Association of cyclosporin A with acquired cystic kidney disease of the native kidneys in renal transplant recipients

Massive Acquired Renal Cysts Presenting with Bowel Obstruction-Like Symptoms

Acquired cystic kidney disease (ACKD) is rarely massive in size. The great majority is asymptomatic and incidentally found on imaging studies for unrelated causes. We reported a case of an 85-year-old male with bilateral multiple huge acquired renal infected cysts, initially presenting with bowel obstruction-like symptoms. The computed tomography (CT) scan later aided in an accurate diagnosis. Symptomatic huge ACKD has, to our knowledge, scarcely been described. In addition, retroperitoneal lesions resulting in abdominal pain remain unusual and underrecognized in general practice.

Acquired cystic kidney disease: an under-recognized condition in children with end-stage renal disease

Acquired cystic kidney disease (ACKD) is a condition that occurs predominantly in patients with end-stage renal disease (ESRD). In contrast to hereditary cystic kidney disease, ACKD is characterized by the presence of multiple small cysts in bilaterally small kidneys. Limited pediatric data suggest a high incidence (21.6-45.8%) of ACKD in children on dialysis, comparable to that in adults, with an increased frequency associated with a longer duration of dialysis. Recent research has shed light on the pathogenesis of ACKD, such as activation of proto-oncogenes. Although most patients with ACKD are asymptomatic, the condition can be complicated by renal cell carcinoma. Routine surveillance should therefore be considered in at-risk populations.

Evaluating the Oxidative Stress in Renal Diseases: What Is the Role for S-Glutathionylation?

SIGNIFICANCE

Reactive oxygen species (ROS) have long been considered as toxic derivatives of aerobic metabolism displaying a harmful effect to living cells. Deregulation of redox homeostasis and production of excessive free radicals may contribute to the pathogenesis of kidney diseases. In line, oxidative stress increases in patients with renal dysfunctions due to a general increase of ROS paralleled by impaired antioxidant ability.

RECENT ADVANCES

Emerging evidence revealed that physiologically, ROS can act as signaling molecules interplaying with several transduction pathways such as proliferation, differentiation, and apoptosis. ROS can exert signaling functions by modulating, at different layers, protein oxidation since proteins have "cysteine switches" that can be reversibly reduced or oxidized, supporting the dynamic signaling regulation function. In this scenario, S-glutathionylation is a posttranslational modification involved in oxidative cellular response.

CRITICAL ISSUES

Although it is widely accepted that renal dysfunctions are often associated with altered redox signaling, the relative role of S-glutathionylation on the pathogenesis of specific renal diseases remains unclear and needs further investigations. In this review, we discuss the impact of ROS in renal health and diseases and the role of selective S-glutathionylation proteins potentially relevant to renal physiology.

FUTURE DIRECTIONS

The paucity of studies linking the reversible protein glutathionylation with specific renal disorders remains unmet. The growing number of S-glutathionylated proteins indicates that this is a fascinating area of research. In this respect, further studies on the association of reversible glutathionylation with renal diseases, characterized by oxidative stress, may be useful to develop new pharmacological molecules targeting protein S-glutathionylation. Antioxid. Redox Signal. 25, 147-164.

Incidence, predictors, costs, and outcome of renal cell carcinoma after kidney transplantation: USRDS experience

INTRODUCTION

We carried out an analysis of the United States Renal Data System to determine the incidence, risk factors, prognosis, and costs associated with the diagnosis of renal cell carcinoma (RCC) after kidney transplantation.

METHODS

This is a retrospective cohort of 40,821 Medicare primary renal transplant recipients transplanted from January 1, 2000, to July 1, 2005, and followed up till December 31, 2005, excluding those with prior RCC or nephrectomy. Kaplan-Meier analysis was performed to determine the time of occurrence of RCC, and Cox regression was used to determine factors associated with RCC.

RESULTS

Three hundred sixty-eight patients were diagnosed with RCC within 3 years after transplant (incidence of 3.16 per 1000 person years). The 3-year incidence of RCC posttransplant was 9.29 per 1000 person years (2.3%) for those with pretransplant cysts and 3.08 per 1000 person years (0.7%) without pretransplant cysts. RCC was diagnosed disproportionately early posttransplant in patients with cysts. Cysts were independently associated with increased risk of RCC, as was male gender, older recipient, donor age, African American recipient, increased time on dialysis and acute rejection within first year posttransplant. RCC was associated with increased risk of mortality with a higher risk with pretransplant cysts. Patients who developed RCC had higher cumulative median costs ($55,456 at 2 years) than those who did not develop RCC ($40,369). There was no "clustering" of RCC in individual states or centers more than would be expected by chance.

