Circulating T follicular helper cell and regulatory T cell frequencies are influenced by B cell depletion in patients with granulomatosis with polyangiitis

Role of T follicular helper cells in autoimmune rheumatic Diseases: A systematic review on immunopathogenesis and response to treatment

BACKGROUND

T follicular helper (Tfh) cells are a subdivision of T helper cells involved in antigen-specific B cell immunity. Tfh cells play an essential role in the interaction of T cells/B cells in the germinal centers (GC), and dysregulation of Tfh actions can offer pathogenic autoantibody formation and lead to the development of autoimmune diseases. This study seeks to evaluate changes in Tfh frequency and its related cytokines in autoimmune disease, its association with disease phase, severity, prognosis, and the effect of immunosuppressive treatment on the Tfh population.

METHOD

The study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Statement. Electronic databases, including PubMed, Scopus, Web of Science, and Embase, were systematically searched for potentially eligible studies up to January 1, 2024.

RESULTS

We identified 4998 articles in the initial search, from which 1686 similar titles were removed. A total of 3312 articles were initially screened, and 3051 articles were excluded by title/abstract screening. A total of 261 studies were considered for full-text assessment, and 205 articles were excluded by reason. Finally, a total of 56 studies were included in our review.

CONCLUSION

The population of Tfh cells is generally higher in autoimmune diseases versus Health control. Moreover, the number of Tfh cells is associated with the disease severity and can be considered for determining the prognosis of studies. Also, peripheral blood circulating Tfh (cTfh) cells are an available sample that can be used as an indicator for diagnosing diseases.

Normalized circulating Tfh and Th17 associates with improvement in myasthenia gravis treated with ofatumumab

Objective

To assess the effect of B cell depletion therapy (BCDT) on circulating T follicular helper (cTfh) and circulating T helper 17 (cTh17) cells and its relation to clinical improvement in patients with myasthenia gravis (MG).

Methods

28 anti-AchR positive MG patients treated with ofatumumab and 28 healthy controls (HCs) were included. Frequencies of cTfh and cTh17 cells were monitored by flow cytometry at baseline and 4, and 12 weeks after the initial dose ofatumumab. Serum cytokines associated with cTfh and cTh17, including IL-6, IL-21, and IL-17, were also analyzed.

Results

The frequency of cTfh and cTh17 significantly increased in MG patients compared with HCs. Additionally, elevated levels of both T-cell subsets correlated with MG severity. During the follow-up, cTfh and cTh17 return to normal after BCDT. Furthermore, the decrease in cTfh and cTh17 was associated with MG scores improvement over time. Notably, cTfh- and cTh17-related cytokines, including IL-6, IL-21, and IL-17, exhibited a marked decrease following ofatumumab therapy.

Conclusions

Abnormal expansion of cTfh and cTh17 cells may be key features in the immunopathology of MG. Their levels returned to normal after BCDT, which was closely correlated with clinical amelioration. This result suggests that these two T-cell subsets may be targets for BCDT treatment of MG.

Longitudinal monitoring of circulating immune cell phenotypes in anti-neutrophil cytoplasmic antibody-associated vasculitis

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) is a necrotizing multiorgan autoimmune disease that affects small- to medium-sized blood vessels. Despite the improvements in treatments, half of the patients with AAV still experience disease relapses. In this review, we focus on peripheral leukocyte properties and phenotypes in patients with AAV. In particular, we explore longitudinal changes in circulating immune cell phenotypes during the active phase of the disease and treatment. The numbers and phenotypes of leukocytes in peripheral blood were differs between AAV and healthy controls, AAV in active versus inactive phase, AAV in treatment responders versus non-responders, and AAV with and without severe infection. Therefore, biomarkers detected in peripheral blood immune cells may be useful for longitudinal monitoring of disease activity in AAV.

T follicular helper cells and T follicular regulatory cells in autoimmune diseases

T follicular helper (Tfh) cells are heterogeneous and mainly characterized by expressing surface markers CXCR5, ICOS, and PD-1; cytokine IL-21; and transcription factor Bcl6. They are crucial for B-cell differentiation into long-lived plasma cells and high-affinity antibody production. T follicular regulatory (Tfr) cells were described to express markers of conventional T regulatory (Treg) cells and Tfh cells and were able to suppress Tfh-cell and B-cell responses. Evidence has revealed that the dysregulation of Tfh and Tfr cells is positively associated with the pathogenic processes of autoimmune diseases. Herein, we briefly introduce the phenotype, differentiation, and function of Tfh and Tfr cells, and review their potential roles in autoimmune diseases. In addition, we discuss perspectives to develop novel therapies targeting Tfh/Tfr balance.

Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

Defective STAT5 Activation and Aberrant Expression of BCL6 in Naive CD4 T Cells Enhances Follicular Th Cell-like Differentiation in Patients with Granulomatosis with Polyangiitis

Granulomatosis with polyangiitis (GPA) is a potentially fatal small vessel vasculitis of unknown etiology, characterized by anti-neutrophil cytoplasmic autoantibodies, chronic inflammation, and granulomatous tissue damage. T cell dysregulation, comprising decreased regulatory T cell function and increased circulating effector memory follicular Th cells (TFH), is strongly associated with disease pathogenesis, but the mechanisms driving these observations are unknown. We undertook transcriptomic and functional analysis of naive CD4 T cells from patients with GPA to identify underlying functional defects that could manifest in the pathogenic profiles observed in GPA. Gene expression studies revealed a dysregulation of the IL-2 receptor β/JAK-STAT signaling pathway and higher expression of BCL6 and BCL6-regulated genes in GPA naive CD4 T cells. IL-2-induced STAT5 activation in GPA naive CD4 T cells was decreased, whereas STAT3 activation by IL-6 and IL-2 was unperturbed. Consistently, BCL6 expression was sustained following T cell activation of GPA naive CD4 T cells and in vitro TFH differentiation of these cells resulted in significant increases in the production TFH-related cytokines IL-21 and IL-6. Thus, naive CD4 T cells are dysregulated in patients with GPA, resulting from an imbalance in signaling equilibrium and transcriptional changes that drives the skewed pathogenic CD4 effector immune response in GPA.

