As a leading cause of chronic kidney disease, clinical demand for noninvasive biomarkers of diabetic kidney disease (DKD) beyond proteinuria is increasing. Metabolomics is a popular method to identify mechanisms and biomarkers. We investigated urinary targeted metabolomics in DKD patients. Methods: We conducted a targeted metabolomics study of 26 urinary metabolites in consecutive patients with DKD stage 1 to 5 (n = 208) and healthy controls (n = 26). The relationships between estimated glomerular filtration rate (eGFR) or urine protein-creatinine ratio (UPCR) and metabolites were evaluated. Multivariate Cox analysis was used to estimate relationships between urinary metabolites and the target outcome, end-stage renal disease (ESRD). C statistics and time-dependent receiver operating characteristics (ROC) were used to assess diagnostic validity. Results: During a median 4.5 years of follow-up, 103 patients (44.0%) progressed to ESRD and 65 (27.8%) died. The median fold changes of nine metabolites belonged to monosaccharide and tricarboxylic acid (TCA) cycle metabolites tended to increase with DKD stage. Myo-inositol, choline, and citrates were correlated with eGFR and choline, while mannose and myo-inositol were correlated with UPCR. Elevated urinary monosaccharide and TCA cycle metabolites showed associations with increased morality and ESRD progression. The predictive power of ESRD progression was high, in the order of choline, myo-inositol, and citrate. Although urinary metabolites alone were less predictive than serum creatinine or UPCR, myo-inositol had additive effect with serum creatinine and UPCR. In time-dependent ROC, myo-inositol was more predictive than UPCR of 1-year ESRD progression prediction. Conclusion: Myo-inositol can be used as an additive biomarker of ESRD progression in DKD.

BACKGROUND: The association of de novo donor-specific anti-human leukocyte antigens (HLA) antibodies (DSA) and development of antibody-mediated rejection (AMR) in kidney transplant recipients (KTRs) is still undetermined. METHODS: We prospectively screened de novo DSA in 167 KTRs during 32 months after kidney transplantation (KT). Timing of DSA detection was at 3, 6, and 12 months post-transplant and annually thereafter and when clinically indicated. DSA levels were determined by Luminex assays and expressed as mean fluorescence intensity (MFI). We evaluated the incidence, characteristics of DSA, and association between DSA and tacrolimus trough levels or AMR. RESULTS: De novo DSA developed in 16 KTRs (9.6%) and acute AMR occurred more commonly in KTRs with de novo DSA compared to KTRs without de novo DSA (18.8% vs. 0%, P < 0.001). All de novo DSA were against class II antigens. The mean number of DSA was 1.8 ± 1.2 and the average MFI of DSA was 7,399 ± 5,470. Tacrolimus trough level during the first 0–2 months after KT was an independent predictor of DSA development (hazard ratio, 0.70; 95% confidence interval, 0.50–0.99; P = 0.043). No differences were found in the number of DSA, average MFI of DSA, and tacrolimus levels during the first year between de novo DSA-positive KTRs with AMR and those without AMR. CONCLUSION: The results of our study suggest that monitoring of DSA and maintaining proper tacrolimus levels are essential to prevent AMR during the initial period after KT.
Antibodies* ; Fluorescence ; Graft Rejection ; Histocompatibility Antigens Class II ; HLA Antigens ; Incidence ; Kidney Transplantation* ; Kidney* ; Prospective Studies ; Tacrolimus ; Transplant Recipients

A 38-year-old man, who underwent a second kidney transplantation (KT), was admitted because of antibody-mediated rejection (AMR) complicated by BK virus-associated nephropathy (BKVAN). He was placed on hemodialysis at the age of 24 years because of membranoproliferative glomerulonephritis. At the age of 28 years, he underwent a living donor KT from his father; however, 1 year after the transplantation, he developed a recurrence of the primary glomerular disease, resulting in graft failure 2 years after the first KT. Ten years later, he received a deceased-donor kidney with a B-cell-positive-cross-match. He received 600 mg of rituximab before the KT with three cycles of plasmapheresis and immunoglobulin (0.5 g/kg) therapy after KT. During the follow-up, the first and second allograft biopsies at 4 and 10 months after KT revealed AMR with a recurrence of primary glomerular disease that was reclassified as C3 glomerulonephritis (C3GN). He received a steroid pulse, rituximab, plasmapheresis, and immunoglobulin therapies. The third allograft biopsy demonstrated that the BKVAN was complicated with AMR and C3GN. As the azotemia did not improve after repeated conventional therapies for AMR, one cycle of bortezomib (1.3 mg/m²×4 doses) was administered. The allograft function stabilized, and BK viremia became undetectable after 6 months. The present case suggests that bortezomib therapy may be applicable to patients with refractory AMR, even in cases complicated with BKVAN.
Adult ; Allografts ; Azotemia ; Biopsy ; BK Virus ; Bortezomib* ; Fathers ; Follow-Up Studies ; Glomerulonephritis* ; Glomerulonephritis, Membranoproliferative ; Graft Rejection ; Humans ; Immunization, Passive ; Immunoglobulins ; Kidney ; Kidney Transplantation ; Living Donors ; Plasmapheresis ; Recurrence ; Renal Dialysis ; Rituximab ; Transplants ; Viremia