NR4A1 suppresses cisplatin-induced ferroptosis in renal proximal tubular epithelial cells by up-regulating the expression of NRF2 / 中华肾脏病杂志

Objective:To explore the role and mechanism of nuclear receptor subfamily 4 group A member 1 ( NR4A1) in suppressing cisplatin nephrotoxicity. Methods:The expression of NR4A1 gene in renal cell subpopulations was analyzed using the "Tabula-muris" single cell transcriptome sequencing database. NR4A1 gene was over-expressed by lentivirus infection in HK-2 cell line and primary renal proximal tubular epithelial cells. Cell counting kit-8 was used to detect the cytotoxicity of cisplatin. The cell death ratio was analyzed using propidium iodide (PI) staining by flow cytometry. The expression of NR4A1 and nuclear factor erythroid 2-related factor 2 ( NRF2) was detected by real-time fluorescent quantitative PCR and Western blotting. Ferroptosis was analyzed by detecting the contents of malondialdehyde (MDA), oxidized glutathione (GSSG) and lipid reactive oxygen species (ROS). Results:The single cell transcriptome sequencing database showed that NR4A1 gene was the lowest expression in renal proximal tubular epithelial cell subsets. Cisplatin (50 μmol/L or 100 μmol/L) could significantly induce MDA, GSSG and lipid ROS production in renal proximal tubular epithelial cells (all P<0.01), and higher cisplatin concentration accompanied with a more increase of MDA, GSSG and lipid ROS. Compared with the control HK-2 cells, the lipid ROS content and iron ion content of HK-2 cells over-expressing NR4A1 were significantly lower (all P<0.01), and the over-expression of NR4A1 inhibited cisplatin-induced cytotoxicity and ferroptosis in renal proximal tubular epithelial cells. Mechanistically, NR4A1 up-regulated the expression of anti-ferroptosis gene NRF2 in proximal renal tubular epithelial cells ( P<0.01). Furthermore, single cell data analysis showed that, similar to the expression of NR4A1 in renal tissue subsets, NRF2 was also the lowest in renal proximal tubular epithelial cells. Conclusions:Cisplatin can induce ferroptosis of renal proximal tubular epithelial cells in a dose-dependent manner. NR4A1 can inhibit cisplatin-induced ferroptosis by up-regulating NRF2 in renal proximal tubular epithelial cells, thereby alleviating the cytotoxicity of cisplatin.

Polymyxin Acute Kidney Injury: a case of severe tubulopathy / Nefropatia por polimixina B: a tubulopatia pode ser muito séria!

Abstract Polymyxins are antibiotics developed in the 1950s. Polymyxin-induced neurotoxicity has been often described in medical literature. The same cannot be said of nephrotoxicity or tubulopathy in particular. This report describes the case of a patient prescribed polymyxin B to treat a surgical wound infection, which led to significant increases in fractional excretion of calcium, magnesium, and potassium and subsequent persistent decreases in the levels of these ions, with serious consequences for the patient. Severe hypocalcemia, hypomagnesemia, and hypokalemia may occur during treatment with polymyxin. Calcium, magnesium and potassium serum levels must be monitored during treatment to prevent life-threatening conditions.

Resumo Polimixinas são um grupo de antibióticos desenvolvidos na década de 1950. Seus efeitos neurotóxicos são comumente descritos na literatura, porém há menos relatos sobre seus efeitos nefrotóxicos, especialmente tubulopatias. O objetivo deste relato é descrever o uso de polimixina B em uma paciente para tratamento de infecção de ferida operatória, promovendo grande aumento das frações de excreção de cálcio, magnésio e potássio e acarretando reduções graves e persistentes desses íons, com sérias consequências para a paciente. Hipocalcemia, hipomagnesemia e hipocalemia severas podem ocorrer durante terapia com polimixina e é sugerido que sejam monitorizadas as concentrações séricas desses eletrólitos durante o tratamento como forma de evitar condições de risco à vida.

