Inhibition of fibrotic changes in infrapatellar fat pad alleviates persistent pain and articular cartilage degeneration in monoiodoacetic acid-induced rat arthritis model

OBJECTIVE

We have reported that fibrotic changes in infrapatellar fat pad (IFP) after acute joint inflammation are closely associated with persistent pain in rats. In this study, to examine the effects of anti-fibrotic treatment on persistent pain, we used C-type natriuretic peptides (CNP) at the recovery phase after acute joint inflammation.

DESIGN

Thirty-two male Wistar rats were used in this study. Monoiodoacetic acid (MIA) was injected intra-articularly to induce IFP fibrosis and persistent pain. CNP was injected after acute inflammatory phase in the same knee joint. Time-course pain-avoidance behavior tests and histological analyses were performed to examine the effects of CNP.

RESULTS

Histological evaluations indicated that intra-articular injection of CNP inhibited fibrotic changes in IFP after acute inflammation. Incapacitance tests indicated that MIA injection into rat knee joint quickly decreased the percent weight on ipsilateral limb. In the vehicle group, the decrease was maintained up to day 28, suggesting that pain persistence occurred after acute inflammation (Day 0/Day 28, Est Dif -8.15, CI -10.78∼-5.53, Linear mixed-effect model). In contrast, the pain was alleviated in the CNP group after day 14 (Day0/Day 14, -0.51, -2.62-1.59). In addition, we observed significant improvement in the degree of articular cartilage degeneration at day 14 in the CNP group (OARSI score: vehicle 16.14 ± 4.37 vs CNP 6.87 ± 3.44, P < 0.01; Wilcoxon rank sum test).

CONCLUSION

Fibrotic changes in IFP may play important roles in both persistent pain and articular cartilage degeneration.

Neutrophil-lymphocyte ratio correlates with limited joint mobility of hand in patients with type 2 diabetes

Limited joint mobility (LJM) of hand, which is one of the complications of diabetic hand, is associated with diabetic micro- and macroangiopathy although the precise pathogenesis is not completely understood. Neutrophil-lymphocyte ratio (NLR), a simple and novel inflammatory marker, has been reported to have a predictive effect to some diabetic complications in recent years. However, it is not elucidated about the relationship between LJM of hand and NLR in patients with type 2 diabetes. We evaluated the relationships between LJM of hand and NLR in 335 consecutive patients with type 2 diabetes in this cross-sectional study. LJM of hand was diagnosed by a 'prayer sign' or 'table test'. LJM of hand was present in 80 patients. The patients with LJM of hand had significantly older age, longer duration of diabetes, worse renal function, and higher proportion of diabetic neuropathy, retinopathy and nephropathy. NLR in patients with LJM of hand was higher than that in patients without LJM of hand (2.54 ± 1.46 vs. 2.11 ± 1.04, p = 0.004). Multivariate logistic regression analysis revealed that LJM of hand was positively correlated with NLR (odds ratio, 1.31; 95% confidence interval 1.03-1.69, p = 0.027) after adjustment for age, sex, duration of diabetes, body mass index, hemoglobin A1c, hypertension and dyslipidemia. Our results demonstrate a positive relation between LJM of hand and NLR in patients with type 2 diabetes.

Relationship between limited joint mobility of hand and carotid atherosclerosis in patients with type 2 diabetes

AIM

Limited joint mobility (LJM) of hand, which is one of a complication of diabetic hand, has a close association with diabetic microangiopathy. However, it remains to be elucidated about the relationships between LJM of hand and subclinical atherosclerosis in patients with type 2 diabetes. Therefore, we conducted a cross-sectional study to evaluate the relationships between LJM of hand and carotid intima-media thickness (IMT) and plaque score in patients with type 2 diabetes.

METHODS

We evaluated the relationships between LJM of hand, and carotid IMT and plaque score, evaluated by carotid ultrasound examination, in 341 consecutive patients with type 2 diabetes. LJM of hand was diagnosed using a 'prayer sign' or 'table test'.

RESULTS

LJM of hand was present in 72 patients. Carotid IMT and plaque score were higher in patients with LJM of hand than those in patients without (1.45±0.66vs. 1.14±0.68mm, P=0.013 and 8.0±5.3vs. 5.4±4.8mm, P<0.001). Multivariate linear regression analysis revealed that LJM of hand was positively correlated with plaque score (β=0.423, P=0.043) after adjusted for age, sex, durations of diabetes, body mass index, hemoglobin A1c, creatinine, uric acid, smoking, hypertension and dyslipidemia.

