Primary SARS-CoV-2 infection in patients with immune-mediated inflammatory diseases: long-term humoral immune responses and effects on disease activity.

BACKGROUND: Patients with immune-mediated inflammatory diseases (IMIDs) on immunosuppressants (ISPs) may have impaired long-term humoral immune responses and increased disease activity after SARS-CoV-2 infection. We aimed to investigate long-term humoral immune responses against SARS-CoV-2 and increased disease activity after a primary SARS-CoV-2 infection in unvaccinated IMID patients on ISPs. METHODS: IMID patients on active treatment with ISPs and controls (i.e. IMID patients not on ISP and healthy controls) with a confirmed SARS-CoV-2 infection before first vaccination were included from an ongoing prospective cohort study (T2B! study). Clinical data on infections and increased disease activity were registered using electronic surveys and health records. A serum sample was collected before first vaccination to measure SARS-CoV-2 anti-receptor-binding domain (RBD) antibodies. RESULTS: In total, 193 IMID patients on ISP and 113 controls were included. Serum samples from 185 participants were available, with a median time of 173 days between infection and sample collection. The rate of seropositive IMID patients on ISPs was 78% compared to 100% in controls (p < 0.001). Seropositivity rates were lowest in patients on anti-CD20 (40.0%) and anti-tumor necrosis factor (TNF) agents (60.5%), as compared to other ISPs (p < 0.001 and p < 0.001, respectively). Increased disease activity after infection was reported by 68 of 260 patients (26.2%; 95% CI 21.2-31.8%), leading to ISP intensification in 6 out of these 68 patients (8.8%). CONCLUSION: IMID patients using ISPs showed reduced long-term humoral immune responses after primary SARS-CoV-2 infection, which was mainly attributed to treatment with anti-CD20 and anti-TNF agents. Increased disease activity after SARS-CoV-2 infection was reported commonly, but was mostly mild. TRIAL REGISTRATION: NL74974.018.20, Trial ID: NL8900. Registered on 9 September 2020.

Geo-epidemiology of autoantibodies in rheumatoid arthritis: comparison between four ethnically diverse populations.

BACKGROUND: Rheumatoid arthritis (RA) occurs across the globe in different ethnic populations. Most RA patients harbor anti-modified protein antibodies (AMPA); however, it is unclear whether differences exist in autoantibody responses at different geographic locations and between different ethnic groups, which could provide new clues regarding factors underlying autoantibody development. We therefore investigated AMPA prevalence and association with HLA DRB1 alleles and smoking in four ethnically diverse populations on four different continents. METHODS: Anti-carbamylated (anti-CarP), anti-malondialdehyde acetaldehyde (anti-MAA), and anti-acetylated protein antibodies (anti-AcVim) IgG were determined in anti-citrullinated protein antibody-positive Dutch (NL, n = 103), Japanese (JP, n = 174), First Nations Peoples in Canada (FN, n = 100), and black South African (SA, n = 67) RA patients. Ethnicity-matched local healthy controls were used to calculate cut-offs. Risk factors associated with AMPA seropositivity in each cohort were identified using logistic regression. RESULTS: Median AMPA levels were higher in First Nations Peoples in Canada and especially South African patients, as reflected by percentage seropositivity: NL, JP, FN, and SA: anti-CarP: 47%, 43%, 58%, and 76% (p < 0.001); anti-MAA: 29%, 22%, 29%, and 53% (p < 0.001); and anti-AcVim: 20%, 17%, 38%, and 28% (p < 0.001). Total IgG levels also differed markedly, and when autoantibody levels were normalized to total IgG, differences between cohorts became less pronounced. Although there were some associations with AMPA and HLA risk alleles and smoking, none was consistent across all four cohorts. CONCLUSIONS: AMPA against various post-translational modifications could consistently be detected on different continents across ethnically diverse RA populations. Differences in AMPA levels corresponded to differences in total serum IgG levels. This suggests that, despite differences in risk factors, a common pathway may be involved in AMPA development across geographic locations and ethnicities.

