Urinary epidermal growth factor predicts renal prognosis in antineutrophil cytoplasmic antibody-associated vasculitis

Non-invasive biomarkers of disease activity and organ damage in ANCA-associated vasculitis: a systematic review

BACKGROUND

In anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), histopathological assessment of affected tissue is often necessary for diagnosis and assessment of disease extent. There is a requirement for validated non-invasive biomarkers to avoid the need for serial tissue biopsies.

METHODS

A systematic review of scientific databases from 2012 until present was performed to identify studies fulfilling the inclusion criteria. Studies were assessed for quality using the Strengthening the Reporting of Observational Studies in Epidemiology checklist for cohort, case-control and cross-sectional studies and the Risk of Bias Assessment tool for Non-randomised Studies, or the Cochrane Risk of Bias tool 2.0 for randomised controlled trials. A descriptive synthesis of the data for non-invasive (blood-based or urinary) biomarkers of AAV-related disease activity and organ damage was performed.

RESULTS

Twenty-two high quality studies were included. These articles reported the value of blood-based and urinary biomarkers including anti-neutrophil cytoplasmic antibodies, immune cells, complement factors, gene expression profiles, cytokines, chemokines and other proteins in the assessment of disease activity and/or organ damage in patients with AAV. Many of these biomarkers involve the alternative complement pathway, neutrophil activation and macrophage activation.

CONCLUSION

This is the first contemporary systematic review synthesising the value of non-invasive biomarkers of AAV-related disease activity and organ damage. The incorporation of individual markers in combined biomarker profiles might enhance clinical decision-making. Many unmet needs were identified; few studies involve oeosinophilic granulomatosis with polyangiitis and patients with childhood-onset AAV. Further validation of the candidate biomarkers is warranted in large prospective studies to bridge the existing knowledge gaps and apply precision health to systemic vasculitis.

Intraindividual variations of urinary biomarkers in hospitalized children with glomerular diseases: a prospective observational study

This study aimed to assess the intraindividual variations of urinary biomarkers in hospitalized children with glomerular diseases. Hospitalized children with glomerular diseases participated in the study. For each patient, an overnight (9:00 p.m.-7:00 a.m.) urine was collected, followed by a 24-h urine (classified into four distinct periods: morning 7:00 a.m.-12:00 p.m., afternoon 12:00 p.m.-4:00 p.m., evening 4:00 p.m.-9:00 p.m., and overnight 9:00 p.m.-7:00 a.m.). The concentrations of protein, albumin, N-acetyl-beta-D-glucosaminidase, and epidermal growth factor (EGF) were measured and normalized by three correction factors (creatinine, osmolality, or specific gravity, respectively). Additionally, the 2nd overnight urine sample was grouped into different aliquots according to centrifugation, additives, storage temperature, or delayed processing. Twenty (14 boys, 6 girls) children were enrolled, with an average age of 11.3 years. Among the three correction factors, creatinine-normalized biomarkers provided the best agreements among different periods over 24 h. There were significant diurnal variations during 24 h in the concentrations of urinary protein, albumin, N-acetyl-beta-D-glucosaminidase, and EGF (p = 0.001, p = 0.003, p = 0.003, and p = 0.003, respectively). Evening urine overestimated 24-h urinary protein and albumin, while overnight urine underestimated 24-h urinary albumin. Urinary EGF showed low variability within a day or between the 2 days (coefficients of variation 10.2% and 10.6%, respectively) and excellent agreements (intraclass correlation coefficients > 0.9) with 24-h urinary concentration. Furthermore, urinary EGF was not affected by centrifugation, additives, storage temperature, or delayed processing of urine samples (all p > 0.05).  Conclusion: Given the diurnal variations of urinary biomarkers, urine samples should be collected during the same time period in clinical practice if possible. The results also extend the evidence for urinary EGF as a relatively stable biomarker applied in the future clinical practice. What is Known: • Urinary biomarkers have been widely used or discussed in making diagnoses and therapy regimens and estimating the prognosis of pediatric glomerular diseases. It remains unclear whether their levels would be affected by the time of sample collection, processing methods, and storage conditions in hospitalized children with glomerular diseases. What is New: • The levels of both commonly used biomarkers and novel biomarkers exhibited diurnal variations in hospitalized children with glomerular diseases. • Our results extend the evidence for urinary EGF as a relatively stable biomarker applied in the future clinical practice.

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.

