Tfh Cell Function Research Articles

BAFF promotes follicular helper T cell development and germinal center formation through BR3 signal.

T follicular helper (Tfh) cells represent an important subset of CD4+ T cells that is crucial to the maturation and differentiation of B cells and the production of high-affinity antibodies. Because B cell activating-factor (BAFF), a vital B cell survival factor, is also crucial to B cell maturation and differentiation, we assessed the effects of BAFF on Tfh cell development and function. We demonstrated that deficiency of BAFF, but not of APRIL, markedly inhibited Tfh cell development, germinal center (GC) formation, and antigen-specific antibody production. The promoting effect of BAFF on Tfh cell development was dependent on expression of BR3 on T cells, and its promoting effect on GC formation was dependent on expression of BR3 on both T cells and B cells. BAFF directly promoted expression of the Tfh cell-characteristic genes via NF-κB signaling. This effect did need BR3 expression. Thus, BAFF not only has direct effects on B cells, but it also has direct effects on Tfh cell differentiation via engagement of BR3, which collectively promoted GC formation and production of high-affinity antibodies. This dual effect of BAFF on B cells and Tfh cells may help explain the clinical utility of BAFF antagonists in the management of certain autoimmune diseases.

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

Introduction and objectivePeripheral 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 methodsIn 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). ResultsIncreased 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 conclusionsOur 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.

The role of dendritic cells in the instruction of helper T cells in the allergic march.

Allergy is a complex array of diseases influenced by innate and adaptive immunity, genetic polymorphisms, and environmental triggers. Atopic dermatitis is a chronic inflammatory skin disease characterized by barrier defects and immune dysregulation, sometimes leading to asthma and food allergies because of the atopic march. During atopic skin inflammation, Langerhans cells and dendritic cells (DCs) in the skin capture and deliver allergen information to local lymph nodes. DCs are essential immune sensors coordinating immune reactions by capturing and presenting antigens to T cells. In the context of allergic responses, DCs play a crucial role in instructing two types of helper T cells-type 2 helper T (Th2) cells and follicular helper T (TFH) cells-in allergic responses and IgE antibody responses. In skin sensitization, the differentiation and function of Th2 cells and TFH cells are influenced by skin-derived factors, including epithelial cytokines, chemokines, and signalling pathways to modify the function of migratory DCs and conventional DCs. In this review, we aim to understand the specific mechanisms involving DCs in allergic responses to provide insights into the pathogenesis of allergic diseases and potential therapeutic strategies.

RACK1 enhances STAT3 stability and promotes T follicular helper cell development and function during blood-stage Plasmodium infection in mice.

CD4+ T cells are central mediators of protective immunity to blood-stage malaria, particularly for their capacity in orchestrating germinal center reaction and generating parasite-specific high-affinity antibodies. T follicular helper (Tfh) cells are predominant CD4+ effector T cell subset implicated in these processes, yet the factors and detailed mechanisms that assist Tfh cell development and function during Plasmodium infection are largely undefined. Here we provide evidence that receptor for activated C kinase 1 (RACK1), an adaptor protein of various intracellular signals, is not only important for CD4+ T cell expansion as previously implied but also plays a prominent role in Tfh cell differentiation and function during blood-stage Plasmodium yoelii 17XNL infection. Consequently, RACK1 in CD4+ T cells contributes significantly to germinal center formation, parasite-specific IgG production, and host resistance to the infection. Mechanistic exploration detects specific interaction of RACK1 with STAT3 in P. yoelii 17XNL-responsive CD4+ T cells, ablation of RACK1 leads to defective STAT3 phosphorylation, accompanied by substantially lower amount of STAT3 protein in CD4+ T cells, whereas retroviral overexpression of RACK1 or STAT3 in RACK1-deficient CD4+ T cells greatly restores STAT3 activity and Bcl-6 expression under the Tfh polarization condition. Further analyses suggest RACK1 positively regulates STAT3 stability by inhibiting the ubiquitin-proteasomal degradation process, thus promoting optimal STAT3 activity and Bcl-6 induction during Tfh cell differentiation. These findings uncover a novel mechanism by which RACK1 participates in posttranslational regulation of STAT3, Tfh cell differentiation, and subsequent development of anti-Plasmodium humoral immunity.

