Increased levels of C-reactive protein in serum from blood donors before the onset of rheumatoid arthritis

Biological variation and reference intervals for circulating osteopontin, osteoprotegerin, total soluble receptor activator of nuclear factor kappa B ligand and high‐sensitivity C‐reactive protein

OBJECTIVE

Monitoring inflammatory diseases and osteoclastogenesis with osteopontin (OPN), osteoprotegerin (OPG), total soluble receptor activator of nuclear factor kappa B ligand (total sRANKL) and high-sensitivity C-reactive protein (hsCRP) has recently attracted increased interest. The purpose of our study was to determine reference intervals, variability caused by sampling time, biological variation and stability after repeated freeze-thaw cycles of circulating levels of OPN, OPG, total sRANKL and hsCRP.

MATERIAL AND METHODS

Plasma OPN and plasma OPG concentrations were determined with sandwich ELISA; serum total sRANKL concentration was determined using a two-site sandwich ELISA; and hsCRP was analysed by turbidimetry in 300 Danish blood donors (183 M and 117 F) with a median age of 43 years (range 18-64 years). Variability due to biological variation and sampling time was studied in serial samples from 38 healthy subjects.

RESULTS

The 95th percentiles in the donors were 76 microg/L for OPN, 4.2 pmol/L for OPG, 40.2 nmol/L for total sRANKL and 12 mg/L for hsCRP. The overall medians for both genders were 51 microg/L, 2.2 pmol/L, 0.66 nmol/L and 1.0 mg/L, respectively. We found a significant correlation between hsCRP and OPN (rho = 0.173; p<0.003). The biological within-subject variations were calculated to be 8.2 % for OPN, 8.8% for total sRANKL and 50% for hsCRP.

CONCLUSIONS

Reference intervals have been established with a high analytic performance for OPN and an acceptable analytic performance for OPG and total sRANKL. The study revealed low biological variation for OPN and total sRANKL and high biological variation for hsCRP.

Different properties of ACPA and IgM-RF derived from a large dataset: further evidence of two distinct autoantibody systems

Introduction

The aim of this study was to examine seroconversion and the relationship with age and inflammation of autoantibodies in a large group of patients attending an outpatient rheumatology clinic.

Methods

Levels of antibodies to citrullinated proteins/peptides (ACPAs) and IgM rheumatoid factor (IgM-RF) were determined in 22,427 samples collected from 18,658 patients. The diagnosis was derived from a diagnosis registration system. The degree of seroconversion in repeated samples and the correlation of levels with age and inflammatory markers were determined for ACPA and IgM-RF in rheumatoid arthritis (RA) and non-RA patients.

Results

Seventy-one percent of RA patients (n = 1,524) were ACPA-positive and 53% were IgM-RF-positive; in non-RA patients (n = 2,245), the corresponding values were 2% and 4%, respectively. In patients with at least two samples (n = 3,769), ACPA status was more stable than IgM-RF status in RA patients. ACPA- or IgM-RF-negative non-RA patients seldom became positive. ACPA positivity was unrelated to age in both RA and non-RA patients. IgM-RF positivity was unrelated to age in RA patients; however, it increased with age in non-RA patients. The correlation between autoantibody levels and inflammatory markers was low in general and was somewhat higher for IgM-RF than for ACPA.

Conclusions

ACPA status is more stable in time and with increasing age than IgM-RF status, further establishing its role as a disease-specific marker. ACPA and IgM-RF levels are only moderately correlated with markers of inflammation.

Biomarkers of inflammation and development of rheumatoid arthritis in women from two prospective cohort studies

OBJECTIVE

To examine the association of biomarkers of inflammation with preclinical rheumatoid arthritis (RA).

METHODS

A nested case-control study was performed using samples from 2 large, prospectively studied cohorts of women (the Women's Health Study [WHS] and the Nurses' Health Study [NHS]). Blood samples obtained prior to symptom onset in women who later developed RA were selected as incident RA cases, and 3 controls per case were randomly chosen, matched for age, menopausal status, postmenopausal hormone use, and day, time, and fasting status at the time of collection. Plasma was tested for levels of interleukin-6 (IL-6), soluble tumor necrosis factor receptor II (sTNFRII) (as a proxy for TNFalpha), and high-sensitivity C-reactive protein. Relationships between biomarkers and RA were assessed using conditional logistic regression models, adjusting for age, body mass index, smoking habits, ethnicity, and reproductive factors.

