Glyoxylate induces renal tubular cell injury and microstructural changes in experimental mouse

Crystal formation in mice could not be induced either by the administration of ethylene glycol or by glycolate. To clarify the reasons for the difference among these oxalate precursors in mice, we studied renal tubular epithelial injury by immunohistochemical staining of oxidative stress and observing microstructures. Daily intra-abdominal injection of saline solution [10 ml/(kg day)], ethylene glycol[(48.3 mmol/(kg day)], glycolate [1.31 mmol/(kg day)], and glyoxylate [1.35 mmol/(kg day)] into C57BL/6 male mice (8 weeks) was performed for 7 days. Immunohistochemical staining of superoxide dismutase (SOD) and malondialdehyde (MDA), and transmission electron microscopy (TEM) of renal tubular epithelial cells were performed to observe oxidative stress and morphological changes, respectively. Decreased SOD and increased MDA were shown only in glyoxylate-treated mouse kidneys. The TEM study with glyoxylate-treated mouse kidneys demonstrated that the internal structure of mitochondria in renal tubular cells underwent destruction and vacuolization, and microvilli density decreased. These changes in renal tubular cells were located in the crystal-forming area. However, such changes were not detected in the other groups. Each precursor of oxalate induces different changes in renal epithelial cells regarding oxidative stress and the microstructural changes. It is suggested that calcium oxalate crystal formation requires cell injury and morphological changes of renal epithelial tubular cells induced by glyoxylate administration in the mouse kidney.     

Role of osteopontin in early phase of renal crystal formation: immunohistochemical and microstructural comparisons with osteopontin knock-out mice

Osteopontin (OPN) is an important matrix protein of renal calcium stone. However, the function of OPN in the early phase of renal crystal formation is not well defined. In this study, we examined OPN expression in the early phase of renal crystal formation with ultra-microstructural observations and immuno-TEM (transmission electron microscopy) in control and OPN knock-out (OPN-KO) mice. Glyoxylate (100 mg/kg) was intra-abdominally administered to male wild-type mice (C57BL/6, 8 weeks of age) and OPN-KO mice (C57BL/6, 8 weeks of age). Kidney was collected before and 6, 12, and 24 h after administration. We examined the relation between renal crystal formation and microstructural OPN location using TEM and immunohistochemical staining of OPN as well as western blotting and quantitative RT-PCR for OPN. OPN protein expression gradually increased in the renal cortex-medulla junction after glyoxylate administration, and OPN mRNA was increased until 12 h, but decreased at 24 h. In ultra-microstructural observation, OPN began to appear on the luminal side of renal distal tubular cells at 6 h and was gradually detected in the tubular lumen at 12 h. OPN was present in the crystal nuclei and collapsed mitochondria in the tubular lumen. In the OPN-KO mice, collapsed mitochondria were present, but no crystal nuclei formation were detected at 24 h. Based on the results this study proposed that the appearance of organelles, such as mitochondria and microvilli, in the tubular lumen after cell injury may be the starting point of crystal nucleus formation due to the aggregation ability of OPN.     

Crucial role of the cryptic epitope SLAYGLR within osteopontin in renal crystal formation of mice

Osteopontin plays a crucial role in the formation of renal calcium crystals, which are primarily induced by renal tubular cell injury, especially mitochondrial damage. We have previously shown that the impaired Arg-Gly-Asp (RGD) sequence of osteopontin inhibits renal crystal formation by using OPN-transgenic mice and OPN-knockout (OPN-KO) mice. Here, we investigated the effects of an antimurine osteopontin antibody (35B6-Ab) that specifically reacts with the (162) SLAYGLR(168) sequence, which is exposed by thrombin cleavage and is located adjacent to the RGD sequence, on renal crystal formation. Renal crystals induced by daily administration of glyoxylate over 9 days (from days 1 to 9) in a murine model were sporadically detected in the renal tubular cells at the corticomedullary junction, where thrombin-cleaved osteopontin expression was also coincidentally detected. On days 0, 3, 6, and 9, 35B6-Ab administration inhibited renal crystal formation and induced significant morphological changes in a dose-dependent manner (250, 500, and 1000 μg per mouse). Scanning electron microscopy showed that the crystals in 35B6-Ab-treated mice were aberrantly formed and their density was low; in contrast, the crystals in untreated mice that were not administered 35B6-Ab had a radial pattern of growth (rosette petal-like crystals), and their density was high. Microstructure analysis of renal tubular cells by transmission electron microscopy revealed that untreated mice showed collapsed mitochondria in the flattened cytoplasm of renal tubular cells, unlike the corresponding structures in 35B6-Ab-treated mice, in which renal tubular cell injury was inhibited. In vitro, 35B6-Ab was found to inhibit the attachment of (14) C-labeled crystals to renal tubular culture cells and reduce morphological damage to these cells. We conclude that thrombin-cleaved osteopontin plays an important role in formation of renal calcium crystals and that 35B6-Ab contributes to the remarkable inhibition of early-stage renal crystal formation by preventing renal tubular cell injury and crystal-cell attachment.     