CONCLUSION

RCC was diagnosed disproportionately early in patients with pretransplant renal cysts and was associated with a worse prognosis and increased costs.

Cyclic nucleotide signaling in polycystic kidney disease

Increased levels of 3'-5'-cyclic adenosine monophosphate (cAMP) stimulate cell proliferation and fluid secretion in polycystic kidney disease. Levels of this molecule are more sensitive to inhibition of phosphodiesterases (PDEs), whose activity far exceeds the rate of cAMP synthesis by adenylyl cyclase. Several PDEs exist, and here we measured the activity and expression of PDE families, their isoforms, and the expression of downstream effectors of cAMP signaling in the kidneys of rodents with polycystic kidney disease. We found a higher overall PDE activity in kidneys from mice as compared with rats, as well as a higher contribution of PDE1, relative to PDE4 and PDE3, to total PDE activity of kidney lysates and lower PDE1, PDE3, and PDE4 activities in the kidneys of cystic as compared with wild-type mice. There were reduced amounts of several PDE1, PDE3, and PDE4 proteins, possibly due to increased protein degradation despite an upregulation of their mRNA. Increased levels of cGMP were found in the kidneys of cystic animals, suggesting in vivo downregulation of PDE1 activity. We found an additive stimulatory effect of cAMP and cGMP on cystogenesis in vitro. Cyclic AMP-dependent protein kinase subunits Ialpha and IIbeta, PKare, the transcription factor CREB-1 mRNA, and CREM, ATF-1, and ICER proteins were upregulated in the kidneys of cystic as compared with wild-type animals. Our study suggests that alterations in cyclic nucleotide catabolism may render cystic epithelium particularly susceptible to factors acting on Gs-coupled receptors. This may account, in part, for increased cyclic nucleotide signaling in polycystic kidney disease and contribute substantially to disease progression.

Acquired renal cysts after pediatric liver transplantation: association with cyclosporine and renal dysfunction

ACKD has been observed in children on dialysis and with chronic renal insufficiency. In one report, ACKD was observed in 30% of pediatric liver transplant recipients after 10 yr. We retrospectively reviewed all renal imaging and measurements of GFR of 235 childhood liver transplant recipients with no known risk for renal cyst formation, no evidence of renal cyst(s) at the time of transplantation and renal imaging at least one yr post-transplant. Twenty-six patients (11%) developed one or more cyst(s). Mean GFR was significantly lower in patients with renal cyst(s). Two (1.4%) of the 146 patients treated with tacrolimus and 24 (27%) of the 89 patients treated with CsA acquired renal cyst(s) (p < 0.001). CsA-treated patients had significantly lower GFR. Multivariate analysis identified CsA as the only independent variable associated with ACKD. These results confirm that ACKD can be a late complication of pediatric liver transplantation. Those at most risk are at least 10-yr post-liver transplantation, have been treated with CsA and have impaired renal function. We speculate that ACKD in these patients is the result of calcineurin inhibitor nephrotoxicity. Whether patients with ACKD will be prone to develop solid renal tumors is unknown.

Sirolimus reduces polycystic liver volume in ADPKD patients

The immunosuppressive agent sirolimus exerts an antiproliferative effect by inhibiting mammalian target of rapamycin (mTOR). Because excessive proliferation of the biliary epithelium is a prominent feature of the polycystic liver that accompanies autosomal dominant polycystic kidney disease (ADPKD), we hypothesized that sirolimus may benefit patients with this disorder. We retrospectively measured the volumes of polycystic livers and kidneys in ADPKD patients who had received kidney transplants and had participated in a prospective randomized trial that compared a sirolimus-containing immunosuppression regimen to a tacrolimus-containing regimen. Sixteen subjects (seven with sirolimus, nine with tacrolimus) had received abdominal imaging studies within 11 mo before and at least 7 mo after transplantation, making them suitable for our analysis. Treatment with the sirolimus regimen for an average of 19.4 mo was associated with an 11.9 +/- 0.03% reduction in polycystic liver volume, whereas treatment with tacrolimus for a comparable duration was associated with a 14.1 +/- 0.09% increase. A trend toward a greater reduction in native kidney volume was also noted in the sirolimus group compared with the nonsirolimus group. Regarding mechanism, the epithelium that lines hepatic cysts exhibited markedly higher levels of phospho-AKT, phospho-ERK, phospho-mTOR, and the downstream effector phospho-S6rp compared with control biliary epithelium. In summary, treatment with sirolimus was associated with decreased polycystic liver volume, perhaps by preventing aberrant activation of mTOR in epithelial cells lining the cysts.

