Association between urinary dickkopf-3, acute kidney injury, and subsequent loss of kidney function in patients undergoing cardiac surgery: an observational cohort study

BACKGROUND

Cardiac surgery is associated with a high risk of postoperative acute kidney injury (AKI) and subsequent loss of kidney function. We explored the clinical utility of urinary dickkopf-3 (DKK3), a renal tubular stress marker, for preoperative identification of patients at risk for AKI and subsequent kidney function loss.

METHODS

This observational cohort study included patients who had cardiac surgery in a derivation cohort and those who had cardiac surgery in a validation cohort (RenalRIP trial). The study comprised consecutive patients who had elective cardiac surgery at the Saarland University Medical Centre (Homburg, Germany; derivation cohort) and those undergoing elective cardiac surgery (selected on the basis of a Cleveland Clinical Foundation score of 6 or higher) who were enrolled in the prospective RenalRIP multicentre trial (validation cohort) and who were randomly assigned to remote ischaemic preconditioning or a sham procedure. The association between the ratio of preoperative urinary concentrations of DKK3 to creatinine (DKK3:creatinine) and postoperative AKI, defined according to the Kidney Disease Improving Global Outcomes criteria, and subsequent kidney function loss, as determined by estimated glomerular filtration rate, was assessed.

FINDINGS

In the 733 patient in the derivation cohort, urinary concentrations of DKK3 to creatinine that were higher than 471 pg/mg were associated with significantly increased risk for AKI (odds ratio [OR] 1·65, 95% CI 1·10-2·47, p=0·015), independent of baseline kidney function. Compared with clinical and other laboratory measurements, urinary concentrations of DKK3:creatinine significantly improved AKI prediction (net reclassification improvement 0·32, 95% CI 0·23-0·42, p<0·0001). High urinary DKK3:creatinine concentrations were independently associated with significantly lower kidney function at hospital discharge and after a median follow-up of 820 days (IQR 733-910). In the RenalRIP trial, preoperative urinary DKK3:creatinine concentrations higher than 471 pg/mg were associated with a significantly higher risk for AKI (OR 1·94, 95% CI 1·08-3·47, p=0·026), persistent renal dysfunction (OR 6·67, 1·67-26·61, p=0·0072), and dialysis dependency (OR 13·57, 1·50-122·77, p=0·020) after 90 days compared with DKK3:creatinine concentrations of 471 pg/mg or less. Urinary DKK3:creatinine concentrations higher than 471 pg/mg were associated with significantly higher risk for AKI (OR 2·79, 95% CI 1·45-5·37) and persistent renal dysfunction (OR 3·82, 1·32-11·05) only in patients having a sham procedure, but not remote ischaemic preconditioning (AKI OR 1·35, 0·76-2·39 and persistent renal dysfunction OR 1·05, 0·12-9·45).

INTERPRETATION

Preoperative urinary DKK3 is an independent predictor for postoperative AKI and for subsequent loss of kidney function. Urinary DKK3 might aid in the identification of patients in whom preventive treatment strategies are effective.

FUNDING

No study funding.

Urine and serum midkine levels in an Australian chronic kidney disease clinic population: an observational study

BACKGROUND AND OBJECTIVES

The cytokine midkine (MK) is pathologically implicated in progressive chronic kidney disease (CKD) and its systemic consequences and has potential as both a biomarker and therapeutic target. To date, there are no published data on MK levels in patients with different stages of CKD. This study aims to quantify MK levels in patients with CKD and to identify any correlation with CKD stage, cause, progression, comorbid disease or prescribed medication.

METHODS

In this observational, single-centre study, demographic data were collected, and serum and urine assayed from 197 patients with CKD and 19 healthy volunteers in an outpatient setting.

RESULTS

The median serum and urine MK level in volunteers was 754 pg/mL (IQR: 554-1025) and 239 pg/mL (IQR: 154-568), respectively. Compared with serum MK in stage 1 CKD (660 pg/mL, IQR: 417-893), serum MK increased in stage 3 (1878 pg/mL, IQR: 1188-2756; p<0.001), 4 (2768 pg/mL, IQR: 2065-4735; p<0.001) and 5 (4816 pg/mL, IQ: 37477807; p<0.001). Urine MK levels increased from stage 1 CKD (343 pg/mL, IQR: 147-437) to stage 3 (1007 pg/mL, IQR: 465-2766; p=0.07), 4 (2961 pg/mL, IQR: 1368-5686; p=0.005) and 5 (6722 pg/mL, IQR: 3796-10 060; p=0.001). Fractional MK excretion (FeMK) increased from stage 1 CKD (0.159, IQR: 0.145-0.299) to stage 3 (1.024, IQR: 0.451-1.886, p=0.047), 4 (3.39, IQR: 2.10-5.82, p=0.004) and 5 (11.95, IQR: 5.36-24.41, p<0.001). When adjusted for estimated glomerular filtration rate, neither serum nor urine MK correlated with primary CKD diagnosis or CKD progression (small sample). There was a positive correlation between protein:creatinine ratio and FeMK (p=0.003). Angiotensin blockade (adjusted for proteinuria) was associated with lower urine MK (p=0.018) and FeMK (p=0.025).

