High frequencies of activated B cells and T follicular helper cells are correlated with disease activity in patients with new-onset rheumatoid arthritis

Helper T cells: A potential target for sex hormones to ameliorate rheumatoid arthritis? (Review)

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease whose etiology is not fully understood. Defective peripheral immune tolerance and subsequent mis‑differentiation and aberrant infiltration of synovium by various immune cells, especially helper T (Th) cells, play an important role in the development of RA. There are significant sex differences in RA, but the results of studies on the effects of sex hormones on RA have been difficult to standardize and hormone replacement therapy has been limited by the potential for serious side effects. Existing research has amply demonstrated that cellular immune responses are largely determined by sex and that sex hormones play a key role in Th cell responses. Based on the aforementioned background and the plasticity of Th cells, it is reasonable to hypothesize that the action of sex hormones on Th cells will hopefully become a therapeutic target for RA. The present review discussed the role of various Th cell subsets in the pathogenesis of RA and also explored the role of sex hormones on the phenotype and function of these aberrantly regulated immune cells in RA as well as other pathologic effects on RA.

Control of T-cell immunity by fatty acid metabolism

Fatty acids play critical roles in maintaining the cellular functions of T cells and regulating T-cell immunity. This review synthesizes current research on the influence of fatty acids on T-cell subsets, including CD8+ T cells, TH1, TH17, Treg (regulatory T cells), and TFH (T follicular helper) cells. Fatty acids impact T cells by modulating signaling pathways, inducing metabolic changes, altering cellular structures, and regulating gene expression epigenetically. These processes affect T-cell activation, differentiation, and function, with implications for diseases such as autoimmune disease and cancer. Based on these insights, fatty acid pathways can potentially be modulated by novel therapeutics, paving the way for novel treatment approaches for immune-mediated disorders and cancer immunotherapy.

Evolving understanding of autoimmune mechanisms and new therapeutic strategies of autoimmune disorders

Autoimmune disorders are characterized by aberrant T cell and B cell reactivity to the body's own components, resulting in tissue destruction and organ dysfunction. Autoimmune diseases affect a wide range of people in many parts of the world and have become one of the major concerns in public health. In recent years, there have been substantial progress in our understanding of the epidemiology, risk factors, pathogenesis and mechanisms of autoimmune diseases. Current approved therapeutic interventions for autoimmune diseases are mainly non-specific immunomodulators and may cause broad immunosuppression that leads to serious adverse effects. To overcome the limitations of immunosuppressive drugs in treating autoimmune diseases, precise and target-specific strategies are urgently needed. To date, significant advances have been made in our understanding of the mechanisms of immune tolerance, offering a new avenue for developing antigen-specific immunotherapies for autoimmune diseases. These antigen-specific approaches have shown great potential in various preclinical animal models and recently been evaluated in clinical trials. This review describes the common epidemiology, clinical manifestation and mechanisms of autoimmune diseases, with a focus on typical autoimmune diseases including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and sjögren's syndrome. We discuss the current therapeutics developed in this field, highlight the recent advances in the use of nanomaterials and mRNA vaccine techniques to induce antigen-specific immune tolerance.

Helper T Cells are Hyperactive and Contribute to the Dysregulation of Antibody Production in Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease, mediated by a complex interaction between B cells and various subsets of T cells. Dysfunction of helper T (Th) and regulatory T (Treg) cells may contribute to the breakdown of self-tolerance and the progression of autoimmune disease. In this study, we investigated the activity of Th and Treg cells on the differentiation of autologous B cells in vitro using cell cultures from the peripheral blood of healthy controls (HCs) and RA patients. The expressions of programmed death 1 (PD-1) and IL-21 were monitored as activation markers for Th cells. Unstimulated Th cells from RA patients showed remarkably higher PD-1 expression than HC samples. Stimulation of Th cells from RA patients with Staphylococcus enterotoxin B (SEB) in the presence of B cells significantly induced their PD-1 and IL-21 expression at a considerably higher level in RA compared to HCs, and Treg cells did not affect IL-21 production. When monitoring B-cell differentiation, a significantly higher frequency of plasma cells was observed, even in unstimulated samples of RA patients compared to HCs. In the SEB-stimulated co-cultures of the RA samples, plasma cell frequency and IgG production were considerably higher than in HCs and were not significantly affected by Tregs. These findings demonstrate that Th cells are constitutively active in RA, and their hyperactivity upon interaction with diseased B cells may lead to uncontrolled antibody production.

