Blimp-1 Expression Research Articles

Spatial microniches of IL-2 combine with IL-10 to drive lung migratory TH2 cells in response to inhaled allergen.

The mechanisms that guide T helper 2 (TH2) cell differentiation in barrier tissues are unclear. Here we describe the molecular pathways driving allergen-specific TH2 cells using temporal, spatial and single-cell transcriptomic tracking of house dust mite-specific T cells in mice. Differentiation and migration of lung allergen-specific TH2 cells requires early expression of the transcriptional repressor Blimp-1. Loss of Blimp-1 during priming in the lymph node ablated the formation of TH2 cells in the lung, indicating early Blimp-1 promotes TH2 cells with migratory capability. IL-2/STAT5 signals and autocrine/paracrine IL-10 from house dust mite-specific T cells were essential for Blimp-1 and subsequent GATA3 upregulation through repression of Bcl6 and Bach2. Spatial microniches of IL-2 in the lymph node supported the earliest Blimp-1+TH2 cells, demonstrating lymph node localization is a driver of TH2 initiation. Our findings identify an early requirement for IL-2-mediated spatial microniches that integrate with allergen-driven IL-10 from responding T cells to drive allergic asthma.

FOS+ B cells: Key mediators of immunotherapy resistance in diverse cancer types

While immunotherapy has marked significant advances in cancer treatment, resistance remains a challenge. The complexity of the tumor microenvironment, particularly the role of B cell subpopulations, is a critical factor affecting treatment efficacy. In this study, we conducted analyses of single-cell RNA sequencing data from immunotherapy patients (n = 25) to explore the biomarker of immunotherapy resistance. Spatial transcriptome analysis, immunofluorescence analysis and multi-cancer immunotherapy transcriptome analysis (n = 1253) were used to validate our finding, and the potential mechanisms were explored. FOS+ B cells, identified across multiple cancer types, were associated with poor response to immunotherapy. FOS may form AP-1 (activator protein 1) with JUNB, thereby promoting the expression of Blimp-1 and subsequently facilitating the differentiation of B cells into immunosuppressive plasma cells. Furthermore, FOS+ B cells were linked to altered TNF signaling pathways, suggesting a mechanism for their immunosuppressive effects. Our findings highlight FOS+ B cells as important players in immunotherapy resistance, providing a novel biomarker for predicting treatment response. This study not only deepens our understanding of the immunological landscape influencing immunotherapy efficacy but also opens avenues for targeted interventions to overcome resistance.

Dissecting the metabolic signaling pathways by which microbial molecules drive the differentiation of regulatory B cells

The host-microbiome axis has been implicated in promoting anti-inflammatory immune responses. Yet, the underlying molecular mechanisms of commensal-mediated IL-10 production by regulatory B cells (Bregs) are not fully elucidated. Here, we demonstrate that bacterial CpG motifs trigger the signaling downstream of TLR9 promoting IκBNS-mediated expression of Blimp-1, a transcription regulator of IL-10. Surprisingly, this effect was counteracted by the NF-κB transcription factor c-Rel. A functional screen for intestinal bacterial species identified the commensal Clostridium sporogenes, secreting high amounts of short-chain fatty acids (SCFAs) and branched-chain fatty acids (BCFAs), as an amplifier of IL-10 production by promoting sustained mTOR signaling in B cells. Consequently, enhanced Breg functionality was achieved by combining CpG with the SCFA butyrate or the BCFA isovalerate thereby synergizing TLR- and mTOR-mediated pathways. Collectively, Bregs required two bacterial signals (butyrate and CpG) to elicit their full suppressive capacity and ameliorate T cell-mediated intestinal inflammation. Our study has dissected the molecular pathways induced by bacterial factors, which might contribute not only to better understanding of host-microbiome interactions, but also to exploration of new strategies for improvement of anti-inflammatory cellular therapy.

IL-27/Blimp-1 axis regulates the differentiation and function of Tim-3+ Tregs during early pregnancy.

