Significance Statement: Reliable prediction tools are needed to personalize treatment in ANCA-associated GN. More than 1500 patients were collated in an international longitudinal study to revise the ANCA kidney risk score. The score showed satisfactory performance, mimicking the original study (Harrell's C=0.779). In the development cohort of 959 patients, no additional parameters aiding the tool were detected, but replacing the GFR with creatinine identified an additional cutoff. The parameter interstitial fibrosis and tubular atrophy was modified to allow wider access, risk points were reweighted, and a fourth risk group was created, improving predictive ability (C=0.831). In the validation, the new model performed similarly well with excellent calibration and discrimination (n=480, C=0.821). The revised score optimizes prognostication for clinical practice and trials. Background: Reliable prediction tools are needed to personalize treatment in ANCA-associated GN. A retrospective international longitudinal cohort was collated to revise the ANCA renal risk score. Methods: The primary end point was ESKD with patients censored at last follow-up. Cox proportional hazards were used to reweight risk factors. Kaplan–Meier curves, Harrell's C statistic, receiver operating characteristics, and calibration plots were used to assess model performance. Results: Of 1591 patients, 1439 were included in the final analyses, 2:1 randomly allocated per center to development and validation cohorts (52% male, median age 64 years). In the development cohort (n=959), the ANCA renal risk score was validated and calibrated, and parameters were reinvestigated modifying interstitial fibrosis and tubular atrophy allowing semiquantitative reporting. An additional cutoff for kidney function (K) was identified, and serum creatinine replaced GFR (K0: 450 µmol/L=11 points). The risk points for the percentage of normal glomeruli (N) and interstitial fibrosis and tubular atrophy (T) were reweighted (N0: >25%=0, N1: 10%–25%=4, N2: <10%=7, T0: none/mild or <25%=0, T1: ≥ mild-moderate or ≥25%=3 points), and four risk groups created: low (0–4 points), moderate (5–11), high (12–18), and very high (21). Discrimination was C=0.831, and the 3-year kidney survival was 96%, 79%, 54%, and 19%, respectively. The revised score performed similarly well in the validation cohort with excellent calibration and discrimination (n=480, C=0.821). Conclusions: The updated score optimizes clinicopathologic prognostication for clinical practice and trials.

Recent studies have demonstrated the key role of the complement alternative pathway (cAP) in the pathophysiology of experimental ANCA-associated vasculitis (AAV). However, in human AAV the role of cAP has not been extensively explored. In the present work, we analysed circulating serum C3 levels measured at AAV onset and their relation to outcomes. We conducted a retrospective observational cohort study including 45 consecutive patients with AAV diagnosed between 2000 and 2014 with serum C3 measurement at diagnosis, before immunosuppressive treatment initiation. Two groups were defined according to the median serum C3 level value: the low C3 group (C3<120 mg/dL) and the high C3 level group (C3≥120 mg/dL). Patient and renal survivals, association between C3 level and renal pathology were analysed. Serum complement C3 concentration remained in the normal range [78–184 mg/dL]. Compared with the high C3 level, the patients in the low C3 level group had lower complement C4 concentrations (P = 0.008) and lower eGFR (P = 0.002) at diagnosis. The low C3 level group had poorer patient and death-censored renal survivals, compared with the high C3 level group (P = 0.047 and P = 0.001, respectively). We observed a significant negative correlation between C3 levels and the percentage of glomeruli affected by cellular crescent (P = 0.017, r = -0.407). According to the Berden et al renal histologic classification, patients in the crescentic/mixed category had low C3 levels more frequently (P<0.01). Interestingly, we observed that when patients with the crescentic/mixed histologic form were analysed according to C3 level, long term renal survival was significantly greater in the high C3 level group than in the low C3 level group (100% vs 40.7% at 6 years, p = 0.046). No relationship between serum C4 and renal outcome was observed. A Low C3 serum level in AAV patients at diagnosis is associated with worse long-term patient and renal survival.

