Circulating osteoprotegerin levels and cardiovascular outcomes in patients with pre-dialysis chronic kidney disease: results from the KNOW-CKD study.

While the relationship between circulating osteoprotegerin (OPG) and cardiovascular events is well-established in the general population, its association with cardiovascular risks in chronic kidney disease (CKD) patients remains less robust. This study hypothesized that elevated circulating OPG levels might be associated with an increased risk of major adverse cardiac events (MACE) in CKD patients, a total of 2,109 patients with CKD stages 1 through pre-dialysis 5 from the KNOW-CKD cohort were categorized into quartiles based on serum OPG levels. The primary outcome of the study was 3-point MACE, defined as a composite of nonfatal myocardial infarction, nonfatal stroke, or cardiac death. The median follow-up duration was 7.9 years. The cumulative incidence of 3-point MACE significantly varied across serum OPG levels in Kaplan-Meier curve analysis (P < 0.001, log-rank test), with the highest incidence observed in the 4th quartile. Cox regression analysis indicated that, relative to the 1st quartile, the risk of 3-point MACE was significantly higher in the 3rd (adjusted hazard ratio 2.901, 95% confidence interval 1.009 to 8.341) and the 4th quartiles (adjusted hazard ratio 4.347, 95% confidence interval 1.410 to 13.395). In conclusion, elevated circulating OPG levels are associated with adverse cardiovascular outcomes in pre-dialysis CKD patients.

Predictive performance of the new race-free Chronic Kidney Disease Epidemiology Collaboration equations for kidney outcome in Korean patients with chronic kidney disease.

BACKGROUND: The new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations without a race coefficient have gained recognition across the United States. We aimed to test whether these new equations performed well in Korean patients with chronic kidney disease (CKD). METHODS: This study included 2,149 patients with CKD G1-G5 without kidney replacement therapy from the Korean Cohort Study for Outcome in Patients with CKD (KNOW-CKD). The estimated glomerular filtration rate (eGFR) was calculated using the new CKD-EPI equations with serum creatinine and cystatin C. The primary outcome was 5-year risk of kidney failure with replacement therapy (KFRT). RESULTS: When we adopted the new creatinine equation [eGFRcr (NEW)], 81 patients (23.1%) with CKD G3a based on the current creatinine equation (eGFRcr) were reclassified as CKD G2. Accordingly, the number of patients with eGFR of <60 mL/min/1.73 m2 decreased from 1,393 (64.8%) to 1,312 (61.1%). The time-dependent area under the receiver operating characteristic curve for 5-year KFRT risk was comparable between the eGFRcr (NEW) (0.941; 95% confidence interval [CI], 0.922-0.960) and eGFRcr (0.941; 95% CI, 0.922-0.961). The eGFRcr (NEW) showed slightly better discrimination and reclassification than the eGFRcr. However, the new creatinine and cystatin C equation [eGFRcr-cys (NEW)] performed similarly to the current creatinine and cystatin C equation. Furthermore, eGFRcr-cys (NEW) did not show better performance for KFRT risk than eGFRcr (NEW). CONCLUSION: Both the current and the new CKD-EPI equations showed excellent predictive performance for 5-year KFRT risk in Korean patients with CKD. These new equations need to be further tested for other clinical outcomes in Koreans.

Comparison of outcomes of chronic kidney disease based on etiology: a prospective cohort study from KNOW-CKD.

