Development, validation, and implementation of a multiplex immunoassay for the simultaneous determination of five cytokines in human serum

Real-Time Signal Analysis with Wider Dynamic Range and Enhanced Sensitivity in Multiplex Colorimetric Immunoassays Using Encoded Hydrogel Microparticles

The simultaneous quantification of multiple proteins is crucial for accurate medical diagnostics. A promising technology, the multiplex colorimetric immunoassay using encoded hydrogel microparticles, has garnered attention, due to its simplicity and multiplex capabilities. However, it encounters challenges related to its dynamic range, as it relies solely on the colorimetric signal analysis of encoded hydrogel microparticles at the specific time point (i.e., end-point analysis). This necessitates the precise determination of the optimal time point for the termination of the colorimetric reaction. In this study, we introduce real-time signal analysis to quantify proteins by observing the continuous colorimetric signal change within the encoded hydrogel microparticles. Real-time signal analysis measures the "slope", the rate of the colorimetric signal generation, by focusing on the kinetics of the accumulation of colorimetric products instead of the colorimetric signal that appears at the end point. By developing a deep learning-based automatic analysis program that automatically reads the code of the graphically encoded hydrogel microparticles and obtains the slope by continuously tracking the colorimetric signal, we achieved high accuracy and high throughput analysis. This technology has secured a dynamic range more than twice as wide as that of the conventional end-point signal analysis, simultaneously achieving a sensitivity that is 4-10 times higher. Finally, as a demonstration of application, we performed multiplex colorimetric immunoassays using real-time signal analysis covering a wide concentration range of protein targets associated with pre-eclampsia.

Development and validation of a pentaplex assay for the identification of antibodies against common viral diseases in cattle

Animal welfare and economic implications of infectious diseases in cattle demand an efficient surveillance as the foundation for control and eradication programmes. Bovine respiratory syncytial virus (BRSV), Parainfluenza virus type 3 (PI3V), Bovine herpes virus-1 (BoHV-1), Bovine viral diarrhoea virus (BVDV), and Enzootic bovine leukosis virus (EBLV) cause common and often underdiagnosed diseases in cattle that are endemic in most countries [1]. A hallmark of individual exposure to a viral pathogen is the presence of antibodies directed towards that virus. The aim of this study was to develop and validate a pentaplex assay to simultaneously detect and quantify antibodies against BRSV, PI3V, BoHV-1, BVDV and EBLV in serum, as an efficient tool to yield epidemiological data. Monoplex assays were initially developed using either complete BRSV or BoHV-1 viral lysates, or recombinant proteins for BVDV, EBLV or PI3V as capture antigens. In addition, 125 serum samples from unvaccinated cattle, which were classified as positive or negative for each of the viruses by commercial ELISA kits, were used for validation. Conditions established for the Luminex monoplex assays were adopted for the pentaplex assay. The accuracy, determined by the area under the ROC curve, was greater than 0.97, and assay diagnostic sensitivities and specificities were over 95 and 90%, respectively, for all antigens. Intra (r) and interassay (R) coefficients of variation were under 10 and 20 %, respectively. Selectivity towards target viruses was shown by binding inhibition assays where unbound viruses reduced fluorescence intensities. Diagnostic agreement for samples analysed simultaneously in the monoplex and multiplex assays was almost perfect. In conclusion, a highly sensitive pentaplex assay was validated for the simultaneous identification of antibodies directed against BVDV, BoHV-1, PI3V, BRSV and EBLV in serum. The developed pentaplex assay complies with performance characteristics established by international guidelines for diagnostic tests and may be used as a tool for the implementation of epidemiological surveillance.

Chemerin as a Potential Marker of Resolution of Inflammation in COVID-19 Infection

Chemerin is one of the specialized pro-resolving mediators that participate in the early phase of inflammation and contribute to the initiation of the pro-resolving response. There is a paucity of data regarding the time course of chemerin during acute infections. We aimed to evaluate the sequence of inflammatory responses in the acute COVID-19 phase throughout onset and resolution of inflammation. We evaluated changes in selected biomarkers in COVID-19 survivors on the 7-day and 28-day follow up. Chemerin was lower in patients with baseline moderate/severe disease at day 7 compared with asymptomatic patients and individuals with mild illness (7265 [5526−9448] vs. 8730 [6888−11,058] pg/mL; p = 0.03). Only in patients with moderate/severe disease, but not in those with mild symptoms, were chemerin concentrations decreased one week after infection onset compared with baseline (7265 [5526−9448] vs. 8866 [6383−10,690] pg/mL; p < 0.05) with a subsequent increase on the 28-day follow up (9313 [7353−11,033] pg/mL; p < 0.05). Resolution of inflammation in the group of moderate/severe SARS-CoV2 infection was associated with increasing serum concentrations of chemerin, contrary to pro-inflammatory cytokines and adipokines (pentraxin 3, TNFα, resistin, leptin). A similar pattern of angiopoietin-2 dynamics may suggest signs of enhanced vascularization as a consequence of acute SARS-CoV2 infection.

Molecular diagnostics in neurotrauma: Are there reliable biomarkers and effective methods for their detection?

To date, a large number of studies are being carried out in the field of neurotrauma, researchers not only establish the molecular mechanisms of the course of the disorders, but are also involved in the search for effective biomarkers for early prediction of the outcome and therapeutic intervention. Particular attention is paid to traumatic brain injury and spinal cord injury, due to the complex cascade of reactions in primary and secondary injury that affect pathophysiological processes and regenerative potential of the central nervous system. Despite a wide range of methods available methods to study biomarkers that correlate with the severity and degree of recovery in traumatic brain injury and spinal cord injury, development of reliable test systems for clinical use continues. In this review, we evaluate the results of recent studies looking for various molecules acting as biomarkers in the abovementioned neurotrauma. We also summarize the current knowledge of new methods for studying biological molecules, analyzing their sensitivity and limitations, as well as reproducibility of results. In this review, we also highlight the importance of developing reliable and reproducible protocols to identify diagnostic and prognostic biomolecules.

Recurrent Severe Subclinical Mastitis and the Risk of HIV Transmission Through Breastfeeding

Subclinical mastitis (SCM) is an important risk factor of postnatal HIV-1 transmission that is still poorly understood. A longitudinal sub-study of the ANRS12174 trial including 270 breastfeeding mothers in Lusaka, Zambia measured sodium (Na⁺) and potassium (K⁺) in archived paired breast milk samples collected at week 14, 26 and 38 postpartum to determine cumulative incidence of SCM and the effects of recurrent severe SCM on HIV-1 shedding in breast milk. A nested retrospective cohort study including 112 mothers was also done to determine longitudinal effects of SCM on four pro-inflammatory cytokines; IL6, IL8, IP10 and RANTES. The cumulative incidence for any SCM (Na⁺/K⁺ ratio > 0.6) and severe SCM (Na⁺/K⁺ ratio > 1) were 58.6% (95%CI: 52.7 – 64.5) and 27.8% (95%CI: 22.5 – 33.1), respectively. In majority of affected mothers (51.4%) severe SCM was recurrent. Both breasts were involved in 11.1%, 33.3% and 70% of the mothers with a single episode, 2 and 3 episodes respectively. In affected breasts, an episode of severe SCM resulted in steep upregulation of the four cytokines considered (IL8, IP10, RANTES and IL6) compared to: before and after the episode; contralateral unaffected breasts; and SCM negative control mothers. Recurrent severe SCM significantly increased the odds of shedding cell-free HIV-1 in breast milk (OR: 5.2; 95%CI: 1.7 – 15.6) whereas single episode of severe SCM did not (OR: 1.8; 95%CI: 0.8 – 4.2). A Na⁺/K⁺ ratio > 1 indicative of severe SCM is an excellent indicator of breast inflammation characterized by a steep, localized and temporal upregulation of several pro-inflammatory cytokines that favor HIV-1 shedding in mature breast milk and may facilitate postnatal HIV-1 transmission through breastfeeding.

