High-dose HOOK effect in urinary DcR2 assay in patients with chronic kidney disease.

BACKGROUND: Urinary DcR2 (uDcR2) is a biomarker for the early detection the tubulointerstitial injury (TII) in patients with chronic kidney disease (CKD), but the high-dose hook effect may lead to falsely low or even negative results when using an enzyme-linked immunosorbent assay (ELISA). This study aimed to investigate if the high-dose hook effect exists with ELISA testing, and to uncover a potential approach for reducing this effect. METHODS: 72 CKD patients were recruited and categorized into four groups based on TII scores. uDcR2 was measured in undiluted and serially diluted (two-, four-, eight- and 16-fold dilutions) urine using an ELISA kit. The results from the assay were normalized to urinary creatinine. We evaluated the correlation between uDcR2/cre levels at different dilutions and renal histological parameters. Receiver operating characteristic (ROC) curves were generated to examine the value of uDcR2/cre for predicting TII. RESULTS: uDcR2/cre levels in the undiluted urine were significantly higher in patients with CKD than those in the control. However, higher TII scores did not yield higher levels of uDcR2/cre in the undiluted urine. After serial dilution, uDcR2/cre levels were highest with the four-fold dilution. A positive correlation was found between uDcR2/cre levels at different dilutions and TII scores, with the highest correlation coefficient and the largest AUC being observed at the four-fold dilution. CONCLUSIONS: The high-dose hook effect was apparent during ELISA testing of uDcR2 in CKD patients, yet dilution of the urine samples neutralized this effect. However, the use of a four-fold dilution of urine for uDcR2/cre testing may eliminate the high-dose hook effect and make it possible to effectively monitor the severity of TII in CKD patients.

Urinary DcR2 is a novel biomarker for tubulointerstitial injury in patients with diabetic nephropathy.

Tubulointerstitial injury (TII) plays a crucial role in the progression of diabetic nephropathy (DN), but lack of specific and sensitive biomarkers for monitoring TII in DN management. This study is to investigate whether urinary decoy receptor 2 (uDcR2) could serve as a novel noninvasive biomarker for assessing TII in DN. We recruited 311 type 2 diabetics and 139 DN patients who were diagnosed by renal biopsy. uDcR2 levels were measured by ELISA, and renal DcR2 expression was detected immunohistochemically. Associations between uDcR2 and renal DcR2 and renal functional parameters were evaluated. Receiver operating characteristics (ROC) curve analyzed area under the curve (AUC) of uDcR2 for assessing TII. Double staining was undertaken for renal DcR2 with proximal and distal tubular markers; senescent markers p16, p21, and senescence-associated ß-galactosidase (SA-ß-gal); and fibrotic markers collagen I and IV. We found DcR2 was primarily expressed in renal proximal tubules; uDcR2 levels were elevated per albuminuria stratum and correlated with renal functional parameters in diabetics and were associated with percentage of tubular DcR2 and TII score in DN. The uDcR2 had an AUC of 0.909 for assessing TII in DN by ROC analysis. Almost all tubular DcR2 was coexpressed with p16 and p21, and nearly more than one-half of tubular DcR2 was positive for SA-ß-gal, primarily in collagen I- and IV-positive regions of DN. Our results indicate uDcR2 could potentially serve as a novel biomarker for TII and may reflect senescence of renal proximal tubular cells in DN pathogenesis.

Modulation of gut barrier function in patients with obstructive jaundice using probiotic LP299v.

OBJECTIVES: This study aimed to determine the effect of LP229v on intestinal permeability and tumour necrosis factor (TNF) p55 receptor concentrations in patients with obstructive jaundice undergoing biliary drainage. PATIENTS AND METHODS: Patients undergoing biliary drainage were recruited and randomized into three groups to receive Lactobacillus plantarum 299v (LP299v), inactivated LP299v (placebo) or water. These were administered daily at noon until 7 days after biliary drainage. Intestinal permeability was measured using the lactulose/mannitol (L/M) dual sugar absorption test on admission, the day before biliary drainage and on days 1 and 7 after biliary drainage. Blood and urine were collected to determine the L/M ratio and the TNF p55 receptor levels at each time point. RESULTS: A total of 25 patients were recruited; 12 had choledocholithiasis and nine had a periampullary tumour. Open surgical biliary drainage was performed in nine patients, endoscopic retrograde cholangiopancreatography in 12 and percutaneous transhepatic cholangiography in two. Five patients received LP299v, five received placebo and seven, water. The median L/M ratio was 0.035 (0.018-0.065) at baseline. No difference existed between the groups on admission, before drainage and on day 7 after drainage (P=0.59, 0.175 and 0.61, respectively). The L/M ratio was lower in the LP299v group on day 1 after drainage [0.01 (0.01) vs. 0.18 (0.03-0.3) and 0.11 (0.07-0.14); P=0.37]. Although the TNF p55 receptor levels were lower on day 1 after drainage in the LP299v group (15.3 vs. 30.9 vs. 82.7 ng/ml; P=0.43), the concentration at the four time points was similar (P=0.24, 0.96, 0.43 and 0.68). CONCLUSION: Pretreatment with probiotic LP299v improves intestinal permeability after biliary drainage and attenuates the inflammatory response. However, a larger multicentre trial is required to determine the effect on clinical outcome.

TNF receptor p55 and IL-8(72) and IL-8(77) isoforms: blood and urine levels in breast cancer patients.

In the preliminary study reported here, 37 patients with breast cancer and 10 healthy volunteers were analyzed for soluble TNF-R p55 and two variants of IL-8 consisting of 72 and 77 amino acid residues (IL-8(72) and IL-8(77), respectively) in their blood and urine with novel ELISA test systems. The clinical/prognostic values of determining these inflammatory cytokines at different stages of the cancer process appeared to depend on the treatment course being evaluated. In contrast to expectations, it was noted that there was a stabile tendency for decreased TNF-R p55 and IL-8(72) levels in the plasma and urine of breast cancer patients as compared with levels observed with healthy controls. Moreover, patients that underwent polychemotherapy treatments were notable for significant decreases in IL-8(72) and TNF-R p55 levels in their blood plasma; these findings contrasted with significant increases in these parameters in these patients' urine. Interestingly, the IL-8(77) isoform that now appeared both in the urine and plasma of patients was not detectable before initiation of the polychemotherapy. In spite of all these findings, individual fluctuations among these parameters still do not allow us to establish, at this time, any strong correlations between these values with any particular breast cancer stage or a type of treatment. Nonetheless, while the results here are preliminary, they demonstrate that testing for TNF-R, along with IL-8 isoforms, in the blood plasma and urine could potentially present a valid means for monitoring of the overall immune and disease progress/remission status in breast cancer patients. Ongoing studies with larger patient sample sizes, as well as collecting and analyzing samples at multiple time points--to minimize the potential influence of any inherent variability in cytokine levels in humans--will hopefully allow us to specify what these preliminary results reported here suggest, i.e., the potential utility of this experimental approach for determining disease progression or efficacy of treatment in cancer patients.