Because of its availability, ease of collection, and correlation with physiology and pathology, urine is an attractive source for clinical proteomics/peptidomics. However, the lack of comparable data sets from large cohorts has greatly hindered the development of clinical proteomics. Here, we report the establishment of a reproducible, high resolution method for peptidome analysis of naturally occurring human urinary peptides and proteins, ranging from 800 to 17,000 Da, using samples from 3,600 individuals analyzed by capillary electrophoresis coupled to MS. All processed data were deposited in an Structured Query Language (SQL) database. This database currently contains 5,010 relevant unique urinary peptides that serve as a pool of potential classifiers for diagnosis and monitoring of various diseases. As an example, by using this source of information, we were able to define urinary peptide biomarkers for chronic kidney diseases, allowing diagnosis of these diseases with high accuracy. Application of the chronic kidney disease-specific biomarker set to an independent test cohort in the subsequent replication phase resulted in 85.5% sensitivity and 100% specificity. These results indicate the potential usefulness of capillary electrophoresis coupled to MS for clinical applications in the analysis of naturally occurring urinary peptides. Molecular & Cellular Proteomics 9:2424 -2437, 2010.From the Departments of a Chemistry and

Abstract. The role of SGLT2 (the gene for a renal sodiumdependent glucose transporter) in renal glucosuria was evaluated. Therefore, its genomic sequence and its intron-exon organization were determined, and 23 families with index cases were analyzed for mutations. In 21 families, 21 different SGLT2 mutations were detected. Most of them were private; only a splice mutation was found in 5 families of different ethnic backgrounds, and a 12-bp deletion was found in two German families. Fourteen individuals (including the original patient with 'renal glucosuria type 0') were homozygous or compound heterozygous for an SGLT2 mutation resulting in glucosuria in the range of 14.

The aim of this manuscript is to initiate a constructive discussion about the definition of clinical proteomics, study requirements, pitfalls and (potential) use. Furthermore, we hope to stimulate proposals for the optimal use of future opportunities and seek unification of the approaches in clinical proteomic studies. We have outlined our collective views about the basic principles that should be considered in clinical proteomic studies, including sample selection, choice of technology and appropriate quality control, and the need for collaborative interdisciplinary efforts involving clinicians and scientists. Furthermore, we propose guidelines for the critical aspects that should be included in published reports. Our hope is that, as a result of stimulating discussion, a consensus will be reached amongst the scientific community leading to guidelines for the studies, similar to those already published for mass spectrometric sequencing data. We contend that clinical proteomics is not just a collection of studies dealing with analysis of clinical samples. Rather, the essence of clinical proteomics should be to address clinically relevant questions and to improve the state-of-the-art, both in diagnosis and in therapy of diseases.

Alport syndrome inevitably leads to end-stage renal disease and there are no therapies known to improve outcome. Here we determined whether angiotensin-converting enzyme inhibitors can delay time to dialysis and improve life expectancy in three generations of Alport families. Patients were categorized by renal function at the initiation of therapy and included 33 with hematuria or microalbuminuria, 115 with proteinuria, 26 with impaired renal function, and 109 untreated relatives. Patients were followed for a period whose mean duration exceeded two decades. Untreated relatives started dialysis at a median age of 22 years. Treatment of those with impaired renal function significantly delayed dialysis to a median age of 25, while treatment of those with proteinuria delayed dialysis to a median age of 40. Significantly, no patient with hematuria or microalbuminuria advanced to renal failure so far. Sibling pairs confirmed these results, showing that earlier therapy in younger patients significantly delayed dialysis by 13 years compared to later or no therapy in older siblings. Therapy significantly improved life expectancy beyond the median age of 55 years of the no-treatment cohort. Thus, Alport syndrome is treatable with angiotensin-converting enzyme inhibition to delay renal failure and therapy improves life expectancy in a time-dependent manner. This supports the need for early diagnosis and early nephroprotective therapy in oligosymptomatic patients.

Schimke immuno-osseous dysplasia is a multi-system autosomal recessive disorder with variable expression that affects the skeletal, renal, immune, vascular, and haematopoietic systems. Medical therapy is limited especially for more severely affected individuals.

Recommendations about structuring proteomic biomarker studies should increase the probability that such markers will be clinically useful.

This study was undertaken to compare the efficacy and safety of tacrolimus (Tac) with the microemulsion formulation of cyclosporin (CyA) in children undergoing renal transplantation. A 6-month, randomized, prospective, open, parallel group study with an open extension phase was conducted in 18 centers from nine European countries. In total, 196 pediatric patients (<18 years) were randomly assigned (1:1) to receive either Tac ( n=103) or CyA microemulsion ( n=93) administered concomitantly with azathioprine and corticosteroids. The primary endpoint was incidence and time to first acute rejection. Baseline characteristics were comparable between treatment groups. Tac therapy resulted in a significantly lower incidence of acute rejection (36.9%) compared with CyA therapy (59.1%) ( P=0.003). The incidence of corticosteroid-resistant rejection was also significantly lower in the Tac group compared with the CyA group (7.8% vs. 25.8%, P=0.001). The differences were also significant for biopsy-confirmed acute rejection (16.5% vs. 39.8%, P<0.001). At 1 year, patient survival was similar (96.1% vs. 96.6%), while 10 grafts were lost in the Tac group compared with 17 graft losses in the CyA group ( P=0.06). At 1 year, mean glomerular filtration rate (Schwartz estimate) was significantly higher in the Tac group (62+/-20 ml/min per 1.73 m(2), n=84) than in the CyA group (56+/-21 ml/min per 1.73 m(2), n=74, P=0.03). The most frequent adverse events during the first 6 months were hypertension (68.9% vs. 61.3%), hypomagnesemia (34.0% vs. 12.9%, P=0.001), and urinary tract infection (29.1% vs. 33.3%). Statistically significant differences ( P<0.05) were observed for diarrhea (13.6% vs. 3.2%), hypertrichosis (0.0% vs. 7.5%), flu syndrome (0.0% vs. 5.4%), and gum hyperplasia (0.0% vs. 5.4%). In previously non-diabetic children, the incidence of long-term (>30 days) insulin use was 3.0% (Tac) and 2.2% (CyA). Post-transplant lymphoproliferative disease was observed in 1 patient in the Tac group and 2 patients in the CyA group. In conclusion, Tac was significantly more effective than CyA microemulsion in preventing acute rejection after renal transplantation in a pediatric population. The overall safety profiles of the two regimens were comparable.

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