Intrahepatic islet transplantation is followed by islet loss due to the instant blood-mediated inflammatory response (IBMIR) in which platelet activation plays a key role. The KEATSTF-fragment (KF7), a newly discovered platelet inhibitor that interferes with the formation of the 14-3-3ζ-c-Src-integrin-β3 complex, holds significant potential in inhibiting IBMIR without causing significant bleeding. This study introduces a novel surface modification technique using 3,4-dihydroxy-l-phenylalanine (L-DOPA) conjugated with KF7 to enhance the engraftment of transplanted islets in a syngeneic marginal mass model. KF7 loaded with L-DOPA (L-DOPA-KF7) formed a protective coating on the surface of islets without interfering with their viability and functionality. Islets coated with L-DOPA-KF7 restored normoglycemia in diabetic mice, and survival time was significantly longer compared with the control group. Transplantation of L-DOPA-KF7-coated islets was associated with reduced blood clot formation and decreased infiltration of CD11b+ cells and platelets. In conclusion, a composite L-DOPA-KF7 coating significantly prolongs the survival of transplanted islets by providing a robust IBMIR isolation barrier, thereby enhancing the overall success of islet transplantation in preclinical models.

Pathologic signaling via the receptor for advanced glycation end products (RAGE) is critical to diabetic kidney disease (DKD) development, whereas RAGE deletion is renoprotective. Noncoding RNAs (ncRNAs), including miRNAs, also play key roles in DKD, including in renal fibrosis. However, the involvement of ncRNAs in RAGE signaling remains unclear. This study investigated the regulation of ncRNAs by RAGE and assessed renal expression of ncRNAs, miRNAs, and fibrotic/inflammatory markers in diabetic RAGE-knockout and wild-type (WT) mice as well as in mesangial cells (MCs) obtained from these mice. Diabetes induction in both RAGE-/- and WT mice was associated with elevated renal expression of miR-214 and its host ncRNA, Dnm3os. miR-214 and Dnm3os levels were remarkably higher in RAGE-/- MCs compared with WT MCs. Overexpression of miR-214 in WT MCs reduced fibrotic/inflammatory gene expression, whereas its inhibition increased these markers. Human DKD tissue demonstrated higher DNM3os expression compared with controls. Notably, miR-214 targeted the RAGE signaling mediator protein diaphanous homolog 1 (DIAPH1), whereas Dnm3os had an opposite effect, enhancing fibrosis and inflammation. miR-214 administration in a DKD mouse model significantly reduced renal fibrosis. These findings suggest a novel mechanism by which miR-214 and Dnm3os act as negative and positive regulators of fibrosis via the RAGE-DIAPH1 axis.

Since little is known about the disposition index (DI) in autoantibody-positive individuals, we have assessed whether DI has a similar association between insulin secretion and sensitivity to the association observed in other populations. In TrialNet Pathway to Prevention (TNPTP; n = 6,620) and Diabetes Prevention Trial-Type 1 (DPT-1; n = 704) study participants, two secretion-sensitivity pairs, each representing a DI, were analyzed cross-sectionally at baseline: area under the curve (AUC) C-peptide/AUC glucose (AUC ratio) and Matsuda index (MI) from TNPTP oral glucose tolerance tests (oral DI), first-phase insulin response (FPIR), and 1 / fasting insulin (1/FI) from DPT-1 from intravenous glucose tolerance tests (DI). Participants were followed for progression to type 1 diabetes (T1D). Within the normal and diabetes glucose ranges, associations of AUC ratio with MI in TNPTP and FPIR with 1/FI in DPT-1 had inverse curvilinear patterns with convexities to the origin. After logarithmic transformations to linearize the secretion and sensitivity measures, the inverse slope was steeper for the diabetes range (P < 0.0001). In a Cox regression model including the AUC ratio and MI as variables and another model including FPIR and 1/FI, the interaction terms of secretion × sensitivity (i.e., the DI/oral DI) predicted stage 3 T1D in both (P < 0.0001). The DI remained significantly predictive (P < 0.0001) when the DPT-1 risk score was added as a covariate in regression models. In autoantibody-positive populations, insulin secretion is inversely related to sensitivity in a quasi-hyperbolic relationship in normal and diabetes ranges of glucose. The DI can be represented by a statistical and physiologic interaction between secretion and sensitivity that is predictive of stage 3 T1D.

