A Machine Learning Approach for Prediction of CDAI Remission with TNF Inhibitors: A Concept of Precision Medicine from the FIRST Registry.

INTRODUCTION: This study aimed to develop low-cost models using machine learning approaches predicting the achievement of Clinical Disease Activity Index (CDAI) remission 6 months after initiation of tumor necrosis factor inhibitors (TNFi) as primary biologic/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) for rheumatoid arthritis (RA). METHODS: Data of patients with RA initiating TNFi as first b/tsDMARD after unsuccessful methotrexate treatment were collected from the FIRST registry (August 2003 to October 2022). Baseline characteristics and 6-month CDAI were collected. The analysis used various machine learning approaches including logistic regression with stepwise variable selection, decision tree, support vector machine, and lasso logistic regression (Lasso), with 48 factors accessible in routine clinical practice for the prediction model. Robustness was ensured by k-fold cross validation. RESULTS: Among the approaches tested, Lasso showed the advantages in predicting CDAI remission: with a mean area under the curve 0.704, sensitivity 61.7%, and specificity 69.9%. Predicted TNFi responders achieved CDAI remission at an average rate of 53.2%, while only 26.4% of predicted TNFi non-responders achieved remission. Encouragingly, the models generated relied solely on patient-reported outcomes and quantitative parameters, excluding subjective physician input. CONCLUSIONS: While external cohort validation is warranted for broader applicability, this study highlights the potential for a low-cost predictive model to predict CDAI remission following TNFi treatment. The approach of the study using only baseline data and 6-month CDAI measures, suggests the feasibility of establishing regional cohorts to generate low-cost models tailored to specific regions or institutions. This may facilitate the application of regional/in-house precision medicine strategies in RA management.

This study aims to enhance the management of rheumatoid arthritis by predicting the likelihood of achieving the treatment target­Clinical Disease Activity Index remission within 6 months of initiating tumor necrosis factor inhibitors. In rheumatoid arthritis, the goal is often Clinical Disease Activity Index remission, and the standard approach involves using medications like methotrexate and biologic/targeted synthetic disease-modifying antirheumatic drugs. However, not all patients respond to these treatments, leading to a trial-and-error process of changing medications. Tumor necrosis factor inhibitors are commonly used as the initial biologic/targeted synthetic disease-modifying antirheumatic drugs for patients who do not respond adequately to methotrexate; however, tumor necrosis factor inhibitor treatment may not achieve effective outcomes for all patients. The study, using a cohort of patients with rheumatoid arthritis treated with tumor necrosis factor inhibitor, has developed a model predicting Clinical Disease Activity Index remission with tumor necrosis factor inhibitors. The models use only standard clinical parameters, therefore no special examination or additional cost is required for the predictions. This approach holds the potential to improve rheumatoid arthritis management by reducing the need for trial-and-error approaches and facilitating more personalized and effective treatment strategies. While further validation is necessary, the study also suggests that creating cost-effective models tailored to specific regions or institutions is possible.

Extracting immunological and clinical heterogeneity across autoimmune rheumatic diseases by cohort-wide immunophenotyping.

OBJECTIVE: Extracting immunological and clinical heterogeneity across autoimmune rheumatic diseases (AIRDs) is essential towards personalised medicine. METHODS: We conducted large-scale and cohort-wide immunophenotyping of 46 peripheral immune cells using Human Immunology Protocol of comprehensive 8-colour flow cytometric analysis. Dataset consisted of >1000 Japanese patients of 11 AIRDs with deep clinical information registered at the FLOW study, including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In-depth clinical and immunological characterisation was conducted for the identified RA patient clusters, including associations of inborn human genetics represented by Polygenic Risk Score (PRS). RESULTS: Multimodal clustering of immunophenotypes deciphered underlying disease-cell type network in immune cell, disease and patient cluster resolutions. This provided immune cell type specificity shared or distinct across AIRDs, such as close immunological network between mixed connective tissue disease and SLE. Individual patient-level clustering dissected patients with AIRD into several clusters with different immunological features. Of these, RA-like or SLE-like clusters were exclusively dominant, showing immunological differentiation between RA and SLE across AIRDs. In-depth clinical analysis of RA revealed that such patient clusters differentially defined clinical heterogeneity in disease activity and treatment responses, such as treatment resistance in patients with RA with SLE-like immunophenotypes. PRS based on RA case-control and within-case stratified genome-wide association studies were associated with clinical and immunological characteristics. This pointed immune cell type implicated in disease biology such as dendritic cells for RA-interstitial lung disease. CONCLUSION: Cohort-wide and cross-disease immunophenotyping elucidate clinically heterogeneous patient subtypes existing within single disease in immune cell type-specific manner.

