Reproducibility of serum cytokines and growth factors

A systematic review and meta-analysis of the stability of peripheral immune markers in healthy adults

Peripheral immune markers are widely used to predict risk for inflammatory disease. However, whether single assessments of inflammatory biomarkers represent stable individual differences remains unclear. We reviewed 50 studies (N = 48,674; 57 % male; mean age 54 (range 13-79) years) that assessed markers of inflammation on >1 occasion, with time between measures ranging from 24 h to 7+ years. Separate random effects meta-analyses were conducted for each inflammatory marker and time interval. Markers that had broad coverage across most time intervals included C-reactive protein (CRP; k = 37), interleukin (IL)-6 (k = 22), TNF-α (k = 10), and fibrinogen (Fg; k = 9). For CRP, IL-6, and TNF-α, stability estimates generally decreased with time, with strong to moderate stability over intervals <6 months (r's = 0.80-0.61), modest to moderate stability over 6 months - 3 years (r's = 0.60-0.51), and low stability for >3 years (r's = 0.39-0.30). Estimates were less reliable for Fg for time intervals ≤ 3 years although they generally followed the same pattern; more reliable findings suggested greater stability for Fg than other markers for intervals >3 years (r = 0.53). These findings suggest that single measures of inflammatory biomarkers may be an adequate index of stable individual differences in the short term (<6 months), with repeated measures of inflammatory biomarkers recommended over intervals ≥ 6 months to 3 years, and absolutely necessary over intervals >3 years to reliably identify stable individual differences in health risk. These findings are consistent with stability estimates and clinical recommendations for repeated measurement of other cardiovascular measures of risk (e.g., blood lipids, blood pressure).

Interbatch Reliability of Blood-Based Cytokine and Chemokine Measurements in Community-Dwelling Older Adults: A Cross-Sectional Study

Blood-based inflammatory markers hold considerable promise for diagnosis and prognostication of age-related neurodegenerative disease, though a paucity of research has empirically tested how reliably they can be measured across different experimental runs ("batches"). We quantified the interbatch reliability of 13 cytokines and chemokines in a cross-sectional study of 92 community-dwelling older adults (mean age = 74; 48% female). Plasma aliquots from the same blood draw were parallelly processed in 2 separate batches using the same analytic platform and procedures (high-performance electrochemiluminescence by Meso Scale Discovery). Interbatch correlations (Pearson's r) ranged from small and nonsignificant (r = .13 for macrophage inflammatory protein-1 alpha [MIP-1α]) to very large (r > .90 for interferon gamma [IFNγ], interleukin-10 [IL-10], interferon gamma-induced protein 10 [IP-10], MIP-1β, thymus and activation-regulated chemokine [TARC]) with most markers falling somewhere in between (.67 ≤ r ≤ .90 for IL-6, tumor necrosis factor alpha [TNF-α], Eotaxin, Eotaxin-3, monocyte chemoattractant protein-1 [MCP-1], MCP-4, macrophage-derived chemokine [MDC]). All markers, except for IL-6 and MCP-4, showed significant differences in absolute values between batches, with discrepancies ranging in effect size (Cohen's d) from small to moderate (0.2 ≤ |d| ≤ 0.5 for IL-10, IP-10, MDC) to large or very large (0.68 ≤ |d| ≤ 1.5 for IFNγ, TNF-α, Eotaxin, Eotaxin-3, MCP-1, MIP-1α, MIP-1β, TARC). Relatively consistent associations with external variables of interest (age, sex, systolic blood pressure, body mass index, cognition) were observed across batches. Taken together, our results suggest heterogeneity in measurement reliability of blood-based cytokines and chemokines, with some analytes outperforming others. Future work is needed to evaluate the generalizability of these findings while identifying potential sources of batch effect measurement error.

Intraindividual Long-term Immune Marker Stability in Plasma Samples Collected in Median 9.4 Years Apart in 304 Adult Cancer-free Individuals

BACKGROUND

Changes in immune marker levels in the blood could be used to improve the early detection of tumor-associated inflammatory processes. To increase predictiveness and utility in cancer detection, intraindividual long-term stability in cancer-free individuals is critical for biomarker candidates as to facilitate the detection of deviation from the norm.

METHODS

We assessed intraindividual long-term stability for 19 immune markers (IL10, IL13, TNFα, CXCL13, MCP-3, MIP-1α, MIP-1β, fractalkine, VEGF, FGF-2, TGFα, sIL2Rα, sIL6R, sVEGF-R2, sTNF-R1, sTNF-R2, sCD23, sCD27, and sCD30) in 304 cancer-free individuals. Repeated blood samples were collected up to 20 years apart. Intraindividual reproducibility was assessed by calculating intraclass correlation coefficients (ICC) using a linear mixed model.

RESULTS

ICCs indicated fair to good reproducibility (ICCs ≥ 0.40 and < 0.75) for 17 of 19 investigated immune markers, including IL10, IL13, TNFα, CXCL13, MCP-3, MIP-1α, MIP-1β, fractalkine, VEGF, FGF-2, TGFα, sIL2Rα, sIL6R, sTNF-R1, sTNF-R2, sCD27, and sCD30. Reproducibility was strong (ICC ≥ 0.75) for sCD23, while reproducibility was poor (ICC < 0.40) for sVEGF-R2. Using a more stringent criterion for reproducibility (ICC ≥ 0.55), we observed either acceptable or better reproducibility for IL10, IL13, CXCL13, MCP-3, MIP-1α, MIP-1β, VEGF, FGF-2, sTNF-R1, sCD23, sCD27, and sCD30.

CONCLUSIONS

IL10, IL13, CXCL13, MCP-3, MIP-1α, MIP-1β, VEGF, FGF-2, sTNF-R1, sCD23, sCD27, and sCD30 displayed ICCs consistent with intraindividual long-term stability in cancer-free individuals.

IMPACT

Our data support using these markers in prospective longitudinal studies seeking early cancer detection biomarkers.

Reproducibility of serum cytokines in an elderly population

Background

It is important to assess the temporal reproducibility of circulating cytokines for their utility in epidemiological studies. However, existing evidence is limited and inconsistent, especially for the elderly population.

Methods

Sixty-five elderly (mean age = 77.89 ± 6.14 years) subjects were randomly selected from an existing prospective cohort study. Levels of 41 cytokines in 195 serum samples, collected at three separate visits that were up to 15.26 years apart, were measured by the Luminex technology. The temporal reproducibility of cytokines was estimated by the intraclass correlation coefficient (ICC) calculated using a mixed-effects model. In addition, data analyses were stratified by the median (4.49 years) of time intervals across sample collection. Sensitivity analyses were performed when excluding subjects with undetectable samples.

Results

A total of 23 cytokines were detectable in more than 60% of samples. Fair to good (ICC = 0.40 to 0.75) and excellent (ICC > 0.75) reproducibility was found in 10 (Eotaxin, VEGF, FGF-2, G-CSF, MDC, GM-CSF, TGFα, IP-10, MIP-1β, IL-1RA) and 5 (GRO, IFNγ, IL-17, PDGF-AA, IL-4) cytokines, respectively. The results were not changed dramatically in the stratification and sensitivity analyses.

Conclusions

Serum levels of the selected 15 cytokines measured with Luminex technology displayed fair to excellent within-person temporal reproducibility among elderly population.

Distinct Inflammation Biomarkers in Healthy Individuals and Patients with Schizophrenia: A Reliability Testing of Multiplex Cytokine Immunoassay by Bland-Altman Analysis

OBJECTIVE

Since the inflammatory process has been implicated in the pathophysiology of psychiatric disorder, an important issue emerging is to assess the test-retest reliability of cytokine measurement in healthy individuals and patients with schizophrenia. The objective of the present study was to investigate the test-retest reliability of bead-based multiplex immunoassay technology (BMIT) for cytokine measurement by using a Bland-Altman plot (BAP).

METHODS

Twenty healthy individuals and twenty patients with schizophrenia were enrolled, and a 17-plex cytokine assay was used to measure inflammatory biomarkers at baseline and two weeks later. The test-retest reliability was examined by BAP, 95% limits of agreement (LOA), intraclass correlation coefficient (ICC), and coefficient of repeatability (CoR).

RESULTS

In the healthy controls, only interleukin (IL)-2, IL-13, IL-10, IL-17, and macrophage inflammatory protein-1β showed excellent ICC. The BAP with 95% LOA determined that 13 cytokines showed acceptable 95% LOA for a 2-week test-retest reliability, and only IL-1β, IL-12 and tumor necrosis factor (TNF)-α had significant test-retest bias. The CoR of cytokines varied significantly, ranging from 1.72 to 218.1. Compared with healthy controls, patients with schizophrenia showed significantly higher levels of IL-5, IL-13, and TNF-α and significantly lower levels of IL-4, IL-12, and interferon-gamma (IFN-γ). Of these six cytokines, IL-12 and TNF-α were considered suboptimal reliability.

CONCLUSION

The findings from ICC and CoR implied that the test-retest reliability of BMIT for cytokine measurement were suboptimal. However, the BAP with 95% LOA confirmed that BMIT can reliably distinguish schizophrenia from healthy individuals in cytokine measurement, while significant within-subject variation and between-group overlapping were evident in cytokine expression.

Cytokines for evaluation of chronic inflammatory status in ageing research: reliability and phenotypic characterisation

Background

There is a growing interest in the role of inflammageing for chronic disease development. Cytokines are potent soluble immune mediators that can be used as target biomarkers of inflammageing; however, their measurement in human samples has been challenging. This study aimed to assess the reliability of a pro- and anti-inflammatory cytokine panel in a sample of healthy people measured with a novel electrochemiluminescent multiplex immunoassay platform (Meso Scale Discovery, MSD), and to characterize their associations with metabolic and inflammatory phenotypes.

