ACPA-positive Rheumatoid Arthritis Research Articles

Exhaled Nitric Oxide Reflects the Immune Reactions of the Airways in Early Rheumatoid Arthritis.

Patients with rheumatoid arthritis (RA) have altered levels of exhaled nitric oxide (NO) compared with healthy controls. Here, we investigated whether the clinical features of and immunological factors in RA pathogenesis could be linked to the NO lung dynamics in early disease. A total of 44 patients with early RA and anti-citrullinated peptide antibodies (ACPAs), specified as cyclic citrullinated peptide 2 (CCP2), were included. Their exhaled NO levels were measured, and the alveolar concentration, the airway compartment diffusing capacity and the airway wall concentration of NO were estimated using the Högman-Meriläinen algorithm. The disease activity was measured using the Disease Activity Score for 28 joints. Serum samples were analysed for anti-CCP2, rheumatoid factor, free secretory component, secretory component containing ACPAs, antibodies against Porphyromonas gingivalis (Rgp) and total levels of IgA, IgA1 and IgA2. Significant negative correlations were found between the airway wall concentration of NO and the number of swollen joints (Rho -0.48, p = 0.004), between the airway wall concentration of NO and IgA rheumatoid factor (Rho -0.41, p = 0.017), between the alveolar concentration and free secretory component (Rho -0.35, p = 0.023) and between the alveolar concentration and C-reactive protein (Rho -0.36, p = 0.016), but none were found for anti-CCP2, IgM rheumatoid factor or the anti-Rgp levels. In conclusion, altered NO levels, particularly its production in the airway walls, may have a role in the pathogenesis of ACPA-positive RA.

Patient burden and joint-inflammation during development of RA from arthralgia: is it similar in ACPA-positive and ACPA-negative disease?

Anti-citrullinated protein antibody(ACPA)-positive and ACPA-negative rheumatoid arthritis(RA) differ in underlying risk factors but have a similar clinical presentation at RA-diagnosis. It is unknown what the ACPA-associated differences or similarities are during the symptomatic at-risk stage of RA, clinically suspect arthralgia(CSA). To deepen insights into these differences/similarities, we compared the course of symptoms/impairments and subclinical joint-inflammation in the CSA-phase during progression to inflammatory arthritis(IA) or to CSA-resolution. 845 CSA-patients were followed for median 24 months; 136 patients developed IA and additional 355/505 patients had resolution of CSA according to rheumatologists. Patient burden (pain/morning stiffness/fatigue/functional disabilities/presenteeism) was assessed at baseline, 4/12/24 months and IA-development. Subclinical joint-inflammation in hands/feet was assessed over time with 1.5 T-MRI. Linear/Poisson mixed models were used. Both in ACPA-positive and ACPA-negative patients, patient burden increased towards IA-development and decreased towards CSA-resolution. However, patient burden was lower in ACPA-positive than ACPA-negative disease on all timepoints. Conversely, subclinical joint-inflammation tended to increase more rapidly during development of ACPA-positive IA (IRR = 1.52,95%CI = 0.94-2.47, p= 0.089), and remained higher over time in ACPA-positive CSA-patients achieving resolution compared with ACPA-negative patients (IRR = 1.52,95%CI = 1.07-2.15, p= 0.018). Although correlation coefficients between changes in patient burden and subclinical joint-inflammation during progression to IA were weak, they were consistently higher in ACPA-positive than ACPA-negative disease, e.g. ρ = 0.29 vs ρ = 0.12 for functional disabilities. During RA-development and CSA-resolution, ACPA-positive CSA-patients have lower patient burden, but more subclinical joint-inflammation than ACPA-negative CSA-patients. These data strengthen the notion that the development of ACPA-positive and ACPA-negative RA is pathophysiologically different, and encourage further research on these differences.

Porphyromonas gingivalis with collagen immunization induces ACPA-positive rheumatoid arthritis in C3H mice

The pathogenic anti-citrullinated protein antibodies (ACPA) are thought to play a vital role in the initiation and immune maintenance of rheumatoid arthritis (RA). However, it is noteworthy that ACPA is not a salient characteristic of any conventional RA animal model. Porphyromonas gingivalis (Pg) is the first microorganism identified to induce citrullination and a target of autoantibodies in early rheumatoid arthritis (RA). Thus, we employed C3H mice with specific MHC types and combined Pg infection with collagen immunity to develop an animal model of ACPA-positive RA. The resulting model exhibited citrullination characteristics, as well as pathological and immune cell changes. 1) Mice showed a significant increase in ACPA levels, and various organs and tissues exhibited elevated levels of citrullinated protein. 2) The mice experienced heightened pain, inflammation, and bone destruction. 3) The spleen and lymph nodes of the mice showed a significant increase in the proportion of Tfh-GCB cell subpopulations responsible for regulating autoantibody production. In conclusion, the C3H mouse model of Pg infection with collagen immunity demonstrated significant alterations in ACPA levels, citrullinated protein expression, and immune cell subpopulations, which could be a crucial factor leading to increased pain, inflammation, and bone destruction.

