Urinary Cell Adhesion Molecule 1 Is a Novel Biomarker That Links Tubulointerstitial Damage to Glomerular Filtration Rates in Chronic Kidney Disease.

Cell adhesion molecule 1 (CADM1) is an immunoglobulin superfamily member strongly expressed on renal tubular epithelia in the urinary tract. Enzymatic cleavage of its ectodomain increases in chronic kidney disease (CKD), and is assumed to contribute to tubulointerstitial lesion formation. Because the cleaved ectodomain fragments are likely to be released into the urine, a sandwich enzyme-linked immunosorbent assay (ELISA) system for urinary CADM1 was developed using two anti-ectodomain antibodies. Urinary CADM1 concentrations in patients with CKD based on various forms of glomerulonephritis and nephropathy (n = 127) were measured. A total of 44 patients (35%) had elevated CADM1 concentrations over the normal upper limit (362 pg/mL), with a mean of 1,727 pg/mL. Renal biopsy specimens of all patients were pathologically scored for tubulointerstitial lesions using epithelial degeneration, interstitial inflammation, and fibrosis. There were no correlations between urinary CADM1 concentrations and pathological scores or any widely used renal markers, including glomerular filtration rate (GFR), but there was a weak inverse correlation between pathological scores and GFR (R2 = 0.292). Notably, this correlation gradually increased in patients with increasing CADM1 concentrations, and reached a maximum R 2 (0.899) at a cutoff of 1,569 pg/mL. The results of this study suggest that urinary CADM1 is a useful marker indicating tubulointerstitial damage from elevated GFR levels in CKD.

Diverse associations between oxidative stress and thromboxane A2 in hypertensive glomerular injury.

We examined the potential contributions of oxidative stress and thromboxane A2 (TXA2) to the development of regional heterogeneity in hypertensive glomerular injury using stroke-prone spontaneously hypertensive rats (SHRSP), an animal model of human essential hypertension. We also examined the effect of antioxidant treatment on the regional expression of thromboxane synthase (TXAS) mRNA using a microdissection method. Increases in the glomerular expression of TXAS mRNA were observed in the SHRSP at 15 weeks of age compared with those in the age-matched normotensive control Wistar-Kyoto (WKY) rats: 2.4-fold and 3.1-fold in the superficial and juxtamedullary glomeruli, respectively (P < 0.05). The heme oxygenase-1 mRNA expression was markedly increased (greater than eightfold, P < 0.05) in both the superficial and juxtamedullary glomeruli in the SHRSP compared with the expression in the WKY rats. In contrast to our expectations, the treatment of SHRSP with tempol (a superoxide dismutase mimetic) significantly (P < 0.05) increased the TXAS mRNA expression in the superficial glomeruli and did not improve the histological injury or albuminuria, which were both aggravated. Moreover, ozagrel (a TXAS inhibitor) had a suppressive effect on the TXAS mRNA expression and significantly (P < 0.05) improved the histological injury. These results indicated that although TXA2 and oxidative stress are linked to each other, TXA2 rather than oxidative stress may be a better therapeutic target to improve hypertensive glomerular injury.

Nivolumab-induced acute granulomatous tubulointerstitial nephritis in a patient with gastric cancer.

We here report a case of nivolumab-induced acute granulomatous tubulointerstitial nephritis in a patient with gastric cancer. A 68-year-old woman with recurrent gastric cancer developed acute kidney injury associated with kidney enlargement and urinary leukocytes after 38 cycles of nivolumab treatment. A diagnosis of acute granulomatous tubulointerstitial nephritis was made based on kidney biopsy findings. Immunohistochemistry revealed expression of programmed cell death-ligand 1 (PD-L1) in degenerated epithelial cells of collecting tubules. Among infiltrating immune cells, aggregation of T cells was more extensive than that of B cells, with CD4+ T cells outnumbering CD8+ T cells, consistent with the relative numbers of these cells in the circulation. Treatment with methylprednisolone (1.0 mg/kg daily) led to a rapid improvement in renal function and reduction in the number of circulating CD4+ T cells. Prompt administration of high-dose corticosteroid is thus recommended after diagnosis of this adverse event of nivolumab treatment by kidney biopsy.