The causes of chronic kidney disease (CKD) affects its outcomes. However, the relative risks for adverse outcomes according to specific causes of CKD is not well established. In a prospective cohort study from KNOW-CKD, a cohort was analyzed using overlap propensity score weighting methods. Patients were grouped into four categories according to the cause of CKD: glomerulonephritis (GN), diabetic nephropathy (DN), hypertensive nephropathy (HTN), or polycystic kidney disease (PKD). From a total of 2070 patients, the hazard ratio of kidney failure, the composite of cardiovascular disease (CVD) and mortality, and the slope of the estimated glomerular filtration rate (eGFR) decline according to the cause of CKD were compared between causative groups in a pairwise manner. There were 565 cases of kidney failure and 259 cases of composite CVD and death over 6.0 years of follow-up. Patients with PKD had a significantly increased risk for kidney failure compared to those with GN [Hazard ratio (HR) 1.82], HTN (HR 2.23), and DN (HR 1.73). For the composite outcome of CVD and death, the DN group had increased risks compared to the GN (HR 2.07), and HTN (HR 1.73) groups but not to the PKD group. The adjusted annual eGFR change for the DN and PKD groups were - 3.07 and - 3.37 mL/min/1.73 m2 per year, respectively, and all of these values were significantly different than those of the GN and HTN groups (- 2.16 and - 1.42 mL/min/1.73 m2 per year, respectively). In summary, the risk of kidney disease progression was relatively higher in patients with PKD compared to other causes of CKD. However, the composite of CVD and death was relatively higher in patients with DN-related CKD than in those with GN- and HTN-related CKD.

Urine creatinine concentration influences the prognostic value of proteinuria for MACE prediction from the findings of the KNOW-CKD study.

Proteinuria is typically quantified according to the spot urine protein-creatinine ratio (UPCR) and an association with cardiovascular events has not been thoroughly investigated in chronic kidney disease (CKD) patients. We investigated whether the severity of proteinuria assessed by spot UPCR is associated with an increased risk for cardiovascular outcomes in the CKD population, and whether the relationship is influenced by urine creatinine concentration. We analyzed 1746 patients enrolled as part of The KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD). Multivariable Cox proportional hazard analysis was performed to evaluate models with proteinuria as a predictor of renal events and extended major adverse cardiovascular events (eMACEs). Risk for renal events was significantly associated with proteinuria across all eGFR and UPCR categories. By contrast, risk for eMACEs increased significantly with UPCR in patients with eGFR ≥ 60 mL/min/1.73 m2 (hazard ratio [HR] 2.109; 95% confidence interval [CI] 1.375-3.235; P = 0.001), but not in patients with eGFR < 60 mL/min/1.73 m2 (HR 1.086; 95% CI 0.910-1.296; P = 0.358). However, in those with the lower eGFR, risk for eMACEs increased significantly with UPCR in participants with urine creatinine concentration ≥ 95 mg/dL (HR 1.503; 95% CI 1.047-2.159; P = 0.027). In non-dialysis CKD patients, the prognostic value of UPCR for eMACEs is weakened in patients with reduced eGFR levels, for whom it has prognostic significance only in patients with high urine creatinine concentration.

The difference between cystatin C- and creatinine-based eGFR is associated with adverse cardiovascular outcome in patients with chronic kidney disease.

BACKGROUND AND AIMS: Decreased kidney function is an important risk factor for cardiovascular disease (CVD). However, assessing risk of CVD may be difficult when there is a gap between creatinine- and cystatin C-based estimated glomerular filtration rate (eGFR). We studied the association of the difference in eGFRs with major adverse cardiovascular events (MACE) in patients with chronic kidney disease (CKD). METHODS: This prospective cohort study was conducted in 2076 patients with CKD stages based on the KDIGO guideline (eGFR categories of G1: ≥90; G 2: 60-89; G3: 30-59; G4: 15-29; G5: <15 mL/min/1.73 m2 without kidney replacement therapy). The difference in eGFR (eGFRdiff) was calculated by subtracting the cystatin C-based eGFR (eGFRcys) from the creatinine-based eGFR (eGFRcreat). The primary outcome was MACE, defined as non-fatal acute myocardial infarction and unstable angina, stroke, congestive heart failure, symptomatic arrhythmia, and cardiac death. RESULTS: During a median follow-up of 4.1 years, MACE occurred in 147 patients (incidence rate, 15.0 per 1000 patient-years). When patients were categorized into baseline eGFRdiff tertiles, the highest tertile was associated with a significantly higher risk of MACE (hazard ratio, 2.12; 95% confidence interval [CI], 1.28-3.51) than the lowest tertile when adjusted for eGFRcreat, eGFRcys, or eGFR based on both creatinine and cystatin C. Patients in the highest tertile had more baseline coronary artery calcification (CAC) than those in the lowest tertile (odds ratio [OR], 1.38; 95% CI, 1.03-1.86). In addition, 978 patients had data for both baseline and follow-up CAC at year 4. In this subgroup, baseline eGFRdiff was significantly associated with accelerated CAC progression (≥50/year) (OR, 1.03; 95% CI, 1.01-1.05). CONCLUSIONS: A large positive difference between eGFRcreat and eGFRcys was associated with a higher risk of MACE and faster CAC progression in patients with CKD. Therefore, careful monitoring of CVD is needed for patients with a higher eGFRdiff.

