Deep Learning Model for Predicting Intradialytic Hypotension Without Privacy Infringement: A Retrospective Two-Center Study

Objective

Previously developed Intradialytic hypotension (IDH) prediction models utilize clinical variables with potential privacy protection issues. We developed an IDH prediction model using minimal variables, without the risk of privacy infringement.

Methods

Unidentifiable data from 63,640 hemodialysis sessions (26,746 of 79 patients for internal validation, 36,894 of 255 patients for external validation) from two Korean hospital hemodialysis databases were finally analyzed, using three IDH definitions: (1) systolic blood pressure (SBP) nadir <90 mmHg (Nadir90); (2) SBP decrease ≥20 mmHg from baseline (Fall20); and (3) SBP decrease ≥20 mmHg and/or mean arterial pressure decrease ≥10 mmHg (Fall20/MAP10). The developed models use 30 min information to predict an IDH event in the following 10 min window. Area under the receiver operating characteristic curves (AUROCs) and precision-recall curves were used to compare machine learning and deep learning models by logistic regression, XGBoost, and convolutional neural networks.

Results

Among 344,714 segments, 9,154 (2.7%), 134,988 (39.2%), and 149,674 (43.4%) IDH events occurred according to three different IDH definitions (Nadir90, Fall20, and Fall20/MAP10, respectively). Compared with models including logistic regression, random forest, and XGBoost, the deep learning model achieved the best performance in predicting IDH (AUROCs: Nadir90, 0.905; Fall20, 0.864; Fall20/MAP10, 0.863) only using measurements from hemodialysis machine during dialysis session.

Conclusions

The deep learning model performed well only using monitoring measurement of hemodialysis machine in predicting IDH without any personal information that could risk privacy infringement.

MO270: N-3-Oxododecanoyl Homoserine Lactone Inhibits Angiogenesis by Activating the Angiopoietin-Tie System in Human Endothelial Cells

BACKGROUND AND AIMS

The dysregulation of the angiopoietin–Tie system is associated with the development of sepsis-associated endothelial dysfunction. Bacterial quorum-sensing molecules act as pathogen-associated molecular patterns; however, the effect of quorum-sensing molecules on the angiopoietin–Tie system remains uncertain.

METHOD

This study investigated the molecular mechanisms of endothelial dysfunction in human umbilical vein endothelial cells treated with N-3-oxododecanoyl homoserine lactone (3OC12-HSL) derived from Pseudomonas aeruginosa.

RESULTS

Treatment with 3OC12-HSL reduced cell viability in a dose-dependent manner. Moreover, 3OC12-HSL treatment impaired the ability of tube formation even at non-lethal concentrations. The patterns of mRNA expression regarding the angiopoietin-Tie axis were assessed and the increased mRNA expressions of angiopoietin-2, Foxo-1, Tie1, and VEGFR2 were found in the 3OC12-HSL-treated cells. Western blot revealed that treatment with 3OC12-HSL increased the relative expressions of agiopoietin-2 and Foxo-1 and decreased the expression of Tie2. The study further evaluated the expression of IQGAP1 and the expressions of IQGAP1 and Rac1 decreased in cells treated with 3OC12-HSL. In addition, coimmunoprecipitation studies showed that treatment with 3OC12-HSL decreased the association between IQGAP1 and Rac1 in endothelial cells.

CONCLUSION

3OC12-HSL can impair endothelial angiogenesis via the activation of the angiopoietin-Tie pathway. In addition, it may induce the dissociation of IQGAP1 with Rac1. Adjuvant therapy for blocking the quorum-sensing systems can help preserve endothelial cell integrity and prevent organ failure in patients with sepsis.

Characteristics of bioimpedance-determined fluid shifts according to intradialytic blood pressure difference

This study was designed to identify the fluid spaces that are most changed during ultrafiltration (UF) according to intradialytic blood pressure (BP) difference. BP data were collected five times (before hemodialysis [HD] and 1–4 h of HD). Intradialytic BP difference was calculated as the highest minus lowest of these BP measurements. Intradialytic systolic BP (SBP) difference over 20 mm Hg and diastolic BP (DBP) difference over 10 mm Hg were defined as wide intradialytic SBP difference (SYS-W) and DBP difference (DIA-W), respectively. We measured the various fluid spaces before HD and 1–4 h of HD, and 30 min after HD using a portable, whole-body bioimpedance spectroscopy (BIS). In this study, 85 prevalent patients aged over 18 years with a fixed dry weight (65.38 ± 12.45 years, 54.18% men, 52.50% patients with diabetes), undergoing HD had participated. 1) Mean relative reduction of extracellular water (ECW) was significantly higher in SYS-W than in narrow intradialytic SBP difference (SYS-N) patients from 1 h to 30 min after HD. 2) Mean relative reduction of intracellular water (ICW) was significantly lower in DIA-W than in narrow intradialytic DBP difference (DIA-N) patients from 1 h to 30 min after HD. 3) ECW of patients with SYS-W was significantly lower than that of patients with SYS-N. Patients with SYS-W have the characteristics of fluid shifts in which reduction of ECW was steeper than patients with SYS-N whereas fluid shifts of ICW were lower in patients with DIA-W than patients with DIA-N.

N-3-oxododecanoyl homoserine lactone exacerbates endothelial cell death by inducing receptor-interacting protein kinase 1-dependent apoptosis

Endothelial dysfunction is associated with the initiation of sepsis-associated organ failure. Bacterial quorum-sensing molecules act as pathogen-associated molecular patterns; however, the effects of quorum-sensing molecules on endothelial cells remain less understood. This study investigated the molecular mechanisms of quorum-sensing molecule-induced cell death and their interaction with lipopolysaccharide (LPS) in human umbilical vein endothelial cells. Endothelial cells were treated with N-3-oxododecanoyl homoserine lactone (3OC12-HSL) and LPS derived from Pseudomonas aeruginosa. Treatment with 3OC12-HSL reduced cell viability in a dose-dependent manner, and cotreatment with 3OC12-HSL and LPS enhanced cell death. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay revealed an increase in apoptotic cell death following 3OC12-HSL treatment; furthermore, cotreatment with 3OC12-HSL and LPS enhanced apoptosis. Western blotting revealed that treatment with 3OC12-HSL activated the receptor-interacting protein kinase 1 (RIPK1) pathway, leading to an increase in the levels of cleaved caspase 8 and 3. In addition, we found that treatment with necrostatin-1, an RIPK1 inhibitor, reduced cell death and ameliorated the activation of the RIPK1-dependent apoptotic pathway in 3OC12-HSL-treated cells. In conclusion, 3OC12-HSL induced endothelial cell apoptosis via the activation of the RIPK1 pathway, independent of LPS toxicity. Inhibition of RIPK1 may act as a therapeutic option for preserving endothelial cell integrity in patients with sepsis by disrupting the mechanism by which quorum-sensing molecules mediate their toxicity.

Relationship Between Arteriovenous Fistula Stenosis and Circulating Levels of Neutrophil Granule Proteins in Chronic Hemodialysis Patients

BACKGROUND

Arteriovenous fistula (AVF) stenosis leading to its failure is a major cause of morbidity in hemodialysis patients; however, detailed pathogenesis of AVF stenosis is still under investigation. To date, monocytes/macrophages have been considered pivotal players in chronic inflammation of vascular disease including atherosclerosis and AVF stenosis. However, recent evidence strongly suggests that neutrophils and neutrophil granule proteins are important contributors to vascular disease. The aim of the present study was to evaluate the relationship between AVF stenosis and neutrophil activation by measuring circulating levels of neutrophil elastase (NE) and lactoferrin, enzymes released on neutrophil activation, as well as other inflammation markers including neutrophil counts.

METHODS

This was a single-center, prospective observational study conducted on 83 prevalent hemodialysis patients with AVF. Blood levels of biomarkers and sonography (US) measurement were assessed at baseline and 1 year after enrollment. Clinical follow-up continued for one more year (a total of 2 years for each patient) to observe any AVF events.

RESULTS

Circulating levels of both NE and lactoferrin positively correlated with the degree of AVF stenosis. Patients with significant AVF stenosis had older AVFs, higher neutrophil-to-lymphocyte ratio (NLR), and higher circulating levels of NE and lactoferrin. On multivariate logistic regression analysis, both circulating levels of NE and NLR remained independent predictors of significant AVF stenosis.

CONCLUSIONS

Circulating levels of NE and the NLR were identified as independent predictors of at-risk AVF with significant stenosis. Our data suggest the potential role of neutrophil and innate immunity activation on the development of AVF stenosis.

