Production of Acetylcholine by Podocytes and its Protection from Kidney Injury in Glomerulonephritis.

BACKGROUND: One of the most important factors modulating endothelial health is acetylcholine, and while it is associated as a cholinergic neurotransmitter; it is also expressed by non-neuronal cells. However, its role in the kidney, which does not receive cholinergic innervation, remains unknown. METHODS: To determine if acetylcholine is produced in the kidney, we used ChAT(BAC)-eGFP (ChAT mice) transgenic mice in which enhanced green fluorescent protein (eGFP) is expressed under the control of the endogenous choline acetyltransferase (ChAT) transcriptional regulatory elements. We then investigated the role of acetylcholine in kidney disease by inducing anti- glomerular basement membrane glomerulonephritis (anti-GBM GN) in ChAT transgenic mice. RESULTS: We demonstrate ChAT, the sole enzyme responsible for acetylcholine production, was expressed in glomerular podocytes and produced acetylcholine. We also show during anti-GBM GN in ChAT transgenic mice, ChAT expression was induced in the glomeruli, mainly in podocytes and protects mice from kidney injury with marked reduction of glomerular proliferation/fibrinoid necrosis (by 71%) crescent formation (by 98%), and tubular injury (by 78%). In contrast, specific knockout of podocyte ChAT worsened the severity of the disease. The mechanism of protection included reduction of inflammation, attenuation of angiogenic factors reduction, and increase of eNOS expression. In vitro and in vivo studies demonstrated available drugs like cholinesterase inhibitors and ChAT inducers increased the expression of podocyte-ChAT and acetylcholine production. CONCLUSIONS: These findings suggest de novo synthesis of acetylcholine by podocytes protected against inflammation and glomerular endothelium damage in anti-GBM glomerulonephritis.

Uric acid induced the phenotype transition of vascular endothelial cells via induction of oxidative stress and glycocalyx shedding.

Recent data suggested a causative role of uric acid (UA) in the development of renal disease, in which endothelial dysfunction is regarded as the key mechanism. Endothelial-to-mesenchymal transition (EndoMT) and shedding of the glycocalyx are early changes of endothelial dysfunction. We investigated whether UA induced EndoMT in HUVECs and an animal model of hyperuricemia fed with 2% oxonic acid for 4 wk. UA induced EndoMT in HUVECs with a generation of reactive oxygen species via the activation of membranous NADPH oxidase (from 15 min) and mitochondria (from 6 h) along with glycocalyx shedding (from 6 h), which were blocked by probenecid. GM6001, an inhibitor of matrix metalloproteinase, alleviated UA-induced glycocalyx shedding and EndoMT. Antioxidants including N-acetyl cysteine, apocynin, and mitotempo ameliorated EndoMT; however, they did not change glycocalyx shedding in HUVECs. In the kidney of hyperuricemic rats, endothelial staining in peritubular capillaries (PTCs) was substantially decreased with a de novo expression of α-smooth muscle actin in PTCs. Plasma level of syndecan-1 was increased in hyperuricemic rats, which was ameliorated by allopurinol. UA caused a phenotypic transition of endothelial cells via induction of oxidative stress with glycocalyx shedding, which could be one of the mechanisms of UA-induced endothelial dysfunction and kidney disease.-Ko, J., Kang, H.-J., Kim, D.-A., Kim, M.-J., Ryu, E.-S., Lee, S., Ryu, J.-H., Roncal, C., Johnson, R. J., Kang, D.-H. Uric acid induced the phenotype transition of vascular endothelial cells via induction of oxidative stress and glycocalyx shedding.

Elevated copeptin, arterial stiffness, and elevated albumin excretion in adolescents with type 1 diabetes.

