Fibronectin fragment inhibits xylosyltransferase-1 expression by regulating Sp1/Sp3- dependent transcription in articular chondrocytes

OBJECTIVE

We investigated the effects of 29-kDa amino-terminal fibronectin fragment (29-kDa FN-f) on xylosyltransferase-1 (XT-1), an essential anabolic enzyme that catalyzes the initial and rate-determining step in glycosaminoglycan chain synthesis, in human primary chondrocytes.

METHODS

Proteoglycan and XT-1 expression in cartilage tissue was analyzed using safranin O staining and immunohistochemistry. The effects of 29-kDa FN-f on XT-1 expression and its relevant signaling pathway were analyzed by quantitative real-time-PCR, immunoblotting, chromatin immunoprecipitation, and immunoprecipitation assays. The receptors for 29-kDa FN-f were investigated using small interference RNA and blocking antibodies.

RESULTS

The expression of XT-1 was significantly lower in human osteoarthritis cartilage than in normal cartilage. Intra-articular injection of 29-kDa FN-f reduced proteoglycan levels and XT-1 expression in murine cartilage. In addition, in 29-kDa FN-f-treated cells, XT-1 expression was significantly suppressed at both the mRNA and protein levels, modulated by the transcription factors specificity protein 1 (Sp1), Sp3, and activator protein 1 (AP-1). The 29-kDa FN-f suppressed the binding of Sp1 to the promoter region of XT-1 and enhanced the binding of Sp3 and AP-1. Inhibition of mitogen-activated protein kinase and nuclear factor kappa B signaling pathways restored the 29-kDa FN-f-inhibited XT-1 expression, along with the altered expression of Sp1 and Sp3. Blockading toll-like receptor 2 (TLR-2) and integrin α5β1 via siRNA and blocking antibodies revealed that the effects of 29-kDa FN-f on XT-1 expression were mediated through the TLR-2 and integrin α5β1 signaling pathways.

CONCLUSION

These results demonstrate that 29-kDa FN-f negatively affects cartilage anabolism by regulating glycosaminoglycan formation through XT-1.

Abstract P123: Plasma Endocan Level as a Predictor of Cardiovascular Composite Outcomes in Patients With End-Stage Renal Disease

Background: Endocan, a proteoglycan which is a potential biomarker of endothelial dysfunction, has been shown to be associated with increased cardiovascular risk. We investigated plasma levels of endocan in patients with end-stage renal disease (ESRD) on hemodialysis to predict the risk of cardiovascular diseases.

Methods: A total of 400 adult patients with ESRD undergoing hemodialysis were prospectively enrolled in 4 tertiary hospitals of South Korea from June 2016 to May 2018. They were observed for development of the cardiovascular composite outcomes. We compared clinical characteristics and the plasma levels of endocan between 47 patients with cardiovascular composite outcomes and 353 control patients without cardiovascular composite outcomes, and developed the predictive markers of cardiovascular diseases using Cox proportional-hazard analysis.

Results: Previous histories of diabetes, acute coronary syndrome, arrhythmia and congestive heart failure were higher in ESRD patients with the cardiovascular composite outcomes than control patients. Patients with cardiovascular composite outcomes showed lower levels of hemoglobin, albumin, and high-density lipoproteins compared with control patients. Higher level of plasma endocan and white blood cells were associated with patients with cardiovascular composite outcomes. Cox proportional-hazard analysis showed that previous histories of diabetes and plasma level endocan were significantly associated with cardiovascular composite outcomes: hazard ratios were 2.1 (95% confidential interval (CI), 1.1 to 4.3) ( p = 0.03) for diabetes and 15.4 (95% CI, 3.2 to 75.2) ( p = 0.001) for endocan (log pg/mL). The patients with level of endocan of 2.96 log pg per mL or more showed significantly higher cumulative incidence of the cardiovascular composite outcomes in Kaplan-Meier curve ( p = 0.03).

Conclusions: Plasma Endocan level can a useful biomarker for prediction of cardiovascular diseases in patients with ESRD on hemodialysis.