Spontaneous retroperitoneal hemorrhage due to acquired cystic kidney disease

A patient with end-stage renal disease on maintenance hemodialysis developed sudden severe abdominal pain and distension. He suffered a decline in his hematocrit and subsequent abdominal imaging revealed a large left-sided retroperitoneal hemorrhage in the setting of atrophic, severely cystic kidneys. He underwent selective left renal artery angiography and embolization due to continued hemorrhage with stabilization in his condition. However, he became paraparetic within hours of the embolization procedure due to spinal cord infarct. Acquired cystic kidney disease is a very common entity in patients with chronic kidney disease. Complications include cystic hemorrhage or infection, erythrocytosis, and renal cell carcinoma. Screening of patients for cystic disease and malignant transformation remains a controversial topic; however, most advocate abdominal imaging after 3 to 5 years on dialysis.

Renal Cell Carcinoma in Transplant Recipients with Acquired Cystic Kidney Disease

BACKGROUND

Acquired cystic kidney disease (ACKD) is a widely known renal cell carcinoma risk factor.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

An ultrasound screening of the native kidneys in all renal transplant patients of a renal outpatient clinic who received a transplant between 1970 and 1998 and presented between 1997 and 2003 (n = 916) was initiated prospectively. A total of 561 patients were screened.

RESULTS

A total of 129 (23%) patients had ACKD; 46 (8.2%) patients had complex renal cysts (Bosniak classification, category IIF to III); and eight (1.5%) patients had newly diagnosed renal cell carcinoma, seven of which were associated with ACKD (category IV). One patient had renal cell carcinoma in the transplanted kidney. Together with 19 patients of the cohort with formerly diagnosed renal cell carcinoma (18 of them associated with ACKD), the prevalence of renal cell carcinoma among all patients was 4.8%; among the patients with ACKD, it was 19.4% (without ACKD 0.5%; P = 0.0001); and among the patients with complex renal cysts (category IIF to III), it was 54.4%. The patients with ACKD were older (54 +/- 13 versus 51 +/- 14 yr; P = 0.048), more often male (65 versus 54%; P = 0.03), more often had heart disease (44 versus 29%; P = 0.001), had larger kidneys (6.9 and 6.8 cm versus 6.0 and 5.9 cm; P < 0.001), and had more calcifications (29 versus 15%; P = 0.002). Renal cell carcinoma was bilateral in 26% of cases. Tumor histology was clear cell carcinoma in 58% and papillary carcinoma in 42% of cases; one patient had both. Only one patient had a lung metastasis, and no patient died.

CONCLUSIONS

Renal cell carcinoma occurs often after renal transplantation and that especially patients with ACKD should routinely be screened. Because ACKD after renal transplantation seems to be less frequent (23%) than during dialysis treatment (30 to 90%), renal transplantation may inhibit renal cell carcinoma.

New insights into ADPKD molecular pathways using combination of SAGE and microarray technologies

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in the PKD1 or PKD2 gene, but cellular mechanisms of cystogenesis remain unclear. In an attempt to display the array of cyst-specific molecules and to elucidate the disease pathway, we have performed comprehensive high-throughput expression analysis of normal and ADPKD epithelia in a two-step fashion. First, we generated expression profiles of normal and cystic epithelia derived from kidney and liver using serial analysis of gene expression (SAGE). We found 472 and 499 differentially expressed genes with fivefold difference in liver and kidney libraries, respectively. These genes encode growth factors, transcription factors, proteases, apoptotic factors, molecules involved in cell-extracellular matrix interactions, and ion channels. As a second step, we constructed a custom cDNA microarray using a subset of the differentially regulated genes identified by SAGE and interrogated ADPKD patient samples. Subsequently, a set of differentially expressed genes was refined to 26 up-regulated and 48 down-regulated genes with ap value of <0.01. This study may provide valuable insights into the pathophysiology of ADPKD and suggest potential therapeutic targets.

Prospective pretransplant ultrasound screening in 206 patients for acquired renal cysts and renal cell carcinoma

BACKGROUND

Numerous studies have reported an increased prevalence of renal cell carcinoma in association with acquired cystic kidney disease (ACKD). In 1995, the clinical practice guidelines of the American Society of Transplant Physicians for evaluation of renal transplant candidates recommend not screening for ACKD and renal cell carcinoma, on the basis of the low frequency of cancer and reported regression of ACKD after transplantation. The objective of this study was to prospectively evaluate the prevalence of ACKD and renal cancer during renal transplant evaluation.