CONCLUSIONS

Our results demonstrate a relation between LJM of hand and subclinical atherosclerosis, especially plaque score, in patients with type 2 diabetes. Diagnosis of diabetic hand is simple and non-invasive, and thus is a useful method for assessment of subclinical atherosclerosis in patients with type 2 diabetes.

Relationship between limited joint mobility of the hand and diabetic foot risk in patients with type 2 diabetes

BACKGROUND

Foot ulceration is a serious problem for patients with type 2 diabetes (T2D), and the early detection of risks for this condition is important to prevent complications. The present cross-sectional study in T2D patients determined the relationship between limited joint mobility (LJM) of the hand and diabetic foot risk classified using the criteria of the International Working Group on the Diabetic Foot (IWGDF).

METHODS

Relationships between LJM of the hand and foot risk according to IWGDF category, HbA1c, age, body mass index, blood pressure, estimated glomerular filtration (eGFR), and diabetic complications (including diabetic peripheral neuropathy [DPN] and peripheral arterial disease [PAD]) were evaluated in 528 consecutive T2D patients. Poor glycemic control was defined as HbA1c ≥ 7%.

RESULTS

Patients with LJM of the hand were older and had a longer duration of diabetes, a higher prevalence of diabetic complications, including DPN and PAD, and a higher IWDGF category (all P < 0.001). Multivariate logistic regression analysis revealed that the foot risk assessed with IWDGF category was correlated with age (odds ratio [OR] 1.04; 95% confidence interval [CI] 1.01-1.06; P = 0.001), poor glycemic control (OR 1.66; 95% CI 1.00-2.77; P = 0.04), eGFR (OR 0.98; 95% CI 0.97-0.99; P = 0.02), and the presence of LJM of the hand (OR 3.86; 95% CI 2.21-6.86; P < 0.001).

CONCLUSIONS

The results demonstrate a correlation between LJM of the hand and foot risk. Diagnosis of diabetic hand is simple and non-invasive, and is thus a useful method for assessing the risk of diabetic foot in T2D patients.

High Resolution Computed Tomography of Auditory Ossicles

Auditory ossicular sections were scanned at section thicknesses (mm)/section interspaces (mm) of 1.5/1.5 (61 patients), 1.0/1.0 (13 patients) or 1.5/1.0 (33 patients). At any type of section thickness/interspace, the malleal and incudal structures were observed with almost equal frequency. The region of the incudostapedial joint and each component part of the stapes were shown more frequently at a section interspace of 1.0 mm than at 1.5 mm. The visualization frequency of each auditory ossicular component on two or more serial sections was investigated. At a section thickness/section interspace of 1.5/1.5, the visualization rates were low except for large components such as the head of the malleus and the body of the incus, but at a slice interspace of 1.0 mm, they were high for most components of the auditory ossicles.

Replacement of neutral protamine Hagedorn insulin with the long-acting insulin analogue, detemir, improves glycemic control without weight gain in basal-bolus insulin therapy in Japanese patients with type 1 diabetes

Aims/Introduction:  The aim of the present study was to evaluate the efficacy of replacing neutral protamine Hagedorn insulin (NPH) with the long‐acting insulin analogue, detemir, in clinical practice.

Materials and Methods:  We carried out a retrospective study to compare the effects of replacing NPH with detemir in basal–bolus insulin therapy in Japanese patients with type 1 diabetes. A total of 19 patients were enrolled in the study, and changes in hemoglobin A_1c (HbA_1c), insulin dose, bodyweight, fasting blood glucose levels (FBG), within‐patient variability in FBG and prevalence in hypoglycemia were monitored for 12 weeks before replacement and during three periods after replacement; 1–12 weeks (period 1), 13–24 weeks (period 2) and 25–36 weeks (period 3).

Results:  HbA_1c values improved significantly in periods 2 and 3. Despite the total insulin dose remaining unchanged throughout the study, the basal insulin dose increased from 0.24 to 0.27 IU/kg/day in period 2 and 0.28 IU/kg/day in period 3. Bodyweight decreased from 61.8 to 60.8 kg in period 1, whereas FBG improved throughout the study. Within‐patient variability in FBG was lower with detemir treatment than with NPH, despite the number of hypoglycemic episodes increasing significantly after replacement.