Decidual regulatory T cells (Tregs) are essential for successful pregnancy outcome. A subset of Tregs, T cell immunoglobulin and mucin domain-containing protein 3-positive regulatory T cells (TregsTim-3+), plays a central role in the acceptance of the fetus during early stages of normal pregnancy. The molecular mechanism regulating the differentiation and function of TregsTim-3+ is unknown. Here, we investigated the role of the transcription factor B lymphocyte-induced maturation protein 1 (Blimp-1) on decidual TregTim-3+ differentiation. We demonstrated that Blimp-1 enhanced the coexpression of negative costimulatory molecules (Tim-3, T cell immunoreceptor with Ig and ITIM domains, and programmed cell death protein 1) on Tregs and improved their immunosuppressive functions, including increased IL-10 secretion, suppression of effector T cell proliferation, and promotion of macrophage polarization toward the M2 phenotype. Furthermore, we showed that IL-27 regulated the expression of Tim-3 and Blimp-1 through the STAT1 signaling pathway and that transfer of TregsBlimp-1+ into an abortion-prone mouse model effectively reduced embryo absorption rate. We postulated that abnormalities in the IL-27/Blimp-1 axis might be associated with recurrent pregnancy loss (RPL). These findings provided insights for developing more efficient immunotherapies for women with RPL.

Maternal Synbiotic Supplementation with B. breve M-16V and scGOS/lcFOS Shape Offspring Immune Development and Gut Microbiota at the End of Suckling.

Immune system development during gestation and suckling is significantly modulated by maternal environmental and dietary factors. Breastfeeding is widely recognized as the optimal source of nutrition for infant growth and immune maturation, and its composition can be modulated by the maternal diet. In the present work, we investigated whether oral supplementation with Bifidobacterium breve M-16V and short-chain galacto-oligosaccharide (scGOS) and long-chain fructo-oligosaccharide (lcFOS) to rat dams during gestation and lactation has an impact on the immune system and microbiota composition of the offspring at day 21 of life. On that day, blood, adipose tissue, small intestine (SI), mesenteric lymph nodes (MLN), salivary gland (SG), cecum, and spleen were collected. Synbiotic supplementation did not affect the overall body or organ growth of the pups. The gene expression of Tlr9, Muc2, IgA, and Blimp1 were upregulated in the SI, and the increase in IgA gene expression was further confirmed at the protein level in the gut wash. Synbiotic supplementation also positively impacted the microbiota composition in both the small and large intestines, resulting in higher proportions of Bifidobacterium genus, among others. In addition, there was an increase in butanoic, isobutanoic, and acetic acid concentrations in the cecum but a reduction in the small intestine. At the systemic level, synbiotic supplementation resulted in higher levels of immunoglobulin IgG2c in plasma, SG, and MLN, but it did not modify the main lymphocyte subsets in the spleen and MLN. Overall, synbiotic maternal supplementation is able to positively influence the immune system development and microbiota of the suckling offspring, particularly at the gastrointestinal level.

Neutrophil-mediated hypoxia drives pathogenic CD8+ T cell responses in cutaneous leishmaniasis.

Cutaneous leishmaniasis caused by Leishmania parasites exhibits a wide range of clinical manifestations. Although parasites influence disease severity, cytolytic CD8+ T cell responses mediate disease. Although these responses originate in the lymph node, we found that expression of the cytolytic effector molecule granzyme B was restricted to lesional CD8+ T cells in Leishmania-infected mice, suggesting that local cues within inflamed skin induced cytolytic function. Expression of Blimp-1 (Prdm1), a transcription factor necessary for cytolytic CD8+ T cell differentiation, was driven by hypoxia within the inflamed skin. Hypoxia was further enhanced by the recruitment of neutrophils that consumed oxygen to produce ROS and ultimately increased the hypoxic state and granzyme B expression in CD8+ T cells. Importantly, lesions from patients with cutaneous leishmaniasis exhibited hypoxia transcription signatures that correlated with the presence of neutrophils. Thus, targeting hypoxia-driven signals that support local differentiation of cytolytic CD8+ T cells may improve the prognosis for patients with cutaneous leishmaniasis, as well as for other inflammatory skin diseases in which cytolytic CD8+ T cells contribute to pathogenesis.

B-lymphocyte-induced maturation protein-1 inhibits inflammation and pyroptosis to alleviate sepsis injury.

Liver and lung tissue damage caused by sepsis is still one of the causes of death. B-lymphocyte-induced maturation protein-1 (Blimp-1) has a protective role in inflammation-related disease. However, whether Blimp-1 can regulate cell pyroptosis and affect disease progression in sepsis is still unclear. Animal and cell models were established by the cecal ligation and puncture method and lipopolysaccharides (LPS)-induced RAW 264.7 cells, respectively, and the role of Blimp-1 in regulation inflammatory response and pyroptosis was verified. The changes of inflammation and pyroptosis in liver and lung tissues of septic mice were determined by the addition of TAK-242 (TLR4 inhibitor). Cell pyroptosis and the level of inflammation was detected after Blimp-1 knockdown and TAK-242 treatment in the cell model. The expression of Blimp-1 was continuously increased in a septic mice model. After treatment with TAK-242, the expression of Blimp-1, pyroptosis and inflammatory levels were reduced in mice. In the LPS-induced cell model, cell injury by knockout Blimp-1 was increased, and cell activity was restored after TAK-242 intervention. Overexpression of Blimp-1 relieved LPS-induced cellular inflammatory damage and pyroptosis. Our study had shown that Blimp-1 could improve septic damage by regulating the level of cellular inflammation and pyroptosis in sepsis.

