Absolute iron deficiency, coronary artery calcification and cardiovascular mortality in maintenance haemodialysis patients.

AIM: The effects of iron on vascular calcification in rats and vascular smooth muscle cells were recently reported, but clinical studies on iron and vascular calcification are scant. We studied the associations of absolute iron deficiency, coronary artery calcification and mortality in patients with maintenance haemodialysis (MHD). METHODS: Transferrin saturation (TSAT), ferritin, mean corpuscular haemoglobin (MCH) and Agatston coronary artery calcium score (CACS) were studied at baseline in MHD patients and followed up for 3 years. Cox proportional hazard analyses for mortality and linear regression analyses for CACS were performed. RESULTS: In 306 patients, the median age was 67 (56-81) years, dialysis duration was 76 (38-142) months, and diabetes prevalence was 42.5%. Fifty-two patients had died by 3 years. Patients with absolute iron deficiency (TSAT <20% and ferritin <100 ng/mL) (n = 102) showed significantly higher CACS (p = .0266) and C-reactive protein (p = .0011), but a lower frequency of iron formulation administration compared with patients without absolute iron deficiency at baseline (n = 204). Absolute iron deficiency was a significant predictor for 3-year cardiovascular (CV) mortality (hazard ratio: 2.08; p = .0466), but not for 3-year all-cause mortality. CACS was significant predictor for both 3-year CV and all-cause mortality (p <.05). Absolute iron deficiency and MCH were significant determinants of CACS (p < .05). CONCLUSION: MHD patients with absolute iron deficiency showed significantly higher CACS than others, and absolute iron deficiency was a significant risk factor for coronary artery calcification and 3-year CV mortality in MHD patients, but was not a significant predictor for 3-year all-cause mortality.

Effects of overhydration, Kt/Vurea, ß2-microglobulin on coronary artery calcification and mortality in haemodialysis patients.

AIM: We studied the effects of overhydration (OH), Kt/Vurea and ß2-microglobulin (ß2-MG) on coronary artery calcification and mortality in patients undergoing haemodialysis (HD). METHODS: The Agatston coronary artery calcium score (CACS), postdialysis body composition using bioimpedance analysis, single-pool Kt/Vurea and predialysis ß2-MG at baseline were assessed and followed up for 3 years in patients undergoing HD. We performed logistic regression analyses for a CACS ≥400 and Cox proportional hazard analyses for all-cause and cardiovascular mortality. RESULTS: The study involved 338 patients with a median age of 67 (56-74) years, dialysis duration of 70 (33-141) months and diabetes prevalence of 39.1% (132/338). Patients with a CACS ≥400 (n = 222) had significantly higher age, dialysis duration, male prevalence, diabetes prevalence, C-reactive protein, predialysis ß2-MG, OH, extracellular water/total body water and overhydration/extracellular water (OH/ECW) but significantly lower Kt/Vurea than patients with a CACS <400 (n = 116) (p < .05). OH/ECW, Kt/Vurea and predialysis ß2-MG were significant predictors of a CACS ≥400 (p < .05) after adjusting for age, dialysis duration, serum phosphate and magnesium. In all patients, cut-off values of OH/ECW, Kt/Vurea and predialysis ß2-MG for a CACS ≥400 were 16%, 1.74 and 28 mg/L, respectively. After adjusting for dialysis duration, OH/ECW ≥16%, Kt/Vurea ≥1.74 and ß2-MG ≥28 mg/L were significant predictors of 3-year all-cause mortality but not 3-year cardiovascular mortality. CONCLUSION: Higher OH/ECW, higher predialysis ß2-MG and lower Kt/Vurea values are significant risk factors for a CACS ≥400 and 3-year all-cause mortality in patients undergoing maintenance HD.

Early arteriovenous fistula failure associated with mortality and major adverse cardiovascular events in patients undergoing incident hemodialysis.