Efficacy of Cryofiltration for Treatment of Mixed Cryoglobulinemia: A Report of Four Cases.

Cryoglobulinemia can induce systemic vasculitis affecting various organs such as skin, peripheral nerves, and kidney. The disease can induce chronic organ failure and even be life-threatening. Cryofiltration has been applied for the treatment of cryoglobulinemic vasculitis. We have experienced four cases with mixed cryoglobulinemia showing severe and progressive clinical manifestations, including skin purpura, nephrotic syndrome, acute kidney injury, and peripheral neuropathy. Cryofiltration in conjunction with conventional pharmacological therapies appeared to be safe and effective. After the treatments, plasma cryoglobulins were markedly reduced and the disease was well controlled. Although its efficacy has not yet been well established, this report can be another evidence showing efficacy of cryofiltration for treatment of mixed cryoglobulinemia.

Epigenetic Regulation Through SIRT1 in Podocytes.

SIRT1 is an NAD-dependent deacetylase. One important role of SIRT1 is its deacetylation activity in the modulation of cell stress signals via epigenetics. In podocytes, SIRT1 regulates the expression of important genes such as PGC-1α, Foxo4, p65 and STAT3, which act to maintain podocyte function by modulating the levels of histone acetylation. Here, we confirmed that SIRT1 protects podocytes by maintaining PGC-1α via its deacetylase-activated transcriptional activity in mitochondria and podocytes. We then showed that the alteration of Foxo4 (forkhead box O4) acetylation and decrease in SIRT1 promote podocyte apoptosis in diabetic nephropathy, resulting in the gradual development of diabetic nephropathy. Next, we showed that advanced glycation end products (AGEs) induced p65 and STAT3 acetylation in human podocytes. Decreased Sirt1 activity in podocytes results in the development of proteinuria and kidney injury via the acetylation of p65 and STAT3. These findings suggest that the beneficial effects of SIRT1 in diabetic nephropathy act via the deacetylation of transcription factors. In addition to its essential role in regulating the epigenetics of podocytes, we recently showed that SIRT1 is necessary to maintaining the function of slit membranes and podocytes. The actin cytoskeleton becomes vulnerable to various stresses, including oxidative stress, which in turn leads to the derangement and effacement of foot processes, slit membrane dysfunction, and proteinuria. SIRT1 protects podocytes and prevents glomerular injury by deacetylating cortactin and changing cortactin localization, thereby maintaining the integrity of the actin cytoskeleton. We expect that SIRT1 will be shown to sufficiently suppress the development of kidney dysfunction and will be proven useful in the near future. The clinical application of SIRT1-activated chemical agents has just started, and results are eagerly anticipated.

Pioglitazone reduces ER stress in the liver: direct monitoring of in vivo ER stress using ER stress-activated indicator transgenic mice.

It is known that endoplasmic reticulum (ER) stress is provoked under diabetic conditions and is possibly involved in the development of insulin resistance. In this study, using ER stress-activated indicator (ERAI) transgenic mice which express green fluorescent protein under ER stress conditions, we directly evaluated the effects of a diabetic agent pioglitazone on in vivo ER stress under diabetic conditions. In high fat and high sucrose diet-induced diabetic ERAI transgenic mice, 8 weeks of pioglitazone treatment reduced the accumulation of fat droplets in the liver and attenuated the development of insulin resistance. In the liver of the ERAI transgenic mice, ERAI fluorescence activity was clearly reduced as early as after 4 weeks of pioglitazone treatment, preceding the improvement of insulin resistance. In addition, after the pioglitazone treatment, serum free fatty acid and triglyceride levels were decreased, and serum adiponectin levels were increased. These data indicate that pioglitazone treatment suppresses ER stress in the liver which may explain, at least in part, the pharmacological effects of pioglitazone to reduce insulin resistance.

Glycated albumin is a better indicator for glucose excursion than glycated hemoglobin in type 1 and type 2 diabetes.

