Acute Tubular Necrosis and Renal Failure in Patients with Glomerular Disease

Renal failure is common in patients with glomerular disease. Although renal failure may result from the glomerular lesion itself, it is also observed in patients with minimal glomerular alterations. Degenerative changes and necrosis of the tubular epithelium are common findings in kidney biopsies from these patients. The aim of this work is to examine the association between acute tubular necrosis (ATN) and renal failure in patients with glomerulopathy and to estimate the relationship between the degree of ATN and renal failure in these patients. Data on age, sex, presence of nephrotic syndrome, and renal failure were recorded for 149 patients, who underwent a renal biopsy for the diagnosis of glomerulopathy. The biopsies were reviewed, and ATN, when present, was classified as one of four grades depending on its intensity. The mean age of the patients was 21 ± 16 years. Eighty patients (54%) were male, 43 (42%) had renal failure, 104 (72%) had nephrotic syndrome, and 66 (45%) had minimal change disease or focal segmental glomerulosclerosis. ATN was present in 115 (77%) patients. The frequency of renal failure was directly correlated with the intensity of ATN [odds ratio (OR) of 26.0 for patients with grade 2 lesions and OR of 45.5 for patients with grade 3 lesions]. ATN is a common finding in the biopsies of patients with glomerulopathy. The severity of ATN is directly associated with the frequency of renal failure in these patients.     

Histological Features of Acute Tubular Necrosis in Native Kidneys and Long-Term Renal Function

There are few studies on the relationship between the morphology of acute tubular necrosis (ATN) in native kidneys and late functional recovery. Eighteen patients with acute renal failure (ARF) who had undergone renal biopsy were studied. All had the histological diagnosis of ATN and were followed for at least six months. Clinical characteristics of ARF were analyzed, and histological features were semi-quantitatively evaluated (tubular atrophy, interstitial inflammatory infiltrate, interstitial fibrosis, and ATN). According to the maximal GFR achieved during the follow-up, patients were divided into two groups: complete recovery (GFR ≥ 90 mL/min/1.73 m²) and partial recovery (GFR < 90 mL/min/1.73 m²). Only 39% of the patients achieved complete recovery. Patients with partial recovery achieved their maximal GFR (63 ± 9 mL/min/1.73 m²) 37 ± 14 months after ARF, a period of time similar to those patients with complete recovery (i.e., 54 ± 22 months). Patients with partial recovery had more severe ARF: oliguria was more frequent (90 versus 17%, p < 0.01), and they had higher peak creatinine (13.85 ± 1.12 versus 8.95 ± 1.30 mg/dL, p = 0.01), and longer hospitalization (45 ± 7 versus 20 ± 4 days, p = 0.03). No single histological parameter was associated with partial recovery, but the sum of all was when expressed as an injury index [4.00 (2.73–5.45) versus 2.00 (1.25–3.31), p < 0.05]. In conclusion, among patients with atypical ATN course, those with more severe ARF and tubule-interstitial lesions are more prone to partial recovery.     