Results

Overall, the majority of cytokines were above the limit of detection (in at least 85.3% of the samples). Cytokines IL-6, IL-8, TNF-α, IL-10, IL-13, and IFN-γ showed overall good to fair reliability (ICC > 0.40), whereas IL-1β, IL-2, IL-4, and IL-12p70 showed poor reliability (ICC < 0.40). The reliability estimates were not substantially influenced by participants' age, sex, obesity and C-reactive protein (CRP) levels. As expected, cytokine concentrations were elevated with advanced age most pronouncedly for IL-6, IL-8, Il-2, IFN- γ, and TNF-α. No major associations with metabolic phenotypes were observed for most cytokines, with the exception of a positive association between IL-6 and TNF-α with body mass index and CRP (ρ: 0.36; ρ: 0.20; ρ: 0.53; ρ: 0.22, respectively), and IFN-γ and IL-10 with CRP (ρ: 0.23 and ρ: 0.19, respectively).

Conclusions

Single measurements of selected cytokines using MSD platform, including IL-6, IL-8, IL-10, IL-13, TNF-α, and IFN-γ have shown to be representative of an individual's average level over time and could be suitable for use in prospective epidemiological and clinical studies. Such studies are highly warranted to characterize associations of cytokines with phenotypes and diseases associated with ageing.

Studies of advanced glycation end products and oxidation biomarkers for type 2 diabetes

Advanced glycation end products (AGEs) are formed upon nonenzymatic reactions of sugars or their metabolites with proteins and other cellular constituents. Many AGEs are long lived. Recent findings suggest that AGEs may predict diabetes and its complications and thus may warrant further study. The objective of this study was to assess the validity of our experimental procedures for measuring AGEs in stored blood sample and to conduct a pilot study for developing AGE biomarkers for diabetes and/or age-related changes of glucose metabolism. We conducted a reliability study of the samples and methods using liquid chromatography-tandem mass spectrometry (LC-MS)/MS assays for 10 AGEs (including methylglyoxal-derived hydroimidazolone (MG-H1), glucosepane (GSP) and two oxidation measures, in stored repository blood samples from the Nurses' Health Study and the Health Professionals Follow-up Study. We also analyzed data relating blood GSP levels to type 2 diabetes status in a case-control study (25 cases and 15 controls). Among the AGEs, GSP, and MG-H1 showed the highest reliability across the various measures: reliability in duplicate samples and stability with delayed processing and storage over 1-2 year period. Furthermore, plasma GSP was associated with older age (P = 0.04) and type 2 diabetes status (age-adjusted P = 0.0475). Our findings suggest that analysis of these AGEs may be developed as biomarkers for diabetes and/or age-related changes of glucose metabolism. © 2018 BioFactors, 44(3):281-288, 2018.

Pre-diagnostic blood immune markers, incidence and progression of B-cell lymphoma and multiple myeloma: Univariate and functionally informed multivariate analyses

Recent prospective studies have shown that dysregulation of the immune system may precede the development of B‐cell lymphomas (BCL) in immunocompetent individuals. However, to date, the studies were restricted to a few immune markers, which were considered separately. Using a nested case–control study within two European prospective cohorts, we measured plasma levels of 28 immune markers in samples collected a median of 6 years before diagnosis (range 2.01–15.97) in 268 incident cases of BCL (including multiple myeloma [MM]) and matched controls. Linear mixed models and partial least square analyses were used to analyze the association between levels of immune marker and the incidence of BCL and its main histological subtypes and to investigate potential biomarkers predictive of the time to diagnosis. Linear mixed model analyses identified associations linking lower levels of fibroblast growth factor‐2 (FGF‐2 p = 7.2 × 10⁻⁴) and transforming growth factor alpha (TGF‐α, p = 6.5 × 10⁻⁵) and BCL incidence. Analyses stratified by histological subtypes identified inverse associations for MM subtype including FGF‐2 (p = 7.8 × 10⁻⁷), TGF‐α (p = 4.08 × 10⁻⁵), fractalkine (p = 1.12 × 10⁻³), monocyte chemotactic protein‐3 (p = 1.36 × 10⁻⁴), macrophage inflammatory protein 1‐alpha (p = 4.6 × 10⁻⁴) and vascular endothelial growth factor (p = 4.23 × 10⁻⁵). Our results also provided marginal support for already reported associations between chemokines and diffuse large BCL (DLBCL) and cytokines and chronic lymphocytic leukemia (CLL). Case‐only analyses showed that Granulocyte‐macrophage colony stimulating factor levels were consistently higher closer to diagnosis, which provides further evidence of its role in tumor progression. In conclusion, our study suggests a role of growth‐factors in the incidence of MM and of chemokine and cytokine regulation in DLBCL and CLL.

What's new?

B‐cell lymphomas (BCL) are frequent in immunocompromised individuals, but most BCL cases are thought to occur as a consequence of minor immune perturbations in otherwise immunocompetent individuals. Here the authors prospectively examined a panel of immune markers in the blood from 268 patients afflicted with BCL and paired controls. The data uncover a functional role for growth factors (i.e. FGF‐2, TGF‐alpha) in the incidence and progression of multiple myeloma, a BCL subtype, and underscore the importance of chemokine and cytokine regulation in diffuse large B‐cell lymphoma and chronic lymphocytic leukemia.

Circulating inflammatory biomarkers in relation to brain structural measurements in a non-demented elderly population

The aim of this investigation was to determine whether circulating inflammatory biomarkers c-reactive protein (CRP), interleukin-6 (IL6), and alpha 1-antichymotrypsin (ACT) were related to structural brain measures assessed by magnetic resonance imaging (MRI). High-resolution structural MRI was collected on 680 non-demented elderly (mean age 80.1years) participants of a community-based, multiethnic cohort. Approximately three quarters of these participants also had peripheral inflammatory biomarkers (CRP, IL6, and ACT) measured using ELISA. Structural measures including brain volumes and cortical thickness (with both global and regional measures) were derived from MRI scans, and repeated MRI measures were obtained after 4.5years. Mean fractional anisotropy was used as the indicator of white matter integrity assessed with diffusion tensor imaging. We examined the association of inflammatory biomarkers with brain volume, cortical thickness, and white matter integrity using regression models adjusted for age, gender, ethnicity, education, APOE genotype, and intracranial volume. A doubling in CRP (b=-2.48, p=0.002) was associated with a smaller total gray matter volume, equivalent to approximately 1.5years of aging. A doubling in IL6 was associated with smaller total brain volume (b=-14.96, p<0.0001), equivalent to approximately 9years of aging. Higher IL6 was also associated with smaller gray matter (b=-6.52, p=0.002) and white matter volumes (b=-7.47, p=0.004). The volumes of most cortical regions including frontal, occipital, parietal, temporal, as well as subcortical regions including pallidum and thalamus were associated with IL6. In a model additionally adjusted for depression, vascular factors, BMI, and smoking status, the association between IL6 and brain volumes remained, and a doubling in ACT was marginally associated with 0.054 (p=0.001) millimeter thinner mean cortical thickness, equivalent to that of approximately 2.7years of aging. None of the biomarkers was associated with mean fractional anisotropy or longitudinal change of brain volumes and thickness. Among older adults, increased circulating inflammatory biomarkers were associated with smaller brain volume and cortical thickness but not the white matter tract integrity. Our preliminary findings suggest that peripheral inflammatory processes may be involved in the brain atrophy in the elderly.

The influence of different calorie restriction protocols on serum pro-inflammatory cytokines, adipokines and IGF-I levels in female C57BL6 mice: short term and long term diet effects

Calorie restriction (CR) is an effective intervention to prevent chronic diseases including cancer. Although many factors, i.e., sex hormones, IGF-I and mTOR have been studied in response to CR, the molecular mechanisms of CR remain to be identified. Our objective was to determine the short and long-term effects of different CR protocols on pro-inflammatory cytokines. Our hypothesis was that Intermittent CR (ICR) would result in greater inhibition of pro-inflammatory serum cytokines compared to Chronic CR (CCR) as we previously found ICR to be more protective in the prevention of mammary tumor development. From ten weeks of age female C57BL6 mice were maintained on either ad libitum (AL) fed, ICR or CCR protocols (overall CR of ~75% of AL) for up to 74 weeks of age. Blood samples were collected for measurements of serum interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), adiponectin, leptin, IGF-I and insulin at specified ages. For ICR mice samples were collected following 3 weeks of restriction (ICR-R) and after one week of refeeding (ICR-RF). In general, both modes of CR significantly reduced serum IL-6, TNF-α, IGF-I and leptin levels compared to AL with IL-6 levels 24 and 3.5 fold and TNF-α levels t 11 and 1.5 fold lower in ICR and CCR groups, respectively at study termination. There was a trend for adiponectin and insulin to be highest in ICR-RF mice. Body weights were positively correlated with IL-6, TNF-α, insulin and leptin but negatively correlated with adiponectin-to-leptin ratio. Moreover, there was a positive correlation between IL-6 and TNF-α. Beneficial effects of ICR may function through pro-inflammatory cytokine pathways.