Kidney injury molecule 1 (KIM-1) is a transmembrane glycoprotein expressed by proximal tubular cells, recognized as an early, sensitive and specific urinary biomarker for kidney injury. Blood KIM-1 was recently associated with the severity of acute and chronic kidney damage but its value in antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis with glomerulonephritis (ANCA-GN) has not been studied. Thus, we analyzed its expression at ANCA-GN diagnosis and its relationship with clinical presentation, kidney histopathology and early outcomes. We assessed KIM-1 levels and other pro-inflammatory molecules (C-reactive protein, interleukin-6, tumor necrosis factor α, monocyte chemoattractant protein-1 and pentraxin 3) at ANCA-GN diagnosis and after 6 months in patients included in the Maine-Anjou registry, which gathers data patients from four French Nephrology Centers diagnosed since January 2000. Blood KIM-1 levels were assessed in 54 patients. Levels were elevated at diagnosis and decreased after induction remission therapy. KIM-1 was associated with the severity of renal injury at diagnosis and the need for kidney replacement therapy. In opposition to other pro-inflammatory molecules, KIM-1 correlated with the amount of acute tubular necrosis and interstitial fibrosis/tubular atrophy (IF/TA) on kidney biopsy, but not with interstitial infiltrate or with glomerular involvement. In multivariable analysis, elevated KIM-1 predicted initial estimated glomerular filtration rate (β = –19, 95% CI –31, –7.6, P = .002). KIM-1 appears as a potential biomarker for acute kidney injury and for tubulointerstitial injury in ANCA-GN. Whether KIM-1 is only a surrogate marker or is a key immune player in ANCA-GN pathogenesis remain to be determined.

Background: Amoxicillin (AMX)-induced crystal nephropathy (AICN) is considered as a rare complication of high dose intravenous (IV) AMX administration. However, recently, its incidence seems to be increasing based on French pharmacovigilance centers. Occurrence of AICN has been observed mainly with IV administration of AMX and mostly under doses over 8 g/day. Given that pharmacovigilance data are based on declaration, the real incidence of AICN may be underestimated. Thus, the primary objective of the present study was to determine the incidence of AICN in the current practice. Materials and Methods: We conducted a retrospective study between 1 January 2015 and 31 December 2017 in Angers University Hospital. Inclusion criteria were age over 18 years-old and IV AMX administration of at least 8 g/day for more than 24 h. Patients admitted directly into the intensive care units were excluded. Medical records of patients that developed Kidney Disease:Improving Global Outcome (KDIGO) stage 2–3 acute kidney injury (AKI) were reviewed by a nephrologist and a specialist in pharmacovigilance. AICN was retained if temporality analysis was conclusive, after exclusion of other causes of AKI, in absence of other nephrotoxic drug administration. Results: A total of 1303 patients received IV AMX for at least 24 h. Among them, 358 (27.5%) were exposed to AMX doses of at least 8 g/day and were included. Patients were predominantly males (68.2%) with a mean age of 69.1 years-old. AMX was administered for a medical reason in 78.5% of cases. Patients received a median dose of AMX of 12 g/day (152.0 mg/kg/day). Seventy-three patients (20.4%) developed AKI, 42 (56.8%) of which were KDIGO stage 2 or 3. Among the latter, AICN diagnosis was retained in 16 (38.1%) patients, representing an incidence of 4.47% of total patients exposed to high IV AMX doses. Only female gender was associated with an increased risk of AICN. AMX dose was not significantly associated with AICN development. Conclusion: This study suggests a high incidence of AICN in patients receiving high IV AMX doses, representing one third of AKI causes in our study. Female gender appeared as the sole risk factor for AICN in this study.

Pentraxins are soluble innate immunity receptors involved in sensing danger molecules. They are classified as short (CRP, SAP) and long pentraxin subfamilies, including the prototypic long pentraxin PTX3. Pentraxins act mainly as bridging molecules favoring the clearance of microbes and dead cells. They are also involved in many other biological processes, such as regulation of complement activation, inflammation and tissue homeostasis. Autoantibodies directed against pentraxins have been reported in various autoimmune diseases, especially in systemic lupus erythematosus and ANCA-associated vasculitis. In this review, we review the main biological characteristics and functions of pentraxins and summarize data concerning autoantibodies directed against pentraxins in the context of autoimmune diseases and discuss their potential pathological role.