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Objectives: To determine the risk factors for mortality in Korean patients with rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) in comparison to patients with RA but without ILD (RA-nonILD)., Methods: Data were extracted from a single-centre prospective cohort of RA patients with a chest computed tomography scan at an academic referral hospital in Korea. Patients with RA-ILD enroled between May 2017 and August 2022 were selected, and those without ILD were selected as comparators. The mortality rate was calculated, and the causes of each death were investigated. We used Cox proportional hazard regression with Firth's penalised likelihood method to identify the risk factors for mortality in patients with RA-ILD., Results: A total of 615 RA patients were included: 200 with ILD and 415 without ILD. In the RA-ILD group, there were 15 deaths over 540.1 person-years (PYs), resulting in mortality rate of 2.78/100 PYs. No deaths were reported in the RA-nonILD group during the 1669.9 PYs. The primary causes of death were infection (nine cases) and lung cancer (five cases), with only one death attributed to ILD aggravation. High RA activity (adjusted HR 1.87, CI 1.16-3.10), baseline diffusing capacity for carbon monoxide (DLCO) < 60% (adjusted HR 4.88, 95% CI 1.11-45.94), and usual interstitial pneumonia (UIP) pattern (adjusted HR 5.13, 95% CI 1.00-57.36) were identified as risk factors for mortality in RA-ILD patients., Conclusion: Patients with RA-ILD have an elevated risk of mortality compared with those without ILD. Infection-related deaths are the main causes of mortality in this population. High RA activity, low DLCO, and the UIP pattern are significantly associated with the mortality in patients with RA-ILD., (© 2024. The Author(s).)

Background/aims: This cross-sectional study aimed to investigate biologics treatment disparities in rheumatoid arthritis (RA) patients based on socioeconomic status (SES)., Methods: Data from the KOrean Observational Study Network for Arthritis (KORONA) database were analyzed to assess various factors associated with SES, health behaviors, and biologics use. Logistic regression and structured equation modeling (SEM) were utilized for data analysis., Results: Among 5,077 RA patients included, 393 (7.7%) patients were identified as biologics users. Within the entire cohort, 31.8% of the participants were in the low-income and low-education groups, and 39.3% of the participants were in the high-income and high-education groups. Despite the patients with low income or low education experienced higher disease activity at diagnosis, had more comorbidities, exhibited higher medication compliance, underwent more check-ups, and had more hospital admissions than their counterparts, the odds of patients with low-income receiving biologics were 34% lower (adjusted odds ratio = 0.76, 95% confidence interval: 0.60-0.96, p = 0.021) after adjustment for demographics and comorbidities. SEM and pathway analyses confirmed the negative impact of low SES on biologics use., Conclusion: The findings suggest that SES plays a significant role in biologics use among RA patients, indicating potential healthcare inefficiencies for low SES patients. Moreover, adverse healthcare habits negatively affect biologics use in RA patients. The study highlights the importance of considering socioeconomic factors while discussing biologics use and promoting equitable access to biologics for optimal RA management.

Background/aims: We aimed to compare the effectiveness and safety of Janus kinase inhibitors (JAKi) vs. biologic disease- modifying antirheumatic drugs (bDMARD) in Korean patients with rheumatoid arthritis (RA) who had an inadequate response to conventional synthetic DMARDs., Methods: A quasi-experimental, multi-center, prospective, non-randomized study was conducted to compare response rates between JAKi and bDMARDs in patients with RA naïve to targeted therapy. An interim analysis was performed to estimate the proportion of patients achieving low disease activity (LDA) based on disease activity score (DAS)-28- erythroid sedimentation rate (ESR) (DAS28-ESR) at 24 weeks after treatment initiation and to evaluate the development of adverse events (AEs)., Results: Among 506 patients enrolled from 17 institutions between April 2020 and August 2022, 346 (196 JAKi group and 150 bDMARD group) were included in the analysis. After 24 weeks of treatment, 49.0% of JAKi users and 48.7% of bDMARD users achieved LDA (p = 0.954). DAS28-ESR remission rates were also comparable between JAKi and bDMARD users (30.1% and 31.3%, respectively; p = 0.806). The frequency of AEs reported in the JAKi group was numerically higher than that in the bDMARDs group, but the frequencies of serious and severe AEs were comparable between the groups., Conclusion: Our interim findings reveal JAKi have comparable effectiveness and safety to bDMARDs at 24 weeks after treatment initiation.