Association of Interosseous Tendon Inflammation in the Hand With Different Early Arthritides in a 10-Year Magnetic Resonance Imaging Study.

Inflammation around the tendons of the hand interosseous muscles (interosseous tendon inflammation [ITI]) was recently identified on magnetic resonance imaging (MRI) in a set of patients with rheumatoid arthritis (RA) and arthralgia. We conducted a large MRI study to assess the prevalence of ITI at diagnosis of RA and of other arthritides, as well as its relationship with clinical signs. A total of 1,205 patients presenting with various types of early arthritis between 2010 and 2020 underwent contrast-enhanced hand MRI as part of the prospective Leiden Early Arthritis Cohort. MRI was evaluated with blinding for clinical data, for ITI lateral of metacarpophalangeal (MCP) joints 2-5, and for synovitis/tenosynovitis/osteitis. We assessed ITI presence at baseline per diagnosis and its relationship with clinical characteristics (ie, presence of hand arthritis, increased acute phase reactants, and local joint swelling and tenderness). Logistic regression and generalized estimating equations were used with adjustment for age and established local inflammation features (synovitis/tenosynovitis/osteitis). A total of 36% of patients with early RA (n=532) had ITI; this was similar in patients with anti-citrullinated protein antibody (ACPA)-negative RA (37%) and those with ACPA-positive RA (34%; P = 0.53). ITI occurred regularly in remitting seronegative symmetrical synovitis with pitting edema (60%) and connective tissue diseases (44%) and less frequently in undifferentiated arthritis (14%), psoriatic arthritis (14%), inflammatory osteoarthritis (8%), reactive arthritis (7%), crystal arthritis (7%), and peripheral spondylarthritis (4%). ITI occurred more often in diagnoses with frequent arthritis of the hands (P < 0.001) and increased acute-phase reactants (P < 0.001). Within RA, ITI occurred together with local MCP joint synovitis (odds ratio [OR] 2.4, 95% confidence interval [95% CI] 1.7-3.4), tenosynovitis (OR 2.4, 95% CI 1.8-3.3), and osteitis (OR 2.2, 95% CI 1.6-3.1) on MRI. Moreover, ITI presence was associated with local MCP joint tenderness (OR 1.6, 95% CI 1.2-2.1) and swelling (OR 1.8, 95% CI 1.3-2.6), independent of age and MRI-detected synovitis/tenosynovitis/osteitis. ITI occurs regularly in RA and other arthritides with preferential involvement of hand joints and increased acute-phase reactants. At the MCP joint level, ITI associates independently with joint tenderness and swelling. Hence, ITI is a newly identified inflamed tissue mainly found in arthritides with particularly extensive and symptomatic inflammation.

Epigenome-wide methylation haplotype association analysis identified HLA-DRB1, HLA-DRB5 and HLA-DQB1 as risk factors for rheumatoid arthritis.

The aim of this study was to compare nonrandom associations between physically adjacent single methylation polymorphism loci among rheumatoid arthritis (RA) and normal subjects for investigating RA-risk methylation haplotypes (meplotype). With 354 ACPA-positive RA patients and 335 normal controls selected from a case-control study based on Swedish population, we conducted the first RA epigenome-wide meplotype association study using our software EWAS2.0, mainly including (i) converted the β value to methylation genotype (menotype) data, (ii) identified methylation disequilibrium (MD) block, (iii) calculated frequent of each meplotypes in MD block and performed case-control association test and (iv) screened for RA-risk meplotypes by odd ratio (OR) and p-values. Ultimately, 545 meplotypes on 334 MD blocks were identified significantly associated with RA (p-value<.05). These meplotypes were mapped to 329 candidate genes related to RA. Subsequently, combined with gene optimization, eight RA-risk meplotypes were identified on three risk genes: HLA-DRB1, HLA-DRB5 and HLA-DQB1. Our results reported the relationship between DNA methylation pattern on HLA-DQB1 and the risk of RA for the first time, demonstrating the co-demethylation of 'cg22984282' and 'cg13423887' on HLA-DQB1 gene (meplotype UU, p-value=2.90E-6, OR=1.68, 95% CI=[1.35, 2.10]) may increase the risk of RA. Our results demonstrates the potential of methylation haplotype analysis to identify RA-related genes from a new perspective and its applicability to the study of other disease.

