Autosomal recessive polycystic kidney disease in adulthood.

BACKGROUND: Renal cysts arising from collecting ducts, congenital hepatic fibrosis, and recessive inheritance characterize autosomal recessive polycystic kidney disease (ARPKD). The disorder usually manifests in infancy, with a high mortality rate in the first year of life. For the patients who survive the neonatal period, the probability of being alive at 15 years of age ranges from 50 to 80%, with 56--67% of them not requiring renal replacement therapy at that stage. Some develop portal hypertension. Long-term outcome of adults escaping renal insufficiency above age 18 is largely unknown. METHOD: In consecutive patients with ARPKD and autonomous renal function at age 18, clinical course of kidney and liver disease in adulthood and status at last follow-up were evaluated. Progression of renal insufficiency was assessed by the rate of decline of creatinine clearance, according to Schwartz's formula before age 18 and Cockcroft and Gault formula thereafter. Severity of liver involvement was estimated by imaging techniques, liver function tests, and endoscopy. RESULTS: Sixteen patients from 15 families were included. ARPKD was diagnosed between 1 day and 13 years of age. From diagnosis, mean follow-up period lasted 24+/-9 years. Before age 18, nine patients (56%) were hypertensive, nine (56%) had renal failure, and four (25%) had portal hypertension. Beyond age 18, no additional patient became hypertensive, and another five developed progressive renal insufficiency; altogether, the mean yearly decline of creatinine clearance was 2.9+/-1.6 ml/min. Portal hypertension was recognized in two additional patients. Four patients experienced gastro-oesophageal bleeding, while recurrent cholangitis or cholangiocarcinoma developed in one case each. At the end of follow-up, 15/16 patients (94%) were alive at a mean age of 27 (18--55) years. Two patients had a normal renal function, 11 had chronic renal insufficiency, one was on regular dialysis, and two had functioning kidney grafts. Four patients had required a porto-systemic shunt. CONCLUSIONS: A subset of ARPKD patients with autonomous renal function at age 18 experiences slowly progressive renal insufficiency. With prolonged renal survival, complications related to portal hypertension are not rare, requiring careful surveillance and appropriate management.     

Role of CFTR in autosomal recessive polycystic kidney disease

An extensive body of in vitro data implicates epithelial chloride secretion, mediated through cystic fibrosis transmembrane conductance regulator (CFTR) protein, in generating or maintaining fluid filled cysts in MDCK cells and in human autosomal dominant polycystic kidney disease (ADPKD). In contrast, few studies have addressed the pathophysiology of fluid secretion in cyst formation and enlargement in autosomal recessive polycystic kidney disease (ARPKD). Murine models of targeted disruptions or deletions of specific genes have created opportunities to examine the role of individual gene products in normal development and/or disease pathophysiology. The creation of a murine model of CF, which lacks functional CFTR protein, provides the opportunity to determine whether CFTR activity is required for renal cyst formation in vivo. Therefore, this study sought to determine whether renal cyst formation could be prevented by genetic complementation of the BPK murine model of ARPKD with the CFTR knockout mouse. The results of this study reveal that in animals that are homozygous for the cystic gene (bpk), the lack of functional CFTR protein on the apical surface of cystic epithelium does not provide protection against cyst growth and subsequent decline in renal function. Double mutant mice (bpk -/-; cftr -/-) developed massively enlarged kidneys and died, on average, 7 d earlier than cystic, non-CF mice (bpk -/-; cftr +/+/-). This suggests fundamental differences in the mechanisms of transtubular fluid secretion in animal models of ARPKD compared with ADPKD.     