Soluble ST2 and Galectin-3 as Predictors of Chronic Kidney Disease Progression and Outcomes.

BACKGROUND: Soluble suppression of tumorigenicity-2 (sST2) and galectin-3, novel biomarkers of heart failure and cardiovascular stress, predict cardiovascular events (CVEs) and mortality. However, their relationship with kidney function and adverse outcomes in CKD are uncertain. The purpose of this study was to determine the association between sST2 and galectin-3 with CKD progression and adverse clinical outcomes. METHODS: We measured baseline sST2 and galectin-3 levels in the CKD patient cohort at our institution between October 2013 and December 2014. The primary outcome was CKD progression (kidney failure with replacement therapy or ≥50% reduction in estimated glomerular filtration rate from the baseline). The secondary outcome was the composite of CVEs and death. We used a Cox proportional hazards model to evaluate the associations between sST2 and galectin-3 levels, with kidney and clinical outcomes. RESULTS: In total, 352 patients were enrolled in this study. At baseline, log sST2 and galectin-3 were directly associated with the serum creatinine (Cr) and urine protein-to-Cr ratio. Cox regression analysis showed that the baseline log sST2 level independently predicted CKD progression and composite outcome after adjustment for age, sex, smoking, diabetes mellitus, hypertension, cardiovascular disease, renin-angiotensin system blocker, calcium channel blocker, ß-blocker, diuretics, antiplatelet agents, anemia, and hypoalbuminemia. The baseline log galectin-3 level was independently associated with CKD progression, but not with the composite outcome after adjustment for confounding variables. CONCLUSIONS: Elevated levels of sST2 and galectin-3 are significantly associated with CKD progression, but only sST2 is associated with adverse clinical outcomes.

Elevated levels of soluble ST2 but not galectin-3 are associated with increased risk of mortality in hemodialysis patients.

BACKGROUND: The soluble forms of suppression of tumorigenicity-2 (ST2) and galectin-3 have been proposed as novel biomarkers for cardiac fibrosis and heart failure, as well as predictors of cardiovascular events and mortality. However, there are limited data on the association between soluble ST2 and galectin-3 and clinical outcomes in patients with kidney failure on replacement therapy. To determine this, we examined the associations between soluble ST2 and galectin-3 and all-cause mortality and cardiovascular events in patients on hemodialysis. METHODS: This study included maintenance hemodialysis patients (over 18 years old) who consented to preserve their serum in the Biobank at our institution between March 2014 and March 2015. We used Cox proportional hazards regression analysis to evaluate the associations between soluble ST2, galectin-3 levels, and clinical outcomes. The primary outcome was all-cause mortality, the secondary outcome was cardiovascular disease, and patients were followed for both outcomes until March 2018. RESULTS: A total of 296 patients were analyzed in this study. The mean age was 57 ± 13 years, and 53.0% were male. Serum concentration of soluble ST2 was significantly associated with higher mortality, after adjustment for confounding factors, but was not associated with cardiovascular disease. Serum galectin-3 level was not independently associated with either outcome after adjustment. CONCLUSION: Elevated soluble ST2 is independently associated with an increased risk of mortality, but not with cardiovascular disease, in patients on hemodialysis. Elevated galectin-3 was not associated with mortality or cardiovascular disease.

Dynamic body posture after unilateral mastectomy: a pilot study.

