T Follicular Helper Research Articles

Enhanced Staphylococcus aureus protection by uncoupling of the α-toxin-ADAM10 interaction during murine neonatal vaccination

Staphylococcus aureus remains a leading global cause of bacterial infection-associated mortality and has eluded prior vaccine development efforts. S. aureus α-toxin (Hla) is an essential virulence factor in disease, impairing the T cell response to infection. The anti-Hla antibody response is a correlate of human protective immunity. Here we observe that this response is limited early in human life and design a vaccine strategy to elicit immune protection against Hla in a neonatal mice. By targeted disruption of the interaction of Hla with its receptor ADAM10, we identify a vaccine antigen (HlaH35L/R66C/E70C, HlaHRE) that elicits an ~100-fold increase in the neutralizing anti-Hla response. Immunization with HlaHRE enhances the T follicular helper (TFH) cell response to S. aureus infection, correlating with the magnitude of the neutralizing anti-toxin response and disease protection. Furthermore, maternal HlaHRE immunization confers protection to offspring. Together, these findings illuminate a path for S. aureus vaccine development at the maternal-infant interface.

T follicular regulatory cells in food allergy promote IgE via IL-4.

T follicular regulatory (TFR) cells are found in the germinal center (GC) response and, along with T follicular helper (TFH) cells, help to control the development of high-affinity antibodies (Ab). Although TFR cells are generally thought to repress GC B cells and the Ab response, we have previously shown that in a mouse food allergy model, TFR cells produce IL-10 and play an essential helper role such that in the absence of TFR cells, IgE responses are diminished. Here we show that in this food allergy response, TFR cells produced IL-4 that promotes the generation of antigen-specific IgE. We show that food allergy-primed TFR cells specifically upregulate IL-4 gene transcription and produce functional IL-4 that promoted IgE responses both in vitro and in vivo. We determined that IgE responses are dependent on a high level of IL-4 produced by follicular T cells in the GC, explaining the need for IL-4 produced by TFR cells in the food allergy response. Overall, our findings have demonstrated that in food allergy, TFR cells can produce IL-4 and regulate IgE in a manner that augments the role of TFH cells in IgE responses.

Benign breast tumors may arise on different immunological backgrounds.

Benign breast tumors are a nonthreatening condition defined as abnormal cell growth within the breast without the ability to invade nearby tissue. However, benign lesions hold valuable biological information that can lead us toward better understanding of tumor biology. In this study, we have used two pathway analysis algorithms, Pathifier and gene set variation analysis (GSVA), to identify biological differences between normal breast tissue, benign tumors and malignant tumors in our clinical dataset. Our results revealed that one-third of all pathways that were significantly different between benign and malignant tumors were immune-related pathways, and 227 of them were validated by both methods and in the METABRIC dataset. Furthermore, five of these pathways (all including genes involved in cytokine and interferon signaling) were related to overall survival in cancer patients in both datasets. The cellular moieties that contribute to immune differences in malignant and benign tumors were analyzed using the deconvolution tool, CIBERSORT. The results showed that levels of some immune cells were specifically higher in benign than in malignant tumors, and this was especially the case for resting dendritic cells and follicular T-helper cells. Understanding the distinct immune profiles of benign and malignant breast tumors may aid in developing noninvasive diagnostic methods to differentiate between them in the future.

Transcriptional re-programming of liver-resident iNKT cells into T-regulatory type-1-like liver iNKT cells involves extensive gene de-methylation.

Unlike conventional CD4+ T cells, which are phenotypically and functionally plastic, invariant NKT (iNKT) cells generally exist in a terminally differentiated state. Naïve CD4+ T cells can acquire alternative epigenetic states in response to different cues, but it remains unclear whether peripheral iNKT cells are epigenetically stable or malleable. Repetitive encounters of liver-resident iNKT cells (LiNKTs) with alpha-galactosylceramide (αGalCer)/CD1d-coated nanoparticles (NPs) can trigger their differentiation into a LiNKT cell subset expressing a T regulatory type 1 (TR1)-like (LiNKTR1) transcriptional signature. Here we dissect the epigenetic underpinnings of the LiNKT-LiNKTR1 conversion as compared to those underlying the peptide-major histocompatibility complex (pMHC)-NP-induced T-follicular helper (TFH)-to-TR1 transdifferentiation process. We show that gene upregulation during the LINKT-to-LiNKTR1 cell conversion is associated with demethylation of gene bodies, inter-genic regions, promoters and distal gene regulatory elements, in the absence of major changes in chromatin exposure or deposition of expression-promoting histone marks. In contrast, the naïve CD4+ T cell-to-TFH differentiation process involves extensive remodeling of the chromatin and the acquisition of a broad repertoire of epigenetic modifications that are then largely inherited by TFH cell-derived TR1 cell progeny. These observations indicate that LiNKT cells are epigenetically malleable and particularly susceptible to gene de-methylation.