Systematic evaluation of immune regulation and modulation

Cancer immunotherapies are showing promising clinical results in a variety of malignancies. Monitoring the immune as well as the tumor response following these therapies has led to significant advancements in the field. Moreover, the identification and assessment of both predictive and prognostic biomarkers has become a key component to advancing these therapies. Thus, it is critical to develop systematic approaches to monitor the immune response and to interpret the data obtained from these assays. In order to address these issues and make recommendations to the field, the Society for Immunotherapy of Cancer reconvened the Immune Biomarkers Task Force. As a part of this Task Force, Working Group 3 (WG3) consisting of multidisciplinary experts from industry, academia, and government focused on the systematic assessment of immune regulation and modulation. In this review, the tumor microenvironment, microbiome, bone marrow, and adoptively transferred T cells will be used as examples to discuss the type and timing of sample collection. In addition, potential types of measurements, assays, and analyses will be discussed for each sample. Specifically, these recommendations will focus on the unique collection and assay requirements for the analysis of various samples as well as the high-throughput assays to evaluate potential biomarkers.

How to: Measuring blood cytokines in biological psychiatry using commercially available multiplex immunoassays

Cytokines produced by both immune and non-immune cells are likely to play roles in the development and/or progression of psychiatric disorders. Indeed, many investigators have compared the blood cytokine levels in psychiatric patients with those of healthy controls or monitored their levels in patients during disease progression to identify biomarkers. Nevertheless, very few studies have confirmed that such cytokines remain stable in healthy individuals through periods of weeks and months. This is an important issue to consider before using blood cytokine levels as biomarkers of disease traits, disease state, or treatment response. Although multiplex assay technology represents an advance in identifying biomarkers because it allows simultaneous examination of large panels of analytes from a small volume of sample, it is necessary to verify whether these assays yield enough sensitivity and reproducibility when applied to the blood from neuropsychiatric patients. Therefore, we compared two multiplex immunoassays, the bead-based Luminex^® (Bio-Rad) and the electro-chemiluminescence-based V-plex^® (MesoScaleDiscovery), for the detection and quantification of 31 cytokines, chemokines and growth factors in both the sera and plasma of patients with major depressive episodes (MDE) and age- and sex-matched healthy control subjects during a 30-week period. Although both platforms exhibited low coefficients of variability (CV) between the duplicates in the calibration curves, the linearity was better in general for the V-PLEX^® platform. However, neither platform was able to detect the absolute values for all of the tested analytes. Among the 16 analytes that were detected by both assays, the intra-assay reproducibility was in general better with the V-PLEX^® platform. Although it is not a general rule that the results from sera and plasma will be correlated, consistent results were more frequent with the V-PLEX^® platform. Furthermore, the V-PLEX^® results were more consistent with the gold standard ELISA simplex assay for IL-6 in both sera and plasma. The intra-individual variability of the measurements, among the sera and plasma for the 4 samples harvested from each healthy individual, was low for Eotaxin, G-CSF, IL-4, IL-7, IL-9, IL-12p40, IL-12p70, IL-15, MIP-1β, PDGF-BB, TNF, TNF-β and VEGF, but intermediate or high for IFN-γ, IL-6, IL-8, IL-10, and IP10. Together, these data suggest that extreme caution is needed in translating the results of multiplex cytokine profiling into biomarker discovery in psychiatry.

Serum polybrominated diphenyl ether (PBDE) concentrations in relation to biomarkers of oxidative stress and inflammation: The National Health and Nutrition Examination Survey 2003-2004

Exposure to polybrominated diphenyl ethers (PBDEs) has been associated with various adverse health outcomes related to liver, neural and endocrine systems. Some of these may be the result of PBDE-induced oxidative stress or inflammation, but these associations have been explored minimally in humans. In the present study we examined the relationship between PBDE concentrations and biomarkers of oxidative stress and inflammation measured in blood samples among a representative US sample from the National Health and Nutrition Examination Survey. Oxidative stress biomarkers showed no significant associations with PBDEs in adjusted regression models. For inflammation biomarkers, we observed small but statistically significant positive associations between BDE-153 and alkaline phosphatase (percent change with an interquartile range [IQR] increase in BDE-153=0.82, 95% confidence interval [CI]=0.01, 1.65) and absolute neutrophil count (percent change with IQR increase in BDE-153=0.53%, 95% CI=0.03, 1.04). Associations with other PBDE congeners and inflammation markers were generally positive but did not reach statistical significance. These results are consistent with human research of oxidative stress and inflammation in response to PBDE congeners and mixtures, and support previous reports of inflammation in response to PBDE treatment in animal and in vitro studies. More detailed toxicological and epidemiologic research in humans is needed to confirm the present results, and to determine the potential clinical and public health significance of these findings.

Multiplex assay reliability and long-term intra-individual variation of serologic inflammatory biomarkers

BACKGROUND

Circulating cytokines, chemokines, and soluble cytokine receptors can serve as biomarkers of inflammation and immune dysregulation. Good reliability of multiplex platforms, which allow for simultaneous, comprehensive biomarker assessment, is critical for their utility in epidemiologic studies. We examined the reliability of the Meso-Scale Discovery (MSD) platform to simultaneously quantitate 15 cytokines and chemokines and the Luminex platform (R&D Systems) to quantitate 5 soluble receptors and 2 chemokines and cytokines and evaluated long-term within-person correlation of these biomarkers.

METHODS

The detectability and reliability of these assay systems were assessed using the same external controls across plates and archived sera from 250 HIV^- men in the Multicenter AIDS Cohort Study. Using up to four visits per person from 1984 to 2009, age-adjusted intraclass correlation coefficients (ICC) of biomarkers with >80% detectability (CCL11, CXCL8, CXCL10, CCL2, CCL4, CCL13, CCL17, CXCL13, IL-10, IL-12p70, IL-6, TNF-α, BAFF, sCD14, sCD27, sgp130, sIL-2Rα, and sTNF-R2) were obtained using linear mixed models.

RESULTS

Most biomarkers were detectable in 80% of control samples; IFN-γ, GM-CSF, and IL-2 were undetectable in >20% of samples. Among the HIV-uninfected men, most biomarkers showed fair to strong within-person correlation (ICC>0.40) up to 15years. The ICC for CXCL8 was good in the short term but decreased with increasing time between visits, becoming lower (ICC<0.40) after 8years.

CONCLUSIONS

These multiplexed assays showed acceptable reliability for use in epidemiologic research, despite some technical variability and limitations in cytokine quantitation. Most biomarkers displayed moderate-to-excellent intra-individual variability over the long term, suggesting their utility in prospective studies investigating etiologic associations with diverse chronic conditions.

Prediagnostic circulating inflammation markers and endometrial cancer risk in the prostate, lung, colorectal and ovarian cancer (PLCO) screening trial

Inflammation is proposed to increase risk of developing endometrial cancer, but few prospective epidemiologic studies have investigated the relationship between circulating inflammation markers and endometrial cancer risk. In a nested case-control study within the PLCO Screening Trial we measured serum levels of 64 inflammation-related biomarkers in 284 incident endometrial cancer cases and 284 matched controls. Using multivariable logistic regression inflammation markers were evaluated individually and combined into a cross-validated inflammation score. Of 64 markers, 22 were associated with endometrial cancer risk at p < 0.05 and 17 of 22 markers remained associated after multiple testing corrections. After adjusting for BMI and estradiol, SERPINE1 [quartile(Q)4 vs. Q1 odds ratio (OR) (95% confidence interval (CI)), p trend = 2.43 (0.94-6.29), 0.03] and VEGFA [2.56 (1.52-4.30), 0.0002] were positively associated with endometrial cancer risk, while CCL3 [0.46 (0.27-0.77), 0.01], IL13 [0.55 (0.33-0.93), 0.01], IL21 [0.52 (0.31-0.87), 0.01], IL1B [0.51 (0.30-0.86), 0.01] and IL23 [0.60 (0.35-1.03), 0.02] were inversely associated with risk. We observed large differences in ORs across BMI-inflammation score categories. Endometrial cancer risk was most pronounced among obese women with the highest inflammation score tertile (T) [10.25 (3.56-29.55) vs. normal BMI/T1]. Several inflammation markers were prospectively associated with endometrial cancer, including adipokines, pro- and anti-inflammatory cytokines, angiogenic factors and acute phase proteins. Inverse associations with anti-inflammatory markers (IL13, IL21), other inflammation markers/mediators (CCL3, IL1B, IL23), and a robust positive association between VEGFA and endometrial cancer risk were independent of BMI and estradiol, suggesting that these factors may influence risk through other mechanisms.

Cytokines as Biomarkers of Pancreatic Ductal Adenocarcinoma: A Systematic Review

OBJECTIVES

A systematic review of the role of cytokines in clinical medicine as diagnostic, prognostic, or predictive biomarkers in pancreatic ductal adenocarcinoma was undertaken.

MATERIALS AND METHODS

A systematic review was conducted according to the 2009 PRISMA guidelines. PubMed database was searched for all original articles on the topic of interest published until June 2015, and this was supplemented with references cited in relevant articles. Studies were evaluated for risk of bias using the Quality in Prognosis Studies tools.

RESULTS

Forty one cytokines were investigated with relation to pancreatic ductal adenocarcinoma (PDAC) in 65 studies, ten of which were analyzed by more than three studies. Six cytokines (interleukin[IL]-1β, -6, -8, -10, vascular endothelial growth factor, and transforming growth factor) were consistently reported to be increased in PDAC by more than four studies; irrespective of sample type; method of measurement; or statistical analysis model used. When evaluated as part of distinct panels that included CA19-9, IL-1β, -6 and -8 improved the performance of CA19-9 alone in differentiating PDAC from healthy controls. For example, a panel comprising IL-1β, IL-8, and CA 19-9 had a sensitivity of 94.1% vs 85.9%, specificity of 100% vs 96.3%, and area under the curve of 0.984 vs 0.925. The above-mentioned cytokines were associated with the severity of PDAC. IL-2, -6, -10, VEGF, and TGF levels were reported to be altered after patients received therapy or surgery. However, studies did not show any evidence of their ability to predict treatment response.

