Shin-ichi Harashima

Outside-to-inside signal through the membrane TNF-alpha induces E-selectin (CD62E) expression on activated human CD4+ T cells.

The membrane TNF-α is known to serve as a precursor of the soluble form of TNF-α. Although it has been reported the biological functions of the membrane TNF-α as a ligand, the outside-to-inside (reverse) signal transmitted through membrane TNF-α is poorly understood. Here we report a novel function mediated by outside-to-inside signal via membrane TNF-α into the cells expressing membrane TNF-α. Activation by anti-TNF-α Ab against membrane TNF-α on human T cell leukemia virus (HTLV) I-infected T cell line, MT-2, or PHA-activated normal human CD4+ T cells resulted in the induction of an adhesion molecule, E-selectin (CD62E), on the cells with the peak of 12–24 h, which completely disappeared by 48 h. When wild-type or mutant membrane TNF-α (R78T/S79T) resistant to proteolytic cleavage was introduced into Jurkat or HeLa cells, E-selectin was induced by the treatment with anti-TNF-α Ab with the similar kinetics. Membrane TNF-α-expressing Jurkat cells also up-regulated E-selectin when brought into cell-to-cell contact with TNF receptor-expressing HeLa cells. Northern blot analysis and RT-PCR analysis showed that the membrane TNF-α-mediated E-selectin expression was up-regulated at the level of transcription. These results not only confirmed our previous findings of reverse signaling through membrane TNF-α, but also presented evidence that E-selectin was inducible in cell types different from endothelial cells. It is strongly suggested that membrane TNF-α is a novel proinflammatory cell surface molecule that transmits bipolar signals in local inflammation.

Efficacy and safety of once-weekly semaglutide monotherapy versus placebo in patients with type 2 diabetes (SUSTAIN 1): a double-blind, randomised, placebo-controlled, parallel-group, multinational, multicentre phase 3a trial

BACKGROUND Despite a broad range of pharmacological options for the treatment of type 2 diabetes, optimum glycaemic control remains challenging for many patients and new therapies are necessary. Semaglutide is a glucagon-like peptide-1 (GLP-1) analogue in phase 3 development for type 2 diabetes. We assessed the efficacy, safety, and tolerability of semaglutide monotherapy, compared with placebo, in treatment-naive patients with type 2 diabetes who had insufficient glycaemic control with diet and exercise alone. METHODS We did a double-blind, randomised, parallel-group, international, placebo-controlled phase 3a trial (SUSTAIN 1) at 72 sites in Canada, Italy, Japan, Mexico, Russia, South Africa, UK, and USA (including hospitals, clinical research units, and private offices). Eligible participants were treatment-naive individuals aged 18 years or older with type 2 diabetes treated with only diet and exercise alone for at least 30 days before screening, with a baseline HbA1c of 7·0%-10·0% (53-86 mmol/mol). We randomly assigned participants (2:2:1:1) to either once-weekly subcutaneously injected semaglutide (0·5 mg or 1·0 mg), or volume-matched placebo (0·5 mg or 1·0 mg), for 30 weeks via prefilled PDS290 pen-injectors. Participants did their own injections and were encouraged to administer them on the same day of each week in the same area of their body; the time of day and proximity of meal times was not specified. We did the randomisation with an interactive voice or web response system. Investigators, participants, and the funder of the study remained masked throughout the trial. The primary endpoint was the change in mean HbA1c from baseline to week 30, and the confirmatory secondary endpoint was the change in mean bodyweight from baseline to week 30. We assessed efficacy and safety in the modified intention-to-treat population (ie, all participants who were exposed to at least one dose of study drug); both placebo groups were pooled for assessment. This trial was registered with ClinicalTrials.gov, number NCT02054897. FINDINGS Between February 3, 2014, and August 21, 2014, we randomly assigned 388 participants to treatment; 387 received at least one dose of study medication (128 0·5 mg semaglutide, 130 1·0 mg semaglutide, 129 placebo). 17 (13%) of those assigned to 0·5 mg semaglutide, 16 (12%) assigned to 1·0 mg semaglutide, and 14 (11%) assigned to placebo discontinued treatment; the main reason for discontinuation was gastrointestinal adverse events such as nausea. Mean baseline HbA1c was 8·05% (SD 0·85); at week 30, HbA1c significantly decreased by 1·45% (95% CI -1·65 to -1·26) with 0·5 mg semaglutide (estimated treatment difference vs placebo -1·43%, 95% CI -1·71 to -1·15; p<0·0001), significantly decreased by 1·55% (-1·74 to -1·36) with 1·0 mg semaglutide (estimated treatment difference vs placebo -1·53%, -1·81 to -1·25; p<0·0001), and non-significantly decreased by 0·02% (-0·23 to 0·18) with placebo. Mean baseline bodyweight was 91·93 kg (SD 23·83); at week 30, bodyweight significantly decreased by 3·73 kg (95% CI -4·54 to -2·91) with 0·5 mg semaglutide (estimated treatment difference vs placebo -2·75 kg, 95% CI -3·92 to -1·58; p<0·0001), significantly decreased by 4·53 kg (-5·34 to -3·72) with 1·0 mg semaglutide (estimated treatment difference vs placebo -3·56 kg, -4·74 to -2·38; p<0·0001), and non-significantly decreased by 0·98 kg (-1·82 to -0·13) with placebo. No deaths were reported in any of the study groups and most reported adverse events were of mild or moderate severity. The most frequently reported adverse events in both semaglutide groups were gastrointestinal in nature: nausea was reported in 26 (20%) who received 0·5 mg semaglutide, 31 (24%) who received 1·0 mg semaglutide, and 10 (8%) who received placebo, and diarrhoea was reported in 16 (13%) who received 0·5 mg semaglutide, 14 (11%) who received 1·0 mg semaglutide, and three (2%) who received placebo. INTERPRETATION Semaglutide significantly improved HbA1c and bodyweight in patients with type 2 diabetes compared with placebo, and showed a similar safety profile to currently available GLP-1 receptor agonists, representing a potential treatment option for such patients. FUNDING Novo Nordisk A/S, Denmark.