CONCLUSION

MK levels sequentially rise with CKD stage beyond stage 2, and our data support existing animal evidence for an MK/renin angiotensin-system/proteinuria relationship. To what extent this is related to renal clearance versus pathology, or the consequences of chronically elevated MK levels requires further exploration.

Serum and Urinary Progranulin in Diabetic Kidney Disease

Progranulin has been recognized as an adipokine related to obesity, insulin resistance and type 2 diabetes mellitus (T2DM). There are scarce data regarding progranulin and kidney disease, but there are some data linking diabetic kidney disease (DKD) and increased progranulin levels. We aimed to better describe the relationship between serum and urinary progranulin levels and DKD in T2DM. This is a case-control study including four groups of subjects: 1) Advanced DKD cases: T2DM patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m²; 2) Albuminuric DKD cases: T2DM patients with urinary albumin excretion (UAE) ≥30 mg/g creatinine and eGFR ≥60 mL/min/1.73m²; 3) Diabetic controls: T2DM patients with UAE <30 mg/g creatinine and eGFR ≥60 mL/min/1.73m²; and 4) Non-diabetic controls: individuals without T2DM. Progranulin was determined by enzyme-linked immunosorbent assay. One hundred and fourteen patients were included (23 advanced DKD cases, 25 albuminuric DKD cases, 40 diabetic controls and 26 non-diabetic controls). Serum progranulin was increased in advanced DKD compared to other groups [70.84 (59.04–83.16) vs. albuminuric cases 57.16 (42.24–67.38), diabetic controls 57.28 (42.08–70.47) and non-diabetic controls 44.54 (41.44–53.32) ng/mL; p<0.001]. Urinary progranulin was decreased in advanced DKD cases compared to albuminuric cases [10.62 (6.30–16.08) vs. 20.94 (12.35–30.22); diabetic controls 14.06 (9.88–20.82) and non-diabetic controls 13.51 (7.94–24.36) ng/mL; p = 0.017]. There was a positive correlation between serum progranulin and body mass index (r = 0.27; p = 0.004), waist circumference (r = 0.25; p = 0.007); body fat percentage (r = 0.20; p = 0.042), high-sensitive C reactive protein (r = 0.35; p<0.001) and interleukin-6 (r = 0.37; p<0.001) and a negative correlation with eGFR (r = -0.22; p = 0.023). Urinary progranulin was positively associated with albuminuria (r = 0.25; p = 0.010). In conclusion, progranulin is affected by a decrease in eGFR, being at a higher concentration in serum and lower in urine of DKD patients with T2DM and eGFR <60 mL/min/1.73m². It is also associated with markers of obesity and inflammation.

Diagnostic value of progranulin in patients with lupus nephritis and its correlation with disease activity

The aim of this study was to explore whether progranulin (PGRN) can be a useful marker not only for accurate diagnosis of patients with active lupus nephritis (LN), but also for prediction of the disease activity in this population. A total of 154 LN patients were enrolled in this study, 76 of which were diagnosed as having active LN and 78 as having stable LN. Additionally, 71 age-matched non-LN patients were enrolled as controls. The serum and urine PGRN levels of each study population were measured using the enzyme-linked immunosorbent assay method. The diagnostic performance of both indicators and their correlation with the disease activity of LN were systematically investigated using receiver operating characteristic (ROC) analysis and correlation analysis. The active LN population had significantly higher serum and urine PGRN levels than the other two populations. ROC analysis further demonstrated that these two indicators, particularly in combination, appear to have a strong performance in discriminating active LN patients from the rest of the LN population. In the active LN population, serum and urine PGRN levels were not only significantly correlated with SLEDAI score, rSLEDAI score, and activity index, but also had a considerable association with several key markers reflecting the disease activity of LN, including serum levels of complement component 3 and ds-DNA. Nevertheless, neither of the two indicators were correlated with the pathological classification of LN, chronicity index, serum creatinine level, and 24-h urine protein levels. Our findings demonstrate that PGRN may have great potential as a diagnostic factor for active LN and as a predictor for its disease activity.

