α-L-iduronidase fused with humanized anti-human transferrin receptor antibody (lepunafusp alfa) for mucopolysaccharidosis type I: A phase 1/2 trial.

Mucopolysaccharidosis type I (MPS I) causes systemic accumulation of glycosaminoglycans due to a genetic deficiency of α-L-iduronidase (IDUA), which results in progressive systemic symptoms affecting multiple organs, including the central nervous system (CNS). Because the blood-brain barrier (BBB) prevents enzymes from reaching the brain, enzyme replacement therapy is effective only against the somatic symptoms. Hematopoietic stem cell transplantation can address the CNS symptoms, but the risk of complications limits its applicability. We have developed a novel genetically modified protein consisting of IDUA fused with humanized anti-human transferrin receptor antibody (lepunafusp alfa; JR-171), which has been shown in nonclinical studies to be distributed to major organs, including the brain, bringing about systemic reductions in heparan sulfate (HS) and dermatan sulfate concentrations. Subsequently, a first-in-human study was conducted to evaluate the safety, pharmacokinetics, and exploratory efficacy of JR-171 in 18 patients with MPS I. No notable safety issues were observed. Plasma drug concentration increased dose dependently and reached its maximum approximately 4 h after the end of drug administration. Decreased HS in the cerebrospinal fluid suggested successful delivery of JR-171 across the BBB, while suppressed urine and serum concentrations of the substrates indicated that its somatic efficacy was comparable to that of laronidase.

Transferrin Receptor-Targeted Iduronate-2-sulfatase Penetrates the Blood-Retinal Barrier and Improves Retinopathy in Mucopolysaccharidosis II Mice.

Mucopolysaccharidoses (MPSs) make up a group of lysosomal storage diseases characterized by the aberrant accumulation of glycosaminoglycans throughout the body. Patients with MPSs display various signs and symptoms, such as retinopathy, which is also observed in patients with MPS II. Unfortunately, retinal disorders in MPS II are resistant to conventional intravenous enzyme-replacement therapy because the blood-retinal barrier (BRB) impedes drug penetration. In this study, we show that a fusion protein, designated pabinafusp alfa, consisting of an antihuman transferrin receptor antibody and iduronate-2-sulfatase (IDS), crosses the BRB and reaches the retina in a murine model of MPS II. We found that retinal function, as assessed by electroretinography (ERG) in MPS II mice, deteriorated with age. Early intervention with repeated intravenous treatment of pabinafusp alfa decreased heparan sulfate deposition in the retina, optic nerve, and visual cortex, thus preserving or even improving the ERG response in MPS II mice. Histological analysis further revealed that pabinafusp alfa mitigated the loss of the photoreceptor layer observed in diseased mice. In contrast, recombinant nonfused IDS failed to reach the retina and hardly affected the retinal disease. These results support the hypothesis that transferrin receptor-targeted IDS can penetrate the BRB, thereby ameliorating retinal dysfunction in MPS II.

Enzyme replacement with transferrin receptor-targeted α-L-iduronidase rescues brain pathology in mucopolysaccharidosis I mice.

Mucopolysaccharidosis I (MPS I), a lysosomal storage disease caused by dysfunction of α-L-iduronidase (IDUA), is characterized by the deposition of dermatan sulfate (DS) and heparan sulfate (HS) throughout the body, which causes several somatic and central nervous symptoms. Although enzyme-replacement therapy (ERT) is currently available to treat MPS I, it does not alleviate central nervous disorders, as it cannot penetrate the blood-brain barrier. Here we evaluate the brain delivery, efficacy, and safety of JR-171, a fusion protein comprising humanized anti-human transferrin receptor antibody Fab and IDUA, using monkeys and MPS I mice. Intravenously administered JR-171 was distributed in major organs, including the brain, and reduced DS and HS concentrations in the central nervous system and peripheral tissues. JR-171 exerted similar effects on peripheral disorders similar to conventional ERT and further reversed brain pathology in MPS I mice. We found that JR-171 improved spatial learning ability, which was seen to deteriorate in the vehicle-treated mice. Further, no safety concerns were noted in repeat-dose toxicity studies in monkeys. This study provides nonclinical evidence that JR-171 might potentially prevent and even improve disease conditions in patients with neuronopathic MPS I without serious safety concerns.