METHODS

A total of 206 consecutive adult patients evaluated for renal transplantation underwent a routine renal ultrasound. Patients with a suspicious ultrasound underwent a contrasted computed tomographic scan of the kidneys followed by excision of kidneys with solid, enhancing (>10 Hounsfield units) lesions.

RESULTS

Sixty-three (30.6%) of 206 patients had ACKD, with a greater proportion being male, African-American, and dialysis-dependent for a longer duration. Eight patients (3.8%) had histologically proven localized cancer (six unilateral, two bilateral), seven in association with ACKD and one in association with autosomal dominant polycystic kidney disease. With a mean follow-up of 14 months (range, 3-33 mo), there has been no recurrence. The positive predictive value of a solid lesion on ultrasound was 100% (8 of 8 patients).

CONCLUSION

With the high prevalence (3.4%) of renal cell carcinoma in association with ACKD and the concern that immunosuppression accelerates the growth of preexisting cancers, we continue to recommend ultrasound screening of the native kidneys before renal transplantation.

New insights into polycystic kidney disease and its treatment

Major advances in the understanding of the genetics and pathogenesis of autosomal dominant polycystic kidney disease have occurred within the past year. The proteins encoded by the PKD1 and PKD2 genes, polycystin 1 and polycystin 2, are membrane proteins, capable of interacting physically in vitro, and are likely components of a complex signalling pathway. The majority of PKD1 and PKD2 mutations so far identified are unique inactivating mutations dispersed over the entire genes. Immunohistochemical studies have shown that polycystin 1 and polycystin 2 are developmentally regulated and are overexpressed in polycystic kidneys. The cysts probably result from clonal expansions of single cells. The demonstration of loss of heterozygosity for PKD1 and the absence of immunoreactive polycystin 1 in approximately 20% of the cysts supports a two-hit tumor suppressor gene model of cystogenesis. Regardless of the nature of the initial pathogenic mechanism, the cysts in autosomal dominant polycystic kidney disease are accompanied by partial dedifferentiation of the epithelial cells, disregulation of epithelial cell proliferation, expression of a secretory phenotype, and disarray of cell matrix interactions which leads to interstitial inflammation and matrix accumulation. Recent observations in animal models of inherited polycystic kidney disease have implicated oxidative stress in its pathogenesis. These downstream pathogenetic events have been targeted for intervention, and an increasing number of studies have demonstrated that the course of polycystic kidney disease in rodents can be altered by environmental and pharmacological interventions. Nevertheless, these experimental observations cannot be extrapolated to human autosomal dominant polycystic kidney disease. The recent generation of mice with PKD1 or PKD2 targeted mutations will help to bridge this gap.

Metastatic renal carcinoma in a pediatric recipient of an adult cadaveric donor kidney

A 15-year old male with chronic renal failure secondary to obstructive uropathy received an adult cadaveric donor kidney. Evaluation for painless macroscopic hematuria occurring 2 years after transplantation disclosed a metastatic renal cell carcinoma, which by the use of restriction fragment length polymorphism analysis was shown to be of the donor's origin. Transplant nephrectomy and cessation of immunosuppressive therapy resulted in complete regression of multiple pulmonary metastases.

Polycystic kidney disease: etiology, pathogenesis, and treatment

Once viewed as hopelessly incurable disorders and the dustbin for careers in academic medicine, the polycystic kidney diseases have emerged as prime targets of pathophysiologic study and palliative and definitive treatment in the era of molecular medicine. Polycystic kidney disease (PKD) may be hereditary or acquired. The major inherited types are autosomal dominant (AD) and autosomal recessive (AR). ADPKD is caused by at least two (and possibly three) genes located on separate chromosomes, while ADPKD-1 is due to a 14 kb transcript in a duplicated region on the short arm of chromosome 16 very near the alpha-globin gene cluster and the gene for one form of tuberous sclerosis. ADPKD-2 has been assigned to the long arm of chromosome 4. ARPKD is due to a mutated gene on both copies of the long arm of chromosome 6. Cysts originate in renal tubules. Proliferation of tubule epithelial cells modulated by endocrine, paracrine, and autocrine factors is a major element in the pathogenesis of renal cystic diseases. In addition, fluid that is abnormally accumulated within the cysts is derived from glomerular filtrate and, to a greater extent, by transepithelial fluid secretion. Abnormal synthesis and degradation of matrix components associated with interstitial inflammation are additional features in the pathogenesis of renal cystic diseases. The ADPKD genotypes are characterized by bilateral kidney cysts, hypertension, hematuria, renal infection, stones, and renal insufficiency. ADPKD is a systemic disorder; cysts appear with decreasing frequency in the kidneys, liver, pancreas, brain, spleen, ovaries, and testis. Cardiac valvular disorders, abdominal and inguinal hernias, and aneurysms of cerebral and coronary arteries and aorta are also associated with ADPKD. Treatment is supportive: dietary regulation of salt and protein intake, control of hypertension and renal stones, and dialysis and transplantation at the end stage. ARPKD is a relatively rare disease that causes clinical symptoms at birth, with significant mortality in the first month of life. The cysts develop primarily in the collecting ducts because of a failure in the maturation process. Early complications include Potter's syndrome; excessive size of the kidneys, causing respiratory dysfunction; hypertension; and renal insufficiency. Hepatic fibrosis is an associated extrarenal problem that results in significant morbidity in young children and adolescents. Treatment includes supportive care, dialysis, and renal transplantation. Acquired cysts (solitary/simple) are commonplace in older persons. Multiple cysts may be seen in association with potassium deficiency, congenital disorders, metabolic diseases, and toxic renal injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Screening for acquired cystic kidney disease: a decision analytic perspective