Potential alleviation of bone mineral density loss with Janus kinase inhibitors in rheumatoid arthritis.

Rheumatoid arthritis (RA) is characterized by localized bone loss, general osteoporosis and increased fracture risks. Tumour necrosis factor inhibitors (TNFi), non-tumour necrosis factor inhibitors (non-TNFi) biologic, Janus kinase inhibitors (JAKi) had shown the suppression effects to osteoclast activation and improvement of bone mineral density (BMD). Anti-cyclic citrullinated peptide antibody (ACPA) is associated with osteoclast activation and the resultant bone loss. However, few studies have compared BMD changes among patients with RA treated with targeted therapies that have different mechanisms of action. This retrospective study recruited patients with RA who had undergone BMD testing twice. Changes in the BMD were compared using the generalized estimating equation (GEE) in treatment groups that received conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), TNFi, non-TNFi biologics, and JAKi. In total, 362 patients with RA were enrolled (csDMARDs, n = 153, TNFi, n = 71, non-TNFi biologics, n = 108, JAKi, n = 30). We observed greater changes in femoral BMD (left, 0.06, 95% CI 0.01-0.12, p = 0.016; right, 0.09, 95% CI 0.04-0.15, p = 0.001 by GEE) following JAKi treatment as compared with other treatments. Compared to the ACPA-negative group, patients with ACPA positivity exhibited greater improvement in the femoral BMD (left, 0.09, 95% CI 0.02-0.15, p = 0.008; right, 0.11, 95% CI 0.05-0.18, p = 0.001). Compared to other targeted therapies, JAKi might exert a more potent effect to prevent BMD loss, specifically in ACPA-positive patients with RA, and could be a potential therapeutic option to mitigate generalized bone loss. Key Points •JAKi therapy inhibits systemic bone loss in patients with RA. •ACPA-positive RA patients exhibited a greater BMD improvement than ACPA-negative RA patients. •JAKi might more potently prevent BMD decline than conventional synthetic or biological DMARDs.

The Natural Sequence in Which Subclinical Inflamed Joint Tissues Subside or Progress to Rheumatoid Arthritis: A Study of Serial MRIs in the TREAT EARLIER Trial.

The natural trajectory of clinical arthritis progression at the tissue level remains elusive. We hypothesized that subclinical inflammation in different joint tissues (synovitis, tenosynovitis, osteitis) increases in a distinct temporal order in patients with clinically suspect arthralgia (CSA) who develop rheumatoid arthritis (RA) and subsides in a different sequence when CSA spontaneously resolves. We studied 185 serial magnetic resonance images (MRIs) from CSA patients with subclinical joint inflammation from the placebo arm of the TREAT EARLIER trial: 52 MRIs from 21 RA progressors (MRIs conducted at 1 year before, at 4 months before, and upon RA development), and 133 MRIs from 35 patients with spontaneous resolution of pain (MRIs conducted at baseline and at 4, 12, and 24 months). MRIs were scored for osteitis, synovitis, and tenosynovitis. We used cross-lagged models to evaluate 2 types of time patterns between pairs of inflamed tissues: a simultaneous pattern (coinciding changes) and a subsequent pattern (inflammatory changes in 1 tissue preceding changes in another tissue). In patients who developed RA, synovitis, tenosynovitis, and osteitis increased simultaneously. Increasing osteitis occurred in the final 4 months before RA diagnosis, following incremental tenosynovitis and synovitis changes during the 1 year to 4 months before diagnosis (P < 0.01). In anti-citrullinated protein antibody (ACPA)-positive and ACPA-negative patients who progressed to RA, osteitis increased just before RA development. In patients with pain resolution, simultaneous decreases in synovitis, tenosynovitis, and osteitis occurred, with tenosynovitis decreasing in the first 4 months after CSA onset preceding decreasing synovitis and osteitis during 4-12 months (P = 0.02 and P < 0.01). We identified natural sequences of subclinical inflammation in different joint tissues, which deepens our understanding of clinical arthritis and RA development. During RA progression, increasing osteitis followed previous increases in tenosynovitis and synovitis. During pain resolution, tenosynovitis decreased first, followed by decreasing synovitis and osteitis.

