Mass spectrometry-based proteomic analysis of proteins adsorbed by hexadecyl-immobilized cellulose bead column for the treatment of dialysis-related amyloidosis.

BACKGROUND: Dialysis-related amyloidosis (DRA) is a severe complication in end-stage kidney disease (ESKD) patients undergoing long-term dialysis treatment, characterized by the deposition of ß2-microglobulin-related amyloids (Aß2M amyloid). To inhibit DRA progression, hexadecyl-immobilized cellulose bead (HICB) columns are employed to adsorb circulating ß2-microglobulin (ß2M). However, it is possible that the HICB also adsorbs other molecules involved in amyloidogenesis. METHODS: We enrolled 14 ESKD patients using HICB columns for DRA treatment; proteins were extracted from HICBs following treatment and identified using liquid chromatography-linked mass spectrometry. We measured the removal rate of these proteins and examined the effect of those molecules on Aß2M amyloid fibril formation in vitro. RESULTS: We identified 200 proteins adsorbed by HICBs. Of these, 21 were also detected in the amyloid deposits in the carpal tunnels of patients with DRA. After passing through the HICB column and hemodialyzer, the serum levels of proteins such as ß2M, lysozyme, angiogenin, complement factor D and matrix Gla protein were reduced. These proteins acted in the Aß2M amyloid fibril formation. CONCLUSIONS: HICBs adsorbed diverse proteins in ESKD patients with DRA, including those detected in amyloid lesions. Direct hemoperfusion utilizing HICBs may play a role in acting Aß2M amyloidogenesis by reducing the amyloid-related proteins.

Pruritus and protein-bound uremic toxins in patients undergoing hemodialysis: a cross-sectional study.

Background: Patients undergoing hemodialysis frequently experience pruritus; its severity is associated with poor quality of life and mortality. Recent progress in hemodialysis treatment has improved the removal of small- and middle-molecular-weight molecules; however, the removal of protein-bound uremic toxins (PBUTs) remains difficult. It is possible that pruritus is associated with serum PBUTs in patients undergoing hemodialysis. Methods: We conducted a multicenter cross-sectional study in patients undergoing hemodialysis (n = 135). The severity of pruritus was assessed using the 5D-itch scale and medication use. Serum PBUTs, including indoxyl sulfate, p-cresyl sulfate, indole acetic acid, phenyl sulfate, and hippuric acid, were measured using mass spectrometry; the PBUT score was calculated from these toxins using principal component analysis. Univariate and multiple regression analyses were performed to examine independent predictors of pruritus. Results: Pruritus was reported by 62.2%, 21.5%, and 13.3%, 1.5% and 0.7% as 5 (not at all), 6-10, 11-15, 16-20, and 21-25 points, respectively. The PBUT score was higher in patients undergoing dialysis having pruritus than those without pruritus (0.201 [-0.021 to 0.424] vs -0.120 [-0.326 to 0.087]; P = 0.046). The PBUT score was shown to have an association with the presence of pruritus (coefficient 0.498[Formula: see text]0.225, odds ratio: 1.65 [1.06-2.56]; P = 0.027). Conclusion: Uremic pruritus was frequently found and associated with the PBUT score in patients undergoing hemodialysis. Further studies are required to clarify the impact of PBUTs on uremic pruritus and to explore therapeutic strategies in patients undergoing hemodialysis.

Adsorption of Protein-Bound Uremic Toxins Through Direct Hemoperfusion With Hexadecyl-Immobilized Cellulose Beads in Patients Undergoing Hemodialysis.

An accumulation of protein-bound uremic toxins (PBUTs) is one of major reasons for development of uremia-related complications. We examined the PBUT removal ability of a hexadecyl-immobilized cellulose bead (HICB)-containing column for patients undergoing hemodialysis. Adsorption of indoxyl sulfate (IS), a representative PBUT, to HICBs was examined in vitro. The HICB column was used in patients undergoing hemodialysis for direct hemoperfusion with a regular hemodialyzer. The serum IS, indole acetic acid (IAA), phenyl sulfate (PhS), and p-cresyl sulfate (PCS) levels were measured before and after passing the column. HICBs adsorbed protein-free (free) IS in a dose- and time-dependent manner in vitro (55.4 ± 1.4% adsorption of 1 millimolar, 251 µg/mL, IS for 1 h). In clinical studies, passing the HICB-containing column decreased the serum level of free IS, IAA, PhS, and PCS levels significantly (by 34.4 ± 30.0%, 34.8 ± 25.4%, 28.4 ± 18.0%, and 34.9 ± 22.1%, respectively), but not protein-bound toxins in maintenance hemodialysis patients. HICBs absorbed some amount of free PBUTs, but the clinical trial to use HICB column did not show effect to reduce serum PBUTs level in hemodialysis patients. Adsorption treatment by means of direct hemoperfusion with regular hemodialysis may become an attractive blood purification treatment to increase PBUT removal when more effective materials to adsorb PBUTs selectively will be developed.

[Teriparatide:benefit and safety for bone disease in CKD patients undergoing hemodialysis].

Teriparatide, 1-34 parathyroid hormone, is one of effective treatments for osteoporosis. Teriparatide shows an anabolic effect for bone formation, as a result, increases bone mineral density as well as prevention of fractures in the general population. On the other hand, there are a few report about the effect of teriparatide on increase of bone mineral density in maintenance hemodialysis patients. In addition to CKD-MBD, osteoporosis is also an important pathological change in ESRD patients, therefore its safety and efficacy should be discussed in more detail.