Challenges in the Development of Dengue Vaccine

The development of a dengue vaccine presents numerous challenges, largely due to the complexity of the virus and the human immune response. One of the primary hurdles is Antibody-Dependent Enhancement (ADE), where antibodies from a previous dengue infection can facilitate a more severe secondary infection with a different serotype, exacerbating the disease. Cross-reactivity with other flaviviruses, such as Zika, complicates the immune response further. Additionally, the vaccine must elicit a balanced immune response against all four dengue serotypes, which is difficult to achieve. The role of T follicular helper (TFH) cells in enhancing vaccine efficacy has emerged as a critical area of focus. Efficiently targeting and inducing TFH cells through specific adjuvants could enhance neutralizing antibody production and long-lasting immunity, addressing some of the current vaccine limitations. Despite these challenges, ongoing research and trials continue to advance the field towards a more effective dengue vaccine.

Follicular Helper T Cells in Peyer's Patches and Galactose- Deficient Iga1 Contribute to Iga Nephropathy.

Common primary glomerulonephritis with aberrant mucosal immunity is IgA nephropathy (IgAN). T follicular helper (TFH) cells are essential in regulating B cell differentiation. Peyer's patches (PPs) are the main site where IgA+ plasmablasts differentiate. Our study aimed to investigate the TFH cell's potential contribution to the etiology of IgA nephropathy. In PPs from IgAN mouse models, the ratio of the TFH cell, B220+IgA+, B220+IgM+, and B220-IgA+ lymphocytes were assessed. Then, we used Western blot to assess the expression of Bcl-6, Blimp- 1, and IL-21 proteins in PPs and used RTPCR to assess the expression of IL-21 and TGF-β1 mRNA. TFH cells coculture with spleen cells to measure the degree of IL-21 and the ratio of activation marker CD69 on the TFH cells. Naive B cells (CD27-IgD+) from children suffering from IgAN were cultured with TFH cell-related cytokines. The supernatant was detected to assess the excretion of galactose-deficient IgA1 (Gd-IgA1). IgAN mice developed noticeably increased degrees of IL-21 and CD69 on TFH cells than controls did, as well as higher percentages of B220+IgA+, B220+IgM+, B220+IgA+, TGF- β1, and IL-21 mRNA and Bcl-6, IL-21 proteins in PPs. The Gd-IgA1 level in the supernatant and IgAN- positive children's serum were noticeably higher than those of the healthy controls (P < 0.05). PPs provide the microenvironment to induce the production of IgA-secreting plasmablasts. TFH cells may be a key moderator to induce B cell differentiation into IgAsecreting plasmablasts and produce Gd-IgA1, which plays a significant part in IgAN's pathogenesis. It could be a new therapeutic target in the future.

Oligoclonal CD4+CXCR5+ T cells with a cytotoxic phenotype appear in tonsils and blood