Alzheimer's disease: a step closer to understanding type 3 diabetes in African Americans

Alzheimer's disease (AD) is the fourth leading cause of death in the United States and the most common cause of adult-onset dementia. Recent results suggest an increased prevalence and severity in African Americans compared to Caucasians. Our understanding of the potential mechanism(s) underlying this ethnicity difference is limited. We previously described ethnicity-related differences in levels of neurodegenerative proteins and cytokines/chemokines in the BA21 region of African Americans and Caucasians with AD. Here, similar multiplex assays were used to examine those endpoints in patient postmortem cerebrospinal fluid (CSF). Additionally, we measured levels of C-peptide, ghrelin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, PAI-1, resistin, and visfatin using a human diabetes 10-plex assay. The cytokine and chemokine assays revealed that levels of 26 chemokines or cytokines differed significantly with ethnicity, and three of those were significantly associated with gender. The neurodegenerative disease panel indicated that levels of soluble RAGE were significantly elevated in African Americans compared to Caucasians. All measures in the diabetes disease panel assay were significantly elevated in African Americans: ghrelin, GIP, GLP-1, glucagon, insulin, and visfatin. Through peripheral sample analysis, these results provide further evidence that ethnicity is critically involved in the manifestation of AD.

The Impacts of Surgery and Intracerebral Electrodes in C57BL/6J Mouse Kainate Model of Epileptogenesis: Seizure Threshold, Proteomics, and Cytokine Profiles

Intracranial electroencephalography (EEG) is commonly used to study epileptogenesis and epilepsy in experimental models. Chronic gliosis and neurodegeneration at the injury site are known to be associated with surgically implanted electrodes in both humans and experimental models. Currently, however, there are no reports on the impact of intracerebral electrodes on proteins in the hippocampus and proinflammatory cytokines in the cerebral cortex and plasma in experimental models. We used an unbiased, label-free proteomics approach to identify the altered proteins in the hippocampus, and multiplex assay for cytokines in the cerebral cortex and plasma of C57BL/6J mice following bilateral surgical implantation of electrodes into the cerebral hemispheres. Seven days following surgery, a repeated low dose kainate (KA) regimen was followed to induce status epilepticus (SE). Surgical implantation of electrodes reduced the amount of KA necessary to induce SE by 50%, compared with mice without surgery. Tissues were harvested 7 days post-SE (i.e., 14 days post-surgery) and compared with vehicle-treated mice. Proteomic profiling showed more proteins (103, 6.8% of all proteins identified) with significantly changed expression (p < 0.01) driven by surgery than by KA treatment itself without surgery (27, 1.8% of all proteins identified). Further, electrode implantation approximately doubled the number of KA-induced changes in protein expression (55, 3.6% of all identified proteins). Further analysis revealed that intracerebral electrodes and KA altered the expression of proteins associated with epileptogenesis such as inflammation (C1q system), neurodegeneration (cystatin-C, galectin-1, cathepsin B, heat-shock protein 25), blood–brain barrier dysfunction (fibrinogen-α, serum albumin, α2 macroglobulin), and gliosis (vimentin, GFAP, filamin-A). The multiplex assay revealed a significant increase in key cytokines such as TNFα, IL-1β, IL-4, IL-5, IL-6, IL-10, IL12p70, IFN-γ, and KC/GRO in the cerebral cortex and some in the plasma in the surgery group. Overall, these findings demonstrate that surgical implantation of depth electrodes alters some of the molecules that may have a role in epileptogenesis in experimental models.

The Potential Impact of Salivary IL-1 on the Diagnosis of Periodontal Disease: A Pilot Study

The aim of this study was to identify inflammatory cytokines as salivary biomarkers for periodontal disease. The subjects were 33 Korean adults aged 23 to 71 years. Using a multiplexed bead immunoassay called Luminex, the levels of inflammatory cytokines related to periodontal disease were evaluated. Oral examination for periodontal disease and gingival bleeding was conducted. With these two independent variables, differences in inflammatory cytokines were analyzed by an independent t-test and age-adjusted ANCOVA. Among the subjects, 21 had periodontal disease and 12 were healthy subjects. The gingival bleeding status was classified into low and high levels. Among 13 inflammatory cytokines in saliva, IL-1α, IL-1β, IL-4, IL-8, CCL2/MCP-1, CCL3/MIP-1α, and TNF-α were found to be significant biomarkers within the standard curve. The quantity of IL-1β was increased in subjects with high levels of gingival bleeding. IL-1α levels were increased in subjects with periodontal disease. After adjusting for age, the significant biomarkers for gingival bleeding and periodontal disease were IL-1β and IL-1α, respectively. Using the receiver operating characteristic (ROC) curve, IL-1β was confirmed as a significant biomarker. The sensitivity and specificity of IL-1β for predicting periodontitis were 88.24% and 62.5%, respectively. Therefore, IL-1 was found to be a significant biomarker for periodontal disease, and it could be used in the diagnosis of periodontal disease using saliva.

Comparison of multiplex cytokine assays in a pediatric cohort with epilepsy

Background

Multiplex analyses allow for detection of dozens of cytokines/chemokines in small sample volumes. Although several commercially available assay kits are available, there are no comparative data in plasma measurements among pediatric or epilepsy cohorts.

New method

Cohort study of 38 children with epilepsy. We evaluated plasma levels of cytokines/chemokines using three different assays: Luminex® xMAP high-sensitivity (HS) and standard-sensitivity (SS) assays, and Meso-Scale Discovery (MSD). We calculated recovery rates of each analyte, correlation coefficients between assays, and level of agreement between measurements. We repeated analyses in a subset of samples after a single freeze-thaw cycle.

Results

Among ten analytes common to all assays, HS had high recovery (<15% of values extrapolated or out-of- range [OOR]) for all analytes, SS for 50%, and MSD for 40%. While several analytes had a high correlation between assays, Bland-Altman plots demonstrated assays were not interchangeable. For most analytes, a single freeze-thaw cycle decreased cytokines/chemokine measurements. There was good correlation of measurements after a freeze-thaw cycle with acceptable agreement between measurements for six of 13 (46%) analytes using HS, one of 9 (11%) for SS, and none for MSD.

Comparison with existing methods

HS assays may optimize yield in plasma for proteins of particular interest in epilepsy research, limit values extrapolated beyond the standard curve, and improve precision compared to other SS and MSD assays.

Conclusion

Our results demonstrate assay choice may be critical to study results and support the need for a standardized approach to biomarker assessment across epilepsy research and other domains.

