Pemafibrate, a selective PPARα modulator, and fenofibrate suppress microglial activation through distinct PPARα and SIRT1-dependent pathways.

Pemafibrate, a selective peroxisome proliferator-activated receptor (PPAR) α modulator, is a new drug that specifically modulates PPARα conformation and co-activator recruitment, thereby lowers plasma triglycerides with less off-target effects. Classical PPARα ligands such as fenofibrate suppress inflammatory cells including microglia. However, effects of pemafibrate on microglia have never been addressed. Here we show that pemafibrate, like other PPARα ligands, potently suppressed NF-κB phosphorylation and cytokine expression in microglial cells. PPARα knockdown significantly amplified LPS-induced cytokine expression. Pemafibrate-induced suppression of IL-6 expression was reversed by PPARα knockdown. However, suppression by fenofibrate was not reversed by PPARα knockdown but by Sirtuin 1 (SIRT1) knockdown. In conclusion, pemafibrate and fenofibrate similarly suppresses microglial activation but through distinct PPARα and SIRT1-dependet pathways.

Epidermal growth factor receptor transactivation is necessary for glucagon-like peptide-1 to protect PC12 cells from apoptosis.

AIM: Patients with long-standing diabetes commonly develop diabetic encephalopathy, which is characterized by cognitive impairment and dementia. To identify potential treatments for diabetic encephalopathy, we focused on the protective action of glucagon-like peptide-1 (GLP-1) against neural cell apoptosis. In this study, we evaluated whether exposure of cells to GLP-1 leads to epidermal growth factor receptor (EGFR) transactivation and signaling through the PI3K/Akt/mTOR/GCLc/redox pathway, which we previously reported. METHODS: We monitored the phosphorylation of EGFR and Akt in PC12 cells exposed to MG and GLP-1 that had been first incubated in the presence or absence of various inhibitors of EGFR transactivation. RESULTS: DAPI staining revealed that pretreatment of cells with BiPS, HB-EGF and anti-TGF-α neutralization antibodies or AG1478 abrogated the ability of GLP-1 to rescue cells from MG-induced apoptosis. We show that exposure of PC12 cells to GLP-1 induces EGFR phosphorylation and that this effect was inhibited by prior exposure of the cells to BiPS, HB-EGF and anti-TGF-α neutralization antibodies or AG1478. Interestingly, these agents also diminished the capacity of GLP-1 to protect cells from MG-induced apoptosis. Moreover, these agents reduced GLP-1-induced phosphorylation of Akt. EGF itself also protected the cells from MG-induced apoptosis and induced phosphorylation of Akt, which was inhibited by LY294002. CONCLUSION: The neuroprotective effects of GLP-1 against MG-induced apoptosis are mediated by EGFR transactivation, which signals through the PI3K/Akt/mTOR/GCLc/redox pathway in PC12 cells.

Disturbed gastric motility in patients with long-standing diabetes mellitus.

PURPOSE: Gastric dysmotility has been reported in patients with long-standing diabetes mellitus (DM). Some patients with DM are diagnosed as diabetes gastroparesis and have several upper gastrointestinal (GI) symptoms such as appetite loss and abdominal pain. This study aimed to identify the relationship between gastric motility and upper GI symptoms in patients with long-standing DM. METHOD: This study was conducted among 23 patients with DM and 15 healthy controls. All the patients with DM were receiving insulin treatment and had at least one history of incidence of diabetic nephropathy, retinopathy or neuropathy. Gastric motility was evaluated using electrogastrography (EGG) and gastric emptying using the 13C-acetic acid breath test. The most severe upper gastrointestinal symptoms were assessed in all patients. RESULTS: Compared to healthy controls, patients with long-standing DM showed a significantly lower percentage of normogastria at the postprandial state with a lower power ratio in EGG. Gastric emptying was significantly delayed in patients with DM in the overall analysis. Sixteen patients with DM (69.6%) demonstrated abnormalities in either gastric myoelectrical activity or gastric emptying. Among patients with abnormal EGG or delayed gastric emptying, 12 had some GI symptoms, compared with 3 patients with normal gastric motility. No significant correlation was observed between the gastric emptying parameters and HbA1c values. CONCLUSION: Patients with long-standing DM showed gastric dysmotility, including impaired gastric myoelectrical activity and delayed gastric emptying. Gastric dysmotility appears to be closely correlated with upper GI symptoms in patients with long-standing DM.

