Tumor necrosis factor α-converting enzyme inhibitor attenuates lipopolysaccharide-induced reactive oxygen species and mitogen-activated protein kinase expression in human renal proximal tubule epithelial cells

Tumor necrosis factor-α (TNFα) and the angiotensin system are involved in inflammatory diseases and may contribute to acute kidney injury. We investigated the mechanisms by which TNFα-converting enzyme (TACE) contributes to lipopolysaccharide (LPS)-induced renal inflammation and the effect of TACE inhibitor treatment on LPS-induced cellular injury in human renal proximal tubule epithelial (HK-2) cells. Mice were treated with LPS (10 mg/kg, i.p.) and HK-2 cells were cultured with or without LPS (10 µg/ml) in the presence or absence of a type 1 TACE inhibitor (1 µM) or type 2 TACE inhibitor (10 µM). LPS treatment induced increased serum creatinine, TNFα, and urinary neutrophil gelatinase-associated lipocalin. Angiotensin II type 1 receptor, mitogen activated protein kinase (MAPK), and TACE increased, while angiotensin-converting enzyme-2 (ACE2) expression decreased in LPS-induced acute kidney injury and LPS-treated HK-2 cells. LPS induced reactive oxygen species and the down-regulation of ACE2, and these responses were prevented by TACE inhibitors in HK-2 cells. TACE inhibitors increased cell viability in LPS-treated HK-2 cells and attenuated oxidative stress and inflammatory cytokines. Our findings indicate that LPS activates renin angiotensin system components via the activation of TACE. Furthermore, inhibitors of TACE are potential therapeutic agents for kidney injury.

Long-term Tolvaptan Treatment of Autosomal Dominant Polycystic Kidney Disease in Korea

A 22-year-old male patient was diagnosed with autosomal dominant polycystic kidney disease (ADPKD). He received conservative treatment with an angiotensin-converting enzyme inhibitor. Two years later, oral therapy, consisting of 60 mg tolvaptan per day, was initiated. Compared with height-adjusted total kidney volume, the rate of kidney growth reduced significantly from 7.33% to 0.66% annually, since commencement of the tolvaptan therapy. The liver enzyme profile and serum sodium level and osmolality were constantly within normal ranges. In Korea, this is the first reported case of a patient with ADPKD who received tolvaptan treatment for more than 1 year. This case demonstrates that long-term tolvaptan treatment appears to be safe, well tolerated, and effective for ADPKD.

Relationship between serum uric acid and mortality among hemodialysis patients: Retrospective analysis of Korean end-stage renal disease registry data

Background

It is thought that hyperuricemia might lower the risk of mortality among hemodialysis patients, unlike in the general population, but the evidence is controversial. The aim of the current study was to evaluate the impact of serum uric acid level on the long-term clinical outcomes of hemodialysis patients in Korea.

Methods

Retrospective analysis was performed on data from the End-Stage Renal Disease Registry of the Korean Society of Nephrology. This included data for 7,333 patients (mean age, 61 ± 14 years; 61% male) who received hemodialysis from January 2001 through April 2015. Initial laboratory data were used in the analysis.

Results

The mean serum uric acid level in this study was 7.1 ± 1.7 mg/dL. Body mass index, normalized protein catabolic rate, albumin, and cholesterol were positively correlated with serum uric acid level after controlling for age and sex. After controlling for demographic data, comorbidities, and residual renal function, a higher uric acid level was independently associated with a significantly lower all-cause mortality (hazard ratio [HR], 0.90 per 1 mg/dL increase in uric acid level; 95% confidence interval [CI], 0.83-0.97; P = 0.008), but not cardiovascular mortality (HR, 0.90; 95% CI, 0.80-1.01; P = 0.078). Comparing uric acid levels in the highest and lowest quintiles, the HR for all-cause mortality was 0.65 (95% CI, 0.42-0.99; P = 0.046).

Conclusion

Hyperuricemia was strongly associated with a lower risk of all-cause mortality, but there seems to be no significant association between serum uric acid level and cardiovascular mortality among Korean hemodialysis patients with end-stage renal disease.

Acute kidney injury due to povidone-iodine ingestion: A case report

RATIONALE

Povidone-iodine is a broad-spectrum antiseptic applied topically to treat wounds and prevent their infection. There have been several case reports of acute kidney injury (AKI) in burn patients after povidone-iodine irrigation and in patients receiving the substance as a sclerotherapy agent for management of lymphocele after renal transplantation. However, biopsy-confirmed AKI after ingestion of povidone-iodine has not previously been described.

PATIENT CONCERNS

A 47-year-old man who had apparently ingested povidone-iodine solution and presented with nausea, vomiting, and reduced urine output. Laboratory data revealed blood urea nitrogen of 124 mg/dL, serum creatinine of 6.3 mg/dL, impaired liver function, and leukocytosis. Urine iodine/creatinine ratio was markedly elevated.

DIAGNOSES

Acute tubular necrosis and interstitial nephritis secondary to povidone-iodine ingestion.