Sitagliptin add-on to low dosage sulphonylureas: efficacy and safety of combination therapy on glycaemic control and insulin secretion capacity in type 2 diabetes

Aims: To assess the efficacy and safety of combination therapy with sitagliptin and low dosage sulphonylureas on glycaemic control and insulin secretion capacity in Japanese type 2 diabetes. Methods: Eighty‐two subjects were sequentially recruited for the 52‐week, prospective, single arm study. Sitagliptin was added on to sulphonylureas (glimepride or gliclazide) with or without metformin. The primary endpoint was a change in A1C. The secondary endpoints were changes in BMI, insulin secretion capacity, blood pressure and urinary albumin excretion, unresponsive rate, and hypoglycaemia. Insulin secretion capacity was evaluated by glucagon loading test.

Effects of glucose and meal ingestion on incretin secretion in Japanese subjects with normal glucose tolerance

Aims/Introduction:  Gastric inhibitory polypeptide (GIP) and glucagon‐like peptide‐1 (GLP‐1) are the major incretins; their secretion after various nutrient loads are well‐evaluated in Caucasians. However, little is known of the relationship between incretin secretion and differing nutritional loading in Japanese subjects. In the present study, we evaluated GIP and GLP‐1 secretion in Japanese subjects with normal glucose tolerance (NGT) after glucose loading (75 g glucose and 17 g glucose) and meal ingestion.

Purkinje cell protein 4 positively regulates neurite outgrowth and neurotransmitter release

Purkinje cell protein 4 (PCP4), also called brain‐specific polypeptide 19 (PEP19), is a neurospecific, small calmodulin‐binding protein that binds both calcium‐free and calcium‐binding calmodulin to regulate the calmodulin‐mediated signal. The expression level of this molecule is decreased in the brain in Alzheimers disease, Huntingtons disease, and alcoholism. However, little is known of the function of PCP4 regarding neuronal or neuroendocrine cell differentiation and neurotransmitter release. To address this, we established a PCP4 tetracycline‐inducible rat chromaffin cell line, PC12. When PCP4 expression was induced with doxcycline, neurite outgrowth was significantly advanced in the presence of nerve growth factor (NGF) and dibutyryl cAMP, which was inhibited by W‐7, a calmodulin inhibitor, and PD98059, an ERK inhibitor. In addition, size of the cell body also was increased by treatment with NGF in the PCP4‐induced PC12 cells. Constitutive and potassium‐evoked release of acetylcholine and dopamine was increased and apoptosis induced by hydrogen peroxide (H2O2) was inhibited in PCP4‐induced PC12 cells. On the other hand, knockdown of PCP4 by siRNA transfection decreased neurite outgrowth and dopamine release and increased H2O2‐induced apoptosis in PC12 cells. These results indicate that PCP4 promotes neuroendocrine cell differentiation and neurotransmitter release by activating calmodulin function.

Exendin-4 protects pancreatic beta cells from the cytotoxic effect of rapamycin by inhibiting JNK and p38 phosphorylation.

It has been reported that the immunosuppressant rapamycin decreases the viability of pancreatic beta cells. In contrast, exendin-4, an analogue of glucagon-like peptide-1, has been found to inhibit beta cell death and to increase beta cell mass. We investigated the effects of exendin-4 on the cytotoxic effect of rapamycin in beta cells. Incubation with 10 nM rapamycin induced cell death in 12 h in murine beta cell line MIN6 cells and Wistar rat islets, but not when coincubated with 10 nM exendin-4. Rapamycin was found to increase phosphorylation of c-Jun amino-terminal kinase (JNK) and p38 in 30 minutes in MIN6 cells and Wistar rat islets while exendin-4 decreased their phosphorylation. Akt and extracellular signal-regulated kinase (ERK) were not involved in the cytoprotective effect of exendin-4. These results indicate that exendin-4 may exert its protective effect against rapamycin-induced cell death in pancreatic beta cells by inhibiting JNK and p38 signaling.