We aimed to determine the risk of herpes zoster (HZ) in Korean rheumatoid arthritis (RA) patients on tofacitinib compared with tumor necrosis factor inhibitor (TNFi) treatment. From the prospective cohorts of RA patients who started tofacitinib or TNFi in an academic referral hospital in Korea, patients who started tofacitinib between March 2017 and May 2021 and those who started TNFi between July 2011 and May 2021 were included. Baseline characteristics of tofacitinib and TNFi users were balanced through inverse probability of treatment weighting (IPTW) using the propensity score including age, disease activity of RA and medication use. The incidence rate of HZ in each group and incidence rate ratio (IRR) were calculated. A total of 912 patients were included: 200 tofacitinib and 712 TNFi users. There were 20 cases of HZ among tofacitinib users and 36 among TNFi users during observation period of 331.4 person-years (PYs) and 1950.7 PYs, respectively. In IPTW analysis with a balanced sample, IRR of HZ was 8.33 (95% confidence interval 3.05-22.76). Tofacitinib use increased the risk of HZ compared with TNFi in Korean patients with RA, but the rate of serious HZ or permanent discontinuation of tofacitinib due to HZ event was low., (© 2023. The Author(s).)

Background: To introduce a prospective cohort for rheumatoid arthritis (RA) patients with interstitial lung disease (ILD) and to identify their clinical features in comparison with RA patients without ILD., Methods: Using a multidisciplinary collaborative approach, a single-center cohort for RA patients with ILD (RA-ILD) was established in May 2017, and enrolment data from May 2017 to March 2021 were used to compare the clinical features of RA patients without ILD (RA-non ILD). Multivariable logistic regression analysis was used to identify factors associated with ILD in RA patients., Results: Among 148 RA-ILD and 410 RA-non ILD patients, participants in the RA-ILD group were older (65.8 ± 9.9 vs. 58.0 ± 10.4 years, P < 0.001) and included more males (35.8% vs. 14.6%, P < 0.001) than in the RA-non ILD group. The RA-ILD group had a higher proportion of late-onset RA patients (age ≥ 60 years) than in the comparator group (43.9% vs. 14.2%, P < 0.001). Multivariable logistic regression analysis showed that higher age at RA onset (OR 1.056, 95% CI 1.021-1.091), higher body mass index (BMI; OR 1.65, 95% CI 1.036-2.629), smoking history (OR 2.484, 95% CI 1.071-5.764), and oral glucocorticoid use (OR 3.562, 95% CI 2.160-5.874) were associated with ILD in RA patients, whereas methotrexate use was less likely to be associated with ILD (OR 0.253, 95% CI 0.155-0.412)., Conclusions: Higher age at RA onset, smoking history, and higher BMI were associated with the presence of ILD among RA patients. Oral glucocorticoids were more frequently used whereas methotrexate was less likely to be used in RA-ILD patients., (© 2023. The Author(s).)

