Seropositive Rheumatoid Arthritis Patients Research Articles

Serum and urine lipidomic profiles identify biomarkers diagnostic for seropositive and seronegative rheumatoid arthritis.

Seronegative rheumatoid arthritis (RA) is defined as RA without circulating autoantibodies such as rheumatoid factor and anti-citrullinated protein antibodies; thus, early diagnosis of seronegative RA can be challenging. Here, we aimed to identify diagnostic biomarkers for seronegative RA by performing lipidomic analyses of sera and urine samples from patients with RA. We performed untargeted lipidomic analysis of sera and urine samples from 111 RA patients, 45 osteoarthritis (OA) patients, and 25 healthy controls (HC). These samples were divided into a discovery cohort (n = 97) and a validation cohort (n = 84). Serum samples from 20 patients with systemic lupus erythematosus (SLE) were also used for validation. The serum lipidome profile of RA was distinguishable from that of OA and HC. We identified a panel of ten serum lipids and three urine lipids in the discovery cohort that showed the most significant differences. These were deemed potential lipid biomarker candidates for RA. The serum lipid panel was tested using a validation cohort; the results revealed an accuracy of 79%, a sensitivity of 71%, and a specificity of 86%. Both seropositive and seronegative RA patients were differentiated from patients with OA, SLE, and HC. Three urinary lipids showing differential expression between RA from HC were identified with an accuracy of 84%, but they failed to differentiate RA from OA. There were five lipid pathways that differed between seronegative and seropositive RA. Here, we identified a panel of ten serum lipids as potential biomarkers that can differentiate RA from OA and SLE, regardless of seropositivity. In addition, three urinary lipids had diagnostic utility for differentiating RA from HC.

Identification of autoantibodies against PsoP27 in synovial fluid derived from psoriatic arthritis and rheumatoid arthritis patients

PsoP27 is an antigen expressed in psoriatic lesions. It plays an inflammatory role in psoriasis. This study objective was to characterize antibodies (Abs) against PsoP27 in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA). Levels of Abs against native and citrullinated PsoP27 in PsA and RA patients’ synovial fluid (SF) and sera were determined by ELISA. SF of osteoarthritis (OA) patients and sera of healthy donors were used as controls. Levels of Abs against PsoP27 were correlated with disease activity scores. Abs against native and citrullinated PsoP27 levels in SF of PsA (n = 48; 0.38 ± 0.03 and 0.44 ± 0.04, respectively) and RA (n = 22; 0.57 ± 0.1 and 0.62 ± 0.09, respectively) were significantly higher than in OA patients (n = 23; 0.14 ± 0.01 and 0.15 ± 0.01, respectively) (p < .0001). For both Abs, there were no significant differences between their level in PsA and RA patients. There was no difference in the level of Abs against citrullinated PsoP27 in SF of seronegative versus seropositive RA patients. Levels of Abs against both native and citrullinated PsoP27 in the SF and level of systemic C-reactive protein in PsA correlated positively, while in RA there were no significant correlations with disease activity scores. No differences in level of Abs against PsoP27 were found in the sera of all three study groups. Abs against native and citrullinated PsoP27 are present in PsA and RA SF but not in those of OA patients, suggesting a potential role of those Abs in inflammatory joint diseases.

Ultrasonographic Evaluation of the Ankle Joint in Relation to Rheumatoid Factor Status and Disease Activity in Patients with Rheumatoid Arthritis

