Follicular helper T cell in immunity and autoimmunity

A Phase 1, randomized, double-blind, placebo-controlled, single- and multiple-dose escalation study to evaluate the safety and pharmacokinetics/pharmacodynamics of PF-06835375, a C-X-C chemokine receptor type 5 directed antibody, in patients with systemic lupus erythematosus or rheumatoid arthritis

BACKGROUND

The objective of this study was to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of PF‑06835375, a potent selective afucosyl immunoglobulin G1 antibody targeting C-X-C chemokine receptor type 5 (CXCR5) that potentially depletes B cells, follicular T helper (Tfh) cells, and circulating Tfh-like (cTfh) cells, in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

METHODS

This first-in-human, multicenter, double-blind, sponsor-open, placebo-controlled Phase 1 study recruited patients aged 18-70 years with SLE or RA. In Part A, patients received single doses of intravenous PF-06835375 (dose range: 0.03-6 mg) or placebo in six sequential single ascending dose (SAD) cohorts. In Part B, patients received repeat doses of subcutaneous PF-06835375 (dose range: 0.3-10 mg) or placebo on Days 1 and 29 in five multiple ascending dose (MAD) cohorts. Tetanus/Diphtheria (Td) and Meningococcal B (MenB/Trumenba™) vaccines were administered at Day 4 (Td and MenB) and Week 8 (MenB only) to assess PF-06835375 functional effects. Endpoints included treatment-emergent adverse events (TEAEs), pharmacokinetic parameters, pharmacodynamic effects on B and cTfh cells, and biomarker counts, vaccine response, and exploratory differential gene expression analysis. Safety, pharmacokinetic, and pharmacodynamic endpoints are summarized descriptively. The change from baseline of B and Tfh cell-specific genes over time was calculated using a prespecified mixed-effects model, with a false discovery rate < 0.05 considered statistically significant.

RESULTS

In total, 73 patients were treated (SAD cohorts: SLE, n = 17; RA, n = 14; MAD cohorts: SLE, n = 22; RA, n = 20). Mean age was 53.3 years. Sixty-two (84.9%) patients experienced TEAEs (placebo n = 17; PF-06835375 n = 45); most were mild or moderate. Three (9.7%) patients experienced serious adverse events. Mean t1/2 ranged from 3.4-121.4 h (SAD cohorts) and 162.0-234.0 h (MAD cohorts, Day 29). B and cTfh cell counts generally showed dose-dependent reductions across cohorts (range of mean maximum depletion: 67.3-99.3%/62.4-98.7% [SAD] and 91.1-99.6%/89.5-98.1% [MAD], respectively). B cell-related genes and pathways were significantly downregulated in patients treated with PF-06835375.

CONCLUSIONS

These data support further development of PF-06835375 to assess the clinical potential for B and Tfh cell depletion as a treatment for autoimmune diseases.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03334851.

[An artificial neural network diagnostic model for scleroderma and immune cell infiltration analysis based on mitochondria-associated genes]

OBJECTIVE

To establish a diagnostic model for scleroderma by combining machine learning and artificial neural network based on mitochondria-related genes.

METHODS

The GSE95065 and GSE59785 datasets of scleroderma from GEO database were used for analyzing expressions of mitochondria-related genes, and the differential genes were identified by Random forest, LASSO regression and SVM algorithms. Based on these differential genes, an artificial neural network model was constructed, and its diagnostic accuracy was evaluated by 10-fold crossover verification and ROC curve analysis using the verification dataset GSE76807. The mRNA expressions of the key genes were verified by RT-qPCR in a mouse model of scleroderma. The CIBERSORT algorithm was used to estimate the bioinformatic association between scleroderma and the screened biomarkers.

RESULTS

A total of 24 differential genes were obtained, including 11 up-regulated and 13 down-regulated genes. Seven most relevant mitochondria-related genes (POLB, GSR, KRAS, NT5DC2, NOX4, IGF1, and TGM2) were screened using 3 machine learning algorithms, and the artificial neural network diagnostic model was constructed. The model showed an area under the ROC curves of 0.984 for scleroderma diagnosis (0.740 for the verification dataset and 0.980 for cross-over validation). RT-qPCR detected significant up-regulation of POLB, GSR, KRAS, NOX4, IGF1 and TGM2 mRNAs and significant down-regulation of NT5DC2 in the mouse models of scleroderma. Immune cell infiltration analysis showed that the differential genes in scleroderma were associated with follicular helper T cells, immature B cells, resting dendritic cells, memory activated CD4+T cells, M0 macrophages, monocytes, resting memory CD4+T cells and mast cell activation.

CONCLUSION

The artificial neural network diagnostic model for scleroderma established in this study provides a new perspective for exploring the pathogenesis of scleroderma.

T cell abnormalities in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease with a poor prognosis. To date, the pathogenesis of SSc is still unclear; moreover, its pathological conditions include microvascular damage, inflammation, and immune abnormalities. Different types of T cells may cause vasculitis and fibrosis in SSc by means of up- and down-regulation of cell surface molecules, abnormal release of pro-fibrotic or pro-inflammatory cytokines and direct contact with fibroblasts. These T cells, which are mainly CD4 + T cells, include the subtypes, T follicular helper (Tfh) cells, regulatory T Cells (Treg), interleukin-17 (IL-17)-producing Th17 cells, CD4⁺ cytotoxic T lymphocytes (CTLs), and angiogenic T (Tang) cells. In addition to the Th1/Th2 imbalance, which has long been established, there is also a Th17/Treg imbalance in SSc. This imbalance may be closely related to the abnormal immune status of SSc. There is mounting evidence that suggest T cell abnormalities may be crucial to the pathogenesis of SSc. In terms of treatment, existing therapies that target T cells, such as immunosuppressive therapy (tacrolimus), Janus kinase(JAK) inhibitors, and biologics(abatacept), have had some success. Other non-drug therapies, including Mesenchymal stem cells (MSCs), have extensive and complex mechanisms of action actually including T cell regulation. Based on the current evidence, we believe that the study of T cells will further our understanding of the pathogenesis of SSc, and may lead to more targeted treatment optionsfor patients with SSc.