丹参多酚酸盐对实验性小鼠草酸钙结晶生成的影响

目的 观察中药丹参多酚酸盐对小鼠肾脏草酸钙结晶生成的干预效果,并探讨其可能的作用机制.方法 24只8周龄雄性C56BL/6小鼠根据丹参多酚酸盐干预与否以及干预浓度（80mg/kg、160 mg/kg）进行分组,每组8只.各组小鼠均给予腹腔注射乙醛酸盐（100 mg/kg）造模,丹参多酚酸盐干预组在乙醛酸盐诱导结晶肾损伤基础上加用不同浓度的丹参多酚酸盐注射液,均为1次/d,连续给药7d后,收集肾脏组织标本.光镜下观察各组小鼠肾组织中草酸钙结晶生成情况;检测肾组织中钙含量、脂质过氧化丙二醛（malondialdehyde,MDA）、谷胱甘肽（glutathione,GSH）、过氧化氢酶（catalase,CAT）及超氧化物歧化酶（superoxide dismutase,SOD）活性.结果 与模型组相比,给予丹参多酚酸盐注射液后的小鼠肾组织SOD、GSH和CAT显著升高,而MDA和肾组织钙含量显著下降（P＜0.05）,但丹参多酚酸盐两种浓度间未见明显的量效关系.结论 丹参多酚酸盐能有效的抑制由乙醛酸盐诱导的小鼠草酸钙结晶的生成.     

草酸钙结晶肾损伤模型小鼠肾小管上皮细胞转分化的实验研究

目的:研究乙醛酸盐诱导所致草酸钙结晶肾损伤模型小鼠中肾小管上皮细胞转分化的发生情况。方法:选择C57BL/6J小鼠连续腹腔注射乙醛酸盐建立草酸钙结晶肾损伤模型,应用HE染色及冯库萨染色分别观察肾组织结构变化及钙盐沉积情况,并应用免疫荧光双染、Western-blot观察肾小管上皮细胞间充质转分化(epithelial mesenchymal transtion,EMT)的情况。结果:随着连续腹腔注射乙醛酸盐时间的延长,小鼠肾组织HE染色结果显示,近端肾小管管腔逐渐扩张,且肾小管上皮细胞逐渐出现肿胀及变形,基底膜逐渐裸露;冯库萨染色结果显示近端小管腔内黑色钙盐沉积逐渐增加;免疫荧光双染、Western blot结果均显示肾小管上皮标志E-cadherin及Pan-ck逐渐丢失,而间质标志α-SMA及Vimentin的表达则逐渐增加,Western blot检测结果显示随着乙醛酸盐干预的增强,Rho相关卷曲螺旋形成蛋白激酶(rho associated coiled coil forming protein kinase,ROCKI)表达也逐渐增加,且在干预第3天即达高峰。结论:乙醛酸盐诱导所致草酸钙结晶肾损伤模型早期即出现EMT,启动了肾间质纤维化的进程。     

Renal tubular alteration by crystalluria in stone disease-an experimental study by means of MDCK cells

