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

New Biomarkers for Systemic Necrotizing Vasculitides

Systemic necrotising vasculitides (SNVs) pose significant challenges due to their diverse clinical manifestations and variable outcomes. Therefore, identifying reliable biomarkers holds promise for improving precision medicine in SNVs. This review explores emerging biomarkers aiming to enhance diagnostic accuracy, prognostic assessment, and disease monitoring. We discuss recent advances in immunological biomarkers, inflammatory indicators, and other parameters that exhibit potential diagnostic and prognostic utility. A comprehensive understanding of these biomarkers may facilitate earlier and more accurate SNV detection, aiding in timely intervention and personalized treatment strategies. Furthermore, we highlight the evolving landscape of disease monitoring through innovative biomarkers, shedding light on their dynamic roles in reflecting disease activity and treatment response. Integrating these novel biomarkers into clinical practice can revolutionize the management of SNVs, ultimately improving patient outcomes and quality of life.

T follicular helper cells and T peripheral helper cells in rheumatic and musculoskeletal diseases

Recent technological progress has greatly advanced our understanding of human immunology. In particular, the discovery of human T follicular helper (Tfh) and T peripheral helper (Tph) cells has significantly advanced our understanding of human adaptive immune system. Tfh and Tph cells share similar molecular characteristics and both play critical roles in B cell differentiation and maturation. However, they differ in their functional properties, such as chemokine receptor expression and cytokine production. As a result, Tfh cells are mainly involved in B cell differentiation and maturation in germinal centres of secondary lymphoid tissues, while Tph cells are involved in B cell differentiation and tissue damage in peripheral inflammatory lesions. Importantly, the involvement of Tfh and Tph cells in the pathogenesis of rheumatic and musculoskeletal diseases has become clear. In rheumatoid arthritis and systemic lupus erythematosus, Tph cell infiltration is predominant in peripheral inflammatory lesions, whereas Tfh cell infiltration is predominant in the affected lesions of IgG4-related disease. Therefore, the contribution of Tfh and Tph cells to the development of rheumatic and musculoskeletal diseases varies depending on each disease. In this review, we provide an overview of human Tfh and Tph cells and summarise the latest findings on these novel T cell subsets in various rheumatic and musculoskeletal diseases.

Antineutrophil Cytoplasmic Antibody-Associated Vasculitis and the Risk of Developing Incidental Tuberculosis: A Population-Based Cohort Study

Background and Objectives: Treatment for antineutrophil cytoplasmic antibody-associated vasculitis (AAV) must deal with immunosuppression, as well as infections associated with a compromised immune system, such as tuberculosis (TB). Our aim was to examine the risk of incidental TB after diagnosis of AAV. Materials and Methods: This retrospective population-based cohort study was based on the data from the National Health Insurance Research Database in Taiwan. Patients with newly diagnosed granulomatous polyangiitis or microscopic polyangiitis were identified between 1 January 2000 and 31 December 2012. The primary outcome was risk of incidental TB. Cox proportional hazard models were used to evaluate the association between AAV and incidental TB. Results: A total of 2257 patients with AAV and a propensity-score matched cohort of 9028 patients were studied. Overall, patients with AAV were at a 1.48× higher risk of contracting incidental TB than the patients in the matched cohort (adjusted HR 1.48; 95% confidence interval [CI], 1.02-2.15). Note that the highest risk of contracting incidental TB was in the first two years following a diagnosis of AAV, with a nearly 1-fold increase in risk (adjusted HR, 1.91; 95% CI, 1.01-3.60). Female AAV patients were 3.24× more likely than females without AAV to develop TB (adjusted HR 3.24; 95% CI, 1.85-5.67). Conclusions: Patients with AAV exhibit a 48% elevated TB risk, notably, a 91% increase within the first two years postdiagnosis. Female AAV patients face a 3.24 times higher TB risk compared to females without AAV. This study is limited by potential misclassification and overestimation of AAV cases. Clinicians should closely monitor TB risk in AAV patients, especially in females and the initial two years following diagnosis.

Case Report: Immune checkpoint inhibitor-induced multiorgan vasculitis successfully treated with rituximab

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. ICIs have a unique side effect profile, generally caused by inflammatory tissue damage, with clinical features similar to autoimmune conditions. Acute kidney injury from ICIs has been well studied; incidence ranges from 1% to 5%, with higher incidence when combination ICI therapies are used. Although the overall reported incidence of ICI-associated glomerulonephritis is less than 1%, vasculitis is the most commonly reported ICI-related glomerulonephritis. Other biopsy findings include thrombotic microangiopathy, focal segmental glomerulosclerosis, minimal change disease, and IgA nephropathy with secondary amyloidosis. We report a case in which a woman previously treated with the PD-L1 inhibitor durvalumab for locally advanced non-small cell lung cancer with pre-existing antineutrophil cytoplasmic (anti-PR3) antibody who later developed multi-organ vasculitis after ICI exposure, which was successfully treated with rituximab, with continued cancer remission for 3 years.

