Graft biopsy, the gold standard, is risky and often not available. Hence, a non-invasive biomarker with good predictive value, such as donor-derived cell free DNA (dd-cfDNA), may be useful in predicting risk of rejection. In this study we sought to analyze the performance of a dd-cfDNA test in patients with simultaneous pancreas kidney (SPK) transplant. Methods: A retrospective study was conducted from 2017 to 2020 on patients admitted for pancreas graft biopsy at the Hospital Clínic Barcelona. Plasma samples were collected on the day of biopsy. dd-cfDNA fraction was assessed using the ProsperaTM test, a SNP-based mmPCR methodology to predict risk of rejection (including T-cell mediated rejection [TCMR] and antibody mediated rejection [ABMR]). Results: Plasma samples (n=50) were obtained from 37 SPK recipients. Pancreas biopsies were collected from 30 patients. Of the 50 plasma samples, 36 were plasma-biopsy paired and per Banff criteria were categorized as no rejection (n=21) and acute rejection (aTCMR and aABMR; n=15). Median dd-cfDNA levels were significantly elevated in samples with graft rejection diagnosis: 1.11 [0.83–1.66] vs. no rejection 0.65 [0.28–1.00]; p=0.004),especially after 45 days post transplantation (AR: 0.83[0.67–1.59], NR:0.45[0.13–0.55], p=0.004) (Figure 1). The overall performance of the test after 45 days of transplant is as follows: sensitivity 71.4%, specificity 91.6%, PPV: 83.8%, NPV:84.6%. Conclusion: dd-cfDNA assay can accurately differentiate active rejection from non rejection through a non-invasive, simple blood test in SPK patients as early as 45 days post SPK transplant.Medical writing support was provided by Nour Al Haj Baddar, Ph.D. from Natera, Inc. at San Carlos, CA.

P.141: Hypoglycemia: A Rare Sign of Pancreas Graft Dysfunction

Introduction: Hypoglycemia is an unusual sign after pancreas transplantation and its cause remains unclear. Hyperinsulinemia and insulin antibodies have been proposed to play a role on its development. Methods: This is a retrospective review of a consecutive series of patients with documented symptomatic hypoglycemia after pancreas transplantation with a concurrent pancreas graft biopsy performed between June 2016 and June 2021. Results: 7 patients had symptomatic hypoglycemia after SPK (5) or PASPK (2) at a mean time of 33 months after transplant (3-86mo). All cases had systemic venous drainage with enteric (4) or bladder (3) exocrine drainage. Most had abnormal OGTT with hypoglycemia 2 hours after glucose administration. Two patients had a history of biopsy proven pancreas rejection. There were no other signs of graft dysfunction (serum amylase, lipase and creatinine at baseline) at the time of the hypoglycemia episode nor at the time of the biopsies.Biopsy results showed pancreas rejection in 2 cases (1 AMR, 1 ACTR), CNI toxicity in 4 cases (3 pancreas and 1 kidney and pancreas) and 1 case showed abnormal islet morphology (small size). Cases of rejection were treated according to Banff Classification type and grade. In the cases of CNI toxicity, tacrolimus was minimized (3) or discontinued and replaced with Belatacept (1). One patient lost the pancreas graft due to AMR. No patient developed rejection during follow-up after IS modification. Hypoglycemia episodes were resolved in 5 cases and became less frequent in the remaining patient.Discussion: Hypoglycemia is a rare sign after pancreas transplantation. Along with hyperglycemia and elevated enzymes, hypoglycemia could be a marker of pancreas graft dysfunction due to treatable causes such as CNI toxicity and rejection.