Conclusions:  These findings show that the weight loss observed in patients was independent of the reduction in calorie intake resulting from less frequent hypoglycemic attacks. In Japanese patients with diabetes who received NPH, replacing NPH with detemir led to improvements in glycemic control without any weight gain. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00066.x, 2010)

Glycated albumin predicts the risk of mortality in type 2 diabetic patients on hemodialysis: evaluation of a target level for improving survival

Glycated albumin (GA) is considered a more reliable marker than glycated hemoglobin (HbA1c) for monitoring glycemic control, particularly in diabetic hemodialysis patients. We investigated the associations of GA, HbA1c, and random serum glucose levels with survival, and evaluated possible targets for improving survival in diabetic hemodialysis patients. In this prospective, longitudinal, observational study, we enrolled 90 diabetic hemodialysis patients across six dialysis centers in Japan. The median duration of follow-up was 36.0 months (mean follow-up, 29.8 months; range, 3-36 months). There were 11 deaths during the observation period. GA was a significant predictor for mortality (hazard ratio, 1.143 per 1% increase in GA; 95% confidence interval, 1.011-1.292; P = 0.033), whereas HbA1c and random glucose levels were not predictors for mortality. Receiver operating characteristics curve analysis showed that the cutoff value of GA for predicting the risk of mortality was 25%. In the Kaplan-Meier analysis, the cumulative survival rate was significantly greater in patients with GA ≤ 25% than in patients with GA >25%. GA predicted the risk of all-cause and cardiovascular mortality in diabetic hemodialysis patients. Our results suggest that GA ≤ 25% is an appropriate target for improving survival in diabetic hemodialysis patients.

Management of paediatric tuberculosis in provincial and district hospitals in Afghanistan

Case detection, diagnosis and treatment of tuberculosis 1 B) in children are challenging issues vorldwide. This study in Afghanistan aimed to evaluate paediatric TB case management, including contact investigation, at health facilities where all diagnostic processes were available. In 7 out of 8 regions of the country 1 province was selected. Documents used for management of paediatric TB cases were reviewed in 15 distinct hospitals and 8 provincial hospitals in the selected provinces. The key issues which emerged were: a low suspect rate among total outpatients (0.4%) and a very low suspect rate among children aged < 5 years; low performance of suspect management (68.5% suspects received further examinations); low utilization of other diagnostic methods; a high early defaulter rate (14.0%); and insufficient coverage of contact management (74.0%). This survey indicated that the Afghanistan national TB programme needs to develop plans to improve the quality of diagnosis, suspect management and contact management in paediatric TB cases.

Intracerebral transplantation of the A7 immortalized astrocytic cell line

The A7 cell line is an astrocyte-like cell immortalized by SV40 large T antigen, using retroviral-mediated gene transfer. These cells were transplanted into rat brains, and the graft-host interaction was investigated immunohistochemically. The A7 cells survived focally 2, 6 and 8 weeks after transplantation and retained the immunocytochemical properties observed in vitro. No immunological response was observed. GAP-43 and N-cadherin immunoreactivities were not expressed by A7 cells, but were seen in the matrix within the area of the graft and in the surrounding brain tissue. This indicates that A7 cells may stimulate expression of GAP-43 and N-cadherin immunoreactivity by host tissue. Expression of Thy 1.1 was not observed within the graft site after 2 weeks of survival, but 6 and 8 weeks after transplantation Thy 1.1 was observed within the graft area, indicating the possible co-existence of grafted cells and host tissue. Although indirect, these observations suggest that the A7 cells induce changes in host brain, including possible growth or regeneration of host tissue into the graft area.

18F-FDG PET/CT useful for the early detection of rapidly progressive fatal interstitial lung disease in dermatomyositis

Interstitial lung disease (ILD) frequently accompanies polymyositis (PM) and dermatomyositis (DM) and is a major cause of mortality. The rapid diagnosis of ILD is paramount. However, the early changes of presymptomatic ILD are difficult to detect. We present a patient with DM who had positive uptake in the lung of FDG-PET/CT as well as 'mechanic's hands' appearance, increased serum ferritin and serum anti-CADM-140 antibody, all before the detection of ILD by CT. Although aggressive treatment was initiated, the patient died of diffuse alveolar damage. These observations suggest that the pulmonary uptake of (18)F-FDG predicts rapidly progressive ILD in DM.