INTERVENTIONS

The patient was admitted to the intensive care unit and underwent continuous venovenous hemodiafiltration. Kidney biopsy showed acute tubular necrosis and interstitial nephritis. Unstained sections showed tan objects in the tubular lumina that were suspected to be povidone-iodine casts. Corticosteroid therapy (1 mg/kg/day) was started after kidney biopsy.

OUTCOMES

Renal function recovered after hemodialysis and corticosteroid medication, but not completely.

LESSONS

We have reported the first case of biopsy-confirmed AKI accompanied by increased urine iodine concentration following povidone-iodine ingestion.

Impact of random urine proteinuria on maternal and fetal outcomes of pregnancy: a retrospective case-control study

BACKGROUND/AIMS

Proteinuria is associated with hypertension and preeclampsia in pregnancy. However, the impact of random urine proteinuria on fetal and maternal outcomes has not been established. We investigated the influence of random urine proteinuria on the clinical outcomes of pregnancy.

METHODS

From January 2008 to December 2010, 2,822 patients were retrospectively studied. A total of 536 pregnant women with proteinuria in random urine and matched controls without proteinuria via propensity score matching were analyzed. Proteinuria was checked by the dipstick method.

RESULTS

The patients' mean age was 33.0 ± 4.7 years, and the mean gestational age was 235.6 ± 50.6 days on admission. The prevalence of hypertension and chronic kidney disease was 2.4% (n = 67) and 1.0% (n = 29), respectively. Women with random urine proteinuria showed higher blood urea nitrogen levels and a higher incidence of hematuria. These women also had a higher incidence of preeclampsia, preterm labor, premature rupture of membranes, and intrauterine growth restriction. Proteinuria was strongly correlated with preeclampsia in both propensity score matching (p < 0.001, r = 0.783) and unmatched whole samples (p < 0.001, r = 0.851).

CONCLUSIONS

These findings suggest that random urine proteinuria is associated with preeclampsia, preterm labor, premature rupture of membrane, and intrauterine growth restriction.

Central Diabetes Insipidus Linked to Rathke's Cleft Cyst, Polyuria in a 17-year-old Girl

A 17-year-old girl presented with polyuria (7 L/day) and polydipsia for one year. Initial urine osmolality was 113mOsm/kg H₂O. Following 6 h of fluid restriction, serum plasma osmolality reached 300mOsm/kg H₂O, whereas urine osmolality was 108mOsm/kg H₂O. Urine osmolality was increased by 427% from 108 to 557mOsm/kg after vasopressin challenge. The patient was diagnosed with central diabetes insipidus, possibly derived from the atypical occupation of a Rathke's cleft cyst at the pituitary stalk following magnetic resonance imaging with enhancement. She was discharged with desmopressin nasal spray (10 µg); urine output was maintained at 2-3 L/day, and urine osmolality was >300 mOsm/kg. Additional pituitary image studies and evaluation of hypopituitarism should be included in the differential diagnosis of patients with central diabetes insipidus.

Prognostic impact of hyponatremia occurring at various time points during hospitalization on mortality in patients with acute myocardial infarction

We investigated the incidence and prognostic impact of hyponatremia occurring at various time points during hospitalization on long-term mortality in acute myocardial infarction (AMI) survivors. We retrospectively studied 1863 patients diagnosed with AMI. Baseline, nadir, and discharge sodium levels during hospitalization were recorded and analyzed. Hyponatremia was defined as a serum sodium level <135 mEq/L. On the basis of baseline, nadir, and discharge sodium levels during hospitalization, hyponatremia was diagnosed in 309 (16.6%), 518 (27.8%), and 147 (7.9%) patients, respectively. In a multivariate Cox-proportional regression analysis, discharge sodium level had the strongest significant relationship with long-term mortality (hazard ratio [HR] as continuous variable = 1.06, 95% confidence interval [CI]: 1.01-1.11, P = .026; HR as categorical variable = 1.71; 95% CI: 1.06-2.75; P = .028), but baseline and nadir sodium had no prognostic impact on long-term mortality after adjustment. The serum sodium level and incidence of hyponatremia varied at different time points during hospitalization. In addition, the association between sodium level and long-term mortality differed at these various time points. The discharge sodium level, among the various time points, seems the best predictor of long-term mortality in AMI survivors.

Association between vitamin D deficiency and health-related quality of life in patients with chronic kidney disease from the KNOW-CKD study

Vitamin D deficiency is a growing health problem in both the general population and in patients with chronic kidney disease (CKD). However, the relationship between serum 25-hydroxyvitamin D levels and health-related quality of life in CKD is not well established. This study examined the association between vitamin D deficiency and quality of life in pre-dialysis CKD patients. Serum 25-hydroxyvitamin D levels and the Korean version of the Kidney Disease Quality of Life short form were obtained for 1844 pre-dialysis CKD patients in the prospective KoreaN cohort Study for Outcomes in patients With Chronic Kidney Disease (KNOW-CKD). The baseline estimated glomerular filtration rate was 50.26 ± 0.71 mL/min/1.73 m2. We identified 1294 (70.2%) patients with vitamin D deficiency, defined as a 25-hydroxyvitamin D level < 20 ng/ml. The scores of the kidney disease component summary, physical component summary, and mental component summary in the vitamin D deficiency group were significantly lower compared to the scores of those without vitamin D deficiency. The serum 25-hydroxyvitamin D level was independently associated with the kidney disease component summary and mental component summary scores (β = 0.147, p = 0.003 and β = 0.151, p = 0.047). In conclusion, there was a significant association between serum 25-hydroxyvitamin D levels and kidney disease component summary and mental component summary scores in pre-dialysis CKD patients.

