Magnetic Resonance Imaging Evaluation of Hepatic Cysts in Early Autosomal-Dominant Polycystic Kidney Disease: The Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease Cohort

Health-related quality of life in patients with autosomal dominant polycystic kidney disease and CKD stages 1-4: a cross-sectional study

BACKGROUND

In people with early autosomal dominant polycystic kidney disease (ADPKD), average total kidney volume (TKV) is 3 times normal and increases by an average of 5% per year despite a seemingly normal glomerular filtration rate (GFR). We hypothesized that increased TKV would be a source of morbidity and diminished quality of life that would be worse in patients with more advanced disease.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

1,043 patients with ADPKD, hypertension, and a baseline estimated GFR (eGFR)> 20mL/min/1.73m(2).

PREDICTORS

(1) eGFR, (2) height-adjusted TKV (htTKV) in patients with eGFR> 60mL/min/1.73m(2).

OUTCOMES

36-Item Short Form Health Survey (SF-36) and the Wisconsin Brief Pain Survey.

MEASUREMENTS

Questionnaires were self-administered. GFR was estimated from serum creatinine using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. htTKV was measured by magnetic resonance imaging.

RESULTS

Back pain was reported by 50% of patients, and 20% experienced it "often, usually, or always." In patients with early disease (eGFR> 60mL/min/1.73m(2)), there was no association between pain and htTKV, except in patients with large kidneys (htTKV> 1,000mL/m). Comparing across eGFR levels and including patients with eGFRs< 60mL/min/1.73m(2), patients with eGFRs of 20-44mL/min/1.73m(2) were significantly more likely to report that pain impacted on their daily lives and had lower SF-36 scores than patients with eGFRs of 45-60 and ≥60mL/min/1.73m(2). Symptoms relating to abdominal fullness were reported by 20% of patients and were related significantly to lower eGFRs in women, but not men.

LIMITATIONS

TKV and liver volume were not measured in patients with eGFR < 60mL/min/1.73m(2). The number of patients with eGFRs< 30mL/min/1.73m(2) is small. Causal inferences are limited by cross-sectional design.

CONCLUSIONS

Pain is a common early symptom in the course of ADPKD, although it is not related to kidney size in early disease (eGFR> 60mL/min/1.73m(2)), except in individuals with large kidneys (htTKV> 1,000 mL/m). Symptoms relating to abdominal fullness and pain are greater in patients with more advanced (eGFR, 20-45mL/min/1.73m(2)) disease and may be due to organ enlargement, especially in women. More research about the role of TKV in quality of life and outcomes of patients with ADPKD is warranted.

From bone abnormalities to mineral metabolism dysregulation in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic cause of kidney failure. It is a systemic disorder, not only affecting the kidneys, but also associated with cyst formation in other organs such as the liver, spleen, pancreas, and seminal vesicles. Other extra-renal symptoms may consist of intracranial arterial aneurysms, cardiac valvular defects, abdominal and inguinal hernias and colonic diverticulosis. Very little is known regarding bone involvement in ADPKD; however, recent evidence has revealed the potential role of fibroblast growth factor 23 (FGF23). FGF23 is an endocrine fibroblast growth factor acting in the kidney as a phosphaturic hormone and a suppressor of active vitamin D with key effects on the bone/kidney/parathyroid axis, and has been shown to increase in patients with ADPKD, even with normal renal function. The aim of this review is to provide an overview of bone and mineral abnormalities found in experimental models and in patients with ADPKD, and to discuss the possible role of FGF23 in this disease.

Novel approach to estimate kidney and cyst volumes using mid-slice magnetic resonance images in polycystic kidney disease

OBJECTIVE

To evaluate whether kidney and cyst volumes can be accurately estimated based on limited area measurements from magnetic resonance (MR) images of patients with autosomal dominant polycystic kidney disease (ADPKD).

MATERIALS AND METHODS

MR coronal images of 178 ADPKD participants from the Consortium for Radiologic Imaging Studies of ADPKD (CRISP) were analyzed. For each MR image slice, we measured kidney and renal cyst areas using stereology and region-based thresholding methods, respectively. The kidney and cyst 'observed' volumes were calculated by summing up the area measurements of all the slices covering the kidney. To estimate the volume, we selected a coronal mid-slice in each kidney and multiplied its area by the total number of slices ('PANK2' for kidney and 'PANC2' for cyst). We then compared the kidney and cyst volumes predicted from PANK2 and PANC2, respectively, to the corresponding observed volumes, using a linear regression analysis.

RESULTS

The kidney volume predicted from PANK2 correlated extremely well with the observed kidney volume (R(2) = 0.994 for the right kidney and 0.991 for the left kidney). The linear regression coefficient multiplier to PANK2 that best fit the kidney volume was 0.637 (95% CI: 0.629-0.644) for the right kidney and 0.624 (95% CI: 0.616-0.633) for the left kidney. The correlation between the cyst volume predicted from PANC2 and the observed cyst volume was also very high (R(2) = 0.984 for the right kidney and 0.967 for the left kidney). The least squares linear regression coefficient for PANC2 was 0.637 (95% CI: 0.624-0.649) for the right kidney and 0.608 (95% CI: 0.591-0.625) for the left kidney.

CONCLUSION

Kidney and cyst volumes can be closely approximated by multiplying the product of the mid-slice area measurement and the total number of slices in the coronal MR images of ADPKD kidneys by 0.61-0.64. This information will help save processing time needed to estimate total kidney and cyst volumes of ADPKD kidneys.

Pathophysiology, epidemiology, classification and treatment options for polycystic liver diseases

Polycystic liver diseases (PLD) represent a group of genetic disorders in which cysts occur in the liver (autosomal dominant polycystic liver disease) or in combination with cysts in the kidneys (autosomal dominant polycystic kidney disease). Regardless of the genetic mutations, the natural history of these disorders is alike. The natural history of PLD is characterized by a continuous increase in the volume and the number of cysts. Both genders are affected; however, women have a higher prevalence. Most patients with PLD are asymptomatic and can be managed conservatively. Severe symptoms can affect 20% of patients who develop massive hepatomegaly with compression of the surrounding organs. Rrarely, patients with PLD suffer from acute complications caused by the torsion of hepatic cysts, intraluminal cystic hemorrhage and infections. The most common methods for the diagnosis of PLD are cross sectional imaging studies. Abdominal ultrasound and computerized tomography are the two most frequently used investigations. Magnetic resonance imaging is more sensitive and specific, and it is a valuable test for patients with intravenous contrast allergies or renal dysfunction. Different treatment modalities are available to physicians caring for these patients. Medical treatment has been ineffective. Percutaneous sclerotherapy, trans-arterial embolization, cyst fenestration, hepatic resection and liver transplantation are indicated to specific groups of patients and have to be tailored according to the extent of disease. This review outlines the current knowledge of the pathophysiology, clinical course, diagnosis and treatment strategies of PLD.

Safety and efficacy of different lanreotide doses in the treatment of polycystic liver disease: pooled analysis of individual patient data

BACKGROUND

Long-acting lanreotide (LAN) 120 mg every 4 weeks reduces liver volume (LV) in patients with polycystic liver diseases (PCLD). Animal studies demonstrated that the inhibition of hepatic and renal cystogenesis is dose dependent.

AIM

To investigate the safety and efficacy of two different LAN doses in PCLD patients.

METHODS

The 6-month results of the LOCKCYST I trial, its extension study and the LOCKCYST II trial were pooled. LV at baseline and month 6 was measured by CT-scan and blindly re-analysed by two independent radiologists.

