The Imbalance of Circulating Follicular Helper T Cells and Follicular Regulatory T Cells Is Associated With Disease Activity in Patients With Ulcerative Colitis

The molecular subtypes of autoimmune diseases

Autoimmune diseases (ADs) are characterized by their complexity and a wide range of clinical differences. Despite patients presenting with similar symptoms and disease patterns, their reactions to treatments may vary. The current approach of personalized medicine, which relies on molecular data, is seen as an effective method to address the variability in these diseases. This review examined the pathologic classification of ADs, such as multiple sclerosis and lupus nephritis, over time. Acknowledging the limitations inherent in pathologic classification, the focus shifted to molecular classification to achieve a deeper insight into disease heterogeneity. The study outlined the established methods and findings from the molecular classification of ADs, categorizing systemic lupus erythematosus (SLE) into four subtypes, inflammatory bowel disease (IBD) into two, rheumatoid arthritis (RA) into three, and multiple sclerosis (MS) into a single subtype. It was observed that the high inflammation subtype of IBD, the RA inflammation subtype, and the MS "inflammation & EGF" subtype share similarities. These subtypes all display a consistent pattern of inflammation that is primarily driven by the activation of the JAK-STAT pathway, with the effective drugs being those that target this signaling pathway. Additionally, by identifying markers that are uniquely associated with the various subtypes within the same disease, the study was able to describe the differences between subtypes in detail. The findings are expected to contribute to the development of personalized treatment plans for patients and establish a strong basis for tailored approaches to treating autoimmune diseases.

Stem-like T cells are associated with the pathogenesis of ulcerative colitis in humans

To understand the role of T cells in the pathogenesis of ulcerative colitis (UC), we analyzed colonic T cells isolated from patients with UC and controls. Here we identified colonic CD4+ and CD8+ T lymphocyte subsets with gene expression profiles resembling stem-like progenitors, previously reported in several mouse models of autoimmune disease. Stem-like T cells were increased in inflamed areas compared to non-inflamed regions from the same patients. Furthermore, TCR sequence analysis indicated stem-like T cells were clonally related to proinflammatory T cells, suggesting their involvement in sustaining effectors that drive inflammation. Using an adoptive transfer colitis model in mice, we demonstrated that CD4+ T cells deficient in either BCL-6 or TCF1, transcription factors that promote T cell stemness, had decreased colon T cells and diminished pathogenicity. Our results establish a strong association between stem-like T cell populations and UC pathogenesis, highlighting the potential of targeting this population to improve clinical outcomes.

Identification of cuproptosis-related molecular classification and characteristic genes in ulcerative colitis

Ulcerative colitis (UC) is a refractory inflammatory disease with imbalances in intestinal mucosal homeostasis. Cuproptosis serves as newly identified programmed cell death (PCD) form involved in UC. In the study, UC-related datasets were extracted from the Gene Expression Omnibus (GEO) database. A comparison of UC patients and healthy controls identified 11 differentially expressed cuproptosis-related genes (DE-CRGs), where FDX1, LIAS, and DLAT were differentially expressed in UC groups from the mouse models and clinical samples, with their expression correlating with disease severity. By comprehending weighted gene co-expression network analysis (WGCNA) and differential expression analysis, the key genes common to the module genes relevant to different cuproptosis-related clusters and differentially expressed genes (DEGs) both in different clusters and patients with and without UC were identified using several bioinformatic analysis. Furthermore, the mRNA levels of four characteristic genes with diagnostic potential demonstrated significant decrease in both mouse models and clinical UC samples. Our discoveries offer a theoretical foundation for cuproptosis effect in UC.

A Review on Novel Therapeutic Modalities and Evidence-based Drug Treatments against Allergic Rhinitis

Allergic rhinitis (AR) is an IgE-mediated atopic disease that occurs due to inhaled antigens in the immediate phase. Misdiagnosis, insufficient treatment, or no treatment at all are frequent problems associated with the widespread condition known as chronic allergic rhinitis. AR symptoms include runny, itchy, stuffy, and sneezing noses. Asthma and nasal polyps, for example, sometimes occur simultaneously in patients. In order for people living with AR to be as comfortable and productive as possible, treatment should center on reducing their symptoms. The online sources and literature, such as Pubmed, ScienceDirect, and Medline, were reviewed to gather information regarding therapeutic modalities of AR and evidence-based treatments for the disease as the objectives of the present study. An increasing number of people are suffering from AR, resulting in a heavy financial and medical burden on healthcare systems around the world. Undertreating AR frequently results in a decline in quality of life. Treatment compliance is a critical challenge in the administration of AR. Innovative therapies are needed for RA to provide patients with symptom alleviation that is less expensive, more effective, and longer duration of action. Evidence-based guidelines are helpful for managing AR illness. Treating AR according to evidence-based standards can help in disease management. AR treatment includes allergen avoidance, drug therapy, immunotherapy, patient education, and follow-up. However, AR treatment with intranasal corticosteroids is more popular. Hence, in this review article, treatment options for AR are discussed in depth. We also discussed the incidence, causes, and new treatments for this clinical condition.

A precise molecular subtyping of ulcerative colitis reveals the immune heterogeneity and predicts clinical drug responses

BACKGROUND AND AIMS

We sought to identify novel molecular subtypes of ulcerative colitis (UC) based on large-scale cohorts and establish a clinically applicable subtyping system for the precision treatment of the disease.

