scholarly journals Tfh Cells in Health and Immunity: Potential Targets for Systems Biology Approaches to Vaccination

2020 ◽  
Vol 21 (22) ◽  
pp. 8524
Author(s):  
Hannah Law ◽  
Vanessa Venturi ◽  
Anthony Kelleher ◽  
C. Mee Ling Munier
Keyword(s):  
T Cells ◽  
B Cells ◽  
Somatic Hypermutation ◽  
Adaptive Immune Response ◽  
Affinity Maturation ◽  
T Cell Response ◽  
Tfh Cells ◽  
Follicular Helper ◽  
Health And Disease ◽  
Analytical Tools

T follicular helper (Tfh) cells are a specialised subset of CD4+ T cells that play a significant role in the adaptive immune response, providing critical help to B cells within the germinal centres (GC) of secondary lymphoid organs. The B cell receptors of GC B cells undergo multiple rounds of somatic hypermutation and affinity maturation within the GC response, a process dependent on cognate interactions with Tfh cells. B cells that receive sufficient help from Tfh cells form antibody-producing long-lived plasma and memory B cells that provide the basis of decades of effective and efficient protection and are considered the gold standard in correlates of protection post-vaccination. However, the T cell response to vaccination has been understudied, and over the last 10 years, exponential improvements in the technological underpinnings of sampling techniques, experimental and analytical tools have allowed multidisciplinary characterisation of the role of T cells and the immune system as a whole. Of particular interest to the field of vaccinology are GCs and Tfh cells, representing a unique target for improving immunisation strategies. Here, we discuss recent insights into the unique journey of Tfh cells from thymus to lymph node during differentiation and their role in the production of high-quality antibody responses as well as their journey back to the periphery as a population of memory cells. Further, we explore their function in health and disease and the power of next-generation sequencing techniques to uncover their potential as modulators of vaccine-induced immunity.

scholarly journals IL-21 acts directly on B cells to regulate Bcl-6 expression and germinal center responses

2010 ◽  
Vol 207 (2) ◽  
pp. 353-363 ◽  
Author(s):  
Michelle A. Linterman ◽  
Laura Beaton ◽  
Di Yu ◽  
Roybel R. Ramiscal ◽  
Monika Srivastava ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Cell Formation ◽  
Affinity Maturation ◽  
Tfh Cells ◽  
Follicular Helper ◽  
Early Memory ◽  
Bone Marrow Chimeras ◽  
Follicular Response

During T cell–dependent responses, B cells can either differentiate extrafollicularly into short-lived plasma cells or enter follicles to form germinal centers (GCs). Interactions with T follicular helper (Tfh) cells are required for GC formation and for selection of somatically mutated GC B cells. Interleukin (IL)-21 has been reported to play a role in Tfh cell formation and in B cell growth, survival, and isotype switching. To date, it is unclear whether the effect of IL-21 on GC formation is predominantly a consequence of this cytokine acting directly on the Tfh cells or if IL-21 directly influences GC B cells. We show that IL-21 acts in a B cell–intrinsic fashion to control GC B cell formation. Mixed bone marrow chimeras identified a significant B cell–autonomous effect of IL-21 receptor (R) signaling throughout all stages of the GC response. IL-21 deficiency profoundly impaired affinity maturation and reduced the proportion of IgG1+ GC B cells but did not affect formation of early memory B cells. IL-21R was required on GC B cells for maximal expression of Bcl-6. In contrast to the requirement for IL-21 in the follicular response to sheep red blood cells, a purely extrafollicular antibody response to Salmonella dominated by IgG2a was intact in the absence of IL-21.

scholarly journals Cyclin D3 drives inertial cell cycling in dark zone germinal center B cells

2020 ◽  
Vol 218 (4) ◽  
Author(s):  
Juhee Pae ◽  
Jonatan Ersching ◽  
Tiago B.R. Castro ◽  
Marta Schips ◽  
Luka Mesin ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
Germinal Center ◽  
Somatic Hypermutation ◽  
Clonal Expansion ◽  
Affinity Maturation ◽  
Cyclin D3 ◽  
Dark Zone ◽  
Follicular Helper ◽  
Cell Cycle Regulator Cyclin

