Effects of blood sample handling procedures on measurable interleukin 6 in plasma and serum

Challenges and Advances in Biomarker Detection for Rapid and Accurate Sepsis Diagnosis: An Electrochemical Approach

Sepsis is a life-threatening condition with high mortality rates due to delayed treatment of patients. The conventional methodology for blood diagnosis takes several hours, which suspends treatment, limits early drug administration, and affects the patient's recovery. Thus, rapid, accurate, bedside (onsite), economical, and reliable sepsis biomarker reading of the clinical sample is an emergent need for patient lifesaving. Electrochemical label-free biosensors are specific and rapid devices that are able to perform analysis at the patient's bedside; thus, they are considered an attractive methodology in a clinical setting. To reveal their full diagnostic potential, electrode architecture strategies of fabrication are highly desirable, particularly those able to preserve specific antibody-antigen attraction, restrict non-specific adsorption, and exhibit high sensitivity with a low detection limit for a target biomarker. The aim of this review is to provide state-of-the-art methodologies allowing the fabrication of ultrasensitive and highly selective electrochemical sensors for sepsis biomarkers. This review focuses on different methods of label-free biomarker sensors and discusses their advantages and disadvantages. Then, it highlights effective ways of avoiding false results and the role of molecular labels and functionalization. Recent literature on electrode materials and antibody grafting strategies is discussed, and the most efficient methodology for overcoming the non-specific attraction issues is listed. Finally, we discuss the existing electrode architecture for specific biomarker readers and promising tactics for achieving quick and low detection limits for sepsis biomarkers.

Circulating IL-6 is associated with disease progression in BRAFwt metastatic melanoma patients receiving anti-PD-1 therapy

AIMS

Despite efficacy of anti-PD-1 blockade in treatment of metastatic melanoma (MM), many patients achieve rapid disease progression (DP). Therefore, the aim of this study is to better define biomarkers for DP by analysing levels of circulating cytokines TGF-β, IFN-γ, IL-6, IL-8 and IL-10 in MM patients prior to anti-PD-1 therapy.

METHODS

Cytokine levels were evaluated before therapy with pembrolizumab in peripheral blood of BRAF wild-type (wt) MM patients by ELISA method.

RESULTS

In this study, we give pretherapy levels for circulating TGF-β, IFN-γ, IL-6, IL-8 and IL-10 in BRAFwt MM patients and analyse them according to metastasis stage (M1a+M1 b, M1c, M1d groups), lactate dehydrogenase (LDH) level and occurrence of DP. Increased IL-6 level was found in M1d group (central nervous system metastasis), while LDH+patients (LDH ≥460 IU/L) have increased IL-6 and IL-8 values that correlate with LDH level. Also, IL-6 correlates with C reactive protein values. Furthermore, patients with DP have significantly higher IL-6 level compared with non-DP patients. Conversely, the other analysed cytokines are similar in investigated groups of MM patients. By receiver operating characteristics curve analysis, pretherapy IL-6 level was found to be a biomarker for the occurrence of DP with cut-off value of 3.02 pg/mL. Patients in M1d stage are prevalent in the group with IL-6 ≥3.02 pg/mL that is characterised with reduced progression-free survival and higher pretherapy IL-8 and LDH.

CONCLUSION

The evidence in this study implies that baseline IL-6 could be a biomarker of DP and poor prognosis in BRAFwt MM patients treated with pembrolizumab.

Estimating the association between systemic Interleukin-6 and mortality in the dialysis population. Re-analysis of the global fluid study, systematic review and meta-analysis

BACKGROUND

Systemic inflammation, measured as circulating Interleukin-6 (IL-6) levels, is associated with cardiovascular and all-cause mortality in chronic kidney disease. However, this has not been convincingly demonstrated in a systematic review or a meta-analysis in the dialysis population. We provide such evidence, including a re-analysis of the GLOBAL Fluid Study.

METHODS

Mortality in the GLOBAL fluid study was re-analysed using Cox proportional hazards regression with IL-6 levels as a covariate using a continuous non-logarithmic scale. Literature searches of the association of IL-6 levels with mortality were conducted on MEDLINE, EMBASE, PyschINFO and CENTRAL. All studies were assessed for risk of bias using the QUIPS tool. To calculate a pooled effect size, studies were grouped by use of IL-6 scale and included in the meta-analysis if IL-6 was analysed as a continuous linear covariate, either per unit or per 10 pg/ml, in both unadjusted or adjusted for other patient characteristics (e.g. age, comorbidity) models. Funnel plot was used to identify potential publication bias.

