Lymphocyte phenotype and its application to precision medicine in systemic autoimmune diseases✰

Pathophysiology and stratification of treatment-resistant rheumatoid arthritis

Early diagnosis and timely therapeutic intervention are clinical challenges of rheumatoid arthritis (RA), especially for treatment-resistant or difficult-to-treat patients. Little is known about the immunological mechanisms involved in refractory RA. In this review, we summarize previous research findings on the immunological mechanisms of treatment-resistant RA. Genetic prediction of treatment-resistant RA is challenging. Patients with and without anti-cyclic citrullinated peptide autoantibodies are considered part of distinct subgroups, especially regarding long-term clinical prognosis and treatment responses. B cells, T cells and other immune cells and fibroblasts are of pathophysiological importance and are associated with treatment responses. Finally, we propose a new hypothesis that stratifies patients with RA into two subgroups with distinct immunological pathologies based on our recent immunomics analysis of RA. One RA subgroup with a favorable prognosis is characterized by increased interferon signaling. Another subgroup with a worse prognosis is characterized by enhanced acquired immune responses. Increases in dendritic cell precursors and diversified autoreactive anti-modified protein antibodies may have pathophysiological roles, especially in the latter subgroup. These findings that improve treatment response predictions might contribute to future precision medicine for RA.

What are the hot topics in Japanese rheumatology? Go above and beyond

Japanese rheumatology and immunology have contributed to progress in the field and advancement of rheumatology, including postmarketing surveillance, development of IL-6-targeting therapy and concept of drug tapering, have accelerated in the 21st century. The 67th Annual Scientific Meeting of the Japan College of Rheumatology, held on Fukuoka on 24 April 2023-26 April 2023, will go ahead and beyond such an advancement. Profound discussion on future perspectives such as precision medicine, the elucidation of pathology and genome-based drug discovery by multilayered integration with various types of omics information, information on metabolome and proteome of blood metabolites, and database of target proteins and compounds for drug discovery will be discussed.

Association between early immunophenotypic changes and therapeutic response of belimumab in patients with systemic lupus erythematosus

Belimumab is a therapeutic medication that inhibits the B-cell-activating factor (BAFF) used for systemic lupus erythematosus (SLE); however, the response sometimes varies among individuals, even when patients are stratified based on general clinical characteristics. Therefore, we focused on immunological phenotypic changes with belimumab, investigated their association with subsequent clinical courses, and sought to identify relevant immunological indicators to stratify patients who would benefit from belimumab. We assessed changes in B and T cell phenotypes, as well as BAFF-related factors, such as levels of BAFF and a proliferation-inducing ligand, and expression of three BAFF receptors: BAFF receptor (BAFF-R), B-cell maturation antigen (BCMA), transmembrane activator and cyclophilin ligand interactor (TACI), in 19 patients with SLE who were treated with belimumab before and 3 months after treatment. First, to visualize patterns in complex and diverse data, we summarized B cell changes such as subsets and BAFF receptor expressions into two axes, the first and second principal components (PC1 and PC2), and characterized broad phenotypic changes by cluster analysis. Next, we evaluated whether the B cell changes represented by PC1 and PC2 were associated with other concurrent phenotypic changes, baseline factors, and treatment response at 6 months. We found that lower PC2, indicating increased BAFF-R expression and decreased percentage of naïve B cells, was associated with a subsequent therapeutic response at 6 months (odds ratio 5.3, 95% confidence interval 1.2-24, p = .031). Furthermore, higher percentages of effector memory CD3+CD4+ T cells at baseline were associated with lower PC2 and therapeutic response. Further analysis revealed that increased PC1, as reflected by increased BCMA and TACI expression and an increase in the percentage of class-switched memory B cells, was associated with both T and B cell activation. Although belimumab is a B-cell targeted therapy, it can also influence T-cell phenotypes. Thus, early B cell changes could be used to predict treatment response, and their changes could be predicted from baseline T cell phenotypes, indicating the importance of B and T cell interactions.

Pathological relevance and treatment perspective of JAK targeting in systemic lupus erythematosus

INTRODUCTION

The pathogenesis of systemic lupus erythematosus (SLE) involves abnormalities in both acquired and innate immune system, which is mediated by numerous cytokines. Janus kinase (JAK) plays important roles in the signaling pathways of those cytokines and is an attractive therapeutic target for SLE. Currently, multiple clinical trials using JAK inhibitors with different selectivities for JAK family proteins are being conducted in SLE.

