Development of human fetal kidney in obstructive uropathy: correlations with ultrasonography and urine biochemistry

In utero urethral obstruction results in bilateral hydronephrosis and severe fetal and post-natal morbidity and mortality. Obstetrical management depends on the indirect evaluation of fetal renal function by ultrasonography and biochemical analysis. No direct evaluation of the severity and possible reversibility of renal lesions is available. In this paper we analyzed kidneys from 34 fetuses (14 to 37 gestational weeks) in which (1) isolated bilateral urinary tract obstruction had been detected in utero by sonography, and (2) the severity of sonographic and biochemical prognostic indicators led to the indication of termination of pregnancy or to perinatal death. Pure hydronephrosis was observed in two young fetuses [14 and 20 gestational weeks (GW)] and was associated with regressive changes in two others. In contrast, a wide spectrum of dysplastic renal lesions was present in 30 fetuses and was classified into four subgroups according to the association of dysplasia, hypoplasia and cysts. They had the following characteristics in common: (1) premature cessation of nephrogenesis assessed by the medullary ray counting method; (2) early disappearance or myofibroblastic differentiation of metanephric blastema; (3) early increase in interstitial mesenchyme with widespread expression of alpha-smooth muscle actin by mesenchymal cells; (4) frequent absence of classical criteria of dysplasia (nests of cartilage were observed in only 5 fetuses); (5) an identification, based upon the detection of alpha-smooth muscle actin expression, of the muscular phenotype of mesenchymal cells encircling primitive ducts. In conclusion, (1) the value of prognostic markers in fetuses less than 20 GW should be reconsidered; (2) after 20 GW there is a good correlation between markers predicting poor prognosis and the severity of renal lesions; (3) hypoplasia with disappearance of blastema cells, dysplasia and early interstitial fibrosis are evidence of the irreversibility of renal lesions and preclude any possibility of new nephron formation; (4) these findings suggest that most surgical in utero procedures are performed when irreversible renal lesions have developed.

Distribution of alpha-integrin subunits in fetal polycystic kidney diseases

An alteration in cell/matrix interactions is one of the suggested mechanisms leading to cyst formation in polycystic kidney diseases. Most of these interactions are mediated by beta 1-integrins, a subfamily of integrin receptors, formed by the association of the beta 1-chain with different alpha-subunits. To date, no study on alpha-integrin subunit distribution during the early stages of cyst development has been reported. Using immunofluorescence, we analyzed the distribution of alpha-integrin subunits (alpha 1, alpha 2, alpha 3, alpha 5, and alpha 6) and basement membrane proteins in kidneys of fetuses with autosomal dominant (ADPKD) or autosomal recessive polycystic kidney disease (ARPKD). The distribution was compared with that observed in normal fetal and post-natal kidneys, and in fetal cystic dysplasia and Meckel syndrome. Marked increase in alpha 1-integrin staining was observed in normal and cystic collecting duct cells of both polycystic diseases (PKD), compared with normal and cystic controls. The distribution of integrin subunits alpha 2, alpha 3, and alpha 6 was irregular in cyst epithelial cells of PKD and cystic controls. The increased expression of the alpha 1-subunit specifically observed in PKD collecting duct cells may be an early consequence of the genetic defect in ARPKD. In ADPKD it parallels the reported expression of polycystin, the protein product of PKD1. The irregular expression of alpha 2, alpha 3, and alpha 6 integrin subunits observed in all types of cysts suggests that cell/matrix interactions are altered early and may participate in the development of cysts, perhaps by contributing to the deregulation of cell survival in cystic diseases.

Diffuse leiomyomatosis associated with X-linked Alport syndrome: extracellular matrix study using immunohistochemistry and in situ hybridization