Vascular calcification and left ventricular hypertrophy in hemodialysis patients: interrelationship and clinical impacts

Background: We examined the relationship and combined effect of vascular calcification (VC) and left ventricular hypertrophy (LVH) on deaths and cardiovascular events (CVEs) in hemodialysis (HD) patients. Methods: Maintenance HD patients (n=341) were included. Echocardiography data and plain chest radiographs were used to assess LVH and aortic arch VC. Results: VC was found in 100 patients (29.3%). LVH was more prevalent in patients with VC compared with those without VC (70% vs. 50.2%, P=0.001). VC was independently associated with a 2.42-fold increased risk of LVH (95% CI, 1.26-4.65). In multivariate analysis, compared with patients with neither VC nor LVH, the coexistence of VC and LVH was independently associated with CVE (HR, 2.01; 95% CI, 1.09-3.72), whereas VC or LVH alone was not. Patients with both VC and LVH had the highest risk for a composite event of deaths or CVE (HR, 1.88; 95% CI, 1.15-3.06). Significant synergistic interaction was observed between VC and LVH (P for interaction=0.039). Conclusions: VC was independently associated with LVH. The coexistence of VC and LVH was associated with higher risk of deaths and CVEs than either factor alone. VC and LVH showed a synergistic interaction for the risk of deaths and CVEs.

The optimal duration of ischemic preconditioning for renal ischemia-reperfusion injury in mice

Purpose

The aim of the present study was to investigate the protective effects of ischemic preconditioning for different periods of time and to elucidate the optimal safe ischemic preconditioning time for renal ischemia-reperfusion (I/R) injury in mice.

Methods

A total of 25 male C57BL/6 mice were randomly divided into 5 groups (sham, I/R, ischemic preconditioning [IP]-3, IP-5, and IP-7 groups), in which the kidney was preconditioned with IP of various durations and then subjected to I/R injury (the last 3 groups). To induce renal ischemia, the left renal pedicle was occluded with a nontraumatic microaneurysm clamp for 30 minutes followed by reperfusion for 24 hours. The effects of IP on renal I/R injury were evaluated in terms of renal function, tubular necrosis, apoptotic cell death and inflammatory cytokines.

Results

Results indicated that BUN and creatinine (Cr) levels increased significantly in the I/R group, but the elevations were significantly lower in IP groups, especially in the IP-5 group. Histological analysis revealed that kidney injury was markedly decreased in the IP-5 group compared with the I/R group, as evidenced by reduced renal necrosis/apoptosis. In addition, IP significantly inhibited gene expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and chemokines (monocyte chemoattractant protein-1). Western blot analysis indicated that the expression levels of Toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) were upregulated in the I/R group, while expression was inhibited in the IP groups.

Conclusion

Five-minute IP had the greatest protective effect against I/R injury.

Transitional cell carcinoma involving graft kidney in a kidney transplant recipient: a case report

Background

Kidney transplantation (KT) is the treatment option for patients with end stage renal disease (ESRD) to prolong survival and improve quality of life. Although the use of potent immunosuppressive agents increases graft survival in kidney transplantation recipients (KTRs), it may lead to the development of malignancy, including transitional cell carcinoma (TCC). TCC developing in the pelvis of graft kidney is very rare in KTRs.

Case Presentation

A 40-year-old male visited hospital with complaints of nausea, vomiting and gross hematuria. Eleven years ago, he was diagnosed ESRD of unknown origin, and received a living related KT from his father 1 year later. Radiologic findings showed a huge polypoid mass in the pelvis of graft kidney with pelvo-calyceal dilation and a 3.3 cm-sized nodule in aortocaval chain and a 2.5 cm-sized nodule in right iliac chain as TCC stage IV. Sonography-guided percutaneous needle biopsy of pelvis mass in the graft kidney revealed a low grade urothelial cell carcinoma. Radical graft nephroureterectomy was performed and histopathological diagnosis confirmed as a low grade urothelial carcinoma of graft pelvis and ureter lumen, which invaded to perirenal fat and renal parenchyma with lymphovascular presence (T3Nx). The patient started with adjuvant concurrent chemo-radiation therapy and returned to regular hemodialysis.