Biological/targeted synthetic DMARDs do not arrest bone loss in patients with rheumatoid arthritis: a multicenter prospective observational study.

OBJECTIVE: To elucidate the differential effects of biological/target synthesized DMARDs (b/tsDMARDs) on bone metabolism in patients with rheumatoid arthritis (RA) in a real-world cohort. METHODS: This was a multicentre prospective observational study of RA patients enrolled at the time of 1st b/tsDMARDs administration. Bone mineral density (BMD) and bone turnover markers (BTMs) were measured during the 52-week observation. The study was designed to enrol all eligible RA patients. The end-points were differences in changes in BMD according to b/tsDMARD type, and the correlation between BMD and BTMs. RESULTS: A total of 1,164 patients were enrolled in this study. b/tsDMARDs improved RA disease activity from mean CDAI 25.5 at baseline to 4.5 at week 26. Patients not receiving anti-osteoporotic agents (anti-OP) at baseline with no history of fracture experienced a significant decrease in both femoral neck (F: mean 0.666-0.655 g/cm3) and radial (R: 0.518-0.514) BMD at week 26. Despite maintaining low CDAI levels during weeks 26-52 (5.3-4.4), there was a continued decline in BMD (F: 0.653, R: 0.509. Weeks 52). None of b/tsDMARDs type preserved BMD. Conversely, patients receiving anti-OP at baseline maintained stable BMD throughout the study (Weeks 0/26/52. F: 0.551/0.551/0.555, R: 0.415/0.416/0.415). Although BTMs were changed by b/tsDMARDs, the changes were unrelated to those in BMD. CONCLUSION: Our study suggested the progression of osteoporosis in RA patients during b/tsDMARDs treatment without anti-OP. BTMs may not reflect BMD change. Regular monitoring of BMD in RA should be considered for early management of osteoporosis.

Safety and efficacy of anifrolumab therapy in systemic lupus erythematosus in real-world clinical practice: LOOPS registry.

OBJECTIVES: To determine the safety and efficacy of anifrolumab in patients with systemic lupus erythematosus (SLE) classified based on the Lupus Low Disease Activity State (LLDAS) in real-world clinical practice. METHODS: This retrospective observational study involved SLE patients who started anifrolumab therapy. The primary end point was the retention rate over 26 weeks after initiating anifrolumab therapy; 45 patients followed up for 12 weeks or longer were analyzed in the following groups to determine the safety and efficacy up to week 12 after treatment initiation: 1) non-LLDAS achievement group and 2) minor flare group. Safety and efficacy were compared between the minor flare group and the standard of care (SoC) group (treated by adding glucocorticoids (GCs) or immunosuppressants) after adjustment with inverse probability of treatment weighting using propensity score (PS-IPTW). RESULTS: The retention rate of anifrolumab was 89.7% at week 26.The LLDAS achievement rates at week 12 were 42.9% and 66.7% in the non-LLDAS achievement and minor flare groups, respectively. In both groups, GC doses and SELENA-SLEDAI score significantly decreased. When the anifrolumab group with minor flare was compared with the SoC group or the GC dose increase group, the GC dose and SLEDAI score were significantly lower in the anifrolumab group than in both groups; there was no significant difference in LLDAS achievement. CONCLUSIONS: At week 26 after initiating anifrolumab therapy, ∼90% patients remained on therapy. Anifrolumab might lower disease activity without initiating GCs and reduce GC doses, especially in patients who experience minor flares after LLDAS achievement.

Generation-Dependent Retention Rates and Reasons for Discontinuation of Molecular Targeted Therapies in Patients with Rheumatoid Arthritis: From FIRST Registry.