Association of genetic variants for susceptibility to obesity with type 2 diabetes in Japanese individuals

AIMS/HYPOTHESIS

In populations of East Asian descent, we performed a replication study of loci previously identified in populations of European descent as being associated with obesity measures such as BMI and type 2 diabetes.

METHODS

We genotyped 14 single nucleotide polymorphisms (SNPs) from 13 candidate loci that had previously been identified by genome-wide association meta-analyses for obesity measures in Europeans. Genotyping was done in 18,264 participants from two general Japanese populations. For SNPs showing an obesity association in Japanese individuals, we further examined diabetes associations in up to 6,781 cases and 7,307 controls from a subset of the original, as well as from additional populations.

RESULTS

Significant obesity associations (p < 0.1 two-tailed, concordant direction with previous reports) were replicated for 11 SNPs from the following ten loci in Japanese participants: SEC16B, TMEM18, GNPDA2, BDNF, MTCH2, BCDIN3D-FAIM2, SH2B1-ATP2A1, FTO, MC4R and KCTD15. The strongest effect was observed at TMEM18 rs4854344 (p = 7.1 × 10(-7) for BMI). Among the 11 SNPs showing significant obesity association, six were also associated with diabetes (OR 1.05-1.17; p = 0.04-2.4 × 10(-7)) after adjustment for BMI in the Japanese. When meta-analysed with data from the previous reports, the BMI-adjusted diabetes association was found to be highly significant for the FTO locus in East Asians (OR 1.13; 95% CI 1.09-1.18; p = 7.8 × 10(-10)) with substantial inter-ethnic heterogeneity (p = 0.003).

CONCLUSIONS/INTERPRETATION

We confirmed that ten candidate loci are associated with obesity measures in the general Japanese populations. Six (of ten) loci exert diabetogenic effects in the Japanese, although relatively modest in size, and independently of increased adiposity.

Diffuse alveolar hemorrhage in lupus nephritis complicated by microscopic polyangiitis

Diffuse alveolar hemorrhage (DAH) is a rare but fatal complication in patients with systemic lupus erythematosus (SLE). We describe a case of a 74-year-old woman who presented with DAH as an initial presentation of SLE. She also had microscopic polyangiitis clinically manifesting as crescentic glomerulonephritis and purpura with positive myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCA). The patient transiently improved when treated with plasma exchange and methylprednisolone pulse therapy; however, she died of recurrent pulmonary hemorrhage and concurrent cryptococcal pneumonia. This case indicates that MPO-ANCA is associated with severe organ involvement such as pulmonary hemorrhage and crescentic glomerulonephritis in SLE.

[Case of MPO-ANCA-positive Wegener's granulomatosis with hepatitis C virus infection]

A 77-year-old Japanese man was referred to our hospital because of the progression of renal dysfunction. Two months prior to the admission he had been diagnosed with otitis media. Urinalysis showed proteinuria and microscopic hematuria. Blood examination revealed renal dysfunction, hepatitis C virus (HCV)infection and positive myeloperoxidase (MPO)-ANCA. A chest CT revealed small infiltrates in the right middle lobe. The renal biopsy demonstrated crescentic glomerulonephritis with tubulitis. He was diagnosed as having Wegener's granulomatosis according to the American College of Rheumatology classification criteria. Methylprednisolone pulse therapy followed by oral prednisolone improved all of the otitis media, lung infiltrates and renal function. Recently, a high prevalence of ANCA has been reported in patients with HCV. It has also been reported that the prevalence of HCV infection is high in patients with Wegener's granulomatosis. Therefore, our case points to the clinical significance of HCV infection in ANCA-associated systemic vasculitis including Wegener's granulomatosis.

Pulmonary hemorrhage and acute renal failure as an initial presentation of multiple myeloma

The combined clinical presentation of acute renal failure with pulmonary hemorrhage is known as pulmonary-renal syndrome. We describe a case of an 84-year-old woman who presented with acute renal failure and pulmonary hemorrhage at onset. Renal biopsy and bone marrow aspiration showed cast nephropathy and an abnormal increase in plasma cells, respectively. She was diagnosed with multiple myeloma and successfully treated with plasma exchange and corticosteroids. This case indicates that multiple myeloma should be considered as a cause of pulmonary-renal syndrome.