Role of T follicular helper cells in autoimmune rheumatic Diseases: A systematic review on immunopathogenesis and response to treatment

BACKGROUND

T follicular helper (Tfh) cells are a subdivision of T helper cells involved in antigen-specific B cell immunity. Tfh cells play an essential role in the interaction of T cells/B cells in the germinal centers (GC), and dysregulation of Tfh actions can offer pathogenic autoantibody formation and lead to the development of autoimmune diseases. This study seeks to evaluate changes in Tfh frequency and its related cytokines in autoimmune disease, its association with disease phase, severity, prognosis, and the effect of immunosuppressive treatment on the Tfh population.

METHOD

The study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Statement. Electronic databases, including PubMed, Scopus, Web of Science, and Embase, were systematically searched for potentially eligible studies up to January 1, 2024.

RESULTS

We identified 4998 articles in the initial search, from which 1686 similar titles were removed. A total of 3312 articles were initially screened, and 3051 articles were excluded by title/abstract screening. A total of 261 studies were considered for full-text assessment, and 205 articles were excluded by reason. Finally, a total of 56 studies were included in our review.

CONCLUSION

The population of Tfh cells is generally higher in autoimmune diseases versus Health control. Moreover, the number of Tfh cells is associated with the disease severity and can be considered for determining the prognosis of studies. Also, peripheral blood circulating Tfh (cTfh) cells are an available sample that can be used as an indicator for diagnosing diseases.

High dimensional proteomic mapping of bone marrow immune characteristics in immune thrombocytopenia

To investigate the role of co-stimulatory and co-inhibitory molecules on immune tolerance in immune thrombocytopenia (ITP), this study mapped the immune cell heterogeneity in the bone marrow of ITP at the single-cell level using Cytometry by Time of Flight (CyTOF). Thirty-six patients with ITP and nine healthy volunteers were enrolled in the study. As soluble immunomodulatory molecules, more sCD25 and sGalectin-9 were detected in ITP patients. On the cell surface, co-stimulatory molecules like ICOS and HVEM were observed to be upregulated in mainly central memory and effector T cells. In contrast, co-inhibitory molecules such as CTLA-4 were significantly reduced in Th1 and Th17 cell subsets. Taking a platelet count of 30×109 L-1 as the cutoff value, ITP patients with high and low platelet counts showed different T cell immune profiles. Antigen-presenting cells such as monocytes and B cells may regulate the activation of T cells through CTLA-4/CD86 and HVEM/BTLA interactions, respectively, and participate in the pathogenesis of ITP. In conclusion, the proteomic and soluble molecular profiles brought insight into the interaction and modulation of immune cells in the bone marrow of ITP. They may offer novel targets to develop personalized immunotherapies.

The changes of intestinal flora and its relevance with memory Tfh and B cells in rheumatoid arthritis patients treated with csDMARDs and csDMARDs + bDMARDs

BACKGROUND

A growing body of experimental and clinical evidence has implicated gut microbiota in the onset and course of rheumatoid arthritis (RA). The imbalance of intestinal flora in RA patients may lead to abnormal expression of immune cells and related cytokines.

PURPOSE

Conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and conventional synthetic disease-modifying antirheumatic drugs combined with biological disease-modifying antirheumatic drugs (csDMARDs + bDMARDs) are widely used to treat RA, but the characteristics of gut microbiota before and after treatment and their relationship with memory Tfh/B cells and cytokines remain unclear.