New detection methods of growth hormone and growth factors

Human growth hormone (GH), but also GH related growth factors like the insulin-like growth factor-1 (IGF-1) are known to be abused in sports. Although the scientific evidence supporting a distinct effect of GH on performance in healthy trained subjects is limited, it has been repeatedly found with athletes or trainers, and the recent introduction of a first test to detect GH doping has led to a number of positive cases. Currently, there is no test for the detection of IGF-1 introduced worldwide, but confiscation of the drug from sports teams can be taken as indirect evidence for its abuse. The major biochemical difficulty for the detection of GH is that the recombinant form is identical in physicochemical properties to the endogenous GH secreted by the pituitary gland. Furthermore, the very short half-life of GH in circulation inherently shortens the window of opportunity where the drug can be detected. Two strategies have been followed for more than a decade to develop a test to detect the application of recombinant GH: the marker approach, which is based on the elevation of GH-dependent markers above the level seen under physiological conditions evoked by administration of recombinant GH, and the isoform approach, which is based on a change in the pattern of GH isoforms in circulation following the injection of recombinant GH.

Connective tissue growth factor and susceptibility to renal and vascular disease risk in type 1 diabetes

OBJECTIVE

We explored the relevance and significance of connective tissue growth factor (CTGF) as a determinant of renal and vascular complications among type 1 diabetic patients.

METHODS AND RESULTS

We measured the circulating and urinary levels of CTGF and CTGF N fragment in 1050 subjects with type 1 diabetes from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study cohort. We found that hypertensive diabetic subjects have significantly higher levels of plasma log CTGF N fragment relative to normotensive subjects (P = 0.0005). Multiple regression analysis showed a positive and independent association between CTGF N fragment levels and log albumin excretion rate (P < 0.0001). In categorical analysis, patients with macroalbuminuria had higher levels of CTGF N fragment than diabetic subjects with or without microalbuminuria (P < 0.0001). Univariate and multiple regression analyses demonstrated an independent and significant association of log CTGF N fragment with the common and internal carotid intima-media thickness. The relative risk for increased carotid intima-media thickness was higher in patients with concomitantly elevated plasma CTGF N fragment and macroalbuminuria relative to patients with normal plasma CTGF N fragment and normal albuminuria (relative risk = 4.76; 95% confidence interval, 2.21-10.25; P < 0.0001).

CONCLUSION

These findings demonstrate that plasma CTGF is a risk marker of diabetic renal and vascular disease.

Presence of immunoreactive salusin-alpha in human serum and urine

Salusins, identified from a full-length enriched human cDNA library by bioinformatics analyses, show mitogenic, neuromodulatory and hemodynamic activities in rats. They are expressed in a wide variety of human tissues, but their precise structures and levels in human body fluids remain unknown. We developed a radioimmunoassay suitable for the detection of immunoreactive human salusin-alpha and characterized the molecular forms and concentrations of salusin-alpha in human serum and urine. The assay allowed for measurement of immunoreactive salusin-alpha concentrations as low as 1 fmol/tube after extraction of serum with an octyl-silica column, and the concentration required for 50% inhibition of binding was 40 fmol/tube. Cross-reactivities with salusin-beta and other bioactive peptides were negligible. Salusin-alpha-like immunoreactivity in normal human serum and urine ranged from 11.0 to 40.4 pmol/l (mean+/-S.D., 23.3+/-8.1 pmol/l, n=31) and from 18.6 to 367.3 pmol/l (mean+/-S.D., 156.8+/-95.8 pmol/l), respectively. Reverse-phase high performance liquid chromatography coupled with radioimmunoassay detection revealed a major immunoreactive component that coeluted with authentic salusin-alpha. These data indicate the presence of salusin-alpha in human serum and urine, thereby verifying the initially predicted processing sites for salusin-alpha in humans.

Combination analysis of hypermethylated Wnt-antagonist family genes as a novel epigenetic biomarker panel for bladder cancer detection

PURPOSE

Aberrant promoter hypermethylation of Wnt-antagonist genes contributes to the pathogenesis of several cancers. We hypothesized that combined methylation analysis of Wnt-antagonist genes could improve their use as a panel of biomarkers for diagnosing and staging of bladder cancers.

