The mitochondrial tRNA-derived fragment, mt-tRF-LeuTAA, couples mitochondrial metabolism to insulin secretion.

OBJECTIVE: The contribution of the mitochondrial electron transfer system to insulin secretion involves more than just energy provision. We identified a small RNA fragment (mt-tRF-LeuTAA) derived from the cleavage of a mitochondrially-encoded tRNA that is conserved between mice and humans. The role of mitochondrially-encoded tRNA-derived fragments remains unknown. This study aimed to characterize the impact of mt-tRF-LeuTAA, on mitochondrial metabolism and pancreatic islet functions. METHODS: We used antisense oligonucleotides to reduce mt-tRF-LeuTAA levels in primary rat and human islet cells, as well as in insulin-secreting cell lines. We performed a joint transcriptome and proteome analysis upon mt-tRF-LeuTAA inhibition. Additionally, we employed pull-down assays followed by mass spectrometry to identify direct interactors of the fragment. Finally, we characterized the impact of mt-tRF-LeuTAA silencing on the coupling between mitochondrial metabolism and insulin secretion using high-resolution respirometry and insulin secretion assays. RESULTS: Our study unveils a modulation of mt-tRF-LeuTAA levels in pancreatic islets in different Type 2 diabetes models and in response to changes in nutritional status. The level of the fragment is finely tuned by the mechanistic target of rapamycin complex 1. Located within mitochondria, mt-tRF-LeuTAA interacts with core subunits and assembly factors of respiratory complexes of the electron transfer system. Silencing of mt-tRF-LeuTAA in islet cells limits the inner mitochondrial membrane potential and impairs mitochondrial oxidative phosphorylation, predominantly by affecting the Succinate (via Complex II)-linked electron transfer pathway. Lowering mt-tRF-LeuTAA impairs insulin secretion of rat and human pancreatic ß-cells. CONCLUSIONS: Our findings indicate that mt-tRF-LeuTAA interacts with electron transfer system complexes and is a pivotal regulator of mitochondrial oxidative phosphorylation and its coupling to insulin secretion.

Pharmacological inhibition of tyrosine protein-kinase 2 reduces islet inflammation and delays type 1 diabetes onset in mice.

Tyrosine protein-kinase 2 (TYK2), a member of the Janus kinase family, mediates inflammatory signaling through multiple cytokines, including interferon-α (IFNα), interleukin (IL)-12, and IL-23. Missense mutations in TYK2 are associated with protection against type 1 diabetes (T1D), and inhibition of TYK2 shows promise in the management of other autoimmune conditions. Here, we evaluated the effects of specific TYK2 inhibitors (TYK2is) in pre-clinical models of T1D. First, human ß cells, cadaveric donor islets, and iPSC-derived islets were treated in vitro with IFNα in combination with a small molecule TYK2i (BMS-986165 or a related molecule BMS-986202). TYK2 inhibition prevented IFNα-induced ß cell HLA class I up-regulation, endoplasmic reticulum stress, and chemokine production. In co-culture studies, pre-treatment of ß cells with a TYK2i prevented IFNα-induced activation of T cells targeting an epitope of insulin. In vivo administration of BMS-986202 in two mouse models of T1D (RIP-LCMV-GP mice and NOD mice) reduced systemic and tissue-localized inflammation, prevented ß cell death, and delayed T1D onset. Transcriptional phenotyping of pancreatic islets, pancreatic lymph nodes (PLN), and spleen during early disease pathogenesis highlighted a role for TYK2 inhibition in modulating signaling pathways associated with inflammation, translational control, stress signaling, secretory function, immunity, and diabetes. Additionally, TYK2i treatment changed the composition of innate and adaptive immune cell populations in the blood and disease target tissues, resulting in an immune phenotype with a diminished capacity for ß cell destruction. Overall, these findings indicate that TYK2i has beneficial effects in both the immune and endocrine compartments in models of T1D, thus supporting a path forward for testing TYK2 inhibitors in human T1D.

Proinflammatory cytokines suppress nonsense-mediated RNA decay to impair regulated transcript isoform processing in pancreatic ß cells.