BACKGROUND: Postural changes after unilateral mastectomy may appear in relation to the dominant hand, postoperative duration, and dynamic conditions. This study aimed to compare the postural changes by inclination angles and muscle activities in the static and dynamic sitting position between women with breast cancer who underwent mastectomy and women who did not have breast cancer. METHODS: The observational study design was conducted. We evaluated 17 women who underwent modified radical mastectomy (MRM) more than 1 year prior to the study. They were categorized into the Rt. mastectomy group (n=7) and the Lt. mastectomy group (n=10). An aged-matched cohort of 8 healthy females was also included. The inclination angle in both static and dynamic sitting positions was measured using the balance board system (BBS), and the muscle activities of 8 muscles were measured in the dynamic sitting position. RESULTS: There was no significant difference in demographic characteristics between the patients, and all patients were right-handed. The inclination angle of the anterior-posterior axis when leaning forward was significantly increased to the anterior side in the Rt. mastectomy group than in the Lt. mastectomy group. Meanwhile, the inclination angle in the static sitting position and when tilted backward to both directions did not differ among the 3 groups. The inclination angle of the right-left axis was statistically increased to the left side during tilting anterior-left direction in the Rt. Mastectomy group. The muscle activities of the thoracic erector spinae were significantly lower when tilted backward in the Rt. mastectomy group than in the Lt. mastectomy group. CONCLUSIONS: Compared with left mastectomy, right unilateral mastectomy yielded more postural changes under dynamic sitting state in right-handed female patients with breast cancer. Thus, to maintain the trunk balance and prevent the postural changes after unilateral mastectomy, the postoperative exercise programs for the para-thoracic muscles will be helpful.

Reduction of Secreted Frizzled-Related Protein 5 Drives Vascular Calcification through Wnt3a-Mediated Rho/ROCK/JNK Signaling in Chronic Kidney Disease.

Vascular calcification (VC) is commonly associated with bone loss in patients with chronic kidney disease (CKD). The Wingless-related integration site (Wnt) regulates osteoblast activation through canonical signaling pathways, but the common pathophysiology of these pathways during VC and bone loss has not been identified. A rat model of adenine-induced CKD with VC was used in this study. The rats were fed 0.75% adenine (2.5% protein, 0.92% phosphate) with or without intraperitoneal injection of calcitriol (0.08 µg/kg/day) for 4 weeks. Angiotensin II (3 µM)-induced VC was achieved in high phosphate medium (3 mM) through its effect on vascular smooth muscle cells (VSMCs). In an mRNA profiler polymerase chain reaction assay of the Wnt signaling pathway, secreted frizzled-related protein 5 (sFRP5) levels were significantly decreased in the CKD rat model compared with the control group. The repression of sFRP5 on VSMC trans-differentiation was mediated through Rho/Rho-associated coiled coil containing protein kinase (ROCK) and c-Jun N-terminal kinase (JNK) pathways activated by Wnt3a. In a proof of concept study conducted with patients with CKD, serum sFRP5 concentrations were significantly lower in subjects with VC than in those without VC. Our findings suggest that repression of sFRP5 is associated with VC in the CKD environment via activation of the noncanonical Wnt pathway, and thus that sFRP5 might be a novel therapeutic target for VC in CKD.

UVB-dependent inhibition of lipin-1 protects against proinflammatory responses in human keratinocytes.