Pathogenic Roles of Heparan Sulfate and Its Use as a Biomarker in Mucopolysaccharidoses.

Heparan sulfate (HS) is an essential glycosaminoglycan (GAG) as a component of proteoglycans, which are present on the cell surface and in the extracellular matrix. HS-containing proteoglycans not only function as structural constituents of the basal lamina but also play versatile roles in various physiological processes, including cell signaling and organ development. Thus, inherited mutations of genes associated with the biosynthesis or degradation of HS can cause various diseases, particularly those involving the bones and central nervous system (CNS). Mucopolysaccharidoses (MPSs) are a group of lysosomal storage disorders involving GAG accumulation throughout the body caused by a deficiency of GAG-degrading enzymes. GAGs are stored differently in different types of MPSs. Particularly, HS deposition is observed in patients with MPS types I, II, III, and VII, all which involve progressive neuropathy with multiple CNS system symptoms. While therapies are available for certain symptoms in some types of MPSs, significant unmet medical needs remain, such as neurocognitive impairment. This review presents recent knowledge on the pathophysiological roles of HS focusing on the pathogenesis of MPSs. We also discuss the possible use and significance of HS as a biomarker for disease severity and therapeutic response in MPSs.

Pharmacokinetics and pharmacodynamics of once-weekly administration of JR-142, a long-acting albumin-fused human growth hormone: A rondemized, placebo-controlled phase 1 study.

OBJECTIVE: Under clinical development for patients with growth hormone deficiency, JR-142 is a long-acting growth hormone with a half-life extended by fusion with modified serum albumin. We conducted a Phase 1 study to investigate the safety, tolerability, and pharmacokinetic (PK) and pharmacodynamic (PD) profiles of once-weekly subcutaneous administrations of JR-142. The study consisted of two parts: an open-label single ascending dosing study (Part 1), and a randomized, placebo-controlled, assessor-blinded multiple ascending dosing study (Part 2). DESIGN: A total of 31 healthy Japanese male participants were enrolled. In Part 1, seven of them received a single subcutaneous injection of JR-142 each at dosages of 0.15 mg/kg (n = 1), 0.25 mg/kg (n = 2), 0.5 mg/kg (n = 2), or 1.0 mg/kg (n = 2). In Part 2, one weekly subcutaneous injection of JR-142 at 0.25 mg/kg, 0.5 mg/kg, 1.0 mg/kg or a placebo were given for four weeks to each of the other 24 participants (six in each group). Plasma JR-142 and serum insulin-like growth factor-1 (IGF-1) concentrations were measured for PK and PD assessments. Safety was evaluated on the basis of adverse events (AEs), laboratory tests, and other measures. RESULTS: JR-142 induced dose-dependent increases in the maximum plasma JR-142 concentration (Cmax) and the area under the plasma concentration-time curve from time 0 to τ (AUC0-τ). A similar dose-response relationship was observed in serum IGF-1 concentrations. All trough IGF-1 levels were well sustained one week after the final administrations of JR-142 at the three dosages, while the peak concentrations of IGF-1 remained mildly elevated. No serious AEs were observed, and laboratory tests, including assessment of anti-drug antibodies, uncovered no significant safety issues. CONCLUSIONS: Once-weekly subcutaneous injections of JR-142 produced positive dose-dependent PK and PD profiles over the dosage range. Drug accumulation was observed after the four-week administration period but did not raise safety concerns, indicating that JR-142 is well-tolerated in healthy participants. The PD profiles observed in terms of IGF-1 concentrations were also positive, and we believe the encouraging results of this study warrant substantiation in further clinical trials in patients with GHD. ETHICS: This clinical study was conducted at one investigational site in Osaka, Japan, where the clinical study and the non-clinical data of JR-142 were reviewed and approved by its Institutional Review Board on 9th May 2019. The study was conducted in compliance with the approved study protocol, the Declaration of Helsinki, 1964, as revised in 2013, and Good Clinical Practice.