To determine the impact of blood glucose profile, involving fluctuation and excursion of blood glucose levels, on glycated proteins, we evaluated the association among the daily profile of blood glucose, and glycated albumin (GA) and HbA1c levels in patients with type 1 diabetes (n = 93) and type 2 diabetes (n = 75). GA levels were strongly correlated with HbA1c levels in type 1 (r = 0.85, P<0.0001) and type 2 diabetes (r = 0.61, P<0.0001), respectively. HbA1c levels were similar between patients with type 1 and type 2 diabetes, while GA levels were significantly higher in type 1 diabetes. Thus the ratio of GA levels to HbA1c levels was significantly higher in type 1 diabetes than that in type 2 diabetes (3.32 0.36 vs. 2.89 0.44, p<0.001). The degrees of GA levels and HbA1c levels correlated with maximum and mean blood glucose levels in patients with type 1 and type 2 diabetes. Stepwise multivariate analysis revealed that GA levels independently correlated with maximum blood glucose levels in type 1 diabetes (F = 43.34, P<0.001) and type 2 diabetes (F = 41.57, P<0.001). HbA1c levels also independently correlated with maximum blood glucose levels in type 1 diabetes (F = 34.78, P<0.001), as well as being correlated with mean blood glucose levels in type 2 diabetes (F = 11.28, P<0.001). In summary, GA could be a better marker for glycemic control than glycated hemoglobin in diabetic patients, especially for evaluating glycemic excursion, which is considered to be a major cause of diabetic angiopathy.

Direct monitoring of in vivo ER stress during the development of insulin resistance with ER stress-activated indicator transgenic mice.

Type 2 diabetes is one of the most prevalent and serious metabolic diseases in the world, and insulin resistance and pancreatic beta-cell dysfunction are the hallmarks of the disease. It has been suggested that endoplasmic reticulum (ER) stress is provoked under diabetic conditions and is possibly involved in the development of insulin resistance. In this study, using ER stress-activated indicator (ERAI) transgenic mice which express green fluorescent protein (GFP) under ER stress conditions, we directly monitored in vivo ER stress in various insulin target tissues such as liver, fat, and muscle in diabetic mice with insulin resistance induced by high fat and high sucrose (HF/HS) diet treatment. In the liver of the ERAI transgenic mice, ERAI fluorescence activity was clearly observed as early as after 4 weeks of HF/HS diet treatment, whereas it was not detected at all in the fat and muscle even after 12 weeks of HF/HS diet treatment. These results suggest that induction of ER stress is associated with the development of insulin resistance and that ER stress in the liver may facilitate the development of insulin resistance in the whole body. This is the first report to directly monitor in vivo ER stress in various insulin target tissues during the development of insulin resistance. In addition, our present results suggest that ERAI transgenic mice are very useful for evaluating in vivo ER stress, especially in the liver, during the development of insulin resistance.

Role of oxidative stress, endoplasmic reticulum stress, and c-Jun N-terminal kinase in pancreatic beta-cell dysfunction and insulin resistance.

Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Normal beta-cells can compensate for insulin resistance by increasing insulin secretion and/or beta-cell mass, but insufficient compensation leads to the onset of glucose intolerance. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates and insulin resistance aggravates. Under diabetic conditions, oxidative stress and endoplasmic reticulum stress are induced in various tissues, leading to activation of the c-Jun N-terminal kinase pathway. The activation of c-Jun N-terminal kinase suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of c-Jun N-terminal kinase in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the c-Jun N-terminal kinase pathway plays a central role in pathogenesis of type 2 diabetes and could be a potential target for diabetes therapy.

The forkhead transcription factor Foxo1 bridges the JNK pathway and the transcription factor PDX-1 through its intracellular translocation.

