Development of ELISA on microplate for serum C-reactive protein and establishment of age-dependent normal reference range

Phosphorylcholine-Functionalized PEDOT-Gated Organic Electrochemical Transistor Devices for Ultra-Specific and Sensitive C-Reactive Protein Detection

Affinity-based organic electrochemical transistor (OECT) sensors offer an attractive approach to point-of-care diagnostics due to their extreme sensitivity and easy operation; however, their application in the real world is frequently challenged by the poor storage stability of antibody proteins and the interference from biofouling in complex biofluids. In this work, we developed an antibody-free and antifouling OECT biosensor to detect C-reactive protein (CRP) at ultra-high specificity and sensitivity. The key to this novel biosensor is the gate coated by phosphorylcholine-functionalized poly (3,4-ethylene dioxythiophene) (PEDOT-PC), which possesses large capacitance and low impedance, prevents biofouling of bovine serum albumin (BSA) and the fetal bovine serum (FBS), and interacts specifically with CRP molecules in the presence of calcium ions. This PEDOT-PC-gated OECT biosensor demonstrated exceptional sensitivity when detecting the CRP molecules at 10 pg/mL, while significantly depressing the signal from the nonspecific binding. This indicates that this biosensor could detect the CRP molecules directly without nonspecific binding blocking, the usual process for the earlier transistor sensors before detection. We envision that this PEDOT-PC-gated OECT biosensor platform may offer a potentially valuable tool for point-of-care diagnostics as it alleviates concerns about poor antibody stability and BSA blocking inconstancy.

Low-Cost Full-Range Detection of C-Reactive Protein in Clinical Samples by Aptamer Hairpin Probes and Coprecipitation of Silver Ions and Gold Nanoparticles

C-reactive protein (CRP) levels can vary widely related to diverse disease contexts. However, expensive antibodies have impeded the clinical utility of antibody-based full-range CRP assays, especially in developing countries. Herein, we established a low-cost, antibody-free, 96-well plate-based full-range CRP detection method by combining gold nanoparticles (AuNPs), silver iodide (AgI), Eosin Y, and the aptamer hairpin probe (AHP) with Ag+-mediated cytosine-cytosine mismatches, that is, the Au@AgI/Eosin Y-AHP method. After binding the target CRP, the AHP released Ag+, which subsequently induced the aggregation of AuNPs on the surface of AgI colloids, resulting in a significant increase in the adsorption of Eosin Y on the surface of AuNPs. The changes in fluorescence intensity (FI) of Eosin Y in the supernate without and with CRP were proportional to the concentration of the CRP in the wide range of 0.01-40 ng/mL (r = 0.9969), and 96 samples can be detected in 96-well plates simultaneously by a microplate reader within 45 min. Remarkably, the CRP levels of 100 clinical samples achieved with the Au@AgI/Eosin Y-AHP had a good correlation with those obtained with the latex-enhanced immune turbidimetry assay (r = 0.986). Furthermore, the kit based on the Au@AgI/Eosin Y-AHP method costs only $8.1 for 100 tests. Therefore, the new method is beneficial for less developed areas where expensive assays are not affordable.

Serum C-reactive Protein and Protein Electrophoretic Pattern Correlated With Age in Horses

Inflammaging or chronic, low-grade inflammation is a phenomenon characterizing age-related pathologies and natural processes in aging tissues. This study aimed to investigate the effect of age on the serum levels of C-reactive protein and protein electrophoretic pattern in horses. Thirty Italian Saddle horses from the same horse training center, were enrolled and divided in three equal groups according to their age: Group A (2-4 years), Group B (7-10 years), Group C (15-20 years). Blood samples were collected from each horse to evaluate hematological parameters and the serum concentration of C-reactive protein (CRP), total proteins, albumin, α1-, α-2, β1-, β2- and γ-globulins. One-way analysis of variance showed an age-related difference in the concentration of CRP, α1- and α2-globulins (P < 0.001) which increased with aging. Albumin and albumin:globulin ratio showed lower values in Groups B and C than Group A (P < 0.001). Age of horses showed a negative correlation with the values of albumin, and a positive correlation with CRP, α1- and α2-globulins concentration. The results of the current study suggest an increased acute phase response in adult and old horses compared to young ones. As α-globulin fractions include many other acute phase proteins (APPs) in addition to CRP, further studies to assess what other APPs could be involved in chronic inflammation or "inflammaging" are recommended in horse in order to improve knowledge on the key inflammatory biomarkers during aging in this species.

A cost-effective smartphone-based device for rapid C-reaction protein (CRP) detection using magnetoelastic immunosensor

C-Reaction protein (CRP) is a marker of nonspecific immunity for vital signs and wound assessment, and it can be used to diagnose infections in clinical medicine. However, measuring CRP level currently requires hospital-based instruments, high-cost reagents, and a complex process, all of which have limited its full capabilities for self-detection, a growing trend in modern medicine. In this study, we developed a novel smartphone-based device using advanced methods of magnetoelastic immunosensing to mitigate these limitations. We combined a system-on-chip (SoC) hardware architecture with smartphone apps to realize the sampling of resonance frequency shift on magnetoelastic chips, which can determine the ultra-sensitivity to mass change caused by the binding of anti-CRP antibody and CRP. Through detecting a multi-group of samples, we found that the resonance frequency shift was linearly proportional to the CRP concentration in the range from 0.1 to 100 μg mL^-1, with a sensitivity of 12.90 Hz μg^-1 mL^-1 and a detection limit of 2.349 × 10^-4 μg mL^-1. Meanwhile, compared with the large-scale instrument used in clinical settings, the performance of our device was stable and significantly more portable, rapid and cost-effective, offering excellent potential for modern home-based diagnosis.

Diagnoses Based on C-Reactive Protein Point-of-Care Tests

C-reactive protein (CRP) is an important part of the immune system's reaction to various pathological impulses such as bacterial infections, systemic inflammation, and internal organ failures. An increased CRP level serves to diagnose the mentioned pathological states. Both standard laboratory methods and simple point-of-care devices such as lateral flow tests and immunoturbidimetric assays serve for the instrumental diagnoses based on CRP. The current method for CRP has many flaws and limitations in its use. Biosensor and bioassay analytical devices are presently researched by many teams to provide more sensitive and better-suited tools for point-of-care tests of CRP in biological samples when compared to the standard methods. This review article is focused on mapping the diagnostical relevance of CRP, the applicability of the current analytical methods, and the recent innovations in the measurement of CRP level.

Role of C-Reactive Protein in Diabetic Inflammation

Even though type 2 diabetes mellitus (T2DM) represents a worldwide chronic health issue that affects about 462 million people, specific underlying determinants of insulin resistance (IR) and impaired insulin secretion are still unknown. There is growing evidence that chronic subclinical inflammation is a triggering factor in the origin of T2DM. Increased C-reactive protein (CRP) levels have been linked to excess body weight since adipocytes produce tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), which are pivotal factors for CRP stimulation. Furthermore, it is known that hepatocytes produce relatively low rates of CRP in physiological conditions compared to T2DM patients, in which elevated levels of inflammatory markers are reported, including CRP. CRP also participates in endothelial dysfunction, the production of vasodilators, and vascular remodeling, and increased CRP level is closely associated with vascular system pathology and metabolic syndrome. In addition, insulin-based therapies may alter CRP levels in T2DM. Therefore, determining and clarifying the underlying CRP mechanism of T2DM is imperative for novel preventive and diagnostic procedures. Overall, CRP is one of the possible targets for T2DM progression and understanding the connection between insulin and inflammation may be helpful in clinical treatment and prevention approaches.