Introduction: Proinflammatory cytokines are implicated in pancreatic ß cell failure in type 1 and type 2 diabetes and are known to stimulate alternative RNA splicing and the expression of nonsense-mediated RNA decay (NMD) components. Here, we investigate whether cytokines regulate NMD activity and identify transcript isoforms targeted in ß cells. Methods: A luciferase-based NMD reporter transiently expressed in rat INS1(832/13), human-derived EndoC-ßH3, or dispersed human islet cells is used to examine the effect of proinflammatory cytokines (Cyt) on NMD activity. The gain- or loss-of-function of two key NMD components, UPF3B and UPF2, is used to reveal the effect of cytokines on cell viability and function. RNA-sequencing and siRNA-mediated silencing are deployed using standard techniques. Results: Cyt attenuate NMD activity in insulin-producing cell lines and primary human ß cells. These effects are found to involve ER stress and are associated with the downregulation of UPF3B. Increases or decreases in NMD activity achieved by UPF3B overexpression (OE) or UPF2 silencing raise or lower Cyt-induced cell death, respectively, in EndoC-ßH3 cells and are associated with decreased or increased insulin content, respectively. No effects of these manipulations are observed on glucose-stimulated insulin secretion. Transcriptomic analysis reveals that Cyt increases alternative splicing (AS)-induced exon skipping in the transcript isoforms, and this is potentiated by UPF2 silencing. Gene enrichment analysis identifies transcripts regulated by UPF2 silencing whose proteins are localized and/or functional in the extracellular matrix (ECM), including the serine protease inhibitor SERPINA1/α-1-antitrypsin, whose silencing sensitizes ß-cells to Cyt cytotoxicity. Cytokines suppress NMD activity via UPR signaling, potentially serving as a protective response against Cyt-induced NMD component expression. Conclusion: Our findings highlight the central importance of RNA turnover in ß cell responses to inflammatory stress.

Everolimus Mitigates the Risk of Hepatocellular Carcinoma Recurrence after Liver Transplantation.

To obtain long-term data on the use of everolimus in patients who underwent liver transplantation for hepatocellular carcinoma, we conducted a retrospective, single-center analysis of adult recipients transplanted between 2013 and 2021. Patients on everolimus-incorporating immunosuppression were matched with those on tacrolimus using an inverse probability of treatment weighting methodology. Two propensity-matched groups of patients were thus compared: 233 (45.6%) receiving everolimus versus 278 (54.4%) on tacrolimus. At a median (interquartile range) follow-up of 4.4 (3.8) years after transplantation, everolimus patients showed a reduced risk of recurrence versus tacrolimus (7.7% versus 16.9%; RR = 0.45; p = 0.002). At multivariable analysis, microvascular infiltration (HR = 1.22; p < 0.04) and a higher tumor grading (HR = 1.27; p < 0.04) were associated with higher recurrence rate while being within Milan criteria at transplant (HR = 0.56; p < 0.001), a successful pre-transplant downstaging (HR = 0.63; p = 0.01) and use of everolimus (HR = 0.46; p < 0.001) had a positive impact on the risk of post-transplant recurrence. EVR patients with earlier drug introduction (≤30 days; p < 0.001), longer treatment duration (p < 0.001), and higher drug exposure (≥5.9 ng/mL; p < 0.001) showed lower recurrence rates versus TAC. Based on our experience, everolimus provides a reduction in the relative risk of hepatocellular carcinoma recurrence, especially for advanced-stage patients and those with earlier drug administration, higher drug exposure, and longer time on treatment. These data advocate for early everolimus introduction after liver transplantation to reduce the attrition rate consequent to chronic immunosuppression.

Accuracy of intermittently scanned continuous glucose monitoring during caesarean delivery in pregnant women with insulin-treated diabetes.

AIM: Continuous Glucose Monitoring (CGM) systems are not currently recommended to guide intrapartum glucose and insulin infusion, due to insufficient data. In this study, intrapartum accuracy of intermittently scanned CGM (isCGM), compared to simultaneously measured capillary glucose (CG), was evaluated. METHODS: Paired isCGM (Freestyle Libre 2) - CG data during caesarean delivery in pregnant women with insulin-treated diabetes were prospectively collected. The isCGM accuracy was assessed by MARD and Clarke Error Grid analysis. Moreover, the impact on intrapartum management was evaluated. RESULTS: Sixty-eight paired isCGM-CG data of 19 women were evaluated. The overallMARD was 9.28 %. All values were in A and B zones of Clarke Error Grid. Forty-six (68 %) isCGM-CG pairs were in the same glycemic range, meaning the same intrapartum management. All discordant data were identified by checking CG in case of isCGM above 110 mg/dL or less than 70 mg/dL [chi-square 21.76, p < 0.001]. At ROC curve, isCGM above 110 mg/dL was associated with 100 % sensitivity to discordant result at CG (AUC 0.859, p < 0.001). CONCLUSION: The accuracy of isCGM during caesarean delivery was good, particularly for glucose values between 70 and 110 mg/dL, when CG confirmation could be safely avoided.

Differential CpG methylation at Nnat in the early establishment of beta cell heterogeneity.