In clinical situations, peripheral blood accessible CD3+CD4+CXCR5+ T-follicular helper (TFH) cells may have to serve as a surrogate indicator for dysregulated germinal center responses in tissues. To determine the heterogeneity of TFH cells in peripheral blood versus tonsils, CD3+CD4+CD45RA–CXCR5+ cells of both origins were sorted. Transcriptomes, TCR repertoires and cell-surface protein expression were analysed by single-cell RNA sequencing, flow cytometry and immunohistochemistry. Reassuringly, all blood-circulating CD3+CD4+CXCR5+ T-cell subpopulations also appear in tonsils, there with some supplementary TFH characteristics, while peripheral blood-derived TFH cells display markers of proliferation and migration. Three further subsets of TFH cells, however, with bona fide T-follicular gene expression patterns, are exclusively found in tonsils. One additional, distinct and oligoclonal CD4+CXCR5+ subpopulation presents pronounced cytotoxic properties. Those ‘killer TFH (TFK) cells’ can be discovered in peripheral blood as well as among tonsillar cells but are located predominantly outside of germinal centers. They appear terminally differentiated and can be distinguished from all other TFH subsets by expression of NKG7 (TIA-1), granzymes, perforin, CCL5, CCR5, EOMES, CRTAM and CX3CR1. All in all, this study provides data for detailed CD4+CXCR5+ T-cell assessment of clinically available blood samples and extrapolation possibilities to their tonsil counterparts.

Interferon subverts an AHR-JUN axis to promote CXCL13+ T cells in lupus.

Systemic lupus erythematosus (SLE) is prototypical autoimmune disease driven by pathological T cell-B cell interactions1,2. Expansion of T follicular helper (TFH) and T peripheral helper (TPH) cells, two T cell populations that provide help to B cells, is a prominent feature of SLE3,4. Human TFH and TPH cells characteristically produce high levels of the B cell chemoattractant CXCL13 (refs. 5,6), yet regulation of T cell CXCL13 production and the relationship between CXCL13+ T cells and other T cell states remains unclear. Here, we identify an imbalance in CD4+ T cell phenotypes in patients with SLE, with expansion of PD-1+/ICOS+ CXCL13+ T cells and reduction of CD96hi IL-22+ T cells. Using CRISPR screens, we identify the aryl hydrocarbon receptor (AHR) as a potent negative regulator of CXCL13 production by human CD4+ T cells. Transcriptomic, epigenetic and functional studies demonstrate that AHR coordinates with AP-1 family member JUN to prevent CXCL13+ TPH/TFH cell differentiation and promote an IL-22+ phenotype. Type I interferon, a pathogenic driver of SLE7, opposes AHR and JUN to promote T cell production of CXCL13. These results place CXCL13+ TPH/TFH cells on a polarization axis opposite from T helper 22(TH22) cells and reveal AHR, JUN and interferon as key regulators of these divergent T cell states.

Clinicopathological characteristics of angioimmunoblastic T-cell lymphoma with B-cell proliferation or neoplasms

Objective: To investigate the clinical, pathological and immunophenotypic features, and differential diagnosis of angioimmunoblastic T-cell lymphoma (AITL) with B-cell proliferation or neoplasms. Methods: Eight qualified cases were collected from the Department of Pathology, the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China from January 2019 to July 2023. One case was diagnosed with AITL and diffuse large B-cell lymphoma (DLBCL) and the other seven cases were diagnosed with AITL and B-cell proliferation. Clinical characteristics and pathological morphology were summarized. Immunohistochemical analysis, fluorescence in situ hybridization and gene rearrangement detection were performed. Results: The patients' average age was 58 years. Five of them were male. Biopsies of the enlarged cervical lymph nodes showed structural destruction and exhibited various histologic patterns. Some cases revealed Burkitt-like morphology, a moderate tumor volume and slightly irregular nuclei. Some cases showed prominent nucleoli. High endothelial venules and expanded follicular dendritic cells were detected. Tumor cells derived from T-follicular helper (TFH) cells were positive for two or more TFH biomarkers. Nodular or diffuse patchy proliferation of B cells was noted around the tumor tissue, which was initially considered as B-cell lymphoma. All of the 8 cases showed monoclonal rearrangements of the T-cell receptor genes while 5 of them also showed clonal rearrangements of the Ig genes. Seven of the 8 cases were subject to the detection of C-MYC gene breakage and were all negative. EBV-positive cells were seen in 6 cases. Neoplastic B cells were positive for C-MYC (>40%), while proliferative B cells were negative for C-MYC (<40%). Conclusions: The histological morphology of AITL with B-cell proliferation or lymphoma may be different from AITL. An integrated analysis, incorporating clinical, morphologic, immunophenotypic, and molecular assessment, helps reach an accurate diagnosis. This group of cases demonstrated the clinical and pathological characteristics of AITL accompanied by B-cell proliferation and B-cell lymphoma. The findings suggest that C-MYC maybe a feasible indicator for distinguishing B-cell proliferation from B-cell lymphoma, and provide a simple and feasible immunohistochemical marker for the diagnosis and research of composite lymphoma.