Activation of GPR119 receptors, expressed on enteroendocrine and pancreatic islet cells, augments glucagon counterregulatory responses to hypoglycemia in preclinical models. We hypothesized that MBX-2982, a GPR119 agonist, would augment counterregulatory responses to experimental hypoglycemia in participants with type 1 diabetes (T1D). To assess this, we designed a phase 2a, double-masked, crossover trial in 18 participants (age 20-60 years) with T1D. Participants were randomized to treatment with 600 mg MBX-2982 or placebo daily for 14 days, with a 2-week washout between treatments. Counterregulatory responses to hypoglycemia during a hyperinsulinemic euglycemic-hypoglycemic clamp and hormonal responses during a mixed-meal test (MMT) were measured. The maximum glucagon response, glucagon area under the curve (AUC), and incremental AUC were not significantly different during MBX-2982 versus placebo treatment. MBX-2982 did not alter epinephrine, norepinephrine, pancreatic polypeptide, free fatty acid, or endogenous glucose production responses to hypoglycemia compared with placebo. However, glucagon-like peptide 1 (GLP-1) response during the MMT was 17% higher with MBX-2982 compared with placebo treatment. In conclusion, GPR119 activation with MBX-2982 did not improve counterregulatory responses to hypoglycemia in people with T1D. Increases in GLP-1 during the MMT are consistent with GPR119 target engagement and the expected pharmacodynamic response from L cells.

G protein-coupled receptor 119 (GPR119) is predominantly expressed in pancreatic β-cells, enteroendocrine cells, and the liver. It is a novel therapeutic for dyslipidemia and type 2 diabetes. DA-1241, a GPR119 agonist, improves glucose tolerance by inhibiting gluconeogenesis and enhancing insulin secretion. It mitigates hepatic inflammation by inhibiting NFκB signaling. However, the mechanism by which DA-1241 ameliorates nonalcoholic fatty liver disease (NAFLD) remains unknown. We hypothesized that DA-1241 improves liver steatosis by inducing autophagy in a transcriptional factor EB (TFEB)-dependent manner. It induced autophagy and TFEB nuclear translocation, and decreased lipid content in liver cell lines. Lysotracker staining and DQ-Red BSA assay revealed it increased lysosomal activity. Furthermore, DA-1241 increased the colocalization of mRFP-LC3 and lipid droplets, which were completely abolished by GPR119 knockdown. DA-1241 treatment improved glucose tolerance and insulin sensitivity, reduced liver enzymes activity and hepatic triglyceride levels, and decreased the NAFLD activity score, accompanied by an increased number of autophagosomes and lysosomes in high-fat diet-fed mice. Despite DA-1241 treatment, lysosomal activity and subsequent lipid content reduction were not induced in tfeb knockout HeLa cells. DA-1241 treatment failed to produce favorable metabolic effects, including reduced hepatic triglyceride levels, in liver-specific Tfeb knockout mice. Thus, DA-1241 attenuates hepatic steatosis through TFEB-mediated autophagy induction.

Effective treatment strategies for diabetes-related pain are limited because of its complex pathogenesis, particularly brain mechanisms underlying this disease. The acid-sensing ion channel 1a (ASIC1a) has emerged as a key player in the development and treatment of various types of pain. We investigated the role of ASIC1a in diabetes-related pain and its molecular mechanisms in the anterior cingulate cortex (ACC). Our findings demonstrate that the upregulation of ASIC1a expression drives enhanced activity of excitatory glutamatergic neurons in the ACC (ACCGlu), promoting the development of pain hypersensitivity in streptozotocin (STZ)-induced diabetic male mice. Pharmacologic inhibition and genetic knockout of ASIC1a in ACCGlu neurons significantly reduced neuronal activity and alleviated mechanical and thermal pain sensitizations in STZ-induced diabetes. Furthermore, increased levels of tumor necrosis factor-α (TNF-α) in the ACC upregulated ASIC1a by triggering nuclear factor-κB (NF-κB) pathways, which led to the development of diabetes-related pain. Notably, the clinically used medication, infliximab, exhibited therapeutic effects on diabetes-related pain via its influence on TNF-α/NF-κB/ASIC1a pathway in STZ-treated mice. Collectively, this study identifies ASIC1a as a potential therapeutic target for diabetes-related pain and shows the neutralization of TNF-α leads to pain relief through the TNF-α/NF-κB/ASIC1a pathway in the ACC. These findings hold promise for the development of new clinical therapeutic strategies for diabetes-related pain.