METHODS

Eight microarray profiles containing colon samples from 357 patients were utilized. Expression heterogeneity was screened out and stable subtypes were identified among UC patients. Immune infiltration pattern and biological agent response were compared among subtypes to assess the value in guiding treatment. The relationship between PRLR and TNFSF13B genes with the highest predictive value was further validated by functional experiments.

RESULTS

Three stable molecular subtypes were successfully identified. Immune cell infiltration analysis defined three subtypes as innate immune activated UC (IIA), whole immune activated UC (WIA), and immune homeostasis like UC (IHL). Notably, the response rate towards biological agents (infliximab/vedolizumab) in WIA patients was the lowest (less than 10%), while the response rate in IHL patients was the highest, ranging from 42 to 60%. Among the featured genes of subtypes, the ratio of PRLR to TNFSF13B could effectively screen for IHL UC subtype suitable for biological agent therapies (Area under curve: 0.961-0.986). Furthermore, we demonstrated that PRLR expressed in epithelial cells could inhibit the expression of TNFSF13B in monocyte-derived macrophages through the CXCL1-NF-κB pathway.

CONCLUSIONS

We identified three stable UC subtypes with a heterogeneous immune pattern and different response rates towards biological agents for the first time. We also established a precise molecular subtyping system and classifier to predict clinical drug response and provide individualized treatment strategies for UC patients.

Altered Phenotypes of Colonic and Peripheral Blood Follicular Helper and Follicular Cytotoxic T Cells in Mice with DSS-Induced Colitis

Background

Follicular helper T (Tfh), follicular regulatory T (Tfr), and follicular cytotoxic T (Tfc) cells play important roles in autoimmune diseases. Nevertheless, their changes of functional phenotypes in ulcerative colitis (UC), most importantly, their changes in colon tissue as the target-organ, have not been explored.

Methods

DSS-colitis was induced in Balb/c mice and lymphocytes were collected from spleen, mesenteric lymph nodes, peripheral blood and colon. Tfh, Tfr, and Tfc cells were analyzed using flow cytometry based on their CD4+CXCR5+FOXP3-Tfh, CD4+CXCR5+FOXP3+Tfr and CD8+CXCR5+Tfc expressions. Various functional characterization markers including CD44, CD62L, TIGIT, CD226, PD-1, ICOS, Helios, CTLA-4 and Bcl6 were analyzed in the T cell subsets of the organs.

Results

Tfh and Tfr cells in the colon were significantly increased in DSS-colitis mice. Additionally, the proportions of Tfr and Tfc cells in the peripheral blood were also increased, while Tfc cell proportions in the colon were decreased. The proportion of naïve cells in the Tfh, Tfr and Tfc cells in the colon and peripheral blood decreased, while the proportion of effector memory T cells increased. The TIGIT+CD226-Tfh and Tfc cells were upregulated in the colon of DSS-colitis mice. The PD-1+, ICOS+ and PD-1+ICOS+ Tfh cells were increased in both the colonic and peripheral blood Tfh and Tfc of DSS-colitis mice. The Bcl6+ proportions in the Tfh and Tfr were increased in the colon of DSS-colitis mice.

Conclusion

The colonic and peripheral blood Tfh and Tfc cells of DSS-colitis mice have a significantly activated T cell phenotype, which may play a significant role in the pathogenesis of UC.

Imbalance of follicular regulatory T (Tfr) cells/follicular helper T (Tfh) cells in adult patients with primary immune thrombocytopenia

This study is to investigate the role of follicular regulatory T (Tfr) cells/follicular helper T (Tfh) cells imbalance in adult patients with primary immune thrombocytopenia (ITP). Totally, 40 cases of primary ITP patients and 30 healthy controls were enrolled. Blood samples were collected from ITP patients (pre- and post-therapy) and controls. Flow cytometry was used to detect the proportion of Tfr and Tfh cells in peripheral blood. Real-time quantitative polymerase chain reaction (PCR) was performed to detect the mRNA expression levels of FOXP3, BCL-6, and BLIMP-1. Enzyme-linked immunosorbent assay (ELISA) was conducted to detect interleukin (IL)-10 and IL-21 levels. Spearman's correlation was used for correlation analysis. Compared with control, Tfr cell proportion, FOXP3 mRNA, and IL-10 were significantly decreased in the pre-therapy ITP group, but were significantly increased post-therapy. Tfh cell proportion, BCL-6 mRNA, and IL-21 were increased, while BLIMP-1 mRNA was decreased, in the pre-therapy ITP group than the control group. These effects were reversed in the post-therapy ITP group. Moreover, the Tfr/Tfh ratio was decreased in the pre-therapy ITP group than control group, whereas was increased in the post-therapy ITP group than the pre-therapy ITP group. Furthermore, Tfr cell proportion, FOXP3 mRNA, IL-10, and Tfr/Tfh ratio were positively correlated with the platelet count (PLT) in the ITP pre-therapy group. In addition, Tfh cell proportion, BCL-6 mRNA, and IL-21 were negatively correlated with the PLT, while BLIMP-1 mRNA was positively correlated with the PLT. Conclusively, Tfr cell proportion in peripheral blood is decreased and Tfh cell proportion is increased, leading to unbalanced Tfr/Tfh ratio in ITP patients pre-therapy. The imbalance of Tfr/Tfh is recovered post-therapy, suggesting that the Tfr and Tfh cells may be involved in ITP pathogenesis. The abnormal expression of FOXP3, BCL-6, and BLIMP-1 mRNA and the changes in IL-10 and IL-21 levels may be related to the imbalance of Tfr/Tfh.