Total Alkaloids of Sophora alopecuroides Linn. Attenuates Rheumatoid Arthritis Through Regulating Follicular Helper T Cells.

Rheumatoid arthritis (RA) is a chronic autoimmune disease with abnormal differentiation of follicular helper T (Tfh) cells, Total alkaloids of Sophora alopecuroides Linn. (Leguminosae) (TASA) have potential effects on collagen-induced arthritis (CIA) mice, while the mechanism needs further elucidation. The purpose of this study is to explore the regulation of TASA on rheumatoid arthritis and related mechanism. The proportion of Tfh and B lymphocytes in peripheral blood lymphocytes of RA patients was examined by flow cytometry. We constructed the collagen induced arthritis DBA/1J mice model. Between days 15 and 45 following the first immunization, the mice were treated intraperitoneally with saline, TASA (100, 50, and 25 mg/kg), and dexamethasone (DXM) for 30 days. Molecular biological techniques such as FCM, PCR, ELISA, and Western-blotting were used to examine Tfh cells and associated signal pathways. Our results indicated that the follicular helper T cells and B lymphocytes in rheumatoid arthritis patients were significantly increased compared with the healthy control. The percentage of Tfh cells are correlated with RA related inflammatory factors. Total alkaloids of Sophora alopecuroides Linn. could significantly attenuate joint swelling. Meanwhile, it reduced the frequencies of spleen Tfh, B lymphocytes and the expression of TLR2, TLR9, p-NF-κBp65, CXCR5, Bcl-6, ICOS of ankle joints in CIA mice. Total alkaloids of Sophora alopecuroides Linn. may down-regulate the frequency and function of Tfh cells and inhibit GCB cells via TLRs/NF-κB signal pathway to relieve the immune-pathological progression of CIA mice.

Regulation of the Function of T Follicular Helper Cells and B Cells in Type 1 Diabetes Mellitus by the OX40/OX40L Axis.

To study the expression of OX40 on T follicular helper (Tfh) cells and the ligand OX40L on antigen-presenting cells (APCs) in peripheral blood of patients with Type 1 diabetes mellitus (T1DM) and the role of OX40 signaling in promoting Tfh cells to assist B-cell differentiation. Cross-sectional study. Endocrinology department of a university hospital. Twenty-five patients with T1DM and 35 with newly diagnosed T2DM from January 2021-December 2021 (39 males, 21 females; mean age: 31.0 ± 4.5, range: 19-46 years). None. The peripheral blood proportion of CD4+CD25-CD127+CXCR5+PD1+ Tfh cells in patients with T1DM or T2DM and the OX40L expression in CD14+ monocytes and CD19+ B cells were analyzed by flow cytometry. The OX40 signal effect on Tfh-cell function was analyzed by co-incubating B cells with Tfh cells under different conditions. Flow cytometry detected the ratio of CD19-CD138+ plasmacytes. The Tfh cells ratio and intracellular IL-21 expression in peripheral blood was significantly higher in patients with T1DM than with T2DM, and the OX40 expression in peripheral Tfh cells and OX40L expression in APC were significantly higher in T1DM. After adding OX40L protein, the CD19-CD138+-plasmacytes percentage was significantly increased and higher in T1DM. Blocking of anti-OX40L monoclonal antibodies significantly reduced the plasmacytes ratio. The peripheral Tfh cells proportion increased and the OX40 expression in peripheral Tfh cells was upregulated in patients with T1DM versus patients with T2DM. OX40/OX40L signaling enhanced the Tfh-cell function to assist B-cell differentiation, which may contribute to the pathogenesis of T1DM.

TLR7 enhancing follicular helper T (Tfh) cells response in C57BL/6 mice infected with Plasmodium yoelii NSM TLR7 mediated Tfh cells in P. yoelii infected mice.

