A predictive model for progression to clinical arthritis in at-risk individuals with arthralgia based on lymphocyte subsets and ACPA.

BACKGROUND: The presence of ACPA significantly increases the risk of developing RA. Dysregulation of lymphocyte subpopulations was previously described in RA. Our objective was to propose the predictive model for progression to clinical arthritis based on peripheral lymphocyte subsets and ACPA in individuals who are at risk of RA. METHODS: Our study included 207 at-risk individuals defined by the presence of arthralgias and either additional ACPA positivity or meeting the EULAR definition for clinically suspect arthralgia. For the construction of predictive models, 153 individuals with symptom duration ≥12 months who have not yet progressed to arthritis were included. The lymphocyte subsets were evaluated using flow cytometry and anti-CCP using ELISA. RESULTS: Out of all individuals with arthralgia, 41 progressed to arthritis. A logistic regression model with baseline peripheral blood lymphocyte subpopulations and ACPA as predictors was constructed. The resulting predictive model showed that high anti-CCP IgG, higher percentage of CD4+ T cells, and lower percentage of T and NK cells increased the probability of arthritis development. Moreover, the proposed classification decision tree showed that individuals having both high anti-CCP IgG and low NK cells have the highest risk of developing arthritis. CONCLUSIONS: We propose a predictive model based on baseline levels of lymphocyte subpopulations and ACPA to identify individuals with arthralgia with the highest risk of progression to clinical arthritis. The final model includes T cells and NK cells, which are involved in the pathogenesis of RA. This preliminary model requires further validation in larger at-risk cohorts.

Anti-citrullinated protein antibody profiles predict changes in disease activity in patients with rheumatoid arthritis initiating biologics.

OBJECTIVES: To determine whether an expanded antigen-specific ACPA profile predicts changes in disease activity in patients with RA initiating biologics. METHODS: The study included participants from a prospective, non-randomized, observational RA cohort. For this sub-study, treatment groups of interest included biologic-naïve initiating anti-TNF, biologic-exposed initiating non-TNF, and biologic-naïve initiating abatacept. ACPAs to 25 citrullinated peptides were measured using banked enrolment serum. Principal component analysis (PCA) was performed and associations of resulting principal component (PC) scores (in quartiles) and anti-CCP3 antibody (≤15, 16-250 or >250 U/ml) with EULAR (good/moderate/none) treatment response at 6 months were examined using adjusted ordinal regression models. RESULTS: Participants (n = 1092) had a mean age of 57 (13) years and 79% were women. At 6 months, 68.5% achieved a moderate/good EULAR response. There were three PCs that cumulatively explained 70% of variation in ACPA values. In models including the three components and anti-CCP3 antibody category, only PC1 and PC2 were associated with treatment response. The highest quartile for PC1 (odds ratio [OR] 1.76; 95% CI: 1.22, 2.53) and for PC2 (OR 1.74; 95% CI: 1.23, 2.46) were associated with treatment response after multivariable adjustment. There was no evidence of interaction between PCs and treatment group in EULAR responses (P-value for interaction >0.1). CONCLUSION: An expanded ACPA profile appears to be more strongly associated with biologic treatment response in RA than commercially available anti-CCP3 antibody levels. However, further enhancements to PCA will be needed to effectively prioritize between different biologics available for the treatment of RA.

CCCTC-binding factor: the specific transcription factor of ß-galactoside α-2,6-sialyltransferase 1 that upregulates the sialylation of anti-citrullinated protein antibodies in rheumatoid arthritis.