Glucagon stimulates hepatic glucose production, in part by promoting the uptake and catabolism of amino acids. Inhibition of the liver glucagon receptor (GCGR) results in elevated plasma amino acids, which triggers the proliferation of pancreatic α-cells, forming a liver-α-cell loop. This study aims to delineate hepatic signaling molecules downstream of GCGR that mediate the liver-α-cell loop. We knocked down liver GCGR, its G-coupled protein GNAS, and two GNAS downstream effectors, PKA and EPAC2 (RAPGEF4). Mice with GCGR, GNAS, and PKA knockdown had similar suppression of hepatic amino acid catabolism genes, hyperaminoacidemia, and α-cell hyperplasia, but those with EPAC2 knockdown did not. We then demonstrated that activating liver PKA was sufficient to reverse hyperaminoacidemia and α-cell hyperplasia caused by GCGR blockade. These results suggest that liver GCGR signals through PKA to control amino acid metabolism and that hepatic PKA plays a critical role in the liver-α-cell loop.

Patients with diabetes are at an increased risk of diabetic cardiomyopathy (DCM) and acute myocardial infarction (AMI). Protecting the heart against AMI is more challenging in DCM than in nondiabetic hearts. We investigated whether intravenous (i.v.) atorvastatin administration during AMI exerts cardioprotection in DCM as seen in nondiabetic hearts. Sprague-Dawley rats were divided into streptozotocin-induced DCM and normoglycemic control groups. Our model of DCM rats exhibited interstitial fibrosis and cardiac dysfunction at 5 weeks. At this time point, all animals underwent AMI induction (coronary ligation for 45 min), receiving i.v. atorvastatin or vehicle during ischemia. Animals were reperfused and sacrificed 24 h later for myocardial infarct size analysis and cardiac tissue sampling. Echocardiography was performed. DCM vehicle rats had larger infarcts than normoglycemic vehicle-treated animals at a comparable area-at-risk. Intravenous atorvastatin reduced infarct size and preserved systolic function in both groups. Compared with vehicle animals, i.v. atorvastatin inhibited RhoA membrane translocation, induced AMPK phosphorylation, prevented apoptosis execution, and improved cardiac remodelling in the infarcted heart of both groups, whereas innate immune cell infiltration was further reduced in i.v. atorvastatin-treated DCM animals. The proven cardioprotective effectiveness of this i.v. statin formulation in the presence of DCM warrants its further development into a clinically therapeutic option.

HLA class I (HLA-I) molecules present intracellular antigenic peptides to CD8+ T cells during immune surveillance. In donors with type 1 diabetes, hyperexpression of HLA-I occurs in islets with residual insulin-producing β-cells as a hallmark of the disease. HLA-I hyperexpression is frequently detected beyond the islet boundary, forming a "halo." We hypothesized that this halo may reflect the diffusion of soluble forms of HLA-I (sHLA-I) from the islets to the surrounding pancreatic parenchyma. To verify this, we assessed the expression of total, cell surface, and sHLA-I in β-cell lines and isolated human islets after treatment with interferon-α (IFN-α) and IFN-γ. Consistent with the expression patterns of HLA-I in situ, the β-cell lines and cultured human islets dramatically upregulated total and surface HLA-I when exposed to IFNs. Concomitantly, sHLA-I release was significantly increased. HLA-I released within extracellular vesicles and cleaved forms of HLA-I did not significantly contribute to the sHLA-I pool. Rather, IFNs upregulated mRNA splice variants lacking the transmembrane domain. Our findings suggest that β-cells respond to IFNs by upregulating cell-associated and soluble forms of HLA-I. Soluble HLA-I may play a role in modulating islet inflammation during the autoimmune attack.