RESULTS

In 93 incident cases in the NHS and 77 incident cases in the WHS, the mean time between blood collection and the onset of RA symptoms was 5.2 years (range 0.3-12 years). Median IL-6 and sTNFRII levels were significantly higher in preclinical RA cases compared with matched controls in the NHS (P = 0.03 and P = 0.003, respectively) though not in the WHS. Pooled analysis of the NHS and WHS cohorts demonstrated significant association of sTNFRII with RA (relative risk 2.0 [95% confidence interval 1.1-3.6], P for trend = 0.004), and a modest association of IL-6 with RA (relative risk 1.4 [95% confidence interval 0.8-2.5], P for trend = 0.06).

CONCLUSION

Levels of sTNFRII, a biomarker typically associated with active RA, were elevated up to 12 years prior to the development of RA symptoms and were positively associated with incident RA in these nested case-control studies. Studies with repeated assessments of biomarkers prior to RA development may provide further insight into the timing of biomarker elevation in preclinical RA.

Inflammation, carotid intima-media thickness and atherosclerosis in rheumatoid arthritis

Carotid intima-media thickness (cIMT) reflects early atherosclerosis and predicts cardiovascular events in the general population. An increased cIMT is present in patients with rheumatoid arthritis, compared with control individuals, from the early stages of the disease and is thought to indicate accelerated atherosclerosis, but direct evidence is not available. Whether cIMT is susceptible to rapid and potentially reversible change depending on the intensity of inflammation in states of high-grade systemic inflammation, such as rheumatoid arthritis, remains unknown. If this is the case, an increased cIMT in such disease states may not reflect structural vessel wall damage, and may not be a good predictor of future cardiovascular events in these particular populations. Prospective, long-term, longitudinal studies are needed to address these questions.

C-reactive protein, inflammatory conditions, and cardiovascular disease risk

BACKGROUND

It is uncertain to what extent high C-reactive protein (CRP) concentrations reflect the presence of inflammatory conditions in the community.

METHODS

We evaluated 3782 Framingham Offspring Study participants (mean age 55 years; 52% women) free of baseline cardiovascular disease. Logistic regression models examined the prevalence of common inflammatory conditions by CRP categories, while a separate matched case-referent analysis evaluated the prevalence of uncommon inflammatory conditions. Cox models were used to assess the influence of common inflammatory conditions on relations between CRP and incident cardiovascular disease.

RESULTS

Common inflammatory conditions were reported by nearly half of the participants; these individuals were more likely to have markedly high CRP concentrations (>10 mg/L, P for trend=.001). In multivariable models, there were increased odds of having at least one common inflammatory condition with CRP concentrations of 1-3.0, 3.01-10, and >10 mg/L, compared with the referent category (<1 mg/L); the respective odds ratios with 95% confidence intervals were 1.41 (1.07-1.86), 1.45 (1.07-1.98), and 1.64 (1.09-2.47) in men, and 1.08 (0.82-1.43), 1.07 (0.80-1.44), and 1.38 (0.97-1.96) in women. In case-referent analyses, uncommon inflammatory conditions were more common in individuals with CRP >10 mg/L compared with those with CRP <1 mg/L (12.1% vs 6.6%; P=.0001). In multivariable models, higher CRP categories were not associated with incident cardiovascular disease, and with additional adjustment for inflammatory conditions, results remained unchanged.

CONCLUSION

There is high prevalence of common and uncommon inflammatory conditions in individuals with high CRP concentrations. Higher CRP concentrations should be interpreted with caution in cardiovascular disease risk assessment.

African Americans at risk for increased iron stores or liver disease

PURPOSE

We sought to determine the prevalence of elevated measures of iron status in African Americans and whether the combination of serum ferritin concentration >200 microg/L for women or >300 microg/L for men and transferrin saturation in the highest quartile represents increased likelihood of mutation of HFE, self-reported iron overload or self-reported liver disease.

SUBJECTS AND METHODS

A cross-sectional observational study of 27,224 African Americans > or =25 years of age recruited in a primary care setting was conducted as part of the multi-center, multi-ethnic Hemochromatosis and Iron Overload Screening (HEIRS) Study. Measurements included serum ferritin concentration, transferrin saturation, testing for HFE C282Y and H63D, and self-reported iron overload and liver disease.

RESULTS

Serum ferritin concentration >200 microg/L for women or >300 microg/L for men occurred in 5263 (19.3%) of African Americans, while serum ferritin concentration in this range with highest-quartile transferrin saturation (>29% women; >35% men) occurred in 1837 (6.7%). Adjusted odds of HFE mutation (1.76 women, 1.67 men), self-reported iron overload (1.97 women, 2.88 men), or self-reported liver disease (5.18 women, 3.73 men) were greater with elevated serum ferritin concentration and highest-quartile transferrin saturation than with nonelevated serum ferritin concentration (each P <.05).