Abstract Background: Rheumatoid arthritis (RA) is a form of inflammatory disease whose clinical pattern is largely dependent on the presence of both anti-citrullinated protein antibodies and rheumatoid factor (RF). Although this is still debatable, seronegative RA seems to be a somewhat less serious condition. The present study aimed to evaluate ankle joint ultrasound in relation to RF status and disease activity in RA patients. Methods: A cross-sectional study involving RA patients from a single center was conducted. Laboratory test evaluations and clinical activity assessments were carried out. The ankle joint was examined using musculoskeletal ultrasound (US). Results: The study included 100 patients with established RA in total. Eighty-two patients tested positive for RF with a mean age of 42.3, whereas only 18 tested negative with a mean age of 39.6. Patients who tested positive for RF had a longer duration of illness (9.39 ± 5.39 vs. 4.56 ± 3.24). There were no differences in clinical activity scores between the seropositive and seronegative groups. The pathological US findings of any ankle joint showed no differences between the seropositive and seronegative groups. Patients with US findings of tibialis posterior tenosynovitis in the left ankle and synovitis and erosion in the right ankle, particularly in the tibiotalar and talonavicular joints, had significantly high Disease Activity Score 28-Erythrocyte sedimentation rate-scores. The increased disease activity was accompanied by significant erosions on both ankles. Conclusion: In terms of disease activity, there is no clinically significant difference between seropositive and seronegative RA patients. Sonographic ankle joint abnormalities do not appear to be associated with the patients’ RF status. High RA disease activity, on the other hand, is associated with synovitis and erosions, particularly in the talonavicular and tibiotalar joints, as well as tibialis posterior tenosynovitis.

Association of HLA-DRB1 locus with treatment response to abatacept or TNF inhibitors in patients with seropositive rheumatoid arthritis

The strongest genetic risk factor for rheumatoid arthritis (RA) has been known as HLA-DRB1 based on amino acid positions 11, 71, and 74. This study analyzed the association between specific HLA-DRB1 locus and treatment response to abatacept or TNF inhibitors (TNFi) in patients with seropositive RA. A total of 374 Korean RA patients were treated with abatacept (n = 110) or TNFi (n = 264). Associations between HLA-DRB1 and treatment response after 6 months were analyzed using multivariable logistic regression. Seropositive RA patients with HLA-DRB1 shared epitope (SE) had a favorable response to abatacept (OR = 3.67, P = 0.067) and an inversely associated response to TNFi (OR 0.57, P = 0.058) based on EULAR response criteria, but the difference was not statistically significant in comparison to those without SE. In analyses using amino acid positions of HLA-DRB1, a significant association was found between valine at amino acid position 11 of SE and good response to abatacept (OR = 6.46, P = 5.4 × 10–3). The VRA haplotype also showed a good response to abatacept (OR = 4.56, P = 0.013), but not to TNFi. Our results suggest that treatment response to abatacept or TNFi may differ depending on HLA-DRB1 locus in seropositive RA, providing valuable insights for selecting optimal therapy.

Type 17-specific immune pathways are active in early spondyloarthritis

ObjectiveUndifferentiated, early inflammatory arthritis (EIA) can differentiate into seropositive or seronegative rheumatoid arthritis (RA), peripheral spondyloarthritis (SpA) or remain as seronegative undifferentiated inflammatory arthritis (UIA). Little is known about immune...

Effectiveness of biological targeted therapies may discriminate seronegative from seropositive rheumatoid arthritis.

To assess the real-world effectiveness of targeting biologic drugs (bDMARD) in rheumatoid arthritis (RA) patients negative for rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA). We retrospectively selected 81 seronegative and 404 seropositive RA patients receiving treatment with abatacept, anti-tumor necrosis factor (TNF) alpha, or tocilizumab. Effectiveness was evaluated by analyzing drug survival using Kaplan-Meyer analysis over 10-year follow-up. Survival rates were compared by log rank test, and hazard ratios (HRs) of therapy discontinuation were estimated through multivariate Cox-regression. Clinical characteristics were similar between the two groups, except for a significantly higher percentage of inadequate responders to prior bDMARDs in the seronegative RA patients (p= 0.02). Among seronegative RA, tocilizumab demonstrated a survival rate of 73.9% with a mean survival time (MST) of 76.8 months (95% CI 61-92), which was significantly higher than abatacept (37.5%, MST 37.1 months (95% CI 22-51; p= 0.01). Anti-TNF alpha therapy fell in the middle (50.0%, MST 63.5 months (95% CI 47-79) but the difference was not significant. Nevertheless, seropositive RA patients did not show significantly different drug survival rates. Negative predictors of drug discontinuation were RF/ACPA positivity (HR 0.56) and sex male (HR 0.58), but treatment with abatacept (HR 1.88) or anti-TNF alpha (HR 1.79), no co-therapy with cDMARD (HR 1.74), absence of bone erosions (HR 1.41), and higher HAQ (HR 1.58) were positive predictors. To confirm these preliminary findings and to explore the hypothesis of a distinctive therapeutic algorithm in seronegative RA, prospective studies on larger cohorts are needed.