Human intestinal B cells in inflammatory diseases

The intestinal lumen contains an abundance of bacteria, viruses and fungi alongside ingested material that shape the chronically active intestinal immune system from early life to maintain the integrity of the gut epithelial barrier. In health, the response is intricately balanced to provide active protection against pathogen invasion whilst tolerating food and avoiding inflammation. B cells are central to achieving this protection. Their activation and maturation generates the body's largest plasma cell population that secretes IgA, and the niches they provide support systemic immune cell specialization. For example, the gut supports the development and maturation of a splenic B cell subset - the marginal zone B cells. In addition, cells such as the T follicular helper cells, which are enriched in many autoinflammatory diseases, are intrinsically associated with the germinal centre microenvironment that is more abundant in the gut than in any other tissue in health. In this Review, we discuss intestinal B cells and their role when a loss of homeostasis results in intestinal and systemic inflammatory diseases.

Update on pathomechanisms and treatments in allergic rhinitis

Allergic rhinitis (AR) is a global health problem with increasing prevalence and association with an enormous medical and socioeconomic burden. New recognition of immune cells such as type 2 innate lymphocytes (ILC2s), T helper (Th2) 2 cells, follicular helper T cells, follicular regulatory T cells, regulatory T cells, B cells, dendritic cells, and epithelial cells in AR pathogenesis has been updated in this review paper. An in-depth understanding of the mechanisms underlying AR will aid the identification of biomarkers associated with disease and ultimately provide valuable parameters critical to guide personalized targeted therapy. As the only etiological treatment option for AR, allergen-specific immunotherapy (AIT) has attracted increasing attention, with evidence for effectiveness of AIT recently demonstrated in several randomized controlled trials and long-term real-life studies. The exploration of biologics as therapeutic options has only involved anti-IgE and anti-type 2 inflammatory agents; however, the cost-effectiveness of these agents remains to be elucidated precisely. In the midst of the currently on-going COVID-19 pandemic, a global life-threatening disease, although some studies have indicated that AR is not a risk factor for severity and mortality of COVID-19, this needs to be confirmed in multi-centre, real-life studies of AR patients from different parts of the world.

CXCL13 is elevated in inflammatory bowel disease in mice and humans and is implicated in disease pathogenesis

CXCL13 is a chemokine that is widely involved in the pathogenesis of autoimmune diseases, tumors and inflammatory diseases. In this study, we investigate the role of CXCL13 in the pathogenesis of inflammatory bowel disease using both clinical specimens and animal models. We found that the serum CXCL13 concentration in IBD patients was significantly higher than that in healthy controls, and correlated with that of CRP, neutrophils counts and hemoglobin. The increase of CXCL13 in IBD patients might be related to the significant decrease of circulating CD4+CXCR5+ T cells, the increase of CD19+CD5+ B cells and the enhancement of humoral immunity. In mice colitis model, we also found elevated levels of CXCL13 in colon tissue. Cxcl13^-/- knockout mice exhibited a mild, self-limiting form of disease. Additionally, CXCL13 deficiency restricted CD4+CXCR5+ T cells migration in mesenteric lymph nodes, resulting locally regulatory B cells increased in colon. In conclusion, our findings raise the possibility that CXCL13 plays a critical role in the pathogenesis of IBD. We believe that our findings will contribute to the understanding of the etiology, and that antagonizing or inhibiting CXCL13 may work as a potential adjunctive therapy strategy for patients with IBD.

Identification of Potential Biomarkers and Immune Infiltration Characteristics in Ulcerative Colitis by Combining Results from Two Machine Learning Algorithms

Objective

This study was designed to identify potential biomarkers for ulcerative colitis (UC) and analyze the immune infiltration characteristics in UC.

Methods

Datasets containing human UC and normal control tissues (GSE87466, GSE107597, and GSE13367) were downloaded from the GEO database. Then, the GSE87466 and GSE107597 datasets were merged, and the differentially expressed genes (DEGs) between UC and normal control tissues were screened out by the “limma R” package. The LASSO regression model and support vector machine recursive feature elimination (SVM-RFE) were performed to screen out the best biomarkers. The GSE13367 dataset was used as a validation cohort, and the receiver operating characteristic curve (ROC) was used to evaluate the diagnostic performance. Finally, the immune infiltration characteristics in UC were explored by CIBERSORT, and we further analyzed the correlation between potential biomarkers and different immune cells.

Results

A total of 76 DEGs were screened out, among which 56 genes were upregulated and 20 genes were downregulated. Functional enrichment analysis revealed that these DEGs were mainly involved in immune response, chemokine signaling, IL−17 signaling, cytokine receptor interactions, inflammatory bowel disease, etc. ABCG2, HSPB3, SLC6A14, and VNN1 were identified as potential biomarkers for UC and validated in the GSE13367 dataset (AUC = 0.889, 95% CI: 0.797~0.961). Immune infiltration analysis by CIBERSORT revealed that there were significant differences in immune infiltration characteristics between UC and normal control tissues. A high level of memory B cells, γδ T cells, activated mast cells, M1 macrophages, neutrophils, etc. were found in the UC group, while a high level of M2 type macrophages, resting mast cells, eosinophils, CD8+ T cells, etc. were found in the normal control group.