A glance into the future of anti-neutrophil cytoplasmic antibody-associated vasculitis

In the past decade, unprecedented progress has been made in understanding the pathogenesis, diagnosis, assessment, and treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs). International collaborations and input from several fields (e.g. immunology, rheumatology, and nephrology) have been critical for analyzing demographics, disease manifestations, and outcomes in clinical research studies. Such efforts opened new avenues for generating novel questions and rationale to design better clinical trials. In addition, clinical research has been a source of several biological discoveries and the starting point for knowledge seeking on the pathophysiology of AAV. Interestingly, the blending of clinical and basic research provides a platform for personalized medicine. Despite recent revisions on AAV classification, the incorporation of new findings on disease genetics and immunologic responses may soon result in changes in clinical practice. These advances will enhance the selection of more specific and targeted therapies. However, current unmet needs in the management of AAV are still sizable and heavily impact long-term survival. Especially, frequent relapses, damage accrual, and high morbidity contribute to poor outcomes. Finally, the lack of defined biomarkers for disease activity and the prognosis is a permanent challenge in AAV research. Our work provides an overview of the current state of the art in AAV literature and suggests bridges for the remaining knowledge gaps. It offers potential future directions for the clinical assessment, management, and research in the field toward a more personalized medicine approach.

B- and Plasma Cell Subsets in Autoimmune Diseases: Translational Perspectives

B lymphocytes play a central role in immunity owing to their unique antibody-producing capacity that provides protection against certain infections and during vaccination. In autoimmune diseases, B cells can gain pathogenic relevance through autoantibody production, antigen presentation, and proinflammatory cytokine secretion. Recent data indicate that B and plasma cells can function as regulators through the production of immunoregulatory cytokines and/or employing checkpoint molecules. In this study, we review the key findings that define subsets of B and plasma cells with pathogenic and protective functions in autoimmunity. In addition to harsh B-cell depletion, we discuss the strategies that have the potential to reinstall the balance of pathogenic and protective B cells with the potential of more specific and personalized therapies.

Circulating autoreactive proteinase 3+ B cells and tolerance checkpoints in ANCA-associated vasculitis

BACKGROUND

Little is known about the autoreactive B cells in antineutrophil cytoplasmic antibody–associated (ANCA-associated) vasculitis (AAV). We aimed to investigate tolerance checkpoints of circulating antigen-specific proteinase 3–reactive (PR3⁺) B cells.

METHODS

Multicolor flow cytometry in combination with bioinformatics and functional in vitro studies were performed on baseline samples of PBMCs from 154 well-characterized participants of the RAVE trial (NCT00104299) with severely active PR3-AAV and myeloperoxidase-AAV (MPO-AAV) and 27 healthy controls (HCs). Clinical data and outcomes from the trial were correlated with PR3⁺ B cells (total and subsets).

RESULTS

The frequency of PR3⁺ B cells among circulating B cells was higher in participants with PR3-AAV (4.77% median [IQR, 3.98%–6.01%]) than in participants with MPO-AAV (3.16% median [IQR, 2.51%–5.22%]) and participants with AAV compared with HCs (1.67% median [IQR, 1.27%–2.16%], P < 0.001 for all comparisons), implying a defective central tolerance checkpoint in patients with AAV. Only PBMCs from participants with PR3-AAV contained PR3⁺ B cells capable of secreting PR3-ANCA IgG in vitro, proving they were functionally distinct from those of participants with MPO-AAV and HCs. Unsupervised clustering identified subtle subsets of atypical autoreactive PR3⁺ memory B cells accumulating through the maturation process in patients with PR3-AAV. PR3⁺ B cells were enriched in the memory B cell compartment of participants with PR3-AAV and were associated with higher serum CXCL13 levels, suggesting an increased germinal center activity. PR3⁺ B cells correlated with systemic inflammation (C-reactive protein and erythrocyte sedimentation rate, P < 0.05) and complete remission (P < 0.001).

CONCLUSION

This study suggests the presence of defective central antigen-independent and peripheral antigen-dependent checkpoints in patients with PR3-AAV, elucidating the selection process of autoreactive B cells.

Trial registration

ClinicalTrials.gov NCT00104299.

Funding

The Vasculitis Foundation, the National Institute of Allergy and Infectious Diseases of the NIH, and the Mayo Foundation for Education and Research.

Predictive Ability of Serum IL-27 Level for Assessing Activity of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Serum interleukin- (IL-) 27 level has been reported to increase in patients with several autoimmune diseases; however, its significance in patients with antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis (AAV) is unknown. In this study, we investigated the associations between serum IL-27, laboratory features, and activity of AAV and evaluate the predictive ability of serum IL-27 level for disease activity. This study included 77 AAV patients, and we collected clinical and laboratory data at blood sampling. Inflammation-related variables included white blood cell, neutrophil, lymphocyte and platelet counts, serum albumin, erythrocyte sedimentation rate, and C-reactive protein levels. Serum IL-27 and IL-18 levels were measured from stored sera using Human Magnetic Luminex® assay. High disease activity of AAV was defined as the highest tertile of Birmingham vasculitis activity score (BVAS) (≥11). The mean age of the enrolled patients was 59.9 years, and 38 (49.4%) were diagnosed as microscopic polyangiitis. In the multivariable analysis, serum albumin (β = −0.419) and serum IL-27 level (β = 0.221) were significantly associated with BVAS. Furthermore, patients with renal manifestation exhibited higher serum IL-27 (mean 308.7 pg/mL vs. 105.8 pg/mL) and IL-18 levels (mean 376.7 pg/mL vs. 270.4 pg/mL) than those without. On applying the optimal cut-off of serum IL-27 level for predicting high activity, AAV patients with serum IL − 27 level ≥ 300.8 pg/mL had a significantly higher risk for having high disease activity than those with serum IL − 27 level < 300.8 pg/mL (relative risk 3.380, 95% confidence interval 1.223, 9.345, P = 0.016). These results suggest that serum IL-27 level is associated with the cross-sectional activity and the presence of renal manifestation and could be used to predict high disease activity in patients with AAV.

Skewed peripheral B- and T-cell compartments in patients with ANCA-associated vasculitis

OBJECTIVES

To characterize lymphocytes dysregulation in patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).

METHODS

Using flow cytometry, we analysed B- and T-cell subsets in peripheral blood from 37 untreated patients with active disease (29 GPA and 8 MPA) and 22 healthy controls (HCs).

