Hsiang-Hao Hsu

Prognosis of Patients on Extracorporeal Membrane Oxygenation: The Impact of Acute Kidney Injury on Mortality

BACKGROUND Extracorporeal membrane oxygenation (ECMO) has been utilized for patients in critical condition, such as those with life-threatening respiratory failure or postcardiotomy cardiogenic shock. This study analyzed the outcomes of patients treated with ECMO and identified the relationship between prognosis and the Acute Kidney Injury Network (AKIN) scores obtained at pre-ECMO support (AKIN0-hour); and at post-ECMO support 24 hours (AKIN24-hour) and 48 hours (AKIN48-hour). METHODS This study reviewed the medical records of 102 critically ill patients on ECMO support at a specialized intensive care unit at a tertiary care university hospital between March 2002 and January 2008. Demographic, clinical, and laboratory variables were retrospectively collected as survival predicators. RESULTS The overall mortality rate was 57.8%. The most common condition requiring ECMO support was cardiogenic shock. Goodness-of-fit was good for AKIN0-hour, AKIN24-hour, and AKIN48-hour criteria. The AKIN0-hour, AKIN24-hour, and AKIN48-hour scoring systems also had excellent areas under the receiver operating characteristic curve (0.804±0.046, 0.811±0.045, and 0.858±0.040, respectively). Furthermore, multiple logistic regression analysis indicated that AKIN48-hour, age, and Glasgow Coma Scale score on the first day of intensive care unit admission were independent risk factors for hospital mortality. Finally, cumulative survival rates at 6-month follow-up after hospital discharge differed significantly (p<0.05) for AKIN48-hour stage 0 versus AKIN48-hour stages 1, 2, and 3; and AKIN48-hour stage 1 and 2 versus AKIN48-hour stage 3. CONCLUSIONS During ECMO support, the AKIN48-hour scoring system proved to be a reproducible evaluation tool with excellent prognostic abilities for these patients.

Improved Iron Utilization and Reduced Erythropoietin Resistance by On-Line Hemodiafiltration

Background: Recent investigation has shown that on-line hemodiafiltration (HDF) can reduce the amount of recombinant human erythropoietin (rhEPO) deemed necessary to reach the target hematocrit. The aim of this study was to analyze the potential effect of on-line HDF on rhEPO resistance in relation to iron utilization and anemia-related parameters, when compared to conventional hemodialysis (HD). Methods: Ninety-two chronic uremic patients were treated with conventional HD and then shifted to on-line HDF. Measurements of various erythropoiesis-related parameters were collected during HD and on-line HDF periods for statistical analysis for erythropoietin resistance. Results: Patients treated with on-line HDF switching from conventional HD significantly contributed to the reduction of EPO dose to reach a higher mean hematocrit level (31.8 ± 4.4% vs. 29.5 ± 3.9%, p < 0.001) and a reduction of the serum ferritin level (322.5 ± 268.4 vs. 544.9 ± 642.4, p < 0.001). The median EPO/Hct ratio was greater in the HD period (504.6 ± 310.1) than in the on-line HDF period (307.6 ± 334.4) (p < 0.001). These results indicated a reduced EPO resistance and improved iron utilization by on-line HDF. By multiple regression analysis, the significant predictors of EPO resistance are ferritin, transferrin, albumin, and TACurea (Time average concentration of urea) in HD treatment. In on-line HDF modality, in addition to ferritin and albumin, the duration of on-line HDF is a negative predictor in EPO resistance. Conclusion: When on-line HDF is recommended to chronic dialysis patients, long-term use of this technique provides an efficient means of achieving the goal of an elevated hemoglobulin by reducing EPO resistance, improved iron utilization and may further improve the quality of life.

Resveratrol ameliorates early diabetic nephropathy associated with suppression of augmented TGF-β/smad and ERK1/2 signaling in streptozotocin-induced diabetic rats.