Conclusion

ABCG2, HSPB3, SLC6A14, and VNN 1 were identified as potential biomarkers for UC. There was an obvious difference in immune infiltration between UC and normal control tissues, which may provide help to guide individualized treatment and develop new research directions.

Astragalus polysaccharide alleviates ulcerative colitis by regulating the balance of Tfh/Treg cells

The immunomodulatory function of natural active ingredients has long been a focus of scientific research, with recent hotspots reporting targeted modulation of the follicular helper T cells (Tfh)/regulatory T cells (Treg) balance as an emerging strategy for the treatment of ulcerative colitis (UC). Here, dextran sodium sulfate induced mice UC and Astragalus polysaccharide (APS, 200 mg/kg/day) was administered simultaneously. In this study, APS effectively alleviated colitis in mice by improving survival rate, disease activity index (DAI), the change rate of body weight, colonic length and weight, and histopathological injury of the colon. Moreover, APS regulated the expression of inflammatory cytokines interleukin (IL)-2, IL-6, IL-12p70, IL-23, Tumour necrosis factor (TNF)-ɑ, and transforming growth factor (TGF)-β1 in colonic tissues of colitis mice. Importantly, APS significantly downregulated Tfh cell and the expression of its related nuclear transcription factors Blimp-1 and Bcl-6, and cytokine IL-21. Meanwhile, APS regulated the differentiation of Tfh subpopulations in colitis mice, with Tfh10 and Tfr significantly upregulated while Tfh1, Tfh17, and Tfh21 significantly downregulated. In addition, APS significantly upregulated Treg cells and the levels of its associated nuclear transcription factor Foxp3, and cytokine IL-10 in colitis mice. In conclusion, APS effectively alleviated UC by reshaping the balance of Tfh/Treg cells.

Inflammatory Cytokine-Neutralizing Antibody Treatment Prevented Increases in Follicular Helper T Cells and Follicular Regulatory T Cells in a Mouse Model of Arthritis

Background

Follicular T helper (TFH) and follicular regulatory T (TFR) cells play important roles in humoral immunity. Nevertheless, their significance in rheumatoid arthritis (RA) pathogenesis has not been fully elucidated. As an important treatment strategy, the effect of inflammatory factor-neutralizing antibodies on TFH and TFR in RA remains unclear.

Methods

We used the collagen-induced arthritis (CIA) mouse model to illustrate the quantity and functional changes in TFH and TFR cells. The changes of plasmablast, TFH and TFR cells in the spleen and peripheral blood of CIA mice were analyzed by flow cytometry. The levels of TFH and TFR and their functional subsets in the spleen after anti-inflammatory antibody treatment were analyzed and compared. The functional changes of TFH and TFR in CIA mice before and after treatment were detected by in vitro culture experiments.

Results

Plasmablast levels were increased in CIA spleen and peripheral blood and both TFH and TFR cell levels were upregulated. TFH and TFR cells were decreased significantly after the anti-inflammatory antibody treatment. TIGIT⁺ and TIGIT⁺CD226⁻ TFH cells in CIA mouse spleen were elevated and PD-1 and ICOS expression on spleen TFH and TFR cells was increased. Both the ability of TFH cells to secrete IL-21 and aid B cells and the ability of TFR cells to secrete IL-10 and inhibit TFH cells were enhanced in the CIA mice. After antibody treatment, the cell subsets and functions were recovered.

Conclusion

Germinal center TFH and TFR cells were increased and their functions were enhanced. With inflammatory factor-neutralizing antibody treatment, TFH and TFR subsets and their functions returned to normal. These findings provide important information on the dynamics of humoral immune-related cell subsets in RA and the effects of treatment on them.

Bupi Yichang Pill alleviates dextran sulfate sodium-induced ulcerative colitis in mice by regulating the homeostasis of follicular helper T cells

BACKGROUND

Follicular helper T (Tfh) cells-based therapy represents a new treatment option for inflammatory bowel disease. Bupi Yichang Pill (BPYCP), a traditional Chinese formula for the treatment of dysentery and diarrhea, exhibits potential anti-inflammatory activities in treating various kinds of inflammation. However, its anti-inflammatory effect on colitis and the underlying mechanisms remain unknown.

PURPOSE

To explore the protective role and underlying immunomodulatory effects of BPYCP in the treatment of UC.

METHODS

The dextran sodium sulfate (DSS) free-drinking method induced UC in C57BL/6 mice, and BPYCP was orally administrated at a dosage of 1.5, 3.0, or 6.0 g/kg/day. Throughout the experimental period, the effects of BPYCP on DSS-induced clinical symptoms and disease activity index (DAI) were monitored and analyzed. Hematoxylin-eosin staining was used to observe the histopathological injury of the colon. Flow cytometry was used to detect the levels of Tfh cells, Tfh cell subpopulations, and memory Tfh cells. ELISA, Western blot, and qRT-PCR were used to detect the expression of inflammatory cytokines and Tfh cell-related biomarkers.