Objective: Deciding which drug to choose for targeted therapy is an important step in sequential treatment for rheumatoid arthritis (RA). This study aimed to identify factors for selecting Janus kinase inhibitors (JAKis) rather than biologic disease-modifying antirheumatic drugs (bDMARDs) in patients with RA in real-world practice., Methods: We selected RA patients starting JAKis or bDMARDs from single-center prospective cohorts in Korea. Patients were divided into JAKi, tumor necrosis factor (TNF) inhibitor, and non-TNF inhibitor groups. We performed multinomial logistic regression analyses to identify factors associated with selecting JAKis., Results: 145, 205, and 89 patients were included in the JAKi, TNF inhibitor, and non-TNF inhibitor groups. In multinomial regression analysis, the JAKi group was older than the TNF inhibitor group (OR 1.03, 95% confidence interval [CI] 1.01-1.05) but younger than the non-TNF inhibitor group (OR 0.97, CI 0.95-1.00). The JAKi group was less likely to have chronic pulmonary diseases compared with the TNF inhibitor group (OR 0.07, CI 0.01-0.56) or the non-TNF inhibitor group (OR 0.06, CI 0.01-0.50). Higher disease activity assessed by physician (OR 1.80, CI 1.51-2.38) and previous tacrolimus use (OR 2.05, CI 1.20-3.51) were factors suggesting selection of JAKis than TNF inhibitors., Conclusion: Age, pulmonary comorbidities, previous tacrolimus use, and high disease activity assessed by physician were factors influencing the selection of JAKis for RA patients in Korea., Competing Interests: DHY has received research grants from Celltrion, has served as a consultant for Celltrion, and is on the speakers’ bureau of Celltrion and Celltrion Healthcare. YKS has received research grants from Bristol-Myers Squibb, Eisai, Pfizer, and JW Pharmaceutical. There are no patents, and no products in development or being marketed to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials. Other authors declare no conflicts of interest., (Copyright: © 2023 Song et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Extracellular PKM2 (exPKM2) levels have been reported to be increased in several cancers and inflammatory diseases, including rheumatoid arthritis (RA). This study aimed to investigate the association of circulating exPKM2 levels with radiographic progression in RA patients and the effect of exPKM2 on osteoclastogenesis. Plasma and synovial fluid exPKM2 levels were significantly elevated in RA patients. Plasma exPKM2 levels were correlated with RA disease activity and were an independent predictor for radiographic progression in RA patients with a disease duration of ≤ 12 months. CD14 + monocytes but not RA fibroblast-like synoviocytes secreted PKM2 upon stimulation with inflammatory mediators. Recombinant PKM2 (rPKM2) increased the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells and resorption pit in osteoclast precursors, dose-dependently, even in the absence of receptor activator of nuclear factor-kappa B ligand (RANKL). rPKM2 treatment upregulated the expression of dendrocyte-expressed seven transmembrane protein (DC-STAMP) and MMP-9 via the ERK pathway. Although rPKM2 did not directly bind to RAW264.7 cells, extracellular application of pyruvate, the end-product of PKM2, showed effects similar to those seen in rPKM2-induced osteoclastogenesis. These results suggest that exPKM2 is a potential regulator of RA-related joint damage and a novel biomarker for subsequent radiographic progression in patients with early-stage RA., (© 2022. The Author(s).)