RESULTS

The study population [132 treatment periods, age 49 years (IQR: 45-55), 114 women] consisted of three groups. Each received treatment every 4 weeks during 6 months: placebo (n = 26); LAN 90 mg (n = 55) or LAN 120 mg (n = 51). The inter-observer variability and agreement in the calculation of LV were excellent. Severe side effects occurred with placebo, LAN 90 mg and LAN 120 mg in respectively 0%, 7% and 16%. Change in LV's after 6 months in these three groups were respectively: increase of +36 mL [(-45)-(+138)]; decrease of -82 mL [(-285)-(+92)] and decrease of -123 mL [(-312)-(+4)] (Kruskal-Wallis One Way anova on Ranks; P = 0.002). Based on ROC analysis, a reduction of ≥120 mL in LV has a positive predictive value of 64% for improving symptoms (ROC analysis AUC: 0.729; sensitivity 73%, specificity 69%, P < 0.0001).

CONCLUSIONS

Both LAN 90 mg and LAN 120 mg reduce liver volume. LAN 90 mg has less side effects. This suggests that in case of intolerance to LAN 120 mg, a dose reduction to LAN 90 mg is meaningful.

Young women with polycystic liver disease respond best to somatostatin analogues: a pooled analysis of individual patient data

BACKGROUND & AIMS

Clinical trials have shown that in patients with polycystic liver disease (PLD), short-term treatment with somatostatin analogues (SAs) reduces liver volumes by 4.5%-5.9%, compared with placebo. However, the effects of SA therapy vary among individuals. We collected data from individual patients with PLD to identify subgroups that benefit most from SA therapy.

METHODS

We analyzed data from 107 patients with PLD from 3 randomized placebo-controlled trials (67 received SAs, 52 received placebo). We used multiple linear regression analysis to determine the effects of SAs based on patients' age, sex, baseline liver volume, and diagnosis (autosomal dominant polycystic liver or kidney disease). The primary outcome was change in liver volume after 6-12 months of treatment.

RESULTS

The effects of SA therapy did not differ significantly among patients with different diagnoses or baseline liver volumes; the overall difference in liver volume between groups receiving SAs therapy vs placebo was 5.3% (P < .001). Among subjects given placebo, young women (48 years old or younger) had the greatest increase in polycystic liver volume (4.8%; 95% confidence interval: 2.2%-7.4%), and mean liver volumes did not increase in older women and men. Women 48 years old or younger had a greater response to therapy (a reduction in liver volume of 8.0% compared with placebo; P < .001) than older women (a reduction in liver volume of 4.1% compared with placebo; P = .022).

CONCLUSIONS

Based on a pooled analysis of data from individual patients with PLD, treatment with somatostatin analogues is equally effective for patients with autosomal dominant polycystic kidney disease or polycystic liver disease; efficacy does not depend on size of the polycystic liver. Young female patients appear to have the greatest benefit from 6-12 months of SA therapy, which might avert the progressive course of the disease in this specific group.

Segmentation of individual renal cysts from MR images in patients with autosomal dominant polycystic kidney disease

OBJECTIVE

To evaluate the performance of a semi-automated method for the segmentation of individual renal cysts from magnetic resonance (MR) images in patients with autosomal dominant polycystic kidney disease (ADPKD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This semi-automated method was based on a morphologic watershed technique with shape-detection level set for segmentation of renal cysts from MR images. T2-weighted MR image sets of 40 kidneys were selected from 20 patients with mild to moderate renal cyst burden (kidney volume < 1500 ml) in the Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP). The performance of the semi-automated method was assessed in terms of two reference metrics in each kidney: the total number of cysts measured by manual counting and the total volume of cysts measured with a region-based thresholding method. The proposed and reference measurements were compared using intraclass correlation coefficient (ICC) and Bland-Altman analysis.

RESULTS

Individual renal cysts were successfully segmented with the semi-automated method in all 20 cases. The total number of cysts in each kidney measured with the two methods correlated well (ICC, 0.99), with a very small relative bias (0.3% increase with the semi-automated method; limits of agreement, 15.2% reduction to 17.2% increase). The total volume of cysts measured using both methods also correlated well (ICC, 1.00), with a small relative bias of <10% (9.0% decrease in the semi-automated method; limits of agreement, 17.1% increase to 43.3% decrease).

CONCLUSION

This semi-automated method to segment individual renal cysts in ADPKD kidneys provides a quantitative indicator of severity in early and moderate stages of the disease.

Evaluation of hepatic cystic lesions

Hepatic cysts are increasingly found as a mere coincidence on abdominal imaging techniques, such as ultrasonography (USG), computed tomography (CT) and magnetic resonance imaging (MRI). These cysts often present a diagnostic challenge. Therefore, we performed a review of the recent literature and developed an evidence-based diagnostic algorithm to guide clinicians in characterising these lesions. Simple cysts are the most common cystic liver disease, and diagnosis is based on typical USG characteristics. Serodiagnostic tests and microbubble contrast-enhanced ultrasound (CEUS) are invaluable in differentiating complicated cysts, echinococcosis and cystadenoma/cystadenocarcinoma when USG, CT and MRI show ambiguous findings. Therefore, serodiagnostic tests and CEUS reduce the need for invasive procedures. Polycystic liver disease (PLD) is arbitrarily defined as the presence of > 20 liver cysts and can present as two distinct genetic disorders: autosomal dominant polycystic kidney disease (ADPKD) and autosomal dominant polycystic liver disease (PCLD). Although genetic testing for ADPKD and PCLD is possible, it is rarely performed because it does not affect the therapeutic management of PLD. USG screening of the liver and both kidneys combined with extensive family history taking are the cornerstone of diagnostic decision making in PLD. In conclusion, an amalgamation of these recent advances results in a diagnostic algorithm that facilitates evidence-based clinical decision making.

Correlation between number of renal cysts and aortic circumferences measured using autopsy material

Although the presence of renal cysts has been reported to be associated with aortic aneurysm or dissection by imaging studies, an autopsy study has not been performed. Therefore, in our institute, recent consecutive adult autopsy cases (n=108, 64 males and 44 females) were reviewed. The circumferences and atherosclerosis ratios of both thoracic and abdominal aorta were individually measured and graded. The number of renal cysts was scored and graded. Age of subjects along with histories of smoking, hypertension, and diabetes mellitus were confirmed. Multiple linear regression analyses demonstrated that severity of atherosclerosis and the number of renal cysts were correlated with thoracic aortic circumference, while only the number of renal cysts was correlated with abdominal aortic circumference (p<0.05), which was more predominant in female subjects (p<0.05). Microscopically, significantly more dilated renal tubules (by Student's t-test, p<0.05) along with decreased stainability of basement membrane by Periodic acid-Schiff staining and immunostaining of type IV collagen were noted in background renal tissues in cases with numerous renal cysts than in age- and sex-matched controls without renal cysts (n=10 vs. 10). The present study suggests that a syndrome that affects both aorta and renal tubules may exist.