Maturity-onset diabetes of the young type 5, presenting as diabetic ketoacidosis with alkalemia: A report of a case.

A 34-year-old man visited our Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, because of dry mouth and weight loss. His plasma glucose level was 32.8 mmol/L and serum levels of ketone bodies were increased, but with metabolic alkalemia. He was also suffering from renal tubular hypomagnesemia and hypokalemia. Abdominal computed tomography showed bilateral renal cysts. These findings were suggestive of maturity-onset diabetes of the young type 5. Genetic testing showed heterozygous hepatocyte nuclear factor 1 beta gene deletion. In the present case, it seemed reasonable to view hepatocyte nuclear factor 1 beta gene deletion as the common cause of maturity-onset diabetes of the young type 5-associated diabetic ketoacidosis and tubular malfunction-induced hypokalemic alkalosis. This case exemplifies the importance of hepatocyte nuclear factor 1 beta gene abnormality as a potential cause of diabetic ketoacidosis with alkalemia.

Streptococcal Toxic Shock Syndrome Induced by Group A Streptococcus with the emm28 Genotype That Developed after a Uterine Cancer Test.

A 69-year-old woman without pre-existing disease visited our hospital due to general malaise, diarrhea, and arthralgia 3 days after a uterine cancer test. We diagnosed her with sepsis of unknown focus and started treatment immediately, but she died 20 hours after the first visit due to multi-organ failure and septic shock. Later, group A streptococcus was detected from the blood culture, and streptococcal toxic shock syndrome (STSS) was diagnosed. The strain had the emm28 genotype and a mutation in csrR with increased NADase activity. These virulence factors were considered to be related to STSS development in this patient.

Effect of Asfotase Alfa on Muscle Weakness in a Japanese Adult Patient of Hypophosphatasia with Low ALP Levels.

A 40-year-old Japanese woman presented to our hospital with general fatigue and muscle weakness. She had a history of premature loss of deciduous teeth at 4 years old, her serum alkaline phosphatase (ALP) activity was as low as 91 U/L, and radiologic studies revealed thoracic deformity and sacroiliac calcification. Genetic sequencing revealed a heterozygous c.1559delT mutation in the tissue non-specific alkaline phosphatase gene (ALPL). Based on these findings, she was diagnosed with hypophosphatasia (HPP), and treatment with asfotase alfa, a recombinant human tissue-nonspecific alkaline phosphatase (TNSALP), was initiated. After six months of treatment with asfotase alfa, improvements were observed in the SF-36 score, six-minute walk distance, and grasping power. Although the overdiagnosis needs to be avoided, HPP should be considered in patients with undiagnosed musculoskeletal symptoms and a low serum ALP activity.

[Hepato-biliary and pancreatic disease and osteodystrophy].

It is well known that insulin resistance affects osteodystrophy, and there is an important relationship between insulin resistance and hepato-biliary disease. It is also well known that hepato-biliary and pancreatic disease is associated with osteodystrophy. In the present review, we describe the mechanism of diabetes and osteodystrophy due to hepato-biliary and pancreatic disease. Hepatic osteodystrophy is associated with malabsorption, abnormalities of vitamin D metabolism, inflammatory cytokines, receptor activator of NF-kappaB ligand, and insulin-like growth factor-1. In particular, tumor necrosis factor-alpha and malabsorption are important factors for viral and alcoholic hepatitis, respectively. Malabsorption due to steatorrhea is important for cholestatic disease and chronic pancreatitis. A greater focus on non-alcoholic steatohepatitis (NASH) and further investigations to clarify the relationship between osteodystrophy and NASH are needed.