AIMS/HYPOTHESIS: Beta cells within the pancreatic islet represent a heterogenous population wherein individual sub-groups of cells make distinct contributions to the overall control of insulin secretion. These include a subpopulation of highly connected 'hub' cells, important for the propagation of intercellular Ca2+ waves. Functional subpopulations have also been demonstrated in human beta cells, with an altered subtype distribution apparent in type 2 diabetes. At present, the molecular mechanisms through which beta cell hierarchy is established are poorly understood. Changes at the level of the epigenome provide one such possibility, which we explore here by focusing on the imprinted gene Nnat (encoding neuronatin [NNAT]), which is required for normal insulin synthesis and secretion. METHODS: Single-cell RNA-seq datasets were examined using Seurat 4.0 and ClusterProfiler running under R. Transgenic mice expressing enhanced GFP under the control of the Nnat enhancer/promoter regions were generated for FACS of beta cells and downstream analysis of CpG methylation by bisulphite sequencing and RNA-seq, respectively. Animals deleted for the de novo methyltransferase DNA methyltransferase 3 alpha (DNMT3A) from the pancreatic progenitor stage were used to explore control of promoter methylation. Proteomics was performed using affinity purification mass spectrometry and Ca2+ dynamics explored by rapid confocal imaging of Cal-520 AM and Cal-590 AM. Insulin secretion was measured using homogeneous time-resolved fluorescence imaging. RESULTS: Nnat mRNA was differentially expressed in a discrete beta cell population in a developmental stage- and DNA methylation (DNMT3A)-dependent manner. Thus, pseudo-time analysis of embryonic datasets demonstrated the early establishment of Nnat-positive and -negative subpopulations during embryogenesis. NNAT expression is also restricted to a subset of beta cells across the human islet that is maintained throughout adult life. NNAT+ beta cells also displayed a discrete transcriptome at adult stages, representing a subpopulation specialised for insulin production, and were diminished in db/db mice. 'Hub' cells were less abundant in the NNAT+ population, consistent with epigenetic control of this functional specialisation. CONCLUSIONS/INTERPRETATION: These findings demonstrate that differential DNA methylation at Nnat represents a novel means through which beta cell heterogeneity is established during development. We therefore hypothesise that changes in methylation at this locus may contribute to a loss of beta cell hierarchy and connectivity, potentially contributing to defective insulin secretion in some forms of diabetes. DATA AVAILABILITY: The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD048465.

CD4+ T Cells From Individuals With Type 1 Diabetes Respond to a Novel Class of Deamidated Peptides Formed in Pancreatic Islets.

The ß-cell plays a crucial role in the pathogenesis of type 1 diabetes, in part through the posttranslational modification of self-proteins by biochemical processes such as deamidation. These neoantigens are potential triggers for breaking immune tolerance. We report the detection by LC-MS/MS of 16 novel Gln and 27 novel Asn deamidations in 14 disease-related proteins within inflammatory cytokine-stressed human islets of Langerhans. T-cell clones responsive against one Gln- and three Asn-deamidated peptides could be isolated from peripheral blood of individuals with type 1 diabetes. Ex vivo HLA class II tetramer staining detected higher T-cell frequencies in individuals with the disease compared with control individuals. Furthermore, there was a positive correlation between the frequencies of T cells specific for deamidated peptides, insulin antibody levels at diagnosis, and duration of disease. These results highlight that stressed human islets are prone to enzymatic and biochemical deamidation and suggest that both Gln- and Asn-deamidated peptides can promote the activation and expansion of autoreactive CD4+ T cells. These findings add to the growing evidence that posttranslational modifications undermine tolerance and may open the road for the development of new diagnostic and therapeutic applications for individuals living with type 1 diabetes.

Aging with a Liver Graft: Analysis of Very Long-Term Survivors after Liver Transplantation.

BACKGROUND: In Italy, data on long-term survivors after liver transplantation are lacking. MATERIALS AND METHODS: We conducted a hybrid design study on a cohort of 359 adult recipients who received transplants between 1996 and 2002 to identify predictors of survival and the prevalence of co-morbidities among long-term survivors. RESULTS: The actuarial (95% CI) patient survival was 96% (94.6-98.3%), 69% (64.2-73.6%), 55% (49.8-59.9%), 42.8% (37.6-47.8%), and 34% (29.2-38.9%) at 1, 5, 10, 15, and 20 years, respectively. The leading causes of death were hepatitis C virus recurrence (24.6%), extrahepatic malignancies (16.9%), infection (14.4%), and hepatocellular carcinoma recurrence (14.4%). The factors associated with the survival probability were younger donor and recipient ages (p = 0.001 and 0.004, respectively), female recipient sex (p < 0.001), absence of HCV (p < 0.01), absence of HCC (p = 0.001), and absence of diabetes mellitus at one year (p < 0.01). At the latest follow-up, the leading comorbidities were hypertension (53.6%), obesity (18.7%), diabetes mellitus (17.1%), hyperlipidemia (14.7%), chronic kidney dysfunction (14.7%), and extrahepatic malignancies (13.8%), with 73.9% of patients having more than one complication. CONCLUSIONS: Aging with a liver graft is associated with an increased risk of complications and requires ongoing care to reduce the long-term attrition rate resulting from chronic immunosuppression.