The Protective Effect of HLA-DRB1 and HLA-DQB1 Alleles to ACPA-Positive and RF-Positive RA in Albanian Population

BACKGOUND: The prevalence of rheumatoid arthritis (RA) and its specific autoantibodies varies in different populations. This variability depends on the genetic polymorphism of the immune response genes among which the HLA system plays a major role. AIM: We conducted a preliminary study of the distribution of HLA-DRB1 and HLA-DQB1 first field level alleles in a sample of 100 Albanian patients with RA. METHODS: In this context, we studied the HLA-DRB1 and HLA-DQB1 first-level allele frequencies in 100 Albanian patients with RA and considering their rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA) serologic subgroups. We compared them with the respective frequencies in a population of 191 Albanian individuals without known pathology. RESULTS: No differences were found between the controls and the RA patient group, but three statistically significant differences were found: an increase in DRB1*04 among ACPA-positive, RF-positive and ACPA-positive/RF-positive patients, a significant decrease in DRB1*11 among ACPA-positive/RF-positive, and also a decrease in DRB1*13 among RF-positive patient subgroups. The frequencies of DRB1 allotypes in ACPA+ and RF+ patients compared to their counterpart ACPA− and RF−patient subgroups showed the predisposing effect of HLA-DRB1*04 for ACPA and RF seropositivity (p, respectively, 0.0008 and 0.0017) and the protective role of HLA-DRB1*11 for ACPA and RF positivity (p, respectively, 0.007 and 0.02). The same protective role from the RF positivity is also found with the HLA-DRB1*13 alleles (p = 0.007). As far as the DQB1 locus is concerned, a protective association has been found between the HLA-DQB1*06 alleles with both RF+ and RF+ ACPA+ positivity (p, respectively, 0.05 and 0.04) when comparing the control group with the respective RA patient subgroups. In ACPA+ and RF+ patients compared to the ACPA− and RF− patient subgroups, the only detected difference was between RF (+) and RF (−) patients (p =0.04). CONCLUSION: The relatively low frequencies of DRB1*04 and high (DRB1*11 and DRB1*13) in the Albanian population might explain the rather low positivity rate of ACPA and RF antibodies among the Albanian RA patients. Our study demonstrates that DRB1*11, DRB1*13 and DQB1*06 may be negatively associated with RA. Conversely, DRB1*04 may confer susceptibility to RA in Albanian population.

Patients with ACPA-positive and ACPA-negative rheumatoid arthritis show different serological autoantibody repertoires and autoantibody associations with disease activity

Patients with rheumatoid arthritis (RA) can test either positive or negative for circulating anti-citrullinated protein antibodies (ACPA) and are thereby categorized as ACPA-positive (ACPA+) or ACPA-negative (ACPA−), respectively. In this study, we aimed to elucidate a broader range of serological autoantibodies that could further explain immunological differences between patients with ACPA+ RA and ACPA− RA. On serum collected from adult patients with ACPA+ RA (n = 32), ACPA− RA (n = 30), and matched healthy controls (n = 30), we used a highly multiplex autoantibody profiling assay to screen for over 1600 IgG autoantibodies that target full-length, correctly folded, native human proteins. We identified differences in serum autoantibodies between patients with ACPA+ RA and ACPA− RA compared with healthy controls. Specifically, we found 22 and 19 autoantibodies with significantly higher abundances in ACPA+ RA patients and ACPA− RA patients, respectively. Among these two sets of autoantibodies, only one autoantibody (anti-GTF2A2) was common in both comparisons; this provides further evidence of immunological differences between these two RA subgroups despite sharing similar symptoms. On the other hand, we identified 30 and 25 autoantibodies with lower abundances in ACPA+ RA and ACPA− RA, respectively, of which 8 autoantibodies were common in both comparisons; we report for the first time that the depletion of certain autoantibodies may be linked to this autoimmune disease. Functional enrichment analysis of the protein antigens targeted by these autoantibodies showed an over-representation of a range of essential biological processes, including programmed cell death, metabolism, and signal transduction. Lastly, we found that autoantibodies correlate with Clinical Disease Activity Index, but associate differently depending on patients’ ACPA status. In all, we present candidate autoantibody biomarker signatures associated with ACPA status and disease activity in RA, providing a promising avenue for patient stratification and diagnostics.

