Effects of interleukin-6 signal inhibition on Treg subpopulations and association of Tregs with clinical outcomes in rheumatoid arthritis.

OBJECTIVES: Anti-IL-6 receptor antibodies are clinically efficacious in the management of RA with an associated increase in Tregs; however, the role of functional Treg subsets has yet to be clarified. This study aimed to evaluate how functional Treg subsets are altered by IL-6 receptor blockade and to analyse the relationship between these Treg subsets and the clinical outcome of RA. METHODS: We collected frozen peripheral blood mononuclear cells (PBMCs) from 40 patients with RA who started tocilizumab (TCZ) with or without MTX and 11 healthy controls (HCs). We fractionated Tregs with flow cytometry based on markers of phenotype and function and measured the proportions of detailed Treg subsets sequentially from baseline to week 52. RESULTS: The proportions of resting Tregs (rTregs) and rTregs+activated Tregs (aTregs) were significantly lower in RA patients at baseline than in HCs. The proportions of all those CD127low Tregs, rTregs, aTregs and rTregs+aTregs were significantly increased with TCZ treatment. In patients treated with TCZ without MTX, rTreg were increased. Patients with an increase in the proportion of rTregs at week 12 had significantly less arthritis flares during the observation period. CONCLUSIONS: Blocking the IL-6 receptor with TCZ increased the proportion of rTregs, a functional Treg subpopulation. Patients with an early increase in rTregs showed a favourable treatment course and this increase in rTregs may reflect molecular remission induced by IL-6 signal inhibition.

Th17/IL-17A axis is critical for pulmonary arterial hypertension (PAH) in systemic sclerosis (SSc): SSc patients with high levels of serum IL-17A exhibit reduced lung functions and increased prevalence of PAH.

BACKGROUND: It is thought that systemic sclerosis (SSc) might be a T helper 17 (Th17) cell-driven autoimmune disease. Noticeably, pulmonary arterial hypertension (PAH) is a leading cause of death in patients with SSc. Here, we investigated the association between serum Th17-related cytokines and prevalence of PAH in SSc patients. METHODS: This study included 72 SSc patients and 51 healthy controls (HC). We determined clinical manifestations, immunophenotypes including Th subsets in peripheral blood lymphocytes, and the serum levels of interleukin (IL)-17A, IL-17A/F, IL-17B. IL-17C, IL-17D. IL-1ß, IL-6, IL-21, IL-22, and IL-23. RESULTS: The frequency of Th17 cells was significantly increased in SSc patients compared to HC and was positively correlated with the modified Rodnan skin scores. Furthermore, the serum levels of IL-17A, IL-17D, IL-1ß, and IL-6 were significantly increased in SSc patients compared to HC. SSc patients with detected IL-17A showed high levels of IL-17A/F, IL-1ß, IL-6, and IL-22, and high frequency of Th17 cells. Interestingly, these patients exhibited the reduced lung functions and increased prevalence of PAH significantly compared to patients with undetected IL-17A. Similarly, SSc patients with detected IL-17A and high IL-6 (≥1.2 pg/mL) exhibited the decreased lung functions and increased prevalence of PAH compared to patients with undetected IL-17A and low IL-6. CONCLUSION: We found that SSc patients with high levels of serum IL-17A or both IL-17A and IL-6 show reduced lung functions and high prevalence of PAH. Consequently, it is highly probable that Th17/IL-17A axis is critical for the prevalence of PAH in SSc patients.

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.

Disease-specific expansion of CD29+IL-17RA+ T effector cells possessing multiple signalling pathways in spondyloarthritis.