OBJECTIVE: We sought to evaluate copeptin concentrations in adolescents with and without type 1 diabetes (T1D) and examine the associations between copeptin and measures of arterial stiffness and kidney dysfunction. RESEARCH DESIGN AND METHODS: This analysis included 169 adolescents with T1D (12-19 years of age, 59% girls, mean HbA1c 9.0 ± 1.5% and diabetes duration of 8.6 ± 2.9 years), in addition to 61 controls without T1D. Arterial stiffness including carotid-femoral pulse wave velocity (CF-PWV), carotid-radial PWV (CR-PWV), augmentation index normalized to heart rate of 75 bpm (AIx@HR75), and brachial artery distensibility (BAD). Serum copeptin, urinary albumin-to-creatinine ratio (UACR), and estimated glomerular filtration rate (eGFR) by serum creatinine and cystatin C were also assessed. RESULTS: Compared to controls, adolescents with T1D had higher median (Q1-Q3) copeptin (7.5 [5.2-11.3] vs 6.4 [4.8-8.3] pmol/L, P = .01), mean ± SD eGFR (121 ± 23 vs 112 ± 16 mL/min/1.73m2 , P = .002) and lower BAD (7.1 ± 1.3 vs 7.2 ± 1.2%, P = .02). Adolescents with T1D in the in high tertile copeptin group (>9.1 pmol/L) had higher AIx@HR75 (10.7 ± 1.2 vs 5 ± 1.2, P = .001), CR-PWV (5.30 ± 1.0 vs 5.18 ± 1.0 m/s, P = .04), and UACR (12 ± 1 vs 8 ± 1 mg/g, P = .025) compared to those in low tertile (<5.8 pmol/L) after adjusting for age, sex, and eGFR. Copeptin inversely associated with CF-PWV independent of age, sex, eGFR, SBP, and HbA1c in T1D adolescents. CONCLUSIONS: Our data demonstrate that elevated copeptin was associated with worse arterial stiffness in adolescents with T1D. These findings suggest that copeptin could improve CVD risk stratification in adolescents with T1D.

Fructose and sugar: A major mediator of non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome; its rising prevalence parallels the rise in obesity and diabetes. Historically thought to result from overnutrition and a sedentary lifestyle, recent evidence suggests that diets high in sugar (from sucrose and/or high-fructose corn syrup [HFCS]) not only increase the risk of NAFLD, but also non-alcoholic steatohepatitis (NASH). Herein, we review the experimental and clinical evidence that fructose precipitates fat accumulation in the liver, due to both increased lipogenesis and impaired fat oxidation. Recent evidence suggests that the predisposition to fatty liver is linked to the metabolism of fructose by fructokinase C, which results in ATP consumption, nucleotide turnover and uric acid generation that mediate fat accumulation. Alterations to gut permeability, the microbiome, and associated endotoxemia contribute to the risk of NAFLD and NASH. Early clinical studies suggest that reducing sugary beverages and total fructose intake, especially from added sugars, may have a significant benefit on reducing hepatic fat accumulation. We suggest larger, more definitive trials to determine if lowering sugar/HFCS intake, and/or blocking uric acid generation, may help reduce NAFLD and its downstream complications of cirrhosis and chronic liver disease.

Role of bicarbonate supplementation on urine uric acid crystals and diabetic tubulopathy in adults with type 1 diabetes.

Uricosuria and crystallization are increasingly recognized risk factors for diabetic tubulopathy. This pilot clinical trial aimed to determine the acute effect of urinary alkalinization using oral sodium bicarbonate (NaHCO3 ) on UA crystals in adults with type 1 diabetes (T1D). Adults with T1D, ages 18 to 65 years (n = 45, 60% female, HbA1c, 7.5 ± 1.2%, 20.2 ± 9.3 years duration) without chronic kidney disease (eGFR ≥60 mL/min/1.73 m2 and albumin-to-creatinine ratio < 30 mg/g) received 2 doses of 1950 mg oral NaHCO3 over 24 hours. Fasting urine and serum were collected pre- and post-intervention. UA crystals were identified under polarized microscopy. Urine measurements included: osmolality, pH, UA, creatinine and kidney injury molecule-1 (KIM-1). NaHCO3 therapy increased mean ± SD urine pH from 6.1 ± 0.7 to 6.5 ± 0.7 (P < .0001). Prior to therapy, 31.0% of participants had UA crystals vs 6.7% post therapy (P = .005). Change in urine pH inversely correlated with change in urine KIM-1 (r:-0.51, P = .0003). In addition, change in urine UA over 24 hours correlated with change in urine KIM-1 (r:0.37, P = .01). In conclusion, oral NaHCO3 normalized urine pH and decreased UA crystals, and may hold promise as an inexpensive and safe tubulo-protective intervention in individuals with T1D.

