Duration of pre-rheumatoid arthritis anti-cyclic citrullinated peptide positivity is positively associated with age at seroconversion

Elevated BMI and antibodies to citrullinated proteins interact to increase rheumatoid arthritis risk and shorten time to diagnosis: A nested case-control study of women in the Nurses' Health Studies

OBJECTIVE

Overweight/obesity and anti-citrullinated protein antibodies (ACPA) increase rheumatoid arthritis (RA) risk. We investigated the relationship between body mass index (BMI) and ACPA, tested for an interaction between BMI and ACPA for RA risk, and examined effects of BMI and ACPA on time to RA diagnosis.

DESIGN

Within the Nurses' Health Studies, blood samples were collected before diagnosis from medical record-confirmed incident RA cases and matched controls. Multiplex assays measured 7 ACPA subtypes (biglycan, clusterin, enolase, fibrinogen, histone 2A, histone 2B, and vimentin). Logistic regression analyses tested the association of BMI and ACPA and for a multiplicative interaction between BMI groups (≥25 vs. <25kg/m2) and ACPA positivity (≥2 vs. <2 subtypes), adjusting for age, smoking, alcohol use, and HLA-shared epitope. In case-only analyses, log-rank tests compared time from blood draw to RA onset by cross-classified BMI/ACPA status.

RESULTS

Among 255 pre-RA cases and 778 matched controls, 15.7% vs. 2.1% (p<0.001) had ≥2 ACPA and 49.4% vs. 40.2% (p<0.01) were overweight/obese. Continuous BMI was not associated with presence of ≥2 ACPA [OR per kg/m2 unit BMI: 1.03 (95% CI: 0.97-1.09)]. However, there was a multiplicative interaction between elevated BMI and the presence of ≥2 ACPA for RA risk (p = 0.027). Women with BMI≥25kg/m2 and ≥2 ACPA had OR 22.7 (95% CI: 6.64-77.72) for RA. Median time to RA differed by BMI/ACPA group (overall log-rank p<0.001) and was shortest among women with ≥2 ACPA and BMI≥25kg/m2 [45.0 months, IQR: 17.5-72.5] and longest in women with <2 ACPA and BMI<25kg/m2 [125.0 months, IQR: 72.0-161.0] (pairwise log-rank p = 0.002).

CONCLUSION

Elevated BMI and presence of ACPA interacted to increase RA risk. Time to RA onset was shortest among overweight/obese women with ≥2 ACPA.

Rheumatoid factor isotypes in relation to antibodies against citrullinated peptides and carbamylated proteins before the onset of rheumatoid arthritis

Background

The presence of rheumatoid factor (RF), anti-carbamylated protein antibodies (anti-CarP) and antibodies against citrullinated protein and peptides (ACPA) precedes the onset of symptoms of rheumatoid arthritis (RA) by several years. Relationships between the development of these antibodies are not obvious.

Methods

Three isotypes [immunoglobulin A (IgA), IgG and IgM) of RF were analysed in 321 pre-symptomatic individuals who provided 598 samples collected a median of 6.2 (interquartile range 7.2) years before the onset of symptoms, and in 492 population control subjects. All samples were donated to the Biobank of Northern Sweden. RF isotypes were analysed using the EliA system (Phadia GmbH, Freiburg, Germany) with 96 % specificity according to receiver operating characteristic curves. Ten ACPA specificities were analysed using the ImmunoCAP ISAC system, and anti-CCP2 and anti-CarP antibodies were evaluated using enzyme-linked immunosorbent assays.

Results

The frequencies of RF isotypes in pre-symptomatic individuals were significantly increased compared with control subjects (p < 0.0001). In samples collected ≥15 years before the onset of symptoms, the IgA-RF isotype was significantly more prevalent than the most frequent ACPAs. Combinations of IgM- and IgA-RF isotypes with ACPA specificities [α-enolase (CEP-1/Eno_5–21)], fibrinogen (Fib)β_36–52, Fibα_580–600, filaggrin (CCP-1/Fil_307–324) and anti-CCP2 antibodies were associated with a significantly shorter time to onset of symptoms (p < 0.001–0.05). Using conditional inference tree analysis, anti-CCP2 in combination with anti-filaggrin antibodies gave the highest probability, 97.5 %, for disease development.