Diagnosis and management of polycystic liver disease

Polycystic liver disease (PLD) is arbitrarily defined as a liver that contains >20 cysts. The condition is associated with two genetically distinct diseases: as a primary phenotype in isolated polycystic liver disease (PCLD) and as an extrarenal manifestation in autosomal dominant polycystic kidney disease (ADPKD). Processes involved in hepatic cystogenesis include ductal plate malformation with concomitant abnormal fluid secretion, altered cell-matrix interaction and cholangiocyte hyperproliferation. PLD is usually a benign disease, but can cause debilitating abdominal symptoms in some patients. The main risk factors for growth of liver cysts are female sex, exogenous oestrogen use and multiple pregnancies. Ultrasonography is very useful for achieving a correct diagnosis of a polycystic liver and to differentiate between ADPKD and PCLD. Current radiological and surgical therapies for symptomatic patients include aspiration-sclerotherapy, fenestration, segmental hepatic resection and liver transplantation. Medical therapies that interact with regulatory mechanisms controlling expansion and growth of liver cysts are under investigation. Somatostatin analogues are promising; several clinical trials have shown that these drugs can reduce the volume of polycystic livers. The purpose of this Review is to provide an update on the diagnosis and management of PLD with a focus on literature published in the past 4 years.

Epidemiology of autosomal-dominant polycystic kidney disease: an in-depth clinical study for south-western Germany

BACKGROUND

As we emerge into the genomic medicine era, the epidemiology of diseases is taken for granted. Accurate prevalence figures, especially of rare diseases (RDs, ≤50/100,000), will become even more important for purposes of health care and societal planning. We noticed that the numbers of affected individuals in regionally established registries for mainly hereditary RDs do not align with published estimated and expected prevalence figures. We therefore hypothesized that such non-population-based means overestimate RDs and sought to address this by recalculating prevalence for an important 'common' hereditary disease, autosomal-dominant polycystic kidney disease (ADPKD) whereby presumed-prevalence is 100-250/100,000 METHODS: The Else-Kroener-Fresenius-ADPKD-Study in south-west Germany with a population of 2,727,351 inhabitants was established with the cooperation of all nephrology centres. Furthermore, general practitioners, internists, urologists, human geneticists and neurosurgery centres were contacted with questionnaires for demographic, family and kidney function data. Germline-mutation screening of susceptibility genes PKD1 and PKD2 was offered. Official population data for 2010 were used for overall and kidney function-adjusted prevalence estimations.

RESULTS

A total of 891 subjects, 658 index-cases and 233 relatives, aged 10-89 (mean 52), were registered, with >90% response rate, 398 by nephrologists and 493 by non-nephrologists. Molecular-genetic analyses contributed to confirmation of the diagnosis in 57%. The overall prevalence of ADPKD was 32.7/100,000 reaching a maximum of 57.3/100,000 in the 6th decade of life.

CONCLUSIONS

Prevalence of ADPKD is overestimated by 2- to 5-fold and close to the limit of RDs which may be of broad clinical, logistic and policy implications.

Acute abdomen and ascites as presenting features of autosomal dominant polycystic kidney disease

We describe a patient with sudden onset of abdominal pain and ascites, leading to the diagnosis of autosomal dominant polycystic kidney disease (ADPKD). Her presentation was consistent with acute liver cyst rupture as the cause of her acute illness. A review of literature on polycystic liver disease in patients with ADPKD and current management strategies are presented. This case alerts physicians that ADPKD could occasionally present as an acute abdomen; cyst rupture related to ADPKD may be considered in the differential diagnoses of acute abdomen.

Polycystic liver disease: a clinical review

Polycystic liver disease rarely occurs in isolation as part of autosomal dominant polycystic liver disease, but more commonly, it exists as an extra-renal manifestation of autosomal dominant polycystic kidney disease. The pathogenesis of polycystic liver disease involves defects in the primary cilium of the cholangiocyte, with genetic mutations that impair key proteins integral to the complex functioning of cilia. While most patients are asymptomatic and require no intervention aside from reassurance and genetic counseling, in a minority of patients, polycystic liver disease creates a myriad of symptoms from the compressive effects of enlarged cysts, and can even cause malnutrition and liver decompensation in the severest of cases. In patients with symptomatic disease, a variety of interventional radiology or surgical techniques can be considered, including aspiration with sclerotherapy of a dominant cyst, fenestration, segmental hepatic resection, and even liver transplantation. Although there are no curative medical options for polycystic liver disease, somatostatin analogs hold promise and have shown minimal efficacy in human studies. However, further research is needed to develop more efficacious medical treatments.

Functional polycystin-1 dosage governs autosomal dominant polycystic kidney disease severity

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations to PKD1 or PKD2, triggering progressive cystogenesis and typically leading to end-stage renal disease in midlife. The phenotypic spectrum, however, ranges from in utero onset to adequate renal function at old age. Recent patient data suggest that the disease is dosage dependent, where incompletely penetrant alleles influence disease severity. Here, we have developed a knockin mouse model matching a likely disease variant, PKD1 p.R3277C (RC), and have proved that its functionally hypomorphic nature modifies the ADPKD phenotype. While Pkd1+/null mice are normal, Pkd1RC/null mice have rapidly progressive disease, and Pkd1RC/RC animals develop gradual cystogenesis. These models effectively mimic the pathophysiological features of in utero-onset and typical ADPKD, respectively, correlating the level of functional Pkd1 product with disease severity, highlighting the dosage dependence of cystogenesis. Additionally, molecular analyses identified p.R3277C as a temperature-sensitive folding/trafficking mutant, and length defects in collecting duct primary cilia, the organelle central to PKD pathogenesis, were clearly detected for the first time to our knowledge in PKD1. Altogether, this study highlights the role that in trans variants at the disease locus can play in phenotypic modification of dominant diseases and provides a truly orthologous PKD1 model, optimal for therapeutic testing.

Ascites complicating unilateral nephrectomy and peritoneal dialysis catheter implantation in a patient with massive polycystic kidney and liver disease

Peritoneal dialysis (PD) is a well-established therapeutic option for patients with polycystic kidney disease. However, in patients with massive polycystic kidney and liver disease, subclinical hepatic venous outflow obstruction may elicit the appearance of ascites after implantation of a peritoneal catheter. The case of a patient who developed ascites after implantation of a PD catheter and further lowering of abdominal pressure after unilateral nephrectomy is discussed.

Altered store operated calcium entry increases cyclic 3',5'-adenosine monophosphate production and extracellular signal-regulated kinases 1 and 2 phosphorylation in polycystin-2-defective cholangiocytes

Mutations in polycystins (PC1 or PC2/TRPP2) cause progressive polycystic liver disease (PLD). In PC2-defective mice, cyclic 3',5'-adenosine monophosphate/ protein kinase A (cAMP/PKA)-dependent activation of extracellular signal-regulated kinase/ mammalian target of rapamycin (ERK-mTOR) signaling stimulates cyst growth. We investigated the mechanisms connecting PC2 dysfunction to altered Ca(2+) and cAMP production and inappropriate ERK signaling in PC2-defective cholangiocytes. Cystic cholangiocytes were isolated from PC2 conditional-KO (knockout) mice (Pkd2(flox/-) :pCxCreER™; hence, called Pkd2KO) and compared to cholangiocytes from wild-type mice (WT). Our results showed that, compared to WT cells, in PC2-defective cholangiocytes (Pkd2KO), cytoplasmic and ER-Ca(2+) (measured with Fura-2 and Mag-Fluo4) levels are decreased and store-operated Ca(2+) entry (SOCE) is inhibited, whereas the expression of Ca(2+) -sensor stromal interaction molecule 1 (STIM1) and store-operated Ca(2+) channels (e.g., the Orai1 channel) are unchanged. In Pkd2KO cells, ER-Ca(2+) depletion increases cAMP and PKA-dependent ERK1/2 activation and both are inhibited by STIM1 inhibitors or by silencing of adenylyl cyclase type 6 (AC6).