Differences in IgG autoantibody Fab glycosylation across autoimmune diseases.

BACKGROUND: Increased prevalence of autoantibody Fab glycosylation has been demonstrated for several autoimmune diseases. OBJECTIVES: To study whether elevated Fab glycosylation is a common feature of autoimmunity, this study investigated Fab glycosylation levels on serum IgG and its subclasses for autoantibodies associated with a range of different B cell-mediated autoimmune diseases, including rheumatoid arthritis, myasthenia gravis subtypes, pemphigus vulgaris, antineutrophil cytoplasmic antibody-associated vasculitis, systemic lupus erythematosus, anti-glomerular basement membrane glomerulonephritis, thrombotic thrombocytopenic purpura, and Guillain-Barré syndrome. METHODS: The level of Fab glycosylated IgG antibodies was assessed by lectin affinity chromatography and autoantigen-specific immunoassays. RESULTS: In 6 of 10 autoantibody responses, in 5 of 8 diseases, the investigators found increased levels of Fab glycosylation on IgG autoantibodies that varied from 86% in rheumatoid arthritis to 26% in systemic lupus erythematosus. Elevated autoantibody Fab glycosylation was not restricted to IgG4, which is known to be prone to Fab glycosylation, but was also present in IgG1. When autoimmune diseases with a chronic disease course were compared with more acute autoimmune illnesses, increased Fab glycosylation was restricted to the chronic diseases. As a proxy for chronic autoantigen exposure, the investigators determined Fab glycosylation levels on antibodies to common latent herpes viruses, as well as to glycoprotein 120 in individuals who are chronically HIV-1-infected. Immunity to these viral antigens was not associated with increased Fab glycosylation levels, indicating that chronic antigen-stimulation as such does not lead to increased Fab glycosylation levels. CONCLUSIONS: These data indicate that in chronic but not acute B cell-mediated autoimmune diseases, disease-specific autoantibodies are enriched for Fab glycans.

IgG Fab Glycans Hinder FcRn-Mediated Placental Transport.

Abs can be glycosylated in both their Fc and Fab regions with marked effects on Ab function and binding. High levels of IgG Fab glycosylation are associated with malignant and autoimmune conditions, exemplified by rheumatoid arthritis and highly Fab-glycosylated (∼90%) anti-citrullinated protein Abs (ACPAs). Important properties of IgG, such as long half-life and placental transport, are facilitated by the human neonatal Fc receptor (hFcRn). Although it is known that glycosylation of Abs can affect binding to Fc receptors, little is known on the impact of IgG Fab glycosylation on hFcRn binding and transplacental transport. Therefore, we analyzed the interaction between hFcRn and IgG with and without Fab glycans in vitro with various methods as well as in vivo by studying placental transfer of Fab-glycosylated Abs from mothers to newborns. No effect of Fab glycosylation on IgG binding to hFcRn was found by surface plasmon resonance and hFcRn affinity chromatography. In contrast, studies in a cell membrane context revealed that Fab glycans negatively impacted IgG-hFcRn interaction. In line with this, we found that Fab-glycosylated IgGs were transported ∼20% less efficiently across the placenta. This appeared to be a general phenomenon, observed for ACPAs, non-ACPAs, as well as total IgG in rheumatoid arthritis patients and healthy controls. Our results suggest that, in a cellular context, Fab glycans inhibit IgG-hFcRn interaction and thus negatively affect the transplacental transfer of IgG. As Fab-glycosylated Abs are frequently associated with autoimmune and malignant disorders and may be potentially harmful, this might encompass a regulatory mechanism, limiting the half-life and transport of such Abs.

In rheumatoid arthritis patients, total IgA1 and IgA2 levels are elevated: implications for the mucosal origin hypothesis.