Dose-dependent effects of a brain-penetrating iduronate-2-sulfatase on neurobehavioral impairments in mucopolysaccharidosis II mice.

Deposition of heparan sulfate (HS) in the brain of patients with mucopolysaccharidosis II (MPS II) is believed to be the leading cause of neurodegeneration, resulting in several neurological signs and symptoms, including neurocognitive impairment. We recently showed that pabinafusp alfa, a blood-brain-barrier-penetrating fusion protein consisting of iduronate-2-sulfatase and anti-human transferrin receptor antibody, stabilized learning ability by preventing the deposition of HS in the CNS of MPS II mice. We further examined the dose-dependent effect of pabinafusp alfa on neurological function in relation to its HS-reducing efficacy in a mouse model of MPS II. Long-term intravenous treatment with low (0.1 mg/kg), middle (0.5 mg/kg), and high (2.0 mg/kg) doses of the drug dose-dependently decreased HS concentration in the brain and cerebrospinal fluid (CSF). A comparable dose-dependent effect in the prevention of neuronal damage in the CNS, and dose-dependent improvements in neurobehavioral performance tests, such as gait analysis, pole test, Y maze, and Morris water maze, were also observed. Notably, the water maze test performance was inversely correlated with the HS levels in the brain and CSF. This study provides nonclinical evidence substantiating a quantitative dose-dependent relationship between HS reduction in the CNS and neurological improvements in MPS II.

Treatment of Neuronopathic Mucopolysaccharidoses with Blood-Brain Barrier-Crossing Enzymes: Clinical Application of Receptor-Mediated Transcytosis.

Enzyme replacement therapy (ERT) has paved the way for treating the somatic symptoms of lysosomal storage diseases (LSDs), but the inability of intravenously administered enzymes to cross the blood-brain barrier (BBB) has left the central nervous system (CNS)-related symptoms of LSDs largely impervious to the therapeutic benefits of ERT, although ERT via intrathecal and intracerebroventricular routes can be used for some neuronopathic LSDs (in particular, mucopolysaccharidoses). However, the considerable practical issues involved make these routes unsuitable for long-term treatment. Efforts have been made to modify enzymes (e.g., by fusing them with antibodies against innate receptors on the cerebrovascular endothelium) so that they can cross the BBB via receptor-mediated transcytosis (RMT) and address neuronopathy in the CNS. This review summarizes the various scientific and technological challenges of applying RMT to the development of safe and effective enzyme therapeutics for neuronopathic mucopolysaccharidoses; it then discusses the translational and methodological issues surrounding preclinical and clinical evaluation to establish RMT-applied ERT.

Drug delivery for neuronopathic lysosomal storage diseases: evolving roles of the blood brain barrier and cerebrospinal fluid.

Whereas significant strides have been made in the treatment of lysosomal storage diseases (LSDs), the neuronopathy associated with these diseases remains impervious mainly because of the blood-brain barrier (BBB), which prevents delivery of large molecules to the brain. However, 100 years of research on the BBB since its conceptualization have clarified many of its functional and structural characteristics, spurring recent endeavors to deliver therapeutics across it to treat central nervous system (CNS) disorders, including neuronopathic LSDs. Along with the BBB, the cerebrospinal fluid (CSF) also functions to protect the microenvironment of the CNS, and it is therefore deeply involved in CNS disorders at large. Recent research aimed at developing therapeutics for neuronopathic LSDs has uncovered a number of critical roles played by the CSF that require further clarification. This review summarizes the most up-to-date understanding of the BBB and the CSF acquired during the development of therapeutics for neuronopathic LSDs, and highlights some of the associated challenges that require further research.

Enzyme Replacement Therapy with Pabinafusp Alfa for Neuronopathic Mucopolysaccharidosis II: An Integrated Analysis of Preclinical and Clinical Data.