Glycosuria in primary glomerulopathies: prevalence and prognostic significance / Glicosúria nas doenças glomerulares primárias: prevalência e significância prognóstica

Abstract Introduction: Tubular damage is common in glomerular diseases (GD). Glycosuria is a marker of tubular dysfunction and may be used to detect tubular lesion and CKD progression. The aim of this study was to evaluate the prevalence and prognostic value of glycosuria at the time of diagnosis in primary glomerulopathies (PG). Methods: We conducted a 24-month retrospective study in patients diagnosed with PG in our center between 2009 and 2020. We excluded diabetic patients, use of SGLT2 inhibitors, transplant patients, and secondary GD. Patients were divided in two groups according to their glycosuria status at diagnosis. Results: We studied 115 patients. Global prevalence of glycosuria was 10% (n=11) and membranous nephropathy (MN) had the highest prevalence (n=5, 17.9%). We found that patients with glycosuria had higher serum creatinine (2.4 vs. 1.2 mg/dL, p=0.030), higher albuminuria (4.8 vs. 1.9 g/g, p=0.004), and lower serum albumin (2.3 vs. 3.2 g/dL, p=0.021). We did not find association with histological prognostic factors. At the end of follow-up, patients with glycosuria had higher prevalence of the composite outcome of stage 5D CKD or 50% increase in basal SCr (45.5% vs. 17.3%, p=0.037). In patients with MN, results were similar but we were able to find an association of glycosuria with more severe interstitial fibrosis and tubular atrophy (25.0 vs. 0.0 %, p=0.032). Conclusion: Ten percent of our patients with PG have glycosuria. Glycosuria at the time of diagnosis was associated with more severe clinical presentation and worst renal outcome. The association with higher albuminuria suggests that tubular function has an impact on the severity and outcomes of PG.

Resumo Introdução: Danos tubulares são comuns em doenças glomerulares (DG). Glicosúria é um marcador de disfunção tubular e pode detectar lesão tubular e progressão da DRC. O objetivo deste estudo foi avaliar a prevalência e o valor prognóstico da glicosúria no diagnóstico em glomerulopatias primárias (GP). Métodos: Realizamos estudo retrospectivo de 24 meses em pacientes diagnosticados com GP em nosso centro entre 2009-2020. Excluímos pacientes diabéticos, uso de inibidores de SGLT2, pacientes transplantados e DG secundárias. Os pacientes dividiram-se em dois grupos de acordo com seu estado de glicosúria no diagnóstico. Resultados: Estudamos 115 pacientes. A prevalência global de glicosúria foi de 10% (n=11) e a nefropatia membranosa (NM) teve maior prevalência (n=5, 17,9%). Constatamos que pacientes com glicosúria apresentavam creatinina sérica mais elevada (2,4 vs. 1,2 mg/dL, p=0,030), albuminúria mais alta (4,8 vs. 1,9 g/g, p=0,004), e albumina sérica mais baixa (2,3 vs. 3,2 g/dL, p=0,021). Não encontramos associação com fatores prognósticos histológicos. Ao final do acompanhamento, pacientes com glicosúria tiveram maior prevalência do desfecho composto de DRC estágio 5D ou aumento de 50% na CrS basal (45,5% vs. 17,3%, p=0,037). Em pacientes com NM, os resultados foram semelhantes, mas encontramos uma associação de glicosúria com fibrose intersticial mais grave e atrofia tubular (25,0 vs. 0,0 %, p=0,032). Conclusão: 10% de nossos pacientes com GP têm glicosúria. A glicosúria no diagnóstico foi associada a uma apresentação clínica mais grave e pior desfecho renal. A associação com albuminúria mais elevada sugere que a função tubular tem um impacto na gravidade e nos desfechos da GP.

