Memory Tfh Research Articles

Memory Phenotype Tfh Cells Develop Without Overt Infection and Support Germinal Center Formation and B Cell Responses to Viral Infection.

Pathogen-induced memory Tfh cells are important to maintain high-affinity antibodies against pathogens. We have now discovered Tfh cells with a similar memory phenotype (MP) that develop in pathogen-free conditions. These MP Tfh cells are similar to pathogen-induced memory Tfh in both phenotype and function. They express FR4 and Egr2, which are both found in pathogen-induced memory Tfh cells. FR4+Egr2+ CD4 MP cells express genes involved in the development of Tfh cells and homeostatic proliferation, as well as key metabolic pathways discovered in pathogen-induced memory Tfh cells. MP Tfh cells can support B cell-mediated IgG production in vitro and induce germinal center formation and anti-viral antibodies in response to virus infection. These mouse MP Tfh cells share a similar phenotype to human circulating Tfh cells that are increased in Sjögren's syndrome patients. Although Foxp3-positive circulating T follicular regulatory (Tfr) cells are normal, a proportion of circulating Tfh cells from patients express increased levels of T-bet, which is associated with high levels of inflammatory pathology. Thus, although they do not require overt infection for their development, MP Tfh cells are important for protective immune responses, and dysregulated MP Tfh responses may play a role in autoimmunity.

Influenza vaccination stimulates maturation of the human T follicular helper cell response

The differentiation and specificity of human CD4+ T follicular helper cells (TFH cells) after influenza vaccination have been poorly defined. Here we profiled blood and draining lymph node (LN) samples from human volunteers for over 2 years after two influenza vaccines were administered 1 year apart to define the evolution of the CD4+ TFH cell response. The first vaccination induced an increase in the frequency of circulating TFH (cTFH) and LN TFH cells at week 1 postvaccination. This increase was transient for cTFH cells, whereas the LN TFH cells further expanded during week 2 and remained elevated in frequency for at least 3 months. We observed several distinct subsets of TFH cells in the LN, including pre-TFH cells, memory TFH cells, germinal center (GC) TFH cells and interleukin-10+ TFH cell subsets beginning at baseline and at all time points postvaccination. The shift toward a GC TFH cell phenotype occurred with faster kinetics after the second vaccine compared to the first vaccine. We identified several influenza-specific TFH cell clonal lineages, including multiple responses targeting internal influenza virus proteins, and found that each TFH cell state was attainable within a clonal lineage. Thus, human TFH cells form a durable and dynamic multitissue network.

Osteomyelitis is associated with increased anti-inflammatory response and immune exhaustion.

Osteomyelitis (OMS) is a bone infection causing bone pain and severe complications. A balanced immune response is critical to eradicate infection without harming the host, yet pathogens manipulate immunity to establish a chronic infection. Understanding OMS-driven inflammation is essential for disease management, but comprehensive data on immune profiles and immune cell activation during OMS are lacking. Using high-dimensional flow cytometry, we investigated the detailed innate and adaptive systemic immune cell populations in OMS and age- and sex-matched controls. Our study revealed that OMS is associated with increased levels of immune regulatory cells, namely T regulatory cells, B regulatory cells, and T follicular regulatory cells. In addition, the expression of immune activation markers HLA-DR and CD86 was decreased in OMS, while the expression of immune exhaustion markers TIM-3, PD-1, PD-L1, and VISTA was increased. Members of the T follicular helper (Tfh) cell family as well as classical and typical memory B cells were significantly increased in OMS individuals. We also found a strong correlation between memory B cells and Tfh cells. We conclude that OMS skews the host immune system towards the immunomodulatory arm and that the Tfh memory B cell axis is evident in OMS. Therefore, immune-directed therapies may be a promising alternative for eradication and recurrence of infection in OMS, particularly in individuals and areas where antibiotic resistance is a major concern.