Effect of Renamezin upon attenuation of renal function decline in pre-dialysis chronic kidney disease patients: 24-week prospective observational cohort study

Renamezin^® is a modified capsule-type oral spherical adsorptive carbon which lowers indoxyl sulfate levels in patients with advanced chronic kidney disease (CKD). This 24-week prospective observational cohort study was performed to evaluate the effect of Renamezin^® upon attenuation of renal function decline. A total of 1,149 adult patients with baseline serum creatinine 2.0–5.0 mg/dL were enrolled from 22 tertiary hospital in Korea from April 2016 to September 2018. Among them, a total of 686 patients completed the study and were included in the intention-to-treat analysis. A total of 1,061 patients were included in the safety analysis. The mean age was 63.5 years and male patients were predominant (63.6%). Most of the patients (76.8%) demonstrated high compliance with study drug (6g per day). After 24 week of treatment, serum creatinine was increased from 2.86±0.72 mg/dL to 3.06±1.15 mg/dL (p<0.001), but estimated glomerular filtration rate was not changed significantly during observation period (22.3±6.8 mL/min/1.73m² to 22.1±9.1 mL/min/1.73m², p = 0.243). Patients with age over 65 years old and those under good systolic blood pressure control <130 mmHg were most likely to get benefit from Renamezin^® treatment to preserve renal function. A total of 98 (9.2%) patients out of 1,061 safety population experienced 134 adverse events, of which gastrointestinal disorders were the most common. There were no serious treatment-related adverse events. Renamezin^® can be used safely to attenuate renal function decline in moderately advanced CKD patients.

MO018QUORUM SENSING MOLECULE INDUCES THE RECEPTOR-INTERACTING PROTEIN KINASE 1-DEPENDENT APOPTOSIS SYNERGISTICALLY WITH LIPOPOLYSACCHARIDE IN ENDOTHELIAL CELLS

Background and Aims

Endothelial dysfunction is an initial step for sepsis-associated organ failure. Bacterial quorum sensing molecules play as pathogen-associated molecular patterns, however, the impact of quorum sensing molecules on endothelial cells remains uncertain. This study investigated the molecular mechanism of quorum sensing molecule-induced cell death and the interaction with lipopolysaccharide (LPS) in human umbilical vein endothelial cells.

Method

Endothelial cells were treated with varying concentrations of N-3-oxododecanoyl-HSL (3OC12-HSL) and LPS derived from Pseudomonas aeruginosa.

Results

Treatment of 3OC12-HSL reduced cell viability in dose-dependent manners, and the combination of this molecule and LPS exacerbated cell deaths in compared to single treatment of LPS. The terminal deoxynucleotidyl transferase dUTP nick end labeling assay revealed that there were clear increases in apoptotic death following the 3OC12-HSL treatment. Treatment of 3CO12-HSL activated the receptor-interacting protein kinase 1 (RIPK1) pathway, resulting in increases in expression of caspase 8 and caspase 3. Moreover, the combination treatment of LPS and 3OC12-HSL amplified these expressions.

Conclusion

Treatment of 3OC12-HSL reduces endothelial cell viability, and this effect is synergistical with LPS. 3OC12-HSL induces apoptotic cell death, through the activation of the RIPK1 pathway, moreover, it is amplified in combination with LPS.

Phase angle values, a good indicator of nutritional status, are associated with median value of hemoglobin rather than hemoglobin variability in hemodialysis patients

Background

Our aim was to elucidate whether Hb variability affects nutritional status in HD patients.

Methods

This study included chronic HD patients (n = 76) with available monthly Hb levels up to 24 months prior to the body composition monitoring (BCM) measurement. The parameters obtained in the BCM included body mass index (BMI), lean tissue index (LTI), fat tissue index (FTI), body cell mass index (BCMI), overhydration/extracellular water ratio (OH), and phase angle (PhA). The coefficient of variation (Hb-CV), standard deviation (Hb-SD), and range of Hb (Hb-RAN) were used as indexes of Hb variability. In addition, minimum (Hb-Min), maximum (Hb-Max), average (Hb-Avg), and median (Hb-Med) Hb levels (g/dL) were analyzed.

Results

There were no significant differences in clinical, biochemical, and nutritional indexes based on the Hb-CV level. Compared to patients with an Hb-Med ≤ 10.77, those with an Hb-Med >10.77 had higher albumin levels, total iron-binding capacity (TIBC), and PhA and lower average weekly prescribed darbepoetin. Age, female sex, OH, and darbepoetin dosage were negatively correlated with PhA. Serum albumin, phosphorus, TIBC, Hb-Med, and Hb-Avg were positively correlated with PhA. In multiple linear regression analysis, PhA was positively associated with Hb-Med and serum albumin level, whereas PhA was negatively associated with age and female sex. The area under the curve (AUC) of Hb-Med was 0.665 (p = 0.040) in predicting PhA >5.00°

Conclusions

PhA was not affected by indexes of Hb variability, whereas PhA was associated with Hb-Med in chronic HD patients.

Neutrophil-Lymphocyte Ratio as a Predictor of Venous Thromboembolism after Total Knee Replacement

Venous thromboembolism (VTE) is a potentially serious complication after total knee replacement (TKR), and recent guideline recommends thromboprophylaxis for VTE after TKR. The neutrophil-lymphocyte ratio (NLR) has emerged as a simple and new prognostic biomarker for several cardiovascular diseases. This study was performed to investigate the precise incidence of postoperative VTE and the role of NLR for predicting VTE in patients receiving thromboprophylaxis after TKR. We retrospectively enrolled 264 patients undergoing TKR who underwent routine screening enhanced pulmonary artery and lower extremity venography computed tomography (CT) scan within 7 postoperative days. Biochemical tests were performed within 2 weeks prior to surgery, and the NLR was defined as the absolute neutrophil count in peripheral blood divided by lymphocyte count. All patients received thromboprophylaxis with enoxaparin postoperatively. Of 264 patients, 102 (38.6%) were diagnosed with deep vein thrombosis (DVT) or pulmonary embolism on CT scan. Preoperative NLR was significantly higher in patients with postoperative VTE compared with that in patients without VTE (2.57 ± 1.59 vs. 2.11 ± 1.10, p = 0.011). Receiver operating characteristic curve analysis showed that a preoperative NLR of 1.90 was the best cutoff value for the prediction of postoperative VTE (sensitivity 57.8%, specificity 55.6%, and area under curve 0.589). In the multivariate analysis, a preoperative NLR ≥1.90 was a sole independent predictor of postoperative VTE (odds ratio: 1.95, 95% computed tomography: 1.16-3.31, p = 0.013). The present study shows a higher incidence of VTE (38.6%) after TKR in patients receiving thromboprophylaxis than that reported in previous studies. Furthermore, preoperative NLR was significantly higher in patients with postoperative VTE, and a high preoperative NLR (≥1.90) was an independent predictor of VTE after TKR. NLR measurement may be a simple and useful method for the prediction of VTE in patients undergoing TKR.

A long journey for acute kidney injury biomarkers

Acute kidney injury (AKI) is a life-threatening illness that continues to have an in-hospital mortality rate of patients with AKI ranges from 20% to 50% or greater, depending on underlying conditions. However, it has only marginally declined over the past 25 years. Previous authoritative publications have been pointed out that the lack of useful biomarkers for AKI has limited progress in improving the outcomes of this disorder. The purpose of this paper is to review the recent biomarkers involved in the early detection of AKI and main reasons for the failure to identify new AKI biomarkers. So far, several new AKI biomarkers have been discovered and validated to improve early diagnosis, degree of severity, pathophysiology, differential diagnosis, prediction for major kidney adverse events (MAKE, risk groups for progressive renal failure, need for renal replacement therapy [RRT], or death). These biomarkers can be classified into functional, damage and pre-injury phase biomarkers. However, the clinical use of the studied biomarkers in AKI prediction remains unclear because large prospective multicenter trials have failed to demonstrate troponin-like diagnostic performance. Reasons for the failure to identify AKI biomarkers are the heterogeneity of AKI itself, biomarker limitations and long roads to the validation of candidates for new AKI biomarkers. In an effort to overcome these barriers to identifying new AKI biomarkers, kidney biopsy specimens should be obtained and assessed in human AKI populations. Research in this field should be carried out in a pan-social approach rather than conducted by just a few medical institutions.