The role of C-reactive protein as a prognostic marker in COVID-19

Background

C-reactive protein (CRP) is a non-specific acute phase reactant elevated in infection or inflammation. Higher levels indicate more severe infection and have been used as an indicator of COVID-19 disease severity. However, the evidence for CRP as a prognostic marker is yet to be determined. The aim of this study is to examine the CRP response in patients hospitalized with COVID-19 and to determine the utility of CRP on admission for predicting inpatient mortality.

Methods

Data were collected between 27 February and 10 June 2020, incorporating two cohorts: the COPE (COVID-19 in Older People) study of 1564 adult patients with a diagnosis of COVID-19 admitted to 11 hospital sites (test cohort) and a later validation cohort of 271 patients. Admission CRP was investigated, and finite mixture models were fit to assess the likely underlying distribution. Further, different prognostic thresholds of CRP were analysed in a time-to-mortality Cox regression to determine a cut-off. Bootstrapping was used to compare model performance [Harrell’s C statistic and Akaike information criterion (AIC)].

Results

The test and validation cohort distribution of CRP was not affected by age, and mixture models indicated a bimodal distribution. A threshold cut-off of CRP ≥40 mg/L performed well to predict mortality (and performed similarly to treating CRP as a linear variable).

Conclusions

The distributional characteristics of CRP indicated an optimal cut-off of ≥40 mg/L was associated with mortality. This threshold may assist clinicians in using CRP as an early trigger for enhanced observation, treatment decisions and advanced care planning.

Plasmonic Optical Biosensors for Detecting C-Reactive Protein: A Review

C-reactive protein (CRP), a potent acute-phase reactant that increases rapidly in response to inflammation, tissue damage or infections, is also considered an indicator of the risk of cardiovascular diseases and neurological disorders. Recent advances in nanofabrication and nanophotonic technologies have prompted the optical plasmonic phenomena to be tailored for specific detection of human serum CRP into label-free devices. We review the CRP-specific detection platforms with high sensitivity, which feature the thin metal films for surface plasmon resonance, nano-enhancers of zero dimensional nanostructures, and metal nanoparticles for localized surface plasmon resonance. The protocols used for various types of assay reported in literature are also outlines with surface chemical pretreatment required for specific detection of CRPs on a plasmonic surface. Properties including sensitivity and detection range are described for each sensor device reviewed, while challenges faced by plasmonic CRP sensors are discussed in the conclusion, with future directions towards which research efforts need to be made.

N- and B-Codoped Graphene: A Strong Candidate To Replace Natural Peroxidase in Sensitive and Selective Bioassays

The work describes a carbon-based peroxidase mimic, N- and B-codoped reduced graphene oxide (NB-rGO), which shows high peroxidase-like activity without oxidase-like activity and has a catalytic efficiency nearly 1000-fold higher than that of undoped rGO. The high catalytic activity of NB-rGO is explained by density functional theory by calculating Gibbs free energy change during the peroxide decomposition reaction. Acetylcholine and C-reactive protein are successfully quantified with high sensitivity and selectivity, which were comparable to or better than those obtained using natural peroxidase. Furthermore, NB-rGO, which does not have oxidase-like activity, is proven to have higher sensitivity toward acetylcholine than Pt nanoparticles having oxidase-like activity. This work will facilitate studies on development, theoretical analysis for rational design, and bioassay applications of enzyme mimics based on nanomaterials.

A Novel Thermal Bubble Valve Integrated Nanofluidic Preconcentrator for Highly Sensitive Biomarker Detection

In this study, we developed a new immunosensor that can achieve an ultralow detection limit and high sensitivity. This new device has an electrokinetic trapping (EKT)-based nanofluidic preconcentrator, which was integrated with oscillating bubble valves, to trap concentrated antigen and immunobeads. During the immunoassay process, oscillating bubbles rapidly grew and acted as control valves and to block the microchannel. Thereafter, the trapped preconcentrated antigen plug and antibody-coated nanobeads were preserved in the region between these two valves. Finally, the antigen concentration was quantitatively analyzed by a real-time measurement of Brownian diffusion of the immunobeads. In this work, the test sample used was C-reactive protein (CRP) which is a risk indicator of coronary heart disease and atherosclerosis.

An optical pickup enzyme-linked immunosorbent assay (ELISA) with a microfluidic disk

We evaluated optical pickup ELISA with an original microfluidic disk that contains eight radially arranged channels, which enable semi-automatic sample loading and washing. This disk-shaped chip composed of acrylic plates was fabricated by CO₂ laser machining and capture antibodies were immobilized in the channels. After the immunoreaction with antigens and enzyme-linked secondary antibodies, an enzyme-catalyzed nanoaggregation of o-phenylenediamine was detected by measuring the reflectivity change of a laser beam focused in the channel. The assay of C-reactive protein (CRP) was successfully performed in a short amount of time (approximately 20 min from CRP loading). The limit of detection was determined to be 2 ng mL⁻¹, which is more sensitive as compared with conventional ELISA using microplates.

Optical pickup ELISA with an original microfluidic disk, which enable semi-automatic sample loading and washing, was developed. The rapid and sensitive assay of C-reactive protein (CRP) was successfully performed.

Glucose homeostasis influences the risk of incident knee osteoarthritis: Data from the osteoarthritis initiative

We aimed to determine if serum measures of impaired glucose homeostasis (glucose concentrations or glycated serum protein, GSP) or systemic inflammation (high-sensitivity C-reactive protein, CRP) are related to incident typical knee osteoarthritis (KOA) or incident accelerated KOA. We conducted a case-control study using the Osteoarthritis Initiative's baseline and first four annual visits. All participants had no radiographic KOA at baseline (Kellgren-Lawrence [KL] < 2). We classified three groups: (i) incident accelerated KOA: >1 knee developed advance-stage KOA (KL Grade 3 or 4) within 48 months; (ii) incident typical KOA: > 1 knee increased in radiographic scoring within 48 months (excluding those with accelerated KOA); and (iii) No KOA: no change in KL grade by 48 months. We matched on sex. A laboratory blinded to group assignment used baseline serum samples to conduct assays for CRP, GSP, and glucose. Due to nonlinear relationships, we used three piece-wise multinomial logistic regression models to determine if baseline CRP, GSP, or glucose were associated with incident typical KOA or accelerated KOA compared with no KOA. We adjusted for age, body mass index, and sex. We analyzed 54 adults/group. Lower and higher GSP concentrations were associated with incident typical KOA compared with adults with concentrations (log) closer to 5.7 (lnGSp < 5.7: OR = 0.28, 95%CI = 0.08-0.93; lnGSp > 5.7: OR = 3.21, 95%CI = 1.07-9.62). Glucose, GSP, and CRP were not significantly associated with incident accelerated KOA. Glucose homeostasis may predict individuals at risk of incident typical KOA but not accelerated KOA, which may indicate accelerated KOA is a distinct disorder from typical KOA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2282-2287, 2017.