RESULTS

Medium and high dosages of BPYCP effectively alleviated DSS-induced experimental colitis with increased body weight, survival rate and colonic length, and decreased DAI, colonic weight, and colonic index, as well as less ulcer formation and inflammatory cell infiltration, increased anti-inflammatory cytokine IL-10, and decreased pro-inflammatory cytokines IL-17A, IL-6, and TNF-ɑ. Moreover, BPYCP administration significantly decreased the percentage of Tfh cells and the expression of Tfh markers ICOS, PD-1 and Bcl-6 in the mesenteric lymph nodes of colitis mice. In addition, BPYCP treatment obviously decreased the percentages of Tfh1, Tfh17 and Tem-Tfh cells and upregulated Tfr cells in colitis mice. However, there were no significant regulatory effects of BPYCP on Tfh cell response in normal mice.

CONCLUSION

Taken together, these results demonstrated a protective effect of BPYCP against DSS-induced experimental colitis by regulating Tfh cell homeostasis.

Members of the Regulatory Lymphocyte Club in Common Variable Immunodeficiency

The role of CD4 T regulatory cells is well established in peripheral tolerance and the pathogenesis of the murine model and human autoimmune diseases. CD4 T regulatory cells (CD4 Tregs) have been investigated in common variable immunodeficiency (CVID). Recently, additional members have been added to the club of regulatory lymphocytes. These include CD8 T regulatory (CD8 Tregs), B regulatory (Bregs), and T follicular helper regulatory (T_FR) cells. There are accumulating data to suggest their roles in both human and experimental models of autoimmune disease. Their phenotypic characterization and mechanisms of immunoregulation are evolving. Patients with CVID may present or are associated with an increased frequency of autoimmunity and autoimmune diseases. In this review, we have primarily focused on the characteristics of CD4 Tregs and new players of the regulatory club and their changes in patients with CVID in relation to autoimmunity and emphasized the complexity of interplay among various regulatory lymphocytes. We suggest future careful investigations of phenotypic and functional regulatory lymphocytes in a large cohort of phenotypic and genotypically defined CVID patients to define their role in the pathogenesis of CVID and autoimmunity associated with CVID.

Curcumin Inhibits T Follicular Helper Cell Differentiation in Mice with Dextran Sulfate Sodium (DSS)-Induced Colitis

Follicular helper T cells (Tfh) regulate the differentiation of germinal center B cells and maintain humoral immunity. Notably, imbalances in Tfh differentiation often lead to the development of autoimmune diseases, including inflammatory bowel disease (IBD). Curcumin, a natural product derived from Curcuma longa, is effective in relieving IBD in humans and animals, and its mechanisms of immune regulation need further elaboration. In this study, dextran sodium sulfate induced ulcerative colitis in BALB/c mice, and curcumin was administered simultaneously for 7 days. Curcumin effectively upregulated the change rate of mouse weight, colonic length, down-regulated colonic weight, index of colonic weight, colonic damage score and the levels of pro-inflammatory cytokines IL-6, IL-12, IL-23 and TGF-[Formula: see text]1 in colonic tissues of colitis mice. Importantly, curcumin regulated the differentiation balance of Tfh and their subpopulation in colitis mice; the percentages of Tfh (CD4[Formula: see text]CXCR5[Formula: see text]BCL-6[Formula: see text], CD4[Formula: see text]CXCR5[Formula: see text]PD-1[Formula: see text], CD4[Formula: see text]CXCR5[Formula: see text]PD-L1[Formula: see text], CD4[Formula: see text]CXCR5[Formula: see text]ICOS[Formula: see text], Tfh17 and Tem-Tfh were downregulated significantly, while CD4[Formula: see text]CXCR5[Formula: see text]Blimp-1[Formula: see text], Tfh1, Tfh10, Tfh21, Tfr, Tcm-Tfh and Tem-GC Tfh were upregulated. In addition, curcumin inhibited the expression of Tfh-related transcription factors BCL-6, p-STAT3, Foxp1, Roquin-1, Roquin-2 and SAP, and significantly upregulated the protein levels of Blimp-1 and STAT3 in colon tissue. In conclusion, curcumin may be effective in alleviating dextran sulfate sodium-induced colitis by regulating Tfh differentiation.

Ulcerative colitis is characterized by a plasmablast-skewed humoral response associated with disease activity

B cells, which are critical for intestinal homeostasis, remain understudied in ulcerative colitis (UC). In this study, we recruited three cohorts of patients with UC (primary cohort, n = 145; validation cohort 1, n = 664; and validation cohort 2, n = 143) to comprehensively define the landscape of B cells during UC-associated intestinal inflammation. Using single-cell RNA sequencing, single-cell IgH gene sequencing and protein-level validation, we mapped the compositional, transcriptional and clonotypic landscape of mucosal and circulating B cells. We found major perturbations within the mucosal B cell compartment, including an expansion of naive B cells and IgG⁺ plasma cells with curtailed diversity and maturation. Furthermore, we isolated an auto-reactive plasma cell clone targeting integrin αvβ6 from inflamed UC intestines. We also identified a subset of intestinal CXCL13-expressing TFH-like T peripheral helper cells that were associated with the pathogenic B cell response. Finally, across all three cohorts, we confirmed that changes in intestinal humoral immunity are reflected in circulation by the expansion of gut-homing plasmablasts that correlates with disease activity and predicts disease complications. Our data demonstrate a highly dysregulated B cell response in UC and highlight a potential role of B cells in disease pathogenesis.