METHODS

Stool samples were collected from 50 RA patients and 25 healthy controls (HCs) for 16SrRNA gene sequencing. We examined the proportion of lymphocyte subsets in healthy controls and RA patients. Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of related cytokines in serum. The α and β diversity of intestinal flora, and the correlation between intestinal flora and clinical indicators, lymphocyte subsets, cytokines were analyzed.

RESULT

At the genus level, Ruminococcaceae_Ruminococcus was decreased in the csDMARDs and csDMARDs + bDMARDs treatment group, whereas Faecalibacterium was reduced in the csDMARDs treatment group, compared to untreated group. CD4+CD45RO+CCR7+CXCR5+central memory Tfh cells and CD4+CD45RO+CCR7-CXCR5+effector memory Tfh cells were significantly lower in the csDMARDs + bDMARDs treatment group than in untreated group. CD19+CD27+IgD+pre-switched memory B cells were higher in the csDMARDs and csDMARDs + bDMARDs treatment groups, whereas CD19+CD27+IgD-switched memory B cells were significantly lower than in untreated group. Ruminococcaceae_Ruminococcus was negatively correlated with CD19+CD27+IgD+ pre-switched memory B cells but positively correlated with CD4+CD45RO+CCR7-CXCR5+effector memory Tfh and CD19+CD27+IgD-switched memory B cells in patients with RA treated with DMARDs.

CONCLUSION

The gut microbiota, memory Tfh cells, memory B cells, and cytokines of patients with RA changed significantly under different treatment regimens and had certain correlations with the clinical indicators of RA.

Circulating Immune Landscape Profiling in Psoriasis Vulgaris and Psoriatic Arthritis by Mass Cytometry

Background

Psoriasis, a systemic disorder mediated by the immune system, can appear on the skin, joints, or both. Individuals with cutaneous psoriasis (PsC) have an elevated risk of developing psoriatic arthritis (PsA) during their lifetime. Despite this known association, the cellular and molecular mechanisms underlying this progression remain unclear.

Methods

We performed high-dimensional, in-depth immunophenotyping of peripheral blood mononuclear cells (PBMCs) in patients with PsA and psoriasis vulgaris (PsV) by mass cytometry. Blood samples were collected before and after therapy for a longitudinal study. Then three sets of comparisons were made here: active PsA vs. active PsV, untreated PsV vs. treated PsV, and untreated PsA vs. treated PsA.

Results

Marked differences were observed in multiple lymphocyte subsets of PsA related to PsV, with expansion of CD4+ T cells, CD16- NK cells, and B cells. Notably, two critical markers, CD28 and CD127, specifically differentiated PsA from PsV. The expression levels of CD28 and CD127 on both Naïve T cells (TN) and central memory CD4+ T cells (TCM) were considerably higher in PsA than PsV. Meanwhile, after treatment, patients with PsV had higher levels of CD28hi CD127hi CD4+ TCM cells, CD28hi CD127hi CD4+ TN cells, and CD16- NK cells.

Conclusion

In the circulation of PsA patients, the TN and CD4+ TCM are characterized with more abundant CD28 and CD127, which effectively distinguished PsA from PsV. This may indicate that individuals undergoing PsV could be stratified at high risk of developing PsA based on the circulating levels of CD28 and CD127 on specific cell subsets.

Comprehensive Co-Inhibitory Receptor (Co-IR) Expression on T Cells and Soluble Proteins in Rheumatoid Arthritis

Co-inhibitory receptors (Co-IRs) are essential in controlling the progression of immunopathology in rheumatoid arthritis (RA) by limiting T cell activation. The objective of this investigation was to determine the phenotypic expression of Co-IR T cells and to assess the levels of serum soluble PD-1, PDL-2, and TIM3 in Taiwanese RA patients.