OBJECTIVES: Physicochemical properties of urine do not explain the formation of urinary stones. Clinical findings and results of animal experiments suggest that alteration to the renal tubular cell plays a key role in the initiation of urinary stone formation. It is not clear whether this is a primarily intracellular alteration of metabolic origin which, after lysis of the renal tubular cell in the lumen, presents a nucleus for the formation of concretions, or whether in the lumen it is tubular cell damage induced by crystalluria that triggers the formation of urinary stones. MATERIALS AND METHOD: Using Madin-Darby canine kidney cells, the influence of crystalluria on the renal tubular cell was tested in cell cultures. The influence of parathyroid hormone, vitamin D(3), oxalate and calcium concentrations and the extent to which these processes can be inhibited by allopurinol and selenium were investigated. RESULTS: Calcium oxalate monohydrate crystals produced reproducible damage to the renal tubular cell which was independent of parathyroid hormone and vitamin D(3). The crystalluria-induced effects were unrelated to the oxalate and calcium concentration or the pH. Allopurinol and selenium were able to inhibit the processes. CONCLUSION: The results indicate secondary involvement of the renal tubular cell in lithogenesis as a result of luminal alteration caused by calcium oxalate crystals. Mechanical damage and interaction between crystal and tubular cell lead to the apposition of crystals. The nephroprotective effect of allopurinol and selenium as antioxidants might explain the benefit of allopurinol found clinically in terms of stone metaphylaxis.     

Effects of Pomegranate Juice on Hyperoxaluria-Induced Oxidative Stress in the Rat Kidneys

To evaluate the role of the inducible nitric oxide synthase (iNOS), selective nuclear factor-kB (NF-kB), and p38-mitogene-activated protein kinase (p38-MAPK) on hyperoxaluria-induced oxidative stress and stone formation in rat kidneys. The rats were divided into five groups: group 1, control group; group 2: ethylene glycol (EG) group; group 3: EG?+?pomegranate juice (PJ)-low group; group 4: EG?+?PJ-middle group; group 5: EG?+?PJ-high group. Rats were sacrificed on 7, 15, and 45 days. The iNOS expression, p65-NF-kB and p38-MAPK activity, and oxidative stress markers were evaluated in the kidney. Crystal depositions were evident on day 7, and mild and severe crystallization were observed on day 15 and 45 in EG group, respectively. There was limited or no crystal formation in rats in both middle- and high-dose PJ groups when compared to low-dose PJ group. Crystal depositions, iNOS, p38-MAPK and p65-NF-kB activity, and oxidative stress markers were found to be decreased by middle- and high-dose PJ treatment. PJ was found to have inhibitory effects on renal tubular cell injury and oxidative stress caused by oxalate crystals by reducing ROS, iNOS, p38-MAPK, and NF-kB expression.     

Lipid peroxidation is not the underlying cause of renal injury in hyperoxaluric rats

BACKGROUND: Hyperoxaluria is a major risk factor of calcium oxalate stone disease and renal injury is thought to be a significant initiating event. However, the relationship among oxidative stress, renal tubule injury and hyperoxaluria in the progression of nephrolithiasis is unclear, especially in animal models. In the current study, we assess the role of oxidative stress in renal tubular damage in a rat model of chronic hyperoxaluria (HYP) and chronic renal failure induced by hyperoxaluria (HRF) compared to control rats. METHODS: Urinary excretion of renal tubular enzymes, including lactate dehydrogenase (LDH), alkaline phosphatase (AP), N-acetyl-beta-D-glucosaminidase (NAG), and alpha- and mu-glutathione-S-transferase (alpha-GST and mu-GST, respectively) was quantified in four groups of Sprague-Dawley rats. The study included normal controls, those made hyperoxaluric with ethylene glycol administration (HYP), unilateral nephrectomized controls, and unilateral nephrectomized rats administered ethylene glycol (HRF). Levels of catalase, superoxide dismutase (SOD), glutathione peroxidase (GP), and glutathione transferase (GST) in the renal cortex were measured after 4 weeks and lipid peroxidation was assessed by measuring 8-isoprostane in the urine and lipid hydroperoxide in the renal cortex. RESULTS: Urinary excretion of NAG, AP, and LDH was elevated after 2 and 4 weeks in the HYP and HRF groups. Urinary levels of mu-GST, a marker of distal tubule damage, were elevated in HRF rats after 4 weeks. alpha-GST levels were similar between control and HYP rats but were lower in HRF rats. Levels of catalase, SOD, GP, and GST in the renal cortex were similar among control, HYP, and unilateral nephrectomized control rats, but were attenuated in the HRF rats after 4 weeks. Renal cortical content of lipid hydroperoxide and urinary 8-isoprostane levels were similar among all groups after 4 weeks. CONCLUSION: Ethylene glycol-induced hyperoxaluria in Sprague-Dawley rats is accompanied by enzymuria, which is suggestive of renal tubular damage. The antioxidant capacity of the renal cortex in HYP rats is similar to that of control rats after 4 weeks of treatment; however, this capacity is significantly attenuated in rats that are in renal failure induced by hyperoxaluria, although significant lipid peroxidation is not evident. These results suggest that lipid peroxidation is not the underlying cause of renal injury in hyperoxaluric rats.     

