Autoantibodies binding to citrullinated telopeptide of type II collagen and to cyclic citrullinated peptides predict synergistically the development of seropositive rheumatoid arthritis

Predicting autoimmune diseases: A comprehensive review of classic biomarkers and advances in artificial intelligence

Autoimmune diseases comprise a spectrum of disorders characterized by the dysregulation of immune tolerance, resulting in tissue or organ damage and inflammation. Their prevalence has been on the rise, significantly impacting patients' quality of life and escalating healthcare costs. Consequently, the prediction of autoimmune diseases has recently garnered substantial interest among researchers. Despite their wide heterogeneity, many autoimmune diseases exhibit a consistent pattern of paraclinical findings that hold predictive value. From serum biomarkers to various machine learning approaches, the array of available methods has been continuously expanding. The emergence of artificial intelligence (AI) presents an exciting new range of possibilities, with notable advancements already underway. The ultimate objective should revolve around disease prevention across all levels. This review provides a comprehensive summary of the most recent data pertaining to the prediction of diverse autoimmune diseases and encompasses both traditional biomarkers and the latest innovations in AI.

Predicting the onset of rheumatoid arthritis

Various scores have attempted to predict the onset of rheumatoid arthritis (RA). In particular, EULAR proposed a simple rule to identify new-onset arthralgia suspicious for progression to RA. However, its specificity would likely be higher if serological tests were included. In patients with clinical arthritis, reliable predictive criteria for progression to RA have also been identified. Overall, the validity of the available scores is still being debated. Such scores do not fully account for the interactions between risk factors in specific subpopulations. New technologies could help to overcome these limitations, but we need databases containing a sufficient number of RA and pre-RA patients, including pre-diagnostic monitoring. Today, the existing predictive rules cannot compete with expert opinions.

Possible roles of anti-type II collagen antibody and innate immunity in the development and progression of diabetic retinopathy

The pathogenesis of both diabetic retinopathy (DR) and rheumatoid arthritis (RA) has recently been considered to involve autoimmunity. Serum and synovial fluid levels of anti-type II collagen antibodies increase early after the onset of RA, thus inducing immune responses and subsequent hydrarthrosis and angiogenesis, which resemble diabetic macular edema and proliferative DR (PDR), respectively. We previously reported that DR is also associated with increased serum levels of anti-type II collagen antibodies. Retinal hypoxia in DR may induce pericytes to express type II collagen, resulting in autoantibody production against type II collagen. As the result of blood-retinal barrier disruption, anti-type II collagen antibodies in the serum come into contact with type II collagen around the retinal vessels. A continued loss of pericytes and type II collagen around the retinal vessels may result in a shift of the immune reaction site from the retina to the vitreous. It has been reported that anti-inflammatory M2 macrophages increased in the vitreous of PDR patients, accompanied by the activation of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, a key regulator of innate immunity. M2 macrophages promote angiogenesis and fibrosis, which might be exacerbated and prolonged by dysregulated innate immunity.

Cohort profile: SCREEN-RA: design, methods and perspectives of a Swiss cohort study of first-degree relatives of patients with rheumatoid arthritis

PURPOSE

Rheumatoid arthritis (RA) is an insidious autoimmune disease, with an immunological onset years before diagnosis. Early interventions in preclinical stages could prevent or minimise the progression towards irreversible joint damage. The SCREEN-RA cohort (Evaluation of a SCREENing strategy for Rheumatoid Arthritis) aims to characterise the preclinical stages of the disease, to identify environmental risk factors, and to discover or validate novel biomarkers predictive for RA development.

PARTICIPANTS

SCREEN-RA includes an at-risk population for RA, namely first-degree relatives of patients with established RA.

FINDINGS TO DATE

The cohort started in 2009 is composed of mostly asymptomatic healthy individuals (total n=1458, 7262 person-years), with a mean age of 44 years at enrolment, 74% female and 91% Caucasian ethnicity. During the study period, 16 participants have developed RA. All participants provide baseline serum, DNA and RNA samples, and in a subset, stool samples and oral examination are performed for microbiota assessment. At enrolment, 10% of participants had asymptomatic autoimmunity associated with RA (n=147), 10% presented 'clinically suspect arthralgias' (n=143) and 3% reported arthralgias in conjunction with autoimmunity or high genetic risk (n=51). Studies with this cohort have uncovered risk factors for RA development, such as female hormonal factors, poor oral health or intestinal dysbiosis.

