The efficacy of novel B cell biologics as the future of SLE treatment: a review

State of the art: the treatment of systemic lupus erythematosus

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with dysregulated cells in the immune system. The disease affects organs like kidneys, nervous system, joints, and skin. To manage SLE effectively, novel treatments targeting immune system components have been developed. This review investigates the therapeutic potential of existing targeted therapies and explores future innovative approaches for well tolerated, personalized treatment.

RECENT FINDINGS

SLE treatment involves cytokine targets and specific immunologic pathways, with even small molecules involved.

SUMMARY

The advanced therapeutic options in SLE management give clinicians more tools to control disease activity according to personalized medicine.

Bruton's Tyrosine Kinase in Ankylosing Spondylitis

STUDY DESIGN

Prospective case-control study.

OBJECTIVE

To explore the role of Bruton's tyrosine kinase (BTK) in ankylosing spondylitis (AS).

SUMMARY OF BACKGROUND DATA

AS substantially affects patients, impairing the range of motion in the whole spine and peripheral joints, as well as overall quality of life. However, surveillance for this condition is limited, and biomarkers that can predict disease activity are not well documented.

PATIENTS AND METHODS

The expression of the BTK gene in peripheral blood mononuclear cells (PBMCs) was measured using flow cytometry and real-time quantitative polymerase chain reaction in 36 patients with AS and 30 healthy controls. Demographic features, Ankylosing Spondylitis Disease Activity Score-C-reactive protein (CRP) based, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, HLA-B27, erythrocyte sedimentation rate (ESR), and CRP were evaluated to identify factors associated with BTK expression. Analyses were performed using the Spearman rank correlation test for continuous data, the χ 2 test for categorical data, and that between continuous and dichotomous variables was measured using a point-biserial correlation test. The area under the curve of the receiver operating characteristic curve was used to assess the performance of each candidate biomarker.

RESULTS

BTK gene expression was significantly higher in patients with AS than in controls ( P = 0.026) according to quantitative polymerase chain reaction results. BTK Y223 was also high in CD19 + PBMCs from patients with AS, with CD 19+ BTK Y223+high cells being significantly positively correlated to ESR, CRP, and Ankylosing Spondylitis Disease Activity Score. A negative association was observed between BTK expression and the chest expansion distance. The area under the curve for CD 19+ BTK Y223+ was larger than that for ESR, but CRP still had the largest area.

CONCLUSIONS

BTK expression was higher in PBMCs from patients with AS when compared with controls, and was associated with a higher disease activity index, inflammatory reactants, and arthritis and extra-articular manifestations. These findings suggest that BTK expression may play a crucial role in the inflammatory process in individuals with AS.

Systemic risk factors of retinopathy in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the risk factors of lupus retinopathy (LR) in patients with systemic lupus erythematosus (SLE).

METHODS

This is a retrospective, cross-sectional study. LR patients admitted at Peking Union Medical College Hospital from June 2013 to April 2023 were reviewed. Age- and gender-matched SLE patients without retinopathy were selected as controls. Medical records including clinical manifestations, laboratory data and ophthalmic examination were collected. Univariate and multivariate logistic regression analyses were conducted.

RESULTS

One hundred and twelve LR patients (198 eyes) were included, with 12 cases (14 eyes) presenting with retinal macrovascular obstruction, and 100 cases (184 eyes) only exhibiting microvasculopathy. Multivariate analysis indicated the presence of haemolytic anaemia, decreased haemoglobin (HGB) and higher relative percentage of neutrophils were independent risk factors for LR (p < 0.05). The first two were also risk factors for retinal microvasculopathy, whereas secondary antiphospholipid syndrome (APS) was for macrovascular obstruction. In male group, LR had significant associations with decreased HGB, no matter which types of retinopathy (p < 0.05). In female group, LR was significantly associated with haemolytic anaemia, presence of antiphospholipid antibodies, decreased white blood cells and relative high percentage of neutrophils. Specifically, haemolytic anaemia (p = 0.002) was significantly associated with retinal microvasculopathy, and APS (p = 0.003) was significantly associated with macrovasculature obstruction.