CONCLUSION

These data suggest that PC2 plays a key role in SOCE activation and inhibits the STIM-dependent activation of AC6 by ER Ca(2+) depletion. In PC2-defective cells, the interaction of STIM-1 with Orai channels is uncoupled, whereas coupling to AC6 is maximized. The resulting overproduction of cAMP, in turn, potently activates the PKA/ERK pathway. PLD, because of PC2 deficiency, represents the first example of human disease linked to the inappropriate activation of store-operated cAMP production.

The long-term outcome of patients with polycystic liver disease treated with lanreotide

BACKGROUND

Polycystic liver disease (PLD) is a phenotypical expression of autosomal dominant polycystic kidney disease and isolated polycystic liver disease. Somatostatin analogues, such as lanreotide, reduce polycystic liver volume.

AIM

To establish long-term outcome and safety of lanreotide.

METHODS

This was an open-label, observational extension study of a 6-month, randomised, placebo-controlled trial with lanreotide (120 mg/month) in PLD. The length of total treatment was 12 months. Primary endpoint was relative change in liver volume, as determined by CT-volumetry after 12 months of treatment. We offered patients a CT scan 6 months after stopping lanreotide.

RESULTS

A total of 41/54 (76%) patients participated in the extension study. Liver volume decreased by 4% (IQR -8% to -1%) after 12 months of treatment. The greatest effect was observed during the first 6 months of treatment (decrease of 4% (IQR -6% to -1%)). Liver volume remained unchanged during the following 6 months. We found that liver volume increased by 4% (IQR 0-6%) 6 months after end of treatment (n = 22).

CONCLUSIONS

Lanreotide reduces liver volume within the first 6 months of treatment and the beneficial effect is maintained in the following 6 months. Stopping results in recurrence of polycystic liver growth. This suggests that continuous use of lanreotide is needed to maintain its effect.

Educational paper: ciliopathies

Cilia are antenna-like organelles found on the surface of most cells. They transduce molecular signals and facilitate interactions between cells and their environment. Ciliary dysfunction has been shown to underlie a broad range of overlapping, clinically and genetically heterogeneous phenotypes, collectively termed ciliopathies. Literally, all organs can be affected. Frequent cilia-related manifestations are (poly)cystic kidney disease, retinal degeneration, situs inversus, cardiac defects, polydactyly, other skeletal abnormalities, and defects of the central and peripheral nervous system, occurring either isolated or as part of syndromes. Characterization of ciliopathies and the decisive role of primary cilia in signal transduction and cell division provides novel insights into tumorigenesis, mental retardation, and other common causes of morbidity and mortality, including diabetes mellitus and obesity. New technologies ("Next generation sequencing/NGS") have considerably improved genetic research and diagnostics by allowing simultaneous investigation of all disease genes at reduced costs and lower turn-around times. This is undoubtedly a result of the dynamic development in the field of human genetics and deserves increased attention in genetic counselling and the management of affected families.

Analysis of baseline parameters in the HALT polycystic kidney disease trials

HALT PKD consists of two ongoing randomized trials with the largest cohort of systematically studied patients with autosomal dominant polycystic kidney disease to date. Study A will compare combined treatment with an angiotensin-converting inhibitor and receptor blocker to inhibitor alone and standard compared with low blood pressure targets in 558 early-stage disease patients with an eGFR over 60 ml/min per 1.73 m(2). Study B will compare inhibitor-blocker treatment to the inhibitor alone in 486 late-stage patients with eGFR 25-60 ml/min per 1.73 m(2). We used correlation and multiple regression cross-sectional analyses to determine associations of baseline parameters with total kidney, liver, or liver cyst volumes measured by MRI in Study A and eGFR in both studies. Lower eGFR and higher natural log-transformed urine albumin excretion were independently associated with a larger natural log-transformed total kidney volume adjusted for height (ln(HtTKV)). Higher body surface area was independently associated with a higher ln(HtTKV) and lower eGFR. Men had larger height-adjusted total kidney volume and smaller liver cyst volumes than women. A weak correlation was found between the ln(HtTKV) and natural log-transformed total liver volume adjusted for height or natural log liver cyst volume in women only. Women had higher urine aldosterone excretion and lower plasma potassium. Thus, our analysis (1) confirms a strong association between renal volume and functional parameters, (2) shows that gender and other factors differentially affect the development of polycystic disease in the kidney and liver, and (3) suggests an association between anthropomorphic measures reflecting prenatal and/or postnatal growth and disease severity.

Imaging approaches to patients with polycystic kidney disease

Imaging is an important approach to diagnosis, monitoring, and predicting outcomes for patients with autosomal-dominant polycystic kidney disease. This article reviews three common clinical imaging techniques, ultrasonography, computed tomography, magnetic resonance imaging, and their role in the management of autosomal-dominant polycystic kidney disease. Ultrasonographic criteria for diagnosis in children and adults are reviewed. Total kidney volume, as measured by magnetic resonance imaging, is suggested as an important potential marker to determine disease progression and overall prognosis. Renal blood flow and a novel approach to interpreting noncystic renal parenchyma by computed tomography images are other innovative imaging approaches described.

Everolimus and long acting octreotide as a volume reducing treatment of polycystic livers (ELATE): study protocol for a randomized controlled trial

Background

Polycystic liver disease (PLD) is defined as having more than 20 liver cysts and can present as a severe and disabling condition. Most symptoms are caused by the mass effect of the liver size and include abdominal pain and distension. The somatostatin analogues octreotide and lanreotide have proven to reduce polycystic liver volume. mTOR inhibitors such as everolimus inhibit cell proliferation and might thereby reduce growth of liver cysts. This trial aims to assess the benefit of combination therapy of everolimus and octreotide compared to octreotide monotherapy. In this study we present the structure of the trial and the characteristics of the included patients.

Methods/design

This is a randomized open-label clinical trial comparing the effect of 12 months of everolimus and octreotide to octreotide monotherapy in PLD patients. Primary outcome is change in liver volume determined by CT-volumetry. Secondary outcomes are changes in abdominal symptoms and quality of life. Moreover, safety and tolerability of the drugs will be assessed.

Discussion

This trial will compare the relative efficacy of combination therapy with octreotide and everolimus to octreotide monotherapy. Since they apply to different pathways of cystogenesis we expect that combining octreotide and everolimus will result in a cumulative reduction of polycystic liver volume.

Trial registration number

ClinicalTrials.gov: NCT01157858

Systematic review: the pathophysiology and management of polycystic liver disease

BACKGROUND

Polycystic liver diseases (PCLD) represent a group of genetic disorders in which cysts occur solely in the liver, or together with renal cysts. Most of the patients with PCLD are asymptomatic, however, in some patients, expansion of liver cysts causes invalidating abdominal symptoms.

AIM

To provide a systemic review on the pathophysiology and management of PCLD.

METHODS

A PubMed search was undertaken to identify relevant literature using search terms including polycystic liver disease, pathophysiology, surgical and medical management.

RESULTS

The most common complication in patients with PCLD is extensive hepatomegaly, which may lead to malnutrition and can be lethal. Conservative surgical approaches are only partially effective and do not change the natural course of the disease. Liver transplantation has been successfully performed in PCLD, however, in an era of organ shortage, medical management needs to be evaluated. A better understanding of the pathophysiology and the availability of animal models have already identified promising drugs. Abnormalities in cholangiocyte proliferation/apoptosis and enhanced fluid secretion are key factors in the pathophysiology. It has been demonstrated in rodents and in humans that somatostatin analogues diminish liver volume. The role of the inhibitors of the mammalian target of rapamycin (mTOR) in the management of PCLD is still under investigation.