Interferons are key cytokines acting on pancreatic islets in type 1 diabetes.

AIMS/HYPOTHESIS: The proinflammatory cytokines IFN-α, IFN-γ, IL-1ß and TNF-α may contribute to innate and adaptive immune responses during insulitis in type 1 diabetes and therefore represent attractive therapeutic targets to protect beta cells. However, the specific role of each of these cytokines individually on pancreatic beta cells remains unknown. METHODS: We used deep RNA-seq analysis, followed by extensive confirmation experiments based on reverse transcription-quantitative PCR (RT-qPCR), western blot, histology and use of siRNAs, to characterise the response of human pancreatic beta cells to each cytokine individually and compared the signatures obtained with those present in islets of individuals affected by type 1 diabetes. RESULTS: IFN-α and IFN-γ had a greater impact on the beta cell transcriptome when compared with IL-1ß and TNF-α. The IFN-induced gene signatures have a strong correlation with those observed in beta cells from individuals with type 1 diabetes, and the level of expression of specific IFN-stimulated genes is positively correlated with proteins present in islets of these individuals, regulating beta cell responses to 'danger signals' such as viral infections. Zinc finger NFX1-type containing 1 (ZNFX1), a double-stranded RNA sensor, was identified as highly induced by IFNs and shown to play a key role in the antiviral response in beta cells. CONCLUSIONS/INTERPRETATION: These data suggest that IFN-α and IFN-γ are key cytokines at the islet level in human type 1 diabetes, contributing to the triggering and amplification of autoimmunity.

Fatty liver index is an independent risk factor for all-cause mortality and major cardiovascular events in type 1 diabetes: an 11-year observational study.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD), identified by the Fatty Liver Index (FLI), is associated with increased mortality and cardiovascular (CV) outcomes. Whether this also applies to type 1 diabetes (T1D) has not been yet reported. METHODS: We prospectively observed 774 subjects with type 1 diabetes (males 52%, 30.3 ± 11.1 years old, diabetes duration (DD) 18.5 ± 11.6 years, HbA1c 7.8 ± 1.2%) to assess the associations between FLI (based on BMI, waist circumference, gamma-glutamyl transferase and triglycerides) and all-cause death and first CV events. RESULTS: Over a median 11-year follow-up, 57 subjects died (7.4%) and 49 CV events (6.7%) occurred among 736 individuals with retrievable incidence data. At baseline, FLI was < 30 in 515 subjects (66.5%), 30-59 in 169 (21.8%), and ≥ 60 in 90 (11.6%). Mortality increased steeply with FLI: 3.9, 10.1, 22.2% (p < 0.0001). In unadjusted Cox analysis, compared to FLI < 30, risk of death increased in FLI 30-59 (HR 2.85, 95% CI 1.49-5.45, p = 0.002) and FLI ≥ 60 (6.07, 3.27-11.29, p < 0.0001). Adjusting for Steno Type 1 Risk Engine (ST1-RE; based on age, sex, DD, systolic BP, LDL cholesterol, HbA1c, albuminuria, eGFR, smoking and exercise), HR was 1.52 (0.78-2.97) for FLI 30-59 and 3.04 (1.59-5.82, p = 0.001) for FLI ≥ 60. Inclusion of prior CV events slightly modified HRs. FLI impact was confirmed upon adjustment for EURODIAB Risk Engine (EURO-RE; based on age, HbA1c, waist-to-hip ratio, albuminuria and HDL cholesterol): FLI 30-59: HR 1.24, 0.62-2.48; FLI ≥ 60: 2.54, 1.30-4.95, p = 0.007), even after inclusion of prior CVD. CV events incidence increased with FLI: 3.5, 10.5, 17.2% (p < 0.0001). In unadjusted Cox, HR was 3.24 (1.65-6.34, p = 0.001) for FLI 30-59 and 5.41 (2.70-10.83, p < 0.0001) for FLI ≥ 60. After adjustment for ST1-RE or EURO-RE, FLI ≥ 60 remained statistically associated with risk of incident CV events, with trivial modification with prior CVD inclusion. CONCLUSIONS: This observational prospective study shows that FLI is associated with higher all-cause mortality and increased risk of incident CV events in type 1 diabetes.

Proinflammatory Cytokines Suppress Nonsense-Mediated RNA Decay to Impair Regulated Transcript Isoform Processing in Pancreatic ß-Cells.