Stability of interleukin-1β, -4, -6, -8, -10, -13, interferon-γ and tumor necrosis factor-α in human sera after repetitive freeze-thaw cycles and long storage

INTRODUCTION

Cytokines (CKs) are one of the key components of the molecular network modulating multiple immunological interactions. Within such biological systems, CKs functions are associated with several processes, thus quantification of these analytes in serum samples, as well as a faithful determination of its concentration, are crucial for the translational aspect of many studies.

AIM

This study is focused on the evaluation of the effects of storage duration and multiple freeze-thaw cycles on CKs stability.

MATERIALS AND METHODS

Serum samples were obtained from 24 healthy participants. Samples were prospectively stored at 4 °C for 1-7 and 30 days, and also underwent multiple freeze-thaw cycles. Afterwards, CK levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Among the 8 examined CKs all of them showed significant degradation (determined with the two-way ANOVA and post-hoc test) after 4 days of sample storage at 4 °C. Serum were affected by freezing at -20 °C and thawing, and 2 of CKs (IL-1β and IL-8) showed significant concentration decrease after following 2 freeze-thaw cycles. It has been also determineded that CKs in serum samples after multiple freeze-thaw cycles had better stability, when samples were stored at -80 °C (compared to storage at -20 °C).

CONCLUSIONS

This study demonstrates that long storage at 4 °C, as well as multiple freeze-thaw cycles of serum samples, must be avoided and CK concentrations should be measured immediately after sample collection.

Performance of the QPLEX™ Alz plus assay, a novel multiplex kit for screening cerebral amyloid deposition

Background

Alzheimer’s disease (AD) is an irreversible neurodegenerative disease characterized by the hallmark finding of cerebral amyloid deposition. Many researchers have tried to predict the existence of cerebral amyloid deposition by using easily accessible blood plasma samples, but the effectiveness of such strategies remains controversial.

Methods

We developed a new multiplex kit, the QPLEX™ Alz plus assay kit, which uses proteomics-based blood biomarkers to prescreen for cerebral amyloid deposition. A total of 300 participants who underwent Pittsburgh compound B (PiB)-positron emission tomography (PET) which allows imaging of cerebral amyloid deposition were included in this study. We compared the levels of QPLEX™ biomarkers between patients who were classified as PiB-negative or PiB-positive, regardless of their cognitive function. Logistic regression analysis followed by receiver operating characteristic (ROC) curve analysis was performed. The kit accuracy was tested using a randomized sample selection method.

Results

The results obtained using our assay kit reached 89.1% area under curve (AUC) with 80.0% sensitivity and 83.0% specificity. Further validation of the QPLEX™ Alz plus assay kit using a randomized sample selection method showed an average accuracy of 81.5%.

Conclusions

Our QPLEX™ Alz plus assay kit provides preliminary evidence that it can be used as blood marker to predict cerebral amyloid deposition but independent validation is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-020-00751-x.

ELISA versus LUMINEX assay for measuring mouse metabolic hormones and cytokines: sharing the lessons I have learned

Enzyme-linked immunosorbent assay (ELISA) has long been the standard for quantitative analysis of metabolic hormones and cytokines. LUMINEX multiplex bead array assays were developed as cost- and time-effective alternatives to ELISA, but they are the only cost- and time-effective if they provide informative data. Here, I show that using half-volume of reagents for an adiponectin single-plex LUMINEX assay and a 6-plex LUMINEX xMAP mouse metabolic bead assay, produces reliable data and increases assay cost-effectiveness. I provide direct comparisons between LUMINEX assay and ELISA for quantitation of mouse leptin and insulin, and evaluate glucagon, GLP-1, IL-6, and TNFα data obtained using the 6-plex LUMINEX assay for a high-fat diet-induced obesity study. Good correlations between assays were obtained for fasting leptin and non-fasting insulin. However, the LUMINEX assay proved unsuitable for quantitating fasting insulin. ELISA proved suitable for quantitating fasting male, but not female, insulin. The LUMINEX assay gave lower values for leptin and higher values for insulin, compared with ELISA. The mouse metabolic LUMINEX assay proved unsuitable for quantitating glucagon, GLP-1, IL-6, and TNFα, due to undetectable levels in most fasting and non-fasting plasma. Overall, quantitative leptin levels were the only reliable data obtained from the mouse metabolic LUMINEX assay.

Increased inflammation in BA21 brain tissue from African Americans with Alzheimer's disease

Chronic neuroinflammation is strongly associated with AD and altered peripheral and central levels of chemokines and cytokines have been frequently described in those with AD. Given the increasing evidence of ethnicity-related differences in AD, it was of interest to determine if those altered chemokine and cytokine levels are ethnicity-related. Because African Americans exhibit a higher incidence of AD and increased symptom severity, we explored chemokine and cytokine concentrations in post-mortem brain tissue from the BA21 region of African Americans and Caucasians with AD using multiplex assays. IL-1β, MIG, TRAIL, and FADD levels were significantly increased in African Americans while levels of IL-3 and IL-8 were significantly decreased. Those effects did not interact with gender; however, overall levels of CCL25, CCL26 and CX3CL1 were significantly decreased in women. The NLRP3 inflammasome is thought to be critically involved in AD. Increased activation of this inflammasome in African Americans is consistent with the current results.

Thermal stability of cytokines: A review

BACKGROUND

The role of cytokines in various disease states is a burgeoning field of academic study and clinical application, however there are no consensus documents on how certain cytokines should be stored prior to quantification. This information is especially of interest to researchers assembling a biobank or clinicians who have to transport specimens to a different location in order to be tested.

OBJECTIVE

To review the literature and synthesize prior findings on cytokine storage and freeze/thaw stability.

DESIGN

We searched PubMed for articles related to cytokine storage stability. All articles were analyzed for cytokines studied, source of reported cytokine concentration (i.e., human whole blood or serum, concentrations from other species or bodily sources were excluded), and reported statistical results.

RESULTS

We identified and synthesized results of 23 peer-reviewed articles which published data on the storage and freeze/thaw stability of 33 different cytokines and chemokines.

CONCLUSION

There is a wide variety of reported cytokine storage and freeze/thaw stability. Interleukin-6 and tumor necrosis factor alpha are the most widely studied cytokines in regard to temperature stability. In a few cytokines, a clear consensus can be reached as to storage safety at particular temperatures, but in most, more research needs to be done and we advise the clinician or researcher to use caution in interpreting cytokine concentration results after a long period of storage or several freeze/thaw cycles.

Interleukin-1beta and Caspase-3 expression serve as independent prognostic markers for metastasis and survival in oral squamous cell carcinoma

BACKGROUND

The Indian subcontinent has the highest incidence and prevalence of oral squamous cell carcinoma (OSCC). Inflammation and apoptosis are two emerging hall marks of cancer that might play a significant role in tumorigenesis and metastasis. Concurrent expression of proinflammatory cytokine (IL-1β) and executioner caspase (Caspase-3) in same OSCC tissue samples has not been reported in an Indian population.

OBJECTIVES

The present study aimed to evaluate the immunohistochemical expression of IL-1β and Caspase-3 in same OSCC tissue samples with clinicopathological correlation and survival analysis in Indian population.