CONCLUSION

LR was related to haemolytic anaemia, decreased HGB levels and higher percentage of neutrophils. Retinal microvasculopathy accounted for most cases and macrovasculature obstructions were rare. Male and female patients have distinct risk factors. Early ophthalmic screening is recommended especially for those with risk factors of LR.

Metabolic Modulators in Cardiovascular Complications of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial disorder with contributions from hormones, genetics, and the environment, predominantly affecting young women. Cardiovascular disease is the primary cause of mortality in SLE, and hypertension is more prevalent among SLE patients. The dysregulation of both innate and adaptive immune cells in SLE, along with their infiltration into kidney and vascular tissues, is a pivotal factor contributing to the cardiovascular complications associated with SLE. The activation, proliferation, and differentiation of CD4+ T cells are intricately governed by cellular metabolism. Numerous metabolic inhibitors have been identified to target critical nodes in T cell metabolism. This review explores the existing evidence and knowledge gaps concerning whether the beneficial effects of metabolic modulators on autoimmunity, hypertension, endothelial dysfunction, and renal injury in lupus result from the restoration of a balanced immune system. The inhibition of glycolysis, mitochondrial metabolism, or mTORC1 has been found to improve endothelial dysfunction and prevent the development of hypertension in mouse models of SLE. Nevertheless, limited information is available regarding the potential vasculo-protective effects of drugs that act on immunometabolism in SLE patients.

Clinical efficacy of plasma exchange in systemic lupus erythematosus during pregnancy

OBJECTIVE

To investigate the clinical efficacy of plasma exchange (PE) with or without prednisone and hydroxychloroquine (HCQ) for the treatment of systemic lupus erythematosus (SLE) during pregnancy.

METHODS

The clinical characteristics of 14 pregnant women with SLE admitted to our hospital were retrospectively analyzed, including 7 only treated with prednisone and HCQ (non-PE group) as well as 7 combined PE (PE group). The delivery situations of 14 patients were recorded. Data like erythrocyte sedimentation rate (ESR), urine protein, platelet count, and SLEDAI scores were compared between two groups before treatment and 3, 6, and 12 months after delivery.

RESULTS

Three patients in the non-PE group ended in miscarriage while all patients in the PE group were delivered successfully. Eleven successfully delivered fetuses in the two groups were healthy, and the Apgar scores were over 8. The ESR of the PE group was significantly lower than that of the non-PE group at 6 and 12 months after delivery, while there was no statistical difference in ESR between the two groups before treatment and 3 months after delivery. The ESR and urine protein were significantly higher in the non-PE group at months 3, 6, and 12 postpartum. There was a significant decrease in disease activity postpartum in the PE group compared to predelivery disease activity. The change in platelet counts between the two groups significantly increased over time in the PE group, while SLEDAI scores decreased.

CONCLUSIONS

The combination of PE and oral prednisone and HCQ is possibly a more effective treatment than oral prednisone and HCQ alone for patients with active SLE during pregnancy. This treatment option reduces pregnancy loss and promotes the patients' postpartum condition to a certain extent.

Appendicitis is associated with an increased risk of systemic lupus erythematosus: a nationwide, population-based, case-control study

OBJECTIVE

To examine the association between appendicitis and the risk of systemic lupus erythematosus (SLE).

METHODS

Using claims data from the 2003-2013 Taiwanese National Health Insurance Research Database, we selected 6054 patients with newly diagnosed SLE from 2007 to 2012 and 36,324 age-, sex- and year of SLE diagnosis date-matched (1:6) non-SLE controls. After controlling for potential confounders, a multivariable conditional logistic regression model was used to calculate the adjusted odds ratio (aOR) with 95% confidence interval (CI) for the association of appendicitis history with SLE. Sensitivity analyses were conducted using various definitions of appendicitis. Subgroup analyses were conducted to examine possible modification effects by age, gender, level of urbanization, income and Charlson Comorbidity Index (CCI).