Follicular helper and follicular regulatory T cell subset imbalance is associated with higher activated B cells and abnormal autoantibody production in primary anti-phospholipid syndrome patients

Primary anti-phospholipid antibody syndrome (pAPS) is a multi-organ autoimmune disease, and autoantibodies are involved in its pathogenesis. Follicular helper T cells (Tfh) and follicular regulatory T cells (Tfr) are critical for B cell maturation and antibody production, but their roles in pAPS remain unknown. We enrolled 32 pAPS patients and 23 healthy controls (HCs) and comprehensively analyzed circulating Tfh and Tfr, as well as their subsets, using flow cytometry. Clinical data including autoantibody levels were collected and their correlations with Tfh and Tfr subsets were analyzed. In addition, correlation analyses between B cell functional subsets and Tfh and Tfr were performed. Changes and potential effects of serum cytokines on Tfr and Tfh were further explored. We found the circulating Tfr was significantly decreased while Tfh and Tfh/Tfr ratios were increased in pAPS patients. Tfh2, inducible T cell co-stimulator (ICOS)+  programmed cell death 1 (PD-1)+  Tfh and Ki-67+  Tfh percentages were elevated, while CD45RA- forkhead box protein 3 (FoxP3)hi , Helios+ , T cell immunoglobulin and ITIM (TIGIT)+  and Ki-67+  Tfr percentages were decreased in pAPS patients. New memory B cells and plasmablasts were increased and altered B cell subsets and serum autoantibodies were positively correlated with Tfh, Tfh2, ICOS+ PD-1+  Tfh cells and negatively associated with Tfr, CD45RA- FoxP3hi Tfr and Helios+  Tfr cells. In addition, pAPS with LA/aCL/β2GPI autoantibodies showed lower functional Tfr subsets and higher activated Tfh subsets. Serum interleukin (IL)-4, IL-21, IL-12 and transforming growth factor (TGF)-β1 were up-regulated and associated with Tfh and Tfr subset changes. Our study demonstrates that imbalance of circulating Tfr and Tfh, as well as their functional subsets, is associated with abnormal autoantibody levels in pAPS, which may contribute to the pathogenesis of pAPS.

The Role of T Follicular Helper Cells and Interleukin-21 in the Pathogenesis of Inflammatory Bowel Disease

T follicular helper (Tfh) cells represent a novel subset of CD4⁺ T cells which can provide critical help for germinal center (GC) formation and antibody production. The Tfh cells are characterized by the expression of CXC chemokine receptor 5 (CXCR5), programmed death 1 (PD-1), inducible costimulatory molecule (ICOS), B cell lymphoma 6 (BCL-6), and the secretion of interleukin-21 (IL-21). Given the important role of Tfh cells in B cell activation and high-affinity antibody production, Tfh cells are involved in the pathogenesis of many human diseases. Inflammatory bowel disease (IBD) is a group of chronic inflammatory diseases characterized by symptoms such as diarrhea, abdominal pain, and weight loss. Ulcerative colitis (UC) and Crohn's disease (CD) are the most studied types of IBD. Dysregulated mucosal immune response plays an important role in the pathogenesis of IBD. In recent years, many studies have identified the critical role of Tfh cells and IL-21 in the pathogenic process IBD. In this paper, we will discuss the role of Tfh cells and IL-21 in IBD pathogenesis.

Effect of Glycyrrhiza uralensis against ulcerative colitis through regulating the signaling pathway of FXR/P-gp

OBJECTIVE

Ulcerative colitis (UC) is a moderate to severe inflammatory bowel disease, with a characteristic inflammatory response. Chinese herbal medicine can play a role in UC treatment. Herein, we aimed to investigate the function of Glycyrrhiza uralensis in UC treatment and the underlying mechanism.

METHODS

After establishing an animal model of UC, different agents of kuijieguanchang prescription, Glycyrrhiza uralensis, mesalazine, and GW4064 were administrated to mice. The apoptosis rate was measured by TUNEL assay, and the expression of different biomarkers was tested by western blot and qPCR.

RESULTS

Glycyrrhiza uralensis could regulate apoptosis of intestinal mucosal cells, through regulating the expression of apoptosis-related proteins and protective proteins of intestinal mucosa. The administration of Glycyrrhiza uralensis could greatly enhance the expression of muc1, muc3, and the pro-apoptotic protein, BAX. The proteins involved in malignancy from UC, such as Bcl-2 and fgf-15, were dramatically downregulated after using the Glycyrrhiza uralensis. Moreover, it was illustrated that Glycyrrhiza uralensis acted against UC by activating the signaling of P-gp through upregualting its expression. The upregulation of FGFR4, SHP, and P-gp in liver conferred protective function in UC.

CONCLUSION

Glycyrrhiza uralensis could regulate apoptosis of intestinal mucosal cells, through regulating the expression of apoptosis-related proteins and protective proteins of intestinal mucosa. The results provide novel options for UC treatment, as well as a rationale for pharmacology of Chinese traditional medicine, that is favorable for use of herbal medicine.

Differentiation, functions, and roles of T follicular regulatory cells in autoimmune diseases

T follicular helper cells participate in stimulating germinal center (GC) formation and supporting B cell differentiation and autoantibody production. However, T follicular regulatory (Tfr) cells suppress B cell activation. Since changes in the number and functions of Tfr cells lead to dysregulated GC reaction and autoantibody response, targeting Tfr cells may benefit the treatment of autoimmune diseases. Differentiation of Tfr cells is a multistage and multifactorial process with various positive and negative regulators. Therefore, understanding the signals regulating Tfr cell generation is crucial for the development of targeted therapies. In this review, we discuss recent studies that have elucidated the roles of Tfr cells in autoimmune diseases and investigated the modulators of Tfr cell differentiation. Additionally, potential immunotherapies targeting Tfr cells are highlighted.