METHODS

A retrospective study was conducted utilizing 40 formalin fixed paraffin embedded histologically diagnosed cases of OSCC comprising of 20 metastatic OSCC and 20 non-metastatic OSCC.

RESULTS

Increased expression of IL-1β and Caspase-3 were observed in metastatic OSCC. Correlation of expression of IL-1β and Caspase-3 with clinicopathological parameters revealed a significant association between these markers and staging, nodal status and site of the lesion.

CONCLUSION

Over expression of IL-1β and Caspase-3 was associated with advanced stage and poor survival of the patient. IL-1β overexpression showed significantly lower disease-free survival and disease specific survival as well. Overexpression of IL-1β and Caspase-3 in incisional OSCC biopsies could be considered for predicting metastasis and survival outcome.

Plasma cytokine levels and the presence of colorectal cancer

Background/Aims

Cancer-related activation of cytokine networks are central aspects of tumor development. The goal of the study was to examine the possibility of plasma cytokines for the screening of colorectal cancer (CRC).

Methods

We carried out a multicenter, hospital-based case-control study in 66 adult Japanese patients with CRC and 87 healthy adult Japanese. A multiplex bead array immunoassay was used to examine 27 different plasma cytokines. Their association with the presence of CRC was evaluated by logistic regression analysis after adjusting for potential confounding factors.

Results

Thirteen plasma cytokines were notably associated with the presence of CRC (p< 0.05). Receiver operating characteristic analysis revealed that the combinatorial assessment of some of these plasma cytokines showed “good” capability for discriminating between CRC patients and control subjects (area under the curve (AUC): 0.819 for the combination of IL-9, Eotaxin, G-CSF, and TNF-α; 0.832 for the combination of IL-4, IL-8, Eotaxin, IP-10, and TNF-α). Individual cytokine assessments presented lower AUCs (0.657–0.755) than the combinatorial cytokine assessments.

Conclusions

The levels of several plasma cytokines varied significantly between CRC patients and control subjects, suggesting the possibility of differentially expressed plasma cytokines as potential biomarkers for detecting the presence of CRC. Our results should be validated in other populations.

Comparing Flow Cytometry QBeads PlexScreen Assays with Other Immunoassays for Determining Multiple Analytes

Immunoassays, utilizing the affinity of antibodies to their antigens, are powerful techniques and have been widely used for quantifying analytes, such as cytokines, in biological samples in the clinic and in drug discovery. Various immunoassays have been developed to fit for different purposes. Recently, bead-based flow cytometry assays have emerged as interesting options for multiplex quantification of analytes. In this study, we compared high-throughput flow cytometry multiplex iQue QBeads PlexScreen assays with several other commonly used immunoassays, including MSD, Luminex, ELISA, HTRF, and AlphaLISA assays. Head-to-head comparisons of quantification data of the following cytokines were made: (1) IL-2, IL-4, IL-6, IL-13, IL-17A, IFNγ, KC/GRO, RANTES, and TNFα in mouse bronchoalveolar lavage fluid samples; (2) IL-10 and TNFα in supernatants from a THP-1 cell assay; (3) IL-6, IL-10, IL-12p70, and TNFα in supernatants from a human monocyte-derived dendritic cell assay; and (4) IL-2 in supernatants from a human CD4+ cell assay. The results demonstrated a good assay correlation between the iQue and the compared assays for the cytokine studied. Although overall good assay correlations were observed, our results showed that the iQue assay generated different absolute cytokine values for some cytokines in the same sample sets compared with other assays.

Plasma proprotein-convertase-subtilisin/kexin type 9 (PCSK9) and cardiovascular events in type 2 diabetes

AIM

To investigate whether plasma concentrations of proprotein-convertase-subtilisin/kexin type 9 (PCSK9) were associated with cardiovascular (CV) events in two cohorts of patients with type 2 diabetes mellitus.

METHODS

We considered patients from the DIABHYCAR (n = 3137) and the SURDIAGENE (n = 1468) studies. Baseline plasma PCSK9 concentration was measured using an immunofluorescence assay. In post hoc, but preplanned, analyses we assessed the relationship between PCSK9 and the following endpoints: (1) a combined endpoint of major CV events: CV death, non-fatal myocardial infarction (MI), stroke and heart failure-related hospital admission; (2) a composite of all CV events: MI, stroke, heart failure-related hospital admission, coronary/peripheral angioplasty or bypass, CV death; (3) MI; (4) stroke/transient ischaemic attack (TIA); and (5) CV death.

RESULTS

In the DIABHYCAR study, plasma PCSK9 tertiles were associated with the incidence of MI, all CV events and stroke/TIA (P for trend <.05). In adjusted Cox analysis, plasma PCSK9 was associated, independently of classic risk factors, with the incidence of major CV events (hazard ratio [HR] for 1-unit increase of log[PCSK9] 1.28 [95% confidence interval {CI} 1.06-1.55]), the incidence of MI (HR 1.66 [95% CI 1.05-2.63]), and the incidence of all CV events (HR 1.22 [95% CI 1.04-1.44]), but not with CV death. Plasma PCSK9 was not associated with the incidence of CV disease in the participants of the SURDIAGENE study with high CV risk treated with statins and insulin.

CONCLUSIONS

We found that PCSK9 was inconsistently associated with CV events in populations with type 2 diabetes. The association may depend on the level of CV risk and the background treatment.

Parallelism experiments to evaluate matrix effects, selectivity and sensitivity in ligand-binding assay method development: pros and cons

Parallelism is an essential experiment characterizing relative accuracy for a ligand-binding assay (LBA). By assessing the effects of dilution on the quantitation of endogenous analyte(s) in matrix, selectivity, matrix effects, minimum required dilution, endogenous levels of healthy and diseased populations and the LLOQ are assessed in a single experiment. This review compares and discusses all available approaches that can be used to assess key assay parameters for pharmacokinetic and biomarker LBAs, as well as the advantages and disadvantages of each approach. This review also summarizes a systematic approach that can apply to guide endogenous LBA method development and optimization with a suggested way to interpret parallelism data.

Impact of freeze-thaw cycles on circulating inflammation marker measurements

BACKGROUND

Circulating inflammation markers are being increasingly measured in prospective cohorts to investigate cancer etiology. However, it is unclear how the measurements are affected by the freeze-thaw cycles of the specimens prior to marker analysis.

METHODS

We compared concentrations of 45 inflammation markers between paired serum vials of 55 participants in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial that have undergone one (T1), two (T2), and three (T3) freeze-thaw cycles at the time of assay. We computed the difference of analyte concentrations across paired vials (T1 vs. T2, T2 vs. T3) and tested whether the difference deviated from zero using the Wilcoxon signed-rank test. We also calculated Spearman rank correlation and weighted kappa statistics for T1 vs. T2 and T2 vs. T3 comparisons to assess agreement in rank ordering of subjects.

RESULTS

Measurements between paired T1 and T2 samples were largely similar, with the difference not statistically deviating from zero for 36 of the 45 markers. In contrast, tests of the difference between paired T2 and T3 samples were statistically significant for 36 markers. However, the rank ordering of participants by marker concentration remained largely consistent across T2 and T3 samples, with Spearman correlation coefficients >0.8 for 42 markers and weighted kappas >0.7 for 37 markers.