RESULTS

GPA patients had increased Th2 (1.8 vs 1.0%, P = 0.02), Th9 (1.1 vs 0.2%, P = 0.0007) and Th17 (1.4 vs 0.9%, P = 0.03) cells compared with HC. Patients with MPO-ANCAs had significantly more CD21- B cells than HC or PR3-ANCA patients (6.9 vs 3.3% and 4.4%, P = 0.01). CD69 expressing B cells were significantly higher in GPA and MPA (3.0 and 5.9 vs 1.4%, P = 0.02 and P = 0.03, respectively) compared with HC, whereas B-cell activating factor-receptor expression was decreased in GPA and MPA (median fluorescence intensity ratio 11.8 and 13.7 vs 45.1 in HC, P < 0.0001 and P = 0.003, respectively). Finally, IL-6-producing B cells were increased in GPA vs HC (25.8 vs 14.9%, P < 0.0001) and decreased in MPA vs HC (4.6 vs 14.9%, P = 0.005), whereas TNF-α-producing B cells were lower in both GPA and MPA patients compared with controls (15 and 8.4 vs 30%, P = 0.01 and P = 0.006, respectively).

CONCLUSION

Skewed T-cell polarization towards Th2, Th9 and Th17 responses characterizes GPA, whereas B-cell populations are dysregulated in both GPA and MPA with an activated phenotype and a decreased B-cell activating factor-receptor expression. Finally, inflammatory B cells producing IL-6 are dramatically increased in GPA, providing an additional mechanism by which rituximab could be effective.

A Review of the Various Roles and Participation Levels of B-Cells in Non-Infectious Uveitis

Non-infectious uveitis is an inflammatory disorder of the eye that accounts for severe visual loss without evident infectious agents. While T cells are supposed to dominate the induction of inflammation in non-infectious uveitis, the role of B cells in the pathogenesis of this disease is obscure. Therefore, this review aimed to discuss diverse B-cell participation in different non-infectious uveitides and their roles in the pathogenesis of this disease as well as the mechanism of action of rituximab. Increasing evidence from experimental models and human non-infectious uveitis has suggested the participation of B cells in non-infectious uveitis. The participation levels vary in different uveitides. Furthermore, B cells play multiple roles in the pathogenic mechanisms. B cells produce autoantibodies, regulate T cell responses via antibody-independent functions, and constitute ectopic lymphoid structures. Regulatory B cells perform pivotal anti-inflammatory functions in non-infectious uveitis. Rituximab may work by depleting pro-inflammatory B cells and restoring the quantity and function of regulatory B cells in this disease. Identifying the levels of B-cell participation and the associated roles is beneficial for optimizing therapy. Diversified experimental model choices and emerging tools and/or methods are conducive for future studies on this topic.

The significance of metalloproteinase 3 (MMP-3), chemokine CXC ligand 13 (CXCL-13) and complement component C5a in different stages of ANCA associated vasculitis

The aim of the study was to evaluate the significance of metalloproteinase 3 (MMP-3), chemokine CXC ligand 13 (CXCL-13) and complement component 5a (C5a) in different stages of ANCA associated vasculitis (AAV). 89 adults were included into the study. 28 patients with active AAV (Birmingham Vasculitis Activity Score, BVAS > 3) formed the Active Group. 24 individuals who were in remission after 6 months of induction therapy formed the Short R Group, while 34 patients with longitudinal remission formed the Long R Group. 28 patients without autoimmune diseases similar in terms of age, gender and stage of kidney disease formed the Control Group. Receiver operating characteristic curve analysis (ROC) was used to evaluate MMP-3, CXCL-13 and C5a as markers of the different phases of vasculitis. In ROC analysis, MMP-3, CXCL-13 and C5a presented a good ability in distinguishing active vasculitis (Active Group) from the Control Group (AUC > 0.8), whereas only CXCL-13 displayed potential ability in distinguishing active vasculitis (Active Group) from long term remission (Long R Group, AUC = 0.683). MMP-3 significantly and positively correlated with serum creatinine concentration (r = 0.51, p = 0.011; r = 0.44, p = 0.009; r =  −0.66, p < 0.001) and negatively with eGFR (r =  −0.5, p = 0.012; r =  −0.35, p = 0.039; r =  −0.63, p < 0.001) in the Short R, Long R and Control Groups. MMP-3, CXCL-13, C5a can be potential markers in differentiating an active phase of vasculitis from other pathologies. However they can be treated as complementary to the well-known markers. CXCL-13 seems to be a potential marker in distinguishing active vasculitis from long term remission. MMP-3 level can be related to kidney function expressed by eGFR, therefore its elevation should be interpreted with caution in patients with kidney failure.

Dysregulation of circulating follicular helper T cells in type 2 diabetic patients with diabetic retinopathy

Inflammation is known to be involved in the progression of diabetic retinopathy. Follicular helper T cells (Tfh) play critical roles in the differentiation of long-live plasma cells and production of antibodies, whereas circulating CD4⁺CXCR5⁺ T cells may act as a counterpart to measure Tfh cell disorders. In this study, we investigated whether Tfh could be involved in the development of diabetic retinopathy (DR) by assessing circulating Tfh cells in peripheral blood. Data showed that serum levels of total IgG and IgA were both significantly increased in type 2 diabetes mellitus (T2DM) patients with proliferative diabetic retinopathy (PDR) than with non-PDR. Also, B cell activation and differentiation were both enhanced in T2DM patients with PDR. Little changes were detected in levels of Th1, Th2, and Th17 cells. As indicated by elevated serum levels and supernatant from cultured PBMC of IL-21, we found increased circulating Tfh cells in PDR patients with dysregulated subsets. This study suggests the involvement of circulating Tfh cells in DR and, in particular, the pathogenesis of PDR.

Traditional Chinese medicine is a useful and promising alternative strategy for treatment of Sjogren's syndrome: A review

Primary Sjogren's syndrome (pSS) is a chronic autoimmune disease involving exocrine glands. Current studies have found that the occurrence of the disease is closely related to genetic, environmental and neuroendocrine factors, as well as abnormal activation of T and B lymphocytes. The etiology and pathogenesis of pSS is complex, and there is a lack of specific targeted drugs. Traditional Chinese medicines (TCMs) have been comprehensively investigated for their treatment effects on pSS. Through a systematic review of the literature, we summarized the TCMs used to treat pSS, and find that there are four major ways that TCMs are used, including upregulation of aquaporin proteins, suppression of cell apoptosis, suppression of the abnormal activation of B lymphocytes and suppression of the abnormal activation of T lymphocytes (balancing T helper type [Th]1/Th2 & Th17/Treg and suppressing follicular helper T [Tfh] cells). However, there are not enough data about the active constituents, quality control, pharmacokinetics, toxicity and modern preparations of these TCMs; therefore, more investigations are needed. This paper highlights the importance of TCMs for treating pSS and provides guidance for future investigations.