Targeting Bcl6 in the TREX1 D18N murine model ameliorates autoimmunity by modulating T follicular helper cells and Germinal center B cells

The Three Prime Repair EXonuclease I (TREX1) is critical for degrading post‐apoptosis DNA. Mice expressing catalytically inactive TREX1 (TREX1 D18N) develop lupus‐like autoimmunity due to chronic sensing of undegraded TREX1 DNA substrates, production of the inflammatory cytokines, and the inappropriate activation of innate and adaptive immunity. This study aimed to investigate Thelper (Th) dysregulation in the TREX1 D18N model system as a potential mechanism for lupus‐like autoimmunity. Comparison of immune cells in secondary lymphoid organs, spleen and peripheral lymph nodes (LNs) between TREX1 D18N mice and the TREX1 null mice revealed that the TREX1 D18N mice exhibit a Th1 bias. Additionally, the T‐follicular helper cells (Tfh) and the germinal celter (GC) B cells were also elevated in the TREX1 D18N mice. Targeting Bcl6, a lineage‐defining transcription factor for Tfh and GC B cells, with a commercially available Bcl6 inhibitor, FX1, attenuated Tfh, GC, and Th1 responses, and rescued TREX1 D18N mice from autoimmunity. The study presents Tfh and GC B‐cell responses as potential targets in autoimmunity and that Bcl6 inhibitors may offer therapeutic approach in TREX1‐associated or other lupus‐like diseases.

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.

Exploration of immune-related cells and ceRNA in squamous cell lung cancer

The treatment for squamous cell lung cancer (SqCLC) is limited, and the prognosis of SqCLC is poor. In this article, we aimed to analyze and identify immune-related cells and competition endogenous RNA (ceRNA) that influence the prognosis of SqCLC. SqCLC and lung adenocarcinoma data were downloaded from TCGA-GDC. A total of 22 types of immune cell fractions were estimated using CIBERSORT. R software was used to identify any significantly different transcriptome data, including mRNA, LncRNA, and miRNA. The univariate cox regression method was applied to screen for prognosis-related lncRNA, miRNA, mRNA and tumor-infiltrating immune cells. There were 504 patients included in this study. There was a higher proportion of memory activated CD4+ T cells and CD8+ T cells in younger women. Follicular helper T (Tfh) cells were predictive of a good prognosis and reflected immune activation in SqCLC. The SFTA1P/NKX2-1-AS1, hsa-mir-503, GREM2 ceRNA axes and NKX2-1-AS1, hsa-mir-96, PROK2 ceRNA axes were found to be important for the immune function, pathogenesis, and prognosis of SqCLC. Collectively, the immune-related ceRNA and tumor-infiltrating immune cells in SqCLC are likely important determinants of SqCLC pathogenesis, prognosis, and immune status.

Association of Circulating Follicular Helper T Cells and Serum CXCL13 With Neuromyelitis Optica Spectrum Disorders

Background

Neuromyelitis optica spectrum disorders (NMOSDs) are severe inflammatory diseases mediated mainly by humoral and cellular immunity. Circulating follicular helper T (Tfh) cells are thought to be involved in the pathogenesis of NMOSD, and serum C-X-C motif ligand 13 (CXCL13) levels reflect the effects of Tfh cells on B-cell-mediated humoral immunity. Immune cell and cytokine changes during the dynamic relapsing and remitting processes in NMOSD require further exploration.

Patients and methods

Blood samples were collected from 36 patients in acute and recovery phases of NMOSD, 20 patients with other noninflammatory neurological diseases (ONND) and 20 age- and sex-matched healthy volunteers. CD4+CXCR5+PD-1+ Tfh cells were detected by flow cytometry, and serum CXCL13 levels were assessed by enzyme-linked immunosorbent assay (ELISA).

Results

The percentage of CD4+CXCR5+PD-1+ Tfh cells was significantly higher during the acute phase than during the recovery phase, and serum CXCL13 levels were significantly higher in patients in the acute and recovery phases of NMOSD than in the ONND and control groups. The Tfh cell percentage was positively correlated with CXCL13 levels, and both were positively correlated with Expanded Disability Status Scale (EDSS) scores and cerebrospinal fluid protein levels in patients with acute NMOSD.

Conclusion

Circulating Tfh cells level has the potential to be a biomarker of disease severity.

Imbalance toward TFH 1 cells playing a role in aberrant B cell differentiation in systemic sclerosis

OBJECTIVE

SSc is a connective tissue disease with multisystem disorder induced by the inflammation and fibrosis following T and B cell abnormalities. Follicular helper CD4+ T (TFH) cells play a crucial role in the formation of germinal centres and specialize in interacting to aid B cell differentiation. We aimed to investigate TFH cells and their subsets to evaluate their involvement with B cell alteration in SSc.

METHOD

Circulating TFH cells (cTFH), B cells and their subsets were assessed by flow cytometry. The concentration of serum cytokines was measured by cytokine array assay. Immunohistochemistry and IF were performed to evaluate the migration of TFH cells in SSc skin lesions.

RESULTS

The proportion of cTFH cells did not differ from controls, but their subsets were imbalanced in SSc patients. The frequency of TFH 1 was increased and correlated with ACA titre, serum IgM or CRP levels of patients, and cytokine concentrations of IL-21 and IL-6 that induce B cell differentiation in SSc. cTFH cells from SSc showed activated phenotype with expressing higher cytokine levels compared with controls. The frequency of TFH 17 was also increased, but was not correlated with a high level of Th17 cytokines in patients' sera. Furthermore, infiltration of TFH cells was found in skin lesion of SSc patients.

CONCLUSION

We here describe an imbalance of cTFH toward TFH 1 that may induce B cell alteration through IL-21 and IL-6 pathways and promote inflammation, contributing to the pathogenesis of SSc disease.

Novel Vaccine Technologies in Veterinary Medicine: A Herald to Human Medicine Vaccines

The success of inactivated and live-attenuated vaccines has enhanced livestock productivity, promoted food security, and attenuated the morbidity and mortality of several human, animal, and zoonotic diseases. However, these traditional vaccine technologies are not without fault. The efficacy of inactivated vaccines can be suboptimal with particular pathogens and safety concerns arise with live-attenuated vaccines. Additionally, the rate of emerging infectious diseases continues to increase and with that the need to quickly deploy new vaccines. Unfortunately, first generation vaccines are not conducive to such urgencies. Within the last three decades, veterinary medicine has spearheaded the advancement in novel vaccine development to circumvent several of the flaws associated with classical vaccines. These third generation vaccines, including DNA, RNA and recombinant viral-vector vaccines, induce both humoral and cellular immune response, are economically manufactured, safe to use, and can be utilized to differentiate infected from vaccinated animals. The present article offers a review of commercially available novel vaccine technologies currently utilized in companion animal, food animal, and wildlife disease control.