EXPERIMENTAL DESIGN

Samples (54 total) of bladder tumor and corresponding normal bladder mucosa were analyzed for the methylation and expression levels of six Wnt-antagonist genes (sFRP-1, sFRP-2, sFRP-4, and sFRP-5, Wif-1, and Dkk-3). To increase the sensitivity/specificity of bladder tumor detection, the methylation score (M score), a new method for multigene methylation analysis, was developed. The M score of each sample was calculated as the sum of the corresponding log hazard ratio coefficients derived from multivariate logistic regression analysis of the methylation status for each Wnt-antagonist gene. Receiver operator characteristic (ROC) curve analysis was used to determine the optimal sensitivity/specificity of the M score. Urine DNA from 24 matched patients with bladder tumor and 20 cancer-free volunteers was also used to investigate the methylation status of Wnt-antagonist genes.

RESULTS

The methylation levels of Wnt-antagonists were significantly higher and mRNA levels were significantly lower in bladder tumor than in bladder mucosa. Each methylation level was inversely correlated with the corresponding mRNA level. In multivariate regression analysis, the methylation levels of sFRP-2 and Dkk-3 were significant independent predictors of bladder tumor (P < 0.05 and P < 0.01, respectively), whereas with sFRP-1, sFRP-5, and Wif-1 there was a trend towards significance as independent predictors. The M score of Wnt-antagonist genes was significantly higher in bladder tumor than in bladder mucosa (P < 0.05). Overall, the M score had a sensitivity of 77.2% and a specificity of 66.7% as a diagnostic biomarker (areas under the curve, 0.763). The M score could distinguish superficial from invasive bladder tumors with a sensitivity of 72.2% and a specificity of 61.1% as a staging biomarker (areas under the curve, 0.671). In patients with bladder tumor, 80.6% of the methylation-specific PCR results had identical methylation in samples of tumor- and urine-derived DNA. Most urine DNA in normal controls showed no aberrant methylation of the Wnt-antagonist genes.

CONCLUSIONS

Hypermethylation of Wnt-antagonist genes plays an important role in the pathogenesis of bladder tumor and can be detected using cellular DNA extracted from urine samples. This is the first report demonstrating that M score analysis of Wnt-antagonist genes could serve as an excellent epigenetic biomarker panel for bladder tumors.

Urinary connective tissue growth factor excretion correlates with clinical markers of renal disease in a large population of type 1 diabetic patients with diabetic nephropathy

OBJECTIVE

Levels of connective tissue growth factor (CTGF; CCN-2) in plasma are increased in various fibrotic disorders, including diabetic nephropathy. Recently, several articles have reported a strong increase of urinary CTGF excretion (U-CTGF) in patients with diabetic nephropathy. However, these studies addressed too small a number of patients to allow general conclusions to be drawn. Therefore, we evaluated U-CTGF in a large cross-sectional study of patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Subjects were 318 type 1 diabetic patients and 29 normoglycemic control subjects. U-CTGF was measured by sandwich enzyme-linked immunosorbent assay. Groups were compared by Kruskal-Wallis and Mann-Whitney analysis. The relation between U-CTGF and markers of diabetic nephropathy was determined by regression analysis.

RESULTS

U-CTGF in patients with diabetic nephropathy (n = 89, median 155 pmol/24 h [interquartile range 96-258]) was significantly higher than in microalbuminuric (n = 79, 100 [65-78]) and normoalbuminuric (n = 150, 85 [48-127]) patients and control subjects (n = 29, 100 [78-114]). U-CTGF correlated with urinary albumin excretion (UAE) (R = 0.31) and glomerular filtration rate (R = -0.38) in patients with diabetic nephropathy. A standardized increase in U-CTGF was associated with diabetic nephropathy (odds ratio 2.3 [95% CI 1.7-3.1]), which was comparable with the odds ratios for diabetic nephropathy of increased HbA(1c) (2.0 [1.5-2.7]), and blood pressure (2.0 [1.5-2.6]).

CONCLUSIONS

This is the first large cross-sectional study addressing U-CTGF in human type 1 diabetes. The observed association of U-CTGF with UAE and glomerular filtration rate might reflect a role of CTGF as progression promoter in diabetic nephropathy.

Reduction of urinary connective tissue growth factor by Losartan in type 1 patients with diabetic nephropathy

BACKGROUND

Connective tissue growth factor (CTGF) is an important profibrotic cytokine implicated in development of diabetic glomerulosclerosis. Urinary CTGF is reported to be significantly increased in patients with diabetic nephropathy. The present study aimed to investigate the short- and long term effects of angiotensin II receptor blockade by Losartan on urinary CTGF levels in hypertensive type 1 diabetic patients with diabetic nephropathy.