CONCLUSION

Our review demonstrates that there is insufficient evidence to support the role of individual cytokines as diagnostic, predictive or prognostic biomarkers for PDAC. However, emerging evidence indicates that a panel of cytokines may be a better tool for discriminating PDAC from other non-malignant pancreatic diseases or healthy individuals.

Inflammatory evidence for the psychosis continuum model

BACKGROUND

Inflammation and immune activation have been implicated in the pathophysiology of severe mental disorders. Previous studies of inflammatory markers, however, have been limited with somewhat inconsistent results.

AIMS

We aimed to determine the effect sizes of inflammatory marker alterations across diagnostic groups of the psychosis continuum and investigate association to antipsychotic medications.

METHODS

Plasma levels of soluble tumor necrosis factor receptor 1 (sTNF-R1), interleukin 1 receptor antagonist (IL-1Ra), osteoprotegerin (OPG), and von Willebrand factor (vWf) were measured in patients (n=992) with schizophrenia spectrum (SCZ, n=584), schizoaffective disorder (SA, n=93), affective spectrum disorders (AFF, n=315), and healthy controls (HC, n=638).

RESULTS

Levels of sTNF-R1 (p=1.8×10(-8), d=0.23) and IL-1Ra (p=0.002, d=0.16) were increased in patients compared to HC. The SCZ group had higher levels of sTNF-R1 (p=8.5×10(-8), d=0.27) and IL-1Ra (p=5.9×10(-5), d=0.25) compared to HC, and for sTNF-R1 this was also seen in the SA group (p=0.01, d=0.3) and in the AFF group (p=0.002, d=0.12). Further, IL-1Ra (p=0.004, d=0.25) and vWf (p=0.02, d=0.21) were increased in the SCZ compared to the AFF group. There was no significant association between inflammatory markers and use of antipsychotic medication.

CONCLUSION

We demonstrate a small increase in sTNF-R1 and IL-1Ra in patients with severe mental disorders supporting a role of inflammatory mechanisms in disease pathophysiology. The increase was more pronounced in SCZ compared to AFF supporting a continuum psychosis model related to immune factors.

High predictive value of immune-inflammatory biomarkers for schizophrenia diagnosis and association with treatment resistance

OBJECTIVES

Recent schizophrenia (SCZ) research aims to establish biomarkers with high predictive value for the diagnosis, severity of illness or treatment resistance. SCZ is accompanied by activated immune-inflammatory pathways, including increased levels of cytokines and chemokines, but few studies tried to identify predictive properties of such measures.

METHODS

We included 54 medicated SCZ patients and 118 healthy controls and examined 15 cytokines and chemokines. Possible associations between these immune-inflammatory biomarkers and the diagnosis of SCZ, severity of illness and treatment resistance were investigated.

RESULTS

SCZ is associated with a specific cytokine - chemokine profile, i.e., increased CCL11, MIP-1α, sTNF-R1 and sTNF-R2 levels, and decreased levels of IP-10, TNF-α, IL-2 and IL-4. The combination of five biomarkers (sTNF-R1, sTNF-R2, CCL11, IP-10, IL-4) may predict the diagnosis of SCZ with a sensitivity of 70.0% and a specificity of 89.4%. There was a weak association between the negative symptoms and biomarkers, i.e., IL-2 (inversely) and CCL11 (positively). Patients with treatment resistance showed increased levels of sTNF-R1, sTNF-R2 and MCP-1.

CONCLUSIONS

The findings of this study reinforce that SCZ is associated with a pro-inflammatory profile and suggest that some immune mediators may be used as reliable biomarkers for the diagnosis of SCZ and treatment resistance.

Bioanalytical chemistry of cytokines--a review

Cytokines are bioactive proteins produced by many different cells of the immune system. Due to their role in different inflammatory disease states and maintaining homeostasis, there is enormous clinical interest in the quantitation of cytokines. The typical standard methods for quantitation of cytokines are immunoassay-based techniques including enzyme-linked immusorbent assays (ELISA) and bead-based immunoassays read by either standard or modified flow cytometers. A review of recent developments in analytical methods for measurements of cytokine proteins is provided. This review briefly covers cytokine biology and the analysis challenges associated with measurement of these biomarker proteins for understanding both health and disease. New techniques applied to immunoassay-based assays are presented along with the uses of aptamers, electrochemistry, mass spectrometry, optical resonator-based methods. Methods used for elucidating the release of cytokines from single cells as well as in vivo collection methods are described.

Proinflammatory and anti-inflammatory cytokine changes related to menopause

The aim of the study

The aim of the study was to determine menopause-related changes in serum levels of main proinflammatory and anti-inflammatory cytokines.

Material and methods

The study included 175 women, who were divided into 5 study groups (group 1 – fertile women; group 2 – pre- and perimenopausal women; group 3 – postmenopausal women; group 4 – surgically induced menopausal women; group 5 – women with chronic inflammatory pathology). We evaluated the serum levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-17, IL-20 and of the tumour necrosis factor (TNF)α with the use of two multiplex cytokine kits. We also determined the serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), 17β-estradiol (17β-E2), progesterone (P), dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) using sandwich ELISA.

Results

The serum level of IL-1β, IL-8 and TNF-α in women with natural menopause and in women with surgically induced menopause is significantly higher than in fertile women in the control group. In patients with surgically induced menopause and in women with natural menopause, IL-8 serum levels are similar to those seen in patients with chronic inflammatory diseases. There is a statistically significant decrease in serum levels of IL-20 in women with natural or surgical menopause than in fertile and premenopausal women.

Conclusions

Women in menopause have elevated levels of the key proinflammatory cytokines, i.e. IL-1β, IL-8 and TNF-α and low serum levels of IL-20 in comparison with fertile women.

Intraindividual variability over time in plasma biomarkers of inflammation and effects of long-term storage

PURPOSE

Systemic measures of chronic inflammation, often based on a single blood draw, are frequently used to study the associations between inflammation and chronic diseases such as cancer. However, more information is needed on the measurement error in these markers due to laboratory error, within-person variation over time, and long-term storage.

METHODS

We investigated the intraindividual variability of inflammation markers C-reactive protein (CRP), interleukin-6 (IL-6), and soluble tumor necrosis factor receptors I and II (sTNFRI and II) in a subsample of the Seattle Barrett's esophagus study cohort. Two fasting blood samples were collected between 1995 and 2009 from 360 participants on average 1.8 years apart. CRP, IL-6, and sTNF receptor levels were measured by immunonephelometry, ELISA, and multiplex assays, respectively. Intra- and inter-batch coefficients of variation (CV) were estimated using blinded pooled samples within each batch. Intraclass correlations (ICCs) were computed using random effects ANOVA.

RESULTS

Intra- and inter-batch CVs for the pooled plasma aliquots were low (2.4-8.9 %), suggesting little laboratory variability. Reliability over time was excellent for sTNF receptors (ICCsTNF-RI = 0.89, ICCsTNF-RII = 0.85) and fair-to-good for CRP and IL-6 (ICCCRP = 0.55, ICCIL-6 = 0.57). For samples stored for over 13 years, the ICCs for CRP and IL-6 were decreased but those for sTNF receptors were unaffected.

CONCLUSION

sTNF receptor levels are more stable within person over time than CRP or IL-6. Long-term storage of samples appears to increase the variability of CRP and IL-6 measures, while the reliability of soluble TNF receptor measures was not affected by storage time.

An exploratory investigation of links between changes in adipokines and quality of life in individuals undergoing weight loss interventions: possible implications for cancer research

OBJECTIVE

Obesity has been linked to a wide spectrum of malignancies, with the strongest association demonstrated for endometrial cancer. Although the mechanisms are not yet entirely clear, a number of risk biomarkers have been proposed, including altered adipokines. Systemic levels of these adipose derived molecules have also been linked in prior research to self-reported quality of life (QOL). The study objective was to examine the hypothesis that adipokine changes during intentional weight loss may be associated with changes in QOL.

METHODS

Fifty-two female participants were selected from two behavioral weight loss trials (SMART and PREFER) on the basis of achieving successful weight loss at 6month assessment, availability of blood samples and completion of standard SF-36 QOL questionnaires. Levels of adiponectin, leptin, and resistin were measured using xMAP immunoassays. Changes in QOL were examined using linear regression models in relation to pre- and post-intervention changes in biomarker levels and BMI.

RESULTS

Significant changes between pre- and post-intervention were observed for leptin. Controlling for baseline BMI, leptin was the only biomarker that predicted change in QOL (Physical Component Scale, PCS). Linear regression models demonstrated that leptin continued to be a significant predictor of change in PCS when other possible predictor variables were included in the model.

CONCLUSIONS

This study is among the first to demonstrate that changes in PCS may be regulated by levels of both metabolic variables and adipokines. An improved understanding of biological mechanisms associated with weight loss and the role of QOL may help guide preventive strategies for obesity-associated cancers.

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.

Statistical methods for the assessment of EQAPOL proficiency testing: ELISpot, Luminex, and Flow Cytometry

In September 2011 Duke University was awarded a contract to develop the National Institutes of Health/National Institute of Allergy and Infectious Diseases (NIH/NIAID) External Quality Assurance Program Oversight Laboratory (EQAPOL). Through EQAPOL, proficiency testing programs are administered for Interferon-γ (IFN-γ) Enzyme-linked immunosorbent spot (ELISpot), Intracellular Cytokine Staining Flow Cytometry (ICS) and Luminex-based cytokine assays. One of the charges of the EQAPOL program was to apply statistical methods to determine overall site performance. We utilized various statistical methods for each program to find the most appropriate for assessing laboratory performance using the consensus average as the target value. Accuracy ranges were calculated based on Wald-type confidence intervals, exact Poisson confidence intervals, or via simulations. Given the nature of proficiency testing data, which has repeated measures within donor/sample made across several laboratories; the use of mixed effects models with alpha adjustments for multiple comparisons was also explored. Mixed effects models were found to be the most useful method to assess laboratory performance with respect to accuracy to the consensus. Model based approaches to the proficiency testing data in EQAPOL will continue to be utilized. Mixed effects models also provided a means of performing more complex analyses that would address secondary research questions regarding within and between laboratory variability as well as longitudinal analyses.

