Differential expansion of T peripheral helper cells in early rheumatoid arthritis and osteoarthritis synovium

Integrated bioinformatics and clinical data identify three novel biomarkers for osteoarthritis diagnosis and synovial immune

Osteoarthritis (OA) is a degenerative joint disease that can be aggravated by synovitis and synovial immune disorders (SID). However, the role of synovial SID-related genes in OA synovium remains poorly understood. OA synovial and peripheral blood datasets were obtained from the GEO database ( https://www.ncbi.nlm.nih.gov/ ). Immune-related genes ( https://reactome.org/ ) showing differential expression in peripheral blood were identified as immune disorder genes. Subsequently, differentially expressed immune disorder genes in OA synovium were further identified as SID genes. The Venn diagram, random forest, SVM-RFE algorithm, and multivariate analysis were employed to determine SID-related hub genes in OA synovium. Using the identified hub genes, we constructed and validated a diagnostic model for predicting OA occurrence. The correlation between hub gene expression and immune-related modules was explored using CIBERSORT and MCP-counter analyses. We identified three SID-related hub genes (ACAT1, SPHK1, and ACACB) in OA synovium. The diagnostic model incorporating these hub genes demonstrated reliable predictive accuracy (AUC = 0.939). Through qPCR analysis, we quantitated the expression levels of the hub genes and confirmed that three hub genes could serve as novel biomarkers for OA patients (AUC = 0.960). Furthermore, we observed a significant correlation between the expression of these hub genes and immune cell infiltration, as well as inflammatory cytokine levels in OA synovium. Our findings suggest that three SID-related hub genes have the potential to serve as diagnostic biomarkers for OA patients. These genes are associated with immune disorder and contribute to immune alterations within the OA synovium.

T Cell Dysregulation in Rheumatoid Arthritis: from Genetic Susceptibility to Established Disease

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is a complex autoimmune disease characterized by chronic inflammation of the synovial tissue, where T cells play a central role in pathogenesis. Recent research has identified T peripheral helper (Tph) cells as critical mediators of local B cell activation in inflamed tissues. This review synthesizes the latest advancements in our understanding the of the role of T cells in RA, from initiation to established disease.

RECENT FINDINGS

We explore recent advances regarding the genetic and epigenetic factors that predispose individuals to RA, the mechanisms of T cell activation and differentiation, and the interactions between T cells and other immune and stromal cells within the synovial microenvironment. The emergence of Tph cells as key drivers of RA pathobiology is highlighted, along with their potential as therapeutic targets. We also discuss the heterogeneity of T cell responses and their interplay with synovial cells, while addressing critical research gaps such as the drivers of T cell recruitment and the plasticity of synovial phenotypes. A deeper understanding of T cell dynamics in RA will provide valuable insights for developing targeted therapies to modulate T cell-mediated inflammation and improve patient outcomes.

Homeostatic signals, including IL-7 and self-MHC recognition, induce the development of peripheral helper T cells, which are enriched in the joints of rheumatoid arthritis

Objective

Dysregulated T cell homeostasis has long been implicated in the pathogenesis of rheumatoid arthritis (RA), in the joint of which peripheral helper T (Tph) cells accumulate and form ectopic lymphoid organs. We examined whether homeostatic signals are involved in the development of Tph cells.

Methods

Human peripheral blood mononuclear cells were cultured with IL-7, the critical cytokine for T cell homeostasis. Development of Tph-like cells was assessed by flow cytometry, gene expression, and functional analysis. Chemotaxis of the Tph-like cells to RA synovial fluid (RASF) and the effect of RASF on the development of Tph-like cells was examined.

Results

PD-1highCXCR5- Tph-like cells developed from human peripheral blood CD4 T cells after proliferation in response to IL-7. Signals from self-MHC recognition and CD28 co-stimulation were also involved. The IL-7-induced Tph-like (IL-7-Tph) cells produced CXCL13 and IL-21 and helped B cells produce IgG. Comprehensive gene expression analysis further supported the similarity with Tph cells in RA joint. IL-7-Tph cells exhibited chemotaxis toward synovial fluid from RA patients (RASF), and RASF promoted the development of IL-7-Tph cells, which were also induced from CD4 T cells residing in non-inflamed joints.

Conclusions

Our results demonstrate an antigen-nonspecific developmental pathway of Tph cells triggered by homeostatic signals and promoted by the local environment of RA, which accounts for the accumulation of Tph cells in inflamed joints.

A detailed quantitative analysis of circulating T peripheral and follicular helper lymphocytes in patients with rheumatoid arthritis and systemic lupus erythematosus

INTRODUCTION AND OBJECTIVE

Peripheral and follicular helper T lymphocytes (Tph and Tfh, respectively) have an important role in B cell immune responses and the pathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Although several studies on the number of Tph and Tfh cells in these conditions have been published, different phenotypes have been employed for their analysis. In this study, we assessed the levels and function of Tph and Tfh cells in blood samples from patients with RA and SLE by using an extended immunophenotype.