Objective: To determine the risk of herpes zoster (HZ) in Korean patients with rheumatoid arthritis (RA) receiving Janus kinase inhibitors (JAKis)., Methods: We performed a nested case-control study with 1:10 matching for sex and age using single-centre prospective cohorts of patients with RA receiving targeted therapy in Korea. Then we performed conditional logistic regression analyses to determine the risk associated with JAKi use compared with biologic disease-modifying antirheumatic drug (bDMARD) use, with adjusting for various factors. We also used logistic regression analysis to identify other risk factors for the development of HZ in JAKi users., Results: From a total of 1147 patients, 61 cases and 610 matched controls were selected. In conditional logistic regression analysis, JAKi use did not increase the risk of HZ development (OR 1.35, 95% CI 0.70 to 2.61) after adjusting for other factors. Rather, duration of RA less than 10 years (OR 0.54, 95% CI 0.30 to 0.97) and having had three or more previous targeted therapies (OR 5.29, 95% CI 1.45 to 19.31) were risk factors for HZ. Among JAKi users, higher disease activity score 28-erythrocyte sedimentation rate (DAS28-ESR) (OR 1.44, 95% CI 1.06 to 1.97) was identified as a risk factor in addition to three or more previous targeted therapies (OR 10.12, 95% CI 1.92 to 53.49)., Conclusions: The number of previous targeted therapies, but not JAKi use, was identified as a risk factor for HZ development in Korean patients with RA in a real-world setting. High disease activity was an additional risk factor for JAKi users., Competing Interests: Competing interests: Y-KS has received research grants from Bristol-Myers Squibb, Eisai, Pfizer and JW Pharmaceutical. Other authors declare that there is no conflict of interest., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Patients with rheumatoid arthritis (RA) undergoing targeted therapy have a higher risk of developing tuberculosis (TB). This requires diagnosis and treatment of latent tuberculosis infection (LTBI). We aimed to evaluate whether diagnosis and treatment of LTBI in RA are effective in Korea, and to estimate the risk of TB development by calculating the incidence rate of active TB among RA patients receiving targeted therapy., Methods: We analyzed data from two prospective cohort studies of RA patients who received biologic disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase (JAK) inhibitor. We selected new starters of targeted therapy and classified them into three groups receiving tumor necrosis factor (TNF) inhibitor, non-TNF inhibitor, and JAK inhibitor, respectively. We then compared LTBI prevalence, treatments, and active TB incidence during first-line therapy in each group., Results: A total of 765 RA patients (574 TNF inhibitor users, 132 non-TNF inhibitor users, and 59 JAK inhibitor users) were included in this study. Observation periods were 1,255.2 person-years (PYs), 264.7 PYs, and 53.3 PYs, respectively. All 765 patients underwent LTBI screening, and the positivity rate was 26.5% (n = 203). Of the 203 LTBI-positive patients, 189 (93.1%) received treatment. Only one patient, who was in the TNF inhibitor group, and was negative for the interferon gamma release assay (IGRA), did not receive LTBI treatment and developed active TB during follow-up., Conclusion: Although the prevalence of LTBI in RA patients who started targeted therapy was slightly elevated, the Korean guidelines specifying LTBI screening and treatment were effective in preventing latent TB from becoming active., Competing Interests: DHY received research grants from Celltrion and HR, and is on the speakers bureau of Celltrion and Celltrion Healthcare. YKS received research grants from Bristol-Myers Squibb, Eisai, Pfizer, and JW Pharmaceutical. YJS, SKC, HK, HWK, EN, and SCB have no disclosures to declare. All authors declare no conflict of interest associated with this work., (© 2021 The Korean Academy of Medical Sciences.)

Background: To estimate the prevalence of Sjögren's syndrome (SS) in patients with rheumatoid arthritis (RA) and to compare the clinical features of RA patients with and without SS., Methods: We conducted a retrospective study of RA patients who visited a rheumatology clinic in a tertiary referral hospital in Korea between May 20 and July 22, 2016. All patients fulfilled the classification criteria for RA, and the diagnosis of SS was made clinically by rheumatologists and according to the 2002 American-European Consensus Group (AECG), 2012 American College of Rheumatology (ACR), and 2016 ACR/European League Against Rheumatism (EULAR) classification criteria. The prevalence was estimated as the number of SS patients within the total number of RA patients. The disease activity and treatment pattern of RA were compared between patients with and without SS., Results: Among 827 RA patients, 72 patients (8.7%) were diagnosed with SS by a rheumatologist, though only 60 patients (7.3%) satisfied the 2002 AECG classification criteria for SS. Fifty-two patients (6.3%) and 56 patients (6.8%) fulfilled the 2012 ACR and 2016 ACR/EULAR classification criteria, respectively. The prevalence of SS in RA patients was 10.5%, 17.0%, and 67.6% in rheumatoid factor, antinuclear antibody (≥ 1:80), and anti-Ro antibody positive patients, respectively., Conclusion: The prevalence of SS among RA patients was 8.7% according to rheumatologists' diagnosis. The presence of SS did not affect the treatment patterns of RA patients. However, the autoantibody profiles and demographics of RA patients with SS differed from those of patients without SS., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2020 The Korean Academy of Medical Sciences.)