Innate Immunity and Biological Therapies for the Treatment of Sjögren's Syndrome

Sjögren's syndrome (SS) is a systemic autoimmune disorder affecting approximately 3% of the population in the United States. This disease has a female predilection and affects exocrine glands, including lacrimal and salivary glands. Dry eyes and dry mouths are the most common symptoms due to the loss of salivary and lacrimal gland function. Symptoms become more severe in secondary SS, where SS is present along with other autoimmune diseases like systemic lupus erythematosus, systemic sclerosis, or rheumatoid arthritis. It is known that aberrant activation of immune cells plays an important role in disease progression, however, the mechanism for these pathological changes in the immune system remains largely unknown. This review highlights the role of different immune cells in disease development, therapeutic treatments, and future strategies that are available to target various immune cells to cure the disease.

Proteinase 3 Autoreactivity in Anti-Neutrophil Cytoplasmic Antibody-associated vasculitis-Immunological versus clinical features

ANCA-associated vasculitis (AAV) is a group of chronic inflammatory diseases of small- and medium-sized vessels, which are broadly subdivided based on organ manifestations and disease-specific autoantibodies. The so called anti-neutrophil cytoplasmic antibodies (ANCA) mostly target one of the enzymes, proteinase 3 (PR3) or myeloperoxidase (MPO). Accumulating genetic data demonstrates that these two autoantibodies discriminate two distinct disease entities, more so than the clinical subdivision which is mainly criteria-based. Treatment of AAV includes heavy immunosuppression and is guided by which organs that are involved. Generally, patients with PR3-ANCA display higher risk for disease relapse than patients with MPO-ANCA. In this review, we will focus on the autoimmune features of PR3+ AAV and our current understanding of its triggers and the potential translation into clinical practice.

T Cells in Autoimmunity-Associated Cardiovascular Diseases

T cells are indisputably critical mediators of atherosclerotic cardiovascular disease (CVD), where they secrete pro-inflammatory cytokines that promote vascular pathology. Equally well-established is the fact that autoimmune diseases, which are mediated by autoreactive T cells, substantially increase the risk of developing CVD. Indeed, as immunomodulatory treatments have become more effective at treating end-organ pathology, CVD has become a leading cause of death in patients with autoimmune diseases. Despite this, investigators have only recently begun to probe the mechanisms by which autoreactive T cells promote CVD in the context of autoimmune diseases. T cells are best-studied in the pathogenesis of systemic vasculitides, where they react to self-antigen in the vessel wall. However, newer studies indicate that T cells also contribute to the increased CVD risk associated with lupus and rheumatoid arthritis. Given the central role of T-cell-derived cytokines in the pathogenesis of psoriasis, the role of these factors in psoriatic CVD is also under investigation. In the future, T cells are likely to represent major targets for the prevention and treatment of CVD in patients with autoimmune diseases.

Significant association between clinical characteristics and immuno-phenotypes in patients with ANCA-associated vasculitis

OBJECTIVES

To elucidate the association between clinical characteristics and immuno-phenotypes in patients with ANCA-associated vasculitis (AAV).

METHODS

Peripheral blood from 36 patients with active AAV and 18 healthy controls was examined for numbers of circulating T cells, B cells, NK cells, dendritic cells, monocytes and granulocytes using flow cytometry. These immuno-phenotyping data were subjected to cluster analysis and principal components analysis to divide AAV patients into subgroups. Associated organ involvement or therapeutic prognosis were assessed for each subgroup.

RESULTS

AAV patients had higher proportions of plasma cells, plasmablasts, activated T cells, CD14++ CD16+ monocytes, eosinophils and neutrophils than healthy controls. Immuno-phenotyping findings were similar between patients with microscopic polyangiitis, granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis. Cluster analysis indicated that AAV patients could be divided into three subgroups according to peripheral immune cell numbers: antibody production-related (n = 9), cytotoxic activity-related (n = 4) and neutrocytosis/lymphocytopenia-related (n = 23). The antibody production-related or cytotoxic activity-related group was associated with CNS involvement, and the neutrocytosis/lymphocytopenia-related group was associated with high incidence of kidney involvement. Incidence of severe infection was markedly higher in the neutrocytosis/lymphocytopenia-related group than the other two groups. Incidence of disease relapse was comparable among the three groups.

CONCLUSION

Patients with active AAV can be divided into three subgroups based on immuno-phenotyping. These results may provide a hint to understanding disease pathophysiology and prognosis, and determining appropriate treatment.

Imbalance of Circulatory T Follicular Helper and T Follicular Regulatory Cells in Patients with ANCA-Associated Vasculitis

Antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis (AAV) is characterized by small-vessel inflammation in association with autoantibodies. Balance between T follicular helper (Tfh) cells and T follicular regulatory (Tfr) cells is critical for humoral immune responses. Accumulating evidence supports that Tfh and Tfr are involved in autoimmune diseases; however, their roles in AAV are unclear. In this study, we tested the changes of circulatory Tfh and Tfr in patients with AAV. Twenty patients with AAV and twenty healthy controls were enrolled. Sixteen AAV patients had kidney involvement. We found that the AAV patients had increased circulating Tfh cells (CD4⁺CXCR5⁺CD25^-CD127^interm-hi), decreased Tfr cells (CD4⁺CXCR5⁺CD25⁺CD127^lo-interm), and elevated Tfh/Tfr ratios compared with healthy controls (P < 0.01). The Tfh percentage and Tfh/Tfr ratio, but not Tfr percentage, were positively correlated to proteinuria levels and BVAS scores in patients with AAV (P < 0.01). In addition, AAV patients had decreased circulating Tfh1 (CCR6^-CXCR3⁺), but increased Tfh2 cells (CCR6^-CXCR3^-), compared with healthy controls (P < 0.01), indicating a Tfh1-to-Tfh2 shift. Furthermore, remission achieved by immunosuppressive treatment markedly attenuated the increase of total Tfh (P < 0.01) and Tfh2 cells (P < 0.05), promoted the Tfh1 response (P < 0.05), and recovered the balance between Tfh/Tfr cells (P < 0.05) and between Tfh1/Tfh2 cells (P < 0.05) in patients with AAV. Plasma levels of IL-21, a cytokine secreted by Tfh cells, were elevated in AAV patients compared with healthy controls (P < 0.01), which was attenuated by immunosuppressive treatment (P < 0.05). Taken together, our findings indicate that circulatory Tfh/Tfr ratios, Tfh2/Tfh1 shift, and plasma IL-21 levels are associated with AAV and disease activity.