OBJECTIVE: Mucosal initiated immune responses may be involved in the pathophysiology of RA. The most abundant immunoglobulin at mucosal surfaces is IgA, of which two subclasses exist: IgA1 and IgA2. IgA2 is mainly present at mucosal sites and has been ascribed pro-inflammatory properties. As IgA subclasses might provide insights into mucosal involvement and pro-inflammatory mechanisms, we investigated IgA responses in sera of RA patients. METHODS: In two cohorts of RA patients, the EAC and IMPROVED, total IgA1 and IgA2 were measured by ELISA. Furthermore, IgA subclass levels of RF and anti-citrullinated protein antibodies (anti-CCP2) were determined. The association of these IgA subclass levels with CRP and smoking was investigated. RESULTS: Total IgA1 and IgA2 were increased in RA patients compared with healthy donors in both cohorts. This increase was more pronounced in seropositive RA vs seronegative RA. For RF and anti-CCP2, both IgA1 and IgA2 could be detected. No strong associations were found between IgA subclasses (total, RF and anti-CCP2) and CRP. In smoking RA patients, a trend towards a selective increase in total IgA2 and RF IgA1 and IgA2 was observed. CONCLUSION: RA patients have raised IgA1 and IgA2 levels. No shift towards IgA2 was observed, indicating that the increase in total IgA is not due to translocation of mucosal IgA into the bloodstream. However, mucosal inflammation might play a role, given the association between smoking and total IgA2 levels. Despite its pro-inflammatory properties, IgA2 does not associate strongly with pro-inflammatory markers in RA patients.

Autoantibody Development under Treatment with Immune-Checkpoint Inhibitors.

Immune-checkpoint inhibitors (ICIs) activate the immune system to assault cancer cells in a manner that is not antigen specific. We hypothesized that tolerance may also be broken to autoantigens, resulting in autoantibody formation, which could be associated with immune-related adverse events (irAEs) and antitumor efficacy. Twenty-three common clinical autoantibodies in pre- and posttreatment sera from 133 ipilimumab-treated melanoma patients were determined, and their development linked to the occurrence of irAEs, best overall response, and survival. Autoantibodies developed in 19.2% (19/99) of patients who were autoantibody-negative pretreatment. A nonsignificant association was observed between development of any autoantibodies and any irAEs [OR, 2.92; 95% confidence interval (CI) 0.85-10.01]. Patients with antithyroid antibodies after ipilimumab had significantly more thyroid dysfunction under subsequent anti-PD-1 therapy: 7/11 (54.6%) patients with antithyroid antibodies after ipilimumab developed thyroid dysfunction under anti-PD1 versus 7/49 (14.3%) patients without antibodies (OR, 9.96; 95% CI, 1.94-51.1). Patients who developed autoantibodies showed a trend for better survival (HR for all-cause death: 0.66; 95% CI, 0.34-1.26) and therapy response (OR, 2.64; 95% CI, 0.85-8.16). We conclude that autoantibodies develop under ipilimumab treatment and could be a potential marker of ICI toxicity and efficacy.

Smoking is associated with the concurrent presence of multiple autoantibodies in rheumatoid arthritis rather than with anti-citrullinated protein antibodies per se: a multicenter cohort study.

BACKGROUND: The contribution of smoking to rheumatoid arthritis (RA) is hypothesized to be mediated through formation of anti-citrullinated protein antibodies (ACPA). In RA, however, autoantibodies such as ACPA, rheumatoid factor (RF), and anti-carbamylated protein antibodies (anti-CarP) often occur together, and it is thus unclear whether smoking is specifically associated with some autoantibodies rather than others. We therefore investigated whether smoking is only associated with ACPA or with the presence of multiple RA-related autoantibodies. METHODS: A population-based Japanese cohort (n = 9575) was used to investigate the association of smoking with RF and anti-cyclic citrullinated peptide antibodies (anti-CCP2) in individuals without RA. Furthermore, RA patients fulfilling the 1987 criteria from three early arthritis cohorts from the Netherlands (n = 678), the United Kingdom (n = 761), and Sweden (n = 795) were used. Data on smoking, RF, anti-CCP2, and anti-CarP were available. A total score of autoantibodies was calculated, and odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by logistic regression. RESULTS: In the population-based non-RA cohort, no association was found between smoking and one autoantibody (RF or anti-CCP2), but smoking was associated with double-autoantibody positivity (OR 2.95, 95% CI 1.32-6.58). In RA patients, there was no association between smoking and the presence of one autoantibody (OR 0.99, 95% CI 0.78-1.26), but smoking was associated with double-autoantibody positivity (OR 1.32, 95% CI 1.04-1.68) and triple-autoantibody positivity (OR 2.05, 95% CI 1.53-2.73). CONCLUSIONS: Smoking is associated with the concurrent presence of multiple RA-associated autoantibodies rather than just ACPA. This indicates that smoking is a risk factor for breaking tolerance to multiple autoantigens in RA.