During affinity maturation, germinal center (GC) B cells alternate between proliferation and somatic hypermutation in the dark zone (DZ) and affinity-dependent selection in the light zone (LZ). This anatomical segregation imposes that the vigorous proliferation that allows clonal expansion of positively selected GC B cells takes place ostensibly in the absence of the signals that triggered selection in the LZ, as if by “inertia.” We find that such inertial cycles specifically require the cell cycle regulator cyclin D3. Cyclin D3 dose-dependently controls the extent to which B cells proliferate in the DZ and is essential for effective clonal expansion of GC B cells in response to strong T follicular helper (Tfh) cell help. Introduction into the Ccnd3 gene of a Burkitt lymphoma–associated gain-of-function mutation (T283A) leads to larger GCs with increased DZ proliferation and, in older mice, clonal B cell lymphoproliferation, suggesting that the DZ inertial cell cycle program can be coopted by B cells undergoing malignant transformation.

scholarly journals CXCR5+PD-1+ follicular helper CD8 T cells control B cell tolerance

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuhong Chen ◽  
Mei Yu ◽  
Yongwei Zheng ◽  
Guoping Fu ◽  
Gang Xin ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cd8 T Cells ◽  
T Cell Subsets ◽  
Cell Tolerance ◽  
B Cell Tolerance ◽  
Autoantibody Production ◽  
Tfh Cells ◽  
Follicular Helper

Abstract Many autoimmune diseases are characterized by the production of autoantibodies. The current view is that CD4+ T follicular helper (Tfh) cells are the main subset regulating autoreactive B cells. Here we report a CXCR5+PD1+ Tfh subset of CD8+ T cells whose development and function are negatively modulated by Stat5. These CD8+ Tfh cells regulate the germinal center B cell response and control autoantibody production, as deficiency of Stat5 in CD8 T cells leads to an increase of CD8+ Tfh cells, resulting in the breakdown of B cell tolerance and concomitant autoantibody production. CD8+ Tfh cells share similar gene signatures with CD4+ Tfh, and require CD40L/CD40 and TCR/MHCI interactions to deliver help to B cells. Our study thus highlights the diversity of follicular T cell subsets that contribute to the breakdown of B-cell tolerance.

scholarly journals Mucosal T follicular helper cells in SIV-infected rhesus macaques: contributing role of IL-27

2019 ◽  
Vol 12 (4) ◽  
pp. 1038-1054 ◽  
Author(s):  
Félicien Moukambi ◽  
Henintsoa Rabezanahary ◽  
Yasmina Fortier ◽  
Vasco Rodrigues ◽  
Julien Clain ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Cd4 T Cells ◽  
Rhesus Macaques ◽  
T Follicular Helper Cells ◽  
Mesenteric Lymph Nodes ◽  
Tfh Cells ◽  
Helper Cells ◽  
Follicular Helper ◽  
Memory Cd4 T Cells

AbstractMesenteric lymph nodes (MLNs), that drain the large and small intestine, are critical sites for the induction of oral tolerance. Although depletion of CD4 T cells in the intestinal lamina propria is a hallmark of HIV infection, CD4 T cell dynamics in MLNs is less known due to the lack of accessibility to these LNs. We demonstrate the early loss of memory CD4 T cells, including T follicular helper cells (Tfh) and a remodeling of MLN architecture in SIV-infected rhesus macaques (RMs). Along with the loss of Tfh cells, we observe the loss of memory B cells and of germinal center B cells. Tfh cells display a Th1 profile with increased levels of the transcription factors that negatively impact on Tfh differentiation and of Stat5 phosphorylation. MLNs of SIV-infected RMs display lower mRNA transcripts encoding for IL-12, IL-23, and IL-35, whereas those coding for IL-27 are not impaired in MLNs. In vitro, IL-27 negatively impacts on Tfh cells and recapitulates the profile observed in SIV-infected RMs. Therefore, early defects of memory CD4 T cells, as well of Tfh cells in MLNs, which play a central role in regulating the mucosal immune response, may have major implications for Aids.

scholarly journals BCL6 orchestrates Tfh cell differentiation via multiple distinct mechanisms

2015 ◽  
Vol 212 (4) ◽  
pp. 539-553 ◽  
Author(s):  
Katerina Hatzi ◽  
J. Philip Nance ◽  
Mark A. Kroenke ◽  
Marcella Bothwell ◽  
Elias K. Haddad ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Tcr Signaling ◽  
Cell Fates ◽  
Binding Motifs ◽  
Tfh Cells ◽  
Follicular Helper ◽  
Distinct Cell ◽  
T Cell Help ◽  
External Stimuli