Autoantibodies against complement factor B in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder affecting the joints. Many patients carry anti-citrullinated protein autoantibodies (ACPA). Overactivation of the complement system seems to be part of the pathogenesis of RA, and autoantibodies against the pathway initiators C1q and MBL, and the regulator of the complement alternative pathway, factor H (FH), were previously reported. Our aim was to analyze the presence and role of autoantibodies against complement proteins in a Hungarian RA cohort. To this end, serum samples of 97 ACPA-positive RA patients and 117 healthy controls were analyzed for autoantibodies against FH, factor B (FB), C3b, C3-convertase (C3bBbP), C1q, MBL and factor I. In this cohort, we did not detect any patient with FH autoantibodies but detected C1q autoantibodies in four patients, MBL autoantibodies in two patients and FB autoantibodies in five patients. Since the latter autoantibodies were previously reported in patients with kidney diseases but not in RA, we set out to further characterize such FB autoantibodies. The isotypes of the analyzed autoantibodies were IgG2, IgG3, IgGκ, IgGλ and their binding site was localized in the Bb part of FB. We detected in vivo formed FB-autoanti-FB complexes by Western blot. The effect of the autoantibodies on the formation, activity and FH-mediated decay of the C3 convertase in solid phase convertase assays was determined. In order to investigate the effect of the autoantibodies on complement functions, hemolysis assays and fluid phase complement activation assays were performed. The autoantibodies partially inhibited the complement-mediated hemolysis of rabbit red blood cells, inhibited the activity of the solid phase C3-convertase and C3 and C5b-9 deposition on complement activating surfaces. In summary, in ACPA-positive RA patients we identified FB autoantibodies. The characterized FB autoantibodies did not enhance complement activation, rather, they had inhibitory effect on complement. These results support the involvement of the complement system in the pathomechanism of RA and raise the possibility that protective autoantibodies may be generated in some patients against the alternative pathway C3 convertase. However, further analyses are needed to assess the exact role of such autoantibodies.

Occupational inhalable agents constitute major risk factors for rheumatoid arthritis, particularly in the context of genetic predisposition and smoking

ObjectivesTo assess the effects of occupational inhalable exposures on rheumatoid arthritis (RA) development and their interactions with smoking and RA-risk genes, stratifying by presence of anticitrullinated protein antibodies (ACPA).MethodsData came...

Higher skin autofluorescence in individuals at risk for rheumatoid arthritis: results from a large population based cohort.

To investigate skin autofluorescence (SAF) levels, an early indicator for cardiovascular disease, in relation to the presence of anticitrullinated protein antibodies (ACPA), joint complaints and rheumatoid arthritis (RA) in a large population-based cohort. Cross-sectional data were used from 17346 participants of the Dutch Lifelines Cohort Study, of whom baseline SAF and ACPA levels were available. Individuals were divided into four groups: ACPA-negative controls (n=17211), ACPA-positive without joint complaints (n=49), ACPA-positive RA risk (n=31) and defined RA (n=52). Multinomial regression was used to compare SAF levels and correct for potential confounders. SAF levels were higher in the ACPA-positive RA risk group (OR 2.04, p=0.034) and the defined RA group (OR 3.10, p<0.001) compared to controls, but not in the ACPA-positive without joint complaints group (OR 1.07, p=0.875). The difference in SAF levels remained statistically significant in the defined RA group after adjusting for age (OR 2.09, p=0.011), smoking status, renal function or HbA1c. In the ACPA-positive RA risk group, the effect was found to be comparable (corrected for age: OR 2.09). Our results indicate that ACPA-positive individuals with RA risk have elevated SAF levels, which is regarded as a non-invasive marker for oxidative stress and a possible indicator for development of cardiovascular disease. Therefore, it is important to conduct further studies to explore if, in ACPA-positive individuals with RA risk and no diagnosis of RA, cardiovascular risk management should be considered in future clinical practice.