Increased CD40L+PD-1+ follicular helper T cells (Tfh) as a biomarker for predicting calcineurin inhibitor sensitivity against Tfh-mediated B-cell activation/antibody production after kidney transplantation

It is unclear to what extent the development of follicular helper T cells (Tfh) and de novo donor-specific human leukocyte antigen antibody (DSA) production could be influenced by immunosuppressive agents, particularly calcineurin inhibitor (CNI; cyclosporine or tacrolimus), after kidney transplantation. Here, the effects of immunosuppressive agents on Tfh-mediated B-cell activation and antibody production were investigated. In vitro circulating Tfh (cTfh; memory CD4+CXCR5+)/B-cell (CD19+) co-culture assays revealed that CNI considerably inhibited cTfh-mediated B-cell activation and IgG antibody secretion through the suppression of IL-21 and IL-2. Both IL-21 and CD40L up-regulated IL-2 receptors (CD25) on B cells, and anti-CD25 antibody induced apoptosis of activated B cells, resulting in the inhibition of IgG production. The frequency of cTfh-expressed CD40L and PD-1 was elevated in patients with de novo DSA 1 year after transplantation. The degree of inhibition by CNI was dependent on Staphylococcal enterotoxin B-induced CD40L+PD-1+ cTfh up-regulation level. Our data demonstrate that CD40L+PD-1+cTfh could be a marker to implicate individual difference in CNI sensitivity for Tfh-mediated B-cell activation in kidney transplantation.

T-lymphocyte in ANCA-associated vasculitis: what do we know? A pathophysiological and therapeutic approach

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an autoimmune condition that commonly causes kidney impairment and can be fatal. The key participation of B-lymphocytes as ANCA producers and neutrophils as target of these antibodies is widely described as the mechanism of endothelial damage in this disease. There has been a rising interest in the role of T-lymphocytes in AAV in recent years. Evidence is strong from animal models, and T-lymphocytes can be found infiltrating kidney tissue and other tissue sites in AAV patients. Furthermore, the different subsets of T-lymphocytes are also key players in the aberrant immune response observed in AAV. Polarization towards a predominant Th1 and Th17 response in the acute phase of the disease has been described, along with a decline in the number of T-regulatory lymphocytes, which, in turn, show functional impairment. Interactions between different T-cell subsets, and between T-cells and neutrophils and B-cells, also enhance the inflammatory response, constituting a complex network. Novel therapies targeting T-cell immunity are emerging in this scenario and may constitute an interesting alternative to conventional therapy in selected patients. This review aims to summarize the available evidence regarding T-cell imbalances and functional impairment, especially focusing on renal involvement of AAV.

Non-Antibody-Secreting Functions of B Cells and Their Contribution to Autoimmune Disease

B cells play multiple important roles in the pathophysiology of autoimmune disease. Beyond producing pathogenic autoantibodies, B cells can act as antigen-presenting cells and producers of cytokines, including both proinflammatory and anti-inflammatory cytokines. Here we review our current understanding of the non-antibody-secreting roles that B cells may play during development of autoimmunity, as learned primarily from reductionist preclinical models. Attention is also given to concepts emerging from clinical studies using B cell depletion therapy, which shed light on the roles of these mechanisms in human autoimmune disease.

Serum interleukin-21 positivity could indicate the current activity of antineutrophil cytoplasmic antibody-associated vasculitis: a monocentric prospective study

Interleukin-21 (IL-21) is a pleotropic cytokine that plays an important role in the regulation of both innate and adaptive immune responses. In the present study, we investigated whether serum IL-21 positivity is associated with disease activity in patients with all variants of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Sixty patients with AAV from a monocentric prospective cohort were enrolled from November 2016 to May 2018 in this study. On the day of visit, clinical manifestations including Birmingham vasculitis activity score (BVAS) were assessed, routine laboratory tests were performed, and blood samples were collected. Isolated sera were stored at - 80 °C on the same day to measure serum IL-21. The definition of generalised AAV set by the European Vasculitis Study group was adopted. In addition, serum IL-21 positivity was compared between patients with different autoimmune diseases and healthy controls. The mean age was 59.3 years, and 39 patients (65.0%) were women. Of patients, 23 (38.3%) had new-onset AAV, whereas 28 (46.7%) had generalised AAV. Serum IL-21 was detected in 16 patients (26.7%). Patients with serum IL-21 positivity exhibited a higher risk of having generalised AAV than those without (relative risk 5.250, p = 0.012). No difference in serum IL-21 positivity was observed among patients with AAV, rheumatoid arthritis, and systemic lupus erythematosus and healthy controls. Among patients with serum IL-21 positivity, serum IL-21 became negative at initial visit following the decrease in BVAS. Serum IL-21 positivity might be a useful biomarker to indicate the disease activity of AAV.

Dampening of CD8+ T Cell Response by B Cell Depletion Therapy in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVE

To compare the effects of rituximab (RTX) and conventional immunosuppressants (CIs) on CD4+ T cells, Treg cells, and CD8+ T cells in antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

A thorough immunophenotype analysis of CD4+, Treg, and CD8+ cells from 51 patients with AAV was performed. The production of cytokines and chemokines by CD8+ T cells stimulated in vitro was assessed using a multiplex immunoassay. The impact of AAV B cells on CD8+ T cell response was assessed using autologous and heterologous cocultures.

RESULTS

CD4+ and Treg cell subsets were comparable among RTX-treated and CI-treated patients. In contrast, within the CD8+ T cell compartment, RTX, but not CIS, reduced CD45RA+CCR7- (TEMRA) cell frequency (from a median of 39% before RTX treatment to 10% after RTX treatment [P < 0.01]) and efficiently dampened cytokine/chemokine production (e.g., the median macrophage inflammatory protein 1α level was 815 pg/ml in patients treated with RTX versus 985 pg/ml in patients treated with CIs versus 970 pg/ml in those with active untreated AAV [P < 0.01]). CD8+ T cell subsets cocultured with autologous B cells produced more proinflammatory cytokines in AAV patients than in controls (e.g., for tumor necrosis factor-producing effector memory CD8+ T cells: 14% in AAV patients versus 9.2% in controls [P < 0.05]). In vitro disruption of AAV B cell-CD8+ T cell cross-talk reduced CD8+ T cell cytokine production, mirroring the reduced CD8+ response observed ex vivo after RTX treatment.