METHODS

Co-IRs T cells were immunophenotyped employing multicolor flow cytometry, and ELISA was utilized for measuring soluble PD-1, PDL-2, and TIM3. Correlations have been detected across the percentage of T cells expressing Co-IRs (MFI) and different indicators in the blood, including ESR, high-sensitivity CRP (hsCRP), 28 joint disease activity scores (DAS28), and soluble PD-1/PDL-2/TIM3.

RESULTS

In RA patients, we recognized elevated levels of PD-1 (CD279), CTLA-4, and TIGIT in CD4+ T cells; TIGIT, HLA-DR, TIM3, and LAG3 in CD8+ T cells; and CD8+CD279+TIM3+, CD8+HLA-DR+CD38+ T cells. The following tests were revealed to be correlated with hsCRP: CD4/CD279 MFI, CD4/CD279%, CD4/TIM3%, CD8/TIM3%, CD8/TIM3 MFI, CD8/LAG3%, and CD8+HLA-DR+CD38+%. CD8/LAG3 and CD8/TIM3 MFIs are linked to ESR. DAS28-ESR and DAS28-CRP exhibited relationships with CD4/CD127 MFI, CD8/CD279%, and CD8/CD127 MFI, respectively. CD4+CD279+TIM3+% was correlated with DAS28-ESR (p = 0.0084, N = 46), DAS28-CRP (p = 0.007, N = 47), and hsCRP (p = 0.002, N = 56), respectively. In the serum of patients with RA, levels of soluble PD-1, PDL-2, and Tim3 were extremely elevated. CD4+ TIM3+% (p = 0.0089, N = 46) and CD8+ TIM3+% (p = 0.0305, N = 46) were correlated with sTIM3 levels; sPD1 levels were correlated with CD4+CD279+% (p < 0.0001, N = 31) and CD3+CD279+% (p = 0.0084, N = 30).

CONCLUSIONS

Co-IR expressions on CD4+ and CD8+ T cells, as well as soluble PD-1, PDL-2, and TIM3 levels, could function as indicators of disease activity and potentially play crucial roles in the pathogenesis of RA.

Single-cell insights into immune dysregulation in rheumatoid arthritis flare versus drug-free remission

Immune-mediated inflammatory diseases (IMIDs) are typically characterised by relapsing and remitting flares of inflammation. However, the unpredictability of disease flares impedes their study. Addressing this critical knowledge gap, we use the experimental medicine approach of immunomodulatory drug withdrawal in rheumatoid arthritis (RA) remission to synchronise flare processes allowing detailed characterisation. Exploratory mass cytometry analyses reveal three circulating cellular subsets heralding the onset of arthritis flare - CD45RO+PD1hi CD4+ and CD8+ T cells, and CD27+CD86+CD21- B cells - further characterised by single-cell sequencing. Distinct lymphocyte subsets including cytotoxic and exhausted CD4+ memory T cells, memory CD8+CXCR5+ T cells, and IGHA1+ plasma cells are primed for activation in flare patients. Regulatory memory CD4+ T cells (Treg cells) increase at flare onset, but with dysfunctional regulatory marker expression compared to drug-free remission. Significant clonal expansion is observed in T cells, but not B cells, after drug cessation; this is widespread throughout memory CD8+ T cell subsets but limited to the granzyme-expressing cytotoxic subset within CD4+ memory T cells. Based on our observations, we suggest a model of immune dysregulation for understanding RA flare, with potential for further translational research towards novel avenues for its treatment and prevention.

Cartilage destruction in early rheumatoid arthritis patients correlates with CD21-/low double-negative B cells

BACKGROUND

Involvement of B cells in the pathogenesis of rheumatoid arthritis (RA) is supported by the presence of disease-specific autoantibodies and the efficacy of treatment directed against B cells. B cells that express low levels of or lack the B cell receptor (BCR) co-receptor CD21, CD21-/low B cells, have been linked to autoimmune diseases, including RA. In this study, we characterized the CD21+ and CD21-/low B cell subsets in newly diagnosed, early RA (eRA) patients and investigated whether any of the B cell subsets were associated with autoantibody status, disease activity and/or joint destruction.