Baseline levels and temporal stability of 27 multiplexed serum cytokine concentrations in healthy subjects

BACKGROUND

Cytokines are humoral molecules that elicit regulatory function in immunologic pathways. The level and type of cytokine production has become critical in distinguishing physiologic from pathologic immune conditions. Cytokine profiling has become an important biomarker discovery tool in monitoring of the immune system. However, the variations in cytokine levels in individual subjects over time in healthy individuals have not been extensively studied. In this study, we use multiplex bead arrays to evaluate 27 analytes in paired serum samples taken seven days apart from 144 healthy individuals in order to assess variations over a short time period.

METHODS

Fluorescent bead-based immunoassay (Luminex) was used to measure 27 analytes in serum samples. Measurements were performed on matched samples from 144 healthy donors. To assess inter-plate variability, one arbitrarily selected serum sample was analyzed on each of the first ten plates as bridge sample.

RESULTS

Using the bridge sample, we showed minimal inter-plate variations in the measurement of most analytes. In measurement of cytokines from the 144 patients at two time points, we found that three cytokines (IL-2, IL-15 and GM-CSF) were undetectable and five analytes (RANTES, MCP-1, VEGF, MIP-1β and PDGF-BB) showed significant difference in concentrations at Day 0 compared to Day 7.

CONCLUSIONS

The current study demonstrated higher variations in cytokine levels among individuals than were observed for samples obtained one week apart from identical donors. These data suggest that a serum sample from each subject for use as a baseline measurement is a better control for clinical trials rather than sera from a paired cohort.

Temporal stability of serum concentrations of cytokines and soluble receptors measured across two years in low-risk HIV-seronegative men

BACKGROUND

Prospective cohort studies often quantify serum immune biomarkers at a single time point to determine risk of cancer and other chronic diseases that develop years later. Estimates of the within-person temporal stability of serum markers partly assess the utility of single biomarker measurements and may have important implications for the design of prospective studies of chronic disease risk.

METHODS

Using archived sera collected from 200 HIV-seronegative men at three visits spaced over approximately 2 years, concentrations of 14 biomarkers (ApoA1, sCD14, sgp130, sIL-6R, sIL-2Rα, sTNFR2, BAFF/BLyS, CXCL13, IFN-γ, interleukin [IL]-1β, IL-6, IL-8, IL-10, and TNF-α) were measured in a single laboratory. Age- and ethnicity-adjusted intraclass correlation coefficients (ICC) were calculated for each biomarker, and mixed linear regression models were used to examine the influence of age, ethnicity, season, and study site on biomarker concentrations.

RESULTS

Across all three study visits, most biomarkers had ICC values indicating fair to excellent within-person stability. ApoA1 (ICC = 0.88) and TNF-α (ICC = 0.87) showed the greatest stability; the ICC for IL-8 (ICC = 0.33) was remarkably less stable. The ICCs were similar when calculated between pairs of consecutive visits. The covariables did not influence biomarker levels or their temporal stability. All biomarkers showed moderate to strong pairwise correlations across visits.

CONCLUSIONS

Serum concentrations of most evaluated immune biomarkers displayed acceptable to excellent within-person temporal reliability over a 2-year period. Further investigation may be required to clarify the stability of IL-8.

IMPACT

These findings lend support to using these serologic immune biomarkers in prospective studies investigating associations with chronic diseases.

Detectability and reproducibility of plasma levels of chemokines and soluble receptors

BACKGROUND

Multiplex assays are available to measure an array of circulating chemokines, soluble cytokine receptors and growth factors. However, there is limited information regarding whether these analytes are suitable for large-scale epidemiological studies to assess their relationships with chronic diseases, including cancer.

METHODS

We examined detectability, assay repeatability, and 3-year within-subject reproducibility of plasma levels of 25 chemokines and 11 soluble receptors of cytokines and growth factors selected from the Human Millipore Panels. Plasma samples were obtained from 36 men (average age 62 years) and 17 women (average age 32 years) who participated in two epidemiological studies. Inter-assay and within-subject reproducibility were assessed by intraclass correlation coefficients (ICC).

RESULTS

All analytes, except lymphotactin (47% detectability), were detectable in >90% of plasma samples. Inter-assay reproducibility for all analytes in 36 men tested three times on separate days were good to excellent (ICCs: 0.71-1.00). Within-subject reproducibility in 17 women sampled three times in three years were excellent (ICC ≥ 0.75) for five chemokines (eotaxin, fractalkine, 6Ckine, eotaxin 3, and SDF-1α+β) and three soluble receptors (sIL-1R2, sIL-4R and sVEGFR2); ICCs were fair to good (0.4 ≤ ICC < 0.75) for 15 chemokines and eight soluble receptors. However, five chemokines (GRO, IP-10, MIP-1β, BCA-1, and MIP-3α) had ICC < 0.4, suggesting biological variability.

CONCLUSION

Multiplex assays for plasma levels of selected chemokines and soluble receptors showed good to excellent assay detectability and repeatability. Most analytes also had good 3-year within-subject reproducibility, indicating that a single measurement of these analytes may be used to assess biomarker-disease associations.

Reproducibility of metabolomic profiles among men and women in 2 large cohort studies

BACKGROUND

Rigorous studies are necessary to demonstrate suitability of metabolomics platforms to profile metabolites in archived plasma within epidemiologic studies of human disease, for which attenuation of effect estimates due to measurement error is a key concern.

METHODS

Using a liquid chromatography-tandem mass spectrometry platform, we quantified 257 metabolites from archived plasma to evaluate metabolite interassay reproducibility, reproducibility with delayed processing, and within-person reproducibility over time. Interassay reproducibility was assessed with CVs from 60 duplicate plasma samples donated by participants in the Nurses' Health Study and Health Professionals Follow-up Study, and 20 QC pool plasma replicates. Metabolite reproducibility over a 24- to 48-h processing delay (n = 48 samples) and within-person reproducibility over 1-2 years (n = 80 samples) were assessed using Spearman and intraclass correlation coefficients (ICCs).

RESULTS

CVs were <20% for 92% of metabolites and generally were similar by plasma anticoagulant type (heparin or EDTA) and fasting time. Approximately 75% of metabolites were reproducible over delays in processing of blood samples (Spearman correlation or ICC ≥ 0.75, comparing immediate and 24-h delayed processing). Carbohydrates and purine/pyrimidine derivatives were most adversely affected by the processing delay. Ninety percent of metabolites were reproducible over 1-2 years within individuals (Spearman correlation or ICC ≥ 0.4).

CONCLUSIONS

For potential use in epidemiologic studies, the majority of plasma metabolites had low CVs and were reproducible over a 24-h processing delay and within individuals over 1-2 years. Certain metabolites, such as carbohydrates and purine/pyrimidine derivatives, may be challenging to evaluate if samples have delayed processing.

Serum interleukin-6 associated with hepatocellular carcinoma risk: a nested case-control study

Inflammatory markers have been associated with increased risk of several cancers, including colon, lung, breast and liver, but the evidence is inconsistent. We conducted a nested case-control study in the longitudinal cohort of atomic-bomb survivors. The study included 224 hepatocellular carcinoma (HCC) cases and 644 controls individually matched to cases on gender, age, city and time and method of serum storage, and countermatched on radiation dose. We measured C-reactive protein (CRP) and interleukin (IL)-6 using stored sera obtained within 6 years before HCC diagnosis from 188 HCC cases and 605 controls with adequate volumes of donated blood. Analyses with adjustment for hepatitis virus infection, alcohol consumption, smoking habit, body mass index (BMI) and radiation dose showed that relative risk (RR) of HCC [95% confidence interval (CI)] in the highest tertile of CRP levels was 1.94 (0.72-5.51) compared to the lowest tertile (p = 0.20). RR of HCC (95% CI) in the highest tertile of IL-6 levels was 5.12 (1.54-20.1) compared to the lowest tertile (p = 0.007). Among subjects with BMI > 25.0 kg/m(2) , a stronger association was found between a 1-standard deviation (SD) increase in log IL-6 and HCC risk compared to subjects in the middle quintile of BMI (21.3-22.9 kg/m(2) ), resulting in adjusted RR (95% CI) of 3.09 (1.78-5.81; p = 0.015). The results indicate that higher serum levels of IL-6 are associated with increased HCC risk, independently of hepatitis virus infection, lifestyle-related factors and radiation exposure. The association is especially pronounced among subjects with obesity.

Interleukin 1 receptor antagonist and soluble tumor necrosis factor receptor 1 are associated with general severity and psychotic symptoms in schizophrenia and bipolar disorder

BACKGROUND

Previous studies suggest elevated inflammation in schizophrenia and bipolar disorder, with increased activity of the Interleukin 1 (IL-1), interleukin 6 (IL-6), tumor necrosis factor (TNF)-alpha, von Willebrand factor (vWf) and osteoprotegerin (OPG). It is unclear how immune activation is involved in the psychopathology. We investigated if elevated inflammation was associated with disease severity (trait) or current symptom level (state), comparing psychotic with general characteristics.

