RESUMEN
Aristolochic acid nephropathy is characterized by rapidly progressive tubulointerstitial nephritis culminating in end-stage renal failure and urothelial malignancy. Profibrotic effects of aristolochic acid are linked to growth arrest of proximal tubular epithelial cells; however, the underlying mechanisms are largely undetermined. miRNAs are small, endogenous, post-transcriptional regulators of gene expression implicated in numerous physiological and pathological processes. In the present study, we characterized the mechanism of aristolochic acid-induced cell cycle arrest and its regulation by miRNAs. Incubation with aristolochic acid led to profound G2/M arrest in proximal tubular epithelial cells via p53-mediated inactivation of the maturation-promoting complex, CDK1/cyclin-B1. Analysis of miRNA expression identified up-regulation of miRNAs, including miR-192, miR-194, miR-450a, and miR-542-3p. The stable overexpression of miR-192 recapitulated G2/M arrest via repression of the E3 ubiquitin ligase, murine double-minute 2, a negative regulator of p53. p53-induced transcription of p21(cip1) and growth arrest and DNA damage 45 and resulted in the inactivation and dissociation of the maturation-promoting complex. These data demonstrate a core role for miR-192 in mediating proximal tubular epithelial cell G2/M arrest after toxic injury by aristolochic acid. Because numerous studies have linked such growth arrest to fibrosis after proximal tubular epithelial cell injury, this mechanism may have widespread relevance to recovery/nonrecovery after acute kidney injury.
Asunto(s)
Ácidos Aristolóquicos/envenenamiento , Puntos de Control de la Fase G2 del Ciclo Celular/genética , Enfermedades Renales/patología , Puntos de Control de la Fase M del Ciclo Celular/genética , MicroARNs/genética , Western Blotting , Células Cultivadas , Células Epiteliales/patología , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Humanos , Inmunoprecipitación , Enfermedades Renales/inducido químicamente , Túbulos Renales Proximales/patología , MicroARNs/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/fisiologíaRESUMEN
BACKGROUND: Despite improvements in safety seen over the last 20 years, percutaneous renal biopsy is still associated with haemorrhagic complications. Due to concerns over delayed bleeding, most nephrologists would advocate overnight observation. Recent evidence in both adult and paediatric populations suggest that in some groups, this is unnecessary. Since 1991, we have provided a day-case renal biopsy service performing 70 such procedures per year. In this study, we present a retrospective analysis of this practice. METHODS: A total of 192 patients over a consecutive 3-year period were analysed retrospectively. Patients were selected according to standardized criteria, and biopsy was performed using a modern technique (automated biopsy needles under ultrasound guidance). Complications were identified by examination of case notes and local hospital admission databases, and by telephone interview. Our pathology database was examined for sample adequacy and diagnosis. RESULTS: There were no delayed complications in the study group with 187 patients (97.4%) being discharged home on the same day. Major complications occurred in five patients (2.6%), all related to bleeding. Of these, two needed radiological intervention to achieve haemostasis. Sufficient tissue for diagnosis was achieved in 97% of cases, with a mean of 47 ± 23 glomeruli obtained per patient. Most biopsies were obtained with ≤ 2 passes (84%). CONCLUSIONS: Our findings show that in selected adult patients, renal biopsy can be performed as a day-case procedure. Given the benefits of day-case strategies in terms of patient and healthcare costs, we advocate increased utilization of this technique.