The objective of this study is to investigate whether the type of biologics (TNFi or others) or type of rheumatic diseases (RA or AS) influence the conversion rate of initially negative tuberculosis (TB) screening test results. A total of 119 patients with RA or AS who had negative baseline interferon-γ release assay (IGRA) results assessed by QuantiFERON-TB Gold in tube (QTF-GIT) were included. All patients received biologic agents, and rescreening with QTF-GIT was performed after a median of 25.9 months from the baseline test. Clinical characteristics and IFN-γ levels were compared between converters and non-converters. Logistic regression analysis was performed to identify factors associated with positive conversion. IGRA conversion was found in 14 of 119 patients (11.8%). The converters were older (53.4 ± 14.2 vs 44.4 ± 15.5 years, p = 0.040), had higher baseline TB-specific IFN-γ responses (0.105 [0.018-0.205] vs 0.010 [0.000-0.035] IU/ml, p = 0.001) and higher incidence of active TB (14.3% vs 0.0%, p = 0.013). The number of patients with RA or AS was 9 (64.3%) or 5 (35.7%) in converters, and 45 (42.9%) or 60 (57.1%) in non-converters. In terms of use of biologics, TNFi of monoclonal antibody form was less commonly used in the converters (p = 0.024). In the logistic regression analysis, type of disease and type of biologics used were not associated with IGRA conversion, whereas baseline TB-specific IFN-γ response was significantly associated with IGRA conversion (OR 1.083, 95% CI 1.019-1.151, p = 0.011). Serial monitoring of LTBI with IGRA retesting is needed during biologic treatment, regardless of the type of rheumatic diseases or type biologics used.

Objectives: To determine the differential expressions of nucleotide oligomerisation domain (NOD)-like receptors (NLRs) and to investigate their association with inflammatory responses in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS)., Methods: Gene expression and protein levels of various NLRs, including NOD1, NOD2, NLRP1, NLRP3, NLRP12, NLRX1, and NLRC3, were determined in FLS and synovial tissues from patients with RA and patients with osteoarthritis (OA) using quantitative real-time PCR and immunohistochemistry. After transfection of NOD2 RNAi plasmids or a pcDNA3.1-NLRX1 vector, gene expression levels of pro-inflammatory cytokines in RA FLS and the protein levels of these cytokines in culture supernatants were determined using quantitative real-time PCR and enzyme-linked immunosorbent assays. The effects of NLR gene regulation on NF-κB and caspase-1 were evaluated using Western blot analysis., Results: Gene expression levels of NOD1, NLRP1, NLRP3, NLRP12, and NLRC3 were not different between RA and OA samples. NOD2 gene expression and protein levels were significantly increased in RA samples, whereas the levels of NLRX1 were significantly decreased. Downregulation of NOD2 gene expression by transfection with NOD2 RNAi plasmid significantly reduced pro-inflammatory cytokine levels in RA FLS, while transfection with adenoviral vectors encoding NLRX1 had no effect on pro-inflammatory cytokine levels. Downregulation of NOD2 gene expression significantly decreased NF-κB, TRAF6, and IKK levels, but not caspase-1 levels, in RA FLS., Conclusions: NOD2 is upregulated in RA FLS; moreover, downregulation of NOD2 gene expression reduces pro-inflammatory cytokine and NF-κB levels in RA FLS. These findings provide evidence that NOD2 exerts pro-inflammatory effects in RA.