RESULTS

Of 1886 citations identified from the electronic search, 60 were included in the qualitative analyses, and 12 had sufficient information to proceed to meta-analysis after full paper screening. Random effects meta-analysis of 11 articles yielded a pooled hazard ratio (HR) per pg/ml of 1.03, (95% CI 1.01, 1.03), [Formula: see text]= 81%. When the analysis was confined to seven articles reporting a non-adjusted HR the result was similar: 1.03, per pg/ml (95% CI: 1.03, 1.06), [Formula: see text]=92%. Most of the heterogeneity could be attributed to three of the included studies. Publication bias could not be determined due to the limited number of studies.

CONCLUSION

This systematic review confirms the adverse association between systemic IL-6 levels and survival in people treated with dialysis. The heterogeneity that we observed may reflect differences in study case mix.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO - CRD42020214198.

Thymic function and survival at advance ages in nursing home residents from Southern Italy

BACKGROUND

Immunosenescence is a complex process characterized by an age-related remodelling of immune system. The prominent effects of the immunosenescence process is the thymic involution and, consequently, the decreased numbers and functions of T cells. Since thymic involution results in a collapse of the T-cell receptor (TCR) repertoire, a reliable biomarker of its activity is represented by the quantification of signal joint T-cell receptor rearrangement excision circles (sjTRECs) levels. Although it is reasonable to think that thymic function could play a crucial role on elderly survival, only a few studies investigated the relationship between an accurate measurement of human thymic function and survival at old ages.

METHODS AND FINDINGS

By quantifying the amount sjTRECs by real-time polymerase chain reaction (PCR), the decrease in thymic output in 241 nursing home residents from Calabria (Southern Italy) was evaluated to investigate the relationship between thymic function and survival at old ages. We found that low sjTREC levels were associated with a significant increased risk of mortality at older ages. Nursing home residents with lower sjTREC exhibit a near 2-fold increase in mortality risk compared to those with sjTREC levels in a normal range.

CONCLUSION

Thymic function failure is an independent predictor of mortality among elderly nursing home residents. sjTREC represents a biomarker of effective ageing as its blood levels could anticipate individuals at high risk of negative health outcomes. The identification of these subjects is crucial to manage older people's immune function and resilience, such as, for instance, to plan more efficient vaccinal campaigns in older populations.

Distance-Based All-In-One Immunodevice for Point-of-Care Monitoring of Cytokine Interleukin-6

We report the development of a distance-based paper analytical device combined with a hydrophilic bridge valve (B-dPAD) as a quantitative immunoassay method to monitor human interleukin-6 (IL-6) in human samples. Our device design features (i) a circular sample inlet zone, (ii) a circular capture zone with immobilized anti-IL-6 (anti-Ab₁), and (iii) a detection zone channel coated with methylene blue (MB). Two hydrophilic valves are positioned between these three zones. IL-6 levels were determined quantitatively by measuring the extent of degradation of MB to a colorless product along the length of the detection zone channel. Following method optimization, we obtained a linear range from 0.05 to 25.0 pg/mL (R² = 0.9995) and a detection limit (LOD) of 0.05 pg/mL by the naked-eye readout. This is directly within the clinically relevant range. The system does not require any external instrumentation, and the bridge valves can be easily connected and disconnected by a minimally trained operator. The total analysis time is 35 min, significantly reduced from a typical ELISA assay, which takes around 1 h since the B-dPAD workflow circumvents washing steps. The device was tested for IL-6 quantification in human saliva and urine samples of volunteers, with no significant difference found between our method and the standard clinical laboratory method at 95% confidence levels. Recoveries ranged from 98 to 105% with the highest standard deviation at 3.9%. Our B-dPAD immunodevice is therefore a promising approach for rapid IL-6 monitoring in the context of point-of-care diagnostics and analysis in resource-limited settings.

Rapid Quantum Magnetic IL-6 Point-of-Care Assay in Patients Hospitalized with COVID-19

Interleukin-6 (IL-6) has been linked to several life-threatening disease processes. Developing a point-of-care testing platform for the immediate and accurate detection of IL-6 concentrations could present a valuable tool for improving clinical management in patients with IL-6-mediated diseases. Drawing on an available biobank of samples from 35 patients hospitalized with COVID-19, a novel quantum-magnetic sensing platform is used to determine plasma IL-6 concentrations. A strong correlation was observed between IL-6 levels measured by QDTI10x and the Luminex assay (r = 0.70, p-value < 0.001) and between QDTI80x and Luminex (r = 0.82, p-value < 0.001). To validate the non-inferiority of QDTI to Luminex in terms of the accuracy of IL-6 measurement, two clinical parameters—the need for intensive care unit admission and the need for mechanical intubation—were chosen. IL-6 concentrations measured by the two assays were compared with respect to these clinical outcomes. Results demonstrated a comparative predictive performance between the two assays with a significant correlation coefficient. Conclusion: In short, the QDTI assay holds promise for implementation as a potential tool for rapid clinical decision in patients with IL-6-mediated diseases. It could also reduce healthcare costs and enable the development of future various biomolecule point-of-care tests for different clinical scenarios.