Dipeptidyl peptidase-4 inhibitor improved exercise capacity and mitochondrial biogenesis in mice with heart failure via activation of glucagon-like peptide-1 receptor signalling

AIMS Exercise capacity is reduced in heart failure (HF) patients, due mostly to skeletal muscle abnormalities including impaired energy metabolism, mitochondrial dysfunction, fibre type transition, and atrophy. Glucagon-like peptide-1 (GLP-1) has been shown to improve exercise capacity in HF patients. We investigated the effects of the administration of a dipeptidyl peptidase (DPP)-4 inhibitor on the exercise capacity and skeletal muscle abnormalities in an HF mouse model after myocardial infarction (MI). METHODS AND RESULTS MI was created in male C57BL/6J mice by ligating the left coronary artery, and a sham operation was performed in other mice. The mice were then divided into two groups according to the treatment with or without a DPP-4 inhibitor, MK-0626 [1 mg/kg body weight (BW)/day] provided in the diet. Four weeks later, the exercise capacity evaluated by treadmill test was revealed to be limited in the MI mice, and it was ameliorated in the MI + MK-0626 group without affecting the infarct size or cardiac function. The citrate synthase activity, mitochondrial oxidative phosphorylation capacity, supercomplex formation, and their quantity were reduced in the skeletal muscle from the MI mice, and these decreases were normalized in the MI + MK-0626 group, in association with the improvement of mitochondrial biogenesis. Immunohistochemical staining also revealed that a shift toward the fast-twitch fibre type in the MI mice was also reversed by MK-0626. Favourable effects of MK-0626 were significantly inhibited by treatment of GLP-1 antagonist, Exendin-(9-39) (150 pmol/kg BW/min, subcutaneous osmotic pumps) in MI + MK-0626 mice. Similarly, exercise capacity and mitochondrial function were significantly improved by treatment of GLP-1 agonist, Exendin-4 (1 nmol/kg/BW/h, subcutaneous osmotic pumps). CONCLUSIONS A DPP-4 inhibitor may be a novel therapeutic agent against the exercise intolerance seen in HF patients by improving the mitochondrial biogenesis in their skeletal muscle.

Self‐monitoring of blood glucose (SMBG) improves glycaemic control in oral hypoglycaemic agent (OHA)‐treated type 2 diabetes (SMBG‐OHA study)

We conducted a clinical research study to determine the effect of self‐monitoring of blood glucose (SMBG) on glycaemic control and the value of a putatively less painful blood sampling technique on SMBG in oral hypoglycaemic agent‐treated type 2 diabetes patients; SMBG has not been broadly applied in non‐insulin‐treated patients in Japan.

DEPTOR-related mTOR suppression is involved in metformin's anti-cancer action in human liver cancer cells.

Metformin, one of the most commonly used drugs for patients with type 2 diabetes, recently has received much attention regarding its anti-cancer action. It is thought that the suppression of mTOR signaling is involved in metformins anti-cancer action. Although liver cancer is one of the most responsive types of cancer for reduction of incidence by metformin, the molecular mechanism of the suppression of mTOR in liver remains unknown. In this study, we investigated the mechanism of the suppressing effect of metformin on mTOR signaling and cell proliferation using human liver cancer cells. Metformin suppressed phosphorylation of p70-S6 kinase, and ribosome protein S6, downstream targets of mTOR, and suppressed cell proliferation. We found that DEPTOR, an endogenous substrate of mTOR suppression, is involved in the suppressing effect of metformin on mTOR signaling and cell proliferation in human liver cancer cells. Metformin increases the protein levels of DEPTOR, intensifies binding to mTOR, and exerts a suppressing effect on mTOR signaling. This increasing effect of DEPTOR by metformin is regulated by the proteasome degradation system; the suppressing effect of metformin on mTOR signaling and cell proliferation is in a DEPTOR-dependent manner. Furthermore, metformin exerts a suppressing effect on proteasome activity, DEPTOR-related mTOR signaling, and cell proliferation in an AMPK-dependent manner. We conclude that DEPTOR-related mTOR suppression is involved in metformins anti-cancer action in liver, and could be a novel target for anti-cancer therapy.

Glycemic Variability Is Associated With Quality of Life and Treatment Satisfaction in Patients With Type 1 Diabetes

Patients with type 1 diabetes have greater glycemic variability than that in patients with type 2 diabetes. However, neither glucose variability nor hypoglycemia is detected precisely by HbA1c. This study investigated whether glycemic variability assessed by continuous glucose monitoring influences quality of life (QOL) and treatment satisfaction in patients with type 1 diabetes. The study was conducted in Kyoto University Hospital between September 2011 and June 2012. The study protocol was approved by the institutional review board (UMIN Clinical Trials Registry UMIN000005833). Twenty-eight patients with type 1 diabetes aged ≥18 years were included in analyses (age, 45.9 ± 14.5 [mean ± SD] years; diabetes duration, 15.0 ± 8.2 years; 57% female; 21% using insulin pump; HbA1c, 8.1 ± 1.2% [64.5 ± 13.0 mmol/mol]). Glycemic variability in everyday life was assessed for a 72-h period using the CGMS System Gold continuous glucose …