OBJECTIVE: Sialylation of the crystallizable fragment (Fc) of ACPAs, which is catalysed by ß-galactoside α-2,6-sialyltransferase 1 (ST6GAL1) could attenuate inflammation of RA. In this study, we screened the transcription factor of ST6GAL1 and elucidated the mechanism of transcriptionally upregulating sialylation of ACPAs in B cells to explore its role in the progression of RA. METHODS: Transcription factors interacting with the P2 promoter of ST6GAL1 were screened by DNA pull-down and liquid chromatography with tandem mass spectrometry (LC-MS/MS), and verified by chromatin immunoprecipitation (ChIP), dual luciferase reporter assay and electrophoretic mobility shift assay (EMSA). The function of the CCCTC-binding factor (CTCF) on the expression of ST6GAL1 and the inflammatory effect of ACPAs were verified by knocking down and overexpressing CTCF in B cells. The CIA model was constructed from B cell-specific CTCF knockout mice to explore the effect of CTCF on arthritis progression. RESULTS: We observed that the levels of ST6GAL1 and ACPAs sialylation decreased in the serum of RA patients and were negatively correlated with DAS28 scores. Subsequently, CTCF was screened and verified as the transcription factor interacting with the P2 promoter of ST6GAL1, which enhances the sialylation of ACPAs, thus weakening the inflammatory activity of ACPAs. Furthermore, the above results were also verified in the CIA model constructed from B cell-specific CTCF knockout mice. CONCLUSION: CCCTC-binding factor is the specific transcription factor of ß-galactoside α-2,6-sialyltransferase 1 in B cells that upregulates the sialylation of ACPAs in RA and attenuates the disease progression.

Predictors of the effectiveness to first-line CTLA4-Ig in patients with rheumatoid arthritis: the FIRST registry.

OBJECTIVES: This study aimed to elucidate which bio-naïve patients with rheumatoid arthritis (RA) are suitable for treatment with CTLA4-Ig. METHODS: This study enrolled 953 patients with RA who were administered their first biological disease-modifying antirheumatic drug (CTLA4-Ig, n = 328; tumour necrosis factor inhibitor [TNFi], n = 625) from July 2013 to August 2022. The primary outcome was the Clinical Disease Activity Index (CDAI) remission rate at week 24 in each group, adjusted using Propensity Score-based Inverse Probability of Treatment Weighting (PS-IPTW). RESULTS: After minimizing selection bias using PS-IPTW, the CDAI remission showed no significant difference between the CTLA4-Ig and TNFi groups (p= 0.464). Multivariable logistic regression analysis identified low baseline Health Assessment Questionnaire-Disability Index (HAQ-DI) scores as a contributing factor to the CDAI remission rate at week 24 in both groups, along with high baseline anti-citrullinated peptide antibody (ACPA) levels in the CTLA4-Ig group. However, among patients with high baseline HAQ-DI scores and low baseline ACPA levels (≦57.2), the CDAI remission rate was significantly higher in the TNFi group (29.8%) compared with the CTLA4-Ig group (5.9%, p< 0.0001). Among patients with high baseline HAQ-DI scores and ACPA levels (>57.2), the CDAI remission rate was significantly higher in the CTLA4-Ig group (35.6%) compared with the TNFi group (22.1%, p= 0.0057). CONCLUSION: Bio-naive RA patients with low HAQ-DI scores showed high treatment efficacy with no significant difference between CTLA4-Ig and TNFi. Among patients with high baseline HAQ-DI scores, TNFi and CTLA4-Ig were more likely to be effective in those with lower and higher baseline ACPA levels, respectively.

Improving our understanding of the paradoxical protective effect of obesity on radiographic damage: a large magnetic resonance imaging-study in early arthritis.

OBJECTIVE: Obesity conveys a risk for RA development, while paradoxically, associating with less radiographic progression after RA diagnosis. Using MRI we can study this surprising association in detail from MRI-detected synovitis and osteitis to MRI-detected erosive progression, which precedes radiographic progression. Previous research suggested obesity associates with less osteitis and synovitis. We therefore aimed to (i) validate the previously suggested association between BMI and MRI-detected osteitis/synovitis; (ii) study whether this is specific for ACPA-positive or ACPA-negative RA or also present in other arthritides; (iii) study whether MRI-detected osteitis associates with MRI-detected erosive progression; and (iv) study whether obesity associates with MRI-detected erosive progression. METHODS: We studied 1029 early arthritis patients (454 RA, 575 other arthritides), consecutively included in Leiden Early Arthritis Clinic. At baseline patients underwent hand-and-foot MRI that were RAMRIS-scored, and 149 RA patients underwent follow-up MRIs. We studied associations between baseline BMI and MRI-detected osteitis/synovitis (using linear regression), and erosive progression (using Poisson mixed models). RESULTS: In RA, higher BMI associated with less osteitis at disease onset (ß = 0.94; 95% CI: 0.93, 0.96) but not with synovitis. Higher BMI associated with less osteitis in ACPA-positive RA (ß = 0.95; 95% CI: 0.93, 0.97), ACPA-negative RA (ß = 0.97; 95% CI: 0.95, 0.99) and other arthritides (ß = 0.98; 95% CI: 0.96, 0.99). Over 2 years, overweight and obesity associated with less MRI-detected erosive progression (P = 0.02 and 0.03, respectively). Osteitis also associated with erosive progression over 2 years (P < 0.001). CONCLUSIONS: High BMI relates to less osteitis at disease onset, which is not confined to RA. Within RA, high BMI and less osteitis associated with less MRI-detected erosive progression. This suggests that the protective effect of obesity on radiographic progression is exerted via a path of less osteitis and subsequently fewer MRI-detected erosions.