METHODS

Seventy-one hypertensive type 1 diabetic patients with diabetic nephropathy were included in the study. After a washout period of 4 weeks, the patients received Losartan 50 mg, 100 mg, and 150 mg once daily in treatment periods each lasting 2 months. Thereafter, patients were followed prospectively during treatment with Losartan 100 mg o.d. with a total mean follow-up time of 36 months. At baseline, after 2, 4, and 6 months and then biannually, urinary and plasma CTGF levels [enzyme linked immunosorbent assay (ELISA) fibroGen], albuminuria (Turbidimetry), glomerular filtration rate (GFR) [51-creatinine ethylenediaminetetraacetic acid ((51)Cr-EDTA plasma clearance)] and 24 hours blood pressure (TM2420)) were determined.

RESULTS

Baseline levels of urinary and plasma CTGF were 7076 (5708 to 8770) ng/24 hours [geometric mean (95% CI)] and 12.7 (7.3) ng/mL [mean (SD)], respectively. Albuminuria, GFR, and arterial blood pressure at baseline were 1152 (937 to 1416) mg/24 hours, 88 (24) mL/min/1.73 m(2), and 153/80 (17/9) mm Hg, respectively. Losartan significantly reduced urinary CTGF by 21% (9 to 31) (95% CI) initially (P < 0.05 vs. baseline), with no further reduction after increasing dose. The sustained reduction in urinary CTGF was 22% (12 to 32) (P < 0.05 vs. baseline). Rate of decline in GFR during the study was 3.2 (-1.6 to 15.9) mL/min/year [median (range)]. Reduction in urinary CTGF was correlated with a lower rate of decline in GFR (r= 0.23, P= 0.05). Plasma CTGF remained unchanged throughout the study.

CONCLUSION

Our 3-year study demonstrates that Losartan persistently reduces urinary CTGF excretion, which is associated with a slower rate of decline in GFR.

Prediction of Acute Renal Allograft Rejection by Urinary Monokine Induced by IFN-γ (MIG)

Early diagnosis of acute allograft rejection (AR) is still decisive for long-term renal allograft survival. The aim of this study was to define the role of the chemokine monokine induced by IFN-gamma (MIG) (CXCL9) and IFN-gamma-inducible protein 10 (IP-10) (CXCL10) as early markers of AR in renal transplantation (NTX). In a prospective study, 69 de novo renal transplant recipients were monitored and urine samples were collected after NTX for a median of 29 d. In pH-adjusted urine, MIG and IP-10 were determined by modified ELISA. AR was clinically diagnosed in 15 of 69 recipients and confirmed by biopsy in 14 of 15 AR patients (Banff classification). Corresponding to CXCR3-positive infiltrates in renal tissue, urinary MIG was elevated in 14 of 15 AR patients with a median of 2809 pg/ml (quartile 25% and 75% = 870 and 13,000; n = 15), being significantly (P < 0.0001) different from both nonrejecting allograft patients (NO-AR) (median, 25%, and 75%: 96, 1.0, and 161, n = 54) and healthy controls (median, 25%, and 75%: 144, 19, and 208, n = 13). Urinary MIG predicted AR with a sensitivity of 93% and a specificity of 89%. In AR and NO-AR groups, MIG values correlated well with IP-10 (P < 0.001). MIG values indicated both imminent rejection and response to successful antirejection therapy. MIG was not related to intercurrent infections or other causes for impairment of renal function. In a multivariate analysis, MIG correlated best (P < 0.001) with AR from all AR-associated parameters. In conclusion, urinary MIG serves as a very sensitive and specific predictor for AR, mirrors response to antirejection therapy, and thus may contribute to improved long-term renal allograft survival.

Enhanced urinary adiponectin excretion in IgA-nephropathy patients with proteinuria

Adiponectin is secreted specifically by adipose tissue. It was reported that the serum adiponectin level was markedly increased in patients with end-stage renal disease and was positively associated with abnormal renal function in type 2 diabetes. Recently, we found that urinary adiponectin level was significantly increased in type 2 diabetic patients with overt diabetic nephropathy, but not in those without nephropathy. The aim of the present study was to evaluate whether the urinary adiponectin level is increased not only in diabetic patients with macroalbuminuria but also in IgA-nephropathy patients with macroalbuminuria. We measured urinary adiponectin levels in 24 healthy control subjects, 12 IgA-nephropathy patients, and 19 type 2 diabetic nephropathy patients, and they were, in medians, 2.24 microg/g creatinine (ranges of 0.85 to approximately 3.70), 59.2 microg/g creatinine (4.95 to approximately 186), and 33.1 microg/g creatinine (4.69 to approximately 114), respectively. In the two patient groups, urinary adiponectin levels were significantly higher than in control subjects (P<0.01). Moreover, positive correlations between urinary adiponectin levels and albumin-to-creatinine ratios were observed in IgA-nephropathy (R2=0.53, P<0.01) and diabetic nephropathy patients (R2=0.61, P<0.01), but not in control subjects. Serum adiponectin levels were unchanged in these three groups. These findings suggested that the increase of urinary adiponectin levels partly results from enhanced filtration of circulating adiponectin through the changes of glomerular permselectivity and intraglomerular hydruric pressure. However, clinical implication of urinary adiponectin excretion in healthy control remains to be elucidated.