RESULTS

The average age of patients was 38 years old in both groups. The proportion of females was 86.5%. 75 (1.2%) of SLE cases and 205 (0.6%) of non-SLE controls had appendicitis history before the index date. After adjusting for potential confounding factors, appendicitis was associated with a higher risk of SLE (aOR, 1.84; 95% CI, 1.34-2.52), and such association remained robust after variation of appendicitis definition. No significant modification effects were found for the association between appendicitis and SLE by age, gender, urbanization level, income and CCI.

CONCLUSION

This nationwide, population-based case-control study demonstrates an association between appendicitis and incident SLE. Lack of individual smoking status is a major limitation. Key Points • Appendicitis was significantly associated with an increased risk of SLE. • Such association remained robust using various definitions of appendicitis.

Relative CTLA-4, PTPN-22, and interleukin 37 mRNA expressions in patients with lupus nephritis

OBJECTIVES

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by T-cell immune-dysregulation and loss of tolerance to self-antigens. CTLA-4 and PTPN-22 are involved in the inhibition of T-lymphocytes activation. IL-37 is an anti-inflammatory cytokine that suppresses innate immunity. The relative expression of CTLA-4, IL-37 and PTPN-22 were evaluated as negative regulators of immune response in SLE patients, lupus nephritis (LN) and disease activity.

METHODS

Real-Time PCR was performed to determine relative CTLA-4, IL-37, and PTPN-22 mRNA expressions in fifty-eight SLE patients, who were divided into two groups: 29 SLE patients without nephritis and 29 patients with LN, versus fifty controls.

RESULTS

There was a significantly high-expression of CTLA-4 and IL-37 genes in SLE patients compared to controls (p=0.005; 0.018 respectively). There was no difference in relative PTPN-22 mRNA expression between the SLE patients and controls. Relative CTLA-4 mRNA expression decreased in LN patients (p=0.044), however, relative IL-37 mRNA over-expressed in LN patients (p=0.001) compared to those without LN. There was a significant over-expression of relative IL-37 andPTPN-22 mRNA in active SLE patients. But, there was a non-significant difference in CTLA-4 expression with disease activity. Regression analysis revealed patients with relative IL-37 mRNA over-expression had two times more to develop lupus nephritis (OR=1.906, 95% CI=1.218-2.983, p=0.005).

CONCLUSIONS

Relative IL-37mRNA expression was elevated in SLE patients and associated with renal involvement and disease activity. It could be considered as a new promising predicting tool for LN. Relative PTPN-22 mRNA expression was correlated with disease activity only in SLE patients.

Sequential treatment of rituximab and belimumab in thrombotic thrombocytopenia purpura associated with systemic lupus erythematous: A respective case series and literature review

INTRODUCTION

Thrombotic thrombocytopenia purpura (TTP) associated with systemic lupus erythematous (SLE), features the appearance of inhibitory autoantibodies against ADAMTS13. Rituximab and belimumab (BEL), as both targeting B cells, seem to be an optimal therapy to induce clinical remission, prevent relapse of disease and contribute to glucocorticoid induction. However, the clinical outcome of SLE-TTP treated with sequential therapy between rituximab and BEL remain elusive.

CASE SERIES

We reported the clinical outcomes of 4 patients diagnosed with SLE-TTP who were administrated a combination of corticosteroids, plasma exchange, and rituximab at stage of induction. BEL was utilized to rapidly reduce the reliance on these agents and prevent relapse of TTP at maintenance stage. Ultimately, 4 patients fully recovered with a SLE Disease Activity Index score of 0 and reached the goal at dose of prednisolone <7.5 mg/d without relapse.

CONCLUSION

Sequential treatment of rituximab and BEL could be an encouraging approach in treatment of SLE-TTP and rapid glucocorticoid reduction.