BLIMP-1 and CEACAM1 cooperate to regulate human regulatory T cell proliferation and function

Abstract BLIMP-1, encoded by the PRDM1 gene, is a major transcriptional hub distinct from Foxp3 in human Tregs, but its mechanisms of action have not been fully determined. Here, using CRISPR/Cas9-mediated disruption of PRDM1, we show that BLIMP-1 limits Treg proliferation while supports Treg functional activity. PRDM1KO human Tregs are less suppressive and exhibit increased expansion in a humanized mouse model of xenogeneic GVHD. BLIMP-1 restrains Treg proliferation by lowering IL-2R signaling through downregulation of CD25 and by inhibiting responsiveness to TCR/CD28 signaling and mTOR activation through upregulation of CEACAM1, an immune checkpoint. Expression of CEACAM1 is induced by IL-2 in human, but not mouse, Tregs. Prolonged IL-2R signaling leads to optimal BLIMP-1 expression and chromatin opening of human CEACAM1, leading to high cell surface CEACAM1 through a 3’ regulatory region containing motifs for binding PRDM1 and STATs. Correspondingly, CEACAM1 is highly induced on Tregs from autoimmune patients undergoing low-dose IL-2 therapy, and these Tregs showed reduced proliferation. In vivo studies using xenogeneic GVHD mouse model show that CEACAM1KO human Tregs have higher suppressive activities, indicating a potential role of CEACAM1 in Treg function. Collectively, our findings uncover a novel IL-2-dependent regulatory loop whereby BLIMP-1 and CEACAM1 act to limit human Treg proliferation and contribute to Treg suppressive function.

Abstract 7536: CD4+T cell exhaustion in the tumor microenvironment and antitumor immunity

Abstract Background: Immune checkpoint inhibitors (ICIs) exert clinical efficacy against various types of cancer through reinvigoration of exhausted CD8+ T cells that attack cancer cells directly in the tumor microenvironment (TME). However, compared to CD8+ T cell exhaustion, the role of CD4+ T cell exhaustion in antitumor immunity remains unclear. Methods and Results: From single-cell sequencing for tumor-infiltrating lymphocytes (TILs) from patients with melanoma and mouse models, we found that CXCL13, which is highly expressed in tumor-infiltrating exhausted CD8+ T cells, induces PD-1+CXCR5+CD4+ follicular helper T (TFH)-like cell infiltration, which could contribute to antitumor immunity. Furthermore, a part of the TFH-like cells in the TME exhibits cytotoxicity and directly attacks MHC-II-expressing tumors. RNA velocity and latent time analysis in single-cell sequencing for melanoma TILs showed that the differentiation of TFH-like cells from the naive CD4+ T cells were different from that of other CD4+ T cells. In addition, the TFH-like cytotoxic CD4+ T cells were at the late stage of differentiation and some non-cytotoxic TFH-like cells might differentiate into TFH-like cytotoxic CD4+ T cells. We additionally found considerable overlapped clonotypes between the cytotoxic and non-cytotoxic clusters. TFH-like cytotoxic CD4+ T cells have high LAG-3/BLIMP1 and low TCF1 expression without self-renewal ability, whereas non-cytotoxic TFH-like cells express low LAG-3/BLIMP1 and high TCF1 with self-renewal ability, closely resembling the relationship between terminally differentiated and stem-like progenitor exhaustion in CD8+ T cells, respectively. Conclusion: Our findings provide novel insights into TFH-like CD4+ T cell exhaustion with helper progenitor and cytotoxic differentiated functions, which mediates antitumor immunity orchestrally with CD8+ T cells. Citation Format: Joji Nagasaki, Wenhao Zhou, Shusuke Kawashima, Takamasa Ishino, Katsushige Kawase, Youki Ueda, Kazuo Yamashita, Tomofumi Watanabe, Takashi Inozume, Yosuke Togashi. CD4+T cell exhaustion in the tumor microenvironment and antitumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7536.

Increased Nasal Blimp1 + Treg Cells After Sublingual Immunotherapy Reflect the Efficacy of Treatment in Allergic Rhinitis.