Construction of an aging model of renal tubular epithelial cells / 中华老年医学杂志

Objective:To compare aging models for renal tubular epithelial cells induced by different drugs.Methods:Different concentrations of D-galactose(D-gal), hydrogen peroxide(H 2O 2)and cisplatin(CDDP)were administered to the human proximal tubular epithelial cell line(HK2). Cell activity and the half maximal inhibitory concentration(IC50)were measured by the CCK-8 assay; cell senescence was assessed by senescence-related β-galactosidase staining(SA-β-gal); senescence-related gene expression was detected by Western blotting; cell cycle distribution and apoptosis were determined by flow cytometry.Pathological changes in renal tubules and interstitial tissues were examined in D-gal-induced and naturally aging mice using HE staining, and p16 expression was detected using immunohistochemistry. Results:CCK-8 assay results showed that HK2 cell activity was inhibited treatment with each of the three compounds.The 48-hour IC50 values were(365.8±9.7)mmol/L for D-gal, (385.4±20.8)μmol/L for H 2O 2 and(8.4±1.6)μmol/L for CDDP.Light microscopic observation revealed slowed growth of HK2 cells in the three groups.The rate of SA-β-gal-positive cells increased, compared with the control group( P<0.05). Treatment resulted in an increase in G0/G1 phase cells by(22.9±1.0)% in the 400 mmol/L D-gal group and by(13.0±4.4)% in the 400 μmol/L H 2O 2 group, while G2/M phase cells increased by(14.4±1.9)%( t=48.07, 6.40, 16.53, P<0.05)in the 8 μmol/L CDDP group, compared with the control group.Also, compared with the control group, HK2 cell apoptosis increased by(50.3±1.0)% in the 400 μmol/L H 2O 2 group and by(41.9±2.0)% in the 8 μmol/L CDDP group, which was significantly higher than(7.7±0.4)% in the 400 mmol/L D-gal group( t=77.47, 33.73, 28.35, all P<0.05). Western blotting results indicated that the expression of CCND1 was down-regulated after any of the three drugs reached a certain concentration.The expression of p16 in the D-gal group was up-regulated( F=92.88, P<0.05), but there was no statistical difference in the expression of p16 after H 2O 2 or CDDP treatment.Mice of the D-gal model showed a decline in renal tubular cells, thickened basement membrane, widened interstitial spaces and increased expression of p16 in renal tubules similar to those observed in naturally aging mice. Conclusions:For HK2 cell senescence models induced by three different drugs, the renal tubular epithelial cell senescence model induced by D-gal is relatively close to the natural senescence model.

Dynamics of Organic Anion Transporter-Mediated Tubular Secretion during Postnatal Human Kidney Development and Maturation.

BACKGROUND AND OBJECTIVES: The neonatal and juvenile human kidney can be exposed to a variety of potentially toxic drugs (e.g., nonsteroidal anti-inflammatory drugs, antibiotics, antivirals, diuretics), many of which are substrates of the kidney organic anion transporters, OAT1 (SLC22A6, originally NKT) and OAT3 (SLC22A8). Despite the immense concern about the consequences of drug toxicity in this vulnerable population, the developmental regulation of OATs in the immature postnatal kidney is poorly understood. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Recognizing that today it is difficult to obtain rich data on neonatal kidney handling of OAT probes due to technical, logistic, and ethical considerations, multiple older physiologic studies that used the prototypical organic anion substrate para-aminohippurate (PAH) were reanalyzed in order to provide a quantitative description of OAT-mediated tubular secretion across the pediatric age continuum. Parametric and semiparametric models were evaluated for kidney function outcome variables of interest (maximum tubular secretory capacity of PAH [TmPAH], effective renal plasma flow [ERPF], and GFR). RESULTS: Data from 119 neonates, infants, and children ranging in age from 1 day to 11.8 years were used to fit TmPAH, ERPF, and GFR as functions of postnatal age. TmPAH is low in the immediate postnatal period and increases markedly after birth, reaching 50% of the adult value (80 mg/min) at 8.3 years of age. During the first 2 years of life, TmPAH is lower than that of GFR when viewed as the fraction of the adult value. CONCLUSIONS: During postnatal human kidney development, proximal tubule secretory function-as measured using PAH, a surrogate for OAT-mediated secretion of organic anion drugs, metabolites, and toxins-is low initially but increases rapidly. Despite developmental differences between species, this overall pattern is roughly consistent with animal studies. The human data raise the possibility that the acquisition of tubular secretory function may not closely parallel glomerular filtration.