Human follicular helper T lymphocytes critical players in antibody responses

Follicular helper T lymphocytes are a subpopulation of CD4+ T lymphocytes initially identified in germinal centers of follicles found in secondary lymphoid organs. The primary function of follicular helper T lymphocytes is to help B lymphocytes' antibody production. Changing of antibody class and affinity, B cell differentiation and memory generation depend on cooperation between follicular helper T lymphocytes and B cells. In blood, follicular helper T lymphocytes are called circulating follicular helper T lymphocytes. They are considered to have specificities similar to those developed in the secondary lymphoid organs. The phenotype of human follicular helper T lymphocytes is given by simultaneous expression of the markers CXCR5, Bcl-6, CD40L, PD-1, and ICOS. In germinal centers, follicular helper T lymphocytes synthesize interleukin 21 as predominant cytokine. In blood, subpopulations of circulating follicular helper T lymphocytes can be recognized, with different expressions of the classical follicular helper T lymphocytes markers and, in addition, can express other markers such as CXCR3 and CCR6. Presently, there is great interest in follicular helper T lymphocytes and circulating follicular helper T lymphocytes in vaccination studies as indicators of immunization efficacy. In addition, follicular helper T lymphocytes are investigated as possible markers of activity in many diseases and potential therapeutic intervention. This short review describes aspects of immunobiology and quantification of follicular helper T lymphocytes and circulating follicular helper T lymphocytes, and presents a few examples of related findings in systemic lupus erythematosus, rheumatoid arthritis, HIV infection and vaccination.

Gingival transcriptomics of follicular T cell footprints in progressing periodontitis

Follicular helper T cells (Tfh) cells have been identified in the circulation and in tertiary lymphoid structures in chronic inflammation. Gingival tissues with periodontitis reflect chronic inflammation, so genomic footprints of Tfh cells should occur in these tissues and may differ related to aging effects. Macaca mulatta were used in a ligature-induced periodontitis model [adult group (aged 12-23 years); young group (aged 3-7 years)]. Gingival tissue and subgingival microbiome samples were obtained at matched healthy ligature-induced disease and clinical resolution sites. Microarray analysis examined Tfh genes (n = 54) related to microbiome characteristics documented using 16S MiSeq. An increase in the major transcription factor of Tfh cells, BCL6, was found with disease in both adult and young animals, while master transcription markers of other T cell subsets were either decreased or showed minimal change. Multiple Tfh-related genes, including surface receptors and transcription factors, were also significantly increased during disease. Specific microbiome patterns were significantly associated with profiles indicative of an increased presence/function of Tfh cells. Importantly, unique microbial complexes showed distinctive patterns of interaction with Tfh genes differing in health and disease and with the age of the animals. An increase in Tfh cell responsiveness occurred in the progression of periodontitis, affected by age and related to specific microbial complexes in the oral microbiome. The capacity of gingival Tfh cells to contribute to localized B cell activation and active antibody responses, including affinity maturation, may be critical for controlling periodontal lesions and contributing to limiting and/or resolving the lesions.

Central Role of T Follicular Helper Cells in Myasthenia Gravis

Myasthenia gravis (gMG) is a critical autoimmune disease, which has a serious impact on the life and survival of patients. Ocular Myasthenia Gravis (oMG) is often the initial manifestation of MG and has the potential to progress to gMG. However, to date no distinct mechanism has been found to clarify the pathogenesis of conversion from oMG to gMG. Recent studies have shown that the development and clinical progression of MG is closely associated with the abnormal function of follicular helper T (Tfh) cells. Thus, this article reviews the recently achieved research progress on the involvement of Tfh cells in MG immunopathogenesis and focuses on the role of Tfh cells and related-factors (IL-21, CXCL13, CXCR5, bcl-6 etc.) in germinal center formation and antibody production in MG immune response.

The Function of T Follicular Helper Cells in the Autoimmune Liver Diseases

T follicular helper (TFH) cells are recognized as a subtype of T cells that are involved in the germinal center formation and B cell development. When dysregulated, TFH cells may represent an important mechanism that contributes to a heightened humoral response and autoantibody production in autoimmune liver diseases (AILDs). TFH cells participate in the immune response associated with AILDs by expressing surface receptors such as programmed cell death protein-1, C-X-C motif chemokine receptor 5, and inducible T cell costimulators, as well as cytokines such as interleukin-21. TFH cells also downregulate chemokine (C-C motif) receptor 7 and promote the dysregulation of the T follicular regulatory/TFH axis. This review highlights the importance of TFH cells in AILDs.

Immunogenomic landscape of gynecologic carcinosarcoma

OBJECTIVE

Carcinosarcoma (CS) of the uterus or ovary is a rare, biphasic tumor comprising epithelial and mesenchymal elements, and exhibits more aggressive clinical features than its carcinoma counterpart. Four molecular subtypes of CS were recently established based on genomic aberration profiles (POLE, MSI, CNH, and CNL) and shown to be associated with multiple clinicopathological parameters, including patient outcomes. However, the role of the immune microenvironment in CS remains unclear. Here, we investigated the influence of the immune cells that infiltrate CS to better understand the immunological status of gynecological CS.

METHODS

Tumor immune microenvironmental analyses on CS samples were performed using immune cell profiling with RNA-seq, transcriptomic subtyping with microenvironmental genes, and T-cell receptor repertoire assay. Carcinoma and sarcoma elements from CS samples were also assessed separately.

RESULTS

Relying on estimations of tumor-infiltrating cell types from RNA-seq data, POLE and MSI (hypermutator) tumors showed an enrichment of M1 macrophages, plasma cells and CD8⁺ T cells, whereas CNH and CNL (non-hypermutator) tumors had high levels of M2 macrophages. Further subclassification by immune-related, non-cancer genes identified a fraction of tumors with distinct patient outcomes, particularly those with the CNH genomic aberration subtype. T-cell heterogeneity was independently correlated with prolonged progression-free survival. Differential analysis of carcinoma and sarcoma elements identified many shared mutations but there was little overlap in the T-cell receptor repertoire between the two elements.

CONCLUSIONS

Tumor immune microenvironmental analyses could offer potential clinical utility in the stratification of gynecological CS above classification by genomic aberration subtype alone.