In silico analysis of serum miRNA profiles in seronegative and seropositive rheumatoid arthritis patients by small RNA sequencing.

Rheumatoid arthritis (RA) is a refractory autoimmune disease, affecting about 1% of the world's population. RA is divided into seronegative RA and seropositive RA. However, biomarkers for discriminating between seronegative and seropositive RA have not been reported. In this study, we profiled serum miRNAs in seronegative RA patients (N-RA), seropositive RA patients (P-RA) and healthy controls (HC) by small RNA sequencing. Results indicated that compared with HC group, there were one up-regulated and four downregulated miRNAs in N-RA group (fold change ≥ 2 and P value < 0.05); compared with P-RA group, there were two up-regulated and four downregulated miRNAs in N-RA group; compared with HC group, there were three up-regulated and four downregulated miRNAs in P-RA group. Among them, the level of hsa-miR-362-5p in N-RA group was up-regulated compared with that in HC group and P-RA group, and the level of hsa-miR-6855-5p and hsa-miR-187-3p in P-RA group was upregulated compared with that in N-RA group and HC group. Validation by qPCR confirmed that serum hsa-miR-362-5p level was elevated in N-RA group. Subsequently, by analyzing the target genes using RNAhybrid, PITA, Miranda and TargetScan and functions of differential miRNAs utilizing Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), we found that the target genes and molecular pathways regulated by miRNAs in seronegative RA and seropositive RA were roughly the same, and miRNAs in these two diseases may participate in the occurrence and development of diseases by regulating the immune system. In conclusion, this study revealed the profiles of serum miRNAs in seronegative and seropositive RA patients for the first time, providing potential biomarkers and targets for the diagnosis and treatment of seronegative and seropositive RA.

Aberrant B-cell activation and B-cell subpopulations in rheumatoid arthritis: analysis by clinical activity, autoantibody seropositivity, and treatment.

Few studies analyze the role of B-cell subpopulations in rheumatoid arthritis (RA) pathophysiology. Therefore, this study aimed to analyze the differences in B-cell subpopulations and B-cell activation according to disease activity, RA subtype, and absence of disease-modifying antirheumatic drugs (DMARDs) therapy. These subgroups were compared with control subjects (CS). One hundred and thirty-nine subjects were included, of which 114 were RA patients, and 25 were controls. Patients were divided into 99 with seropositive RA, 6 with seronegative RA, and 9 without DMARDs. The patients with seropositive RA were subclassified based on the DAS28 index. A seven-color multicolor flow cytometry panel was used to identify B-cell immunophenotypes and cell activation markers. There were no changes in total B-cell frequencies between RA patients and controls. However, a lower frequency of memory B cells and pre-plasmablasts was observed in seropositive RA compared to controls (P < 0.0001; P = 0.0043, respectively). In contrast, a higher frequency of mature B cells was observed in RA than in controls (P = 0.0002). Among patients with RA, those with moderate activity had a higher percentage of B cells (P = 0.0021). The CD69+ marker was increased (P < 0.0001) in RA compared to controls, while the CD40+ frequency was decreased in patients (P < 0.0001). Transitional, naïve, and double-negative B-cell subpopulations were higher in seronegative RA than in seropositive (P < 0.01). In conclusion, in seropositive and seronegative RA patients, there are alterations in B-cell activation and B-cell subpopulations, independently of clinical activity and DMARDs therapy.

Hand and Wrist Involvement in Seropositive Rheumatoid Arthritis, Seronegative Rheumatoid Arthritis, and Psoriatic Arthritis—The Value of Classic Radiography