Fructose increases risk for kidney stones: potential role in metabolic syndrome and heat stress.

BACKGROUND: Fructose intake, mainly as table sugar or high fructose corn syrup, has increased in recent decades and is associated with increased risk for kidney stones. We hypothesized that fructose intake alters serum and urinary components involved in stone formation. METHODS: We analyzed a previously published randomized controlled study that included 33 healthy male adults (40-65 years of age) who ingested 200 g of fructose (supplied in a 2-L volume of 10% fructose in water) daily for 2 weeks. Participants were evaluated at the Unit of Nephrology of the Mateo Orfila Hospital in Menorca. Changes in serum levels of magnesium, calcium, uric acid, phosphorus, vitamin D, and intact PTH levels were evaluated. Urine magnesium, calcium, uric acid, phosphorus, citrate, oxalate, sodium, potassium, as well as urinary pH, were measured. RESULTS: Ingestion of fructose was associated with an increased serum level of uric acid (p < 0.001), a decrease in serum ionized calcium (p = 0.003) with a mild increase in PTH (p < 0.05) and a drop in urinary pH (p = 0.02), an increase in urine oxalate (p = 0.016) and decrease in urinary magnesium (p = 0.003). CONCLUSIONS: Fructose appears to increase urinary stone formation in part via effects on urate metabolism and urinary pH, and also via effects on oxalate. Fructose may be a contributing factor for the development of kidney stones in subjects with metabolic syndrome and those suffering from heat stress. TRIAL REGISTRATION: ClinicalTrials.gov NCT00639756 March 20, 2008.

Metabolic and Kidney Diseases in the Setting of Climate Change, Water Shortage, and Survival Factors.

Climate change (global warming) is leading to an increase in heat extremes and coupled with increasing water shortage, provides a perfect storm for a new era of environmental crises and potentially, new diseases. We use a comparative physiologic approach to show that one of the primary mechanisms by which animals protect themselves against water shortage is to increase fat mass as a means for providing metabolic water. Strong evidence suggests that certain hormones (vasopressin), foods (fructose), and metabolic products (uric acid) function as survival signals to help reduce water loss and store fat (which also provides a source of metabolic water). These mechanisms are intricately linked with each other and stimulated by dehydration and hyperosmolarity. Although these mechanisms were protective in the setting of low sugar and low salt intake in our past, today, the combination of diets high in fructose and salty foods, increasing temperatures, and decreasing available water places these survival signals in overdrive and may be accelerating the obesity and diabetes epidemics. The recent discovery of multiple epidemics of CKD occurring in agricultural workers in hot and humid environments may represent harbingers of the detrimental consequences of the combination of climate change and overactivation of survival pathways.

Hyperfiltration and uricosuria in adolescents with type 1 diabetes.