An automated and portable microfluidic chemiluminescence immunoassay for quantitative detection of biomarkers

Microfluidic platforms capable of automated, rapid, sensitive, and quantitative detection of biomarkers from patient samples could make a major impact on clinical or point-of-care (POC) diagnosis. In this work, we realize an automated diagnostic platform composed of two main components: (1) a disposable, self-contained, and integrated microfluidic chip and (2) a portable instrument that carries out completely automated operations. To demonstrate its potential for real-world application, we use injection molding for mass fabrication of the main components of disposable microfluidic chips. The assembled three-layered chip with on-chip mechanical valves for fluid control consists of (1) a top silicone fluidic layer with embedded zigzag microchannels, reagent reservoirs and a negative pressure port, (2) a middle tinfoil layer with patterned antibody/antigen stripes, and (3) a bottom silicone substrate layer with waste reservoirs. The versatility of the microfluidics-based system is demonstrated by implementation of a chemiluminescence immunoassay for quantitative detection of C-reactive protein (CRP) and testosterone in real clinical samples. This lab-on-a-chip platform with features of quantitation, portability and automation provides a promising strategy for POC diagnosis.

Influence of MTHFR C677T gene polymorphism in the development of cardiovascular disease in Egyptian patients with rheumatoid arthritis

OBJECTIVE

To investigate the association between increased carotid intima-media thickness (CIMT), homocysteine level, and MTHFR C677T (rs1801133) gene polymorphism in Egyptian people with rheumatoid arthritis (RA).

SUBJECTS AND METHODS

280 Egyptian women (160 RA patients and 120 controls) were included in the study. CIMT was measured using high resolution B-mode ultrasonography and homocysteine levels were measured using enzyme-linked immunosorbent assay. While, MTHFR C677T polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

We found that subjects who carried the TT genotype and T allele were significantly more likely to develop RA with 2.9 and 1.5 fold, respectively. RA patients carrying the T allele presented a statistically significant increased risk of developing atherosclerosis compared with those carrying the C allele. Moreover, MTHFR TT genotype was independent risk factor of thick CIMT.

CONCLUSIONS

C677T MTHFR gene polymorphism is associated with RA in Egyptians. MTHFR 677TT carriers had higher concentrations of serum Hcy than did subjects harboring the CC and CT genotypes. The presence of 677T allele increases the risk of atherosclerosis in patients with RA. This increased risk of atherosclerosis could be due to hyperhomocysteinemia.

Elevated Values of C-Reactive Protein Induced by Imported Infectious Diseases: A Controlled Cross-Sectional Study of 11,079 Diseased German Travelers Returning from the Tropics and Subtropics

The present controlled cross-sectional study aimed to assess elevated values of C-reactive protein (CRP), a positive acute-phase protein, induced by imported infectious diseases (IDs) seen in patients consulting the University of Munich (1999-2015) after being in the tropics/subtropics. The analysis investigated data sets from 11,079 diseased German travelers (cases) returning from Latin America (1,986), Africa (3,387), and Asia (5,706), and from 714 healthy Germans who had not recently traveled (controls). The proportions of elevated values of CRP (> 0.5 mg/dL) were significantly larger among cases (44.3%) than among controls (20.7%). Among cases, this proportion was largest among males (49.2%) in comparison to females (39.9%), among travelers with short travel duration of 1-14 days (49.6%) in comparison to travelers with a travel duration of > 180 days (30.8%), and with travel destination in Africa (47.0%) in comparison to Asia (44.2%) and Latin America (39.9%), among all-inclusive travelers (47.4%) in comparison to business travelers (46.7%) and backpackers (44.1%), and among patients presenting with fever (70.9%) and arthralgia (54.3%). The study identified various imported IDs with significantly larger proportions of elevated values of CRP including viral (cytomegalovirus infection [94.7%], influenza [88.9%], infectious mononucleosis [71.8%]), bacterial (typhoid fever [100%], paratyphoid fever [92.9%], shigellosis [76.8%], rickettsiosis [74.2%], Salmonella enteritis [71.3%], Campylobacter infection [68.7%]), and protozoan (vivax malaria [100%], ovale malaria [100%], falciparum malaria [95.4%], noninvasive Entamoeba infection [65.9%]) IDs. This study demonstrates that elevated values of CRP can be a useful laboratory finding for travelers returning from the tropics/subtropics, as these findings are typically caused mainly by certain imported bacterial IDs, but also by viral and protozoan IDs.

Interactive effects of C-reactive protein levels on the association between APOE variants and triglyceride levels in a Taiwanese population

Background

Apolipoprotein E (APOE) plays a major role in lipid metabolism and inflammation. However, the association between APOE gene polymorphisms and serum triglyceride levels remains controversial. We tested the effects of APOE variants on triglyceride levels and their interactions with the inflammatory marker C-reactive protein (CRP) in a Taiwanese population.

Methods

Two APOE single nucleotide polymorphisms (SNPs) rs429358 and rs7412 were genotyped by TaqMan Assay using real time PCR in 595 healthy subjects attending the clinic for routine visits.

Results

After adjustment for clinical covariates, subjects carrying the rs429358-TT genotype and non-ε4 alleles were found to have higher CRP levels, whereas those with rs7412-CC genotype and non-ε2 alleles had significantly higher total and low-density lipoprotein cholesterol levels (all P < 0.01). Using subgroup and interaction analyses, we observed significantly lower triglyceride levels in subjects carrying the rs429358-TT genotype and non-ε4 alleles in the low CRP group (P = 2.71× 10⁻⁴ and P = 4.32 × 10⁻⁴, respectively), but not in those in the high CRP group (interaction P = 0.013 and 0.045, respectively). In addition, multivariate stepwise linear regression analysis showed that subjects carrying the rs429358-TT genotype and non-ε4 alleles with low CRP levels had significantly lower triglyceride levels (P < 0.001 and P < 0.001, respectively). In addition, when combined with the risk alleles of GCKR, APOA5 and LPL gene variants, we observed that triglyceride levels increased significantly with the number of risk alleles (P = 2.9 × 10⁻¹²).

Conclusions

The combination of SNPs and ε alleles at the APOE locus is involved in managing lipid and CRP levels in the Taiwanese population. APOE polymorphisms interact with CRP to regulate triglyceride levels, thus triglyceride concentration is influenced by both the genetic background of the APOE locus and the inflammatory status of a subject.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-016-0262-z) contains supplementary material, which is available to authorized users.

A plasmonic chip-based bio/chemical hybrid sensing system for the highly sensitive detection of C-reactive protein

A synthetic polymer ligand-grafted plasmonic chip was fabricated and demonstrated a highly sensitive detection of C-reactive protein (CRP) by grating-coupled surface plasmon field-enhanced fluorescence.

Effects of obesity on the association between common variations in the TBX5 gene and matrix metalloproteinase 9 levels in Taiwanese

Objectives:

The TBX5 gene, a member of the T-box family, is associated with congenital heart disease, electrocardiographic parameters, and development of atrial fibrillation in the general population. This study aimed to elucidate the role of TBX5 gene polymorphisms in metabolic and inflammatory profiles possibly linked to TBX5-related pathologies.

Materials and Methods:

A sample population of 597 individuals having routine health examinations was enrolled. Five tagging TBX5 single nucleotide polymorphisms (SNPs) were analyzed using polymerase chain reaction and restriction enzyme digestion or TaqMan SNP genotyping assays. Associations between genotypes/haplotypes and matrix metalloproteinase 9 (MMP9) levels were investigated using generalized linear model analysis. Interactions between each genotype/haplotype, MMP9 level, and obesity status were tested using two-way analysis of variance with Golden Helix SVS Win32 7.3.1 software.