Recent evidence has shown that adipose tissue eventually develops fibrosis through complex cellular cross talk. Although advances in single-cell transcriptomics have provided new insights into cell diversity during this process, little is known about the interactions among the distinct cell types. In this study, we used single-cell analytical approaches to investigate cell-to-cell communications between macrophages and fibroblasts in the adipose tissue of diet-induced obese mice. Spatial transcriptomics was used to understand local cellular interaction within crown-like structures (CLS), a characteristic histological feature of adipose tissue in obesity driving inflammation and fibrosis. Macrophages and fibroblasts were divided into several subclusters that appeared to interact more intensely and complexly with the degree of obesity. Besides previously reported lipid-associated macrophages (LAMs), we found a small subcluster expressing macrophage-inducible C-type lectin (Mincle), specifically localizing to CLS. Mincle signaling increased the expression of oncostatin M (Osm), suppressing collagen gene expression in adipose tissue fibroblasts. Consistent with these findings, Osm deficiency in immune cells enhanced obesity-induced adipose tissue fibrosis in vivo. Moreover, OSM expression was positively correlated with MINCLE expression in human adipose tissue during obesity. Our results suggest that Osm secreted by Mincle-expressing macrophages is involved in dynamic adipose tissue remodeling in the proximity of CLS.

This study compares novel type 1 diabetes-related autoantibody assays developed to improve upon the standard radiobinding assay (RBA). Samples from 1505 individuals, followed for 5 years or to clinical type 1 diabetes, originally tested by RBA were aliquoted and sent blindly to 5 laboratories (BDC, IDR, DRI, MSD, Enable) to be tested by electrochemiluminescence (ECL) assays, Luciferase Immuno Precipitation System (LIPS) assays, multiplex antibody detection by agglutination-PCR (ADAP) assays, and N-terminally truncated GAD65 or IA2β autoantibody RBAs (tGADA/IA2βA). Findings: The fraction of samples that were concordant for negative/positive interpretations across all assays were 79.7% (GADA), 65.2% (IA-2A), 36.2% (IAA), and 67.5% (ZnT8A). The assays with the highest Youden index for predicting the previous RBA results differed by autoantibody: 0.65 LIPS(IDR) for IAA, 0.91 ECL(BDC) for ZnT8A, 0.82 tGADA RBA(IDR) for GADA, 0.91 ECL(MSD and BDC) for IA-2A. The Youden index for predicting 5-year type 1 diabetes varied significantly across assays and was highest for LIPS(DRI) for all autoantibody combinations, with little variation in the respective maximum Youden index. The discordance between assays makes it problematic to interpret positivity when comparing results from different assays. Longitudinal autoantibody assessments should be tested with the same assay.

Genome-wide association studies have identified SH2B3 as an important non-MHC gene for islet autoimmunity and type 1 diabetes (T1D). In this study, we found a single SH2B3 haplotype significantly associated with increased risk for human T1D. Fine mapping has demonstrated the most credible causative variant is the single nucleotide rs3184504*T polymorphism in SH2B3. To better characterize the role of SH2B3 in T1D, we used mouse modeling and found a T-cell-intrinsic role for SH2B3 regulating peripheral tolerance. SH2B3 deficiency had minimal effect on T-cell receptor (TCR) signaling or proliferation across antigen doses, yet enhanced cell survival and cytokine signaling including common γ-chain-dependent and interferon-γ receptor signaling. SH2B3-deficient naive CD8+ T cells showed augmented STAT5-MYC and effector-related gene expression partially reversed with blocking autocrine IL-2 in culture. Using the rat insulin promoter-membrane-bound ovalbumin (RIP-mOVA) model, we found CD8+ T cells lacking SH2B3 promoted early islet destruction and diabetes without requiring CD4+ T cell help. SH2B3-deficient cells demonstrated increased survival and reduced activation-induced cell death. Lastly, we created a spontaneous NOD.Sh2b3-/- mouse model and found markedly increased incidence and accelerated T1D across sexes. Collectively, these studies identify SH2B3 as a critical mediator of peripheral T-cell tolerance limiting the T-cell response to self-antigens.