Monocyte counts are negatively associated with ankle-brachial index values in non-dialysis-dependent chronic kidney disease patients

Our aim was to determine which leukocyte subtypes are most relevant to ankle-brachial index (ABI) values in patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). The study included 79 NDD-CKD patients aged 62.84 ± 12.09 years (63.33% men; 26.67% patients with diabetes) and 21 age-matched normal controls. According to the estimated glomerular filtration rate (eGFR) calculated by the CKD-Epidemiology Collaboration equation (CKD-EPI), we classified the study population into 2 groups (21 subjects with NDD-CKD with an eGFR 60–89 mL/min/1.73m², 58 subjects with NDD-CKD with eGFR <60 mL/min/1.73 m²). ABI was calculated as the ratio of the ankle systolic BP divided by the arm systolic BP using an ABI-form device. An automated hematologic analyzer was used to measure total and differential leukocyte counts. Monocyte counts and monocyte-to-total leukocyte count ratios (MTR) in patients with an ABI value <1.10 were significantly higher than those in patients with an ABI value ≥1.10, respectively. Univariate analyses revealed that mean ABI values were negatively correlated with monocyte count (r= −0.341; p = 0.044), MTR (r= −0.346, p = 0.031). Multivariate linear regression analyses showed that monocyte count was negatively associated with ABI values (β ± SE = −1.825 ± 0.341, p = 0.013). The area under the curve of monocyte counts was 0.695 (95% confidence interval 0.586–0.804, p = 0.002) in predicting an ABI value <1.10. Monocyte counts are negatively associated with ABI values in patients with NDD-CKD without apparent peripheral arterial occlusive disorder (PAOD).

Severe asymptomatic hypokalemia associated with prolonged licorice ingestion: A case report

RATIONALE

Excessive ingestion of licorice can cause pseudohyperaldosteronism. A few case reports in the available literature have described significant hypokalemia secondary to licorice consumption with clinical manifestations of muscle weakness, paralysis, or severe hypertension. To our knowledge, no report has discussed severe asymptomatic hypokalemia associated with licorice consumption.

PATIENT CONCERNS

A 79-year-old man presented to the urology clinic with a several-month history of urinary frequency and a weak stream. Routine laboratory investigations revealed serum potassium (K) level of 1.8 mmol/L, and he was immediately admitted to the nephrology department.

DIAGNOSES

He was in a good state of health, and systemic and neurological examinations were unremarkable. However, laboratory investigations revealed severe hypokalemia and metabolic alkalosis accompanied with renal K wasting and hypertension, suggesting a state of mineralocorticoid excess. Hormonal studies revealed low serum renin and aldosterone but normal serum cortisol levels. Detailed history taking revealed that he had used licorice tea daily during the preceding 18 months.

INTERVENTIONS AND OUTCOME

The patient's serum K returned to normal levels after vigorous K replacement and discontinuation of licorice intake. He was also diagnosed with benign prostatic hyperplasia during hospitalization and was treated.

LESSONS

Chronic licorice ingestion can precipitate severe hypokalemia, although patients may remain asymptomatic. This case report indicates that the severity of a patient's clinical presentation depends on individual susceptibility, as well as the dose and duration of licorice intake.

Evaluation of the Wnt signaling pathway as a prognostic marker in patients with urosepsis

The Wnt signaling pathway has critical roles in dysregulated inflammation during sepsis; however, its impacts on clinical outcomes remain uncertain. This prospective observational study investigated the association between the Wnt pathway and clinical outcomes in patients with urosepsis. The study included 38 patients with urosepsis and 20 healthy individuals. Wnt3a and Wnt5a levels were measured at admission. The primary outcome was the occurrence of major adverse kidney events (MAKE), defined as new renal replacement therapy, stage 3 acute kidney injury, or death. Both Wnt3a and Wnt5a levels were higher in the patient group than in the control (P = 0.001 and P < 0.001, respectively). The primary outcome occurred in 13 (34.2%) subjects. The levels of Wnt5a were higher in subjects with MAKE than in those without MAKE (P = 0.015); however, Wnt3a levels showed no significant difference. Moreover, Wnt5a levels could be a marker to predict the possibility of MAKE (area under the curve 0.74 [0.57-0.92]; P = 0.016). Serum creatinine levels on day 0, day 5, and on discharge day were evaluated. The levels of creatinine on discharge day were higher in patients with high Wnt5a levels, compared to those with low Wnt5a levels (P = 0.030); however, no difference in Wnt5a levels was observed on day 0 and 5. Wnt3a and Wnt5a levels increased in patients with urosepsis. Moreover, evaluation of Wnt5a levels might help to predict the occurrence of MAKE and renal recovery in these patients.

P0565EVALUATION OF THE WNT SIGNALING PATHWAY AS A PROGNOSTIC MARKER IN PATIENTS WITH UROSEPSIS

Background and Aims

Sepsis is a serious condition characterized by a dysregulated inflammatory response to infection, leading to life threatening organ dysfunction. Acute kidney injury (AKI) is one of sepsis-induced organ dysfunction and results in extremely high morbidity and mortality. Emerging evidence demonstrated the relationship between the Wnt signaling pathway and inflammation. In vitro and in vivo studies reported that inhibition of canonical Wnt/β-catenin signaling attenuates the sepsis-induced organ injury and systemic inflammation. On the other hand, Wnt5a, a typical glycoprotein of the non-canonical pathway, may have proinflammatory functions. Studies showed that Wnt5a levels are elevated in patients with sepsis. Despite potentials, there is a paucity of studies evaluating these pathways and correlating it with clinical data, particularly in patients with sepsis. Therefore, this prospective observational study investigated the association between the Wnt pathway and clinical outcomes in patients with urosepsis.

Method

Adult patients (&gt;18 years of age) with urinary tract infection admitted to the intensive care unit of the Myongji Hospital were screened for sepsis according to the 2012 Surviving Sepsis Campaign Guidelines. Thereafter, 38 subjects who were diagnosed with urosepsis were included in the study. Twenty healthy volunteers (10 males and 10 females, aged 55–64 years) were recruited into the control group. In patient serum creatinine levels at day 0, day 5, and at discharge day were obtained for accessing renal recovery. Wnt3a and Wnt5a levels were measured at admission. Levels of Wnt3a and Wnt5a proteins were evaluated using the enzyme-linked immunosorbent assay (ABclonal Biotechnology, Woburn, MA, USA). The primary composite outcome was the incidence of Major Adverse Kidney Events (MAKE), which was defined as new renal replacement therapy, stage 3 AKI by the guideline of the Kidney Disease Improving Global Outcomes, or death. Thereafter, the levels of Wnt3a and Wnt5a were evaluated to predict the primary composite outcome.

Results

1) Both Wnt3a and Wnt5a levels were significantly increased in the urosepsis group (P = 0.001 and P &lt; 0.001 respectively) compared to normal individuals. 2) Out of 38 included patients with urosepsis, MAKE occurred in 13 (34.2%) subjects. The patients were divided into two groups, with MAKE (13 patients, 34.2%) and without MAKE (25 patients, 65.8%). No significant difference in the levels of Wnt3a was observed between the two groups (P = 0.927); however, the levels of Wnt5a were higher in the patients with MAKE than in those without MAKE (P = 0.015). 3) Results showed that Wnt5a levels could be a predictor for the occurrence of MAKE, while Wnt3a levels are not (P = 0.927). The area under the curve of Wnt5a was 0.74 (95% confidence interval 0.57– 0.92; P = 0.016). 4) The levels of serum creatinine at discharge were higher in the Wnt5a high group than in the Wnt5a low group (P = 0.030) although the levels on day 0 and day 5 were similar (P = 0.201 and 0.233 respectively).

Conclusion

This study confirmed the elevated levels of Wnt3a and Wnt5a in patients with urosepsis. It furthermore identified that the elevated levels of Wnt5a could predict a higher incidence of MAKE and non recovery of renal function in the patients; however, Wnt3a levels are not associated with MAKE and renal recovery. Accordingly, we suggest that Wnt5a levels can be used as a prognostic marker in patients with sepsis. Further studies with a larger number of subjects are required to confirm the utility of Wnt5a as a biomarker in various diseases including sepsis. This study also suggests the potentials of the Wnt signaling pathway as novel therapeutic targets in sepsis.

Association between Serum N-Terminal Pro-Brain Natriuretic Peptide Concentration and Left Ventricular Dysfunction and Extracellular Water in Continuous Ambulatory Peritoneal Dialysis Patients

Background

This study investigated the association between serum N-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels and extracellular water (ECW%) and left ventricular (LV) dysfunction in continuous ambulatory peritoneal dialysis (CAPD) patients.