Risk of renal stone formation induced by long-term bed rest could be decreased by premedication with bisphosphonate and increased by resistive exercise

Objectives:   To clarify the influence of long-term bed rest on renal stone formation and to analyze the mechanism of bed-rest-induced stone formation and prevention by bisphosphonate and bed-rest exercise.
Methods:   Twenty-five men aged 26–48 years and divided into control (CON: n  = 9), exercise (EX: n  = 9), and pamidronate (PMD: n  = 7) groups, rested on a 6° head-down tilt bed for 90 days. The exercise group carried out resistive exercise every 3 days. Pamidronate (60 mg) was intravenously given 2 weeks before the initiation of bed rest. Abdominal X-ray examination and urine biochemistry were carried out during 90 days of bed rest and 90 days of reloading.
Results:   Renal stone formation was observed in two (22.2%) and four (44.4%) subjects in the control and exercise groups, respectively. No stone was seen in the pamidronate group. In the exercise group, urinary oxalate and phosphate excretion were significantly higher than in the control group. In the pamidronate group, urinary calcium excretion and relative supersaturation of calcium oxalate and brushite were lower than in the control group throughout the bed-rest and recovery period.
Conclusion:   Long-term bed-rest-induced renal stone formation was found to be induced by increased urinary calcium and subsequent crystal formation of calcium oxalate and calcium phosphate. Exercise during bed rest for the prevention of bone mineral loss and contracture might increase the risk of renal stone formation. Pamidronate is useful for the prevention of renal stone formation during and after bed rest.     

Taurine protected kidney from oxidative injury through mitochondrial-linked pathway in a rat model of nephrolithiasis

Hyperoxaluria and crystal deposition induce oxidative stress (OS) and renal epithelial cells injury, both mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase are considered as the main sources of reactive oxygen species (ROS). Taurine is known to have antioxidant activity and shows renoprotective effect. We investigate the effect of taurine treatment on renal protection, and the putative source of ROS, in a rat model of calcium oxalate nephrolithiasis. Rats were administered with 2.5% (V/V) ethylene glycol + 2.5% (W/V) ammonium chloride (4 ml/day), with restriction on intake of drinking water (20 ml/day) for 4 weeks. Simultaneous treatment with taurine (2% W/W, mixed with the chow) was performed. At the end of the study, indexes of OS and renal injury were assessed. Renal tubular ultrastructure changes were analyzed under transmission electron microscopy. Crystal deposition in kidney was scored under light microscopy. Angiotensin II in kidney homogenates was determined by radioimmunoassay. Expression of NADPH oxidase subunits p47phox and Nox-4 mRNAs in kidney was evaluated by real time-polymerase chain reaction. The data showed that oxidative injury of the kidney occurred in nephrolithiasis-induced rats. Hyperplasia of mitochondria developed in renal tubular epithelium. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in mitochondria decreased and the mitochondrial membrane showed oxidative injury. Taurine treatment alleviated the oxidative injury of the kidney, improved SOD and GSH-Px activities, as well as the mitochondrial membrane injury, with lesser crystal depositions in the kidney. We could not detect statistical changes in the renal angiotensin II level, and the renal p47phox and Nox-4 mRNAs expression in those rats. The results suggest that mitochondria but not NADPH oxidase may account for the OS and taurine protected kidney from oxidative injury through mitochondrial-linked pathway in this rat model.     