208.1: The Presence of Donor-specific Antibodies Around the Time of Pancreas Graft Biopsy With Rejection Is Associated With an Increased Risk of Graft Failure

Introduction: Donor-specific antibodies (DSA) against human leukocyte antigen (HLA) are an important biomarker predicting graft injury, rejection (Rej), and failure in various solid organ transplant recipients. However, the impact of DSA with or without Rej among pancreas transplant recipients (PTRs) is unknown. Method: In this study, we included all PTRs who had undergone either simultaneous pancreas-kidney or solitary pancreas transplant at our center between 2005 and 2020, with pancreas allograft biopsy before 03/2021, and with DSA checked within 15 days of the biopsy. Among PTRs with multiple biopsies during the study period, the first index biopsy was used to analyze the data. Pancreas biopsies at the time of implant or explant were excluded, as were biopsies with no pancreas tissue present. PTRs were divided into four groups based on the biopsy findings on the index biopsy and DSA status as Rej-/DSA-; Rej+/DSA-; Rej-/DSA+ and Rej+/DSA+. Results: A total of 352 pancreas allograft biopsies were performed in 203 PTRs during the study period. Of these, 203 PTRs, 41 were in Rej-/DSA-; 87 Rej+/DSA-; 24 Rej-/DSA+; and 51 Rej+/DSA+. Most of the baseline characteristics were similar between the groups, except PTRs in Rej-/DSA+ and Rej+/DSA+ were relatively younger, with a mean age of 39 compared to 43 for the other two groups. The mean interval from transplant to index biopsy was not statistically different between the four groups. The most common rejection was TCMR, however, AMR was more prevalent in the Rej+/DSA+ group. In addition, DSA against class II HLA was more prevalent in the DSA+/Rej + group. There was no statistical difference in the mean post index biopsy follow-up. At last follow up, the rate of death censored graft failure (DCGF) for Rej-/DSA- was 22%, 29% in Rej+/DSA-; 17% in Rej-/DSA+ and 39% in Rej+/DSA+. Although not statistically significant, there was a trend towards inferior pancreas graft survival in Rej+/DSA+ group by unadjusted K-M survival analysis (Figure 1).In multivariable analysis compared to Rej-/DSA-, Rej+/DSA+ was significantly associated with DCGF (HR: 2.25, 95% CI: 1.02 to 4.97; p=0.04), however Rej+/DSA- was not (HR: 1.40; 95% CI: 0.65 to 3.0; p=0.39). Conclusions: PTRs with pancreas allograft rejection in the presence of DSA have an increased risk of DCGF, and may warrant particularly aggressive management.

P.156: Transcriptomic Profile in Pancreas Biopsies for Monitoring Graft Rejection

Introduction: Overall, almost 30% of pancreas transplant recipients present an episode of rejection during the first year after transplantation. Pancreas biopsy is the gold standard for the diagnosis and treatment pancreas rejection since other modes of monitoring pancreas rejection are neither sensitive nor specific enough. Immune infiltrates of graft from transplantations are usually evaluated with immunohistochemistry, immunofluorescence and flow cytometry. Interestingly enough, Banff schema has refined the diagnosis in kidney antibody-mediated rejection (ABMR) 4 times in the last 10 years, whereas in pancreas transplantation it has remained unchanged since its first description in 2011. Identification of genetic variants to aid in individualized treatment of solid organ allograft recipients would be associated with outcomes and personalized medicine. In kidney, liver, and heart transplantation, the molecular microscope has been paving the way towards the introduction of these novel transcriptomic fingerprints into the clinical practice and provide assistance into decision making. In pancreas transplantation only one work explored the correlation between the transcriptomic fingerprint and development of de novo ABMR using a 34 gene-set. Methods: We are developing a retrospective multicentre observational study aiming at comparing the transcriptomic profile of RNA obtained from paraffin embedded pancreas graft biopsies, and compare to the clinical and biochemical markers, and histological diagnosis. Study is being developed using pancreas graft biopsies performed previously per protocol or clinical indication. Samples from a range of different histological diagnosis (according to the Banff criteria) will be included (estimated n=20/diagnosis). Briefly, 3 sections of 20-micron thickness were obtained from FFPE blocks and RNA extraction were performed with the RNeasy FFPE Kit (Qiagen). Quality and quantity of RNA was checked by NanoDrop ND1000 (Thermo Scientific) spectrophotometer. For transcriptome analysis we are applying the Human Organ Transplant panel from Nanostring©, which includes a comprehensively profile of 770 genes across 37 pathways to identify biomarkers for rejection, uncover the mechanisms of tissue damage, and study toxicities brought on by immunosuppressive drugs. We expect to have preliminary results by May and some more conclusive data by November 2021.