Toll-like receptors (TLRs) play an important role in inducing innate and acquired immune responses against infection. However, the effect of Toll-like receptor 7 (TLR7) on follicular helper T (Tfh) cells in mice infected with Plasmodium is still not clear. The results showed that the splenic CD4+ CXCR5+ PD-1+ Tfh cells were accumulated after Plasmodium yoelii NSM infection, the content of splenic Tfh cells was correlated to parasitemia and/or the red blood cells (RBCs) counts in the blood. Moreover, the expression of TLR7 was found higher than TLR2, TLR3 and TLR4 in splenic Tfh cells of the WT mice. TLR7 agonist R848 and the lysate of red blood cells of infected mice (iRBCs) could induce the activation and differentiation of splenic Tfh cells. Knockout of TLR7 leads to a decrease in the proportion of Tfh cells, down-regulated expression of functional molecules CD40L, IFN-γ, IL-21 and IL-10 in Tfh cells; decreased the proportion of plasma cells and antibody production and reduces the expression of STAT3 and Ikzf2 in Tfh cells. Administration of R848 could inhibit parasitemia, enhance splenic Tfh cell activation and increase STAT3 and Ikzf2 expression in Tfh cells. In summary, this study shows that TLR7 could regulate the function of Tfh cells, affecting the immune response in the spleen of Plasmodium yoelii NSM-infected mice.

IL-21-producing effector Tfh cells promote B cell alloimmunity in lymph nodes and kidney allografts.

Follicular helper T (Tfh) cells have been implicated in controlling rejection after allogeneic kidney transplantation, but the precise subsets, origins, and functions of Tfh cells in this process have not been fully characterized. Here we show that a subset of effector Tfh cells marked by previous IL-21 production is potently induced during allogeneic kidney transplantation and is inhibited by immunosuppressive agents. Single-cell RNA-Seq revealed that these lymph node (LN) effector Tfh cells have transcriptional and clonal overlap with IL-21-producing kidney-infiltrating Tfh cells, implicating common origins and developmental trajectories. To investigate the precise functions of IL-21-producing effector Tfh cells in LNs and allografts, we used a mouse model to selectively eliminate these cells and assessed allogeneic B cell clonal dynamics using a single B cell culture system. We found that IL-21-producing effector Tfh cells were essential for transplant rejection by regulating donor-specific germinal center B cell clonal dynamics both systemically in the draining LN and locally within kidney grafts. Thus, IL-21-producing effector Tfh cells have multifaceted roles in Ab-mediated rejection after kidney transplantation by promoting B cell alloimmunity.

Tfh and Tfr Cells in Autoimmune Diseases

An immunological condition known as autoimmunity causes the excessive generation of autoantibodies against self-antigen and is characterized by enhanced T-cell activation and extra-stimulated B-cells. The development of lymphatic follicle germinal centers (GCs), the maturation of B cells, and differentiation into plasma cells are all significantly aided by follicular helper T cells (Tfh). Tfh cells express the transcriptional regulator B cell lymphoma 6 (BCL-6), C-X-C chemokine receptor 5 (CXCR5), inducible T cell co-stimulator (ICOS), and programmed cell death protein 1 (PD-1). The production of interleukin (IL)-21 and low expression of the chemokine (C-C motif) receptor 7 (CCR7) define Tfh cells. Additionally, Tfh cells are a diverse population of cells with the potential to co-express minute quantities of transcription factors, such as T-box expressed in T cells (T-bet), GATA-binding protein 3 (GATA-3), and retinoic acid receptor-related orphan receptor (ROR-t). Tfh cells that also produce IL-21, IL-4, IL-17, and IFN-γ are referred to as Tfh1, Tfh2, and Tfh17 cells, respectively. The control of humoral immunity is carried out by follicular regulatory (Tfr) cells that express Forkhead box protein 3 (Foxp3). Tfr cells can, however, decrease T-B cell interactions through the cytotoxic T lymphocyte-associated protein 4 (CTLA-4) while promoting B cell maturation through IL-10. In the context of autoimmunity, the role of Tfh and Tfr cells is still not fully understood. We intend to present the most recent data on the characteristics and function of Tfh and Tfr cells under conditions of autoimmunity in this review.