Microbial Mechanisms of Rheumatoid Arthritis Pathogenesis.

PURPOSE OF REVIEW: Host-microbiome interactions have been implicated in the pathophysiology of rheumatoid arthritis (RA), but the data linking specific microbes to RA is largely associative. Here, we review recent studies that have interrogated specific mechanistic links between microbes and host in the setting of RA. RECENT FINDINGS: Several candidate bacterial species and antigens that may trigger the conversion of an anti-bacterial to an autoimmune response have been recently identified. Additional studies have identified microbial metabolic pathways that are altered in RA. Some of these microbial species and metabolic pathways have been validated in mouse models to induce RA-like immune responses, providing initial evidence of specific mechanisms by which the microbiota contributes to the development of RA. Several microbial species, antigens, and metabolites have been identified as potential contributors to RA pathophysiology. Further interrogation and validation of these pathways may identify novel biomarkers of or therapeutic avenues for RA.

The Lung in Rheumatoid Arthritis-Friend or Enemy?

Rheumatoid arthritis (RA) is a chronic autoimmune condition frequently found in rheumatological patients that sometimes raises diagnosis and management problems. The pathogenesis of the disease is complex and involves the activation of many cells and intracellular signaling pathways, ultimately leading to the activation of the innate and acquired immune system and producing extensive tissue damage. Along with joint involvement, RA can have numerous extra-articular manifestations (EAMs), among which lung damage, especially interstitial lung disease (ILD), negatively influences the evolution and survival of these patients. Although there are more and more RA-ILD cases, the pathogenesis is incompletely understood. In terms of genetic predisposition, external environmental factors act and subsequently determine the activation of immune system cells such as macrophages, neutrophils, B and T lymphocytes, fibroblasts, and dendritic cells. These, in turn, show the ability to secrete molecules with a proinflammatory role (cytokines, chemokines, growth factors) that will produce important visceral injuries, including pulmonary changes. Currently, there is new evidence that supports the initiation of the systemic immune response at the level of pulmonary mucosa where the citrullination process occurs, whereby the autoantibodies subsequently migrate from the lung to the synovial membrane. The aim of this paper is to provide current data regarding the pathogenesis of RA-associated ILD, starting from environmental triggers and reaching the cellular, humoral, and molecular changes involved in the onset of the disease.

Insights into the study and origin of the citrullinome in rheumatoid arthritis.

The presence of autoantibodies and autoreactive T cells to citrullinated proteins and citrullinating enzymes in patients with rheumatoid arthritis (RA), together with the accumulation of citrullinated proteins in rheumatoid joints, provides substantial evidence that dysregulated citrullination is a hallmark feature of RA. However, understanding mechanisms that dysregulate citrullination in RA has important challenges. Citrullination is a normal process in immune and non-immune cells, which is likely activated by different conditions (eg, inflammation) with no pathogenic consequences. In a complex inflammatory environment such as the RA joint, unique strategies are therefore required to dissect specific mechanisms involved in the abnormal production of citrullinated proteins. Here, we will review current models of citrullination in RA and discuss critical components that, in our view, are relevant to understanding the accumulation of citrullinated proteins in the RA joint, collectively referred to as the RA citrullinome. In particular, we will focus on potential caveats in the study of citrullination in RA and will highlight methods to precisely detect citrullinated proteins in complex biological samples, which is a confirmatory approach to mechanistically link the RA citrullinome with unique pathogenic pathways in RA.

