Microdissection Demonstration of the Lesion of the Endocrine Kidney in Children

Microdissection of nephrons of kidneys of children showing advanced ischemic tubular atrophy, and removed for control of hypertension, demonstrates marked proximal convoluted tubular atrophy, with formation of multiple small proximal tubular diverticula. These diverticula presumably contribute to the microscopic appearance of large numbers of small tubules lined by low epithelial cells with pale or clear cytoplasm, adjacent to glomeruli in the cortices of kidneys showing ischemic tubular atrophy (endocrine kidney). Segmentation of such atrophic tubules leads to formation of blind segments (microcysts), as demonstrated in this study and by Oliver.⁸ The distinctive microscopic appearance of the endocrine kidney, a not infrequent finding in kidneys of children with chronic renal insufficiency who require nephrectomy for control of hypertension, has not hitherto been emphasized in the literature on pediatric renal disease.     

Labeled Lectin Studies of Renal Tubular Dysgenesis and Renal Tubular Atrophy of Postnatal Renal Ischemia and end-Stage Kidney Disease

Renal tubular dysgenesis (RTD), with hypoplasia especially of renal proximal convoluted tubules and clinical neonatal anuria or oliguria, has been reported as a congenital familial (autosomal recessive) disease, variably with features of oligohydramnios, Potter syndrome, or pulmonary hypoplasia. A similar tubular lesion due to antenatal tubular atrophy has been reported for conjoined twins with twin-twin transfusion syndrome or acardia and in infants of mothers given antihypertensive agents, including angiotensin-converting enzyme (ACE) inhibitors, during pregnancy, and it has been seen as a unilateral lesion in young infants with renal artery stenosis due to arteritis or medial arterial calcinosis. The renal tubular changes in RTD are very like those of the “endocrine kidney” in experimental animals and resemble those of the renal tubular atrophy of end-stage kidney diseases such as glomerulonephritis, tubulointerstitial kidney disease, obstructive uropathy/pyelonephritis, graft rejection of transplanted kidneys, or the renal parenchymal changes seen with protracted dialysis therapy. Labeled lectins that differentially mark proximal convoluted, distal convoluted and connecting, and collecting tubules showed no distinctive differences in stainingpatterns of the hypoplastic renal tubules of infants and children with RTD, postnatal renal artery obstruction, or the various types of end-stage renal disease with the lectins used (PNA, GSL1, UEA, and LTA). The findings suggest that the renal tubular changes in some if not all the conditions studied are the result of renal ischemia. The reported familial RTD with hypernephronic nephromegaly may be a specific disorder, but other forms could reflect renal ischemia acquired in utero or in early or later postnatal life.     

Cellular response to renal hypoxia is different in adolescent and infant rats

Immature renal tubules are more tolerant to ischemia than mature renal tubules. Here we compared the developmental pattern for some cellular responses evoked by hypoxia and reoxygenation in renal proximal tubules from 10- and 40-day-old rats. Redistribution of Na(+)-K(+)-ATPase from the plasma membrane was studied by confocal microscopy techniques in primary cultured renal proximal tubular cells. The developmental expression of Na(+)-K(+)-ATPase, micro-calpain and heme oxygenase-1 was measured by RT-PCR techniques in rat renal cortex. In response to hypoxia Na(+)-K(+)-ATPase redistribution from the plasma membrane was almost 2-fold increased in cells isolated from mature kidneys compared with cells isolated from immature kidneys. Reoxygenation resulted in a complete reestablishment of Na(+)-K(+)-ATPase in the plasma membrane in the immature but not in the mature cells. The dissociation of Na(+)-K(+)-ATPase from the plasma membrane was associated with a reduced activity and a reduced expression of Na(+)-K(+)-ATPase in the mature but not in the immature tubular cells. The expression of micro-calpain, a factor shown to induce ischemic injury to proximal tubular cells, was significantly lower in the immature compared with the mature kidney, whereas the expression of heme oxygenase-1, a factor shown to protect from renal ischemic injury, was significantly higher in the immature kidney. The results help to explain the increased tolerance of the immature kidney to injury caused by ischemia and reperfusion.     