An investigation of the added value of an ACPA multiplex assay in an early rheumatoid arthritis setting.

INTRODUCTION: Recently, arrays have become available that allow the simultaneous analysis of several anti-citrullinated protein antibody (ACPA) reactivities using distinct citrullinated peptides. Such assays are designed for exploratory studies. The interpretation of positive antibody reactivities can best be made if the diagnostic and prognostic value of a multiplex array in an early arthritis setting is known and if the multiplex-positive patients who are negative according to three commonly used commercial ACPA assays are characterized. METHODS: Using Thermo Scientific's ImmunoCap ISAC (Immuno Solid-phase Allergen Chip) system, a multiplexed array that determines reactivities to 11 citrullinated peptides, we analysed serum/plasma of 195 healthy controls and 1282 early arthritis patients from two independent cohorts: the Leiden Early Arthritis Clinic (n = 1013) and the IMPROVED (n = 269) cohort. Findings were compared with results primarily of the anti-citrullinated cyclic peptide 2 (anti-CCP-2) assay but also with anti- CCP-3 and anti-mutated citrullinated vimentin (anti-MCV) assays. The associations between ACPA reactivities and patient characteristics, risk factors (shared epitope, smoking) and disease outcomes (progression of undifferentiated arthritis to rheumatoid arthritis (RA) and severity of joint destruction) were assessed. RESULTS: Thirty-one percent of anti-CCP-2-negative RA patients displayed reactivity toward citrullinated peptides in the multiplex assay. These patients had a positive signal toward a more restricted peptide repertoire than anti-CCP-2-positive RA patients (median of 1 versus 5). Within anti-CCP-2-negative patients, ACPA reactivity as detected by multiplex array was not significantly associated with known risk factors or clinical or prognostic parameters. The frequency of sera from anti-CCP-2-negative RA patients who were positive for the multiplexed peptides was comparable to the frequency in non-RA arthritic patients (27 %). CONCLUSIONS: Additive citrulline peptide reactivities detected by the current multiplex system did not reach significant power to be RA-specific. The presence of residual citrulline reactivities detected by this multiplex system in arthritis patients who are negative in commercial ACPA assays needs to be interpreted with caution.

HLA and anti-citrullinated protein antibodies: Building blocks in RA.

Antibodies against citrullinated proteins (ACPAs) are specific for rheumatoid arthritis (RA). ACPA-positive RA is a chronic inflammatory disease resulting from the complex interaction between genetic (mainly HLA class II genes) and environmental factors (mainly smoking). Recent findings have offered new insights into where, when and how anti-citrulline immunity develops. Some studies have found that a mucosal site, such as the lungs, may function as the initiating site for the immune response against citrullinated proteins, in line with the known association between smoking and ACPA. Other studies, focusing rather on the HLA associations, have suggested that cross-reactivity between microbial sequences and citrullinated self-proteins may lead to ACPA formation. Once ACPAs have developed, they can circulate throughout the body and upon reaching the joints exert direct pathogenic effects themselves. ACPAs can target first the bone compartment of the joints to activate osteoclasts and release interleukin (IL)-8 that in turn will promote bone loss and pain-like behaviour. In the current review, we will present the current understanding of the genetic associations in RA contributing to ACPA occurrence and offer insight in the latest findings explaining how and why autoimmunity generated in the lungs of genetically susceptible hosts might lead to chronic inflammation in the joints.