Reduction in microalbuminuria as an integrated indicator for renal and cardiovascular risk reduction in patients with type 2 diabetes

OBJECTIVE

Microalbuminuria in diabetic patients is a predictor for diabetic nephropathy and cardiovascular disease. The aim of this study is to investigate the clinical impact of reducing microalbuminuria in type 2 diabetic patients in an observational follow-up study.

RESEARCH DESIGN AND METHODS

We enrolled 216 type 2 diabetic patients with microalbuminuria during an initial 2-year evaluation period and observed them for the next 8 years. Remission and a 50% reduction of microalbuminuria were defined as a shift to normoalbuminuria and a reduction <50% from the initial level of microalbuminuria. The association between reducing microalbuminuria and first occurrence of a renal or cardiovascular event and annual decline rate of estimated glomerular filtration rate (eGFR) was evaluated.

RESULTS

Twelve events occurred in 93 patients who attained a 50% reduction of microalbuminuria during the follow-up versus 35 events in 123 patients without a 50% reduction. The cumulative incidence rate of events was significantly lower in patients with a 50% reduction. A pooled logistic regression analysis revealed that the adjusted risk for events in subjects after a 50% reduction was 0.41 (95% CI 0.15-0.96). In addition, the annual decline rate of eGFR in patients with a 50% reduction was significantly slower than in those without such a reduction. The same results were also found in the analysis regarding whether remission occurred.

CONCLUSIONS

The present study provides clinical evidence implying that a reduction of microalbuminuria in type 2 diabetic patients is an integrated indicator for renal and cardiovascular risk reduction.

Iron status and the use of non-steroidal anti-inflammatory drugs in hemodialysis patients

We examined whether the use of non-steroidal anti-inflammatory drugs (NSAIDs) can affect the anemia and iron status of hemodialysis patients. We recruited patients from six dialysis centers who had undergone maintenance hemodialysis for at least four months. We examined the use of NSAIDs during the past three months based on their medical records and assigned the patients to three groups (group A, non-NSAID group; group B, aspirin group; and group C, non-aspirin NSAID group). Of the 446 patients, 95 (21.3%) were treated with aspirin and 103 (23.1%) were treated with non-aspirin NSAIDs. The serum iron level and transferrin saturation (TSAT) were significantly lower in group C patients than those in group A. However, the ratio of the patients who were administrated iron preparations during the past three months was significantly higher than that in the other two groups. The incidences of positive fecal occult blood tests did not differ substantially between the three groups. The ratios of the patients who were administrated recombinant human erythropoietin were the same between three groups. Using a multiple regression analysis, the administration of non-aspirin NSAIDs was identified as an independent factor for the decreased serum iron and the decreased TSAT levels. A multiple logistic regression analysis revealed that the patients using non-aspirin NSAIDs had an increased the requirement for iron preparation therapy (OR 2.03, 95% CI, 1.28-3.22). The use of non-aspirin NSAIDs may therefore increase the risk of the iron deficiency in patients undergoing hemodialysis.

SIRT1 Inhibits Transforming Growth Factor β-Induced Apoptosis in Glomerular Mesangial Cells via Smad7 Deacetylation

SIRT1, a class III histone deacetylase, is considered a key regulator of cell survival and apoptosis through its interaction with nuclear proteins. In this study, we have examined the likelihood and role of the interaction between SIRT1 and Smad7, which mediates transforming growth factor beta (TGFbeta)-induced apoptosis in renal glomerular mesangial cells. Immunoprecipitation analysis revealed that SIRT1 directly interacts with the N terminus of Smad7. Furthermore, SIRT1 reversed acetyl-transferase (p300)-mediated acetylation of two lysine residues (Lys-64 and -70) on Smad7. In mesangial cells, the Smad7 expression level was reduced by SIRT1 overexpression and increased by SIRT1 knockdown. SIRT1-mediated deacetylation of Smad7 enhanced Smad ubiquitination regulatory factor 1 (Smurf1)-mediated ubiquitin proteasome degradation, which contributed to the low expression of Smad7 in SIRT1-overexpressing mesangial cells. Stimulation by TGFbeta or overexpression of Smad7 induced mesangial cell apoptosis, as assessed by morphological apoptotic changes (nuclear condensation) and biological apoptotic markers (cleavages of caspase3 and poly(ADP-ribose) polymerase). However, TGFbeta failed to induce apoptosis in Smad7 knockdown mesangial cells, indicating that Smad7 mainly mediates TGFbeta-induced apoptosis of mesangial cells. Finally, SIRT1 overexpression attenuated both Smad7- and TGFbeta-induced mesangial cell apoptosis, whereas SIRT1 knockdown enhanced this apoptosis. We have concluded that Smad7 is a new target molecule for SIRT1 and SIRT1 attenuates TGFbeta-induced mesangial cell apoptosis through acceleration of Smad7 degradation. Our results suggest that up-regulation of SIRT1 deacetylase activity is a potentially useful therapeutic strategy for prevention of TGFbeta-related kidney disease through its effect on cell survival.