CONCLUSIONS

The exact pathophysiology of polycystic liver disease still remains unclear. In symptomatic patients, none of the currently available surgical options except liver transplantation have been shown to change the natural course of the disease. The use of somatostatin analogues has been shown to diminish liver volume.

Intermediate volume on computed tomography imaging defines a fibrotic compartment that predicts glomerular filtration rate decline in autosomal dominant polycystic kidney disease patients

Total kidney and cyst volumes have been used to quantify disease progression in autosomal dominant polycystic kidney disease (ADPKD), but a causal relationship with progression to renal failure has not been demonstrated. Advanced image processing recently allowed to quantify extracystic tissue, and to identify an additional tissue component named "intermediate," appearing hypoenhanced on contrast-enhanced computed tomography (CT). The aim of this study is to provide a histological characterization of intermediate volume, investigate its relation with renal function, and provide preliminary evidence of its role in long-term prediction of functional loss. Three ADPKD patients underwent contrast-enhanced CT scans before nephrectomy. Histological samples of intermediate volume were drawn from the excised kidneys, and stained with hematoxylin and eosin and with saturated picrosirius solution for histological analysis. Intermediate volume showed major structural changes, characterized by tubular dilation and atrophy, microcysts, inflammatory cell infiltrate, vascular sclerosis, and extended peritubular interstitial fibrosis. A significant correlation (r = -0.69, P < 0.001) between relative intermediate volume and baseline renal function was found in 21 ADPKD patients. Long-term prediction of renal functional loss was investigated in an independent cohort of 13 ADPKD patients, followed for 3 to 8 years. Intermediate volume, but not total kidney or cyst volume, significantly correlated with glomerular filtration rate decline (r = -0.79, P < 0.005). These findings suggest that intermediate volume may represent a suitable surrogate marker of ADPKD progression and a novel therapeutic target.

Diagnosis and management of childhood polycystic kidney disease

A number of syndromic disorders have renal cysts as a component of their phenotypes. These disorders can generally be distinguished from autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) by imaging studies of their characteristic, predominantly non-renal associated abnormalities. Therefore, a major distinction in the differential diagnosis of enlarge echogenic kidneys is delineating ARPKD from ADPKD. ADPKD and ARPKD can be diagnosed by imaging the kidney with ultrasound, computed tomography, or magnetic resonance imaging (MRI), although ultrasound is still the method of choice for diagnosis in utero and in young children due to ease of use, cost, and safety. Differences in ultrasound characteristics, the presence or absence of associated extrarenal abnormalities, and the screening of the parents >40 years of age usually allow the clinician to make an accurate diagnosis. Early diagnosis of ADPKD and ARPKD affords the opportunity for maximal anticipatory care (i.e. blood pressure control) and in the not-too-distant future, the opportunity to benefit from new therapies currently being developed. If results are equivocal, genetic testing is available for both ARPKD and ADPKD. Specialized centers are now offering preimplantation genetic diagnosis and in vitro fertilization for parents who have previously had a child with ARPKD. For ADPKD patients, a number of therapeutic interventions are currently in clinical trial and may soon be available.

Assessment of kidney volume in polycystic kidney disease using magnetic resonance imaging without contrast medium

BACKGROUND/AIMS

Total renal volume (TRV) is an important index to evaluate the progression of autosomal-dominant polycystic kidney disease (ADPKD). TRV has been assessed by manually tracing renal contours from CT or MR scans, often employing contrast medium (CM). We developed a fast and nearly automated technique based on the analysis of MR images acquired without CM injection for TRV quantification.

METHODS

30 ADPKD patients underwent MRI. After the selection of one point inside each kidney for the entire volume, the automatic extraction of kidney contours was performed on each acquired slice; the segmentation procedure was based on region growing and on the application of morphological operators and curvature-based motion. The area inside each contour was calculated and TRV was derived. Volume measurements were validated by comparison with measurements obtained by stereology.

RESULTS

TRV estimated in patients was 768 ± 545 ml (range 161-3,111 ml). The automatic measurements were in excellent correlation with the manual ones (r = 0.99, y = x - 0.7), with a small bias and narrow limits of agreement in both absolute (-5 ± 37 ml) and percentage (-0.6 ± 9.6%) terms.

CONCLUSION

This preliminary study showed the feasibility of a fast and nearly automated method for determining TRV; importantly it does not require the use of potentially nephrotoxic CM.

Congenital fibrocystic liver diseases

Fibrocystic diseases affecting the liver and often also other organs like the kidneys are a clinically and genetically heterogeneous group of disorders that may present in utero or remain clinically silent into late adulthood. During recent years, substantial progress has been made in unravelling the aetiology with primary cilia playing a central pathogenic role in many if not all of these diseases. The fibrocystogenic process shares some common features including proliferation and dilatation of epithelial bile ducts with concomitant abnormal apoptosis, fluid secretion and extracellular matrix deposition. In this review, we summarise clinical and diagnostic aspects, mechanisms of hepatic cystogenesis, and recent knowledge on potential therapies for these conditions.

Hepatic cysts and liver abscess

Benign pathologies of the liver often include several cystic diseases, such as simple cysts, autosomal dominant polycystic liver disease, and Caroli's disease. The differential of hepatic cysts also includes infectious pathologies, such as pyogenic liver abscess, hydatid cysts, and parasitic infections if the appropriate clinic setting. Understanding of the various causes, clinical presentation, and treatment options is required to ensure the appropriate surgical management of these patients.

Polycystic kidney disease: inheritance, pathophysiology, prognosis, and treatment

Both autosomal dominant and recessive polycystic kidney disease are conditions with severe associated morbidity and mortality. Recent advances in the understanding of the genetic and molecular pathogenesis of both ADPKD and ARPKD have resulted in new, targeted therapies designed to disrupt cell signaling pathways responsible for the abnormal cell proliferation, dedifferentiation, apoptosis, and fluid secretion characteristic of the disease. Herein we review the current understanding of the pathophysiology of these conditions, as well as the current treatments derived from our understanding of the mechanisms of these diseases.

Mammalian target of rapamycin regulates vascular endothelial growth factor-dependent liver cyst growth in polycystin-2-defective mice

Polycystic liver disease may complicate autosomal dominant polycystic kidney disease (ADPKD), a disease caused by mutations in polycystins, which are proteins that regulate signaling, morphogenesis, and differentiation in epithelial cells. The cystic biliary epithelium [liver cystic epithelium (LCE)] secretes vascular endothelial growth factor (VEGF), which promotes liver cyst growth via autocrine and paracrine mechanisms. The expression of insulin-like growth factor 1 (IGF1), insulin-like growth factor 1 receptor (IGF1R), and phosphorylated mammalian target of rapamycin (p-mTOR) and the protein kinase A (PKA)-dependent phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) are also up-regulated in LCE. We have hypothesized that mammalian target of rapamycin (mTOR) represents a common pathway for the regulation of hypoxia-inducible factor 1 alpha (HIF1alpha)-dependent VEGF secretion by IGF1 and ERK1/2. Conditional polycystin-2-knockout (Pkd2KO) mice were used for in vivo studies and to isolate cystic cholangiocytes [liver cystic epithelial cells (LCECs)]. The expression of p-mTOR, VEGF, cleaved caspase 3 (CC3), proliferating cell nuclear antigen (PCNA), IGF1, IGF1R, phosphorylated extracellular signal-regulated kinase, p-P70S6K, HIF1alpha, and VEGF in LCE, LCECs, and wild-type cholangiocytes was studied with immunohistochemistry, western blotting, or enzyme-linked immunosorbent assays. The cystic area was measured by computer-assisted morphometry of pancytokeratin-stained sections. Cell proliferation in vitro was studied with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and bromodeoxyuridine assays. The treatment of Pkd2KO mice with the mTOR inhibitor rapamycin significantly reduced the liver cyst area, liver/body weight ratio, pericystic microvascular density, and PCNA expression while increasing expression of CC3. Rapamycin inhibited IGF1-stimulated HIF1alpha accumulation and VEGF secretion in LCECs. IGF1-stimulated LCEC proliferation was inhibited by rapamycin and SU5416 (a vascular endothelial growth factor receptor 2 inhibitor). Phosphorylation of the mTOR-dependent kinase P70S6K was significantly reduced by PKA inhibitor 14-22 amide and by the mitogen signal-regulated kinase inhibitor U1026.