OBJECTIVES: T cells adhere to enthesis fibrocartilage via integrins and intrinsically require IL-17RA-mediated signals to maintain their effector function. We analysed CD29+IL-17RA+ T cells in inflamed lesions and peripheral blood in patients with SpA and investigated their association with disease activity and therapeutic response. METHODS: Transcriptome analysis of synovial fluid T cells from PsA was performed using publicly available bulk cell RNA sequencing data. Blood samples were obtained from healthy controls (n = 37), RA (n = 12), IgG4-related disease (IgG4-RD; n = 12), large vessel vasculitis (LVV; n = 12) and SpA (n = 28) and were analysed by flow cytometry. RESULTS: T cells in the inflamed joints of PsA showed CD29 and IL-17RA expression. CD29+IL-17RA+ T cells showed enriched CXCR3+CD45RA+ effector cells and activation of spleen tyrosine kinase (Syk), nuclear factor κB (NF-κB) and Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways. The proportion of peripheral blood CD29+IL-17RA+ T cells was significantly increased in patients with SpA compared with patients with RA, IgG4-RD or LVV and in healthy controls. Based on the ASDAS-CRP scores, the proportion of CD29+IL-17RA+ T cells was positively correlated with disease activity in treatment-naïve patients with active SpA. Anti-IL-17 but not anti-TNF monoclonal antibodies reduced CD29+IL-17RA+ T cells. CONCLUSIONS: CD29+IL-17RA+ T effector cells with enhanced Syk, NF-κB and JAK-STAT pathways were specifically increased in SpA and were correlated with disease activity, implicating a role of this newly identified T cell population in the pathogenesis. Anti-IL-17 monoclonal antibodies may be effective for patients by reducing this pathogenic T cell population.

Role of interferons (IFNs) in the differentiation of T peripheral helper (Tph) cells.

Interleukin (IL)-21-producing T peripheral helper (Tph) cells are thought to contribute to extra-follicular B cell activation and play a pathogenic role in autoimmune diseases. In this study, we investigated the relationship between Tph cells and interferons (IFNs) in several autoimmune diseases because our previous study demonstrated that type I IFNs promote the differentiation of IL-21-producing Tph-like cells. The frequency of Tph cells in the blood as well as serum IFN-α2a and IFN-λ1 were markedly elevated in patients with active systemic lupus erythematosus (SLE) compared to other autoimmune diseases or healthy controls. Notably, the frequency of Tph cells was positively correlated with the SLE disease activity index, serum IFN-α and serum IFN-λ1 in SLE patients. Additionally, we found that type III IFNs (IFN-λ1, IFN-λ2 and IFN-λ3) promote the differentiation of programmed cell death-1 (PD-1)+ CXCR5 -CD4+ T cells and enhance the secretion of IL-21, IFN-γ and CXCL13. IFN-λ1, like IFN-α, up-regulated the mRNA expression of IL21, IFNG, CXCL13, CD244, SLAMF7, GZMB, PRF1, CCR5 and PRDM1, whereas it down-regulated that of CXCR5 and BCL6, reflecting a Tph-related gene expression pattern. IFN-α in combination with IFN-λ1, IFN-λ2 or IFN-λ3 significantly increased the differentiation of PD-1+CXCR5- Tph-like cells and the secretion of Tph-related cytokines as compared with each IFN alone, suggesting a cooperative interaction. From these findings, it is highly probable that type III IFNs in addition to type I IFNs play a key role in the differentiation of Tph cells and that high levels of IFN-α and IFN-λ1 trigger the differentiation and expansion of Tph cells in SLE.

Role of interferons (IFNs) in the differentiation of T peripheral helper (Tph) cells.