It has been shown that oxidative stress and activation of the c-Jun N-terminal kinase (JNK) pathway induce the nucleocytoplasmic translocation of the pancreatic transcription factor PDX-1, which leads to pancreatic beta-cell dysfunction. In this study, we have shown that the forkhead transcription factor Foxo1/FKHR plays a role as a mediator between the JNK pathway and PDX-1. Under oxidative stress conditions, Foxo1 changed its intracellular localization from the cytoplasm to the nucleus in the pancreatic beta-cell line HIT-T15. The overexpression of JNK also induced the nuclear localization of Foxo1, but in contrast, suppression of JNK reduced the oxidative stress-induced nuclear localization of Foxo1, suggesting the involvement of the JNK pathway in Foxo1 translocation. In addition, oxidative stress or activation of the JNK pathway decreased the activity of Akt in HIT cells, leading to the decreased phosphorylation of Foxo1 following nuclear localization. Furthermore, adenovirus-mediated Foxo1 overexpression reduced the nuclear expression of PDX-1, whereas repression of Foxo1 by Foxo1-specific small interfering RNA retained the nuclear expression of PDX-1 under oxidative stress conditions. Taken together, Foxo1 is involved in the nucleocytoplasmic translocation of PDX-1 by oxidative stress and the JNK pathway.

Decreased endogenous secretory advanced glycation end product receptor in type 1 diabetic patients: its possible association with diabetic vascular complications.

OBJECTIVE: The binding of advanced glycation end products (AGEs) to their receptor (RAGE) plays an important role in the development of diabetic vascular complications. In the present study, we examined circulating endogenous secretory RAGE (esRAGE) levels in subjects with type 1 diabetes and explored the possible association between esRAGE levels and the severity of diabetic vascular complications. RESEARCH DESIGN AND METHODS: Circulating esRAGE levels in serum were examined in 67 Japanese type 1 diabetic patients (22 men and 45 women, age 24.0 +/- 4.4 years [means +/- SD]) and 23 age-matched healthy nondiabetic subjects (10 men and 13 women aged 24.9 +/- 1.4 years). Daily urinary albumin excretion, the presence of retinopathy, and intima-media thickness (IMT) of the carotid artery were also evaluated. We further explored the association between esRAGE levels and severity of diabetic vascular complications. RESULTS: Circulating esRAGE levels were significantly lower in subjects with type 1 diabetes than in nondiabetic subjects (0.266 +/- 0.089 vs. 0.436 +/- 0.121 ng/ml, respectively, P < 0.0001) and was inversely correlated with HbA(1c) (A1C) levels (r = -0.614, P < 0.0001). In addition, multivariate regression analysis demonstrated that A1C was an independent risk factor for a low esRAGE value. Furthermore, circulating esRAGE levels were inversely correlated with carotid IMT (r = -0.325, P = 0.0017) and was one of the independent risk factors for IMT thickening. Furthermore, there was a significant difference (P = 0.0124) in esRAGE levels between patients without retinopathy (0.286 +/- 0.092 ng/ml) and those with retinopathy (0.230 +/- 0.074 ng/ml). CONCLUSIONS: Circulating esRAGE levels were significantly lower in type 1 diabetic patients than in nondiabetic subjects and were inversely associated with the severity of some diabetic vascular complications.

Hepatic insulin resistance induced by chronic hindlimb ischemia.

Peripheral vascular disease (PVD) has been reported to cause deterioration in insulin sensitivity. The precise mechanism of insulin resistance induced by PVD has not been clarified. To elucidate the mechanism causing impaired insulin action and glucose metabolism under peripheral ischemic conditions, we determined glucose turnover and glucose tolerance in hindlimb-ischemic (FAL) rats. The right femoral artery was ligated in hindlimb-ischemic (FAL) rats, while the artery was only exposed in the Sham operated (Sham) rats used as a control. Two weeks after the ligation, glucose tolerance was impaired and plasma insulin levels were significantly increased in FAL rats compared with Sham rats after intraperitoneal glucose loading (2 g kg(-1)). Under euglycemic hyperinsulinemic clamp conditions, the glucose infusion rate was significantly lower in FAL rats compared with Sham rats, but there was no significant difference in the glucose disappearance rate between the two groups. Hyperinsulinemia suppressed endogenous glucose production by 50% in Sham rats, while the suppression was 20% in FAL rats, indicating hepatic insulin resistance in FAL rats. mRNA analysis of isolated liver after the clamp experiment revealed that glucokinase mRNA, but not PEPCK and glucose-6-phosphatase mRNA, was significantly lower in FAL rats compared with Sham rats. In conclusion, chronic hindlimb ischemia impaired glucose tolerance associated with insulin resistance in the liver rather than the peripheral tissues.