BACKGROUND: Arteriovenous fistula (AVF) patency is important for patients undergoing hemodialysis. The association between early AVF failure and the prognosis, including all-cause mortality and major adverse cardiovascular events (MACE), has not been fully investigated. The present study was performed to investigate the association between early AVF failure and 3-year mortality, cardiovascular disease (CVD) mortality, and MACE. METHODS: We analyzed 358 patients who started hemodialysis in our institution from October 2008 to February 2020. We defined early AVF failure as cases requiring percutaneous transluminal angioplasty or reoperation within 1 year after AVF surgery. The patients were divided into two groups according to the presence or absence of early AVF failure, and the prognosis of each group was examined. The association between early AVF failure and outcomes (3-year all-cause mortality, CVD mortality, and MACE) was determined using Cox proportional hazards regression analysis. RESULTS: During the 3-year follow-up, 75 (20.9%) patients died (cardiovascular death: n = 39) and 145 patients developed MACE. According to the multivariable analysis, the early AVF failure group had a significantly higher risk of 3-year all-cause mortality (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.09-1.83; p = 0.009), CVD mortality (HR, 1.54; 95% CI, 1.29-2.08; p < 0.001), and MACE (HR, 1.68; 95% CI, 1.25-2.26; p < 0.001). When the patients were stratified by age, early AVF failure was associated with 3-year all-cause mortality in all groups except for the younger group (<65 years of age). CONCLUSIONS: Early AVF failure was associated with an increased risk of 3-year all-cause mortality, CVD mortality, and MACE.

Membranous nephropathy after multiple Hymenoptera stings: a case report.

An association between Hymenoptera (bee and wasp) stings and nephrotic syndrome has been rarely reported. We report a case of nephrotic syndrome after multiple Hymenoptera stings, and membranous nephropathy was later diagnosed by a kidney biopsy. The patient was a 79-year-old woman who was stung by Hymenoptera at seven sites on her body. A weight gain of 3.7 kg was observed in the patient at 1 week after being stung, and she had considerable edema in both lower extremities. A urine protein concentration of 14.8 g/g creatinine and a serum albumin concentration of 1.7 g/dL led to the diagnosis of nephrotic syndrome. A percutaneous kidney biopsy 8 days after the Hymenoptera stings showed stage I membranous nephropathy. She was in complete remission 1 week after the administration of oral prednisolone 40 mg/day, which was started 14 days after Hymenoptera stings, and had no relapse of nephrotic syndrome. To the best of our knowledge, this is the first report of biopsy-proven membranous nephropathy caused by Hymenoptera stings.

α1- and ß2-Microglobulin reduction ratios and survival in patients on predilution online haemodiafiltration.

AIM: ß2-Microglobulin (ß2-MG) and α1-microglobulin (α1-MG) have molecular weights of 11,800 and 33,000 Da, respectively. We studied the α1-MG and ß2-MG reduction ratios (RRs) and survival in patients on predilution online haemodiafiltration (Pre-OL-HDF). METHODS: Participants were 247 Pre-OL-HDF patients. α1-MG and ß2-MG RRs were assessed at baseline. Kaplan-Meier survival and Cox proportional hazard analyses were used. RESULTS: In 247 patients, the median age was 67 (56-73) years, the dialysis duration was 77 (46-150) months, and the diabetes prevalence was 47.4%. Twenty-two patients died over the 450-day study period. The mortality cut-off values using receiver-operating characteristic curves for the α1-MG and ß2-MG RRs were 20% and 80%, respectively. Survival rates were significantly (p < 0.05) higher in patients with α1-MG RRs ≥20% (n = 134) compared with patients with α1-MG RRs <20% (n = 113) and in patients with ß2-MG RRs ≥80% (n = 87) compared with patients with ß2-MG RRs <80% (n = 160). Cox models adjusting for diabetes and dialysis duration showed that α1-MG RR, ß2-MG RR, and pre- and postdialysis ß2-MG were risk factors for all-cause mortality; however, after additional adjustment for age, sex, and serum albumin, only ß2-MG RR and pre- and postdialysis ß2-MG were significant predictors of mortality (p < 0.05). α1-MG RRs were significantly correlated with ß2-MG RRs (ρ = 0.73, p < 0.0001) and serum albumin levels (ρ = 0.13, p < 0.05). CONCLUSION: In patients on Pre-OL-HDF, α1-MG RRs ≥20% and ß2-MG RRs ≥80% were associated with better survival, ß2-MG RR ≥80% and pre-and postdialysis ß2-MG levels were significant predictors of all-cause mortality, and α1-MG RR ≥20% may predict mortality.