Methods

The study involved 30 stable CAPD patients: 14 males, 16 females; mean age 52 ± 14 years; mean CAPD duration 34 ± 12 months; 12 with diabetes mellitus (DM) and 18 non-DM. Serum NT-pro-BNP levels were determined using electrochemiluminescence immunoassay. Baseline echocardiography was performed using a Hewlett-Packard Sonos 1000 (Andover, Massachusetts, USA) device equipped with a 2.25-MHz probe, allowing M-mode, two-dimensional, and pulsed Doppler measurements. Left ventricular mass index (LVMI) was calculated according to the Penn formula. A multifrequency bioimpedance analyzer was used; ECW% was calculated as a percentage of total body water and was considered the index of volume load.

Results

( 1 ) Serum NT-pro-BNP level, ECW%, LVMI, and LV ejection fraction in CAPD patients were 3924 (240 – 74460) pg/mL, 36.7% ± 2.2%, 158 ± 48 g/m2, and 60.5% ± 11.2%, respectively. ( 2 ) Patients were divided into three tertiles (10 patients each) according to their serum NT-pro-BNP concentration [1st tertile 1168 (240 – 2096), 2nd tertile 4856 (2295 – 20088), 3rd tertile 35012 (20539 – 74460) pg/mL]. The tertiles did not differ significantly in terms of age, sex, presence of DM, body mass index, or PD duration. Patients in the 3rd tertile (highest serum NT-pro-BNP concentration) had the highest LVMI (126 ± 45 vs 160 ± 41 vs 200 ± 23 g/m2 for 1st, 2nd, 3rd tertiles, respectively) and the lowest LV ejection fraction (66% ± 11% vs 62% ± 6% vs 55% ± 9%). ECW% did not differ significantly between tertiles (35.5% ± 2.0% vs 37.5% ± 2.0% vs 36.5% ± 2.0%). ( 3 ) In CAPD patients, serum NT-pro-BNP levels correlated positively with LVMI ( r = 0.628, p = 0.003) and negatively with LV ejection fraction ( r = –0.479, p = 0.033). Serum NT-pro-BNP levels did not correlate with ECW% ( r = 0.227, p = 0.25). ( 4 ) Stepwise regression analysis showed that LV ejection fraction (b = -0.610, p = 0.015) and LVMI (b = 0.415, p = 0.007) were independently associated with the serum NT-pro-BNP concentration.

Conclusions

There was no link between ECW% and serum NT-pro-BNP concentration. Thus, serum NT-pro-BNP levels may not provide objective information with respect to pure hydration status in CAPD patients. In contrast, serum NT-pro-BNP levels were linked to LVMI and LV ejection fraction in CAPD patients. Therefore, while the serum NT-pro-BNP concentration might not be a useful clinical marker for extracellular fluid volume load, it appears useful for evaluating LV hypertrophy and LV dysfunction in CAPD patients.

P1478 Evaluation of reversibility of alcoholic cardiomyopathy using doubaimine stress echocardiography

Alcoholic cardiomyopathy (CM) is known as a reversible CM. Appropriate medications with cessation of alcohol may lead to full recovery of chamber size and contractility. But there is not much information about morphologic and hemodynamic changes over the course of treatment, and predictors of reversibility. We experienced the patient with alcoholic CM who was admitted with heart failure and recovered over 1 year and 5 months. He consumed daily 180g alcohol for 6 months before admission. On initial echocardiography, left atrial (LA) dimension, left ventricular (LV) systolic dimension (SD) and diastolic dimension (DD), inferior vena cava (IVC) size, and ejection fraction (EF) were 50 mm, 69 mm, 78 mm, 27 mm and 22%, respectively. Doppler examination revealed a restrictive pattern in tansmitral flow, and a systolic peak velocity/diastolic peak velocity (S/D) ratio of less than 1 in pulmonary vein flow (PVF). Pressure gradient through tricuspid regurgitation was 29 mmHg. Coronary angiogram confirmed no significant stenosis. Within 1 week after medications, LVEF increased mainly by decrease of enlarged LVSD which might be partly caused by volume overload, evidenced by respiratory variation of transmitral flow. On 8th day, we performed dobutamine stress echocardiography (DSE) to evaluate reversibility because LVEF slightly decreased despite decrease of LVDD. During dobutamine infusion, both LVDD and LVSD decreased along with increase of LVEF according to dose escalation. From 1 to 2 months, LVEF slightly increased with decrease of LVDD and LVSD. Afterwards, LVEF was normalized mainly with decrease of LVSD, and LVEF was completely normalized at 1 year and 5 month after initiation of treatment. Initial increase of LVEF might reflect decrease of LVSD by relief of volume overload rather than improving LV contractility. Based on this observation of serial change of chambers and LVEF, we speculate that increased LV wall tension, which is induced by increase of preload as a compensating mechanism for increasing stroke volume, might aggravate LVEF in later stage of heart failure with reduced EF. The sequence of normalization in chamber size was IVC, and then LA, and then LVDD. Transmitral flow as an indicator of diastolic dysfunction changed from restrictive (transiently existed only for 1 week) to abnormal relaxation pattern (no change since that time). PVF pattern showed S/D ratio &lt; 1 until 1 week, and then triphasic pattern at 1 month, finally biphasic pattern at 8 month after initiation of medications. We observed a serial change of echocardiographic findings in patient with alcoholic CM, which might provide an insightful information to understand reverse of LV or LA remodeling associated with hemodynamic parameters, and DSE might be helpful to evaluate reversibility of LV systolic function and convince patients who are reluctant to medications.

Changes in FGF-23, Neutrophil/Platelet Activation Markers, and Angiogenin in Advanced Chronic Kidney Disease and Their Effect on Arterial Stiffness

AIMS

The aims of this study were to measure changes in fibroblast growth factor 23 (FGF-23), neutrophil (elastase, lactoferrin)/platelet activation marker (mean platelet volume-to-platelet count ratio [MPR]), and angiogenin according to the stage of chronic kidney disease (CKD), and to evaluate the association of FGF-23, elastase, lactoferrin, MPR, and angiogenin with arterial stiffness using brachial-ankle pulse wave velocity (ba-PWV) in CKD patients.

METHODS

According to the estimated glomerular filtration rate (eGFR) calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the patients were allocated to five groups: (1) normal controls (eGFR ≥90 mL/min/1.73 m2 without pathologic, urine [proteinuria], blood [electrolyte], and imaging abnormalities; n = 22); (2) CKD stage 2 (eGFR 60-89 mL/min/1.73 m2; n = 17); (3) CKD stage 3 (eGFR 30-59 mL/min/1.73 m2; n = 22); (4) CKD stage 4 (eGFR 15-30 mL/min/1.73 m2; n = 17); and (5) CKD stage 5-hemodialysis (HD) (n = 30). All the patients were free of clinically apparent cardiovascular disease. Serum FGF-23, elastase, lactoferrin, and angiogenin concentrations and the MPR were measured to study the association of the above parameters with the clinical (age, sex, presence of diabetes mellitus, and blood pressure), biochemical (calcium, phosphorus, uric acid, intact parathyroid hormone [PTH], low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein), and ba-PWV values of the CKD patients.

RESULTS

(1) The mean ba-PWV values were 1,497.2 ± 206.4 cm/s in the controls, 1,649.0 ± 247.9 cm/s in the CKD stage 2 group (p < 0.05 vs. controls), 1,655.8 ± 260.3 cm/s in the CKD stage 3 group (p < 0.05 vs. controls), 1,823.0 ± 402.4 cm/s in the CKD stage 4 group (p < 0.05 vs. controls and CKD stages 2 and 3), and 1,905.2 ± 374.1 cm/s in the CKD stage 5-HD group (p < 0.05 vs. controls and CKD stage 2). (2) The mean log10(FGF-23) concentration values were 0.77 ± 0.27, 0.97 ± 0.48, 1.10 ± 0.35 (p < 0.05 vs. controls and CKD stage 2), 1.35 ± 0.48 (p < 0.05 vs. controls and CKD stages 2 and 3), and 2.12 ± 0.82 (p < 0.05 vs. controls and CKD stages 2-4); the mean angiogenin levels were 230.6 ± 70.5 pg/mL, 283.0 ± 53.5 pg/mL (p < 0.05 vs. controls), 347.3 ± 76.9 pg/mL (p < 0.05 vs. controls and CKD stage 2), 445.9 ± 90.6 pg/mL (p < 0.05 vs. controls and CKD stages 2 and 3), and 370.9 ± 142.4 pg/mL (p < 0.05 vs. controls and CKD stages 2 and 3). (3) In the stage 3-4 CKD/HD patients, the mean elastase-to-neutrophil and lactoferrin-to-neutrophil ratios were significantly lower than in the controls and the stage 2 CKD patients. (4) Our multivariate linear regression analyses showed that age, pulse pressure, mean arterial pressure, PTH, and FGF-23 were independently associated with ba-PWV values.