Inherited diffuse esophageal leiomyomatosis a benign tumor involving smooth muscle cells of the whole esophagus, is frequently associated with X-linked Alport syndrome, a hereditary disease of type IV collagen. Families with this condition are consistently found to have deletions encompassing the 5' ends of both the alpha 5 chain of type IV collagen (COL4A5) and the alpha 6 chain of type IV collagen (COL4A6) genes, always limited in COL4A6 to exons 1', 1, and 2. On the contrary, patients with COL4A5/COL4A6 deletions extending further into COL4A6 display no such tumors. Despite the deletion, a COL4A6 transcript including exon 4, but not exon 3, was found in a tumor sample, raising the possibility of the involvement of a truncated alpha 6(IV) chain in the tumorous process. Using immunohistochemistry and in situ hybridization methods, we analyzed the expression and distribution of the alpha 6 chain of type IV collagen in tumors in comparison with that of normal, fetal, and mature esophagus. We also studied associated changes in tumor basement membrane composition and in tumor-cell integrin subunit distribution. No labeling with alpha 6(IV) antibodies was detected in tumors, ruling out the hypothesis of a stably integrated truncated alpha 6(IV) chain in tumor basement membranes. In contrast, despite the deletions of the first two exons of the gene and its 5' end, a COL4A6 transcript is clearly expressed by tumor cells. This finding raises the question of a potential role for this RNA in the tumor process. The absence of the alpha 6(IV) chain is associated with the absence of the alpha 5(IV) chain, as was suggested by the COL4A5 deletion. An additional striking feature is the absence of the beta 1 chain of laminin in tumor basement membranes and the lack of or uneven expression of the alpha 5 integrin subunit. These findings show that dramatic changes in the composition of the matrix and the expression of integrin receptors also occur in this benign tumorous process.

Renal failure from mitochondrial cytopathies

Mitochondrial cytopathies are metabolic diseases, expressing mutations in nuclear DNA, punctiform mutations or depletions in mitochondrial DNA. These genetic lesions alter mitochondrial oxidative phosphorylation, with a reduction in energy produced for cell activity. Renal disease may be the first sign of mitochondrial cytopathy, or it may appear together with neurological and neuromuscular signs. Fanconi's syndrome, a benign sign of renal tubulopathy, is particularly frequent in newborns with mitochondrial cytopathy, whereas tubulointerstitial nephropathy, which affects infants and adults, is more serious because it develops into terminal uremia. Findings of hyperlactatemia and reduced enzymatic activity on the respiratory chain in tissue biopsies are of diagnostic significance in mitochondrial cytopathy. A breakthrough is being made in our understanding of genetic alterations in mitochondrial DNA, and with future therapy, the kidney, a target organ, may be safeguarded.

Spectrum of mutations in the COL4A5 collagen gene in X-linked Alport syndrome

Alport syndrome is a mainly X-linked hereditary disease of basement membranes that is characterized by progressive renal failure, deafness, and ocular lesions. It is associated with mutations of the COL4A5 gene located at Xq22 and encoding the alpha5 chain of type IV collagen. We have screened 48 of the 51 exons of the COL4A5 gene by SSCP analysis and have identified 64 mutations and 10 sequence variants among 131 unrelated Alport syndrome patients. This represents a mutation-detection rate of 50%. There were no hot-spot mutations and no recurrent mutations in our population. The identified mutations were 6 nonsense mutations, 12 frameshift mutations, 17 splice-site mutations, and 29 missense mutations, 27 of the latter being glycine substitutions in the collagenous domain. Two of these occurred on the same allele in one patient and segregated with the disease in the family. We showed that some of the glycine substitutions could be associated with the lack of immunological expression of the alpha3(IV)-alpha5(IV) collagen chains in the glomerular basement membrane.

Long-term (15-25 years) outcome of childhood hemolytic-uremic syndrome

The short-term prognosis of the "typical", "post-enteropathic" form of infantile HUS is usually good, with a complete recovery of renal function. However, the extent of the renal damage observed on some biopsies may raise concern for the long-term prognosis. Therefore, we studied the outcome of 29 patients affected with classical HUS in infancy or early childhood and followed-up for 15-28 years (m = 18 yrs). Initial renal symptoms ranged from a moderate renal failure with normal diuresis to a 12-day anuria: 21 children had to be treated by peritoneal dialysis. Twenty-five patients underwent a renal biopsy shortly after recovery: lesions of glomerular thrombotic microangiopathy (TMA) were found in 14 patients, and patchy cortical necrosis was diagnosed in the other 11. At latest examination 10 patients had no renal abnormality, 12 had residual renal symptoms (hypertension in 7, proteinuria in 4 and midly reduced GFR in 1), 3 were in chronic renal failure (CRF), and 4 had reached end-stage renal failure (ESRF) 16-24 years after onset; 2 of these latter 4 had a normal GFR at 10-year examination. The long-term evolution was not correlated with the initial clinical severity but appeared well correlated with the extent of the histological damage: 10 of the 11 patients with cortical necrosis have either ESRF (4), CRF (3) or renal sequelae (3), and 4 of the 5 patients with TMA involving more than 50% of glomeruli present with moderate sequelae, whereas the 9 patients with TMA involving less than 50% of glomeruli are symptom-free or have mild sequelae. Thus, the risk of renal failure 20 years after a seemingly cured childhood HUS is not negligible, and renal histology is the best indicator of long-term prognosis.