CONCLUSIONS

Serum ferritin concentration >200 microg/L for women or >300 microg/L for men in combination with transferrin saturation >29% for women or >35% for men occurs in approximately 7% of adult African American primary care patients. Patients with this combination of iron test results should be evaluated for increased body iron stores or liver disease.

Early environmental exposure and the development of lupus

Systemic lupus erythematosus (SLE) is a complex trait with evidence of polygenic inheritance influenced by environmental factors. However, the precise underlying causes of SLE remain unclear. A number of environmental exposures have been associated with lupus or related autoimmune phenomena. Evidence suggests that some environmental exposures need to be present many years before the onset of SLE. Both SLE and rheumatoid arthritis (RA) can occur in very young children and this supports the possibility that important environmental factors must be present during or before this time. In addition, the immune pathology, including autoantibody production, in adult lupus may begin years before clinical disease. There is also evidence that the developing immune system demonstrates developmental plasticity and can be permanently altered or 'programmed' by the early environment. We describe how early life environmental influences including infectious exposure may lead to autoantibody production in later life thus beginning the journey that leads to autoimmune diseases such as lupus in susceptible individuals.

Use of prognostic markers in early rheumatoid arthritis to identify patients at risk of destructive disease

As the benefits of early aggressive treatment of rheumatoid arthritis have become clear, and with the availability of newer (and more expensive) therapies, we need to be able to identify which patients are most at risk of destructive disease and poorer outcomes, and therefore, pinpoint which patients are most likely to benefit from intensive intervention at an early stage. A need for reliable prognostic markers is paramount in identifying these patients. Anticyclic citrullinated peptide antibody and serum inflammatory markers can precede the onset of disease by months and aid in both diagnosis and prognosis. Newer imaging modalities are now available and add to information gained from conventional radiography. This article reviews laboratory markers and imaging currently used in recognizing those patients at risk of nonreversible, destructive disease.

Identification and Functional Validation of Novel Autoantigens in Equine Uveitis

The development, progression, and recurrence of autoimmune diseases are frequently driven by a group of participatory autoantigens. We identified and characterized novel autoantigens by analyzing the autoantibody binding pattern from horses affected by spontaneous equine recurrent uveitis to the retinal proteome. Cellular retinaldehyde-binding protein (cRALBP) had not been described previously as autoantigen, but subsequent characterization in equine recurrent uveitis horses revealed B and T cell autoreactivity to this protein and established a link to epitope spreading. We further immunized healthy rats and horses with cRALBP and observed uveitis in both species with typical tissue lesions at cRALBP expression sites. The autoantibody profiling outlined here could be used in various autoimmune diseases to detect autoantigens involved in the dynamic spreading cascade or serve as predictive markers.

Lipids and inflammation: serial measurements of the lipid profile of blood donors who later developed rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis is characterised by inflammation and an increased cardiovascular risk. It was recently shown that active early rheumatoid arthritis is associated with dyslipidaemia, which may partially explain the enhanced cardiovascular risk. However, it is unknown when this dyslipidaemia starts.

OBJECTIVE

To investigate the progression of the lipid profile over time and the influence of inflammatory parameters on this lipid profile, in people who later developed rheumatoid arthritis.

METHODS

Levels of total cholesterol, high-density lipoprotein cholesterol (HDLc), triglycerides, apolipoprotein AI (apo AI), apolipoprotein B (apo B) and lipoprotein(a) (Lp(a)) were determined in 1078 stored, deep-frozen, serial blood bank samples, collected between 1984 and 1999, of 79 blood donors who later developed rheumatoid arthritis. These samples were compared with 1071 control samples of unselected blood donors, matched for age, sex and storage time.

RESULTS

Samples of patients who later developed rheumatoid arthritis showed, on average, 4% higher total cholesterol, 9% lower HDLc, 17% higher triglyceride and 6% higher apo B levels than matched controls (p< or =0.05). The magnitude of the differences in lipid levels between groups, explained by C reactive protein (CRP), was limited. For example, only 3.6% of the difference in HDLc levels between the groups was explained by the CRP concentrations.

CONCLUSION

Patients who later develop rheumatoid arthritis have a considerably more atherogenic lipid profile than matched blood donors at least 10 years before onset of symptoms. As inflammation only marginally explains the differences between the two groups, a modulating effect of lipids on inflammatory processes is hypothesised.