肾小管坏死后修复与胚胎发育过程中细胞极性形成的比较

目的:细胞极性是肾小管上皮细胞发挥生理功能的结构基础。本研究的目的是明确成体大鼠肾小管坏死后修复过程中与胚胎大鼠肾小管发育过程中细胞极性形成过程的一致性。方法:通过皮下注射硫酸庆大霉素制作出生后8周雄性Wistar大鼠急性肾小管坏死后自然修复的动物模型,分别在注射庆大霉素后第7天(用药5d,停药2d)、第14天和第28天采集肾脏标本;另外采集妊娠20d大鼠的胚胎肾脏标本。观察成体大鼠肾小管坏死后修复再生过程中与胚胎大鼠肾小管发育过程中肾小管的形态学变化;以Na+-K+-ATP酶作为细胞极性的标志物,采用免疫荧光染色技术对比观察成体大鼠肾小管坏死后修复再生过程中与胚胎大鼠肾小管发育过程中细胞极性形成的过程。结果:(1)成体大鼠注射庆大霉素后第7天,肾小管上皮细胞坏死、脱落,肾小管基底膜裸露,管腔内有大量脱落的上皮细胞碎片;第14天,肾小管基底膜出现新再生的肾小管上皮细胞;第28天,大多数肾小管结构基本恢复正常。(2)成体大鼠注射庆大霉素后第7天,裸露的肾小管基底膜没有Na+-K+-ATP酶的表达;第14天,新再生的肾小管上皮细胞有Na+-K+-ATP酶的表达,但此时Na+-K+-ATP酶没有明显的极性分布,胞膜和胞浆均有表达;第28天,Na+-K+-ATP酶呈极性分布,主要表达在肾小管上皮细胞的侧基底膜。(3)胚胎大鼠肾小管发育过程是从S形体发育成为不成熟的肾小管,再发育成为成熟的肾小管。(4)胚胎大鼠肾小管发育过程中,Na+-K+-ATP酶的表达从没有极性到有极性分布,即Na+-K+-ATP酶从肾小管上皮细胞的胞膜和胞浆均有表达到只局限在侧基底膜表达。结论:成体大鼠肾小管坏死后修复过程中细胞极性形成的过程与胚胎大鼠肾小管发育过程中细胞极性形成的过程是一致的,提示大鼠肾小管坏死后修复再生的过程类似肾小管胚胎发育的过程。     

Angiotensin II and Endothelin in the Renal Cortex During the Evolution of Glycerol-Induced Acute Tubular Necrosis

Hypertonic glycerol injection is one of the most frequently used models of experimental acute renal failure. Late structural changes such as interstitial fibrosis in the renal cortex and tubular atrophy have been detected after severe acute tubular necrosis (ATN). The aim of this study was to investigate the expression of angiotensin II (AII) and endothelin during the evolution of the ATN induced by glycerol and their relationships with the late structural changes observed in the kidneys. Forty-nine male Wistar rats were injected with a 50% glycerol solution, 8 mL/kg, divided into equal amounts, each administered into one hind leg, and 18 with 0.15 M NaCl solution. Blood and urine samples were collected 1, 5, 30, and 60 days after the injections to quantify sodium and creatinine; the animals were killed and the kidneys removed for histologic and immunohistochemical studies. The results of the immunohistochemical studies were scored according to the extent of staining in the cortical tubulointerstitium. Glycerol-injected rats presented a transitory increase in plasma creatinine levels and in fractional sodium excretion. The immunohistochemical studies showed increased AII and endothelin staining in the renal cortex from rats killed 5 days after glycerol injection (p < 0.001) compared with control that persisted until day 60. The animals killed on days 30 and 60 also presented chronic lesions (fibrosis, tubular dilatation, and atrophy) in the renal cortex, despite the recovery of renal function. AII and endothelin may have contributed to the development of renal fibrosis in these rats.     

胚胎后肾间充质细胞移植对急性肾小管坏死肾功能的修复作用

目的：将体外培养的胚胎后肾间充质细胞,通过尾静脉注射移植给急性肾小管坏死的模型大鼠,观察是否改善对肾功能起修复作用。方法：（1）体外培养、扩增及生物学鉴定大鼠胚胎后肾间充质细胞株（RIMM-18）;（2）通过皮下注射总量为900mg/kg庆大霉素,建立急性肾小管坏死的大鼠模型;（3）除空白组外,将造模大鼠随机分为3组：①移植组：造模后通过尾静脉注射移植培养的RIMM-18细胞1～6×107/ml;②培基组：造模后通过尾静脉注射等量的无血清培养基;③急性肾小管坏死组（ATN组）：皮下注射总量为900mg/kg的庆大霉素×3d。（4）留取标本：分别于成模后1d、4d、1周、2周及4周杀鼠,留取尿和血标本;（5）生化指标检测：BUN、Scr、尿蛋白、尿肌酐、β2-MG、NAG和RBP等。结果：（1）RIMM-18细胞体外生长良好,保持间充质细胞特性。（2）皮下注射总量900mg/kg的庆大霉素3d成模。（3）移植组大鼠毛发有光泽、脱毛少,体重及尿量的恢复较快,死亡率下降。（4）各组大鼠生化指标比较：移植组尿蛋白于4d时达峰值,2周时下降接近正常;而培基组和ATN组于1周达峰值,持续至4周降至正常。移植组、培基组和ATN组于1周、2周时其值分别为（1.37±0.10）mg/L、（1.97±0.21）mg/L、（2.05±0.19）mg/L,（0.56±0.07）mg/L、（1.59±0.07）mg/L、（1.66±0.11）mg/L,移植组与培基组及ATN组之间差异有统计学意义（P〈0.01）。BUN、Scr、NAG、RBP及β2-MG变化规律类似。（5）肾脏病理：移植组4d时肾小管病变最显著,培基组和ATN组则于1周时肾小管病变最明显,恢复较移植组慢。肾小管Paller氏评分显示于1周、2周、4周时移植组与培基组及ATN组之间差异有统计学意义（P〈0.01）。结论：胚胎后肾间充质细胞通过尾静脉移植能改善ATN的肾功能。     