Enzyme replacement therapy (ERT) improves somatic manifestations in mucopolysaccharidoses (MPS). However, because intravenously administered enzymes cannot cross the blood-brain barrier (BBB), ERT is ineffective against the progressive neurodegeneration and resultant severe central nervous system (CNS) symptoms observed in patients with neuronopathic MPS. Attempts to surmount this problem have been made with intrathecal and intracerebroventricular ERT in order to achieve CNS effects, but the burdens on patients are inimical to long-term administrations. However, since pabinafusp alfa, a human iduronate-2-sulfatase fused with a BBB-crossing anti-transferrin receptor antibody, showed both central and peripheral efficacy in a mouse model, subsequent clinical trials in a total of 62 patients with MPS-II (Hunter syndrome) in Japan and Brazil substantiated this dual efficacy and provided an acceptable safety profile. To date, pabinafusp alfa is the only approved intravenous ERT that is effective against both the somatic and CNS symptoms of patients with MPS-II. This article summarizes the previously obtained preclinical and clinical evidence related to the use of this drug, presents latest data, and discusses the preclinical, translational, and clinical challenges of evaluating, ameliorating, and preventing neurodegeneration in patients with MPS-II.

Nonclinical safety evaluation of pabinafusp alfa, an anti-human transferrin receptor antibody and iduronate-2-sulfatase fusion protein, for the treatment of neuronopathic mucopolysaccharidosis type II.

Pabinafusp alfa is a fusion protein comprising a humanized anti-human transferrin receptor (TfR) antibody and human iduronate-2-sulfatase. It was developed as a novel modality to target central nervous system-related symptoms observed in patients with mucopolysaccharidosis type II (MPS II, also known as Hunter syndrome). As the fusion protein contains an entire IgG1 molecule that binds TfR, there may be specific safety concerns, such as unexpected cellular toxicity due to its effector functions or its ability to inhibit iron metabolism, in addition to general safety concerns. Here, we present the comprehensive results of a nonclinical safety assessment of pabinafusp alfa. Pabinafusp alfa did not exhibit effector functions, as assessed by antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity studies in TfR-expressing hematopoietic cells. Repeat-dose toxicity studies in cynomolgus monkeys showed that pabinafusp alfa did not induce any significant toxicological changes at doses up to 30 mg/kg/week upon intravenous administration for up to 26 weeks. Interaction of transferrin with TfR was not inhibited by pabinafusp alfa, suggesting that the effect of pabinafusp alfa on the physiological iron transport system is minimal, which was confirmed by toxicity studies in cynomolgus monkeys. These findings suggest that pabinafusp alfa is expected to be safe for long-term use in individuals with MPS II.

Clearance of heparan sulfate in the brain prevents neurodegeneration and neurocognitive impairment in MPS II mice.

Mucopolysaccharidosis II (MPS II), a lysosomal storage disease caused by mutations in iduronate-2-sulfatase (IDS), is characterized by a wide variety of somatic and neurologic symptoms. The currently approved intravenous enzyme replacement therapy with recombinant IDS (idursulfase) is ineffective for CNS manifestations due to its inability to cross the blood-brain barrier (BBB). Here, we demonstrate that the clearance of heparan sulfate (HS) deposited in the brain by a BBB-penetrable antibody-enzyme fusion protein prevents neurodegeneration and neurocognitive dysfunctions in MPS II mice. The fusion protein pabinafusp alfa was chronically administered intravenously to MPS II mice. The drug reduced HS and attenuated histopathological changes in the brain, as well as in peripheral tissues. The loss of spatial learning abilities was completely suppressed by pabinafusp alfa, but not by idursulfase, indicating an association between HS deposition in the brain, neurodegeneration, and CNS manifestations in these mice. Furthermore, HS concentrations in the brain and reduction thereof by pabinafusp alpha correlated with those in the cerebrospinal fluid (CSF). Thus, repeated intravenous administration of pabinafusp alfa to MPS II mice decreased HS deposition in the brain, leading to prevention of neurodegeneration and maintenance of neurocognitive function, which may be predicted from HS concentrations in CSF.

Gs/Gq signaling switch in ß cells defines incretin effectiveness in diabetes.