Signatures of CD4+ T and B cells are associated with distinct stages of chronic chagasic cardiomyopathy.

Chagas disease is a neglected parasitic disease caused by Trypanosoma cruzi. While most patients are asymptomatic, around 30% develop Chronic Chagasic Cardiomyopathy (CCC). Here, we employed high-dimensional flow cytometry to analyze CD4+ T and B cell compartments in patients during the chronic phase of Chagas disease, presenting the asymptomatic and mild or moderate/severe cardiac clinical forms. Effector CD27-CD4+ T cells were expanded in both CCC groups, and only mild CCC patients showed higher frequencies of effector memory and T follicular helper (Tfh) cells than healthy donors (CTL) and asymptomatic patients. Unsupervised analysis confirmed these findings and further revealed the expansion of a specific subpopulation composed of Tfh, transitional, and central memory CD4+ T cells bearing a phenotype associated with strong activation, differentiation, and exhaustion in patients with mild but not moderate/severe CCC. In contrast, patients with mild and moderate/severe CCC had lower frequencies of CD4+ T cells expressing lower levels of activation markers, suggesting resting status, than CTL. Regarding the B cell compartment, no alterations were found in naïve CD21-, memory cells expressing IgM or IgD, marginal zone, and plasma cells in patients with Chagas disease. However, expansion of class-switched activated and atypical memory B cells was observed in all clinical forms, and more substantially in mild CCC patients. Taken together, our results showed that T. cruzi infection triggers changes in CD4+ T and B cell compartments that are more pronounced in the mild CCC clinical form, suggesting an orchestrated cellular communication during Chagas disease. Overall, these findings reinforce the heterogeneity and complexity of the immune response in patients with chronic Chagas disease and may provide new insights into disease pathology and potential markers to guide clinical decisions.

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

BackgroundA 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. PurposeConventional 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. MethodsStool 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. ResultAt 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. ConclusionThe 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.

Effector-Phase IL-2 Signals Drive Th1 Effector and Memory Responses Dependently and Independently of TCF-1.

Following viral infection, CD4+ T cell differentiation is tightly regulated by cytokines and TCR signals. Although most activated CD4+ T cells express IL-2Rα after lymphocytic choriomeningtis virus infection, by day 3 postinfection, only half of activated T cells maintain expression. IL-2Rα at this time point distinguishes precursors for terminally differentiated Th1 cells (IL-2Rαhi) from precursors for Tfh cells and memory T cells (IL-2Rαlo) and is linked to strong TCR signals. In this study, we test whether TCR-dependent IL-2 links the TCR to CD4+ T cell differentiation. We employ a mixture of anti-IL-2 Abs to neutralize IL-2 throughout the primary CD4+ T cell response to lymphocytic choriomeningitis virus infection in mice or only after the establishment of lineage-committed effector cells (day 3 postinfection). We report that IL-2 signals drive the formation of Th1 precursor cells in the early stages of the immune response and sustain Th1 responses during its later stages (after day 3). Effector-stage IL-2 also shapes the composition and function of resulting CD4+ memory T cells. Although IL-2 has been shown previously to drive Th1 differentiation by reducing the activity of the transcriptional repressor TCF-1, we found that sustained IL-2 signals were still required to drive optimal Th1 differentiation even in the absence of TCF-1. Therefore, we concluded that IL-2 plays a central role throughout the effector phase in regulating the balance between Th1 and Tfh effector and memory cells via mechanisms that are both dependent and independent of its role in modulating TCF-1 activity.

Dysregulation of circulating T follicular helper cell subsets and their potential role in the pathogenesis of syphilis.