Retinal thickness and microvascular alterations in the diagnosis of systemic lupus erythematosus: a new approach

BACKGROUND

To investigate the differences of retinal thickness (RT) and superficial vascular density (SVD) between patients with systemic lupus erythematosus (SLE) and healthy controls using optical coherence tomography angiography (OCTA).

METHODS

Individuals with SLE (n=12; 24 eyes) and healthy controls (n=12; 24 eyes) were recruited to this study. The study protocol was in accordance with the tenets of the Declaration of Helsinki (as revised in 2013). The monocular best-corrected visual acuity (BCVA) was determined using a Snellen eye chart. Each image was segmented into 9 early treatment diabetic retinopathy study subregions, within which the macular RT and SVD were measured by OCTA. The vascular perfusion area as a percentage of the measured area was considered to be the vascular density.

RESULTS

The mean age of the SLE group was 33.80±9.49 years, and the mean age of the control group was 33.20±9.41 years. The mean duration of SLE was 4.33±2.67 years. The BCVA was significantly different between the SLE and control groups (0.17±0.20 vs. 0.05±0.07, respectively; P=0.021). In the SLE group, inner RT was reduced in the outer superior and temporal regions and full RT was reduced in the outer temporal region, compared with the control group (P<0.05). In the outer temporal region, the area under the receiver operating characteristic curve (AUC) for the inner RT was 0.805 [95% confidence interval (CI): 0.674 to 0.935], and the full RT was 0.828 (95% CI: 0.701 to 0.955). Thinning of RT was negatively correlated with erythrocyte sedimentation rate (ESR) in the inner retina at the outer temporal and outer superior regions and the full retina at the outer temporal region (P<0.05). The SVD was significantly lower in SLE participants than in controls in the central region, all 4 inner quadrants, and 4 outer quadrants (P<0.05). In the SLE group, SVD was positively correlated with inner RT in the outer superior region, inner RT, and full RT in the outer temporal region (P<0.05).

CONCLUSIONS

Variations in RT within the macular area may affect visual acuity. The OCTA measurement of RT may be a potential marker for diagnosis of SLE and an indicator of its inflammatory activity.

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.

Bacteroides fragilis alleviates the symptoms of lupus nephritis via regulating CD1d and CD86 expressions in B cells

Emerging evidences indicated that the dysbiosis of microbiota was related to the onset of systemic lupus erythematosus (SLE). Bacteroides fragilis (B. fragilis) ATCC 25285, a human commensal, was discovered to improve inflammatory diseases. However, whether B. fragilis (ATCC 25285) has the beneficial effects on the treatment of lupus nephritis has still remained elusive. In the present study, oral treatment with B. fragilis (ATCC 25285) ameliorated the activity of MRL/lpr mice, including decreased levels of autoantibodies and symptoms of lupus nephritis. Furthermore, we demonstrated that treatment with B. fragilis (ATCC 25285) could promote CD1d expression in B cells by Est-1 pathway, while inhibit CD86 expression via SHP-2 signaling pathway to repair the immune response of B cells in MRL/lpr mice. In addition, our findings revealed a possible role of treatment with B. fragilis (ATCC 25285) in relieving intestinal inflammation in MRL/lpr mice. Meanwhile, it was uncovered that B. fragilis (ATCC 25285) restored the Th17/Treg balance in MRL/lpr mice that was consistent with the role of B. fragilis in other autoimmune diseases. Overall, the current study may highlight the potential application of B. fragilis (ATCC 25285) to treat manifestations of SLE in high-risk individuals.