Cell Proliferation in the Developing Human Kidney

In a previous study, utilizing antibodies to proliferating cell nuclear antigen (PCNA), we determined the proliferation index (PI) (percentage of PCNA-positive cells) of intrinsic renal cell populations in the normal adult and pediatric kidney. We have found that the PI in both adult and pediatric kidneys was very low (below 0.5 in all examined cell populations). In our present study, we investigated cell proliferation in the developing human kidney with an antibody to PCNA. Histologically normal kidneys were collected from 25 fetuses (spontaneous abortions and stillborns) ranging from 10 wk of gestation to term. Immature mesenchyme (blastema), immature early tubules, ampulla of ureteric bud, proximal tubules, Tamm-Horsfall protein (THP)-positive tubules, distal tubules, collecting ducts, and glomeruli were evaluated separately. The PI for each cell population was calculated. The PI of immature early tubules remains high (33–43) throughout embryonic life. The PI of blastemal cells is initially similarly high, but gradually decreases starting from the second trimester. The PI of THP-positive tubules, distal tubules, collecting ducts, and glomeruli starts out relatively high (5.9, 8.6, 6.0, and 12.4, respectively) and decreases gradually as term approaches (1.8, 1.3, 1.2, and 1.4, respectively). Interestingly, as soon as proximal tubules become differentiated (appearance of light microscopic features of proximal tubular epithelium with TP lectin positive brush border), their PI becomes very low (below 1) irrespective of the age of the kidney. This is the first quantitative study to show changes of the PI in various renal cell populations during human nephrogenesis. These changes in the PI relate to the stage of differentiation of the developing nephron segments. Received December 12, 1996; accepted April 24, 1997     

成纤维细胞生长因子受体4在人发育肾和病理肾中的表达

目的：观察成纤维细胞生长因子受体4(Fibroblast growth factor receptor4, FGFR4) 在人发育肾组织和儿童常见肾脏疾病中的表达,研究成纤维细胞生长因子（Fibroblast growth factor, FGF）及其受体(FGFR4)在人发育肾和病理肾中的作用,为肾脏病理发生机制研究提供新思路。方法：采用免疫组化法分析FGFR4在18例8~34周龄胎儿肾组织和82例儿科常见肾脏疾病,包括原发性肾病综合征、急性肾炎、紫癜性肾炎、单纯性血尿的表达,并作与肾脏病理积分的相关性分析。结果：①肾发生带内FGFR4表达微弱,肾囊泡和S 型小体的上支和中间支,即原始肾小管上皮细胞部位有微弱表达,间充质、压缩间充质细胞未见表达,输尿管芽及其末端壶腹和C-期足细胞表达不明显。M-期肾小球和近端小管无阳性细胞染色,远端小管和集合管表达较为明显。②所有病理切片均存在FGFR4不同程度阳性的表达,较正常对照组明显增加,其中肾小球区表达微弱,主要在足细胞部位;肾小管区表达较为强烈,主要部位在远端小管,表达密集部位的小管结构明显异常,表现为细胞萎缩、管腔扩大,尤其部分近端小管更为明显。③原发性肾病综合征与其他3种肾脏疾病的各部位FGFR4表达均未见明显差异(P>0.05)。肾近端小管和远端小管各病理类型间FGFR4表达差异无显著性,足细胞FGFR4表达在紫癜性肾炎组明显高于其他各病理类型组( P<0.05)。④相关性分析发现,近端小管FGFR4表达与肾小管病理积分呈正相关,其他各部位表达均与病理积分呈负相关（均P<0.05）。结论：FGF-FGFR4对早期肾单位的形成可能不起关键作用,而是与其后期较成熟阶段肾小管和集合管发育的调控有关。FGFR4可能参与儿童原发性肾病综合征、急性肾炎、紫癜性肾炎、单纯性血尿的病理发生,表达程度增多与肾脏病理损害有一定关系,表达适度增多有利于足细胞和肾小管损伤修复,过表达则可能加重病理损害。［中国当代儿科杂志,2007,9（2）：133-138］     