T follicular helper (Tfh) cells and T peripheral helper (Tph) cells produce interleukin (IL)-21 and are thought to contribute to follicular and extra-follicular B-cell activation, respectively, in autoimmune diseases. It is known that programmed cell death-1 (PD-1)-positive CXCR5+ Tfh-like cells are differentiated from human naive CD4+ T cells by IL-12 plus transforming growth factor (TGF)-ß. However, it remains unclear what cytokines are required for Tph differentiation. In this study, we found that interferon (IFN)-α and IFN-ß reduce the frequency of Tfh-like cells under the IL-12 plus TGF-ß condition, whereas they promote generation of PD-1+CXCR5-CD4+ T cells and secretion of IL-21, IFN-γ and CXCL13. Intracellular cytokine staining and T-cell-B-cell co-culture studies indicated that IFN-α promotes generation of IL-21+IFN-γ +CXCR5-CD4+ T cells thereby enhancing B-cell helper function. By IFN-α treatment, the mRNA levels of IL21, IFNG, CXCL13, CD244, SLAMF7, GZMB and PRDM1 were significantly up-regulated but BCL6 mRNA expression was down-regulated, suggesting a Tph-related gene expression pattern. On the other hand, IL-2-neutralization increased mRNA levels of IL21, CXCL13 and CXCR5, retained BCL6, but showed no clear effect on IFNG or PRDM1. RNA sequencing analyses revealed that PD-1hiCXCR5-CD4+ T cells prepared from in vitro culture show a Tph-related gene expression pattern similar with that of PD-1hiCXCR5- Tph cells obtained from the blood of patients with systemic lupus erythematosus. From our findings, it is highly probable that type I IFNs play a key role in differentiation of Tph cells and trigger Tph cell expansion in autoimmune diseases.

Significant association of CX3CR1+CD8 T cells with aging and distinct clinical features in Sjögren's syndrome and IgG4-related disease.

OBJECTIVES: Recent studies have implicated cytotoxic CD4 and CD8 T cells in primary Sjögren's syndrome (pSS) and IgG4-related disease (IgG4-RD), but their association with immune aging and organ-specific clinical features remain unclear. CX3CR1 is expressed on cytotoxic CD4 and CD8 T cells. The aim of this study was to determine associations of peripheral CX3CR1+CD4 and CX3CR1+CD8 T cells with aging and clinical features. METHODS: Whole blood samples were freshly obtained from consecutive patients with active, treatment-naïve pSS (n=57), IgG4-RD (n=54), and healthy individuals (n=40) and analysed by flow cytometry for CX3CR1+CD4 and CX3CR1+CD8 proportions. Associations of those T cells with aging and clinical features were determined. RESULTS: CX3CR1+CD4 and CX3CR1+CD8 T cells selectively expressed perforin and granzyme B. Proportions of CX3CR1+CD4 and CX3CR1+CD8 T cells were significantly higher in pSS and IgG4-RD than in healthy individuals. Higher proportions of CX3CR1+CD8 T cells were associated with aging in pSS and IgG4-RD but not in healthy individuals. Sex differences were not associated with proportions of CX3CR1+CD8 T cells. Furthermore, patients with pSS with interstitial lung disease showed higher proportions of CX3CR1+CD8 T cells than those without interstitial lung disease. IgG4-RD patients with retroperitoneal fibrosis and/or aortitis exhibited higher proportions of CX3CR1+CD8 T cells compared with those with Mikulicz's disease. Moreover, proportions of CX3CR1+CD8 T cells were decreased following glucocorticoid treatment in paralleled with clinical improvements in IgG4-RD. CONCLUSIONS: CX3CR1+CD8 T cells might be involved in immune aging and distinct clinical phenotypes of patients with pSS or IgG4-RD.

Differences in the strength of inhibition of interleukin-6 signalling by subcutaneous sarilumab and tocilizumab in rheumatoid arthritis patients.