[Effect of Statins on Glycemic Status and Plasma Adiponectin Concentrations in Patients with Type 2 Diabetes Mellitus and Hypercholesterolemia].

It is reported that statins have inconsistent effects on glycemic status and adiponectin concentrations in patients with type 2 diabetes mellitus (T2DM). We aimed to investigate the effect of statins on these variables in patients with T2DM and hypercholesterolemia. A control group comprising 24 patients with T2DM but without hypercholesterolemia was observed for more than 12 weeks, while 24 patients with T2DM and hypercholesterolemia were treated with statins for the same period (statin group). The percentage changes in the glycemic status [blood glucose and glycated hemoglobin (HbA1c)], and levels of plasma adiponectin [total and high molecular weight (HMW)] were compared between the two groups. The statin group had reduced percentage changes in HbA1c, blood glucose, and total and HMW-adiponectin concentration percentage changes that were similar to those in the control group. However, when matched for sex, age (±5 years) and HbA1c (±0.5%) with the control group, the pravastatin group had reduced percentage changes in the plasma HMW-adiponectin concentrations than the matched controls (p=0.023). However, there were no differences in the percentage changes in the plasma total adiponectin (p=0.137), HbA1c (p=0.202), or blood glucose concentrations (p=0.450) between the two groups. Pravastatin treatment had no effect on the glycemic status of patients with T2DM and hypercholesterolemia, but may reduce the percentage changes in the plasma HMW-adiponectin concentrations. Hence, patients with T2DM and hypercholesterolemia receiving long-term treatment with pravastatin might experience increased insulin resistance.

Glucagon promotes colon cancer cell growth via regulating AMPK and MAPK pathways.

Cancer is one of the major causes of death in diabetic patients, and an association between antidiabetic drugs and cancer risk has been reported. Such evidence implies a strong connection between diabetes and cancer. Recently, glucagon has been recognized as a pivotal factor implicated in the pathophysiology of diabetes. Glucagon acts through binding to its receptor, glucagon receptor (GCGR), and cross-talk between GCGR-mediated signals and signaling pathways that regulate cancer cell fate has been unveiled. In the current study, expression of GCGR in colon cancer cell lines and colon cancer tissue obtained from patients was demonstrated. Glucagon significantly promoted colon cancer cell growth, and GCGR knockdown with small interfering RNA attenuated the proliferation-promoting effect of glucagon on colon cancer cells. Molecular assays showed that glucagon acted as an activator of cancer cell growth through deactivation of AMPK and activation of MAPK in a GCGR-dependent manner. Moreover, a stable GCGR knockdown mouse colon cancer cell line, CMT93, grew significantly slower than control in a syngeneic mouse model of type 2 diabetes with glycemia and hyperglucagonemia. The present observations provide experimental evidence that hyperglucagonemia in type 2 diabetes promotes colon cancer progression via GCGR-mediated regulation of AMPK and MAPK pathways.

An Autopsy Case of Pulmonary Tumor Thrombotic Microangiopathy Due to Rapidly Progressing Colon Cancer in a Patient with Type 2 Diabetes.

We herein describe a case of pulmonary tumor thrombotic microangiopathy (PTTM) with rapidly progressing colon cancer. A 61-year-old man who had been receiving treatment for type 2 diabetes mellitus for 3 years was hospitalized due to critical hypoxemia. Computed tomography, which had not shown any abnormalities 3 months previously, revealed a tumor in the ascending colon, multiple nodules in the liver, and the absence of any lung abnormalities. On day 3 of hospitalization, a sudden onset of severe dyspnea and tachycardia occurred, followed by death. Autopsy revealed microscopic metastatic tumor emboli in multiple pulmonary vessels with fibrin thrombus and intimal proliferation, which led to a diagnosis of PTTM.

A Case of Euthyroid Graves' Ophthalmopathy in a Patient Sero-Negative for TSH Receptor Autoantibody.