Renal tubular injury induced by hyperoxaluria: evaluation of apoptotic changes

In order to evaluate the injurious effect of hyperoxaluria on renal tubular epithelium, as judged by apoptotic changes in the renal parenchyma, we performed an experimental study in 20 rabbits. In the experimental group animals (n=10) severe hyperoxaluria was induced by continuous ethylene glycol (EG; 0.75%). Histologic alterations, including crystal formation, together with apoptotic changes were evaluated after 7 and 28 days. Control group animals (n=10) received normal distilled drinking water. Following 7- and 28-day periods, tissue sections obtained from kidneys were examined histopathologically under light microscopy for the presence and the degree of crystal deposition in the tubular lumen. Apoptotic changes in renal tubular cells were examined using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP in situ nick and labeling (TUNEL) method during the same follow-up period. Crystal deposition was evident in the tubular lumen of tissue sections obtained during the 7-day examination period. During the 28-day examination period, however, these findings were found to be either limited or to have disappeared. In relation to apoptotic changes, the percentage of positive nuclei stained using the TUNEL method was from 11 to 20% in the experimental group and 5.6% in the control group. Our findings indicate that both calcium oxalate (CaOx) crystals and hyperoxaluria itself may be injurious to renal tubular cells, as indicated by apoptotic changes. These changes may be responsible for the pathologic course of urolithiasis. Received: 28 March 2000 / Accepted: 11 September 2000     

Experimentally induced hyperoxaluria in MCP-1 null mice

Experimental animal model studies suggest that calcium oxalate (CaOx) crystal deposition in the kidneys is associated with the development of oxidative stress, epithelial injury and inflammation. There is increased production of inflammatory molecules including osteopontin (OPN), monocyte chemoattractant protein-1 (MCP-1) and various subunits of inter-alpha-inhibitor such as bikunin. What does the increased production of such molecules suggest? Is it a cause or consequence of crystal deposition? We hypothesized that over-expression and increased production of MCP-1 is a result of the interaction between renal epithelial cells and CaOx crystals after their deposition in the renal tubules. We induced hyperoxaluria in MCP-1 null as well as wild type mice and examined pathological changes in their kidneys and urine. Both wild type and MCP-1 null male mice became hyperoxaluric and demonstrated CaOx crystalluria. Neither of them developed crystal deposits in their kidneys. Both showed some morphological changes in their renal proximal tubules. Significant pathological changes such as cell death and increased urinary excretion of LDH were not seen. Results suggest that at least in mice (1) Increase in oxalate and decrease in citrate excretion can lead to CaOx crystalluria but not CaOx nephrolithiasis; (2) MCP-1 does not play a role in crystal retention within the kidneys; (3) Expression of OPN and MCP-1 is not increased in the kidneys in the absence of crystal deposition; (4) Crystal deposition is necessary for significant pathological changes and movement of monocytes and macrophages into the interstitium.     

N-acetylcysteine protects against star fruit-induced acute kidney injury

Background: Star fruit (SF) is a popular fruit, commonly cultivated in many tropical countries, that contains large amount of oxalate. Acute oxalate nephropathy and direct renal tubular damage through release of free radicals are the main mechanisms involved in SF-induced acute kidney injury (AKI). The aim of this study was to evaluate the protective effect of N-acetylcysteine (NAC) on SF-induced nephrotoxicity due to its potent antioxidant effect.

Materials and methods: Male Wistar rats received SF juice (4?mL/100?g body weight) by gavage after a 12?h fasting and water deprivation. Fasting and water deprivation continued for 6?h thereafter to warrant juice absorption. Thereafter, animals were allocated to three experimental groups: SF (n?=?6): received tap water; SF?+?NAC (n?=?6): received NAC (4.8?g/L) in drinking water for 48?h after gavage; and Sham (n?=?6): no interventions. After 48?h, inulin clearance studies were performed to determine glomerular filtration rate. In a second series of experiment, rats were housed in metabolic cages for additional assessments.

Results: SF rats showed markedly reduced inulin clearance associated with hyperoxaluria, renal tubular damage, increased oxidative stress and inflammation. NAC treatment ameliorated all these alterations. Under polarized light microscopy, SF rats exhibited intense calcium oxalate birefringence crystals deposition, dilation of renal tubules and tubular epithelial degeneration, which were attenuate by NAC therapy.

Conclusions: Our data show that therapeutic NAC attenuates renal dysfunction in a model of acute oxalate nephropathy following SF ingestion by reducing oxidative stress, oxaluria, and inflammation. This might represent a novel indication of NAC for the treatment of SF-induced AKI.     