Diabetic nephropathy (DN) is the major cause of end-stage renal disease. The early changes in DN are characterized by an increased in kidney size, glomerular volume, and kidney function, followed by the accumulation of glomerular extracellular matrix, increased urinary albumin excretion (UAE), glomerular sclerosis, and tubular fibrosis. Resveratrol (RSV) has been shown to ameliorate hyperglycemia and hyperlipidemia in streptozotocin-induced diabetic rats. In the present study, we examined the beneficial effects of RSV on DN and explored the possible mechanism of RSV action. Male Sprague-Dawley rats were injected with streptozotocin at 65mg/kg body weight. The induction of diabetes mellitus (DM) was confirmed by a fasting plasma glucose level ≥300mg/dL and symptoms of polyphagia and polydipsia. The DM rats were treated with or without RSV at 0.75mg/kg body weight 3 times a day for 8 weeks. Animals were sacrificed and kidney histology was examined by microscopy. Urinary albumin excretion, glomerular hypertrophy and expressions of fibronectin, collagen IV, and TGF-β in the glomeruli were alleviated in RSV-treated DM rats, but not in untreated DM rats. In addition, RSV treatment reduced the thickness of the glomerular basement membrane (GBM) to the original thickness and increased nephrin expressions to normal levels in DM rats. Moreover, RSV inhibited phosphorylation of smad2, smad3 and ERK1/2 in diabetic rat kidneys. This is the first report showing that RSV alleviates early glomerulosclerosis in DN through TGF-β/smad and ERK1/2 inhibition. In addition, podocyte injuries of diabetic kidneys are lessened by RSV.

Outcome scoring systems for short-term prognosis in critically ill cirrhotic patients.

Cirrhotic patients admitted to intensive care units (ICUs) have high mortality rates. This study evaluated specific predictors and scoring systems for hospital and 6-month mortality in critically ill cirrhotic patients. This investigation is a prospective clinical study performed in a 10-bed specialized hepatogastroenterology ICU in a tertiary care university hospital in Taiwan. Two hundred two consecutive cirrhotic patients admitted to the ICU during a 2-year period were enrolled in this study. Demographic, clinical, and laboratory variables recorded on the first day of ICU admission and scoring systems applied were prospectively recorded for post hoc analysis for predicting survival. The overall hospital mortality was 59.9%, and the 6-month mortality rate was 70.8%. The main causes of cirrhosis were hepatitis B (29%), hepatitis C (22%), and alcoholism (20%). The major cause of ICU admission was upper gastrointestinal bleeding (36%). Multiple logistic regression analysis revealed that the Acute Kidney Injury Network (AKIN) score at the 48th hour of ICU admission and the Sequential Organ Failure Assessment (SOFA) as well as the Model for End-Stage Liver Disease scores on the first day of ICU admission were independent risk factors for hospital mortality. The SOFA score had the best discriminatory power (0.872 ± 0.036), whereas the AKIN had the best Youden index (0.57) and the highest correctness of prediction (79%). Cumulative survival rates at the 6-month follow-up after hospital discharge differed significantly (P < 0.05) for AKIN stage 0 vs. stages 1, 2, and 3, and for AKIN stage 1 vs. stage 3. The AKIN, SOFA, and Model for End-stage Liver Disease (MELD) scores showed well discriminative power in predicting hospital mortality in this group of patients. The AKIN scoring system proved to be a reproducible evaluation tool with excellent prognostic abilities for these patients.

The AMPK agonist AICAR inhibits TGF-β1 induced activation of kidney myofibroblasts.

Activation of interstitial myofibroblasts and excessive production of extracellular matrix proteins are common pathways that contribute to chronic kidney disease. In a number of tissues, AMP-activated kinase (AMPK) activation has been shown to inhibit fibrosis. Here, we examined the inhibitory effect of the AMPK activator, 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR), on renal fibrosis in vivo and TGF-β1-induced renal fibroblasts activation in vitro. A unilateral ureteral obstruction (UUO) model was induced in male BALB/c mice. Mice with UUO were administered AICAR (500 mg/Kg/day) or saline intraperitoneally 1 day before UUO surgery and daily thereafter. Both kidneys were harvested 7 days after surgery for further analysis. For the in vitro studies, NRK-49F rat fibroblasts were pre-incubated with AICAR before TGF-β1 stimulation. The inhibitory effects of AICAR on signaling pathways down-stream of TGF-β1 were analyzed. In UUO model mice, administration of AICAR attenuated extracellular matrix protein deposition and the expression of α-smooth muscle actin (α-SMA), type I collagen and fibronectin. Pre-incubation of NRK-49F cells with AICAR inhibited TGF-β1-induced myofibroblast activation. Silencing of AMPKα1 by siRNA or by blocking AMPK activation with Compound C diminished the inhibitory effect of AICAR. Moreover, the inhibitory effects of AICAR on TGF-β1-mediated myofibroblast activation were associated with down-regulation of ERK 1/2 and STAT3. Our results suggest that AICAR reduces tubulointerstitial fibrosis in UUO mice and inhibits TGF-β1-induced kidney myofibroblast activation. AMPK activation by AICAR may have therapeutic potential for the treatment of renal tubulointerstitial fibrosis.