Allergen-specific immunotherapy (AIT) plays a pivotal role in altering the immune status and tissue responses in allergic rhinitis (AR). This study focuses on the impact of sublingual immunotherapy (SLIT) involving dust mite drops, exploring the modulation of regulatory Tcells (Treg) and their specific marker, BLIMP1, in the nasal mucosa. Immune cells were isolated from nasal lavage fluid of patients with AR undergoing SLIT (n = 94). Treg cells were analyzed for BLIMP1 expression, and chemokine levels associated with Treg recruitment were assessed using Luminex assay. Patients were categorized on the basis of SLIT efficacy and followed for changes after discontinuation. SLIT induced a significant increase in nasal Treg cells (7.09 ± 2.59% vs. 0.75 ± 0.27%, P < 0.0001). BLIMP1 expression in Treg cells notably increased after SLIT (0.36 ± 0.22% to 16.86 ± 5.74%, P < 0.0001). Ineffective SLIT cases exhibited lower levels of nasal Treg and Blimp1 + Treg cells (both P < 0.0001). Receiver operating characteristic (ROC) analysis confirmed their potential as efficacy predictors (AUC = 0.908 and 0.968, respectively). SLIT discontinuation led to a significant reduction in Treg and Blimp1 + Treg cells (P < 0.001), emphasizing their maintenance during treatment. Pro-inflammatory cytokines decreased (P < 0.001), while CCL2 associated with Treg recruitment increased (P = 0.0015). Elevated nasal Blimp1 + Treg cells serve as a predictive biomarker for SLIT responsiveness in pediatric AR. Their influence on immunotherapy effectiveness contributes to a nuanced understanding of SLIT mechanisms, allowing for disease stratification and personalized treatment plans. This study offers scientific support for predicting SLIT efficacy, enhancing the prospects of improved treatment outcomes in AR.

Circulating NK cells establish tissue residency upon acute infection of skin and mediate accelerated effector responses to secondary infection

Natural killer (NK) cells are present in the circulation and can also be found residing in tissues, and these populations exhibit distinct developmental requirements and are thought to differ in terms of ontogeny. Here, we investigate whether circulating conventional NK (cNK) cells can develop into long-lived tissue-resident NK (trNK) cells following acute infections. We found that viral and bacterial infections of the skin triggered the recruitment of cNK cells and their differentiation into Tcf1hiCD69hi trNK cells that share transcriptional similarity with CD56brightTCF1hi NK cells in human tissues. Skin trNK cells arose from interferon (IFN)-γ-producing effector cells and required restricted expression of the transcriptional regulator Blimp1 to optimize Tcf1-dependent trNK cell formation. Upon secondary infection, trNK cells rapidly gained effector function and mediated an accelerated NK cell response. Thus, cNK cells redistribute and permanently position at sites of previous infection via a mechanism promoting tissue residency that is distinct from Hobit-dependent developmental paths of NK cells and ILC1 seeding tissues during ontogeny.

A National Cancer Database Analysis of Demographics, Treatment Patterns and Survival Trends of Patients with Plasmablastic Lymphoma in US: Does Ethnicity Predict Enhanced Outcomes?