INTRODUCTION: The study aimed to optimize medical care for elderly patients with rheumatoid arthritis (RA) by examining the 3-year continuation rate of different molecular targeted therapies across age groups in Japan, which has a significant elderly population. METHODS: The study included patients with RA who started molecular targeted therapies between 2013 and 2019 and divided them into three age groups. The primary outcome was to assess the 3-year continuation rate of each drug and analyze reasons for treatment discontinuation using inverse probability of treatment weighting. RESULTS: Among 2292 patients analyzed, tumor necrosis factor (TNF) inhibitors were most commonly used in those younger than 65 years of age (43.5%), while Janus kinase (JAK) inhibitors were also utilized (17.1%). In contrast, JAK inhibitors were less frequently used in patients aged 75 years and older (7.8%), with cytotoxic T lymphocyte antigen 4 immunoglobulin fusion proteins (CTLA4-Ig) being the most common (39.2%). JAK inhibitors and anti-interleukin-6 receptor (IL-6R) antibodies had higher continuation rates than other drugs in patients under 65 years (p < 0.001). For those aged 65-74 years, JAK inhibitors and CTLA4-Ig had higher continuation rates (p < 0.001), while among those aged 75 years and older, CTLA4-Ig and IL-6R antibodies had higher continuation rates (p < 0.001). Inadequate efficacy was the main reason for discontinuation in all age groups, while infection leading to discontinuation increased with age. CONCLUSIONS: The study highlights the need to consider different age groups separately in elderly RA care. Among patients aged 75 years and older, abatacept and anti-IL-6R antibodies showed the highest continuation rates, suggesting their potential suitability and efficacy for this specific age cohort.

Malignancies and rheumatoid arthritis, csDMARDs, biological DMARDs, and JAK inhibitors: challenge and outlook.

INTRODUCTION: Rheumatoid arthritis (RA) is an autoimmune disorder necessitating immunosuppressive therapy. Remarkable progress has been made in the treatment of RA over recent decades, particularly with the development of biological disease-modifying antirheumatic drugs (bDMARDs) and Janus kinase inhibitors (JAKi). Nonetheless, the development of new drugs has been accompanied by concerns regarding the association between these novel therapies and the risk of malignancy. AREAS COVERED: This narrative review aims to discuss the understanding of RA, conventional synthetic (cs) DMARDs, bDMARDs, JAKi, and their association with malignancy. Furthermore, the review discusses the management of malignancy in patients receiving b/tsDMARDs. EXPERT OPINION: Although recent studies suggest that the potential risk of malignancy of methotrexate and a JAKi tofacitinib, it is essential to avoid indiscriminate withholding of treatment by those agents, as this may lead functional impairment and increased mortality. Therefore, the adoption of a Treat-to-Target (T2T) approach considering individual patient characteristics, becomes of utmost importance. Rheumatologists should maintain a vigilant stance regarding malignancy in this context, recognizing the importance of early detection and management. Implementing a screening program for malignancies is indispensable, and the use of computed tomography screening may enhance the effectiveness of management strategies.

High-fat-diet-associated intestinal microbiota exacerbates psoriasis-like inflammation by enhancing systemic γδ T cell IL-17 production.

Although it is known that psoriasis is strongly associated with obesity, the mechanistic connection between diet and skin lesions is not well established. Herein, we showed that only dietary fat, not carbohydrates or proteins, exacerbates psoriatic disease. Enhanced psoriatic skin inflammation was associated with changes in the intestinal mucus layer and microbiota composition by high-fat diet (HFD). Change of intestinal microbiota by vancomycin treatment effectively blocked activation of psoriatic skin inflammation by HFD, inhibited the systemic interleukin-17 (IL-17) response, and led to increased mucophilic bacterial species such as Akkermansia muciniphila. By using IL-17 reporter mice, we could show that HFD facilitates IL-17-mediated γδ T cell response in the spleen. Notably, oral gavage with live or heat-killed A. muciniphila effectively inhibited HFD-induced enhancement of psoriatic disease. In conclusion, HFD exacerbates psoriatic skin inflammation through changing the mucus barrier and the intestine microbial composition, which leads to an enhanced systemic IL-17 response.

Computed tomography for malignancy screening in patients with rheumatoid arthritis before initiation of disease modifying antirheumatic drug.