AREA COVERED

In this article, we provide an overview of the pathological relevance of JAK and the clinical implications of JAK inhibitors in SLE based on recent reports.

EXPERT OPINION

JAK inhibitors have the potential to modulate various immune networks through a variety of mechanisms, potentially regulating the complex immunopathogenesis in SLE. SLE is a clinically and immunologically heterogeneous disease; therefore, precision medicine is required to maximize the efficacy of JAK inhibitors. Further studies are needed to determine their risk-benefit ratio and selection of the most appropriate patients for JAK inhibitors.

Janus kinase-targeting therapies in rheumatology: a mechanisms-based approach

The four Janus kinase (JAK) proteins and seven signal transducer and activator of transcription (STAT) transcription factors mediate intracellular signal transduction downstream of cytokine receptors, which are implicated in the pathology of autoimmune, allergic and inflammatory diseases. Development of targeted small-molecule therapies such as JAK inhibitors, which have varied selective inhibitory profiles, has enabled a paradigm shift in the treatment of diverse disorders. JAK inhibitors suppress intracellular signalling mediated by multiple cytokines involved in the pathological processes of rheumatoid arthritis and many other immune and inflammatory diseases, and therefore have the capacity to target multiple aspects of those diseases. In addition to rheumatoid arthritis, JAK inhibition has potential for treatment of autoimmune diseases including systemic lupus erythematosus, spondyloarthritis, inflammatory bowel disease and alopecia areata, in which stimulation of innate immunity activates adaptive immunity, leading to generation of autoreactive T cells and activation and differentiation of B cells. JAK inhibitors are also effective in the treatment of allergic disorders, such as atopic dermatitis, and can even be used for the COVID-19-related cytokine storm. Mechanism-based treatments targeting JAK-STAT pathways have the potential to provide positive outcomes by minimizing the use of glucocorticoids and/or non-specific immunosuppressants in the treatment of systemic immune-mediated inflammatory diseases.

Recent progress in treatments of rheumatoid arthritis: an overview of developments in biologics and small molecules, and remaining unmet needs

Through treatment with biological DMARDs (bDMARDs) or targeted synthetic (tsDMARDs) such as Janus kinase (JAK) inhibitors in addition to MTX, clinical remission has become a realistic therapeutic goal for the majority of patients with RA, and sustained remission facilitates prevention of joint damage and physical dysfunction. Long-term safety and sustained inhibition of structural changes and physical dysfunction by bDMARDs have been reported. The development of next-generation bDMARDs and expansion of their indications to various autoimmune diseases are expected. Five JAK inhibitors show comparable efficacy to bDMARDs, and the latest ones are effective for overcoming difficult-to-treat RA regardless of prior medications. Patients treated with JAK inhibitors should be adequately screened and monitored for infection, cardiovascular disorders, thrombosis, malignancies and so on. Advances in therapeutic strategies, including the differential use of therapeutic drugs and de-escalation of treatment after remission induction, are prioritized.

Efficacy and Safety of High-Dose of Mycophenolate Mofetil Compared With Cyclophosphamide Pulse Therapy as Induction Therapy in Japanese Patients with Proliferative Lupus Nephritis

OBJECTIVE

To clarify the effectiveness and safety of induction therapy with mycophenolate mofetil (MMF) in patients with lupus nephritis (LN).

METHODS

Patients with LN administered MMF (n = 35) or IVCY (n = 25) plus high-dose corticosteroids between July 2015 and June 2020 were included. MMF was increased from 2 g/day to 3 g/day, with no adverse events (AEs). The primary endpoint was the 6-month renal remission rate. Secondary endpoints were retention rate and AEs.

RESULTS

There were no significant differences in age, sex, disease duration, renal histological type, SLEDAI, and UPCR between the two groups. Twenty-six patients (74%) continued with MMF therapy, whereas twelve (48%) completed six IVCY courses. The retention rate was significantly higher in the MMF than in the IVCY group (p = 0.048). Twenty-four and fourteen patients in MMF and IVCY groups, respectively, achieved renal remission with insignificant differences. Grade 3 or higher AEs were observed in eight and fourteen patients in the MMF and IVCY groups, respectively (p = 0.014).

CONCLUSIONS

The efficacy of high-dose MMF was comparable to that of IVCY in Japanese patients with proliferative LN, with fewer AEs and a higher retention rate than IVCY, suggesting the high tolerability of MMF.