CONCLUSION

The disruption of a pathogenic B cell/CD8+ T cell axis may contribute to the efficacy of RTX in AAV. Further studies are needed to determine the value of CD8+ T cell immunomonitoring in B cell-targeted therapies.

T cells in primary Sjögren's syndrome: targets for early intervention

A histologic hallmark of primary SS (pSS) is lymphocytic infiltration of the salivary and lacrimal glands, in particular by CD4⁺ T and B cells. In the early stages of the disease, infiltrates are dominated by CD4⁺ T cells, while B cell accumulation occurs at later stages. Activated T cells contribute to pathogenesis by producing pro-inflammatory cytokines and by inducing B cell activation, which results in the establishment of a positive feedback loop. In the inflamed glandular tissues, many different CD4⁺ effector subsets are present, including IFN-γ-producing Th1 cells, IL-17-producing Th17 cells and IL-21-producing T follicular helper cells. In blood from pSS patients, frequently observed abnormalities of the T cell compartment are CD4⁺ T cell lymphopenia and enrichment of circulating follicular helper T (Tfh) cells. Tfh cells are critical mediators of T cell–dependent B cell hyperactivity and these cells can be targeted by immunotherapy. Inhibition of T cell activation, preferably early in the disease process, can mitigate B cell activity and may be a promising treatment approach in this disease.

T Follicular Helper Cells in Autoimmune Disorders

T follicular helper (Tfh) cells are a distinct subset of CD4⁺ T lymphocytes, specialized in B cell help and in regulation of antibody responses. They are required for the generation of germinal center reactions, where selection of high affinity antibody producing B cells and development of memory B cells occur. Owing to the fundamental role of Tfh cells in adaptive immunity, the stringent control of their production and function is critically important, both for the induction of an optimal humoral response against thymus-dependent antigens but also for the prevention of self-reactivity. Indeed, deregulation of Tfh activities can contribute to a pathogenic autoantibody production and can play an important role in the promotion of autoimmune diseases. In the present review, we briefly introduce the molecular factors involved in Tfh cell formation in the context of a normal immune response, as well as markers associated with their identification (transcription factor, surface marker expression, and cytokine production). We then consider in detail the role of Tfh cells in the pathogenesis of a broad range of autoimmune diseases, with a special focus on systemic lupus erythematosus and rheumatoid arthritis, as well as on the other autoimmune/inflammatory disorders. We summarize the observed alterations in Tfh numbers, activation state, and circulating subset distribution during autoimmune and some other inflammatory disorders. In addition, central role of interleukin-21, major cytokine produced by Tfh cells, is discussed, as well as the involvement of follicular regulatory T cells, which share characteristics with both Tfh and regulatory T cells.

Changes in CD73, CD39 and CD26 expression on T-lymphocytes of ANCA-associated vasculitis patients suggest impairment in adenosine generation and turn-over

Extracellular adenosine, generated via the concerted action of CD39 and CD73, contributes to T-cell differentiation and function. Adenosine concentrations are furthermore influenced by adenosine deaminase binding protein CD26. Because aberrant T-cell phenotypes had been reported in anti-neutrophil cytoplasmic auto-antibody (ANCA)-associated vasculitis (AAV) patients, an impaired expression of these molecules on T-cells of AAV patients was hypothesized in the present study. While in AAV patients (n = 29) CD26 was increased on CD4⁺ lymphocytes, CD39 and CD73 were generally reduced on patients’ T-cells. In CD4⁺ cells significant differences in CD73 expression were confined to memory CD45RA^- cells, while in CD4^- lymphocytes differences were significant in both naïve CD45RA⁺ and memory CD45RA^- cells. The percentage of CD4^-CD73⁺ cells correlated with micro-RNA (miR)−31 expression, a putative regulator of factor inhibiting hypoxia-inducible factor 1 alpha (FIH-1), inversely with serum C-reactive protein (CRP) and positively with estimated glomerular filtration rate (eGFR). No correlation with disease activity, duration, and ANCA profile was found. It remains to be assessed if a decreased CD73 and CD39 expression underlies functional impairment of lymphocytes in AAV patients. Likewise, the relations between frequencies of CD4^-CD73⁺ cells and serum CRP or eGFR require further functional elucidation.

Impact of Depleting Therapeutic Monoclonal Antibodies on the Host Adaptive Immunity: A Bonus or a Malus?

Clinical responses to anti-tumor monoclonal antibody (mAb) treatment have been regarded for many years only as a consequence of the ability of mAbs to destroy tumor cells by innate immune effector mechanisms. More recently, it has also been shown that anti-tumor antibodies can induce a long-lasting anti-tumor adaptive immunity, likely responsible for durable clinical responses, a phenomenon that has been termed the vaccinal effect of antibodies. However, some of these anti-tumor antibodies are directed against molecules expressed both by tumor cells and normal immune cells, in particular lymphocytes, and, hence, can also strongly affect the host adaptive immunity. In addition to a delayed recovery of target cells, lymphocyte depleting-mAb treatments can have dramatic consequences on the adaptive immune cell network, its rebound, and its functional capacities. Thus, in this review, we will not only discuss the mAb-induced vaccinal effect that has emerged from experimental preclinical studies and clinical trials but also the multifaceted impact of lymphocytes-depleting therapeutic antibodies on the host adaptive immunity. We will also discuss some of the molecular and cellular mechanisms of action whereby therapeutic mAbs induce a long-term protective anti-tumor effect and the relationship between the mAb-induced vaccinal effect and the immune response against self-antigens.

The value of rituximab treatment in primary Sjögren's syndrome

The rationale for B cell depletion therapy with rituximab in primary Sjögren's syndrome relies upon the well-established role of B cell hyperactivity in immunopathogenesis. In line with this notion, several biomarkers of B cell activity are significantly affected by treatment, both in the target organs and periphery. In contrast to most biological outcomes, clinical outcomes are not consistent between studies. Although two large RCTs did not meet their primary endpoint, several beneficial clinical effects of treatment have been shown. As discussed in this review, differences in study design and patient characteristics could explain the variation in results. Interestingly, a newly developed composite endpoint of subjective and objective outcomes did show a significant effect of rituximab in one of the large RCTs. Response predictors need to be identified to define more targeted inclusion criteria and achieve precision medicine. The positive effects seen on biological and clinical parameters warrant future studies to investigate this promising treatment modality.