Role of oxidative stress, endoplasmic reticulum stress, and c-Jun N-terminal kinase in pancreatic beta-cell dysfunction and insulin resistance.

Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Normal beta-cells can compensate for insulin resistance by increasing insulin secretion and/or beta-cell mass, but insufficient compensation leads to the onset of glucose intolerance. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates and insulin resistance aggravates. Under diabetic conditions, oxidative stress and endoplasmic reticulum stress are induced in various tissues, leading to activation of the c-Jun N-terminal kinase pathway. The activation of c-Jun N-terminal kinase suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of c-Jun N-terminal kinase in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the c-Jun N-terminal kinase pathway plays a central role in pathogenesis of type 2 diabetes and could be a potential target for diabetes therapy.

PDX-1/VP16 fusion protein, together with NeuroD or Ngn3, markedly induces insulin gene transcription and ameliorates glucose tolerance.

Diabetes is the most prevalent and serious metabolic disease, and the number of diabetic patients worldwide is increasing. The reduction of insulin biosynthesis in pancreatic beta-cells is closely associated with the onset and progression of diabetes, and thus it is important to search for ways to induce insulin-producing cells in non-beta-cells. In this study, we showed that a modified form of the pancreatic and duodenal homeobox factor 1 (PDX-1) carrying the VP16 transcriptional activation domain (PDX-1/VP16) markedly increases insulin biosynthesis and induces various pancreas-related factors in the liver, especially in the presence of NeuroD or neurogenin 3 (Ngn3). Furthermore, in streptozotocin-induced diabetic mice, PDX-1/VP16 overexpression, together with NeuroD or Ngn3, drastically ameliorated glucose tolerance. Thus PDX-1/VP16 expression, together with NeuroD or Ngn3, markedly induces insulin gene transcription and ameliorates glucose tolerance. This approach warrants further investigation and may have utility in the treatment of diabetes.

Oxidative stress, ER stress, and the JNK pathway in type 2 diabetes.

Pancreatic beta-cell dysfunction and insulin resistance are observed in type 2 diabetes. Under diabetic conditions, oxidative stress and ER stress are induced in various tissues, leading to activation of the JNK pathway. This JNK activation suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of the JNK pathway in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the JNK pathway plays a central role in pathogenesis of type 2 diabetes and may be a potential target for diabetes therapy.

The endoplasmic reticulum chaperone improves insulin resistance in type 2 diabetes.

To determine the role of the endoplasmic reticulum (ER) in diabetes, Akita mice, a mouse model of type 2 diabetes, were mated with either heterozygous knockout mice or two types of transgenic mice of 150-kDa oxygen-regulated protein (ORP150), a molecular chaperone located in the ER. Systemic expression of ORP150 in Akita mice improves insulin intolerance, whereas the exclusive overexpression of ORP150 in pancreatic beta-cells of Akita mice did not change their glucose tolerance. Both an insulin tolerance test and hyperinsulinemic-euglycemic clamp revealed that ORP150 enhanced glucose uptake, accompanied by suppression of oxidized protein. Furthermore, ORP150 enhanced the insulin sensitivity of myoblast cells treated with hydrogen peroxide. These data suggest that ORP150 plays an important role in insulin sensitivity and is a potential target for the treatment of diabetes.

A crucial role of MafA as a novel therapeutic target for diabetes.

MafA, a recently isolated pancreatic beta-cell-specific transcription factor, is a potent activator of insulin gene transcription. In this study, we show that MafA overexpression, together with PDX-1 (pancreatic and duodenal homeobox factor-1) and NeuroD, markedly increases insulin gene expression in the liver. Consequently, substantial amounts of insulin protein were induced by such combination. Furthermore, in streptozotocin-induced diabetic mice, MafA overexpression in the liver, together with PDX-1 and NeuroD, dramatically ameliorated glucose tolerance, while combination of PDX-1 and NeuroD was much less effective. These results suggest a crucial role of MafA as a novel therapeutic target for diabetes.