Synergistic Effects of the Geriatric Nutritional Risk Index and the Modified Creatinine Index for Predicting Mortality in Patients on Hemodialysis.

This study aimed to investigate whether a combined estimation of the geriatric nutritional risk index (GNRI) and the modified creatinine index (mCI) provides synergistic information for mortality in patients treated by chronic hemodialysis. We analyzed 499 patients on hemodialysis for five years. We set each cut-off value as the high (≥92) and low (<92) GNRI groups and the high (≥21 mg/kg/day) and low (<21 mg/kg/day) mCI groups, and divided them into four subgroups: G1, high GNRI + high mCI; G2, high GNRI + low mCI; G3, low GNRI + high mCI; and G4, low GNRI + low mCI. The survival rate was evaluated and time-to-event analysis was performed. All-cause death occurred in 142 (28%) patients. Kaplan−Meier curves showed that G2 and G4 had a significantly worse outcome (p < 0.05) than G1 but not G3. Using the multivariable-adjusted model, only G4 was significantly associated with all-cause mortality compared with G1. Our study suggests that the synergistic effects of the GNRI and the mCI are helpful in predicting all-cause mortality. The combination of these indices may be superior to a single method to distinguish patients who are well or moderately ill from potentially severely ill.

Utility of CHA2DS2-VASc Score to Predict Mid-Term Clinical Outcomes in Hemodialysis Patients.

BACKGROUND: The CHA2DS2-VASc score has been widely used to predict stroke in patients with atrial fibrillation (AF). Recently, it was reported that the CHA2DS2-VASc score helps predict cardiovascular disease (CVD) or all-cause mortality in patients with or without AF. However, few reports have examined the association between this score and mortality in hemodialysis (HD) patients. METHODS: We analyzed 557 consecutive patients who initiated HD at our facilities between February 2005 and October 2017. The CHA2DS2-VASc score was calculated at the time of initiation of HD. Patients were then categorized into three groups according to their CHA2DS2-VASc scores: 0-1 (low), 2-3 (intermediate), and 4-9 (high). Multivariate Cox proportional hazards analysis was used to assess independent risk factors for 3-year all-cause mortality. RESULTS: During the 3-year follow-up period, 153 (27.5%) patients died (cardiovascular death: n = 88). According to multivariate analysis, serum albumin (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.43-0.85, p = 0.003), creatinine (HR 0.91, 95% CI 0.84-0.99, p = 0.049), and CHA2DS2-VASc score (HR 1.33, 95% CI 1.20-1.46, p < 0.001) were associated with 3-year all-cause mortality. Compared with patients in the low CHA2DS2-VASc score group, those in the intermediate- and high-score groups had a higher risk for all-cause and CVD mortality (all-cause mortality: HR 1.77, 95% CI 1.23-2.55, p = 0.002 and HR 2.94, 95% CI 1.90-4.53, p < 0.001, respectively; CVD mortality: HR 1.82, 95% CI 1.27-2.59, p = 0.001 and HR 2.85, 95% CI 1.88-4.31, p < 0.001, respectively). CONCLUSION: The CHA2DS2-VASc score is a valuable predictor of 3-year all-cause and CVD mortality in incident HD patients.

Klotho deficiency intensifies hypoxia-induced expression of IFN-α/ß through upregulation of RIG-I in kidneys.