Proinflammatory cytokines are implicated in pancreatic ß-cell failure in type 1 and type 2 diabetes and are known to stimulate alternative RNA splicing and the expression of Nonsense-Mediated RNA Decay (NMD) components. Here, we investigate whether cytokines regulate NMD activity and identify transcript isoforms targeted in ß-cells. A luciferase-based NMD reporter transiently expressed in rat INS1(832/13), human-derived EndoC-ßH3 or dispersed human islet cells is used to examine the effect of proinflammatory cytokines (Cyt) on NMD activity. Gain- or loss-of function of two key NMD components UPF3B and UPF2 is used to reveal the effect of cytokines on cell viability and function. RNA-sequencing and siRNA-mediated silencing are deployed using standard techniques. Cyt attenuate NMD activity in insulin-producing cell lines and primary human ß-cells. These effects are found to involve ER stress and are associated with downregulation of UPF3B. Increases or decreases in NMD activity achieved by UPF3B overexpression (OE) or UPF2 silencing, raises or lowers Cyt-induced cell death, respectively, in EndoC-ßH3 cells, and are associated with decreased or increased insulin content, respectively. No effects of these manipulations are observed on glucose-stimulated insulin secretion. Transcriptomic analysis reveals that Cyt increase alternative splicing (AS)-induced exon skipping in the transcript isoforms, and this is potentiated by UPF2 silencing. Gene enrichment analysis identifies transcripts regulated by UPF2 silencing whose proteins are localized and/or functional in extracellular matrix (ECM) including the serine protease inhibitor SERPINA1/α-1-antitrypsin, whose silencing sensitises ß-cells to Cyt cytotoxicity. Cytokines suppress NMD activity via UPR signalling, potentially serving as a protective response against Cyt-induced NMD component expression. Our findings highlight the central importance of RNA turnover in ß-cell responses to inflammatory stress.

Immunosuppression for older liver transplant recipients.

Older liver transplant recipients have a lower risk of acute rejection than younger patients (9% for patients aged ≥65 years versus 23% for those aged 18-34 years) and are more vulnerable to immunosuppression-related complications. The number of liver transplant recipients ≥65 years has risen to 22% in Europe and the US, but limited information is available on the optimal immunosuppressive regimen for these patients. In this review, we discuss the appropriate management of immunosuppressive agents in older adults to minimize adverse events while avoiding acute rejection. The way the body processes drugs greatly depends on age. In the case of calcineurin inhibitor drugs, aging reduces hepatic metabolism, leading to changes in their pharmacokinetics. Corticosteroids also show decreased clearance as the patient ages. In severe cases of hypoalbuminemia, dose adjustment of mycophenolate acid derivatives may be necessary. However, the pharmacokinetic profiles of the mammalian target of rapamycin inhibitors, basiliximab, and rabbit anti-thymocyte globulin remain unaffected by age. Furthermore, age-related frailty may impact drug metabolism and require tailored interventions and closer follow-up. Although there is limited research, elderly liver transplant recipients require less immunosuppression with double or triple-agent regimens, lower exposure to calcineurin inhibitors, and a shorter course of corticosteroids. The usage of mammalian target of rapamycin inhibitors in older transplant populations has not been specifically investigated, and thus their usage should align with indications for younger patient groups.

Differential CpG methylation at Nnat in the early establishment of beta cell heterogeneity.

Aims/hypothesis: Beta cells within the pancreatic islet represent a heterogenous population wherein individual sub-groups of cells make distinct contributions to the overall control of insulin secretion. These include a subpopulation of highly-connected 'hub' cells, important for the propagation of intercellular Ca2+ waves. Functional subpopulations have also been demonstrated in human beta cells, with an altered subtype distribution apparent in type 2 diabetes. At present, the molecular mechanisms through which beta cell hierarchy is established are poorly understood. Changes at the level of the epigenome provide one such possibility which we explore here by focussing on the imprinted gene neuronatin (Nnat), which is required for normal insulin synthesis and secretion. Methods: Single cell RNA-seq datasets were examined using Seurat 4.0 and ClusterProfiler running under R. Transgenic mice expressing eGFP under the control of the Nnat enhancer/promoter regions were generated for fluorescence-activated cell (FAC) sorting of beta cells and downstream analysis of CpG methylation by bisulphite and RNA sequencing, respectively. Animals deleted for the de novo methyltransferase, DNMT3A from the pancreatic progenitor stage were used to explore control of promoter methylation. Proteomics was performed using affinity purification mass spectrometry and Ca2+ dynamics explored by rapid confocal imaging of Cal-520 and Cal-590. Insulin secretion was measured using Homogeneous Time Resolved Fluorescence Imaging. Results: Nnat mRNA was differentially expressed in a discrete beta cell population in a developmental stage- and DNA methylation (DNMT3A)-dependent manner. Thus, pseudo-time analysis of embryonic data sets demonstrated the early establishment of Nnat-positive and negative subpopulations during embryogenesis. NNAT expression is also restricted to a subset of beta cells across the human islet that is maintained throughout adult life. NNAT+ beta cells also displayed a discrete transcriptome at adult stages, representing a sub-population specialised for insulin production, reminiscent of recently-described "ßHI" cells and were diminished in db/db mice. 'Hub' cells were less abundant in the NNAT+ population, consistent with epigenetic control of this functional specialization. Conclusions/interpretation: These findings demonstrate that differential DNA methylation at Nnat represents a novel means through which beta cell heterogeneity is established during development. We therefore hypothesise that changes in methylation at this locus may thus contribute to a loss of beta cell hierarchy and connectivity, potentially contributing to defective insulin secretion in some forms of diabetes.

