Lise Morin

Urinary C-X-C Motif Chemokine 10 Independently Improves the Noninvasive Diagnosis of Antibody–Mediated Kidney Allograft Rejection

Urinary levels of C-X-C motif chemokine 9 (CXCL9) and CXCL10 can noninvasively diagnose T cell-mediated rejection (TCMR) of renal allografts. However, performance of these molecules as diagnostic/prognostic markers of antibody-mediated rejection (ABMR) is unknown. We investigated urinary CXCL9 and CXCL10 levels in a highly sensitized cohort of 244 renal allograft recipients (67 with preformed donor-specific antibodies [DSAs]) with 281 indication biopsy samples. We assessed the benefit of adding these biomarkers to conventional models for diagnosing/prognosing ABMR. Urinary CXCL9 and CXCL10 levels, normalized to urine creatinine (Cr) levels (CXCL9:Cr and CXCL10:Cr) or not, correlated with the extent of tubulointerstitial (i+t score; all P<0.001) and microvascular (g+ptc score; all P<0.001) inflammation. CXCL10:Cr diagnosed TCMR (area under the curve [AUC]=0.80; 95% confidence interval [95% CI], 0.68 to 0.92; P<0.001) and ABMR (AUC=0.76; 95% CI, 0.69 to 0.82; P<0.001) with high accuracy, even in the absence of tubulointerstitial inflammation (AUC=0.70; 95% CI, 0.61 to 0.79; P<0.001). Although mean fluorescence intensity of the immunodominant DSA diagnosed ABMR (AUC=0.75; 95% CI, 0.68 to 0.82; P<0.001), combining urinary CXCL10:Cr with immunodominant DSA levels improved the diagnosis of ABMR (AUC=0.83; 95% CI, 0.77 to 0.89; P<0.001). At the time of ABMR, urinary CXCL10:Cr ratio was independently associated with an increased risk of graft loss. In conclusion, urinary CXCL10:Cr ratio associates with tubulointerstitial and microvascular inflammation of the renal allograft. Combining the urinary CXCL10:Cr ratio with DSA monitoring significantly improves the noninvasive diagnosis of ABMR and the stratification of patients at high risk for graft loss.

Early Low Urinary CXCL9 and CXCL10 Might Predict Immunological Quiescence in Clinically and Histologically Stable Kidney Recipients.

We monitored the urinary C‐X‐C motif chemokine (CXCL)9 and CXCL10 levels in 1722 urine samples from 300 consecutive kidney recipients collected during the first posttransplantation year and assessed their predictive value for subsequent acute rejection (AR). The trajectories of urinary CXCL10 showed an early increase at 1 month (p = 0.0005) and 3 months (p = 0.0009) in patients who subsequently developed AR. At 1 year, the AR‐free allograft survival rates were 90% and 54% in patients with CXCL10:creatinine (CXCL10:Cr) levels <2.79 ng/mmoL and >2.79 ng/mmoL at 1 month, respectively (p < 0.0001), and 88% and 56% in patients with CXCL10:Cr levels <5.32 ng/mmoL and >5.32 ng/mmoL at 3 months (p < 0.0001), respectively. CXCL9:Cr levels also associate, albeit less robustly, with AR‐free allograft survival. Early CXCL10:Cr levels predicted clinical and subclinical rejection and both T cell– and antibody‐mediated rejection. In 222 stable patients, CXCL10:Cr at 3 months predicted AR independent of concomitant protocol biopsy results (p = 0.009). Although its positive predictive value was low, a high negative predictive value suggests that early CXCL10:Cr might predict immunological quiescence on a triple‐drug calcineurin inhibitor–based immunosuppressive regimen in the first posttransplantation year, even in clinically and histologically stable patients. The clinical utility of this test will need to be addressed by dedicated prospective clinical trials.

Urinary mRNA for the Diagnosis of Renal Allograft Rejection: The Issue of Normalization

Urinary messenger RNA (mRNA) quantification is a promising method for noninvasive diagnosis of renal allograft rejection (AR), but the quantification of mRNAs in urine remains challenging due to degradation. RNA normalization may be warranted to overcome these issues, but the strategies of gene normalization have been poorly evaluated. Herein, we address this issue in a case‐control study of 108 urine samples collected at time of allograft biopsy in kidney recipients with (n = 52) or without (n = 56) AR by comparing the diagnostic value of IP‐10 and CD3ε mRNAs—two biomarkers of AR—after normalization by the total amount of RNA, normalization by one of the three widely used reference RNAs—18S, glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) and Hypoxanthine‐guanine phosphoribosyltransferase (HPRT)—or normalization using uroplakin 1A (UPK) mRNA as a possible urine‐specific reference mRNA. Our results show that normalization based on the total quantity of RNA is not substantially improved by additional normalization and may even be worsened with some classical reference genes that are overexpressed during rejection. However, considering that normalization by a reference gene is necessary to ensure polymerase chain reaction (PCR) quality and reproducibility and to suppress the effect of RNA degradation, we suggest that GAPDH and UPK1A are preferable to 18S or HPRT RNA.

Reduction in late onset cytomegalovirus primary disease after discontinuation of antiviral prophylaxis in kidney transplant recipients treated with de novo everolimus

Donor (D)+/recipient (R)− serostatus is closely associated with a higher risk of cytomegalovirus (CMV) infection and disease. Antiviral prophylaxis is conventionally used in such patients, but late onset CMV infection/disease still occurs after the discontinuation of prophylaxis.

A Comparative Study of the Predictive Values of Urinary Acute Kidney Injury Markers Angiogenin and Kidney Injury Molecule 1 for the Outcomes of Kidney Allografts

Background Whether injury-related molecules in urines of individuals with ischemia-reperfusion injury (IRI) are independent predictors of graft outcomes and provide additional information compared with usual risk factors remains to be established. Methods We explored a cohort of 244 kidney transplant recipients who systematically had a urine collection 10 days after transplantation. The injury-related markers kidney injury molecule-1 (KIM-1) and angiogenin (ANG) levels in urines were measured. We determined the prognostic values of these markers on graft outcomes. Results Urinary KIM-1 and ANG concentrations were strongly correlated to each other and were significantly and independently associated with cold ischemia time, delayed graft function, and plasma creatinine 10 days after transplantation, indicating that these markers reflect the severity of IRI. However, urinary ANG and KIM-1 were not predictive of histological changes on protocol biopsies performed 3 and 12 months after transplantation. Finally, urinary ANG and urinary KIM-1 were not associated with graft survival. Conclusions Together, our results indicate that, in a cohort of 244 kidney transplant recipients, urinary ANG and KIM-1 levels in a single measurement 10 days after transplantation reflect the severity of IRI after kidney transplantation, but are neither independent predictors of renal function, histological changes and graft survival.