Conclusions

We report a rare case of TCC in the pelvis of graft kidney with already advanced disease at diagnosis in a young KTR. For the early diagnosis of TCC in KTRs, exposure history to Chinese herb or analgesics should be investigated before KT and high risk population in KTRs should be tightly performed regular postoperative surveillance for TCC and considered of less calcineurin inhibitor-based immunosuppressant protocol.

Paricalcitol attenuates lipopolysaccharide-induced inflammation and apoptosis in proximal tubular cells through the prostaglandin E2 receptor EP4

Background

Vitamin D is considered to exert a protective effect on various renal diseases but its underlying molecular mechanism remains poorly understood. This study aimed to determine whether paricalcitol attenuates inflammation and apoptosis during lipopolysaccharide (LPS)-induced renal proximal tubular cell injury through the prostaglandin E₂ (PGE₂) receptor EP4.

Methods

Human renal tubular epithelial (HK-2) cells were pretreated with paricalcitol (2 ng/mL) for 1 hour and exposed to LPS (1 μg/mL). The effects of paricalcitol pretreatment in relation to an EP4 blockade using AH-23848 or EP4 small interfering RNA (siRNA) were investigated.

Results

The expression of cyclooxygenase-2, PGE₂, and EP4 were significantly increased in LPS-exposed HK-2 cells treated with paricalcitol compared with cells exposed to LPS only. Paricalcitol prevented cell death induced by LPS exposure, and the cotreatment of AH-23848 or EP4 siRNA offset these cell-protective effects. The phosphorylation and nuclear translocation of p65 nuclear factor-kappaB (NF-κB) were decreased and the phosphorylation of Akt was increased in LPS-exposed cells with paricalcitol treatment. AH-23848 or EP4 siRNA inhibited the suppressive effects of paricalcitol on p65 NF-κB nuclear translocation and the activation of Akt. The production of proinflammatory cytokines and the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells were attenuated by paricalcitol in LPS exposed HK-2 cells. The cotreatment with an EP4 antagonist abolished these anti-inflammatory and antiapoptotic effects.

Conclusion

EP4 plays a pivotal role in anti-inflammatory and antiapoptotic effects through Akt and NF-κB signaling after paricalcitol pretreatment in LPS-induced renal proximal tubule cell injury.

Gender-Specific Associations between Low Skeletal Muscle Mass and Albuminuria in the Middle-Aged and Elderly Population

Objective This study assessed gender-specific associations between low muscle mass (LMM) and albuminuria. Methods Data from the Korea National Health and Nutrition Examination Survey 2011 were employed. The study consisted of 1,087 subjects (≥50 years old). Skeletal muscle index (SMI) was defined as the weight-adjusted appendicular skeletal muscle mass. Mild LMM and severe LMM were defined as SMI that were 1-2 and >2 standard deviations below the sex-specific mean appendicular skeletal muscle mass of young adults, respectively. Increased albuminuria was defined as albumin-to-creatinine ratio ≥30mg/g Results Men with mild and severe LMM were significantly more likely to have increased albuminuria (15.2% and 45.45%, respectively) than men with normal SMI (9.86%, P<0.0001), but not women. Severe LMM associated independently with increased albuminuria in men (OR=7.661, 95% CI=2.72-21.579) but not women. Severe LMM was an independent predictor of increased albuminuria in hypertensive males (OR=11.449, 95% CI=3.037-43.156), non-diabetic males (OR=8.782, 95% CI=3.046-25.322), and males without metabolic syndrome (MetS) (OR=8.183, 95% CI=1.539-43.156). This was not observed in males without hypertension, males with diabetes or MetS, and all female subgroups. Conclusion Severe LMM associated with increased albuminuria in men, especially those with hypertension and without diabetes or MetS.