Overlooked Risk for Chronic Kidney Disease after Leptospiral Infection: A Population-Based Survey and Epidemiological Cohort Evidence.

Background Leptospirosis is the most widespread zoonosis. Chronic human infection and asymptomatic colonization have been reported. However, renal involvement in those with leptospira chronic exposure remains undetermined. Methods and Findings In 2007, a multistage sampling survey for chronic kidney disease (CKD) was conducted in a southern county of Taiwan, an area with a high prevalence of dialysis. Additionally, an independent cohort of 88 participants from a leptospira-endemic town was followed for two years after a flooding in 2009. Risks of CKD, stages of CKD, associated risk factors as well as kidney injury markers were compared among adults with anti-leptospira antibody as defined by titers of microscopic agglutination test (MAT). Of 3045 survey participants, the individuals with previous leptospira exposure disclosed a lower level of eGFR (98.3±0.4 vs 100.8±0.6 ml/min per 1.73 m2, P<0.001) and a higher percentage of CKD, particularly at stage 3a-5 (14.4% vs 8.5%), than those without leptospira exposure. Multivariable linear regression analyses indicated the association of leptospiral infection and lower eGFR (95% CI -4.15 to -1.93, P < 0.001). In a leptospiral endemic town, subjects with a MAT titer ≥400 showed a decreased eGFR and higher urinary kidney injury molecule–1 creatinine ratio (KIM1/Cr) level as compared with those having lower titers of MAT (P<0.05). Furthermore, two participants with persistently high MAT titers had positive urine leptospira DNA and deteriorating renal function. Conclusions and Significance Our data are the first to show that chronic human exposure of leptospirosis is associated significantly with prevalence and severity of CKD and may lead to deterioration of renal function. This study also shed light on the search of underlying factors in areas experiencing CKD of unknown aetiology (CKDu) such as Mesoamerican Nephropathy.

Essential Calcium-binding Cluster of Leptospira LipL32 Protein for Inflammatory Responses through the Toll-like Receptor 2 Pathway

Background: LipL32 induces a renal cell inflammatory response through the TLR2-signaling pathway. Results: Ca2+-binding LipL32 mutants showed attenuated TLR2-mediated inflammatory responses. Conclusion: The Ca2+-binding cluster of LipL32 is essential in regulating its interaction with TLR2 for subsequent inflammatory response induction. Significance: This investigation provides significant evidence for crucial roles of the Ca2+-binding cluster of LipL32 for pathogenesis via association with TLR2. Leptospirosis is the most widespread zoonosis caused by the pathogenic Leptospira worldwide. LipL32, a 32-kDa lipoprotein, is the most abundant protein on the outer membrane of Leptospira and has an atypical poly(Asp) motif (161DDDDDGDD168). The x-ray crystallographic structure of LipL32 revealed that the calcium-binding cluster of LipL32 includes several essential residues Asp132, Thr133, Asp164, Asp165, and Tyr178. The goals of this study were to determine possible roles of the Ca2+-binding cluster for the interaction of LipL32 and Toll-like receptor 2 (TLR2) in induced inflammatory responses of human kidney cells. Site-directed mutagenesis was employed to individually mutate Ca2+-binding residues of LipL32 to Ala, and their effects subsequently were observed. These mutations abolished primarily the structural integrity of the calcium-binding cluster in LipL32. The binding assay and atomic force microscopy analysis further demonstrated the decreased binding capability of LipL32 mutants to TLR2. Inflammatory responses induced by LipL32 variants, as determined by TLR2 pathway intermediates hCXCL8/IL-8, hCCL2/MCP-1, hMMP7, and hTNF-α, were also lessened. In conclusion, the calcium-binding cluster of LipL32 plays essential roles in presumably sustaining LipL32 conformation for its proper association with TLR2 to elicit inflammatory responses in human renal cells.

Polyomavirus BK-encoded microRNA suppresses autoregulation of viral replication.

