SMARCB1 regulates a TFCP2L1-MYC transcriptional switch promoting renal medullary carcinoma transformation and ferroptosis resistance.

Renal medullary carcinoma (RMC) is an aggressive tumour driven by bi-allelic loss of SMARCB1 and tightly associated with sickle cell trait. However, the cell-of-origin and oncogenic mechanism remain poorly understood. Using single-cell sequencing of human RMC, we defined transformation of thick ascending limb (TAL) cells into an epithelial-mesenchymal gradient of RMC cells associated with loss of renal epithelial transcription factors TFCP2L1, HOXB9 and MITF and gain of MYC and NFE2L2-associated oncogenic and ferroptosis resistance programs. We describe the molecular basis for this transcriptional switch that is reversed by SMARCB1 re-expression repressing the oncogenic and ferroptosis resistance programs leading to ferroptotic cell death. Ferroptosis resistance links TAL cell survival with the high extracellular medullar iron concentrations associated with sickle cell trait, an environment propitious to the mutagenic events associated with RMC development. This unique environment may explain why RMC is the only SMARCB1-deficient tumour arising from epithelial cells, differentiating RMC from rhabdoid tumours arising from neural crest cells.

Involvement of Neutrophils in Metastatic Evolution of Pancreatic Neuroendocrine Tumors.

Well-differentiated pancreatic neuroendocrine tumors (pNET) have an unpredictable natural history. The identification of both blood and tumor immune features associated with patients' outcomes remains limited. Herein, we evaluated the best prognostic value of the neutrophils-to-lymphocyte ratio (NLR) in a cohort of 144 pNETs. The NLR ≥ 4 was associated with worse overall survival in both univariate analysis (HR = 3.53, CI95% = 1.50-8.31, p = 0.004) and multivariate analysis (HR = 2.57, CI95% = 1.061-6.216, p = 0.036). The presence of synchronous liver metastasis was identified as a prognostic factor in multivariate analysis (HR = 3.35, CI95% = 1.411-7.973, p = 0.006). Interestingly, the absolute tumor-associated neutrophils count was higher in liver metastasis as compared to their paired primary tumor (p = 0.048). Deconvolution of immune cells from the transcriptome of 83 primary tumors and 30 liver metastases reveals enrichment for neutrophils in metastasis relative to primary tumors (p = 0.005), and this was associated with upregulation of the complement pathway (NES = 1.84, p < 0.0001). Combining neutrophils signature and complement pathway genes, unsupervised clustering identified two pNETs subgroups, namely Neu-Comp1 and Neu-Comp2. Characterized by neutrophils infiltration and activation of the complement pathway, Neu-Comp1 was highly enriched for metastatic liver samples as compared to Neu-Comp2 (p < 0.0001). These data suggest the possible link between liver metastasis, complement pathway activation, and neutrophils infiltration in well-differentiated pNET and open avenues for targeting complement pathways in these tumors.

In Vitro Impact of Pro-Senescent Endothelial Microvesicles on Isolated Pancreatic Rat Islets Function.

BACKGROUND: Ischemia-driven islet isolation procedure is one of the limiting causes of pancreatic islet transplantation. Ischemia-reperfusion process is associated with endothelium dysfunction and the release of pro-senescent microvesicles. We investigated whether pro-senescent endothelial microvesicles prompt islet senescence and dysfunction in vitro. MATERIAL AND METHODS: Pancreatic islets were isolated from male young rats. Replicative endothelial senescence was induced by serial passaging of primary porcine coronary artery endothelial cells, and microvesicles were isolated either from young passage 1 (P1) or senescent passage 3 (P3) endothelial cells. Islet viability was assessed by fluorescence microscopy, apoptosis by flow cytometry, and Western blot. Function was assessed by insulin secretion and islet senescence markers p53, p21, and p16 by Western blot. Microvesicles were stained by the PKH26 lipid fluorescent probe and their islet integration assessed by microscopy and flow cytometry. RESULTS: Regardless of the passage, half microvesicles were integrated in target islets after 24 hours incubation. Insulin secretion significantly decreased after treatment by senescent microvesicles (P3: 1.7 ± 0.2 vs untreated islet: 2.7 ± 0.2, P < .05) without altering the islet viability (89.47% ± 1.69 vs 93.15% ± 0.97) and with no significant apoptosis. Senescent microvesicles significantly doubled the expression of p53, p21, and p16 (P < .05), whereas young microvesicles had no significant effect. CONCLUSION: Pro-senescent endothelial microvesicles specifically accelerate the senescence of islets and alter their function. These data suggest that islet isolation contributes to endothelial driven islet senescence.