Efficacy of chloramphenicol in refractory cyst infections in autosomal dominant polycystic kidney disease

We previously predicted that highly lipid soluble antibiotics would be very effective in the treatment of infected cysts in autosomal dominant polycystic kidney disease (ADPKD). This study examines the use of chloramphenicol, a lipid soluble antibiotic with a therapeutic spectrum covering most gram negative organisms, in the treatment of patients with infected polycystic cysts who had not responded to initial antibiotic therapy. Intravenous chloramphenicol was used in five hospitalized patients with serious infections of the renal cysts. Three of the five patients had positive blood cultures. E. coli was grown in all five patients, in three from blood, in two from urine, and four of five patients were initially treated with antibiotics to which the organism was sensitive. Despite favorable sensitivities, none of the reported patients showed clinical response to initial antibiotic therapy. Chloramphenicol treatment was subsequently effective in all cases. One patient ultimately developed an infection with a chloramphenicol resistant organism. We conclude that chloramphenicol is effective in the treatment of infected cysts in ADPKD but that care must be taken in the use of this agent as selection of resistant organisms may occur in patients with recurrent cyst infections.     

The renin-angiotensin system and hypertension in autosomal recessive polycystic kidney disease

Hypertension is a well-recognized complication of autosomal recessive polycystic kidney disease (ARPKD). The renin-angiotensin system (RAS) is a key regulator of blood pressure; however, data on the RAS in ARPKD are limited and conflicting, showing both up- and down-regulation. In the current study, we characterized intrarenal and systemic RAS activation in relationship to hypertension and progressive cystic kidney disease in the ARPKD orthologous polycystic kidney (PCK) rat. Clinical and histological measures of kidney disease, kidney RAS gene expression by quantitative real-time PCR, angiotensin II (Ang II) immunohistochemistry, and systemic Ang I and II levels were assessed in 2-, 4-, and 6-month-old cystic PCK and age-matched normal rats. PCK rats developed hypertension and progressive cystic kidney disease without significant worsening of renal function or relative kidney size. Intrarenal renin, ACE and Ang II expression was increased significantly in cystic kidneys; angiotensinogen and Ang II Type I receptor were unchanged. Systemic Ang I and II levels did not differ. This study demonstrates that intrarenal, but not systemic, RAS activation is a prominent feature of ARPKD. These findings help reconcile previous conflicting reports and suggest that intrarenal renin and ACE gene upregulation may represent a novel mechanism for hypertension development or exacerbation in ARPKD.     

Recurrent bacteremia with enteric pathogens in recessive polycystic kidney disease

Eight children with autosomal recessive polycystic kidney disease (ARPKD) and recurrent bacteremia with enteric pathogens are described. Typical clinical features of bacterial cholangitis were absent, although in five patients histological and/or microbiological data indicated that the bacteremic episodes originated in the biliary tree. Bacteremia with enteric pathogens or recurrent culture-negative febrile illness in a child with ARPKD should raise suspicion of cholangitis, even in the absence of typical clinical findings. Received: 10 February 1999 / Revised: 15 March 1999 / Accepted: 16 March 1999     

Renal and biliary abnormalities in a new murine model of autosomal recessive polycystic kidney disease

Current models of autosomal recessive polycystic kidney disease (ARPKD) fail to demonstrate biliary abnormalities in association with renal cysts. We therefore studied a new murine model of ARPKD in which dual renal tubular and biliary epithelial abnormalities are present. Affected homozygous animals typically die 1 month postnatally in renal failure with progressively enlarged kidneys. Renal cysts shift in site from inner cortical proximal tubules at birth to collecting tubules 20 days later, as determined by segment-specific lectin binding. Increased numbers of mitosis were demonstrated in proximal and collecting tubular cysts. In addition, epithelial hyperplasia was demonstrated morphometrically in the intra- and extrahepatic biliary tract of affected animals. The number of intrahepatic biliary epithelial cells was increased by 50% on postnatal day 5 and by 100% on postnatal day 25 (P<0.01). Despite an increased frequency of chaotic portal areas in mice with renal cysts, no intrahepatic cysts or shape abnormalities of the biliary lumen were detected using biliary casts and morphometry. Additionally there was nonobstructive hyperplastic dilatation of the extrahepatic biliary tract which was linked in all animals to the presence of renal cysts. The hyperplastic abnormalities in both renal and biliary epithelium make this new mouse strain a good model for the study of the dual organ cellular pathophysiology of ARPKD.     