The role of the host immune response could be critical in the development of Treponema pallidum (Tp) infection in individuals with latent syphilis. This study aims to investigate the alterations in T follicular helper T (Tfh) cell balance among patients with secondary syphilis and latent syphilis. 30 healthy controls (HCs), 24 secondary syphilis patients and 41 latent syphilis patients were enrolled. The percentages of total Tfh, ICOS+ Tfh, PD-1+ Tfh, resting Tfh, effector Tfh, naïve Tfh, effector memory Tfh, central memory Tfh,Tfh1, Tfh2, and Tfh17 cells in the peripheral blood were all determined by flow cytometry. The percentage of total Tfh cells was significantly higher in secondary syphilis patients compared to HCs across various subsets, including ICOS+ Tfh, PD-1+ Tfh, resting Tfh, effector Tfh, naïve Tfh, effector memory Tfh, central memory Tfh, Tfh1, Tfh2, and Tfh17 cells. However, only the percentages of ICOS+ Tfh and effector memory Tfh cells showed significant increases in secondary syphilis patients and decreases in latent syphilis patients. Furthermore, the PD-1+ Tfh cells, central memory Tfh cells, and Tfh2 cells showed significant increases in latent syphilis patients, whereas naïve Tfh cells and Tfh1 cells exhibited significant decreases in secondary syphilis patients when compared to the HCs. However, no significant change was found in resting Tfh and effector Tfh in HCs and secondary syphilis patients or latent syphilis patients. Dysregulated ICOS+ Tfh or effector memory Tfh cells may play an important role in immune evasion in latent syphilis patients.

Tet2 deletion in CD4+ T cells disrupts Th1 lineage commitment in memory cells and enhances T follicular helper cell recall responses to viral rechallenge

Following viral clearance, antigen-specific CD4+ T cells contract and form a pool of distinct Th1 and Tfh memory cells that possess unique epigenetic programs, allowing them to rapidly recall their specific effector functions upon rechallenge. DNA methylation programing mediated by the methylcytosine dioxygenase Tet2 contributes to balancing Th1 and Tfh cell differentiation during acute viral infection; however, the role of Tet2 in CD4+ T cell memory formation and recall is unclear. Using adoptive transfer models of antigen-specific wild type and Tet2 knockout CD4+ T cells, we find that Tet2 is required for full commitment of CD4+ T cells to the Th1 lineage and that in the absence of Tet2, memory cells preferentially recall a Tfh like phenotype with enhanced expansion upon secondary challenge. These findings demonstrate an important role for Tet2 in enforcing lineage commitment and programing proliferation potential, and highlight the potential of targeting epigenetic programing to enhance adaptive immune responses.

Longitudinal analysis of memory Tfh cells and antibody response following CoronaVac vaccination.

The inactivated vaccine CoronaVac is one of the most widely used COVID-19 vaccines globally. However, the longitudinal evolution of the immune response induced by CoronaVac remains elusive compared with other vaccine platforms. Here, we recruited 88 healthy individuals who received 3 doses of CoronaVac vaccine. We longitudinally evaluated their polyclonal and antigen-specific CD4+ T cells and neutralizing antibody response after receiving each dose of vaccine for over 300 days. Both the second and third doses of vaccine induced robust spike-specific neutralizing antibodies, with a third vaccine further increasing the overall magnitude of antibody response and neutralization against Omicron sublineages B.1.1.529, BA.2, BA.4/BA.5, and BA.2.75.2. Spike-specific CD4+ T cells and circulating T follicular helper (cTfh) cells were markedly increased by the second and third dose of CoronaVac vaccine, accompanied by altered composition of functional cTfh cell subsets with distinct effector and memory potential. Additionally, cTfh cells were positively correlated with neutralizing antibody titers. Our results suggest that CoronaVac vaccine-induced spike-specific T cells are capable of supporting humoral immunity for long-term immune protection.