FUTURE PLANS

Future directions include immunological and 'multiomics' approaches to discover new biological markers of progression towards RA, as well as testing preventive interventions in 'high-risk' population.

Objective and noninvasive biochemical markers in rheumatoid arthritis: where are we and where are we going?

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects approximately 1% of the adult population. RA is multi-factorial, and as such our understanding of the molecular pathways involved in the disease is currently limited. An increasing number of studies have suggested that several molecular phenotypes (i.e. endotypes) of RA exist, and that different endotypes respond differently to various treatments. Biochemical markers may be an attractive means for achieving precision medicine, as they are objective and easily obtainable.

AREAS COVERED

We searched recent publications on biochemical markers in RA as either diagnostic or prognostic markers, or as markers of disease activity. Here, we provide a narrative overview of different classes of markers, such as autoantibodies, citrulline products, markers of tissue turnover and cytokines, that have been tested in clinical cohorts or trials including RA patients.

EXPERT OPINION

Although many biochemical markers have been identified and tested, few are currently being used in clinical practice. As more treatment options are becoming available, the need for precision medicine tools that can aid physicians and patients in choosing the right treatment is growing.

In vitro elimination of autoreactive B cells from rheumatoid arthritis patients by universal chimeric antigen receptor T cells

OBJECTIVES

Autoreactive B cells play a crucial role in the pathogenesis of rheumatoid arthritis (RA), and B cell-depleting therapies using an antibodies, such as rituximab, have been suggested to be effective in RA treatment. However, transient B cell depletion with rituximab is associated with significant safety challenges related to global suppression of the immune system and thus increases the risks of infection and cancer development. To address selective and persistent issues associated with RA therapy, we developed a customised therapeutic strategy employing universal antifluorescein isothiocyanate (FITC) chimeric antigen receptor T cells (CAR-T cells) combined with FITC-labelled antigenic peptide epitopes to eliminate autoreactive B cell subsets recognising these antigens in RA.

METHODS

For a proof-of-concept study, four citrullinated peptide epitopes derived from citrullinated autoantigens, namely, citrullinated vimentin, citrullinated type II collagen, citrullinated fibrinogen and tenascin-C, and a cyclocitrulline peptide-1 were selected as ligands for targeting autoreactive B cells; Engineered T cells expressing a fixed anti-FITC CAR were constructed and applied as a universal CAR-T cell system to specifically eliminate these protein-specific autoreactive B cells via recognition of the aforementioned FITC-labelled autoantigenic peptide epitopes.

RESULTS

We demonstrated that anti-FITC CAR-T cells could be specifically redirected and kill hybridoma cells generated by immunisation with antigenic peptides, and autoreactive B cell subsets from RA patients via recognition of corresponding FITC-labelled citrullinated peptide epitopes. Additionally, the cytotoxicity of the CAR-T cells was dependent on the presence of the peptides and occurred in a dose-dependent manner.

CONCLUSIONS

The approach described here provides a direction for precise, customised approaches to treat RA and can likely be applied to other systemic autoimmune diseases.

Periodontal status correlates with anti-citrullinated protein antibodies in first-degree relatives of individuals with rheumatoid arthritis

AIM

To evaluate periodontal status in first-degree relatives of patients with rheumatoid arthritis (FDR-RA) and detect correlation with the presence of anti-citrullinated protein antibodies (ACPAs).

MATERIALS AND METHODS

Rheumatologic status and periodontal status were evaluated in a nested case-control study of FDR-RA with no diagnosis of RA at enrolment. The following parameters were assessed in 34 ACPA-positive (ACPA+) and 65 ACPA-negative (ACPA-) subjects: gingival index (GI), plaque index (PI), probing depth (PD), bleeding on probing (BOP) and clinical attachment level (CAL). We compared the two groups using conditional logistic regression.

RESULTS

In ACPA+ individuals, the mean, PD, BOP, CAL and number of sites per person with PD > 4 mm and BOP were significantly higher compared to the ACPA- group. All ACPA+ subjects had periodontitis: 44.1% presenting moderate and 47.1% severe periodontitis. ACPA- subjects had mainly mild (30.8%) and moderate (27%) periodontitis, differences being significantly different for both moderate periodontitis (p = 0.001) and severe periodontitis (p < 0.001). In multivariable analyses, ACPA status (p = 0.04) and age (p = 0.002) were significantly and independently associated with periodontal conditions.