The hand and wrist are among the most common anatomical areas involved in rheumatic diseases, especially seropositive and seronegative rheumatoid arthritis (RA) and psoriatic arthritis (PsA). The purpose of this study was to identify the most differentiating radiographic characteristics of PsA, seropositive RA, and seronegative RA, particularly in the early stages. A retrospective analysis of radiographic hand findings was performed on 180 seropositive RA patients (29 males, 151 females, mean age at the point of acquisition of the analyzed radiograph of 53.4 y/o, SD 12.6), 154 PsA patients (45 males, 109 females, age median of 48.1 y/o, SD 12.4), and 36 seronegative RA patients (4 males, 32 females, age median of 53.1 y/o, SD 17.1) acquired during the period 2005-2020. Posterior-anterior and Nørgaard views were analyzed in all patients. The radiographs were evaluated for three radiographic findings: type of symmetry (asymmetric/bilateral/changes in corresponding joint compartments/'mirror-image' symmetry), anatomic location (e.g., wrist, metacarpophalangeal (MCP), proximal interphalangeal (PIP), distal interphalangeal (DIP) joints), and type of lesions (e.g., juxta-articular osteoporosis, bone cysts, erosions, proliferative bone changes). The study showed that symmetric distribution of lesions defined as 'lesions present in corresponding compartments' was more suggestive of seropositive or seronegative RA than PsA. Lesions affecting the PIP joints, wrist, or styloid process of the radius; juxta-articular osteoporosis, joint space narrowing, joint subluxations, or dislocations were more common in patients with seropositive RA than in those with PsA, whereas DIP joints' involvement and proliferative bone changes were more likely to suggest PsA than seropositive RA. Lesions in PIP, MCP, and wrist joints, as well as erosions, advanced bone damage, joint subluxations, dislocations, and joint space narrowing, were more common in seropositive RA patients than in seronegative RA patients. The ulnar styloid was more commonly affected in seronegative RA patients than in PsA patients. The study confirmed that types of bone lesions and their distribution in the hands and wrists can be useful in differentiating seropositive RA from PsA and suggests that seronegative RA varies in radiological presentation from seropositive RA and PsA.

Incidence of seropositive rheumatoid arthritis in population-based studies in Northern Savo, Finland, during 1980–2020

The objective is to evaluate the incidence of seropositive rheumatoid arthritis (RA) over 40-year period in Northern Savo, Finland. Data on new seropositive RA patients according to the American College of Rheumatology (ACR) 1987 classification criteria were collected in 2020–2021. In 2020 data on tobacco exposure, patient-reported dental health and living in residences with fluoridated tap water were gathered. Incidence rates were estimated and age- and gender-adjusted to Northern Savo population. The results were compared with data acquired in studies from 1980, 1990, 2000, and 2010. In 2020, 46 seropositive RA patients (21 females and 25 males) were recorded. The crude incidence of seropositive RA fulfilling the ACR 87 criteria in 2020 was 22.3 (95% CI 16.3 to 29.8)/100 000 and age and gender-adjusted 22.3 (95% CI 15.9 to 28.8)/100 000. Tobacco exposure > 5 pack years occurred 18% of females and 56% of males. Only 16% of males were full dentate. A total of 242 incident seropositive RA (age ≥ 16 years, 55% females) were identified in all study years. No differences in the gender-specific incidence rates in each cohort or in incidence between the studies every 10 years were recorded. The incidence of seropositive RA decreased in the age group < 55 years, p = 0.003. There was no change in the incidence of seropositive RA between genders or the study years. A declining trend for occurrence of seropositive RA in the young and early middle-aged population may reflect change in risk factors.

Dynamics of circulating follicular helper T cell subsets and follicular regulatory T cells in rheumatoid arthritis patients according to HLA-DRB1 locus.

B cells, follicular helper T (Tfh) cells and follicular regulatory T (Tfr) cells are part of a circuit that may play a role in the development or progression of rheumatoid arthritis (RA). With the aim of providing further insight into this topic, here we evaluated the frequency of different subsets of Tfh and Tfr in untreated and long-term treated RA patients from a cohort of Argentina, and their potential association with particular human leukocyte antigen (HLA) class-II variants and disease activity. We observed that the frequency of total Tfh cells as well as of particular Tfh subsets and Tfr cells were increased in seropositive untreated RA patients. Interestingly, when analyzing paired samples, the frequency of Tfh cells was reduced in synovial fluid compared to peripheral blood, while Tfr cells levels were similar in both biological fluids. After treatment, a decrease in the CCR7loPD1hi Tfh subset and an increase in the frequency of Tfr cells was observed in blood. In comparison to healthy donors, seropositive patients with moderate and high disease activity exhibited higher frequency of Tfh cells while seropositive patients with low disease activity presented higher Tfr cell frequency. Finally, we observed that HLA-DRB1*09 presence correlated with higher frequency of Tfh and Tfr cells, while HLA-DRB1*04 was associated with increased Tfr cell frequency. Together, our results increase our knowledge about the dynamics of Tfh and Tfr cell subsets in RA, showing that this is altered after treatment.