Advances in diabetes management: have pregnancy outcomes in women with type 1 diabetes changed in the last decades?

AIMS: Over the recent years multiple therapeutic and management opportunities have been made available to treat pregnant women with Type 1 diabetes (T1DM). However, analyses assessing whether these different approaches may have any specific advantage/disadvantage in metabolic control and neonatal outcomes is still limited. The aim of this study was to compare metabolic control and neonatal outcomes in pregnant women with T1DM among different basal insulins (NPH vs. analogue), insulin administration ways [Multiple Daily Injections (MDI) vs. Continuous Subcutaneous Insulin Infusion (CSII)] and glucose monitoring systems [Self-Monitoring of Blood Glucose (SMBG) vs. real-time/intermittently scanned Continuous Glucose Monitoring (rtCGM/isCGM)]. METHODS: A retrospective analysis on metabolic data and neonatal outcomes of 136 T1DM pregnant women (76% on MDI, based on NPH (51%) or analogue (49%); 24% on CSII; 24% using rtCGM/isCGM), managed between 2008 and 2020, was performed, comparing different therapeutic approaches. RESULTS: Metabolic data and neonatal outcomes were comparable among women treated with different basal insulins. Women on CSII planned their pregnancy more frequently (82 vs. 60%; p = 0.043) and had better pregestational HbA1c (52 ± 5 vs. 60 ± 13 mmol/mol; p = 0.044) and first trimester HbA1c (48 ± 4 vs. 51 ± 8 mmol/mol; p = 0.047). Pregestational and first trimester HbA1c were also lower in women using rtCGM/isCGM (53 ± 8 vs. 58 ± 13 mmol/mol; p = 0.027 and 46 ± 5 vs. 51 ± 7 mmol/mol; p = 0.034, respectively). In the whole cohort, LGA risk was directly correlated to HbA1c at third trimester (correlation coefficient: 0.335, p = 0.001) and inversely correlated to the achievement of HbA1c target (≤6% [<42 mmol/mol]) at third trimester (correlation coefficient: - 0.367, p < 0.001). CONCLUSION: Treatment with insulin analogs didn't significantly change metabolic control and neonatal outcomes in T1DM women, while CSII and rtCGM/isCGM can optimize preconception and first trimester pregnancy glycemic control. Irrespective of the therapeutic management, third trimester HbA1c remains the strongest risk factor for LGA.

Interferon-α promotes neo-antigen formation and preferential HLA-B-restricted antigen presentation in pancreatic ß-cells.

Interferon (IFN)-α is the earliest cytokine signature observed in individuals at risk for type 1 diabetes (T1D), but its effect on the repertoire of HLA Class I (HLA-I)-bound peptides presented by pancreatic ß-cells is unknown. Using immunopeptidomics, we characterized the peptide/HLA-I presentation in in-vitro resting and IFN-α-exposed ß-cells. IFN-α increased HLA-I expression and peptide presentation, including neo-sequences derived from alternative mRNA splicing, post-translational modifications - notably glutathionylation - and protein cis-splicing. This antigenic landscape relied on processing by both the constitutive and immune proteasome. The resting ß-cell immunopeptidome was dominated by HLA-A-restricted ligands. However, IFN-α only marginally upregulated HLA-A and largely favored HLA-B, translating into a major increase in HLA-B-restricted peptides and into an increased activation of HLA-B-restricted vs. HLA-A-restricted CD8+ T-cells. A preferential HLA-B hyper-expression was also observed in the islets of T1D vs. non-diabetic donors, and we identified islet-infiltrating CD8+ T-cells from T1D donors reactive to HLA-B-restricted granule peptides. Thus, the inflammatory milieu of insulitis may skew the autoimmune response toward epitopes presented by HLA-B, hence recruiting a distinct T-cell repertoire that may be relevant to T1D pathogenesis.