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

Background

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

Methods

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

Results

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

Conclusion

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

Increased Circulating PD-1 hi CXCR5 - Peripheral T Helper Cells are Associated with Disease Activity of ANCA-Associated Vasculitis

Newly identified PD-1 hiCXCR5 -CD4 + T cells, termed as peripheral helper T cells (Tph), have been found elevated and playing pathogenic role in some autoimmune diseases like systemic lupus erythematosus (SLE) and rheumatic arthritis (RA). However, the potential role of Tph cells in Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) remains unclear. Here, we explored the potential clinical significance of circulating Tph cells in the pathogenesis of AAV. Comparing 32 active AAV patients and 18 age- and sex-matched healthy controls (HCs), we found that the frequency of circulating Tph cells was significantly expanded in active AAV patients. Besides, programmed death 1 (PD-1) expression on the surface of Tph cells was significantly up-regulated in active AAV patients. Importantly, the frequency of circulating Tph cells was greatly decreased in AAV patients after receiving treatment. Tph cells frequency was positively correlated with the Birmingham Vasculitis Activity Score (BVAS), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), neutrophil lymphocyte ratio (NLR) and cellular crescent in active AAV patients, but negatively correlated with fibrosus crescent. Tph cells frequency was also positively correlated with naïve B cells, serum concentration of MPO-ANCAs, serum tumor necrosis factor-α (TNF-α), IL-4, IL-21 and IL-12. However, serum IL-10 exhibited negative correlation with circulating Tph cells in active AAV patients. These results demonstrated that circulating Tph cells are greatly expanded in active AAV patients and are positively associated with serum MPO-ANCAs and disease activity, thus contributing to the pathogenesis of AAV.

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.

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.

Immune Cells Profiling in ANCA-Associated Vasculitis Patients-Relation to Disease Activity

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a group of necrotizing multiorgan autoimmune vasculitides that predominantly affect small blood vessels and are associated with the presence of ANCAs. The aim was to assess regulatory and effector cell populations accompanied by the suPAR biomarker level and link the so-defined immune state to the AAV disease activity. The research involved a multicomponent description of an immune state encompassing a range of B and T cell subsets such as transitional/regulatory B cells (CD19+CD24++CD38++), naïve B cells (CD19+CD24INTCD38INT), Th17 cells, T regulatory cells (CD4+CD25+FoxP3+) and cytotoxic CD4+CD28- cells by flow cytometry. The suPAR plasma level was measured by ELISA. The results indicate that AAV is associated with an increased suPAR plasma level and immune fingerprint characterized by an expansion of Th17 cells and T cells lacking the costimulatory molecule CD28, accompanied by a decrease of regulatory populations (Tregs and transitional B cells) and NK cells. Decreased numbers of regulatory T cells and transitional B cells were shown to be linked to activation of the AAV disease while the increased suPAR plasma level-to AAV-related deterioration of kidney function. The observed immune fingerprint might be a reflection of peripheral tolerance failure responsible for development and progression of ANCA-associated vasculitides.

Follicular regulatory T cell biology and its role in immune-mediated diseases

Follicular regulatory T (Tfr) cells are recently found to be a special subgroup of regulatory T (Treg) cells. Tfr cells play an important role in regulating the germinal center (GC) response, especially modulating follicular helper T (Tfh) cells and GC-B cells, thereby affecting the production of antibodies. Tfr cells are involved in the generation and development of many immune-related and inflammatory diseases. This article summarizes the advances in several aspects of Tfr cell biology, with special focus on definition and phenotype, development and differentiation, regulatory factors, functions, and interactions with T/B cells and molecules involved in performance and regulation of Tfr function. Finally, we highlight the current understanding of Tfr cells involvement in autoimmunity and alloreactivity, and describe some drugs targeting Tfr cells. These latest studies have answered some basic questions in Tfr cell biology and explored the roles of Tfr cells in immune-mediated diseases.