Fibromyalgia Concomitant with Seropositive Rheumatoid Arthritis in a Tertiary Hospital in South-Western Saudi Arabia: Prevalence and Treatment Patterns

Introduction: Rheumatoid arthritis (RA) patients with fibromyalgia syndrome (FMS) report worse functional status and quality of life hence the association has important clinical implications. FMS can be challenging to treat, and the current evidence recommends a multidisciplinary treatment approach focused on symptom management. Aim: Information regarding the current prevalence of FMS in RA patients is lacking. Thus, this study aims to address the prevalence and predictors of FMS in seropositive RA patients and demonstrate our clinical practice in the management of FMS. Methods: Participants’ data was gathered from Aseer central hospital (ACH) rheumatology clinics and daycare units over a period of 2 years. Subjects were assessed using the 2010 American College of Rheumatology (ACR) criteria for FMS. Data were collected from medical records, including patient demographics, comorbidities and concomitant FMS-related data. Results: Out of 310 seropositive RA patients, 15% (n = 47) fulfilled the diagnostic criteria for FMS. Of them, 29, 11 and 7 were on pregabalin, amitriptyline and duloxetine, respectively. Half of FMS patients showed one or more therapy changes. A significant difference between RA patients with and without concomitant FMS was observed, including age, gender and comorbidities. Conclusion: In this retrospective study, a high prevalence of FMS in individuals with seropositive RA was identified. This study explores real-world practice in the treatment of FMS with remarkable findings regarding underdosing and lower discontinuation rate of pregabalin.

Influence of periodontitis on levels of autoantibodies in rheumatoid arthritis patients: A systematic review.

Periodontitis (PD) is a dysbiotic disease of tooth-supporting structures that has been associated with various systemic diseases including rheumatoid arthritis (RA). To date, evidence demonstrated increased prevalence of RA among PD patients and postulated PD to have a role in the development of autoantibodies in RA patients. Therefore, a systematic review was conducted to assess the available evidence to ascertain the effect of PD on levels of autoantibodies in the serum, saliva and gingival crevicular fluid (GCF) of RA patients. The systematic review was conducted in compliance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. Relevant literature was searched from PubMed, Web of Science, Scopus and Ebscohost databases from inception until 31 August 2020. The risk of bias in each study was determined based on the Newcastle-Ottawa Scale tool. Results from random-effect meta-analyses were presented as summary estimates of odds ratios (ORs) for seropositivity and standardised mean difference (SMD) of autoantibody levels with 95% confidence intervals. Sensitivity tests and meta-regression were performed to assess the robustness of the results and potential cause of heterogeneity. The electronic and manual searches gathered 932 articles. Following screening and full-text assessment, a total of 29 studies were included in the analysis. Twenty-eight published observational studies were included in the quantitative analysis in the form of random-effect meta-analysis which revealed that PD was associated with anti-citrullinated proteins autoantibodies (ACPAs) and Rheumatoid Factor (RF) seropositive RA patients (OR for ACPA seropositivity: 1.82; 95% CI: 1.13-2.93) (OR for RF seropositivity: 1.53; 95% CI: 1.05-2.24). Also, RA patients with PD had increased serum levels of ACPA and RF. However, high heterogeneity among studies' results, partially ascribed to the unstandardised case definition of PD and laboratory testing of autoantibodies. Apart from ACPA and RF in serum, studies which reported on other RA-related autoantibodies, as well as autoantibody levels in saliva and GCF were scarce. RA patients with PD tend to have greater ACPA and RF levels in their serum when compared with the RA patients without PD supporting the plausible role of PD in the development of systemic autoimmunity in RA patients.

Low Serum BAFF Concentration Is Associated with Response to TNF Inhibitors in Seropositive Patients with Rheumatoid Arthritis.