Adequate tetanus but poor diphtheria and pertussis response to a Tdap booster in adolescents with juvenile systemic lupus erythematosus

BACKGROUND

Reports on vaccine responses in immunocompromised patients, such as juvenile systemic lupus erythematosus (jSLE), have shown highly variable results.

OBJECTIVE

To compare the immune response and safety after a Tdap booster in 26 jSLE patients and 26 matched healthy adolescents.Methodology: Adverse events and disease activity were evaluated. Lymphocyte immunophenotyping was performed by flow cytometry. Tetanus, diphtheria and pertussis toxin antibodies were assessed by ELISA; whole blood was stimulated with whole cell pertussis and supernatants were assessed for cytokines by xMAP.

RESULTS

Both groups showed a similar frequency of adverse events. There was no evidence of disease reactivation after Tdap booster in the jSLE cohort. Both groups showed a significant increase in antibody titers for all three antigens on D14 and D28 (p < 0.001). jSLE patients had a significantly lower increase in diphtheria titers than the control group (p = 0.007). jSLE patients had a distinct titer increase of tetanus and pertussis antibodies when compared to controls (p = 0.004 and p < 0.001, respectively). There was a lower frequency of pertussis seroconversion in the jSLE group on D14 (p = 0.009), D28 (p = 0.023), D12m (p = 0.015) and D24m (p = 0.004). Cellular immune response to Bordetella pertussis showed significantly lower levels of IFNγ (p < 0.001) and higher levels of IL10, IL12, IL21 and TNFα in jSLE patients than controls.

CONCLUSIONS

jSLE patients had good response to Tdap booster dose for the tetanus antigen, but not for diphtheria and pertussis. This vaccine was safe in relation to adverse events and absence of disease reactivation.

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.

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.

Regulatory Effect of Sishen Pill on Tfh Cells in Mice With Experimental Colitis

The T follicular helper T (Tfh) cells play a significant role in the pathogenesis of inflammatory bowel disease (IBD), which is regulated by the Bcl-6/Blimp-1 pathway. Some studies have suggested that regulating activation of the Bcl-6/Blimp-1 pathway should be an effective method to treat IBD. Sishen Pill (SSP) has been used frequently to treat chronic colitis. Its mechanism is related to the downstream proteins in the Bcl-6/Blimp-1 pathway. However, it is unknown whether SSP regulates the function and differentiation of Tfh cells to treat IBD. In the present study, chronic colitis was induced by dextran sodium sulfate and treated with SSP for 7 days. SSP effectively treated chronic colitis, regulated the balance between Tfh10, Tfh17 and T follicular regulatory cells, while SSP increased the Blimp-1 level, inhibited expressions of Bcl-6, T-cell costimulator, programmed death (PD)-1 and PD-ligand 1 on the surface of Tfh cells. SSP inhibited activation of BcL-6, phosphorylated signal transducer and activator of transcription (p-STAT)3, signal lymphocyte activation molecule (SLAM)-associated protein but improved Blimp-1 and STAT3 expression in colonic tissues. The results indicated that SSP regulated the differentiation and function of Tfh cells to treat IBD, which was potentially related with inhibiting the Bcl-6/Blimp-1 pathway.

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

Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting the colon and rectum, in which the abnormality of B cells is involved in both its pathogenesis and progression. Follicular helper T cells (TFH) play an important role in assisting the immune function of human B cells in germinal centers, and follicular regulatory T cells (TFR) have the function of inhibiting TFH and germinal center B cell responses. The significance of circulating TFH and TFR in ulcerative colitis (UC) remains unclear. We analyzed peripheral blood of active and stable remission UC patients and found that circulating TFR was significantly decreased while TFH was increased in active UC patients. As to TFH subsets, TFH2 was elevated while TFH17 was decreased in active UC, with IL-4/IL-17A secretion enhanced. Helios⁺ and CD45RA⁻FoxP3^high TFR cells were decreased while CD226⁺ and CD45RA⁺FoxP3^int TFR cells were increased in active UC patients. The levels of new memory B cells, plasmablasts and serum IgG were significantly increased in active UC patients, and were positively correlated with TFH and TFH2, and negatively correlated with TFR. Serum CRP and Mayo Clinic scores were positively correlated with TFH and TFH2 but negatively correlated with TFR. Serum IL-12 and IL-21 were up-regulated while IL-10 was down-regulated in active UC. To conclude, an imbalance of circulating TFH and TFR cells is associated with disease activity in UC patients. Our results suggest a new mechanism for TFH and TFR imbalance in the pathogenesis of UC, providing a new perspective for theoretical research and therapeutic strategies for UC.

Exploring the imbalance of circulating follicular helper CD4+ T cells in sarcoidosis patients

BACKGROUND

Sarcoidosis is a systemic granulomatous disease characterized by the combination of Th1 and Th17 responses. Recently, several arguments have suggested a potential involvement of B cells as well as T cells in the pathogenesis of sarcoidosis. Follicular helper CD4⁺ T (T_FH) cells are specialized in interacting with and helping B cells, and play a crucial role in the formation of germinal centers.

OBJECTIVE

We sought to explore the status of T_FH cells and investigate their possible pathogenic role in sarcoidosis.

METHODS

T_FH cells and B cells in peripheral blood were examined by flow cytometry, and serum samples were studied by cytokine arrays. Immunohistochemistry was performed to check for the presence of T_FH cells in sarcoidosis skin lesions. Gene expression in isolated T_FH cells was analyzed by quantitative RT-PCR.

RESULTS

The proportion of circulating T_FH cells was decreased. CD4⁺CXCR5⁺ T_FH cells were observed in cutaneous lesions in sarcoidosis. Gene expression in circulating T_FH cells and serum cytokine concentrations related to Th17 were increased in sarcoidosis patients. Gene expressions of B cell differentiation cytokines in T_FH cells were not altered in sarcoidosis patients.

CONCLUSION

We herein describe a decrease of circulating T_FH cells and their migration to affected tissues. Circulating T_FH cells are one of the potential cell types capable of producing IL-17 and enhancing Th17 responses, and may promote the chronic inflammation. We could not demonstrate a direct linkage between the imbalance of T_FH cells and abnormal B cell differentiation in sarcoidosis.