Increased Circulating T Follicular Helper Cells Are Inhibited by Rituximab in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune disease of the central nervous system. The existence of autoantibody targeting aquaporin-4 (AQP4-Ab) indicates the involvement of humoral immunity in the pathogenesis of this disease. Rituximab (RTX), a monoclonal antibody against CD20, has been used to treat NMOSD by depleting circulating B cells and overall satisfactory outcome has been achieved. Although T follicular helper cells have been proved to regulate B cell activation and antibody production, the role of these cells in NMOSD and the impact of RTX treatment on these cells remain less understood. In this study, we found that frequencies of circulating T follicular helper (cTfh) cells and B cells together with the related cytokines, IL-21 and IL-6, were closely correlated with disease activity of NMOSD. Furthermore, B cell depletion with RTX treatment inhibited the expansion of cTfh cells, and these effects were achieved through eliminating IL-6-producing B cells and blocking the direct contact between cTfh cells and B cells. These findings imply the complicated cross talk between cTfh cells and B cells and may provide a novel therapeutic target for NMOSD.

B Cell Depletion Therapy Normalizes Circulating Follicular Th Cells in Primary Sjögren Syndrome

OBJECTIVE

To assess the effect of B cell depletion therapy on effector CD4+ T cell homeostasis and its relation to objective measures of disease activity in patients with primary Sjögren syndrome (pSS).

METHODS

Twenty-four patients with pSS treated with rituximab (RTX) and 24 healthy controls (HC) were included. Frequencies of circulating effector CD4+ T cell subsets were examined by flow cytometry at baseline and 16, 24, 36, and 48 weeks after the first RTX infusion. Th1, Th2, follicular Th (TFH), and Th17 cells were discerned based on surface marker expression patterns. Additionally, intracellular cytokine staining was performed for interferon-γ, interleukin (IL)-4, IL-21, and IL-17 and serum levels of these cytokines were analyzed.

RESULTS

In patients with pSS, frequencies of circulating TFH cells and Th17 cells were increased at baseline compared with HC, whereas frequencies of Th1 and Th2 cells were unchanged. B cell depletion therapy resulted in a pronounced decrease in circulating TFH cells, whereas Th17 cells were only slightly lowered. Frequencies of IL-21-producing and IL-17-producing CD4+ T cells and serum levels of IL-21 and IL-17 were also reduced. Importantly, the decrease in circulating TFH cells was associated with lower systemic disease activity over time, as measured by the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index scores and serum IgG levels.

CONCLUSION

B cell depletion therapy in patients with pSS results in normalization of the elevated levels of circulating TFH cells. This reduction is associated with improved objective clinical disease activity measures. Our observations illustrate the pivotal role of the crosstalk between B cells and TFH cells in the pathogenesis of pSS.

MPO-ANCA-associated necrotizing glomerulonephritis in rheumatoid arthritis; a case report and review of literature

Background

Renal involvement in rheumatoid arthritis (RA) is common and has a negative impact on patient survival. Only few cases have been reported of necrotizing glomerulonephritis (GN) associated with myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) in patients with RA.

Case Presentation

We report a patient with RA who developed a necrotizing GN associated with ANCA-MPO, treated with rituximab (RTX). A 55-year-old man with a 27-year history of RA under secukinumab was referred to our nephrology clinic with worsening renal function associated with microhematuria and proteinuria. Our laboratory evaluation showed hypocomplementemia and positive titers for MPO-ANCA (615 U/mL). A renal biopsy demonstrated pauci-immune necrotizing GN. The patient was treated with 3 consecutive pulses of methylprednisolone followed by oral prednisolone (1 mg/Kg) and rituximab (1000 mg, repeated 14 days later). After a 10-month follow-up, the arthritis remains well-controlled, renal function stabilized, proteinuria improved and MPO-ANCA titer normalized (6.3 U/mL).

Conclusions

Necrotizing GN is a rare but a serious condition and an early diagnosis is essential to treatment. This is the first case of necrotizing GN (without extra-renal manifestations of vasculitis) in a patient with active RA, successfully treated with RTX.

Altered circulating T follicular helper cell subsets in patients with psoriasis vulgaris

Circulating T follicular helper (Tfh) cells in the blood are counterparts to conventional Tfh cells in germinal centres. Similarly to conventional Tfh cells, circulating Tfh cells provide helpful signals for B cells. Circulating Tfh cells can be divided into three subpopulations, including Tfh17 (CXCR3-CCR6+), Tfh1 (CXCR3+CCR6-), and Tfh2 (CXCR3-CCR6-) cells, based on differences in CXCR3 and CCR6 expression. Recent studies have demonstrated that alterations in circulating Tfh cell subsets have significant effects on the progression of numerous autoimmune diseases. To address the role of circulating Tfh cells in psoriasis, we used flow cytometry to analyse frequencies of circulating Tfh cell subsets and levels of IL-21 receptor (IL-21R) expression on B cells in 32 patients with psoriasis vulgaris and 13 sex- and age-matched healthy controls. We observed dynamic changes in Tfh17 cell frequency and disease severity in 10 psoriasis patients during a 6-month treatment. Our results demonstrate that the frequency of Tfh17 cells was significantly increased in psoriasis patients and was positively correlated with psoriasis area and severity index (PASI) score, a marker of disease severity (P<0.05). During the follow-up period, the frequencies of Tfh17 cells decreased, and reductions in PASI scores were observed. Moreover, IL-21R expression on B cells was significantly increased in patients with psoriasis vulgaris (P<0.05). Interestingly, IL-21R levels on B cells were correlated with both PASI score and the frequency of Tfh17 cells (P<0.05). In conclusion, this study is the first investigation of the distribution of circulating Tfh subsets in psoriasis. These results deepen our understanding of the immune state of psoriasis patients. Our data also indicate that Tfh17 cells may not be good biomarkers for diagnosing psoriasis but may be potential biomarkers of disease severity in psoriasis.

Changes in circulating follicular helper T-cells in Chinese patients with allergic rhinitis

CONCLUSIONS

Changes of circulating Follicular helper T (cTfh) cells existed in allergic rhinitis (AR) patients, and the severity of disease was associated with a more severe change of cTfh milieu. These results imply that cTfh cells may play a crucial role in the pathology of AR in Chinese patients.

OBJECTIVES

The aim of this study was to investigate the changes in cTfh cells in Chinese AR patients.