Renal Tubular Apoptosis in Twin-to-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome (TTTS) is caused by uneven shunting of blood between monochorionic twins, resulting in polycythemia in the recipient twin and growth restriction, anemia, and oliguria in the donor twin. Recent reports have described loss of proximal convoluted tubules in the kidneys of TTTS donor twins. In order to elucidate the pathogenesis of tubular deficiency in TTTS, we have reviewed the renal pathology in 25 twin pairs with autopsy-proven TTTS. Loss of differentiated proximal tubules, associated with atrophy of medullary tubules, was identified in 12/25 donor twins. In seven of these cases (all > 23-wk gestational age), the kidneys showed diffuse or partial tubular atrophy without evidence of cell death, similar to previously reported patterns. In five cases (all between 18- and 22-wk gestation), proximal and medullary tubules showed active injury characterized by markedly increased apoptosis, cell detachment, and intraluminal cell debris associated with calcifications. Tubular apoptosis tended to be more prevalent in donor fetuses with greater inter-twin body weight discordance, consistent with a more severe degree of TTTS. These results extend the spectrum of tubular alterations in TTTS to include an early stage of active apoptotic injury. The temporal distribution of injury patterns suggests that apoptotic injury of proximal and medullary tubules may be a precursor to partial or diffuse tubular atrophy. We speculate that the risk for development of tubular apoptosis in TTTS depends on the severity and timing of the hemodynamic imbalance, whereby early mid-trimester fetuses may be more vulnerable.     

The role of nitric oxide in reflux nephropathy

Reflux nephropathy (RN) is recognized as a major cause of end-stage renal failure in children and young adults. Inhibition of nitric oxide (NO) exacerbates and enhanced production ameliorates tubulointerstitial fibrosis (TIF) in experimental obstructive uropathy. NO is synthesised by NO synthase (NOS), three distinct isoforms of which have been identified: inducible (iNOS), endothelial (eNOS), and neuronal (nNOS). It has been reported that iNOS induces immunologic injury to glomerular cells and enhances accumulation of extracellular matrix in the glomerulus and tubulointerstitial space. Furthermore, it has been suggested that nNOS and eNOS have beneficial effects in ameliorating TIF. We investigated the expression of different isoforms of NOS in severe refluxing kidneys in order to further understand the pathogenesis of RN in kidney specimens from nine children with severe RN obtained at nephrectomy. Control material included normal kidney specimens from three adult patients undergoing partial nephrectomy for small kidney tumours. Histochemistry for NO was performed using nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase. Single-label immunofluorescence histochemistry was carried out using polyclonal antibodies to nNOS, iNOS, eNOS, and transforming growth factor (TGF)-beta 1 employing laser-scanning confocal microscopy. The TUNEL method was used to assess tubular apoptosis. Strong NADPH staining was observed in the proximal tubules of RN kidneys compared to controls, where there was weak staining. Control kidneys demonstrated weak immunoreactivity for iNOS in the proximal tubules and a lack of immunoreactivity for nNOS and eNOS. RN kidneys demonstrated strong immunoreactivity for nNOS in the tubulointerstitial space, for eNOS in the glomerulus, and for iNOS in the glomerulus and proximal tubules. Strong immunoreactivity for TGF beta 1 was seen in the glomerulus and proximal tubules identical to iNOS. Increased immunoreactivity for iNOS and TGF-beta 1 strongly correlated with the severity of apoptosis in RN. Our data demonstrate that NO derived from nNOS, iNOS, and eNOS is strongly expressed in RN. The selective shunting of NO via iNOS may induce renal fibrosis in RN. The upregulation of nNOS and eNOS in RN appears to be a compensatory mechanism of ameliorating TIF.     