Characterization of lymphocyte subsets in peripheral blood cells of children with EV71 infection

BACKGROUND

Enterovirus 71 (EV71) is one of the major causative pathogens of hand, foot, and mouth disease (HFMD). Immune cells play a critical role in determining the outcomes of virus infection. We aimed to characterize the lymphocyte subsets and transcriptional levels of T lymphocytes-associated transcription factors in peripheral blood cells of children with EV71 infection.

METHODS

Peripheral blood samples from 32 children with EV71 infection and 32 control subjects were included in this study. The frequencies of T-, B-lymphocytes, and their subsets were determined by flow cytometry. The expression of transcription factors, including T-bet, Gata3, ROR γ t, Foxp3, TCF-1, and BCL-6 in the whole blood cells were evaluated by real-time reverse-transcription quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The frequencies of T cells, helper T cells (Th), cytotoxic T cells (Tc), IFN-γ⁺ Th1, IFN-γ⁺ Tc1, and regulatory T (Treg) cells were significantly decreased (P < 0.01) in children with EV71 infection. As for IL-4⁺ Th2, IL-4⁺ Tc2, IL-17⁺ Th17, IL-17⁺ Tc17, follicular helper T cells (Tfh), CD3⁺CD8⁺IL-21⁺ T cells, CD19⁺ B cells, and CD19⁺IL-10⁺ B10 cells, their frequencies were significantly increased in the EV71 group (P < 0.01). The EV71 group had lower mRNA expressions of T-bet, Gata3, and Foxp3 than the control group (P < 0.05), whereas the expressions of ROR γ t, TCF-1, and BCL-6 showed no significant difference between two groups.

CONCLUSIONS

EV71 infection in children caused a decreased frequency of total Th, Tc and Treg cells, and increased percentages of B cell, Th2 and Th17 cells in blood.

C5aR1 regulates T follicular helper differentiation and chronic graft-versus-host disease bronchiolitis obliterans

CD4+ follicular helper T (Tfh) cells are specialized providers of T cell help to B cells and can function as pathogenic mediators of murine antibody-dependent chronic graft-versus-host disease (GvHD). Using a parent→F1 model of lupus-like chronic GvHD, in which Tfh cell and germinal center (GC) B cell differentiation occurs over 14 days, we demonstrate that absence of CD4+ T cell-expressed C5a receptor 1 (C5ar1) or pharmacological C5aR1 blockade abrogated generation/expansion of Tfh cells, GC B cells, and autoantibodies. In a Tfh cell-dependent model of chronic GvHD manifested by bronchiolitis obliterans syndrome (BOS), C5aR1 antagonism initiated in mice with established disease ameliorated BOS and abolished the associated differentiation of Tfh and GC B cells. Guided by RNA-sequencing data, mechanistic studies performed using murine and human T cells showed that C5aR1 signaling amplifies IL-6-dependent expression of the transcription factor c-MAF and the cytokine IL-21 via phosphorylating phosphokinase B (AKT) and activating the mammalian target of rapamycin (mTOR). In addition to linking C5aR1-initiated signaling to Tfh cell differentiation, our findings suggest that C5aR1 may be a useful therapeutic target for prevention and/or treatment of individuals with Tfh cell-dependent diseases, including those chronic GvHD patients who have anti-host reactive antibodies.

Aberrant Expansion and Function of Follicular Helper T Cell Subsets in IgG4-Related Disease

Objective

To determine the number and function of follicular helper T (Tfh) cell subsets in IgG4‐related disease (IgG4‐RD).

Methods

Mononuclear cells from the peripheral blood and involved tissue of patients with IgG4‐RD were assessed for Tfh cells and their subsets, and levels of B cell lymphoma 6 (Bcl‐6), B lymphocyte–induced maturation protein 1 (BLIMP‐1), and interleukin‐21 (IL‐21) messenger RNA (mRNA). Immunohistochemical and immunofluorescence techniques were used to assess the involved tissue of patients to determine the location of IL‐21, Bcl‐6, and CD4+CXCR5+ Tfh cells. Furthermore, the ability of circulating Tfh (cTfh) cell subsets to induce B cell proliferation, apoptosis, and differentiation and to produce IgG4 was explored in cell cocultures in vitro.

Results

Frequencies of cTfh cells were significantly increased in the peripheral blood of patients with IgG4‐RD, and even higher frequencies were observed in the involved tissue. Percentages of programmed cell death protein 1 in CD4+CXCR5+ICOS+ cTfh cells were positively correlated with the serum levels of IgG and IgG4, IgG4:IgG ratio, number of involved organs, and frequency of CD19+CD24−CD38^high plasmablasts/plasma cells. Levels of BLIMP‐1 and IL‐21 mRNA in peripheral CD4+ T cells were increased in patients with IgG4‐RD compared to healthy controls, and this was correlated with the levels of serum IgG4. Moreover, in the involved tissue, Bcl‐6, IL‐21, and Tfh cells were highly expressed. Compared to cTfh cells from healthy controls, cTfh cells from patients with IgG4‐RD could facilitate B cell proliferation and inhibit B cell apoptosis more efficiently, and enhanced the differentiation of naive B cells into switched memory B cells and plasmablasts/plasma cells, with a resultant increase in the secretion of IgG4. Notably, the cTfh1 and cTfh2 cell subsets were the most effective at providing B cell help.

Conclusion

Tfh cell subsets are expanded in IgG4‐RD and may play pivotal roles in the pathogenesis of the disease.

B Lymphocyte Chemoattractant (CXCL13) Is an Indicator of Acute Gastrointestinal GVHD in Murine Model

Gastrointestinal acute graft-vs.-host disease (GI aGVHD) remains a significant obstacle to the success of allogeneic hematopoietic cell transplantation and is a major cause of morbidity and mortality. In addition, GI aGVHD is often clinically indistinguishable from other causes of GI dysfunction such as conditioning regimen toxicity, infections, or medications, which complicates the diagnosis. Thus, specific biomarkers are needed to help improve diagnosis and obtain a deeper understanding of the cytokine changes in GI aGVHD. An MHC-mismatched model of aGVHD was established by transplanting 1 × 10⁷ bone marrow nuclear cells and 3 × 10⁷ spleen cells from C57/Bl6 mice or from BALB/c mice into lethally irradiated BALB/c recipients. The mice in the allogeneic transplantation group were intraperitoneally treated with 20 mg kg^-1 day^-1 cyclosporin A after aGVHD developed. Five micrograms of lipopolysaccharide were administered intraperitoneally daily to syngeneic recipients at day 11 to imitate infection; the same volume of phosphate-buffered saline was administered to control mice. The mice were killed at the indicated time points. Forty molecules derived from the GI tract were screened cytokine array. The data demonstrated that the expression of B lymphocyte chemoattractant (CXCL13) was increased by ~10-, 12-, and 16-fold upon the occurrence of aGVHD compared with infection, aGVHD after treatment, and the syngeneic control group, respectively. Thus, the elevation of BLC (CXCL13) is an indicator of acute GI GVHD.