By restoring glucose-regulated insulin secretion, glucagon-like peptide-1-based (GLP-1-based) therapies are becoming increasingly important in diabetes care. Normally, the incretins GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) jointly maintain normal blood glucose levels by stimulation of insulin secretion in pancreatic ß cells. However, the reason why only GLP-1-based drugs are effective in improving insulin secretion after presentation of diabetes has not been resolved. ATP-sensitive K+ (KATP) channels play a crucial role in coupling the systemic metabolic status to ß cell electrical activity for insulin secretion. Here, we have shown that persistent membrane depolarization of ß cells due to genetic (ß cell-specific Kcnj11-/- mice) or pharmacological (long-term exposure to sulfonylureas) inhibition of the KATP channel led to a switch from Gs to Gq in a major amplifying pathway of insulin secretion. The switch determined the relative insulinotropic effectiveness of GLP-1 and GIP, as GLP-1 can activate both Gq and Gs, while GIP only activates Gs. The findings were corroborated in other models of persistent depolarization: a spontaneous diabetic KK-Ay mouse and nondiabetic human and mouse ß cells of pancreatic islets chronically treated with high glucose. Thus, a Gs/Gq signaling switch in ß cells exposed to chronic hyperglycemia underlies the differential insulinotropic potential of incretins in diabetes.

Physicochemical and biological evaluation of JR-131 as a biosimilar to a long-acting erythropoiesis-stimulating agent darbepoetin alfa.

Renal anemia is predominantly caused by a relative deficiency in erythropoietin (EPO). Conventional treatment for renal anemia includes the use of recombinant human EPO (rhEPO) or a long-acting erythropoiesis-activating agent named darbepoetin alfa, which is a modified rhEPO with a carbohydrate chain structure that differs from native hEPO. We have developed a biosimilar to darbepoetin alfa designated JR-131. Here, we comprehensively compare the physicochemical and biological characteristics of JR-131 to darbepoetin alfa. JR-131 demonstrated similar protein structure to the originator, darbepoetin alfa, by peptide mapping and circular dichroism spectroscopy. Additionally, mass spectroscopic analyses and capillary zone electrophoresis revealed similar glycosylation patterns between the two products. Human bone marrow-derived erythroblasts differentiated and proliferated to form colonies with JR-131 to a similar degree as darbepoetin alfa. Finally, JR-131 stimulated erythropoiesis and improved anemia in rats similarly to darbepoetin alfa. Our data show the similarity in physicochemical and biological properties of JR-131 to those of darbepoetin alfa, and JR-131 therefore represents a biosimilar for use in the treatment of renal anemia.

Iduronate-2-Sulfatase with Anti-human Transferrin Receptor Antibody for Neuropathic Mucopolysaccharidosis II: A Phase 1/2 Trial.

Hunter syndrome (mucopolysaccharidosis II [MPS II]), a deficiency of iduronate-2-sulfatase (IDS), causes an accumulation of glycosaminoglycans, giving rise to multiple systemic and CNS symptoms. The currently available therapies, idursulfase and idursulfase beta, are ineffective against the CNS symptoms because they cannot pass the blood-brain barrier (BBB). A novel IDS fused with anti-human transferrin receptor antibody (JR-141) has been shown to penetrate the BBB and ameliorate learning deficits in model mice. This first-in-human study evaluated the pharmacokinetics, safety, and potential efficacy of JR-141 in 14 patients with MPS II. In a dose-escalation study performed in two patients, JR-141 plasma concentrations were dose dependent and peaked at 3 hr after initiation of each infusion, and no or only mild adverse reactions were exhibited. In a subsequent 4-week evaluation at two dose levels, the plasma concentration profiles were similar between the first and final administration, indicating no drug accumulation. Levels of heparan sulfate (HS) and dermatan sulfate (DS) were suppressed in both plasma and urine and HS levels were significantly decreased in cerebrospinal fluid. Two patients experienced some amelioration of neurocognitive and motor symptoms. These results suggest that the drug successfully penetrates the BBB and could have CNS efficacy.

Non-clinical evaluation of JR-051 as a biosimilar to agalsidase beta for the treatment of Fabry disease.

