Background: Urinary tract infection (UTI) occurs in 30%-50% of individuals with autosomal dominant polycystic kidney disease (ADPKD). However, the clinical relevance of asymptomatic pyuria in ADPKD patients remains unknown. Methods: We retrospectively reviewed medical records of 256 ADPKD patients who registered to the ADPKD clinic at Seoul National University Hospital from Aug 1999 to Aug 2010. We defined the asymptomatic pyuria as more than 5-9 white blood cells in high-power field with no related symptoms or signs of overt UTI. Patients were categorized into 2 groups depending on its duration and frequency: Group A included non-pyuria and transient pyuria patients; Group B included recurrent and persistent pyuria patients. The association between asymptomatic pyuria and both the development of overt UTI and the deterioration of renal function were examined. Results: With a mean follow-up duration of 65.3 months, 176 (68.8%) out of 256 patients experienced 681 episodes of asymptomatic pyuria and 50 episodes of UTI. The annual incidence of asymptomatic pyuria was 0.492 episodes/patient/year. The patients in group B showed female predominance (58.5% vs. 42.0%, P=0.01) and experienced an upper UTI more frequently (hazard ratio: 4.612, 95% confidence interval: 1.735-12.258; P=0.002, adjusted for gender and hypertension). The annual change in estimated glomerular filtration rate (ΔeGFR) was significantly larger in magnitude in group B than in group A (-2.7±4.56 vs. -1.17±5.8, respectively; P=0.01). Age and Group B found to be the independent variables for ΔeGFR and developing end-stage renal disease (16.0% vs. 4.3%, respectively; P=0.001). Conclusions: Chronic asymptomatic pyuria may increase the risk of developing overt UTI and may contribute to declining renal function in ADPKD.

Regulatory T cells (Tregs) can suppress immunologic damage in renal ischemia-reperfusion injury (IRI), but the isolation and ex vivo expansion of these cells for clinical application remains challenging. Here, we investigated whether the IL-2/anti-IL-2 complex (IL-2C), a mediator of Treg expansion, can attenuate renal IRI in mice. IL-2C administered before bilateral renal IRI induced Treg expansion in both spleen and kidney, improved renal function, and attenuated histologic renal injury and apoptosis after IRI. Furthermore, IL-2C administration reduced the expression of inflammatory cytokines and attenuated the infiltration of neutrophils and macrophages in renal tissue. Depletion of Tregs with anti-CD25 antibodies abrogated the beneficial effects of IL-2C. However, IL-2C–mediated renal protection was not dependent on either IL-10 or TGF-β. Notably, IL-2C administered after IRI also enhanced Treg expansion in spleen and kidney, increased tubular cell proliferation, improved renal function, and reduced renal fibrosis. In conclusion, these results indicate that IL-2C–induced Treg expansion attenuates acute renal damage and improves renal recovery in vivo, suggesting that IL-2C may be a therapeutic strategy for renal IRI.

Background: Beneficial aspects of solid organ transplantation, which encompass survival benefit, improved quality of life, and cost efficacy, have been clearly demonstrated. However, regional and ethnic differences require further studies to identify prognostic factors and transplant outcomes against various backgrounds. After previous efforts of a nationwide, retrospective study on the kidney transplant outcomes in Korea, a new prospective-designed version of the Korean Organ Transplantation Registry (KOTRY) was launched in 2014. Methods: Cohorts of kidney, liver, heart, lung, and pancreas transplantation were developed. Data on demographics, comorbid conditions, laboratory tests, including tissue typing and panel reactive antibody tests, immunosuppressive regimen followed, concentration and dosage of immunosuppressants, allograft rejection type, infectious events, cardiovascular outcomes, malignancies, donor comorbidity, and outcomes of living donors are collected. Longitudinal data collection is based on a regular annual interval, and blood samples are collected before organ transplantation and again at 1 and 3 years posttransplantation. To enhance data quality, a predefined data verification system operates on a Web-based database, and transplant center users receive regular education about updates. Data are cleansed thrice a year, and feedback given to centers about outlier values and missing data. Annual auditing is conducted. Results: Currently, 59 centers are participating in KOTRY. The estimated annual enrollment is more than 2000 cases. Conclusions: KOTRY, as a systematic Korean transplant cohort, is expected to provide important information on Asian organ transplantation. The processes used to establish KOTRY provide a good model for launching new nationwide transplant cohort studies.

Background: Acute kidney injury (AKI) is commonly encountered in clinical practice and is associated with poor patient outcomes and increased health care costs. Despite it posing significant challenges for clinicians, effective measures for AKI prediction and prevention are lacking. Previously published AKI prediction models mostly have a simple design without external validation. Furthermore, little is known about the process of linking model output and clinical decisions due to the black-box nature of neural network models. Objective: We aimed to present an externally validated recurrent neural network (RNN)–based continuous prediction model for in-hospital AKI and show applicable model interpretations in relation to clinical decision support. Methods: Study populations were all patients aged 18 years or older who were hospitalized for more than 48 hours between 2013 and 2017 in 2 tertiary hospitals in Korea (Seoul National University Bundang Hospital and Seoul National University Hospital). All demographic data, laboratory values, vital signs, and clinical conditions of patients were obtained from electronic health records of each hospital. We developed 2-stage hierarchical prediction models (model 1 and model 2) using RNN algorithms. The outcome variable for model 1 was the occurrence of AKI within 7 days from the present. Model 2 predicted the future trajectory of creatinine values up to 72 hours. The performance of each developed model was evaluated using the internal and external validation data sets. For the explainability of our models, different model-agnostic interpretation methods were used, including Shapley Additive Explanations, partial dependence plots, individual conditional expectation, and accumulated local effects plots. Results: We included 69,081 patients in the training, 7675 in the internal validation, and 72,352 in the external validation cohorts for model development after excluding cases with missing data and those with an estimated glomerular filtration rate less than 15 mL/min/1.73 m2 or end-stage kidney disease. Model 1 predicted any AKI development with an area under the receiver operating characteristic curve (AUC) of 0.88 (internal validation) and 0.84 (external validation), and stage 2 or higher AKI development with an AUC of 0.93 (internal validation) and 0.90 (external validation). Model 2 predicted the future creatinine values within 3 days with mean-squared errors of 0.04-0.09 for patients with higher risks of AKI and 0.03-0.08 for those with lower risks. Based on the developed models, we showed AKI probability according to feature values in total patients and each individual with partial dependence, accumulated local effects, and individual conditional expectation plots. We also estimated the effects of feature modifications such as nephrotoxic drug discontinuation on future creatinine levels. Conclusions: We developed and externally validated a continuous AKI prediction model using RNN algorithms. Our model could provide real-time assessment of future AKI occurrences and individualized risk factors for AKI in general inpatient cohorts; thus, we suggest approaches to support clinical decisions based on prediction models for in-hospital AKI.