Clinical Features of ACPA-Negative and ACPA-Positive Variants of Rheumatoid Arthritis.

The aim of the study was to investigate the features of the clinical picture of the disease in patients with ACPA-negative and ACPA-positive variants of rheumatoid arthritis. MATERIALS AND METHODS: : The study included patients with a reliable diagnosis of rheumatoid arthritis (RA) according to the criteria of ACR/EULAR 2010. Depending on the ACPA values, two groups of patients were recruited: ACPA-positive and ACPA-negative, comparable in gender, age, duration of the disease, and therapy. The nature of the onset and course of the disease and the activity of RA were evaluated (according to the DAS28, SDAI, CDAI indices). RESULTS AND DISCUSSION: : The study involved 79 patients with ACPA-negative variant of RA and 79 ACPA-positive patients. The age of patients (Me [IR] (in years)) with the ACPA(-) variant was 52 [39; 62]; with the ACPA(+) variant, 54 [42; 62]; the duration of the disease (in months) was 59 [23; 122] and 48 [17; 84], respectively. In ACPA(+) patients, a higher disease activity was determined (by the indices DAS 28crp, DAS28esr, SDAI, CDAI), higher values of C-reactive protein and erythrocyte sedimentation rate, and a greater number of painful and swollen joints (p < 0.05). According to the localization of the involved joints, arthritis of the proximal interphalangeal, metacarpal, wrist and shoulder joints was more often determined in ACPA(+) patients. Systemic manifestations of RA at the time of examination and in the anamnesis were statistically significantly more common in ACPA(+) (32.9%) than in ACPA(-) (17.7%) patients. Of the systemic manifestations, rheumatoid nodules were more common in ACPA(+) patients, whereas a tendency to a higher frequency of neuropathy, sclerites, and episcleritis was revealed in ACPA(-) patients. CONCLUSIONS: . In patients with ACPA(-) subtype, clinical signs of joint damage and the inflammatory component are less pronounced compared to ACPA(+). However, the mixed picture of manifestation, the less "bright" course of the disease, the absence of characteristic immunological biomarkers necessitate long-term and careful monitoring of this group of patients. At the same time, the subjective severity of the disease and dysfunction due to ankylosing joints do not differ from the ACPA(+) variant of RA.

Anti-Carbamylated Protein Antibodies in ACPA-Negative and ACPA-Positive Patients with Rheumatoid Arthritis.

The objective of this study was to assess the level of antibodies to carbamylated proteins and analyze the clinical and immunological associations in patients with ACPA-negative and ACPA-positive variants of rheumatoid arthritis. MATERIALS AND METHODS: . The study involved 150 patients with a reliable diagnosis of rheumatoid arthritis and 25 patients as healthy controls. Depending on ACPA values, two groups of patients were recruited: ACPA-positive (n = 75) and ACPA-negative (n = 75). RA activity was assessed by the DAS28 index. Determination of antibodies to carbamylated proteins was performed by enzyme-linked immunosorbent assay (BlueGene Biotech, China). Quantitative determination of ACPA in serum was performed by enzyme immunoassay using a commercial reagent kit (AxisShield, UK; upper limit of normal 5.0 U/mL; Orgentec, Germany; upper limit of normal 20.0 U/mL). RESULTS AND DISCUSSION: . Median anti-CarP in patients with RA was 126.2 [100.83; 157.41] ng/mL and was statistically significantly higher (p < 0.001) than in healthy controls (88.89 [70.53; 107.75] ng/mL). Among all patients with RA, 50 (33.3%) were anti-Carp-positive (22 (29.3%) in the ACPA(+) group and 28 (37.3%) in the ACPA(-) group), and one (2%) volunteer from healthy controls was anti-CarP(+) (p = 0.002). In ROC analysis performed to assess the diagnostic significance of anti-CarP for RA for all patients with RA, the area under the curve was 0.783 ± 0.047 with 95% CI: 0.691-0.874 (p < 0.001), with a cut-off point of 143 ng/mL, specificity 96%, sensitivity 36.7%. In the ACPA(+) RA group, the erosion count was statistically significantly higher (p = 0.044) in anti-CarP(+) patients than in anti-CarP(-) patients. A weak direct correlation between anti-CarP and DAS28 was found in the ACPA(-) RA group. CONCLUSIONS: . We studied the predictive value of anti-CarP as an auxiliary biomarker in ACPA(+) and ACPA(-) subtypes of RA. ACPA(+) anti-CarP(+) patients have a more "erosive" subtype of the disease than ACPA(+) anti-CarP(-) patients. In ACPA(-) patients, anti-CarP helps to identify a more erosive subtype of the disease, and among ACPA(-) patients it helps to reduce the proportion of seronegative patients. Further studies are required to determine the optimal standards for the laboratory diagnosis of anti-CarP and to clarify the diagnostic potential of these ABs as part of the differential diagnosis of arthritis in other rheumatic diseases.

