Klotho-related Molecules Upregulated by Smoking Habit in Apparently Healthy Men: A Cross-sectional Study.

While aging is unavoidable, the aging mechanism is still unclear because of its complexity. Smoking causes premature death and is considered as an environmental aging accelerator. In the present study, we focused on the influence of smoking to the serum concentration of anti-aging protein α-klotho (αKl) and the ß-klotho-associated protein fibroblast growth factor (FGF)-21 in men. Subjects consisted of apparently healthy men over 40 years of age who underwent health examination. Physical and biochemical parameters, including the levels of several cytokines and growth factors, were obtained from the subjects. Among middle-aged men (46.1 ± 5.1 years), serum levels of FGF-21, soluble αKl (sαKl), and inflammation-related cytokine interleukin (IL)-6 were significantly higher in smokers than in never-smokers. Serum levels of FGF-21 increased and correlated with alanine transaminase, γ guanosine-5'-triphosphate, and total cholesterol only in smokers, suggesting FGF-21 as a metabolic disorder-related factor in smokers. In aged men (60.3 ± 1.7 years), although the serum levels of sαKl in never-smokers were low, smokers showed highly increased serum levels of sαKl. Serum levels of sαKl was correlated with IL-6 in middle-aged never-smokers, suggesting sαKl regulates IL-6. However, this correlation was disrupted in smokers and aged men.

Gender differences in the relationship between blood pressure and body mass index during adolescence.

OBJECTIVE: In adults, gender and obesity play significant roles in the regulation of blood pressure (BP). This study investigated the effects of gender and body mass index (BMI) on BP during adolescence. DESIGN AND SETTING: A cross-sectional and longitudinal study involving 6838 students under twenty years old (median, eighteen years old; male, 4624; female, 2214) at Osaka University visited the Healthcare Center for their matriculation health examination from April to May in the years 2008, 2009, and 2010, and re-visited the Healthcare Center for their student health examination from May to June in the years 2011, 2012, and 2013. METHODS: Height, body weight, and BP were measured in students both on and 3 years after admission to Osaka University. RESULTS: On admission, the slope of the regression line for BMI and systolic BP (SBP) in non-underweight students was significantly different between genders. SBP and diastolic BP (DBP) increased in both genders during the observation period. Among male students who had a normal BMI on admission, those who had an increase in BMI of over 4% during the observation period showed a greater increase in SBP than those who had a change in BMI of -4% to 4%. On the other hand, female students showed no change in BP with the increase in BMI. CONCLUSIONS: The magnitude of BP elevation with increased BMI was associated with gender during adolescence. This may be a cause of the higher prevalence of hypertension in adult males.

A pilot study of the effects of eplerenone add-on therapy in patients taking renin-angiotensin system blockers.

HYPOTHESIS: This study determined the parameters for predicting the clinical effects of eplerenone (Ep) add-on therapy on blood pressure (BP) and proteinuria in patients taking angiotensin-converting enzyme inhibitors (ACEis) or angiotensin II type I receptor blockers (ARBs). MATERIALS AND METHODS: Patients were treated with a gradual increase of Ep to a final dose of 50 mg/day for 2 months. In 35 patients, the efficacy of Ep was evaluated by peripheral BP, proteinuria, and the transtubular K gradient (TTKG). Fifteen patients had additional analysis for central BP, plasma renin activity (PRA) and plasma aldosterone concentration (PAC), measured in the supine position, and 24-hour urine collection before and after receiving Ep. RESULTS: Ep add-on therapy reduced the mean arterial pressure (p=0.0005) and central BP (p=0.009) independently to the baseline PAC. Ep induced PRA, but failed to show effects on PAC, TTKG, or albuminuria. Correlation analysis showed inverse relationships between the percent reduction in albuminuria and baseline PAC. CONCLUSIONS: Ep add-on therapy in patients taking renin-angiotensin system blockers is expected to reduce BP, even in patients with low PAC. In contrast, the anti-proteinuric action of Ep is dependent on baseline plasma aldosterone levels. TTKG is not appropriate for evaluating the efficacy of Ep.

Febuxostat suppressed renal ischemia-reperfusion injury via reduced oxidative stress.