Collagen distribution in focal and segmental glomerulosclerosis: an immunofluorescence and ultrastructural immunogold study

Focal and segmental glomerulosclerosis (FSGS) is a non-specific scarring process of the glomerulus, initially described in idiopathic nephrotic syndrome. The distribution of types I, III, IV, V, and VI collagen and of the alpha 1, alpha 3, alpha 4, alpha 5, and alpha 6 chains of type IV collagen was studied by immunohistochemistry in sclerotic lesions of nine nephrotic children. Dual immunofluorescence and high-resolution immunogold labelling were used to determine the precise distribution of the antigens. No changes were detected in normal glomeruli of patients compared with controls. In FSGS, type IV collagen [alpha 1(IV)2 alpha 2(IV)], and to a lesser degree type VI, accumulates in the two components of the lesion: the enlarged mesangial matrix and the material deposited between the pushed-out podocytes and the alpha 3-alpha 5(IV)-positive glomerular basement membrane. Staining for alpha 6(IV) and types I, III, and V collagen was practically negative. These results suggest that the matrix components of the sclerotic lesion are produced solely by glomerular cells. Changes in the relative distribution of type IV collagen chains, characterized by the presence of collagen [alpha 1(IV)2 alpha 2(IV)] in close contact with the podocytes, strongly suggest a switch in the podocyte programme of collagen synthesis.

Congenital nephrotic syndrome of the Finnish type: linkage to the locus in a non-Finnish population

Congenital nephrotic syndrome of the Finnish type (CNF) is inherited as an autosomal recessive trait. The biochemical basis of the disease is unknown, although a lesion in the glomerular basement membrane is strongly suggested. Recently, the CNF locus was assigned to chromosome 19q12-q13.1 on the basis of linkage analysis in Finnish families. The high incidence of the disease in Finland, as well as the demonstration of linkage disequilibrium in the Finnish study, strongly suggests a founder effect based on a common ancient mutation in this population. We confirm linkage of the CNF locus to the same chromosomal region in seven non-Finnish CNF families without evidence of linkage disequilibrium. Our results show that the same gene seems to be affected in both Finnish and non-Finnish CNF populations. However, in the latter the mutation-carrying chromosomes descend from different ancestors without evidence of a founder effect.

Large homozygous deletions of the 2q13 region are a major cause of juvenile nephronophthisis

Juvenile nephronophthisis (NPH) is a genetically heterogeneous disorder representing the most frequent inherited cause of chronic renal failure in children. We recently assigned a gene (NPH1) to the 2q13 region which is responsible for approximately 85% of cases. Cloning this region in a yeast artificial chromosome contig revealed the presence of low copy repeats. Large-scale rearrangements were detected in 80% of the patients belonging to inbred or multiplex NPH1 families and in 65% of the sporadic cases. Surprisingly, these rearrangements seem to be, in most cases, large homozygous deletions of approximately 250 kb involving an 100 kb inverted duplication. This suggests a common genetic disease-causing mechanism, which could be responsible for the highest frequency of large rearrangements reported in an autosomal recessive trait. Our findings are also of major clinical interest, as they permit the diagnosis in the majority of sporadic cases without the need for kidney biopsy.

Collagen distribution in human membranous glomerulonephritis

In membranous glomerulonephritis (MGN), thickening of the glomerular basement membrane (GBM) is partly due to the accumulation of basement membrane material between and around immune deposits located on the epithelial aspect of the GBM. We investigated the distribution of type IV collagen chains (alpha 1/alpha 2, alpha 3, alpha 4, alpha 5, alpha 6) and of types I, III, V, and VI collagen in the glomeruli from 16 patients, by indirect immunofluorescence in 13 and the high-resolution immunogold technique in 6. No changes were detected in stage I MGN. The spiky projections of the GBM in stage II MGN and the basement membrane layers encircling immune deposits in stage III contained the alpha 3, alpha 4, and alpha 5 chains of type IV collagen. In contrast, the alpha 1/alpha 2 chains of type IV, as well as type VI collagen accumulated in the subendothelial aspect of the GBM. No significant staining for types I, III, and V collagens or for the alpha 6 chain of type IV collagen was detected. The results show that, as in the normal glomeruli, the different chains of type IV collagen are not co-distributed in the glomerular extracellular matrix in MGN. They also indicate that type IV collagen chains and type IV collagen play an important role in the thickening of the GBM in human MGN.