METHODS

Seventy-six eRA patients and 28 age- and sex-matched healthy donors were recruited. Multiple clinical parameters were assessed, including disease activity and radiographic joint destruction. B cell subsets were analysed in peripheral blood (PB) and synovial fluid (SF) using flow cytometry.

RESULTS

Compared to healthy donors, the eRA patients displayed an elevated frequency of naïve CD21+ B cells in PB. Amongst memory B cells, eRA patients had lower frequencies of the CD21+CD27+ subsets and CD21-/low CD27+IgD+ subset. The only B cell subset found to associate with clinical factors was the CD21-/low double-negative (DN, CD27-IgD-) cell population, linked with the joint space narrowing score, i.e. cartilage destruction. Moreover, in SF from patients with established RA, the CD21-/low DN B cells were expanded and these cells expressed receptor activator of the nuclear factor κB ligand (RANKL).

CONCLUSIONS

Cartilage destruction in eRA patients was associated with an expanded proportion of CD21-/low DN B cells in PB. The subset was also expanded in SF from established RA patients and expressed RANKL. Taken together, our results suggest a role for CD21-/low DN in RA pathogenesis.

Identification of potential ferroptosis key genes and immune infiltration in rheumatoid arthritis by integrated bioinformatics analysis

Objective

Ferroptosis is of vital importance in the development of Rheumatoid arthritis (RA). The purpose of this project is to clarify the potential ferroptosis-related genes, pathways, and immune infiltration in RA by bioinformatics analysis.

Methods

We acquired ferroptosis-related genes (FRGs) from Ferroptosis database (FerrDb). We obtained the Gene dataset of RA (GSE55235) from the Gene Expression Omnibus (GEO) Database, screened the differentially expressed genes (DEGs) in RA and control samples, and then took the intersection of it and FRGs. Aiming to construct the protein-protein interaction (PPI) networks of the FRGs-DEGs, STRING database and Cytoscape software 3.7.0 would be used. Furthermore, hub genes were identified by CytoNCA, a Cytoscape plug-in. The gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment of FRGs-DEGs were performed.

Results

We identified 34 FRGs-DEGs, including 7 upregulated and 27 downregulated genes by taking the intersection of the FRGs and DEGs. PPI analysis identified a total of 3 hub genes(VEGFA, PTGS2, and JUN). GO enrichment analyses and KEGG Pathway enrichment displayed that the FRGs-DEGs are involved in the response to oxidative stress and corticosteroid, heme binding, FoxO-signal pathway. Results of immune infiltration displayed that increased infiltration of T cells, while Macrophages M2 less may be related to the occurrence of RA.

Conclusion

The hub genes involved in ferroptosis in RA may be VEGFA, PTGS2, and JUN, which are mainly involved in FoxO-signal pathway. T cell, Mac, and plasma cells may be involved in the regulation of RA-joints-synovial-inflammation.

The roles of T cells in psoriasis

Psoriasis is a recurring inflammatory skin condition characterized by scaly, red patches on the skin. It affects approximately 3% of the US population and is associated with histological changes such as epidermal hyperplasia, increased blood vessel proliferation, and infiltration of leukocytes into the skin's dermis. T cells, which are classified into various subtypes, have been found to play significant roles in immune-mediated diseases, particularly psoriasis. This paper provides a review of the different T lymphocyte subtypes and their functions in psoriasis, as well as an overview of targeted therapies for treating psoriasis.