OBJECTIVES: This study aimed to clarify the usefulness of screening for malignancies using CT before the initiation of biologic and targeted synthetic DMARDs (b/tsDMARDs) in patients with active RA. METHODS: We examined 2192 patients with RA who underwent plain CT scans prior to the initiation of b/tsDMARDs. The sensitivity for detecting malignancy was measured and compared with that of regular screening (physical examination and X-ray). We then evaluated the clinical characteristics, prognosis and treatment of patients with RA with concomitant malignancies. Additionally, we determined the incidence rate of malignancy in patients with RA who were initiated on b/tsDMARDs after CT screening. RESULTS: Of the 2192 patients, 33 (1.5%) were diagnosed with malignancy after CT screening. Whereas regular screening detected only seven malignancies, CT screening further detected 26 (including 19 at the early stage). On the other hand, 86% of the malignancies detectable by regular screening were at an advanced stage. Patients diagnosed with early-stage malignancies received RA treatments that included b/tsDMARDs after curative resection; 80% of these patients achieved low disease activity after 1 year. This rate was comparable to the patients without malignancy detection after screening (70%). The 5 year incidence of malignancy after the initiation of b/tsDMARDs after CT screening was lower than that of the RA cohort without CT screening (standardized incidence ratio: 0.35). CONCLUSION: Screening in patients with RA using CT before the initiation of b/tsDMARDs allows for the early detection and treatment of malignancy, resulting in safer and more stable b/tsDMARD treatments.

Reduced homovanillic acid, SDF-1α and SCGF-ß levels in cerebrospinal fluid are related to depressive states in systemic lupus erythematosus.

OBJECTIVE: This study aimed to seek a new method of evaluation and surrogate markers for diffuse neuropsychiatric SLE (NPSLE). METHODS: We enrolled 44 patients with SLE between 2017 and 2020 who fulfilled at least one of three specific inclusion criteria: high disease activity, abnormal findings (cerebrospinal fluid [CSF] examination, brain MRI, or electroencephalography), or history of neuropsychiatric illness. Psychiatric symptom rating scales (PSYRATS) were evaluated retrospectively. The primary end point was the PSYRATS positivity rate in SLE patients who had not been diagnosed with diffuse NPSLE. RESULTS: Based on the 1999 ACR classifications, 7 out of the 44 patients evaluated using PSYRATS had been diagnosed with diffuse NPSLE. PSYRATS positivity was seen in 13 out of 37 SLE patients (35.1%) who had not been diagnosed with diffuse NPSLE, and all these patients were positive for Montgomery-Åsberg Depression Rating Scale (MADRS), an indicator of depression state in PSYRATS. Additionally, in the 20 SLE patients exhibiting depression symptoms who were MADRS-positive, CSF concentrations of the neuroinflammatory markers homovanillic acid (HVA; P = 0.0400), stromal cell-derived factor-1α (SDF-1α; P = 0.0431) and stem cell growth factor-ß (SCGF-1ß; P = 0.0061) were significantly reduced compared with the 24 MADRS-negative SLE patients, and the levels of HVA, SDF-1α and SCGF-1ß correlated with one another (P < 0.05). CONCLUSION: Many patients with active SLE have subclinical depression, and MADRS evaluation of neuropsychiatric symptoms is useful for detecting them. Additionally, the decrease in CSF levels of HVA, SDF-1 α and SCGF-1ß reflects the same pathology, and these may serve as surrogate markers.

TGF-ß3 in differentiation and function of Tph-like cells and its relevance to disease activity in patients with systemic lupus erythematosus.

OBJECTIVES: T peripheral helper (Tph) cells have major roles in pathological processes in SLE. We sought to clarify the mechanisms of Tph cell differentiation and their relevance to clinical features in patients with SLE. METHOD: Phenotypes and functions of Tph cell-related markers in human CD4+ T cells purified from volunteers or patients were analysed using flow cytometry and quantitative PCR. Renal biopsy specimens from patients with LN were probed by multicolour immunofluorescence staining. RESULTS: Among multiple cytokines, transforming growth factor (TGF)-ß3 characteristically induced programmed cell death protein 1 (PD-1)hi musculoaponeurotic fibrosarcoma (MAF)+, IL-21+IL-10+ Tph-like cells with a marked upregulation of related genes including PDCD-1, MAF, SOX4 and CXCL13. The induction of Tph-like cells by TGF-ß3 was suppressed by the neutralization of TGF-ß type II receptor (TGF-ßR2). TGF-ß3-induced Tph-like cells efficiently promoted the differentiation of class-switch memory B cells into plasmocytes, resulting in enhanced antibody production. The proportion of Tph cells in the peripheral blood was significantly increased in patients with SLE than in healthy volunteers in concordance with disease activity and severity of organ manifestations such as LN. TGF-ß3 was strongly expressed on macrophages, which was associated with the accumulation of CD4+ C-X-C chemokine receptor (CXCR5)-PD-1+ Tph cells, in the renal tissue of patients with active LN. CONCLUSION: The induction of Tph-like cells by TGF-ß3 mainly produced from tissue macrophages plays a pivotal role in the pathological processes of active LN by enhancing B-cell differentiation in patients with SLE.