METHODS

Plasma levels of sTNF receptor 1 (sTNF-R1), IL-1 receptor antagonist (IL-1Ra), IL-6, vWf and OPG were measured with ELISA techniques in 322 patients with schizophrenia spectrum and bipolar disorder. Current symptom level (state) was measured with Global Assessment of Functioning (GAF) and Positive and Negative Syndrome Scale (PANSS). Disease severity (trait) was measured with premorbid adjustment scale (PAS), age at onset, number of psychotic episodes and number and length of hospitalizations.

RESULTS

After controlling for confounders, IL-1Ra and TNF-R1 were independently associated with GAF, and significantly correlated with PANSS negative and positive, respectively. In addition, Il-1Ra was associated with PAS, and sTNF-R1 with number of hospitalizations and psychotic episodes. VWf was significantly correlated with psychotic episodes, OPG with hospitalizations and IL-6 with history of psychosis. Linear regression analysis showed that GAF remained associated with sTNF-R1 and IL-1Ra with PANSS, after controlling for the other clinical measures.

CONCLUSIONS

This supports that inflammatory markers, particularly IL-1Ra and sTNF-R1 are associated with both general disease severity and psychotic features. This supports a role of immune activation in the core pathological mechanisms of severe mental disorders.

Effect of anticoagulants on multiplexed measurement of cytokine/chemokines in healthy subjects

INTRODUCTION

Cytokines are humoral regulatory molecules that act together in immunologic pathways. Monitoring cytokines and their variations within physiologic ranges is critical for biomarker discovery. Therefore, we evaluated the performance characteristics of 72 analytes measured by multiplex cytokine immunoassay, with an emphasis on the differences of analytes measured in serum compared to plasma, and, in plasma, on the impact of anticoagulants on the cytokine measurement.

METHODS

We used fluorescent bead-based (Luminex) immunoassay kits to simultaneously measure 72 analytes. We tested serum and plasma samples from 11 matched donors. Plasma samples were anti-coagulated with sodium heparin, sodium citrate dextrose and ethylene diamine tetra-acetic acid (EDTA), respectively.

RESULTS

Of the 72 cytokines, 12 were undetectable in all types of specimen samples. Nineteen analytes, including PDGF-bb, IL-4, IL-8, IL-9, FGF-b, PAI-1, CXCL-5, CCL-5, CD40L, EGF, VEGF, IL-2ra, IL-3, SDF-1a, PCT, MCP-3, GIP, IL-16 and fibrinogen, showed significant differences between measurements in serum and all types of plasma, regardless of anticoagulant. Among plasma samples, 10 analytes (eotaxin, SCGF-b, MCP-1, SCF, MIP-1b, VEGF, RANTES, PDGF-b, PAI-1 and ITAC) showed significantly higher concentrations in heparinized plasma compared to citrated and EDTA plasma. IP-10, and CTAK were the only 2 cytokines that presented different concentrations in citrate and EDTA plasma.

CONCLUSIONS

With their small volume, low cost per test, and multiplex capacity, Luminex-based cytokine assays have enormous potential utility for screening in epidemiologic studies. In our study, we showed that many cytokines' concentrations differed between serum and plasma samples, and that different anticoagulants used in preparation of plasma samples also affected the measurement of some cytokines. There was no optimal sample preparation that was clearly superior for the measurement of all analytes measured. Ultimately, the utility of cytokine measurement, as biomarker or to monitor the immune system, will depend on attention to detail in the collection and processing of samples in addition to assay precision.

Adipokines linking obesity with colorectal cancer risk in postmenopausal women

Mechanistic associations between obesity and colorectal cancer remain unclear. In this study, we investigated whether adipokines are risk factors for colorectal cancer and whether they may mediate its association with obesity. In a case-cohort study nested within the Women's Health Initiative cohort of postmenopausal women, baseline plasma samples from 457 colorectal cancer cases and 841 subcohort subjects were assayed for seven adipokines-adiponectin, leptin, plasminogen activator inhibitor-1 (PAI-1), resistin, hepatocyte growth factor, interleukin-6 (IL-6), and TNF-α. Serum insulin and estradiol values measured previously were also available for data analysis. After adjusting for age, race, smoking, colonoscopy history, and estrogen level, a low level of anti-inflammatory adiponectin and high levels of proinflammatory leptin, PAI-1, and IL-6 were associated with increased colorectal cancer risk, though only leptin remained significant after further adjustment for insulin [HRs comparing extreme quartiles (HR(Q4-Q1)), 1.84; 95% CI, 1.17-2.90]. Mediation analyses showed that leptin and insulin partially explained the association between waist circumference and colorectal cancer and attenuated it by 25% and 37%, respectively, with insulin being a significant mediator (P = 0.041). Our findings support the conclusion that adipokines involved in inflammation are associated with colorectal cancer risk, but that their effects may be mediated mostly by insulin, with leptin exerting an independent effect. Hyperinsulinemia and hyperleptinemia may therefore partially explain the adiposity association with colorectal cancer in postmenopausal women.

Reliability of serum biomarkers of inflammation from repeated measures in healthy individuals

BACKGROUND

Biomarkers of low-grade systemic inflammation are used to study the associations of inflammation with chronic diseases, including cancer. However, relatively little is known about the intraindividual variability of most of these measures.

METHODS

Fasting serum samples, collected at baseline and the end of ≥3-week washout periods in a four-diet crossover feeding trial, were used to measure the inflammatory markers high sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-8, and soluble TNF receptor (sTNFR) I and II. Participants included 62 men and women for analyses of IL-6 and CRP and 56 for analyses of IL-8, TNF-α, and sTNFRs, aged 20 to 40, who were free of factors known to influence inflammation, for example, chronic disease, medication use, heavy alcohol use, smoking, and obesity (body mass index >30 kg/m(2)). Intraclass correlations (ICC) were estimated using random effects ANOVA, across all four time points (~6 weeks apart).

RESULTS

ICCs for TNF-α and sTNFR I and II were very high: ICC = 0.92 [95% confidence interval (CI), 0.89-0.96], 0.92 (95% CI, 0.88-0.95), and 0.90 (95% CI, 0.85-0.94), respectively. ICCs for IL-8 and hsCRP were 0.73 (95% CI, 0.63-0.83) and 0.62 (95% CI, 0.49-0.75), respectively. The ICC for IL-6 was considerably lower, ICC = 0.48 (95% CI, 0.36-0.62). Three measures of IL-6 would be needed to achieve a reliability coefficient (Cronbach α) of 0.75.

CONCLUSIONS

With the exception of IL-6, reliability of all inflammatory markers in our panel was high.

IMPACT

This suggests that a single measure accurately captures the short-term (e.g., 4-6 months) variability within an individual.

Inflammation marker and risk of pancreatic cancer: a nested case-control study within the EPIC cohort

Background:

Established risk factors for pancreatic cancer include smoking, long-standing diabetes, high body fatness, and chronic pancreatitis, all of which can be characterised by aspects of inflammatory processes. However, prospective studies investigating the relation between inflammatory markers and pancreatic cancer risk are scarce.

Methods:

We conducted a nested case–control study within the European Prospective Investigation into Cancer and Nutrition, measuring prediagnostic blood levels of C-reactive protein (CRP), interleukin-6 (IL-6), and soluble receptors of tumour necrosis factor-α (sTNF-R1, R2) in 455 pancreatic cancer cases and 455 matched controls. Odds ratios (ORs) were estimated using conditional logistic regression models.

Results:

None of the inflammatory markers were significantly associated with risk of pancreatic cancer overall, although a borderline significant association was observed for higher circulating sTNF-R2 (crude OR=1.52 (95% confidence interval (CI) 0.97–2.39), highest vs lowest quartile). In women, however, higher sTNF-R1 levels were significantly associated with risk of pancreatic cancer (crude OR=1.97 (95% CI 1.02–3.79)). For sTNF-R2, risk associations seemed to be stronger for diabetic individuals and those with a higher BMI.

Conclusion:

Prospectively, CRP and IL-6 do not seem to have a role in our study with respect to risk of pancreatic cancer, whereas sTNF-R1 seemed to be a risk factor in women and sTNF-R2 might be a mediator in the risk relationship between overweight and diabetes with pancreatic cancer. Further large prospective studies are needed to clarify the role of proinflammatory proteins and cytokines in the pathogenesis of exocrine pancreatic cancer.

A multiplexed serum biomarker immunoassay panel discriminates clinical lung cancer patients from high-risk individuals found to be cancer-free by CT screening

INTRODUCTION

Clinical decision making in the setting of computed tomography (CT) screening could benefit from accessible biomarkers that help predict the level of lung cancer risk in high-risk individuals with indeterminate pulmonary nodules.

METHODS

To identify candidate serum biomarkers, we measured 70 cancer-related proteins by Luminex xMAP (Luminex Corporation) multiplexed immunoassays in a training set of sera from 56 patients with biopsy-proven primary non-small-cell lung cancer and 56 age-, sex-, and smoking-matched CT-screened controls.

RESULTS

We identified a panel of 10 serum biomarkers-prolactin, transthyretin, thrombospondin-1, E-selectin, C-C motif chemokine 5, macrophage migration inhibitory factor, plasminogen activator inhibitor, receptor tyrosine-protein kinase, erbb-2, cytokeratin fragment 21.1, and serum amyloid A-that distinguished lung cancer patients from controls with an estimated balanced accuracy (average of sensitivity and specificity) of 76.0 ± 3.8% from 20-fold internal cross-validation. We then iteratively evaluated this model in an independent test and verification case/control studies confirming the initial classification performance of the panel. The classification performance of the 10-biomarker panel was also analytically validated using enzyme-linked immunosorbent assays in a second independent case/control population, further validating the robustness of the panel.