CONCLUSION

High prevalence and severity of periodontitis in FDR-RA was associated with seropositivity to ACPAs. This further strengthens the hypothesis that periodontitis may be a risk factor in the development of RA.

How well do ACPA discriminate and predict RA in the general population: a study based on 12 590 population-representative Swedish twins

Objective

Anti-citrullinated protein antibodies (ACPA) are highly specific for rheumatoid arthritis (RA), but the diagnostic accuracy of ACPA in the general population has not been thoroughly assessed. We aimed to assess the diagnostic accuracy of ACPA for RA in the general population and to further characterise the citrullinated peptide recognition pattern.

Methods

Serum samples from a large population-representative twin cohort consisting of 12 590 individuals were analysed for the presence of ACPA using anti-CCP2 ELISA. All ACPA-positive samples were further tested on ELISAs for four peptide-specific ACPA. RA cases were identified by linkage to the Swedish National Patient Register at inclusion and after a median follow-up of 37 months (IQR 31–49).

Results

350 out of 12 590 individuals had a positive anti-CCP2 test, measuring ACPA. Of these, 103 had an RA diagnosis at the time of blood donation and inclusion. During a median follow-up of 3 years, an additional 21 of the remaining 247 ACPA-positive individuals developed RA. Overall, a positive anti-CCP2 test had a positive predictive value of 29% for prevalent RA at inclusion (negative predictive value of 99.6%). High titres (>3× cut-off) of anti-CCP2 increased the positive predictive value to 48% (negative predictive value of 99.5%). ACPA-positive individuals without RA had lower anti-CCP2 titres and fewer peptide-specific ACPA than ACPA-positive patients with RA and higher C reactive protein levels than ACPA-negative individuals without RA.

Conclusion

Presence of ACPA and especially high titres of anti-CCP2 have a high diagnostic accuracy for an RA diagnosis in a population setting.

Ureido group-specific antibodies are induced in rabbits immunized with citrulline- or homocitrulline-containing antigens

The specificities and cross-reactions of antibodies induced by citrulline- and homocitrulline-containing proteins may give implications on the role of citrulline- and homocitrulline-binding antibodies in the pathogenesis and progression of rheumatoid arthritis (RA). Here we use rabbits as an experimental model of antibody development in RA. Thirty-two animals were immunized with peptide antigens containing either homocitrulline or citrulline. The sera were tested for binding to CCP and MCV antigens and to peptide sequences related to carboxyterminal telopeptides of type I and II collagens and containing arginine, citrulline, or homocitrulline. The binding of CCP and MCV antigens to antisera against homocitrulline-containing immunogens could be inhibited by human serum albumin containing homocitrulline, whereas similar binding to sera against citrulline-containing immunogens was not inhibited. The antisera induced with citrulline-containing collagen telopeptides recognized type I collagen-related antigens in a sequence-specific manner, as antibody binding to both citrulline- and homocitrulline-containing peptides was inhibited by corresponding citrullinated and native peptides. In contrast, type II collagen-related peptides were recognized by the antisera in a ureido group-specific manner, as their binding to homocitrulline-containing peptide was inhibited by both citrulline- and homocitrulline-containing, but not native peptide. Binding of the citrullinated type II collagen peptide could only be inhibited by the similarly citrullinated peptide. In conclusion, antibodies induced with citrulline or homocitrulline-containing antigens bound antigens in a ureido group-specific manner, recognizing citrulline and homocitrulline also in other sequences than those used in the original immunization. In competitive situations the amino acid present in the immunization antigen was favored.

Separate and overlapping specificities in rheumatoid arthritis antibodies binding to citrulline- and homocitrulline-containing peptides related to type I and II collagen telopeptides

Introduction

Our objective was to find out if there are antibodies binding to homocitrulline-containing type I and II collagen carboxyterminal telopeptides in sera of patients with rheumatoid arthritis (RA), and if these antibodies cross-react with citrulline and homocitrulline in the same peptide sequence.