Congenital murine polycystic kidney disease

In the current study, the pathogenesis of proximal tubular cyst formation was studied in an animal model of polycystic kidney disease, the CPK mouse. The specific roles of (a) sodium-potassium adenosine triphosphatase (Na–K ATPase) activity, determined by an enzyme-linked kinetic microassay, (b) proximal tubular epithelial hyperplasia, determined by calculation of mitotic indices, and (c) altered proximal tubular basal lamina formation, determined by immunohistological localization of basal lamina glycoproteins, were investigated at progressive developmental stages of CPK proximal tubular cyst formation. Increases in renal Na–K ATPase were present at the earliest fetal stages of proximal tubular cyst formation, and subsequently paralleled the course of proximal tubular cyst progression. Proximal tubular epithelial hyperplasia, although not present at the earliest stages of cyst formation, was a consistent feature of progressive proximal tubular cystic enlargement. Abnormalities in basal lamina glycoprotein expression were not present at any stage of proximal tubular cyst development. We conclude that increased Na–K ATPase and tubular epithelial hyperplasia are significant features of proximal tubular cyst formation in the CPK mouse.     

Congenital murine polycystic kidney disease

In the current study, the ontogeny of tubular cyst formation was studied in the CPK mouse, a murine strain with autosomal recessive polycystic kidney disease. Utilizing the technique of intact nephron microdissection in addition to standard light and transmission electron microscopy, the earliest morphologic alterations in CPK kidneys were localized in fetal tissue at 17 days of gestation to the distal portion of developing proximal tubules. During disease progression, from birth to 21 days of postnatal age, there was a shift in the site of cystic nephron involvement from proximal tubule to collecting tubules without involvement of other nephron segments. Cysts were enlarged tubular segments which remained in continuity with other portions of the nephron and were not associated with abnormalities in the overall pattern of nephron growth or differentiation. Analysis suggested that alterations in transtubular transport in abnormally shortened proximal tubular segments of juxtamedullary nephrons may have pathogenic importance in the early stages of cyst formation, and that epithelial hyperplasia and cytoskeletal alterations may have a role in progressive proximal tubular cystic enlargement. Cellular hyperplasia of epithelial walls of normally formed tubules was a prominent feature of cyst formation and progressive enlargement in collecting tubules. Such data form the basis for future studies into specific pathophysiological processes which may be operative in specific nephron segments during different stages of cyst formation in the CPK mouse.A preliminary report of this work was presented at the Annual Meeting of the Society for Pediatric Research, Washington DC, USA, May 1986, and has appeared in abstract form (Pediatr Res 20: 446A, 1986)     

Intracranial aneurysms in a child with autosomal recessive polycystic kidney disease

Intracranial aneurysms (ICA) are a well-known feature of autosomal dominant polycystic kidney disease. There is only one report about ICA in an adult patient with autosomal recessive polycystic kidney disease (ARPKD). We observed a 2-year, 6-month old girl with ARPKD and multiple ICA. The family history is negative for kidney disease. The diagnosis of ARPKD was based on the typical findings in ultrasonography and computed tomography. Cystic ectasia of biliary ducts 6.3/4.8 cm in diameter was found in the liver. Arterial hypertension in a range of 140/100–170/120 mm Hg was registered. The child has polyuria, polydipsia and enuresis. Blood urea was 15 mmol/l, creatinine in a range of 120 to 75 μmol/l. One episode of vomiting, dizziness and lethargy was the reason for a brain magnetic resonance imaging. Multiple fusiform and saccular aneurysms in the branches of middle and posterior cerebral arteries were seen bilaterally. The girl is growing well without neurological symptoms during an observation period of 1.5 years. Blood pressure is well controlled with an ACE inhibitor (Enalapril 2.5 mg daily). It was concluded that ICA can be found in patients with ARPKD. Blood pressure control is essential to reduce the risk of intracranial hemorrhage. Received: 2 May 2001 / Revised: 18 July 2001 / Accepted: 23 July 2001     

Pathways of apoptosis in human autosomal recessive and autosomal dominant polycystic kidney diseases