Association between warfarin use and incidence of ischemic stroke in Japanese hemodialysis patients with chronic sustained atrial fibrillation: a prospective cohort study.

BACKGROUND: Although generally recommended for atrial fibrillation (AF) in the general population, the efficacy and safety of warfarin in hemodialysis patients remains controversial. Warfarin use in hemodialysis patients may confer an additional risk of bleeding that is not appreciated in patients without renal failure because hemodialysis patients have platelet defects and receive anticoagulation agents during dialysis. The incidence of major bleeding was reported to be higher in Japanese AF patients on warfarin therapy compared to patients in other countries, suggesting that racial differences may influence bleeding tendency. Thus, examining risks and benefits of warfarin therapy in Japanese hemodialysis patients with AF is important. METHODS: In order to determine associations between warfarin use and new ischemic stroke events, major bleeding, and all-cause mortality, a prospective cohort study of 60 Japanese hemodialysis patients with chronic sustained AF was conducted using Cox proportional modeling and propensity score matching. RESULTS: The mean patient age was 68.1 years. During 110 person-years of follow-up, 13 ischemic strokes occurred. After adjusting for CHADS2 score, warfarin use was not associated with a significant reduction in ischemic stroke events [hazard ratio (HR) 3.36; 95 % confidence interval (CI) 0.94-11.23]. Similar results were obtained after propensity score matching (HR 3.36; 95 % CI 0.67-16.66). Warfarin use was not associated with significant increases in major bleeding or all-cause mortality. CONCLUSIONS: These results suggest that warfarin may not prevent ischemic stroke in Japanese hemodialysis patients with chronic sustained AF. Adequately powered studies are needed to determine the risks and benefits of anticoagulation therapy in these patients.

Circulating 1-84 PTH and large C-terminal PTH fragment levels in uremia.

BACKGROUND: The so-called "intact parathyroid hormone (iPTH)" assay detects large C-terminal PTH fragments that are lacking several N-terminal amino acid residues in addition to 1-84 PTH molecules. METHODS: Blood samples were obtained from 65 predialysis patients (male, 35; female, 30) and 109 dialysis patients (male, 73; female, 36). The plasma 1-84 PTH levels were determined by a specific immunoradiometric assay (IRMA). RESULTS: The ratio of 1-84 PTH/iPTH did not show a significant correlation with glomerular filtration rate (GFR) among patients with a GFR of more than 80 ml/min, while it showed a positive correlation with GFR among patients with a GFR of less than 80 ml/min. The ratio of 1-84 PTH/iPTH demonstrated a significant tendency to decrease in the order of patients with normal renal function (0.928 +/- 0.182), those with renal dysfunction (0.836 +/- 0.186; P < 0.05 vs patients with GFR > 80 ml/min [i.e., normal renal function]), and those with maintenance hemodialysis (0.618 +/- 0.123; P < 0.01 vs patients with GFR > 80 ml/min). The plasma levels of 1-84 PTH and conventional iPTH showed a close correlation in dialysis patients. Neither 1-84 PTH levels nor secondary parameters calculated from them showed a better correlation with bone metabolic markers than iPTH levels. CONCLUSIONS: Circulating large C-terminal PTH fragment levels are increased in uremic patients. However, this noninvasive study failed to demonstrate the superiority of the specific 1-84 assay compared with the conventional iPTH assay to evaluate bone metabolism.

LCAT-dependent conversion of prebeta1-HDL into alpha-migrating HDL is severely delayed in hemodialysis patients.

Prebeta1-HDL is a minor HDL subfraction that acts as an efficient initial acceptor of cell-derived free cholesterol. During 37 degrees C incubation, plasma prebeta1-HDL decreases over time due to its conversion to alpha-migrating HDL by lecithin:cholesterol acyltransferase (LCAT). This conversion may be delayed in hemodialysis patients who have decreased LCAT activity. To clarify whether LCAT-dependent conversion of prebeta1-HDL to alpha-migrating HDL is delayed in hemodialysis patients, prebeta1-HDL concentrations were determined in 45 hemodialysis patients and 45 gender-matched control subjects before and after 37 degrees C incubation with and without the LCAT inhibitor. It was found that the baseline prebeta1-HDL concentration in hemodialysis patients was more than twice that in the controls (44.9 +/- 21.4 versus 19.8 +/- 6.7 mg/L apoAI; P < 0.001). After 2-h incubation, the LCAT-dependent decrease in prebeta1-HDL in hemodialysis patients was about one-third of that in the controls (30 +/- 27 versus 97 +/- 17% of baseline; P < 0.01). The LCAT-dependent rate of decrease in prebeta1-HDL levels (DR(prebeta1)) was the same for samples from hemodialysis patients exhibiting normal (> or =1.03 mmol/L) and low HDL-cholesterol levels (32 +/- 32 versus 28 +/- 23% of baseline; NS). DR(prebeta1) was positively correlated with LCAT activity (r = 0.617; P < 0.001). In conclusion, the LCAT-dependent conversion of prebeta1-HDL to alpha-migrating HDL is severely delayed in hemodialysis patients. The impaired catabolism of prebeta1-HDL may accelerate atherosclerosis in hemodialysis patients.