Hypoxia is a common pathway to the progression of end-stage kidney disease. Retinoic acid-inducible gene I (RIG-I) encodes an RNA helicase that recognizes viruses including SARS-CoV2, which is responsible for the production of interferon (IFN)-α/ß to prevent the spread of viral infection. Recently, RIG-I activation was found under hypoxic conditions, and klotho deficiency was shown to intensify the activation of RIG-I in mouse brains. However, the roles of these functions in renal inflammation remain elusive. Here, for in vitro study, the expression of RIG-I and IFN-α/ß was examined in normal rat kidney (NRK)-52E cells incubated under hypoxic conditions (1% O2). Next, siRNA targeting RIG-I or scramble siRNA was transfected into NRK52E cells to examine the expression of RIG-I and IFN-α/ß under hypoxic conditions. We also investigated the expression levels of RIG-I and IFN-α/ß in 33 human kidney biopsy samples diagnosed with IgA nephropathy. For in vivo study, we induced renal hypoxia by clamping the renal artery for 10 min in wild-type mice (WT mice) and Klotho-knockout mice (Kl-/- mice). Incubation under hypoxic conditions increased the expression of RIG-I and IFN-α/ß in NRK52E cells. Their upregulation was inhibited in NRK52E cells transfected with siRNA targeting RIG-I. In patients with IgA nephropathy, immunohistochemical staining of renal biopsy samples revealed that the expression of RIG-I was correlated with that of IFN-α/ß (r = 0.57, P<0.001, and r = 0.81, P<0.001, respectively). The expression levels of RIG-I and IFN-α/ß were upregulated in kidneys of hypoxic WT mice and further upregulation was observed in hypoxic Kl-/- mice. These findings suggest that hypoxia induces the expression of IFN-α/ß through the upregulation of RIG-I, and that klotho deficiency intensifies this hypoxia-induced expression in kidneys.

Xanthine Oxidase Inhibitor Febuxostat Exerts an Anti-Inflammatory Action and Protects against Diabetic Nephropathy Development in KK-Ay Obese Diabetic Mice.

Hyperuricemia has been recognized as a risk factor for insulin resistance as well as one of the factors leading to diabetic kidney disease (DKD). Since DKD is the most common cause of end-stage renal disease, we investigated whether febuxostat, a xanthine oxidase (XO) inhibitor, exerts a protective effect against the development of DKD. We used KK-Ay mice, an established obese diabetic rodent model. Eight-week-old KK-Ay mice were provided drinking water with or without febuxostat (15 µg/mL) for 12 weeks and then subjected to experimentation. Urine albumin secretion and degrees of glomerular injury judged by microscopic observations were markedly higher in KK-Ay than in control lean mice. These elevations were significantly normalized by febuxostat treatment. On the other hand, body weights and high serum glucose concentrations and glycated albumin levels of KK-Ay mice were not affected by febuxostat treatment, despite glucose tolerance and insulin tolerance tests having revealed febuxostat significantly improved insulin sensitivity and glucose tolerance. Interestingly, the IL-1ß, IL-6, MCP-1, and ICAM-1 mRNA levels, which were increased in KK-Ay mouse kidneys as compared with normal controls, were suppressed by febuxostat administration. These data indicate a protective effect of XO inhibitors against the development of DKD, and the underlying mechanism likely involves inflammation suppression which is independent of hyperglycemia amelioration.

Possible involvement of normalized Pin1 expression level and AMPK activation in the molecular mechanisms underlying renal protective effects of SGLT2 inhibitors in mice.