We investigated the association between plasma angiogenin and the risk of progression to end-stage kidney disease (ESKD) in patients with type 2 diabetes (T2D) and attempted to infer the causal relationship between plasma angiogenin and chronic kidney disease. A total of 1,863 outpatients with T2D were included in this prospective cohort study. ESKD was defined as a composite of progression to sustained estimated glomerular filtration rate (eGFR) <15 mL/min/1.73 m2, maintenance dialysis, or death due to renal causes. The secondary outcome was rapid kidney function decline defined as a eGFR decline of 5 mL/min/1.73 m2 or greater per year. Over a median follow-up of 9.3 years, 125 incident ESKD events were identified. Elevated plasma angiogenin levels were associated with an increased risk of incident ESKD (adjusted hazard ratio 1.25 [95% CI 1.01-1.55], per 1 SD) independent of cardiorenal risk factors including baseline eGFR and albuminuria. A high level of plasma angiogenin was also associated with an increased risk for rapid kidney function decline (adjusted odds ratio 1.31 [95% CI 1.07-1.61], per 1 SD). A two-sample Mendelian randomization approach suggested a potential causal relationship between plasma angiogenin and chronic kidney disease. Plasma angiogenin may be a novel biomarker and potential therapeutic target for progressive kidney disease in patients with T2D.

Current treatments for type 1 diabetes (T1D) focus on insulin replacement. We demonstrated the therapeutic potential of a secreted protein fraction from embryonic brown adipose tissue (BAT) that mediates insulin receptor-dependent recovery of euglycemia in a T1D, nonobese diabetic (NOD) mouse model, by suppressing glucagon secretion. This fraction promoted white adipocyte differentiation and browning, maintained healthy BAT, and enhanced glucose uptake in adipose tissue, skeletal muscle, and liver. We identified nidogen-2 as a critical BAT-secreted protein that reverses hyperglycemia in NOD mice, inhibits glucagon secretion from pancreatic α-cells, and mimics other actions of the entire secreted fraction. Secretions from a BAT cell line with siRNA knockdown of nidogen-2 failed to inhibit glucagon secretion and restore euglycemia. These findings demonstrate that BAT-secreted peptides represent a novel therapeutic approach to diabetes management. Furthermore, our research reveals a novel signaling role for nidogen-2 beyond its traditional classification as an extracellular matrix protein.

Cadaveric islet and stem cell-derived transplantation hold promise as treatments for type 1 diabetes. To tackle the issue of immunocompatibility, numerous cellular macroencapsulation techniques that use diffusion to transport insulin across an immunoisolating barrier have been developed. However, despite several devices progressing to human clinical trials, none have successfully attained physiological glucose control or insulin independence. Based on empirical evidence, macroencapsulation methods with multilayered, high islet surface density are incompatible with on-demand insulin delivery and physiological glucose regulation when solely reliant on diffusion. An additional driving force is essential to overcome the distance limit of diffusion. In this study, we present both theoretical evidence and experimental validation that applying pressure, at levels comparable to physiological diastolic blood pressure, significantly enhances insulin flux across immunoisolation membranes, increasing it by nearly three orders of magnitude. This significant enhancement in transport rate allows for precise, subminute regulation of both bolus and basal insulin delivery. By incorporating this technique with a pump-based extravascular system, we demonstrate the ability to rapidly reduce glucose levels in diabetic rodent models, replicating the timescale and therapeutic effect of subcutaneous insulin injection or infusion. This advance provides a potential path toward achieving insulin independence with islet macroencapsulation.

Diabetic peripheral neuropathy (DPN) is a common diabetes complication with no currently available curative treatments. Here, we demonstrated that the protein level of G-protein-coupled receptor 40 (GPR40) is significantly repressed in the sciatic nerves (SNs) of DPN patients, as well as in the peripheral nerves, including dorsal root ganglia (DRG) and SNs, of streptozotocin-induced type 1 diabetic mice and BKS Cg-m+/+Lepr db/J (db/db) type 2 diabetic mice. We identified that amlodipine besylate (AB), a first-line clinical antihypertensive drug, is a GPR40 agonist capable of alleviating DPN-like pathologies in mice. These pathologies include neurological damage, destruction of myelin sheath structures, vascular injury, loss of intraepidermal nerve fibers, and impaired neurite outgrowth in DRG neurons. To elucidate the underlying mechanisms, we generated the DPN mice with GPR40-specific knockdown in SN and DRG tissues using adeno-associated virus 8-GPR40-RNAi. Mechanistically, AB attenuated inflammatory responses via the GPR40/β-arrestin2/NLRP3 pathway and ameliorated mitochondrial dysfunction through the GPR40/LKB1/AMPK/SIRT1/PGC-1α pathway in DPN mice, which were all further validated in primary human Schwann cells. Additionally, AB suppressed the cross talk between Schwann cells and endothelial cells/DRG neurons in DPN mice. Collectively, our findings highlight the potential of AB for the treatment of DPN.