We report of a case of Graves' ophthalmopathy presented solely with symptoms of the eyes with normal thyroid function tests and negative immunoreactive TSH receptor autoantibody. 40-year-old male was referred to our hospital due to 2-month history of ocular focusing deficit without any signs or symptoms of hyper- or hypothyroidism. Serum thyroid function tests and 99mTc uptake were both within the normal range. Anti-thyroid autoantibodies were all negative except for the cell-based assay for serum TSH receptor stimulating activity. Since orbital CT scan and MRI gave typical results compatible with Graves' ophthalmopathy, we treated the patients with corticosteroid pulse therapy and orbital radiation therapy, leading to a partial improvement of the symptoms. This case gives insights into the potential pathophysiologic mechanism underlying Graves' ophthalmopathy and casts light upon the difficulties of establishing the diagnosis in a euthyroid case with minimal positive results for anti-thyroid autoantibodies.

Alteration of the responses of gastric smooth muscle to endothelin in streptozotocin-induced diabetic rats.

Diabetic gastropathy is suggested to be the result of not only an autonomic neuropathy but also to disorder of the spontaneous rhythmic motility of the gastric smooth muscle. Attempts were made to investigate the alteration of the effects of endothelin-1 (ET-1), which is known to enhance the spontaneous activity of gastrointestinal smooth muscle, on gastric activity in streptozotocin (STZ)-induced diabetic rats. STZ-induced diabetic rats were prepared by the injection of Sprague-Dawley (SD) rats with STZ (i.p.). Isometric mechanical responses were recorded in isolated circular smooth muscle strips of the stomach antrum, to measure changes in the rhythmicity of the smooth muscle. ET-1 (10 nM) significantly elevated the resting tension and the frequency of spontaneous contraction, but did not alter the amplitude of the spontaneous oscillatory contractions in normal rats. In diabetic rats, ET-1 elevated the resting tension, and spontaneous contractions were increased in frequency, however they were decreased in amplitude. In normal rats, sarafotoxin S6c (S6c, 10 nM), a selective ET(B) receptor agonist, elevated the resting tension slightly and increased both the frequency and amplitude of the spontaneous contractions. However, S6c significantly elevated the resting tension alone in STZ-induced diabetic rats. Selective stimulation of endothelin type A (ET(A)) receptors with ET-1, in the presence of a selective antagonist of ET(B) receptors, produced similar responses in the gastric muscle of both normal and diabetic rats. These results indicate that ET-1 elevates the resting tension and increases the frequency of the spontaneous oscillatory contractions in both normal and STZ-induced diabetic rats, to a similar extent. However, the specific actions on ET(B) receptors were quite different between the two: the elevating actions on the resting tension were much greater in STZ-diabetic rats than in normal rats. The results suggested the facilitation of ET(B) receptor signaling in the antrum during the pathogenesis of diabetic gastropathy.

Effects of histamine 2 receptor antagonists on endothelial-neutrophil adhesion and surface expression of endothelial adhesion molecules induced by high glucose levels.

Neutrophil-endothelial adhesion is a crucial step in vascular inflammation and is recognized as a direct cause of serious atherosclerosis-mediated diseases. We previously demonstrated that high concentrations of glucose increased adhesion in a protein kinase C (PKC)-dependent manner within 48 h of administration by increasing the surface expression of endothelial adhesion molecules. In this study, we focused on the effects of histamine 2 receptor antagonists on endothelial-neutrophil adhesion and on the surface expression of endothelial adhesion molecules mediated by high glucose levels. Histamine 2 receptor antagonists have pleiotropic effects; they not only block the secretion of gastric acid, but also inhibit cell-cell adhesion, resulting in inhibition of metastasis. However, relevant mechanisms of action are not yet fully understood. Of three histamine 2 receptor antagonists (cimetidine, ranitidine, and famotidine), only cimetidine significantly attenuated adhesion mediated by 48-h incubation with 27.8 mM glucose. Cimetidine was found to decrease the surface expression of endothelial adhesion molecules intercellular adhesion molecule-1 and P-selectin, but not E-selectin. To determine the effects of cimetidine on intracellular level, we examined the effects of cimetidine on PKC-induced changes in adhesion, as well as the effects of nitric oxide (NO) synthase inhibitors on cimetidine. We found that NO synthase inhibitors reduced the inhibitory effects of cimetidine, whereas cimetidine did not affect adhesion mediated by a PKC activator. These data suggest that cimetidine acts directly on endothelial cells to inhibit high-glucose-induced expression of adhesion molecules and neutrophil adhesion mediated by increasing endothelial NO production, but not by inhibiting PKC.

