Determination of a microRNA signature of protective kidney ischemic preconditioning originating from proximal tubules

Ischemic preconditioning (IPC) is effective in limiting subsequent ischemic acute kidney injury in experimental models. MicroRNAs are an important class of post-transcriptional regulator and show promise as biomarkers of kidney injury. We evaluated the time- and dose-dependence of benefit from IPC in a rat model of functional (bilateral) ischemia–reperfusion injury (IRI). We found optimal protection from subsequent injury following short, repetitive sequences of preconditioning insult. We subsequently used hybridization array and microRNA sequencing to characterize microRNA signatures of protective IPC and of IRI. These approaches identified a profile of microRNA changes consequent on IRI, that were limited by prior IPC. To localize these signals within the kidney, we used laser capture microdissection and RT-qPCR to measure microRNA abundance in nephron segments, pinpointing microRNA changes principally to glomeruli and proximal tubules. Our data describe a unique microRNA signature for IRI in the rat kidney. Pulsatile IPC reduces kidney damage following IRI and diminishes this microRNA signal. We have also identified candidate microRNAs that may act as biomarkers of injury and therapeutic targets in this context

A localized ischemic preconditioning regimen increases tumor necrosis factor a expression in a rat model of kidney ischemia-reperfusion injury

OBJECTIVES: We evaluated a continuous, immediate, localized ischemic preconditioning regimen in a rat model of ischemia-reperfusion injury and assessed whether it attenuated injury at the histologic and molecular levels. MATERIALS AND METHODS: Fifteen adult male Lewis rats received sham operation, left unilateral warm ischemia (45 minutes of cross-clamping of the renal pedicle; ischemia-reperfusion injury group), or 15 minutes of ischemia followed by a 20-minute reperfusion period, 45 minutes of ischemia-reperfusion injury, and subsequent reperfusion (ischemic preconditioning/ischemia-reperfusion injury group). Kidney tissue was retrieved 48 hours later, sectioned, stained with hematoxylin and eosin, and examined. We used RNA extraction and real-time quantitative polymerase chain reaction analysis to assess acute kidney injury markers, cytokines, and microRNA-21. RESULTS: Forty-five minutes of unilateral ischemia-reperfusion injury caused marked changes in histology at 48 hours, characterized by endothelial loss, tubulointerstitial damage (inflammation, cast formation), tubular cell necrosis, and glomerular capsule thickening. The ischemia-reperfusion injury and ischemic preconditioning/ischemia-reperfusion injury groups showed no measurable differences in histology. Expression of the acute kidney injury markers was significantly increased in the ischemia-reperfusion injury versus Sham group; however, no difference was found between the ischemia reperfusion injury and ischemic preconditioning/ischemia-reperfusion injury groups. Similarly, expression of interleukin 17, interleukin 18, and tumor necrosis factor ? was significantly increased in the ischemia-reperfusion injury versus Sham group. No significant difference was found between the ischemia-reperfusion injury and ischemic preconditioning/ischemia-reperfusion injury groups for interleukin 17 and interleukin 18; however, tumor necrosis factor ? expression was significantly increased in the ischemic preconditioning/ischemia-reperfusion injury versus ischemia-reperfusion injury group. CONCLUSIONS: In our ischemic preconditioning model, tumor necrosis factor α expression was increased without altering the sequelae of ischemia-reperfusion injury. The long-term consequences of this augmented early inflammatory response and whether these consequences are altered by variations in ischemic preconditioning or a subsequent injury require further study

A new comprehensive scoring system is an accurate and robust tool for histological assessment of rat kidney IRI [Abstract]