Febuxostat is a novel selective inhibitor of xanthine oxidase (XO), approved for treating hyperuricemia. XO inhibits the generation of uric acid (UA) as well as the resulting generation of superoxide. During renal ischemia-reperfusion (I/R) injury, the burst of reactive oxygen species (ROS) can trigger the inflammation and the tubular cell injury. As XO is a critical source of ROS, inhibition of XO could be a therapeutic target for I/R injury. Therefore, we performed this study to test the therapeutic effect of febuxostat on renal I/R injury. Sprague-Dawley rats, received vehicle or febuxostat, were subjected to right nephrectomy and left renal I/R injury. Febuxostat significantly suppressed XO activity, and thereby reduced oxidative stress, assessed by nitrotyrosine, thiobarbituric acid-reactive substances (TBARS) and urine 8-isoprostane. Furthermore, febuxostat reduced the induction of endoplasmic reticulum (ER) stress, assessed by GRP-78, ATF4, and CHOP. Vehicle-treated I/R injured rats exhibited elevated serum creatinine and UN, which were significantly suppressed in febuxostat-treated I/R-injured rats. Histological analysis revealed that fubuxostat-treated rats showed less tubular injury and interstitial fibrosis with reduction in ED1-positive macrophage infiltration, TUNEL positive apoptotic tubular cells, and interstitial smooth muscle α actin (SMαA) expression, compared to vehicle-treated rats. In conclusion; novel XO inhibitor, febuxostat, can protect kidney from renal I/R injury, and may contribute to preserve kidney function.

Use of xanthine oxidase inhibitor febuxostat inhibits renal interstitial inflammation and fibrosis in unilateral ureteral obstructive nephropathy.

BACKGROUND: Renal interstitial fibrosis is the common pathway in progressive renal diseases, where oxidative stress promotes inflammation and macrophage infiltration. Febuxostat is a novel nonpurine xanthine oxidase (XO)-specific inhibitor for treating hyperuricemia. While some reports suggest a relationship between hyperuricemia and chronic kidney disease (CKD), the renoprotective mechanism of an XO inhibitor in CKD remains unknown. Recent reports have focused on XO as a source of oxidative stress. METHODS: Here, we investigate the potential of febuxostat to reduce fibrogenic and inflammatory responses in an established interstitial fibrosis model-unilateral ureteric obstruction (UUO). Male Sprague-Dawley rats were divided into three groups: sham-operated group, vehicle-treated UUO group, and febuxostat-treated UUO group. RESULTS: Treatment with febuxostat diminished XO activity in obstructed kidneys, and suppressed nitrotyrosine, a marker of oxidative stress. Consequently, febuxostat inhibited early proinflammatory cytokine expression, followed by a reduction of interstitial macrophage infiltration. In addition, febuxostat suppressed transforming growth factor-ß messenger RNA expression, thereby ameliorating smooth muscle alpha actin and type I collagen expression. CONCLUSION: Our results provide evidence for the renoprotective action of febuxostat against the formation of interstitial fibrosis. A decrease in macrophage infiltration and interstitial fibrosis, along with a decrease of the oxidative stress marker, strongly suggests the existence of a causal relationship between them. Febuxostat may have therapeutic value in slowing or preventing interstitial fibrosis in patients with CKD.

Towards developing new strategies to reduce the adverse side-effects of nonsteroidal anti-inflammatory drugs.