Unveiling nanoscale optical signatures of cytokine-induced ß-cell dysfunction.

Pro-inflammatory cytokines contribute to ß-cell failure in both Type-1 and Type-2 Diabetes. Data collected so far allowed to dissect the genomic, transcriptomic, proteomic and biochemical landscape underlying cytokine-induced ß-cell progression through dysfunction. Yet, no report thus far complemented such molecular information with the direct optical nanoscopy of the ß-cell subcellular environment. Here we tackle this issue in Insulinoma 1E (INS-1E) ß-cells by label-free fluorescence lifetime imaging microscopy (FLIM) and fluorescence-based super resolution imaging by expansion microscopy (ExM). It is found that 24-h exposure to IL-1ß and IFN-γ is associated with a neat modification of the FLIM signature of cell autofluorescence due to the increase of either enzyme-bound NAD(P)H molecules and of oxidized lipid species. At the same time, ExM-based direct imaging unveils neat alteration of mitochondrial morphology (i.e. ~ 80% increase of mitochondrial circularity), marked degranulation (i.e. ~ 40% loss of insulin granules, with mis-localization of the surviving pool), appearance of F-actin-positive membrane blebs and an hitherto unknown extensive fragmentation of the microtubules network (e.g. ~ 37% reduction in the number of branches). Reported observations provide an optical-microscopy framework to interpret the amount of molecular information collected so far on ß-cell dysfunction and pave the way to future ex-vivo and in-vivo investigations.

Angiotensin I-converting enzyme type 2 expression is increased in pancreatic islets of type 2 diabetic donors.

AIMS: Angiotensin I-converting enzyme type 2 (ACE2), a pivotal SARS-CoV-2 receptor, has been shown to be expressed in multiple cells, including human pancreatic beta-cells. A putative bidirectional relationship between SARS-CoV-2 infection and diabetes has been suggested, confirming the hypothesis that viral infection in beta-cells may lead to new-onset diabetes or worse glycometabolic control in diabetic patients. However, whether ACE2 expression levels are altered in beta-cells of diabetic patients has not yet been investigated. Here, we aimed to elucidate the in situ expression pattern of ACE2 in Type 2 diabetes (T2D) with respect to non-diabetic donors which may account for a higher susceptibility to SARS-CoV-2 infection in beta-cells. MATERIAL AND METHODS: Angiotensin I-converting enzyme type 2 immunofluorescence analysis using two antibodies alongside insulin staining was performed on formalin-fixed paraffin embedded pancreatic sections obtained from n = 20 T2D and n = 20 non-diabetic (ND) multiorgan donors. Intensity and colocalisation analyses were performed on a total of 1082 pancreatic islets. Macrophage detection was performed using anti-CD68 immunohistochemistry on serial sections from the same donors. RESULTS: Using two different antibodies, ACE2 expression was confirmed in beta-cells and in pancreas microvasculature. Angiotensin I-converting enzyme type 2 expression was increased in pancreatic islets of T2D donors in comparison to ND controls alongside with a higher colocalisation rate between ACE2 and insulin using both anti-ACE2 antibodies. CD68+ cells tended to be increased in T2D pancreata, in line with higher ACE2 expression observed in serial sections. CONCLUSIONS: Higher ACE2 expression in T2D islets might increase their susceptibility to SARS-CoV-2 infection during COVID-19 in T2D patients, thus worsening glycometabolic outcomes and disease severity.

The power of TOPMed imputation for the discovery of Latino-enriched rare variants associated with type 2 diabetes.

AIMS/HYPOTHESIS: The Latino population has been systematically underrepresented in large-scale genetic analyses, and previous studies have relied on the imputation of ungenotyped variants based on the 1000 Genomes (1000G) imputation panel, which results in suboptimal capture of low-frequency or Latino-enriched variants. The National Heart, Lung, and Blood Institute (NHLBI) Trans-Omics for Precision Medicine (TOPMed) released the largest multi-ancestry genotype reference panel representing a unique opportunity to analyse rare genetic variations in the Latino population. We hypothesise that a more comprehensive analysis of low/rare variation using the TOPMed panel would improve our knowledge of the genetics of type 2 diabetes in the Latino population. METHODS: We evaluated the TOPMed imputation performance using genotyping array and whole-exome sequence data in six Latino cohorts. To evaluate the ability of TOPMed imputation to increase the number of identified loci, we performed a Latino type 2 diabetes genome-wide association study (GWAS) meta-analysis in 8150 individuals with type 2 diabetes and 10,735 control individuals and replicated the results in six additional cohorts including whole-genome sequence data from the All of Us cohort. RESULTS: Compared with imputation with 1000G, the TOPMed panel improved the identification of rare and low-frequency variants. We identified 26 genome-wide significant signals including a novel variant (minor allele frequency 1.7%; OR 1.37, p=3.4 × 10-9). A Latino-tailored polygenic score constructed from our data and GWAS data from East Asian and European populations improved the prediction accuracy in a Latino target dataset, explaining up to 7.6% of the type 2 diabetes risk variance. CONCLUSIONS/INTERPRETATION: Our results demonstrate the utility of TOPMed imputation for identifying low-frequency variants in understudied populations, leading to the discovery of novel disease associations and the improvement of polygenic scores. DATA AVAILABILITY: Full summary statistics are available through the Common Metabolic Diseases Knowledge Portal ( https://t2d.hugeamp.org/downloads.html ) and through the GWAS catalog ( https://www.ebi.ac.uk/gwas/ , accession ID: GCST90255648). Polygenic score (PS) weights for each ancestry are available via the PGS catalog ( https://www.pgscatalog.org , publication ID: PGP000445, scores IDs: PGS003443, PGS003444 and PGS003445).