Lipin-1 is an Mg2+-dependent phosphatidate phosphatase (PAP1) that catalyzes a critical step in the synthesis of glycerophospholipids and is also a cotranscriptional regulator. The role of lipin-1 in the regulation of inflammatory responses has been extensively studied in various cell types but not in skin cells. In the present study, the function of lipin-1 in UVB-induced proinflammatory responses was assessed in normal human epidermal keratinocytes (NHEKs). UVB radiation downregulated lipin-1 expression. Lipin-1 inhibition was mediated by UVB-dependent sterol-response element binding protein-1 (SREBP-1) inhibition. The UVB-dependent inhibition of lipin-1 and SREBP-1 was mediated by AMPK activation. UVB-induced activation of JNK was dependent on AMPK activation and mediated lipin-1 inhibition. Prevention of UVB-mediated lipin-1 repression by introducing a lipin-1 expression vector stimulated IL-6 and IL-8 production, suggesting that lipin-1 inhibition attenuates UVB-induced IL-6 and IL-8 production. The downregulation of lipin-1 ameliorated UVB-induced NF-ĸB phosphorylation, which might be attributed to the suppression of UVB-induced accumulation of free fatty acids (FFAs). Pharmacological inhibition of PAP1 with propranolol suppressed UVB-induced production of IL-6 and IL-8 in NHEKs and reconstituted human skin models. Taken together, lipin-1 is downregulated by exposure to UVB radiation, which confers protection against UVB-induced proinflammatory responses; therefore, the inhibition of lipin-1 is a potential strategy for photoaging.

Association between acute kidney injury and serum procalcitonin levels and their diagnostic usefulness in critically ill patients.

Procalcitonin (PCT) is a useful marker for the diagnosis of systemic inflammatory response syndrome. In addition, PCT is affected by renal function. However, few studies have investigated the relationship between PCT and the development of acute kidney injury (AKI). Hence, we investigated whether serum PCT levels at the time of admission were associated with the development of AKI and clinical outcomes. A total of 790 patients in whom PCT was measured on admission to the intensive care unit (ICU) were analyzed retrospectively. We attempted to investigate whether serum PCT levels measured at the time of admission could be used as a risk factor for the development of AKI in septic and nonseptic patients or as a risk factor for all-cause mortality, and diagnostic usefulness of PCT was further assessed. Serum PCT levels were significantly higher in patients with AKI than in those without AKI (P < 0.001). After multivariable adjustment for clinical factors, laboratory findings, and comorbidities, PCT as a continuous variable showed a significant association with AKI (OR 1.006, 95% CI [1.000-1.011]; P = 0.035). However, PCT was not effective in predicting mortality. The cut-off value of PCT for the prediction of AKI incidence was calculated to be 0.315 ng/ml, with sensitivity and specificity of 60.9% and 56.9%, respectively. The odds ratios (ORs) from an equation adjusted for optimum thresholds of PCT levels for developing AKI with and without sepsis were 2.422 (1.222-4.802, P = 0.011) and 1.798 (1.101-2.937, P = 0.019), respectively. However, there were no absolute differences between the pre- and posttest probabilities after including the PCT value for AKI development. This study suggests that the PCT value was higher in AKI patients than in non-AKI patients, but PCT measurement at the time of admission did not improve the prediction model for AKI.

Differential diagnoses of magnetic resonance imaging for suspected acute appendicitis in pregnant patients.

BACKGROUND: Accurate and timely diagnosis of acute surgical disease in pregnant patient is challenging. Although magnetic resonance imaging (MRI) is the most accurate modality to diagnose acute appendicitis in pregnant patients, it is often used as a last resort because of high cost and long scan time. We performed this study to analyze differential diagnoses of appendix MRI and to investigate if there are any blood tests that can predict surgical condition in pregnant patients. METHODS: A retrospective, cross-sectional study was conducted on 46 pregnant patients who underwent non-enhanced appendix MRI in suspicion of acute appendicitis from 2010 to 2016. Differential diagnoses of appendix MRI were analyzed and blood tests were compared between those who had surgical and non-surgical disease. RESULTS: Appendix MRI differentiated two surgical disease; acute appendicitis and ovarian torsion; and various non-surgical conditions such as uterine myoma, hydronephrosis, ureterolithiasis and diverticulitis among clinically suspected acute appendicitis in pregnancy. The diagnostic accuracy of MRI for acute appendicitis in this study was 93.5%. Patients who had surgical disease showed significantly higher WBC count (≥11,000/mm3), proportion of neutrophils in the WBC (≥79.9%), neutrophil-to-lymphocyte ratio (NLR≥6.4), levels of C-reactive protein (CRP≥1.82 mg/dL) and bilirubin (≥0.66 mg/dL) than those who had non-surgical disease. CONCLUSION: MRI can reliably differentiate surgical conditions and several blood tests (WBC, proportion of neutrophils in the WBC, NLR, CRP, bilirubin) can help anticipate acute surgical condition among pregnant patients suspected to have acute appendicitis.