The antipyretic and analgesic actions of nonsteroidal anti-inflammatory drugs (NSAIDs) are caused by the inhibition of prostaglandin E(2) (PGE(2)), thromboxane A(2) and prostacyclin (PGI(2)) production. Accumulating evidence suggests that the inhibition of PGE(2) production can cause adverse side-effects of NSAIDs on fluid and blood pressure regulation, such as hypertension and edema formation. Since both cyclooxygenase (COX)-1 and COX-2 isoforms contribute to the production of PGE(2), selective COX-2 inhibitors are not free of these adverse side-effects although they may be less severe. Four subtypes of PGE(2) receptors have been identified. The antipyretic action of blunted PGE(2) production is mediated predominantly by a reduced input to the prostaglandin E receptor 3 (EP(3)) pathway, whereas the analgesic action is mediated predominantly by a reduced input to the EP(1) pathway and perhaps by contributions from the other EP receptors. Accordingly, some of the adverse side-effects might be moderated by combined use of NSAIDs with selective EP(2) or EP(4) agonists that do not block the antipyretic or analgesic actions of NSAIDs that are mediated by reduced activation of EP(1) or EP(3) receptors. Moreover, EP(2) receptor-deficient mice had salt-sensitive hypertension and EP(4) receptor blockade moderated salt and water excretion and both EP(2) and EP(4) agonists had renoprotective effects. This suggests that strategies to maintain activation of EP(2) and EP(4) receptors during NSAID administration may not only reduce adverse effects but might confer additional benefits. In conclusion, enhancing EP(2) and EP(4) receptor activity by administration of selective agonists during the administration of NSAIDs has the potential to permit treating fever, inflammation and pain but with marginal adverse effects on fluid or blood pressure regulation.

Safety and efficacy of administering the maximal dose of candesartan in renal transplant recipients.

BACKGROUND: The regular dose of an angiotensin II type-1 receptor blocker (ARB) in renal transplant patients for hypertension is shown to be safe and effective; however, information on the appropriate dosing of ARBs in renal transplant patients is limited. We evaluate the efficacy and safety of the maximal dose of candesartan administered to renal transplant patients. METHODS: Sixty-nine recipients were enrolled in this study. Patients were divided into three groups based on the basal dose of candesartan: patients not taking candesartan (Group A); patients taking a low to medium dose of candesartan (2-4 mg/day; Group B); and patients taking a high dose of candesartan (8 mg/day; Group C). During the course of the study, the dose of candesartan was gradually increased to a final dose of 12 mg/day. Physiological and biochemical parameters were measured before and after the 12-month study period. RESULTS: Ninety-one percent of patients succeeded in continuing their administration of candesartan for 1 year and 75% tolerated the administration of the maximal dose of candesartan. Significant differences in proteinuria, albuminuria, serum creatinine, and estimated glomerular filtration rate (eGFR) level among the groups were detected. In Group A, candesartan reduced systolic blood pressure, decreased the levels of proteinuria, albuminuria, eGFR, and hemoglobin and increased plasma potassium, creatinine level, and plasma renin activity. CONCLUSION: The gradual increase of an ARB to its maximal dose in renal transplant patients is safe when carefully monitored. We were able to demonstrate the impact of maximal renin-angiotensin system (RAS) blockade on both proteinuria and albuminuria, which indicates the need for future, long-term randomized prospective trials to further establish the impact of maximal RAS blockade on renal and cardiovascular protection in transplant patients.

Effects of nicorandil on the reduction of BNP levels in patients with chronic kidney disease.

BACKGROUND: Patients with chronic kidney disease (CKD) still frequently experience cardiovascular events despite recent progress in treatment. We examined whether nicorandil, a hybrid nitrate and adenosine triphosphate-sensitive potassium channel opener, could improve a biomarker and physiological markers of cardiovascular events. METHODS: Patients with advanced stage CKD (stage III-V with or without peritoneal dialysis) were included in this trial if they were considered at high risk for cardiovascular events [past history of cardiovascular diseases, past history of coronary angiography, presence of endothelial dysfunction measured by reactive hyperemia peripheral arterial tonometry, and presence of high brain natriuretic peptide (BNP) values]. Patients were randomly assigned to be treated with or without oral nicorandil, 15 mg/day. BNP values and endothelial function (augmentation index, pulse wave velocity, and reactive hyperemia peripheral arterial tonometry) before and 1 month after the initiation of the trial were assessed. RESULTS: Nineteen patients (15 men, 4 women) with a mean age of 61 ± 10 (SD) years were included. The median baseline BNP value was 75.3 (interquartile range, 32.1-138.8) pg/ml, and the BNP level was significantly reduced in the nicorandil group (P < 0.05). Regression analysis demonstrated that only the use of nicorandil is related to a decrease of BNP levels [standardized ß coefficient, -75.1 (95% CI, -19.7 to -130.6), P = 0.01]. There were no significant changes in the rest of the parameters in the nicorandil group in comparison to the control group. The change in BNP levels was correlated with changes in the augmentation index (P < 0.01) and central pulse pressure (P = 0.03). CONCLUSIONS: Nicorandil treatment may reduce the level of BNP by reducing the central blood pressure in CKD patients.