Silent information regulator 2 (SIRT1) attenuates oxidative stress-induced mesangial cell apoptosis via p53 deacetylation

Oxidative stress-induced apoptosis of renal glomerular cells is an important factor for the development of various kidney diseases. Identification of molecules that modulate this process could lead to the development of new strategies for preventing kidney diseases. In this study, we evaluated whether mammalian silent information regulator 2 (SIRT1), which has been recently identified as a cell survival factor countering various stressors, is a key regulator of oxidative stress-induced mesangial cell apoptosis. Morphological features of apoptotic cell death (nuclear condensation) and the expression of biochemical proapoptotic markers [cleavages of caspase-3 and poly (ADP-ribose) polymerase (PARP)] were assessed in murine mesangial cells (MMCs) exposed to hydrogen peroxide (H(2)O(2)). H(2)O(2) increased mesangial cell apoptosis, predominantly through p53 activation by acetylation, which is a posttranscriptional modification for p53 activation. H(2)O(2)-induced apoptosis was significantly attenuated in SIRT1-overexpressing MMCs, but enhanced in SIRT1-knockdown MMCs. Although SIRT1 did not affect H(2)O(2)-mediated phosphorylation of mitogen-activated protein (MAP) kinase, it interacted with p53 and inhibited H(2)O(2)-mediated p53 acetylation but not phosphorylation in MMCs. Our results indicate that SIRT1 can prevent oxidative stress-induced apoptosis through p53 deacetylation in mesangial cells. Upregulation of SIRT1 may provide a new strategy for preventing kidney glomerular diseases.

Polymorphisms of the protein kinase C-beta gene (PRKCB1) accelerate kidney disease in type 2 diabetes without overt proteinuria

OBJECTIVE

We investigated the contribution of PKC-beta gene (PRKCB1) polymorphisms to diabetic kidney disease in a prospective observational follow-up study.

RESEARCH DESIGN AND METHODS

A total of 364 Japanese subjects with type 2 diabetes without overt proteinuria were enrolled during 1996-1998 and followed until 2004. Five single nucleotide polymorphisms (-1504C/T, -546C/G, -348A/G, -278C/T, and -238C/G) in the promoter region of PRKCB1 were genotyped. The end points were transition from stage to stage of diabetic nephropathy as a time-to-event outcome and the annual decline rate of estimated glomerular filtration rate (eGFR) as a slope-based outcome.

RESULTS

During the study (median 6 years), 34 of 364 subjects (9.3%) progressed. Kaplan-Meier estimation revealed that subjects with both T allele at -1054 C/T and G allele at -546 C/G polymorphisms frequently showed transition to advanced stages of diabetic nephropathy (P = 0.015). The annual change rate in eGFR in the subjects with both alleles was also significantly higher than in others (-2.96 +/- 0.62 vs. -1.63 +/- 0.15 ml/min per 1.73 m(2)/year, P = 0.02). The estimated frequency of this risk T-G haplotype was significantly higher in the progressors who showed transition to advanced nephropathy stages (12%) than in the nonprogressors (5%) (odds ratio 2.3 [95% CI 1.0-5.2]), and it was also higher in those with accelerated decline of the Delta eGFR (> or =3 ml/min per 1.73 m(2)/year) than in those without (2.1 [1.1-3.9]).

CONCLUSIONS

Our study indicates that PRKCB1 is a predictor for worsening of kidney disease in Japanese subjects with type 2 diabetes.