Memory T follicular helper cells drive donor-specific antibodies independent of memory B cells and primary germinal center and alloantibody formation

Human leukocyte antigen antibodies are important immunologic mediators of renal allograft loss and are difficult to control. The inability to permanently eliminate donor-specific antibodies (DSA) is partly due to an incomplete understanding of the cellular mechanisms driving alloantibody formation, recurrence, and maintenance. Memory T follicular helper (mTfh) cells rapidly interact with memory B cells upon antigen re-exposure for anamnestic humoral responses, but little is known about Tfh memory in transplantation. We hypothesized that alloreactive mTfh cells form after transplantation and play a critical role in DSA formation following alloantigen re-encounter. To test this hypothesis, we utilized murine skin allograft models to identify and characterize Tfh memory and interrogate its ability to mediate alloantibody responses. We identified alloreactive Tfh memory as a mediator of accelerated humoral alloresponses independent of memory B cells and primary germinal center, or DSA, formation. Furthermore, we demonstrate that mTfh-driven alloantibody formation is susceptible to CD28 costimulation blockade. These findings provide novel insight into a pathologic role for memory Tfh in alloantibody responses and strongly support shifting therapeutic focus from the singular targeting of B cell lineage cells and alloantibodies themselves to multimodal strategies that include inhibition of mTfh cells to treat DSA.

O005 Perturbations in gut microbial metabolites promotes a pro-inflammatory state increasing risk of acute rejection post renal transplantation

Abstract Introduction Emerging evidence suggests that the gastrointestinal microbiota-immune axis impacts on extra-intestinal health. We aim to identify the influence of microbial metabolites on recipient's immunity; testing the hypothesis that reduced availability of bacterial-derived metabolites associated with immunoregulation e.g., short chain fatty acids (SCFAs) and tryptophan-derivatives promote a pro-inflammatory state increasing risk of acute rejection (AR). Methods Ninety recipients and 21 live-donors were recruited with urine, stool and blood samples collected at baseline and up to 12-months after surgery. Flow cytometry was used to assess for circulating subpopulations of CD19+ B-cells and CD4+ T cells (cTFH - CD3+CD4+CD45RA-CXCR5+ and cTFR -CD3+CD4+CXCR5+FoxP3+). Faecal SCFAs and indole derivatives were identified by mass spectroscopy and high-performance liquid chromatography. Results Patients with AR had an almost 10-fold reduction of FoxP3+ cTFR cells after transplantation compared to baseline (p=0.03). There were lower frequencies of cTFR cells at 3-months when compared to matched recipients without AR (0.009%±0.014% vs 0.10%±0.12%; p=0.01). In AR, there was a trend for higher frequencies of plasmablasts, resting memory B-cells and TFH cells at baseline, with fewer transitional B-cells at 3-months. Despite tryptophan availability increasing after transplantation, patients with AR displayed reduced levels of SCFAs at 1-month. Conclusion Complex changes in microbial metabolites exist after transplantation that may influence the balance of cTFH vs cTFR cells. Despite increase in dietary tryptophan, recipients with AR may harbour gut microbes that are unable to metabolise tryptophan into immune-regulatory metabolites, which predisposes a pro-inflammatory immune state.

Targeting Multiple Costimulatory Molecules Prevents Persistence of Lung Tissue-resident Memory T cells and Leads to Airway Tolerance

Abstract Pools of tissue-resident memory T (Trm) cells are thought to maintain and contribute to exacerbations of inflammatory or autoimmune disease. We hypothesized that several costimulatory molecules would control the expansion and maintenance of these populations when responding to antigen, and tested the potential of targeting OX40L, CD30L, and ICOSL, using a house dust mite (HDM) allergen-based mouse model of asthmatic lung inflammation. We found that allergen induced persisting CD4+CD44hiCD62Llo CD69+ and CD69− lung-localized Trm cells and RNA-seq revealed the heterogeneity of these memory pools, containing Th2, Tfh, Th17, and Th1 clusters. Showing their reliance on costimulation for recall activity to allergen, blocking CD30L and OX40L together, or blocking ICOSL alone, resulted in ~50% reduction in the expansion of both CD69+ and CD69− tissue-resident effector T cells during a secondary allergen exposure or a tertiary allergen exposure. Blocking all three molecules at once further inhibited T cell accumulation by ~90%, corresponding to a similar reduction in lung tissue inflammation, including eosinophilia. Moreover, triple costimulation blockade resulted in a diminished persisting lung tissue-resident memory T cell pool, which failed to expand to normal levels and drive further exacerbations of lung inflammation upon subsequent exposure to allergen, resulting in a state of airway tolerance. Overall, our data suggest that the concurrent inhibition of OX40, CD30, and ICOS signaling, can impair the expansion and persistence of lung-localized Trm cells and could engender long-lasting tolerance in asthma and similar autoimmune or inflammatory diseases that are maintained by tissue-resident memory T cells.