BACKGROUND: Urine uric acid (UUA) has been implicated in the pathogenesis of diabetic nephropathy via its effect on tubular cells. We hypothesized that the UUA level would be higher in adolescents with type 1 diabetes (T1D) than in those without T1D. We also hypothesized that UUA and fractional uric acid excretion (FeUA) would be higher in adolescents with T1D and hyperfiltration [estimated glomerular filtration rate (eGFR) ≥141 mL/min/1.73 m(2)] than in those without hyperfiltration. METHODS: The UUA concentration was determined and FeUA calculated in adolescents with (n = 239) and without T1D (n = 75). The eGFR was calculated using the Zappitelli equation based on serum creatinine and cystatin C concentrations. RESULTS: Compared to the non-diabetic adolescents enrolled in the study, those with T1D had a higher eGFR (mean ± standard deviation: 120 ± 22 vs. 112 ± 16 mL/min/1.73 m(2); p = 0.0006), lower urine pH (6.2 ± 0.8 vs. 6.5 ± 1.0; p = 0.01), and higher UUA (37.7 ± 18.6 vs. 32.8 ± 18.1 mg/dL; p = 0.049) and FeUA (median [interquartile range]: 6.2 [4.3-8.7] vs. 5.2 [3.6-7.0] %; p = 0.02). Among adolescents with T1D, those with hyperfiltration had higher median FeUA (8.6 [5.2-9.9] vs. 6.0 [4.2-8.3] %; p = 0.02) than those without hyperfiltration. CONCLUSIONS: The adolescents with T1D enrolled in the study had higher eGFR, higher UUA and more acidic urine than the non-diabetic controls, which may have increased their risk of UUA crystallization. Adolescents with T1D and hyperfiltration had higher FeUA than those without hyperfiltration. These hypothesis-generating observations may suggest a potential pathophysiologic association between uricosuria and hyperfiltration.

Heat stress, dehydration, and kidney function in sugarcane cutters in El Salvador--A cross-shift study of workers at risk of Mesoamerican nephropathy.

BACKGROUND: An epidemic of progressive kidney failure afflicts sugarcane workers in Central America. Repeated high-intensity work in hot environments is a possible cause. OBJECTIVES: To assess heat stress, dehydration, biomarkers of renal function and their possible associations. A secondary aim was to evaluate the prevalence of pre-shift renal damage and possible causal factors. METHODS: Sugarcane cutters (N=189, aged 18-49 years, 168 of them male) from three regions in El Salvador were examined before and after shift. Cross-shift changes in markers of dehydration and renal function were examined and associations with temperature, work time, region, and fluid intake were assessed. Pre-shift glomerular filtration rate was estimated (eGFR) from serum creatinine. RESULTS: The mean work-time was 4 (1.4-11) hours. Mean workday temperature was 34-36 °C before noon, and 39-42 °C at noon. The mean liquid intake during work was 0.8L per hour. There were statistically significant changes across shift. The mean urine specific gravity, urine osmolality and creatinine increased, and urinary pH decreased. Serum creatinine, uric acid and urea nitrogen increased, while chloride and potassium decreased. Pre-shift serum uric acid levels were remarkably high and pre-shift eGFR was reduced (<60 mL/min) in 23 male workers (14%). CONCLUSIONS: The high prevalence of reduced eGFR, and the cross-shift changes are consistent with recurrent dehydration from strenuous work in a hot and humid environment as an important causal factor. The pathophysiology may include decreased renal blood flow, high demands on tubular reabsorption, and increased levels of uric acid.

Cardiovascular risk factors among adult patients with haemophilia.

Since the introduction of episodic and prophylactic treatments with safer factor concentrates, the life expectancy of people with haemophilia (PwH) has improved considerably. Ageing-related diseases such as cardiovascular disease (CVD) have also become more prevalent in PwH. This cross-sectional study aimed to evaluate CVD risk factors and estimate 10-year risk for CVD events among PwH. Male patients ≥ 30 years were interviewed and examined. Blood tests were performed at the local laboratory. Eighty-two patients were included, of whom 83% had haemophilia A and half had severe disease. Median age at study entry was 43.0 years (interquartile range [IQR], 36.0-51.3). Prevalence of obesity, systemic arterial hypertension (SAH) and diabetes mellitus were 16%, 60% and 16%, respectively. Hypertriglyceridaemia, hypercholesterolaemia and low HDL blood levels were present in 18%, 41% and 30% of patients, respectively. Metabolic syndrome was found in 37%. The Framingham Risk Score showed that 39% of PwH had a high risk of developing cardiovascular events in the following 10 years. We conclude that, in this cohort, PwH have a higher prevalence of SAH when compared with Brazilian men without haemophilia and about two-fifths have a high risk of developing a CVD event in the following 10 years.