CONCLUSION

We recommend that studies measuring inflammation markers use previously unthawed specimens to the extent possible, or match on the number of prior freeze-thaw cycles in nested case-control studies.

Optimization and evaluation of Luminex performance with supernatants of antigen-stimulated peripheral blood mononuclear cells

BACKGROUND

The Luminex bead-based multiplex assay is useful for quantifying immune mediators such as cytokines and chemokines. Cross-comparisons of reagents for this technique from different suppliers have already been performed using serum or plasma but rarely with supernatants collected from antigen-stimulated peripheral blood mononuclear cells (PBMC). Here, we first describe an optimization protocol for cell culture including quantity of cells and culture duration to obtain reproducible cytokine and chemokine quantifications. Then, we compared three different Luminex kit suppliers.

RESULTS

Intraclass correlation coefficients (ICCs) for a 2-days stimulation protocol were >0.8 for IFNγ and Perforin. The specific concentration was maximal after two or five days of stimulation, depending on the analyte, using 0.5 million PBMC per well, a cell quantity that gave the same level of specific cytokine secretion as 1.0 million. In the second part of the study, Luminex kits from Millipore showed a better working range than Bio-Rad and Ozyme ones. For tuberculin purified protein derivative (PPD)-stimulated samples, the overall mean pooled coefficients of variation (CVs) for all donors and all cytokines was 17.2 % for Bio-Rad, 19.4 % for Millipore and 26.7 % for Ozyme. Although the different kits gave cytokine concentrations that were generally compatible, there were discrepancies for particular cytokines. Finally, evaluation of precision and reproducibility of a 15-plex Millipore kit using a "home-made" internal control showed a mean intra-assay CV <13 % and an inter-assay CV <18 % for each cytokine concentration.

CONCLUSIONS

A protocol with a single round of stimulation but with two time points gave the best results for assaying different cytokines. Millipore kits appear to be slightly more sensitive than those from Bio-Rad and Ozyme. However, we conclude that the panel of analytes that need to be quantified should be the main determinant of kit selection. Using an internal control we demonstrated that a 15-plex magnetic Milliplex kit displayed good precision and reproducibility. Our findings should help optimize assays for evaluating immune responses during the course of disease or infection, or in response to vaccine or therapy.

Development and Validation of a Fluorescent Multiplexed Immunoassay for Measurement of Transgenic Proteins in Cotton (Gossypium hirsutum)

In order to provide farmers with better and more customized alternatives to improve yields, combining multiple genetically modified (GM) traits into a single product (called stacked trait crops) is becoming prevalent. Trait protein expression levels are used to characterize new GM products and establish exposure limits, two important components of safety assessment. Developing a multiplexed immunoassay capable of measuring all trait proteins in the same sample allows for higher sample throughput and savings in both time and expense. Fluorescent (bead-based) multiplexed immunoassays (FMI) have gained wide acceptance in mammalian research and in clinical applications. In order to facilitate the measurement of stacked GM traits, we have developed and validated an FMI assay that can measure five different proteins (β-glucuronidase, neomycin phosphotransferase II, Cry1Ac, Cry2Ab2, and CP4 5-enolpyruvyl-shikimate-3-phosphate synthase) present in cotton leaf from a stacked trait product. Expression levels of the five proteins determined by FMI in cotton leaf tissues have been evaluated relative to expression levels determined by enzyme-linked immunosorbent assays (ELISAs) of the individual proteins and shown to be comparable. The FMI met characterization requirements similar to those used for ELISA. Therefore, it is reasonable to conclude that FMI results are equivalent to those determined by conventional individual ELISAs to measure GM protein expression levels in stacked trait products but with significantly higher throughput, reduced time, and more efficient use of resources.

Comparison of non-magnetic and magnetic beads in bead-based assays

Multiplex bead-based flow cytometry is an attractive way for simultaneous, rapid and cost-effective analysis of multiple analytes in a single sample. Previously, we developed various bead-based assays using non-magnetic beads coated with Staphylococcus aureus and Streptococcus pneumoniae antigens for the detection of antibodies. Here, we compared the performance of the assay using non-magnetic beads with one based on the newly developed magnetic beads. We optimized the magnetic beads' coupling procedure and antibody detection assays for S. aureus and S. pneumoniae antigens and we measured IgG in human pooled serum against a series of S. aureus and S. pneumoniae-derived antigens in a singleplex and in a multiplex assay, respectively. For the multiplex assay, the comparison between magnetic and non-magnetic beads showed: i) in the majority of the cases (13 of the 17 tested S. pneumoniae antigens) significantly higher Median Fluorescence Intensity (MFI) values, ii) lower detection limits, iii) lower coefficient of variation (CV: 12% vs. 7% for non-magnetic vs. magnetic beads), so lower inter-assay variation and hence higher reproducibility. Magnetic bead coupling is cost effective, as we used 25% of the normal amount of antigen and only 50% of the beads in comparison to the non-magnetic beads. This optimized magnetic-based assay, which combines ease of use with an improved assay performance, allows detection of antibodies with a low titer that are potentially missed with the non-magnetic-based assay.

Effect of Repeated Freezing and Thawing on Biomarker Stability in Plasma and Serum Samples

Objectives

The stability of circulating proteins can be affected by repeated freezing and thawing. The aim of our study was to identify the effect of repeated freezing and thawing on the plasma and serum concentrations of eight proteins [interferon-γ, interleukin (IL)-8, IL-15, IL-17A, matrix metalloproteinase (MMP)-7, tumor necrosis factor-α, vascular endothelial growth factor (VEGF), and VEGF receptor 2 (VEGF-R2)].

Methods

We assessed the concentration changes of these proteins in 30 plasma and serum samples subjected to three, four, or five freeze–thaw cycles, and compared these with the concentration changes in the samples that were subjected to two freeze–thaw cycles before analysis.

Results

Repeated freezing and thawing by up to five cycles did not modify the plasma and serum concentrations of interferon-γ, IL-8, and VEGF-R2, while levels of MMP-7, tumor necrosis factor-α, and VEGF were significantly changed in both plasma and serum samples. Moreover, MMP-7 and VEGF concentrations tended to increase with freeze–thaw cycles. They were more elevated in plasma samples (up to about 15%) than in serum samples (up to about 7%), suggesting that serum is the preferred sample type for the analysis of circulating proteins.

Conclusion

This is the first report on the effect of repeated freezing and thawing on plasma concentrations of MMP-7 and VEGF-R2. Our findings propose that researchers should consider the number of freeze–thaw cycles to select plasma or serum samples, depending on the type of analyte.

Silicon nanowire biosensor for highly sensitive and multiplexed detection of oral squamous cell carcinoma biomarkers in saliva

Silicon nanowire (SiNW) field-effect transistor (FET) biosensors have already been used as powerful sensors for the direct detection of disease-related biomarkers. However, the multiplexed detection of biomarkers in real samples is still challenging. Interleukin 8 (IL-8) and tumor necrosis factor α (TNF-α) are two typical biomarkers of oral squamous cell carcinoma (OSCC). In this study, we developed a multiplexed detection methodology for IL-8 and TNF-α detection in saliva using SiNW FET biosensors. We fabricated the SiNW FET sensors using a top-down lithography fabrication technique. Subsequently, we achieved the multiplexed detection of two biomarkers in saliva by specific recognition of the two biomarkers with their corresponding antibodies, which were modified on the SiNW. The established method was found to have a limit of detection as low as 10 fg/mL in 1 × PBS as well as 100 fg/mL in artificial saliva. Because of its advantages, including label-free and multiplexed detection, non-invasive analysis, highly sensitive and specific determination, the proposed method is expected to be widely used for the early diagnosis of OSCC.

