Relevance of lymphocyte subsets to B cell-targeted therapy in systemic lupus erythematosus

Revolutionary Changes in the Management of Lupus Nephritis: Towards De-Glucocorticoid or No-Glucocorticoid

Glucocorticoids (GCs) possess potent anti-inflammatory and immunosuppressive properties and are used to treat various diseases, including systemic autoimmune rheumatic diseases, rheumatoid arthritis, and systemic lupus erythematosus (SLE). However, GCs are associated with several adverse events and are considered risk factors for infections and cardiovascular disorders; furthermore, their application as therapeutics has changed with recent progress in molecular-targeted therapies. Although GCs have been the mainstay of SLE treatment for more than 50 years, the latest European Alliance of Association for Rheumatology recommendations for the management of SLE in 2023 has significantly relegated the use of GCs and recommended that these be used as "bridging therapy" during periods of SLE disease activity. They also recommended the use of GC pulse therapy followed by relatively low doses of GCs even in patients with high disease-activity lupus nephritis, with a focus on the appropriate use of hydroxychloroquine, immunosuppressive drugs, and biological agents. This combination is essential for improving renal survival, minimizing flares, and reducing the side effects of GC. The GC dose was tapered to < 5 mg/day of prednisolone within half a year, maintained for 3 years, and then discontinued with the concomitant use of combination therapies. In contrast to non-renal SLE, the development of more potent molecular targeted therapies for lupus nephritis is required.

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.

Lymphocyte Subsets Are Associated with Disease Status in Neuromyelitis Optica Spectrum Disorders

OBJECTIVE

At present, studies on lymphocytes are mostly conducted on CD19+ B cells and CD27+ B cells in neuromyelitis optica spectrum disorders (NMOSDs), but the exact changes in lymphocyte subsets (CD19+ B cells, CD3+ T cells, CD4+ Th cells, CD8+ Ts cells, the CD4+/CD8+ ratio, and NK [CD56+ CD16] cells) have rarely been studied. This study aimed to assess lymphocyte subset changes in patients with NMOSD.

METHODS

We performed a cross-sectional study of consecutive patients with acute NMOSD (n = 41), chronic NMOSD (n = 21), and healthy individuals (n = 44). Peripheral blood samples were obtained upon admission, and lymphocyte subsets were analyzed by flow cytometry. Levels of lymphocyte subsets among 3 groups were compared and its correlation with the length of spinal cord lesions was analyzed.

RESULTS

The levels of peripheral blood CD19+ B cells were significantly higher in patients with acute and chronic NMOSD than in healthy controls (HCs) (17.91 ± 8.7%, 13.08 ± 7.562%, and 12.48 ± 3.575%, respectively; p < 0.001) and were positively correlated with the length of spinal cord lesions in acute NMOSD (r = 0.433, p < 0.05). The peripheral blood CD4+/CD8+ ratio was significantly lower in patients with acute NMOSD and chronic NMOSD than in HCs (1.497 ± 0.6387, 1.33 ± 0.5574, and 1.753 ± 0.659, respectively; p < 0.05), and the levels of peripheral blood NK (CD56+ CD16) cells were significantly lower in patients with acute and chronic NMOSD than in HCs (13.6 ± 10.13, 11.11 ± 7.057, and 14.7 [interquartile range = 9.28], respectively; p < 0.01).

CONCLUSIONS

The levels of certain subsets of peripheral blood lymphocytes are associated with disease status in NMOSD.

Clinical relevance of T follicular helper cells in systemic lupus erythematosus

INTRODUCTION

T helper cells regulate a variety of immune responses and are involved in the pathogenesis of infection, allergy and autoimmune diseases. T follicular helper (Tfh) cells, which induce B cell maturation, play an important role in the production of the extremely diverse autoantibodies found in systemic lupus erythematosus (SLE).

AREA COVERED

We provide an overview of the plasticity and diversity of Tfh cells in humans and their involvement in the pathology and pathogenesis of SLE. Our review outlines the potential of Tfh cells as a therapeutic target for SLE.

EXPERT OPINION

Tfh cells are involved in the pathogenesis of SLE based on their plasticity and diversity. Tfh cell differentiation and function are variably regulated by cytokines (IL-12, interferons, IL-2, etc), co-stimulatory molecules (ICOS, CD40L, OX40, etc), and intracellular signals (JAK-STAT, etc). Elucidation of the mechanisms underlying Tfh cell differentiation and function may lead to the development of new therapies for SLE.