Background: Plasmablastic lymphoma (PbL) is an exceedingly rare, aggressive non-Hodgkin lymphoma with overlapping features of myeloma and lymphoma diagnosed most commonly in immunocompromised individuals, especially in the setting of human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV) infection ( Int J Lab Hematol PMID 36074710). Pathologically, it is characterized by lacking CD20 and PAX5 expression with the presence of CD38, CD138, MUM1/IRF4, Blimp1, and XBP1 expression ( Blood Lymphat Cancer PMID 31360094). There is no established standard of care ( Blood PMID 25636338). Due to the disease's rarity, limited information is available on PbL, especially when focusing on underrepresented minorities. This study aims to describe the demographics, treatment patterns, and survival outcome differences in Hispanic (HI) versus non-Hispanic (NH) patients in the United States with PbL. Methods: Data was analyzed on patients with PbL in the US reported to the NCDB between 2010 and 2019. Sociodemographic and treatment characteristics were compared between ethnic groups. Kaplan-Meier and Cox regression analyses were used to compare overall survival (OS) between HI and NH populations. Multivariate analysis and propensity score matching were performed with adjustment for age, stage, co-morbidity score, insurance status, type of facility and great circle distance. Results: Between 2010 and 2019, 1624 patients were diagnosed with PbL with 16% identified as HI. HI were diagnosed at a younger median age of 48 years as compared to NH at 58 years. Diagnosis was made predominately in males (78%) with no statistical difference between HI and NH. Most HI and NH were white (92% and 74% in HI and NH, respectively) with increased racial diversity among NH. 17% of all patients identified as black with 1% HI and 21% NH. Regarding income, 32% HI had an income less than $38,000 versus 23% NH; whereas, 31% NH had an income greater than $63,000 versus 20% HI [p=0.017]. 38% HI had a Charlson-Deyo Comorbidity Index score ≥ 2 as compared to 27% NH [p&amp;lt;0.001]. Table 1 provides additional information on demographics. 45% of all patients had stage IV disease at the time of diagnosis. 86% of all patients received treatment with no statistical difference among HI and NH [p=0.246]. 67% of HI were treated at academic/research programs compared to 50% of NH [p=0.004]. The median distance between the patient's residence and treatment facility was 6.9 miles for HI versus 9.8 miles for NH [p=0.001]. The survival probability at 2, 5, and 10 years for HI was 59%, 52%, and 42%, respectively as compared to NH was 47%, 37%, and 31%, respectively. The median survival time (MS) was 9.4 years in HI versus 1.4 years in NH [p &amp;lt;0.001]. Figure 1 shows the Kaplan Meier curve comparing overall survival (OS) between HI versus NH.When adjusted on multivariate analysis, there were no independent variables associated with better or worse OS; moreover, propensity matched analysis showed no MS difference between HI vs NH (1.79 years versus 1.17 years). Conclusion: This hospital-based analysis noted that HI presented with PbL at a younger age than NH; however, HI more frequently had a higher Charlson-Deyo Comorbidity Index score than NH. There was no statistical difference in the stage at diagnosis between HI and NH. Additionally, HI had a lower income and no medical insurance as compared to NH suggesting HI possibly had inferior access to medical resources. Paradoxically, HI had significantly higher OS rates. Further insight into the disease's intrinsic characteristics, as well as biological factors, is needed to gain a better understanding of these poor outcomes.

Single-Cell Transcriptomic Profiling of T Cells from Blinatumomab-Treated Patients with B-Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL) Reveals Circulating CD8 T Cell Subsets Associated with Treatment Response

Background Blinatumomab (Blina), a bispecific CD3xCD19 T-cell engager (BiTE®), is approved for patients with relapsed/refractory (R/R) and measurable residual disease (MRD) positive B-Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL). However, a significant percentage of patients do not respond to Blina, and the determinants of resistance are currently unknown. Here, we used Cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) to identify pre-treatment T cell features associated with response. Methods PBMCs of 13 patients with BCP-ALL who received Blina at the LMU Munich University Hospital from 2016 to 2021 were collected before treatment start. CITE-seq(BD Rhapsody Platform) was performed on a total of 34.907 cells isolated via magnetic-activated cell sorting based on the expression of CD3. An AbSeq panel containing 7 surface markers (CD4, CD8, CCR7, CD45RA, CX3CR1, CD127 and PD1) and a customized T-cell targeted RNA sequencing panel (477 genes) were employed. A Monte-Carlo permutation test was used to compare the proportions of cells in different clusters between Responders (R) and Non-Responders (NR). Significant differences were assumed with a fold change threshold of at least 1.5 (log2FC (LFC) ≥ 0.58) and a false discovery rate (FDR) cutoff of &amp;lt; 0.05. Results We used CITE-seq to characterize T cells in peripheral blood (PB) samples obtained from R/R (n=3) and MRD+ (n=10) BCP-ALL patients. Ten patients (9 MRD+, 1 R/R) responded to the Blina treatment. An integrated strategy based on Reciprocal Principal Component Analysis(RPCA) was implemented and bioinformatic analysis of gene expression mapped in two dimensions via uniform manifold approximation and projection (UMAP) identified 12 CD3 pos distinct clusters. Within CD8 pos T cells of R, we found an increased proportion of CCR7 low Granzyme K(GZMK) high Effector Memory-like cells (GZMK high TEM-like, LFC 0.78, 95CI: 0.66 to 0.92; FDR=0.0012) and a reduced percentage of Naïve cells(CCR7 high LEF1 high CD62L high), when compared to NR (LFC -0.59, 95CI: -0.54 to -0.64; FDR =0.0012, Figure1A). Atrend towards an increased proportion of CCR7 lowCX3CR1 highGZMB high terminal effector-like cells (GZMB high TE-like, LFC 0.57, 95CI: 0.45-0.70; FDR=0.0013) was also noted in CD8 pos T cells of R vs NR. Peripheral CD4 pos T cells of R exhibited a tendency towards an increased proportion of GZMK high cytotoxic T cells (LFC 0.43, 95CI: 0.26 to 0.58; FDR=0.0019) and a reduced percentage of FOXP3 high T regulatory cells (LFC -0.19, 95CI: -0.03 to -0.34; FDR=0.025), compared to NR. Furthermore, we investigated gene expression differences between R and NR cells in each cell cluster. Naïve T cells (CD8 and CD4) of NR showed a significantly increased (LFC&amp;gt;1, FDR&amp;lt;0.05, Figure1B) PRDM1 (Blimp-1) expression, a key promoter of T-cell terminal differentiation that is known to be involved in CD19 CAR-T dysfunction. CD8GZMB high TE-likecells of NR showed upregulated expression of genes involved in chemokine production and cytokine signaling (CCL3, IFNGR1) and downregulated LAIR2, a decoy receptor protecting CD8 T cells from collagen-induced exhaustion. Additionally, TOX, a regulator of T cell exhaustion, was moderately upregulated in CD8GZMB high TE-like cells of NR (LFC 0.41, FDR=0.007). Conclusions Taken together, we were able to identify CD8 T cell subsets that are associated with a response to Blina treatment, as well as gene sets involved in BiTE-mediated T-cell function. Interestingly, the PRDM1 overexpression we found in both CD4 and CD8 naive T cells of Non-Responders has already been linked to T-cell dysfunction in the context of CD19 CAR-T cell therapy. We plan to confirm the results of our analysis in an independent patient cohort. Concomitantly, we will enrich the dataset with results from multi-parameter flow cytometry and in vitro T-cell functional assays conducted using longitudinally collected PB samples from Blina-treated patients. Figure1 A)Log Fold Change(log FC) of the proportion of Responders vs Non Responders CD8 pos cells in each cluster. The dots represent the observed logFC, the horizontal line the bootstrapped 95%Confidence Intervals; PTGDR2= prostaglandin D2 receptor 2; ns= not significant B) Differentially expressed genes in Non Responders vs Responders CD8 pos naïve T cells. FDR=False Discovery Rate; CCL5= Chemokine (C-C motif) ligand 5 ; PRDM1= PR/SET Domain 1;SGK1= serum/glucocorticoid regulated kinase 1.