Severe ascites with hypothyroidism and elevated CA125 concentration: a case report.

Ascites caused by hypothyroidism is rare and the pathogenesis is unclear. Several reports have presented cases of progressive ascites with hypothyroidism and elevated tumor markers. We report a 31-year-old female case with massive ascites and elevated serum CA 125 concentrations. The patient had no typical feature of hypothyroidism except an accumulation of ascitic fluid which showed elevated total protein concentration and a high serum-ascites albumin gradient (SAAG). There was no finding of malignancy. Following thyroid hormone replacement, the ascites was completely resolved accompanied by reduced concentrations of serum CA125. In general, primary hypothyroidism with ascites presents with coexisting massive pericardial or pleural effusion. The massive ascites and increased serum CA125 concentrations may have led us to make the incorrect diagnosis of ovarian malignancy. The evaluation of thyroid function is useful to determine the pathology of high-protein ascites or elevated tumor markers, and ascites may be treatable by thyroid replacement therapy.

Nocturnal reactive hypoglycaemia well treated subjectively and objectively with voglibose.

Clinicians sometimes encounter difficulty in diagnosing hypoglycaemia. Here, we present a case report of a 53-year-old woman with recurrent nocturnal hypoglycaemia. A continuous glucose monitoring system (CGMS) revealed postprandial hyperglycaemia and subsequent hypoglycaemia, and an oral glucose tolerance test showed an impaired glycaemic and delayed hyperinsulinaemic pattern. On the basis of these clinical findings, we diagnosed her unexplained hypoglycaemia as reactive hypoglycaemia. CGMS showed a sharp contrast of diurnal variation in blood glucose levels including hypoglycaemia between before and after treatment with an alpha-glucosidase inhibitor, voglibose. Her hypoglycaemic attacks disappeared.

Mechanical and electrophysiological effects of endothelin-1 on guinea-pig isolated lower oesophageal sphincter circular smooth muscle.

1. The effects of endothelin-1 (ET-1) on guinea-pig lower oesophageal sphincter (LOS) circular smooth muscle were investigated by using intracellular microelectrodes and isometric tension recording techniques. 2. ET-1 produced biphasic mechanical responses; an initial transient relaxation followed by a sustained contraction. The initial relaxation was not inhibited by either tetrodotoxin (TTX, 1 microM) or L-N(G)-nitroarginine (L-NOARG, 100 microM). The sustained contraction was greatly attenuated by nifedipine (1 microM). 3. ET-1 (1 - 30 nM) induced a concentration-dependent hyperpolarisation that was unaffected by TTX or L-NOARG. The ET(A) receptor antagonist, BQ123 (0.3 microM) abolished the ET-1-induced hyperpolarisation, whereas the ET(B) receptor antagonist, BQ788 (0.3 microM) had no detectable effect. Sarafotoxin S6c (10 nM) did not change the membrane potential. 4. The ET-1-induced hyperpolarisation was abolished by apamin (0.1 microM). Interestingly, apamin abolished the ET-1-induced transient relaxation but potentiated the sustained contraction. 5. In Ca(2+)-free Krebs solution, the ET-1-induced hyperpolarisation was greatly attenuated and returned to the control value when the tissue was reperfused with Krebs solution containing Ca(2+). The ET-1-induced hyperpolarisation was insensitive to nifedipine but was attenuated by SK&F 96365 (1 - [beta-[3-(4 - methoxy - phenyl)propoxy] - 4 - methoxyphenethyl] - 1H-imidazole hydrochloride, 50 microM), an inhibitor of receptor-mediated Ca(2+) entry. The residual component of the ET-1-induced hyperpolarisation was sensitive to thapsigargin (1 microM). 6. These results demonstrate that, in guinea-pig LOS circular smooth muscle, ET-1 hyperpolarizes the membrane by activating apamin-sensitive K(+) channels, mainly as a result of receptor-mediated Ca(2+) entry and partly by Ca(2+) release from intracellular stores. The hyperpolarisation triggers the initial transient relaxation, which acts to oppose the sustained contraction.