Genetic variant in SPAG16 is associated with the susceptibility of ACPA-positive rheumatoid arthritis possibly via regulation of MMP-3

ObjectivesIn two previously published genome-wide association studies, a cluster of variants of sperm-associated antigen16 (SPAG16) were reported to be associated with the radiological progression rate of ACPA-positive rheumatoid arthritis (RA) patients from North American and Southern European ancestry. In this study, we aimed to investigate whether the reported RA-risk loci in SPAG16 are associated with the disease in the Chinese population and to further validate the functional role of the susceptible locus in RA tissues.MethodsA total of 500 ACPA-positive RA patients and 1000 age-matched healthy subjects were recruited. Two SNPs of SPAG16, including rs7607479 (C/T) and rs6435818 (A/C), were genotyped, and the genotyping data were compared with chi-square test. Gene expression analysis was performed in synovial tissues obtained from 40 RA patients and 30 non-RA controls surgically treated for bone fracture. The tissue expression of SPAG16 and matrix metalloproteinase 3 (MMP-3) was compared between the two groups by the Student’s t test. The relationship between serum indexes and mRNA expression of SPAG16 and MMP-3 were evaluated by Spearman’s correlation analysis.ResultFor rs7607479, the frequency of genotype TT was significantly higher in RA patients than in the controls (49.0% vs. 40.4%, p = 0.002). The RA patients were found to have significantly lower frequency of allele C than the controls (30.9% vs. 36.8%, p = 0.001). As for rs6435818, there was no significant difference of genotype or allele frequency between the two groups. The mRNA expression of MMP-3 was 1.63-fold higher in the RA patients than in the controls (p < 0.001). The expression of SPAG16 was comparable between the two groups (p = 0.43). The mRNA expression of MMP-3 was 1.39-fold higher in patients with genotype TT than in the patients with genotype CC (p = 0.006). The mRNA expression level of MMP-3 was significantly correlated with serum rheumatoid factor (r = 0.498, p < 0.001) and C-reactive protein (r = 0.272, p = 0.01), weakly correlated with erythrocyte sedimentation rate (r = 0.236, p = 0.09).ConclusionsWe validated a common genetic risk factor in ACPA-positive patients with RA, which is associated with the tissue production of MMP-3 and disease progression. Further functional analysis into the role of rs7607479 in MMP-3 expression can shed new light on the genetic architecture of ACPA-positive RA.

ACPA-negative rheumatoid arthritis: From immune mechanisms to clinical translation.

SummaryThe presence of anti-citrullinated protein autoantibodies (ACPA) is a hallmark feature of rheumatoid arthritis (RA), which causes chronic joint destruction and systemic inflammation. Based on ACPA status, RA patients can be sub-grouped into two major subsets: ACPA-positive RA (ACPA+ RA) and ACPA-negative RA (ACPA– RA). Accumulating evidence have suggested that ACPA+ RA and ACPA– RA are two distinct disease entities with different underlying pathophysiology. In contrast to the well-characterized pathogenic mechanisms of ACPA+ RA, the etiology of ACPA– RA remains largely unknown. In this review, we summarized current knowledge about the primary drivers of ACPA– RA, particularly focusing on the serological, cellular, and molecular aspects of immune mechanisms. A better understanding of the immunopathogenesis in ACPA– RA will help in designing more precisely targeting strategies, and paving the road to personalized treatment. In addition, identification of novel biomarkers in ACPA– RA will substantially promote early treatment and improve the outcomes.

Treatment resistance of rheumatoid arthritis relates to infection of periodontal pathogenic bacteria: a case–control cross-sectional study

Recent studies have shown that periodontitis is associated with rheumatoid arthritis (RA) and periodontal bacteria, such as Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) are involved in the pathogenesis of RA via citrullinated proteins. Smoking has also been shown to be involved in the pathogenesis of RA; however, the extent of this involvement is still poorly understood. In addition, RA and polymyalgia rheumatica (PMR) are sometimes difficult to differentiate; however, the relationship between PMR and the factors from smoking and periodontal bacteria is unclear. The aim of this study was to clarify the relationship between periodontal pathogenic bacterial infections and smoking in patients with RA or PMR. This case–control study included 142 patients with untreated RA or PMR. This study evaluated the serum antibody titers against periodontal pathogenic bacterial antigens and an anti-citrullinated peptide antibody (ACPA). In patients with RA, the relationship between antibody titers and disease activity of RA and response after 3 months of treatment was also investigated. Additionally, the effects of smoking were evaluated. Although there was no significant difference in serum antibody titer against periodontal pathogenic bacteria between the ACPA-positive RA group and the ACPA-negative PMR group, we found an association between the elevated antibody titer against Pg and the degree of ACPA value, especially between negative group and high-value positive group (≥ 100 U/mL). The antibody titers against Aa and Pg did not differ depending on disease activity score 28 (DAS28) at baseline; however, patients with high antibody titers had poor RA therapeutic response as judged by DAS28 after 3 months. We could not find any association between smoking and any of these parameters. Periodontal pathogenic bacteria, especially Pg, are associated with elevated ACPA levels. Our findings suggest that Pg and Aa infections interfere with the therapeutic response of RA.