Post-rituximab immunoglobulin M (IgM) hypogammaglobulinemia

Rituximab is a B cell depleting monoclonal antibody that targets the B cell-specific cell surface antigen CD20 and is currently used to treat several autoimmune diseases. The elimination of mature CD20-positive B lymphocytes committed to differentiate into autoantibody-producing plasma cells is considered to be the major effect of rituximab, that makes it a beneficial biological agent in treating autoimmune diseases. Hypogammaglobulinemia has been reported after rituximab therapy in patients with lymphoma and rheumatoid arthritis. Similar data are scarce for other autoimmune diseases. Low immunoglobulin G (IgG) or hypogammaglobulinemia has attracted the most attention because of its significant role in protective immunity. However, the incidence and clinical implications of low immunoglobulin M (IgM) or hypogammaglobulinemia have not been studied in detail. This review will focus on the frequency and the clinical concerns of low IgM levels that result as a consequence of the administration of rituximab. The etiopathogenic mechanisms underlying post-rituximab IgM hypogammaglobulinemia and its implications are presented. The long-term consequences, if any, are not known or documented. Multiple factors may be involved in whether IgG or IgM decreases secondary to rituximab therapy. It is possible that the autoimmune disease itself may be one of the important factors. The dose, frequency and number of infusions appear to be important variables. Post-rituximab therapy immunoglobulin levels return to normal. During this process. IgM levels take a longer time to return to normal levels when compared to IgG or other immunoglobulins. IgM deficiency persists after B cell repopulation to normal levels has occurred. Laboratory animals and humans deficient in IgM can have multiple infections. Specific pharmacologic agents or biologic therapy that address and resolve IgM deficiency are currently unavailable. If the clinical situation so warrants, then prophylactic antibiotics may be indicated and perhaps helpful. Research in this iatrogenic phenomenon will provide a better understanding of not only the biology of IgM, but also the factor(s) that control its production and regulation, besides its influence if any, on rituximab therapy.

Targeting the Immune Complex-Bound Complement C3d Ligand as a Novel Therapy for Lupus

Humoral autoimmunity is central to the development of systemic lupus erythematosus (SLE). Complement receptor type 2 (CR2)/CD21 plays a key role in the development of high-affinity Abs and long-lasting memory to foreign Ags. When CR2 is bound by its primary C3 activation fragment-derived ligand, designated C3d, it coassociates with CD19 on B cells to amplify BCR signaling. C3d and CR2 also mediate immune complex binding to follicular dendritic cells. As the development of SLE involves subversion of normal B cell tolerance checkpoints, one might expect that CR2 ligation by C3d-bound immune complexes would promote development of SLE. However, prior studies in murine models of SLE using gene-targeted Cr2-/- mice, which lack both CR2 and complement receptor 1 (CR1), have demonstrated contradictory results. As a new approach, we developed a highly specific mouse anti-mouse C3d mAb that blocks its interaction with CR2. With this novel tool, we show that disruption of the critical C3d-CR2 ligand-receptor binding step alone substantially ameliorates autoimmunity and renal disease in the MRL/lpr model of SLE.

The Role of Immune Checkpoint Receptors in Regulating Immune Reactivity in Lupus

Immune checkpoint receptors with co-stimulatory and co-inhibitory signals are important modulators for the immune system. However, unrestricted co-stimulation and/or inadequate co-inhibition may cause breakdown of self-tolerance, leading to autoimmunity. Systemic lupus erythematosus (SLE) is a complex multi-organ disease with skewed and dysregulated immune responses interacting with genetics and the environment. The close connections between co-signaling pathways and SLE have gradually been established in past research. Also, the recent success of immune checkpoint blockade in cancer therapy illustrates the importance of the co-inhibitory receptors in cancer immunotherapy. Moreover, immune checkpoint blockade could result in substantial immune-related adverse events that mimic autoimmune diseases, including lupus. Together, immune checkpoint regulators represent viable immunotherapeutic targets for the treatment of both autoimmunity and cancer. Therefore, it appears reasonable to treat SLE by restoring the out-of-order co-signaling axis or by manipulating collateral pathways to control the pathogenic immune responses. Here, we review the current state of knowledge regarding the relationships between SLE and the co-signaling pathways of T cells, B cells, dendritic cells, and neutrophils, and highlight their potential clinical implications. Current clinical trials targeting the specific co-signaling axes involved in SLE help to advance such knowledge, but further in-depth exploration is still warranted.