Conclusions

RF isotypes predicted the development of RA, particularly in combination with ACPA, anti-CCP2 or anti-CarP antibodies. The highest probability for disease development was the presence of anti-CCP2 and anti-filaggrin antibodies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0940-2) contains supplementary material, which is available to authorized users.

Autoantibodies in prediction of the development of rheumatoid arthritis among healthy relatives of patients with the disease

OBJECTIVE

Although blood bank-based studies have shown that rheumatoid arthritis (RA)-related autoantibodies are present before the onset of RA, information on their positive predictive value (PPV) for development of RA in healthy individuals is scarce. This study was undertaken to assess the 5-year PPV of serum IgM rheumatoid factor (IgM-RF) and anti-cyclic citrullinated peptide (anti-CCP) for the development of RA among healthy relatives of patients with RA.

METHODS

Healthy relatives of RA patients were invited to participate in a cohort study. At baseline, information on participants' medical history was obtained, and serum levels of IgM-RF and anti-CCP antibodies were determined (by nephelometry and second-generation anti-CCP enzyme-linked immunosorbent assay, respectively). The subjects were followed up every 4 months via a structured interview (Community Oriented Program for Control of Rheumatic Diseases [COPCORD] questionnaire). When the COPCORD questionnaire indicated possible arthritis, subjects underwent an in-office rheumatology assessment including joint count. The study end point was defined as fulfillment of the American College of Rheumatology criteria for RA.

RESULTS

Eight hundred nineteen initially healthy relatives of 252 patients with RA were included (69% female, 41% offspring, mean ± SD age 35 ± 12 years). Eleven (1.3%) were positive for both anti-CCP-2 and RF, 12 (1.5%) only for anti-CCP-2, and 16 (2%) only for RF. RA developed in 17 (2.1%) of the relatives during the 5-year followup (3,313 person-years for the seronegative group and 60.8 person-years for the anti-CCP-2-positive group). The PPV was 64% when both anti-CCP-2 and RF were positive and 58% when only anti-CCP-2 was positive. Offspring of patients with RA had an independent 3-fold increased risk of developing RA.

CONCLUSION

Results of the present study indicate that the magnitude of risk for developing RA in healthy relatives of patients with RA can be estimated using simple routine laboratory tests.

Autoantibodies in pre-clinical autoimmune disease

The presence of autoantibodies is characteristic of autoimmune diseases. It is widely accepted that autoantibodies provide crucial diagnostic and prognostic information for autoimmune diseases. Indeed, numerous studies have demonstrated that the appearance of autoantibodies precedes the clinical onset of autoimmune diseases. We performed a literature review regarding the appearance of autoantibodies that preceded the clinical onset of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, primary biliary cirrhosis, inflammatory bowel disease, and multiple sclerosis. Herein we review and comment on the major findings of these studies.

Pathogenesis and prevention of rheumatic disease: focus on preclinical RA and SLE

Established and emerging data demonstrate that a 'preclinical' period of disease precedes the onset of clinical rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), as well as other autoimmune rheumatic diseases (ARDs).This preclinical stage of development of disease is characterized by abnormalities in disease-related biomarkers before the onset of the clinically apparent signs and symptoms. Numerous genetic and environmental risk factors for ARDs have also been identified, and many of these factors are likely to act before the clinical appearance of tissue injury to initiate and/or propagate autoimmunity and autoimmune disease. Thus, biomarkers representative of these autoimmune processes could potentially be used in conjunction with other clinical parameters during the preclinical period of ARDs to predict the future development of clinically apparent disease. This Review focuses on the preclinical stages of RA and SLE, as our current understanding of these diseases can be used to present an overall model of the development of ARDs that might ultimately be used to develop screening programmes and preventive strategies. Important considerations for the future development of such approaches, in particular, the issues that require additional research and how they might be addressed, are also discussed.