Fabry disease (FD) is an X-linked lysosomal storage disease. It is caused by deficiency of the enzyme α-galactosidase A (α-Gal A), which leads to excessive deposition of neutral glycosphingolipids, especially globotriaosylceramide (GL-3), in cells throughout the body. Progressive accumulation of GL-3 causes life-threatening complications in several tissues and organs, including the vasculature, heart, and kidney. Currently available enzyme replacement therapy for FD employs recombinant α-Gal A in two formulations, namely agalsidase alfa and agalsidase beta. Here, we evaluated JR-051 as a biosimilar to agalsidase beta in a non-clinical study. JR-051 was shown to have identical primary and similar higher-order structures to agalsidase beta. Mannose-6-phosphate content was higher in JR-051 than in agalsidase beta, which probably accounts for a slightly better uptake into fibroblasts in vitro. In spite of these differences in in vitro biological features, pharmacokinetic profiles of the two compounds in mice, rats, and monkeys were similar. The ability to reduce GL-3 accumulation in the kidney, heart, skin, liver, spleen, and plasma of Gla-knockout mice, a model of FD, was not different between JR-051 and agalsidase beta. Furthermore, we identified no safety concerns regarding JR-051 in a 13-week evaluation using cynomolgus monkeys. These findings indicate that JR-051 is similar to agalsidase beta in terms of physicochemical and biological properties.

Inhibition of SNAT5 Induces Incretin-Responsive State From Incretin-Unresponsive State in Pancreatic ß-Cells: Study of ß-Cell Spheroid Clusters as a Model.

ß-Cell-ß-cell interactions are required for normal regulation of insulin secretion. We previously found that formation of spheroid clusters (called K20-SC) from MIN6-K20 clonal ß-cells lacking incretin-induced insulin secretion (IIIS) under monolayer culture (called K20-MC) drastically induced incretin responsiveness. Here we investigated the mechanism by which an incretin-unresponsive state transforms to an incretin-responsive state using K20-SC as a model. Glutamate production by glucose through the malate-aspartate shuttle and cAMP signaling, both of which are critical for IIIS, were enhanced in K20-SC. SC formed from ß-cells deficient for aspartate aminotransferase 1, a critical enzyme in the malate-aspartate shuttle, exhibited reduced IIIS. Expression of the sodium-coupled neutral amino acid transporter 5 (SNAT5), which is involved in glutamine transport, was downregulated in K20-SC and pancreatic islets of normal mice but was upregulated in K20-MC and islets of rodent models of obesity and diabetes, both of which exhibit impaired IIIS. Inhibition of SNAT5 significantly increased cellular glutamate content and improved IIIS in islets of these models and in K20-MC. These results suggest that suppression of SNAT5 activity, which results in increased glutamate production, and enhancement of cAMP signaling endows incretin-unresponsive ß-cells with incretin responsiveness.

A Blood-Brain-Barrier-Penetrating Anti-human Transferrin Receptor Antibody Fusion Protein for Neuronopathic Mucopolysaccharidosis II.

Mucopolysaccharidosis II (MPS II) is an X-linked recessive lysosomal storage disease caused by mutations in the iduronate-2-sulfatase (IDS) gene. Since IDS catalyzes the degradation of glycosaminoglycans (GAGs), deficiency in this enzyme leads to accumulation of GAGs in most cells in all tissues and organs, resulting in severe somatic and neurological disorders. Although enzyme replacement therapy with human IDS (hIDS) has been used for the treatment of MPS II, this therapy is not effective for defects in the CNS mainly because the enzyme cannot cross the blood-brain barrier (BBB). Here, we developed a BBB-penetrating fusion protein, JR-141, which consists of an anti-human transferrin receptor (hTfR) antibody and intact hIDS. The TfR-mediated incorporation of JR-141 was confirmed by using human fibroblasts in vitro. When administrated intravenously to hTfR knockin mice or monkeys, JR-141, but not naked hIDS, was detected in the brain. In addition, the intravenous administration of JR-141 reduced the accumulation of GAGs both in the peripheral tissues and in the brain of hTfR knockin mice lacking Ids, an animal model of MPS II. These data provide a proof of concept for the translation of JR-141 to clinical study for the treatment of patients with MPS II with CNS disorders.