BACKGROUND: Recently, clinical studies have shown the protective effects of sodium glucose co-transporter2 (SGLT2) inhibitors against progression of diabetic nephropathy, but the underlying molecular mechanisms remain unclear. METHODS: Diabetic mice were prepared by injecting nicotinamide and streptozotocin, followed by high-sucrose diet feeding (NA/STZ/Suc mice). The SGLT2 inhibitor canagliflozin was administered as a 0.03% (w/w) mixture in the diet for 4 weeks. Then, various parameters and effects of canagliflozin on diabetic nephropathy were investigated. RESULTS: Canagliflozin administration to NA/STZ/Suc mice normalized hyperglycemia as well as elevated renal mRNA of collagen 1a1, 1a2, CTGF, TNFα and MCP-1. Microscopic observation revealed reduced fibrotic deposition in the kidneys of canagliflozin-treated NA/STZ/Suc mice. Interestingly, the protein level of Pin1, reportedly involved in the inflammation and fibrosis affecting several tissues, was markedly increased in the NA/STZ/Suc mouse kidney, but this was normalized with canagliflozin treatment. The cells showing increased Pin1 expression in the kidney were mainly mesangial cells, along with podocytes, based on immunohistochemical analysis. Furthermore, it was revealed that canagliflozin induced AMP-activated kinase (AMPK) activation concentration-dependently in CRL1927 mesangial as well as THP-1 macrophage cell lines. AMPK activation was speculated to suppress mesangial cell proliferation and exert anti-inflammatory effects in hematopoietic cells. CONCLUSION: Therefore, we can reasonably suggest that normalized Pin1 expression and AMPK activation contribute to the molecular mechanisms underlying SGLT2 inhibitor-induced suppression of diabetic nephropathy, possibly at least in part by reducing inflammation and fibrotic change.

microRNA-200c regulates KLOTHO expression in human kidney cells under oxidative stress.

KLOTHO deficiency is associated with the progression of kidney dysfunction, whereas its overexpression exerts renoprotective effects. Oxidative stress suppresses KLOTHO expression in renal epithelial cells but upregulates microRNA-200c (miR-200c) in human umbilical vein endothelial cells. In this study, we investigated whether oxidative stress-induced miR-200c is implicated in KLOTHO downregulation in human renal tubular epithelium (HK-2) cells. HK-2 cells were stimulated with hydrogen peroxide (H2O2) to examine the effect of oxidative stress. A luciferase reporter containing the KLOTHO 3'-UTR was used to investigate the effect of miR-200c on KLOTHO mRNA metabolism. The expressions of KLOTHO, oxidative stress markers, and miR-200c were determined in human kidney biopsy specimens. H2O2 suppressed KLOTHO expression without a reduction in KLOTHO mRNA levels but upregulated miR-200c expression. Similarly, transfection of a miR-200c mimic reduced KLOTHO levels and luciferase activity without a reduction in KLOTHO mRNA levels. In contrast, transfection of a miR-200c inhibitor maintained KLOTHO expression. Immunofluorescent assay revealed KLOTHO was present in the cytosol and nuclei of HK-2 cells. In human kidney biopsies, KLOTHO expression was inversely correlated with levels of oxidative stress markers (8-hydroxy-2'-deoxyguanosine: ρ = -0.38, P = 0.026; 4-hydroxy-2-hexenal: ρ = -0.35, P = 0.038) and miR-200c (ρ = -0.34, P = 0.043). Oxidative stress-induced miR-200c binds to the KLOTHO mRNA 3'-UTR, resulting in reduced KLOTHO expression.

The Xanthine Oxidase Inhibitor Febuxostat Suppresses the Progression of IgA Nephropathy, Possibly via Its Anti-Inflammatory and Anti-Fibrotic Effects in the gddY Mouse Model.

Recent clinical studies have demonstrated the protective effect of xanthine oxidase (XO) inhibitors against chronic kidney diseases, although the underlying molecular mechanisms remain unclear. However, to date, neither clinical nor basic research has been carried out to elucidate the efficacy of XO inhibitor administration for IgA nephropathy. We thus investigated whether febuxostat, an XO inhibitor, exerts a protective effect against the development of IgA nephropathy, using gddY mice as an IgA nephropathy rodent model. Eight-week-old gddY mice were provided drinking water with (15 µg/mL) or without febuxostat for nine weeks and then subjected to experimentation. Elevated serum creatinine and degrees of glomerular sclerosis and fibrosis, judged by microscopic observations, were significantly milder in the febuxostat-treated than in the untreated gddY mice, while body weights and serum IgA concentrations did not differ between the two groups. In addition, elevated mRNA levels of inflammatory cytokines such as TNFα, MCP-1, IL-1ß, and IL-6, collagen isoforms and chemokines in the gddY mouse kidneys were clearly normalized by the administration of febuxostat. These data suggest a protective effect of XO inhibitors against the development of IgA nephropathy, possibly via suppression of inflammation and its resultant fibrotic changes, without affecting the serum IgA concentration.