Iguratimod suppresses Tfh cell differentiation in primary Sjögren’s syndrome patients through inhibiting Akt/mTOR/STAT3 signaling

BackgroundIguratimod (IGU) reduces hypergammaglobulinemia and disease activity in pSS (primary Sjögren’s syndrome) patients. However, the therapeutical mechanism of IGU for pSS remains largely unknown. This study aimed to investigate the regulation of Tfh cell differentiation by IGU in pSS patients.MethodsWe prospectively enrolled 13 pSS patients treated with IGU for 3 months and examined circulating T cell and B cell subsets by flow cytometry. We measured Tfh cell differentiation treated by IGU in pSS patients and healthy controls. Transcriptome analysis combined with molecular docking were employed to identify potential therapeutical targets of IGU, which were verified by Western blot and Tfh cell differentiation.ResultsTfh, plasmablast, and plasma cells were suppressed by IGU treatment at 1 and 3 months. Tfh cell differentiation and function were significant inhibited by IGU in pSS patients and healthy controls in vitro. Pyruvate dehydrogenase kinase 1 (PDK1) was identified as a target of IGU during Tfh cell differentiation, and the downstream Akt phosphorylation was attenuated by IGU. Moreover, the activity of mTORC1 and phosphorylation of STAT3 were suppressed by IGU, with downregulation of BCL6 and upregulation of PRDM1. Finally, Akt activator restored IGU-suppressed Tfh cell differentiation.ConclusionsIGU suppresses Tfh cell differentiation in pSS patients through interacting with PDK1 and suppressing Akt-mTOR-STAT3 signaling.

T follicular helper cells and T follicular regulatory cells in autoimmune diseases.

T follicular helper (Tfh) cells are heterogeneous and mainly characterized by expressing surface markers CXCR5, ICOS, and PD-1; cytokine IL-21; and transcription factor Bcl6. They are crucial for B-cell differentiation into long-lived plasma cells and high-affinity antibody production. T follicular regulatory (Tfr) cells were described to express markers of conventional T regulatory (Treg) cells and Tfh cells and were able to suppress Tfh-cell and B-cell responses. Evidence has revealed that the dysregulation of Tfh and Tfr cells is positively associated with the pathogenic processes of autoimmune diseases. Herein, we briefly introduce the phenotype, differentiation, and function of Tfh and Tfr cells, and review their potential roles in autoimmune diseases. In addition, we discuss perspectives to develop novel therapies targeting Tfh/Tfr balance.

Targeting Bcl-6 prevents sclerodermatous chronic graft-versus-host disease by abrogating T follicular helper differentiation in mice.

Chronic graft-versus-host disease (cGVHD) is the most common cause of non-relapse mortality (NRM) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). CD4+ follicular helper T (Tfh) cells, specialized providers of T cell help to B cells, play a vital role in GVHD pathogenesis. B-cell lymphoma-6 (Bcl-6) transcription factor has been shown to be required for Tfh-mediated germinal center reactions. In this study, we would like to evaluate the effect of Bcl-6 on Tfh function in sclerodermatous cGVHD and the efficacy of Bcl-6 inhibitors (Bcl-6i) for treating a minor histocompatibility complex (miHC) mismatch model of sclerodermatous cGVHD (scl-cGVHD). A minor histocompatibility haploidentical model of scl-cGVHD was established and received intraperitoneal injection of 79-6, a small-molecule inhibitor of Bcl-6. The clinical manifestations and survival times of cGVHD mice were recorded. The histological assessment was performed by hematoxylin-eosin (HE) and Masson's trichrome staining on the skin and lung tissues. Tfh cells and germinal center B cells in the spleen and peripheral blood were detected by flow cytometry. The cellular markers were immunostained in different organs. ELISA was performed to detect cytokine secretion. Bcl-6 inhibition by 79-6 improved the clinical manifestation of scl-cGVHD mice and prolonged their survival. The histopathologic damage, particular the fibrotic changes of scl-cGVHD mice was significantly relieved after 79-6 treatment. Furthermore, 79-6 treatment not only suppressed the development and function of Tfh and Tph cells in the peripheral blood, but also reduced the survival of Tfh cells in the spleen. Moreover, 79-6 decreased the frequency of GC plasmocytes accompanied by a reduction in IL-21. Our study demonstrates that Bcl-6 inhibitor could prevent murine sclerodermatous chronic graft-versus-host disease by abrogating T follicular helper differentiation and suppressing the function of GC B cells, indicating that Bcl-6 inhibition may be a potential treatment for patients with cGVHD.

