Significant differences between two commonly used bioimpedance methods in hemodialysis patients.

INTRODUCTION: Bioimpedance methods are currently used abundantly in patients on chronic hemodialysis. In this population, their most important role is to determine the level of fluid volume, respectively its intra- and extracellular components. There are several bioimpedance devices on the market. In this project, we compared two frequently used devices: Body Composition Monitor and InBody S10. MATERIALS AND METHODS: We invited patients on chronic hemodialysis who are being treated in our institution. Inclusion criteria were: clinically stable condition, lack of artificial joints, pacemakers, or other implanted metal objects. The examinations were performed just prior to hemodialysis by both methods 5 minutes apart. Patients were examined in the supine position after 15 minutes at rest to stabilize body fluids. Studied parameters were those that are obtainable by both methods: total body water (TBW) (L), extracellular water (ECW) (L) and intracellular water (ICW) (kg), lean tissue mass (LTM) (L), and fat tissue mass (kg). RESULTS: We included 14 participants (aged 64.4 ± 18.0 years). Statistically and clinically significant differences between data from compared devices were observed for all variables. Inbody S10 overestimated TBW by 2.58 ± 2.73 L and ICW by 4.56 ± 2.27 L in comparison to BCM. The highest difference (27%) was measured for LTM and ICW 22%. LTM, fat, and ECW were higher when measured by BCM (LTM by 8.54 ± 6.43 kg, p < 0.001; fat by 3.41 ± 4.22, p = 0.01; ECW by 2.01 ± 0.89 L, p < 0.001). CONCLUSION: The differences between tested devices were significant not only statistically, but also clinically. These two devices cannot be used interchangeably for dry weight setting of hemodialysis patients.

Biomarkers of fibrosis, kidney tissue injury and inflammation may predict severity and outcome of renal ANCA - associated vasculitis.

Background: Activity and chronicity of kidney involvement in ANCA-associated vasculitis (AAV) can be currently reliably evaluated only by kidney biopsy. In this study, we measured a panel of serum and urinary biomarkers collected at the time of kidney biopsy and hypothesized that they could reflect specific histopathological parameters in the biopsy and help to predict prognosis. Methods: We examined a cohort of 45 patients with AAV and 10 healthy controls. Biomarker levels (DKK-3, CD163, EGF, PRO-C6 and C3M) were measured in this study by ELISA. Biopsies were scored with a scoring system for AAV (focal x crescentic x sclerotic x mixed class) and interstitial fibrosis was quantified. Results: Levels of urinary DKK-3, CD163, EGF, PRO-C6 and C3M significantly differed among biopsy classes in AAV, with urinary DKK-3 and PRO-C6 levels being highest in the sclerotic class and lowest in the focal class, urinary CD163 levels highest in the crescentic class and urinary C3M levels highest in the focal class. Moreover, the urinary biomarkers were able to discriminate focal biopsy class from the other classes. Urinary DKK-3, EGF, PRO-C6 and C3M levels measured at the time of biopsy were also significantly related to the extent of fibrosis and to the final kidney function at the end of follow-up. Conclusions: This small pilot study suggests that selected urinary biomarkers of fibrosis and inflammation may reflect changes in the kidney biopsy and be prognostic of kidney outcome in patients with AAV.

Traditional and Disease-Specific Risk Factors for Cardiovascular Events in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A Multinational Retrospective Study.

OBJECTIVE: To investigate the occurrence of cardiovascular events (CVEs) in a large cohort of patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) across the European Union, China, Turkey, Russia, the United Kingdom, and the USA. METHODS: Patients with a definite diagnosis of AAV who were followed for ≥ 3 months and had sufficient documentation were included. Data on myocardial infarction (MI) and stroke were collected retrospectively from tertiary vasculitis centers. Univariate and multivariate Cox regression models were used to estimate hazard ratios (HRs) and 95% CIs. RESULTS: Over a median follow-up of 62.0 months (IQR 22.6-100.0), CVEs (mostly MIs) occurred in 245 (10.7%) of 2286 patients with AAV, with a higher frequency in China and the UK. On multivariate regression analysis, older age (55-64.9 yrs, HR 2.93, 95% CI 1.99-4.31), smoking (HR 1.98, 95% CI 1.48-2.64), Chinese origin (HR 4.24, 95% CI 3.07-5.85), and pulmonary (HR 1.50, 95% CI 1.09-2.06) and kidney (HR 3.02, 95% CI 2.08-4.37) involvement were independent variables associated with a higher occurrence of CVEs. CONCLUSION: We showed that geographic region and both traditional and disease-specific (kidney involvement in particular) factors were independently associated with CVEs. Proper assessment and management of modifiable cardiovascular (CV) risk factors are essential for prevention of CV morbidity in patients with AAV.

Analysis of microRNAs in Small Urinary Extracellular Vesicles and Their Potential Roles in Pathogenesis of Renal ANCA-Associated Vasculitis.

Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) represents an autoimmunity disease characterized by high mortality. For successful treatment, the detailed knowledge of its complex pathogenesis and the set of biomarkers for differential diagnostics are desired. Analysis of molecular content of small urinary extracellular vesicles (uEV) offers the possibility to find markers in the form of microRNAs (miRNAs) and study the pathways involved in pathogenesis. We used next-generation sequencing in the first preliminary study to detect the miRNAs with altered expression in uEVs of patients with AAV in comparison with age-matched controls. We confirmed the results using single-target quantitative polymerase chain reaction tests on different sets of samples and found five miRNAs (miR-30a-5p, miR-31-3p, miR-99a-5p, miR-106b-5p, miR-182-5p) with highly elevated levels in uEVs of patients. We performed the comparison of their targets with the differentially expressed proteins in uEVs of patients included in the first phase. We realized that upregulated miRNAs and proteins in uEVs in AAV patients target different biological pathways. The only overlap was detected in pathways regulating the actin cytoskeleton assembly and thus potentially affecting the glomerular functions. The associations of upregulated miRNAs with pathways that were neglected as components of complex AAV pathogenesis, e.g., the epidermal growth factor receptor signaling pathway, were found.

Endotrophin, a collagen type VI-derived matrikine, reflects the degree of renal fibrosis in patients with IgA nephropathy and in patients with ANCA-associated vasculitis.

BACKGROUND: Renal fibrosis is the hallmark of chronic kidney disease (CKD) and is characterized by an imbalanced extracellular matrix remodelling. Endotrophin (ETP) is a signalling molecule released from collagen type VI (COL VI). ETP can be measured by the PRO-C6 assay, which quantifies the levels of COL VI formation. ETP levels were previously associated with mortality and disease progression in patients with CKD. We hypothesized that serum and urinary ETP levels correlate with the degree of interstitial fibrosis in kidney biopsies from patients with immunoglobulin A nephropathy (IgAN) and patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). METHODS: We examined a cohort of 49 IgAN and 47 AAV patients. A validation cohort of 85 IgAN patients was included. ETP was measured in serum (S-ETP) and urine (U-ETP/Cr) samples, taken on the same day before renal biopsy was performed, using the enzyme-linked immunosorbent assay PRO-C6. The biopsies were evaluated for interstitial fibrosis and tubular atrophy according to the Banff and MEST-C scores. RESULTS: S-ETP and U-ETP/Cr levels correlated with kidney function, increased CKD severity, correlated with the extent of interstitial fibrosis and gradually increased with increasing degree of interstitial fibrosis and tubular atrophy. ETP outperformed the known fibrosis biomarker Dickkopf-3 for discrimination of patients with high fibrotic burden. The association of S-ETP and U-ETP/Cr with the level of kidney fibrosis was confirmed in the validation cohort. CONCLUSIONS: We demonstrated that high levels of circulating and excreted ETP are not only indicative of lower kidney function, but also reflect the burden of fibrosis in the kidneys.

Association of venous thromboembolic events with skin, pulmonary and kidney involvement in ANCA-associated vasculitis: a multinational study.

OBJECTIVE: To investigate the occurrence of venous thromboembolic events (VTE) in a large cohort of patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) across the European Union, Turkey, Russia, UK and North America. METHODS: Patients with a definite diagnosis of AAV who were followed for at least 3 months and had sufficient documentation were included. Data on VTE, including either deep vein thrombosis or pulmonary embolism, were collected retrospectively from tertiary vasculitis centres. Univariate and multivariate regression models were used to estimate odds ratios (ORs) and 95% CIs. RESULTS: Over a median follow-up of 63 (interquartile range: 29, 101) months, VTE occurred in 278 (9.7%) of 2869 AAV patients with a similar frequency across different countries (from 6.3% to 13.7%), and AAV subtype [granulomatosis with polyangiitis: 9.8% (95% CI: 8.3, 11.6%); microscopic polyangiitis: 9.6% (95% CI: 7.9, 11.4%); and eosinophilic granulomatosis with polyangiitis: 9.8% (95% CI: 7.0, 13.3%)]. Most VTE (65.6%) were reported in the first-year post-diagnosis. Multiple factor logistic regression analysis adjusted for sex and age showed that skin (OR 1.71, 95% CI: 1.01, 2.92), pulmonary (OR 1.78, 95% CI: 1.04, 3.14) and kidney [eGFR 15-60 ml/min/1.73 m2, OR 2.86 (95% CI: 1.27, 6.47); eGFR <15 ml/min/1.73 m2, OR 6.71 (95% CI: 2.94, 15.33)] involvement were independent variables associated with a higher occurrence of VTE. CONCLUSION: Two-thirds of VTE occurred during the initial phase of active disease. We confirmed previous findings from smaller studies that a decrease in kidney function, skin involvement and pulmonary disease are independently associated with VTE.

Mass spectrometry-based proteomic exploration of the small urinary extracellular vesicles in ANCA-associated vasculitis in comparison with total urine.