Reactive oxygen species,inflammation and calcium oxalate nephrolithiasis

Calcium oxalate (CaOx) kidney stones are formed attached to Randall’s plaques (RPs) or Randall’s plugs. Mechanisms involved in the formation and growth are poorly understood. It is our hypothesis that stone formation is a form of pathological biomineralization or ectopic calcification. Pathological calcification and plaque formation in the body is triggered by reactive oxygen species (ROS) and the development of oxidative stress (OS). This review explores clinical and experimental data in support of ROS involvement in the formation of CaOx kidney stones. Under normal conditions the production of ROS is tightly controlled, increasing when and where needed. Results of clinical and experimental studies show that renal epithelial exposure to high oxalate and crystals of CaOx/calcium phosphate (CaP) generates excess ROS, causing injury and inflammation. Major markers of OS and inflammation are detectable in urine of stone patients as well as rats with experimentally induced CaOx nephrolithiasis. Antioxidant treatments reduce crystal and oxalate induced injury in tissue culture and animal models. Significantly lower serum levels of antioxidants, alpha-carotene, beta-carotene and beta-cryptoxanthine have been found in individuals with a history of kidney stones. A diet rich in antioxidants has been shown to reduce stone episodes. ROS regulate crystal formation, growth and retention through the timely production of crystallization modulators. In the presence of abnormal calcium, citrate, oxalate, and/or phosphate, however, there is an overproduction of ROS and a decrease in the antioxidant capacity resulting in OS, renal injury and inflammation. Cellular degradation products in the urine promote crystallization in the tubular lumen at a faster rate thus blocking the tubule and plugging the tubular openings at the papillary tips forming Randall’s plugs. Renal epithelial cells lining the loops of Henle/collecting ducts may become osteogenic, producing membrane vesicles at the basal side. In addition endothelial cells lining the blood vessels may also become osteogenic producing membrane vesicles. Calcification of the vesicles gives rise to RPs. The growth of the RP’s is sustained by mineralization of collagen laid down as result of inflammation and fibrosis.     

Inhibitions of urinary oxidative stress and renal calcium level by an extract of Quercus salicina Blume/Quercus stenophylla Makino in a rat calcium oxalate urolithiasis model

Objectives:   To clarify the mechanism of Urocalun, an extract of Quercus salicina Blume /Quercus stenophylla Makino (QS), in the treatment of urolithiasis.
Methods:   Rat calcium oxalate urolithiasis was induced by oral administration of ethylene glycol and the vitamin D₃ analog alfa-calcidol for 14 days. QS extract was repeatedly given to rats. After the last administration, biochemistries in urine and plasma, renal calcium, and urinary malondialdehyde (an oxidative stress marker) were measured.
Results:   Ethylene glycol and alfa-calcidol treatment increased urinary malondialdehyde and renal calcium levels. This increase was significantly suppressed by the administration of QS extract, suggesting that the inhibition of renal calcium accumulation by QS extract is due to its antioxidative activity.
Conclusions:   These findings suggest that the antioxidative activity of QS extract plays a role in the prevention of stone formation and recurrence in urolithiasis.     

Renal L-type fatty acid--binding protein in acute ischemic injury

Fatty acid-binding proteins (FABPs) bind unsaturated fatty acids and lipid peroxidation products during tissue injury from hypoxia. We evaluated the potential role of L-type FABP (L-FABP) as a biomarker of renal ischemia in both human kidney transplant patients and animal models. Urinary L-FABP levels were measured in the first urine produced from 12 living-related kidney transplant patients immediately after reperfusion of their transplanted organs, and intravital video analysis of peritubular capillary blood flow was performed simultaneously. A significant direct correlation was found between urinary L-FABP level and both peritubular capillary blood flow and the ischemic time of the transplanted kidney (both P < 0.0001), as well as hospital stay (P < 0.05). In human-L-FABP transgenic mice subjected to ischemia-reperfusion injury, immunohistological analyses demonstrated the transition of L-FABP from the cytoplasm of proximal tubular cells to the tubular lumen. In addition, after injury, these transgenic mice demonstrated lower blood urea nitrogen levels and less histological injury than injured wild-type mice, likely due to a reduction of tissue hypoxia. In vitro experiments using a stable cell line of mouse proximal tubule cells transfected with h-L-FABP cDNA showed reduction of oxidative stress during hypoxia compared to untransfected cells. Taken together, these data show that increased urinary L-FABP after ischemic-reperfusion injury may find future use as a biomarker of acute ischemic injury.     