Insulin-like growth factor-1 expression in reflux nephropathy

Background Reflux nephropathy (RN) is recognised as a major cause of end-stage renal failure in children and young adults. Insulin-like growth factor-1 (IGF-1), a peptide growth factor produced by collecting ducts, and its receptor, insulin-like growth factor-1 receptor (IGF-1R), are present in the glomeruli and basolateral membrane of renal proximal tubular cells. Exogenous IGF-1 has been shown to enhance proliferation and reduce apoptosis of tubular cells following renal injury.Methods We designed this study to investigate the expression of IGF-1 in RN. The kidney specimens from 15 children with RN were obtained at the time of nephrectomy. Control material included normal kidney specimens obtained from adult patients during partial nephrectomy for an incidentaloma. Single-label immunofluorescence histochemistry was carried out using polyclonal antibodies to IGF-1 and IGF-1R employing laser scanning confocal microscopy. Double-label immunofluorescence histochemistry was carried out using monoclonal antibodies to vimentin and clusterin to assess tubulointerstitial fibrosis. IGF-1 and IGF-1R gene expression were evaluated by in situ hybridisation (ISH). The TUNEL method was utilised to assess tubular apoptosis.Results In the normal kidney there was strong IGF-1 and IGF-1R immunoreactivity in the proximal tubules, whereas IGF-1 and IGF-1R immunoreactivity was markedly reduced in RN specimens. Strong IGF-1 and IGF-1R mRNA expression was observed in the proximal tubules in normal kidneys, whereas IGF-1 and IGF-1R mRNA expression was undetectable in RN. Renal tubulointerstitial expression of vimentin and clusterin was markedly increased in RN kidneys. Decreased IGF-1 and IGF-1R expression in RN strongly correlated with severity of tubular apoptosis in RN compared with controls.Conclusion These data suggest that the downregulation of IGF-1 and IGF-1R may play an important role in the pathogenesis of RN, at least in part by increasing interstitial collagen deposition and tubular apoptosis.     

Immuno-localization of CD44 and osteopontin in developing human kidney

CD44 is observed in ureteric bud structures and is implicated in branching morphogenesis during early mouse renal development. Healthy adult kidney demonstrates minimal CD44, but CD44 is up-regulated in renal diseases. CD44 may mediate binding of calcium oxalate crystals to tubular epithelia via the ligands osteopontin (OPN) and hyaluronan. Because 15% of premature infants develop nephrocalcinosis, developmental tubular CD44 expression might promote nephrocalcinosis. We studied CD44 and OPN immuno-localization in developing human kidney by immunohistochemical analysis. Human renal tissue between 18 and 40 wk of gestation showed CD44 immuno-localization in ureteric buds, with staining decreasing with increasing gestational age; CD44 was rarely observed in developing renal tubules. OPN was diffusely observed in proximal tubules, rarely observed in distal tubules, ureteric buds or metanephric structures. These data support the role of CD44 in early human nephron formation and branching morphogenesis. Rare CD44 staining in developing tubular epithelium suggests no role for CD44 in promoting calcium oxalate adherence to tubular epithelia in premature infants. Immuno-localization of OPN in tubules supports its role in tubular differentiation, but OPN does not seem to be necessary during early nephron formation.     

Evolution of renal segmental atrophy (Ask-Upmark kidney) in children with vesicoureteric reflux: radiographic and morphologic studies

A radiographic and morphologic study of nine patients with renal segmental "hypoplasia," whose kidneys were radiographically normal when first examined, showed the lesion to be a form of localized, progressive renal atrophy. The renal abnormality bears a strong relationship to vesicoureteric reflux, which could be demonstrated in every patient. No evidence of renal scarring or atrophy was observed in initial roentgenographic examinations at a mean age of 2.9 years (range 0.1 to 10 years); however, serial studies during five to 14 years after discovery of vesicoureteral reflux demonstrated both a lack of renal growth and a progressive loss of substance irrespective of infection. Radiographic lengths of scarred kidneys, as measures of renal growth, correlated poorly with the radiographic surface areas of the renal parenchymal outlines. The mean time from discovery of vesicoureteric reflux to appearance of a renal scar was 6.1 years, and to onset of hypertension in six patients was 7.8 years. The renal abnormality consisted of lobar atrophy with variable tubular atrophy and glomerular sclerosis and with parenchymal destruction that in some specimens had proceeded to a complete loss of nephronic elements. The occasional presence of relatively well-preserved glomeruli and tubules and of focal segmental sclerosis within persisting glomeruli was taken as evidence of a progressive renal abnormality, as opposed to a static developmental hypoplasia. These observations indicate that renal scarring, the injury presumably having been initiated by vesicoureteric reflux, can progress despite correction of the reflux and despite prevention of urinary tract infection.     

Nephronophthisis: Report of 8 Cases from Britain

Eight Scottish children with nephronophthisis are described. The typical clinical picture is thirst and polyuria associated with severe anaemia, progressive impairment of renal function, and dwarfism. Isosthenuria and gross enlargement of the bladder are usually present. Systemic hypertension is usually absent until the terminal stages.Five of these children are dead and the kidneys have been examined at necropsy. Percutaneous renal biopsy has been carried out on the remainder. The typical morbid anatomical feature is the presence of medullary cysts in small uniformly contracted kidneys. Histologically, the kidney is diffusely affected with extensive sclerosis of glomeruli, periglomerular fibrosis, and obvious hyaline thickening of the tubular basement membrane.The disease progresses inexorably and renal transplantation offers the only longterm solution.     