Biologic markers for the early detection of acute kidney injury

PURPOSE OF REVIEW

This review discusses the current status of several biomarkers as potential diagnostic tools in patients with acute kidney disease.

RECENT FINDINGS

Although the term "acute renal failure" has generally been used to describe acute kidney dysfunction that runs the spectrum from mild prerenal azotemia with no renal pathologic changes and no functional failure to severe oliguric renal dysfunction associated with tubular necrosis with failure of function, this spectrum is better described by the term "acute kidney injury." The mortality rate of hospitalized patients with severe acute kidney disease has not decreased significantly over the past 50 years despite advances in supportive care. The absence of sensitive and specific biomarkers for detecting injury early, grading the severity of the injury, and monitoring the response to therapy has impaired progress in the field and has had a very detrimental effect on the design and outcome of clinical trials in acute kidney disease. As a result of reliance on serum creatinine as a marker for injury and diagnosis, the institution of therapy is markedly delayed.

SUMMARY

The search for new biomarkers for acute kidney injury is evolving rapidly with advancement in modern technologies. With better biomarkers we will have the ability to detect injury earlier, identify subclinical injury, provide prognostic information on the course of renal impairment, identify the nephron segments most affected, provide a rationale for segmentation of patients for clinical studies, guide timing of therapy, assess response to therapy, and screen patients at risk for renal injury.

Elevation of CXCR3-binding chemokines in urine indicates acute renal-allograft dysfunction

A noninvasive urinary test that diagnoses acute renal allograft dysfunction would benefit renal transplant patients. We aimed to develop a rapid urinary diagnostic test by detecting chemokines. Seventy-three patients with renal allograft dysfunction prompting biopsy and 26 patients with stable graft function were recruited. Urinary levels of CXCR3-binding chemokines, monokine induced by IFN-gamma (Mig/CXCL9), IFN-gamma-induced protein of 10 kDa (IP-10/CXCL10), and IFN-inducible T-cell chemoattractant (I-TAC/CXCL11), were determined by a particle-based triplex assay. IP-10, Mig and I-TAC were significantly elevated in renal graft recipients with acute rejection, acute tubular injury and BK virus nephritis. Using 100 pg/mL as the threshold level, both IP-10 and Mig had diagnostic value (sensitivity 86.4%; specificity 91.3%) in differentiating acute graft dysfunction from other clinical conditions. In terms of monitoring the response to antirejection therapy, this urinary test is more sensitive and predictive than serum creatinine. These results indicate that this rapid test is clinically useful.

Urinary CCN2 (CTGF) as a possible predictor of diabetic nephropathy: preliminary report

BACKGROUND

It is currently impossible to reliably predict which diabetic patients will develop nephropathy and progress to kidney failure. Microalbuminuria, often regarded as a predictor of overt diabetic renal disease is, in fact, an indicator of established glomerular damage. We have shown that glomerular expression of the prosclerotic cytokine CCN2 (CTGF) is greatly up-regulated early in experimental and in human diabetes and mesangial cell exposure to CCN2 increases its production of extracellular matrix (ECM) molecules responsible for glomerulosclerosis. As an early marker, we therefore investigated the presence of CCN2 in urine and the relationship to diabetes and/or renal disease in an experimental model of diabetes and in a limited patient population.

METHODS

Urine samples from (1) healthy rats, (2) rats made diabetic by streptozotocin (STZ), (3) healthy human volunteers, (4) diabetic patients with renal disease, and (5) diabetic patients without renal disease were examined by Western blotting and/or enzyme-linked immunosorbent assay (ELISA) for qualitative and quantitative analysis of the of CCN2.