Altered follicular regulatory T (Tfr)- and helper T (Tfh)-cell subsets are associated with autoantibody levels in microscopic polyangiitis patients

Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) is an autoimmune disease characterized by B cells-derived ANCAs, and ANCA was proved to be a key factor in its pathogenesis. Follicular regulatory T (Tfr) and follicular helper T (Tfh) cells were T-cell subsets that play important roles in B-cell maturation and antibody production. However, their significances in microscopic polyangiitis (MPA) patients, one type of AAV, has not been thoroughly studied. In this study, comprehensive pattern analyses of circulating Tfr and Tfh were performed in MPA patients and healthy controls (HCs), and we found Tfr levels and Tfr/Tfh ratios were significantly decreased in MPA patients. Compared with HCs, Helios+, CD45RA-FoxP3hi, and Ki-67+ Tfr were lower in MPA patients, while CD226+ Tfr cells were higher. These phenotypes suggest that function and proliferation ability of Tfr cells were relatively impaired. Tfh subsets, including ICOS+PD-1+ and Ki-67+ Tfh, were significantly increased, suggesting that the function of Tfh was enhanced in MPA although the total Tfh levels did not change significantly. Circulating memory B cells and plasmablasts were significantly elevated and negatively correlated with Tfr levels and Tfr/Tfh ratios in MPA patients. In addition, Tfr levels and Tfr/Tfh ratios were negatively while Tfh was positively correlated with serum myeloperoxidase (MPO)-ANCA levels. Furthermore, Tfr and Tfr/Tfh ratio were also reversely associated with SCr, BUN, IL-4, and IL-21 levels. Our results suggest that the imbalance of Tfr and Tfh functional subsets is related to increased level of autoantibodies in MPA patients, and we propose a new mechanism for the pathogenesis of MPA.

Increased circulating PD-1hiCXCR5- peripheral helper T cells are associated with disease severity of active ulcerative colitis patients

PURPOSE

A recently identified population of T cells, phenotypically CD4⁺PD-1^hiCXCR5^-, has been firstly termed as peripheral helper T cells (Tph) and found to be pathogenic in autoimmune diseases. However, the potential role of Tph in ulcerative colitis (UC) remains unclear. We aim to investigate the changes of circulating Tph in UC patients and their potential significance in the pathogenesis of UC.

METHODS

Totally 68 UC patients and 34 age- and sex-matched healthy controls were enrolled. Circulating Tph and B cell subsets were analyzed by flow cytometry. Expressions of inducible T-cell co-stimulator (ICOS) on Tph cells were analyzed. Serum IL-4, IL-10, IL-12 and IL-21 were detected using ELISA. Correlation analyses were conducted between Tph cells and disease severity, functional B cell subsets and serum cytokines.

RESULTS

Both the frequency and absolute number of Tph were significantly increased in active UC patients and ICOS levels in Tph cells were also elevated, compared with remission UC patients and healthy controls. Tph and ICOS expression were significantly positively correlated with Mayo score and serum CRP in active UC patients, and were significantly decreased when achieving remission after treatment. Tph levels were correlated with new memory B cells, plasmablasts, serum IL-4 and IL-21. Meanwhile, serum IL-10 showed negative correlation while IL-12 exhibited positive correlation with circulating Tph cells in UC patients.

CONCLUSIONS

Circulating Tph cells are elevated in active UC patients and are associated with the disease activity, which may contribute to the pathogenesis of UC.

Immune Monitoring of Patients With Primary Immune Regulation Disorders Unravels Higher Frequencies of Follicular T Cells With Different Profiles That Associate With Alterations in B Cell Subsets

Primary immune regulation disorders lead to autoimmunity, allergy and inflammatory conditions due to defects in the immune homeostasis affecting different T, B and NK cell subsets. To improve our understanding of these conditions, in this work we analyzed the T and B cell compartments of 15 PID patients with dysregulation, including 3 patients with STAT1 GOF mutation, 7 patients with CVID with dysregulation, 3 patients with mutations in CTLA4, 1 patient with CD25 mutation and 1 patient with STAT5b mutation and compared them with healthy donors and with CVID patients without dysregulation. CD4⁺ and CD8⁺ T cells from the patients exhibited a significant decreased frequency of naïve and regulatory T cells with increased frequencies of activated cells, central memory CD4⁺ T cells, effector memory CD8⁺ T cells and terminal effector CD8⁺ T cells. Patients also exhibited a significantly increased frequency of circulating CD4⁺ follicular helper T cells, with altered frequencies of cTfh cell subsets. Such cTfh cells were skewed toward cTfh1 cells in STAT1 GOF, CTLA4, and CVID patients, while the STAT5b deficient patient presented a skew toward cTfh17 cells. These alterations confirmed the existence of an imbalance in the cTfh1/cTfh17 ratio in these diseases. In addition, we unraveled a marked dysregulation in the B cell compartment, characterized by a prevalence of transitional and naïve B cells in STAT1 GOF and CVID patients, and of switched-memory B cells and plasmablast cells in the STAT5b deficient patient. Moreover, we observed a significant positive correlation between the frequencies cTfh17 cells and switched-memory B cells and between the frequency of switched-memory B cells and the serum IgG. Therefore, primary immunodeficiencies with dysregulation are characterized by a skew toward an activated/memory phenotype within the CD4⁺ and CD8⁺ T cell compartment, accompanied by abnormal frequencies of Tregs, cTfh, and their cTfh1 and cTfh17 subsets that likely impact on B cell help for antibody production, which likely contributes to their autoimmune and inflammatory conditions. Therefore, assessment of these alterations by flow cytometry constitutes a simple and straightforward manner to improve diagnosis of these complex clinical entities that may impact early diagnosis and patients' treatment. Also, our findings unravel phenotypic alterations that might be associated, at least in part, with some of the clinical manifestations observed in these patients.

