What is the clinical relevance of deviant serum calcium and phosphate levels after pig-to-primate kidney xenotransplantation?

Experience from human renal allotransplantation informs us that disturbances in serum calcium and phosphate levels are relatively common. Post-transplant hypercalcemia is associated with an increased risk of recipient mortality, but not of graft loss or nephropathy, and post-transplant hyperphosphatemia with an increased risk of both recipient mortality and death-censored graft failure, but neither post-transplant hypocalcemia nor hypophosphatemia is associated with adverse outcome. Studies after pig-to-nonhuman primate kidney xenotransplantation have demonstrated consistent supranormal serum calcium and subnormal serum phosphate levels. If these trends in serum electrolyte levels were to occur following pig-to-human kidney xenotransplantation, the data from allotransplant studies would indicate an increased risk of recipient mortality (associated with hypercalcemia) but not of graft loss or nephropathy, and no adverse outcome from hypophosphatemia. Furthermore, some nonhuman primates are now surviving in a healthy state for longer than a year after life-supporting pig kidney transplantation, suggesting that chronic hypercalcemia and/or hypophosphatemia are not detrimental to long-term survival, and should not prevent clinical trials of pig kidney transplantation from being undertaken.

Immunological selection and monitoring of patients undergoing pig kidney transplantation.

Pig kidney xenotransplantation has the potential to alleviate the current shortage of deceased and living human organs and provide patients with end-stage renal disease with a greater opportunity for long-term survival and a better quality of life. In recent decades, advances in the genetic engineering of pigs and in immunosuppressive therapy have permitted the resolution of many historical obstacles to the success of pig kidney transplantation in nonhuman primates. Pig kidney xenotransplantation may soon be translated to the clinic. Given the potential risks of kidney xenotransplantation, particularly of immunologic rejection of the graft, potential patients must be carefully screened for inclusion in the initial clinical trials and immunologically monitored diligently post-transplantation. We provide an overview of the immunological methods we believe should be used to (i) screen potential patients for the first clinical trials to exclude those with a higher risk of rejection, and (ii) monitor patients with a pig kidney graft to determine their immunological response to the graft.

Pain resolution and glucose control in pediatric patients with chronic pancreatitis after total pancreatectomy with islet auto-transplantation.

BACKGROUND: Chronic pancreatitis (CP) and acute recurrent pancreatitis (ARP) in pediatric patients are strongly associated with genetic mutations and lead to pan-parenchymal disease refractory to medical and endoscopic treatment. Our aim was to assess pain resolution and glucose control in patients with CP and ARP following total pancreatectomy with islet auto-transplantation (TPIAT). METHODS: We retrospectively analyzed prospectively collected clinical data of 12 children who developed CP and ARP and underwent TPIAT when 21 years old or younger at the University of Chicago between December 2009 and June 2020. Patients with recurrent or persistent abdominal pain attributed to acute or chronic pancreatic inflammation and a history of medical interventions attempted for the relief of pancreatic pain were selected by a multi-disciplinary team for TPIAT. We followed patients post-operatively and reported data for pre-TPIAT, post-operative day 75, and yearly post-TPIAT. RESULTS: All 12 patients experienced complete resolution of pancreatic pain. The overall insulin-independence rate after 1 year was 66% (8/12) and 50% (3/6) at 4 years. Shorter duration of CP/ARP pre-TPIAT, higher mass of islets infused, and lower BMI, BMI percentile, and BSA were associated with insulin-independence post-TPIAT. CONCLUSIONS: TPIAT is a viable treatment option for pediatric patients with CP and ARP. Pediatric patients undergoing TPIAT for CP achieved resolution of pancreatic-type pain and reduced opioid requirements. The majority were able to achieve insulin-independence which was associated with lower pre-TPIAT BMI and higher islet mass transplanted (i.e., over 2000 IEQ/kg), the latter of which can be achieved by earlier TPIAT. LEVEL OF EVIDENCE: Treatment study, Level IV.

Uterus transplantation: the importance of uterine natural killer cells.

PURPOSE OF REVIEW: Murine studies have established that uterine natural killer (uNK) cells are critical regulators of normal placentation and fetal development in mammals. However, the biology of uNK cells in humans remains poorly understood. This ignorance represents a costly knowledge gap, as disordered placentation is thought to underpin a variety of pregnancy complications that impact maternal and neonatal health. In the context of uterus transplantation (UTx), uNK cells are anticipated to play a critical role within the allograft. Here, we review the current understanding of uNK cells in pregnancy biology and explore how this critically important cell population may contribute to pregnancy and graft outcomes in uterus transplant recipients. RECENT FINDINGS: Recent studies have characterized differences in NK cell populations between anatomic compartments in humans. In the endometrium, at least five phenotypically and functionally distinct subpopulations of uNK cells have been identified, with research into mechanisms regulating their differentiation and function currently underway. SUMMARY: Further elucidating uNK cell biology has the potential to influence the outcomes of pregnancy and UTx and benefit human health. UTx is a unique opportunity to study uNK cell biology and may shed light on mechanisms by which immunological tolerance is established at the maternal-fetal interface.