Epstein-Barr virus-induced gene 3 commits human mesenchymal stem cells to differentiate into chondrocytes via endoplasmic reticulum stress sensor.

Mesenchymal stem cells (MSC) can differentiate into chondrocytes. Epstein-Barr virus-induced gene 3 (EBI3) is differentially expressed during chondrogenic differentiation and can be produced by MSC. EBI3 is also a subunit of interleukin (IL)-27 and IL-35, and it accumulates in the endoplasmic reticulum (ER) when its partners, such as IL-27 p28 and IL-35 p35, are insufficient. ER stress induced by protein accumulation is responsible for chondrogenic differentiation. However, the role of EBI3 and its relevance to the ER stress in chondrogenic differentiation of MSC have never been addressed. Here, we demonstrate that EBI3 protein is expressed in the early stage of chondrogenic differentiation of MSC. Additionally, knockdown, overexpression, or induction of EBI3 through IL-1ß inhibits chondrogenesis. We show that EBI3 localizes and accumulates in the ER of MSC after overexpression or induction by IL-1ß and TNF-α, whereas ER stress inhibitor 4-phenylbutyric acid decreases its accumulation in MSC. Moreover, EBI3 modulates ER stress sensor inositol-requiring enzyme 1 α (IRE1α) after induced by IL-1ß, and MSC-like cells coexpress EBI3 and IRE1α in rheumatoid arthritis (RA) synovial tissue. Altogether, these data demonstrate that intracellular EBI3 commits to chondrogenic differentiation by regulating ER stress sensor IRE1α.

Enhancer RNA commits osteogenesis via microRNA-3129 expression in human bone marrow-derived mesenchymal stem cells.

BACKGROUND: Highly regulated gene expression program underlies osteogenesis of mesenchymal stem cells (MSCs), but the regulators in the program are not entirely identified. As enhancer RNAs (eRNAs) have recently emerged as a key regulator in gene expression, we assume a commitment of an eRNA in osteogenesis. METHODS: We performed in silico analysis to identify potential osteogenic microRNA (miRNA) gene predicted to be regulated by super-enhancers (SEs). SE inhibitor treatment and eRNA knocking-down were used to confirm the regulational mechanism of eRNA. miRNA function in osteogenesis was elucidated by miR mimic and inhibitor transfection experiments. RESULTS: miR-3129 was found to be located adjacent in a SE (osteoblast-specific SE_46171) specifically activated in osteoblasts by in silico analysis. A RT-quantitative PCR analysis of human bone marrow-derived MSC (hBMSC) cells showed that eRNA_2S was transcribed from the SE with the expression of miR-3129. Knockdown of eRNA_2S by locked nucleic acid as well as treatment of SE inhibitors JQ1 or THZ1 resulted in low miR-3129 levels. Overexpression of miR-3129 promoted hBMSC osteogenesis, while knockdown of miR-3129 inhibited hBMSC osteogenesis. Solute carrier family 7 member 11 (SLC7A11), encoding a bone formation suppressor, was upregulated following miR-3129-5p inhibition and identified as a target gene for miR-3129 during differentiation of hBMSCs into osteoblasts. CONCLUSIONS: miR-3129 expression is regulated by SEs via eRNA_2S and this miRNA promotes hBMSC differentiation into osteoblasts through downregulating the target gene SLC7A11. Thus, the present study uncovers a commitment of an eRNA via a miR-3129/SLC7A11 regulatory pathway during osteogenesis of hBMSCs.

Impact of serum interleukin-22 as a biomarker for the differential use of molecular targeted drugs in psoriatic arthritis: a retrospective study.