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

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

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

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

Frontiers of Autoantibodies in Autoimmune Disorders: Crosstalk Between Tfh/Tfr and Regulatory B Cells

Balance of Tfh/Tfr cell is critically important for the maintenance of immune tolerance, as evidenced by the fact that T follicular helper (Tfh) cells are central to the autoantibodies generation through providing necessary help for germinal center (GC) B cells, whereas T follicular regulatory (Tfr) cells significantly inhibit autoimmune inflammation process through restraining Tfh cell responses. However, signals underlying the regulation of Tfh and Tfr cells are largely undefined. Regulatory B cells (Bregs) is a heterogeneous subpopulation of B cells with immunosuppressive function. Considerable advances have been made in their functions to produce anti‐inflammatory cytokines and to regulate Th17, Th1, and Treg cells in autoimmune diseases. The recent identification of their correlations with dysregulated Tfr/Tfh cells and autoantibody production makes Bregs an important checkpoint in GC response. Bregs exert profound impacts on the differentiation, function, and distribution of Tfh and Tfr cells in the immune microenvironment. Thus, unraveling mechanistic information on Tfh-Breg and Tfr-Breg interactions will inspire novel implications for the establishment of homeostasis and prevention of autoantibodies in diverse diseases. This review summarizes the dysregulation of Tfh/Tfr cells in autoimmune diseases with a focus on the emerging role of Bregs in regulating the balance between Tfh and Tfr cells. The previously unsuspected crosstalk between Bregs and Tfh/Tfr cells will be beneficial to understand the cellular mechanisms of autoantibody production and evoke a revolution in immunotherapy for autoimmune diseases.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Frequency of Efficient Circulating Follicular Helper T Cells Correlates with Dyslipidemia and WBC Count in Atherosclerosis

Background

The significance of cTfh cells and their subsets in atherosclerosis is not well understood. We measured the frequency of cTfh subsets in patients with different degrees of stenosis using flow-cytometry.

Methods

Participants included high (≥50%; n = 12) and low (<50%; n = 12) stenosis groups, as well as healthy controls (n = 6).

Results

The frequency of CCR7loPD-1hiefficient-cTfh was significantly higher in patients with high stenosis compared to healthy controls (p = 0.003) and correlated with low-density lipoprotein (LDL; p = 0.043), cholesterol (p = 0.043), triglyceride (p = 0.019), neutrophil count (p = 0.032), platelet count (p = 0.024), neutrophil/lymphocyte ratio (NLR; p = 0.046), and platelet/lymphocyte ratio (PLR; p = 0.025) in high stenosis group. The frequency of CCR7hiPD-1lo quiescent-cTfh was higher in healthy controls compared to the high-stenosis group (p = 0.001) and positively correlated with high-density lipoprotein (p = 0.046). The frequency of efficient-cTfh cells was correlated with platelet count (p = 0.043), NLR (p = 0.036), and PLR (p P = 0.035) in low-stenosis group, while that of quiescent-cTfh cells was negatively correlated with LDL (p = 0.034), cholesterol (p = 0.047), platelet count (p = 0.032), and PLR (p = 0.041).

Conclusion

High percentages of cTfh and efficient-cTfh cells in patients with advanced atherosclerosis and their correlation with dyslipidemia and white blood cell counts suggest an ongoing cTfh subset deviation, towards efficient phenotype in the milieu of inflammation and altered lipid profile. Efficient cTfh cells have an effector phenotype and could in turn contribute to atherosclerosis progression.

Checkpoint inhibitor-related renal vasculitis and use of rituximab

The percentage of patients with cancer eligible for checkpoint inhibitor (CPI) therapy has increased rapidly over the past few years and approaches 45%. As a result, more cases of CPI-related nephrotoxicity, including a rare subset with vasculitis, are being reported. To elucidate the clinical presentation of CPI-associated renal vasculitis and its possible mechanisms, treatment options and prognosis, we describe cases from a comprehensive cancer center and reviewed the literature for similar cases. We retrospectively reviewed the charts of all patients with cancer from 2014 to 2020 who were diagnosed with CPI-related nephrotoxicity and underwent a kidney biopsy. We identified five cases of renal vasculitis: three patients were diagnosed with seronegative antineutrophil cytoplasm antibody (ANCA)-associated vasculitis, one case with seropositive ANCA-associated vasculitis and one case was diagnosed with IgA vasculitis. Of these cases, four patients were receiving nivolumab, and one patient was receiving tremelimumab. All patients had microscopic hematuria, four out of five patients had negative ANCA serology, one patient had concurrent lung involvement and positive ANCA serology, and all had severe acute kidney injury with creatinine >4.50 mg/dL on diagnosis. All patients were treated by discontinuing CPI and initiating corticosteroids and rituximab. Three patients received plasmapheresis; two of these required renal replacement therapy including the patient with lung involvement. All patients after rituximab had a partial or complete renal response. Two patients died within 8 months of diagnosis due to malignancy progression. None of the patients had a relapse of vasculitis. We demonstrated that CPI can be associated with different types of renal vasculitis that are predominantly ANCA negative and manifest as severe acute kidney injury. Despite the lack of strong evidence, treatment similar to treatment of primary seropositive ANCA-associated vasculitis with corticosteroids and rituximab is well tolerated with favorable renal outcomes.