BETA-2 score is an early predictor of graft decline and loss of insulin independence after pancreatic islet allotransplantation.

This study aimed to evaluate whether the BETA-2 score is a reliable early predictor of graft decline and loss of insulin independence after islet allotransplantation. Islet transplant procedures were stratified into 3 groups according to clinical outcome: long-term insulin independence without islet graft decline (group 1, N = 9), initial insulin independence with subsequent islet graft decline and loss of insulin independence (group 2, N = 13), and no insulin independence (group 3, N = 13). BETA-2 was calculated on day 75 and multiple times afterwards for up to 145 months posttransplantation. A BETA-2 score cut-off of 17.4 on day 75 posttransplantation was discerned between group 1 and groups 2 and 3 (area under the receiver operating characteristic 0.769, P = .005) with a sensitivity and negative predictive value of 100%. Additionally, BETA-2 ≥ 17.4 at any timepoint during follow-up reflected islet function required for long-term insulin independence. While BETA-2 did not decline below 17.4 for each of the 9 cases from group 1, the score decreased below 17.4 for all transplants from group 2 with subsequent loss of insulin independence. The reduction of BETA-2 below 17.4 predicted 9 (1.5-21) months in advance subsequent islet graft decline and loss of insulin independence (P = .03). This finding has important implications for posttransplant monitoring and patient care.

Evaluating the Prognostic Value of Islet Autoantibody Monitoring in Islet Transplant Recipients with Long-Standing Type 1 Diabetes Mellitus.

(1) Background: The correlation between titers of islet autoantibodies (IAbs) and the loss of transplanted islets remains controversial. We sought to evaluate the prognostic utility of monitoring IAbs in diabetic patients after islet transplantation (ITx); (2) Methods: Twelve patients with Type 1 diabetes mellitus and severe hypoglycemia underwent ITx. Serum concentration of glutamic acid decarboxylase (GAD), insulinoma antigen 2 (IA-2), and zinc transport 8 (ZnT8) autoantibodies was assessed before ITx and 0, 7, and 75 days and every 3 months post-operatively; (3) Results: IA-2A (IA-2 antibody) and ZnT8A (ZnT8 antibody) levels were not detectable before or after ITx in all patients (median follow-up of 53 months (range 24-61)). Prior to ITx, GAD antibody (GADA) was undetectable in 67% (8/12) of patients. Of those, 75% (6/8) converted to GADA+ after ITx. In 67% (4/6) of patients with GADA+ seroconversion, GADA level peaked within 3 months after ITx and subsequently declined. All patients with GADA+ seroconversion maintained long-term partial or complete islet function (insulin independence) after 1 or 2 ITx. There was no correlation between the presence of IAb-associated HLA haplotypes and the presence of IAbs before or after ITx; (4) Conclusions: There is no association between serum GADA trends and ITx outcomes. IA-2A and ZnT8A were not detectable in any of our patients before or after ITx.

Post-Hoc Analysis of a Randomized, Double Blind, Prospective Study at the University of Chicago: Additional Standardizations of Trial Protocol are Needed to Evaluate the Effect of a CXCR1/2 Inhibitor in Islet Allotransplantation.