Reciprocal regulation of T follicular helper cells and dendritic cells drives colitis development.

The immunological mechanisms underlying chronic colitis are poorly understood. T follicular helper (TFH) cells are critical in helping B cells during germinal center reactions. In a T cell transfer colitis model, a lymphoid structure composed of mature dendritic cells (DCs) and TFH cells was found within T cell zones of colonic lymphoid follicles. TFH cells were required for mature DC accumulation, the formation of DC-T cell clusters and colitis development. Moreover, DCs promoted TFH cell differentiation, contributing to colitis development. A lineage-tracing analysis showed that, following migration to the lamina propria, TFH cells transdifferentiated into long-lived pathogenic TH1 cells, promoting colitis development. Our findings have therefore demonstrated the reciprocal regulation of TFH cells and DCs in colonic lymphoid follicles, which is critical in chronic colitis pathogenesis.

Integrated spatial and multimodal single-cell transcriptomics reveal patient-dependent cell heterogeneity in splenic marginal zone lymphoma.

Biological hallmarks of splenic marginal zone lymphoma (SMZL) remain poorly described. Herein, we performed in-depth SMZL characterization through multimodal single-cell analyses of paired blood/spleen samples. The 3'-single-cell RNA-sequencing, Cellular Indexing of Transcriptomes and Epitopes by sequencing, and 5'-V(D)J single-cell RNA-sequencing datasets were integrated to characterize SMZL transcriptome profiles, including B-cell receptor and T-cell receptor repertoires. Hyperexpanded B-cell clones in the spleen were at a memory-like stage, whereas recirculating tumor B-cells in blood encompassed multiple differentiation stages, indicating an unexpected desynchronization of the B-cell maturation program in SMZL cells. Spatial transcriptomics showed the enrichment of T-effector and T-follicular helper (TFH) signatures in the nodular subtype of SMZL. This latter also exhibited gene-based cell-cell interactions suggestive of dynamic crosstalk between TFH and cancer cells in transcriptomics, further substantiated by using imaging mass cytometry. Our findings provide a comprehensive high-resolution description of SMZL biological hallmarks and characterize, for the first time in situ, inter- and intra-patient heterogeneity at both transcriptomic and protein levels. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Survival outcomes after autologous stem cell transplantation in T follicular helper type lymphoma.

7073 Background: T follicular helper (TfH)-type lymphoma is the most common subtype of peripheral T-cell lymphoma (PTCL). TfH lymphoma consists of angioimmunoblastic T-cell lymphoma (AITL), PTCL-TfH and Follicular T cell lymphoma. Most patients receive first-line treatment with anthracycline-based chemotherapy regimens with a potential role for consolidation with autologous stem cell transplantation (ASCT). In this study we analyzed survival outcomes in TfH lymphoma. Methods: This is an IRB approved retrospective analysis of patients with TfH lymphoma followed between 1997–2023 at the MD Anderson Cancer Center. Demographics, treatment history, response and survival outcomes were collected and analyzed. Next-generation sequencing (NGS) data was collected from a panel of 162 cancer-related genes. Survival analysis was performed with Kaplan Meier curves and comparisons were made with log-rank tests. Results: Of the 218 patients with TfH lymphoma for whom information was known about prior history of ASCT, 84 (39%) underwent ASCT (Table). At the time of diagnosis, the majority of patients had advanced stage disease (92% with stage III or IV) and elevated LDH (89%). NGS testing was available from 31 patients and the genes with recurrent somatic mutations identified were TET2 (65% patients), DNMT3A (29%), RHOA (13%), IDH2 (10%), PLCG1 (10%), TP53 (10%), ATM (6%), CCR7 (6%), JAK3 (6%) and STAT3 (6%). The three most common first-line treatments were CHOP (37%) followed by CHOEP (14%) and combination of brentuximab with either CHP or CHEP (13%). Patients who received ASCT were significantly younger (Table). The median overall survival (OS) for the cohort was 40.3 months with median progression-free survival (PFS) after first treatment of 12.5 months. Patients who received ASCT had a significantly higher overall survival (log-rank test p-value &lt; 0.01) compared to those who did not receive ASCT. Conclusions: This retrospective analysis of a large single institution cohort of patients with TfH lymphoma found significantly improved OS in those who underwent ASCT compared to those who did not. Given the sizeable proportion of patients who are transplant-ineligible due to age or comorbidities, there is a need for newer consolidation approaches for TfH lymphoma. [Table: see text]

Immunophenotypic classification regarding prognosis in peripheral T cell lymphoma, NOS, and nodal T follicular helper T cell lymphoma, angioimmunoblastic-type.

