Increased intracellular adenosine triphosphate level as an index to predict acute rejection in kidney transplant recipients

Non-Invasive Diagnosis for Acute Rejection Using Urinary mRNA Signature Reflecting Allograft Status in Kidney Transplantation

Urine has been regarded as a good resource based on the assumption that urine can directly reflect the state of the allograft or ongoing injury in kidney transplantation. Previous studies, suggesting the usefulness of urinary mRNA as a biomarker of acute rejection, imply that urinary mRNA mirrors the transcriptional activity of the kidneys. We selected 14 data-driven candidate genes through a meta-analysis and measured the candidate genes using quantitative PCR without pre-amplification in the cross-sectional specimens from Korean kidney transplant patients. Expression of 9/14 genes (CXCL9, CD3ϵ, IP-10, LCK, C1QB, PSMB9, Tim-3, Foxp3, and FAM26F) was significantly different between acute rejection and stable graft function with normal pathology and long-term graft survival in 103 training samples. CXCL9 was also distinctly expressed in allografts with acute rejection in in situ hybridization analysis. This result, consistent with the qPCR result, implies that urinary mRNA could reflect the magnitude of allograft injury. We developed an AR prediction model with the urinary mRNAs by a binary logistic regression and the AUC of the model was 0.89 in the training set. The model was validated in 391 independent samples, and the AUC value yielded 0.84 with a fixed manner. In addition, the decision curve analysis indicated a range of reasonable threshold probabilities for biopsy. Therefore, we suggest the urine mRNA signature could be used as a non-invasive monitoring tool of acute rejection for clinical application and could help determine whether to perform a biopsy in a recipient with increased creatinine.

Monitoring cellular immune function of renal transplant recipients based on adenosine triphosphate (ATP) production by mitogen-induced CD4+ T helper cells

Maintaining the balance between over- and under-immunosuppression has a critical role for successful immunosuppressive therapy after renal transplantation. We studied the predictive value of our functional immune assay, which works based on adenosine triphosphate (ATP) levels, in determining risk of infection and rejection among renal transplant recipients (RTRs). A total of 65 RTRs with less than 1 month (RTRL1) and 48 RTRs with more than 6 months (RTRM6) of post-transplant time, and 56 healthy individuals were included. Upon lymphocyte activation by phytohemagglutinin (PHA), CD4+ T cells were separated using magnetic beads (Dynabeads), the intracellular ATP (iATP) concentrations were measured by luciferin-luciferase reaction, and compared within and between the groups. Activated CD4+ cells iATP production directly correlated with post-transplant time (r = 0.32, P = 0.011). The iATP levels were significantly lower in both RTRL1 and RTRM6 groups compared to control (P < 0.001), and in the RTRL1 group compared to the RTRM6 (P < 0.05). The iATP concentrations were significantly lower in patients who suffered from infection versus the RTRs with stable graft function (SGF). However, the iATP levels were higher in those with allograft rejection episode (ARE). Our optimization experiments showed that best iATP levels cutoffs were 472.5 and 572.5 ng/ml for predicting risk of ARE, and 218.5 and 300.5 ng/ml for predicting risk of developing infection in RTRL1 and RTRM6 patients, respectively. iATP levels measured by immune function assay might be a promising predictive tool for identifying RTRs who are at risk of developing infection or allograft rejection.

CD4+ lymphocyte adenosine triphosphate--a new marker in sepsis with acute kidney injury?

BACKGROUND

AKI frequently develops in sepsis patients, significantly decreasing the overall prognosis. There are currently no diagnostic markers available which reliably predict the prognosis of sepsis-associated AKI. Recently, ATP content of CD4+ T cells (ATP_CD4) has been shown to correlate with survival in sepsis. The aim of the study was to determine ATP_CD4 in sepsis-associated AKI.

METHODS

Thirty-three patients with sepsis were prospectively analyzed for ATP_CD4 at three different time points. Results were related to survival, renal recovery, and further clinical/laboratory findings.

RESULTS

ATP_CD4 tended to lower in concentration at 48 h after onset of sepsis in those patients with complete renal recovery. There were no differences between patients with no AKI and those with AKI of different severity (AKIN 1-3). Urinary NGAL did not correlate with renal prognosis.

CONCLUSION

ATP_CD4 may serve as risk predictor in sepsis-associated AKI. Lower concentrations may indicate a higher chance of complete renal recovery in sepsis.