A superagonistic monoclonal antibody for CD28 ameliorates crescentic glomerulonephritis in wistar-kyoto rats.

Regulatory T (Treg) cells play an important role in the resolution of crescentic glomerulonephritis, where a T helper 1 (Th1)-predominant immune response promotes crescent formation. Therefore, agents that increase Treg cells appear to be ideal for suppressing T-cell-mediated renal pathology. We hypothesized that a superagonistic monoclonal antibody for CD28 (JJ316), which has been known to preferentially expand Treg cells in vivo, could prevent nephrotoxic serum-induced nephritis in Wistar-Kyoto rats, one of the experimental models of crescentic glomerulonephritis. Administration of JJ316 attenuated crescent formation, proteinuria and glomerular accumulation of macrophages and CD8(+) T cells. These changes were accompanied by increased infiltration of Treg cells. Among glomerular macrophages, the CD163(+) subset was significantly increased after treatment, suggesting that Treg cells may modulate the phenotype of macrophages leading to resolution of glomerulonephritis. In an adoptive transfer experiment, two T-cell subsets (CD4(+)CD25(+) and CD4(+)CD25(-) T cells) purified from spleens and lymph nodes of donor rats primed with JJ316 3 d before were inoculated into nephritic recipient rats, which recapitulated the beneficial effects of in vivo administration of JJ316. Furthermore, a single injection of JJ316 administered 3 d after disease induction completely protected nephritic rats from death for 2 months. In conclusion, we demonstrated that treatment with JJ316 has a dramatic therapeutic effect on an experimental crescentic glomerulonephritis, possibly due to expansion and activation of Treg cells.

Cigarette smoking and progression of IgA nephropathy.

BACKGROUND: Multiple community-based cohort studies of mainly middle-aged and elderly populations have shown that cigarette smoking is a risk factor for chronic kidney disease. However, little information is available about an effect of cigarette smoking on progression of primary kidney diseases, including immunoglobulin A (IgA) nephropathy. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: 971 of 1,001 patients with a diagnosis of IgA nephropathy in 3 major nephrology centers in Osaka, Japan, between 1992 and 2005 who enrolled in the Study of Outcome and Practice Pattern of IgA Nephropathy (STOP-IgAN). PREDICTORS: Smoking status and number of cigarettes smoked at the time of diagnosis using kidney biopsy. Dose-dependent associations between cigarette smoking and outcomes were assessed in multivariate Cox proportional hazards models. Significantly different clinical characteristics between non-/past and current smokers were controlled for using propensity score-based adjustment, stratification, and matching. OUTCOMES: 50% increase in serum creatinine level as primary outcome. A composite outcome of a 100% increase in serum creatinine level or end-stage renal disease (ESRD) and ESRD alone as secondary outcomes. RESULTS: During the median 5.8 years (interquartile range, 2.6-10.2) of the observational period, 117 participants progressed to a 50% increase in serum creatinine level and 47 advanced to ESRD. Multivariate Cox proportional hazards models identified current smokers (HR, 2.03 [95% CI, 1.33-3.10] for primary outcome) and number of cigarettes at kidney biopsy (HR, 1.21 [95% CI, 1.06-1.39] per 10 cigarettes per day) as significant predictors of outcomes. Propensity score-based models confirmed these results. Tests for interaction showed that the association of current smoking with adverse outcomes was stronger in those with lower compared with higher estimated glomerular filtration rates. LIMITATION: Baseline smoking status was not verified using biochemical tests. Smoking status during the observational period was unavailable. CONCLUSIONS: Cigarette smoking, in a dose-dependent manner, was identified as a key prognostic factor in IgA nephropathy. Smoking cessation should be encouraged as part of the treatment for IgA nephropathy.

Specialist care and improved long-term survival of dialysis patients.