RESULTS

Low levels of urinary CCN2 were present in healthy, control rats, but were increased approximately sevenfold overall in STZ-diabetic animals. CCN2 levels were the highest at week 3 of diabetes, then decreased with time, but remained significantly elevated over controls even after 32 weeks. Consistently low levels of urinary CCN2 were also detected in healthy volunteers (mean value, 7.1 CCN2/mg creatinine). However, levels were elevated approximately sixfold in the majority of diabetic patients with nephropathy. A small number of the diabetic patients not yet exhibiting evidence of renal involvement demonstrated CCN2 urinary levels that were ninefold greater than controls. The remaining normoalbuminuric diabetic patients demonstrated CCN2 levels indistinguishable from those of healthy volunteers. Analysis by Western blotting confirmed the identity of the urinary CCN2. A molecular species equivalent to full-length CCN2 (37/39 kD doublet) was present in healthy controls. In contrast, the nephropathic group demonstrated multiple CCN2 bands.

CONCLUSION

These findings support our hypothesis that CCN2 is up-regulated early in the evolution of glomerulosclerosis, including that of diabetes. We contend that urinary CCN2 may both stage nephropathy and predict those patients who are destined for progressive glomerulosclerosis and end-stage renal disease (ESRD). Cross-sectional and prospective studies of larger, well-defined diabetic patients groups will be required to prove this hypothesis, and are ongoing.

Sequential changes in pancreatic markers in acute pancreatitis

BACKGROUND

Trypsinogen activation within acinar cells plays a crucial role in the pathogenesis of acute pancreatitis (AP). Our aim was to characterize temporal changes of trypsinogen-1, trypsinogen-2, complexes of trypsin-1-alpha1-antitrypsin (T1-AAT) and trypsin-2-alpha1-antitrypsin (T2-AAT), trypsinogen activation peptide (TAP) and pancreatic secretory trypsin inhibitor (PSTI) in patients with AP.

METHODS

The study comprised 64 consecutive patients with AP (19 with severe disease) and 32 controls. The concentrations of trypsinogen-1 and -2, PSTI, T1-AAT and T2-AAT were determined by time-resolved immunofluorometric assays (IFMA), and TAP was measured using a competitive enzyme immunoassay from serum and urine.

RESULTS

The concentrations of trypsinogen-1 and -2 in serum reflected similar patterns, but excretion of trypsinogen-1 into urine was markedly lower than that of trypsinogen-2, the concentration of which correlated strongly with disease severity. The concentrations of T1-AAT were no higher in severe AP than in mild AP, while T2-AAT concentrations were significantly higher in severe than in mild disease. PSTI increased over the course of several days, showing strong correlation with disease severity. The concentrations of plasma and urinary TAP decreased rapidly to undetectable levels. During the early phase of AP, TAP correlated with the disease severity in plasma and urine but there was no difference between controls and patients with mild AP.

CONCLUSION

More pronounced changes in trypsinogen-2 and its complex with AAT than in those of trypsinogen-1 were demonstrated, suggesting that trypsinogen-2 might play a more important role in the pathogenesis of AP than earlier believed. Urinary PSTI showed features warranting further investigations as a marker of disease severity.

Effects of the cyclooxygenase inhibitor, piroxicam, in combination with chemotherapy on tumor response, apoptosis, and angiogenesis in a canine model of human invasive urinary bladder cancer

The objectives of this study were: (a) to determine the antitumor activity and toxicity of a cyclooxygenase inhibitor (piroxicam) combined with cisplatin chemotherapy in dogs with naturally-occurring, invasive transitional cell carcinoma (TCC) of the urinary bladder; and (b) to determine the effects of this treatment on prostaglandin E(2) concentration, tumor cell proliferation and apoptosis, and angiogenesis. Pet dogs with naturally-occurring invasive TCC underwent complete tumor staging before and after 10 weeks of piroxicam/cisplatin treatment. Prostaglandin E(2) concentrations were determined by immunoassay in snap-frozen tumor tissues. Apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling assay), proliferation (proliferating cell nuclear antigen), and microvessel density were determined in formalin-fixed tissues. Urine basic fibroblast growth factor and vascular endothelial cell growth factor concentrations were determined by immunoassay. Partial remission (> or =50% reduction in tumor volume) was noted in 6 of 12 dogs treated with piroxicam/cisplatin. Renal toxicity was dose-limiting. Apoptotic index doubled with treatment in 11 of 12 dogs but was not associated with tumor response. Proliferative index decreased in five dogs, and tumor decreased in size in three of the five dogs. Change in urine basic fibroblast growth factor and vascular endothelial cell growth factor was associated with tumor response. microvessel density was not associated with tumor response. In conclusion, piroxicam/cisplatin had antitumor activity against canine TCC, a disease that closely mimics human invasive urinary bladder cancer. Strategies to prevent renal toxicity of this protocol are needed. Induction of tumor apoptosis and reduction in angiogenic factor concentrations were observed, but additional studies are needed to further define the mechanisms of the antitumor activity of piroxicam/cisplatin.