Human PIK3R1 mutations disrupt lymphocyte differentiation to cause activated PI3Kδ syndrome 2.

Heterozygous loss-of-function (LOF) mutations in PIK3R1 (encoding phosphatidylinositol 3-kinase [PI3K] regulatory subunits) cause activated PI3Kδ syndrome 2 (APDS2), which has a similar clinical profile to APDS1, caused by heterozygous gain-of-function (GOF) mutations in PIK3CD (encoding the PI3K p110δ catalytic subunit). While several studies have established how PIK3CD GOF leads to immune dysregulation, less is known about how PIK3R1 LOF mutations alter cellular function. By studying a novel CRISPR/Cas9 mouse model and patients' immune cells, we determined how PIK3R1 LOF alters cellular function. We observed some overlap in cellular defects in APDS1 and APDS2, including decreased intrinsic B cell class switching and defective Tfh cell function. However, we also identified unique APDS2 phenotypes including defective expansion and affinity maturation of Pik3r1 LOF B cells following immunization, and decreased survival of Pik3r1 LOF pups. Further, we observed clear differences in the way Pik3r1 LOF and Pik3cd GOF altered signaling. Together these results demonstrate crucial differences between these two genetic etiologies.

Multidimensional Analysis of Lung Lymph Nodes in a Mouse Model of Allergic Lung Inflammation following and Indeno[1,2,3-cd]pyrene Exposure.

Ambient particulate matter with an aerodynamic diameter of () is suggested to act as an adjuvant for allergen-mediated sensitization and recent evidence suggests the importance of T follicular helper (Tfh) cells in allergic diseases. However, the impact of exposure and its absorbed polycyclic aromatic hydrocarbon (PAHs) on Tfh cells and humoral immunity remains unknown. We aimed to explore the impact of environmental and indeno[1,2,3-cd]pyrene (IP), a prominent PAH, as a model, on Tfh cells and the subsequent pulmonary allergic responses. - or IP-mediated remodeling of cellular composition in lung lymph nodes (LNs) was determined by mass cytometry in a house dust mite (HDM)-induced mouse allergic lung inflammation model. The differentiation and function of Tfh cells in vitro were analyzed by flow cytometry, quantitative reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, chromatin immunoprecipitation, immunoprecipitation, and western blot analyses. Mice exposed to during the HDM sensitization period demonstrated immune cell population shifts in lung LNs as compared with those sensitized with HDM alone, with a greater number of differentiated Tfh2 cells, enhanced allergen-induced immunoglobulin E (IgE) response and pulmonary inflammation. Similarly enhanced phenotypes were also found in mice exposed to IP and sensitized with HDM. Further, IP administration was found to induce interleukin-21 (Il21) and Il4 expression and enhance Tfh2 cell differentiation in vitro, a finding which was abrogated in aryl hydrocarbon receptor (AhR)-deficient T cells. Moreover, we showed that IP exposure increased the interaction of AhR and cellular musculoaponeurotic fibrosarcoma (c-Maf) and its occupancy on the Il21 and Il4 promoters in differentiated Tfh2 cells. These findings suggest that the (IP)-AhR-c-Maf axis in Tfh2 cells was important in allergen sensitization and lung inflammation, thus adding a new dimension in the understanding of Tfh2 cell differentiation and function and providing a basis for establishing the environment-disease causal relationship. https://doi.org/10.1289/EHP11580.