The association of kidney function with repetitive breath-hold diving activities of female divers from Korea, Haenyeo.

BACKGROUND: Voluntary apnea during breath-hold diving (BHD) induces cardiovascular changes including bradycardia, reduced cardiac output, and arterial hypertension. Although the impacts of repetitive BHD on cardiovascular health have been studied previously, the long-term risk for kidney dysfunction has never been investigated. METHODS: A cross-sectional propensity score-matched study was performed to evaluate the influence of repetitive long-lasting BHD on kidney function. Using matching propensity scores (PS), 715 breath-hold female divers (Haenyeo) and non-divers were selected for analysis from 1,938 female divers and 3,415 non-divers, respectively. The prevalence of chronic kidney disease (CKD) defined as an estimated glomerular filtration rate (eGFR) calculated to be less than 60 ml/min/1.73 m2 was investigated in both diver and non-diver groups. RESULTS: The prevalence of CKD was significantly higher in breath-hold divers compared with non-divers after PS matching (12.6% vs. 8.0%, P = 0.004). In multivariate analysis, BHD activity was significantly associated with the risk of CKD in an unmatched cohort (OR, 1.976; 95% CI, 1.465-2.664). In the PS-matched cohort, BHD remained the independent risk factor for CKD even after adjusting for multiple covariates (OR 1.967; 95% CI, 1.341-2.886). CONCLUSION: Shallow but repetitive intermittent apnea by BHD, sustained for a long period of time, may potentially cause a deterioration in kidney function, as a long-term consequence.

The Prevalence and Management of Anemia in Chronic Kidney Disease Patients: Result from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD).

Anemia is a common and significant complication of chronic kidney disease (CKD). However, its prevalence and current management status has not been studied thoroughly in Korea. We examined the prevalence of anemia, its association with clinical and laboratory factors, and utilization of iron agents and erythropoiesis stimulating agents using the baseline data from the large-scale CKD cohort in Korea. We defined anemia when hemoglobin level was lower than 13.0 g/dL in males and 12.0 g/dL in females, or received by erythropoiesis stimulating agents. Overall prevalence of anemia was 45.0% among 2,198 non-dialysis CKD patients from stage 1 to 5. Diabetic nephropathy (DN) as a cause, CKD stages, body mass index (BMI), smoking, leukocyte count, serum albumin, iron markers, calcium, and phosphorus concentration were identified as independent risk factors for anemia. Considering the current coverage of Korean National Health Insurance System, only 7.9% among applicable patients were managed by intravenous iron agents, and 42.7% were managed by erythropoiesis stimulating agents.

Baseline renal function as a prognostic indicator in patients with newly diagnosed diffuse large B-cell lymphoma.

BACKGROUND: The association between baseline renal impairment (RI) and the prognosis of diffuse large B-cell lymphoma (DLBCL) was previously not defined. The aim of this study was to evaluate the prognostic value of RI in patients with DLBCL treated with three-weekly rituximab plus cyclophosphamide, Adriamycin, vincristine, and prednisolone immunochemotherapy (R-CHOP21). METHODS: Patients with newly diagnosed de novo DLBCLs treated with ≥1 cycle of R-CHOP21 were analyzed retrospectively. Pretreatment blood samples were collected and the glomerular filtration rate (GFR) was calculated. RI was defined by a GFR of <60 mL/min/1.73 m(2) according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. RESULTS: Of the 185 patients enrolled in the present study, 19 patients (10.3%) had RI. The reasons for baseline RI were pre-existing CKD (N=5), acute kidney injury due to either obstruction (N=2) or electrolyte imbalance (N=2) related to DLBCL, and undefined causes (N=10). Patients with baseline RI showed inferior overall survival (OS) compared to those without RI (P<0.001). In multivariate analysis, RI was identified as an International Prognostic Index (IPI)-independent prognostic indicator. A baseline hemoglobin level of <10 g/dL and the presence of RI effectively discriminated a portion of the patients with far inferior event-free survival and OS among the patients having high or high-intermediate risk cancers according to either the standard- or the National Comprehensive Cancer Network-IPI. CONCLUSION: Pretreatment RI was an independent prognostic marker for inferior OS in patients with DLBCL treated with R-CHOP21 immunochemotherapy.