[Value of cyclosporine in the treatment of the recurrence of nephrosis after renal transplantation]

From May 1992 to December 1994, 14 children with end stage renal failure secondary to steroid-resistant idiopathic nephrotic syndrome received a cadaver kidney graft. Immediate recurrence of the nephrotic syndrome occurred in four patients. In the four patients, a complete remission was observed shortly after the start of intravenous cyclosporin; two children received in addition methylprednisolone pulses for secondary rejection. Two children were still protein-free 9 and 15 months after transplantation. In the third patient, proteinuria relapsed after 9 months of complete remission and persisted in spite of the reintroduction of intravenous cyclosporin. The fourth graft was lost at 3.5 month from irreversible rejection. The creatinine clearance of the 3 functioning grafts was respectively: 73, 76 and 92 ml/mn/1.73 m2 16, 10 and 15 months after transplantation. Intravenous cyclosporin started shortly after the recurrence, maintaining blood levels between 200 and 300 ng/ml, may induce a remission in recurrent nephrotic syndrome after renal transplantation in childhood.

A 11 Mb YAC-based contig spanning the familial juvenile nephronophthisis region (NPH1) located on chromosome 2q

A gene (NPH1) responsible for approximately 90% of the purely renal form of familial juvenile nephronophthisis, a progressive tubulo-interstitial kidney disorder, maps to human chromosome 2. We report the construction of a YAC-based contig spanning the critical NPH1 region and the flanking genetic markers. This physical map was integrated with a refined genetic map that restricted the NPH1 interval to about 2 cM; this interval corresponds to a maximum physical distance of 3.5 Mb. The entire contig covers 9 cM between the loci D2S135 and D2S121. The maximum physical distance between these two markers is approximately 11.3 Mb. Forty-five sequence-tagged sites, including six genes, have been located within this contig. PAX8, a member of the human paired box gene family, that is expressed in the developing kidney, was assigned outside the restricted NPH1 critical region and cannot therefore be regarded as a candidate gene. This set of overlapping clones represents a useful resource for further targeted development of genetic markers and for the characterization of candidate genes responsible for juvenile nephronophthisis.

Mapping a gene (SRN1) to chromosome 1q25-q31 in idiopathic nephrotic syndrome confirms a distinct entity of autosomal recessive nephrosis

Idiopathic nephrotic syndrome (INS) in childhood is characterized by massive proteinuria and minimal glomerular changes. Most patients with INS respond to steroid therapy. INS is generally regarded as a sporadic disease with favorable outcome. We investigated a distinct subgroup of nephrosis--the familial form of steroid resistant INS (SRN). These patients always progress to end-stage renal failure within a few years and show absence of recurrence of the disease after renal transplantation. The occurrence of the disorder in siblings and the high incidence of inbreeding in these families made an autosomal recessive mode of inheritance very likely. We performed whole genome linkage analysis in nine multiplex families of European or Northern African origin. Our results allowed us to assign a disease locus (SRN1) to a defined chromosomal region on 1q25-1q31, thus confirming the existence of a distinct entity of autosomal recessive nephrosis. Exclusion of linkage to the entire region in one family proves genetic heterogeneity.

Distribution and ontogenesis of tenascin in normal and cystic human fetal kidneys

BACKGROUND

Tenascin is a mesenchymal extracellular matrix glycoprotein transiently expressed during development, mainly at the site of epithelial-mesenchymal interactions. It is thought to play a key role in morphogenesis. Little is known about the distribution of tenascin in normal human fetal kidney, and, so far, no data have been reported concerning the distribution of the protein in fetal cystic kidneys.

EXPERIMENTAL DESIGN

Using specific mAb and the immunofluorescence technique, we analyzed the distribution of tenascin in normal human embryonic (n = 3), fetal (n = 15), and mature kidneys (n = 4) and in fetuses affected with autosomal recessive polycystic disease (n = 3), autosomal dominant polycystic disease (n = 3), and cystic dysplasia (n = 3). We compared the distribution of this protein with that of fibronectin and types I, III, V, and VI collagens.