BACKGROUND: The quality of dialysis care provided by specialists is expected to be superior to that by nonspecialists. However, little is known about the actual effect of specialist care on long-term prognosis in dialysis patients. We sought to determine whether specialist care can actually be associated with better survival rates in a nationwide Japanese dialysis cohort. METHODS: The Japanese Society for Dialysis Therapy (JSDT) has annually reported clinical and demographic variables of dialysis patients for each prefecture in Japan since 1983. We analysed the data for the 47 prefectures from 1983 to 2006 to evaluate the relationship between the proportion of specialists and the cumulative survival rates for 5-year periods. RESULTS: Trend analyses revealed that a higher quintile of specialists was associated with a better cumulative survival rate at 5-, 10-, 15- and 20-year periods. Univariate analyses for the 47 prefectures showed a higher proportion of specialists to be correlated with a better cumulative survival at 10-, 15- and 20-year periods. Multivariate analyses revealed that the proportion of specialists persisted as an independent contributor for better survival at 10-, 15- and 20-year periods even after adjustment for age, sex, diabetes mellitus and socioeconomical status, while the survival rate at 5 years was at a nonsignificant level. CONCLUSIONS: While our study should be confirmed using data for individuals, this was not possible due to privacy issues. Therefore, based on our current findings, we conclude that for patients on maintenance dialysis, specialist care can be associated with better survival rates, particularly with longer follow-up.

The CXCL12 (SDF-1)/CXCR4 axis is essential for the development of renal vasculature.

CXC chemokine ligand 12 (CXCL12; stromal cell-derived factor 1) is a unique homeostatic chemokine that signals through its cognate receptor, CXCR4. CXCL12/CXCR4 signaling is essential for the formation of blood vessels in the gastrointestinal tract during development, but its contribution to renal development remains unclear. Here, we found that CXCL12-secreting stromal cells surround CXCR4-positive epithelial components of early nephrons and blood vessels in the embryonic kidney. In glomeruli, we observed CXCL12-secreting podocytes in close proximity to CXCR4-positive endothelial cells. Both CXCL12- and CXCR4-deficient kidneys exhibited identical phenotypes; there were no apparent abnormalities in early nephrogenesis or in differentiation of podocytes and tubules, but there was defective formation of blood vessels, including ballooning of the developing glomerular tuft and disorganized patterning of the renal vasculature. To clarify the relative importance of different cellular defects resulting from ablation of CXCL12 and CXCR4, we established endothelial cell-specific CXCR4-deficient mice, which recapitulated the renal phenotypes of conventional CXCR4-deficient mice. We conclude that CXCL12 secreted from stromal cells or podocytes acts on endothelial cells to regulate vascular development in the kidney. These findings suggest new potential therapeutic targets for remodeling the injured kidney.

Negative effects of anemia on quality of life and its improvement by complete correction of anemia by administration of recombinant human erythropoietin in posttransplant patients.

BACKGROUND: Anemia is a common complication in posttransplant patients (posttransplant anemia: PTA). We tested the hypothesis that targeting hemoglobin (Hb) over 13.3 g/dl by administration of recombinant human erythropoietin (rHuEPO-ad) has positive impact on quality of life (QOL). METHODS: Twenty-four patients, whose initial Hb and estimated glomerular filtration rate (eGFR) were 10.5 +/- 0.2 g/dl and 48.5 +/- 2.7 ml/(min 1.73 m2), respectively, were enrolled in the present study. Physical and mental QOL in these patients before and after rHuEPO-ad were acquired and summarized as physical summary sore (PSC) and mental summary sore (MSC), respectively, by the 36-item Short Form (SF-36), an international questionnaire for analysis of QOL. RESULTS: Before rHuEPO-ad, posttransplant patients had preserved MSC (54.1 +/- 2.3) but impaired PSC (32.6 +/- 3.2). rHuEPO-ad for 6 months increased their Hb to 13.7 +/- 0.3 g/dl. This was accompanied by improvement of PSC (49.1 +/- 2.1: P < 0.01 versus before rHuEPO-ad). MSC was preserved during rHuEPO-ad (54.4 +/- 1.6: NS versus before rHuEPO-ad). There was inverse correlation between initial PSC or MSC and responses of these parameters to rHuEPO-ad (PSC, P = 0.007; MSC, P = 0.009). Patients whose initial PSC was lower than 39.6 or whose initial MSC was lower than 39.4 were expected to improve their PSC or MSC by more than 10 by rHuEPO-ad. CONCLUSIONS: Anemia in posttransplant patients has negative impacts on their QOL. Scoring mental and physical QOL by SF-36 in posttransplant patients is useful to identify groups of patients whose QOL could be improved by rHuEPO-ad.