CONCLUSION

These data demonstrate that PKA-dependent up-regulation of mTOR has a central role in the proliferative, antiapoptotic, and pro-angiogenic effects of IGF1 and VEGF in polycystin-2-defective mice. This study also highlights a mechanistic link between PKA, ERK, mTOR, and HIF1alpha-mediated VEGF secretion and provides a proof of concept for the potential use of mTOR inhibitors in ADPKD and conditions with aberrant cholangiocyte proliferation.

Evaluation and management of pain in autosomal dominant polycystic kidney disease

Transient episodes of pain are common in autosomal dominant polycystic kidney disease (ADPKD). A small fraction of patients have disabling chronic pain. In this review, we discuss the etiologies of pain in ADPKD; review how ADPKD patients should be assessed; and discuss medical, surgical, and other management options.

Randomized clinical trial of long-acting somatostatin for autosomal dominant polycystic kidney and liver disease

There are no proven, effective therapies for polycystic kidney disease (PKD) or polycystic liver disease (PLD). We enrolled 42 patients with severe PLD resulting from autosomal dominant PKD (ADPKD) or autosomal dominant PLD (ADPLD) in a randomized, double-blind, placebo-controlled trial of octreotide, a long-acting somatostatin analogue. We randomly assigned 42 patients in a 2:1 ratio to octreotide LAR depot (up to 40 mg every 28+/-5 days) or placebo for 1 year. The primary end point was percent change in liver volume from baseline to 1 year, measured by MRI. Secondary end points were changes in total kidney volume, GFR, quality of life, safety, vital signs, and clinical laboratory tests. Thirty-four patients had ADPKD, and eight had ADPLD. Liver volume decreased by 4.95%+/-6.77% in the octreotide group but remained practically unchanged (+0.92%+/-8.33%) in the placebo group (P=0.048). Among patients with ADPKD, total kidney volume remained practically unchanged (+0.25%+/-7.53%) in the octreotide group but increased by 8.61%+/-10.07% in the placebo group (P=0.045). Changes in GFR were similar in both groups. Octreotide was well tolerated; treated individuals reported an improved perception of bodily pain and physical activity. In summary, octreotide slowed the progressive increase in liver volume and total kidney volume, improved health perception among patients with PLD, and had an acceptable side effect profile.

Distinct patterns of kidney and liver cyst growth in pkd2(WS25/-) mice

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease that results in the development of cystic kidneys and liver. Pkd2(WS25/-) mice are a key genetic mouse model of human ADPKD that recapitulate the 'molecular recessive' nature of human ADPKD. Providing the foundation for future long-term studies, the present work documents distinct patterns of long-term cyst growth in the kidneys and liver of male and female pkd2(WS25/-) mice.

METHODS

Gravimetric measurements documented the progression of kidney and liver growth in male and female pkd2(WS25/-) mice over 12 months. A fast imaging with steady-state precision-magnetic resonance imaging (FISP-MRI) technique to measure kidney and liver organ and cyst volumes was optimized and validated. Longitudinal FISP-MRI analyses of changes in cyst volumes were performed in pkd2(WS25/-) mice over 15 months.

RESULTS

Male and female pkd2(WS25/-) mice had significant increases in kidney weights after 4 months of age. The progression of kidney growth was minimal after 4 months of age. Liver cyst growth in male pkd2(WS25/-) mice was minimal after 4 months of age but showed an accelerated rate of growth after 8 months of age. Female pkd2(WS25/-) mice also showed accelerated growth but this was delayed in time when compared with male pkd2(WS25/-) mice.

CONCLUSIONS

Pkd2(WS25/-) mice are a genetic mouse model that recapitulates the early phenotypic characteristics of human ADPKD kidney cystogenesis. Male pkd2(WS25/-) mice consistently display a late progression in liver growth that is seen in clinically impacted livers of human ADPKD patients.

Polycystic liver diseases

Polycystic liver diseases (PCLDs) are genetic disorders with heterogeneous etiologies and a range of phenotypic presentations. PCLD exhibits both autosomal or recessive dominant pattern of inheritance and is characterized by the progressive development of multiple cysts, isolated or associated with polycystic kidney disease, that appear more extensive in women. Cholangiocytes have primary cilia, functionally important organelles (act as mechanosensors) that are involved in both normal developmental and pathological processes. The absence of polycystin-1, 2, and fibrocystin/polyductin, normally localized to primary cilia, represent a potential mechanism leading to cyst formation, associated with increased cell proliferation and apoptosis, enhanced fluid secretion, abnormal cell-matrix interactions, and alterations in cell polarity. Proliferative and secretive activities of cystic epithelium can be regulated by estrogens either directly or by synergizing growth factors including nerve growth factor, IGF1, FSH and VEGF. The abnormalities of primary cilia and the sensitivity to proliferative effects of estrogens and different growth factors in PCLD cystic epithelium provide the morpho-functional basis for future treatment targets, based on the possible modulation of the formation and progression of hepatic cysts.

Isolated polycystic liver disease

Isolated polycystic liver disease (PCLD) is an autosomal dominant disease with genetic and clinical heterogeneity. Apart from liver cysts, it exhibits few extrahepatic manifestations, and the majority of patients with this condition are asymptomatic or subclinical. However, a small fraction of these patients develop acute liver cyst-related complications and/or massive cystic liver enlargement, causing morbidity and mortality. Currently, the management for symptomatic PCLD is centered on palliating symptoms and treating complications.

Determinants of renal disease variability in ADPKD

In common with other Mendelian diseases, the presentation and progression of autosomal dominant polycystic kidney disease (ADPKD) vary widely in the population. The typical course is of adult-onset disease with ESRD in the 6th decade. However, a small proportion has adequate renal function into the 9th decade, whereas others present with enlarged kidneys as neonates. ADPKD is genetically heterogeneous, and the disease gene is a major determinant of severity; PKD1 on average is associated with ESRD 20 years earlier than PKD2. The majority of PKD1 and PKD2 mutations are likely fully inactivating although recent studies indicate that some alleles retain partial activity (hypomorphic alleles). Homozygotes for such alleles are viable and in combination with an inactivating allele can result in early-onset disease. Hypomorphic alleles and mosaicism may also account for some cases with unusually mild disease. The degree of phenotypic variation detected in families indicates that genetic background influences disease severity. Genome-wide association studies are planned to map common variants associated with severity. Although ADPKD is a simple genetic disease, fully understanding the phenotypic variability requires consideration of influences at the genic, allelic, and genetic background level, and so, ultimately, it is complex.