CONCLUSIONS

The performance of this 10-biomarker panel-based model was 77.1% sensitivity/76.2% specificity in cross-validation in the expanded training set, 73.3% sensitivity/93.3% specificity (balanced accuracy 83.3%) in the blinded verification set with the best discriminative performance in stage I/II cases: 85% sensitivity (balanced accuracy 89.2%). Importantly, the rate of misclassification of CT-screened controls was not different in most control subgroups with or without airflow obstruction or emphysema or pulmonary nodules. These biomarkers have potential to aid in the early detection of lung cancer and more accurate interpretation of indeterminate pulmonary nodules detected by CT screening.

Serum PAI-1 is a novel predictor for response to pegylated interferon-α-2b plus ribavirin therapy in chronic hepatitis C virus infection

Obesity and insulin resistance have been reported as negative predictors for sustained virological response (SVR) in hepatitis C virus (HCV) genotype 1 infected patients treated with pegylated interferon-α plus ribavirin. They are also known to affect serum levels of several cytokines including adipocytokines. But the association between these cytokines and treatment outcome has not been fully elucidated. We examined pretreatment serum levels of 14 cytokines among 190 patients who were treated with pegylated interferon-α-2b plus ribavirin for chronic HCV-1b infection with high viral load (≥ 5 log IU/mL) and analyzed their contribution to treatment response. Plasminogen activator inhibitor-1 (PAI-1), vascular endothelial growth factor, and 11 clinical factors showed significant association with SVR in univariate logistic regression analysis. Four significant factors in multivariate analysis; serum PAI-1 (odds ratio [OR] = 15.42), body mass index (OR = 4.56), rs8099917 (OR = 4.95) and fibrosis stage (OR = 5.18) were identified as independent predictors. We constructed a simple and minimally invasive prediction score for SVR based on the presence of these factors except for fibrosis stage. The accuracy of this score was 73%, and was confirmed using an independent validation cohort consisting of 31 patients (68%). The strongest correlation was between PAI-1 level and platelet count (r = 0.38, P = 1.8 × 10(-7)), and PAI-1 level was inversely correlated with fibrosis stage. Serum PAI-1 is a novel predictor for the response to combination therapy against chronic HCV-1b infection and may be associated with liver fibrosis.

Longitudinal evaluation of cancer-associated biomarkers before and after weight loss in RENEW study participants: implications for cancer risk reduction

INTRODUCTION

Obesity is a major risk factor for the development of endometrial cancer (EC). An improved understanding of biologic mechanisms associated with weight loss, including alteration in inflammation, hormonal balance, and cancer antigens expression may lead to the development of effective cancer prevention strategies. The goal of this study was to explore longitudinal biomarker changes in obese women who underwent weight loss intervention, testing the hypothesis biomarker levels can be altered through intentional weight loss.

METHODS

Serum samples from 89 participants with Class II and Class III obesity and 43 non morbidly obese comparisons were obtained in Re-Energize with Nutrition, Exercise and Weight Loss (RENEW) study as previously reported. Twenty-one bead-based xMAP immunoassays were utilized, including cancer-associated antigens, cytokines, chemokines, and hormones. One-way repeated measures ANOVA was used to examine the association between changes in biomarker expression levels over time (baseline, 6 months and 12 months). Linear mixed effects models were used to examine longitudinal relationships between biomarker expression levels.

RESULTS

Mean levels of VEGF, soluble E-selectin, GH, adiponectin, IL-6, IL-7, CA-125, and IGFBP-1 significantly differed between time periods. In adjusted mixed linear models, decreasing BMI was significantly associated with lower levels of soluble E-selectin and IL-6 and increases in GH, adiponectin, and IGFBP-1.

CONCLUSIONS

This is one of the first efforts to explore changes in cancer-associated biomarkers in a cohort of weight loss research participants at high risk for EC development. Our findings demonstrate that changes in the expression of markers can be achieved with weight loss intervention.

Affective symptoms are associated with markers of inflammation and immune activation in bipolar disorders but not in schizophrenia

OBJECTIVE

Elevated levels of inflammation are reported in bipolar disorders (BP), but how this relates to affective symptoms is unclear. We aimed to determine if immune markers that consistently have been reported elevated in BP were associated with depressive and manic symptoms, and if this was specific for BP.

METHODS

From a catchment area, 112 BP patients were included together with 153 schizophrenia (SCZ) patients and 239 healthy controls. Depression and mania were assessed and the patients were grouped into depressed, neutral, and elevated mood. We measured the immune markers tumor necrosis factor receptor 1 (sTNF-R1), interleukin 1 receptor antagonist (IL-1Ra), interleukin 6 (IL-6), high sensitive C-reactive protein (hsCRP), osteoprotegerin (OPG) and von Willebrand factor (vWf) which have been found increased in severe mental disorders.

RESULTS

In BP all inflammatory markers were lowest in depressed state, with significant group differences after control for confounders with respect to TNF-R1 (p = 0.04), IL-1Ra (p = 0.02), OPG (p = 0.004) and IL-6 (p = 0.005). STNF-R1 was positively correlated with the item elevated mood (p = 0.02) whereas sad mood was negatively correlated with OPG (p = 0.0003), IL-1Ra (p = 0.001) and IL-6 (p = 0.006). Compared to controls the neutral mood group had significantly higher levels of OPG (p = 0.0003) and IL-6 (p = 0.005), and the elevated mood group had higher levels of TNF-R1 (p = 0.000005) and vWf (p = 0.002). There were no significant associations between affective states orsymptoms in SCZ.

CONCLUSIONS

The current associations between inflammatory markers and affective symptomatology in BP and not SCZ suggest that immune related mechanisms are associated with core psychopathology of BP.

Intra-individual variability over time in serum cytokine levels among participants in the prostate, lung, colorectal, and ovarian cancer screening Trial

BACKGROUND

Serum measurements of cytokines, mediators of various B and T cell activities, are important markers of inflammation and immune dysregulation. We assessed the reproducibility of serum cytokine measurements over a five-year period among participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO).

METHODS

Levels of 13 cytokines [interleukin (IL) 1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, interferon-gamma (IFNγ), granulocyte macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-α (TNFα)] in stored sera from three collections (study baseline,+1 year, and+5 years) among 28 randomly selected PLCO participants were measured using a high-sensitivity Luminex xMap-based multiplex panel. Within- and between-subject components of variance were estimated from random effects models and were used to calculate the coefficient of variation (CV) and intraclass correlation coefficient (ICC) for analytes with <30% of samples below the limit of detection (LOD). Spearman correlation coefficients between measurements of the same analyte over time and between analytes were also calculated.

RESULTS

Among the six cytokines with <30% of samples below the LOD, we observed excellent reproducibility for IL-6, IL-7, IL-13, and TNFα (ICC≥0.73), and fair to good reproducibility for IL-8 (ICC=0.55) and IL-10 (ICC=0.60). Spearman correlation coefficients comparing paired measurements of each cytokine at baseline and at +5 years were high (ρ≥0.74) with the exception of IL-10 (ρ=0.44).

CONCLUSIONS

These results suggest that measurements of most of the cytokines evaluated in this study were highly reproducible over five-year periods.

Dietary inflammation factor rating system and risk of Alzheimer disease in elders

It has been suggested that inflammation is involved in Alzheimer disease (AD) pathogenesis. The aim of this study is to evaluate the association between inflammatory aspects of diet and incident AD risk. About 2258 nondemented elderly (age ≥ 65) in New York who provided dietary information at baseline were followed-up prospectively for AD development. We examined the composite total Inflammation Factor Rating (tIFR), as a measure of inflammatory impact of foods, in relation with (i) serum level of high-sensitivity C-reactive protein (hsCRP) and (ii) risk of incident AD using Cox proportional hazard model. The tIFR was not associated with serum hsCRP level. After an average of 4.0 years of follow-up, 262 participants developed incident AD. The tIFR was not associated with AD risk: compared with the lowest tertile of tIFR (most proinflammatory), hazard ratios (95% confidence interval) for the highest tertile (most anti-inflammatory) was 0.97 (0.69-1.35) (P-for-trend=0.71), in the adjusted model. We conclude that tIFR might not be a biologically relevant measure of the inflammatory impact of the diet. In addition, although it remains possible that tIFR might be related with some other aspects of inflammation not captured by hsCRP, lack of association with AD risk suggests its limited clinical utility.

Factors associated with inflammation markers, a cross-sectional analysis

Epidemiological studies have reported associations between circulating inflammation markers and risk of chronic diseases. It is of interest to examine whether risk factors for these diseases are associated with inflammation. We conducted a cross-sectional analysis to evaluate whether reproductive and lifestyle factors and circulating vitamin D were associated with inflammation markers, including C-reactive protein, cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα), and cytokine modulators (IL-1RA, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1/R2), among 616 healthy women. We confirmed associations of several inflammation markers with age and BMI. We also observed significantly higher levels of certain inflammation markers in postmenopausal vs. premenopausal women (TNFα, sIL-1RII, sIL-2Ra), with increasing parity (IL-12p40), and with higher circulating 25(OH) vitamin D (IL-13) and lower levels among current users of non-steroidal anti-inflammatory drugs (NSAIDs) (IL-1β, IL-2, IL-10, IL-12p70, and IL-12p40), current smokers (IL-4, IL-13, IL-12p40), and women with a family history of breast or ovarian cancer (IL-4, IL-10, IL-13). Our findings suggest that risk factors for chronic diseases (age, BMI, menopausal status, parity, NSAID use, family history of breast and ovarian cancer, and smoking) are associated with inflammation markers in healthy women.