The human bone marrow plasma cell compartment in rheumatoid arthritis - Clonal relationships and anti-citrulline autoantibody producing cells.

A majority of circulating IgG is produced by plasma cells residing in the bone marrow (BM). Long-lived BM plasma cells constitute our humoral immune memory and are essential for infection-specific immunity. They may also provide a reservoir of potentially pathogenic autoantibodies, including rheumatoid arthritis (RA)-associated anti-citrullinated protein autoantibodies (ACPA). Here we investigated paired human BM plasma cell and peripheral blood (PB) B-cell repertoires in seropositive RA, four ACPA+ RA patients and one ACPA- using two different single-cell approaches, flow cytometry sorting, and transcriptomics, followed by recombinant antibody generation. Immunoglobulin (Ig) analysis of >900 paired heavy-light chains from BM plasma cells identified by either surface CD138 expression or transcriptome profiles (including gene expression of MZB1, JCHAIN and XBP1) demonstrated differences in IgG/A repertoires and N-linked glycosylation between patients. For three patients, we identified clonotypes shared between BM plasma cells and PB memory B cells. Notably, four individuals displayed plasma cells with identical heavy chains but different light chains, which may indicate receptor revision or clonal convergence. ACPA-producing BM plasma cells were identified in two ACPA+ patients. Three of 44 recombinantly expressed monoclonal antibodies from ACPA+ RA BM plasma cells were CCP2+, specifically binding to citrullinated peptides. Out of these, two clones reacted with citrullinated histone-4 and activated neutrophils. In conclusion, single-cell investigation of B-cell repertoires in RA bone marrow provided new understanding of human plasma cells clonal relationships and demonstrated pathogenically relevant disease-associated autoantibody expression in long-lived plasma cells.

N-glycan in the variable region of monoclonal ACPA (CCP-Ab1) promotes the exacerbation of experimental arthritis.

OBJECTIVES: The variable region of most ACPA IgG molecules in the serum of RA patients carries N-glycan (N-glycanV). To analyse the pathogenicity of N-glycanV of ACPAs, we analysed the pathogenicity of a monoclonal ACPA, CCP-Ab1, with or without N-glycanV, which had been isolated from a patient with RA. METHODS: CCP-Ab1 with no N-glycosylation site in the variable region (CCP-Ab1 N-rev) was generated, and antigen binding, the effect on in vitro differentiation of osteoclasts from bone marrow mononuclear cells of autoimmune arthritis-prone SKG mice (the cell size of TRAP+ cells and bone resorption capacity) and the in vivo effect on the onset or exacerbation of autoimmune arthritis in SKG mice were evaluated in comparison with glycosylated CCP-Ab1. RESULTS: Amino acid residues in citrullinated peptide (cfc1), which are essential for binding to CCP-Ab1 N-rev and original CCP-Ab1, were almost identical. The size of TRAP+ cells was significantly larger and osteoclast bone resorption capacity was enhanced in the presence of CCP-Ab1, but not with CCP-Ab1 N-rev. This enhancing activity required the sialic acid of the N-glycan and Fc region of CCP-Ab1. CCP-Ab1, but not CCP-Ab1 N-rev, induced the exacerbation of experimental arthritis in the SKG mouse model. CONCLUSIONS: These data showed that N-glycanV was required for promoting osteoclast differentiation and bone resorption activity in both in vitro and in vivo assays. The present study demonstrated the important role of N-glycanV in the exacerbation of experimental arthritis by ACPAs.