Objective: The aim of this study was to investigate the turnover of Treg cells in the SF of RA patients., Methods: Treg cells were enumerated in peripheral blood and SF of RA patients and analysed by flow cytometry for expression of the proliferation marker Ki-67 and binding of the apoptosis marker annexin V. Sorted Treg cells of RA patients were analysed for expression of anti-apoptotic regulators Bcl-2 and microRNA-21 (miR-21) by RT-PCR., Results: Treg cells displaying a memory phenotype were abundant in the SF of RA patients. SF Treg cells more frequently expressed the proliferation marker Ki-67 than conventional T cells. Only few SF Treg cells were apoptotic, as indicated by limited annexin V staining of these cells. SF Treg cells displayed high transcription levels of Bcl-2 and miR-21 in comparison with SF conventional T cells and peripheral blood Treg cells., Conclusion: Treg cells with a memory phenotype accumulate in the SF of RA patients. These Treg cells have a high proliferative activity and demonstrate little apoptosis. The latter finding could be explained by high transcription of Bcl-2 and miR-21 in SF Treg cells., (© The Author 2014. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Clinical characteristics of antitumor necrosis factor (TNF) agents-related tuberculosis (TB) in ankylosing spondylitis (AS) are not well described. The aim was to compare the incidences and the characteristics of TB in AS and rheumatoid arthritis (RA) during TNF inhibitor treatment. AS (n = 1,322) and RA (n = 3,154) patients who received medical care between January 2001 and August 2011 were enrolled. The incidence of TB in patients treated, or not, with TNF inhibitors and the clinical features associated with TB were explored. Seven patients with AS and seven with RA developed TB while receiving TNF inhibitor therapy, resulting in an incidence rate of 600.2/100,000 person-years (PYs) (95 % confidence interval (CI), 241.3-1236.3) for those with AS and 771.6/100,000 PYs (95 % CI, 310.2-1589.9) for those with RA. Incidence rate ratios for TNF inhibitor-treated vs. untreated patients were 4.87 for AS (95 % CI, 1.50-15.39; p < 0.001) and 3.61 for RA (95 % CI, 1.38-8.07; p < 0.001). Low body mass index was identified as a significant risk factor for TB in the AS group (odds ratio (OR), 13.0; p = 0.002). Extrapulmonary TB was predominant at 85.7 % during TNF inhibitor treatment. Three (42.8 %) of the AS patients, but none of the RA patients, developed TB with concomitant isoniazid. All AS patients recovered from TB whereas two of seven RA patients died. Treatment with TNF inhibitors significantly increases the risk of extrapulmonary TB in AS. Symptoms of infection should warrant clinicians to evaluate for TB during TNF inhibitor therapy in AS patients.

Little is known about the cellular characteristics of CD8(+) T cells in rheumatoid arthritis (RA). We addressed this by investigating whether the frequency of the CD8(+) T cell subsets and their phenotypic characteristics are altered in the peripheral blood and synovial fluid (SF) from patients with RA. In this study, CD8(+) T cells, mainly CD45RA(-) effector memory (EM) CD8(+) T cells, were increased significantly in the SF, but not in the peripheral blood from RA patients, compared with healthy controls. The synovial EM CD8(+) T cells were activated phenotypes with high levels of CD80, CD86, and PD-1, and had a proliferating signature in vivo upon Ki-67 staining, whereas the Fas-positive cells were prone to apoptosis. In addition, EM CD8(+) T cells in the SF were less cytotoxic, as they expressed less perforin and granzyme B. In particular, the proportions of synovial fluid mononuclear cells that were CCR4(+)CD8(+) T cells and IL-4-producing CD8(+) T cells (i.e., Tc2 cells) were significantly higher than those in peripheral blood mononuclear cells of patients with RA and healthy controls. In addition, the number of IL-10-producing CD8(+) suppressor T (Ts) cells increased significantly in the SF of RA patients. Especially, CD8(+) T cells were inversely correlated with disease activity. These findings strongly suggest that EM CD8(+) T cells in the SF are increased, likely because of inflammation, and they may be involved in modulating inflammation, thereby affecting the development and progression of RA.