Active vitamin D and its analogue, 22-oxacalcitriol, ameliorate puromycin aminonucleoside-induced nephrosis in rats.

BACKGROUND: Recent studies have demonstrated that podocyte injury, which results in proteinuria, leads to tubulointerstitial fibrosis. Although some studies have revealed that vitamin D administration protects renal structure and function in mesangial cell proliferative and/or excessive matrix productive models, the effects of vitamin D on podocyte injury have remained uncertain. METHODS: In this study, we examined whether administration of active vitamin D (calcitriol) or its analogue, 22-oxacalcitriol (maxacalcitol), is preventative in podocyte injury using the puromycin aminonucleoside nephrosis model with neither mesangial proliferation nor matrix accumulation. RESULTS: Before the onset of proteinuria, renal 1alpha-hydroxylase and 24-hydroxylase were markedly down-regulated and up-regulated, respectively, leading to impaired vitamin D activation. Thereafter, serum 25-hydroxyvitamin D decreased along with the increased excretion of vitamin D-binding protein in urine. After confirming that podocytes express vitamin D receptor and all retinoid X receptors (RXRs) except RXR-alpha, we found that daily administration of calcitriol or its analogue 22-oxacalcitriol ameliorated the nephrotic state by protecting podocytes, as shown by the reduced staining of desmin (podocyte injury marker) and the upregulation of nephrin and podocin. These data suggest that the impairment of the vitamin D system plays a role in increasing proteinuria in podocyte injury. CONCLUSIONS: We demonstrated the breakdown of the vitamin D activation system in podocyte injury, and established a preventative role for vitamin D in podocyte injury.

Fully phosphorylated fetuin-A forms a mineral complex in the serum of rats with adenine-induced renal failure.

The serum glycoprotein fetuin-A is an important inhibitor of extra-osseous calcification, but correlations between serum fetuin-A levels and the extent of vascular calcification are controversial. In this study, we used a rat model of adenine-induced renal failure with secondary hyperparathyroidism that exhibits all characteristic features of patients with chronic kidney disease. These rats had medial vascular calcification along with reduced levels of both serum and hepatic fetuin-A. Treatment with an inhibitor of ectopic calcification, alendronate, decreased bone turnover and eliminated completely the vascular calcification in this rat model, but there was no change in the levels of hepatic and serum fetuin-A. Centrifugation of the serum of untreated rats with renal failure gave a small precipitate composed of fetuin-A, calcium, magnesium, and phosphate; this complex, absent from normal rat serum, was not found in the serum of alendronate-treated rats with renal failure. Rat serum contained three types of phosphorylated fetuin-A, as well as unphosphorylated forms, but only the fully phosphorylated fetuin-A was present in the mineral complex. The amount of this complex reflected the risk of mineral precipitation. Our results suggest that the measurement of serum fetuin-mineral complex rather than fetuin-A alone might provide a better indication of extra-osseous calcification propensity.

Pharmacokinetics of olmesartan medoxomil in hemodialysis patients: little effect of dialysis upon its pharmacokinetics.

Olmesartan medoxomil is a new angiotensin-2 receptor blocker (ARB). Its pharmacokinetics in hemodialysis patients has not been investigated. We evaluated the pharmacokinetics of olmesartan medoxomil in six patients on maintained hemodialysis. We divided these six patients into two groups; one group (n = 3) took the drug when hemodialysis started (HD day group), and the other group (n = 3) took in the morning on non-dialysis day (non HD day group). In each group, plasma concentrations of olmesartan were evaluated seven points after drug administration. In each point, blood pressure and heart rate were also measured. On HD day group, plasma concentrations in upstream of dialyser were compared with those in downstream of dialyser in three points. The area under the plasma concentration-time curve (AUC) in HD day group had no remarkable difference from those in non-HD day group. Another pharmacokinetic parameter, such as maximum plasma drug concentration (C (max)), biological half-life (t (1/2)) and time to reach C (max) (t (max)), were almost similar in both groups. Blood pressure and heart rate showed the same consequence as well. This result suggests that plasma concentration of olmesartan medoxomil does not decrease during hemodialysis, and that it is not necessary to change prescription on hemodialysis day or not.