RESULTS

In normal developing kidneys, tenascin is present in the uninduced blastema and in the mesenchyme around differentiating nephrons. It is homogeneously distributed in the inner cortex and in the medulla. During maturation, tenascin expression persists in the medulla but progressively decreases in the cortex. Tenascin is present in the mesangial area from the S-shaped body stage. Both types of polycystic diseases are characterized by a marked and diffuse increase in cortical and medullary expression of tenascin as well as types III, V, and VI collagen. In cystic dysplasia, two types of changes were observed: (a) increased tenascin and interstitial collagen expression in the subcapsular strips of condensed mesenchyme; and (b) heterogeneous medullary tenascin distribution with positive labeling of the condensed mesenchyme surrounding cysts and primitive ducts and negative labeling of the loose interstitial mesenchyme, contrasting with the diffuse accumulation of types III, V, and VI collagen.

CONCLUSIONS

In the human fetal kidney, tenascin is expressed by blastema cells and disappears when converted to epithelium. In polycystic diseases, an early increase in tenascin and interstitial collagen expression suggests that renal mesenchyme per se may contribute to the progressive alteration of the kidney. In cystic dysplasia, phenotypic changes in metanephric blastema indicate inappropriate commitment of blastema cells into interstitial cells, leading to the definitive arrest of nephrogenesis; the heterogeneity in tenascin medullary expression underlines the heterogeneity in the mesenchymal cell population.

Deleterious effects of inhibition of the renin-angiotensin system in neonatal rats

The angiotensin I converting enzyme inhibitor (ACEI) perindopril (2 mg/kg body weight), the peripheral vasodilator dihydralazine (DHL) (25 mg/kg body weight) or distilled water was given daily from birth to day 14 to neonatal rats. Blood pressure, plasma creatinine, plasma renin activity (PRA), substrate (PRS) and concentration (PRC) and renin content of kidney tissue sections were evaluated on days 14 and 28. By day 14, a high mortality in the ACEI group was observed. ACEI, but not DHL, led to a significant fall (P < 0.01) in blood pressure, 57 +/- 11 versus 89 +/- 25 in the DHL group and 103 +/- 24 mmHg in controls, and to a dramatic increase in plasma creatinine. PRA and PRS were undetectable in ACEI-treated rats; in contrast, PRC and renal staining with anti-renin antibody were significantly increased in ACEI rats. On day 28, the blood pressure was normal in all groups and plasma creatinine returned to the normal range in ACEI rats. PRA, PRS and PRC were not significantly different in the ACEI group and controls. These results suggest that the renin-angiotensin system (RAS) plays a major postnatal role in the neonatal rat. Inhibition of the RAS during the first 2 weeks of life leads to high mortality, severe hypotension, reversible renal failure and a defect in circulating angiotensinogen.

Autosomal recessive Alport syndrome: immunohistochemical study of type IV collagen chain distribution

Alport syndrome (AS) is an hereditary disease of basement membrane collagen. It is mainly transmitted as a dominant X-linked trait and caused by mutations in the COL4A5 gene encoding the alpha 5 chain of type IV collagen. However, autosomal recessive AS due to mutations in the COL4A3 or COL4A4 genes could represent up to 15% of AS. Using the immunofluorescence technique, we analyzed the distribution of the different chains of type IV collagen in renal (12 specimens) and skin (4 specimens) basement membranes of 12 AS patients belonging to 11 unrelated kindreds in which autosomal recessive inheritance had been demonstrated (3 kindreds) or was suggested by clinical and genealogic data (8 kindreds). The renal and skin distribution was normal in one patient with COL4A4 mutations. A peculiar pattern of distribution of the alpha 3-alpha 5(IV) chains was observed in the other patients. It was characterized the co-absence of the alpha 3(IV), alpha 4(IV) and alpha 5(IV) chains in the glomerular basement membrane, and the presence of the alpha 5(IV) chain in a series of extraglomerular basement membranes including capsular, collecting ducts and epidermal basement membranes, a combination never observed in X-linked AS. This immunohistochemical pattern is correlated with the specific distribution of the alpha 3-alpha 5 chains of type IV collagen chains within extraglomerular basement membranes. It could be a useful marker for the identification of autosomal recessive AS.