Comparison of Aptamer-Based and Antibody-Based Assays for Protein Quantification in Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

Novel aptamer-based technologies can identify >7000 analytes per sample, offering a high-throughput alternative to traditional immunoassays in biomarker discovery. However, the specificity for distinct proteins has not been thoroughly studied in the context of CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We assessed the use of SOMAscan, an aptamer-based technology, for the quantification of eight immune activation biomarkers and cystatin C among 498 African American Study of Kidney Disease and Hypertension (AASK) participants using immunoassays as the gold standard. We evaluated correlations of serum proteins as measured by SOMAscan versus immunoassays with each other and with iothalamate-measured GFR. We then compared associations between proteins measurement with risks of incident kidney failure and all-cause mortality.

RESULTS

Six biomarkers (IL-8, soluble TNF receptor superfamily member 1B [TNFRSF1B], cystatin C, soluble TNF receptor superfamily member 1A [TNFRSF1A], IL-6, and soluble urokinase-type plasminogen activator receptor [suPAR]) had non-negligible correlations (r=0.94, 0.93, 0.89, 0.85, 0.46, and 0.23, respectively) between SOMAscan and immunoassay measurements, and three (IL-10, IFN-γ, and TNF-α) were uncorrelated (r=0.08, 0.07, and 0.02, respectively). Of the six biomarkers with non-negligible correlations, TNFRSF1B, cystatin C, TNFRSF1A, and suPAR were negatively correlated with measured GFR and associated with higher risk of kidney failure. IL-8, TNFRSF1B, cystatin C, TNFRSF1A, and suPAR were associated with a higher risk of mortality via both methods. On average, immunoassay measurements were more strongly associated with adverse outcomes than their SOMAscan counterparts.

CONCLUSIONS

SOMAscan is an efficient and relatively reliable technique for quantifying IL-8, TNFRSF1B, cystatin C, and TNFRSF1A in CKD and detecting their potential associations with clinical outcomes.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_02_23_CJN11700921.mp3.

Pathophysiology of Circulating Biomarkers and Relationship With Vascular Aging: A Review of the Literature From VascAgeNet Group on Circulating Biomarkers, European Cooperation in Science and Technology Action 18216

Impairment of the arteries is a product of sustained exposure to various deleterious factors and progresses with time; a phenomenon inherent to vascular aging. Oxidative stress, inflammation, the accumulation of harmful agents in high cardiovascular risk conditions, changes to the extracellular matrix, and/or alterations of the epigenetic modification of molecules, are all vital pathophysiological processes proven to contribute to vascular aging, and also lead to changes in levels of associated circulating molecules. Many of these molecules are consequently recognized as markers of vascular impairment and accelerated vascular aging in clinical and research settings, however, for these molecules to be classified as biomarkers of vascular aging, further criteria must be met. In this paper, we conducted a scoping literature review identifying thirty of the most important, and eight less important, biomarkers of vascular aging. Herein, we overview a selection of the most important molecules connected with the above-mentioned pathological conditions and study their usefulness as circulating biomarkers of vascular aging.

Impact of short-term storage of plasma samples on quantitation of ultra-low levels of interleukin-6

Objective

To quantitate plasma interleukin-6 (IL-6) levels in healthy individuals and to clarify how these levels are affected by blood sample handling procedures during short-term storage.

Methods

Ethylenediaminetetraacetic acid (EDTA)-treated plasma samples were simultaneously collected from 14 healthy individuals and stored on ice prior to analysis of the IL-6 levels. White blood cells (WBCs), red blood cells, and platelets were counted immediately after blood collection. IL-6 levels were analyzed every 30 minutes using a commercial electrochemiluminescence immunoassay.

Results

Correlation coefficients between plasma IL-6 levels and WBC counts ranged between 0.605 and 0.554, higher than those for other cell types. The lowest IL-6 value in healthy individuals was estimated at 0.04 pg/mL and the mean values remained under 2 pg/mL over time.