BACKGROUND: We explored whether serum cytokines could be used as biomarkers for optimal use of tumor necrosis factor inhibitors (TNF-i) and interleukin (IL)-17 inhibitors (IL-17-i) in patients with psoriatic arthritis (PsA). METHODS: In cohort 1 (47 patients treated with IL-17-i [n=23] or TNF-i [n=24] for ≥1 year), we identified serum cytokines that predicted the achievement of Disease Activity in Psoriatic Arthritis-remission (DAPSA-REM), Psoriasis Area and Severity Index (PASI) 90, and Minimal Disease Activity after 1 year of TNF-i or IL-17-i therapy. Subsequently, we developed treatment strategies based on the identified cytokines; initiation of IL-17-i therapy in patients with low IL-22 concentrations (IL-22 <0.61376 pg/ml) and TNF-i therapy in patients with high IL-22 concentrations (0.61376< IL-22 pg/ml). In cohort 2 (34 patients), treatment responses were compared between the strategic treatment group (n=17), which was treated based on the treatment strategies, and the mismatched treatment group (n=17) to verify the validity of the treatment strategies developed using serum cytokines as biomarkers. RESULTS: In cohort 1, serum IL-22 concentration was identified as a predictor of DAPSA-remission after 1 year of IL-17-i therapy. Regarding treatment strategies, we selected TNF-i for patients with high IL-22 concentrations and IL-17-i for those with low IL-22 concentrations. There were no significant differences in the baseline characteristics between the strategic and mismatched treatment groups. Regarding treatment effects, activity significantly improved at 1 year in both groups. Upon comparison of the treatment effects, the rate of achieving DAPSA-REM and Minimal Disease Activity at month 12 was significantly higher in the strategic treatment group. CONCLUSIONS: The results of this pilot study suggest that IL-22 may be a biomarker of treatment response to TNF-i and IL-17-i in patients with PsA. Further large-scale studies in independent, prospectively collected datasets are required to verify that IL-22 is indeed a biomarker of treatment response in these patients.

Preferable outcome of Janus kinase inhibitors for a group of difficult-to-treat rheumatoid arthritis patients: from the FIRST Registry.

BACKGROUNDS: Treatment of difficult-to-treat rheumatoid arthritis (D2T RA) is one of the greatest unmet needs in rheumatology. This study aims to find out preferable treatment options for a group of D2T RA patients who are refractory to multiple biologic and targeted synthetic disease-modifying anti-rheumatic drugs (b/tsDMARDs). METHODS: Data were obtained from patients enrolled in the FIRST Registry who started either TNF inhibitor (TNFi), interleukin-6 receptor inhibitor, cytotoxic T-lymphocyte-associated antigen-4 immunoglobulin, or Janus-kinase inhibitor (JAKi) in the period of August 2013 to December 2020. Those who failed to ≥ 2 and ≥ 3 b/tsDMARDs were categorised as D2T RA and very D2T RA (vD2T RA), respectively. Change in Clinical Disease Activity Index (CDAI) and Health Assessment Questionnaire Disability Index were compared among the groups using propensity-based inverse probability treatment weighted (IPTW) method. RESULTS: Of 2128 cases included, 353 were categorised as D2T RA. Among the D2T RA, 106 were identified as vD2T RA. JAKi showed a significant improvement in CDAI in the patients with D2T RA and vD2T RA, compared to IPTW-adjusted patients treated with the other 3 regimens. Latent class analysis of the trajectories of treatment response revealed that the proportion of a group of patients who showed poor response was lower among the JAKi subgroup than among those with other subgroups. This superiority of JAKi was more apparent among methotrexate- and glucocorticoid-free individuals. The hazard ratio of severe adverse events was comparable among the four treatment subgroups in both the D2T RA and b/tsDMARD-naïve groups. CONCLUSIONS: This study compared responsiveness to different classes of b/tsDMARDs among D2T RA and vD2T RA patients who were refractory to multiple b/tsDMARDs. The results suggest JAKi is a preferable treatment choice for this type of D2T RA.

Estrogen-mediated downregulation of HIF-1α signaling in B lymphocytes influences postmenopausal bone loss.

In the bone marrow, B cells and bone-resorbing osteoclasts colocalize and form a specific microenvironment. How B cells functionally influence osteoclasts and bone architecture is poorly understood. Using genetically modified mice and high-throughput analyses, we demonstrate that prolonged HIF-1α signaling in B cells leads to enhanced RANKL production and osteoclast formation. In addition, deletion of HIF-1α in B cells prevents estrogen deficiency-induced bone loss in mice. Mechanistically, estrogen controls HIF-1α protein stabilization through HSP70-mediated degradation in bone marrow B cells. The stabilization of HIF-1α protein in HSP70-deficient bone marrow B cells promotes RANKL production and osteoclastogenesis. Induction of HSP70 expression by geranylgeranylacetone (GGA) administration alleviates ovariectomy-induced osteoporosis. Moreover, RANKL gene expression has a positive correlation with HIF1A expression in human B cells. In conclusion, HIF-1α signaling in B cells is crucial for the control of osteoclastogenesis, and the HSP70/HIF-1α axis may serve as a new therapeutic target for osteoporosis.