Endothelin A Receptors Expressed in Renal Blood Vessels of Renal Transplant Patients Are Connected With Acute Tubular Necrosis or Antibody-Mediated Rejection

Background

The role of non-HLA antibodies named antiendothelin A receptor antibodies is potentially significant but not established. The significance of the endothelin A receptor (ETAR) and its expression in renal biopsy has not been defined. We decided to evaluate the presence and relevance of ETARs in renal transplant biopsy for cause.The aim of our study was to evaluate the immunoreactivity of the ETAR and its significance in patients who had a renal transplant biopsy due to deterioration of transplant function (biopsy for cause) with detailed characterization of staining in small and intermediate arteries of renal transplant biopsies.

The Prevention of Acute Tubular Necrosis in Renal Transplantation by Chronic Salt Loading of the Recipient1

By replacing normal water intake with 0–9% saline solution on a continuing basis, animals are protected against acute is ch?mic tubular necrosis. Last-minute plasma volume expansion does not provide this protection. To see whether the protection is intrinsic to the kidney or merely involves the host, kidneys were transplanted syngeneically from salt-drinking rats to water-drinking rats, and vice versa, and the recipients were injected with glycerol to produce myoh?moglobinuric renal failure. The kidneys transplanted from water-drinking animals did not develop failure in the salt-drinking animals, but those from salt drinkers did develop failure in the water drinkers. Therefore overhydration of the recipient by continuous salt loading is important in preventing acute tubular necrosis in renal transplantation.     

Nephrotic Syndrome and Acute Tubular Necrosis Due to Meloxicam Use

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used by patients all over the world. Five to eighteen percent of the patients who receive NSAIDs can suffer from kidney-related side effects. Among them, the most relevant are sodium and water retention, hyponatremia, worsening of hypertension or preexisting cardiac failure, hyperkalemia, acute kidney injury, chronic kidney disease, papillary necrosis, nephrotic syndrome (NS), and acute interstitial nephritis. We report the case of a 65-year-old woman who developed acute tubular necrosis and NS a few days after receiving 15 mg of meloxicam (MLX) for 3 days for tendinitis. Steroid therapy was begun with normalization of kidney function after 7 weeks of treatment. NS (minimal change disease) was characterized by frequent remissions and relapses as prednisone was lowered under 30 mg/day. Azathioprine (100 mg/day) was added on the fifth month of diagnosis and a complete remission was finally obtained 4 years after hospital admittance. In her last medical checkup, 8 years after her debut and receiving azathioprine (50 mg) and prednisone (5 mg/day), renal function was normal (creatinine 1.0 mg/dL and creatinine clearance 80 mL/min/1.73 m²), proteinuria was 150 mg/day and there was no hematuria or hypertension.

The aim of communicating this case is to raise a warning about these renal side effects of MLX. After thorough review of literature, only one other report with the same findings was found.     

