Upregulation of interferon-γ response genes in monocytes and T cells identified by single-cell transcriptomics in patients with anti-citrullinated peptide antibody-positive early rheumatoid arthritis.

Our aim was to investigate the insufficiently understood differences in the immune system between anti-citrullinated peptide antibody (ACPA)-positive (ACPA+) and ACPA-negative (ACPA-) early rheumatoid arthritis (eRA) patients. We performed multiple cytokine assays using sera from drug-naïve ACPA+ and ACPA- eRA patients. Additionally, we conducted single-cell RNA sequencing of CD45+ cells from peripheral blood samples to analyze and compare the distribution and functional characteristics of the cell subsets based on the ACPA status. Serum concentrations of interferon-γ (IFN-γ) and interleukin (IL)-12 were higher in ACPA+ eRA than in ACPA- eRA. Single-cell transcriptome analysis of 37,318 cells identified 17 distinct cell types and revealed the expansion of IL1B+ proinflammatory monocytes, IL7R+ T cells, and CD8+ CCL4+ T cells in ACPA+ eRA. Furthermore, we observed an enrichment of IFN-γ response genes in nearly all monocytes and T cells of ACPA+ eRA subsets. Heightened interactions between IFN-γ and IFN-γ receptors were observed in ACPA+ eRA, particularly between monocytes and T cells. We examined IFITM2 and IFITM3 as potential key markers in ACPA+ eRA given their pronounced upregulation and association with the IFN response. Specifically, the expression of these genes was elevated in IL1B+ proinflammatory monocytes (likely M1 monocytes), correlating with serum IFN-γ levels. Compared to ACPA- eRA, ACPA+ eRA showed higher serum IFN-γ and IL-12 levels, upregulated IFN-γ response genes, and enhanced IFN-γ-driven monocyte-T cell interactions. These distinct immune features of the peripheral circulation in ACPA+ eRA suggest a role for type 1 helper T cell-related immunity in its pathogenesis.

Hong BK ，You S ，Kim JG ，Kim M ，Lee N ，Lee K ，Baek IP ，Ju JH ，Kim WU ，Kim HY ... -  《Frontiers in Immunology》

Metabolic reprogramming and macrophage expansion define ACPA-negative rheumatoid arthritis: insights from single-cell RNA sequencing.

Anti-citrullinated peptide antibodies (ACPA)-negative (ACPA-) rheumatoid arthritis (RA) presents significant diagnostic and therapeutic challenges due to the absence of specific biomarkers, underscoring the need to elucidate its distinctive cellular and metabolic profiles for more targeted interventions. Single-cell RNA sequencing data from peripheral blood mononuclear cells (PBMCs) and synovial tissues of patients with ACPA- and ACPA+ RA, as well as healthy controls, were analyzed. Immune cell populations were classified based on clustering and marker gene expression, with pseudotime trajectory analysis, weighted gene co-expression network analysis (WGCNA), and transcription factor network inference providing further insights. Cell-cell communication was explored using CellChat and MEBOCOST, while scFEA enabled metabolic flux estimation. A neural network model incorporating key genes was constructed to differentiate patients with ACPA- RA from healthy controls. Patients with ACPA- RA demonstrated a pronounced increase in classical monocytes in PBMCs and C1QChigh macrophages (p < 0.001 and p < 0.05). Synovial macrophages exhibited increased heterogeneity and were enriched in distinct metabolic pathways, including complement cascades and glutathione metabolism. The neural network model achieved reliable differentiation between patients with ACPA- RA and healthy controls (AUC = 0.81). CellChat analysis identified CD45 and CCL5 as key pathways facilitating macrophage-monocyte interactions in ACPA- RA, prominently involving iron-mediated metabolite communication. Metabolic flux analysis indicated elevated beta-alanine and glutathione metabolism in ACPA- RA macrophages. These findings underscore that ACPA-negative rheumatoid arthritis is marked by elevated classical monocytes in circulation and metabolic reprogramming of synovial macrophages, particularly in complement cascade and glutathione metabolism pathways. By integrating single-cell RNA sequencing with machine learning, this study established a neural network model that robustly differentiates patients with ACPA- RA from healthy controls, highlighting promising diagnostic biomarkers and therapeutic targets centered on immune cell metabolism.

Jiang Y ，Hu Z ，Huang R ，Ho K ，Wang P ，Kang J ... -  《Frontiers in Immunology》

Development of rheumatoid arthritis after methotrexate in anticitrullinated protein antibody-negative people with clinically suspect arthralgia at risk of rheumatoid arthritis: 4-year data from the TREAT EARLIER trial.