Up regulation of monocyte chemoattractant protein-1 expression in anti-citrulline antibody and immunoglobulin M rheumatoid factor positive subjects precedes onset of inflammatory response and development of overt rheumatoid arthritis

OBJECTIVE

To analyse the inflammatory mediators, including monocyte chemoattractant protein-1 (MCP-1), in blood samples donated years before onset of rheumatoid arthritis. Previously, it has been shown in these individuals that antibodies against cyclic citrullinated peptide (anti-CCP) detectable years before the onset of symptoms have a high predictive value for development of rheumatoid arthritis.

METHODS

A nested case-control study was performed: patients with rheumatoid arthritis were identified from among blood donors antedating onset by a median of three years (pre-patients, n = 92); four matched controls were selected randomly for each pre-patient. Plasma were analysed for secretory phospholipase A2 (sPLA2) and MCP-1 using ELISA, for high-sensitivity C reactive protein (hsCRP) using the chemiluminescence method and for interleukin-6 using a sensitive bioassay.

RESULTS

When the results were stratified for the presence of anti-CCP antibodies and immunoglobulin M-rheumatoid factor (IgM-RF), only MCP-1 levels were found to be significantly raised in patients with anti-CCP and IgM-RF compared with controls.

CONCLUSION

Levels of MCP-1 were significantly increased in the plasma of patients having anti-CCP antibodies or IgM-RF and who later developed rheumatoid arthritis. These findings indicate up regulation of chemotactic activity for leucocytes before the development of rheumatoid arthritis.

Early environmental factors and rheumatoid arthritis

The precise cause of autoimmune diseases such as rheumatoid arthritis (RA) remains uncertain. In recent years there has been extensive investment in pursuing genes important in RA. However, estimates suggest that the risk of developing RA is at most 50% determined by genes. There has been limited success defining the environmental factors important in developing RA. We hypothesize that this lack of success may be due to a concentration on the time around disease onset. There is evidence of production of the autoantibodies rheumatoid factor (RF) and anti-cyclic citrullinated peptides (anti-CCP) and increased levels of C-reactive protein (CRP) years before RA becomes clinically apparent. In addition, early life events including intrauterine growth retardation (IUGR) may have long lasting effects on immune function. We review the evidence that the early environment through effects on growth and infectious exposure may influence the likelihood of developing autoimmune diseases such as RA.

What does minor elevation of C-reactive protein signify?

Reports of the predictive value of minor elevation of serum C-reactive protein (CRP) levels (between 3 and 10 mg/L) for atherosclerotic events have generated considerable interest, as well as a degree of controversy and confusion. CRP concentrations in this range are found in about one third of the American population. To better understand the mechanisms underlying minor elevation of CRP, we have surveyed its reported associations with a variety of states and conditions. It has become clear that even minimal environmental irritants and inflammatory stimuli elicit a minor CRP response. Minor CRP elevation has been found associated with a number of genetic polymorphisms, with membership in different demographic and socioeconomic groups, with a variety of dietary patterns and with many medical conditions that are not apparently inflammatory. Finally, minor CRP elevation bears negative prognostic implications for many conditions, particularly age-related diseases, and predicts mortality in both diseased and apparently healthy individuals. In sum, minor CRP elevation is associated with a great many diverse conditions, some of which are, or may prove to be, causal. Many of these reported associations imply a mild degree of tissue stress or injury, suggesting the hypothesis that the presence of distressed cells, rather than a resulting inflammatory response, is commonly the stimulus for CRP production.

The Evidence for Early Intervention

It is believed that rheumatoid arthritis (RA) is the most common, potentially treatable cause of disability in the Western world. A commonsense approach to the management of a persistent, progressive, damaging condition such as RA would seem to be intervention before the onset of damage, at a stage when disease still may be reversible. Such a phase of disease has been described as a "window of opportunity" for intervention. This article discusses the evidence for early intervention in RA.

Synovial biopsy

In patients with arthritis, synovial tissue is easily accessible for analysis. Blind needle biopsy is a simple and safe procedure. Arthroscopic biopsy is also safe, it allows access to most sites in the joint and it can provide adequate tissue for extensive laboratory investigations, both before and after successful therapy. Synovial tissue analysis has been successfully applied to the study of disease mechanisms and response to treatment. In addition, there may be an indication for diagnostic synovial biopsy in selected cases.

Simultaneous development of acute phase response and autoantibodies in preclinical rheumatoid arthritis

OBJECTIVE

To investigate the temporal relationship between onset of inflammation (as measured by secretory phospholipase A2 (sPLA2) and C reactive protein (CRP)) and the presence of autoantibodies (IgM rheumatoid factor (IgM RF) and antibodies against citrullinated peptides (anti-CCP)) in the preclinical phase of rheumatoid arthritis (RA).