Effects of albumin overload on mitochondrial membrane potential and ultrastructural changes in renal tubular epithelial cells / 中华老年医学杂志

Objective To investigate effects of albumin overload on mitochondrial membrane potential and ultrastructural changes in renal tubular epithelial cells (HK-2).Methods Vitrocultured HK-2 cells were treated with different concentrations of albumin.The mitochondrial membrane potential in HK-2 cells was detected by fluorescence probe JC-1,and the electron microscopy was used to detect the mitochondrial ultrastructure of cells.Results JC-1-detected red/green ratio was 2.34 ± 0.21 at 0 g/L of albumin treatment,0.83 ± 0.09 at 4 g/L,0.41 ± 0.07 at 8 g/L,0.38± 0.08 at 16 g/L albumin overload,which showed a gradually decreased red and green fluorescence intensity ratio along with increased albumin overload(F =162.794,P ＜0.001),and with significant differences in the ratio among groups (all P ＜ 0.05).Albumin overload-induced mitochondrial abnormality in transmission electron microscope included mitochondrial swelling,disordered cristae arrangement,cristae lysis and cavitation,and the increase of bilayer membrane structures in HK-2 cells.Conclusions Albumin overload can induce the decline of mitochondrial membrane potential,mitochondrial damage and autophagy in renal tubular epithelial cells,which suggest that mitochondrial damage and autophagy may be one of the mechanisms of albumin overloadinduced renal tubular epithelial cell injury.

Perfluorinated Chemicals as Emerging Environmental Threats to Kidney Health: A Scoping Review.

BACKGROUND AND OBJECTIVES: Per- and polyfluoroalkyl substances (PFASs) are a large group of manufactured nonbiodegradable compounds. Despite increasing awareness as global pollutants, the impact of PFAS exposure on human health is not well understood, and there are growing concerns for adverse effects on kidney function. Therefore, we conducted a scoping review to summarize and identify gaps in the understanding between PFAS exposure and kidney health. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We systematically searched PubMed, EMBASE, EBSCO Global Health, World Health Organization Global Index, and Web of Science for studies published from 1990 to 2018. We included studies on the epidemiology, pharmacokinetics, or toxicology of PFAS exposure and kidney-related health, including clinical, histologic, molecular, and metabolic outcomes related to kidney disease, or outcomes related to the pharmacokinetic role of the kidneys. RESULTS: We identified 74 studies, including 21 epidemiologic, 13 pharmacokinetic, and 40 toxicological studies. Three population-based epidemiologic studies demonstrated associations between PFAS exposure and lower kidney function. Along with toxicology studies (n=10) showing tubular histologic and cellular changes from PFAS exposure, pharmacokinetic studies (n=5) demonstrated the kidneys were major routes of elimination, with active proximal tubule transport. In several studies (n=17), PFAS exposure altered several pathways linked to kidney disease, including oxidative stress pathways, peroxisome proliferators-activated receptor pathways, NF-E2-related factor 2 pathways, partial epithelial mesenchymal transition, and enhanced endothelial permeability through actin filament modeling. CONCLUSIONS: A growing body of evidence portends PFASs are emerging environmental threats to kidney health; yet several important gaps in our understanding still exist.

[A Case of Tenofovir-associated Fanconi Syndrome in Patient with Chronic Hepatitis B].

Tenofovir disoproxil fumarate (TDF) is one of the most widely used treatment options for human immunodeficiency virus (HIV) and HBV infections. Despite its efficacy and safety, some cases of nephrotoxicity have been reported in the treatment of HIV patients. Even more recently, very few cases of Fanconi syndrome associated with tenofovir therapy in HBV monoinfection have been reported. Herein, we report a case of a 47-year-old male with an HBV monoinfection, who developed Fanconi syndrome and a secondary osteomalacia with multiple bone pain. After TDF withdrawal and supplementation of calcitriol, his renal function was reverted. Although the overall risk of TDF-associated nephrotoxicity is very low, both glomerular and tubular function should be monitored in patients undergoing TDF treatment.

Transcriptional regulation of renal dopamine D1 receptor function during oxidative stress.