AP-1-independent NFAT signaling maintains follicular T cell function in infection and autoimmunity.

Coordinated gene expression programs enable development and function of T cell subsets. Follicular helper T (Tfh) cells coordinate humoral immune responses by providing selective and instructive cues to germinal center B cells. Here, we show that AP-1-independent NFAT gene expression, a program associated with hyporesponsive T cell states like anergy or exhaustion, is also a distinguishing feature of Tfh cells. NFAT signaling in Tfh cells, maintained by NFAT2 autoamplification, is required for their survival. ICOS signaling upregulates Bcl6 and induces an AP-1-independent NFAT program in primary T cells. Using lupus-prone mice, we demonstrate that genetic disruption or pharmacologic inhibition of NFAT signaling specifically impacts Tfh cell maintenance and leads to amelioration of autoantibody production and renal injury. Our data provide important conceptual and therapeutic insights into the signaling mechanisms that regulate Tfh cell development and function.

ICOS costimulation is indispensable for the differentiation of T follicular regulatory cells.

ICOS is a T-cell costimulatory receptor critical for Tfh cell generation and function. However, the role of ICOS in Tfr cell differentiation remains unclear. Using Foxp3-Cre-mediated ICOS knockout (ICOS FC) mice, we show that ICOS deficiency in Treg-lineage cells drastically reduces the number of Tfr cells during GC reactions but has a minimal impact on conventional Treg cells. Single-cell transcriptome analysis of Foxp3+ cells at an early stage of the GC reaction suggests that ICOS normally inhibits Klf2 expression to promote follicular features including Bcl6 up-regulation. Furthermore, ICOS costimulation promotes nuclear localization of NFAT2, a known driver of CXCR5 expression. Notably, ICOS FC mice had an unaltered overall GC B-cell output but showed signs of expanded autoreactive B cells along with elevated autoantibody titers. Thus, our study demonstrates that ICOS costimulation is critical for Tfr cell differentiation and highlights the importance of Tfr cells in maintaining humoral immune tolerance during GC reactions.

Dysregulation of memory B cells and circulating T follicular helper cells is a predictor of poor immune recovery in HIV‐infected patients on antiretroviral therapy

T follicular helper (Tfh) cells and their interactions with B cells within the germinal center play extensive roles in human immunodeficiency virus (HIV) pathology. However, their association with immune reconstitution during antiretroviral therapy (ART) is still unclear. The aim of this study was to determine the impact of Tfh and memory B cell function on T helper cell recovery in patients with acute or chronic HIV infection. A total of 100 HIV-infected individuals were enrolled in our study, classified into acute and chronic HIV infection groups (60 and 40, respectively), and subsequently classified into immunological responder (IR) and immunological nonresponder (INR) subgroups according to immune recovery outcomes after 96 weeks of ART. Liquid chromatography-mass spectrometry was used to quantify the temporal regulation patterns of B and CD4+ T-cell profiles among patients, and flow cytometry was used to investigate certain subsets of B and T cells. Here we showed that the prevalence of Tfh cells in the T helper cell population correlated negatively with CD4+ T-cell recovery. The proportion of CXCR3- Tfh cells in patients with acute or chronic infection was associated with CD4+ T-cell count recovery, and the proportion of CD21+ memory B cells at baseline was significantly higher in those with improved immune recovery outcomes. Universal proteomic dysregulation of B and CD4+ T cells at baseline was detected in patients with acute infected and poor CD4+ T-cell recovery. Proteomics analysis revealed distinct temporal regulation profiles of both T helper cells and B cells between IRs and INRs among patients with acute infection. Our results suggest that the functions of memory B cells in INRs are dysregulated at the early stage of ART, possibly through disruption of Tfh cell function. The frequency and function of Tfh cells and their subsets are potential predictors of poor immune recovery.

Regulation of follicular T helper cell differentiation in antitumor immunity.

