Urine Periostin as a Biomarker of Renal Injury in Chronic Allograft Nephropathy

Background

Chronic allograft nephropathy (CAN) represents the main cause of renal allograft failure after transplantation. Noninvasive CAN testing is required. Periostin promotes the expression of a mesenchymal phenotype in renal tubules and is a promising urine biomarker for progressive renal injury. Information regarding periostin expression in the setting of CAN remains scarce.

Methods

Subjects were recruited from our outpatient transplantation clinic. Random urine samples were collected from CAN patients (n = 24) and renal transplant patients with normal renal function (transplant controls, n = 18). Control samples were collected from healthy volunteers (n = 18) who had normal renal function. Urine periostin was measured by enzyme-linked immunosorbent assay.

Results

The median urine periostin in CAN patients was significantly higher than in transplant and healthy controls (1.74 vs 0.00 vs 0.14 ng/mg creatinine, respectively; P < .001). Urine periostin enzyme-linked immunosorbent assay at a cutoff value of 0.152 ng/mg creatinine demonstrated the sensitivity, specificity, and accuracy for distinguishing CAN patients from transplant patients with normal renal function (91.7%, 77.8%, and 85.7%, respectively). In addition, urine periostin levels correlated directly with urine protein creatinine ratio (R = 0.566, P < .001) and serum creatinine (R = 0.522; P < .001), whereas inverse significant correlations were evidenced with estimated glomerular filtration rate (R = −0.431; P < .001).

Conclusion

The appearance of urine periostin in CAN patients but not in healthy and transplant controls underscores its value as a potential biomarker for chronic progressive renal injury in transplant recipients.     

Factor V Leiden and prothrombin G20210A mutations in Thai patients awaiting kidney transplant

Renal transplantation provides the best long-term treatment for chronic renal failure, but thrombosis of the transplanted renal artery or renal vein is one of the causes of kidney failure in the early postoperative period. Factor V Leiden (FVL) and prothrombin G20210A mutation are the most frequent genetic abnormalities associated with venous thrombosis. We investigated the prevalence of FVL and prothrombin G20210A by polymerase chain reaction with restriction fragment length polymorphism in 75 Thai patients awaiting renal transplant, and a control group of 106 healthy blood donors. Of those awaiting renal transplant, none was found to carry FVL or prothrombin G20210A mutations. Neither the heterozygous nor the homozygous FVL mutation nor the prothrombin G20210A mutation was detected in the 106 healthy volunteers. Although we failed to detect FVL and prothrombin G20210A mutation among those waiting for a kidney transplant, the population size was small. Further studies need to be performed in order to ascertain if these coagulation mutations are of relevance in predicting patients at risk of early transplant failure.     

Metabolic syndrome and its relation to chronic kidney disease in a Southeast Asian population

The metabolic syndrome has been documented to increase the risk of cardiovascular disease and chronic kidney disease (CKD); however, there are few studies of this in developing countries. A total of 15,357 participants of a standardized check-up, included metabolic screening, were enrolled. Metabolic syndrome was defined using criteria modified from the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) and the International Diabetes Federation (IDF). CKD was defined as a glomerular filtration rate <60 m/min per 1.73 m2. Eighty point four percent of participants were men and 2,228 (14.5%) had CKD. Metabolic syndrome was more prevalent among CKD subjects than non-CKD subjects (modified NCEP-ATP III, 30.1% vs 24.4%; p < 0.001; modified IDF 26.9% vs 23.1%; p < 0.001, respectively). Abdominal obesity, high triglycerides, high blood pressure and impaired fasting glucose were significantly associated with an increased prevalence of CKD. There was also a significant graded relationship between the number of metabolic syndrome components and the prevalence of CKD. Participants with metabolic syndrome according to the modified NCEP-ATP III and modified IDF criteria had a 1.34-fold increase in adjusted odds ratio (95% CI 1.21-1.49) and a 1.20-fold increase in adjusted odds ratio (95% CI 1.08-1.33), respectively, compared to those without metabolic syndrome. Our study demonstrated metabolic syndrome defined with modified NCEP-ATP III and modified IDF criteria was significantly associated with increased prevalence of CKD in a Southeast Asian population.