There exists a strong link between oxidative stress, renal dopaminergic system, and hypertension. It is reported that reactive oxygen species attenuate renal proximal tubular dopamine receptor (D1R) function, which disrupts sodium regulation and leads to hypertension. However, the mechanisms for renal D1R dysfunction are not clear. We investigated the role of redox-sensitive transcription factors AP1 and SP3 in transcriptional suppression of D1R gene and subsequent D1R signaling. Human kidney proximal tubular cells were treated with a pro-oxidant l-buthionine sulfoximine (BSO) with and without an antioxidant tempol. In human kidney cells, BSO caused oxidative stress and reduced D1R mRNA and membrane receptor expression. Incubation of human kidney cells with SKF38393, a D1R agonist, caused a concentration-dependent inhibition of Na/K-ATPase. However, SKF38393 failed to inhibit Na/K-ATPase in BSO-treated cells. BSO increased AP1 and SP3 nuclear expression. Transfection with AP1- or SP3-specific siRNA abolished BSO-induced D1R downregulation. Treatment of rats with BSO for 4 weeks increased oxidative stress and SP3-AP1 expression and reduced D1R numbers in renal proximal tubules. These rats exhibited high blood pressure, and SKF38393 failed to inhibit proximal tubular Na/K-ATPase activity. Control rats were kept on tap water. Tempol per se had no effect on D1R expression or other signaling molecules but prevented BSO-induced oxidative stress, SP3-AP1 upregulation, and D1R dysfunction in both human kidney cells and rats. These data show that oxidative stress via AP1-SP3 activation suppresses D1R transcription and function. Tempol mitigates oxidative stress, blocks AP1-SP3 activation, and prevents D1R dysfunction and hypertension.

A pan caspase inhibitor decreases caspase-1, IL-1α and IL-1ß, and protects against necrosis of cisplatin-treated freshly isolated proximal tubules.

Caspase-1, IL-1α, and IL-1ß are known to be activated in the NLRP3 inflammasome. The inflammasome is activated mostly in inflammatory cells. The presence of inflammasome proteins in proximal tubules (PTs) and the effect of cisplatin-treatment or caspase inhibition on inflammasome proteins in PTs are not known. The aim of this study was to investigate the effect of cisplatin on inflammasome proteins in freshly isolated PTs and also to determine the effect of caspase inhibition on inflammasome proteins and PT injury. PTs were isolated using collagenase digestion and Percoll centrifugation. After recovery period, freshly isolated PTs were incubated with vehicle, 50 µM cisplatin or 50 µM cisplatin plus 50 µM pan caspase inhibitor, QVD-OPH. PTs treated with 50 µM cisplatin showed Propidium Iodide staining indicative of necrosis. Necrotic cells (%) were 2.2 in Vehicle-treated, 37.7 in Cisplatin-treated (p < 0.05 vs. Vehicle), and 3.3 in QVD-treated (p < 0.05 vs. Cisplatin). LDH release (%), a marker of cell membrane damage seen in necrosis was 7.1 in Vehicle-treated, 39.7 in Cisplatin-treated (p < 0.05 vs. Vehicle), and 13.5 in QVD-treated (p < 0.05 vs. Cisplatin). Caspase-1 activity and active caspase-1 protein (10 kDa) were significantly increased in Cisplatin-treated PTs. NLRP3 was strongly expressed in PTs, but there were no significant changes between groups. Pro-apoptotic BID (22 kDa) was unchanged between groups. IL-1α and IL-1ß activity was increased in Cisplatin-treated PTs. QVD-OPH co-treatment decreased caspase-1, IL-1α, and IL-1ß. In summary, caspase inhibition decreases caspase-1, IL-1α, and IL-1ß but not NLRP3 or BID protein and protects against necrosis in cisplatin-treated freshly isolated PTs.

The expression profile of Wnt4 in rat kidney during renal development / 天津医药

Objective To explore the expression profile of Wnt4 in rat kidney during renal development and its effect on renal development. Methods Rats with embryonic age of 18 days (E 18 d) , 20 days (E 20 d) as well as postnatal age of 0 day (P 0 d), 1 day (P 1 d), 3 days (P 3 d), 5 days (P 5 d) and 7 days (P 7 d) were selected. Expression levels of Wnt4 in rat kidney during renal development were quantified by immunohistochemistry and Western blot in all time points. Results Immuno?histochemistry analysis showed that during E 18 d to P 7 d, Wnt4 mainly expressed in proximal tubules, ureteric bud, comma shaped bodies and S shaped bodies of nephrogenic zone;the expression in the distal tubule was weak;the expression in renal corpuscle decreased with time;Western blot analysis showed that the expression of Wnt4 in rat kidney began to decrease from E 18 d and reached bottom at P 1 d then rise again until P 7 d when it dropped again. Conclusion During renal development, Wnt4 proteins were involved in the development of the nephrogenic zone through regulating canonical Wnt/β-catenin signaling pathway, and was involved in extension of proximal tubules by inducing the non canonical Wnt/PCP signaling pathway. Expression of Wnt4 protein in rat kidney was closely related to nephron formation and development of proximal tubules.

