Assessment of metabolomic and proteomic biomarkers in detection and prognosis of progression of renal function in chronic kidney disease

Chronic kidney disease (CKD) is part of a number of systemic and renal diseases and may reach epidemic proportions over the next decade. Efforts have been made to improve diagnosis and management of CKD. We hypothesised that combining metabolomic and proteomic approaches could generate a more systemic and complete view of the disease mechanisms. To test this approach, we examined samples from a cohort of 49 patients representing different stages of CKD. Urine samples were analysed for proteomic changes using capillary electrophoresis-mass spectrometry and urine and plasma samples for metabolomic changes using different mass spectrometry-based techniques. The training set included 20 CKD patients selected according to their estimated glomerular filtration rate (eGFR) at mild (59.9±16.5 mL/min/1.73 m2; n = 10) or advanced (8.9±4.5 mL/min/1.73 m2; n = 10) CKD and the remaining 29 patients left for the test set. We identified a panel of 76 statistically significant metabolites and peptides that correlated with CKD in the training set. We combined these biomarkers in different classifiers and then performed correlation analyses with eGFR at baseline and follow-up after 2.8±0.8 years in the test set. A solely plasma metabolite biomarker-based classifier significantly correlated with the loss of kidney function in the test set at baseline and follow-up (ρ = −0.8031; p<0.0001 and ρ = −0.6009; p = 0.0019, respectively). Similarly, a urinary metabolite biomarker-based classifier did reveal significant association to kidney function (ρ = −0.6557; p = 0.0001 and ρ = −0.6574; p = 0.0005). A classifier utilising 46 identified urinary peptide biomarkers performed statistically equivalent to the urinary and plasma metabolite classifier (ρ = −0.7752; p<0.0001 and ρ = −0.8400; p<0.0001). The combination of both urinary proteomic and urinary and plasma metabolic biomarkers did not improve the correlation with eGFR. In conclusion, we found excellent association of plasma and urinary metabolites and urinary peptides with kidney function, and disease progression, but no added value in combining the different biomarkers data

Biomarkers of neurodegeneration and glial activation validated in Alzheimer’s disease assessed in longitudinal cerebrospinal fluid samples of Parkinson’s disease

Aim: Several pathophysiological processes are involved in Parkinson's disease (PD) and could inform in vivo biomarkers. We assessed an established biomarker panel, validated in Alzheimer's Disease, in a PD cohort. Methods: Longitudinal cerebrospinal fluid (CSF) samples from PPMI (252 PD, 115 healthy controls, HC) were analyzed at six timepoints (baseline, 6, 12, 24, 36, and 48 months follow-up) using Elecsys® electrochemiluminescence immunoassays to quantify neurofilament light chain (NfL), soluble TREM2 receptor (sTREM2), chitinase-3-like protein 1 (YKL40), glial fibrillary acidic protein (GFAP), interleukin-6 (IL-6), S100, and total α-synuclein (αSyn). Results: αSyn was significantly lower in PD (mean 103 pg/ml vs. HC: 127 pg/ml, p0.05) and none showed a significant difference longitudinally. We found significantly higher levels of all these markers between PD patients who developed cognitive decline during follow-up, except for αSyn and IL-6. Conclusion: Except for αSyn, the additional biomarkers did not differentiate PD and HC, and none showed longitudinal differences, but most markers predict cognitive decline in PD during follow-up

Cerebrospinal α-Synuclein Oligomers Reflect Disease Motor Severity in DeNoPa Longitudinal Cohort