Deletion of mitochondrial DNA in patient with chronic tubulointerstitial nephritis

We report a mitochondrial DNA deletion (2.6 kb) in a boy with tubulointerstitial nephritis in whom chronic renal failure and leukodystrophy subsequently developed. Elevated lactate values in plasma and cerebrospinal fluid were suggestive of a defect in the mitochondrial respiratory chain. High amounts of deleted mitochondrial DNA were present in muscle and cerebral white matter. On the basis of this observation, we suggest giving consideration to genetic defects of oxidative phosphorylation in any attempt to determine the origin of unexplained chronic tubulointerstitial nephritis, especially when seemingly unrelated organs are involved.

Structural-functional relationships in Alport syndrome

Renal morphometric analysis was performed in 15 (13 male) Alport syndrome patients ages 4 to 26 years, along with 10 controls ages 3 to 26 years, to better understand the structural basis of renal dysfunction in Alport syndrome. The glomerular basement membrane (GBM) width class frequencies of controls were normally distributed; those of Alport syndrome patients were slightly skewed, especially toward thicker classes, although there was also an increase in the proportion of thinner classes. Mesangial volume fraction was not different between Alport syndrome patients (0.21 +/- 0.09) and controls (0.19 +/- 0.04). There was an inverse correlation between mesangial volume fraction and creatinine clearance in Alport syndrome patients (r = -0.72, P < 0.01); however, the creatinine clearances in Alport syndrome patients were far less than in insulin-dependent diabetic patients with similar mesangial volume fraction. Similarly, there was no significant difference in the surface density of the peripheral GBM (in square micrometers per cubic micrometer) in Alport syndrome patients (0.12 +/- 0.04) versus controls (0.13 +/- 0.02). The surface density of the peripheral GBM correlated with creatinine clearance in Alport syndrome patients (r = 0.71, P < 0.01). However, there was a greater reduction in creatinine clearance as related to declining the surface density of the peripheral GBM in Alport syndrome than in diabetic patients. The cortical interstitial volume fraction was highly inversely correlated with creatinine clearance in Alport syndrome patients (r = -0.85, P < 0.01). Global glomerular sclerosis was 0% in five and 5 to 61% in nine Alport syndrome patients and correlated inversely with creatinine clearance (r = -0.74, P < 0.01). However, the creatinine clearance was lower in Alport syndrome than in diabetic patients with similar cortical interstitial volume fraction and percent glomerular sclerosis. There was no significant difference in an index of glomerular number between Alport syndrome patients and controls. Thus, changes in mesangial volume fraction, cortical interstitial volume fraction, percent glomerular sclerosis, and surface density of the peripheral GBM in Alport syndrome patients only partially account for the reduction in creatinine clearance. It was speculated that decreased glomerular capillary wall hydraulic conductivity in Alport syndrome could explain many of these observations.

Identification of mutations in the alpha 3(IV) and alpha 4(IV) collagen genes in autosomal recessive Alport syndrome

Alport syndrome (AS) is an hereditary disease of basement membranes characterized by progressive renal failure and deafness. Changes in the glomerular basement membrane (GBM) in AS suggest that the type IV collagen matrix, the major structural component of GBM, is disrupted. We recently isolated the genes for two type IV collagens, alpha 3(IV) and alpha 4(IV), that are encoded head-to-head on human chromosome 2. These chains are abundant in normal GBM but are sometimes absent in AS. We screened for mutations in families in which consanguinity suggested autosomal recessive inheritance. Homozygous mutations were found in alpha 3(IV) in two families and in alpha 4(IV) in two others, demonstrating that these chains are important in the structural integrity of the GBM and that there is an autosomal form of AS in addition to the previously-defined X-linked form.

Persistent anuria, neonatal death, and renal microcystic lesions after prenatal exposure to indomethacin

OBJECTIVE

The purpose of this study is to emphasize the high risk of renal failure and severe morphologic changes related to prolonged prenatal exposure to indomethacin.

STUDY DESIGN

Referred renal specimens from six anuric neonates exposed in utero to indomethacin were studied. Clinical charts were retrospectively reviewed. Indomethacin dosages varied from 150 to 400 mg daily, and the drug was given for a 2- to 11-week period, until birth.

RESULTS

All infants died in anuria, 4 of them after 7 to 39 days on peritoneal dialysis. In 5 infants cystic dilatations of superficial nephrons were associated with ischemic changes of the deep cortex. By immunohistochemical analysis intrarenal renin content was increased in 4 of 5 patients.

CONCLUSION

Long-term indomethacin treatment during pregnancy may lead to the development of renal failure and irreversible renal damage with cystic dilatation of developing nephrons in an exposed fetus. Prior stimulation of the renin-angiotensin system may favor this complication.