The multifaceted functions of follicular regulatory T cells

The immune system is capable of generating robust antibody responses to foreign antigens during infection and vaccination, while simultaneously limiting antibodies to self-antigens. T follicular regulatory (Tfr) cells are a subset of follicular T cell with specialized roles in regulating humoral immunity. Although Tfr cells have been studied for the past 10 years, their roles have remained elusive. In this review we discuss the current understanding of Tfr cell functions in autoimmunity and how Tfr cells simultaneously control foreign and autoantigen specific antibody responses. We highlight new tools that enable in-depth study of Tfr cells in vivo and recent data suggesting an important role for Tfr cells in limiting participation of autoreactive B cells in germinal centers.

Activated inducible co-stimulator-positive programmed cell death 1-positive follicular helper T cells indicate disease activity and severity in ulcerative colitis patients

Inducible co-stimulator-positive (ICOS) and programmed cell death 1-positive (PD-1) are important markers for follicular helper T cells (Tfh); however, their roles and clinical values in ulcerative colitis (UC) remain unknown. In this study, we recruited 68 UC patients and 34 healthy controls. Circulating ICOS⁺ , PD-1⁺ and ICOS⁺ PD-1⁺ Tfh subsets were analyzed by flow cytometry. Twelve active UC patients achieving remission after treatment with 5-aminosalicylic acid were followed-up and Tfh subset changes were analyzed. Serum immunoglobulin (Ig)G, C-reactive protein (CRP), interleukin (IL)-4 and IL-21 levels and B cell subsets were analyzed and Mayo scores were calculated. Correlation analyses were performed between Tfh subsets and the clinical indicators. Receiver operating characteristic (ROC) curves were generated to evaluate the efficiency of Tfh subsets for disease monitoring. We found that levels of ICOS⁺ , PD-1⁺ and ICOS⁺ PD-1⁺ Tfh cells were significantly increased in active UC and significantly decreased when achieving clinical remission. Activated ICOS⁺ PD-1⁺ Tfh cells were positively correlated with serum CRP and Mayo scores. Furthermore, ICOS⁺ PD-1⁺ Tfh cells were significantly correlated with circulating new memory B cells and plasmablasts, as well as serum IgG, IL-4 and IL-21. ROC analyses showed that when ICOS⁺ PD-1⁺ Tfh cells were used in combination with PD-1⁺ Tfh cells, the diagnostic efficacy in distinguishing active UC from stable remission patients was higher than that of any one used alone, with area under curve (AUC) value 0·931. Our findings suggest that increased ICOS⁺ PD-1⁺ Tfh cells are associated with the activation of B cells in the pathogenesis of UC, and may be a potential biomarker for UC disease monitoring.

Ustekinumab Inhibits T Follicular Helper Cell Differentiation in Patients With Crohn's Disease

BACKGROUND & AIMS

The pathogenesis of chronic inflammatory bowel diseases (Crohn's disease [CD] and ulcerative colitis) involves dysregulated TH1 and TH17 cell responses, which can be targeted therapeutically by the monoclonal antibody Ustekinumab directed against the joint p40 subunit of IL-12 and IL-23. These cytokines may also regulate the differentiation of T follicular helper (TFH) cells, which promote B cell function in germinal centers. However, the role of TFH cells in CD pathogenesis and impact of Ustekinumab therapy on TFH cell fate in patients are poorly defined.

METHODS

Lymphocytes were isolated from peripheral blood (n=45) and intestinal biopsies (n=15) of CD patients or healthy controls (n=21) and analyzed by flow cytometry to assess TFH cell phenotypes and functions ex vivo. In addition, TFH cell differentiation was analyzed in the presence of Ustekinumab in vitro.

RESULTS

TFH cell frequencies in the intestine as well as peripheral blood were associated with endoscopic as well as biochemical evidence of CD activity. CD patients with clinical response to Ustekinumab, but not those with response to anti-TNF antibodies, displayed reduced frequencies of circulating TFH cells in a concentration-dependent manner while the TFH phenotype was not affected by Ustekinumab therapy. In keeping with this notion, TFH cell differentiation was inhibited by Ustekinumab in vitro while TFH cell maintenance was not affected. Moreover, Ustekinumab therapy resulted in reduced germinal center activity in CD patients in vivo.

CONCLUSIONS

These data implicate TFH cells in the pathogenesis of CD and indicate that Ustekinumab therapy affects TFH cell differentiation, which may influence TFH-mediated immune functions in UST-treated CD patients.