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.

A tyrosine sulfation-dependent HLA-I modification identifies memory B cells and plasma cells

Memory B cells and plasma cells are antigen-experienced cells tasked with the maintenance of humoral protection. Despite these prominent functions, definitive cell surface markers have not been identified for these cells. We report here the isolation and characterization of the monoclonal variable lymphocyte receptor B (VLRB) N8 antibody from the evolutionarily distant sea lamprey that specifically recognizes memory B cells and plasma cells in humans. Unexpectedly, we determined that VLRB N8 recognizes the human leukocyte antigen-I (HLA-I) antigen in a tyrosine sulfation-dependent manner. Furthermore, we observed increased binding of VLRB N8 to memory B cells in individuals with autoimmune disorders multiple sclerosis and systemic lupus erythematosus. Our study indicates that lamprey VLR antibodies uniquely recognize a memory B cell- and plasma cell-specific posttranslational modification of HLA-I, the expression of which is up-regulated during B cell activation.

Prognostic Significance of Tumor-Infiltrating B Cells and Plasma Cells in Human Cancer

There is abundant evidence that tumor-infiltrating CD8⁺ T cells contribute positively to antitumor immunity; however, the role of tumor-infiltrating B cells (TIL-B) and plasma cells (PC) remains controversial, leading to differing opinions about whether immunotherapies should be designed to enhance or inhibit these cells. Through a comprehensive PubMed search, we reviewed publications with cohorts of 50 or more cases in which the prognostic value of TIL-B/PC was assessed by immunohistochemistry and/or gene-expression analysis. Sixty-nine studies representing 19 cancers met our review criteria. The large majority of studies assessed TIL-B by immunohistochemical detection of CD20. Of these, 50.0% reported a positive prognostic effect for CD20⁺ TIL-B, whereas the remainder found a neutral (40.7%) or negative (9.3%) effect. These differences in prognostic effect were not attributable to cancer type, other clinicopathologic factors, or differing technical approaches. The prognostic significance of TIL-B/PC was generally concordant with that of CD3⁺ and/or CD8⁺ T cells, and the prognostic effect of T cells was generally stronger when TIL-B and/or PC were also present. Additionally, 21 studies inferred the presence of TIL-B/PC from gene-expression data, and a large majority reported a positive prognostic effect. Although more studies are required involving additional cancer types and independent patient cohorts, the weight of evidence supports a positive role for TIL-B and PC in antitumor immunity, suggesting that enhancement of these responses should be considered in the design of cancer immunotherapies.

Recent advances in the management of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease presenting highly heterogeneous clinical manifestations and multi-systemic involvement. Patients are susceptible to relapse- and remission, thus making management challenging. Moreover, a considerable number of side effects may occur with conventional therapies; therefore, there is clearly a need for new therapeutic strategies. Since the pathogenesis of SLE is highly complex, it is far from being fully understood. However, greater understanding of the pathways and of the cellular and molecular mediators involved in SLE is being achieved. Emerging evidence has allowed the development of new biological therapeutic options targeting crucial molecular mediators involved in the pathogenesis of SLE. This literature review analyzes the availability of biological and target-directed treatments, phase II and III trials, and new therapies that are being developed for the treatment of SLE.