AT2 receptor activation induces natriuresis and lowers blood pressure.

RATIONALE: Compound 21 (C-21) is a highly selective nonpeptide AT2 receptor (AT2R) agonist. OBJECTIVE: To test the hypothesis that renal proximal tubule AT2Rs induce natriuresis and lower blood pressure in Sprague-Dawley rats and mice. METHODS AND RESULTS: In rats, AT2R activation with intravenous C-21 increased urinary sodium excretion by 10-fold (P<0.0001); this natriuresis was abolished by direct renal interstitial infusion of specific AT2R antagonist PD-123319. C-21 increased fractional excretion of Na(+) (P<0.05) and lithium (P<0.01) without altering renal hemodynamic function. AT2R activation increased renal proximal tubule cell apical membrane AT2R protein (P<0.001) without changing total AT2R expression and internalized/inactivated Na(+)-H(+) exchanger-3 and Na(+)/K(+)ATPase. C-21-induced natriuresis was accompanied by an increase in renal interstitial cGMP (P<0.01); C-21-induced increases in urinary sodium excretion and renal interstitial cGMP were abolished by renal interstitial nitric oxide synthase inhibitor l-N(6)-nitroarginine methyl ester or bradykinin B2 receptor antagonist icatibant. Renal AT2R activation with C-21 prevented Na(+) retention and lowered blood pressure in the angiotensin II infusion model of experimental hypertension. CONCLUSIONS: AT2R activation initiates its translocation to the renal proximal tubule cell apical membrane and the internalization of Na(+)-H(+) exchanger-3 and Na(+)/K(+)ATPase, inducing natriuresis in a bradykinin-nitric oxide-cGMP-dependent manner. Intrarenal AT2R activation prevents Na(+) retention and lowers blood pressure in angiotensin II-dependent hypertension. AT2R activation holds promise as a renal proximal tubule natriuretic/diuretic target for the treatment of fluid-retaining states and hypertension.

Gastrin and D1 dopamine receptor interact to induce natriuresis and diuresis.

Oral NaCl produces a greater natriuresis and diuresis than the intravenous infusion of the same amount of NaCl. Gastrin is the major gastrointestinal hormone taken up by renal proximal tubule (RPT) cells. We hypothesized that renal gastrin and dopamine receptors interact to synergistically increase sodium excretion, an impaired interaction of which may be involved in the pathogenesis of hypertension. In Wistar-Kyoto rats, infusion of gastrin induced natriuresis and diuresis, which was abrogated in the presence of a gastrin (cholecystokinin B receptor [CCKBR]; CI-988) or a D1-like receptor antagonist (SCH23390). Similarly, the natriuretic and diuretic effects of fenoldopam, a D1-like receptor agonist, were blocked by SCH23390, as well as by CI-988. However, the natriuretic effects of gastrin and fenoldopam were not observed in spontaneously hypertensive rats. The gastrin/D1-like receptor interaction was also confirmed in RPT cells. In RPT cells from Wistar-Kyoto but not spontaneously hypertensive rats, stimulation of either D1-like receptor or gastrin receptor inhibited Na(+)-K(+)-ATPase activity, an effect that was blocked in the presence of SCH23390 or CI-988. In RPT cells from Wistar-Kyoto and spontaneously hypertensive rats, CCKBR and D1 receptor coimmunoprecipitated, which was increased after stimulation of either D1 receptor or CCKBR in RPT cells from Wistar-Kyoto rats; stimulation of one receptor increased the RPT cell membrane expression of the other receptor, effects that were not observed in spontaneously hypertensive rats. These data suggest that there is a synergism between CCKBR and D1-like receptors to increase sodium excretion. An aberrant interaction between the renal CCK BR and D1-like receptors (eg, D1 receptor) may play a role in the pathogenesis of hypertension.

Amelioration of angiotensin II-induced salt-sensitive hypertension by liver-type fatty acid-binding protein in proximal tubules.