Atypical hemolytic and uremic syndrome due to C3 mutation in pancreatic islet transplantation: a case report.

BACKGROUND: We here report on the first observation of a C3 mutation that is related to atypical hemolytic and uremic syndrome (aHUS), which occurred in a pancreatic islet transplant patient. Immunosuppressive treatments, such as calcineurin inhibitors, have been linked to undesirable effects like nephrotoxicity. CASE PRESENTATION: A 40-year-old man with brittle diabetes, who was included in the TRIMECO trial, became insulin-independent 2 months after pancreatic islet transplantation. About 15 months after islet transplantation, the patient exhibited acute kidney injury due to aHUS. Despite plasma exchange and eculizumab treatment, the patient developed end-stage renal disease. A genetic workup identified a missense variant (p.R592Q) in the C3 gene. In vitro, this C3 variant had defective Factor I proteolytic activity with membrane proteins as cofactor proteins, which was thus classified as pathogenic. About 1 year after the aHUS episode, kidney transplantation was carried out under the protection of the specific anti-C5 monoclonal antibody eculizumab. The patient had normal kidney function, with preserved pancreatic islet function 4 years later. CONCLUSIONS: Pancreatic islet transplantation could have triggered this aHUS episode, but this link needs to be clarified. Although prophylactic eculizumab maintains kidney allograft function, its efficacy still needs to be studied in larger populations.

Effect of adding vildagliptin to insulin in haemodialysed patients with type 2 diabetes: The VILDDIAL study, a randomized, multicentre, prospective study.

AIM: To evaluate the effect of adding the dipeptidyl-peptidase-4 inhibitor vildagliptin to insulin on the glycaemic control of patients with type 2 diabetes undergoing haemodialysis. METHODS: Overall, 65 insulin-treated patients with type 2 diabetes undergoing haemodialysis (HbA1c: 7.3% ± 1.1%; age: 70.5 ± 8.5 years) were randomized (1:1) either to receive vildagliptin 50 mg/day in addition to insulin (vildagliptin-insulin group) or to pursue their usual insulin regimen (insulin-only group). Continuous glucose monitoring (CGM) was performed for 48 ± 6 hours at baseline and at week 12. The primary study endpoint was change from baseline in mean interstitial glucose using CGM. The secondary endpoints included other CGM variables and glucose control markers. RESULTS: After 12 weeks, a greater reduction in mean CGM glucose from baseline was observed in the vildagliptin-insulin group compared with the insulin-only group, although the between-treatment difference was not statistically significant (mean difference [CI 95%]: -0.96 mmol/L [-2.09; 0.18] vs. -0.29 mmol/L [-1.29; 0.76], P = 0.32). However, a significant decrease from baseline in HbA1c, glycated albumin and insulin daily doses was observed in the vildagliptin-insulin group versus the insulin-only group (-0.6% [-1.19; -0.1], P < 0.01), in the vildagliptin-insulin group versus no change in the insulin-only group (-130.6 µmol/L [-271; 10.7] vs. +36.2 µmol/L [-164.4; 236.9], P = 0.04 and - 5.9 IU/day [-1.8; 7.1] vs. +1.1 IU/day [-14.5; 16.6], P = 0.01, respectively). There was no significant difference in the percentage of time spent in hypoglycaemia using CGM, occurrence of severe hypoglycaemia or number of adverse events. CONCLUSION: In this study, vildagliptin added to insulin improved glycaemic control with an associated insulin-sparing effect in patients with type 2 diabetes undergoing haemodialysis and was well tolerated.