Anti-CarP antibodies in two large cohorts of patients with rheumatoid arthritis and their relationship to genetic risk factors, cigarette smoking and other autoantibodies.

INTRODUCTION: In rheumatoid arthritis (RA), several genetic risk factors and smoking are strongly associated with the presence of anticitrullinated protein antibodies (ACPA), while much less is known about risk factors for ACPA-negative RA. Antibodies against carbamylated proteins (anti-CarP) have been described in both ACPA-positive and ACPA-negative RA patients. In this study, we have analysed the relationships among anti-CarP antibodies, ACPA, genetic risk factors (HLA-DRB1 alleles and PTPN22) and smoking in RA. METHODS: Presence of antibodies to carbamylated fetal calf serum (CarP-FCS) and fibrinogen (CarP-Fib) was determined by inhouse ELISAs among RA cases in the Leiden Early Arthritis Clinic (n=846) and in the Swedish Epidemiological Investigation of Rheumatoid Arthritis (n=1985) cohorts. ORs for associations with different HLA-DRB1 alleles, PTPN22 genotypes and smoking were calculated separately for each cohort as well as in meta-analysis in RA subsets defined by the presence/absence of anti-CarP and anticyclic citrullinated peptide (anti-CCP) antibodies. RESULTS: In both cohorts, anti-CarP antibody positivity was mainly detected in the anti-CCP-positive population (49%-73%), but also in the anti-CCP-negative population (8%-14%). No associations between anti-CarP antibodies and HLA-DRB1 shared epitope alleles could be identified, while there were data to support an association between anti-CarP-FCS and HLA-DRB1*03. Further analyses did not reveal any specific associations of anti-CarP antibodies with other HLA-DRB1 alleles, PTPN22 genotypes or smoking. CONCLUSIONS: Anti-CarP antibodies were present in both ACPA-positive and ACPA-negative RA. There were no significant associations among anti-CarP antibodies and HLA-DRB1 alleles, PTPN22 or smoking. These data suggest that different biological mechanisms may underlie anti-CarP versus anti-CCP antibody formation.

Patients with early arthritis consume less alcohol than controls, regardless of the type of arthritis.

OBJECTIVES: There are conflicting reports concerning the association between alcohol consumption and RA. We performed a case-control study to investigate the association of alcohol consumption with RA as well as with other forms of arthritis. To assess whether alcohol consumption affects long-term disease outcome, we also investigated its association with radiographic progression and sustained drug-free remission in RA. METHODS: Patients with arthritis and various diagnoses including RA, OA, ReA, SpA and PsA were compared with 5868 controls from the general population. The association of disease with alcohol consumption was analysed by logistic regression analysis. RESULTS: Alcohol consumption was inversely associated with not only RA [odds ratio (OR) 0.28, 95% CI 0.23, 0.35] but also OA (OR 0.31, 95% CI 0.16, 0.62) and other forms of arthritis (OR 0.34, 95% CI 0.24, 0.48). A higher degree of systemic inflammation, reflected by the ESR and CRP level, was associated with a smaller proportion of patients consuming alcohol. There was no dose-response relationship between the amount of alcohol consumed and the presence of arthritis. The extent of joint destruction and the rate of sustained drug-free remission were not affected by alcohol consumption. CONCLUSION: Arthritis patients report less alcohol consumption than controls, regardless of the type of arthritis. This suggests that alcohol may either protect against different kinds of arthritis or that the inverse association between alcohol and arthritis may be secondary to disease development, with arthritis patients being less inclined to consume alcohol due to their decreased general well-being.

Sustained drug-free remission in rheumatoid arthritis after DAS-driven or non-DAS-driven therapy: a comparison of two cohort studies.