We investigated B-cell-activating factor (BAFF) in relation to response to treatment with TNF inhibitors (TNFis) in rheumatoid arthritis (RA). This was a longitudinal study including 158 patients with RA treated with TNFis and followed up for 6 months. Clinical response at 6 months of treatment was defined according to the EULAR criteria for good responders (GRs). BAFF concentration was measured in serum samples, collected at baseline and at 6 months. Associations with EULAR response were evaluated using univariable and multivariable logistic regression models. ROC analysis was performed to determine the optimal threshold of serum BAFF concentration associated with good EULAR response to treatment. After 6 months of TNFi treatment, 24% of patients were GRs. They had a lower BMI, lower baseline DAS28 and lower baseline serum BAFF concentration than non-responders. After 6 months of TNFi treatment, autoantibody-positive patients who attained GR had significantly lower serum BAFF concentrations compared with patients who did not. Serum BAFF < 968 pg/mL at 6 months represented the concentration likely to best discriminate between GR and non-GR at 6 months of TNFi treatment. Autoantibody-seropositive patients who had serum BAFF < 968 pg/mL at 6 months demonstrated a more than four-fold increased probability to be GRs compared with patients with higher BAFF concentrations. In conclusion, serum BAFF concentrations were associated with response to TNFis in seropositive RA patients, corroborating the importance of the B-cell compartment in RA.

Weight Gain in Seropositive Rheumatoid Arthritis Patients Treated With Anti-tumor Necrosis Factor (TNF) Therapy.

IntroductionRheumatoid arthritis and its treatment have different effects on weight gain. This study examined the effect of tumor necrosis factor (TNF) inhibitors on weight gain in patients with seropositive rheumatoid arthritis compared with non-TNF therapy and disease activity.MethodsA retrospective cohort study was conducted in Prince Mohammad bin Abdulaziz Hospital for all patients aged ≥ 18-year-old diagnosed with seropositive rheumatoid arthritis and started on TNF inhibitors or non-TNF biologics in outpatient clinics since 2015. Patients were excluded if they were pregnant, had an uncontrolled underlying metabolic disease, were post-bariatric, or had a history of malabsorption. We also excluded individuals on treatment for congestive heart failure or end-stage renal disease.ResultsA total of 116 patients with rheumatoid arthritis were reviewed between 2015 and 2019. Only 69 patients met the inclusion criteria (51 and 18) in the TNF-a (alpha) and non-TNF-a inhibitor groups, respectively. The weight change from pre-treatment to post-treatment showed an average increase of 1.2 kg (95% CI: -0.68-3.17) in the TNF-a inhibitor group while in the non- TNF-a inhibitor group, the average increase in weight was 2.67 kg (95% CI: -0.44-5.78). Over the period of two years, there was no statistical difference in weight gain in both groups or in relation to disease activity.ConclusionThe results of this study did not show a significant increase in weight gain in seropositive patients with rheumatoid arthritis who were treated with TNF or non-TNF inhibitors.

POS0596 SERUM CHOLESTEROL LOADING CAPACITY ON MACROPHAGES IS LINKED TO OXIDIZED LOW-DENSITY LIPOPROTEIN AND REGULATED BY SEROPOSITIVITY AND C-REACTIVE PROTEIN IN PATIENTS WITH RHEUMATOID ARTHRITIS