Roles of vasoconstrictor prostaglandins, COX-1 and -2, and AT1, AT2, and TP receptors in a rat model of early 2K,1C hypertension.

Angiotensin (ANG) II activating type 1 receptors (AT(1)Rs) enhances superoxide anion (O(2)*(-)) and arachidonate (AA) formation. AA is metabolized by cyclooxygenases (COXs) to PGH(2), which is metabolized by thromboxane (Tx)A(2) synthase to TxA(2) or oxidized to 8-isoprostane PGF(2alpha) (8-Iso) by O(2)*(-). PGH(2), TxA(2), and 8-Iso activate thromboxane-prostanoid receptors (TPRs). We investigated whether blood pressure in a rat model of early (3 wk) two-kidney, one-clip (2K,1C) Goldblatt hypertension is maintained by AT(1)Rs or AT(2)Rs, driving COX-1 or -2-dependent products that activate TPRs. Compared with sham-operated rats, 2K,1C Goldblatt rats had increased mean arterial pressure (MAP; 120 +/- 4 vs. 155 +/- 3 mmHg; P < 0.001), plasma renin activity (PRA; 22 +/- 7 vs. 48 +/- 5 ng x ml(-1) x h(-1); P < 0.01), plasma malondialdehyde (1.07 +/- 0.05 vs. 1.58 +/- 0.16 nmol/l; P < 0.01), and TxB(2) excretion (26 +/- 4 vs. 51 +/- 7 ng/24 h; P < 0.01). Acute graded intravenous doses of benazeprilat (angiotensin-converting enzyme inhibitor) reduced MAP at 20 min (-36 +/- 5 mmHg; P < 0.001) and excretion of TxA(2) metabolites. Indomethacin (nonselective COX antagonist) or SC-560 (COX-1 antagonist) reduced MAP at 20 min (-25 +/- 5 and -28 +/- 7 mmHg; P < 0.001), whereas valdecoxib (COX-2 antagonist) was ineffective (-9 +/- 5 mmHg; not significant). Losartan (AT(1)R antagonist) or SQ-29548 (TPR antagonist) reduced MAP at 150 min (-24 +/- 6 and -22 +/- 3 mmHg; P < 0.001), whereas PD-123319 (AT(2)R antagonist) was ineffective. Acute blockade of TPRs, COX-1, or COX-2 did not change PRA, but TxB(2) generation by the clipped kidney was reduced by blockade of COX-1 and increased by blockade of COX-2. 2K,1C hypertension in rats activates renin, O(2)*(-), and vasoconstrictor PGs. Hypertension is maintained by AT(1)Rs and by COX-1, but not COX-2, products that activate TPRs.

Smooth muscle alpha-actin deficiency in myofibroblasts leads to enhanced renal tissue fibrosis.

Myofibroblasts are a major source of proinflammatory cytokines and extracellular matrix in progressive tissue fibrosis leading to chronic organ failure. Myofibroblasts are characterized by de novo expression of smooth muscle alpha-actin (SMalphaA), which correlates with the extent of disease progression, although their exact role is unknown. In vitro cultured myofibroblasts from kidney of SMalphaA knock-out mice demonstrate significantly more prominent cell motility, proliferation, and type-I procollagen expression than those of wild-type myofibroblasts. These pro-fibrotic properties are suppressed by adenovirus-mediated SMalphaA re-expression, accompanied by down-regulation of focal adhesion proteins. In interstitial fibrosis model, tissue fibrosis area, proliferating interstitial cell number, and type-I procollagen expression are enhanced under SMalphaA deficiency. In mesangioproliferative glomerulonephritis model, cell proliferation in the mesangial area is also enhanced in SMalphaA knock-out mice. Adenoviral SMalphaA introduction into renal interstitium obviously ameliorates tissue fibrosis in interstitial fibrosis model. These results indicate that SMalphaA suppresses the pro-fibrotic properties of myofibroblasts, highlighting the significance of smooth muscle-related proteins in moderating chronic organ fibrosis under pathological conditions.