Results:

After adjusting for clinical covariates, TBX5 genotypes were found to be associated with MMP9 levels (p = 0.002 and p = 0.001 for rs4113925 and rs3825214, respectively) in a dominant inheritance model. Haplotype analysis using three tag SNPs (rs11067101, rs1247973, and rs3825214) revealed a significant association between TBX5 haplotype GCG and MMP9 levels (uncorrected p = 0.0093 and the corrected false discovery rate p = 0.0435). Multivariate analysis identified that SNP rs3825214, in addition to the MMP9 and E-selectin genotypes, was independently associated with MMP9 levels (p < 0.001). Using a dominant inheritance model, subgroup and interaction analysis showed associations between the rs4113925, rs3825214, and MMP9 levels only in nonobese individuals (p = 1.04 × 10⁻⁴ and p = 7.11 × 10⁻⁵, respectively; interaction p = 0.009 and 0.018, respectively). Subgroup analysis showed a borderline significant association between haplotype GCG and MMP9 levels (uncorrected p = 0.020 and corrected false discovery rate p = 0.073), but with no evidence of interaction.

Conclusion:

TBX5 genotypes/haplotypes are independently associated with MMP9 in Taiwanese individuals and occur predominantly in nonobese people. These associations may broaden our understanding of the mechanism underlying T-box family gene activity and related cardiovascular pathologies.

Rapid and quantitative detection of C-reactive protein based on quantum dots and immunofiltration assay

Convenient and rapid immunofiltration assays (IFAs) enable on-site "yes" or "no" determination of disease markers. However, traditional IFAs are commonly qualitative or semi-quantitative and are very limited for the efficient testing of samples in field diagnostics. Here, we overcome these limitations by developing a quantum dots (QDs)-based fluorescent IFA for the quantitative detection of C-reactive proteins (CRP). CRP, the well-known diagnostic marker for acute viral and bacterial infections, was used as a model analyte to demonstrate performance and sensitivity of our developed QDs-based IFA. QDs capped with both polyethylene glycol (PEG) and glutathione were used as fluorescent labels for our IFAs. The presence of the surface PEG layer, which reduced the non-specific protein interactions, in conjunction with the inherent optical properties of QDs, resulted in lower background signal, increased sensitivity, and ability to detect CRP down to 0.79 mg/L with only 5 µL serum sample. In addition, the developed assay is simple, fast and can quantitatively detect CRP with a detection limit up to 200 mg/L. Clinical test results of our QD-based IFA are well correlated with the traditional latex enhance immune-agglutination aggregation. The proposed QD-based fluorescent IFA is very promising, and potentially will be adopted for multiplexed immunoassay and in field point-of-care test.

A Novel Targeted Screening Tool for Hypogammaglobulinemia: Measurement of Serum Immunoglobulin (IgG, IgM, IgA) Levels from Dried Blood Spots (Ig-DBS Assay)

PURPOSE

To develop an assay to quantify serum immunoglobulin (IgG, IgM, IgA) levels using dried blood spots (DBS) obtained on collection cards to be used as a tool for targeted screening for hypogammaglobulinemia.

METHODS

DBS samples, along with simultaneous serum samples, were collected from 107 healthy individuals (11 months to 57 years of age). After eluting proteins from DBS, IgG, IgM, and IgA were quantified by an enzyme-linked immunosorbent assay (ELISA). The Ig-DBS assay was validated through calibration curve performance, intra- and inter-assay precision, accuracy, specificity, selectivity, and linearity. The ELISA measurements were compared with serum Ig levels obtained using a standard nephelometry assay on serum samples collected simultaneously with the DBS samples and the results of the two assays were correlated. The stability of IgG, IgM, and IgA in the DBS was tested at room temperature, 36° to 38 °C, 2 to 8 °C, and -25 to -40 °C, from 4 to 14 days.

RESULTS

The Ig-DBS assay demonstrated precision, accuracy, specificity, selectivity, and linearity. Using the identified correlation coefficients of 0.834 for IgG, 0.789 for IgM, and 0.918 for IgA, the standard nephelometry-based normal reference ranges for all 3 serum Ig isotypes could be used with the Ig-DBS assay in individuals ≥16 years of age. The DBS samples were stable for 14 days at room temperature in a closed polyethylene bag.

CONCLUSIONS

The Ig-DBS assay is both sensitive and accurate for quantification of serum immunoglobulins. Samples are sufficiently stable at ambient temperature to allow for convenient shipping and analysis at a centralized laboratory. This assay therefore presents a new option for screening patients ≥16 years of age for hypogammaglobulinemia in any setting.

AlGaN/GaN High Electron Mobility Transistor-Based Biosensor for the Detection of C-Reactive Protein

In this paper, we propose an AlGaN/GaN high electron mobility transistor (HEMT)-based biosensor for the detection of C-reactive protein (CRP) using a null-balancing circuit. A null-balancing circuit was used to measure the output voltage of the sensor directly. The output voltage of the proposed biosensor was varied by antigen-antibody interactions on the gate surface due to CRP charges. The AlGaN/GaN HFET-based biosensor with null-balancing circuit applied shows that CRP can be detected in a wide range of concentrations, varying from 10 ng/mL to 1000 ng/mL. X-ray photoelectron spectroscopy was carried out to verify the immobilization of self-assembled monolayer with Au on the gated region.

Analysis of Inflammatory and Anemia-Related Biomarkers in a Randomized, Double-Blind, Placebo-Controlled Study of Siltuximab (Anti-IL6 Monoclonal Antibody) in Patients With Multicentric Castleman Disease

PURPOSE

Siltuximab (IL6 antibody) is approved for the treatment of multicentric Castleman disease (MCD). Effects of IL6 inhibition on the inflammatory milieu accompanying MCD have not been characterized.

EXPERIMENTAL DESIGN

Trends in inflammatory- and anemia-associated markers, measured over the course of a placebo-controlled study of siltuximab (11 mg/kg q3w) in patients with MCD (n = 79), were characterized.

RESULTS

Baseline IL6 and C-reactive protein (CRP) levels were significantly correlated (r = 0.708; P < 0.0001). CRP levels decreased (median, 92%) by cycle 1 day 8 (C1D8), remaining suppressed during siltuximab treatment while remaining stable in the placebo group. There were no associations between baseline CRP or IL6 and MCD symptom burden, histologic subtype, ethnicity, maximum CRP decrease, and response parameters. A hemoglobin response (change ≥ 15 g/L at week 13) was observed with siltuximab (61%; P = 0.0002). Median hepcidin decrease from baseline at C1D8 with siltuximab was 47% versus median 11% increase with placebo. Maximum post-baseline changes in hepcidin levels among siltuximab recipients were correlated with maximum changes for hemoglobin (r = -0.395; P = 0.00607), total iron-binding capacity (TIBC; r = -0.354; P = 0.01694), and ferritin (r = 0.599; P = 0.0001). Greater median changes from baseline in ferritin, hemoglobin, and TIBC were observed in anemic siltuximab-treated patients.

CONCLUSIONS

IL6 neutralization with siltuximab resulted in sustained CRP suppression and improvement of anemia, in part, by hepcidin pathway inhibition.