Methods

A total of 72 RA and 72 control sera were analyzed for binding using enzyme-linked immunosorbent assay to citrulline- or homocitrulline-containing type I and II collagen carboxyterminal telopeptides, as well as to cyclic citrullinated peptide (CCP) and to mutated citrullinated vimentin (MCV). Specificities of the antibodies were tested using inhibition-ELISA.

Results

Of the RA sera, 39 (54%) and 41 (57%) were positive for binding to CCP and MCV, respectively. Further, 34 (47%) and 30 (42%) of the patients had specific antibodies binding to and being inhibited by citrulline-containing type I collagen telopeptides and by citrulline-containing type II collagen carboxyterminal telopeptides, respectively. The corresponding figures regarding homocitrulline-containing type I and homocitrulline-containing type II collagen telopeptides were 16 (22%) and 14 (19%). Most of the patients, who were seropositive for citrullinated peptides, showed binding in multiple assays. A total of 10 (14%) RA patients were positive for all the tested peptide pairs, while 28 (39%) of them had antibodies that contained overlapping specifities between citrulline and homocitrulline in the same peptide sequence.

Conclusions

Antibodies to both citrulline and homocitrulline containing type I and II collagen telopeptides can be found in sera of RA patients. These antibodies are not constant from one RA patient to another, but contain separate or overlapping specificities within the same peptide sequence varying between individuals. Our results suggest some relationship between citrulline and homocitrulline-recognizing antibodies, since homocitrulline antibodies exist mainly in individuals seropositive to anti-CCP and anti-MCV.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0515-z) contains supplementary material, which is available to authorized users.

Reactive oxygen species deficiency induces autoimmunity with type 1 interferon signature

AIMS

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by mutations in the phagocyte reactive oxygen species (ROS)-producing NOX2 enzyme complex and characterized by recurrent infections associated with hyperinflammatory and autoimmune manifestations. A translational, comparative analysis of CGD patients and the corresponding ROS-deficient Ncf1(m1J) mutated mouse model was performed to reveal the molecular pathways operating in NOX2 complex deficient inflammation.

RESULTS

A prominent type I interferon (IFN) response signature that was accompanied by elevated autoantibody levels was identified in both mice and humans lacking functional NOX2 complex. To further underline the systemic lupus erythematosus (SLE)-related autoimmune process, we show that naïve Ncf1(m1J) mutated mice, similar to SLE patients, suffer from inflammatory kidney disease with IgG and C3 deposits in the glomeruli. Expression analysis of germ-free Ncf1(m1J) mutated mice reproduced the type I IFN signature, enabling us to conclude that the upregulated signaling pathway is of endogenous origin.

INNOVATION

Our findings link the previously unexplained connection between ROS deficiency and increased susceptibility to autoimmunity by the discovery that activation of IFN signaling is a major pathway downstream of a deficient NOX2 complex in both mice and humans.

CONCLUSION

We conclude that the lack of phagocyte-derived oxidative burst is associated with spontaneous autoimmunity and linked with type I IFN signature in both mice and humans.

Automated immunoassays for the autoantibodies to carbamylated or citrullinated telopeptides of type I and II collagens

BACKGROUND

The aim of the study was to describe automated immunoassays for autoantibodies to homocitrulline or citrulline containing telopeptides of type I and II collagen in various disease categories in an early arthritis series.

METHODS

Serum samples were collected from 142 patients over 16 years of age with newly diagnosed inflammatory joint disease. All samples were analyzed with an automated inhibition chemiluminescence immunoassay (CLIA) using four different peptide pairs, each consisting of a biotinylated antigen and an inhibiting peptide. Assays were performed with an IDS-iSYS analyzer. Autoantibodies binding to homocitrulline and citrulline containing C-telopeptides of type I (HTELO-I, TELO-I) and type II collagens (HTELO-II, TELO-II) were analyzed.

RESULTS

The mean ratio of HTELO-I inhibition in seropositive and seronegative rheumatoid arthritis (RA) was 3.07 (95% CI 1.41-11.60), p=0.003, and in seropositive and seronegative undifferentiated arthritis (UA) 4.90 (1.85-14.49), p<0.001. The respective mean ratios in seropositive and seronegative RA and UA were in TELO-I 8.72 (3.68-58.01), p<0.001 and 3.13 (1.49-6.16), p=0.008, in HTELO-II 7.57 (3.18-56.60), p<0.001 and 2.97 (1.23-6.69), p=0.037, and in TELO-II 3.01 (1.30-9.51), p=0.002 and 3.64 (1.86-7.65), p=0.008. In reactive arthritis, ankylosing spondylitis, psoriatic arthritis and unspecified spondyloarthritis the inhibition levels were similar to those observed in seronegative RA or UA.