Dietary fructose causes tubulointerstitial injury in the normal rat kidney.

Recent studies suggest that the metabolic syndrome is associated with renal disease. We previously reported that a high-fructose diet, but not a high-glucose diet, can induce metabolic syndrome and accelerate chronic renal disease in rats. We now examined the effects of a high-fructose diet on normal rat kidneys. Three groups of Sprague-Dawley rats were pair fed a special diet containing 60% fructose, 60% glucose, or control standard rat chow for 6 wk, and then histological studies were performed. The effect of fructose to induce cell proliferation in cultured proximal tubular cells was also performed. Fructose diet, but not glucose diet, significantly increased kidney weight by 6 wk. The primary finding was tubular hyperplasia and proliferation involving all segments of the proximal tubules while glomerular changes were not observed. This is the same site where the fructose transporters (GLUT2 and -5) as well as the key enzyme in fructose metabolism (ketohexokinase) were expressed. Consistently, fructose also induced proliferation of rat proximal tubular cells in culture. In vivo, tubular proliferation was also associated with focal tubular injury, with type III collagen deposition in the interstitium, an increase in alpha-smooth muscle actin positive myofibroblasts, and an increase in macrophage infiltration. In conclusion, a high-fructose diet induces cell proliferation and hyperplasia in proximal tubules, perhaps via a direct metabolic effect. The effect is independent of total energy intake and is associated with focal tubulointerstitial injury. These studies may provide a mechanism by which metabolic syndrome causes renal disease.

Comparison of free fructose and glucose to sucrose in the ability to cause fatty liver.

BACKGROUND: There is evidence that disaccharide sucrose produce a greater increase in serum fructose and triglycerides (TGs) than the effect produced by their equivalent monosaccharides, suggesting that long-term exposure to sucrose or fructose + glucose could potentially result in different effects. AIM OF THE STUDY: We studied the chronic effects of a combination of free fructose and glucose relative to sucrose on rat liver. METHODS: Rats were fed either a combination of 30% fructose and 30% glucose (FG) or 60% sucrose (S). Control rats were fed normal rat chow (C). All rats were pair fed and were followed for 4 months. After killing, blood chemistries and liver tissue were examined. RESULTS: Both FG-fed- and S-fed rats developed early features of metabolic syndrome when compared with C. In addition, both diets induced hepatic alterations, including variable increases in hepatic TG accumulation and fatty liver, an increase in uric acid content in the liver, as well as an increase in hepatic levels of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) measured in liver homogenates. CONCLUSIONS: Diets containing 30% of fructose either as free fructose and glucose, or as sucrose, induce metabolic syndrome, intrahepatic accumulation of uric acid and TGs, increased MCP-1 and TNF-alpha as well as fatty liver in rats. It will be relevant to determine clinically whether pharmacological reduction in uric acid levels might have a therapeutic advantage in the treatment of non-alcoholic fatty liver disease.

Demographic and clinical characteristics of pulmonary arterial hypertension caused by schistosomiasis are indistinguishable from other etiologies.

INTRODUCTION: Pulmonary arterial hypertension (PAH) is a serious pulmonary circulation disease caused by several etiologies, including schistosomiasis. The present study retrospectively evaluated the clinical and hemodynamic characteristics of patients with schistosomal PAH (PAH-Sch) compared to those of non-Sch PAH patients (non-Sch PAH). METHODS: Patients treated at the Pronto-Socorro Cardiológico de Pernambuco and diagnosed by right cardiac catheterization were divided into PAH-Sch and non-Sch PAH groups. Their socio-demographic and clinical characteristics, N-terminal-pro B-type natriuretic peptide (NT-proBNP), and echocardiography and hemodynamic parameters were retrospectively reviewed. RESULTS: Among the included 98 patients (mean age, 45 ± 14 years; 68 women [69.4%]), we found 56 PAH-Sch and 42 non-Sch PAH. The age distribution was heterogeneous in the PAH-Sch group, with patients predominantly ranging from 50-59 (p <0.004). Dyspnea was the most common symptom, reported by 92 patients (93.8%), and commonly present for over two years prior to diagnosis. Clinical symptoms were similar in both groups, with no differences in functional class, pulmonary artery systolic pressure (p = 0.102), 6-minute walk test score (p = 0.234), NT-proBNP serum levels (p = 0.081), or hemodynamic parameters. CONCLUSIONS: Patients with PAH-Sch present clinical, laboratory, and hemodynamic profiles similar to those with PAH resulting from other etiologies of poor prognosis. PAH is an important manifestation of schistosomiasis in endemic regions that is often diagnosed late.