Acquired cystic kidney disease (ACKD) increases the risk of renal malignancy, and many authors suggest routine screening of dialysis patients for ACKD and renal tumors. However, they have defined neither the target population, the optimal screening strategy, the magnitude of its benefit, nor its risk. We used decision analysis to evaluate strategies of performing either computed tomography (CT) or ultrasound every three years on all dialysis patients and annually on patients found to have cysts. We compared these strategies to a strategy of seeking cysts and cancer only if these are clinically suspected. The baseline analysis shows that both CT and ultrasound may decrease cancer deaths by half for patients with a life expectancy of 25 years. Screening for ACKD offers these patients as much as a 1.6 year gain in life expectancy. However, for the majority of patients beginning renal replacement therapy, age or comorbid disease substantially limits life expectancy. For such patients, the gain in life expectancy from an ACKD screening program is measured in days. Sensitivity analyses show that the benefit of screening depends on the rate of malignant transformation, which needs better definition. The gain in life expectancy does not appear to be large enough to justify an ACKD screening program for the entire ESRD population. However, for the youngest and healthiest patients, a screening program would be of benefit. The magnitude of this benefit is uncertain, because the analysis was consistently biased in favor of the screening strategies.

Renal neoplasm in acquired cystic kidney disease

The development of renal cell neoplasms ranging from adenoma to metastatic carcinoma is the most serious complication of acquired cystic kidney disease (ACKD). A comprehensive review of the pertinent literature shows that there is up to 50-fold increased risk of renal cell carcinoma in ACKD compared to the general population. The ACKD-associated renal cell carcinoma is seen predominantly in males, occurs approximately 20 years earlier than in the general population, and is frequently bilateral (9%) and multicentric (50%). Acquired cystic kidney disease-associated renal cell carcinoma is frequently asymptomatic (86%), but may be associated with bleeding, abrupt changes in hematocrit, fever, and flank pain or rarely with hypoglycemia, hypercalcemia, or metastases at presentation. Computed tomography seems to provide a better diagnostic yield than sonography or magnetic resonance imaging; nevertheless, large (up to 8 cm) tumors not visualized by any imaging techniques have been reported. It is generally agreed that there is a need for regular screening of symptomatic ACKD patients for early detection of renal cell carcinoma; however, whether screening is needed for asymptomatic patients remains controversial. Nephrectomy is indicated for tumors larger than 3 cm. Management for tumors smaller than 3 cm with persistent symptoms, such as back pain or hematuria, remains controversial, but nephrectomy may be recommended since many of these tumors turn out to be unequivocal renal cell carcinoma. Asymptomatic tumors smaller than 3 cm should be serially screened, and tumor enlargement may be an indication for nephrectomy. Acquired cystic kidney disease-associated renal cell carcinoma accounts for approximately 2% of deaths in renal transplant patients. A median length of survival of approximately 14 months and a 5-year survival rate of 35% are comparable to the same data for renal cell carcinoma in the general population. Successful renal transplant probably decreases the risk of renal cell carcinoma in ACKD patients, but this preliminary observation needs confirmation. The development of ACKD-associated renal carcinoma is a continuous process with evolving phenotypic expression, including damaged renal tubule, simple cyst, cyst with atypical lining, adenoma, and, finally, carcinoma. The pathogenesis of this continuous process is not entirely known, but growth factor-induced compensatory growth of tubular epithelium initiated by the changes of end-stage kidney disease, and probably perpetuated by activation of proto-oncogenes, seems to be the most significant factor.