T Follicular Helper Cells in Tertiary Lymphoid Structure Contribute to Renal Fibrosis by IL-21

Tertiary lymphoid structure (TLS) represents lymphocyte clusters in non-lymphoid organs. The formation and maintenance of TLS are dependent on follicular helper T (TFH) cells. However, the role of TFH cells during renal TLS formation and the renal fibrotic process has not been comprehensively elucidated in chronic kidney disease. Here, we detected the circulating TFH cells from 57 IgAN patients and found that the frequency of TFH cells was increased in IgA nephropathy patients with renal TLS and also increased in renal tissues from the ischemic-reperfusion-injury (IRI)-induced TLS model. The inducible T-cell co-stimulator (ICOS) is one of the surface marker molecules of TFH. Remarkably, the application of an ICOS-neutralizing antibody effectively prevented the upregulation of TFH cells and expression of its canonical functional mediator IL-21, and also reduced renal TLS formation and renal fibrosis in IRI mice in vivo. In the study of this mechanism, we found that recombinant IL-21 could directly promote renal fibrosis and the expression of p65. Furthermore, BAY 11-7085, a p65 selective inhibitor, could effectively alleviate the profibrotic effect induced by IL-21 stimulation. Our results together suggested that TFH cells contribute to TLS formation and renal fibrosis by IL-21. Targeting the ICOS-signaling pathway network could reduce TFH cell infiltration and alleviate renal fibrosis.

T cells in health and disease

T cells are crucial for immune functions to maintain health and prevent disease. T cell development occurs in a stepwise process in the thymus and mainly generates CD4+ and CD8+ T cell subsets. Upon antigen stimulation, naïve T cells differentiate into CD4+ helper and CD8+ cytotoxic effector and memory cells, mediating direct killing, diverse immune regulatory function, and long-term protection. In response to acute and chronic infections and tumors, T cells adopt distinct differentiation trajectories and develop into a range of heterogeneous populations with various phenotype, differentiation potential, and functionality under precise and elaborate regulations of transcriptional and epigenetic programs. Abnormal T-cell immunity can initiate and promote the pathogenesis of autoimmune diseases. In this review, we summarize the current understanding of T cell development, CD4+ and CD8+ T cell classification, and differentiation in physiological settings. We further elaborate the heterogeneity, differentiation, functionality, and regulation network of CD4+ and CD8+ T cells in infectious disease, chronic infection and tumor, and autoimmune disease, highlighting the exhausted CD8+ T cell differentiation trajectory, CD4+ T cell helper function, T cell contributions to immunotherapy and autoimmune pathogenesis. We also discuss the development and function of γδ T cells in tissue surveillance, infection, and tumor immunity. Finally, we summarized current T-cell-based immunotherapies in both cancer and autoimmune diseases, with an emphasis on their clinical applications. A better understanding of T cell immunity provides insight into developing novel prophylactic and therapeutic strategies in human diseases.

Pathologic and molecular insights in nodal T-follicular helper cell lymphomas

T-follicular helper (TFH) cells are one of the T-cell subsets with a critical role in the regulation of germinal center (GC) reactions. TFH cells contribute to the positive selection of GC B-cells and promote plasma cell differentiation and antibody production. TFH cells express a unique phenotype characterized by PD-1^hi, ICOS^hi, CD40L^hi, CD95^hi, CTLA^hi, CCR7^lo, and CXCR5^hi . Three main subtypes of nodal TFH lymphomas have been described: 1) angioimmunoblastic-type, 2) follicular-type, and 3) not otherwise specified (NOS). The diagnosis of these neoplasms can be challenging, and it is rendered based on a combination of clinical, laboratory, histopathologic, immunophenotypic, and molecular findings. The markers most frequently used to identify a TFH immunophenotype in paraffin-embedded tissue sections include PD-1, CXCL13, CXCR5, ICOS, BCL6, and CD10. These neoplasms feature a characteristic and similar, but not identical, mutational landscape with mutations in epigenetic modifiers (TET2, DNMT3A, IDH2), RHOA, and T-cell receptor signaling genes. Here, we briefly review the biology of TFH cells and present a summary of the current pathologic, molecular, and genetic features of nodal lymphomas. We want to highlight the importance of performing a consistent panel of TFH immunostains and mutational studies in TCLs to identify TFH lymphomas.