Extrarenal manifestations of autosomal dominant polycystic kidney disease

Although asymptomatic in most patients, extrarenal manifestations of ADPKD may become more clinically relevant with the increasing life expectancy of affected patients. They mainly encompass cysts in other organs than the kidney (liver: 94%, seminal vesicle: 40%, pancreas: 9%, arachnoid membrane: 8%, and spinal meningeal, 2%) and connective tissue abnormalities (mitral valve prolapse: 25%, intracranial aneurysms: 8%, and abdominal hernia: 10%). Their recognition may spare the patient from other, useless investigations (eg, when an arachnoid cyst is incidentally found) or lead to the implementation of prophylactic or therapeutic measures (eg, screening, sometimes followed by the treatment of an asymptomatic intracranial aneurysm in at-risk patients, or, in the presence of a severe polycystic liver disease, avoidance from estrogens and treatment aimed to slow cyst growth).

Reducing polycystic liver volume in ADPKD: effects of somatostatin analogue octreotide

BACKGROUND AND OBJECTIVES

No medical treatment is available for polycystic liver disease, a frequent manifestation of autosomal-dominant polycystic kidney disease (ADPKD). In a prospective, randomized, double-blind, crossover study, 6 months of octreotide (40 mg every 28 days) therapy limited kidney volume growth more effectively than placebo in 12 patients with ADPKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this secondary, post hoc analysis of the above study, octreotide-induced changes in liver volumes compared with placebo and the relationship between concomitant changes in liver and kidney volumes were evaluated. Those analyzing liver and kidney volumes were blinded to treatment.

RESULTS

Liver volumes significantly decreased from 1595 +/- 478 ml to 1524 +/- 453 ml with octreotide whereas they did not appreciably change with placebo. Changes in liver volumes were significantly different between the two treatment periods (-71 +/- 57 ml versus +14 +/- 85 ml). Octreotide-induced liver volume reduction was fully explained by a reduction in parenchyma volume from 1506 +/- 431 ml to 1432 +/- 403 ml. Changes in liver volumes were significantly correlated with concomitant changes in kidney volumes (r = 0.67) during octreotide but not during placebo treatment. Liver and kidney volume changes significantly differed with both treatments (octreotide: -71 +/- 57 ml versus +71 +/- 107; placebo: +14 +/- 85 ml versus +162 +/- 114), but net reductions in liver (-85 +/- 103 ml) and kidney (-91 +/- 125 ml) volume growth on octreotide versus placebo were similar.

CONCLUSIONS

Octreotide therapy reduces liver volumes in patients with ADPKD and is safe.

A metabolomics approach using juvenile cystic mice to identify urinary biomarkers and altered pathways in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease and affects 1 in 1,000 individuals. Ultrasound is most often used to diagnose ADPKD; such a modality is only useful late in the disease after macroscopic cysts are present. There is accumulating evidence suggesting that there are common cellular and molecular mechanisms responsible for cystogenesis in human and murine PKD regardless of the genes mutated, and, in the case of complex metabolomic analysis, the use of a mouse model has distinct advantages for proof of principle over a human study. Therefore, in this study we utilized a urinary metabolomics-based investigation using gas chromatography-time of flight mass spectrometry to demonstrate that the cystic mouse can be discriminated from its wild-type counterpart by urine analysis alone. At day 26 of life, before there is serological evidence of kidney dysfunction, affected mice are distinguishable by urine metabolomic analysis; this finding persists through 45 days until 64 days, at which time body weight differences confound the results. Using functional score analysis and the KEGG pathway database, we identify several biologically relevant metabolic pathways which are altered very early in this disease, the most highly represented being the purine and galactose metabolism pathways. In addition, we identify several specific candidate biomarkers, including allantoic acid and adenosine, which are augmented in the urine of young cystic mice. These markers and pathway components, once extended to human disease, may prove useful as a noninvasive means of diagnosing cystic kidney diseases and to suggest novel therapeutic approaches. Thus, urine metabolomics has great diagnostic potential for cystic renal disorders and deserves further study.

ERK1/2-dependent vascular endothelial growth factor signaling sustains cyst growth in polycystin-2 defective mice

BACKGROUND & AIMS

Severe polycystic liver disease can complicate adult dominant polycystic kidney disease, a genetic disease caused by defects in polycystin-1 (Pkd1) or polycystin-2 (Pkd2). Liver cyst epithelial cells (LCECs) express vascular endothelial growth factor (VEGF) and its receptor, VEGFR-2. We investigated the effects of VEGF on liver cyst growth and autocrine VEGF signaling in mice with Pkd1 and Pkd2 conditional knockouts.

METHODS

We studied mice in which Pkd1 or Pkd2 were conditionally inactivated following exposure to tamoxifen; these mice were called Pkd1(flox/-):pCxCreER (Pkd1KO) and Pkd2(flox/-):pCxCreER (Pkd2KO).

RESULTS

Pkd1KO and Pkd2KO mice developed liver defects; their LCECs expressed VEGF, VEGFR-2, hypoxia-inducible factor (HIF)-1alpha, phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2), and proliferating cell nuclear antigen (PCNA). In Pkd2KO but not Pkd1KO mice, exposure to the VEGFR-2 inhibitor SU5416 significantly reduced liver cyst development, liver/body weight ratio, and expression of pERK and PCNA. VEGF secretion and phosphorylation of ERK1/2 and VEGFR-2 were significantly increased in cultured LCECs from Pkd2KO compared with Pkd1KO mice. Inhibition of protein kinase A (PKA) reduced VEGF secretion and pERK1/2 expression. Addition of VEGF to LCECs from Pkd2KO mice increased phosphorylated VEGFR-2 and phosphorylated mitogen signal-regulated kinase (MEK) expression and induced phosphorylation of ERK1/2; this was inhibited by SU5416. Expression of HIF-1alpha increased in parallel with secretion of VEGF following LCEC stimulation. VEGF-induced cell proliferation was inhibited by the MEK inhibitor U1026 and by ERK1/2 small interfering RNA.

CONCLUSIONS

The PKA-ERK1/2-VEGF signaling pathway promotes growth of liver cysts in mice. In Pkd2-defective LCECs, PKA-dependent ERK1/2 signaling controls HIF-1alpha-dependent VEGF secretion and VEGFR-2 signaling. Autocrine and paracrine VEGF signaling promotes the growth of liver cysts in Pkd2KO mice. VEGF inhibitors might be used to treat patients with polycystic liver disease.

Liver and kidney disease in ciliopathies

Hepatorenal fibrocystic diseases (HRFCDs) are among the most common inherited human disorders. The discovery that proteins defective in the autosomal dominant and recessive polycystic kidney diseases (ADPKD and ARPKD) localize to the primary cilia and the recognition of the role these organelles play in the pathogenesis of HRFCDs led to the term "ciliopathies." While ADPKD and ARPKD are the most common ciliopathies associated with both liver and kidney disease, variable degrees of renal and/or hepatic involvement occur in many other ciliopathies, including Joubert, Bardet-Biedl, Meckel-Gruber, and oral-facial-digital syndromes. The ductal plate malformation (DPM), a developmental abnormality of the portobiliary system, is the basis of the liver disease in ciliopathies that manifest congenital hepatic fibrosis (CHF), Caroli syndrome (CS), and polycystic liver disease (PLD). Hepatocellular function remains relatively preserved in ciliopathy-associated liver diseases. The major morbidity associated with CHF is portal hypertension (PH), often leading to esophageal varices and hypersplenism. In addition, CD predisposes to recurrent cholangitis. PLD is not typically associated with PH, but may result in complications due to mass effects. The kidney pathology in ciliopathies ranges from non-functional cystic dysplastic kidneys to an isolated urinary concentration defect; the disorders contributing to this pathology, in addition to ADPKD and ARPKD, include nephronophithisis (NPHP), glomerulocystic kidney disease and medullary sponge kidneys. Decreased urinary concentration ability, resulting in polyuria and polydypsia, is the first and most common renal symptom in ciliopathies. While the majority of ADPKD, ARPKD, and NPHP patients require renal transplantation, the frequency and rate of progression to renal failure varies considerably in other ciliopathies. This review focuses on the kidney and liver disease found in the different ciliopathies.