Cellular and molecular diversity in spondyloarthritis

The spondyloarthritides are a cluster of inflammatory rheumatic diseases characterized by different diagnostic entities with heterogeneous phenotypes. The current classification system groups spondyloarthritis patients in two main categories, axial and peripheral spondyloarthritis, providing a framework wherein the clinical picture guides the treatment. However, the heterogeneity of the clinical manifestations of the pathologies, even when residing in the same group, highlights the importance of analyzing the smallest features of each entity to understand how different cellular subsets evolve, what the underlying mechanisms are and what biological markers can be identified and validated to evaluate the stage of disease and the corresponding efficacy of treatments. In this review, we will focus mostly on axial spondyloarthritis, report current knowledge concerning the cellular populations involved in its pathophysiology, and their molecular diversity. We will discuss the implications of such a diversity, and their meaning in terms of patients' stratification.

T Cells in Systemic Lupus Erythematosus

T-cell dysregulation has been implicated in the loss of tolerance and overactivation of B cells in systemic lupus erythematosus (SLE). Recent studies have identified T-cell subsets and genetic, epigenetic, and environmental factors that contribute to pathogenic T-cell differentiation, as well as disease pathogenesis and clinical phenotypes in SLE. Many therapeutics targeting T-cell pathways are under development, and although many have not progressed in clinical trials, the recent approval of the calcineurin inhibitor voclosporin is encouraging. Further study of T-cell subsets and biomarkers of T-cell action may pave the way for specific targeting of pathogenic T-cell populations in SLE.

The growing role of precision medicine for the treatment of autoimmune diseases; results of a systematic review of literature and Experts' Consensus

Autoimmune diseases (AIDs) share similar serological, clinical, and radiological findings, but, behind these common features, there are different pathogenic mechanisms, immune cells dysfunctions, and targeted organs. In this context, multiple lines of evidence suggest the application of precision medicine principles to AIDs to reduce the treatment failure. Precision medicine refers to the tailoring of therapeutic strategies to the individual characteristics of each patient, thus it could be a new approach for management of AIDS which considers individual variability in genes, environmental exposure, and lifestyle. Precision medicine would also assist physicians in choosing the right treatment, the best timing of administration, consequently trying to maximize drug efficacy, and, possibly, reducing adverse events. In this work, the growing body of evidence is summarized regarding the predictive factors for drug response in patients with AIDs, applying the precision medicine principles to provide high-quality evidence for therapeutic opportunities in improving the management of these patients.

Anifrolumab, a monoclonal antibody to the type I interferon receptor subunit 1, for the treatment of systemic lupus erythematosus: an overview from clinical trials

Chronic activation of the type I interferon (IFN) pathway plays a critical role in systemic lupus erythematosus (SLE) pathogenesis. Anifrolumab is a human monoclonal antibody to the type I IFN receptor subunit 1, which blocks the action of type I IFNs. Two phase 3 studies (TULIP-1 and TULIP-2) and a phase 2b study (MUSE) provide substantial evidence for the efficacy and safety of anifrolumab for moderately to severely active SLE. In all three studies, monthly intravenous anifrolumab 300 mg was associated with treatment differences >16% compared with placebo at Week 52 in British Isles Lupus Assessment Group-based Composite Lupus Assessment response rates. The combined data across a range of other clinically significant endpoints (e.g. oral corticosteroid reduction, improved skin disease, flare reduction) further support the efficacy of anifrolumab for SLE treatment. The safety profile of anifrolumab was generally similar across all studies; serious adverse events occurred in 8-16% and 16-19% of patients receiving anifrolumab and placebo, respectively. Herpes zoster incidence was greater with anifrolumab (≤7%) vs placebo (≤2%). Evidence from these clinical trials suggests that in patients with active SLE, anifrolumab is superior to placebo in achieving composite endpoints of disease activity response and oral corticosteroid reduction.

Rheumatoid arthritis

Rheumatoid arthritis is an autoimmune inflammatory disease primarily characterized by synovitis which is accompanied by extra-articular organ involvement, such as interstitial pneumonia, in addition to clinical symptoms including pain, swelling, stiffness of multiple joints, fever, and malaise. Joint destruction progresses soon after the onset, and once the affected joints are deformed, the development of irreversible physical dysfunction is noted. Thus, proper diagnosis and treatment are required from the early stages of the disease. Although palliative therapy with glucocorticoids and anti-inflammatory drugs had been used, disease-modifying antirheumatic drugs (DMARDs) are currently used to suppress immune abnormalities and to control disease activity. DMARDs are classified into different groups, such as conventional synthetic DMARD, targeted synthetic DMARD, and biologic DMARD. The appropriate use of these drugs has allowed remission to be the therapeutic goal in all patients. By maintaining remission, these drugs have also been shown to prevent the progression of joint destruction and physical dysfunction over a long period. The advent of molecular-targeted therapies has allowed for the use of treatments based on pathological mechanisms, and such therapeutic strategies have also been applied to the treatment of various autoimmune inflammatory diseases. In the future, safer and more effective treatments, therapeutic strategies aimed at drug holidays or cure, and the introduction of precision medicine are expected.