Follicular helper T cells (Tfh cells) are required for T cell help to B cells, and BCL6 is the defining transcription factor of Tfh cells. However, the functions of BCL6 in Tfh cells have largely remained unclear. Here we defined the BCL6 cistrome in primary human germinal center Tfh cells to assess mechanisms of BCL6 regulation of CD4 T cells, comparing and contrasting BCL6 function in T and B cells. BCL6 primarily acts as a repressor in Tfh cells, and BCL6 binding was associated with control of Tfh cell migration and repression of alternative cell fates. Interestingly, although some BCL6-bound genes possessed BCL6 DNA–binding motifs, many BCL6-bound loci were instead characterized by the presence of DNA motifs for AP1 or STAT. AP1 complexes are key positive downstream mediators of TCR signaling and external stimuli. We show that BCL6 can directly bind AP1, and BCL6 depends on AP1 for recruitment to BCL6-binding sites with AP1 motifs, suggesting that BCL6 subverts AP1 activity. These findings reveal that BCL6 has broad and multifaceted effects on Tfh biology and provide insight into how this master regulator mediates distinct cell context–dependent phenotypes.

scholarly journals B cell priming for extrafollicular antibody responses requires Bcl-6 expression by T cells

2011 ◽  
Vol 208 (7) ◽  
pp. 1377-1388 ◽  
Author(s):  
Sau K. Lee ◽  
Robert J. Rigby ◽  
Dimitra Zotos ◽  
Louis M. Tsai ◽  
Shimpei Kawamoto ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Antibody Responses ◽  
B Cell Differentiation ◽  
Tfh Cells ◽  
Follicular Helper ◽  
Microbial Infections

T follicular helper cells (Tfh cells) localize to follicles where they provide growth and selection signals to mutated germinal center (GC) B cells, thus promoting their differentiation into high affinity long-lived plasma cells and memory B cells. T-dependent B cell differentiation also occurs extrafollicularly, giving rise to unmutated plasma cells that are important for early protection against microbial infections. Bcl-6 expression in T cells has been shown to be essential for the formation of Tfh cells and GC B cells, but little is known about its requirement in physiological extrafollicular antibody responses. We use several mouse models in which extrafollicular plasma cells can be unequivocally distinguished from those of GC origin, combined with antigen-specific T and B cells, to show that the absence of T cell–expressed Bcl-6 significantly reduces T-dependent extrafollicular antibody responses. Bcl-6+ T cells appear at the T–B border soon after T cell priming and before GC formation, and these cells express low amounts of PD-1. Their appearance precedes that of Bcl-6+ PD-1hi T cells, which are found within the GC. IL-21 acts early to promote both follicular and extrafollicular antibody responses. In conclusion, Bcl-6+ T cells are necessary at B cell priming to form extrafollicular antibody responses, and these pre-GC Tfh cells can be distinguished phenotypically from GC Tfh cells.

scholarly journals IL-21 regulates germinal center B cell differentiation and proliferation through a B cell–intrinsic mechanism

2010 ◽  
Vol 207 (2) ◽  
pp. 365-378 ◽  
Author(s):  
Dimitra Zotos ◽  
Jonathan M. Coquet ◽  
Yang Zhang ◽  
Amanda Light ◽  
Kathy D'Costa ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Affinity Maturation ◽  
Memory B Cells ◽  
Target Cells ◽  
B Cell Differentiation ◽  
Follicular Helper

Germinal centers (GCs) are sites of B cell proliferation, somatic hypermutation, and selection of variants with improved affinity for antigen. Long-lived memory B cells and plasma cells are also generated in GCs, although how B cell differentiation in GCs is regulated is unclear. IL-21, secreted by T follicular helper cells, is important for adaptive immune responses, although there are conflicting reports on its target cells and mode of action in vivo. We show that the absence of IL-21 signaling profoundly affects the B cell response to protein antigen, reducing splenic and bone marrow plasma cell formation and GC persistence and function, influencing their proliferation, transition into memory B cells, and affinity maturation. Using bone marrow chimeras, we show that these activities are primarily a result of CD3-expressing cells producing IL-21 that acts directly on B cells. Molecularly, IL-21 maintains expression of Bcl-6 in GC B cells. The absence of IL-21 or IL-21 receptor does not abrogate the appearance of T cells in GCs or the appearance of CD4 T cells with a follicular helper phenotype. IL-21 thus controls fate choices of GC B cells directly.