An enhanced mitochondrial function through glutamine metabolism in plasmablast differentiation in systemic lupus erythematosus.

OBJECTIVE: To evaluate the dysfunction of B-cell metabolism and its involvement in SLE pathology. METHODS: We assessed the expression of metabolic markers of B cells in the peripheral blood of healthy controls (HCs) and SLE patients by using flow cytometry. In vitro, peripheral B cells were isolated from HCs and SLE patients to investigate the metabolic regulation mechanisms involved in their differentiation. RESULTS: The expression level of DiOc6 (mitochondrial membrane hyperpolarization) was higher in B cells from SLE patients than in HCs, and correlated to the percentage of plasmablasts in CD19+ cells and with SLEDAI, a disease activity score. Stimulation of CD19+ cells with the Toll-like receptor 9 (TLR9) ligand CpG and IFN-α enhanced glycolysis, oxidative phosphorylation (OXPHOS), DiOc6 expression, and plasmablast differentiation in vitro. In the absence of glutamine, both glycolysis and OXPHOS were reduced, and plasmablast differentiation was suppressed, whereas there was no change in the absence of glucose. As glutamine is an important nutrient for protein synthesis, we further investigated the effect of the glutaminase inhibitor BPTES, which inhibits glutamine degradation, on metabolic regulation. BPTES reduced DiOc6 expression, OXPHOS, reactive oxygen species (ROS) production, adenosine triphosphate (ATP) production, plasmablast differentiation without affecting glycolysis. Metformin inhibited CpG- and IFN-α-induced glutamine uptake, mitochondrial functions and suppressed plasmablast differentiation. CONCLUSIONS: Mitochondrial dysfunction in B cells is associated with plasmablast differentiation and disease activity in SLE. Enhanced mitochondrial functions mediated by glutamine metabolism are important for plasmablast differentiation, which may be a potential therapeutic target for SLE.

Prophylaxis against pneumocystis pneumonia in rheumatoid arthritis patients treated with b/tsDMARDs: insights from 3787 cases in the FIRST registry.

OBJECTIVES: The use of biologic and targeted synthetic (b/ts) DMARDs in the treatment of RA is increasing. Therefore, prevention of b/tsDMARDs-induced infection is important. Here we describe a prophylaxis protocol for preventing pneumocystis pneumonia (PCP) in RA patients treated with b/tsDMARDs. METHODS: The study subjects were 3787 RA patients from the FIRST registry. They were divided into cohort 1 (n = 807, requiring prophylaxis against PCP based on physicians' assessment at the point of new treatment with or switch to b/tsDMARDs) and cohort 2 (n = 2980, receiving strategic PCP prophylaxis). The incidence and risk factors for PCP were investigated. RESULTS: Twenty-six PCP cases were observed throughout the study. After the introduction of strategic PCP prophylaxis, PCP incidence diminished from 0.51/100 person-years (PYs) to 0.21/100 PYs (risk ratio = 0.42). Sulfamethoxazole and trimethoprim in combination (SMX-TMP) showed greater efficacy in the prevention of PCP than pentamidine inhalation (P <0.0001). The prophylaxis rate increased chronologically despite the falls in the average SMX-TMP dose and in the incidence of PCP. Subanalysis of the data for 929 patients from both groups who did not receive prophylaxis showed that old age, high BMI, coexisting lung diseases, low lymphocyte count, and low serum IgG levels increased the risk of PCP development. Development of PCP could be predicted (using an equation based on these variables) in patients not treated with glucocorticoids [area under the curve (AUC) = 0.910)], but less accurately in those on glucocorticoids (AUC = 0.746). CONCLUSIONS: Our study clarified the risk factors for PCP in RA patients on b/tsDMARDs treatment and highlighted and defined the criteria for effective prophylaxis against PCP.

mTOR activation in CD8+ cells contributes to disease activity of rheumatoid arthritis and increases therapeutic response to TNF inhibitors.