Circulating YKL-40 level, but not CHI3L1 gene variants, is associated with atherosclerosis-related quantitative traits and the risk of peripheral artery disease

YKL-40, a pleotropic cytokine, is emerging as a risk factor and a prognostic predictor of atherosclerotic cardiovascular disease. We attempted to elucidate the genetic, clinical and biochemical correlates of circulating YKL-40 level and, by combining it with CHI3L1 gene variants, with the risk and long-term mortality of peripheral artery disease (PAD). Plasma YKL-40 concentrations were measured in 612 Taiwanese individuals who had no clinically overt systemic disease. Clinical parameters, CHI3L1 gene promoter variants and 18 biomarker levels were analyzed. Eighty-six PAD patients were further enrolled for analysis. Significant associations were found between CHI3L1 genotypes/haplotypes and YKL-40 levels for the health examination subjects (smallest p = 8.36 × 10-7 for rs4950928 and smallest p = 1.72 × 10-10 for haplotype TGG) and also for PAD patients. For the health examination subjects, circulating YKL-40 level, but not CHI3L1 gene variants, were positively associated with age, smoking, and circulating levels of triglyceride, lipocalin 2 and multiple inflammatory biomarkers and negatively associated with low-density-lipoprotein cholesterol levels. Circulating YKL-40 level is also significantly associated with the risk of PAD (p = 3.3 × 10-23). Circulating YKL40 level, but not CHI3L1 gene promoter variants, is associated with the risk of PAD in Taiwanese. The association of YKL-40 levels with multiple quantitative traits relating to the risk of PAD may provide a molecular basis linking YKL-40 to atherosclerotic cardiovascular disease.

The interleukins IL-6 and IL-1Ra: a mediating role in the associations between BMI and birth weight?

The biological mechanisms in the association between maternal body mass index (BMI) and birth weight are not well understood, but are likely to involve maternal plasma glucose levels and nutrient transport across the placenta, both important modulators of fetal growth. Adipose tissue contributes to circulating levels of interleukins that may affect glucose metabolism and possibly also placental transport of nutrients. We investigated possible mediating roles of Interleukin 6 (IL-6) and Interleukin 1 Receptor antagonist (IL-1Ra) in 208 pregnant women. Known and hypothesized dependencies between BMI in early pregnancy and fasting glucose, IL-1Ra and IL-6 at gestational weeks 30-32, and birth weight were specified in a path diagram. Standardized regression coefficients, expressing direct, indirect and total effects, were estimated by Bayesian path analysis. Mean (s.d.) BMI was 24.9 kg/m2 (4.2) and mean (s.d.) birth weight 3748 g (454). The total effect of BMI on birth weight was 0.24 (95% credibility interval (CrI) [0.12, 0.36]). The direct effect of IL-1Ra on birth weight was not statistically significant, but significant effects of BMI on IL-1Ra (0.61, 95% CrI [0.51, 0.72]), of IL-1Ra on fasting glucose (0.17, 95% CrI [0.01, 0.34]) and of fasting glucose on birth weight (0.14, 95% CrI [0.01, 0.27]) implied an indirect pathway from BMI via IL-1Ra on birth weight. Approximately 20% of the effect of BMI on birth weight was mediated through IL-1Ra. For IL-6, no such effects were found. Our results indicate that IL-1Ra may be a mediator in the association between BMI and birth weight.

Association and prognostic value of serum inflammation markers in patients with leukoplakia and oral cavity cancer

BACKGROUND

Oral cavity cancer ranks as the fourth leading cancer in men in Taiwan. The development of a serum biomarker panel for early detection and disease monitoring is, therefore, warranted.

METHODS

Nine inflammation-associated markers were investigated in 46 patients with leukoplakia, 151 patients with untreated oral cavity squamous cell carcinoma (OSCC), and 111 age- and gender-matched healthy controls using enzyme-linked immunosorbent assay. During a subsequent 28-month surveillance of OSCC patients, serum samples were prospectively collected at predetermined intervals following the completion of therapy.

RESULTS

Logistic regression analysis showed matrix metalloproteases (MMP)-2, MMP-9, C-reactive protein (CRP), transforming growth factor-β1 (TGF-β1), and E-selectin having the best discrimination power between groups and significant elevation trends of those five markers were noted from control to OSCC. By combining those five markers, a 0.888 and 0.938 area under curve by ROC curve analysis with 67.4% and 80% overall sensitivity and fixed 90% specificity for leukoplakia and OSCC groups were demonstrated. In the follow-up period, 25 OSCC patients developed recurring or secondary tumors. All examined markers had decreased in relapse-free patients following treatment. However, in patients with relapse, interleukin-6, CRP, and serum amyloid A remained at elevated levels. Statistical analysis showed that patients with CRP ≧2 mg/L and E-selectin ≧85 ng/mL at baseline had highest probability of relapse (odds ratio=3.029, p<0.05).

CONCLUSIONS

The results indicate that inflammation plays a crucial role in the pathogenesis process of OSCC. By examining the inflammation markers, physicians could potentially identify patients at risk of cancer transformation or relapse.

Human C-reactive protein gene polymorphism and metabolic syndrome are associated with premature coronary artery disease

The aim of this study was to investigate the association between C-reactive protein (CRP) gene polymorphism and metabolic syndrome (MetS) with premature coronary artery disease (PCAD). 116 patients with PCAD (58 with MetS and 58 without MetS) and 119 controls were included in the study. CRP gene +1059 G>C polymorphism was analyzed by polymerase chain reaction. Serum hs-CRP was measured using high-sensitivity enzyme-linked immunosorbent assay. Carriers of C allele of the CRP +1059 G>C polymorphism had 3.37 fold increased risk to develop MetS in patients with PCAD. In addition CRP gene and hs-CRP levels were independent risk factors for PCAD and MetS. The present study provides new evidence that the presence of CRP +1059 G>C polymorphism and hs-CRP levels are independent determinants of PCAD and MetS in Egyptians. The results of our study suggest a synergistic effect of CRP C allele with classical risk factors such as hypertension, obesity, dyslipidemia and MetS.

Genetic variants associated with circulating MMP1 levels near matrix metalloproteinase genes on chromosome 11q21-22 in Taiwanese: interaction with obesity

BACKGROUND

MMP1 is implicated in the pathogenesis of atherothrombotic cardiovascular disease. We aimed to elucidate genetic determinants of inflammatory marker levels, including circulating MMP1, in Taiwanese, and their association with obesity.

METHODS

Five genetic polymorphisms around matrix metalloproteinase genes on chromosome 11q21-22 region were genotyped in 519 subjects.

RESULTS

After adjusting for clinical covariates, two polymorphisms were significantly associated with MMP1 levels, rs1799750 and rs495366, using an additive inheritance model (P = 1.5x10-4 and P = 2.57x10-5, respectively). Using dominant model, minor alleles of rs1799750 and rs495366 were associated with higher MMP1 levels (P = 1.3x10-4 and P = 1.95x10-5, respectively). In haplotype analysis, two haplotypes inferred from five SNPs (A2GATA and A1GATG) were associated with MMP1 levels (P = 5x10-4 and P = 8.47x10-5, respectively). Subgroup and interaction analysis revealed an association of rs1799750 and rs495366 with MMP1 levels only in non-obese subjects (P = 6.66x10-6 and P = 4.38x10-5, respectively, and interaction P = 0.008 for rs1799750). Haplotype interaction analysis also showed significant interaction for haplotype A1GATG (interaction P = 0.003).

CONCLUSIONS

Genotypes/haplotypes around MMP1 locus are associated with MMP1 levels in Taiwanese. Further, since genotypes/haplotypes near MMP1 locus interact with obesity to set MMP1 levels, genetic determinants for MMP1 level may be different between obese and non-obese individuals.