CONCLUSIONS

Circulating FGF-23 and angiogenin concentrations gradually increased as CKD advanced, whereas neutrophil activation markers were significantly lower in the stage 3-4 CKD/HD patients than in the controls and stage 2 CKD patients. FGF-23 was weakly associated with ba-PWV values in patients with CKD/HD and no previous cardiovascular disease.

Chronic kidney disease in neurogenic bladder

AIM

It was believed that neurogenic bladder (NB) might be a risk factor of chronic kidney disease (CKD). However, data are limited regarding the real incidence or risk of CKD in NB. In addition, serum creatinine (sCr), a classical marker of renal function, is not reliable in NB patients because they present muscle wasting due to disuse or denervation. The aim of the study was to estimate the prevalence of CKD in NB patients using serum Cystatin-C. Secondly, we aimed to identify the risk factors for CKD development in NB.

METHODS

This was a cross-sectional study in a public hospital, a specialized center for patients who were victims of industrial accidents. Serum Cystatin-C was checked at the regular laboratory test in the structured NB programme of the hospital, and 313 patients were included in the study.

RESULTS

The overall prevalence of CKD, defined as estimated glomerular filtration rate (eGFR) <60/mL per 1.73m² was 8.0% and 22.4%, by sCr-based and Cystain-C-based eGFR, respectively, and was greater than age-matched general population in Korea. sCr was not able to detect the early deterioration of renal function in NB patients. Co-morbid diabetes, small bladder volume, recurrent urinary tract infection, and proteinuria were significantly associated with CKD in the multivariable analysis.

CONCLUSION

Chronic kidney disease prevalence was more than three times higher in NB patients than in the general population despite recent progress in the medical care of NB. Co-morbid diabetes, small bladder volume, recurrent urinary tract infection, and proteinuria seem to be the risk factors for CKD development in NB.

A calpain inhibitor protects against fractalkine production in lipopolysaccharide-treated endothelial cells

Background

Fractalkine (CX3CL1) is a chemokine with a unique CX3C motif and is produced by endothelial cells stimulated with lipopolysaccharide (LPS), tumor necrosis factor (TNF)-α, interleukin (IL)-1, and interferon-γ. There have been several reports that the caspase/calpain system is activated in endotoxemia, which leads to cellular apoptosis and acute inflammatory processes. We aimed to determine the role of the caspase/calpain system in cell viability and regulation of fractalkine production in LPS-treated endothelial cells.

Methods

Human umbilical vein endothelial cells (HUVECs) were stimulated with 0.01–100 μg/mL of LPS to determine cell viability. The changes of CX3CL1 expression were compared in control, LPS (1 μg/mL)-, IL-1α (1 μg/mL)-, and IL-1β (1 μg/mL)-treated HUVECs. Cell viability and CX3CL1 production were compared with 50 μM of inhibitors of caspase-1, caspase-3, caspase-9, and calpain in LPS-treated HUVECs.

Results

Cell viability was significantly decreased from 1 to 100 μg/mL of LPS. Cell viability was significantly restored with inhibitors of caspase-1, caspase-3, caspase-9, and calpain in LPS-treated HUVECs. The expression of CX3CL1 was highest in IL-1β-treated HUVECs. CX3CL1 production was highly inhibited with a calpain inhibitor and significantly decreased with the individual inhibitors of caspase-1, caspase-3, and caspase-9.

Conclusion

The caspase/calpain system is an important modulator of cell viability and CX3CL1 production in LPS-treated endothelial cells.

Systematic Review of Treatment for Trapped Thrombus in Patent Foramen Ovale

Background and Objectives

Trapped thrombus in patent foramen ovale (PFO) is a rare complication of pulmonary embolism that may lead to tragic clinical events. The aim of this study was to identify the optimal treatment for different clinical situations in patients with trapped thrombus in a PFO by conducting a literature review.

Subjects and Methods

A PubMed database search was conducted from 1991 through 2015, and 194 patients (185 articles) with trapped thrombus in a PFO were identified. Patient characteristics, paradoxical embolic events, and factors affecting 60-day mortality were analyzed retrospectively.

Results

Among all patients, 112 (57.7%) were treated with surgery, 28 with thrombolysis, and 54 with anticoagulation alone. Dyspnea (79.4%), chest pain (33.0%), and syncope (17.5%) were the most common presenting symptoms. Pretreatment embolism was found in 37.6% of cases, and stroke (24.7%) was the most common event. Surgery was associated with fewer post-treatment embolic events than were other treatment options (p=0.044). In the multivariate analysis, initial shock or arrest, and thrombolysis were independent predictors of 60-day mortality. Thrombolysis was related with higher 60-day mortality compared with surgery in patients who had no initial shock or arrest.

Conclusion

This systematic review showed that surgery was associated with a lower overall incidence of post-treatment embolic events and a lower 60-day mortality in patients with trapped thrombus in a PFO. In patients without initial shock or arrest, thrombolysis was related with a higher 60-day mortality compared with surgery.

Use of supplemental anti-HBc testing of donors showing non-discriminating reactive results in multiplex nucleic acid testing

BACKGROUND AND OBJECTIVES

The Korean Red Cross began nucleic acid amplification testing (NAT) for HIV and HCV in February 2005, and added HBV NAT beginning in June 2012. The current NAT system utilizes a multiplex assay for simultaneous detection of HBV DNA, HCV RNA and HIV-1 RNA. For samples that are reactive in the multiplex assay, we do specific tests for each virus. However, there have been cases of non-discriminated reactive (NDR) results which appear to be the result of non-specific reactions or cross-contamination, although some cases are considered to arise from the presence of low levels of HBV DNA due to occult hepatitis B infection.

MATERIALS AND METHODS

We examined the incidence of NDR results in previous donations of some NAT-reactive donors. Additionally, for those donors with NDR results, we performed an HBV core antibody (anti-HBc) assay.

RESULTS

From November 2015 to March 2016, there were 408 NAT-reactive donors. Of these, nineteen HBV NAT-reactive donors showed a history of NDR results in the past donations. Seven donors showed NDR results more than once. Of 771 NDR donors, 362 (47·0%) were anti-HBc reactive.

CONCLUSION

The NDR donors had a substantially higher rate of anti-HBc reactivity than other blood donors indicating that some with anti-HBc reactivity represent donors with occult HBV. Therefore, the incorporation of an anti-HBc testing for NDR donors could improve blood safety testing for the Korean Red Cross.

Which dialysis unit blood pressure is the most accurate for predicting home blood pressure in patients undergoing hemodialysis?

BACKGROUND/AIMS

We investigated which dialysis unit blood pressure (BP) is the most useful for predicting home BP in patients undergoing hemodialysis (HD).

METHODS

Patients undergoing HD who had been treated > 3 months were included in this study. Exclusion criteria were hospitalized patients with acute illness and changes in dry weight and anti-hypertensive drugs 2 weeks before the study. We used the dialysis unit BP recording data, such as pre-HD, intra-HD, post-HD, mean pre-HD, and post-HD (pre-post-HD), mean pre-HD, intra-HD, and post-HD (pre-intra-post-HD) BP. Home BP (the same period of dialysis unit BP) was monitored as a reference method during 2 weeks using the same automatic oscillometric device. Patients were asked to record their BP three times daily (wake up, between noon and 6:00 PM, and at bedtime).

RESULTS

Significant differences were detected between home systolic blood pressure (SBP) and pre-HD, post-HD, and intra-HD SBP (p = 0.003, p = 0.001, p = 0.016, respectively). In contrast, no differences were observed between home SBP and pre-intra-post-HD and pre-post-HD SBP (p = 0.235, p = 0.307, respectively). Areas under the receiver operating characteristic curve for pre-intra-post-HD and prepost-HD SBP with 2-week home BP as the reference standard were 0.812 and 0.801, respectively.

CONCLUSIONS

These results suggest that pre-intra-post-HD and pre-post-HD SBP had similar accuracy for predicting mean 2-week home SBP in HD patients. Therefore, pre-intra-post-HD and pre-post-HD SBP should be useful for predicting home SBP in HD patients if ambulatory or home BP measurements are unavailable.