Background: Tangible efforts have been made to identify biomarkers for Parkinson's disease (PD) diagnosis and progression, with α-synuclein (α-syn) related biomarkers being at the forefront. Objectives: The objectives of this study were to explore whether cerebrospinal fluid (CSF) levels of total, oligomeric, phosphorylated Ser 129 α-synuclein, along with total tau, phosphorylated tau 181, and β-amyloid 1–42 are (1) informative as diagnostic markers for PD, (2) changed over disease progression, and/or (3) correlated with motor and cognitive indices of disease progression in the longitudinal De Novo Parkinson cohort. Methods: A total of 94 de novo PD patients and 52 controls at baseline and 24- and 48-month follow-up were included, all of whom had longitudinal lumbar punctures and clinical assessments for both cognitive and motor functions. Using our in-house enzymelinked immunosorbent assays and commercially available assays, different forms of α-synuclein, tau, and β-amyloid 1–42 were quantified in CSF samples from the De Novo Parkinson cohort. Results: Baseline CSF total α-synuclein was significantly lower in early de novo PD compared with healthy controls, whereas the ratio of oligomeric/total and phosphorylated/total were significantly higher in the PD group. CSF oligomeric-α-synuclein longitudinally increased over the 4-year follow-up in the PD group and correlated with PD motor progression. Patients at advanced stages of PD presented with elevated CSF oligomeric-α-synuclein levels compared with healthy controls. Conclusions: Longitudinal transitions of CSF biomarkers over disease progression might not occur linearly and are susceptible to disease state. CSF oligomeric-α-synuclein levels appear to increase with diseases severity and reflect PD motor rather than cognitive trajectories. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

A database of naturally occurring human urinary peptides and proteins for use in clinical applications

Owing to its availability, ease of collection and correlation with (patho-) physiology, urine is an attractive source for clinical proteomics. However, the lack of comparable datasets from large cohorts has greatly hindered development in this field. Here we report the establishment of a high resolution proteome database of naturally occurring human urinary peptides and proteins - ranging from 800-17,000 Da - from over 3,600 individual samples using capillary electrophoresis coupled to mass spectrometry, yielding an average of 1,500 peptides per sample. All processed data were deposited in an SQL database, currently containing 5,010 relevant unique urinary peptides that serve as classifiers for diagnosis and monitoring of diseases, including kidney and vascular diseases. Of these, 352 have been sequenced to date. To demonstrate the applicability of this database, two examples of disease diagnosis were provided: For renal damage diagnosis, patients with a specific renal disease were identified with high specificity and sensitivity in a blinded cohort of 131 individuals. We further show definition of biomarkers specific for immunosuppression and complications after transplantation (Kaposi's sarcoma). Due to its high information content, this database will be a powerful tool for the validation of biomarkers for both renal and non-renal diseases

Long-term results for post-interventional systemic heparinization following angioplasty of peripheral vessels

Objective: The long-term outcome of percutaneous transluminal angioplasties is mainly determined by restenoses, either by progression of the underlying disease or by intimal hyperplasia. Pharmacological substances on the one hand and the implantation of stents on the other have been developed with the intention of preventing precisely this complication. While patients are treated after PTA of peripheral vessels with different low-molecular-weight heparins, the indication for stent implantation is determined individually rather by experience. The aim of this study was to determine gender-specific risk factors of long-term outcome after percutaneous transluminal angioplasty (PTA) of peripheral vessels with or without stentimplantation. Methods: In the present study, we examined the long-term results of percutaneous transluminal angioplasty (PTA) of peripheral vessels. Between 2007 and 2017, in total, 3,276 patients underwent PTA with or without stent implantation in our clinic. All patients were treated postinterventionally for 48 hours with 25,000 IU heparin (Unfractionated Heparin (UFH), heparinsodium-Braun, 25,000 I.E./5 ml, 2 ml/h) monitored by the partial thromboplastin time and subsequently underwent a control investigation every 6 months. The endpoint of the study was determination of symptomatic stenosis larger than 50% that required reintervention. Results: 239 (68.2% with mean age 68.02 years) male patients and 111 female patients (31.71% with mean age 62.92 years) were evaluated with complete follow-up. A total of 470 PTAs were performed on male patients and 213 on female patients in multiple interventions. The majority of patients at the time of treatment were in stage IIb according to the classification of Fontaine (81.6% of male patients and 68% of females). In our sample, peripheral arterial disease stage III and IV according to Fontaine classification occurred twice as frequently in female patients as in male patients (stage III in 12.6% in female versus 6.1% in male, and stage IV in 18% in female versus 8.9% in males). In both groups, the femoral superficialis artery was most frequently dilated (64 cases, 30% in female and 155 cases, 32.9% in male), followed by the iliacal communis artery (46 cases in female and 99 cases in male, both with 21.5%). A balloon angioplasty of the tibialis anterior and posterior arteries was performed twice as frequently in female patients as in male patients (28 cases with 13.1% of tibialis ant. artery in female versus 32 cases with 6.8% in male patients, and in 17 cases with 7.9% of tibialis post. artery in female versus 16 cases with 3.4% in male patients). In this study, without consideration of gender, patency rates of 79% after 2.5 years, 67% after 5 years, 49% after 7.5 years and 37% after 10 years were determined for PTA without stent implantation. Between the 7th and 10th year in follow-up, the cumulative patency rates for stent implantation was 49%, whereas it was 31% for PTA alone. The results of this study show that the stent assisted PTA`s of comm. artery and external iliacal artery are significantly independent of risk factors better than the femoral vessels, and these in female patients better than in male patients. Male patients do not benefit significantly from stent implantation in the long term. As the COXI and II regression analyses show, gender-linked results are most evident for renal insufficiency and diabetes mellitus, and less pronounced also for the number of open lower leg vessels. Conclusion: Under consideration of gender and risk factors, while male patients with diabetes mellitus, renal insufficiency and/or poor run-off did not benefit from stent implantation in the long-term, female patients with similar risk factors showed higher patency rates after stent therapy. In addition, the long-term results after PTA of femoral superficialis artery and poplitea artery are significantly worse than PTA of the pelvic vessels in both genders