Clinical pharmacokinetics, pharmacodynamics and metabolism of the novel matrix metalloproteinase inhibitor ABT-518

PURPOSE

To investigate the pharmacokinetics, pharmacodynamics and metabolism of the novel matrix metalloproteinase (MMP) inhibitor ABT-518.

METHODS

Plasma and urine samples were obtained from six patients included in a phase I trial in which ABT-518 was given once daily via the oral route. Samples were analyzed by LC-MS/MS, ELISA and immunocapture assay. The pharmacokinetics of the parent compound and of detectable metabolites were calculated.

RESULTS

After a single dose of ABT-518 peak plasma levels were reached within 4-8 h. ABT-518 had an estimated clearance (Cl/F) of approximately 3 l/h, an estimated volume of distribution (V/F) of over 70 l and a terminal half-life (T(1/2)) of 20 h. At least six different metabolites were formed. Pharmacodynamic analysis for angiogenic growth factors (bFGF and VEGF) showed plasma and urine levels in the picogram range and for total MMP-9 and MMP-2 or MMP-9 activity showed plasma and urine levels in the nanogram range.

CONCLUSIONS

The MMP inhibitor ABT-518 is extensively metabolized in humans. No significant correlations between pharmacokinetics and pharmacodynamics could be established.

Early detection of cysteine rich protein 61 (CYR61, CCN1) in urine following renal ischemic reperfusion injury

BACKGROUND

Acute renal failure (ARF) has a high morbidity and mortality. Many therapies have worked in animals but were unsuccessful in clinical trials. The inability to diagnose ARF early may have impaired the success of these trials.

METHOD

We screened a subtraction library to search for potential disease markers that would be induced rapidly after renal injury. Mice and rats were subjected to 30 to 40 minutes of bilateral ischemia.

RESULTS

mRNA for Cyr61, a secreted growth factor-inducible immediate early gene, was markedly up-regulated at two hours in the kidney but not other organs following renal ischemia. In situ hybridization studies suggested Cyr61 was synthesized in the proximal straight tubule. Cyr61 protein was analyzed by capture with heparin beads followed by Western blotting. Induction of Cyr61 protein could be detected in the kidney within one hour, peaked at four to eight hours, and remained elevated for at least 24 hours following ischemia. Cyr61 protein was detected in urine at three to six hours and peaked at six to nine hours after renal injury. Cyr61 was not detected after volume depletion, which is often difficult to differentiate from ARF.

CONCLUSIONS

The secreted, cysteine-rich, heparin binding protein Cyr61 is rapidly induced in proximal straight tubules following renal ischemia, and excreted in the urine where it might serve as an early biomarker of renal injury.

Results of a Phase I dose-escalating study of the antiangiogenic agent, SU5416, in patients with advanced malignancies

SU5416 is a small molecule antiangiogenic agent that inhibits vascular endothelial growth factor (VEGF) stimulation of the KDR tyrosine kinase receptor. In this Phase I dose escalation trial, a weekly dose schedule of SU5416 was tested whereby an initial 5-day loading dose was followed by weekly maintenance infusions. The start dose was 20 mg/m(2) for the loading dose followed by 65 mg/m(2) for the weekly infusions. Dose escalations occurred at 33% until a final dose of 65 mg/m(2) (loading dose) and 190 mg/m(2) (weekly infusion) was obtained. Twenty-two patients were treated at five dose levels; tumor types included gastrointestinal (8), breast (3), lung (4), sarcoma (2), and other (5). The most common serious drug-related toxicity was headache, often associated with nausea and vomiting. Grade 1 and 2 toxicities included headache, nausea, vomiting, asthenia, pain at the infusion site, phlebitis, change in voice, and fevers. Of 19 evaluable patients, 4 obtained clinical benefit as defined by tumor regression (1) or disease stabilization for at least 12 weeks (3). Pharmacokinetic data revealed that the weekly infusion schedule prevented the reported 50-60% induction in SU5416 clearance observed with either daily or twice weekly dosing. Higher baseline levels of urine VEGF were observed in the 4 patients who gained clinical benefit, suggesting this may be a useful marker for predicting response to anti-VEGF therapies. Our results suggest that a weekly schedule of SU5416 shows signs of biological activity and is well tolerated at doses up to 145 mg/m(2).