This study aimed to determine the clinicopathological predictive factors of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS), and nodal T-follicular helper cell lymphoma, angioimmunoblastic-type (nTFH, AI-type). In this single-centered, retrospective study, medical records of 59 patients who were diagnosed with PTCL, NOS, or nTFH, AI-type from March 2007 to September 2022 were reviewed. The clinicopathological variables, including immunohistochemistry(IHC) subgroups, distinguishing TBX21 from the GATA3 subgroups were analyzed. Overall, 28 patients (75.7%) in the TBX21 group were PTCL, NOS. There were 9 (24.3%) patients in the GATA3 group. In univariable analyses, lymphoma subtype, age, and performance status were associated with progression-free survival (PFS), and overall survival (OS). In multivariable analyses, lymphoma subtype, and performance status were related to PFS and OS (P = 0.012, P < 0.001, P = 0.006, and P < 0.001, respectively). The GATA3 subgroup tended to have a worse prognosis in univariable analyses; however, it became more insignificant in multivariable when lymphoma subtype and performance status were adjusted (P = 0.065, P = 0.180, P = 0.972, and P = 0.265, respectively). The double-positive group showed variable prognoses of better PFS and worse OS. PD-1 and PD-L1 were associated with the EBV in situ hybridization (P = 0.027, and P = 0.005), and PD-1 was associated with CD30 expression (P = 0.043). This study demonstrated the potential of IHC classification to predict prognosis for PTCL, NOS, as well as nTFH AI-type, although further validation is necessary. Treatments targeting CD30, PD-1, and PD-L1 appear promising for lymphoma treatment.

Phase II Trial of Romidepsin as Consolidation Therapy after Gemcitabine, Dexamethasone, and Cisplatin in Elderly Transplant-Ineligible Patients with Relapsed/Refractory Peripheral T-Cell Lymphoma.

Romidepsin is an important therapeutic option for patients with peripheral T-cell lymphoma (PTCL). However, the timing of romidepsin administration remains controversial. The objective of this study was to characterize the safety and efficacy of romidepsin as consolidation therapy after gemcitabine, dexamethasone, and cisplatin (GDP) therapy (GDPR). This study of patients treated between March 2019 and March 2021 was registered with the Japan Registry of Clinical Trials (registration number: jRCT0000000519). If complete response, partial response, or stable disease was confirmed after 2-4 GDP cycles, romidepsin was administered every 4 weeks for 1 year. Seven patients with relapsed/refractory (R/R) PTCL (T-follicular helper phenotype [n = 1] and angioimmunoblastic T-cell lymphoma [n = 6]) were included in this prospective study (PTCL-GDPR). After a median follow-up of 34 months of patients in PTCL-GDPR, the 2-year overall survival rate was 71%, and the overall response rate after treatment was 57%. Common adverse events in patients with PTCL-GDPR included hematological toxicities such as neutropenia, which improved with supportive treatment. There were no treatment-related mortalities. GDPR might be safe and effective in elderly transplant-ineligible patients with R/R PTCL; however, further investigation is required.

A new mode for the diagnosis of angioimmunoblastic T-cell lymphoma.