The number of elevated cytokines and chemokines in preclinical seropositive rheumatoid arthritis predicts time to diagnosis in an age-dependent manner

OBJECTIVE

To evaluate levels of biomarkers in preclinical rheumatoid arthritis (RA) and to use elevated biomarkers to develop a model for the prediction of time to future diagnosis of seropositive RA.

METHODS

Stored samples obtained from 73 military cases with seropositive RA prior to RA diagnosis and from controls (mean 2.9 samples per case; samples collected a mean of 6.6 years prior to diagnosis) were tested for rheumatoid factor (RF) isotypes, anti-cyclic citrullinated peptide (anti-CCP) antibodies, 14 cytokines and chemokines (by bead-based assay), and C-reactive protein (CRP).

RESULTS

Preclinical positivity for anti-CCP and/or ≥2 RF isotypes was >96% specific for future RA. In preclinical RA, levels of the following were positive in a significantly greater proportion of RA cases versus controls: interleukin-1α (IL-1α), IL-1β, IL-6, IL-10, IL-12p40, IL-12p70, IL-15, fibroblast growth factor 2, flt-3 ligand, tumor necrosis factor α, interferon-γ-inducible 10-kd protein, granulocyte-macrophage colony-stimulating factor, and CRP. Also, increasing numbers of elevated cytokines/chemokines were present in cases nearer to the time of diagnosis. RA patients who were ≥40 years old at diagnosis had a higher proportion of samples positive for cytokines/chemokines 5-10 years prior to diagnosis than did patients who were <40 years old at diagnosis (P < 0.01). In regression modeling using only case samples positive for autoantibodies highly specific for future RA, increasing numbers of cytokines/chemokines were predictive of decreased time to diagnosis, and the predicted time to diagnosis based on cytokines/chemokines was longer in older compared with younger cases.

CONCLUSION

Levels of autoantibodies, cytokines/chemokines, and CRP are elevated in the preclinical period of RA development. In preclinical autoantibody-positive cases, the number of elevated cytokines/chemokines is predictive of the time of diagnosis of future RA in an age-dependent manner.

Preclinical rheumatoid arthritis: identification, evaluation, and future directions for investigation

Rheumatoid arthritis (RA) likely develops in several phases, beginning with genetic risk, followed by asymptomatic autoimmunity, then finally, clinically apparent disease. Investigating the phases of disease that exist prior to the onset of symptoms (ie, the preclinical period of RA) will lead to understanding of the important relationships between genetic and environmental factors that may lead to disease, as well as allow for the development of predictive models for disease, and ultimately preventive strategies for RA.

What happens before the onset of rheumatoid arthritis?

PURPOSE OF REVIEW

To give an overview of publications on presence of autoantibodies, rheumatoid factor and anticitrullinated protein/peptide antibodies (ACPAs) and their relationships to genetic markers and soluble factors as indicators of immune activation and identified predating the onset of symptoms of rheumatoid arthritis (RA).

RECENT FINDINGS

The development during recent years concerning autoantibodies with high specificity for RA, ACPAs, has confirmed previous findings of presence of autoantibodies, such as rheumatoid factors and antikeratin antibodies, years before disease onset. Particularly, ACPAs in combination with human leukocyte antigen-shared epitope alleles and PTPN22 1858T carriage increased the relative risks of developing RA compared with not having these factors. Both shared epitope alleles and 1858T variant seemed to contribute to development of ACPAs rather than independently contribute to RA. Soluble factors such as hypersensitive C-reactive protein, cytokines, cytokine receptors and chemokines are upregulated before disease onset, though, not as long antedating time as ACPAs and rheumatoid factors.

SUMMARY

Presence of ACPAs and rheumatoid factors are present several years before disease onset suggesting a gradual process leading to the development of RA. Genetic markers such as shared epitope alleles and PTPN22 1858T variant increase the relative risk for disease development. Soluble immunological markers are also increased closer to the onset of symptoms indicating activation of the immune system.