Anti-protein arginine deiminase antibodies are distinctly associated with joint and lung involvement in rheumatoid arthritis.

OBJECTIVES: RA is a chronic inflammatory disease in which possible interstitial lung disease (ILD) is an extra-articular manifestation that carries significant morbidity and mortality. RF and ACPA are included in the RA classification criteria but prognostic and diagnostic biomarkers for disease endotyping and RA-ILD are lacking. Anti-protein arginine deiminase antibodies (anti-PAD) are a novel class of autoantibodies identified in RA. This study aimed to assess clinical features, ACPA and anti-PAD antibodies in RA patients with articular involvement and ILD. METHODS: We retrospectively collected joint erosions, space narrowing, clinical features and lung involvement of a cohort of 71 patients fulfilling the 2010 ACR/EULAR RA classification criteria. Serum samples from these patients were tested for ACPA IgG (QUANTA Flash CCP3), and anti-PAD3 and anti-PAD4 IgG, measured with novel assays based on a particle-based multi-analyte technology (PMAT). RESULTS: Anti-PAD4 antibodies were significantly associated with radiographic injury (P = 0.027) and erosions (P = 0.02). Similarly, ACPA levels were associated with erosive disease (P = 0.014). Anti-PAD3/4 double-positive patients displayed more joint erosions than patients with anti-PAD4 antibodies only or negative for both (P = 0.014 and P = 0.037, respectively). RA-ILD (15.5%, 11/71 patients) was associated with older age (P < 0.001), shorter disease duration (P = 0.045) and less erosive disease (P = 0.0063). ACPA were elevated in RA-ILD, while anti-PAD4 were negatively associated (P = 0.043). CONCLUSION: Anti-PAD4 and anti-PAD3 antibodies identify RA patients with higher radiographic injury and bone erosions. In our cohort, ILD is associated with lower radiographic and erosive damage, as well as low levels of anti-PAD4 antibodies.

Citrullinated and carbamylated proteins in extracellular microvesicles from plasma of patients with rheumatoid arthritis.

OBJECTIVES: To investigate the expression of citrullinated and carbamylated proteins in extracellular microvesicles (EMVs) from RA patients. METHODS: We enrolled 24 RA naïve for biological therapy and 20 healthy donors (HD), matched for age and sex. For each patient, laboratory and clinical data were recorded and clinical indexes were measured (Clinical Disease Activity Index, Simplified Disease Activity Index, DAS28). EMVs in RA patients and HD were purified from plasma and measured by nanoparticle tracking analysis (NanoSight). Further, EMVs were incubated with anti-citrullinated/carbamylated proteins antibodies and processed by flow cytometry and western blot to evaluate the expression of citrullinated/carbamylated antigens. RESULTS: NanoSight revealed a significant increase of EMVs in RA compared with HD. Moreover, cytofluorimetric analysis showed a significative higher expression of citrullinated antigens on EMVs' surface in RA than donors, while no substantial difference was found in the expression of carbamylated antigens. These data were confirmed by western blot which identified vimentin, glycolytic enzyme alpha-enolase 1 and collagen type II as the main citrullinated and carbamylated proteins carried by EMVs. Finally, a relevant correlation between the expression of citrullinated antigens and disease activity was found. CONCLUSIONS: The results of this study suggest an involvement of EMVs in the pathogenesis of RA by inducing autoimmunity.

Difficult to treat rheumatoid arthritis in a comprehensive evaluation program: frequency according to different objective evaluations.