In order to explore a new mode for the diagnosis of angioimmunoblastic T-cell lymphoma (AITL), 31 cases of AITL and 28 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) were used as the study subjects. Identifying T follicular helper (TFH) cells with CD4, CD10, Bcl-6, and PD-1, identifying proliferative B cells with CD20 and EZH2, identifying proliferative follicular dendritic cells (FDCs) with CD21 and CD23, and analyzing the value of TFH/B/FDC proliferation and immunolocalization in the diagnosis of AITL. (1) Outside the inherent lymphoid follicles, simultaneous proliferation of TFH/B/FDC (a new diagnostic mode) were observed in AITL [83.87%; 26/31], with their immunolocalizations in the same site [83.87%; 26/31], while this phenomenon was not observed in 28 cases of PTCL-NOS (P<0.05). (2) The sensitivity and specificity of using this new mode to diagnose AITL were both high (83.87%, 100%), which was superior to CD2 (100%, 0%), CD3 (100%, 0%), CD4 (100%, 32.14%), CD5 (100%, 25%), CD10 (61.9%, 100%), Bcl-6 (42.86%, 100%), PD-1 (83.87%, 96.43%), and its Youden Index (0.84) was the highest. The areas under the curve (AUC) of CD10, Bcl-6, PD-1, and new mode to diagnosis AITL were 0.81, 0.71, 0.90, and 0.92, respectively, while the new mode had the highest AUC. The simultaneous proliferation of TFH/B/FDC cells outside the inherent lymphoid follicles can be used to assist in the diagnosis of AITL, and the simultaneous spatiotemporal proliferation of TFH/B/FDC cells is a specific immunomorphology of AITL.

Blockade of OX40/OX40L signaling using anti-OX40L alleviates murine lupus nephritis.

Genetic variants of the OX40 ligand (OX40L) locus are associated with the risk of systemic lupus erythematosus (SLE), it is unclear how the OX40L blockade delays the lupus phenotype. Therefore, we examined the effects of an anti-OX40L antibody in MRL/Lpr mice. Next, we investigated the effect of anti-OX40L on immunosuppression in keyhole limpet hemocyanin-immunized C57BL/6J mice. In vitro treatment of anti-OX40L in CD4+ T and B220+ B cells was used to explore the role of OX40L in the pathogenesis of SLE. Anti-OX40L alleviated murine lupus nephritis, accompanied by decreased production of anti-dsDNA and proteinuria, as well as lower frequencies of splenic T helper (Th) 1 and T-follicular helper cells (Tfh). In keyhole limpet hemocyanin-immunized mice, decreased levels of immunoglobulins and plasmablasts were observed in the anti-OX40L group. Anti-OX40L reduced the number and area of germinal centers. Compared with the control IgG group, anti-OX40L downregulated CD4+ T-cell differentiation into Th1 and Tfh cells and upregulated CD4+ T-cell differentiation into regulatory T cells in vitro. Furthermore, anti-OX40L inhibited toll-like receptor 7-mediated differentiation of antibody-secreting cells and antibody production through the regulation of the SPIB-BLIMP1-XBP1 axis in B cells. These results suggest that OX40L is a promising therapeutic target for SLE.

Single-shot dendritic cell targeting SARS-CoV-2 vaccine candidate induces broad, durable and protective systemic and mucosal immunity in mice

Current coronavirus disease 2019 vaccines face limitations including waning immunity, immune escape by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, limited cellular response, and poor mucosal immunity. We engineered a Clec9A-receptor binding domain (RBD) antibody construct that delivers the SARS-CoV-2 RBD to conventional type 1 dendritic cells. Compared with non-targeting approaches, single dose immunization in mice with Clec9A-RBD induced far higher RBD-specific antibody titers that were sustained for up to 21months after vaccination. Uniquely, increasing neutralizing and antibody-dependent cytotoxicity activities across the sarbecovirus family was observed, suggesting antibody affinity maturation over time. Consistently and remarkably, RBD-specific follicular T helper cells and germinal center B cells persisted up to 12months after immunization. Furthermore, Clec9A-RBD immunization induced a durable mono- and poly-functional T-helper 1-biased cellular response that was strongly cross-reactive against SARS-CoV-2 variants of concern, including Omicron subvariants, and with a robust CD8+ Tcell signature. Uniquely, Clec9A-RBD single-shot systemic immunization effectively primed RBD-specific cellular and humoral immunity in lung and resulted in significant protection against homologous SARS-CoV-2 challenge as evidenced by limited body weight loss and approximately 2 log10 decrease in lung viral loads compared with non-immunized controls. Therefore, Clec9A-RBD immunization has the potential to trigger robust and sustained, systemic and mucosal protective immunity against rapidly evolving SARS-CoV2 variants.