Serum 1,25-dihydroxyvitamin D Better Reflects Renal Parameters Than 25-hydoxyvitamin D in Patients with Glomerular Diseases

Background: Impaired vitamin D metabolism may contribute to the development and progression of chronic kidney disease. The purpose of this study was to determine associations of circulating vitamin D with the degree of proteinuria and estimated glomerular filtration rate (eGFR) in patients with biopsy-proven glomerular diseases. Methods: Clinical and biochemical data including blood samples for 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D) levels were collected from patients at the time of kidney biopsy. Results: Serum 25(OH)D levels were not different according to eGFR. However, renal function was significantly decreased with lower serum 1,25(OH)₂D levels (P < 0.001). The proportions of nephrotic-range proteinuria and renal dysfunction (eGFR ≤ 60 mL/min/1.73 m²) progressively increased with declining 1,25(OH)₂D but not 25(OH)D. Multivariable linear regression analysis showed that 25(OH)D was significantly correlated with serum albumin and total cholesterol (β = 0.224, P = 0.006; β = -0.263, P = 0.001) and 1,25(OH)₂D was significantly correlated with eGFR, serum albumin and phosphorus (β = 0.202, P = 0.005; β = 0.304, P < 0.001; β = -0.161, P = 0.024). In adjusted multivariable linear regression, eGFR and 24hr proteinuria were independently correlated only with 1,25(OH)₂D (β = 0.154, P = 0.018; β = -0.171, P = 0.012), but not 25(OH)D. The lower level of 1,25(OH)₂D was associated with the frequent use of immunosuppressive agents (P < 0.001). Conclusion: It is noteworthy in these results that circulating 1,25(OH)₂D may be superior to 25(OH)D as a marker of severity of glomerular diseases.

Clinical impact of coexisting retinopathy and vascular calcification on chronic kidney disease progression and cardiovascular events

BACKGROUND AND AIMS

Retinopathy and vascular calcification (VC) are representative markers of microvascular and macrovascular dysfunction in patients with chronic kidney disease (CKD). However, their relationship and combined effects on clinical outcomes remain undetermined.

METHODS AND RESULTS

We included 523 patients with nondialysis-dependent CKD stage 3-5 who had been examined with fundus photography for diabetic or hypertensive retinopathy. Simple radiographs were analyzed for the presence of VC. The clinical significance of VC of the abdominal aorta and iliofemoral artery (apVC) and retinopathy was evaluated in terms of the rate of renal function decline and composite of any cardiovascular event or death. CKD patients with retinopathy showed higher prevalence of apVC than those without retinopathy (25.6% vs. 12.5%, P < 0.001).The presence of retinopathy was independently associated with apVC (OR 2.13, 95% CI 1.31, 3.49). In multivariate analysis, compared with subjects with neither apVC nor retinopathy, the coexistence of both apVC and retinopathy were independently associated with rapid renal function decline (β = -1.51; 95% CI -2.40, -0.61), whereas apVC or retinopathy alone were not. Compared with subjects with neither apVC nor retinopathy, the HRs for composite end points were 1.05 (95% CI 0.48, 2.27), 1.79 (95% CI 1.14, 2.80), and 2.07 (95% CI 1.17, 3.67) for patients with apVC only, those with retinopathy only, and those with both apVC and retinopathy, respectively.

CONCLUSION

The coexistence of VC and retinopathy was independently associated with CKD progression and cardiovascular events or deaths, and its combined effect was stronger than any separate condition.