Memory phenotype Tfh cells are homeostatically maintained and are important for the development of germinal centers and B cell responses to virus infection

Abstract Memory phenotype (MP) CD4 T cells that develop in the absence of overt antigen stimulation are important for both innate and adaptive immune responses. Although pathogen specific MP CD4 T cells have been found to function effectively against infection, it is not known if MP Tfh cells can also be developed in the absence of overt antigen stimulation. Here, we demonstrate that MP Tfh cells develop in the absence of overt antigen stimulation. In addition to FR4+, a mark found in pathogen induced memory Tfh cells, MP Tfh expressed high levels of Egr2. The development of MP Tfh are defective in CD2-Egr2/3−/− mice. MP Tfh cells share similar features in phenotypes and epigenetics with antigen induced memory Tfh cells and can effectively induce germinal center formation and B cells responses. Thus, MP Tfh cells regulated by Egr2/3 pathway are important component of adaptive immunity. Medical Research Council UK (MR/N00096X/1), Barts Charity (MGU0463)

Abstract P5-02-10: In-silico approaches that detect immune contexture to trastuzumab response in neo-adjuvant studies

Abstract Introduction: Computational approaches have aided in estimating cellular composition of the tumour microenvironment. The evaluation of immune composition in tumours before treatment may predict pathologic complete response (pCR). The aim of the study was to perform a meta-analysis of HER2-positive breast cancer subjects who received neoadjuvant trastuzumab to detect associations between immune cells measured by CIBERSORT and ESTIMATE and pCR. Methods: PubMed was used to identify transcriptomic data of HER2-positive breast cancer patients who received neoadjuvant trastuzumab. Baseline data from eight neoadjuvant studies (N=338) was downloaded from GEO. Data from each study was background corrected and quantile normalised using ‘limma’ or ‘oligo’ packages in R. Immune profiles per sample was generated using computational softwares CIBERSORT and ESTIMATE, and were then linked to pCR status. Correlations between immune contexture and pCR for each study were interpreted using statistical testing. Meta-analysis by a logistic regression model was conducted on studies which passed assumptions to identify CIBERSORT immune subsets robust to pCR. Results: CIBERSORT results showed that three studies had reduced T follicular helper cells (Tfh) (Brodsky p=0.38, CHER-LOB p=0.17, TransNOAH p=0.25) and two studies had reduced plasma cells (CHER-LOB p=0.15, Brodsky p=0.38) in the pCR group, but was not significant after multiple correction. ESTIMATE analysis showed that data from two studies had elevated immune infiltration in pCR (Brodsky p=0.19, CHER-LOB p=0.10) but was not significant. A meta-analysis of pooled data from four studies (TRIO-US B07, 03-311, TransNOAH, CHER-LOB) showed that low Tfh (p=0.053, OR=0.04, CI [0.0012-0.99]) and high memory B-cells (p=0.008, OR=2126.9, CI [8.12-7.65 × 10+5]) prior to trastuzumab treatment may be associated with a better chance of achieving pCR. Conclusion: Results from our meta-analysis proposed that memory B- and T follicular helper subsets may predict a role in achieving pCR. Incorporating studies with larger sample cohorts such as the CALGB-40601 (N=265) study can achieve statistical power of this analysis. Citation Format: Dalal AlSultan, Alex J. Eustace, Stephen F. Madden, John Crown. In-silico approaches that detect immune contexture to trastuzumab response in neo-adjuvant studies [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-10.