Expression of microRNAs (133b and 138) and Correlation with Echocardiographic Parameters in Patients with Alcoholic Cardiomyopathy.

INTRODUCTION: Alcoholic Cardiomyopathy (ACM) is a disease with a difficult diagnosis. The real mechanisms related to its pathophysiology are not fully understood. OBJECTIVE: The aims of this study were to investigate whether miR-133b and miR-138 could be associated with ACM. METHODS: Forty-four patients were included comprising 24 with ACM and 20 with cardiomyopathies of different etiologies (control group). Real-time PCR was performed to verify the relative expression among the studied groups. In the statistical analysis, the quantitative variables t-student Mann- Whitney and correlation of Pearson tests were carried out, while the qualitative variable comprised the chi-square test, with p<0.05 being considered statistically significant. RESULTS: There was no association between clinical and sociodemographic characteristics of the groups. The patients with ACM presented downregulation of miR-133b in comparison with control patients (p=0.004). On the other hand, for the miR-138, there was no association when the ACM group was compared with the control group. The presence of miR-133b among cases and controls was not correlated with any of the echocardiographic parameters. However, the increase in the expression of miR-138 was correlated with an increase in the ejection fraction (r=0.28, p=0.01) and the diameter of the left atrium (r=0.23, p=0.04) in patients with ACM. CONCLUSION: The downregulation of miR-133b might be a marker for ACM and, in addition, miR- 138 could be used to correlate the increase in ejection fraction with and normalization of the diameter of the left atrium diameter in patients with this disease.

Effect of lowering uric acid on renal disease in the type 2 diabetic db/db mice.

Hyperuricemia has recently been recognized to be a risk factor for nephropathy in the diabetic subject. We tested the hypothesis that lowering uric acid with a xanthine oxidase inhibitor might reduce renal injury in the diabetic mouse. Diabetic (db/db) mice were treated with allopurinol or no treatment for 8 wk. Serum uric acid, renal function, and histology were assessed at death. The direct effect of uric acid in human proximal tubular epithelial cells was also evaluated under normal or high glucose condition. We found that db/db mice developed hyperuricemia, albuminuria, mesangial matrix expansion, and mild tubulointerstitial disease. Allopurinol treatment significantly lowered uric acid levels, reduced albuminuria, and ameliorated tubulointerstitial injury, but it did not prevent mesangial expansion. The mechanism for protection was shown to be due to a reduction in inflammatory cells mediated by a reduction in ICAM-1 expression by tubular epithelial cells. Interestingly, allopurinol did not reduce oxidative stress in the kidney. An inflammatory role of uric acid on tubular cells was also confirmed by our in vitro evidence that uric acid directly induced ICAM-1 expression in the human proximal tubular cell. In conclusion, hyperuricemia has a pathogenic role in the mild tubulointerstitial injury associated with diabetic nephropathy but not glomerular damage in db/db mice. Lowering uric acid may reduce tubulointerstitial injury in diabetes.

Combination of captopril and allopurinol retards fructose-induced metabolic syndrome.