Calcium ions function as a booster of chromosome condensation.

Chromosome condensation is essential for the faithful transmission of genetic information to daughter cells during cell division. The depletion of chromosome scaffold proteins does not prevent chromosome condensation despite structural defects. This suggests that other factors contribute to condensation. Here we investigated the contribution of divalent cations, particularly Ca2+, to chromosome condensation in vitro and in vivo. Ca2+ depletion caused defects in proper mitotic progression, particularly in chromosome condensation after the breakdown of the nuclear envelope. Fluorescence lifetime imaging microscopy-Förster resonance energy transfer and electron microscopy demonstrated that chromosome condensation is influenced by Ca2+. Chromosomes had compact globular structures when exposed to Ca2+ and expanded fibrous structures without Ca2+. Therefore, we have clearly demonstrated a role for Ca2+ in the compaction of chromatin fibres.

Purification and characterization of meta-cleavage compound hydrolase from a carbazole degrader Pseudomonas resinovorans strain CA10.

2-Hydroxy-6-oxo-6-(2'-aminophenyl)-hexa-2,4dienoic acid [6-(2'-aminophenyl)-HODA] hydrolase, involved in carbazole degradation by Pseudomonas resinovorans strain CA10, was purified to near homogeneity from an overexpressing Escherichia coli strain. The enzyme was dimeric, and its optimum pH was 7.0-7.5. Phylogenetic analysis showed the close relationship of this enzyme to other hydrolases involved in the degradation of monocyclic aromatic compounds, and this enzyme was specific for 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (6-phenyl-HODA), having little activity toward 2-hydroxy-6-oxohepta-2,4-dienoic acid and 2-hydroxymuconic semialdehyde. The enzyme had a Km of 2.51 microM and k(cat) of 2.14 (s(-1)) for 6-phenyl-HODA (50 mM sodium phosphate, pH 7.5, 25 degrees C). The effect of the presence of an amino group or hydroxyl group at the 2'-position of phenyl moiety of 6-phenyl-HODA on the enzyme activity was found to be small; the activity decreased only in the order of 6-(2'-aminophenyl)-HODA (2.44 U/mg) > 6-phenyl-HODA (1.99 U / mg) > 2-hydroxy-6-oxo-6-(2'-hydroxyphenyl)-hexa-2,4-dienoic acid (1.05 U/mg). The effects of 2'-substitution on the activity were in accordance with the predicted reactivity based on the calculated lowest unoccupied molecular orbital energy for these substrates.

Crystal structure of a histidine-tagged serine hydrolase involved in the carbazole degradation (CarC enzyme).

2-Hydroxy-6-oxo-6-(2(')-aminophenyl)-hexa-2,4-dienoate hydrolases (CarC enzymes) from two carbazole-degrading bacteria were purified using recombinant Escherichia coli strains with the histidine (His)-tagged purification system. The His-tagged CarC (ht-CarC) enzymes from Pseudomonas resinovorans strain CA10 (ht-CarC(CA10)) and Janthinobacterium sp. strain J3 (ht-CarC(J3)) exhibited hydrolase activity toward 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate as the purified native CarC(CA10) did. ht-CarC(J3) was crystallized in the space group I422 with cell dimensions of a=b=130.3A, c=84.5A in the hexagonal setting, and the crystal structure of ht-CarC(J3) was determined at 1.86A resolution. The final refined model of ht-CarC(J3) yields an R-factor of 21.6%, although the electron-density corresponding to Ile146 to Asn155 was ambiguous in the final model. We compared the known structures of BphD from Rhodococcus sp. strain RHA1 and CumD from Pseudomonas fluorescens strain IP01. The backbone conformation of ht-CarC(J3) was better superimposed with CumD than with BphD(RHA1). The side-chain directions of Arg185 and Trp262 residues in the substrate binding pockets of these enzymes were different among these proteins, suggesting that these residues may take a conformational change during the catalytic cycles.