T follicular helper 17 (Tfh17) cells are superior for immunological memory maintenance.

A defining feature of successful vaccination is the ability to induce long-lived antigen-specific memory cells. T follicular helper (Tfh) cells specialize in providing help to B cells in mounting protective humoral immunity in infection and after vaccination. Memory Tfh cells that retain the CXCR5 expression can confer protection through enhancing humoral response upon antigen re-exposure but how they are maintained is poorly understood. CXCR5+ memory Tfh cells in human blood are divided into Tfh1, Tfh2, and Tfh17 cells by the expression of chemokine receptors CXCR3 and CCR6 associated with Th1 and Th17, respectively. Here, we developed a new method to induce Tfh1, Tfh2, and Tfh17-like (iTfh1, iTfh2, and iTfh17) mouse cells in vitro. Although all three iTfh subsets efficiently support antibody responses in recipient mice with immediate immunization, iTfh17 cells are superior to iTfh1 and iTfh2 cells in supporting antibody response to a later immunization after extended resting in vivo to mimic memory maintenance. Notably, the counterpart human Tfh17 cells are selectively enriched in CCR7+ central memory Tfh cells with survival and proliferative advantages. Furthermore, the analysis of multiple human cohorts that received different vaccines for HBV, influenza virus, tetanus toxin or measles revealed that vaccine-specific Tfh17 cells outcompete Tfh1 or Tfh2 cells for the persistence in memory phase. Therefore, the complementary mouse and human results showing the advantage of Tfh17 cells in maintenance and memory function supports the notion that Tfh17-induced immunization might be preferable in vaccine development to confer long-term protection.

Immunophenotyping identifies distinct cellular signatures for systemic lupus erythematosus and lupus nephritis

AbstractBackgroundSystemic lupus erythematosus (SLE) is a complex systemic autoimmune disease characterized by development of autoantibodies and multiorgan involvement. Kidney involvement, termed lupus nephritis, has major impact on life expectancy. It is increasingly recognized that SLE is likely a common clinical manifestation of pathophysiologically diverse processes, and lupus nephritis has similarly been associated with several distinct immunological processes. We compared the immune cell phenotypes of individuals with SLE in the presence or absence of nephritis.MethodsCryopreserved peripheral blood mononuclear cells from SLE patients with and without kidney involvement underwent flow cytometric analysis to identify major populations in T cells, B cells and myeloid lineages.ResultsWe compared the frequencies of lymphocyte populations in 69 SLE patients without nephritis, 20 SLE patients with nephritis, and 92 healthy blood donors. Patients with SLE and lupus nephritis (LN) had reduced marginal zone B cells (P < 0.0001 in SLE; P = 0.001 in LN), memory B cells (P = 0.002 in SLE; P = 0.001 in LN) and circulating T follicular helper (Tfh) memory cells (P < 0.0001 in SLE and LN) compared to healthy donors. Patients with lupus nephritis had increase Th2 (P < 0.0001) and T regulatory cells (P < 0.0001) compared to both SLE patients without nephritis and healthy donors.ConclusionSLE patients with and without lupus nephritis have distinct immunologic differences that may reflect the unique pathophysiological processes contributing to disease manifestations.