Comparison of Clinical Outcome Between Twice-Weekly and Thrice-Weekly Hemodialysis in Patients With Residual Kidney Function

Residual kidney function (RKF) contributes to improved survival in hemodialysis (HD) patients. However, it is not clear whether RKF allows a comparable survival rate in patients undergoing twice-weekly HD compared with thrice-weekly HD.We enrolled 685 patients from a prospective multicenter observational cohort. RKF and HD adequacy was monitored regularly over 3-year follow-up. Patients with RKF were divided into groups undergoing twice-weekly HD (n = 113) or thrice-weekly HD (n = 137). Patients without RKF undergoing thrice-weekly HD (n = 435) were included as controls. Fluid balance and dialysis-associated characteristics were followed and clinical outcomes evaluated using all-cause mortality and cardiovascular events (CVE).In patients with RKF, baseline and follow-up RKF were significantly higher in patients undergoing twice-weekly HD than in those undergoing thrice-weekly HD. Total Kt/V urea (dialysis plus residual renal) in patients with RKF undergoing twice-weekly HD was greater than or equal to those in patients with or without RKF undergoing thrice-weekly HD. Compared with patients with RKF undergoing thrice-weekly HD, patients with RKF undergoing twice-weekly HD had no fluid excess, but their normalized protein catabolic rate became lower since 24-month follow up. In multivariable analyses, patients with RKF undergoing twice-weekly HD had a noninferior risk of mortality (hazard ratio [HR], 0.83; 95% confidence interval [95% CI], 0.34-2.01, P = 0.68) and of CVE (HR, 0.60; 95% CI, 0.28-1.29, P = 0.19) compared with patients without RKF undergoing thrice-weekly HD. However, this group showed an independent association with a greater risk of mortality compared with patients with RKF undergoing thrice-weekly HD (HR, 4.20; 95% CI, 1.02-17.32, P = 0.04).In conclusion, patients with RKF undergoing twice-weekly HD had an increased risk of mortality compared with those undergoing thrice-weekly HD. Decisions about twice-weekly HD should consider not only RKF, but also other risk factors such as normalized protein catabolic rate.

Tenofovir-associated Fanconi syndrome and nephrotic syndrome in a patient with chronic hepatitis B monoinfection

Tenofovir disoproxil fumarate (TDF) is widely used as an effective first-line therapy for chronic hepatitis B (CHB) infection. While TDF demonstrates successful viral suppression, it has been linked to the development of renal proximal tubular (PT) dysfunction, leading to Fanconi syndrome. However, Fanconi syndrome has been rarely reported in CHB-monoinfected patients, and there were no reports of TDF-associated nephrotic syndrome. Here, we report a case of combined Fanconi and nephrotic syndrome in CHB patients after TDF exposure.

Diabetes retinopathy is a poor predictor for renal and cardiovascular outcomes in comparison with hypertensive retinopathy in patients with chronic kidney disease

AIMS

Chronic kidney disease (CKD) and retinopathy share the common pathophysiology of microvascular dysfunction. It is unclear whether the clinical significance of diabetic retinopathy (DMR) and hypertensive retinopathy (HTNR) differs in CKD patients.

METHODS

We included 684 nondialysis-dependent CKD stage 3-5 patients with diabetes or hypertension: 501 patients with diabetes and 183 with hypertension. The clinical significance of DMR and HTNR was evaluated in terms of the rate of renal function decline and composite of any cardiovascular event or death.

RESULTS

DMR was observed in 261 (52.1%) CKD patients with diabetes, and HTNR in 44 (24.0%) CKD patients with hypertension. In the diabetes group, the renal function decline rate was significantly steeper in patients with than in those without DMR (-7.4 ± 9.8mL/min/1.73m(2)/yr vs. -2.4 ± 7.6mL/min/1.73m(2)/yr; P<0.001). In multivariate analysis, DMR were independently associated with a rapid decline in renal function (β=-2.44; P=0.20). However, HTNR did not affect the renal function decline in CKD patients. The composite event-free survival rate was lower in patients with diabetes and DMR than in those without DMR (P=0.043). Patients with diabetes and DMR were independently associated with a 2.13-fold increased risk for composite events (P=0.010). HTNR was not associated with higher risk for composite events in CKD patients.

CONCLUSION

Coexistence of diabetes and DMR were independently associated with CKD progression and composite cardiovascular event/death, but the clinical significance of HTNR is less clear in CKD patients.