Urinary epidermal growth factor predicts complete remission of proteinuria in Chinese children with IgA nephropathy

BACKGROUND

This study investigated the association between urinary epidermal growth factor (EGF) and complete remission (CR) of proteinuria in children with IgA nephropathy (IgAN).

METHODS

We included 108 patients from the Registry of IgA Nephropathy in Chinese Children. The urinary EGF at the baseline and follow-up were measured and normalized by urine creatinine (expressed as uEGF/Cr). The person-specific uEGF/Cr slopes were estimated using linear mixed-effects models for the subset of patients with longitudinal data of uEGF/Cr. Cox models were used to analyze the associations of baseline uEGF/Cr and uEGF/Cr slope with CR of proteinuria.

RESULTS

Patients with high baseline uEGF/Cr were more likely to achieve CR of proteinuria (adjusted HR 2.24, 95% CI: 1.05-4.79). The addition of high baseline uEGF/Cr on the traditional parameters significantly improved the model fit for predicting CR of proteinuria. In the subset of patients with longitudinal data of uEGF/Cr, high uEGF/Cr slope was associated with a higher likelihood of CR of proteinuria (adjusted HR 4.03, 95% CI: 1.02-15.88).

CONCLUSIONS

Urinary EGF may be a useful noninvasive biomarker for predicting and monitoring CR of proteinuria in children with IgAN.

IMPACT

High levels of baseline uEGF/Cr (>21.45 ng/mg) could serve as an independent predictor for CR of proteinuria. The addition of baseline uEGF/Cr on the traditional clinical pathological parameters significantly improved the fitting ability for the prediction of CR of proteinuria. Longitudinal data of uEGF/Cr were also independently associated with CR of proteinuria. Our study provides evidence that urinary EGF may be a useful noninvasive biomarker in the prediction of CR of proteinuria as well as monitoring therapeutic response, thus guiding treatment strategies in clinical practice for children with IgAN.

Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

The Michigan O'Brien Kidney Research Center: transforming translational kidney research through systems biology

Research on kidney diseases is being transformed by the rapid expansion and innovations in omics technologies. The analysis, integration, and interpretation of big data, however, have been an impediment to the growing interest in applying these technologies to understand kidney function and failure. Targeting this urgent need, the University of Michigan O'Brien Kidney Translational Core Center (MKTC) and its Administrative Core established the Applied Systems Biology Core. The Core provides need-based support for the global kidney community centered on enabling incorporation of systems biology approaches by creating web-based, user-friendly analytic and visualization tools, like Nephroseq and Nephrocell, guiding with experimental design, and processing, analysis, and integration of large data sets. The enrichment core supports systems biology education and dissemination through workshops, seminars, and individualized training sessions. Meanwhile, the Pilot and Feasibility Program of the MKTC provides pilot funding to both early-career and established investigators new to the field, to integrate a systems biology approach into their research projects. The relevance and value of the portfolio of training and services offered by MKTC are reflected in the expanding community of young investigators, collaborators, and users accessing resources and engaging in systems biology-based kidney research, thereby motivating MKTC to persevere in its mission to serve the kidney research community by enabling access to state-of-the-art data sets, tools, technologies, expertise, and learning opportunities for transformative basic, translational, and clinical studies that will usher in solutions to improve the lives of people impacted by kidney disease.

Urinary Matrix Metalloproteinase 7 Activated by Oxidative Stress Predicts Kidney Prognosis in Myeloperoxidase-Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Aims: Effective and applicable predictors of end-stage kidney disease (ESKD) are needed for patients with myeloperoxidase-antineutrophil cytoplasmic antibody-associated vasculitis (MPO-AAV) and kidney involvement. We investigated whether urinary matrix metalloproteinase-7 (uMMP7) was associated with kidney injury severity and incident ESKD in MPO-AAV. Results: A prospective two-stage study was conducted in 150 patients with newly diagnosed MPO-AAV in two independent cohorts. uMMP7 was measured on the days of initial and repeat kidney biopsies. In stage I, a higher initial uMMP7 level was associated with a lower estimated glomerular filtration rate (eGFR), higher level of proteinuria, and greater extent of kidney pathologic lesions. This elevated uMMP7 protein level is activated and potentially derived from the enhanced kidney production induced by oxidative stress. In stage II, uMMP7 at initial biopsy was independently associated with the incidence of ESKD over 6 years. The higher uMMP7 group (vs. lower) had an adjusted hazard ratio of 3.79 (95% confidence interval [CI], 1.49-6.09) for ESKD in the test cohort. Findings were similar in the validation cohort. A combination of data from the two cohorts revealed that adding uMMP7 into clinical or clinicopathologic models significantly improved risk discrimination for future ESKD. Innovation: An elevated uMMP7 level in MPO-AAV was independently associated with severe kidney injury and incident ESKD. Conclusions: uMMP7 in MPO-AAV improves identification of patients at risk of ESKD and may enable early and optimized therapy to improve outcomes. Antioxid. Redox Signal. 37, 246-256.