BACKGROUND: Both ACE inhibitors and allopurinol have been shown to partially prevent metabolic syndrome induced by fructose. We tested the hypothesis that combined therapy might be more effective at blocking the metabolic syndrome induced with fructose. METHODS: Male Sprague-Dawley rats were fed a high fructose diet with or without allopurinol, captopril, or the combination for 20 weeks. A control group received a normal diet. All groups were pair-fed to assure equivalent caloric intake. RESULTS: Despite reduced energy intake, the fructose-fed rats developed features of metabolic syndrome including elevated blood pressure, abdominal obesity, hypertriglyceridemia, hyperuricemia and hyperinsulinemia. While both allopurinol and captopril alone tended to reduce features of the metabolic syndrome, the combined therapy was synergistic, with significant reduction in blood pressure, less accumulation of abdominal fat, an improvement in the dyslipidemia and a complete prevention of insulin resistance. CONCLUSION: A high fructose diet can induce metabolic syndrome even in the setting of caloric restriction. Captopril and allopurinol synergistically reduce features of the metabolic syndrome, especially hypertension, insulin resistance and dyslipidemia. Combination allopurinol and ACE inhibitor therapy might provide a superior means to prevent diabetes and cardiovascular disease.

Fructose induces the inflammatory molecule ICAM-1 in endothelial cells.

Epidemiologic studies have linked fructose intake with the metabolic syndrome, and it was recently reported that fructose induces an inflammatory response in the rat kidney. Here, we examined whether fructose directly stimulates endothelial inflammatory processes by upregulating the inflammatory molecule intercellular adhesion molecule-1 (ICAM-1). When human aortic endothelial cells were stimulated with physiologic concentrations of fructose, ICAM-1 mRNA and protein expression increased in a time- and dosage-dependent manner, which was independent of NF-kappaB activation. Fructose reduced endothelial nitric oxide (NO) levels and caused a transient reduction in endothelial NO synthase expression. The administration of an NO donor inhibited fructose-induced ICAM-1 expression, whereas blocking NO synthase enhanced it, suggesting that NO inhibits endothelial ICAM-1 expression. Furthermore, fructose resulted in decreased intracellular ATP; administration of exogenous ATP blocked fructose-induced ICAM-1 expression and increased NO levels. Consistent with the in vitro studies, dietary intake of fructose at physiologic dosages increased both serum ICAM-1 concentration and endothelial ICAM-1 expression in the rat kidney. These data suggest that fructose induces inflammatory changes in vascular cells at physiologic concentrations.

Hypokalemic nephropathy is associated with impaired angiogenesis.

Hypokalemic nephropathy is associated with alterations in intrarenal vasoactive substances, leading to vasoconstriction, salt-sensitivity, and progression of interstitial fibrosis. In this study, we investigated whether hypokalemic nephropathy might also involve impaired renal angiogenesis. Sprague-Dawley rats that were fed low-potassium diets developed peritubular capillary loss that began in the inner stripe of the outer medulla (week 2) and progressed to the outer stripe of the outer medulla (week 4) and cortex (week 12). These changes were associated with increased macrophage infiltration, increased expression of both monocyte chemoattractant protein-1 and TNF-alpha, and a loss of vascular endothelial growth factor and endothelial nitric oxide synthase. Renal thiobarbituric acid-reactive substances, markers of oxidative stress, were increased late in disease. In conclusion, hypokalemic nephropathy is associated with impaired renal angiogenesis, evidenced by progressive capillary loss, reduced endothelial cell proliferation, and loss of VEGF expression.

Serum uromodulin is associated with urinary albumin excretion in adolescents with type 1 diabetes.

Early diabetic kidney disease (DKD) occurs in adolescents with type 1 diabetes (T1D). Lower serum uromodulin (SUMOD) predicts DKD progression in adults with T1D. In this study, we demonstrate that lower SUMOD is associated with urinary albumin excretion in adolescents with T1D, suggesting a potential relationship between SUMOD and early kidney dysfunction in T1D youth.

Serum uromodulin inversely associates with aortic stiffness in youth with type 1 diabetes: A brief report from EMERALD study.

Youth with type 1 diabetes (T1D) carry greater cardiovascular disease (CVD) risk than their nondiabetic peers. Low serum uromodulin (SUMOD) associates with increased CVD mortality in adults. We found that T1D youth have low SUMOD. Lower SUMOD correlated with aortic stiffness, suggesting its potential as a CVD biomarker in T1D.