Follicular T helper (Tfh) cells are a subset of CD4+ T cells that play an important role in the formation of germinal centers and the maturation and differentiation of affinity-matured B cells. Recent studies have demonstrated important functions of Tfh cells in tertiary lymphoid structures of tumors, revealing great potential of Tfh cells in tumor immunity. However, Tfh development is incompletely understood. The differentiation of Tfh cells is a complex, multistage process regulated at the DNA, RNA and protein levels. This review just summarizes current research on the molecular mechanisms of Tfh cell differentiation to better understand the role of Tfh cells in antitumor immunity.

CCR7-mediated T follicular helper cell differentiation is associated with the pathogenesis and immune microenvironment of spinal cord injury-induced immune deficiency syndrome.

Spinal cord injury-induced immune deficiency syndrome (SCI-IDS) is a disorder characterized by systemic immunosuppression secondary to SCI that dramatically increases the likelihood of infection and is difficult to treat. T follicular helper (Tfh) cells regulated by chemokine receptor CCR7 are associated with SCI-IDS after acute SCI. The present study explored the roles of CCR7 in SCI-IDS occurrence and immune microenvironment composition. Gene expression profile data of peripheral blood leukocytes from SCI and non-SCI subjects were collected from the Gene Expression Omnibus database. According to differential gene expression analysis, a protein-protein interaction (PPI) network, and risk model construction, the CCR7 expression level was prominently related to acute SCI and CCR7 expression was significantly downregulated after acute SCI. Next, we constructed a clinical prediction model and used it to identify patients with acute SCI. Using Gene Ontology (GO) analysis and gene set enrichment analysis (GSEA), we discovered that immune-related biological processes, such as T cell receptor signaling pathway, were suppressed, whereas chemokine-related signaling pathways were activated after acute SCI. Immune infiltration analysis performed using single sample GSEA and CIBERSORT suggested that Tfh cell function was significantly correlated with the CCR7 expression levels and was considerably reduced after acute SCI. Acute SCI was divided into two subtypes, and we integrated multiple classifiers to analyze and elucidate the immunomodulatory relationships in both subtypes jointly. The results suggested that CCR7 suppresses the immunodeficiency phenotype by activating the chemokine signaling pathway in Tfh cells. In conclusion, CCR7 exhibits potential as a diagnostic marker for acute SCI.

Increased Intrathecal Activity of Follicular Helper T Cells in Patients With Relapsing-Remitting Multiple Sclerosis.

Follicular helper T (Tfh) cells play a critical role in protective immunity helping B cells produce antibodies against foreign pathogens and are likely implicated in the pathogenesis of various autoimmune diseases. The purpose of this study was to investigate the role of Tfh cells in the pathogenesis of multiple sclerosis (MS). Using flow cytometry, we investigated phenotype, prevalence, and function of Tfh cells in blood and CSF from controls and patients with relapsing-remitting MS (RRMS) and primary progressive MS (PPMS). In addition, an in vitro blood-brain barrier coculture assay of primary human astrocytes and brain microvascular endothelial cells grown in a Boyden chamber was used to assess the migratory capacity of peripheral Tfh cells. This study identified 2 phenotypically and functionally distinct Tfh cell populations: CD25- Tfh cells (Tfh1-like) and CD25int Tfh cells (Tfh17-like). Whereas minor differences in Tfh cell populations were found in blood between patients with MS and controls, we observed an increased frequency of CD25- Tfh cells in CSF of patients with RRMS and PPMS and CD25int Tfh cells in patients with RRMS, compared with controls. Increasing frequencies of CSF CD25- Tfh cells and the CD25- Tfh/Tfr ratio scaled with increasing IgG index in patients with RRMS. Despite an increased prevalence of intrathecal Tfh cells in patients with MS, no difference in the migratory capacity of circulating Tfh cells was observed between controls and patients with MS. Instead, CSF concentrations of CXCL13 scaled with total counts of Tfh and Tfr cell subsets in the CSF. Our study indicates substantial changes in intrathecal Tfh dynamics, particularly in patients with RRMS, and suggests that the intrathecal inflammatory environment in patients with RRMS promotes recruitment of peripheral Tfh cells rather than the Tfh cells having an increased capacity to migrate to CNS.