Revascularization strategies failed to improve outcome in patients with diabetes with peripheral artery disease (PAD). Histone modifications are key modulators of gene expression and could play a role in angiogenic response. This study investigates the role of chromatin remodelling in modulating angiogenesis in diabetes. RNA sequencing (RNA-seq), and angiogenic assays (cell migration and tube formation) were performed in human aortic endothelial cells (HAECs) exposed to normal glucose (NG, 5 mmol/L) or high glucose (HG, 25 mmol/L) for 48 h. The expression of the histone methyltransferase SETD7 and its chromatin signature at histone 3 on lysine 4 (H3K4me1) were investigated by Western blot and chromatin immunoprecipitation (ChIP). Diabetic mice were treated with the SETD7 inhibitor (R)-PFI-2 or vehicle and underwent hind limb ischemia by femoral artery ligation. The experimental findings were translated into two cohorts of patients with diabetes with PAD. RNA-seq in HG-treated HAECs unveiled SETD7 as the top-ranking transcript. SETD7 upregulation was associated with increased H3K4me1 levels and defective angiogenesis. Both SETD7 depletion and (R)-PFI-2 rescued hyperglycemia-induced impairment of HAECs migration and tube formation, while SETD7 overexpression blunted the angiogenic response. RNA-seq and ChIP assays showed that SETD7-induced H3K4me1 enables the transcription of the angiogenesis inhibitor semaphorin-3G (SEMA3G) by increasing chromatin accessibility to peroxisome proliferator-activated receptor-γ. In diabetic mice with hind limb ischemia, (R)-PFI-2 improved limb perfusion by suppressing SEMA3G. The SETD7/SEMA3G axis was upregulated in patients with diabetes with PAD. Of note, (R)-PFI-2 restored angiogenic properties in endothelial cells collected from patients with diabetes. These findings show that SETD7 is a druggable epigenetic target in diabetic PAD.

The association between KCNJ5 mutations and the risk of developing new-onset diabetes (NOD) in patients with unilateral primary aldosteronism (uPA) remains underexplored. To investigate this association, we conducted a longitudinal study using data from the Taiwan Primary Aldosteronism Investigation database. Our sample included 360 patients with uPA who underwent adrenalectomy between 2012 and 2017, 191 (53.1%) of whom had KCNJ5 mutations in their adrenal adenomas. We found that patients with uPA harboring KCNJ5 mutations had a higher rate of complete clinical success (69.5% vs. 43.8%; P < 0.01) and complete biochemical success (93.8% vs. 86.6%; P = 0.04) compared with those without KCNJ5 mutations at 6 months to 1 year after adrenalectomy. Over an average follow-up period of 8.5 years, multivariate Cox regression analysis revealed that patients with uPA with KCNJ5 mutations had a significantly lower risk of developing NOD (hazard ratio [HR] 0.41; 95% CI 0.17-0.996; P = 0.049). Additionally, we identified higher BMI (HR 1.23; 95% CI 1.11-1.37; P < 0.01) and lower estimated glomerular filtration rate (eGFR; HR 0.98; 95% CI 0.97-0.99; P = 0.01) as potential predictors of NOD based on baseline characteristics. The association between patients with uPA without KCNJ5 mutations and higher incidence of NOD was less pronounced in subgroups characterized by younger age, higher BMI, higher eGFR, and lower potassium levels. In conclusion, patients with uPA without KCNJ5 mutations had a higher incidence of NOD, with 13.6% affected during long-term follow-up. Our findings suggest that patients with uPA without KCNJ5 mutations may require more frequent follow-up for NOD after adrenalectomy.