The approach to precision medicine for the treatment of psoriatic arthritis

In rheumatic diseases, advances in biological molecular-targeted therapies have brought remarkable progress in treatment, but the molecular and clinical heterogeneity of the diseases can often pose a treatment challenge. In psoriatic arthritis, each patient exhibits various symptoms, and some may be resistant to treatment. It is difficult to improve all of these various symptoms simultaneously with the use of limited drugs. Therefore, precision medicine is an urgent concern that is required to overcome this problem. However, few studies focus on the precision medicine in rheumatic disease including psoriatic arthritis. We explored the potential of precision medicine in which patients with psoriatic arthritis are stratified by lymphocyte flow cytometry to select specific biologics. Selecting specific biologics according to different immunophenotypes of peripheral blood lymphocytes in psoriatic arthritis was shown to produce high therapeutic responses; in other words, the potential of precision medicine was suggested. The peripheral blood lymphocyte analysis can be applied to many other rheumatic diseases presenting various clinical features, such as spondyloarthritis and systemic lupus erythematous. We should shed light on the precision medicine not only in the psoriatic arthritis also in the other rheumatic disease.

Peripheral Blood Lymphocyte Phenotype Differentiates Secondary Antibody Deficiency in Rheumatic Disease from Primary Antibody Deficiency

The phenotype of primary immunodeficiency disorders (PID), and especially common variable immunodeficiency (CVID), may be dominated by symptoms of autoimmune disorders. Furthermore, autoimmunity may be the first manifestation of PID, frequently preceding infections and the diagnosis of hypogammaglobulinemia, which occurs later on. In this case, distinguishing PID from hypogammaglobulinemia secondary to anti-inflammatory treatment of autoimmunity may become challenging. The aim of this study was to evaluate the diagnostic accuracy of peripheral blood lymphocyte phenotyping in resolving the diagnostic dilemma between primary and secondary hypogammaglobulinemia. Comparison of B and T cell subsets from patients with PID and patients with rheumatic disease, who developed hypogammaglobulinemia as a consequence of anti-inflammatory regimes, revealed significant differences in proportion of naïve B cells, class-switched memory B cells and CD21^low B cells among B cells as well as in CD4⁺ memory T cells and CD4⁺ T follicular cells among CD4⁺ T cells. Identified differences in B cell and T cell subsets, and especially in the proportion of class-switched memory B cells and CD4⁺ T follicular cells, display a considerable diagnostic efficacy in distinguishing PID from secondary hypogammaglobulinemia due to anti-inflammatory regimens for rheumatic disease.

State-of-the-art treatment of systemic lupus erythematosus

As glucocorticoids and immunosuppressive drugs are non‐specific therapeutic agents that cause many adverse reactions, the development of biologicals aiming to control specific molecular targets is anticipated for the treatment of systemic lupus erythematosus (SLE). The antibody targeting B cell‐activating factor belonging to the tumor necrosis factor family (BAFF) belimumab was the first biological approved for SLE. At present, many biologicals, such as anifrolumab (anti‐type I interferon receptor antibody) and ustekinumab (antibody against interleukin 12/23 [p40]), are in clinical trials. Thus, successful treatments with biologicals targeting “bridging cytokines” produced by dendritic cells, which form a bridge between the innate and acquired immune/autoimmune systems, is of particular interest. Moreover, a phase IIb clinical trial of baricitinib, a low‐molecular‐weight compound targeting Janus kinase 1/2, in patients with SLE revealed that baricitinib was significantly more effective for relieving arthritis and skin manifestations than placebo, and the trial met the primary endpoint. In the future, it is expected that drugs with better efficacy and safety profiles will be used to apply therapeutic strategies, such as precision medicine, in which different molecular target drugs are used for patients classified by their conditions, and to set a therapeutic goal of the discontinuation of glucocorticoids.