Intermetatarsal Bursitis, a Novel Feature of Juxtaarticular Inflammation in Early Rheumatoid Arthritis Related to Clinical Signs: Results of a Longitudinal Magnetic Resonance Imaging Study.

Intermetatarsal bursae in the forefeet possess a synovial lining similar to joints and tendon sheaths. Inflammation of these bursae (intermetatarsal bursitis [IMB]) was recently identified as specific for early rheumatoid arthritis (RA). The present study was undertaken to determine if IMB is indeed an RA feature by assessing the following: 1) the association with other local inflammatory measures (synovitis, tenosynovitis, and osteitis), 2) the association with clinical signs, and 3) whether it responds to disease-modifying antirheumatic drug (DMARD) therapy similarly to other local inflammatory measures. One hundred fifty-seven consecutive early RA patients underwent unilateral contrast-enhanced 1.5T forefoot magnetic resonance imaging (MRI) at diagnosis. MRIs were evaluated for IMB presence and for synovitis, tenosynovitis, and osteitis in line with the RA MRI Scoring (RAMRIS) system (summed as RAMRIS inflammation). MRIs at 4, 12, and 24 months were evaluated for IMB presence and size in patients who had IMB at baseline and received early DMARD therapy. Logistic regression and generalized estimating equations were used. Anti-citrullinated protein antibody (ACPA) stratification was performed. Sixty-nine percent of RA patients had ≥1 IMB. In multivariable analysis on bursa level, presence of IMB was independently associated with local presence of synovitis and tenosynovitis, with odds ratios (OR) of 1.69 (95% confidence interval [95% CI] 1.12, 2.57) and 2.83 (95% CI 1.80, 4.44), respectively, but not osteitis. On the patient level, IMB presence was most strongly associated with tenosynovitis (OR 2.92 [95% CI 1.62, 5.24]). IMB presence was associated with local joint swelling (OR 2.7 [95% CI 1.3, 5.3]) and tenderness (OR 1.7 [95% CI 1.04, 2.9]) independent of RAMRIS inflammation. During treatment, IMB size decreased between 0 and 12 months. This decrease associated with decrease in RAMRIS inflammation, which was driven by synovitis decrease. Within ACPA-positive and ACPA-negative RA, similar results were obtained. IMB particularly accompanies inflammation of the synovial lining of joints and tendon sheaths, showed a similar treatment response after DMARD initiation, and associates with typical clinical signs. These findings suggest that IMB represents a frequently present novel RA feature of juxtaarticular synovial inflammation.

Efficacy of Abatacept Versus Tumor Necrosis Factor Inhibitors in Anti-citrullinated Protein Antibody-Positive Patients with Rheumatoid Arthritis: Results from a Korean Nationwide Biologics Registry.

Introduction To compare the efficacy of abatacept and tumor necrosis factor inhibitor (TNFi) in patients with anti-citrullinated protein antibody (ACPA)-positive rheumatoid arthritis (RA) and identify those who benefit most from abatacept over TNFi.MethodsThis observational study identified RA patients who were ACPA-positive and initiated abatacept or TNFi from the Korean College of Rheumatology Biologics and Targeted therapy registry. Propensity score (PS) matching was performed to balance baseline confounding in abatacept- or TNFi-treated patients. The major endpoints were changes in Clinical Disease Activity Index (CDAI) and achievement of CDAI remission/low disease activity after 1 year of treatment. Subgroup analysis was mainly performed stratified by prior biologics use.ResultsA total of 291 PS-matched, ACPA-positive RA patients who initiated abatacept (n = 97) and TNFi (n = 194) were included. From baseline CDAI scores of 26.52 in the abatacept group and 26.38 in the TNFi group, the mean changes after 1 year were − 16.78 and − 13.61, respectively (difference − 3.17, p = 0.020). The proportion of patients achieving CDAI remission/low disease activity was 68.0% with abatacept and 52.6% with TNFi (p = 0.013). In the subgroup analysis, patients that were biologics-naïve had better improvement in CDAI after treatment with abatacept than TNFi (difference − 3.35, p = 0.021).ConclusionsThis real-world study suggests that abatacept may have better clinical response compared to TNFi in patients with established ACPA-positive RA, especially in those that were biologics-naïve.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40744-022-00467-4.