Increased expression of bitter taste receptors in human allergic nasal mucosa and their contribution to the shrinkage of human nasal mucosa

OBJECTIVE

Bitter taste receptors (TAS2Rs) are expressed in the extraoral tissues, where they possess various physiological functions. This study is to characterize TAS2Rs expression in normal and allergic nasal mucosa and analyse nasal symptom after challenge with bitter tastes to evaluate their pathophysiological function in normal and allergic nasal mucosa.

METHODS

The expression levels of TAS2Rs (TAS2R4, 5, 7, 10, 14, 39, and 43) in nasal mucosa were investigated by real-time PCR, Western blot, and immunohistochemistry. The expression levels of TAS2Rs and Ca(2+) imaging in cultured epithelial cells were measured after stimulation with type 2 cytokines (IL-4, IL-5, and IL-13) or bitter tastes. Nasal symptoms in control subjects and allergic rhinitis patients using visual analogue score and acoustic rhinometry were evaluated before and after stimulation with bitter tastes. Vascular diameter of rat nasal septum was measured before and after treatment with bitter tastes.

RESULTS

TAS2Rs tested here were expressed in nasal mucosa where they were commonly distributed in superficial epithelium, submucosal glands, and endothelium. Their expression levels are increased in allergic nasal mucosa and up-regulated in cultured epithelial cells simulated with type 2 cytokines. After treatment with bitter tastes, intracellular Ca(2+) signalling was increased in cultured epithelial cells, and vascular constriction was found in rat nasal septum. Increased nasal patency was observed in human nasal mucosa without pain or sneezing.

CONCLUSION AND CLINICAL RELEVANCE

TAS2Rs are constitutively expressed in human nasal mucosa and their expression levels are increased in allergic nasal mucosa, where they could potentially contribute to shrinkage of normal and allergic nasal mucosa.

The source of net ultrafiltration during hemodialysis is mostly the extracellular space regardless of hydration status

Fluid shifts are common in patients undergoing chronic hemodialysis (HD) during the intradialytic periods, as several liters of fluid are removed during ultrafiltration (UF). Some patients have experienced frequent intradialytic hypotension (IDH). However, the characteristics of fluid shifts and which fluid space is affected remain controversial. Therefore, we designed this study to evaluate the fluid spaces most affected by UF and to determine whether hydration status influences the fluid shifts during HD. This was a prospective cohort study of 40 patients undergoing HD. We measured the patient's fluid spaces using a whole-body bioimpedance apparatus to evaluate the changes in the fluid spaces before HD and 1-4 hours of HD and 30 minutes after HD. UF achieved during HD by the 40 patients (age, 60.0 ± 5.2 years; 50% men; 50% of patients with diabetes; body weight, 61.3 ± 10.5 kg) was 2.18 ± 0.78 L (measured fluid overload, 2.15 ± 1.24 L). 1) Mean relative reduction of total body water and extracellular water was reduced from the start to the end of HD. 2) However, mean relative reduction of intracellular water was not reduced from the start to the end of HD. 3) No significant differences in fluid shifts were observed according to hydration status. The source of net UF during HD is mostly the extracellular space regardless of hydration status. Thus, IDH may be related to differences in the interstitial fluid shift to the vascular space.

Aqueous outflow: segmental and distal flow

The elevated intraocular pressure (IOP) of primary open-angle glaucoma is caused by impaired outflow of aqueous humor through the trabecular meshwork. Within the juxtacanalicular region, alterations of both extracellular matrix homeostasis and the cellular tone of trabecular meshwork endothelial and the inner wall of Schlemm canal cells affect outflow. Newer pharmacologic agents that target trabecular meshwork and Schlemm canal cell cytoskeleton lower IOP. Aqueous drainage occurs nonhomogenously with greater flow going through certain portions of the TM and less going through other portions-a concept known as segmental flow, which is theoretically the result of outflow being dependent on the presence of discrete pores within Schlemm canal. The limited long-term success of trabecular meshwork bypass surgeries implicates the potential impact of resistance in Schlemm canal itself and collector channels. Additionally, others have observed that outflow occurs preferentially near collector channels. These distal structures may be more important to aqueous outflow than previously believed.

FINANCIAL DISCLOSURE

Dr. Rhee is a consultant to Aerie Pharmaceuticals, Alcon Laboratories, Inc., Allegan, Inc., Aquesys, Inc., Glaukos Corp., Ivantis, Inc., Johnson & Johnson, Merck Sharp & Dohme Corp. and Santen, Inc., and has received research funding from Alcon Laboratories, Inc., Merck Sharp & Dohme Corp., and Ivantis, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Spontaneous rupture of a renal artery pseudoaneurysm in a previously hypertensive patient

Previously, renal artery pseudoaneurysms were thought to be extremely uncommon. However, these lesions are now being detected more frequently as incidental findings on computed tomography, magnetic resonance imaging, and the extensive use of angiography. The incidence of ruptured renal artery pseudoaneurysms is very low. We report a case of a giant renal artery pseudoaneurysm (9.4-cm diameter) with severe left flank pain and a syncopal attack in a young woman who did not control high blood pressure for a couple of years.

Canonical wnt signaling regulates extracellular matrix expression in the trabecular meshwork

PURPOSE

Canonical Wnt signaling has emerged as a critical regulator of aqueous outflow facility and intraocular pressure (IOP). In this study, we examine the role of canonical Wnt signaling on extracellular matrix (ECM) expression in the trabecular meshwork (TM) and explore the molecular mechanisms involved.

METHODS

β-catenin localization in human TM tissue was examined using immunofluorescent staining. Primary human TM cells were incubated with lithium chloride (LiCl) and the effect on active β-catenin expression was assessed by immunoblot. Adenovirus expressing a dominant-negative TCF4 mutant that lacks a β-catenin binding domain was used. Changes in the levels of the microRNA-29 (miR-29) family and ECM proteins were determined by real-time quantitative PCR and immunoblot analysis, respectively.

RESULTS

β-catenin was expressed throughout the TM, with localization primarily to the plasma membrane. Incubation of TM cells with lithium chloride increased the expression of active β-catenin. Lithium chloride treatment upregulated miR-29b expression, and suppressed the levels of various ECM proteins under both basal and TGF-β2 stimulatory conditions. Infection of TM cells with a dominant-negative TCF4 mutant induced ECM levels without a significant change in the expression of the miR-29 family.

CONCLUSIONS

Collectively, our data identify the canonical Wnt signaling pathway as an important modulator of ECM expression in the TM and provide a mechanistic framework for its regulation of outflow facility and IOP.

TGF-β2-mediated ocular hypertension is attenuated in SPARC-null mice

PURPOSE

Transforming growth factor-β2 (TGF-β2) has been implicated in the pathogenesis of primary open-angle glaucoma through extracellular matrix (ECM) alteration among various mechanisms. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that regulates ECM within the trabecular meshwork (TM), and is highly upregulated by TGF-β2. We hypothesized that, in vivo, SPARC is a critical regulatory node in TGF-β2-mediated ocular hypertension.

METHODS

Empty (Ad.empty) or TGF-β2-containing adenovirus (Ad.TGF-β2) was injected intravitreally into C57BL6-SV129 WT and SPARC-null mice. An initial study was performed to identify a stable period for IOP measurement under isoflurane. The IOP was measured before injection and every other day for two weeks using rebound tonometry. Additional mice were euthanized at peak IOP for immunohistochemistry.

RESULTS

The IOP was stable under isoflurane during minutes 5 to 8. The IOP was significantly elevated in Ad.TGF-β2-injected (n = 8) versus Ad.empty-injected WT (n = 8) mice and contralateral uninjected eyes during days 4 to 11 (P < 0.03). The IOPs were not significantly elevated in Ad.TGF-β2-injected versus Ad.empty-injected SPARC-null mice. However, on day 8, the IOP of Ad.TGF-β2-injected SPARC-null eyes was elevated compared to that of contralateral uninjected eyes (P = 0.0385). Immunohistochemistry demonstrated that TGF-β2 stimulated increases in collagen IV, fibronectin, plasminogen activator inhibitor-1 (PAI-1), connective tissue growth factor (CTGF), and SPARC in WT mice, but only PAI-1 and CTGF in SPARC-null mice (P < 0.05).

CONCLUSIONS

SPARC is essential to the regulation of TGF-β2-mediated ocular hypertension. Deletion of SPARC significantly attenuates the effects of TGF-β2 by restricting collagen IV and fibronectin expression. These data provide further evidence that SPARC may have an important role in IOP regulation and possibly glaucoma pathogenesis.