CCL3 serves as a potential plasma biomarker in knee degeneration (osteoarthritis)

OBJECTIVE

To explore the ability of chemokines in plasma to detect the presence of pre-X-rays defined knee degeneration and the extent (burden).

METHODS

A total of 181 subjects (75 control subjects, 47 pre-X-KD patients and 50 X-KOA patients) were included and subdivided into three subgroups. Articular cartilage loss in pre-X-KD patients were scored on the basis of the ICRS classification during the arthroscopy or documented on MRI with chondral WORMS. The severity of X-KOA was graded using the Kellgren-Lawrence classification through the posterior-anterior knee X-rays. The concentrations of the inflammatory cytokines and chemokines in plasma were quantified using Luminex microbead-based suspension array (SA) and were cross-validated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

CCL3 in plasma showed the highest ability to discriminate pre-X-KD patients from the controls with an AUC of 0.799. At a cutoff value of 0.168 pg/ml, the sensitivity was 70.21%, the specificity was 96.00%, the positive predictive value was 91.67% and the negative predictive value was 83.72%. As to define disease burden, the plasma levels of resistin, IL6, IL8, CCL3 and CCL4 showed significant association with the severity of X-rays defined knee OA, with regard to the KL classification. Moreover, significant elevation of IL6, IL8, CCL3 and CCL4 levels in plasma were observed in severe knee OA patients (KL grade IV) compared with those with pre-X-KD (KL grade 0-I).

CONCLUSION

We firstly showed that the plasma CCL3 could be potential serum biomarker for knee OA with the capacity to detect pre-X-rays defined changes and stage the severity of damage in knee.

Effect of Vitamin D3 Supplementation in Combination with Weight Loss on Inflammatory Biomarkers in Postmenopausal Women: A Randomized Controlled Trial

Obesity and vitamin D deficiency are associated with risk for several cancers, possibly through inflammation and adipokine-related pathways. Two hundred and eighteen postmenopausal women with BMI > 25 kg/m(2) and low serum 25-hydroxyvitamin D (25(OH)D; ≥10-<32 ng/mL), were randomized to 12 months of either (i) weight-loss intervention + 2000 IU/day oral vitamin D3 or (ii) weight-loss intervention + daily placebo. Serum adiponectin, leptin, TNFα, IL6, IL1β, IL8, and IL10, were measured by immunoassay, and a composite inflammatory biomarker score calculated. Using generalized estimating equations, mean changes in outcomes were compared between arms (intent-to-treat), adjusted for possible confounders. Analyses were also stratified by weight-loss (gained/no weight-loss; <5%; 5% to 10%; ≥10%). At 12 months, there were no significant differences in analyte changes between arms. In stratified analyses, participants randomized to vitamin D3 who lost 5% to 10% of baseline weight, versus participants who gained weight/had no weight-loss, had significantly greater decreases in levels of IL6 compared with those randomized to placebo: absolute change -0.75 pg/mL (-17.2%), placebo versus -1.77 pg/mL (-37.3%), vitamin D, P = 0.004. Similar but attenuated results were observed for participants who lost ≥10% of baseline weight: -0.41 pg/mL (-13.6%), placebo versus -0.67 pg/mL (-17.3%), vitamin D, P = 0.02. Effects of vitamin D3 supplementation on levels of IL1β were inconsistent when stratified by weight loss. There were no intervention effects on IL10, TNFα, IL8, the composite score, adiponectin, or leptin, when stratified by weight-loss. In conclusion, vitamin D3 supplementation in combination with weight-loss of at least 5% of baseline weight was associated with significant reductions in levels of IL6.

Measurement of Leptin by RIA Versus MIA in a Population of Healthy Newborns

BACKGROUND

Assays based on multiplex immunoassay (MIA) technology have demonstrated advantages over enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). Its acceptance depends on how well it performs in comparison to older techniques. The aim is to compare the results of leptin using RIA versus MIA.

METHODS

We analyzed 81 samples of umbilical cord blood of healthy term newborns by RIA and MIA.

RESULTS

The concordance correlation coefficient was 0.158 (95% CI 0.10-0.21). Pearson's correlation coefficient was 0.6651 (95% CI 0.52-0.77; P < 0.0001). In the Bland-Altman plot, concordance is acceptable because most of the measurements are within a mean of ±1.96 SD.

CONCLUSIONS

As shown by the Bland-Altman plot, there is concordance by both methods, but with a weak correlation.

Multiplex serum cytokine immunoassay using nanoplasmonic biosensor microarrays

Precise monitoring of the rapidly changing immune status during the course of a disease requires multiplex analysis of cytokines from frequently sampled human blood. However, the current lack of rapid, multiplex, and low volume assays makes immune monitoring for clinical decision-making (e.g., critically ill patients) impractical. Without such assays, immune monitoring is even virtually impossible for infants and neonates with infectious diseases and/or immune mediated disorders as access to their blood in large quantities is prohibited. Localized surface plasmon resonance (LSPR)-based microfluidic optical biosensing is a promising approach to fill this technical gap as it could potentially permit real-time refractometric detection of biomolecular binding on a metallic nanoparticle surface and sensor miniaturization, both leading to rapid and sample-sparing analyte analysis. Despite this promise, practical implementation of such a microfluidic assay for cytokine biomarker detection in serum samples has not been established primarily due to the limited sensitivity of LSPR biosensing. Here, we developed a high-throughput, label-free, multiarrayed LSPR optical biosensor device with 480 nanoplasmonic sensing spots in microfluidic channel arrays and demonstrated parallel multiplex immunoassays of six cytokines in a complex serum matrix on a single device chip while overcoming technical limitations. The device was fabricated using easy-to-implement, one-step microfluidic patterning and antibody conjugation of gold nanorods (AuNRs). When scanning the scattering light intensity across the microarrays of AuNR ensembles with dark-field imaging optics, our LSPR biosensing technique allowed for high-sensitivity quantitative cytokine measurements at concentrations down to 5-20 pg/mL from a 1 μL serum sample. Using the nanoplasmonic biosensor microarray device, we demonstrated the ability to monitor the inflammatory responses of infants following cardiopulmonary bypass (CPB) surgery through tracking the time-course variations of their serum cytokines. The whole parallel on-chip assays, which involved the loading, incubation, and washing of samples and reagents, and 10-fold replicated multianalyte detection for each sample using the entire biosensor arrays, were completed within 40 min.