Difficult-to-treat Rheumatoid Arthritis (RA-D2T) is a condition in which patients do not achieve the treatment target despite multiple advanced therapies, more others features. Aims: to estimate the frequency of RA-D2T in a cohort comprehensively evaluated (clinical, serology, imaging), and to analyze the associated characteristics. In a second part, the frequency of RA-D2T after 1 year of follow-up, analyzing the predictive variables at baseline and therapeutic behavior. Cross-sectional and prospective study, consecutive RA were included, then those who completed the one-year follow-up were evaluated. RA-D2T frequency was estimated (DAS28-CDAI-SDAI-Ultrasonography (US)-HAQ) at baseline and 1 year. The variables associated and those baseline predictive characteristics of D2T at 1 year, and their independent association by logistic regression were analyzed. The treatment approach was described. Two hundred seventy-six patients completed the evaluation, frequency of RA-D2T (all scores): 27.5%. Anemia, RF high titers and higher HAQ score were independent associated. At year, 125 competed follow-up. RA-D2T (all scores): 33%, D2T-US and D2T-HAQ were 14 and 18.4% (p 0.001). Predictive baseline characteristics D2T (all score): ACPA + (OR: 13.7) and X-ray erosion (OR: 2.9). D2T-US: X-ray erosion (OR: 19.7). Conventional DMARDs, corticosteroids and TNF-blockers were the drugs most used by D2T patients, Jaki were the most used in the switch. We showed different frequencies of RA-D2T according to different objective parameters (scores, images) and their association with patient characteristics. In turn, predictive variables (erosions-ACPA) for RA-D2T at 1 year were analyzed. It was shown that the Jaki were the most used drug in these patients.

The Sizes and Composition of HDL-Cholesterol Are Significantly Associated with Inflammation in Rheumatoid Arthritis Patients.

Rheumatoid arthritis (RA), a chronic inflammatory disease, carries a significant burden of atherosclerotic cardiovascular diseases (ASCVD). With their heterogeneous composition, high-density lipoprotein (HDL) particles have varied athero-protective properties, and some may even increase ASCVD risk. In this prospective and cross-sectional study, we aimed to examine the relationship between HDL sizes/metabolites and inflammation in RA. Using 1H-NMR-based lipid/metabolomics, differential HDL-related metabolites were identified between RA patients and healthy control (HC) subjects and between RA patients with and without anti-citrullinated peptide antibodies (ACPA). The correlation between the discriminative HDL-related metabolites and C-reactive protein (CRP) was evaluated in RA patients. RA patients demonstrated higher particle number, lipids, cholesterol, cholesterol ester, free cholesterol, and phospholipids in large/very large-sized HDLs. ACPA-positive patients had higher L-HDL-C and L-HDL-CE but lower small-/medium-sized HDL-TG levels than ACPA-negative patients. An inverse correlation was found between CRP levels and small-sized HDLs. Janus kinase inhibitor treatment was associated with increased serum small-sized HDL-related metabolites and decreased CRP levels. We are the first to reveal the significant associations between RA inflammation and HDL sizes/metabolites. A potential link between ACPA positivity and changes in serum levels of HDL-related metabolites was also observed in RA patients.

PADI4 Haplotypes Contribute to mRNA Expression, the Enzymatic Activity of Peptidyl Arginine Deaminase and Rheumatoid Arthritis Risk in Patients from Western Mexico.

Citrullination is catalyzed by the peptidyl arginine deiminase 4 (PAD4) enzyme, encoded by the PADI4 gene. Increased PAD4 activity promotes the onset and progression of rheumatoid arthritis (RA). This study aimed to evaluate the association of PADI4 haplotypes with RA risk, mRNA expression, and the PAD4 activity in patients with RA from Mexico. Methodology: 100 RA patients and 100 control subjects (CS) were included. Genotyping was performed by PCR-RFLP method, PADI4 mRNA expression was quantified by real-time PCR, the contribution of PADI4 alleles (PADI4_89 G>A, PADI4_90 T>C, and PADI4_92 G>C) to mRNA expression by the ASTQ method, and PAD4 activity by HPLC. Also, the anti-CCP and anti-PADI4 antibodies were quantified by ELISA. Results: The three PADI4 polymorphisms were associated with RA susceptibility (OR = 1.72, p = 0.005; OR = 1.62; p = 0.014; OR = 1.69; p = 0.009; respectively). The 89G, 90T, and 92G alleles have a higher relative contribution to PADI4 mRNA expression from RA patients than 89A, 90C, and 92C alleles in RA patients. Moreover, the GTG/GTG haplotype was associated with RA susceptibility (OR = 2.86; p = 0.024). The GTG haplotype was associated with higher PADI4 mRNA expression (p = 0.04) and higher PAD4 enzymatic activity (p = 0.007) in RA patients. Conclusions: The evaluated polymorphisms contribute to PADI4 mRNA expression and the enzymatic activity of PAD4 in leukocytes. Therefore, the GTG haplotype is a genetic risk factor for RA in western Mexico, and is associated with increased PADI4 mRNA expression and higher PAD4 activity in these patients.