Mechanisms of TFR cell-mediated regulation of microbiota-reactive IgA responses

Abstract The rising prevalence of food allergies impacting over 10% of the U.S. population requires innovative diagnostic approaches and therapeutic interventions. Gut microbiota alterations play a crucial role in food allergy development, with immunoglobulin IgA (IgA) actively regulating gut microbiome composition. While T follicular helper (TFH) cells aid in high-affinity antigen-specific IgA production, T follicular regulatory (TFR) cells' role in generating microbiota-specific IgA remains unclear. Using a unique TFR cell-deficient mouse model (Bcl6FC) and flow cytometry staining, we found increased fecal IgA-coated bacteria over time in Bcl6FC compared to WT mice after sensitization. IgA-seq revealed differential baseline microbiota IgA-coating in naïve Bcl6FC, displaying increased alpha diversity and more taxa with higher relative abundance than WT mice. Calculating the IgA-index demonstrated elevated IgA binding in Bcl6FC mice to specific taxa, primarily Firmicute members, indicating TFR cells' suppression of taxon-specific IgA in the peanut allergy model. Ongoing experiments, including the adoptive transfer of WT TFR cells into Bcl6FC mice and the assessment of IgA-coated biome function via Fecal Microbiota Transplantation (FMT) into germ-free mice in a peanut allergy model, aim to validate TFR cells' role in generating microbiota-specific IgA responses. This contributes essential insights for potential therapeutic antibodies targeting specific commensals.

Germinal center cytokine driven epigenetic control of Epstein-Barr virus latency gene expression.

Epstein-Barr virus (EBV) persistently infects 95% of adults worldwide and is associated with multiple human lymphomas that express characteristic EBV latency programs used by the virus to navigate the B-cell compartment. Upon primary infection, the EBV latency III program, comprised of six Epstein-Barr Nuclear Antigens (EBNA) and two Latent Membrane Protein (LMP) antigens, drives infected B-cells into germinal center (GC). By incompletely understood mechanisms, GC microenvironmental cues trigger the EBV genome to switch to the latency II program, comprised of EBNA1, LMP1 and LMP2A and observed in GC-derived Hodgkin lymphoma. To gain insights into pathways and epigenetic mechanisms that control EBV latency reprogramming as EBV-infected B-cells encounter microenvironmental cues, we characterized GC cytokine effects on EBV latency protein expression and on the EBV epigenome. We confirmed and extended prior studies highlighting GC cytokine effects in support of the latency II transition. The T-follicular helper cytokine interleukin 21 (IL-21), which is a major regulator of GC responses, and to a lesser extent IL-4 and IL-10, hyper-induced LMP1 expression, while repressing EBNA expression. However, follicular dendritic cell cytokines including IL-15 and IL-27 downmodulate EBNA but not LMP1 expression. CRISPR editing highlighted that STAT3 and STAT5 were necessary for cytokine mediated EBNA silencing via epigenetic effects at the EBV genomic C promoter. By contrast, STAT3 was instead necessary for LMP1 promoter epigenetic remodeling, including gain of activating histone chromatin marks and loss of repressive polycomb repressive complex silencing marks. Thus, EBV has evolved to coopt STAT signaling to oppositely regulate the epigenetic status of key viral genomic promoters in response to GC cytokine cues.

PD-L1- and IL-4-expressing basophils promote pathogenic accumulation of T follicular helper cells in lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by anti-nuclear autoantibodies whose production is promoted by autoreactive T follicular helper (TFH) cells. During SLE pathogenesis, basophils accumulate in secondary lymphoid organs (SLO), amplify autoantibody production and disease progression through mechanisms that remain to be defined. Here, we provide evidence for a direct functional relationship between TFH cells and basophils during lupus pathogenesis, both in humans and mice. PD-L1 upregulation on basophils and IL-4 production are associated with TFH and TFH2 cell expansions and with disease activity. Pathogenic TFH cell accumulation, maintenance, and function in SLO were dependent on PD-L1 and IL-4 in basophils, which induced a transcriptional program allowing TFH2 cell differentiation and function. Our study establishes a direct mechanistic link between basophils and TFH cells in SLE that promotes autoantibody production and lupus nephritis.