MATERIALS AND METHODS

In a cross-sectional pilot study, blood samples from twenty-seven patients with RA and fifteen with SLE, and twenty-six healthy controls were studied. The levels of Tph (CD4+PD-1+CXCR5-CD38+CD69+ICOS+) and Tfh (CD4+PD-1+CXCR5+CD38+CD69+ICOS+) cells were analyzed by flow cytometry. In addition, the function of Tph/Tfh cells was estimated by measuring the synthesis of IL-21 by these lymphocytes as well as the number of circulating plasmablasts (CD19+CD27+CD20-CD38hi).

RESULTS

Increased percentages of Tph and Tfh lymphocytes were detected in patients with RA and SLE. Furthermore, the synthesis of IL-21 tended to be higher in both conditions, and higher levels of plasmablasts were detected in these patients, compared to controls. In patients with SLE, the number of Tph cells was associated with disease activity and with the levels of circulating plasmablasts, whereas in patients with RA a significant correlation between Tph cells and evolution time was observed.

DISCUSSION AND CONCLUSIONS

Our data of Tph and Tfh lymphocytes, based in the analysis of an extended phenotype of these cells, provides further evidence on their involvement in the pathogenesis of RA and SLE.

Integration of single-cell and bulk RNA sequencing revealed immune heterogeneity and its association with disease activity in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic, inflammatory, systemic autoimmune disease characterized by cartilage, bone damage, synovial inflammation, hyperplasia, autoantibody production, and systemic features. To obtain an overall profile of the immune environment in RA patients and its association with clinical features, we performed single-cell transcriptome and T-cell receptor sequencing of mononuclear cells from peripheral blood (PBMC) and synovial fluid (SF) from RA patients, integrated with two large cohorts with bulk RNA sequencing for further validation and investigation. Dendritic cells (DCs) exhibited relatively high functional heterogeneity and tissue specificity in relation to both antigen presentation and proinflammatory functions. Peripheral helper T cells (TPHs) are likely to originate from synovial tissue, undergo activation and exhaustion, and are subsequently released into the peripheral blood. Notably, among all immune cell types, TPHs were found to have the most intense associations with disease activity. In addition, CD8 effector T cells could be clustered into two groups with different cytokine expressions and play distinct roles in RA development. By integrating single-cell data with bulk sequencing from two large cohorts, we identified interactions among TPHs, CD8 cells, CD16 monocytes, and DCs that strongly contribute to the proinflammatory local environment in RA joints. Of note, the swollen 28-joint counts exhibited a more pronounced association with this immune environment compared to other disease activity indexes. The immune environment alternated significantly from PBMCs to SF, which indicated that a series of immune cells was involved in proinflammatory responses in the local joints of RA patients. By integrating single-cell data with two large cohorts, we have uncovered associations between specific immune cell populations and clinical features. This integration provides a rapid and precise methodology for assessing local immune activation, offering valuable insights into the pathophysiological mechanisms at play in RA.

Characteristics of PD-1+CD4+ T cells in peripheral blood and synovium of rheumatoid arthritis patients

Objectives

PD-1 plays a crucial role in the immune dysregulation of rheumatoid arthritis (RA), but the specific characteristics of PD-1+CD4+ T cells remain unclear and require further investigation.

Methods

Circulating PD-1+CD4+ T cells from RA patients were analysed using flow cytometry. Plasma levels of soluble PD-1 (sPD-1) were measured using enzyme-linked immunosorbent assay (ELISA). Single-cell RNA sequence data from peripheral blood mononuclear cells (PBMCs) and synovial tissue of patients were obtained from the GEO and the ImmPort databases. Bioinformatics analyses were performed in the R studio to characterise PD-1+CD4+ T cells. Expression of CCR7, KLF2 and IL32 in PD-1+CD4+ T cells was validated by flow cytometry.

Results

RA patients showed an elevated proportion of PD-1+CD4+ T cells in peripheral blood, along with increased plasma sPD-1 levels, which positively correlated with TNF-α and erythrocyte sedimentation rate. Bioinformatic analysis revealed PD-1 expression on CCR7+CD4+ T cells in PBMCs, and on both CCR7+CD4+ T cells and CXCL13+CD4+ T cells in RA synovium. PD-1 was co-expressed with CCR7, KLF2, and IL32 in peripheral CD4+ T cells. In synovium, PD-1+CCR7+CD4+ T cells had higher expression of TNF and LCP2, while PD-1+CXCL13+CD4+ T cells showed elevated levels of ARID5A and DUSP2. PD-1+CD4+ T cells in synovium also appeared to interact with B cells and fibroblasts through BTLA and TNFSF signalling pathways.

Conclusion

This study highlights the increased proportion of PD-1+CD4+ T cells and elevated sPD-1 levels in RA. The transcriptomic profiles and signalling networks of PD-1+CD4+ T cells offer new insights into their role in RA pathogenesis.