HSP70在缺血再灌注大鼠肾脏中的表达及意义

目的观察大鼠肾脏缺血及缺血再灌注(I/R)诱导热休克蛋白70(HSP70)的表达及意义。方法制作大鼠肾脏缺血及I/R模型,缺血组于缺血5、15和30min,I/R组于再灌注2、5、8、24、48、72h不同时间摘取肾脏,采用免疫组化方法检测肾脏HSP70的表达,同时采用HE染色,观察肾脏病理改变。结果在缺血组各时间点肾脏HSP70的表达无明显差异(P>0·05);肾脏I/R后,随时间延长,HSP70表达明显增强(P<0·05);肾脏病理显示,缺血时肾组织呈现局灶性及弥散性血管周围水肿,I/R后随时间延长肾脏损伤加重,损伤部位主要在肾小管,表现为空泡样变、小管萎缩、上皮细胞脱落及肾小球囊腔扩张等。结论HSP70在I/R后表达增强,但肾脏仍损伤严重,提示HSP70在肾脏I/R过程中没有起到主要的保护作用。     

Effects of maternal subtotal nephrectomy on the development of the fetal kidney: A morphometric study

The present study was designed to explore if maternal subtotal (5/6) nephrectomy affects the development of fetal rat kidneys using morphometric methods and examining whether there are any apoptotic changes in the fetal kidney. To generate 5/6 nephrectomized model rats, animals underwent 2/3 left nephrectomy on gestation day (GD) 5 and total right nephrectomy on GD 12. The fetal kidneys were examined on GDs 16 and 22. A significant decrease in fetal body weight resulting from maternal 5/6 nephrectomy was observed on GD 16, and a significant decrease in fetal renal weight and fetal body weight caused by maternal nephrectomy was observed on GD 22. Maternal 5/6 nephrectomy induced a significant increase in glomerular number, proximal tubular length, and total proximal tubular volume of fetuses on GD 22. Maternal 5/6 nephrectomy resulted in an increase in the number of apoptotic cells in the metanephric mesenchyme of the kidney on GD 16, and in the collecting tubules on GD 22. These findings suggest that maternal 5/6 nephrectomy stimulates the development of the fetal kidney while suppressing fetal growth.     

Dysplasia of tubular cells in a kidney- transplanted patient treated with recombinant human growth hormone

After renal transplantation (Tx), children with growth retardation can be successfully treated with recombinant human growth hormone (rhGH). However, the impact of this treatment on kidney allograft function remains a source of concern. We report on one boy who received a cadaveric kidney transplant at 12 yr of age, after developing end-stage focal and segmental glomerulosclerosis and hyalinosis. The early post-transplant period was complicated by thrombosis of an arterial branch of the graft and two acute rejection episodes. Because of poor growth, the boy was treated with rhGH starting 22 months after the Tx. The renal function remained relatively stable for 22 months after initiation of rhGH therapy and then progressively deteriorated over a period of 10 months, with the patient ending up on dialysis. Several biopsies, performed for rejection episodes or before the start of rhGH, or to elucidate the deterioration of the renal function, were analyzed. Histologically, a progressive increase in the amount of hypertrophy of the tubules and of the glomeruli was seen after initiation of rhGH. Hyperplasia of the tubular epithelium with crowding of cells of the proximal tubules, hyperchromasia and irregularities in the shape of the nuclei, and abrupt changes of chromatism along the tubuli, were also observed. These lesions of tubular dysplasia are extremely unusual in transplanted kidneys and are unlikely to be caused by compensatory hypertrophy secondary to destruction of renal tissue. They may be an effect of rhGH treatment. The prognostic significance of these lesions is unknown but merits attention.     