Chronic Kidney Disease-Mineral Bone Disorder in Korean Patients: a Report from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD)

This study examined the characteristics of biochemical parameters, bone diseases, and vascular calcification in Korean patients with chronic kidney disease (CKD) not yet on dialysis. Serum levels of fibroblast growth factor 23 (FGF23), intact parathyroid hormone (iPTH), 25-hydroxyvitamin D3 (25D), and 1,25-dihydroxyvitamin D3 (1,25D); lumbar spine, total hip, and femur neck bone mineral densities; and brachial-to-ankle pulse wave velocity (baPWV) representing vascular calcification were measured at baseline for 2,238 CKD patients in the KoreaN Cohort Study for Outcomes in Patients With CKD (KNOW-CKD). Increases in serum FGF23 and iPTH preceded changes in serum calcium and phosphate, similar to Western populations. However, the 25D and 1,25D levels decreased earlier than serum FGF23 or iPTH increased, with a decreased estimated glomerular filtration rate (eGFR) in Korean CKD patients. Vitamin D deficiency occurred in 76.7% of patients with CKD stage 1. Bone mineral densities were lowest in CKD stage 5 (lumbar spine, -0.64 ± 1.67; total hip, -0.49 ± 1.21; femur neck, -1.02 ± 1.25). Osteoporosis was more prevalent in patients with higher CKD stages. The mean baPWV, abdominal aortic calcification (AAC), and coronary calcium score also increased, with declined eGFR. In conclusion, a decline in serum vitamin D levels was observed in early CKD stages before significant increases of FGF23 and iPTH in the Korean CKD population compared with that in Western populations. Increased bone disease and vascular calcification occurred in early-stage CKD.

Biomarkers Predicting Survival of Sepsis Patients Treated with Continuous Renal Replacement Therapy

The present study investigated the prognostic factors predicting survival of patients with sepsis and acute kidney injury (AKI) undergoing continuous renal replacement therapy (CRRT). This retrospective observational study included 165 sepsis patients treated with CRRT. The patients were divided into two groups; the survivor group (n=73, 44.2%) vs. the nonsurvivor group (n=92, 55.8%). AKI was defined by the 2012 Kidney Disease: Improving Global Outcomes Clinical Practice Guidelines. We analyzed medical histories, clinical characteristics and laboratory findings of the enrolled patients when they started CRRT. In addition, we performed binary logistic regression and cox regression analysis. In the survivor group, urine output during the first day was significantly higher compared with the nonsurvivor group (55.7±66.3 vs. 26.6±46.4, p=0.001). Patients with urine output <30 mL/hour during the 1st day showed worse outcomes than ≥30 mL/hour in the logistic regression (hazard ratio 2.464, 95% confidence interval 1.152-5.271, p=0.020) and the cox regression analysis (hazard ratio 1.935, 95% confidence interval 1.147-3.263, p=0.013). In conclusion, urine output may predict survival of septic AKI patients undergoing CRRT. In these patients, urine output <30 mL/hour during the first day was the strongest risk factor for in-hospital mortality.

Impact of Transient and Persistent Acute Kidney Injury on Chronic Kidney Disease Progression and Mortality after Gastric Surgery for Gastric Cancer

Acute kidney injury (AKI) is common after gastric surgery for gastric cancer and associated with adverse outcomes. However, the impact of transient or persistent AKI on clinical outcomes after gastric surgery for gastric cancer has not been described. We performed a retrospective study of 4,886 patients with normal renal function who underwent partial or total gastrectomy for gastric cancer between June 2002 and December 2012. AKI patients were classified as transient and persistent AKI based on the return of serum creatinine to the level indicating no AKI within 7 days. Our outcomes included occurrence of new-onset chronic kidney disease (CKD) and mortality 1 year after gastric surgery. AKI occurred in 638 (13.1%) after gastric surgery. Transient AKI was documented in 574 (90%). Use of diuretics and contrast agents was a common risk factor for persistent and transient AKI. Length of intensive care unit (ICU) and hospital stay, and ICU admission rate were higher in patients with transient AKI than in those without AKI. Although patients with persistent AKI had a higher new-onset CKD 1 year after gastric surgery after adjusting for multiple covariates, transient AKI was not associated with new-onset CKD. The 1-year mortality rates were significantly higher in patients with transient and persistent AKI. Not only persistent AKI but transient AKI is associated with increased risk of hospital complications and a significantly higher risk of long-term mortality than patients without AKI after gastric surgery. Moreover, persistent AKI, but not transient AKI, is associated with CKD progression at 1 year.