T peripheral helper (Tph) cells, a marker of immune activation in cancer and autoimmune disorders

T peripheral helper (Tph) cells are a newly discovered subtype of CD4+ T cells that have emerged as the counterpart of T follicular helper (Tfh) cells in the peripheral tissues. These two cell types share some common characteristics, such as high levels of PD1 and CXCL13 expression, but differ in the expression of transcription factors and chemokine receptors. Tph cells have been studied in relation to B cells' effector functions, including cytokines production and antibody-mediated immune responses. However, their role in the inflammatory-mediated development of malignancies remains poorly understood. Tph cells were initially identified in the synovium of rheumatoid arthritis patients and have since been found to be expanded in several autoimmune diseases. They have been linked to a worse prognosis in autoimmune conditions, but intriguingly, their presence has been correlated with better outcomes in certain types of cancer. The functions of Tph cells are still being investigated, but recent data suggests their involvement in the assembly of tertiary lymphoid structures (TLS). Furthermore, their interaction with B cells, which have been mainly described as possessing a memory phenotype, promotes their development. In this review, we explore the role of Tph cells in peripheral immune responses during cancer and autoimmune disorders.

In patients at high risk for RA, abatacept reduced inflammation and RA development at 6 mo

SOURCE CITATION

Rech J, Tascilar K, Hagen M, et al. Abatacept inhibits inflammation and onset of rheumatoid arthritis in individuals at high risk (ARIAA): a randomised, international, multicentre, double-blind, placebo-controlled trial. Lancet. 2024;403:850-859. 38364841.

Peripheral helper T cells in human diseases

Peripheral helper T cells (Tph) are a specialized subset of CD4+ T cells with the ability to help B cells and induce antibody production. Although usually located in ectopic lymphoid-like structures (ELS), inside the peripheral blood, Tph cells can also be identified. The aberrant proliferation and functions of Tph cells are commonly found in the patients with disease. In this review, first we will summarize the biological characteristics of Tph cells, such as the expression of surface molecules, transcription factors and cytokines, and discuss its B cell help functions. Tph cells also have roles in a wide range of human diseases, including autoimmune diseases, infectious diseases, malignancies etc. Therefore, there is a strong interest in targeting Tph cells to improve treat strategies of human diseases.

Immune checkpoints in rheumatoid arthritis: progress and promise

Rheumatoid arthritis (RA) is one of the most prevalent autoimmune inflammatory conditions, and while the mechanisms driving pathogenesis are yet to be completely elucidated, self-reactive T cells and immune checkpoint pathways have a clear role. In this review, we provide an overview of the importance of checkpoint pathways in the T cell response and describe the involvement of these in RA development and progression. We discuss the relationship between immune checkpoint therapy in cancer and autoimmune adverse events, draw parallels with the involvement of immune checkpoints in RA pathobiology, summarise emerging research into some of the lesser-known pathways, and the potential of targeting checkpoint-related pathways in future treatment approaches to RA management.

Efficacy and safety of Duhuo-Jisheng decoction in rheumatoid arthritis: A systematic review and meta-analysis of 42 randomized controlled trials

BACKGROUND

Duhuo-Jisheng decoction (DJD) is a Chinese herb formula. Previous studies have reported that the clinical symptoms and laboratory indicators of rheumatoid arthritis (RA) patients could be improved by DJD. However, the existing evidence was not robust enough and controversial.

METHODS

Randomized controlled trials of DJD for RA were retrieved from Chinese and English databases from their inception to April 16, 2023. Meta-analysis was performed by Stata 17 software. We used subgroup analysis, meta-regression, and sensitivity analysis to identify potential sources of heterogeneity. The subgroup analysis and meta-regression were conducted from 6 aspects, including age, course of disease, course of treatment, interventions used in the experimental or control group, and random sequence generation. Galbraith plot was used to find studies with possible heterogeneity. Publication bias was assessed by Egger's test and funnel plots when the number of relevant studies was greater than or equal to 10.

RESULTS

Forty-two studies were included, involving 3635 patients and 19 outcome indicators. Meta-analysis showed that, compared with the routine disease-modifying antirheumatic drugs (rDMARDs), DJD could better improve the level of laboratory indicators, main symptoms and signs, and questionnaire scores of RA patients. The laboratory indicators included rheumatoid factor, T lymphocyte subpopulation (including CD4+, CD8+, and CD4+/CD8+), and inflammatory biomarkers (including erythrocyte sedimentation rate, C-reactive protein, tumor necrosis factor-α, interleukin 6, interleukin 1β, and interleukin 1). The main symptoms and signs included the duration of morning stiffness, the number of joint tenderness, the number of swollen joints, and the grip strength of both hands. The questionnaire included visual analogue scale, health assessment questionnaire, and disease activity score in 28 joints. In addition, the adverse events of DJD treatment were significantly lower than those of rDMARDs. However, the results of a few subgroup analyses differed from the overall results. Furthermore, the publication bias assessment showed that, out of 11 evaluated results, 4 had publication bias.

CONCLUSION

DJD could be a satisfactory complementary and alternative therapy for RA. However, due to a small number of subgroup analysis results being different from the overall results, it should be verified by further studies.