Electrophysiological properties of inhibitory junction potential in murine lower oesophageal sphincter.

The electrophysiological properties of smooth muscle in the murine lower oesophageal sphincter (LOS) were investigated by intracellular microelectrode recording. Inhibitory junction potentials (IJPs) evoked by trains of field stimulation (30 V, 0.2-0.3 ms, 10 stimuli at 1-50 Hz) were observed in the murine LOS in the presence of atropine (1 microM) and nifedipine (1 microM). The IJP consists of two components, which we termed fast IJP and slow IJP. The fast IJP was partly sensitive to guanethidine (5 microM), pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS, 30 microM) and apamin (0.1 microM), suggesting that the fast IJP was produced partly through the activation of apamin-sensitive Ca2+-activated K+ channels and of P2-purinoceptors. The other part of the fast IJP was sensitive to N(omega)-nitro-L-arginine (L-NNA, 100 microM) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ, 1 microM), but insensitive to apamin (0.1 microM), iberiotoxin (50 nM) and charybdotoxin (30 nM). Slow IJP was sensitive to L-NNA (100 microM), ODQ (10 microM) and glibenclamide (10 microM), but insensitive to apamin (0.1 microM), iberiotoxin (50 nM) and charybdotoxin (30 nM). KT5823, a protein kinase G (PKG) inhibitor, had no effect on the fast and slow IJP in this tissue. It was suggested that, in the mouse LOS, adenosine trisphosphate (ATP) partly mediated the fast UP through apamin-sensitive Ca2+-activated K+ channels, and nitric oxide mediated the remained part of the fast IJP and the slow IJP through cGMP, but not PKG. ATP-sensitive K+ channels were suggested to be partly involved in the production of slow IJP, but the responsible channel(s) for the nitrergic fast IJP remained unclarified.

Effects of endothelin-1 on the membrane potential and slow waves in circular smooth muscle of rat gastric antrum.

Electrophysiological effects of endothelin-1 (ET-1) on circular smooth muscle of rat gastric antrum were investigated by using intracellular membrane potential recording techniques. ET-1 (10 nM) caused an initial hyperpolarization of the membrane which was followed by a sustained depolarization. ET-1 also increased the frequency but not the amplitude of slow waves. In the presence of the endothelin type A (ETA) receptor antagonist, BQ123 (1 microM), ET-1 (10 nM) depolarized the membrane and increased the frequency of slow waves, but without the initial hyperpolarization. The selective endothelin type B (ETB) receptor agonist, sarafotoxin S6c (10 nM), also depolarized the membrane and increased the frequency of slow waves. In the presence of the ETB receptor antagonist, BQ788 (1 microM), ET-1 (10 nM) hyperpolarized the membrane. However, in the presence of BQ788, ET-1 caused neither the depolarization nor the increase in the frequency of the slow waves. The ET-1-induced hyperpolarization was completely abolished by apamin (0.1 microM). In the presence of apamin, ET-1 depolarized the membrane and increased the frequency of slow waves. The ET-1-induced depolarization was significantly attenuated by 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS, 0.3 mM). The increase of the frequency by ET-1 was observed both in the presence and absence of DIDS. These results suggest that, ET-1 hyperpolarizes the membrane by the activation of Ca2+-activated K+ channels via ETA receptors, and depolarizes the membrane by the activation of Ca2+-activated Cl- channels via ETB receptors. ET-1 also appears to increase the frequency of slow waves via ETB receptors, however this mechanism would seem to be independent of membrane depolarization.