Essential roles of aspartate aminotransferase 1 and vesicular glutamate transporters in ß-cell glutamate signaling for incretin-induced insulin secretion.

Incretins (GLP-1 and GIP) potentiate insulin secretion through cAMP signaling in pancreatic ß-cells in a glucose-dependent manner. We recently proposed a mechanistic model of incretin-induced insulin secretion (IIIS) that requires two critical processes: 1) generation of cytosolic glutamate through the malate-aspartate (MA) shuttle in glucose metabolism and 2) glutamate transport into insulin granules by cAMP signaling to promote insulin granule exocytosis. To directly prove the model, we have established and characterized CRISPR/Cas9-engineered clonal mouse ß-cell lines deficient for the genes critical in these two processes: aspartate aminotransferase 1 (AST1, gene symbol Got1), a key enzyme in the MA shuttle, which generates cytosolic glutamate, and the vesicular glutamate transporters (VGLUT1, VGLUT2, and VGLUT3, gene symbol Slc17a7, Slc17a6, and Slc17a8, respectively), which participate in glutamate transport into secretory vesicles. Got1 knockout (KO) ß-cell lines were defective in cytosolic glutamate production from glucose and showed impaired IIIS. Unexpectedly, different from the previous finding that global Slc17a7 KO mice exhibited impaired IIIS from pancreatic islets, ß-cell specific Slc17a7 KO mice showed no significant impairment in IIIS, as assessed by pancreas perfusion experiment. Single Slc17a7 KO ß-cell lines also retained IIIS, probably due to compensatory upregulation of Slc17a6. Interestingly, triple KO of Slc17a7, Slc17a6, and Slc17a8 diminished IIIS, which was rescued by exogenously introduced wild-type Slc17a7 or Slc17a6 genes. The present study provides direct evidence for the essential roles of AST1 and VGLUTs in ß-cell glutamate signaling for IIIS and also shows the usefulness of the CRISPR/Cas9 system for studying ß-cells by simultaneous disruption of multiple genes.

A Novel Diphenylthiosemicarbazide Is a Potential Insulin Secretagogue for Anti-Diabetic Agen.

Insulin secretagogues are used for treatment of type 2 diabetes. We attempted to discover novel small molecules to stimulate insulin secretion by using in silico similarity search using sulfonylureas as query, followed by measurement of insulin secretion. Among 38 compounds selected by in silico similarity search, we found three diphenylsemicarbazides and one quinolone that stimulate insulin secretion. We focused on compound 8 (C8), which had the strongest insulin-secreting effect. Based on the structure-activity relationship of C8-derivatives, we identified diphenylthiosemicarbazide (DSC) 108 as the most potent secretagogue. DSC108 increased the intracellular Ca2+ level in MIN6-K8 cells. Competitive inhibition experiment and electrophysiological analysis revealed sulfonylurea receptor 1 (SUR1) to be the target of DSC108 and that this diphenylthiosemicarbazide directly inhibits ATP-sensitive K+ (KATP) channels. Pharmacokinetic analysis showed that DSC108 has a short half-life in vivo. Oral administration of DSC108 significantly suppressed the rises in blood glucose levels after glucose load in wild-type mice and improved glucose tolerance in the Goto-Kakizaki (GK) rat, a model of type 2 diabetes with impaired insulin secretion. Our data indicate that DSC108 is a novel insulin secretagogue, and is a lead compound for development of a new anti-diabetic agent.

Meal sequence and glucose excursion, gastric emptying and incretin secretion in type 2 diabetes: a randomised, controlled crossover, exploratory trial.