An infant case of bilateral small kidneys with both proximal and distal tubular dysfunction

Abstract A male infant with bilateral small kidneys associated with both proximal and distal tubular dysfunction, who showed chronic renal failure soon after birth, is reported. He was also noted to have both proximal and distal type of renal tubular acidosis. The small kidneys were thought to be due to renal hypodysplasia associated with bilateral severe vesicoureteral reflux, by radiological findings. An alkalization therapy with chemo-prophylaxis seemed to be of benefit in slowing the progression of renal failure in this case.     

Renal Granulomatous sarcoidosis in childhood: a report of 11 cases and a review of the literature

We analysed retrospectively 11 children with renal granulomatous sarcoidosis confirmed by renal histology in order to describe the course and prognosis of the disease. Symptomatic sarcoidosis was diagnosed at a mean age of 10.1 years. Nine children had renal involvement at the time of diagnosis. In the course of the disease, nine patients developed renal failure and mild proteinuria, seven had transient sterile leucocyturia, four showed microscopic haematuria, seven had a urinary concentrating defect, and enlarged kidneys were seen in three patients. One child had hypercalcaemia and hypercalciuria, none had hypertension. Light microscopy of the kidney showed interstitial infiltration by mononuclear cells in all children, interstitial fibrosis in nine patients, epithelioid granulomas in seven, tubular involvement in eight, and mild glomerular involvement in seven patients. Renal immunofluorescence was negative. Ten children received prednisone for 1–11 years. After a mean follow up of 5.5 years, three patients had entered end-stage renal failure and one had chronic insufficiency after interruption of medical supervision and prednisone therapy. Conclusion Renal failure, proteinuria, leucocyturia, haematuria, and concentration defect are the prominent features of renal granulomatous sarcoidosis in children. Steroid therapy, adjusted according to disease activity, may prevent end-stage renal failure. Received: 4 December 1997 / Accepted in revised form: 22 June 1998     

Glycogen Accumulation in the Pars Recta of the Proximal Tubule in Fanconi Syndrome

We reviewed the renal pathology in 10 cases of renal Fanconi syndrome. Five cases showed the Armanni-Ebstein lesion, i.e., clear glycogen-filled cells limited to the pars recta of the proximal tubules. The 5 cases included 2 siblings with a unique syndrome characterized by death in infancy, severe Fanconi syndrome, severe rickets, carnitine deficiency, and atrophy of the exocrine pancreas. Two other siblings had glycogen storage disease type XI. One of 4 cases of putative tyrosinemia had the lesion. The ultrastructure was studied in 2 cases. The Armanni-Ebstein lesion in these cases was morphologically indistinguishable from that seen in diabetic patients dying after prolonged hyperglycemia. Glycosuria is the only common factor in both diabetic hyperglycemia and the varied proximal tubular diseases studied. The mechanism of the glycogen accumulation in this short parts recta segment of the proximal renal tubule was further investigated by reviewing the renal histology in cases of glycogen storage disease types I, II, III, and VIII None showed the Armanni-Ebstein lesion, but type I showed glycogen deposition throughout the proximal tubule. Thus, the Armanni-Ebstein lesion is not the result of an enzymatic deficiency for glycogen synthesis in the convoluted tubules.     

Glycogen accumulation in the pars recta of the proximal tubule in Fanconi syndrome

We reviewed the renal pathology in 10 cases of renal Fanconi syndrome. Five cases showed the Armanni-Ebstein lesion, i.e., clear glycogen-filled cells limited to the pars recta of the proximal tubules. The 5 cases included 2 siblings with a unique syndrome characterized by death in infancy, severe Fanconi syndrome, severe rickets, carnitine deficiency, and atrophy of the exocrine pancreas. Two other siblings had glycogen storage disease type XI. One of 4 cases of putative tyrosinemia had the lesion. The ultrastructure was studied in 2 cases. The Armanni-Ebstein lesion in these cases was morphologically indistinguishable from that seen in diabetic patients dying after prolonged hyperglycemia. Glycosuria is the only common factor in both diabetic hyperglycemia and the varied proximal tubular diseases studied. The mechanism of the glycogen accumulation in this short parts recta segment of the proximal renal tubule was further investigated by reviewing the renal histology in cases of glycogen storage disease types I, II, III, and VIII. None showed the Armanni-Ebstein lesion, but type I showed glycogen deposition throughout the proximal tubule. Thus, the Armanni-Ebstein lesion is not the result of an enzymatic deficiency for glycogen synthesis in the convoluted tubules.