OBJECTIVES: To assess differences in the strength of inhibition of IL-6/STAT3 signalling induced by subcutaneously (sc) administered tocilizumab (TCZ) and sarilumab (SAR). METHODS: Data were collected on patients with rheumatoid arthritis (RA) who achieved low disease activity (Clinical Disease Activity Index [CDAI]≤10) following treatment with weekly or bi-weekly administration of 162 mg sc of TCZ (TCZ qw group, n=8; TCZ q2w group, n=8), bi-weekly doses of 200 mg sc of SAR (SAR q2w group, n=7), or MTX (n=8) as a control. The clinical characteristics of each group were collected, and the serum concentrations of IL-6 and soluble IL-6 receptor (sIL-6R) were measured using ELISA. Whole blood samples from each group were stimulated with 100 ng/ml of IL-6. The proportion of phosphorylated (p)STAT3-positive CD4+ T cells was measured using phosflow cytometric analysis. RESULTS: The proportion of pSTAT3-positive CD4+ T cells following stimulation with 100 ng/ml of recombinant human IL-6 was significantly different among the groups (median 1.8% [0.9-3.0] vs. 7.7% [2.9-8.0] vs. 12.5% [11.4-16.6] vs. 71.5% [68.0-78.5] for the TCZ qw, SAR q2w, TCZ q2w, and MTX control groups, respectively; p<0.01 for all comparisons). CONCLUSIONS: SAR 200 mg q2w showed significantly stronger inhibition of IL-6/STAT3 signalling than TCZ sc q2w but weaker inhibition than TCZ sc qw. The results of this study may be useful for adjusting the IL-6 blockade treatment for patients with RA.

Distinct impact of malignancy and allergy on the clinical and immunological features of IgG4-related disease.

OBJECTIVES: To clarify the clinical and immunological characteristics of IgG4-RD based on the underlying diseases. METHODS: Consecutive patients with IgG4-RD treated at Keio University Hospital between 2010 and 2021 were divided according to the presence of malignancy or allergy into three groups. The clinical characteristics and 56 immune cell subsets in the peripheral blood were compared among the groups. RESULTS: Among 123 patients, 18 (14.6%) had malignancy including 4 with allergy (malignancy group), 57 (46.3%) had allergy alone (allergy group), and 48 (39.0%) had neither (idiopathic group). In the malignancy group, the patients were older (70.1 vs. 54.4 vs. 64.9 years, p<0.001), male-dominant (83.3 vs. 42.1 vs. 54.2%, p=0.008), and had smoking habits (77.8 vs. 42.1 vs. 43.8%, p=0.02). They also had significant involvement of the aorta/large vessels (33.3 vs. 7.0 vs. 20.8%, p=0.02), while the patients in the allergy group tended to have orbital/lacrimal gland involvement. Remission and relapse rates were not different between the groups; however, overall survival was significantly poorer in the malignancy group (p=0.02). Comprehensive immunophenotyping of the peripheral blood revealed that the increase in CXCR5+CD2-double negative T cells and the decrease in naive CD8 T cells were characteristic of the malignancy group. CONCLUSIONS: The clinical and immunological phenotypes of IgG4-RD differ among those with underlying diseases.

Clinical and immunological effects of hydroxychloroquine in patients with active rheumatoid arthritis despite antirheumatic treatment.

OBJECTIVE: To investigate the efficacy and safety of hydroxychloroquine (HCQ) in patients with rheumatoid arthritis (RA). METHODS: Patients with active RA, despite conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), were recruited. HCQ was administered for 24 weeks, in addition to prior treatment. The primary endpoint was the proportion of American College of Rheumatology (ACR) 20 achievement at week 24, compared to that of a propensity score matched historical control group. RESULTS: Sixty patients were enrolled and administered HCQ. We also identified 276 patients as candidates for the historical control group. Propensity score matching yielded 46 patients in each group. The proportion of ACR20 achievements at week 24 was significantly higher in the HCQ group than that in the control group (54.4% vs. 28.3%, P = 0.007). The proportion of ACR50 and ACR70 achievement at week 24 were also higher in the HCQ group than those in the control group (ACR50, 30.4% vs. 4.3%, P = 0.006; ACR70, 17.4% vs. 0%, P = 0.005). Neither hydroxychloroquine retinopathy nor any new safety signal was observed during the study. CONCLUSION: The addition of HCQ to csDMARDs was effective, with no new safety signal in patients with RA.