Insights Into the Molecular Mechanisms of T Follicular Helper-Mediated Immunity and Pathology

T follicular helper (Tfh) cells play key role in providing help to B cells during germinal center (GC) reactions. Generation of protective antibodies against various infections is an important aspect of Tfh-mediated immune responses and the dysregulation of Tfh cell responses has been implicated in various autoimmune disorders, inflammation, and malignancy. Thus, their differentiation and maintenance must be closely regulated to ensure appropriate help to B cells. The generation and function of Tfh cells is regulated by multiple checkpoints including their early priming stage in T zones and throughout the effector stage of differentiation in GCs. Signaling pathways activated downstream of cytokine and costimulatory receptors as well as consequent activation of subset-specific transcriptional factors are essential steps for Tfh cell generation. Thus, understanding the mechanisms underlying Tfh cell-mediated immunity and pathology will bring into spotlight potential targets for novel therapies. In this review, we discuss the recent findings related to the molecular mechanisms of Tfh cell differentiation and their role in normal immune responses and antibody-mediated diseases.

Dimethyl fumarate therapy suppresses B cell responses and follicular helper T cells in relapsing-remitting multiple sclerosis

Background:

Dimethyl fumarate (DMF) is a disease-modifying therapy used for patients with relapsing-remitting multiple sclerosis (RRMS). B cells are important contributors to the pathogenesis of RRMS, where they regulate the inflammatory immune responses and participate in development of lesions in the central nervous system (CNS). The impact of DMF on B cell subpopulations remains incompletely understood.

Objectives:

In this study, we evaluated the effects of DMF on B cell subpopulations and their effector functions.

Methods:

Blood from 21 DMF-treated and 18 untreated patients with RRMS was analyzed by flow cytometry.

Results:

We found that DMF reduces the frequency of circulating antigen–experienced B cells, a reduction likely related to a reduced frequency of follicular helper T (TFH) cells and an increased frequency of follicular regulatory T (TFR) cells. Studying the impact of monomethyl fumarate (MMF), the primary metabolite of DMF, on B cell effector function in vitro showed that MMF increased the frequency of transforming growth factor (TGF)-β-producing B cells and decreased the frequency of B cells secreting lymphotoxin (LT)-α, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and to a lesser extent IL-10.

Conclusion:

In summary, these data suggest an anti-inflammatory role of DMF and its metabolite MMF on the B cell compartment.

Correlates of Protection Against SIVmac251 Infection in Rhesus Macaques Immunized With Chimpanzee-Derived Adenovirus Vectors

We report on prime-boost vaccine regimens with two simian adenovirus (Ad) vectors (SAdV) or two human serotype Ad vectors (HAdV) expressing Gag and gp160 of simian immunodeficiency virus (SIV)mac239 tested in HAdV-seropositive rhesus macaques (RMs) repeatedly challenged rectally with low doses of SIVmac251. Both vaccine regimens reduced set point and peak viral loads (PVL) and accelerated viral clearance. In SAdV-vaccinated controller genotype RMs resistance against infection correlated with levels of envelope (Env)-specific antibody (Ab) titers. In both vaccine groups CD8+T cells controlled viral loads (VL) upon infection. Circulating CD4+ and CD8+ T cells showed significant changes in their transcriptome over time following vaccination, which differed between the vaccine groups. T cells from SIV-resistant RMs had unique transcriptional profiles indicating that both follicular T helper (TFH) cell responses and highly activated CD8+ T cells may play a role in protection.

Altered Ratio of T Follicular Helper Cells to T Follicular Regulatory Cells Correlates with Autoreactive Antibody Response in Simian Immunodeficiency Virus-Infected Rhesus Macaques

Individuals with chronic HIV-1 infection have an increased prevalence of autoreactive Abs. Many of the isolated HIV broadly neutralizing Abs from these individuals are also autoreactive. However, the underlying mechanism(s) that produce these autoreactive broadly neutralizing Abs remains largely unknown. The highly regulated coordination among B cells, T follicular helper (T_FH) cells, and T follicular regulatory (T_FR) cells in germinal centers (GCs) of peripheral lymphatic tissues (LTs) is essential for defense against pathogens while also restricting autoreactive responses. We hypothesized that an altered ratio of T_FH/T_FR cells in the GC contributes to the increased prevalence of autoreactive Abs in chronic HIV infection. We tested this hypothesis using a rhesus macaque (RM) SIV model. We measured the frequency of T_FH cells, T_FR cells, and GC B cells in LTs and anti-dsDNA and anti-phospholipid Abs from Indian RMs, with and without SIV infection. We found that the frequency of anti-dsDNA and anti-phospholipid Abs was much higher in chronically infected RMs (83.3% [5/6] and 66.7% [4/6]) than in acutely infected RMs (33.3% [2/6] and 18.6% [1/6]) and uninfected RMs (0% [0/6] and 18.6% [1/6]). The increased ratio of T_FH/T_FR cells in SIV infection correlated with anti-dsDNA and anti-phospholipid autoreactive Ab levels, whereas the frequency of T_FR cells alone did not correlate with the levels of autoreactive Abs. Our results provide direct evidence that the ratio of T_FH/T_FR cells in LTs is critical for regulating autoreactive Ab production in chronic SIV infection and possibly, by extension, in chronic HIV-1 infection.

Gender Bias in Human Systemic Lupus Erythematosus: A Problem of Steroid Receptor Action?