Introduction: Hypothermic machine perfusion improves outcomes fromkidney transplantation, and molecular analyses of hypothermic machineperfusate (HMP) have the potential to identify biomarkers of organ viabilityprior to transplantation. Effective prediction of organ-specific outcomes prior totransplantation offers enormous advantages to the transplant surgeon, andmay increase the organ donor pool by allowing use of the ever-increasing‘extended criteria donors (ECD)’. MicroRNAs (miRNAs) have considerablepotential for use as biomarkers of numerous pathological processes, includingkidney disease. Our previous analysis of urine samples from renal transplantpatients with delayed graft function identified miRNAs miR-10a, -21, -29a, -221and -429 as potential biomarkers of kidney injury. This study aimed todetermine if expression of these miRNAs predicted early transplant outcomes.Methods: HMP samples were taken after 15 min, 1 and 2 h of perfusion for11 kidneys (ECD/DCD) placed on the LifePortprior to transplantation.Following RNA extraction using miRNeasy Mini Kits (Qiagen), cDNA wasgenerated using the High Capacity Reverse Transcription kit (Life Technolo-gies) and RT-qPCR was carried out using specific TaqMan microRNAdetection assays (Life Technologies). Clinical data including demographicsand eGFR at 6 months post transplantation were collected.Results: MiRNAs were readily detected and found to be stable in the HMPmedium from the 11 kidneys (ECD/DCD) included in this study. Expression ofmiR-10a, -21, -29a, -221 and -429 in HMP after 1 h of perfusion correlatedsignificantly with eGFR at 6 months post transplantation.Conclusion: MicroRNAs are emerging as important biomarkers in thecontext of kidney injury and transplantation. This study shows that expressionmiR-10a, -21, -29a, -221 and -429 in HMP is predictive of early outcomesfollowing kidney transplantation. Further studies are underway to confirm thesein larger cohort

Robust rat and mouse models of bilateral renal ischemia reperfusion injury

Background/Aim: Acute and chronic kidney diseases are a major contributor to morbidity and mortality worldwide, with no specific treatments currently available for these. To enable understanding the pathophysiology of and testing novel treatments for acute and chronic kidney disease, a suitable in vivo model of kidney disease is essential. In this article, we describe two reliable rodent models (rats and mice) of efficacious kidney injury displaying acute to chronic kidney injury progression, which is also reversible through novel therapeutic strategies such as ischemic preconditioning (IPC). Materials and Methods: We utilized adult male Lewis rats and adult male wildtype (C57BL/6) mice, performed a midline laparotomy, and induced warm ischemia to both kidneys by bilateral clamping of both renal vascular pedicles for a set time, to mimic the hypoxic etiology of disease commonly found in kidney injury. Results: Bilateral ischemia reperfusion injury caused marked structural and functional kidney injury as exemplified by histology damage scores, serum creatinine levels, and kidney injury biomarker levels in both rodents. Furthermore, this effect displayed a dose-dependent response in the mouse model. Conclusion: These rodent models of bilateral kidney IRI are reliable, reproducible, and enable detailed mechanistic study of the underlying pathophysiology of both acute and chronic kidney disease. They have been carefully optimised for single operator use with a strong track record of training both surgically trained and surgically naïve operators

International Nosocomial Infection Control Consortiu (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module

We report the results of an International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2007-December 2012 in 503 intensive care units (ICUs) in Latin America, Asia, Africa, and Europe. During the 6-year study using the Centers for Disease Control and Prevention's (CDC) U.S. National Healthcare Safety Network (NHSN) definitions for device-associated health care–associated infection (DA-HAI), we collected prospective data from 605,310 patients hospitalized in the INICC's ICUs for an aggregate of 3,338,396 days. Although device utilization in the INICC's ICUs was similar to that reported from ICUs in the U.S. in the CDC's NHSN, rates of device-associated nosocomial infection were higher in the ICUs of the INICC hospitals: the pooled rate of central line–associated bloodstream infection in the INICC's ICUs, 4.9 per 1,000 central line days, is nearly 5-fold higher than the 0.9 per 1,000 central line days reported from comparable U.S. ICUs. The overall rate of ventilator-associated pneumonia was also higher (16.8 vs 1.1 per 1,000 ventilator days) as was the rate of catheter-associated urinary tract infection (5.5 vs 1.3 per 1,000 catheter days). Frequencies of resistance of Pseudomonas isolates to amikacin (42.8% vs 10%) and imipenem (42.4% vs 26.1%) and Klebsiella pneumoniae isolates to ceftazidime (71.2% vs 28.8%) and imipenem (19.6% vs 12.8%) were also higher in the INICC's ICUs compared with the ICUs of the CDC's NHSN