Personalized Therapeutic Strategies in the Management of Osteoporosis in Patients with Autoantibody-Positive Rheumatoid Arthritis.

Bone mineral density (BMD) reduction and fragility fractures still represent a major source of morbidity in rheumatoid arthritis (RA) patients, despite adequate control of the disease. An increasing number of clinical and experimental evidence supports the role of autoantibodies, especially anti-citrullinated protein antibodies (ACPAs), in causing localized and generalised bone loss in ways that are both dependent on and independent of inflammation and disease activity. The human receptor activator of nuclear factor kappa B and its ligand—the so-called RANK-RANKL pathway—is known to play a key role in promoting osteoclasts’ activation and bone depletion, and RANKL levels were shown to be higher in ACPA-positive early untreated RA patients. Thus, ACPA-positivity can be considered a specific risk factor for systemic and periarticular bone loss. Through the inhibition of the RANK-RANKL system, denosumab is the only antiresorptive drug currently available that exhibits both a systemic anti-osteoporotic activity and a disease-modifying effect when combined with conventional synthetic or biologic disease-modifying anti-rheumatic drugs (DMARDs). Thus, the combination of DMARD and anti-RANKL therapy could be beneficial in the prevention of fragility fractures and structural damage in the subset of RA patients at risk of radiographic progression, as in the presence of ACPAs.

Serum Antigenome Profiling Reveals Diagnostic Models for Rheumatoid Arthritis

ObjectiveThe study aimed to investigate the serum antigenomic profiling in rheumatoid arthritis (RA) and determine potential diagnostic biomarkers using label-free proteomic technology implemented with machine-learning algorithm.MethodSerum antigens were captured from a cohort consisting of 60 RA patients (45 ACPA-positive RA patients and 15 ACPA-negative RA patients), together with sex- and age-matched 30 osteoarthritis (OA) patients and 30 healthy controls. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was then performed. The significantly upregulated and downregulated proteins with fold change > 1.5 (p < 0.05) were selected. Based on these differentially expressed proteins (DEPs), a machine learning model was trained and validated to classify RA, ACPA-positive RA, and ACPA-negative RA.ResultsWe identified 62, 71, and 49 DEPs in RA, ACPA-positive RA, and ACPA-negative RA, respectively, as compared to OA and healthy controls. Typical pathway enrichment and protein–protein interaction networks were shown among these DEPs. Three panels were constructed to classify RA, ACPA-positive RA, and ACPA-negative RA using random forest models algorithm based on the molecular signature of DEPs, whose area under curve (AUC) were calculated as 0.9949 (95% CI = 0.9792–1), 0.9913 (95% CI = 0.9653–1), and 1.0 (95% CI = 1–1).ConclusionThis study illustrated the serum auto-antigen profiling of RA. Among them, three panels of antigens were identified as diagnostic biomarkers to classify RA, ACPA-positive, and ACPA-negative RA patients.

Exhaled nitric oxide in early rheumatoid arthritis and effects of methotrexate treatment

Patients with established rheumatoid arthritis (RA) and disease modifying treatments have lower nitric oxide (NO) levels in the alveolar compartment (CANO) and in the airway wall (CawNO), but also higher diffusion capacities for NO in the airways (DawNO) compared to matched controls. The aim of the present study was to investigate the NO lung dynamics in patients with recent onset RA before and after immune suppression with methotrexate therapy. Patients with early RA and antibodies against anticitrullinated peptides (ACPA) were recruited. Measurement of exhaled NO and inflammatory markers in serum were performed. Clinical disease activity was evaluated with Disease Activity Score for 28 joints. Healthy individuals were used as matched controls. Data are presented as median (lower quartile, upper quartile) values. RA patients (n = 44) had lower exhaled NO (FENO50) 16 (10–24) ppb compared to controls 21 (15, 29) ppb, p = 0.013. In NO-dynamics, CANO was lower in RA patients 1.6 (1.0, 2.2) ppb compared to the control subjects 2.3 (1.3, 3.1) ppb, p = 0.007. CawNO was also lower in the RA patients 55 (24, 106) ppb compared to control subjects 124 (110, 170) ppb, p < 0.001, but DawNO was higher 17 (8, 30) mL/s and 9 (5, 11) mL/s respectively, p < 0.001. Methotrexate treatment for three months reduced disease activity, but did not change the NO dynamics. In conclusion, the altered NO dynamics of the lung in ACPA-positive RA patients are already present in the early stages of the disease before any treatments and do not change after methotrexate therapy suggesting a role in the pathogenesis.