The mechanisms of inhibitory actions of gliclazide on neutrophils-endothelial cells adhesion and surface expression of endothelial adhesion molecules mediated by a high glucose concentration.

BACKGROUND: We previously reported that culture of endothelial cells in the presence of high glucose concentrations (27.8 and 55.5 mM) increase neutrophils adhesion because of the increase in endothelial adhesion molecules expression via activation of a protein kinase C (PKC) pathway. The antidiabetic sulfonylurea gliclazide, but not glibenclamide, inhibited these events, but the mechanisms involved were not clarified then. We present hereafter the results of further investigations of that effect with special reference to PKC activation. METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured for 48 h in a glucose-rich medium and neutrophils from healthy volunteers were then added and allowed to adhere for 30 min. Adhered neutrophils were quantified by measuring myeloperoxidase (MPO) activities and the surface expression of endothelial adhesion molecules was determined by enzyme immunoassay. RESULTS: Culture in the presence of a high glucose concentration (27.8 mM for 48 h) increased neutrophils-endothelial cells adhesion and the surface expression of intercellular adhesion molecule-1 (ICAM-1), P-selectin, and E-selectin on the endothelial cells. These phenomena were significantly inhibited by gliclazide (20 microM). On the other hand, phorbol 12-myristate 13-acetate (PMA), a PKC activator, had an effect similar to a high glucose concentration and that effect was also inhibited by gliclazide. CONCLUSIONS: These data suggest that gliclazide inhibits high glucose-mediated neutrophils-endothelial cells adhesion and expression of endothelial adhesion molecules through inhibition of a PKC pathway.

Cerivastatin ameliorates high insulin-enhanced neutrophil-endothelial cell adhesion and endothelial intercellular adhesion molecule-1 expression by inhibiting mitogen-activated protein kinase activation.

BACKGROUND AND AIMS: There is growing evidence that hyperinsulinemia is linked to the development of atherosclerosis in patients with diabetes. We demonstrated previously that high insulin exacerbates neutrophil-endothelial cell adhesion and endothelial intercellular adhesion molecule (ICAM)-1 expression through activation of protein kinase C (PKC) and mitogen-activated protein (MAP) kinase. Though 3-hydroxymethyl-3-glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have been employed as therapeutic agents in the treatment of dyslipidemia, which is frequently accompanied by diabetes mellitus; it is not known whether statins protect against leukocyte-endothelial interactions, especially in hyperinsulinemia. In this study, we determined which statin(s) could protect against endothelial reactions to high insulin. METHODS: Studies of adhesion between neutrophils from healthy volunteers and human umbilical vein endothelial cells incubated in regular insulin-rich medium with or without statins were performed. Adhered neutrophils were quantified by measuring their myeloperoxidase (MPO) activities, and endothelial expression of ICAM-1 was examined using an enzyme immunoassay. RESULTS: Both the increased neutrophil-endothelial cell adhesion and ICAM-1 expression caused by high insulin (100 microU/ml) for 48 h were significantly attenuated by pretreatment with cerivastatin (0.01 microM), but not by fluvastatin (0.5 microM) or pravastatin (0.05 microM). These protective actions of cerivastatin were attenuated by a key intermediate in the cholesterol biosynthesis pathway, mevalonate (400 microM). In addition, cerivastatin attenuated both neutrophil-endothelial cell adhesion and endothelial ICAM-1 expression enhanced by a MAP kinase activator, anisomycin (1 microM) but not by a PKC activator, PMA (10 nM). CONCLUSIONS: These results suggest that through inhibiting MAP kinase but not PKC activation therapy with cerivastatin would be promising strategy for inhibiting neutrophil-endothelial cell adhesion and endothelial ICAM-1 expression enhanced by high insulin, which is closely correlated with atherosclerosis.