Identification of urinary peptide biomarkers associated with rheumatoid arthritis

Early diagnosis and treatment of rheumatoid arthritis are associated with improved outcomes but current diagnostic tools such as rheumatoid factor or anti-citrullinated protein antibodies have shown limited sensitivity. In this pilot study we set out to establish a panel of urinary biomarkers associated with rheumatoid arthritis using capillary electrophoresis coupled to mass spectrometry. We compared the urinary proteome of 33 participants of the Scottish Early Rheumatoid Arthritis inception cohort study with 30 healthy controls and identified 292 potential rheumatoid arthritis-specific peptides. Amongst them, 39 were used to create a classifier model using support vector machine algorithms. Specific peptidic fragments were differentially excreted between groups; fragments of protein S100-A9 and gelsolin were less abundant in rheumatoid arthritis while fragments of uromodulin, complement C3 and fibrinogen were all increasingly excreted. The model generated was subsequently tested in an independent test-set of 31 samples. The classifier demonstrated a sensitivity of 88% and a specificity of 93% in diagnosing the condition, with an area under the receiver operating characteristic curve of 0.93 (p<0.0001). These preliminary results suggest that urinary biomarkers could be useful in the early diagnosis of rheumatoid arthritis. Further studies are currently being undertaken in larger cohorts of patients with rheumatoid arthritis and other athridities to assess the potential of the urinary peptide based classifier in the early detection of rheumatoid arthritis

The human urinary proteome reveals high similarity between kidney aging and chronic kidney disease.

International audienceAging induces morphological changes of the kidney and reduces renal function. We analyzed the low molecular weight urinary proteome of 324 healthy individuals from 2-73 years of age to gain insight on human renal aging. We observed age-related modification of secretion of 325 out of over 5000 urinary peptides. The majority of these changes were associated with renal development before and during puberty, while 49 peptides were related to aging in adults. We therefore focussed the remainder of the study on these 49 peptides. The majority of these 49 peptides were also markers of chronic kidney disease, suggesting high similarity between aging and chronic kidney disease. Blinded evaluation of samples from healthy volunteers and diabetic nephropathy patients confirmed both the correlation of biomarkers with aging and with renal disease. Identification of a number of these aging-related peptides led us to hypothesize that reduced proteolytic activity is involved in human renal aging. Finally, among the 324 supposedly healthy individuals, some had urinary aging-related peptide excretion patterns typical of an individual significantly older than their actual age. In conclusion, these aging-related biomarkers may allow noninvasive detection of renal lesions in healthy persons and show high resemblance between human aging and chronic kidney disease. This similarity has to be taken into account when searching for biomarkers of renal disease