GLP-1R agonists demonstrate potential to treat Wolfram syndrome in human preclinical models.

AIMS/HYPOTHESIS: Wolfram syndrome is a rare autosomal recessive disorder caused by pathogenic variants in the WFS1 gene. It is characterised by insulin-dependent diabetes mellitus, optic nerve atrophy, diabetes insipidus, hearing loss and neurodegeneration. Considering the unmet treatment need for this orphan disease, this study aimed to evaluate the therapeutic potential of glucagon-like peptide 1 receptor (GLP-1R) agonists under wolframin (WFS1) deficiency with a particular focus on human beta cells and neurons. METHODS: The effect of the GLP-1R agonists dulaglutide and exenatide was examined in Wfs1 knockout mice and in an array of human preclinical models of Wolfram syndrome, including WFS1-deficient human beta cells, human induced pluripotent stem cell (iPSC)-derived beta-like cells and neurons from control individuals and individuals affected by Wolfram syndrome, and humanised mice. RESULTS: Our study shows that the long-lasting GLP-1R agonist dulaglutide reverses impaired glucose tolerance in WFS1-deficient mice, and that exenatide and dulaglutide improve beta cell function and prevent apoptosis in different human WFS1-deficient models including iPSC-derived beta cells from people with Wolfram syndrome. Exenatide improved mitochondrial function, reduced oxidative stress and prevented apoptosis in Wolfram syndrome iPSC-derived neural precursors and cerebellar neurons. CONCLUSIONS/INTERPRETATION: Our study provides novel evidence for the beneficial effect of GLP-1R agonists on WFS1-deficient human pancreatic beta cells and neurons, suggesting that these drugs may be considered as a treatment for individuals with Wolfram syndrome.

Inhibition of the type 1 diabetes candidate gene PTPN2 aggravates TNF-α-induced human beta cell dysfunction and death.

AIMS/HYPOTHESIS: TNF-α plays a role in pancreatic beta cell loss in type 1 diabetes mellitus. In clinical interventions, TNF-α inhibition preserves C-peptide levels in early type 1 diabetes. In this study we evaluated the crosstalk of TNF-α, as compared with type I IFNs, with the type 1 diabetes candidate gene PTPN2 (encoding protein tyrosine phosphatase non-receptor type 2 [PTPN2]) in human beta cells. METHODS: EndoC-ßH1 cells, dispersed human pancreatic islets or induced pluripotent stem cell (iPSC)-derived islet-like cells were transfected with siRNAs targeting various genes (siCTRL, siPTPN2, siJNK1, siJNK3 or siBIM). Cells were treated for 48 h with IFN-α (2000 U/ml) or TNF-α (1000 U/ml). Cell death was evaluated using Hoechst 33342 and propidium iodide staining. mRNA levels were assessed by quantitative reverse transcription PCR (qRT-PCR) and protein expression by immunoblot. RESULTS: PTPN2 silencing sensitised beta cells to cytotoxicity induced by IFN-α and/or TNF-α by 20-50%, depending on the human cell model utilised; there was no potentiation between the cytokines. We silenced c-Jun N-terminal kinase (JNK)1 or Bcl-2-like protein 2 (BIM), and this abolished the proapoptotic effects of IFN-α, TNF-α or the combination of both after PTPN2 inhibition. We further observed that PTPN2 silencing increased TNF-α-induced JNK1 and BIM phosphorylation and that JNK3 is necessary for beta cell resistance to IFN-α cytotoxicity. CONCLUSIONS/INTERPRETATION: We show that the type 1 diabetes candidate gene PTPN2 is a key regulator of the deleterious effects of TNF-α in human beta cells. It is conceivable that people with type 1 diabetes carrying risk-associated PTPN2 polymorphisms may particularly benefit from therapies inhibiting TNF-α.