钙化性纳米微粒与人肾小管上皮细胞相互作用的实验研究

目的 探讨钙化性纳米微粒( calcifying nanoparticle,CNP)对人肾小管上皮细胞(HK-2)的损伤机制及CNP在肾结石形成中的可能作用. 方法 体外培养的HK-2加入CNP,使用NADPH氧化酶抑制剂apocynin进行干预.将HK-2分为4组:正常对照组、纳米微粒组、药物组、纳米微粒+药物组.光镜及透射电镜下观察HK-2与CNP相互作用后的形态变化.采用比色法检测各组24h后细胞培养液中乳酸脱氢酶、丙二醛和透明质酸的水平. 结果 CNP可引起HK-2形态变化,通过透射电镜观察到HK-2吞噬CNP现象.24 h后各组细胞培养液中乳酸脱氢酶含量分别为(231 ±19)、(1042±25)、(433±24)、(652±39) U/L,丙二醛分别为(1.61±0.04)、(5.41±0.10)、(1.98±0.05)、(2.69±0.10)μmol/L,透明质酸分别为(83.44±4.23)、(130.01±3.76)、(95.39±2.06)、(104.73±1.67) ng/L,组间差异均有统计学意义(P＜0.05). 结论 HK-2具有黏附、吞噬CNP的能力,CNP可引起HK-2氧化应激损伤.     

Early Events in Kidney Donation: Progression of Endothelial Activation, Oxidative Stress and Tubular Injury After Brain Death

Cerebral injury leading to brain death (BD) causes major physiologic derangements in potential organ donors, which may result in vascular-endothelial activation and affect posttransplant graft function. We investigated the kinetic of pro-coagulatory and pro-inflammatory endothelial activation and the subsequent oxidative stress and renal tubular injury, early after BD declaration. BD was induced by slowly inflating a balloon-catheter inserted in the extradural space over a period of 30 min. Rats (n = 30) were sacrificed 0.5, 1, 2 or 4 h after BD-induction and compared with sham-controls. This study demonstrates immediate pro-coagulatory and pro-inflammatory activation of vascular endothelium after BD in kidney donor rats, proportional with the duration of BD. E- and P-Selectins, Aα/Bβ-fibrinogen mRNA were abruptly and progressively up-regulated from 0.5 h BD onwards; P-Selectin membrane protein expression was increased; fibrinogen was primarily visualized in the peritubular capillaries. Plasma von Willebrand factor was significantly higher after 2 h and 4 h BD. Urine heart-fatty-acid-binding-protein and N-acetyl-glucosaminidase, used as new specific and sensitive markers of proximal and distal tubular damage, were found significantly increased after 0.5 h, with a maximum at 4 h. Unexpectedly, oxidative stress was detectable only late, after the installation of tubular injury, suggesting only a secondary role for hypoxia in triggering these injuries.     

Mechanism of calcium oxalate renal stone formation and renal tubular cell injury

Abstract:   Formation of calcium oxalate stones tends to increase with age and begins from the attachment of a crystal formed in the cavity of renal tubules to the surface of renal tubular epithelial cells. Though most of the crystals formed in the cavity of renal tubules are discharged as is in the urine, in healthy people, crystals that attach to the surface of renal tubular epithelial cells are thought to be digested by macrophages and/or lysosomes inside of cells. However, in individuals with hyperoxaluria or crystal urine, renal tubular cells are injured and crystals easily become attached to them. Various factors are thought to be involved in renal tubular cell injury. Crystals attached to the surface of renal tubular cells are taken into the cells ( crystal–cell interaction ). And then the crystal and crystal aggregates grow, and finally a stone is formed.     

草酸钙结晶-肾小管细胞损伤机制研究进展

草酸钙是肾结石中最常见的化学成分。肾钙盐结晶是草酸钙结石形成的关键步骤之一,而近年来研究发现肾钙盐结晶形成与肾小管上皮细胞损伤密切相关。本文就草酸钙结石形成和肾小管上皮细胞损伤相互作用机制方面进行综述。