Proteome-Wide Analysis Using SOMAscan Identifies and Validates Epidermal Growth Factor as a Disease Marker of Collagenous Gastritis

Background and Aims

Collagenous gastritis (CG) is a rare disorder characterized by increased subepithelial collagen deposition and inflammatory infiltrates. The mechanisms involved in CG pathogenesis are poorly understood, and no CG-associated biomarkers have been identified. This proteomics study identified serum biomarkers and pathogenic pathways to provide new knowledge about the pathobiology of CG, a disease reported in less than 100 patients.

Methods

Nine serum samples from pediatric patients diagnosed with CG were evaluated using novel aptamer-based proteomic technology and systems biology to generate new knowledge about the complex interactions between the differentially expressed proteins and candidate upstream regulators, using the Ingenuity Pathway Analysis in patients with non-CG and patients with normal gastric biopsies or nongastritis (NG).

Results

SOMAscan analysis identified 63 proteins significantly dysregulated in CG as compared to non-CG or NG patients that converged around enhanced inflammatory response and immune cell migration but reduced vascular functions. Principal component analysis using 15 of those proteins accurately separated the CG cases from the 2 comparator control groups. Using immunoassays, serum epidermal growth factor concentrations in CG patients, a protein involved in collagen production, were confirmed to be significantly lower than those in gastritis/NG patients.

Conclusion

This is the first comprehensive analysis of the proteome in CG patients that reveals metabolic pathways relating inflammation and fibrosis as well as a new potential role of epidermal growth factor as a disease biomarker.

The lupus nephritis management renaissance

Over the past year, and for the first time ever, the US Food and Drug Administration approved 2 drugs specifically for the treatment of lupus nephritis (LN). As the lupus community works toward understanding how to best use these new therapies, it is also an ideal time to begin to rethink the overall management strategy of LN. In addition to new drugs, this must include how to use kidney biopsies for management and not just diagnosis, how molecular technologies can be applied to interrogate biopsies and how such data can impact management, and how to incorporate LN biomarkers into management paradigms. Herein, we will review new developments in these areas of LN and put them into perspective for disease management now and in the future.

Renal-limited ANCA-associated vasculitis during erlotinib treatment for lung carcinoma

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) had clinical success in the treatment of non-small cell lung carcinoma (NSCLC). An effect of this drug on kidney has not been clarified and the occurrence of glomerulonephritis related to EGFR-TKI has rarely been reported. We present the case of a 71-year-old man with NSCLC who developed proteinuria and microscopic hematuria with the rise in a titer of MPO-ANCA, when 2 years and 3 months passed since the initiation of erlotinib, one of oral EGFR-TKI. Two serial biopsies support that ANCA-associated vasculitis may have been modified by the persistent use of erlotinib. We initiated intravenous pulse therapy with methylprednisolone followed by oral prednisone. The proteinuria has decreased and serum CRP was normalized. However, the serum creatinine level and hematuria did not change during the treatment period. While EGFR inhibition is implicated in protective control for glomerulonephritis, it may exacerbate vasculitis. Close monitoring of the kidney function and urinary findings is required during the use of EGFR inhibitors, such as erlotinib, because it may cause renal adverse events.

Systematic Scoring of Tubular Injury Patterns Reveals Interplay between Distinct Tubular and Glomerular Lesions in ANCA-Associated Glomerulonephritis