Diagnostic utility of immunochemical fecal occult blood tests to detect lower gastrointestinal lesions in patients with chronic kidney disease

PURPOSE

The immunochemical fecal occult blood test (iFOBT) is a useful method to screen for lower gastrointestinal (GI) bleeding-related lesions. However, few studies have investigated the diagnostic utility of iFOBT in chronic kidney disease (CKD).

METHODS

We included 691 patients with nondialysis-dependent CKD stages 2-5 or those receiving dialysis. Bleeding-related lower GI lesions were identified by colonoscopy, and the diagnostic utility of iFOBT was evaluated.

RESULTS

Bleeding-related lower GI lesions were found in 9.2% of 491 patients with CKD stage 2, 17.8% of 107 patients with CKD stage 3/4, and 25.8% of 93 patients with CKD stage 5/dialysis (p < 0.001). Compared with CKD stage 2, CKD stage 5/dialysis was independently associated with a 2.80-fold risk for bleeding-related lesions (p = 0.019). The iFOBT was positive in 92 (13.3%) patients and the area under the receiver operating curve (AUC) for a bleeding-related lesion was 0.64 (p < 0.001). The sensitivity of iFOBT increased as the CKD stage worsened (20.0 vs 52.6 vs 58.3%; p = 0.002). However, the specificity to detect bleeding-related lesions decreased with the severity of CKD stage (94.6 vs. 78.4 vs. 76.8%; p < 0.001). The AUC of iFOBT to detect adenoma or carcinoma was 0.54 (p = 0.046), and a similar pattern of sensitivity and specificity was observed between different CKD stages.

CONCLUSIONS

The prevalence of bleeding-related lower GI lesions and the sensitivity of iFOBT to detect these GI lesions increased in advanced CKD. However, iFOBT should be used cautiously in these patients because its specificity decreased.

The prevalence of bronchiectasis in patients with Marfan syndrome

An association has been suggested between Marfan syndrome (MFS) and the nodular bronchiectatic form of lung disease caused by non-tuberculous mycobacteria (NTM). We evaluated the prevalence of bronchiectasis in 79 adult patients with MFS using computed tomography (CT) imaging. Airway dilation indicative of bronchiectasis (22/79, 28%) and bronchioloectasis (10/79, 13%) were relatively common, although the extent of dilation was not severe and was frequently confined to a single lobe. However, bronchiolitis was evident in only three patients (4%), and no patient was diagnosed with NTM lung disease.

Progressive rise in red blood cell distribution width predicts mortality and cardiovascular events in end-stage renal disease patients

Red blood cell distribution width (RDW) is a robust marker of adverse clinical outcomes in various populations. However, the clinical significance of a progressive rise in RDW is undetermined in end-stage renal disease (ESRD) patients. The purpose of this study was to determine the prognostic importance of a change in RDW in ESRD patients. Three hundred twenty-six incident dialysis patients were retrospectively analyzed. Temporal changes in RDW during 12 months after dialysis initiation were assessed by calculating the coefficients by linear regression. Patients were divided into two groups: an RDW-decreased group who had negative coefficient values (n = 177) and an RDW-increased group who had positive values (n = 149). The associations between rising RDW and mortality and cardiovascular (CV) events were investigated. During a median follow-up of 2.7 years (range, 1.0–7.7 years), 75 deaths (24.0%) and 60 non-fatal CV events (18.4%) occurred. The event-free survival rate for the composite of end-points was lower in the RDW-increased group (P = 0.004). After categorizing patients according to baseline RDW, the event-free survival rate was lowest in patients with a baseline RDW >14.9% and increased RDW, and highest in patients with a baseline RDW ≤14.9% and decreased RDW (P = 0.02). In multivariate analysis, rising RDW was independently associated with the composite of end-points (hazard ratio = 1.75, P = 0.007), whereas the baseline RDW was not. This study shows that a progressive rise in RDW independently predicted mortality and CV events in ESRD patients. Rising RDW could be an additive predictor for adverse CV outcomes ESRD patients.