AIMS/HYPOTHESIS: Investigation of dietary therapy for diabetes has focused on meal size and composition; examination of the effects of meal sequence on postprandial glucose management is limited. The effects of fish or meat before rice on postprandial glucose excursion, gastric emptying and incretin secretions were investigated. METHODS: The experiment was a single centre, randomised controlled crossover, exploratory trial conducted in an outpatient ward of a private hospital in Osaka, Japan. Patients with type 2 diabetes (n = 12) and healthy volunteers (n = 10), with age 30-75 years, HbA1c 9.0% (75 mmol/mol) or less, and BMI 35 kg/m(2) or less, were randomised evenly to two groups by use of stratified randomisation, and subjected to meal sequence tests on three separate mornings; days 1 and 2, rice before fish (RF) or fish before rice (FR) in a crossover fashion; and day 3, meat before rice (MR). Pre- and postprandial levels of glucose, insulin, C-peptide and glucagon as well as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide were evaluated. Gastric emptying rate was determined by (13)C-acetate breath test involving measurement of (13)CO2 in breath samples collected before and after ingestion of rice steamed with (13)C-labelled sodium acetate. Participants, people doing measurements or examinations, and people assessing the outcomes were not blinded to group assignment. RESULTS: FR and MR in comparison with RF ameliorated postprandial glucose excursion (AUC-15-240 min-glucose: type 2 diabetes, FR 2,326.6 ± 114.7 mmol/l × min, MR 2,257.0 ± 82.3 mmol/l × min, RF 2,475.6 ± 87.2 mmol/l × min [p < 0.05 for FR vs RF and MR vs RF]; healthy, FR 1,419.8 ± 72.3 mmol/l × min, MR 1,389.7 ± 69.4 mmol/l × min, RF 1,483.9 ± 72.8 mmol/l × min) and glucose variability (SD-15-240 min-glucose: type 2 diabetes, FR 1.94 ± 0.22 mmol/l, MR 1.68 ± 0.18 mmol/l, RF 2.77 ± 0.24 mmol/l [p < 0.05 for FR vs RF and MR vs RF]; healthy, FR 0.95 ± 0.21 mmol/l, MR 0.83 ± 0.16 mmol/l, RF 1.18 ± 0.27 mmol/l). FR and MR also enhanced GLP-1 secretion, MR more strongly than FR or RF (AUC-15-240 min-GLP-1: type 2 diabetes, FR 7,123.4 ± 376.3 pmol/l × min, MR 7,743.6 ± 801.4 pmol/l × min, RF 6,189.9 ± 581.3 pmol/l × min [p < 0.05 for FR vs RF and MR vs RF]; healthy, FR 3,977.3 ± 324.6 pmol/l × min, MR 4,897.7 ± 330.7 pmol/l × min, RF 3,747.5 ± 572.6 pmol/l × min [p < 0.05 for MR vs RF and MR vs FR]). FR and MR delayed gastric emptying (Time50%: type 2 diabetes, FR 83.2 ± 7.2 min, MR 82.3 ± 6.4 min, RF 29.8 ± 3.9 min [p < 0.05 for FR vs RF and MR vs RF]; healthy, FR 66.3 ± 5.5 min, MR 74.4 ± 7.6 min, RF 32.4 ± 4.5 min [p < 0.05 for FR vs RF and MR vs RF]), which is associated with amelioration of postprandial glucose excursion (AUC-15-120 min-glucose: type 2 diabetes, r = -0.746, p < 0.05; healthy, r = -0.433, p < 0.05) and glucose variability (SD-15-240 min-glucose: type 2 diabetes, r = -0.578, p < 0.05; healthy, r = -0.526, p < 0.05), as well as with increasing GLP-1 (AUC-15-120 min-GLP-1: type 2 diabetes, r = 0.437, p < 0.05; healthy, r = 0.300, p = 0.107) and glucagon (AUC-15-120 min-glucagon: type 2 diabetes, r = 0.399, p < 0.05; healthy, r = 0.471, p < 0.05). The measured outcomes were comparable between the two randomised groups. CONCLUSIONS/INTERPRETATION: Meal sequence can play a role in postprandial glucose control through both delayed gastric emptying and enhanced incretin secretion. Our findings provide clues for medical nutrition therapy to better prevent and manage type 2 diabetes. TRIAL REGISTRATION: UMIN Clinical Trials Registry UMIN000017434. FUNDING: Japan Society for Promotion of Science, Japan Association for Diabetes Education and Care, and Japan Vascular Disease Research Foundation.