Lanreotide reduces the volume of polycystic liver: a randomized, double-blind, placebo-controlled trial

BACKGROUND & AIMS

Therapy for polycystic liver is invasive, expensive, and has disappointing long-term results. Treatment with somatostatin analogues slowed kidney growth in patients with polycystic kidney disease (PKD) and reduced liver and kidney volume in a PKD rodent model. We evaluated the effects of lanreotide, a somatostatin analogue, in patients with polycystic liver because of autosomal-dominant (AD) PKD or autosomal-dominant polycystic liver disease (PCLD).

METHODS

We performed a randomized, double-blind, placebo-controlled trial in 2 tertiary referral centers. Patients with polycystic liver (n = 54) were randomly assigned to groups given lanreotide (120 mg) or placebo, administered every 28 days for 24 weeks. The primary end point was the difference in total liver volume, measured by computerized tomography at weeks 0 and 24. Analyses were performed on an intention-to-treat basis.

RESULTS

Baseline characteristics were comparable for both groups, except that more patients with ADPKD were assigned to the placebo group (P = .03). The mean liver volume decreased 2.9%, from 4606 mL (95% confidence interval (CI): 547-8665) to 4471 mL (95% CI: 542-8401 mL), in patients given lanreotide. In the placebo group, the mean liver volume increased 1.6%, from 4689 mL (95% CI: 613-8765 mL) to 4895 mL (95% CI: 739-9053 mL) (P < .01). Post hoc stratification for patients with ADPKD or PCLD revealed similar changes in liver volume, with statistically significant differences in patients given lanreotide (P < .01 for both diseases).

CONCLUSIONS

In patients with polycystic liver, 6 months of treatment with lanreotide reduces liver volume.

Liver Cyst Cytokines Promote Endothelial Cell Proliferation and Development

Autosomal dominant polycystic kidney (ADPKD) is highly prevalent genetic disease. Liver cyst disease is the most common extrarenal manifestation in ADPKD and accounts for up to 10% of ADPKD morbidity and mortality. The clinical features of ADPKD liver disease arise from dramatic increases in liver cyst volumes. To identify mechanisms that promote liver cyst growth, the present study characterized the degree of vascularization of liver cyst walls and determined that cyst-specific cytokines and growth factors can drive endothelial cell proliferation and development. Microscopic techniques demonstrated liver cyst walls are well vascularized. A comparative analysis found the vascular density in free liver cyst walls was greater in mice than in humans. Treatment of human micro-vascular endothelial cells (HMEC-1) with human liver cyst fluid (huLCF) induced a rapid increase in vascular endothelium growth factor receptor 2 (VEGFR2) phosphorylation that persisted for 45–60 min and was blocked by 20 μM SU5416, a VEGFR tyrosine kinase inhibitor. Similarly, huLCF treatment of HMEC-1 cells induced an increase in the cell proliferation rate (131 ± 6% of control levels; P > 0.05) and the degree of vascular development (‘tube’ diameter assay: 92 ± 14 μm for huLCF vs. 12 ± 7 μm for vehicle); P > 0.05). Both cell proliferation and vascular development were sensitive to SU5416. These studies indicate that factors secreted by liver cyst epithelia can activate VEGF signaling pathways and induce endothelial cell proliferation and differentiation. The present studies suggest that targeting VEGFR2-dependent angiogenesis may be an effective therapeutic strategy in blocking ADPKD liver cyst vascularization and growth.

Autosomal dominant polycystic kidney disease: the last 3 years

Autosomal dominant polycystic kidney disease is the most prevalent, potentially lethal monogenic disorder. It has large inter- and intra-familial variability explained to a large extent by its genetic heterogeneity and modifier genes. An increased understanding of its underlying genetic, molecular, and cellular mechanisms and a better appreciation of its progression and systemic manifestations have laid out the foundation for the development of clinical trials and potentially effective therapies. The purpose of this review is to update the core of knowledge in this area with recent publications that have appeared during 2006-2009.

MRI-based kidney volume measurements in ADPKD: reliability and effect of gadolinium enhancement

BACKGROUND AND OBJECTIVES

To evaluate the inter- and intrareader reliability and the effect of gadolinium enhancement on kidney volume measurements obtained from pre- and postgadolinium T1 MR images in patients with autosomal dominant polycystic kidney disease (ADPKD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Twenty subjects were randomly selected with approximately equal frequency from three kidney-size groups. Pre- and postgadolinium 3D T1 (pre-T1, post-T1) MR images were obtained. The stereology method was applied to segment and measure kidney volumes. The measurement process was repeated at two-wk intervals by two radiologists. Reliability was assessed with correlation coefficients. Intra- and inter-reader bias and measure differences were assessed with paired T-tests. The size effect on the pre- and post-T1 measurements was evaluated with one-way ANOVA.

RESULTS

The intra- and inter-reader reliability was extremely high in all measurements. No systematic intrareader bias but a small inter-reader bias for the post-T1 measurements was observed. All kidney volumes measured on the pre- and post-T1 images were highly correlated with each other for both readers. The post-T1 volumes were significantly higher than pre-T1 volumes. While the post-pre volume differences were relatively constant across the three kidney-size groups, the post-pre percent volume differences were significantly smaller as the size of the kidney increased.

CONCLUSIONS

Kidney volume measurements can be made with minimum intra- and inter-reader variability on both pre- and post-T1 MR images. Kidney volumes measured on the pre-T1 were smaller than those on post-T1, and percent differences between pre-T1 and post-T1 kidney volumes decreased with increasing kidney size.

Review article: the evaluation of solitary liver masses

BACKGROUND

The increasing use of imaging modalities has led to the detection of more liver masses. The differential diagnosis of a focal liver mass includes a host of benign as well as malignant conditions.

AIM

To provide a comprehensive review on the commonly encountered liver masses, and to help guide an approach to their evaluation and management.

METHODS

Pertinent literature that was identified through PubMed search and senior author's experience formed the basis of this review.

RESULTS

While most incidentally noted liver masses are benign, it may be difficult to differentiate them from those that are malignant. Furthermore, some benign lesions have malignant potential. Certain lesions such as focal nodular hyperplasia, haemangiomas and focal steatosis are often distinctly diagnosed by an imaging modality alone. The less frequently encountered hepatic adenomas are diagnosed radiologically in those with the appropriate clinical background and the absence of radiological features to suggest haemangioma or focal nodular hyperplasia.

CONCLUSIONS

A reasonable approach to the diagnosis, follow-up and management of liver masses is based on a rudimentary knowledge of their presentation, associated clinical and laboratory features, natural history and available treatment options. Most often, the so called 'incidentalomas' are benign and require patient reassurance.