OBJECTIVES: To compare the prevalence of and predictors for sustained drug-free remission in two cohorts of patients with recent-onset RA treated with DAS-driven therapy or non-DAS-driven therapy. METHODS: Sustained drug-free remission was assessed after 5 years of follow-up in 508 patients treated with DAS-driven therapy (DAS ≤ 2.4) in a randomized treatment cohort, and in 424 patients who received non-DAS-driven therapy in a prospective inception cohort. The design of the DAS-driven cohort required systematic joint assessments with DAS-driven restart of therapy. Predictors for remission were identified by univariable and multivariable logistic regression in each cohort separately and in a combined multivariate logistic regression analysis corrected for propensity scores, including a sensitivity analysis on patients receiving initial monotherapy. RESULTS: Patients in the DAS-driven cohort had more active disease at baseline, but the prevalence of sustained drug-free remission was similar after DAS-driven (9.8%) and non-DAS-driven therapy (10.6%). Among patients with ACPA, drug-free remission was more frequently achieved after DAS-driven than after non-DAS-driven therapy (5.4 vs. 2.1%, OR = 2.68, 95% CI 0.97, 7.43). Absence of ACPA and short symptom duration were independent predictors for sustained drug-free remission in both cohorts. Initial treatment choice and inclusion period were not predictive. The sensitivity analysis yielded comparable results. CONCLUSION: Retrospectively comparing a DAS-driven to a non-DAS-driven therapy cohort, the occurrence and predictors of sustained drug-free remission were similar. The DAS-driven cohort had a more unfavourable prognosis. DAS-driven therapy may improve the chance of sustained drug-free remission in ACPA-positive patients with recent-onset RA.

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.

Genetics of ACPA-positive rheumatoid arthritis: the beginning of the end?

Heritability is a measure for the contribution of genetic variation to the variation in liability to disease and for rheumatoid arthritis (RA) had previously been estimated to be about 60%. This has been recently confirmed and could show that the heritability of anti-citrullinated protein autoantibody (ACPA)-positive and ACPA-negative RA is similar. Apart from gender, the main known genetic factor is HLA, and its contribution to genetic variation has previously been estimated as 37% but recent studies indicate that this figure may be too high. HLA-linked genes, and in particular the HLA-DRB1 SE alleles, predispose much more strongly to ACPA-positive than to ACPA-negative RA. The same is true for the protective effect of DERAA-positive DRB1 alleles. It has been calculated that the contribution of the protective and predisposing HLA alleles to genetic variance is about 40% for ACPA-positive and 2% for ACPA-negative RA. A meta-analysis indicated that the protective effect may be confined to the HLA-DRB1*1301 allele. The search for non-HLA genes contributing to the genetic variation in RA susceptibility has implicated about 30 other loci/genes. The OR of the associations with these non-HLA polymorphisms is considerably lower than the ORs of sex and HLA as is their contribution to the genetic variation-namely, altogether only about 5%. This means that known genetic factors do not explain much more than 50% of the genetic variance of ACPA-positive RA. Until recently, the only established non-genetic factor contributing to RA susceptibility was smoking. It has recently been shown that non-inherited maternal HLA-DRB1 DERAA-positive antigens (NIMA) should be added to the environmental factors affecting RA susceptibility.

Antibodies to porphyromonas gingivalis are associated with anticitrullinated protein antibodies in patients with rheumatoid arthritis and their relatives.