Acute Tubular Necrosis in Hepatorenal Syndrome: An Electron Microscopy Study

This report describes light and transmission electron microscopy (LM and EM, respectively) studies of kidneys from five cases of hepatorenal syndrome. The kidneys were removed and fixed for LM and EM between 30 and 120 min after death. All patients had progressive renal failure after admission to the hospital. All cases were jaundiced, had ascites, and exhibited features of hepatic encephalopathy. LM study revealed severe acute tubular lesions (ATL) or, more conventionally, acute tubular necrosis (ATN). EM study demonstrated necrosis of the proximal tubules characterized by swelling, disorganization of the cristae and appearance of dark bodies in the mitochondria, coalescence, fragmentation or displacement of the microvilli, loss of plasma membranes, rupture of the basement membranes, and separation of the cells from the basement membranes. Rupture of tubular basement membranes (tubulorrhexis) and mitochondrial dark bodies suggest an ATN due to ischemia or induced by vasoconstrictor substance(s). Glomerular lesions were infrequent (one in five) and therefore, do not seem to have contributed to renal failure. All cases terminally had extremely low urinary sodium (11 mEq/liter), high urinary potassium (50 mEq/liter), a remarkably low urinary sodium/potassium ratio (0.26, normal = 4.27), and a low urinary osmolality (<400 mOsm/kg). From this study we conclude that an ATN of variable severity may be associated with the hepatorenal syndrome. Since this ATN developed without preceding shock, sepsis, or hypotension it is possible that this ATN like that in ischemic acute renal failure may be due to reduced renal blood flow and intense cortical vasoconstriction which has been reported in hepatorenal syndrome. Finally, our data imply that low urinary sodium is consistent with this pathologic lesion in this clinical setting.     

Acute Tubular Necrosis Associated with Non-Hemorrhagic Dengue Fever: A Case Report

Dengue fever (DF) is an arthropod-born viral infection affecting humans. Dengue viruses are transmitted through the bites of the mosquito Aedes aegypti. Acute renal failure (ARF) is reported in patients who are affected mainly with Dengue hemorrhagic fever (DHF), which is a severe presentation of the disease. We report the case of a 24-year-old Omani female with no past history of particular medical problems. She was referred to our hospital for the further management of acute renal failure. She had clinical features of DF without DHF. The kidney biopsy showed features of acute tubular necrosis (ATN). She had a complete recovery after 25 days and required three sessions of hemodialysis. We conclude that DF even without DHF may lead to ATN and ARF. Clinicians should be aware of this etiology. Treatment is supportive and may require dialysis. The prognosis could be favorable.     

肿瘤坏死因子基因型多态性与肾移植受者急性排斥反应的关系

目的：探讨肾移植受者外周血中肿瘤坏死因子（TNF-α）基因多态性与急性排斥反应的关系。方法：应用序列特异性引物聚合酶链反应（PCR—SSP）测定62例肾移植受者外周血中TNF-α的基因型,并结合供受者HLA配型情况,比较各基因型对急性排斥反应发生率的影响。结果：在HLA—DR错配的情况下,TNF—α等位基因为高分泌型者,其术后急性排斥反应发生率较低分泌型者高（P〈0．05）。结论：TNF-α基因型对肾移植排斥反应发生率有明显影响,可据此或可制定更为合理的个体化免疫抑制治疗方案。     

Thyroid Hormone in the Treatment of Post-transplant Acute Tubular Necrosis (ATN)

Delayed graft function (DGF) in cadaver kidney transplants is a common problem and is often due to acute tubular necrosis (ATN). DGF in transplants may have a deleterious effect on long-term graft survival. Since thyroid hormone has been shown to hasten recovery from ATN in experimental models, we designed a trial to determine if a defined course of triiodothyronine (T3) would improve the short- or long-term outcome of patients with DGF in cadaveric transplants. A prospective, randomized, placebo controlled, double blind trial of T3 was carried out in patients with DGF in cadaveric renal transplants. End-points were percentage requiring dialysis, percentage recovering function, time to recovery and length of hospital stay. Long-term outcomes were percentage grafts functioning at 1 year and mean serum creatinine at 1 year. Forty-four patients were randomized to receive either T3 or placebo. Three patients were dropped from each group when early biopsies disclosed that DGF was due to rejection. The groups were well matched by age, cold ischemia time of the graft, and percentage reactivity to a random panel of antigens. Baseline thyroid function studies, including T3, reverse T3 (rT3), and thyroid stimulating hormone (TSH) levels, were similar between the two groups and typical of 'euthyroid-sick syndrome'. T3 had no effect on percentage requiring dialysis, time to recovery, percentage recovering function, or length of stay. At 1 year follow-up, graft function was similar in both groups and significantly lower than that seen in patients with good initial function. Thyroid hormone, given early in the course of DGF in cadaver kidney recipients, had no effect on the course of DGF. Long-term graft function is impaired in patients who experience post-transplant DGF compared to those who have good initial function.     