Inappropriate activation of the intrarenal renin-angiotensin system induces generation of reactive oxygen species and tubulointerstitial inflammation, which contribute to salt-sensitive hypertension (SSHT). Liver-type fatty acid-binding protein is expressed in proximal tubules in humans, but not in rodents, and may play an endogenous antioxidative role. The objective of the present study was to examine the antioxidative effect of liver-type fatty acid-binding protein on post-angiotensin II SSHT model in transgenic mice with selective overexpression of human liver-type fatty acid-binding protein in the proximal tubules. The transgenic mice showed marked protection against angiotensin II-induced SSHT. Overexpression of tubular liver-type fatty acid-binding protein prevented intrarenal T-cell infiltration and also reduced reactive oxygen species generation, intrarenal renin-angiotensin system activation, and monocyte chemotactic protein-1 expression. We also performed an in vitro study using the murine proximal tubular cell lines with or without recombinant liver-type fatty acid-binding protein and murine proximal tubular cell lines transfected with human liver-type fatty acid-binding protein, and found that gene transfection of liver-type fatty acid-binding protein and, in part, recombinant liver-type fatty acid-binding protein administration had significantly attenuated angiotensin II-induced reactive oxygen species generation and the expression of angiotensinogen and monocyte chemotactic protein-1 in murine proximal tubular cell lines. These findings indicated that liver-type fatty acid-binding protein in the proximal tubules may protect against angiotensin II-induced SSHT by attenuating activation of the intrarenal renin-angiotensin system and reducing oxidative stress and tubulointerstitial inflammation. Present data suggest that liver-type fatty acid-binding protein in the proximal tubules may be a novel therapeutic target for SSHT.

Blood pressure in relation to interactions between sodium dietary intake and renal handling.

There is abundant evidence that sodium intake is related to blood pressure. However, the relationship varies between individuals and is probably determined by renal sodium handling. We investigated clinic and ambulatory blood pressure in relation to interactions between sodium dietary intake and renal handling, as assessed by 24-hour urinary sodium excretion and endogenous lithium clearance, respectively. We calculated fractional excretion of lithium and fractional distal reabsorption rate of sodium, as markers of proximal and distal sodium handling, respectively. The 766 subjects included 379 men and 478 ambulatory hypertensive patients. They were never treated (n=697) or did not take antihypertensive medication for ≥2 weeks (n=69). In adjusted analyses, none of the associations of urinary sodium excretion, fractional excretion of lithium, and fractional distal reabsorption rate of sodium with clinic or ambulatory blood pressure were statistically significant (P≥0.09). However, there was significant (P=0.01) interaction between urinary sodium excretion and fractional excretion of lithium in relation to nighttime diastolic blood pressure. In tertile 3 but not tertiles 1 and 2 of fractional excretion of lithium, nighttime diastolic pressure was positively associated with urinary sodium excretion (P=0.03). However, nighttime diastolic pressure was higher in tertile 1 than tertile 3 of fractional excretion of lithium (+2.0 mm Hg; P=0.01), especially in the bottom tertile of urinary sodium excretion (+4.9 mm Hg; P<0.001). Similar trends were observed for nighttime systolic pressure and clinic and 24-hour diastolic pressure. In conclusion, sodium dietary intake and proximal tubular handling interact to be associated with blood pressure.

Evaluation urinary trehalase in patients with renal proximal tubular damage / 中华检验医学杂志