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease resulting from abnormal interactions between T and B cells. The acquisition of SLE is linked to genetic susceptibility, and diverse environmental agents can trigger disease onset in genetically susceptible individuals. However, the strongest risk factor for developing SLE is being female (9:1 female to male ratio). The female sex steroid, estradiol, working through its receptors, contributes to the gender bias in SLE although the mechanisms remain enigmatic. In a small clinical trial, monthly administration of the estrogen receptor (ERα) antagonist, ICI182,780 (fulvestrant), significantly reduced disease indicators in SLE patients. In order to identify changes that could account for improved disease status, the present study utilized fulvestrant (Faslodex) to block ERα action in cultured SLE T cells that were purified from blood samples collected from SLE patients (n = 18, median age 42 years) and healthy control females (n = 25, median age 46 years). The effects of ERα antagonism on estradiol-dependent gene expression and canonical signaling pathways were analyzed. Pathways that were significantly altered by addition of Faslodex included T helper (Th) cell differentiation, steroid receptor signaling [glucocorticoid receptor (GR), ESR1 (ERα)], ubiquitination, and sumoylation pathways. ERα protein expression was significantly lower (p < 0.018) in freshly isolated, resting SLE T cells suggesting ERα turnover is inherently faster in SLE T cells. In contrast, ERα/ERβ mRNA and ERβ protein levels were not significantly different between SLE and normal control T cell samples. Plasma estradiol levels did not differ (p > 0.05) between SLE patients and controls. A previously undetected interaction between GR and ERα signaling pathways suggests posttranslational modification of steroid receptors in SLE T cells may alter ERα/GR actions and contribute to the strong gender bias of this autoimmune disorder.

An optimized HMGB1 expressed by recombinant rabies virus enhances immunogenicity through activation of dendritic cells in mice

Rabies remains an important public health threat, killing approximately 59,000 people worldwide annually, most of which are from the developing countries of Africa and Asia where dog rabies are endemic. Therefore, developing an affordable and efficacious vaccine for dog-mediated rabies control is needful in these countries. Our previous studies indicated that over-expression of granulocyte-macrophage colony stimulating factor (GM-CSF) or macrophage inflammatory protein-1 (MIP-1α or CCL3) by recombinant rabies virus (rRABV) could enhance the immunogenicity by activating dendritic cells (DCs). In this study, to further characterize the role of activating DCs in RABV immunogenicity, High mobility group box 1 (HMGB1), a highly conserved and non-histone chromosomal protein that can promote DCs maturation and activation, were investigated. The wild-type HMGB1 (HMGB1wt) and an optimized HMGB1 (HMGB1mut) were individually inserted into the genome of the rRABV strain LBNSE (designated as LBNSE-HMGB1wt and LBNSE-HMGB1mut, respectively), and the effect of over-expression of HMGB1 on the immunogenicity of RABV was investigated. The results demonstrated that LBNSE-HMGB1mut could promote significantly more DCs activation, and the recruitment of follicular helper T, germinal center B and plasma cells in vaccinated mice than those immunized with LBNSE-HMGB1wt or parent virus LBNSE. Further investigations suggested that mice vaccinated with LBNSE-HMGB1mut produced significantly higher level of RABV-neutralizing antibodies and offered a better protection than those vaccinated with LBNSE or LBNSE-HMGB1wt. Taken together, these data provides a better understanding of the mechanism for HMGB1 as a potential adjuvant in enhancing the immunogenicity of RABV, which would contribute to developing more-efficacious rabies vaccines.

Bioconjugation Approaches to Producing Subunit Vaccines Composed of Protein or Peptide Antigens and Covalently Attached Toll-Like Receptor Ligands

Traditional vaccines derived from attenuated or inactivated pathogens are effective at inducing antibody-based protective immune responses but tend to be highly reactogenic, causing notable adverse effects. Vaccines with superior safety profiles can be produced by subunit approaches, utilizing molecularly defined antigens (e.g., proteins and polysaccharides). These antigens, however, often elicit poor immunological responses, necessitating the use of adjuvants. Immunostimulatory adjuvants have the capacity to activate antigen presenting cells directly through specific receptors (e.g., Toll-like receptors (TLRs)), resulting in enhanced presentation of antigens as well as the secretion of proinflammatory chemokines and cytokines. Consequently, innate immune responses are amplified and adaptive immunity is generated. Recently, site-specific conjugation of such immunostimulatory adjuvants (e.g., TLR ligands) onto defined antigens has shown superior efficacy over unconjugated mixtures, suggesting that the development of chemically characterized immunostimulatory adjuvants and optimized approaches for their conjugation with antigens may provide a better opportunity for the development of potent, novel vaccines. This review briefly summarizes various TLR agonists utilized as immunostimulatory adjuvants and focuses on the development of techniques (e.g., recombinant, synthetic, and semisynthetic) for generating adjuvant-antigen fusion vaccines incorporating peptide or protein antigens.

Human neonatal thymectomy induces altered B-cell responses and autoreactivity

An association between T‐cell lymphopenia and autoimmunity has long been proposed, but it remains to be elucidated whether T‐cell lymphopenia affects B‐cell responses to autoantigens. Human neonatal thymectomy (Tx) results in a decrease in T‐cell numbers and we used this model to study the development of autoreactivity. Two cohorts of neonatally thymectomized individuals were examined, a cohort of young (1–5 years post‐Tx, n = 10–27) and older children (>10 years, n = 26), and compared to healthy age‐matched controls. T‐cell and B‐cell subsets were assessed and autoantibody profiling performed. Early post‐Tx, a decrease in T‐cell numbers (2.75 × 10⁹/L vs. 0.71 × 10⁹/L) and an increased proportion of memory T cells (19.72 vs. 57.43%) were observed. The presence of autoantibodies was correlated with an increased proportion of memory T cells in thymectomized children. No differences were seen in percentages of different B‐cell subsets between the groups. The autoantigen microarray showed a skewed autoantibody response after Tx. In the cohort of older individuals, autoantibodies were present in 62% of the thymectomized children, while they were found in only 33% of the healthy controls. Overall, our data suggest that neonatal Tx skews the autoantibody profile. Preferential expansion and preservation of Treg (regulatory T) cell stability and function, may contribute to preventing autoimmune disease development after Tx.

Minimal hepatic encephalopathy is associated with expansion and activation of CD4+CD28-, Th22 and Tfh and B lymphocytes

Peripheral inflammation acts synergistically with hyperammonemia in inducing neurological alterations in cirrhotic patients with minimal hepatic encephalopathy (MHE). We hypothesized that appearance of MHE would be associated to some specific qualitative change in peripheral inflammation. The aim of this work was to characterize the changes in peripheral inflammation associated to appearance of MHE. We analyzed it by immunophenotyping and cytokine profile analysis, in cirrhotic patients without or with MHE and controls. The main alterations associated specifically with MHE are: 1) increased activation of all subtypes of CD4⁺ T-lymphocytes, with the increased expression of CD69; 2) increased amount of CD4⁺CD28⁻ T lymphocytes, associated with increased levels of CX3CL1 and of IL-15; 3) increased differentiation of CD4⁺ T lymphocytes to Th follicular and Th22; 4) increased activation of B lymphocytes and serum IgG. This study has identified some specific alterations of the immune system associated with appearance of the neurological alterations in MHE patients.