Development of a bead-based aptamer/antibody detection system for C-reactive protein

A multiplexing bead-based platform provides an approach for the development of assays targeting specific analytes for biomonitoring and biosensing applications. Multi-Analyte Profiling (xMAP) assays typically employ a sandwich-type format using antibodies for the capture and detection of analytes of interest, and the system permits the simultaneous quantitation of multiple targets. In this study, an aptamer/antibody assay for the detection of C-reactive protein (CRP) was developed. CRP is an acute phase marker of inflammation whose elevated basal levels are correlated with an increased risk for a number of pathologies. For this assay, an RNA aptamer that binds CRP was conjugated to beads to act as the capture agent. Biotinylated anti-CRP antibody coupled to fluorescently labeled streptavidin was used for quantification of CRP. The detection limit of the CRP assay was 0.4 mg/L in diluted serum. The assay was then used to detect spiked CRP samples in the range of 0.4 to 10mg/L in diluted serum with acceptable recoveries (extrapolated values of 70-130%), including that of a certified reference material (129% recovery). The successful incorporation of the CRP aptamer into this platform demonstrates that the exploration of other aptamer-target systems could increase the number of analytes measurable using xMAP-type assays.

IgG4 subclass-specific responses to Staphylococcus aureus antigens shed new light on host-pathogen interaction

IgG4 responses are considered indicative for long-term or repeated exposure to particular antigens. Therefore, studying IgG4-specific antibody responses against Staphylococcus aureus might generate new insights into the respective host-pathogen interactions and the microbial virulence factors involved. Using a bead-based flow cytometry assay, we determined total IgG (IgGt), IgG1, and IgG4 antibody responses to 40 different S. aureus virulence factors in sera from healthy persistent nasal carriers, healthy persistent noncarriers, and patients with various staphylococcal infections from three distinct countries. IgGt responses were detected against all tested antigens. These were mostly IgG1 responses. In contrast, IgG4 antibodies were detected to alpha-toxin, chemotaxis inhibitory protein of S. aureus (CHIPS), exfoliative toxins A and B (ETA and -B), HlgB, IsdA, LukD, -E, -F, and -S, staphylococcal complement inhibitor (SCIN), staphylococcal enterotoxin C (SEC), staphylococcal superantigen-like proteins 1, 3, 5, and 9 (SSL1, -3, -5, and -9), and toxic shock syndrome toxin 1 (TSST-1) only. Large interpatient variability was observed, and the type of infection or geographical location did not reveal conserved patterns of response. As persistent S. aureus carriers trended toward IgG4 responses to a larger number of antigens than persistent noncarriers, we also investigated sera from patients with epidermolysis bullosa (EB), a genetic blistering disease associated with high S. aureus carriage rates. EB patients responded immunologically to significantly more antigens than noncarriers and trended toward even more responses than carriers. Altogether, we conclude that the IgG4 responses against a restricted panel of staphylococcal antigens consisting primarily of immune modulators and particular toxins indicate important roles for these virulence factors in staphylococcal pathogen-host interactions, such as chronicity of colonization and/or (subclinical) infections.

Multiplexed measurements of immunomodulator levels in peripheral blood of healthy subjects: Effects of analytical variables based on anticoagulants, age, and gender

Multiplex microbead immunoassay (MMIA) is a powerful technology for a wide range of biomedical and clinical applications. It is important to study the normal concentration ranges of immunomodulators under different sample preparation conditions and age groups of subjects in order to more precisely determine their reference values for use in assessing alterations of their levels in disease. The aim of this study was to determine the plasma concentrations of immunomodulators (cytokines, chemokines, and growth factors) in the peripheral blood from healthy subjects by the use of a large multiplex panel, and to determine the effects of different anticoagulants, age, and gender on the immunomodulator levels. In addition, the assay precision for these biomarker analytes was determined. Plasma samples from 107 healthy subjects, aged 18 to 85 years, were collected in three different anticoagulants (sodium citrate, EDTA, Heparin); corresponding serum samples were also obtained. Multiplex microbead immunoassays were performed for measuring a total of 23 analytes including chemokines, cytokines, and growth factors (IL-1β, IL-1ra, IL-2, IL-6, IL-7, IL-8, IL-12 p70, IL-17, IFN-γ, IP-10, MCP-1, PDGF-BB, RANTES, TNF-α, IL-1a, IL-16, HGF, MIG, TNF-β, PDGF-ABBB, EGF, Flt-3 Ligand, VEGF). For these analytes, our results showed that the anticoagulant affected the concentration measurements and the coefficients of variation. However, the relative levels of the analytes (profiles) of samples collected in a particular anticoagulant are consistent. The analytes IL-1β, IL-7, Flt-3 Ligand, and IL-12p70 show the largest variation (up to fourfold) between the age groups. In addition, no statistically significant differences in the level of the analytes were found between the sexes.

Interleukin-1 beta in unstimulated whole saliva is a potential biomarker for oral squamous cell carcinoma

The objective of this study was to evaluate cytokines in unstimulated whole saliva (UWS) of oral squamous cell carcinoma (OSCC) patients as compared to those with pre- and post-operation for evaluation as markers of OSCC. Sixteen OSCC patients were included in this study. Cytokine concentrations in resting saliva were measured using a Bio-Plex suspension array system. Only interleukin-1 (IL-1) beta showed significantly different cytokine concentration in saliva between pre- and post-operation. IL-1 beta was released from cultured OSCC cells confirmed by ELISA and immunohistochemistry. From this study, IL-1 beta in UWS may be useful for detection of early stage OSCC. More studies are needed to accept the utility of IL-1 beta in UWS for predicting, diagnosis and evaluation of OSCC.

Determination of tear and serum inflammatory cytokines in patients with rosacea using multiplex bead technology

PURPOSE

To compare serum and tear inflammatory and anti-inflammatory cytokine levels of rosacea patients with the healthy controls and evaluate the correlation of tear cytokine levels with tear function parameters.

METHODS

Tear and serum interleukin (IL)-1α, IL-6, IL-8, IL-10, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) levels were measured using multiplex bead (Luminex) technology in 12 rosacea patients without ocular involvement (group 1), 20 rosacea patients with ocular involvement (group 2), and 22 healthy subjects (group 3). The correlation of the cytokines with tear function parameters was analyzed using Spearman correlation test.

RESULTS

Tear IL-10 and VEGF levels were significantly lower in group 1 (median: 35.78 pg/mL and 427.29, respectively) and group 2 (median: 26.25 pg/mL and 348.31, respectively) than in group 3 (median: 75.96 pg/mL and 480.12, respectively) (p < 0.05). Mean serum IL-8 level was significantly lower in group 2 (median = 0) compared to group 3 (median = 3.98) (p = 0.02). Tear breakup time was found to be positively correlated with IL-10 (r = 0.46, p = 0.013) and inversely correlated with MCP-1 (r = -0.52, p = 0.004).

CONCLUSIONS

Tear and serum levels of cytokines and growth factors measured with Luminex technology showed a large variation in rosacea and healthy subjects. Decreased levels of tear IL-10, an anti-inflammatory cytokine, may lead to an inflammatory ocular surface environment, exacerbate ocular surface inflammation, and deteriorate tear function tests. A bigger sample size, including rosacea patients with corneal involvement, is needed to confirm the role of cytokines in the pathogenesis of rosacea-associated ocular inflammation.