Anti-citrullinated protein antibody specificities and pulmonary fibrosis in relation to genetic loci in early rheumatoid arthritis.

OBJECTIVES: Pulmonary manifestations in RA are common comorbidities, but the underlying mechanisms are largely unknown. The added value of a multiplex of ACPA and genetic risk markers was evaluated for the development of pulmonary fibrosis (PF) in an inception cohort. METHODS: A total of 1184 patients with early RA were consecutively included and followed prospectively from the index date until death or 31 December 2016. The presence of 21 ACPA fine specificities was analysed using a custom-made microarray chip (Thermo Fisher Scientific, Uppsala, Sweden). Three SNPs, previously found related to PF were evaluated, rs2609255 (FAM13A), rs111521887 (TOLLIP) and rs35705950 (MUC5B). ACPA and genetic data were available for 841 RA patients, of whom 50 developed radiologically defined PF. RESULTS: In unadjusted analyses, 11 ACPA specificities were associated with PF development. In multiple variable analyses, six ACPA specificities were associated with increased risk of PF: vimentin (Vim)60-75, fibrinogen (Fib)ß62-78 (72), Fibα621-635, Bla26, collagen (C)II359-369 and F4-CIT-R (P < 0.01 to P < 0.05). The number of ACPA specificities was also related to PF development (P < 0.05 crude and adjusted models). In multiple variable models respectively adjusted for each of the SNPs, the number of ACPA specificities (P < 0.05 in all models), anti-Vim60-75 (P < 0.05, in all models), anti-Fibß62-78 (72) (P < 0.001 to P < 0.05), anti-CII359-369 (P < 0.05 in all models) and anti-F4-CIT-R AQ4 (P < 0.01 to P < 0.05), anti-Fibα621-635 (P < 0.05 in one) and anti-Bla26 (P < 0.05 in two) were significantly associated with PF development. CONCLUSION: The development of PF in an inception cohort of RA patients was associated with both presence of certain ACPA and the number of ACPA specificities and risk genes.

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.

IgA anti-citrullinated protein antibodies are associated with flares during DMARD tapering in rheumatoid arthritis.

OBJECTIVES: A substantial proportion of RA patients flare upon withdrawal of DMARDs, and thus the definition of prognostic markers is crucial. ACPA positivity has been identified as a risk factor for flare. However, only the role of IgG ACPA is established in this context, while the role of IgA ACPA is poorly defined. We thus aimed to investigate the role of IgA ACPA in flaring of RA. METHODS: Serum levels of IgA1 and IgA2 ACPA at baseline and after 12 months were measured in 108 patients from the randomized controlled RETRO study. RA patients in stable remission for at least 6 months at study recruitment were assigned to either one of the DMARD tapering arms or to continuation of DMARDs. RESULTS: In patients remaining in remission but not in the ones who flared, IgA2 ACPA levels and proportion of IgA2 in ACPA (IgA2% ACPA) significantly declined (median of 17.5%; P < 0.0001). This seemed to be independent of the treatment choice, as there was no difference in IgA2 ACPA dynamics between the study arms. IgA2% ACPA was associated with disease activity (DAS28) at flare (r = 0.36; P = 0.046). IgA and IgG ACPA showed a tendency towards independent contribution to the risk of flare with the highest risk if a patient had both antibody classes. CONCLUSION: In this study, IgA ACPA was identified as a risk factor for flare in combination with IgG ACPA. IgA2 ACPA levels were associated with flare severity and declined in patients in stable remission.