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis, most frequently presenting as microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA). Acute tubular injury with the presence of tubulitis was previously reported to be of prognostic value in ANCA glomerulonephritis (GN). In particular, distinct tubular injury lesions were associated with the deterioration of kidney function at AAV disease onset, as well as renal resistance to treatment, and higher risk of progression to composite outcome in patients with AAV. To expand our knowledge regarding distinct tubular lesions in AAV, we aimed to describe acute tubular injury patterns in association with glomerular lesions in ANCA GN by systematic histological scoring. Methods: A total number of 48 renal biopsies with confirmed renal involvement of AAV admitted to the University Medical Center Göttingen from 2015 to 2020 were retrospectively examined. By systematic scoring of tubular injury lesions, the association between clinical parameters, laboratory markers, and histopathological findings was explored. Results: We have shown that cellular casts in renal biopsies were frequently observed in the majority of cases with ANCA GN. Furthermore, we showed that tubular epithelial simplification with dilatation correlated with MPA and MPO subtypes, C3c hypocomplementemia, severe renal involvement, and uACR. Red blood cell (RBC) casts were associated with increased levels of C-reactive protein (CRP), leukocyturia, and hematuria. Finally, we found that hyaline casts were associated with an increased fraction of glomeruli with global glomerular sclerosis. Conclusions: Acute tubular injury patterns were correlated with active ANCA GN, whereas tubular injury lesions reflecting the later stages of kidney disease correlated with chronic glomerular lesions. These results suggest an interplay between different renal compartments.

Urinary EGF and MCP-1 and risk of CKD after cardiac surgery

BACKGROUND

Assessment of chronic kidney disease (CKD) risk after acute kidney injury (AKI) is based on limited markers primarily reflecting glomerular function. We evaluated markers of cell integrity (EGF) and inflammation (monocyte chemoattractant protein-1, MCP-1) for predicting long-term kidney outcomes after cardiac surgery.

METHODS

We measured EGF and MCP-1 in postoperative urine samples from 865 adults who underwent cardiac surgery at 2 sites in Canada and the United States and assessed EGF and MCP-1’s associations with the composite outcome of CKD incidence or progression. We used single-cell RNA-Seq (scRNA-Seq) of AKI patient biopsies to perform transcriptomic analysis of programs corregulated with the associated genes.

RESULTS

Over a median (IQR) follow-up of 5.8 (4.2–7.1) years, 266 (30.8%) patients developed the composite CKD outcome. Postoperatively, higher levels of urinary EGF were protective and higher levels of MCP-1 were associated with the composite CKD outcome (adjusted HR 0.83, 95% CI 0.73–0.95 and 1.10, 95% CI 1.00–1.21, respectively). Intrarenal scRNA-Seq transcriptomes in patients with AKI-defined cell populations revealed concordant changes in EGF and MCP-1 levels and underlying molecular processes associated with loss of EGF expression and gain of CCL2 (encoding MCP-1) expression.

CONCLUSION

Urinary EGF and MCP-1 were each independently associated with CKD after cardiac surgery. These markers may serve as noninvasive indicators of tubular damage, supported by tissue transcriptomes, and provide an opportunity for novel interventions in cardiac surgery.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00774137.

FUNDING

The NIH funded the TRIBE-AKI Consortium and Kidney Precision Medicine Project. Yale O’Brien Kidney Center, American Heart Association, Patterson Trust Fund, Dr. Adam Linton Chair in Kidney Health Analytics, Canadian Institutes of Health Research, ICES, Ontario Ministry of Health and Long-Term Care, Academic Medical Organization of Southwestern Ontario, Schulich School of Medicine & Dentistry, Western University, Lawson Health Research Institute, Chan Zuckerberg Initiative Human Cell Atlas Kidney Seed Network.

Perspectives in systems nephrology

Chronic kidney diseases (CKD) are a major health problem affecting approximately 10% of the world’s population and posing increasing challenges to the healthcare system. While CKD encompasses a broad spectrum of pathological processes and diverse etiologies, the classification of kidney disease is currently based on clinical findings or histopathological categorizations. This descriptive classification is agnostic towards the underlying disease mechanisms and has limited progress towards the ability to predict disease prognosis and treatment responses. To gain better insight into the complex and heterogeneous disease pathophysiology of CKD, a systems biology approach can be transformative. Rather than examining one factor or pathway at a time, as in the reductionist approach, with this strategy a broad spectrum of information is integrated, including comprehensive multi-omics data, clinical phenotypic information, and clinicopathological parameters. In recent years, rapid advances in mathematical, statistical, computational, and artificial intelligence methods enable the mapping of diverse big data sets. This holistic approach aims to identify the molecular basis of CKD subtypes as well as individual determinants of disease manifestation in a given patient. The emerging mechanism-based patient stratification and disease classification will lead to improved prognostic and predictive diagnostics and the discovery of novel molecular disease-specific therapies.