SpiB regulates the expression of B-cell-related genes and increases the longevity of memory B cells.

Generation of memory B cells is one of the key features of adaptive immunity as they respond rapidly to re-exposure to the antigen and generate functional antibodies. Although the functions of memory B cells are becoming clearer, the regulation of memory B cell generation and maintenance is still not well understood. Here we found that transcription factor SpiB is expressed in some germinal center (GC) B cells and memory B cells and participates in the maintenance of memory B cells. Overexpression and knockdown analyses revealed that SpiB suppresses plasma cell differentiation by suppressing the expression of Blimp1 while inducing Bach2 in the in-vitro-induced germinal center B (iGB) cell culture system, and that SpiB facilitates in-vivo appearance of memory-like B cells derived from the iGB cells. Further analysis in IgG1+ cell-specific SpiB conditional knockout (cKO) mice showed that function of SpiB is critical for the generation of late memory B cells but not early memory B cells or GC B cells. Gene expression analysis suggested that SpiB-dependent suppression of plasma cell differentiation is independent of the expression of Bach2. We further revealed that SpiB upregulates anti-apoptosis and autophagy genes to control the survival of memory B cells. These findings indicate the function of SpiB in the generation of long-lasting memory B cells to maintain humoral memory.

Vitamin D3 resolved human and experimental asthma via B lymphocyte-induced maturation protein 1 in T cells and innate lymphoid cells.

Vitamin D3 (VitD3) is known to have immunomodulatory functions, and VitD3 deficiency is associated with more severe asthma. We aimed to assess the immunoregulatory effects of VitD3 food supplementation on asthma manifestation, with particular focus on T cells and type 2 innate lymphoid cells. Preschool children and adult asthmatic cohorts were analyzed in the context of VitD3 supplementation and serum levels. In a murine model of ovalbumin-induced asthma, effects of diet VitD3 sufficiency and deficiency on T cells and type 2 innate lymphoid cells immune mechanisms were investigated. We found less severe and better-controlled asthma phenotypes along with reduced need for steroid medication in preschool children and asthmatic adults with VitD3 supplementation. VitD3 serum levels correlated with B lymphocyte-induced maturation protein 1 (Blimp-1) expression in blood peripheral mononuclear cells. VitD3-supplement-fed mice showed decreased asthmatic traits, with a decrease in IgE serum levels, reduced airway mucus, and increased IL-10 production by lung cells. Furthermore, we discovered an upregulation of effector T cells and Blimp-1+ lung tissue-resident memory T cells as well as induction of anti-inflammatory Blimp-1+ lung innate lymphoid cells producing IL-10. Supplementing VitD3 resulted in amelioration of clinical asthma manifestations in human studies as well as in experimental allergic asthma, indicating that VitD3 shifts proinflammatory immune responses to anti-inflammatory immune responses via upregulating Blimp-1 in lung innate lymphoid cells and tissue-resident memory cells.