OBJECTIVE: Anticitrullinated protein antibodies (ACPA) are relatively specific for rheumatoid arthritis (RA), and predate disease. The oral pathogen Porphyromonas gingivalis may play a role in breaking immune tolerance to citrullinated antigens. We studied a cohort of patients with RA and their relatives looking for associations between anti-P. gingivalis antibodies and ACPA. METHODS: Patients with RA (n = 82) and their relatives (n = 205) from a North American Native (NAN) population were studied, along with 47 NAN and 60 non-NAN controls. IgM and IgA rheumatoid factor (RF) were tested by nephelometry and ELISA. Second-generation anticyclic citrullinated peptide (anti-CCP2) isotypes and IgG anti-P. gingivalis lipopolysaccharides were tested by ELISA. HLA-DRB1 typing was performed by sequencing. Oral hygiene and smoking habits were assessed by questionnaires. RESULTS: Autoantibody frequency in patients with RA and relatives: ACPA 91% vs 19%, respectively; IgM RF 82% vs 17%; IgA RF 48% vs 22%. Anti-P. gingivalis levels were higher in patients with RA compared to relatives and controls (p = 0.005) and higher in ACPA-positive patients with RA than in ACPA-negative patients with RA (p = 0.04) and relatives (p < 0.001), but comparable in RF-positive and RF-negative patients and relatives. Poor oral hygiene and smoking were prevalent, but with no clear association with autoantibodies. Relatives with 2 shared-epitope alleles were more likely to be ACPA-positive (OR 2.5, p = 0.02). CONCLUSION: In a genetically predisposed population of NAN patients with RA and their relatives, anti-P. gingivalis antibodies were associated with ACPA. These findings suggest that immune responses to P. gingivalis may be involved in breaking immune tolerance to citrullinated antigens.

Prevalence of and predictive factors for sustained disease-modifying antirheumatic drug-free remission in rheumatoid arthritis: results from two large early arthritis cohorts.

OBJECTIVE: Remission has become an attainable goal of rheumatoid arthritis (RA) treatment, especially since the advent of biologic antirheumatic therapy. Because little is known about patients who achieve disease remission with conventional treatment, we used 2 large independent inception cohorts to study the prevalence of and predictive factors for disease-modifying antirheumatic drug (DMARD)-free sustained remission after treatment with conventional therapy. METHODS: Remission of disease was assessed in 454 patients from the Leiden Early Arthritis Clinic (EAC) and in 895 patients from the British Early Rheumatoid Arthritis Study (ERAS) who fulfilled the American College of Rheumatology 1987 revised criteria for the classification of RA and were treated with conventional therapy. Sustained DMARD-free remission was defined as fulfilling the following criteria for at least 1 year: 1) no current DMARD use, 2) no swollen joints, and 3) classification as DMARD-free remission by the patient's rheumatologist. Predictive factors were identified by Cox regression analysis. RESULTS: Sustained DMARD-free remission was achieved by 68 of 454 patients (15.0%) in the Leiden EAC and by 84 of 895 patients (9.4%) in the ERAS. Six factors were associated with sustained DMARD-free remission in both cohorts: acute onset, short symptom duration before inclusion, not smoking, little radiographic damage at baseline, absence of IgM rheumatoid factor (IgM-RF), and absence of HLA shared epitope alleles. In the ERAS, low disease activity at baseline was also predictive of remission. Multivariate analyses revealed symptom duration and the absence of autoantibodies (anti-cyclic citrullinated peptide 2 and IgM-RF) as independent predictors. CONCLUSION: Sustained DMARD-free remission in RA patients treated with conventional therapy is not uncommon. Symptom duration at presentation and the absence of autoantibodies are associated with sustained DMARD-free remission.

CTLA-4 regulates cell cycle progression during a primary immune response.

Engagement of CTLA-4 is critical for inhibiting T cell immune responses. Recent studies have shown that CTLA-4 plays a key role in regulating peripheral T cell tolerance. It has been suggested that one mechanism by which CTLA-4 performs this function is by regulating cell cycle progression. Here, we investigate in depth the role of CTLA-4 in regulating cell cycle progression in naive T cells by comparing the immune responses in the absence or presence of CTLA-4. In the absence of CLTA-4, T cells exhibit marked increases in T cell proliferation, IL-2 mRNA and protein secretion, and cells cycling in the S and G2-M phase. Analyses of cyclins, cyclin-dependent kinases, and cell cycle inhibitors involved in the transition from the G1 to S phase reveal that cell cycle progression is prolonged in the absence of CTLA-4. This is due to the early exit from the G1 phase, entry into the S phase, and prolonged S phase period. Re-expression of the cell cycle inhibitor p27(kip1) is delayed in the absence of CTLA-4. These studies demonstrate that the B7 : CTLA-4 pathway exerts its major effects on T cell immune responses via regulation of the cell cycle.