Polyomavirus BK (BKV) infection is an important cause of renal allograft failure. Viral microRNAs are known to play a crucial role in viral replication. This study investigated the expression of BKV-encoded microRNAs (miR-B1) in patients with polyomavirus-associated nephropathy (PVAN) and their role in viral replication. Following BKV infection in renal proximal tubular cells, the 3p and 5p miR-B1 levels were significantly increased. Cells transfected with the vector containing the miR-B1 precursor (the miR-B1 vector) showed a significant increase in expression of 3p and 5p miR-B1 and decrease in luciferase activity of a reporter containing the 3p and 5p miR-B1 binding sites, compared to cells transfected with the miR-B1-mutated vector. Transfection of the miR-B1 expression vector or the 3p and 5p miR-B1 oligonucleotides inhibited expression of TAg. TAg-enhanced promoter activity and BKV replication were inhibited by miR-B1. In contrast, inhibition of miR-B1 expression by addition of miR-B1 antagomirs or silencing of Dicer upregulated the expression of TAg and VP1 proteins in BKV-infected cells. Importantly, patients with PVAN had significantly higher levels of 3p and 5p miR-B1 compared to renal transplant patients without PVAN. In conclusion, we demonstrated that (1) miR-B1 expression was upregulated during BKV infection and (2) miR-B1 suppressed TAg-mediated autoregulation of BKV replication. Use of miR-B1 can be evaluated as a potential treatment strategy against BKV infection.

High-Sensitivity C-Reactive Protein Predicts Mortality and Technique Failure in Peritoneal Dialysis Patients

Introduction An elevated level of serum C-reactive protein (CRP) is widely considered an indicator of an underlying inflammatory disease and a long-term prognostic predictor for dialysis patients. This cross-sectional cohort study was designed to assess the correlation between the level of high-sensitivity CRP (HS-CRP) and the outcome of peritoneal dialysis (PD) patients. Methods A total of 402 patients were stratified into 3 tertiles (lower, middle, upper) according to serum HS-CRP level and and followed up from October 2009 to September 2011. During follow-up, cardiovascular events, infection episodes, technique failure, and mortality rate were recorded. Results During the 24-month follow-up, 119 of 402 patients (29.6%) dropped out from PD, including 28 patients (7.0%) who died, 81 patients (20.1%) who switched to hemodialysis, and 10 patients (2.5%) who underwent kidney transplantation. The results of Kaplan–Meier analysis and log-rank test demonstrated a significant difference in the cumulative patient survival rate across the 3 tertiles (the lowest rate in upper tertile). On multivariate Cox regression analysis, only higher HS-CRP level, older age, the presence of diabetes mellitus (DM), lower serum albumin level, and the occurrence of cardiovascular events during follow-up were identified as independent predictors of mortality. Every 1 mg/L increase in HS-CRP level was independently predictive of a 1.4% increase in mortality. Multivariate Cox regression analysis also showed that higher HS-CRP level, the presence of DM, lower hemoglobin level, lower serum albumin level, higher dialysate/plasma creatinine ratio, and the occurrence of infective episodes and cardiovascular events during follow-up were independent predictors of technique failure. Conclusions The present study shows the importance of HS-CRP in the prediction of 2-year mortality and technique survival in PD patients independent of age, diabetes, hypoalbuminemia, and the occurrence of cardiovascular events.

Leptospiral outer membrane protein LipL32 induces inflammation and kidney injury in zebrafish larvae.

Leptospirosis is an often overlooked cause of acute kidney injury that can lead to multiple organ failure and even death. The principle protein that conserved in many pathogenic leptospires is the outer membrane protein LipL32. However, the role of LipL32 in the pathogenesis of renal injury in leptospirosis is not entirely clear. Here we studied the effects of LipL32 on the developing kidney in zebrafish larvae. Incubation of zebrafish larvae with Leptospira santarosai serovar Shermani induced acute tubular injury predominantly in the proximal pronephric ducts. Furthermore, microinjection of lipl32 mRNA or recombinant LipL32 protein into zebrafish larvae increased macrophage accumulation and disrupted the basolateral location of NA-K-ATPase in pronephric ducts. These changes led to substantial impairment of the pronephric kidney structure. We further demonstrated that morpholino knockdown of tlr2, but not tlr4, reduced the LipL32-induced leukocyte infiltration and kidney injury. These data demonstrate that LipL32 contributes to the renal pathology in leptospirosis and gives some clues to the potential virulence of LipL32. Our results support the use of zebrafish as a model organism for studying the disease mechanism of leptospiral infection. This model might permit the future exploration of the virulence and molecular pathways of different leptospiral outer membrane proteins.