Advancing science and education through a novel collaboration platform between the University of Michigan and Peking University Health Science Center

Research in China has been advancing over the past decade with increasing investments from government and private entities. Collaboration with Chinese investigators and those in the United States has also increased as reflected in the growth of scientific papers with Chinese authors. Collaborations are more commonly based on faculty‐to‐faculty relationships which can be challenged by institutional or governmental policies. This paper reports on an institution‐to‐ institution collaboration, the Joint Institute for Translational and Clinical Research initiated in 2010 between the University of Michigan Medical School and Peking University Health Science Center, to enable and support collaborative faculty‐initiated research. Concomitant education and training programs have also been co‐developed. Beginning in 2011, 190 proposals from faculty‐to‐faculty partnerships have been submitted from which 59 have been selected for funding. These projects have involved over 138,000 patient subjects and resulted in 86 peer‐reviewed publications to date. Pilot data has been leveraged to secure $27.3 million dollars of extramural funding outside of China. Faculty and trainee exchanges take place regularly including an annual symposium with mechanisms to link faculty who are seeking partnerships by utilizing each other's complementary strengths and resources. As the collaboration enters its second decade, both institutions believe that the model offers a unique platform to promote faculty‐initiated collaborative research. Next steps include funding studies in prioritized scientific themes, and promoting access to high‐quality cohorts to attract industry partners and to develop sustainable financial models.

Association Between Urinary Epidermal Growth Factor and Renal Prognosis in Lupus Nephritis

OBJECTIVE

To evaluate the role of urinary epidermal growth factor (EGF) as a biomarker of chronic kidney damage in lupus nephritis (LN).

METHODS

A proteomics approach was used to identify urinary EGF as a biomarker of interest in a discovery cohort of patients with LN. The expression of urinary EGF was characterized in 2 large multiethnic LN cohorts, and the association between urinary EGF levels at the time of flare and kidney outcomes was evaluated in a subset of 120 patients with long-term follow-up data. For longitudinal studies, the expression of urinary EGF over time was determined in 2 longitudinal cohorts of patients with LN from whom serial urine samples were collected.

RESULTS

Discovery analysis showed the urinary EGF levels as being low in patients with active LN (median peptide count 8.4, interquartile range [IQR] 2.8-12.3 in patients with active LN versus median 48.0, IQR 45.3-64.6 in healthy controls). The peptide sequence was consistent with that of proEGF, and this was confirmed by immunoblotting. The discovery findings were verified by enzyme-linked immunosorbent assay. Patients with active LN had a significantly lower level of urinary EGF compared to that in patients with active nonrenal systemic lupus erythematosus (SLE), patients with inactive SLE, and healthy kidney donors (each P < 0.05). The urinary EGF level was inversely correlated with the chronicity index of histologic features assessed in kidney biopsy tissue (Spearman's r = -0.67, P < 0.001). Multivariate survival analysis showed that the urinary EGF level was associated with time to doubling of the serum creatinine level (DSCr), a marker of future end-stage kidney disease (ESKD) (hazard ratio 0.88, 95% confidence interval 0.77-0.99, P = 0.045). Patients whose LN symptoms progressed to DSCr and those who experienced progression to ESKD had a lower urinary EGF level at the time of flare, and urinary EGF levels decreased over the 12 months following flare. All patients who experienced progression to ESKD were identified based on a urinary EGF cutoff level of <5.3 ng/mg.

CONCLUSION

Urinary EGF levels are correlated with histologic kidney damage in patients with LN. Low urinary EGF levels at the time of flare and decreasing urinary EGF levels over time are associated with adverse long-term kidney outcomes.

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.

Integrated multi-omics approaches to improve classification of chronic kidney disease

Chronic kidney diseases (CKDs) are currently classified according to their clinical features, associated comorbidities and pattern of injury on biopsy. Even within a given classification, considerable variation exists in disease presentation, progression and response to therapy, highlighting heterogeneity in the underlying biological mechanisms. As a result, patients and clinicians experience uncertainty when considering optimal treatment approaches and risk projection. Technological advances now enable large-scale datasets, including DNA and RNA sequence data, proteomics and metabolomics data, to be captured from individuals and groups of patients along the genotype-phenotype continuum of CKD. The ability to combine these high-dimensional datasets, in which the number of variables exceeds the number of clinical outcome observations, using computational approaches such as machine learning, provides an opportunity to re-classify patients into molecularly defined subgroups that better reflect underlying disease mechanisms. Patients with CKD are uniquely poised to benefit from these integrative, multi-omics approaches since the kidney biopsy, blood and urine samples used to generate these different types of molecular data are frequently obtained during routine clinical care. The ultimate goal of developing an integrated molecular classification is to improve diagnostic classification, risk stratification and assignment of molecular, disease-specific therapies to improve the care of patients with CKD.