Prevention of rheumatoid arthritis has become a definitive target. However, whether prevention of anti-citrullinated protein antibody (ACPA)-negative rheumatoid arthritis is possible is still unknown. We aimed to assess the efficacy of a 1-year course of methotrexate on the development of rheumatoid arthritis in ACPA-negative people with clinically suspect arthralgia and predicted increased risk of rheumatoid arthritis. For this follow-up analysis, we used 4-year data from the TREAT EARLIER trial, a randomised, double-blind, placebo-controlled, proof-of-concept trial conducted in the southwest region of the Netherlands from which we analysed data collected between April 16, 2015, and Sept 11, 2023. ACPA-positive and ACPA-negative adults aged 18 years or older with arthralgia and subclinical joint inflammation who were at risk of developing rheumatoid arthritis were eligible for enrolment. For TREAT EARLIER, participants were randomly assigned (1:1) to active treatment or placebo. Active treatment consisted of a single intramuscular glucocorticoid injection (120 mg of methylprednisolone) upon inclusion, then a 1-year course of methotrexate. Placebo consisted of a single placebo injection followed by a 1-year course of placebo tablets. Trial visits occurred every 4 months during the first 2 years, at which clinical and questionnaire data were collected. Total follow-up was 4 years. For this analysis, participants were stratified via a prediction model into low risk, increased risk, and high risk of developing persistent, clinically apparent inflammatory arthritis. The primary outcome was development of rheumatoid arthritis, defined as the presence of clinically apparent inflammatory arthritis and clinical diagnosis of rheumatoid arthritis, and was assessed in all TREAT EARLIER participants. Severity of subclinical joint inflammation, physical functioning, and grip strength in ACPA-negative participants was studied in each risk group over a period of 2 years. 901 people with clinically suspect arthralgia were assessed for eligibility and 236 were enrolled in TREAT EARLIER. All 236 participants were included in the intention-to-treat analysis and 217 (92%) completed 4-year follow-up. 154 (65%) of 236 participants were women and 82 (35%) were men, 182 (77%) were ACPA-negative and 54 (23%) were ACPA-positive. Of the 182 randomly assigned ACPA-negative participants, none were predicted to be at high risk of developing persistent, clinically apparent inflammatory arthritis, 66 (36%) at increased risk, and 116 (64%) at low risk. Of the 54 ACPA-positive participants, 24 (44%) were predicted to be at high risk, 30 (56%) at increased risk, and none at low risk. After 4 years, 52 (22%) of 236 participants had developed the primary outcome of rheumatoid arthritis (25 [21%] of 119 in the treatment group and 27 [23%] of 117 in the placebo group). Of the 66 ACPA-negative participants predicted to be at increased risk, three (9%) of 35 in the treatment group developed the primary outcome compared with nine (29%) of 31 in the placebo group (hazard ratio 0·27, 95% CI 0·07-0·99; p=0·034). Of the 116 ACPA-negative participants predicted to be at low risk, four (8%) of 53 in the treatment group met the primary outcome compared with six (10%) of 63 in the placebo group (0·79, 0·22-2·80; p=0·71). Thus, after risk stratification, a 1-year course of methotrexate was associated with a reduced rate of development of ACPA-negative rheumatoid arthritis in participants with predicted increased risk of developing the disease. Subclinical joint inflammation, physical functioning, and grip strength persistently improved upon treatment in ACPA-negative participants with increased risk of developing rheumatoid arthritis, but not in those with low risk. Risk stratification can be helpful in trials of ACPA-negative people with clinically suspect arthralgia to identify participants who could benefit from treatment to prevent development of rheumatoid arthritis. Dutch Research Council-ZonMw, Dutch Arthritis Society.

Dumoulin QA ，Krijbolder DI ，Visser K ，Lard LR ，van der Helm-van Mil AHM ... -  《Lancet Rheumatology》

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

《Jove-Journal of Visualized Experiments》

The role of Anti-PAD4, Anti-CarP, and Anti-RA33 antibodies combined with RF and ACPA in predicting abatacept response in rheumatoid arthritis.

To explore the role of newly emerging autoantibodies (AAbs) - peptidyl-arginine deiminase 4 (aPAD4), carbamylated proteins (aCarP), and anti-RA33 (aRA33) - alongside the traditionally assessed rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA), in predicting the response to abatacept (ABT) and its retention rate in rheumatoid arthritis (RA) patients. Data from 121 consecutive ABT-treated RA patients were recorded. The RF and ACPA status were retrospectively assessed by reviewing the patients' clinical records. Positivity for aPAD4, aCarP and aRA33 were determined by Enzyme-Linked Immunosorbent Assay (ELISA). The achievement of a moderate or good EULAR response at 6 months and the 3-years retention were analyzed as treatment outcomes. Multiple logistic regression models and Cox regression hazard analysis models were built to identify the association between such outcomes and the different AAbs, after adjustment for different confounders. The AAbs were assessed both individually and in different combinations to identify the most robust predictive model. In the studied cohort, RF, ACPA, aPAD4, aCarP and aRA33-Ab tested positive in 74.4%, 69.4%, 43.8%, 23.9%, 14.9% patients, respectively. A moderate or good EULAR response at 6 months was achieved by 64.5% of subjects and the cumulative 3-years retention rate was 56.6%. A higher EULAR response rate was recorded in patient with positivity for RF (67% in subjects tested positive vs. 58% in negative), ACPA (68% vs. 57%), aPAD4 (68% vs. 62%), and aCarP (72% vs. 62%), although statistical significance was not reached likely due to sample size limitations. Similarly, ACPA, aPAD4, aCarP were associated with higher 3-year retention rates, though not statistically significant individually. The combined analysis revealed that positivity for ACPA and/or aPAD4 predicted a significantly higher EULAR response rate at 6 months compared with double negativity (adjusted OR 2.7, p 0.026). Furthermore, positivity for at least one of ACPA, aPAD4, or aCarP predicted a significantly higher 3-year ABT retention rate compared to triple negativity (62.1% single or double positive vs. 33.5% triple negative, adjusted HR 0.48, p 0.022). This study highlights the potential benefits of using a combined assessment of ACPA aPAD4 and aCarP in predicting effectiveness of ABT in RA.

Floris A ，Angioni MM ，Fadda M ，Naitza MR ，Congia M ，Chessa E ，Piga M ，Cauli A ... -  《-》