Conclusion

Analysis of IL-6 levels in EDTA-treated plasma samples centrifuged within 1 hour and stored on ice can be performed within 90 minutes of short-term storage if the analytical method has a sensitivity in the range of 10 fg/mL.

A novel case of impaired C-reactive protein response following open-heart surgery: A case report and review of the literature

BACKGROUND

C-reactive protein (CRP) is expected to increase in response to a range of inflammatory stimuli such as infections or extensive tissue trauma.

CASE REPORT

We present a novel case of severely impaired CRP response following NSTEMI, influenza A infection and open-heart surgery in which serum CRP concentrations remained < 1 mg/L during an observational period of 28 days.

CONCLUSION

To our knowledge, no previous publications exists describing patients with a lack of CRP response following cardiothoracic surgery. We believe this to be a novel finding warranting further investigations regarding the etiology and prevalence of this phenomenon.

Assessment of low volume sampling technologies: utility in nonclinical and clinical studies

Background: Low volume sampling technologies have come a long way; however, their uptake has been slow due to logistical and perceived implementation challenges. Additional studies are needed to overcome these barriers. Materials & methods/results: Here we present two studies where different sampling technologies were evaluated to determine the feasibility of their implementation. First, we evaluated pharmacokinetic profiles for anti-gD in rats using three tail bleed sampling methods, glass capillary tubes, Shimadzu MSW2^® and the Neoteryx Mitra^® microsampler. Second, we evaluated two low volume-sampling methods to measure drug levels from patients treated with anti-A therapeutic. This evaluation used whole blood finger pricks for Neoteryx Mitra and plasma from capillary blood using TASSO OnDemand technology to compare results to established venipuncture collection method. Conclusion: These studies evaluate the feasibility and considerations for implementation of different low volume sampling technologies.

Best practice recommendations for the measurement and interpretation of salivary proinflammatory cytokines in biobehavioral research

Despite the integration of salivary inflammatory cytokines into research across the biobehavioral, psychological, clinical, and health-related disciplines, there is little guidance regarding the biospecimen collection, handling, and storage practices that maximize the quality and validity of salivary cytokine data. Furthermore, associations between salivary cytokines and measures related to oral health are rarely assessed and accounted for in studies outside the oral health fields. To address these gaps, we examine the sensitivity of salivary interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor-α (TNF-α) to changes in saliva sample collection technique and cold chain management procedures. Using subsets of saliva samples collected from 150 healthy adults, we measure salivary IL-1β, IL-6, IL-8, TNF-α, and other oral health-related indices (i.e., blood contamination [transferrin], and salivary matrixmallotprotienase-8). In addition to examining changes in cytokine levels associated with sample collection technique and cold chain management procedures, we assess relations between cytokine concentrations and levels of other oral health-related measures. We found that IL-1β, IL-6, and IL-8 were more robust to changes in sample collection and cold chain management procedures than TNF-α, and all cytokines were positively associated with other oral health-related measures. Based on our findings, we recommend analyte-specific guidance for measuring and interpreting salivary cytokine concentrations.

Biomaker evaluation for major adverse cardiovascular event development in patients undergoing cardiac Surgery

Objectives

The postoperative period of cardiac surgery (CS) is associated with the development of major adverse cardiovascular events (MACEs). However, the evaluation of MACE after CS by means of biomarkers is poorly developed. We aimed to evaluate postoperative biomarkers that could be associated with MACE.

Methods

Two Hundred and ten patients who underwent CS were enrolled during the study period. The diagnosis of MACE was defined as the presence of at least one of the following complications: acute myocardial infarction, heart failure, stroke presented during intensive care unit (ICU) stay, and 30-day mortality after CS. High-sensitive troponin T (hs-TnT), C-reactive protein, procalcitonin, interleukin-6, and immature platelet fraction (IPF) were measured on ICU admission and after 24 h. The difference between both measurements (Δ) was calculated to assess their association with MACE. Early infected patients (n=13) after CS were excluded from final analysis.

Results

The most frequent surgery was single-valve surgery (n=83; 38%), followed by coronary artery bypass graft (n=72; 34%). Postoperative MACE was diagnosed in 31 (14.8%) patients. Biomarker dynamics showed elevated values at 24 h compared with those at ICU admission in patients with MACE versus no-MACE. Multivariate analysis showed that ΔIPF (OR: 1.47; 95% CI: 1.110-1.960; p=0.008) and Δhs-TnT (OR: 1.001; 95% CI: 1.0002-1.001; p=0.008) were independently associated with MACE.