Autosomal dominant polycystic kidney disease (ADPKD) is a major cause of end-stage renal disease in adults. Autosomal recessive (AR) PKD affects approximately 1:20,000 live-born children with high perinatal mortality. Both diseases have abnormalities in epithelial proliferation, secretion, and cell-matrix interactions, leading to progressive cystic expansion and associated interstitial fibrosis. Cell number in a kidney reflects the balance between proliferation and apoptosis. Apoptosis results from extrinsic (ligand-induced, expression of caspase-8) and intrinsic (mitochondrial damage, expression of caspase-9) triggers. Previous studies have suggested a role for apoptosis in PKD cyst formation and parenchymal destruction. Mechanisms underlying apoptosis in human ADPKD and ARPKD were examined by quantitative immunohistochemistry and Western immunoblot analyses of age-matched normal and PKD tissues. Caspase-8 expression was significantly greater in small cysts and normal-appearing tubules than in larger cysts in ADPKD kidneys. Caspase-8 also appeared early in the disease process of ADPKD. In ARPKD, expression of caspase-8 was most pronounced in later stages of the disease and was not confined to a specific cyst size. In conclusion, apoptosis in human ADPKD is an early event, occurring predominantly in normal-appearing tubules and small cysts, and is triggered by an extrinsic factor, but it occurs later in ARPKD.     

Blood pressure and renal function in autosomal dominant polycystic kidney disease

  The purpose of this study was to identify hypertension in children and adolescents in an early stage of autosomal dominant polycystic kidney disease (ADPKD) by the application of ambulatory blood pressure monitoring (ABPM) over 24 h; 32 children and adolescents (mean age 12.3±4.7 years) were examined. The diagnosis was based on family history and ultrasound examination. In 21 children ADPKD was confirmed by molecular genetic analysis. At the time of the study, 45% patients were asymptomatic and all had glomerular filtration rates (GFRs) ≥65 ml/min per 1.73 m². By ABPM, 11 patients (34%) were defined as hypertensive (systolic or diastolic blood pressure >95th percentile), including 4 with an exclusive nocturnal hypertension. Of 7 patients with daytime hypertension, 4 had normal blood pressure by casual measurements. The nocturnal dip in blood pressure was reduced in 2 patients. Blood pressure correlated with renal size, but not with GFR, concentrating capacity, proteinuria, and plasma renin activity. The study reveals an early trend for increased blood pressure in children with ADPKD, requiring close supervision. Received October 18, 1996; received in revised form and accepted March 11, 1997     

Multiorgan mRNA misexpression in murine autosomal recessive polycystic kidney disease

BACKGROUND: BALB/c mice homozygous for the cpk mutation develop a form of polycystic kidney disease (PKD) with multiorgan pathology similar to human autosomal recessive PKD. Messenger RNA expression in multiple affected organs was analyzed to determine if common gene cascades were misexpressed in the cystic kidney and extrarenal sites of disease. In cystic kidneys, misexpressed mRNAs were found in one of four general groups: proliferation/cell growth, apoptosis, differentiation or extracellular matrix. METHODS: RNA was isolated from kidney, liver and pancreas of cystic and normal BALB/c-cpk mice. Using Northern blot hybridization and ribonuclease protection assays (RPA), the expression of several genes thought to be associated with PKD, namely c-myc, epidermal growth factor receptor (EGF-R) and PKD-1, were evaluated. RPAs were used to assess mRNA expression of cyclins and members of the bax/bcl-2 family. In addition, kidney, liver and pancreas were immunostained for c-Myc and PCNA. RESULTS: Cystic kidney, liver and pancreas all exhibited similar patterns of mRNA misexpression of c-myc, EGF-R and PKD-1. In addition, a number of cell proliferation and apoptosis-related mRNAs also were elevated in cystic kidney and pancreas. Renal epithelial cells expressing proliferation-associated proteins [c-Myc and proliferating cell nuclear antigen (PCNA)] were nearly absent in normal kidney; however, cells of cystic and non-cystic renal tubules plus liver and pancreatic cyst exhibited an increased number of nuclei labeled with antibodies to these proteins. CONCLUSIONS: These data suggest that similar pathologic mechanisms (including the expression of c-myc, EGF-R, PKD-1, cyclin, and bax/bcl-2 family mRNAs) may be responsible for the development of cystic changes in kidney, liver and pancreas in murine autosomal recessive PKD. Treatments targeting these similarly misexpressed mRNAs may be efficacious in ameliorating the cystic pathology in the kidney as well as the other affected organs in ARPKD.     