Integrated Single Cell Analysis Reveals Co-Evolution of Malignant B Cells and the Tumor Microenvironment in Transformed Follicular Lymphoma

Introduction: The transformation of follicular lymphoma (FL) is believed to follow a divergent evolutionary model. However, the relationship between clonal (genetic) evolution and phenotype has been largely unexplored. Similarly, it is unknown if transformation arises from the expansion of a pre-existing clone with a transformed genotype, or if instead it requires the acquisition of genetic and phenotypic traits absent at diagnosis. In addition, previous bulk sequencing studies have provided only limited information about tumor microenvironment (TME) components. To address these shortcomings, we used single cell whole transcriptome (scWTS) and whole genome sequencing (scWGS) to characterize the clonal and phenotypic evolution of malignant B cells during transformation and elucidate interactions within TME. Methods: Our study included 11 transformed FL (tFL) patients with paired FL and DLBCL time point biopsies, and 11 indolent FL controls (>6y follow-up without progression/transformation). Combined scWTS and BCR sequencing was performed for all samples, along with scWGS for transformation pairs. We included two independent validation cohorts of pre-treatment FLs (N=125 treated with Rituximab-Bendamustine and N=154 with Rituximab-CVP (N=154)). Results: Phylogenetic analysis using scWGS showed a non-uniform pattern of evolution across the tFL pairs. In 3 pairs, all genetically-defined clones were composed of cells from both FL and DLBCL time points (called mixed-clones). Conversely, in 5 pairs fully divergent evolution was observed, featuring unique genetic clones at the DLBCL timepoint. Finally, 3 pairs had both mixed and unique DLBCL clones. Clustering of malignant B cells from tFL pairs using scWTS data indicated that the transcriptional similarity between the FL and DLBCL samples was inversely correlated with the time between sampling. Importantly, in the 6 pairs with well-separated FL and DLBCL clusters, some FL cells could always be found within the DLBCL clusters (so-called "DLBCL-like cells") and vice-versa. Integrative analysis of scWGS and scWTS data highlighted that samples with the fewest genomic changes showed the least transcriptional change. However, this correlation did not hold true for all tFL pairs. In particular, 2 pairs showed minimal genomic change but a high degree of phenotypic change, suggesting other determinants of cellular phenotype. Furthermore, in the 5 pairs with an extreme genomic clonal divergence, the strict co-evolution of malignant B-cell genotypes and phenotypes could not account for the presence of cells with a "DLBCL-like" phenotype in FL time point biopsies (Figure A). Differential expression and GSEA of malignant cells identified "MYC targets V1'', "mTORC1", and "OXPHOS" as pathways enriched in malignant B cells at the transformed time point compared to the earlier FL. Within these pathways, control non-tFL cells had significantly lower gene expression scores than pre-transformed FL, independent of cell-cycle state. At the TME level, a significant composition shift was observed from T cells with a TFH and central memory phenotype in FL samples, to cells with an exhausted phenotype at the time of transformation. The largest shift was an increase in the CD8+/LAG3+/PD1+ population (more than doubled, Figure B), confirmed by multicolour-IHC analysis. The magnitude of the TME shift was correlated with the magnitude of the malignant B-cell phenotypic evolution. A cell-cell interaction analysis highlighted MIF/CD44 and CD27/CD70 pathways as enriched at the time of transformation, while IL15/IL15RA signaling was more prominent in FLs. Finally, in two independent cohorts of pre-treatment FL, the proportion of CD8+/LAG3+ cells within the CD20-negative TME compartment was associated with time to transformation, time to progression and disease specific survival, independently of FLIPI score and FL histologic grade. Conclusion: By applying high-dimensional scWTS and scWGS techniques, we describe the range of possible relationships between cellular genotype and phenotype during FL transformation. We observed different modes of clonal evolution, from the expansion of a precursor cell population present at the time of diagnosis, to the emergence of novel clones present only at transformation. Shifts in the TME composition allowed us to identify a CD8+/LAG3+ population that could be used as a predictive marker of transformation risk. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

AMPK activator AICAR in combination with anti-mouse IL10 mAb restores the functionality of intra-tumoral Tfh cells in the 4T1 mouse model