High-throughput flow cytometry for drug discovery

High-throughput flow cytometry exploits a novel many-samples/one-file approach to dramatically speed data acquisition, limit aspirated sample volume to as little as 2 μl/well and produce multisample data sets that facilitate automated analysis of samples in groups as well as individually. It has been successfully applied to both cell- and microsphere-based bioassays in 96- and 384-well formats, to screen tens-of-thousands of compounds and identify novel bioactive structures. High-content multiparametric analysis capabilities have been exploited for assay multiplexing, allowing the assessment of biologic selectivity and specificity to be an integral component of primary screens. These and other advances in the last decade have contributed to the application of flow cytometry as a uniquely powerful tool for probing biologic and chemical diversity and complex systems biology.

Predictive value of combined cervicovaginal cytokines and gestational age at sampling for intra-amniotic infection in preterm premature rupture of membranes

OBJECTIVE

To determine whether interleukin (IL)-1β, IL-6, and IL-8 in cervicovaginal fluid, alone or in combination with clinical risk factors, could predict intra-amniotic infection in women with preterm premature rupture of membranes (PPROM).

DESIGN

A prospective cohort study.

SETTING

University teaching hospital.

POPULATION

Women with singleton pregnancies presenting PPROM between 20 and 35 weeks of gestation (n = 76).

METHODS

Cervicovaginal fluid samples were collected for IL-1β, IL-6, and IL-8 measurements immediately before amniocentesis. Amniotic fluid obtained by amniocentesis was cultured and the white blood cell count was determined. Clinical risk factors analyzed included demographics and gestational age. Cervicovaginal concentrations of cytokines were measured using a multiplex bead array assay.

MAIN OUTCOME MEASURE

A positive amniotic fluid culture.

RESULTS

The prevalence of a positive amniotic fluid culture was 46.1% (35/76). Stepwise multivariate regression analysis yielded a model using cervicovaginal IL-6 and gestational age at sampling with the area under the curve (AUC) of 0.807 for predicting intra-amniotic infection. The AUC for this model was significantly higher than either parameter retained in this model but no differences were observed between the AUC of this model based on non-invasive variables, and amniotic fluid white blood cell count using invasive amniocentesis for the prediction of intra-amniotic infection.

CONCLUSIONS

Among measured cytokines, the combination of cervicovaginal IL-6 and gestational age appears to be best in predicting intra-amniotic infection and allows for a considerably better accuracy than the use of either factor alone. Overall, this combination performed as well as amniotic fluid WBC count for predicting intra-amniotic infection.

Selection of disease-specific biomarkers by integrating inflammatory mediators with clinical informatics in AECOPD patients: a preliminary study

Systemic inflammation is a major factor influencing the outcome and quality of patient with chronic obstructive pulmonary disease (COPD) and acute exacerbations (AECOPD). Because of the inflammatory complexity, a great challenge is still confronted to optimize the identification and validation of disease-specific biomarkers. This study aimed at developing a new protocol of specific biomarker evaluation by integrating proteomic profiles of inflammatory mediators with clinical informatics in AECOPD patients, understand better their function and signal networks. Plasma samples were collected from healthy non-smokers or patients with stable COPD (sCOPD) or AECOPD on days 1 and 3 of the admission and discharging day (day 7–10). Forty chemokines were measured using a chemokine multiplex antibody array. Clinical informatics was achieved by a Digital Evaluation Score System (DESS) for assessing severity of patients. Chemokine data was compared among different groups and its correlation with DESS scores was performed by SPSS software. Of 40 chemokines, 30 showed significant difference between sCOPD patients and healthy controls, 16 between AECOPD patients and controls and 13 between AECOPD patients and both sCOPD and controls, including BTC, IL-9, IL-18Bpa, CCL22,CCL23, CCL25, CCL28, CTACK, LIGHT, MSPa, MCP-3, MCP-4 and OPN. Of them, some had significant correlation with DESS scores. There is a disease-specific profile of inflammatory mediators in COPD and AECOPD patients which may have a potential diagnostics together with clinical informatics of patients. Our preliminary study suggested that integration of proteomics with clinical informatics can be a new way to validate and optimize disease-special biomarkers.

A condensed performance-validation strategy for multiplex detection kits used in studies of human clinical samples

Quantification of soluble phase analytes represents one of the most commonly used techniques applied to a broad range of samples in both basic and clinical immunology laboratories, as well as in context of drug development and diagnostic programs. The recent increase in the application of multiplex immunoassays, such as Luminex, has resulted in a growing array of commercially available multiplex kits. Validated, highly sensitive, and precise methods for such quantification is critical, especially when applied to precious sample collections. While vendors are expected to carry out kit performance validation, discrepancies between technical specifications provided with multiplex kits and their actual performance can be relatively common. Here we present a validation strategy that will aid users to select the optimal kits for their purpose and most validly interpret results from the multiplex assays. To illustrate key considerations when validating and comparing kits, we assess the performance of three conventional multiplex cytokine kits. Our findings confirm the importance of validating the performance of commercial multiplex kits and provide a practical and cost-effective approach that can be readily implemented in both academic and translational laboratory settings.

Analytical aspects of molecular Alzheimer’s disease biomarkers

In general, a biomarker has multiple uses such as a diagnostic tool and a method to monitor therapy. The quality of a biomarker depends on how big the difference is between, for example, patients and healthy controls, but also on the capacity of the method used to measure it (the uncertainty in the method should be much less than the difference between the groups). A good biomarker should also be specific towards a disease, allowing for differentiation between clinically related syndromes. In addition, it is of importance that the stability of the methods used is high enough to establish cut-off levels both in individual laboratories and on a global scale. In the field of Alzheimer’s disease, there are currently three cerebrospinal fluid markers that have been verified in multiple studies and the analytical aspects of measuring them will be discussed.

Effects of a physical activity behavior change intervention on inflammation and related health outcomes in breast cancer survivors: pilot randomized trial

BACKGROUND

The goal of this pilot study was to determine the magnitude and direction of intervention effect sizes for inflammatory-related serum markers and relevant health outcomes among breast cancer survivors (BCSs) receiving a physical activity behavior change intervention compared with usual care.

METHODS

This randomized controlled trial enrolled 28 stage I, II, or IIIA BCSs who were post-primary treatment and not regular exercisers. Participants were assigned to either a 3-month physical activity behavior change intervention group (ING) or usual care group (UCG). Intervention included supervised aerobic (150 weekly minutes, moderate-intensity) and resistance (2 sessions per week) exercise that gradually shifted to home-based exercise. Outcomes were assessed at baseline and 3 months.

RESULTS

Cardiorespiratory fitness significantly improved in the ING versus the UCG (between-group difference = 3.8 mL/kg/min; d = 1.1; P = .015). Self-reported sleep latency was significantly reduced in the ING versus the UCG (between group difference = -0.5; d = -1.2; P = .02) as was serum leptin (between-group difference = -9.0 ng/mL; d = -1.0; P = .031). Small to medium nonsignificant negative effect sizes were noted for interleukin (IL)-10 and tumor necrosis factor (TNF)-α and ratios of IL-6 to IL-10, IL-8 to IL-10, and TNF-α to IL-10, whereas nonsignificant positive effect sizes were noted for IL-6 and high-molecular-weight adiponectin.

CONCLUSIONS

Physical activity behavior change interventions in BCSs can achieve large effect size changes for several health outcomes. Although effect sizes for inflammatory markers were often small and not significant, changes were in the hypothesized direction for all except IL-6 and IL-10.