Adiposity-related inflammation: effects of pregnancy

In the nonpregnant population, there is extensive evidence of a systemic low-grade inflammatory status in relation to excess adipose tissue. Less is known about the relation during pregnancy.

OBJECTIVE

Our main objective was therefore to explore the effect of pregnancy on adiposity-related systemic inflammation.

DESIGN AND METHODS

This study is a longitudinal cohort study of 240 pregnant women of Scandinavian heritage at Oslo University hospital-Rikshospitalet, Norway from 2002 to 2005. The inflammatory markers (C-reactive protein [CRP], Interleukin-6 [IL-6], monocyte chemoattractant protein 1 [MCP-1], IL1-Ra, tumor necrosis factor receptor II, and IL-10) were measured at four timepoints during pregnancy and analyzed by enzyme immuno-assay. The women were categorized based on BMI at inclusion (BMI <25, 25-30, and >30 kg/m(2)). Data were analyzed by Friedman-test, Wilcoxon signed rank test, or Kruskal-Wallis test as appropriate.

RESULTS

Maternal adiposity was associated with significantly higher circulatory levels of several inflammatory markers (CRP, MCP-1, IL-6, and IL-1Ra). However, this proinflammatory upregulation was not evident toward the end of pregnancy, as levels of CRP, MCP-1, and IL-6 were not any longer significantly different between the BMI categories.

CONCLUSIONS

Although normal pregnancy exhibits proinflammatory features, this does not seem to have additive or synergistic effects on the inflammation associated with adiposity. On the contrary, we found that the BMI-dependent increase in proinflammatory markers was not evident at the end of pregnancy.

Association of SELE genotypes/haplotypes with sE-selectin levels in Taiwanese individuals: interactive effect of MMP9 level

Background

E-selectin is implicated in various inflammatory processes and related disorders. We aimed to investigate the role of SELE-gene genotypes/haplotypes on plasma levels of MMP9 and sE-selectin in Taiwanese individuals.

Methods

Five hundred twenty individuals were enrolled. Seven tagging SELE single nucleotide polymorphisms were analyzed.

Results

SELE genotypes were found associated with MMP9 and sE-selectin levels. Multivariate analysis identified that the most significant genetic polymorphism (rs5368 genotype) was independently associated with MMP9 levels (P < 0.001). One haplotype (GGAGAGT) was marginally associated with MMP9 levels (P = 0.0490). One SELE SNP, (rs3917406, P = 0.031) was associated with sE-selectin levels after adjusting for MMP9 and sICAM1 levels. Subgroup and interaction analysis revealed association of SELE SNP rs10800469 with sE-selectin levels only in the highest quartile of MMP9 level (P = 0.002, interaction P = 0.023). Haplotype analysis showed one haplotype (AAAAAGC) borderline associated with sE-selectin level (P = 0.0511).

Conclusion

SELE genotypes/haplotypes are independently associated with MMP9 and E-selectin levels in Taiwanese individuals. The associations of SELE genotypes/haplotypes with sE-selectin levels are affected by MMP9 levels.

CRP detection from serum for chip-based point-of-care testing system

Most of point-of-care testing (POCT) to improve facilitates in diagnosis, treatment, and monitoring of patients. POCT technique has still remained a quantitatively and accurately detective effect. In this article, we demonstrated that real human C-reactive protein (CRP) in serum was detected for a chip-based point-of-care testing application based on a nanogap-embedded field effect transistor (FET), and the results were compared with those obtained via the enzyme-linked immunosorbent assay (ELISA) method. The limit of detection (LOD), determined from the standard curve, was 0.1 ng/ml, which is comparable to that of commercialized ELISAs. We evaluated that an improved detection range (0.1 ng/ml to 100 ng/ml) was achieved by comparing with commercialized ELISA. Control experiments to determine selectivity and to discern false-positive/false-negative rates were also performed. This report is the first description of the detection of CRP in human serum using a silicon-based biosensor.

Introduction to haemostasis from a pharmacodynamic perspective

Biochemical characterization of the haemostatic system has advanced significantly in the past decades. Sub-systems, such as coagulation, fibrinolysis, blood cells and platelets and the vessel wall have been studied by specialists, mostly separately and independently. The time has come to integrate the approaches, and, in particular, to develop tests to document the state of the whole system and to have available adequate pharmacodynamic tests to evaluate treatments. Many examples are available to show that traditional general methods of clotting and lysis do not provide the information that is desired. The present tendency is to use specific methods for specific factors or effects which are very limited in pharmacological information. There is also increasing awareness of the occurrence of rather broad interindividual variability in the haemostatic system. This suggests that individually tailored treatments are required. This is the more relevant since haemostasis is a balance and treatment should be positioned between efficacy and safety. The conclusion is reached that there is a need for integrated or global methods or sets of methods that reflect the complexity and individual status appropriately and allow the practitioner to judge the effects of interventions and their individual aspects.

Serum levels of osteoprotegerin and receptor activator of nuclear factor -κB ligand in children with early juvenile idiopathic arthritis: a 2-year prospective controlled study

BACKGROUND

The clinical relevance of observations of serum levels of osteoprotegerin (OPG) and receptor activator of nuclear factor -κB ligand (RANKL) in juvenile idiopathic arthritis (JIA) is not clear. To elucidate the potential role of OPG and RANKL in JIA we determined serum levels of OPG and RANKL in patients with early JIA compared to healthy children, and prospectively explored changes in relation to radiographic score, bone and lean mass, severity of the disease, and treatment.

METHODS

Ninety children with early oligoarticular or polyarticular JIA (ages 6-18 years; mean disease duration 19.4 months) and 90 healthy children individually matched for age, sex, race, and county of residence, were examined at baseline and 2-year follow-up. OPG and RANKL were quantified by enzyme-immunoassay. Data were analyzed with the use of t-tests, ANOVA, and multiple regression analyses.

RESULTS

Serum OPG was significantly lower in patients than controls at baseline, and there was a trend towards higher RANKL and a lower OPG/RANKL ratio. Patients with polyarthritis had significantly higher increments in RANKL from baseline to follow-up, compared to patients with oligoarthritis. RANKL was a significant negative predictor for increments in total body lean mass. Patients who were receiving corticosteroids (CS) or disease-modifying antirheumatic drugs (DMARDs) at follow-up had higher OPG/RANKL ratio compared with patients who did not receive this medication.

CONCLUSIONS

The data supports that levels of OPG are lower in patients with JIA compared to healthy children, and higher levels of RANKL is associated with more serious disease. RANKL was a significant negative predictor of lean mass in patients with JIA. The OPG/RANKL ratio was higher in patients on DMARDs or CS treatment.

Serum, plasma, and dried blood spot high-sensitivity C-reactive protein enzyme immunoassay for population research

C-reactive protein (CRP) is used as a biomarker of morbidity and mortality risk in studies of population health, and is essential to interpretation of several micronutrient biomarkers. There is thus a need for a robust high-sensitivity CRP (hsCRP) measurement method for large-scale, non-clinical studies. We developed an efficient, inexpensive assay suitable for quantifying CRP across the physiological range using any blood specimen type. The ELISA uses readily available monoclonal antibodies to measure CRP in serum, plasma, or dried blood spots (DBS) made from venous or capillary blood. Assay performance was evaluated by standard methods, including comparison with a previously described assay. Effects of specimen type were tested by measuring CRP in 52 matched serum, plasma, and venous and capillary dried blood spot specimens. Long- and short-term CRP stability were evaluated. Assessments of assay limits of detection, linearity, recovery, imprecision, and concordance with an established method (Pearson correlation=0.988, n=20) demonstrated the validity of the new assay. CRP measurements in serum, plasma, and DBS had Pearson correlations from 0.974 to 0.995, n=52, but CRP in serum was on average 1.6 times (SD 0.37) higher than in DBS. CRP was stable in frozen serum for up to 34 months, but DBS CRP declined quickly with exposure to ambient temperatures, and across long-term storage at -20°C. This hsCRP assay is a robust and inexpensive tool designed for use in large-scale population health research. Our results indicate that DBS CRP is less stable than previously reported.