OBJECTIVE: This study aimed to understand the role of mammalian target of rapamycin (mTOR) in CD8+ cells in the pathogenicity of RA and the changes after treatment with biologic drugs. METHODS: Peripheral blood mononuclear cells (PBMCs) were isolated from 17 healthy controls and 86 patients with RA. Phosphorylation of mTOR (p-mTOR) and its clinical relevance were evaluated. The role of mTOR in CD8+ cells was also examined in vitro. RESULTS: Patients with RA who had a moderate or high disease activity, were biologic-naïve, and were refractory to MTX were enrolled in this study. The p-mTOR levels in CD8+ cells were higher in patients with RA than in healthy controls, and they positively correlated with the disease activity in such patients. However, after one year of treatment with TNF inhibitors, the p-mTOR levels in CD8+ cells were suppressed and showed a positive correlation with the treatment response, which was not observed in the abatacept-treatment group. In vitro stimulation of CD8+ cells with anti-CD3 and anti-CD28 antibodies induced mTOR phosphorylation and increased the production of granzyme B, granulysin, TNF-α and IFN-γ but decreased the production of granzyme K. However, on treatment with TNF inhibitors, p-mTOR levels in CD8+ cells and granzyme B production decreased, while granzyme K production increased. The production of granulysin and IFN-γ was not affected by the TNF inhibitors. CONCLUSION: These results suggested that mTOR activation in CD8+ cells may be a novel evaluation marker for RA disease activity and a predictive marker of therapeutic response to TNF inhibitors.

T helper cells expressing fractalkine receptor and bearing T follicular helper 1-like cell functions in patients with IgG4-related disease.

OBJECTIVE: Because the pathological features of IgG4-related disease (IgG4-RD) include lymphocyte infiltration and fibrotic changes in the lesions, we investigated the significance of fractalkine (CX3CL1) and lymphocyte subsets in patients with IgG4-RD. METHODS: Peripheral blood and biopsied samples were obtained from healthy controls (HCs, n = 10), RA (n = 10) and IgG4-RD patients (n = 16) and were analysed by flow cytometry, immunohistology and costimulation assays. RESULTS: Peripheral CX3CR1+ CD4+ T cells had an approximately 3-fold increase in the IgG4-RD patients (15.4%), compared with the HCs (5.0%). In addition, CX3CR1+ CD4+ T cells were localized in the salivary glands of the IgG4-RD patients but not in those with Sicca syndrome. CX3CR1 was induced on 20% of CD4+ T cells after T-cell receptor (TCR) simulation with IL-12 for five days culture. CX3CR1+ T cells showed high expression of both CXCR5 and CXCR3. Moreover, they co-expressed Bcl-6 and T-bet, the master transcription factors for T helper 1 (Th1) and T follicular helper (Tfh) cells. After secondary stimulation, CX3CR1+ T cells produced both IFN-gamma (IFN-γ) and IL-21. Compared with their CX3CR1- counterparts, CX3CR1+ CD4+ T cells induced plasmablast differentiation from naïve B cells more efficiently (15.0 vs 5.0%) and increased the production of IgG2, IgG3 and IgG4 by B cells. CONCLUSION: CX3CR1+ CD4+ T cells characteristically increased in the peripheral blood and the affected tissues and were associated with an increase in the serum IgG4 levels of patients with IgG4-RD. This CD4 subset has a Th1/Tfh-like phenotype and a B cell helper function.

Efficacy and safety of belimumab during maintenance therapy in patients with systemic lupus erythematosus.

OBJECTIVES: The efficacy of belimumab (BEL) during maintenance therapy in patients with SLE remains unclear in the real-life clinical setting. This study investigated the efficacy and safety of BEL in patients with SLE during maintenance therapy. METHODS: In this retrospective observational study, maintenance therapy was defined as low-dose glucocorticoid (GC) therapy (prednisolone equivalent dose of ≤0.2 mg/kg/day) in patients with a Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index (SELENA-SLEDAI) score <10. Participants comprised patients with SLE on HCQ or MMF [standard-of-care (SoC) group: n = 103] and those on BEL plus SoC (BEL+SoC group: n = 100). Selection bias was minimized using propensity score-based inverse probability of treatment weighting (IPTW). GC dose trajectories were modelled using growth mixture modelling (GMM). The primary end point was GC dose at 52 weeks. RESULTS: No significant difference was observed in patient characteristics between the two groups after IPTW adjustment. The BEL+SoC group exhibited a significant decrease in GC dose. GC dose at 52 weeks and relapse rate were significantly lower in the BEL+SoC group than in the SoC group. The proportion of patients in one of four groups defined by GMM for which GC dose was tapered to 0 mg within 52 weeks (GC tapering-discontinuation group) was significantly higher in the BEL+SoC group than in the SoC group. In the BEL+SoC group, low SELENA-SLEDAI score and low GC dose at baseline were associated with being GC dose-tapering discontinuation. CONCLUSION: The present study suggests that BEL is suitable for patients with SLE during maintenance therapy.