Objective To investigate the value of urinary trehalase (T) in patients with renal proximal tubular damage.Methods 134 patients with kidney disease (male:66 female:68 age:18-59 ; 31cases with acute renal failure,30 cases with chronic renal failure,20 cases with drug-induced renal impairment,21 cases with renal transplantation and 32 cases with nephritic syndrome) and 101 healthy controls (58 males and 43 females) were selected.Urinary T,N-acetyl-D-glucosaminidase (NAG),β2-MG,gamma-glutamyl transferase (GGT) were detected.Data were analyzed by SPSS 11.5,including nonparametric rank test,ROC analysis.Results The level of urinary trehalase in control group was normally distributed (7.1 ± 4.1) μmol/h · g Cr (0-25 μmol/h · g Cr).There was no significant difference between men and women (t =0.63,P =0.53).Urinary T levels were significant higher in all kidney disease groups than in control group (Z =6.80,5.90,5.23,6.00,8.04,P ＜0.01).According to ROC curve,the area of urinary T under the ROC curve (AUC) in 134 patients was 0.9,significantly different with NAG,β2-MG,GGT area (P ＜ 0.01),the AUCs of T were 0.94,0.85,0.90,0.90,0.91 in acute and chronic renal failure group,drug-induced renal impairment group,renal transplantation group and nephritic syndrome group,respectively; Youden index were 0.85,0.65,0.77,0.66,0.72 respectively.Corresponding to the Youden index,sensitivity and specificity were 90.3％ and 95.1％,73.3％ and 92.1％,85.0％ and 92.1％,81.0％ and 85.2％,87.5％ and 84.2％ respectively.Conclusions The Urinary trehalase is better than other markers in the diagnosis of the proximal renal tubular damage.It was better to evaluate the proximal tubular function early in time.The diagnostic value of urinary trehalase played a key role in diagnosis,treatment and prognosis of kidney diseases.

Increased Expression of Heat Shock Protein 72 Protects Renal Proximal Tubular Cells from Gentamicin-induced Injury

The nephrotoxicity of gentamicin (GM) has been widely recognized. Heat shock protein 72 (HSP72) has been reported to be a cytoprotectant. However, its cytoprotective effect against GM induced kidney injury has not yet been studied. In this study, we investigated the cytoprotective effect of HSP72 on GM-induced nephrotoxicity in vitro. Human Kidney tubular cell line, HK-2 cells were divided into four groups: control group, GM group (cells incubated with GM only), heat shock (HS) group (cells incubated at 43 degrees C for 30 min), and GM plus HS group, respectively. Lactate dehydrogenanse (LDH) release increased time-dependently from 24 hr to 96 hr compared to the data of cells treated with GM only. Results of NAG activities, superoxide dismutase (SOD) activities and malondialdehyde (MDA) content were similar to that of the LDH release. The amount of HSP72 positive cells increased significartly at 72 hr after cells were treated with GM only. Both HSP72 protein and gene expression increased significantly at 72 hr when cells were treated with GM. On the other hand, HS induced HSP72 expression markedly. Pretreatment of HS inhibited HK-2 cells from GM-induced injury. It could reduce LDH release and NAG activity. HS also increased SOD activity, and decreased MDA content when cells were damaged by GM. These findings suggested that HS may protect kidney cells from GM-induced injury. Pre-induction of HSP72 may provide therapeutic strategies for nephrotoxicity induced by GM.

Expression of SGK isoforms in human proximal tubular epithelial cells under the condition of high glucose concentration / 中国病理生理杂志

AIM: To investigate the effect of high glucose concentration on serum and glucocorticoid induced protein kinase (SGK) mRNA and protein expressions in human proximal tubular epithelial cells (HKC) and the possible role of SGK in the production of extracellular matrix (ECM) of HKC under the condition of high glucose. METHODS: HKC was divided into 3 groups: control glucose group (CG group, 5 5 mmol/L D-glucose); high glucose group (HG group, 25 mmol/L D-glucose) and osmotic control group (MG group, 19 5 mmol/L mannitol and 5 5 mmol/L D-glucose). The expressions of SGK mRNA and protein were assessed by semi-quantitative RT-PCR and Western blotting respectively. The level of secretary and cytoplasmic fibronectin (FN) were detected by enzyme-linked immunoabsordent assay (ELISA) and indirect-immunofluorescence. RESULTS: HKC expressed SGK1, SGK2 and SGK3 at mRNA and protein levels. Their mRNA level were up-regulated since 2 hours after cells exposed to D-glucose and this up-regulation persisted to the end of 8th hour, and SGK1 protein level elevated simultaneously. On the other hand, the increased FN secretion by high glucose was in a time-dependent manner and its improved secretion threshold was just followed by the high expression of SGK1. CONCLUSIONS: In response to high glucose, the expression of SGK1, SGK2 and SGK3 in human proximal tubular epithelial cells were up-regulated which was accompanied with FN accumulation. The high expression of SGK may mediate overproduction of ECM in proximal tubular epithelial cells and contribute to the diabetic nephropathy.