A recent randomized, multicenter trial did not show benefit of a CXCR1/2 receptor inhibitor (Reparixin) when analysis included marginal islet mass (>3,000 IEQ/kg) for allotransplantation and when immunosuppression regimens were not standardized among participating centers. We present a post-hoc analysis of trial patients from our center at the University of Chicago who received an islet mass of over 5,000 IEQ/kg and a standardized immunosuppression regimen of anti-thymocyte globulin (ATG) for induction. Twelve islet allotransplantation (ITx) recipients were randomized (2:1) to receive Reparixin (N = 8) or placebo (N = 4) in accordance with the multicenter trial protocol. Pancreas and donor characteristics did not differ between Reparixin and placebo groups. Five (62.5%) patients who received Reparixin, compared to none in the placebo group, achieved insulin independence after only one islet infusion and remained insulin-free for over 2 years (P = 0.08). Following the first ITx with ATG induction, distinct cytokine, chemokine, and miR-375 release profiles were observed for both the Reparixin and placebo groups. After excluding procedures with complications, islet engraftment on post-operative day 75 after a single transplant was higher in the Reparixin group (n = 7) than in the placebo (n = 3) group (P = 0.03) when islet graft function was measured by the ratio of the area under the curve (AUC) for c-peptide to glucose in mixed meal tolerance test (MMTT). Additionally, the rate of engraftment was higher when determined via BETA-2 score instead of MMTT (P = 0.01). Our analysis suggests that Reparixin may have improved outcomes compared to placebo when sufficient islet mass is transplanted and when standardized immunosuppression with ATG is used for induction. However, further studies are warranted. Investigation of Reparixin and other novel agents under more standardized and optimized conditions would help exclude confounding factors and allow for a more definitive evaluation of their role in improving outcomes in islet transplantation. Clinical trial reg. no. NCT01817959, clinicaltrials.gov.

Total pancreatectomy with islet autotransplantation in diabetic and pre-diabetic patients with intractable chronic pancreatitis.

Total pancreatectomy with islet autotransplantation (TPIAT) is an effective treatment option for non-diabetic patients with intractable chronic pancreatitis. The outcome and potential benefits for pre-diabetic and diabetic patients are less well established. Thirty-four patients underwent TPIAT were retrospectively divided into 3 groups according to pre-operative glycemic control: diabetes mellitus (DM) (n=5, 15%), pre-DM (n=11, 32%) and non-DM (n=18, 54%). Pre-operative fasting c-peptide was detectable and similar in all 3 groups. Islet yield in the DM group was comparable to pre-DM and non-DM groups (median islet equivalents [IEQ] was 191,800, 111,800, and 232,000IEQ, respectively). Patients received islet mass of over the target level of 2000IEQ/kg in pre-DM and DM at lower but clinically meaningful rates compared to the non-DM group: 45% (5/11) and 60% (3/5) for a combined 50% (8/16) rate, respectively, compared to 83% (15/18) for the non-DM group. At 1 year, fasting c-peptide and HbA1c did not differ between DM and pre-DM groups but c-peptide was significantly higher in non-DM. Islet transplantation failed (negative c-peptide) only in 1 patient. Pre-operatively, all patients experienced pancreatic pain with daily opioid dependence in 60% to 70%. Pancreatic-type pain gradually subsided completely in all groups with no differences in other painful somatic symptoms. Diabetic patients with measurable pre-operative c-peptide can achieve similar benefit from TPIAT, with comparable outcomes to pre-diabetic and non-diabetic patients including pain relief and the metabolic benefit of transplanted islets. Not surprisingly, endocrine outcomes for diabetic and pre-diabetics patients are substantially worse than in those with normal pre-operative glucose control.

En bloc liver and pancreas transplantation after total pancreatectomy with autologous islet transplantation.

We present a patient with intractable and debilitating pain secondary to chronic pancreatitis who was effectively treated with total pancreatectomy with islet autotransplantation (TPIAT). Islets engrafted into his liver significantly contributed to improved blood glucose control and quality of life. Subsequently, the patient developed alcohol related acute liver failure and en bloc liver and pancreas transplantation was performed to replace the failing liver with engrafted islets. Pancreas transplantation was required to resolve his life-threatening severe hypoglycemic episodes. Herein, we detail an innovative and multidisciplinary management of this complex medical problem.

Hierarchical assembly and disassembly of a transcriptionally active RAG locus in CD4+CD8+ thymocytes.

Expression of Rag1 and Rag2 is tightly regulated in developing T cells to mediate TCR gene assembly. Here we have investigated the molecular mechanisms governing the assembly and disassembly of a transcriptionally active RAG locus chromatin hub in CD4+CD8+ thymocytes. Rag1 and Rag2 gene expression in CD4+CD8+ thymocytes depends on Rag1 and Rag2 promoter activation by a distant antisilencer element (ASE). We identify GATA3 and E2A as critical regulators of the ASE, and Runx1 and E2A as critical regulators of the Rag1 promoter. We reveal hierarchical assembly of a transcriptionally active chromatin hub containing the ASE and RAG promoters, with Rag2 recruitment and expression dependent on assembly of a functional ASE-Rag1 framework. Finally, we show that signal-dependent down-regulation of RAG gene expression in CD4+CD8+ thymocytes depends on Ikaros and occurs with disassembly of the RAG locus chromatin hub. Our results provide important new insights into the molecular mechanisms that orchestrate RAG gene expression in developing T cells.