The Role of TNF Superfamily Member 13 in the Progression of IgA Nephropathy.

TNF superfamily member 13 (TNFSF13) has been identified as a susceptibility gene for IgA nephropathy in recent genetic studies. However, the role of TNFSF13 in the progression of IgA nephropathy remains unresolved. We evaluated two genetic polymorphisms (rs11552708 and rs3803800) and plasma levels of TNFSF13 in 637 patients with IgA nephropathy, and determined the risk of ESRD according to theses variable. Neither of the examined genetic polymorphisms associated with a clinical outcome of IgA nephropathy. However, high plasma levels of TNFSF13 increased the risk of ESRD. To explore the causal relationship and underlying mechanism, we treated B cells from patients (n=21) with or without recombinant human TNFSF13 (rhTNFSF13) and measured the expression of IgA and galactose-deficient IgA (GdIgA) using ELISA and flow cytometry. Treatment with rhTNFSF13 significantly increased the total IgA level among B cells, and TNFSF13 receptor blockade abrogated this increase. Furthermore, the absolute levels of GdIgA increased with rhTNFSF13 treatment, but the total IgA-normalized levels did not change. Both RNA sequencing and quantitative PCR results showed that rhTNFSF13 did not alter the expression of glycosyltransferase enzymes. These results suggest that high plasma TNFSF13 levels associate with a worse prognosis of IgA nephropathy through the relative increase in GdIgA levels.

S-nitrosylation of fatty acid synthase regulates its activity through dimerization.

NO regulates a variety of physiological processes, including cell proliferation, differentiation, and inflammation. S-nitrosylation, a NO-mediated reversible protein modification, leads to changes in the activity and function of proteins. In particular, the role of S-nitrosylation during adipogenesis is largely unknown. We hypothesized that the normal physiological levels of NO, but not the excess levels generated under severe conditions, such as inflammation, may be critically involved in the proper regulation of adipogenesis. We found that endogenous S-nitrosylation of proteins was required for adipocyte differentiation. By performing a biotin-switch assay, we identified FAS, a key lipogenic enzyme in adipocytes, as a target of S-nitrosylation during adipogenesis. Interestingly, we also observed that the dimerization of FAS increased in parallel with the amount of S-nitrosylated FAS during adipogenesis. In addition, we found that exogenous NO enhanced the dimerization and the enzymatic activity of FAS. Moreover, site-directed mutagenesis of three predicted S-nitrosylation sites indicated that S-nitrosylation of FAS at Cys(1471)and Cys(2091), but not at Cys(1127), increased its enzymatic activity. Taken together, these results suggest that the S-nitrosylation of FAS at normal physiological levels of NO increases its activity through dimerization and may contribute to the proper regulation of adipogenesis.

Klotho and S100A8/A9 as Discriminative Markers between Pre-Renal and Intrinsic Acute Kidney Injury.

