The metabolites ofde novoNAD+ synthesis are a valuable predictor of acute kidney injury

Figures

• 

  Figure 1:. Characterization of major enzymes responsible for NAD+de novo synthesis in human kidney. (A) De novo biosynthetic pathway of NAD+. (B) Representative immunohistochemical staining of NAD+de novo biosynthetic enzymes in human renal tissue specimens (magnification as 40×). (C) Immunofluorescence co-staining and immunohistochemical staining of serial sections of NAD+de novo biosynthetic enzymes (red dot) with renal tubular markers (green arrow). (Immunohistochemical staining for KMO/THP and KYNU/THP with magnification as 200× and others with magnification as 400×.) (D) A dot plot of single-cell RNA sequencing of KMO, KYNU, HAAO, QPRT and ACMSD genes in human kidney.

• 

  Figure 2:. Signature of urinary NAD+de novo metabolites in AKI cohorts. (A) In the MTX cohort, significantly higher concentration of urinary N-formyl KYN and 3-OH AA and lower urinary QA and QA/3-OH AA were exhibited in the AKI group (n = 35) compared with the non-AKI group (n = 154). No difference in urinary TRP or KYN between two groups was observed. (B) In the liver transplantation cohort, post-operative AKI patients (n = 16) had higher urinary 3-OH AA and lower urinary QA/3-OH AA than non-AKI patients (n = 33). No difference in urinary TRP, N-formyl KYN, KYN or QA between two groups was observed. All urine samples were collected before chemotherapy or surgery. Boxes show interquartile range; the horizontal lines are medians and the whiskers are plotted using Tukey method.

• 

  Figure 3:. Predictive value of urinary QA/3-OH AA for AKI development. (A) Low quantile and high quantile are determined by the median of urinary QA/3-OH AA (5.51) in MTX cohort. In unadjusted model, the upper quantile of urinary QA/3-OH AA has 4.27 (95% confidence interval 1.67 to 10.69) odds for the development of AKI after HDMTX. After adjusting for age, sex and diabetes, the odds ratio is 3.25 (95% confidence interval 1.19 to 8.93). (B) ROC curves show the predictive performance for AKI after HDMTX. AUC for urinary QA/3-OH AA is 0.749(SEM 0.044). The clinical model is comprised of age, sex and diabetes and AUC for the clinical model is 0.672 (SEM 0.052). AUC for the combination of clinical model and urinary QA/3-OH AA is 0.772 (SEM 0.041). (C) ROC curves show the predictive performance for AKI after liver transplantation. AUC for urinary QA/3-OH AA is 0.729 (SEM 0.079).

• 

  Figure 4:. Urinary QA/3-OH AA and renal HAAO expression in AKI-susceptible subjects. (A) Diabetic patients (n = 16) had significantly lower urinary QA/3-OH AA than non-diabetic ones (n = 53). (B) Correlation analysis of urinary QA/-3-OH AA with age. The average urinary QA/3-OH AA of patients with multiple treatment courses in MTX cohort was used for analysis. (C) HAAO expression (log HAAO expression by microarray) in renal tubulointerstitial area of DKD patients compared with that of healthy controls (data from Nephroseq). (D) Representative immunohistochemical staining of HAAO in kidney biopsy from five patients diagnosed with DKD and five patients with minimal change disease (Control). Semi-quantification analysis suggested all slides from control groups had a staining intensity score more than 3 while 80% of slides from the DKD groups scored below 3.