Heme Oxygenase-1 Inhibits Renal Tubular Macroautophagy in Acute Kidney Injury

Autophagy is a tightly regulated, programmed mechanism to eliminate damaged organelles and proteins from a cell to maintain homeostasis. Cisplatin, a chemotherapeutic agent, accumulates in the proximal tubules of the kidney and causes dose-dependent nephrotoxicity, which may involve autophagy. In the kidney, cisplatin induces the protective antioxidant heme oxygenase-1 (HO-1). In this study, we examined the relationship between autophagy and HO-1 during cisplatin-mediated acute kidney injury (AKI). In wild-type primary proximal tubule cells (PTC), we observed a time-dependent increase in autophagy after cisplatin. In HO-1^−/− PTC, however, we observed significantly higher levels of basal autophagy, impaired progression of autophagy, and increased apoptosis after cisplatin. Restoring HO-1 expression in these cells reversed the autophagic response and inhibited apoptosis after treatment with cisplatin. In vivo, although both wild-type and HO-1–deficient mice exhibited autophagosomes in the proximal tubules of the kidney in response to cisplatin, HO-1–deficient mice had significantly more autophagosomes, even in saline-treated animals. In addition, ecdysone-induced overexpression of HO-1 in cells led to a delay in autophagy progression, generated significantly lower levels of reactive oxygen species, and protected against cisplatin cytotoxicity. These findings demonstrsate that HO-1 inhibits autophagy, suggesting that the heme oxygenase system may contain therapeutic targets for AKI.Oxidative stress plays a major role in the pathogenesis of cisplatin-induced nephrotoxicity.^1,2 In response to injury, the kidney is able to elicit adaptive and protective mechanisms to limit further damage. One such mechanism is the rapid and robust induction of heme oxygenase-1 (HO-1).^3–5 Heme oxygenase is the rate-limiting enzyme in the degradation of heme to iron, carbon monoxide, and biliverdin.^3,6,7 Studies have shown that HO-1 mRNA is induced in the kidney as early as 3 to 6 hours in animal models of both ischemia/reperfusion and nephrotoxin-induced acute kidney injury (AKI).^3,8 Such induction occurs predominantly in the proximal tubule segment of the nephron,^3,8 which coincides with the location of maximal cisplatin accumulation and oxidative stress.^9,10 Chemical inhibition of HO enzyme activity in rats³ and genetically deficient HO-1 mice¹¹ treated with cisplatin have significantly worse kidney function and tubular injury, suggesting a protective role for HO-1 expression in cisplatin-induced renal tubular cell death, specifically necrosis and apoptosis.Recent evidence indicates that autophagy, a type II programmed cell death, is induced during cisplatin injury in proximal tubular epithelial cells (PTC) and is a protective response.^12–15 Autophagy, a physiologically regulated and evolutionarily conserved process, refers to an intracellular degradation system in which cytoplasmic components, such as damaged organelles, long-lived proteins, protein aggregates, and other macromolecules, are directed to the lysosome.^16–19 Autophagy (also referred to as macroautophagy) begins with the formation of an initiation membrane (vesicle nucleation) that sequesters cytoplasmic components as it expands (vesicle elongation); finally, the edges fuse to form a double-membraned vesicle called autophagosome. This vesicle fuses with the lysosome to form an autolysosome where the sequestered components are degraded by the acidic lysosomal enzymes.^17,20 At least 31 Atg (Autophagy) genes have been identified in yeast and their mammalian orthologs have also been recently characterized.^21–24 Expression of the mammalian orthologs of Atg5, Atg6 (beclin 1), Atg7, and Atg8 (LC3, microtubule-associated protein 1 light chain 3) are used as markers to detect autophagy in mammalian cells.^13,25,26 Both Atg5 and beclin play an important role in autophagosome initiation and vesicle nucleation. Vesicle elongation requires several autophagy proteins such as Atg7 and Atg4. These proteins conjugate the lipid phosphatidylethanolamine to LC3 to form membrane-associated LC3-II. LC3-II is one of the autophagy proteins that specifically interacts only with the autophagic vesicles and remains associated until vesicle breakdown. All of the other proteins associate with the vesicle at different stages of maturation and have alternate functions in the cell. Therefore, LC3-II is a valuable marker to assess the presence of autophagosomes in cells.Several in vitro and in vivo studies suggest that autophagy can induce cell survival or death depending on the stress or the cellular environment.^{12,13,18,22,27} Under normal physiologic conditions, cells use autophagy to maintain homeostasis. If insufficient autophagy occurs, long-lived proteins and damaged organelles accumulate and cell death occurs. Even under certain pathologic conditions, autophagy is induced and is cytoprotective. However, if autophagy is prolonged or unregulated, it can lead to cell death. This suggests that autophagy may act as a cytoprotective mechanism but converges into apoptotic pathways during severe stress. Therefore, it is important to understand how autophagy is modulated as both insufficient and excessive autophagy have deleterious effects.Because both autophagy and HO-1 are induced during cisplatin injury, the purpose of this study was to evaluate whether HO-1 expression modulated autophagy in PTC and protected them from cisplatin-induced cell death. We studied the effects of HO-1 deficiency using HO-1 knockout (HO-1^−/−) mice on the progression of autophagy during cisplatin injury. Also, PTC cultures generated from HO-1^+/+ (heme oxygenase-1 wild-type) and HO-1^−/− mice were analyzed for cisplatin-mediated autophagy and cell death. Furthermore, HO-1^−/− mice that specifically express only the human HO-1 gene (HBAC mice, human HO-1 overexpressing bacterial artificial chromosome mice) were generated and PTC isolated from these mice were used to study the effects of restoring HO-1 expression on autophagy progression during cisplatin injury. Also, ecdysone inducible HO-1 overexpressing renal epithelial cells were generated and analyzed for cisplatin-mediated autophagy.     