BackgroundExcessive cholesterol accumulation in macrophages underlies foam cell formation, initiation and progression of atherosclerosis. LDL oxidation and unregulated uptake of oxidized LDL by macrophages are critical in foam cell development. Cholesterol loading capacity (CLC) is the ability of serum to deliver cholesterol to cells and is related to foam cell formation. Rheumatoid arthritis (RA) serum increased cholesterol content in macrophages and promoted foam cell formation significantly more than control serum1. Although inflammation, LDL oxidation and antibodies to oxidized LDL (anti-oxLDL) may be higher in RA, their relationships and their individual and synergistic contributions to CLC in RA are unknown.ObjectivesTo explore determinants and moderators of serum CLC in patients with RA. We also investigated whether oxidized LDL influences CLC directly or indirectly through anti-oxLDL IgG and proprotein convertase subtilisin/Kexin type-9 (PCSK9), independently or conditionally on RA-related autoantibodies such as rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) or level of inflammation.MethodsIn an observational study of 104 patients, CLC was measured fluorimetrically as intracellular cholesterol content in human THP-1-derived macrophages after incubation with patient serum. Oxidized LDL was measured as oxidized phospholipids on apoB100 particles (oxPL-apoB100). Anti-oxLDL, PCSK9 and C-reactive protein (CRP) were also quantified. Associations of oxPL-apoB100, anti-oxLDL IgG and PCSK9 with CLC were examined with multivariable linear regression. A two-stage dual moderated mediation model explored whether an indirect association of oxPL-apoB100 with CLC through parallel mediators anti-oxLDL IgG and PCSK9 varied as a function of moderators CRP and RF/ACPA positivity.ResultsOxPL-apoB100, anti-oxLDL IgG and PCSK9 positively associated with CLC (all adjusted p&lt;0.020). In the final dual moderated mediation model oxPL-apoB100 was directly linked to CLC only in dual seropositive patients (unstandardized b [95% bootstrap confidence interval]=2.08 [0.38-3.79], Figure 1). An indirect effect of oxPL-apoB100 on CLC through anti-oxLDL IgG was present and increased along with level of CRP (index of moderated mediation=0.55 [0.05-1.17]). CRP also moderated the other indirect effect of oxPL-apoB100 on CLC through PCSK9, but only in dual seropositive patients (conditional indirect effect=0.64 [0.13-1.30]).ConclusionOxidized LDL can directly influence CLC in dual seropositive RA patients, regardless of CRP. This suggests that targeting LDL oxidation in addition to inflammation may enable a more comprehensive reduction of atherosclerotic risk in these patients. Depending on CRP level, oxidized LDL also affected CLC indirectly via anti-oxLDL IgG and via PCSK9 in dual seropositive patients. If externally validated, our findings may have clinical implications for cardiovascular risk stratification and prevention.

Study of Plasma Anti-CD26 Autoantibody Levels in a Cohort of Treatment-Naïve Early Arthritis Patients

In rheumatoid arthritis (RA), the identification of biomarkers to adjust treatment intensity and to correctly diagnose the disease in early stages still constitutes a challenge and, as such, novel biomarkers are needed. We proposed that autoantibodies (aAbs) against CD26 (DPP4) might have both etiological importance and clinical value. Here, we perform a prospective study of the potential diagnostic power of Anti-CD26 aAbs through their quantification in plasmas from 106 treatment-naïve early and undifferentiated AR. Clinical antibodies, Anti-CD26 aAbs, and other disease-related biomarkers were measured in plasmas obtained in the first visit from patients, which were later classified as RA and non-RA according to the American College of Rheumatology criteria. Two different isotype signatures were found among ten groups of patients, one for Anti-CD26 IgA and other for Anti-CD26 IgG and IgM isotypes, both converging in patients with arthritis (RA and Unresolved Undifferentiated Arthritis: UUA), who present elevated levels of all three isotypes. The four UUA patients, unresolved after two years, were ACPA and rheumatic factor (RF) negatives. In the whole cohort, 51.3% of ACPA/RF seronegatives were Anti-CD26 positives, and a similar frequency was observed in the seropositive RA patients. Only weak associations of the three isotypes with ESR, CRP and disease activity parameters were observed. Anti-CD26 aAbs are present in treatment-naïve early arthritis patients, including ACPA and RF seronegative individuals, suggestive of a potential pathogenic and/or biomarker role of Anti-CD26 aAbs in the development of rheumatic diseases.

Metabolomics of Synovial Fluid and Infrapatellar Fat Pad in Patients with Osteoarthritis or Rheumatoid Arthritis