T cell receptor signaling strength establishes the chemotactic properties of effector CD8+ T cells that control tissue-residency

Tissue-resident memory (TRM) CD8+ T cells are largely derived from recently activated effector T cells, but the mechanisms that control the extent of TRM differentiation within tissue microenvironments remain unresolved. Here, using an IFNγ-YFP reporter system to identify CD8+ T cells executing antigen-dependent effector functions, we define the transcriptional consequences and functional mechanisms controlled by TCR-signaling strength that occur within the skin during viral infection to promote TRM differentiation. TCR-signaling both enhances CXCR6-mediated migration and suppresses migration toward sphingosine-1-phosphate, indicating the programming of a ‘chemotactic switch’ following secondary antigen encounter within non-lymphoid tissues. Blimp1 was identified as the critical target of TCR re-stimulation that is necessary to establish this chemotactic switch and for TRM differentiation to efficiently occur. Collectively, our findings show that access to antigen presentation and strength of TCR-signaling required for Blimp1 expression establishes the chemotactic properties of effector CD8+ T cells to promote residency within non-lymphoid tissues.

Short-Chain Fatty Acids Alleviate Vancomycin-Caused Humoral Immunity Attenuation in Rabies-Vaccinated Mice by Promoting the Generation of Plasma Cells via Akt-mTOR Pathway.

Mounting evidence suggests that gut microbial composition and its metabolites, including short-chain fatty acids (SCFAs), have beneficial effects in regulating host immunogenicity to vaccines. However, it remains unknown whether and how SCFAs improve the immunogenicity of the rabies vaccine. In this study, we investigated the effect of SCFAs on the immune response to rabies vaccine in vancomycin (Vanco)-treated mice and found that oral gavage with butyrate-producing bacteria (C. butyricum) and butyrate supplementation elevated RABV-specific IgM, IgG, and virus-neutralizing antibodies (VNAs) in Vanco-treated mice. Supplementation with butyrate expanded antigen-specific CD4+ T cells and IFN-γ-secreting cells, augmented germinal center (GC) B cell recruitment, promoted plasma cells (PCs) and RABV-specific antibody-secreting cells (ASCs) generation in Vanco-treated mice. Mechanistically, butyrate enhanced mitochondrial function and activated the Akt-mTOR pathway in primary B cells isolated from Vanco-treated mice, ultimately promoting B lymphocyte-induced maturation protein-1 (Blimp-1) expression and CD138+ PCs generation. These results highlight the important role of butyrate in alleviating Vanco-caused humoral immunity attenuation in rabies-vaccinated mice and maintaining host immune homeostasis. IMPORTANCE The gut microbiome plays many crucial roles in the maintenance of immune homeostasis. Alteration of the gut microbiome and metabolites has been shown to impact vaccine efficacy. SCFAs can act as an energy source for B-cells, thereby promoting both mucosal and systemic immunity in the host by inhibiting HDACs and activation of GPR receptors. This study investigates the impact of orally administered butyrate, an SCFA, on the immunogenicity of rabies vaccines in Vanco-treated mice. The results showed that butyrate ameliorated humoral immunity by facilitating the generation of plasma cells via the Akt-mTOR in Vanco-treated mice. These findings unveil the impact of SCFAs on the immune response of the rabies vaccine and confirm the crucial role of butyrate in regulating immunogenicity to rabies vaccines in antibiotic-treated mice. This study provides a fresh insight into the relationship of microbial metabolites and rabies vaccination.

Oxymatrine ameliorates rheumatoid arthritis by regulation of Tfr/Tfh cell balance via the TLR9-MyD88-STAT3 signaling pathway.