Human B-cell subset identification and changes in inflammatory diseases

Our understanding of the B-cell subsets found in human blood and their functional significance has advanced greatly in the past decade. This has been aided by the evolution of high dimensional phenotypic tools such as mass cytometry and single-cell RNA sequencing which have revealed heterogeneity in populations that were previously considered homogenous. Despite this, there is still uncertainty and variation between studies as to how B-cell subsets are identified and named. This review will focus on the most commonly encountered subsets of B cells in human blood and will describe gating strategies for their identification by flow and mass cytometry. Important changes to population frequencies and function in common inflammatory and autoimmune diseases will also be described.

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 CCR7^loPD1^hi 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.

Aberrant B Cell Signaling in Autoimmune Diseases

Aberrant B cell signaling plays a critical in role in various systemic and organ-specific autoimmune diseases. This is supported by genetic evidence by many functional studies in B cells from patients or specific animal models and by the observed efficacy of small-molecule inhibitors. In this review, we first discuss key signal transduction pathways downstream of the B cell receptor (BCR) that ensure that autoreactive B cells are removed from the repertoire or functionally silenced. We provide an overview of aberrant BCR signaling that is associated with inappropriate B cell repertoire selection and activation or survival of peripheral B cell populations and plasma cells, finally leading to autoantibody formation. Next to BCR signaling, abnormalities in other signal transduction pathways have been implicated in autoimmune disease. These include reduced activity of several phosphates that are downstream of co-inhibitory receptors on B cells and increased levels of BAFF and APRIL, which support survival of B cells and plasma cells. Importantly, pathogenic synergy of the BCR and Toll-like receptors (TLR), which can be activated by endogenous ligands, such as self-nucleic acids, has been shown to enhance autoimmunity. Finally, we will briefly discuss therapeutic strategies for autoimmune disease based on interfering with signal transduction in B cells.

Inflammatory Cytokine-Neutralizing Antibody Treatment Prevented Increases in Follicular Helper T Cells and Follicular Regulatory T Cells in a Mouse Model of Arthritis

Background

Follicular T helper (TFH) and follicular regulatory T (TFR) cells play important roles in humoral immunity. Nevertheless, their significance in rheumatoid arthritis (RA) pathogenesis has not been fully elucidated. As an important treatment strategy, the effect of inflammatory factor-neutralizing antibodies on TFH and TFR in RA remains unclear.

Methods

We used the collagen-induced arthritis (CIA) mouse model to illustrate the quantity and functional changes in TFH and TFR cells. The changes of plasmablast, TFH and TFR cells in the spleen and peripheral blood of CIA mice were analyzed by flow cytometry. The levels of TFH and TFR and their functional subsets in the spleen after anti-inflammatory antibody treatment were analyzed and compared. The functional changes of TFH and TFR in CIA mice before and after treatment were detected by in vitro culture experiments.

Results

Plasmablast levels were increased in CIA spleen and peripheral blood and both TFH and TFR cell levels were upregulated. TFH and TFR cells were decreased significantly after the anti-inflammatory antibody treatment. TIGIT⁺ and TIGIT⁺CD226⁻ TFH cells in CIA mouse spleen were elevated and PD-1 and ICOS expression on spleen TFH and TFR cells was increased. Both the ability of TFH cells to secrete IL-21 and aid B cells and the ability of TFR cells to secrete IL-10 and inhibit TFH cells were enhanced in the CIA mice. After antibody treatment, the cell subsets and functions were recovered.

Conclusion

Germinal center TFH and TFR cells were increased and their functions were enhanced. With inflammatory factor-neutralizing antibody treatment, TFH and TFR subsets and their functions returned to normal. These findings provide important information on the dynamics of humoral immune-related cell subsets in RA and the effects of treatment on them.