Evaluation of multiplexed cytokine and inflammation marker measurements: a methodologic study

BACKGROUND

Chronic inflammation is etiologically related to several cancers. We evaluated the performance [ability to detect concentrations above the assay's lower limit of detection, coefficients of variation (CV), and intraclass correlation coefficients (ICC)] of 116 inflammation, immune, and metabolic markers across two Luminex bead-based commercial kits and three specimen types.

METHODS

From 100 cancer-free participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Trial, serum, heparin plasma, and EDTA plasma samples were utilized. We measured levels of 67 and 97 markers using Bio-Rad and Millipore kits, respectively. Reproducibility was assessed using 40 blinded duplicates (20 within-batches and 20 across-batches) for each specimen type.

RESULTS

A majority of markers were detectable in more than 25% of individuals on all specimen types/kits. Of the 67 Bio-Rad markers, 51, 52, and 47 markers in serum, heparin plasma, and EDTA plasma, respectively, had across-batch CVs of less than 20%. Likewise, of 97 Millipore markers, 75, 69, and 78 markers in serum, heparin plasma, and EDTA plasma, respectively, had across-batch CVs of less than 20%. When results were combined across specimen types, 45 Bio-Rad and 71 Millipore markers had acceptable performance (>25% detectability on all three specimen types and across-batch CVs <20% on at least two of three specimen types). Median concentrations and ICCs differed to a small extent across specimen types and to a large extent between Bio-Rad and Millipore.

CONCLUSIONS

Inflammation and immune markers can be measured reliably in serum and plasma samples using multiplexed Luminex-based methods.

IMPACT

Multiplexed assays can be utilized for epidemiologic investigations into the role of inflammation in cancer etiology.

Prediagnostic serum levels of cytokines and other immune markers and risk of non-hodgkin lymphoma

Although severe immune dysregulation is an established risk factor for non-Hodgkin lymphoma (NHL), it is unclear whether subclinical immune system function influences lymphomagenesis. To address this question, we conducted a nested case-control study within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial to investigate whether circulating levels of cytokines and other immune markers are associated with future risk of NHL. Selected cytokines [interleukin (IL)-4, IL-6, IL-10, and TNF-α] and other immune markers [soluble TNF receptor 1 (sTNF-R1), sTNF-R2, C-reactive protein, and sCD27] were measured in prediagnostic serum specimens from 297 incident NHL cases and 297 individually matched controls. ORs and 95% confidence intervals (CI) relating quartiles of analyte concentration to NHL risk were calculated by using conditional logistic regression. Statistically significant associations with increased NHL risk were observed for elevated serum levels of sTNF-R1 (quartile 4 vs. quartile 1: OR = 1.7, 95% CI: 1.1-2.8; P(trend) = 0.02) and sCD27 (OR = 5.3, 95% CI: 2.9-9.4; P(trend) < 0.0001). These associations remained in analyses of cases diagnosed longer than 6 years following blood collection (sTNF-R1: OR = 2.1, 95% CI: 1.0-4.0, P(trend) = 0.01; sCD27: OR = 4.1, 95% CI: 1.9-8.5, P(trend) = 0.0001). Elevated levels of IL-10, TNF-α and sTNF-R2 were also significantly associated with increased risk of NHL overall; however, these associations weakened with increasing time from blood collection to case diagnosis and were null for cases diagnosed longer than 6 years postcollection. Our findings for sTNF-R1 and sCD27, possible markers for inflammatory and B-cell stimulatory states, respectively, support a role for subclinical inflammation and chronic B-cell stimulation in lymphomagenesis.

Urinary phthalate metabolites in relation to biomarkers of inflammation and oxidative stress: NHANES 1999-2006

Phthalate esters are a class of compounds utilized extensively in widely-distributed consumer goods, and have been associated with various adverse health outcomes in previous epidemiologic research. Some of these health outcomes may be the result of phthalate-induced increases in oxidative stress or inflammation, which have been demonstrated in animal studies. The aim of this study was to explore the relationship between urinary phthalate metabolite concentrations and serum markers of inflammation and oxidative stress (C-reactive protein (CRP) and gamma glutamyltransferase (GGT), respectively). Subjects were participants in the National Health and Nutrition Examination Survey (NHANES) between the years 1999 and 2006. In multivariable linear regression models, we observed significant positive associations between CRP and mono-benzyl phthalate (MBzP) and mono-isobutyl phthalate (MiBP). There were CRP elevations of 6.0% (95% confidence interval (CI) 1.7-10.8%) and 8.3% (95% CI 2.9-14.0%) in relation to interquartile range (IQR) increases in urinary MBzP and MiBP, respectively. GGT was positively associated with mono(2-ethylhexyl) phthalate (MEHP) and an MEHP% variable calculated from the proportion of MEHP in comparison to other di(2-ethylhexyl) phthalate (DEHP) metabolites. IQR increases in MEHP and MEHP% were associated with 2.5% (95% CI 0.2-4.8%) and 3.7% (95% CI 1.7-5.7%) increases in GGT, respectively. CRP and GGT were also inversely related to several phthalate metabolites, primarily oxidized metabolites. In conclusion, several phthalate monoester metabolites that are detected in a high proportion of urine samples from the US general population are associated with increased serum markers of inflammation and oxidative stress. On the other hand, several oxidized phthalate metabolites were inversely associated with these markers. These relationships deserve further exploration in both experimental and observational studies.

Inflammatory signaling compromises cell responses to interferon alpha

Interferon alpha (IFNα) is widely used for treatment of melanoma and certain other malignancies. This cytokine as well as the related IFNβ exerts potent anti-tumorigenic effects; however, their efficacy in patients is often suboptimal. Here, we report that inflammatory signaling impedes the effects of IFNα/β. Melanoma cells can secrete pro-inflammatory cytokines that inhibit cellular responses to IFNα/β via activating the ligand-independent pathway for the phosphorylation and subsequent ubiquitination and accelerated degradation of the IFNAR1 chain of type I IFN receptor. Catalytic activity of the p38 protein kinase was required for IFNAR1 downregulation and inhibition of IFNα/β signaling induced by proinflammatory cytokines such as interleukin 1 (IL-1). Activation of p38 kinase inversely correlated with protein levels of IFNAR1 in clinical melanoma specimens. Inhibition of p38 kinase augmented the inhibitory effects of IFNα/β on cell viability and growth in vitro and in vivo. The roles of inflammation and p38 protein kinase in regulating cellular responses to IFNα/β in normal and tumor cells are discussed.

Circulating inflammation markers and risk of epithelial ovarian cancer

BACKGROUND

Factors contributing to chronic inflammation appear to be associated with increased risk of ovarian cancer. The purpose of this study was to assess the association between circulating levels of inflammation mediators and subsequent risk of ovarian cancer.

METHODS

We conducted a case-control study of 230 cases and 432 individually matched controls nested within three prospective cohorts to evaluate the association of prediagnostic circulating levels of inflammation-related biomarkers (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα, IL-1Ra, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1, and sTNF-R2) measured using Luminex xMap technology with risk of ovarian cancer.

RESULTS

We observed a trend across quartiles for IL-2 (OR(Q4 vs. Q1): 1.57, 95% CI: 0.98-2.52, P = 0.07), IL-4 (OR(Q4 vs. Q1): 1.50, 95% CI: 0.95-2.38, P = 0.06), IL-6 (OR(Q4 vs. Q1): 1.63, 95% CI: 1.03-2.58, P = 0.03), IL-12p40 (OR(Q4 vs. Q1): 1.60, 95% CI: 1.02-2.51, P = 0.06), and IL-13 (OR(Q4 vs. Q1): 1.42, 95% CI: 0.90-2.26, P = 0.11). Trends were also observed when cytokines were modeled on the continuous scale for IL-4 (P trend = 0.01), IL-6 (P trend = 0.01), IL-12p40 (P trend = 0.01), and IL-13 (P trend = 0.04). ORs were not materially different after excluding cases diagnosed less than 5 years after blood donation or when limited to serous tumors.

CONCLUSIONS AND IMPACT

This study provides the first direct evidence that multiple inflammation markers, specifically IL-2, IL-4, IL-6, IL-12, and IL-13, may be associated with risk of epithelial ovarian cancer, and adds to the evidence that inflammation is involved in the development of this disease.

Mediterranean diet, inflammatory and metabolic biomarkers, and risk of Alzheimer's disease

We aimed to investigate the association between adherence to the Mediterranean diet (MeDi) and Alzheimer's disease (AD) risk in a prospective study. Specifically, we analyzed reduced inflammation and improved metabolic profile as a potential medium through which the MeDi reduced the risk of AD. During a 4-year follow-up, 118 incident AD cases were identified among the 1219 non-demented elderly (age ≥ 65) subjects who provided dietary information and blood samples at baseline. We used high-sensitivity C-reactive protein (hsCRP) as an index of systemic inflammation, and fasting insulin and adiponectin as indexes of metabolic profile. We investigated whether there was a change in the association between MeDi and incident AD risk when the biomarkers were introduced into multivariable adjusted COX models. Better adherence to MeDi was associated with lower level of hsCRP (p =0.003), but not fasting insulin or adiponectin. Better adherence to MeDi was significantly associated with lower risk for AD: compared to those in the lowest tertile of MeDi, subjects in the highest tertile had a 34% less risk of developing AD (p-for-trend =0.04). Introduction of the hsCRP, fasting insulin, adiponectin, or combinations of them into the COX model did not change the magnitude of the association between MeDi and incident AD. Ultimately, the favorable association between better adherence to MeDi and lower risk of AD did not seem to be mediated by hsCRP, fasting insulin, or adiponectin. Other aspects of inflammatory and metabolic pathways not captured by these biomarkers, or non-inflammatory or non-metabolic pathways, may be relevant to the MeDi-AD association.