动员自体骨髓干细胞对大鼠急性肾小管坏死的治疗

目的：观察粒细胞集落刺激因子联合干细胞因子动员骨髓干细胞的作用、骨髓干细胞是否具有向损伤肾组织归巢的能力及其在肾脏组织中的分布,初步探讨粒细胞集落刺激因子联合干细胞因子是否具有促进急性肾小管坏死修复的作用。方法：160只8～10周龄雄性SD大鼠随机分为4组：对照组,模型组、G-CSF＋SCF治疗组、G-CSF＋SCF对照组,检测：（1）外周血白细胞总数及单个核细胞中CD34＋细胞百分比的变化;（2）尿NAG酶检测;（3）肾脏组织病理学改变;（4）肾组织CD34＋细胞表达变化。结果：（1）G-CSF＋SCF治疗组和G-CSF＋SCF对照组外周血中白细胞数、CD34＋细胞百分比于第5天达高峰,与对照组、模型组相比,差异有统计学意义（P〈0.05）,以后逐渐下降;相应地,G-CSF＋SCF治疗组肾组织内CD34＋细胞较对照组、模型组也明显增多（P〈0.05）。（2）手术后第5、10、17天,G-CSF＋SCF治疗组尿NAG酶、肾脏病理学改变均明显好于模型组（P〈0.05）。第24天G-CSF＋SCF治疗组尿NAG酶、肾脏病理学改变基本恢复正常,而模型组仍异常。第31天各组间尿NAG酶、肾脏病理学改变其差异无统计学意义。结论：（1）粒细胞集落刺激因子和干细胞因子联合应用对缺血再灌注损伤诱发急性肾小管坏死大鼠的骨髓干细胞有显著的动员作用。（2）骨髓干细胞能在损伤的肾小管归巢和定居,并可能参与损伤肾组织的修复。（3）粒细胞集落刺激因子和干细胞因子联合应用能在一定程度上加速急性肾小管坏死后肾功能的修复。