Oxymatrine (OMT) is one of the authentic Chinese herbal medicines which has rich and complex active ingredients. however,the relevant potential targets of oxymatrine on rheumatoid arthritis and the mechanism remains unreported. The aim of this study was to determine the regulation of oxymatrine on rheumatoid arthritis using a collagen-induced arthritis (CIA) mice models and blood samples from RA patients. Our results indicated that Tfr cells in RA patients express low levels of Blimp-1 and CTLA-4. Oxymatrine treatment of CIA mice alleviated joint swelling, reduced the arthritis score, and improved joint damage. While flow cytometry results showed that oxymatrine treatment reduced Tfh cells and B cells, and increased Tfr cells in the spleen of CIA mice. In addition, oxymatrine treatment significantly down-regulated the expression of TLR9（Toll-like Receptors 9), IL-21, MyD88, STAT3, p-STAT3, and CXCR5 in the synovial tissues of CIA mice, and up-regulated the expression of Foxp3, Blimp-1, and CTLA-4. Oxymatrine can alleviate rheumatoid arthritis by regulating the TLR9-MyD88-STAT3 signaling pathway to maintain immune balance between Tfr-Tfh cells. © 2023 Society of Chemical Industry.

Identifying the expression and function of Blimp-1 in ILC2s in allergic asthma

Abstract Allergic asthma is driven by type 2 inflammation from Th2 cell and Type 2 innate lymphoid cells (ILC2s). We recently demonstrated a critical role for Blimp-1, a transcriptional repressor, in Th2 cells to promote allergic asthma. However, the expression and function of Blimp-1 in ILC2s remains undefined. Using genetically modified mouse strains that report Blimp-1 expression via YFP, we surveyed Blimp-1 expression in allergic asthma and other type 2 immune models across various tissues. We found that Blimp-1 is induced in ILC2s in the lung in response to the typical alarmins IL-33 and IL-25, as well as house dust mite (HDM). However, ILC2 activation did not upregulate Blimp-1 in the skin or gut in response to peanut allergen, suggesting a tissue-specific requirement for Blimp-1 in ILC2s. IL-33, as known to be a potent activator of ILC2s, was not required for Blimp-1 expression upon HDM stimulation. Interestingly, IL-10, a potent driver of Blimp-1 in Th2 cells, induced Blimp-1 expression in ILC2s, suggesting IL-10 but not IL-33 may be important for a Blimp-1+ ILC2 state. Intriguingly, Blimp-1 expression did not correlate with cytokine production, potentially representing a unique functional state of ILC2 cells that are high for Blimp-1. To evaluate Blimp-1 function, we deleted Blimp-1 in ILC populations using IL-7Ra Cre crossed to Blimp-1 floxed mice and generated mixed bone marrow chimeras with IL-7Ra Cre control donors. Blimp-1 knockout ILC2s in response to HDM exhibited an alteration in markers of ILC2 activation including ST2, KLRG1 and GATA3, suggesting Blimp-1 plays a role in promoting ILC2 differentiation. Collectively, our study has identified a lung-specific state of ILC2s expressing Blimp-1 that are found in a model of allergic asthma.

B cell Tet2 promotes maturation of the antibody response through active DNA demethylation and OGT-mediated histone glycosylation of Aicdaand Prdm1loci

Abstract Epigenetic DNA methylation regulates gene expression and, therefore, cellular functions. It typically represses gene transcription, which can be re-activated by demethylation in the absence of cell division by the recently characterized Tet1, Tet2 and Tet3 dioxygenases. Tet2, the most abundant Tet protein in B cells, not only actively demethylates DNA but also promotes Ogt recruitment to chromatin to effect Ogt-dependent histone O-GlcNAcylation. This potentiates catalytic DNA demethylation to activate gene expression. To define the role of Tet2 in B cell functions and antibody responses, we generated Aicda creTet2 fl/flmice, which specifically delete Tet2 in activated B cells. Aicda creTet2 fl/flmice showed significantly reduced antibody responses to T-dependent and T-independent antigens, due to downregulation of AID and Blimp-1 expression, CSR/SHM and plasma cell differentiation. Accordingly, activated Aicda creTet2 fl/flB cells reduced DNA hydroxymethylation (resulting in increased methylation) and histone O-GlcNAcylation of Aicda and Prdm1 promoters and enhancers, thereby dampening CSR/SHM and plasma cell differentiation. These were partially rescued by enforced expression of Tet2 mutants defective in catalytic activity or Ogt-binding, but not by a double mutant lacking both activities. Accordingly, Tet2 and Ogt inhibitors synergistically inhibited Aicda and Prdm1 expression in both human and mouse B cells. Conversely, Tet2 activation by vitamin C enhanced CSR and plasma cell differentiation. Thus, Tet2 plays a B cell-intrinsic role in modulation of CSR/SHM and plasma cell differentiation through catalytic active DNA demethylation and (non-catalytic) Ogt-mediated histone O-GlcNAcylation. Supported by NIH grants AI 079705, AI 105813/105813S1, AI138944, AI 167416 and Lupus Research Alliance grant LRA 641363 to PC.