AMP-activated protein kinase regulates intraocular pressure, extracellular matrix, and cytoskeleton in trabecular meshwork

PURPOSE

In this study, we investigate how adenosine monophosphate-activated protein kinase (AMPK) affects extracellular matrix (ECM) and cellular tone in the trabecular meshwork (TM), and examine how deletion of its catalytic α2 subunit affects IOP and aqueous humor clearance in mice.

METHODS

Human TM tissue was examined for expression of AMPKα1 and AMPKα2, genomically distinct isoforms of the AMPK catalytic subunit. Primary cultured human TM cells were treated for 24 hours with the AMPK activator 5-amino-1-β-Dffff-ribofuranosyl-imidazole-4-carboxamide (AICAR), under basal or TGF-β2 stimulatory conditions. Conditioned media (CM) was probed for secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1 (TSP-1), and ECM proteins, and cells were stained for F-actin. Cells underwent adenoviral infection with a dominant negative AMPKα subunit (ad.DN.AMPKα) and were similarly analyzed. Intraocular pressure, central corneal thickness (CCT), and aqueous clearance were measured in AMPKα2-null and wild-type (WT) mice.

RESULTS

Both AMPKα1 and AMPKα2 are expressed in TM. AICAR activated AMPKα and suppressed the expression of various ECM proteins under basal and TGF-β2 stimulatory conditions. AICAR decreased F-actin staining and increased the phospho-total RhoA ratio (Ser188). Transforming growth factor-β2 transiently dephosphorylated AMPKα. Infection with ad.DN.AMPKα upregulated various ECM proteins, decreased the phospho-total RhoA ratio, and increased F-actin staining. AMPKα2-null mice exhibited 6% higher IOP and decreased aqueous clearance compared with WT mice, without significant differences in CCT or angle morphology.

CONCLUSIONS

Collectively, our data identify AMPK as a critical regulator of ECM homeostasis and cytoskeletal arrangement in the TM. Mice that are AMPKα2-null exhibit higher IOPs and decreased aqueous clearance than their WT counterparts.

Pharmacological regulation of SPARC by lovastatin in human trabecular meshwork cells

PURPOSE

Statins have been shown to increase aqueous outflow facility. The matricellular protein SPARC (secreted protein acidic and rich in cysteine) is a critical mediator of aqueous outflow and intraocular pressure (IOP). Here, we examine the effects of lovastatin on SPARC expression in trabecular meshwork (TM) cells, exploring the molecular mechanisms involved.

METHODS

Primary cultured human TM cells were incubated for 24, 48, and 72 hours with 10 μM lovastatin. In separate cultures, media was supplemented with either farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP) for the duration of the 72-hour time point experiment. Trabecular meshwork cells were also pretreated for 24 hours with lovastatin followed by 24-hour stimulation with 3 ng/mL TGF-β2. Cell lysates and media were harvested and relative mRNA and protein level changes were determined. Krüppel-like factor 4 (KLF4) localization in normal human anterior segments was examined by immunofluorescence. Adenovirus expressing human KLF4 was used and relative changes in SPARC mRNA and protein levels were assessed.

RESULTS

Incubating TM cells with lovastatin suppressed SPARC mRNA and protein levels. This effect was reversed upon media supplementation with GGPP but not FPP. Pretreating cells with lovastatin inhibited TGF-β2 induction of SPARC. The KLF4 transcription factor was expressed throughout the TM and the inner and outer walls of Schlemm's canal. Lovastatin treatment upregulated KLF4 mRNA and protein levels. Overexpression of KLF4 downregulated SPARC expression.

CONCLUSIONS

Collectively, our data identify lovastatin as an important pharmacological suppressor of SPARC expression in TM cells, and provide further insight into the molecular mechanisms mediating statin enhancement of aqueous outflow facility.

Profile of human β-defensins 1,2 and proinflammatory cytokines (TNF-α, IL-6) in patients with chronic kidney disease

BACKGROUND/AIM

Our aim was to determine whether altered human β-defensin (HBD), pro-inflammatory cytokines including interleukin (IL)-6 and tumor necrotic factor (TNF)-α could increase the risk of developing and exacerbation of chronic kidney disease (CKD), especially for patients with diabetic nephropathy (DN).

METHODS

Serum samples were obtained from 338 CKD patients and 88 sex, age-matched healthy controls. The concentrations of HBD-1 were assayed using an RIA kit. Serum levels of HBD-2, IL-6 and TNF-α were assayed using an ELISA kit.

RESULTS

Serum levels of HBD-1, IL-6 and TNF-α were significantly higher in CKD patients compared to healthy controls (P<0.05). HBD-1 levels were inversely related to estimated glomerular filtration rate (eGFR), which was the coefficient factor (β = -0.357, P = 0.035) explaining the variability in HBD-1 in CKD. Diabetic nephropathy (DN) patients at stage 3-5 had significantly higher serum HBD-1 levels than non DN patients (P=0.00).

CONCLUSION

Our data support the view that there is increased inflammation in CKD and DN. The inverse correlation between eGFR and serum HBD-1 which we observed is suggestive of a relationship between innate immunity and renal function and should be further investigated.

The effects of tenascin C knockdown on trabecular meshwork outflow resistance

PURPOSE

Tenascin C (TNC) is a matricellular glycoprotein whose expression in adult tissue is indicative of tissue remodeling. The purpose of the current study was to determine the localization of TNC in trabecular meshwork (TM) tissue and to analyze the effects of TNC on intraocular pressure (IOP).

METHODS

Human TM frontal sections were immunostained with anti-TNC and imaged by confocal microscopy. TNC mRNA and protein levels were quantitated in anterior segments perfused at physiological and elevated pressure. Short, hairpin RNA (shRNA) silencing lentivirus targeting full-length TNC (shTNC) was applied to anterior segment perfusion organ cultures. The IOPs and central corneal thickness (CCT) of wild-type, TNC(-/-), and tenascin X (TNX(-/-)) knockout mice were measured.

RESULTS

TNC was distributed in the juxtacanalicular (JCT) region of adult human TM, predominantly in the basement membrane underlying the inner wall of Schlemm's canal. Application of shTNC lentivirus to human and porcine anterior segments in perfusion culture did not significantly affect outflow rate. Although TNC was upregulated in response to pressure, there was no difference in outflow rate when shTNC-silenced anterior segments were subjected to elevated pressure. Furthermore, IOPs and CCTs were not significantly different between TNC(-/-) or TNX(-/-) and wild-type mice.

CONCLUSIONS

TNC does not appear to contribute directly to outflow resistance. However, TNC immunolocalization in the JCT of adult human eyes suggests that certain areas of the TM are being continuously remodeled with or without an IOP increase.

Central corneal thickness does not correlate with TonoLab-measured IOP in several mouse strains with single transgenic mutations of matricellular proteins

Accurate and reliable measurement of intraocular pressure (IOP) is crucial in the study of glaucoma using the mouse model. The purpose of this study was to determine the relationship between TonoLab-measured IOP and central corneal thickness (CCT) in mouse strains with single gene mutations of matricellular proteins. Wild-type (WT) and transgenic mouse strains with single gene mutations (KO) of thrombospondin-1 (TSP-1), thrombospondin-2 (TSP-2), osteopontin (OPN), hevin, and secreted protein acidic rich in cysteine (SPARC) were imaged at six weeks using optical coherence tomography (Stratus, Zeiss) to determine CCT. IOP was measured between 11am and 3pm using TonoLab, one week later. For all measurements, mice were anesthetized using intraperitoneal injection ketamine:xylazine. CCT and IOP were measured in 583 mice (TSP-1 n = 71 and 41, TSP-2 n = 60 and 32, OPN n = 81 and 50, hevin n = 59 and 76, SPARC n = 54 and 59, WT and KO, respectively). Mean CCT was 5-6% lower in three KO strains-TSP-1, OPN, and SPARC-compared to their corresponding WT (p = 1.55 × 10(-7), 1.63 × 10(-11), and 1.91 × 10(-7), respectively). The mean IOP was 8.3%, 6.6%, and 15.1% lower in three KO strains-TSP-1, TSP-2, and SPARC-compared to corresponding WT (p = 2.11 × 10(-5), 2.93 × 10(-3), and 3.76 × 10(-9), respectively. Linear regression of IOP versus CCT yielded no statistically significant within-strain correlations for TSP-1 (p = 0.12 and 0.073), TSP-2 (p = 0.473 and 0.92), OPN (p = 0.212 and 0.916), Hevin (p = 0.746 and 0.257), and SPARC (p = 0.080 and 0.056), reported as p-values considering a null hypothesis of zero slope (WT and KO, respectively). Neither C57-derived strains (TSP-1 and OPN) nor 129-derived strains (TSP-2, hevin, SPARC) demonstrated a correlation between mean IOP and mean CCT across different strains (p = 0.75 and p = 0.53, respectively). Taken together, these results indicate that CCT is not required to interpret TonoLab IOP readings in the mice when CCT varies 10% about the mean. This does not exclude the possibility of an IOP-CCT correlation for CCT values outside this range or for inter-strain comparisons where the mean CCT differs more than 10%.