METHODS

Fifty-two patients were studied (32 in the AR group and 20 in the control group) for this research. The cTfh cell frequency and mRNA levels of transcription factor Bcl-6, B lymphocyte induced maturation protein 1 (BLIMP-1), and related cytokine IL-21 (IL-21 protein was also measured) were analyzed. Clinical severity was evaluated by total serum IgE levels, visual analog scale scores (VAS), and rhino-conjunctivitis quality-of-life questionnaires (RQLQ).

RESULTS

The frequency of cTfh cells were elevated in AR groups vs healthy controls (p < 0.05). Levels of IL-21 mRNA, Bcl-6 mRNA and the level of IL-21 protein were also significantly higher in the AR groups (p < 0.05), whereas BLIMP-1 mRNA was decreased (p < 0.05). Furthermore, positive correlations were identified between the frequency of cTfh cells and indicators of clinical severity (p < 0.01).

Impaired function of CD4+ T follicular helper (Tfh) cells associated with hepatocellular carcinoma progression

Background and Aims

CD4+ T follicular helper (Tfh) cells, a new subset of immune cells, have been demonstrated to be involved in the development and prognosis of tumors. However, their functional role in human hepatocellular carcinoma (HCC) is relatively unknown, and the detailed mechanisms in HCC development remain to be described.

Methods

A total of 85 HCC patients with hepatitis B virus (HBV) infection, 25 HBV-relative liver cirrhosis (LC) patients, and 20 healthy controls (HC) were randomly enrolled. Flow cytometric analysis, immunohistochemical staining, and relative function (i.e., cytokine secretion, B cell maturation) assays were used to analyze the properties of CXCR5+CD4+ T cells. In addition, the relationship between the frequency of CXCR5+CD4+ T cells and overall survival rates or disease-free survival rates was also analyzed by the Kaplan-Meier method.

Results

The frequency of circulating CXCR5+CD4+ T cells was significantly decreased in HCC patients compared with HBV-relative liver cirrhosis (LC) patients and healthy controls, and the decrease in circulating CXCR5+CD4+ T cells correlated with disease progression. The proportion of infiltrated CXCR5+CD4+ T cells was significantly decreased in tumor regions compared with nontumor regions. Furthermore, compared with healthy controls, the function of circulating CXCR5+CD4+ T cells in HCC was impaired, with reduced IL-21 secretion and dysfunction in promoting B cell maturation. Importantly, follow-up data indicated that a decreased frequency of circulating CXCR5+CD4+ T cells was also associated with reduced disease-free survival time in HCC patients.

Conclusions

Impairment of CD4+ T follicular helper cells may influence the development of HBV-associated HCC. Decreased CD4+ T follicular helper cells may represent a potential prognostic marker and serve as a novel therapeutic target for HCC patients.

The impact of biological therapy on regulatory T cells in rheumatoid arthritis

Regulatory T cells (Treg) are functionally defective in patients with RA. Restoring their function may not only control inflammation but also restore tolerance in these patients. Biologic therapies have been tremendously successful in treating RA. Here we review numerous reports suggesting that these immunomodulatory therapies have an impact on Treg and that this may contribute to their beneficial effects. Better understanding of their mode of action may not only lead to improvements in therapies and sustained remission but also enable the development of biomarkers of response, which would be the first steps towards personalized medicine.

Current and emerging treatment options for ANCA-associated vasculitis: potential role of belimumab and other BAFF/APRIL targeting agents

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises several clinical entities with diverse clinical presentations, outcomes, and nonunifying pathogenesis. AAV has a clear potential for relapses, and shows unpredictable response to treatment. Cyclophosphamide-based therapies have remained the hallmark of induction therapy protocols for more than four decades. Recently, B-cell depleting therapy with the anti-CD20 antibody rituximab has proved beneficial in AAV, leading to Food and Drug Administration approval of rituximab in combination with corticosteroids for the treatment of AAV in adults. Rituximab for ANCA-associated vasculitis and other clinical trials provided clear evidence that rituximab was not inferior to cyclophosphamide for remission induction, and rituximab appeared even more beneficial in patients with relapsing disease. This raised hopes that other B-cell-targeted therapies directed either against CD19, CD20, CD22, or B-cell survival factors, B-cell activating factor of the tumor necrosis factor family (BAFF) and a proliferation-inducing ligand could also be beneficial for the management of AAV. BAFF neutralization with the fully humanized monoclonal antibody belimumab has already shown success in human systemic lupus erythematosus and, along with another anti-BAFF reagent blisibimod, is currently undergoing Phase II and III clinical trials in AAV. Local production of BAFF in granulomatous lesions and elevated levels of serum BAFF in AAV provide a rationale for BAFF-targeted therapies not only in AAV but also in other forms of vasculitis such as Behcet’s disease, large-vessel vasculitis, or cryoglobulinemic vasculitis secondary to chronic hepatitis C infection. BAFF-targeted therapies have a very solid safety profile, and may have an additional benefit of preferentially targeting newly arising autoreactive B cells over non-self-reactive B cells.

Circulating follicular helper T cells in Crohn's disease (CD) and CD-associated colorectal cancer

Follicular helper T cells (Tfh) represent a distinct subset of CD4+ T cells specialized in providing help to B lymphocytes. Studies have indicated that Tfh in circulating blood can act as a prognostic marker for diseases. In the current study, we investigated the percentages of circulating Tfh (CTfh) in Crohn's disease (CD) and CD-associated colorectal cancer (CRC). CTfh and it subtypes were determined by measuring CD3, CD4, CXCR5, CXCR3, and CCR6 using flow cytometry in 32 healthy controls and 78 CD patients, which included 16 CD-associated CRC. Data showed that proportion of CTfh in CD4+ T cells was significantly increased in CD patients (9.8 %) than in controls (5.1 %) (p < 0.01). Further analysis revealed that the upregulation of CTfh was contributed by CTfh-Th1 subtype and CTfh-Th17 subtype. Investigating the behavior of the patients demonstrated that prevalence of CTfh was significantly elevated in penetrating CD (20.9 %) than inflammatory CD (8.2 %) or stricturing CD (7.5 %). In addition, we analyzed CTfh in CD-associated CRC, and identified that patients with CRC had 1.59-fold higher percentage of CTfh than patients without CRC (p < 0.01). Furthermore, the distribution of CTfh subsets was significantly altered in patients with the cancer. This study suggests the involvement of CTfh in CD and CD-associated CRC, in which the effect of CTfh is partially different between these two diseases.