Immunomodulatory role of T helper cells in rheumatoid arthritis : a comprehensive research review

Rheumatoid arthritis (RA) is an autoimmune disease that involves T and B cells and their reciprocal immune interactions with proinflammatory cytokines. T cells, an essential part of the immune system, play an important role in RA. T helper 1 (Th1) cells induce interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α), and interleukin (IL)-2, which are proinflammatory cytokines, leading to cartilage destruction and bone erosion. Th2 cells primarily secrete IL-4, IL-5, and IL-13, which exert anti-inflammatory and anti-osteoclastogenic effects in inflammatory arthritis models. IL-22 secreted by Th17 cells promotes the proliferation of synovial fibroblasts through induction of the chemokine C-C chemokine ligand 2 (CCL2). T follicular helper (Tfh) cells produce IL-21, which is key for B cell stimulation by the C-X-C chemokine receptor 5 (CXCR5) and coexpression with programmed cell death-1 (PD-1) and/or inducible T cell costimulator (ICOS). PD-1 inhibits T cell proliferation and cytokine production. In addition, there are many immunomodulatory agents that promote or inhibit the immunomodulatory role of T helper cells in RA to alleviate disease progression. These findings help to elucidate the aetiology and treatment of RA and point us toward the next steps.

Cite this article: Bone Joint Res 2022;11(7):426–438.

T Cell Help in the Autoreactive Germinal Center

The germinal center serves as a site of B cell selection and affinity maturation, critical processes for productive adaptive immunity. In autoimmune disease tolerance is broken in the germinal center reaction, leading to production of autoreactive B cells that may propagate disease. Follicular T cells are crucial regulators of this process, providing signals necessary for B cell survival in the germinal center. Here we review the emerging roles of follicular T cells in the autoreactive germinal center. Recent advances in immunological techniques have allowed study of the gene expression profiles and repertoire of follicular T cells at unprecedented resolution. These studies provide insight into the potential role follicular T cells play in preventing or facilitating germinal center loss of tolerance. Improved understanding of the mechanisms of T cell help in autoreactive germinal centers provides novel therapeutic targets for diseases of germinal center dysfunction.

The activity level of follicular helper T cells in the peripheral blood of osteosarcoma patients is associated with poor prognosis

Osteosarcoma (OS) is solid tumors with high malignancy and incidence starting in the bones. OS pathogenesis has been proved to be closely associated with immune imbalance, and follicular helper T cells (Tfh) significantly affect host humoral immune homeostasis. However, there are few reports on the effect of Tfh cell activation on the prognosis of OS patients. Hence, this investigation on the changes in the proportion of peripheral blood Tfh cells in OS patients, and the relationship between their activity level and OS prognosis. We collected peripheral blood from patients with OS, benign bone tumor (BT group) and healthy subjects (Healthy group), respectively. The number of CD4⁺CXCR5⁺ Tfh cell in peripheral blood was measured by flow cytometry and correlation analysis between its activity and OS clinicopathological characteristics was carried out. The data showed that in comparison with the BT and Healthy groups, higher proportion and activation level of peripheral blood CD4⁺CXCR5⁺ Tfh cells in CD4⁺ T cells were found in the OS group. In OS patients, increases of the proportion and activity level of Tfh cells were associated with poorly differentiated OS and tumor metastasis. Additionally, Kaplan-Meier and Cox regression analysis showed a longer overall survival in patients with low proportion of peripheral blood CD4⁺CXCR5⁺ Tfh cells in CD4⁺ T cells, and their activation level may be a prognostic factor in OS patients. In conclusion, peripheral blood CD4⁺CXCR5⁺ Tfh cell activation in OS patients was associated with a poor prognosis. This study provided ideas for improving the clinical treatment of OS patients.