N-acetyl-seryl-aspartyl-lysyl-proline inhibits DNA synthesis in human mesangial cells via up-regulation of cell cycle modulators

N-Acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) was originally reported as a natural inhibitor of the proliferation of stem cells. To elucidate whether Ac-SDKP inhibits the proliferation of human mesangial cells, we examined the effect of Ac-SDKP on fetal calf serum (FCS)- or platelet-derived growth factor (PDGF)-BB-induced DNA synthesis and a cell proliferation. Ac-SDKP inhibited PDGF-BB- or FCS-induced DNA synthesis without cellular toxicity. The protein expression of p53 and p27kip1 was significantly increased by Ac-SDKP. Ac-SDKP also up-regulated the PDGF-BB-stimulated expression of p21cip1 and suppressed PDGF-BB-induced cyclin D1 expression. In p53 knock-out human mesangial cells made with small interference RNA, the protein expression of p21cip1 and p27kip1 was also decreased and the inhibitory effect of Ac-SDKP on mesangial proliferation was completely abolished. Ac-SDKP increased the stability of p53 protein as demonstrated by pulse-chase experiment. These results suggest that p53 is the key mediator of Ac-SDKP-induced inhibition of DNA synthesis through the up-regulation of cell cycle modulators, highlighting a potential effect of Ac-SDKP on various progressive renal diseases.

MAPK/AP-1-dependent regulation of PAI-1 gene expression by TGF-beta in rat mesangial cells

BACKGROUND

Receptor-regulated Smads and/or mitogen-activated protein kinases (MAPKs) are involved in transforming growth factor-beta (TGF-beta)-induced expression of various genes, including plasminogen activator inhibitor-1 (PAI-1). Because the sequence of the promoter region in rat PAI-1 gene differs from that in the human gene, we examined the mechanisms of TGF-beta-induced rat PAI-1 expression in rat mesangial cells.

METHODS

TGF-beta1-induced PAI-1 and c-fos mRNA expressions were determined by Northern blot analysis. Activation of MAPKs and Smad proteins was evaluated by an immunoblot analysis. DNA binding activities of nuclear protein were examined by using an electrophoretic mobility shift assay (EMSA). The activities of PAI-1 promoter were measured by a luciferase reporter assay.

RESULTS

Extracellular-regulated kinase (ERK) and c-Jun NH-terminal kinase (JNK) phosphorylation, c-fos mRNA expression, and activator protein-1 (AP-1) DNA binding activity stimulated by TGF-beta1 were completely suppressed by the ERK kinase (MEK) inhibitors. EMSA and reporter analysis revealed that an AP-1-like sequence located in the proximal region of the rat PAI-1 promoter was the target for TGF-beta1, and the disruption of this AP-1-like sequence suppressed basal and TGF-beta1-induced promoter activation. TGF-beta1 also stimulated nuclear translocation of Smads and binding to palindromic Smad binding element (SBE) located in the rat PAI-1 promoter, without being affected by MEK inhibitor. Point mutation and deletion of palindromic SBE did not affect TGF-beta1-induced rat PAI-1 promoter activity. Moreover, interferon-gamma (IFN-gamma) inhibited TGF-beta1-induced PAI-1 expression through selectively suppressing the ERK-AP-1 pathway.

CONCLUSION

These results suggest that the essential requirement of MAPK/AP-1 activation for TGF-beta1-induced PAI-1 expression is unique to rat mesangial cells.

Inhibition of mTOR signaling with rapamycin attenuates renal hypertrophy in the early diabetic mice

Early diabetic nephropathy is characterized by renal hypertrophy that is mainly due to proximal tubular hypertrophy. Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase, and its signaling has been reported to regulate protein synthesis and cellular growth, specifically, hypertrophy. Therefore, we examined the effect of mTOR signaling on diabetic renal hypertrophy by using the specific inhibitor for mTOR, rapamycin. Ten days after streptozotocin-induced diabetes, mice showed kidney hypertrophy with increases in the phosphorylation of p70S6kinase and the expression of cyclin kinase inhibitors, p21(Cip1) and p27(Kip1), in the kidneys. The intraperitoneal injection of rapamycin (2 mg/kg/day) markedly attenuated the enhanced phosphorylation of p70S6kinase, the increment of cyclin-dependent kinase inhibitors, and renal enlargement without any changes of clinical parameters, including blood glucose, blood pressure, and food intake. Overexpression of a constitutive active form of p70S6kinase resulted in increased cell size of cultured mouse proximal tubule cells; thus, activation of p70S6kinase causes hypertrophy of proximal tubular cells. Our findings suggest that activation of mTOR signaling causes renal hypertrophy at the early stage of diabetes.