Osteoprotegerin levels in patients with severe mental disorders

BACKGROUND

Severe mental disorders are associated with elevated levels of inflammatory markers. In the present study, we investigated whether osteoprotegerin (OPG), a member of the tumour necrosis factor receptor family involved in calcification and inflammation, is elevated in patients with severe mental disorders.

METHODS

We measured the plasma levels of OPG in patients with severe mental disorders (n = 312; 125 with bipolar disorder and 187 with schizophrenia) and healthy volunteers (n = 239).

RESULTS

The mean plasma levels of OPG were significantly higher in patients than in controls (t531 = 2.6, p = 0.01), with the same pattern in bipolar disorder and schizophrenia. The increase was significant after adjustment for possible confounding variables, including age, sex, ethnic background, alcohol consumption, liver and kidney function, diabetes, cardiovascular disease, autoimmune diseases and levels of cholesterol, glucose and C-reactive protein.

LIMITATIONS

Owing to the cross-sectional design, it is difficult to determine causality.

CONCLUSION

Our results indicate that elevated OPG levels are associated with severe mental disorders and suggest that mechanisms related to calcification and inflammation may play a role in disease development.

Insulin resistance is associated with C-reactive protein independent of abdominal obesity in nondiabetic Taiwanese

Insulin resistance, which plays a fundamental role in the pathogenesis of metabolic syndrome and type 2 diabetes mellitus, is associated with serum levels of inflammatory markers and abdominal obesity. Whether insulin resistance is caused by inflammation or is an epiphenomenon of obesity remains unresolved. We therefore conducted a cross-sectional study to investigate whether the association between insulin resistance and C-reactive protein (CRP) levels is independent of abdominal obesity in a nondiabetic Taiwanese population. The study included 574 Taiwanese participants (300 men and 274 women) who were nondiabetic persons with CRP levels not exceeding 10 mg/L and who did not have a history of cardiovascular disease or were taking medication for dyslipidemia. All participants were of Han-Chinese origin. The degree of insulin resistance was determined using the homeostasis model assessment of insulin resistance (HOMA-IR). The CRP levels were categorized into quartiles from the lowest to the highest concentrations (Q1-Q4). Blood pressure, fasting glucose level, triglycerides level, waist circumference, and HOMA-IR were all found to be significantly higher in Q3 and Q4 than in Q1 and Q2. Stratified analysis by sex and abdominal obesity showed that HOMA-IR was significantly associated with CRP levels in both sexes in either obese or nonobese populations. Multiple linear regression analysis adjusting for age, smoking, components of metabolic syndrome, and waist circumference showed that the association between HOMA-IR and CRP levels remained significant in both men and women (P = .029 for men and P < .001 for women). These findings confirm that insulin resistance is strongly associated with CRP levels independent of abdominal obesity in nondiabetic Taiwanese. Factors other than abdominal obesity, such as polymorphisms in the CRP gene, may influence the association of insulin resistance with CRP levels in different ethnic populations.

Inflammatory markers in patients with coronary artery disease with and without inflammatory rheumatic disease

OBJECTIVES

Patients with inflammatory rheumatic diseases (IRDs) have a higher morbidity and mortality from accelerated atherosclerosis than the general population. We hypothesized that patients with the combination of IRD and coronary artery disease (CAD) would have a certain inflammatory phenotype compared with CAD patients without this comorbidity.

METHODS

Four groups of patients were included: patients with IRD, referred to coronary artery bypass grafting (CABG) (CAD-IRD, n = 67), patients without IRD, referred to CABG (CAD, n = 52), patients with IRD without CAD (IRD, n = 32) and healthy controls (n = 30). Plasma levels of several inflammatory markers were analysed by enzyme immunoassays.

RESULTS

(i) Plasma levels of markers of endothelial cell activation [i.e. vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand factor] and osteoprotegerin (OPG) were significantly increased and plasma levels of CCL21 significantly decreased in CAD-IRD patients as compared with CAD patients without IRD. (ii) Within the CAD-IRD group, acute coronary syndrome was a significant predictor of OPG, suggesting an enhanced inflammatory response during plaque destabilization in CAD-IRD patients. (iii) Plasma levels of VCAM-1, OPG and CCL21, but not lipid parameters, IRD characteristics and several other inflammatory markers (e.g. CRP), were significant predictors of CAD-IRD as opposed to CAD in two logistic regression models.

CONCLUSION

Our findings further support a role for inflammation in the accelerated form of atherosclerosis in IRD patients, and suggest that certain inflammatory pathways, such as the enhanced endothelial cell activation and the RANK ligand/RANK/OPG system, may be of particular importance.

Inflammatory mediators in morbidly obese subjects: associations with glucose abnormalities and changes after oral glucose

OBJECTIVE

To explore inflammatory mediators in morbidly obese (MO) subjects with various categories of glucose tolerance and to study the changes in these mediators after an oral glucose load.

DESIGN

Cross-sectional and experimental study.

METHODS

A total of 144 MO subjects were classified into three categories: normal glucose tolerance (NGT); pre-diabetes; and new onset diabetes mellitus (NODM) were included, as were 27 normal weight normoglycemic controls. Serum osteoprotegerin (OPG), visfatin, leptin, adiponectin, interleukin-1 receptor antagonist (IL-1Ra), and C-reactive protein (CRP) were analyzed during an oral glucose tolerance test (OGTT).

RESULTS

Fasting levels of leptin and IL-1Ra were consistently higher in obese persons (P<0.001 and P<0.05). MO subjects with NGT had higher CRP levels (P<0.001) and lower adiponectin levels (P<0.05) compared to controls. Yet when compared with MO subjects with NODM, those with NGT had lower CRP levels and higher adiponectin levels (both P<0.05). Baseline OPG and visfatin levels did not differ between the groups (P=0.326 and P=0.198). During OGTT, OPG levels decreased (P<0.001) and visfatin levels increased transiently (P=0.018). The response in OPG and visfatin did not differ between the groups (P=0.690 and P=0.170). There were minor changes in adiponectin and leptin levels.

CONCLUSIONS

Morbid obesity and glucose intolerance were associated with lower adiponectin levels and higher CRP levels, thus supporting a relationship between obesity, glucose homeostasis, and inflammation. Oral glucose suppressed OPG levels and transiently enhanced visfatin levels independent of obesity and glucose tolerance status, indicating that glucose may be involved in the acute regulation of these proteins.

Association between C-reactive protein gene haplotypes and C-reactive protein levels in Taiwanese: interaction with obesity

OBJECTIVE

The level of C-reactive protein (CRP), an inflammatory marker that predicts future cardiovascular events, is a heritable trait. Our aim was to test the statistical associations between variations in the CRP gene and serum CRP levels in a Taiwanese population with interaction analysis.