CONCLUSIONS

Autoantibodies binding to homocitrulline or citrulline containing telopeptides of type I and II collagen did not differ significantly. They were highest among patients with seropositive disease and they differentiated seropositive and seronegative arthritis.

Relatives without rheumatoid arthritis show reactivity to anti-citrullinated protein/peptide antibodies that are associated with arthritis-related traits: studies of the etiology of rheumatoid arthritis

OBJECTIVE

To examine reactivity to anti-citrullinated protein/peptide antibodies (ACPAs) and determine associations between ACPAs and other rheumatoid arthritis (RA)-related autoantibodies and clinically assessed swollen or tender joints in unaffected first-degree relatives of RA patients.

METHODS

Serum samples were obtained from first-degree relatives without RA according to the 1987 American College of Rheumatology (ACR) and the 2010 ACR/European League Against Rheumatism classification criteria. A bead-based assay was used to measure 16 separate ACPAs in sera from 111 antibody-positive first-degree relatives who were positive on at least 1 visit for any of 5 RA-related autoantibodies (rheumatoid factor [RF], anti-cyclic citrullinated peptide 2 [anti-CCP-2], and RF isotypes), and sera from 99 antibody-negative first-degree relatives who were never autoantibody positive. Cutoffs for positivity for each ACPA were determined using receiver operating characteristic curves derived from data on 200 RA patients and 98 blood donor controls, in which positivity for ≥9 ACPAs had 92% specificity and 62% sensitivity for RA. In first-degree relatives, ACPA reactivity was assessed, and associations between ACPAs (number positive, and positivity for ≥9 ACPAs) and RA-related characteristics were examined.

RESULTS

Fifty-seven percent of anti-CCP-2-positive first-degree relatives and 8% of anti-CCP-2- negative first-degree relatives were positive for ≥9 ACPAs. After adjusting for age, sex, ethnicity, and pack-years of smoking, an increasing number of ACPAs was directly associated with the presence of ≥1 tender joint on examination (odds ratio [OR] 1.18, 95% confidence interval [95% CI] 1.04-1.34), with the greatest risk of having ≥1 tender joint seen in first-degree relatives positive for ≥9 ACPAs (OR 5.00, 95% CI 1.37-18.18).

CONCLUSION

RA-free first-degree relatives (even those negative for RF and anti-CCP-2) demonstrate reactivity to multiple ACPAs, and the presence of an increasing number of ACPAs may be associated with signs of joint inflammation. Prospective evaluation of the relationship between these findings and the progression of classifiable RA is warranted.

Different amounts of protein-bound citrulline and homocitrulline in foot joint tissues of a patient with anti-citrullinated protein antibody positive erosive rheumatoid arthritis

Background

Antibodies binding to citrullinated proteins are a frequent finding in rheumatoid arthritis patients and may precede the onset of clinical symptoms several years. The antibodies are a predisposing factor for bone erosions but their origin is unknown. In this study we analyze in detail the levels of protein bound citrulline and homocitrulline in several tissue samples of a single erosive arthritic surgery patient.

Methods

Serum antibodies binding to CCP, MCV and citrulline- or homocitrulline-containing type I and II collagen carboxytelopeptides were measured. Tissue samples of a single RA patient, taken in two separate operations performed with two-year time span were hydrolyzed and analyzed for citrulline and homocitrulline content by HPLC.

Results

Protein-bound citrulline and homocitrulline were found in several joint tissues of a RA patient with ACPA-positive erosive disease. The amount of homocitrulline stayed relatively constant between the different tissues. The amount of citrulline in erosive tissue was 3-times higher than in non-erosive tissue in the first operation. In the samples of the second operation 3-4-times higher mean amounts of citrulline were found in two out of the six tissues investigated.

Conclusions

Homocitrulline is present in rheumatoid nodule together with citrulline. There is more variation in the amount of citrulline than in the amount of homocitrulline between the tissues. The tissue sample containing the most citrulline was the most erosive.