Oxidative stress and the JNK pathway in diabetes.

Under diabetic conditions, oxidative stress is induced and the JNK pathway is activated, which is involved in deterioration of pancreatic beta-cell function found in diabetes. Oxidative stress and/or activation of the JNK pathway suppress insulin gene expression, accompanied by reduction of PDX-1 DNA binding activity. Treatment with antioxidants and/or suppression of the JNK pathway protect beta-cells from some of the toxic effects of hyperglycemia. The JNK pathway is also involved in the progression of insulin resistance; suppression of the JNK pathway in obese diabetic mice markedly improves insulin resistance and ameliorates glucose tolerance. The phosphorylation state of key molecules for insulin signaling is altered upon modification of the JNK pathway. Taken together, the JNK pathway plays a crucial role in progression of insulin resistance as well as beta-cell dysfunction found in diabetes and thus could be a potential therapeutic target for diabetes.

Involvement of endoplasmic reticulum stress in insulin resistance and diabetes.

Type 2 diabetes is one of the most prevalent and serious metabolic diseases in the world, and insulin resistance and pancreatic beta-cell dysfunction are the hallmarks of the disease. In this study, we have shown that endoplasmic reticulum (ER) stress, which is provoked under diabetic conditions, plays a crucial role in the insulin resistance found in diabetes by modifying the expression of oxygen-regulated protein 150 (ORP150), a molecular chaperone that protects cells from ER stress. Sense ORP overexpression in the liver of obese diabetic mice significantly improved insulin resistance and markedly ameliorated glucose tolerance. Conversely, expression of antisense ORP150 in the liver of normal mice decreased insulin sensitivity. The phosphorylation state of IRS-1 and Akt, which are key molecules for insulin signaling, and the expression levels of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase, key enzymes of gluconeogenesis, were also altered by ORP150 overexpression. This is the first report showing that ER stress plays a crucial role in the insulin resistance found in diabetes and thus could be a potential therapeutic target for diabetes.

Acute elevation of free fatty acids impairs hepatic glucose uptake in conscious rats.

To investigate the dose-dependent effect of free fatty acid (FFA) on the hepatic glucose uptake (HGU), we determined hepatic glucose fluxes by a dual tracer technique during the basal state and euglycemic hyperinsulinemic clamp combined with a portal glucose load in three groups of rats given saline (saline), low-dose lipid (lipid-L), or high-dose lipid infusion (lipid-H). In the basal state, lipid infusion dose-dependently increased plasma FFA (saline, 400 +/- 50; lipid-L, 550 +/- 30; lipid-H, 1700 +/- 270 micromol l(-1); mean +/- S.E). Endogenous glucose production (EGP) in lipid-H was 63.5 +/- 5.5 micromol kg(-1) min(-1) and significantly higher than in the saline and lipid-L (40.2 +/- 2.9, 47.6 +/- 3.1 micromol kg(-1) min(-1), respectively). During euglycemic hyperinsulinemic clamp, plasma FFA decreased to 130 +/- 30 micromol l(-1) in saline, but remained at basal levels in lipid-L and lipid-H (470 +/- 30 and 1110 +/- 180 micromol l(-1), respectively). Insulin-suppressed EGP was complete in saline and lipid-L, but impaired in lipid-H (38.0 +/- 6.4 micromol kg(-1) min(-1)). Elevated FFA dose-dependently reduced HGU (saline, 12.2 +/- 0.9; lipid-L, 8.6 +/- 0.6; lipid-H, 4.7 +/- 1.4 micromol kg(-1) min(-1)). In conclusion, acutely elevated FFA impairs HGU as well as insulin-mediated suppression of EGP during hyperinsulinemic clamp with portal glucose loading. Impaired hepatic glucose uptake associated with elevated FFA may contribute to the development of insulin resistance in obesity and type 2 diabetes.