ANCA-associated vasculitis (AAV) is a rare, but potentially severe autoimmune disease, even nowadays displaying increased mortality and morbidity. Finding early biomarkers of activity and prognosis is thus very important. Small extracellular vesicles (EVs) isolated from urine can be considered as a non-invasive source of biomarkers. We evaluated several protocols for urinary EV isolation. To eliminate contaminating non-vesicular proteins due to AAV associated proteinuria we used proteinase K treatment. We investigated the differences in proteomes of small EVs of patients with AAV compared to healthy controls by label-free LC-MS/MS. In parallel, we performed an analogous proteomic analysis of urine samples from identical patients. The study results showed significant differences and similarities in both EV and urine proteome, the latter one being highly affected by proteinuria. Using bioinformatics tools we explored differentially changed proteins and their related pathways with a focus on the pathophysiology of AAV. Our findings indicate significant regulation of Golgi enzymes, such as MAN1A1, which can be involved in T cell activation by N-glycans glycosylation and may thus play a key role in pathogenesis and diagnosis of AAV. SIGNIFICANCE: The present study explores for the first time the changes in proteomes of small extracellular vesicles and urine of patients with renal ANCA-associated vasculitis compared to healthy controls by label-free LC-MS/MS. Isolation of vesicles from proteinuric urine samples has been modified to minimize contamination by plasma proteins and to reduce co-isolation of extraluminal proteins. Differentially changed proteins and their related pathways with a role in the pathophysiology of AAV were described and discussed. The results could be helpful for the research of potential biomarkers in renal vasculitis associated with ANCA.

Tolerance and safety of rapid 2-hour infusion of rituximab in patients with kidney-affecting autoimmune diseases and glomerulonephritides: a single-centre experience.

OBJECTIVE: According to the manufacturer's documentation, rituximab (RTX) should be administered with slow infusion rates to prevent infusion-related adverse events (AEs). Nevertheless, slow infusions are time-consuming and uncomfortable for patients and medical staff. Therefore, faster infusion rates have been studied and proven safe and well tolerated in lymphomas and rheumatoid arthritis (RA). A small amount of data is available for rapid RTX infusions in non-RA autoimmune diseases. METHODS: Beginning in September 2015, all RTX-reated patients in our centre and willing to participate, were switched from slow RTX infusions (4.25 hours, given at least once to all patients) to fast infusions (2 hours). A total of 85 RTX 2-hour infusions was administered to 53 patients with autoimmune diseases with renal involvement and selected primary glomerulonephritides (26 ANCA-associated vasculitis, nine systemic lupus erythematodes, seven membranous nephropathy, five IgM nephropathy and six other autoimmune disease). Most of the patients received chronic corticosteroid therapy. The prednisone equivalent dose median (IQR) was 0.1 (0.0-0.2) mg/kg/day. RESULTS: Rapid RTX infusions were generally well tolerated. Only two infusion-related AEs were recorded: one Common Terminology Criteria for Adverse Events, grade 3, (lower back pain and hypotension followed by chills necessitating methylprednisolone and dipyrone administration) and one grade 1 (subjective intolerance). The AEs frequency does not differ from other studies with rapid RTX infusions in patients with lymphomas and RA. CONCLUSIONS: Our experience supported other published data and provides evidence concerning the safety of non-initial RTX 2-hour infusion which can be administered without raising the infusion-related AEs rate in patients with kidney-affecting autoimmune diseases and glomerulonephritides.

Patients double-seropositive for ANCA and anti-GBM antibodies have varied renal survival, frequency of relapse, and outcomes compared to single-seropositive patients.

Co-presentation with both ANCA and anti-GBM antibodies is thought to be relatively rare. Current studies of such 'double-positive' cases report small numbers and variable outcomes. To study this further we retrospectively analyzed clinical features and long-term outcomes of a large cohort of 568 contemporary patients with ANCA-associated vasculitis, 41 patients with anti-GBM disease, and 37 double-positive patients with ANCA and anti-GBM disease from four European centers. Double-positive patients shared characteristics of ANCA-associated vasculitis (AAV), such as older age distribution and longer symptom duration before diagnosis, and features of anti-GBM disease, such as severe renal disease and high frequency of lung hemorrhage at presentation. Despite having more evidence of chronic injury on renal biopsy compared to patients with anti-GBM disease, double-positive patients had a greater tendency to recover from being dialysis-dependent after treatment and had intermediate long-term renal survival compared to the single-positive patients. However, overall patient survival was similar in all three groups. Predictors of poor patient survival included advanced age, severe renal failure, and lung hemorrhage at presentation. No single-positive anti-GBM patients experienced disease relapse, whereas approximately half of surviving patients with AAV and double-positive patients had recurrent disease during a median follow-up of 4.8 years. Thus, double-positive patients have a truly hybrid disease phenotype, requiring aggressive early treatment for anti-GBM disease, and careful long-term follow-up and consideration for maintenance immunosuppression for AAV. Since double-positivity appears common, further work is required to define the underlying mechanisms of this association and define optimum treatment strategies.