Expression of Foxp3 by T follicular helper cells in end-stage germinal centers

Science ◽  
2021 ◽  
Vol 373 (6552) ◽  
pp. eabe5146
Author(s):  
Johanne T. Jacobsen ◽  
Wei Hu ◽  
Tiago B. R. Castro ◽  
Sigrid Solem ◽  
Alice Galante ◽  
...  
Keyword(s):  
T Cells ◽  
Transcription Factor ◽  
Antibody Response ◽  
Somatic Hypermutation ◽  
Ectopic Expression ◽  
Germinal Centers ◽  
Affinity Maturation ◽  
Follicular Helper ◽  
End Stage ◽  
Single Reaction

Germinal centers (GCs) are the site of immunoglobulin somatic hypermutation and affinity maturation, processes essential to an effective antibody response. The formation of GCs has been studied in detail, but less is known about what leads to their regression and eventual termination, factors that ultimately limit the extent to which antibodies mature within a single reaction. We show that contraction of immunization-induced GCs is immediately preceded by an acute surge in GC-resident Foxp3+ T cells, attributed at least partly to up-regulation of the transcription factor Foxp3 by T follicular helper (TFH) cells. Ectopic expression of Foxp3 in TFH cells is sufficient to decrease GC size, implicating the natural up-regulation of Foxp3 by TFH cells as a potential regulator of GC lifetimes.

scholarly journals The Tumor Microenvironment in Follicular Lymphoma: Its Pro-Malignancy Role with Therapeutic Potential

2021 ◽  
Vol 22 (10) ◽  
pp. 5352
Author(s):  
Takashi Watanabe
Keyword(s):  
T Cells ◽  
B Cells ◽  
Follicular Lymphoma ◽  
Therapeutic Potential ◽  
Cytotoxic T Cells ◽  
Interleukin 4 ◽  
Cell Frequency ◽  
Tfh Cells ◽  
Follicular Helper ◽  
Reticular Cells

In the follicular lymphoma (FL) microenvironment, CXCR5+ICOS+PD1+BCL6+ follicular helper T (Tfh) cells, which closely correlate with FL B cells in neoplastic follicles, play a major role in supporting FL. Interleukin-4 secreted by Tfh cells triggers the upregulation of the lymphocyte chemoattractant CXCL12 in stromal cell precursors, in particular by fibroblastic reticular cells (FRCs). In turn, mesenchymal fistromal cells (MSCs) can be committed to FRC differentiation in the bone marrow and lymph nodes involved by FL. Noteworthy, MSCs can promote the differentiation of Tfh cells into highly immunosuppressive T-follicular regulatory cells. The tumor suppressor HVEM is highly mutated in FL cells, and its deficiency increases Tfh cell frequency. In contrast, PI3Kδ inhibition impedes the recruitment of Tfh/regulatory T cells and impairs the proliferation of follicular dendritic cells (FDCs) and FDC-induced angiogenesis. Since TIGIT ligands are expressed by FDCs, the immune checkpoint receptor TIGIT plays an important role in tumor-infiltrating T cells. Thus, TIGIT blockade might invigorate cytotoxic T cells in the FL microenvironment. Given their potential to simultaneously reduce the neoplastic B cells, Tfh, and TFR cells could also reinforce the effects of the cytotoxic T cells. This combinatory strategy should be explored as a treatment option to tackle FL.

scholarly journals Atypical B cells upregulate co-stimulatory molecules during malaria and secrete antibodies with T follicular helper cell support

2021 ◽  
Author(s):  
Christine S. Hopp ◽  
Jeff Skinner ◽  
Sarah L. Anzick ◽  
Christopher M. Tipton ◽  
Mary E. Peterson ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
Somatic Hypermutation ◽  
Acute Infection ◽  
Cell Receptor ◽  
Tfh Cells ◽  
Influenza Hemagglutinin ◽  
Follicular Helper ◽  
T Cell Help

ABSTRACTSeveral infectious and autoimmune diseases are associated with an expansion of CD21-CD27- atypical B cells (atBCs). The function of atBCs remains unclear and few studies have investigated the biology of pathogen-specific atBCs during acute infection. Here, we performed longitudinal RNA-sequencing and flow cytometry analyses of Plasmodium falciparum (Pf)-specific B cells before and shortly after febrile malaria, with simultaneous analysis of influenza hemagglutinin (HA)-specific B cells as a comparator. B cell receptor-sequencing showed that Pf-specific atBCs, activated B cells (actBCs) and classical memory B cells share clonality and have comparable somatic hypermutation. In response to malaria, Pf-specific atBCs and actBCs expanded and upregulated molecules that mediate B-T cell interactions, suggesting that atBCs respond to T follicular helper (Tfh) cells. Indeed, in the presence of Tfh cells and Staphylococcal enterotoxin B, atBCs of malaria-exposed individuals differentiated into CD38+ antibody-secreting cells in vitro, suggesting that atBCs may actively contribute to humoral immunity to infectious pathogens.One Sentence SummaryThis study shows that atypical B cells actively respond to acute malaria and have the capacity to produce antibodies with T cell help.

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