Retinitis pigmentosa associated with autosomal dominant polycystic kidney disease

We report a case of a 35-year-old man with autosomal dominant polycystic kidney disease (ADPKD) who presented for the first time with end-stage renal failure. He had a long history of blurred vision and on examination had retinitis pigmentosa. To our knowledge, this is the second report on the association of retinitis pigmentosa with polycystic kidney disease.     

Retinitis pigmentosa associated with autosomal dominant polycystic kidney disease

SUMMARY: We report a case of a 35-year-old man with autosomal dominant polycystic kidney disease (ADPKD) who presented for the first time with end-stage renal failure. He had a long history of blurred vision and on examination had retinitis pigmentosa. to our knowledge, this is the second report on the association of retinitis pigmentosa with polycystic kidney disease.     

Optimal care of autosomal dominant polycystic kidney disease patients

Autosomal dominant polycystic kidney disease (ADPKD) is the most common life-threatening, hereditary disease. The prevalence of ADPKD is more common than Huntington disease, haemophilia, sickle cell disease, cystic fibrosis, myotonic dystrophy and Down syndrome combined. In recent years there have not only been advances in the understanding of the genetic and molecular events involved in ADPKD, but some diagnostic and therapeutic advances have also emerged. In the genetics area, the gene for PKD1 was localised to chromosome 16, is associated with polycystin-2 protein, and found to account for approximately 85% of patients with ADPKD. The gene for PKD2, found in chromosome 4, accounts for approximately 15% of ADPKD, and is associated with the polycystin-2 protein. While these genetic and molecular biology findings have stimulated a great deal of exciting basic research in ADPKD, therapies to decrease morbidity and mortality in ADPKD patients have yet to emerge from these findings. In contrast, the early diagnosis and treatment of hypertension with inhibitors of the renin-angiotensin-aldosterone system have the potential to decrease or prevent left ventricular hypertrophy cardiac complications and slow the progression of the renal disease.     

Assessment of renal function with color Doppler ultrasound in autosomal dominant polycystic kidney disease

BACKGROUND: Measurement of renal blood flow by color Doppler ultrasound is useful for assessment of renal function in a variety of renal disorders. In autosomal dominant polycystic kidney disease (ADPKD), however, it might be difficult to visualize interlobar arteries because of deformity of renal structure. To evaluate the usefulness of color Doppler in ADPKD, parameters determined by blood flow examination were compared with the results of ordinal renal function tests. METHODS: Twenty-one patients with ADPKD were examined by color Doppler ultrasound measurement. In each patient, 10 interlobar arteries in both kidneys were investigated. Minimum blood flow velocity (Vmin), maximum blood flow velocity (Vmax), mean blood flow velocity (Vmean), acceleration, resistive index and pulsatility index were measured in relation to the results of creatinine clearance, serum creatinine, blood urea nitrogen and 15 and 120 min values of the phenolsulfonphthalein test. RESULTS: In all patients, interlobar arteries were able to be visualized and blood-flow profile was measured. Although variations of Vmin, Vmax, Vmean and acceleration were relatively large, the resistive index and pulsatility index varied little in each kidney. Mean values of Vmin (P < 0.005), Vmean (P < 0.05), resistive index (P < 0.005) and pulsatility index (P < 0.005) were well correlated to creatinine clearance with statistical significance. CONCLUSIONS: In ADPKD, color Doppler ultrasound measurement is a useful method for assessment of renal function and could be used for monitoring the dynamic state of renal blood flow as a non-invasive technique.