METHODS

A sample population of 617 Taiwanese subjects was enrolled. Five CRP single nucleotide polymorphisms (SNPs) previously reported to be associated with CRP level and with reasonable coverage of the CRP gene region were analyzed using polymerase chain reaction and restriction enzyme digestion or by TaqMan SNP Genotyping Assays.

RESULTS

After adjusting for clinical covariates, minor alleles of 3 of the 5 SNPs were associated with change in CRP level: rs3091244 and rs1205 were associated with increased CRP level (P=0.001 and P<0.001, respectively) and rs1800947 with decreased CRP level (P=0.003). Two haplotypes inferred from 5 SNPs (GCGCG and AAGCG) were associated with increased CRP level (P=0.017 and P<0.0001, respectively). Interaction analysis revealed interaction of obesity with CRP genotypes associated with high CRP level (interaction P=0.034 and 0.020 for SNPs rs2794521 and rs1800947, respectively). An effect of obesity on CRP level was also noted in haplotype interaction analysis with the association occurring predominantly in obese subjects (P=0.034).

CONCLUSION

CRP polymorphisms are independently associated with increased or decreased CRP level in Taiwanese. Further, CRP genotypes/haplotypes interact with obesity to set CRP level. These findings have implications for the prediction of atherosclerotic disease.

Aptamer-antibody on-chip sandwich immunoassay for detection of CRP in spiked serum

This study describes a RNA aptamer-based biochip with high affinity and specificity for C-reactive protein (CRP). CRP, which exists in concentrations of 1-3mg/l in the serum of healthy patients, has been identified as a reliable biomarker for inflammation and as a potential marker for sepsis and tissue necrosis. The CRP-specific aptamer was covalently immobilized with its 5'-end on ARChip Epoxy. The detection of bound CRP was carried out optically using labelled secondary antibody in a sandwich format. Assay conditions were optimized with respect to the CRP binding buffer (buffer system, pH and additives) and Ca(2+) concentration (10 mM). Moreover, two sandwich immunoassay formats were tested, the one using dye-labelled antibodies and the other with biotin-modified antibodies/Dy647-labelled streptavidin. In comparison with an antibody-based chip assay, the aptamer chip is superior in terms of CRP measuring range (10 microg/l to 100mg/l) in human serum whereas antibody-based chips result in superior data reproducibility (CV of 8-15%). In contrast to antibody chips, aptamer microarrays provide the unique potential of detecting CRP in serum samples of low risk patients (1-3mg/l) as well as high risk patients (>500 mg/l), furthermore elevated CRP levels (20-350 mg/l) with acceptable recovery (70-130%) by including only one serum sample dilution step (1:100) for the complete measuring range.

Impact of the complement lectin pathway on cytomegalovirus disease early after kidney transplantation

BACKGROUND

This study retrospectively investigated the association between pre-transplant levels of mannose-binding lectin (MBL) plus the associated serine protease (MASP)-2 and the occurrence of cytomegalovirus (CMV) infection and symptomatic CMV disease during the first 12 weeks after kidney transplantation. Materials and methods. Altogether 159 consecutive single kidney transplant recipients were included. The patients were screened for CMV pp65 antigenaemia every second week. No CMV prophylaxis or pre-emptive treatment was given. MBL and MASP-2 were measured in samples taken at transplantation and 10 weeks later.

RESULTS

CMV infection, defined as at least one positive test, was found in 95 patients (59.8%). MBL and MASP-2 measured at transplantation were similar in patients with and without CMV infection. The incidence of CMV infection was also similar in 36 patients (58.3%) with pre-transplant MBL levels below the reference level (500 microg/L) and in patients with higher MBL levels (60.2%). Symptomatic CMV disease was diagnosed in 35 patients (22%), and MASP-2 levels at transplantation in the lower quartile range (<or=148 microg/L) was significantly associated with CMV disease during the first 12 weeks, P = 0.028. MBL levels decreased significantly from transplantation to 10 weeks later, and median (interquartile range) fell from 2597 (526-4939) microug/L to 1520 (270-3069) microg/L (P < 0.001). In contrast, MASP-2 levels increased significantly from 252 (148-382) microg/L to 380 (302-492) microg/L (P < 0.001).

CONCLUSION

Pre-transplant MBL levels do not influence the incidence of any CMV infection or symptomatic CMV disease during the first 12 weeks after kidney transplantation. However, low MASP-2 levels may play a role in the development of symptomatic CMV disease.

Biochemical markers for cardiovascular risk following treatment in endogenous Cushing's syndrome

OBJECTIVE

Cardiovascular disease has been reported to be more common in patients with endogenous Cushing's syndrome (CS) compared to the normal population. In addition to altered lipid profile, inflammation seems to play an important pathogenic role in atherogenesis, but the role of inflammation in CS-associated cardiovascular disease is still not clear. To further elucidate these issues we measured several markers of inflammation in CS patients at baseline and following operative treatment and potential cure.

SUBJECTS

Twenty-eight CS patients (22 women, 6 men) were included in the study and 21 of these patients (15 women, 6 men) were also followed longitudinally for a mean 33 months (range 5-69 months) after operative treatment. For comparison, blood samples were also collected from 24 healthy controls (21 women, 3 men).

RESULTS

We show a distinct cytokine profile in CS patients before and after operative treatment. Thus, while interleukin (IL)-8 and osteoprotegerin (OPG) were significantly increased in CS patients before operation and fell during follow-up, levels of C-reactive protein (CRP) and soluble intracellular adhesion molecule 1 (sICAM) were significantly decreased at baseline, reaching normal levels after operation. While soluble CD40 ligand was within normal limit at baseline, this marker of platelet-mediated inflammation was markedly elevated during follow-up.

CONCLUSIONS

Our findings suggest a complex interaction between CS and inflammation. In particular, the raised levels of IL-8 and OPG in CS patients, despite glucocorticoid excess, may represent an inflammatory and pro-atherogenic phenotype. However, the clinical relevance of these findings will have to be clarified.

C-reactive protein levels according to physical activity and body weight for participants in the coronary health improvement project

OBJECTIVES

To identify whether the Coronary Health Improvement Project (CHIP), an intervention designed to increase physical activity and improve diet, lowers serum C-reactive protein (CRP). The study will also assess whether changes in CRP over the study period are associated with baseline levels of and changes in selected coronary risk factors.

METHODS

A randomized controlled study design assigned 348 individuals to the intervention or control group with measurements taken at baseline, 6 weeks, and 6 months of body weight, physical activity, and serum CRP levels. Participants attended an intensive 40-hour educational course delivered over a 4-week period, beginning March 2003, in Rockford, IL, USA.

RESULTS

The intervention significantly increased physical activity and decreased BMI, weight, percent body fat, and saturated fat (P<0.0001). However, the intervention was not significantly associated with a decrease in CRP. Participants in both the intervention and control groups combined showed a decrease in high CRP (>3 mg/L), from 46% at baseline to 38% at 6 weeks and 41% at 6 months. Those with higher BMI at baseline showed a greater increase in CRP over time (P<0.0001), whereas those with higher CRP at baseline showed a greater decrease in CRP over time (P<0.0001).

CONCLUSIONS

Over 6 week and 6 month follow-up periods, the intervention failed to discriminate changes in CRP. However, the percentage with high CRP did fall, more so for those with lower BMI and higher CRP at baseline. BMI may mediate the influence of physical activity on CRP.