Osteoarthritis (OA) and autoimmune-driven rheumatoid arthritis (RA) are inflammatory joint diseases with complex and insufficiently understood pathogeneses. Our objective was to characterize the metabolic fingerprints of synovial fluid (SF) and its adjacent infrapatellar fat pad (IFP) obtained during the same surgical operation from OA and RA knees. Non-targeted metabolite profiling was performed for 5 non-inflammatory trauma controls, 10 primary OA (pOA) patients, and 10 seropositive RA patients with high-resolution mass spectrometry-based techniques, and metabolites were matched with known metabolite identities. Groupwise differences in metabolic features were analyzed with the univariate Welch’s t-test and the multivariate linear discriminant analysis (LDA) and principal component analysis (PCA). Significant discrimination of metabolite profiles was discovered by LDA for both SF and IFP and by PCA for SF based on diagnosis. In addition to a few drug-derived substances, there were 16 and 13 identified metabolites with significant differences between the diagnoses in SF and IFP, respectively. The pathways downregulated in RA included androgen, bile acid, amino acid, and histamine metabolism, and those upregulated included biotin metabolism in pOA and purine metabolism in RA and pOA. The RA-induced downregulation of androgen and bile acid metabolism was observed for both SF and IFP. The levels of 11 lipid metabolites, mostly glycerophospholipids and fatty acid amides, were also altered by these inflammatory conditions. The identified metabolic pathways could be utilized in the future to deepen our understanding of the pathogeneses of OA and RA and to develop not only biomarkers for their early diagnosis but also therapeutic targets.

Increased synovial galectin-3 induce inflammatory fibroblast activation and osteoclastogenesis in patients with rheumatoid arthritis

Objective Galectin-3 (Gal-3) has been suggested as a proinflammatory mediator in rheumatoid arthritis (RA). We aimed to study clinical and pathogenic aspects of Gal-3 in RA. Method Plasma samples from healthy controls (n = 48) and patients with newly diagnosed, early RA were assayed for soluble Gal-3. In patients with chronic RA (n = 18), Gal-3 was measured in both plasma and synovial fluid. Synovial fluid mononuclear cells were used to purify fibroblast-like synoviocytes (FLSs) and osteoclasts. Monocultures of FLSs and autologous co-cultures of FLSs and peripheral blood mononuclear cells were established and co-incubated with a Gal-3 inhibitor. Results Patients with early and chronic RA had persistently increased plasma levels of Gal-3 compared with controls. However, changes in plasma Gal-3 at the level of individuals were associated with long-term disease activity. In seropositive early RA patients, all patients with decreasing plasma Gal-3 from 0 to 3 months had low disease activity after 2 years (p < 0.05). Gal-3 levels in synovial fluid were markedly elevated. In vitro, co-incubation with a Gal-3 inhibitor (GB1107, 10 µM) led to a significant reduction in both interleukin-1β and tumour necrosis factor-α secretion from FLS monocultures (both p < 0.05) and decreased monocyte-derived osteoclastogenesis compared with controls (both p < 0.05). Conclusions Our findings underscore the role of Gal-3 regarding disease activity and tissue destruction in RA. An initial decrease in plasma Gal-3 levels predicted decreased long-term disease activity. Correspondingly, a Gal-3 inhibitor decreased the activity of inflammatory FLSs and osteoclastogenesis in patients with RA.

ITRAQ-based proteomic analysis of differentially expressed proteins in sera of seronegative and seropositive rheumatoid arthritis patients.

ObjectiveThe diagnosis of seronegative rheumatoid arthritis (SNRA) is often difficult due to the unavailability of reliable laboratory markers. The aim of this study was to identify differentially expressed proteins in sera of SNRA, seropositive RA (SPRA), and healthy donors (HD).MethodsA total of 32 seropositive RA patients, 32 SNRA patients, and 35 HD were enrolled in our study. Differentially expressed proteins between 3 groups were identified via isobaric tags for relative and absolute quantitation (iTRAQ)‐based proteomic analysis, and an ELISA test was used for the validation test. Correlation analysis was conducted by GraphPad Prism.ResultsUsing iTRAQ quantitative proteomics, we identified 14 proteins were significantly different between SPRA and SNRA, including 4 upregulated proteins and 10 downregulated proteins. Four differentially expressed proteins were validated by ELISA test, and the results showed that SAA1 protein was significantly higher in SPRA and SNRA patients compared with HD, and PSME1 was elevated in SPRA patients. What's more, SAA1 was increased in the anti‐CCP or RF high‐level group in RA patients, and PSME1 was increased in the RF high‐level group. Alternatively, SAA1 was positively correlated with inflammation indicators in RA patients, while PSME1 showed no correlation with inflammation indicators.ConclusionsiTRAQ proteomic approaches revealed variations in serum protein composition among SPRA patients, SNRA patients, and HD and provided new idea for advanced diagnostic methods and precision treatment of RA.