4T1 cell-mediated TNBC breast cell carcinoma is a highly malignant mice tumor model which resembles an advanced stage of breast cancer in humans. Tumor progression occurs depending on the intra-tumoral balance of pro- and anti- tumorigenic immune cells. Enhancement of T-cell-mediated anti-tumor immunity will be advantageous for inhibiting tumor progression and improving the efficacy of cancer therapy. This study is focused on alleviating suppressed anti-tumor immune response by improving CD4+ T follicular helper cell (Tfh) response in 4T1 mice. We employed anti-IL10 mAb along with metabolic drugs 2-deoxy-D-glucose (2DG) which inhibits the glycolytic pathway and Cpt1a inhibitor Etomoxir which inhibits FAO. AMPK activator AICAR with or without anti-IL10 mAb was also used to ameliorate metabolic stress and exhaustion faced by immune cells. Our results demonstrate that synergistic treatment with 2DG/Etomoxir + anti-IL10 mAb induced Tfh cell, memory B, and GC B cell response more potently compared to treatment with 2DG or Etomoxir treatment alone as observed in several LNs and tumor tissue of 4T1 mouse. However, AICAR + anti-IL10 mAb increased the frequency of intratumoral Tfh cells, simultaneously downregulated Tfr cells; and improved humoral response by stimulating upregulation of memory B, GC B, and plasmablasts in tumor-draining, axillary, and mesenteric LNs of 4T1 mouse.

MiR-29a-3p negatively regulates circulating Tfh memory cells in patients with Graves' disease by targeting ICOS.

MicroRNAs (miRNAs) are small endogenous noncoding RNAs that regulate genome expression posttranscriptionally and are involved in autoimmune diseases. Previous studies have indicated that follicular helper T (Tfh) cells play a critical role in the pathogenesis of Graves' disease (GD). However, the molecular mechanisms that contribute to circulating Tfh memory cell response in GD patients remain incompletely understood. This study aimed to investigate the role of miRNAs on circulating Tfh memory cells in GD patients. Herein, our data showed that the proportion of circulating Tfh memory cells, the transcript levels of IL-21, and the plasma concentrations of IL-21 were increased in the peripheral blood from GD patients. We also found that inducible co-stimulator (ICOS) expression, an important molecule expressed on Tfh cells, were significantly augmented in the peripheral blood mononuclear cells (PBMCs) from GD patients and positively correlated with the percentage of circulating Tfh memory cells and the transcript levels of IL-21 in GD. Intriguingly, miRNA sequencing screened miR-29a-3p expression was downregulated and inversely correlated with ICOS expression and the frequency of circulating Tfh memory cells in patients with GD. Luciferase assay demonstrated that ICOS was the direct target gene of miR-29a-3p, and miR-29a-3p could inhibit ICOS at both transcriptional and translational levels. Overexpression of miR-29a-3p reduced the proportion of circulating Tfh memory cells. Moreover, miR-29a-3p expression negatively correlated with serum concentrations of TSH receptor antibody (TRAb) in GD patients. Collectively, our results demonstrate that miR-29a-3p emerges as a post-transcriptional brake to limit circulating Tfh memory cell response in GD patients and may be involved in the pathogenesis of GD.

Evolution of antigen-specific follicular helper T cell transcription from effector function to memory.

Understanding how follicular helper T cells (TFH) regulate the specialization, maturation, and differentiation of adaptive B cell immunity is crucial for developing durable high-affinity immune protection. Using indexed single-cell molecular strategies, we reveal a skewed intraclonal assortment of higher-affinity T cell receptors and the distinct molecular programming of the localized TFH compartment compared with emigrant conventional effector TH cells. We find a temporal shift in B cell receptor class switch, which permits identification of inflammatory and anti-inflammatory modules of transcriptional programming that subspecialize TFH function before and during the germinal center (GC) reaction. Late collapse of this local primary GC reaction reveals a persistent post-GC TFH population that discloses a putative memory TFH program. These studies define subspecialized antigen-specific TFH transcriptional programs that progressively change with antibody class-specific evolution of high-affinity B cell immunity and a memory TFH transcriptional program that emerges upon local GC resolution.