Organized Management of Diabetes Mellitus in Lung Transplantation: Study of Glycemic Control and Patient Survival in a Single Center.

OBJECTIVE: To study patient survival and glycemic control before and after lung transplantation (LTx) according to the diabetes status in patients submitted to an organized management of diabetes mellitus (DM) at the Strasbourg University Hospital, France. MATERIAL AND METHODS: Two hundred and sixty-seven LTx recipients were included retrospectively and analyzed according to diabetes status: pretransplant diabetes, new-onset diabetes mellitus after transplant (NODAT) or no diabetes. Organized DM management was coordinated by a diabetologist trained in DM management before and after transplantation and included pretransplant screening, a close monitoring of glycemia after transplant and optimized treatment before and after LTx. RESULTS: DM was well-controlled after transplantation: mean glycosylated hemoglobin and fasting blood glucose levels after LTx were 5.8 ± 0.2% and 5.4 ± 0.1 mmol/L respectively, in pretransplant DM patients and 5.7 ± 0.1% and 5.6 ± 0.2 mmol/L respectively, in NODAT patients. The overall median survival time was 8.3 ± 1.9 years. Pretransplant DM increased the risk of mortality (1.82-fold increase; 95% confidence interval, 1.08-3.06; P = .02) in LTx recipients. CONCLUSIONS: Organized management of diabetes achieved very satisfactory glycemic control in both pretransplant DM and NODAT patients. However, no specific protocols have been created for managing DM following LTx. As DM continues to become an increasing comorbidity in LTx, there exist a significant need of studies in this area.

Endothelial microparticles released by activated protein C protect beta cells through EPCR/PAR1 and annexin A1/FPR2 pathways in islets.

Islet transplantation is associated with early ischaemia/reperfusion, localized coagulation and redox-sensitive endothelial dysfunction. In animal models, islet cytoprotection by activated protein C (aPC) restores islet vascularization and protects graft function, suggesting that aPC triggers various lineages. aPC also prompts the release of endothelial MP that bear EPCR, its specific receptor. Microparticles (MP) are plasma membrane procoagulant vesicles, surrogate markers of stress and cellular effectors. We measured the cytoprotective effects of aPC on endothelial and insulin-secreting Rin-m5f ß-cells and its role in autocrine and paracrine MP-mediated cell crosstalk under conditions of oxidative stress. MP from aPC-treated primary endothelial (EC) or ß-cells were applied to H2 O2 -treated Rin-m5f. aPC activity was measured by enzymatic assay and ROS species by dihydroethidium. The capture of PKH26-stained MP and the expression of EPCR were probed by fluorescence microscopy and apoptosis by flow cytometry. aPC treatment enhanced both annexin A1 (ANXA1) and PAR-1 expression in EC and to a lesser extent in ß-cells. MP from aPC-treated EC (eMaPC ) exhibited high EPCR and annexin A1 content, protected ß-cells, restored insulin secretion and were captured by 80% of ß cells in a phosphatidylserine and ANXA1-dependent mechanism. eMP activated EPCR/PAR-1 and ANXA1/FPR2-dependent pathways and up-regulated the expression of EPCR, and of FPR2/ALX, the ANXA1 receptor. Cytoprotection was confirmed in H2 O2 -treated rat islets with increased viability (62% versus 48% H2 O2 ), reduced apoptosis and preserved insulin secretion in response to glucose elevation (16 versus 5 ng/ml insulin per 10 islets). MP may prove a promising therapeutic tool in the protection of transplanted islets.