Early detection and accurate differentiation of the cause of AKI may improve the prognosis of the patient. However, to date, there are few reliable biomarkers that can discriminate between pre-renal and intrinsic AKI. In this study, we determined whether AKI is associated with altered serum and urinary levels of Klotho, S100A8/A9 (an endogenous ligand of toll-like receptor 4), and neutrophil gelatinase-associated lipocalin (NGAL), which may allow differentiation between pre-renal and intrinsic AKI. A volume-depleted pre-renal AKI model was induced in male Sprague Dawley rats fed a low-salt diet (0.03%) without water 96 h before two intraperitoneal (IP) injections of furosemide (20 mg/kg) at a 24 h interval. In contrast, in the cisplatin-induced intrinsic AKI model, animals were given a single IP injection of cisplatin (5 mg/kg). All of the animals were euthanized 72 h after the first IP injection. Serum and urinary levels of Klotho, S100A8/A9, and NGAL were measured using an enzyme-linked immunosorbent assay. We also performed a proof-of-concept cross-sectional study to measure serum and urinary biomarkers in 61 hospitalized patients with established AKI. Compared to the intrinsic AKI group, the pre-renal AKI group showed a marked depression in urinary Klotho levels (13.21 ± 17.32 vs. 72.97 ± 17.96 pg/mL; P = 0.002). In addition, the intrinsic AKI group showed marked elevation of S100A8/A9 levels compared to the pre-renal AKI group (2629.97 ± 598.05 ng/mL vs. 685.09 ± 111.65 ng/mL; P = 0.002 in serum; 3361.11 ± 250.86 ng/mL vs. 741.72 ± 101.96 ng/mL; P = 0.003 in urine). There was no difference in serum and urinary NGAL levels between the pre-renal and intrinsic AKI groups. The proof-of-concept study with the hospitalized AKI patients also demonstrated decreased urinary Klotho in pre-renal AKI patients and increased urinary S100A8/A9 concentrations in intrinsic AKI patients. The attenuation of urinary Klotho and increase in urinary S100A8/A9 may allow differentiation between pre-renal and intrinsic AKI.

Lipin-1 expression is critical for keratinocyte differentiation.

Lipin-1 is an Mg(2+)-dependent phosphatidate phosphatase that facilitates the dephosphorylation of phosphatidic acid to generate diacylglycerol. Little is known about the expression and function of lipin-1 in normal human epidermal keratinocytes (NHEKs). Here, we demonstrate that lipin-1 is present in basal and spinous layers of the normal human epidermis, and lipin-1 expression is gradually downregulated during NHEK differentiation. Interestingly, lipin-1 knockdown (KD) inhibited keratinocyte differentiation and caused G1 arrest by upregulating p21 expression. Cell cycle arrest by p21 is required for commitment of keratinocytes to differentiation, but must be downregulated for the progress of keratinocyte differentiation. Therefore, reduced keratinocyte differentiation results from sustained upregulation of p21 by lipin-1 KD. Lipin-1 KD also decreased the phosphorylation/activation of protein kinase C (PKC)α, whereas lipin-1 overexpression increased PKCα phosphorylation. Treatment with PKCα inhibitors, like lipin-1 KD, stimulated p21 expression, while lipin-1 overexpression reduced p21 expression, implicating PKCα in lipin-1-induced regulation of p21 expression. Taken together, these results suggest that lipin-1-mediated downregulation of p21 is critical for the progress of keratinocyte differentiation after the initial commitment of keratinocytes to differentiation induced by p21, and that PKCα is involved in p21 expression regulation by lipin-1.

Hypoxia leads to abnormal epidermal differentiation via HIF-independent pathways.

Atmospheric oxygen is important for the epidermis, as the skin epidermis is not greatly affected by blood circulation. Therefore, it is necessary to understand the effect of hypoxic signals on the epidermis as some environmental stimuli can induce skin hypoxia. Here, we investigated how hypoxia (1% O2) affected skin equivalents (SEs) and normal human epidermal keratinocytes. We found that hypoxia specifically decreased the protein levels of keratin 1 (K1)/keratin 10 (K10), a representative marker of the epidermal spinous layer in the epidermis. However, hypoxia-inducible factors, the major regulators of hypoxia, did not affect hypoxia-induced down-regulation of K1/K10. We also found that N-acetyl-l-cysteine (NAC), a reactive oxygen species scavenger, antagonized the hypoxia-induced reduction of K1/K10 in keratinocytes and SEs. In contrast to the findings for NAC, inhibitors that blocked reactive oxygen species generation did not cause recovery of K1/K10 protein levels under hypoxic conditions. Taken together, these results indicate that hypoxia leads to abnormal keratinocyte differentiation by down-regulating K1/K10 and that this phenomenon can be ameliorated by NAC.