The interaction between HLA shared epitope alleles and smoking and its contribution to autoimmunity against several citrullinated antigens

OBJECTIVE

Recent data suggest that a gene-environment interaction between smoking and the HLA shared epitope alleles plays a role in shaping the autoimmune reaction to specific citrullinated antigens. This study was undertaken to determine the effects of HLA shared epitope alleles and tobacco exposure on the immune response against various citrullinated antigens. These associations were analyzed in the anti-citrullinated protein antibody (ACPA)-positive stratum to control for the possibility that the associations found are explained by the known interaction between HLA shared epitope alleles and tobacco exposure on ACPA status.

METHODS

In 661 patients with rheumatoid arthritis, reactivity against several citrullinated antigens from vimentin, fibrinogen, enolase, and myelin basic protein was determined by enzyme-linked immunosorbent assay. The effects of the HLA shared epitope alleles and tobacco exposure were assessed by logistic regression analysis. Biologic interaction was analyzed by investigating whether the effects of the risk factors combined exhibited departure from additivity.

RESULTS

A significant interaction between tobacco exposure and HLA shared epitope alleles was found for the presence of ACPA as reported previously. When these interaction effects were studied for several ACPA "fine specificities," significant interactions were noted for several citrullinated peptides. However, these interactions were not present after stratification for ACPA status, indicating that the interaction between tobacco exposure and HLA shared epitope alleles influences autoimmunity not to specific citrullinated antigens, but rather to ACPA development.

CONCLUSION

Our data indicate that the gene-environment interaction between HLA shared epitope alleles and smoking does not appear to shape the reactivity of the ACPA response. These data suggest that smoking promotes nonspecific citrullination rather than citrullination of specific antigens.

Anticitrulline antibodies can be caused by homocitrulline-containing proteins in rabbits

OBJECTIVE

To clarify the possible roles of protein-bound homocitrulline in causing an antibody response to citrulline and as a confounding factor in citrulline detection assays.

METHODS

Native, carbamoylated, and citrullinated albumins were used for testing the specificity of commercial antibodies against modified citrulline by Western blot. Rabbits were immunized with human albumin and/or bone type I collagen, both of which were treated with cyanate to produce homocitrulline, or with citrullinated synthetic telopeptide of type I collagen. These antisera were tested for binding to cyclic citrullinated peptide 2 (CCP-2), mutated citrullinated vimentin, and type I or II collagen telopeptides containing either citrulline or homocitrulline.

RESULTS

Commercial antibodies that had been considered to be specific for chemically modified citrulline were found to recognize both homocitrulline- and citrulline-containing albumins. The rabbits immunized with proteins containing homocitrulline produced high-affinity antibodies against CCP-2 and, to a lesser extent, against mutated citrullinated vimentin. The antisera also bound homocitrulline-containing collagen telopeptides and, less strongly, citrulline-containing telopeptides.

CONCLUSION

Our findings demonstrate that homocitrulline, which is a structural analog of citrulline (longer by 1 carbon, and readily formed in the body), can be involved in raising citrulline-recognizing antibodies in experimental animals and can cause false-positive reactions in assays for citrulline.

Early inflammatory arthritis versus rheumatoid arthritis

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) has started to be perceived as a potentially curable condition with early, aggressive use of disease-modifying antirheumatic drugs. We review the pathophysiological concepts of RA development, the technological advances used to estimate the individual risk of progression to RA, and the impact of antirheumatic therapy for patients presenting with early inflammatory arthritis.

RECENT FINDINGS

The finding of a strong gene-environment interaction has modified our concepts of RA pathogenesis and opened new opportunities for disease prevention and therapeutic interventions. Anticyclic citrullinated antibodies and prediction rules have improved our ability to estimate the risk of progression to RA in individual patients presenting with early inflammatory arthritis. In patients at high risk of developing RA, results from trials suggest that treating these patients with potent antirheumatic therapies may slow the progression from early inflammatory arthritis to definite RA and inhibit the progression of joint damage.

SUMMARY

Early inflammatory arthritis is a critical period of the disease, during which therapy may have a durable effect and change the natural course of the condition. Physicians need to assess the individual risk of progression to RA in patients presenting with early inflammatory arthritis and consider initiating early disease-modifying antirheumatic drug therapy in patients at high risk of developing 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.