Peripheral B Cell Subsets in Autoimmune Diseases: Clinical Implications and Effects of B Cell-Targeted Therapies

Antibody-secreting cells (ASCs) play a fundamental role in humoral immunity. The aberrant function of ASCs is related to a number of disease states, including autoimmune diseases and cancer. Recent insights into activated B cell subsets, including naïve B cell to ASC stages and their resultant cellular disturbances, suggest that aberrant ASC differentiation occurs during autoimmune diseases and is closely related to disease severity. However, the mechanisms underlying highly active ASC differentiation and the B cell subsets in autoimmune patients remain undefined. Here, we first review the processes of ASC generation. From the perspective of novel therapeutic target discovery, prediction of disease progression, and current clinical challenges, we further summarize the aberrant activity of B cell subsets including specialized memory CD11c^hiT-bet⁺ B cells that participate in the maintenance of autoreactive ASC populations. An improved understanding of subgroups may also enhance the knowledge of antigen-specific B cell differentiation. We further discuss the influence of current B cell therapies on B cell subsets, specifically focusing on systemic lupus erythematosus, rheumatoid arthritis, and myasthenia gravis.

The imbalance between regulatory and memory B cells accompanied by an increased number of circulating T-follicular helper cells in MOG-antibody-associated demyelination

OBJECTIVE

To explore the alteration of T and B lymphocyte subsets proportions in myelin oligodendrocyte glycoprotein (MOG)-antibody-associated demyelination.

METHODS

19 MOG-antibody-positive, 25 AQP4-antibody-positive and 25 double-negative NMOSD patients in the acute phase of the diseases were included in the study, as well as 29 healthy controls. The frequencies of different lymphocyte subsets, including CD19⁺CD27⁺ memory B cells, CD19⁺CD24^hiCD38^hi, and CD19⁺CD5⁺CD1d^hi regulatory B cells, IFN-γexpressing B cells, IL-10 expressing B cells and CD4⁺CXCR5⁺ICOS⁺T-follicular helper cells (T_FH) were measured via flow cytometry and compared among the four groups.

RESULTS

The frequencies of CD19⁺CD24^hiCD38^hi, CD19⁺CD5⁺CD1d^hi regulatory B cells as well as the IL-10 expressing B cells were significantly lower in the MOG-antibody-associated demyelination compared to the healthy controls, whereas the frequencies of CD19⁺CD27⁺ memory B cells were significantly higher in the MOG-antibody-positive group. The frequencies of T_FH were significantly higher in the MOG-antibody-positive group as compared to the healthy controls. No significant difference was detected in the above mentioned lymphocytic profile between the MOG-antibody-positive and the AQP4-antibody-positive groups.

CONCLUSIONS

The immuno-regulatory functions of B cells were significantly impaired whereas T_FH cells were markedly increased in the acute phase of MOG-antibody-associated demyelination. Despite having distinct clinical features, MOG-antibody-associated demyelination shared a similar lymphocytic profile with AQP4-antibody-positive NMOSD in the acute relapse phase.

The role of BAFF and APRIL in rheumatoid arthritis

Development and activation of B cells quickly became clear after identifying new ligands and receptors in the tumor necrosis factor superfamily. B cell-activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are the members of membrane proteins Type 2 family released by proteolytic cleavage of furin to form active, soluble homotrimers. Except for B cells, ligands are expressed by all such immune cells like T cells, dendritic cells, monocytes, and macrophages. BAFF and APRIL have two common receptors, namely TNFR homolog transmembrane activator and Ca2+ modulator and CAML interactor (TACI) and B cell-maturation antigen. BAFF alone can also be coupled with a third receptor called BAFFR (also called BR3 or BLyS Receptor). These receptors are often expressed by immune cells in the B-cell lineage. The binding of BAFF or APRIL to their receptors supports B cells differentiation and proliferation, immunoglobulin production and the upregulation of B cell-effector molecules expression. It is possible that the overexpression of BAFF and APRIL contributes to the pathogenesis of autoimmune diseases. In BAFF transgenic mice, there is a pseudo-autoimmune manifestation, which is associated with an increase in B-lymphocytes, hyperglobulinemia, anti-single stranded DNA, and anti-double-stranded DNA antibodies, and immune complexes in their peripheral blood. Furthermore, overexpressing BAFF augments the number of peripheral B220+ B cells with a normal proliferation rate, high levels of Bcl2, and prolonged survival and hyperactivity. Therefore, in this review article, we studied BAFF and APRIL as important mediators in B-cell and discussed their role in rheumatoid arthritis.

Type I and II interferons commit to abnormal expression of chemokine receptor on B cells in patients with systemic lupus erythematosus

Memory B cells are increased in systemic lupus erythematosus (SLE) cases, but the qualitative abnormalities and induction mechanism of these cells are unclear. Here, we subclassified B cells by their chemokine receptor expression and investigated their induction mechanism. The peripheral blood of patients with SLE showed higher levels of CXCR5^- and CXCR3⁺ B cells. CXCR5^-CXCR3⁺ B cell levels were elevated in patients with active SLE, which decreased with improving disease conditions. Interferon (IFN)-γ stimulation increased CXCR3 expression, whereas IFN-β stimulation reduced CXCR5 expression in B cells. Furthermore, CXCR5^-CXCR3⁺ B cells were induced by a combination of IFN-β and IFN-γ stimulation. Renal tissue examination of patients with active lupus nephritis confirmed the presence of CD19⁺CXCR3⁺ B cells. Collectively, the results revealed qualitative abnormalities accompanying reduced CXCR5 expression via type I IFN and enhanced CXCR3 expression via type II IFN in SLE, suggesting their involvement in B cell infiltration into tissues and inflammatory pathogenesis.