Cyclooxygenase-1-deficient mice have high sleep-to-wake blood pressure ratios and renal vasoconstriction.

We used cyclooxygenase-1 (COX-1)-deficient mice to test the hypothesis that COX-1 regulates blood pressure (BP) and renal hemodynamics. The awake time (AT) mean arterial pressures (MAPs) measured by telemetry were not different between COX-1(+/+) and COX-1(-/-) (131+/-2 versus 126+/-3 mm Hg; NS). However, COX-1(-/-) had higher sleep time (ST) MAP (93+/-1 versus 97+/-2 mm Hg; P<0.05) and sleep-to-awake BP ratio (+8.6%; P<0.05). Under anesthesia with moderate sodium loading, COX-1(-/-) had higher MAP (109+/-5 versus 124+/-4 mm Hg; P<0.05), renal vascular resistance (23.5+/-1.6 versus 30.7+/-1.7 mm Hg . mL(-1) . min(-1) . g(-1); P<0.05) and filtration fraction (33.7+/-2.1 versus 40.2+/-2.0%; P<0.05). COX-1(-/-) had a 89% reduction (P<0.0001) in the excretion of TxB2, a 76% reduction (P<0.01) in PGE2, a 40% reduction (P<0.0002) in 6-ketoPGF1alpha (6keto), a 27% reduction (P<0.02) in 11-betaPGF2alpha (11beta), a 35% reduction (P<0.01) in nitrate plus nitrite (NOx), and a 52% increase in metanephrine (P<0.02). The excretion of normetanephrine, a marker for sympathetic nervous activity, was reduced during ST in COX-1(+/+) (6.9+/-0.9 versus 3.2+/-0.6 g . g(-1) creatinine . 10(-3); P<0.01). This was blunted in COX-1(-/-) (5.1+/-0.9 versus 4.9+/-0.7 g . g(-1) creatinine . 10(-3); NS). Urine collection during ST showed lower excretion of 6keto, 11beta, NOx, aldosterone, sodium, and potassium than during AT in both COX-1(+/+) and COX-1(-/-), and there were positive correlations among these parameters (6keto versus NOx; P<0.005; 11beta versus NOx; P<0.005; and NOx versus sodium; P<0.005). In conclusion, COX-1 mediates a suppressed sympathetic nervous activity and enhanced NO, which may contribute to renal vasodilatation and a reduced MAP while asleep or under anesthesia. COX-1 contributes to the normal nocturnal BP dipping phenomenon.

CCAAT/Enhancer-binding protein delta contributes to myofibroblast transdifferentiation and renal disease progression.

Myofibroblasts are pivotal participants in pathologic processes in a wide variety of organs, such as lung, liver, and kidney, by producing several inflammatory cytokines and extracellular matrices. The mechanism by which transdifferentiation from original cell to myofibroblast occurs, however, is still unclear. The expression of smooth muscle alpha-actin (SMalphaA) is the most characteristic feature of myofibroblasts; therefore, it was speculated that any factors that promote SMalphaA expression might be the key to transdifferentiation to myofibroblasts and disease exacerbation. A transcription factor CCAAT/enhancer-binding protein delta (C/EBPdelta) was identified and demonstrated to bind to sequences including the CArG motif from SMalphaA intron 1 and to increase transcriptional activity of this promoter. Expression of SMalphaA and C/EBPdelta in the glomerular area was upregulated in rat anti-Thy1 glomerulonephritis and mouse Habu-venom glomerulonephritis, both of which are models of mesangioproliferative glomerulonephritis. In the latter model, C/EBPdelta knockout mice demonstrated significantly less SMalphaA expression in the glomerular area on day 8 and less renal functional deterioration on day 14, compared with wild-type mice. These data suggest an important role for C/EBPdelta in myofibroblast transdifferentiation and glomerulonephritis exacerbation.