A Novel Rabies Vaccine Expressing CXCL13 Enhances Humoral Immunity by Recruiting both T Follicular Helper and Germinal Center B Cells

Rabies remains a public health threat in most parts of the world, and approximately 99% of the cases are transmitted by dogs. There is an urgent need to develop an efficacious and affordable vaccine to control canine-transmitted rabies in developing countries. Our previous studies demonstrate that overexpression of chemokines/cytokines such as CCL-3 (MIP-1α) and granulocyte-macrophage colony-stimulating factor (GM-CSF) can enhance the immunogenicity of rabies vaccines. In the present study, the chemokine CXCL13 was inserted into the genome of the recombinant rabies virus (rRABV) strain LBNSE, and the effect of the chemokine CXCL13 on the immunogenicity of RABV was investigated. It was found that LBNSE-CXCL13 recruited follicular helper T (Tfh) and germinal center (GC) B cells, promoted the formation of GCs, and increased the population of plasma cells in immunized mice. Further studies showed that mice immunized with LBNSE-CXCL13 produced more rabies virus-neutralizing antibodies (VNAs) and developed better protection than those immunized with the parent virus LBNSE or the GM-CSF-expressing RABV (LBNSE-GM-CSF). Collectively, these findings provide a better understanding of the role of CXCL13 expression in the immunogenicity of the RABV, which may help in designing more-efficacious rabies vaccines.

IMPORTANCE

Rabies is endemic in most parts of the world, and more effort is needed to develop affordable and effective vaccines to control or eliminate this disease. The chemokine CXCL13 recruits both Tfh and B cells, which is essential for the homing of Tfh cells and the development of B cell follicles. In this study, the effect of the overexpression of CXCL13 on the immunogenicity of the RABV was evaluated in a mouse model. We found that CXCL13 expression promoted humoral immunity by recruiting Tfh and GC B cells, facilitating the formation of GCs, and increasing the number of plasma cells. As expected, the overexpression of CXCL13 resulted in enhanced virus-neutralizing antibody (VNA) production and protection against a virulent RABV challenge. These findings provide a better understanding of the role of CXCL13 in RABV-induced immune responses, which will help in designing more efficacious rabies vaccines.

How pregnancy can affect autoimmune diseases progression?

Autoimmune disorders are characterized by tissue damage, caused by self-reactivity of different effectors mechanisms of the immune system, namely antibodies and T cells. Their occurrence may be associated with genetic and/or environmental predisposition and to some extent, have implications for fertility and obstetrics. The relationship between autoimmunity and reproduction is bidirectional. This review only addresses the impact of pregnancy on autoimmune diseases and not the influence of autoimmunity on pregnancy development. Th17/Th1-type cells are aggressive and pathogenic in many autoimmune disorders and inflammatory diseases. The immunology of pregnancy underlies the role of Th2-type cytokines to maintain the tolerance of the mother towards the fetal semi-allograft. Non-specific factors, including hormonal changes, favor a switch to Th2-type cytokine profile. In pregnancy Th2, Th17/Th2 and Treg cells accumulate in the decidua but may also be present in the mother’s circulation and can regulate autoimmune responses influencing the progression of autoimmune diseases.

Differences in Tfh Cell Response Between the Graft and Spleen With Chronic Allograft Nephropathy

The aim of this study was to investigate follicular helper T (Tfh) cell response and its difference between renal graft and spleen in a rat renal transplantation model undergoing chronic allograft nephropathy (CAN). Orthotopical kidney transplantations were performed on Fischer (F344) rats and transplanted to Lewis rats, using syngeneic Lewis-Lewis grafts as controls. Tissue samples were collected at 8 weeks posttransplantation. The status of Tfh cell response was assessed by measuring the levels of transcription factor B-cell lymphoma 6 (Bcl-6), interleukin-21 (IL-21), chemokine receptor type 5 (CXCR5), and B-cell-activating factor belonging to the TNF family (BAFF). Tfh cell response was upregulated in both renal graft and spleen of the CAN group compared to the control group. However, Tfh cell response of the spleen was weaker than that of the graft, which was possibly related to the upregulation of splenic Treg activation. Also, the difference between two tissues was partially associated with the different expressions of tristetraprolin (TTP)/IL-10. Our data help improve our understanding of the role of Tfh cell response in the body with CAN and may provide a valuable clue for better treatment of CAN.

Immune-inflammatory responses in atherosclerosis: Role of an adaptive immunity mainly driven by T and B cells

Adaptive immune response plays an important role in atherogenesis. In atherosclerosis, the proinflammatory immune response driven by Th1 is predominant but the anti-inflammatory response mediated mainly by regulatory T cells is also present. The role of Th2 and Th17 cells in atherogenesis is still debated. In the plaque, other T helper cells can be observed such as Th9 and Th22 but is little is known about their impact in atherosclerosis. Heterogeneity of CD4(+) T cell subsets presented in the plaque may suggest for plasticity of T cell that can switch the phenotype dependening on the local microenvironment and activating/blocking stimuli. Effector T cells are able to recognize self-antigens released by necrotic and apoptotic vascular cells and induce a humoral immune reaction. Tth cells resided in the germinal centers help B cells to switch the antibody class to the production of high-affinity antibodies. Humoral immunity is mediated by B cells that release antigen-specific antibodies. A variety of B cell subsets were found in human and murine atherosclerotic plaques. In mice, B1 cells could spontaneously produce atheroprotective natural IgM antibodies. Conventional B2 lymphocytes secrete either proatherogenic IgG, IgA, and IgE or atheroprotective IgG and IgM antibodies reactive with oxidation-specific epitopes on atherosclerosis-associated antigens. A small population of innate response activator (IRA) B cells, which is phenotypically intermediate between B1 and B2 cells, produces IgM but possesses proatherosclerotic properties. Finally, there is a minor subset of splenic regulatory B cells (Bregs) that protect against atherosclerotic inflammation through support of generation of Tregs and production of anti-inflammatory cytokines IL-10 and TGF-β and proapoptotic molecules.