Conclusions

These findings suggest that postoperative ΔIPF and Δhs-TnT may be useful biomarkers for the identification of patients at risk of MACE development.

The Key Characteristics of Carcinogens: Relationship to the Hallmarks of Cancer, Relevant Biomarkers, and Assays to Measure Them

The key characteristics (KC) of human carcinogens provide a uniform approach to evaluating mechanistic evidence in cancer hazard identification. Refinements to the approach were requested by organizations and individuals applying the KCs. We assembled an expert committee with knowledge of carcinogenesis and experience in applying the KCs in cancer hazard identification. We leveraged this expertise and examined the literature to more clearly describe each KC, identify current and emerging assays and in vivo biomarkers that can be used to measure them, and make recommendations for future assay development. We found that the KCs are clearly distinct from the Hallmarks of Cancer, that interrelationships among the KCs can be leveraged to strengthen the KC approach (and an understanding of environmental carcinogenesis), and that the KC approach is applicable to the systematic evaluation of a broad range of potential cancer hazards in vivo and in vitro We identified gaps in coverage of the KCs by current assays. Future efforts should expand the breadth, specificity, and sensitivity of validated assays and biomarkers that can measure the 10 KCs. Refinement of the KC approach will enhance and accelerate carcinogen identification, a first step in cancer prevention.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Specialized Cell-Free DNA Blood Collection Tubes Can Be Repurposed for Extracellular Vesicle Isolation: A Pilot Study

Background: Liquid biopsies offer a minimally invasive approach to patient disease diagnosis and monitoring. However, these are highly affected by preprocessing variables with many protocols designed for downstream analysis of a single molecular biomarker. Here we investigate whether specialized blood tubes could be repurposed for the analysis of an increasingly valuable biomarker, extracellular vesicles (EVs). Methods: Blood was collected from three donors into K3-EDTA, Roche, or Streck cell-free DNA (cfDNA) collection tubes and processed using sequential centrifugation either immediately or after storage for 3 days. MicroEV were collected from platelet-poor plasma by 10,000 g centrifugation and NanoEVs isolated using size exclusion chromatography. Particle size and counts were assessed by Nanoparticle Tracking Analysis, protein quantitation by bicinchoninic acid assay (BCA) assay, and dot blotting for blood cell surface proteins. Results: MicroEVs and NanoEVs could be isolated from plasma collected using all three tube types. Major variations were seen with delayed time to processing. Both MicroEV particle number and protein content increased with the processing delay. The NanoEV number did not change with the time-delay but their protein quantity increased. EV-associated proteins predominantly arose from platelets (CD61) and erythrocytes (CD235a). However, leukocyte marker CD45 was only increased in NanoEVs from ethylenediaminetetraacetic acid (EDTA) tubes, suggestive of stabilization of nucleated cells by the specialized blood tubes. Epithelial cell surface marker EpCAM, often used as a marker of cancer, remained the same across conditions in both MicroEV and NanoEV preparations indicating that these EVs were stable with time. Conclusions: Specialized cfDNA collection tubes can be repurposed for MicroEV and NanoEV analysis; however, simple counting or using protein quantity as a surrogate of EV number may be confounded by preanalytical processing. The EVs would be suitable for disease selective EV subtype analysis if the molecular target of interest is not present in blood cells.

Effects of blood sample handling procedures on measurable interleukin 6 in plasma and serum

Introduction

Interleukin‐6(IL‐6) measurement is used as a biomarker in medical diagnosis, therapy, and prognosis in various diseases. However, several pre‐analytical factors may yield a false IL‐6 result. In this study, we set out to investigate the effects of corrected blood sample handling procedures on measurable IL‐6.

Method

EDTA plasma and serum samples were collected from 45 healthy individuals. The participants were divided into three groups to perform different handling procedures. Different centrifugal timing, storage temperature, and time were executed on the samples. The changed trends of IL‐6 levels were analyzed.

Results

At baseline, while the paired plasma and serum IL‐6 values had a good correlation, the plasma levels were higher than serum. In general, the unseparated EDTA plasma kept steady with time. With the increase in storage temperature and time, a more pronounced rise in unseparated serum IL‐6 was observed. Nevertheless, the samples in Group 3 which centrifuged and separated immediately kept stable after a different temperature and longtime storage.

Conclusion

Sample types, centrifugal timing, storage temperature, and time may affect the IL‐6 levels. A standard blood sample handling procedure should be performed to ensure the accuracy and stability of IL‐6 values.