Overexpression of SPARC in human trabecular meshwork increases intraocular pressure and alters extracellular matrix

PURPOSE

Intraocular pressure (IOP) regulation is largely unknown. SPARC-null mice demonstrate a lower IOP resulting from increased outflow. SPARC is a matricellular protein often associated with fibrosis. We hypothesized that SPARC overexpression would alter IOP by affecting extracellular matrix (ECM) synthesis and/or turnover in the trabecular meshwork (TM).

METHODS

An adenoviral vector containing human SPARC was used to increase SPARC expression in human TM endothelial cells and perfused human anterior segments using multiplicities of infection (MOIs) 25 or 50. Total RNA from TM was used for quantitative PCR, while protein from cell lysates and conditioned media were used for immunoblot analyses and zymography. After completion of perfusion, the anterior segments were fixed, sectioned, and examined by light and confocal microscopy.

RESULTS

SPARC overexpression increased the IOP of perfused human anterior segments. Fibronectin and collagens IV and I protein levels were elevated in both TM cell cultures and within the juxtacanalicular (JCT) region of perfused anterior segments. Collagen VI and laminin protein levels were increased in TM cell cultures but not in perfused anterior segments. The protein levels of pro-MMP-9 decreased while the kinetic inhibitors of metalloproteinases, TIMP-1 and PAI-1 protein levels, increased at MOI 25. At MOI 50, the protein levels of pro-MMP-1, -3, and -9 also decreased while PAI-1 and TIMP-1 and -3 increased. Only MMP-9 activity was decreased on zymography. mRNA levels of the collagens, fibronectin, and laminin were not affected by SPARC overexpression.

CONCLUSIONS

SPARC overexpression increases IOP in perfused cadaveric human anterior segments resulting from a qualitative change the JCT ECM. Selective decrease of MMP-9 activity is likely part of the mechanism. SPARC is a regulatory node for IOP.

Regulation of SPARC by transforming growth factor β2 in human trabecular meshwork

PURPOSE

An increased aqueous level of TGF-β2 has been found in many primary open-angle glaucoma patients. Secreted Protein, Acidic, and Rich in Cysteine (SPARC)-null mice have a lower intraocular pressure. The mechanistic relationship between SPARC and TGF-β2 in trabecular meshwork (TM) is unknown. We hypothesized that TGF-β2 upregulates SPARC expression in TM.

METHODS

Cultured TM cells were incubated with selective inhibitors for p38 MAP kinase (p38), Smad3, p42, JNK, RhoA, PI3K, or TGF-β2 receptor for 2 hours, and then TGF-β2 was added for 24 hours in serum-free media. Quantitative polymerase chain reaction (qPCR) and immunoblot analysis were performed. Immunofluorescent microscopy was used to determine nuclear translocation of signaling proteins. Ad5.hSPARC and Lentiviral shRNA for p38 and Smad3 were constructed, and infected human TM cells.

RESULTS

SPARC was upregulated by TGF-β2 in the human TM cells (3.8 ± 1.7-fold, n = 6, P = 0.01 for protein and 7.1 ± 3.7-fold, n = 6, P = 0.01 for mRNA), while upregulation of SPARC had no effect on TGF-β2. TGF-β2-induced SPARC expression was suppressed by inhibitors against p38 (-40.3 ± 20.9%, n = 10, P = 0.0001), Smad3 (-56.2 ± 18.9%, n = 10, P = 0.0001), JNK (-49.1 ± 24.6%, n = 10, P = 0.0001), and TGF-β2 receptor (-83.6 ± 14.4%, n = 6, P = 0.003). Phosphorylation and translocation of Smad3, p38, and MAPKAPK2 were detected at 30 minutes and 1 hour, respectively, following TGF-β2 treatment. Phosphorylation of JNK and c-jun was detected before TGF-β2 treatment. SPARC was suppressed 31 ± 13% (n = 5, P < 0.0001) by shRNA-p38 and 41 ± 3% (n = 5, P < 0.0001) by shRNA-Smad3.

CONCLUSIONS

TGF-β2 upregulates SPARC expression in human TM through Smad-dependent (Smad2/3) or -independent (p38) signaling pathways. SPARC may be a downstream regulatory node of TGF-β2-mediated IOP elevation.

Secreted protein acidic and rich in cysteine (SPARC)-null mice exhibit more uniform outflow

PURPOSE

Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein known to regulate extracellular matrix (ECM) in many tissues and is highly expressed in trabecular meshwork (TM). SPARC-null mice have a 15% to 20% decrease in intraocular pressure (IOP) compared to wild-type (WT) mice. We hypothesized that mouse aqueous outflow is segmental, and that transgenic deletion of SPARC causes a more uniform pattern that correlates with IOP and TM morphology.

METHODS

Eyes of C57BL6-SV129 WT and SPARC-null mice were injected with fluorescent microbeads, which were also passively exposed to freshly enucleated eyes. Confocal and electron microscopy were performed. Percentage effective filtration length (PEFL) was calculated as PEFL = FL/TL × 100%, where TL = total length and FL = filtration length. IOP was measured by rebound tonometry.

RESULTS

Passive microbead affinity for WT and SPARC-null ECM did not differ. Segmental flow was observed in the mouse eye. SPARC-null mice had a 23% decrease in IOP. PEFL increased in SPARC-null (70.61 ± 11.36%) versus WT mice (54.68 ± 9.95%, P < 0.005; n = 11 pairs), and PEFL and IOP were negatively correlated (R(2) = 0.72, n = 10 pairs). Morphologically, TM of high-tracer regions had increased separation between beams compared to low-tracer regions. Collagen fibril diameter decreased in SPARC-null (28.272 nm) versus WT tissue (34.961 nm, P < 0.0005; n = 3 pairs).

CONCLUSIONS

Aqueous outflow in mice is segmental. SPARC-null mice demonstrated a more uniform outflow pattern and decreased collagen fibril diameter. Areas of high flow had less compact juxtacanalicular connective tissue ECM, and IOP was inversely correlated with PEFL. Our data show a correlation between morphology, aqueous outflow, and IOP, indicating a modulatory role of SPARC in IOP regulation.

Thrombospondin-1 (TSP1)-null and TSP2-null mice exhibit lower intraocular pressures

PURPOSE

Thrombospondin-1 (TSP1) and TSP2 are matricellular proteins that have been shown to regulate cytoskeleton, cell adhesion, and extracellular matrix remodeling. Both TSP1 and TSP2 are found in the trabecular meshwork (TM). In cadaver eyes with primary open-angle glaucoma (POAG), TSP1 is increased in one third of patients. We hypothesized that TSP1 and TSP2 participate in the regulation of intraocular pressure (IOP). Methods. IOPs of TSP1-null, TSP2-null mice, and their corresponding wild-type (WT) mice were measured using a commercial rebound tonometer. Fluorophotometric measurements assessed aqueous turnover. Central corneal thickness (CCT) was measured by optical coherence tomography. Iridocorneal angles were examined using light microscopy (LM), immunofluorescence (IF), and transmission electron microscopy (TEM).

RESULTS

Average IOPs of TSP1-null and TSP2-null mice were 10% and 7% less than that of the corresponding WT mice, respectively. CCTs were 6.5% less in TSP1-null mice (P < 0.05) and 1.1% less in TSP2-null mice (P > 0.05). Fluorophotometric measurements suggest that aqueous turnover rates in TSP1-null and TSP2-null mice are greater than those of WT mice. LM of the TSP1-null and TSP2-null iridocorneal angles reveals morphology, which is indistinguishable from that of their corresponding WTs. IF revealed possible concurrent underexpression of TSP2 in TSP1-null mice and of TSP1 in TSP2-null mice. TEM revealed larger collagen fibril diameters in TSP1-null and TSP2-null mice compared with WTs.

CONCLUSIONS

TSP1-null and TSP2-null mice have lower IOPs than their WT counterparts. The rate of aqueous turnover suggests that the mechanism is enhanced outflow facility. An alteration in the extracellular matrix may contribute to this finding.