The use of biologics and small molecules in pregnant patients with rheumatic diseases

INTRODUCTION

Biological agents have radically changed the prognosis of rheumatic patients. Current evidence demonstrates that tight disease control during pregnancy is mandatory to minimize adverse outcome risk. As the new therapeutic tools are pivotal to maintain appropriate disease activity, it is timely to review available evidence about the safety of biologics and small molecules in pregnancy. Areas covered: A comprehensive literature review has been performed, reporting available data about the passage into breast milk, rate of pregnancy loss and fetal malformations, and long-term complications due to in utero exposure to biological agents and small molecules. Expert commentary: Data about the safety of agents against tumor necrosis factor in pregnancy are reassuring. Even rituximab, tocilizumab, belimumab, ustekinumab, secukinumab, and abatacept have not been associated with an increased rate of fetal abnormalities or adverse pregnancy outcome. Experience with small molecules is too small to draw any conclusion. Even if further data are warranted to define the possible long-term effects of in utero biologic exposure on the infant immune system development, it is reasonable to speculate that in the next future the use of biologics during pregnancy will continue to expand, at least when maternal benefit justifies the potential risk to the fetus.

DNA-reactive B cells in lupus

IgG anti-DNA antibodies are both diagnostic and pathogenic for systemic lupus erythematosus (SLE). They contribute to tissue inflammation through direct tissue binding and to systemic inflammation through activation of Toll-like receptors by nucleic acid-containing immune complexes. IgG DNA-reactive antibodies originate when B cell tolerance mechanisms are impaired. The heterogeneous immune perturbations in SLE lead to the survival and activation of DNA-reactive B cells in various B cell subsets at distinct stages of B cell maturation and differentiation. We propose that the spectrum of B cell alterations and failed tolerance mechanisms for DNA-reactive B cells in lupus patients is best understood by studying genetic risk alleles. This implies that the B cells producing IgG anti-DNA antibodies and the failed tolerance mechanisms(s) will differ across patients. A better understanding of these differences should lead to better patient stratification, improved outcomes of clinical trials, and the identification of novel therapeutic targets.

BAFF- and APRIL-targeted therapy in systemic autoimmune diseases

B cells play a pivotal role in autoimmunity not only by producing pathogenic autoantibodies but also by modulating immune responses via the production of cytokines and chemokines. The B cell-activating factor/a proliferation-inducing ligand (BAFF/APRIL) system promotes B cell survival and differentiation and thus plays a prominent role in the pathogenesis of autoimmune diseases. Currently, BAFF and APRIL inhibitors are in clinical trials for systemic lupus erythematosus with significant efficacy. However, several studies have demonstrated the efficacy of the BAFF/APRIL blockade which showed considerable variability in the response to B cell-targeted therapy. This may indicate substantial heterogeneity in the pathogenesis of autoimmune diseases. Therefore, objective markers that can predict the effect of BAFF/APRIL-blocking agents could be valuable to the precision medicine linked clinically and to cost-effective therapy.

The immune balance between memory and regulatory B cells in NMO and the changes of the balance after methylprednisolone or rituximab therapy

We aim to explore the impacts of high dose methylprednisolone therapy (HDMT) and rituximab on circulating B cells in NMO patients. Twenty-two NMO patients in the acute relapse phase were treated with HDMT and 9 patients in the remission stage were treated with rituximab. The frequencies of circulating CD19(+)CD27(+) memory B cell (Bmem), CD19(+)CD24(high)CD38(high) regulatory B cell (Breg) and the B cell production of interleukin (IL)-10 and interferon (IFN)-γ were monitored by flow cytometry before and after the treatment. The frequencies of circulating Bregs and the B cell IL-10 production were significantly lower in NMO patients before HDMT compared to healthy controls. Two weeks' HDMT further reduced the frequencies of Bregs while increased the frequencies of Bmems, which steered the numerical balance between Bmem and Breg in favor of Bmem. Meanwhile, HDMT significantly inhibited the B cell IFN-γ expression. Rituximab exerted its effect through B cell elimination and subsequent B cell repopulation which was characterized by the predominance of Bregs, restored the numerical balance between Breg and Bmem back to an advantageous "Breg>Bmem" status. Therefore, HDMT and rituximab had basically different impacts on B cells in NMO.