METHODS

For 79 patients with RA who had been blood donors before the onset of disease, a median of 13 serum samples per patient was available. sPLA2 was measured in patient and matched control samples and related to previous CRP, IgM RF, and anti-CCP measurements. The temporal relationship between the increased markers of inflammation and autoantibodies was analysed with time lag analysis.

RESULTS

IgM RF and anti-CCP concentrations were significantly associated (p<0.001) with concentrations of sPLA2, CRP, and the combination of sPLA2 and CRP at the same time point. However, we found no stronger association between the two autoantibody tests and the three inflammation measures 1, 2, and 3 years before or after a time point than for measurements at the same time, in the whole group or in subgroups of IgM RF and anti-CCP positive patients.

CONCLUSION

Both the acute phase response and autoantibody formation often develop years before the first symptoms of RA occur, and these phenomena are probably closely connected in time.

Modeling human arthritic diseases in nonhuman primates

Models of rheumatoid arthritis (RA) in laboratory animals are important tools for research into pathogenic mechanisms and the development of effective, safe therapies. Rodent models (rats and mice) have provided important information about the pathogenic mechanisms. However, the evolutionary distance between rodents and humans hampers the translation of scientific principles into effective therapies. The impact of the genetic distance between the species is especially seen with treatments based on biological molecules, which are usually species-specific. The outbred nature and the closer anatomical, genetic, microbiological, physiological, and immunological similarity of nonhuman primates to humans may help to bridge the wide gap between inbred rodent strain models and the heterogeneous RA patient population. Here we review clinical, immunological and pathological aspects of the rhesus monkey model of collagen-induced arthritis, which has emerged as a reproducible model of human RA in nonhuman primates.

Alexithymic characteristics and patient-therapist interaction: a video analysis of facial affect display

Alexithymia as a disorder of affect regulation entails a patient's reduced ability to process emotional information. The purpose of this study was to evaluate the impact of alexithymia [as measured by the Toronto Alexithymia Scale (TAS)-26, German version] on affective correlates in a dyadic therapeutic interaction (as recorded by the Emotional Facial Action Coding System). Interviews with 12 in-patients with various psychosomatic disorders (anxiety, depression, somatisation) were videotaped and evaluated for facial affect display. The corresponding emotional reactions of the therapists (split screen) were recorded separately. Patients with high alexithymia scores (TAS-26 total score) tended to display less aggressive affects than those with low scores. The therapists' predominant emotional reaction to alexithymic patients was contempt. Our findings underscore the deep-rooted nature of alexithymia as a disorder of affect regulation. Since facial affects play a major role in the regulation of emotional interaction, this disorder may evoke negative reactions of potential caregivers.

The risk of congestive heart failure in rheumatoid arthritis: A population-based study over 46 years

OBJECTIVE

It is hypothesized that the systemic inflammation associated with rheumatoid arthritis (RA) promotes an increased risk of cardiovascular (CV) morbidity and mortality. We examined the risk and determinants of congestive heart failure (CHF) in patients with RA.

METHODS

We assembled a population-based, retrospective incidence cohort from among all individuals living in Rochester, Minnesota, in whom RA (defined according to the American College of Rheumatology 1987 criteria) was first diagnosed between 1955 and 1995, and an age- and sex-matched non-RA cohort. After excluding patients in whom CHF occurred before the RA index date, all subjects were followed up until either death, incident CHF (defined according to the Framingham Heart Study criteria), migration from the county, or until January 1, 2001. Detailed information from the complete medical records (including all inpatient and outpatient care provided by all local providers) regarding RA, ischemic heart disease, and traditional CV risk factors was collected. Cox models were used to estimate the effect of RA on the development of CHF, adjusting for CV risk factors and/or ischemic heart disease.

RESULTS

The study population included 575 patients with RA and 583 subjects without RA. The CHF incidence rates were 1.99 and 1.16 cases per 100 person-years in patients with RA and in non-RA subjects, respectively (rate ratio 1.7, 95% confidence interval [95% CI] 1.3-2.1). After 30 years of followup, the cumulative incidence of CHF was 34.0% in patients with RA and 25.2% in non-RA subjects (P< 0.001). RA conferred a significant excess risk of CHF (hazard ratio [HR] 1.87, 95% CI 1.47-2.39) after adjusting for demographics, ischemic heart disease, and CV risk factors. The risk was higher among patients with RA who were rheumatoid factor (RF) positive (HR 2.59, 95% CI 1.95-3.43) than among those who were RF negative (HR 1.28, 95% CI 0.93-1.78).

CONCLUSION

Compared with persons without RA, patients with RA have twice the risk of developing CHF. This excess risk is not explained by traditional CV risk factors and/or clinical ischemic heart disease.