Mesenchymal stem cell transplantation in systemic lupus erythematous, a mesenchymal stem cell disorder

Systemic lupus erythematosus (SLE) is a chronic autoimmune and inflammatory disorder with involvement of several organs and systems such as the kidney, lung, brain and the hematopoietic system. As the most prevailing organ manifestation, lupus nephritis is the major cause of mortality and morbidity in SLE patients. The most classically and widely administered immunosuppressive medications, namely corticosteroids and cyclophosphamide, have eventuated in a remarkable amelioration in disease complications over the last few years and reduced the progression to end-stage multiorgan failure. Mesenchymal stem cells (MSCs) are considered as non-hematopoietic and multipotential progenitor cells, which are able to differentiate into multiple cell lineages such as chondrocytes, osteoblasts, myoblasts, endothelial cells, adipocytes, neuron-like cells, hepatocytes and cardiomyocytes. MSCs from SLE patients have demonstrated defects such as aberrant cytokine production. Moreover, impaired phenotype, growth and immunomodulatory functions of MSCs from patients with SLE in comparison to healthy controls have been reported. Therefore, it is hypothesized that SLE is potentially an MSC-mediated disease and, as a result, allogeneic rather than autologous MSC transplantation can be argued to be a potentially advantageous therapy for patients with SLE. On the other hand, the MSC senescence phenomenon may meet the current therapeutic approaches with challenges and demand more attention. Here, we discuss MSC transplantations to date in animal models and humans and focus on the MSC senescence complications in SLE patients.

Peli1 negatively regulates noncanonical NF-κB signaling to restrain systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by uncontrolled secretion of autoantibodies by plasma cells. Although the functional importance of plasma cells and autoantibodies in SLE has been well established, the underlying molecular mechanisms of controlling autoantibody production remain poorly understood. Here we show that Peli1 has a B cell-intrinsic function to protect against lupus-like autoimmunity in mice. Peli1 deficiency in B cells induces autoantibody production via noncanonical NF-κB signaling. Mechanically, Peli1 functions as an E3 ligase to associate with NF-κB inducing kinase (NIK) and mediates NIK Lys48 ubiquitination and degradation. Overexpression of Peli1 inhibits noncanonical NF-κB activation and alleviates lupus-like disease. In humans, PELI1 levels negatively correlate with disease severity in SLE patients. Our findings establish Peli1 as a negative regulator of the noncanonical NF-κB pathway in the context of restraining the pathogenesis of lupus-like disease.

Rituximab therapy for IgA-vasculitis with nephritis: a case series and review of the literature

Henoch-Schonlein purpura, also called IgA-vasculitis, is a systemic small vessels vasculitis with immunoglobulin A1-dominant immune deposits. The optimal treatment remains controversial. Because IgA-vasculitis is characterized by leukocyte infiltration of the blood vessel walls along with immunoglobulin A deposition, and because glucocorticosteroids inhibit inflammatory processes, early administration of glucocorticosteroids has been postulated to be effective, but this indication remains controversial. Immunosuppressive agents (azathioprine, cyclophosphamide, cyclosporine, mycophenolate) have been used in combination with glucocorticosteroids without definitive evidence of effectiveness. The efficacy of rituximab in adult IgA-vasculitis has been reported in few cases. We described a monocentric experience on the use of rituximab in adult IgA-vasculitis with biopsy-proven nephritis. The patients achieved a complete remission of nephritis and syndromic manifestations, and no patients experienced adverse reactions. These data have been compared with the limited literature nowadays available.

Plasma Cell Depletion Attenuates Hypertension in an Experimental Model of Autoimmune Disease

Numerous studies show a direct relation between circulating autoantibodies, characteristic of systemic autoimmune disorders, and primary hypertension in humans. Whether these autoantibodies mechanistically contribute to the development of hypertension remains unclear. Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by aberrant immunoglobulin production, notably pathogenic autoantibodies, and is associated with prevalent hypertension, renal injury, and cardiovascular disease. Because plasma cells produce the majority of serum immunoglobulins and are the primary source of autoantibodies in SLE, we hypothesized that plasma cell depletion using the proteasome inhibitor bortezomib would lower autoantibody production and attenuate hypertension. Thirty-week-old female SLE (NZBWF1) and control (NZW [New Zealand White]) mice were injected IV with vehicle (0.9% saline) or bortezomib (0.75 mg/kg) twice weekly for 4 weeks. Bortezomib treatment significantly lowered the percentage of bone marrow plasma cells in SLE mice. Total plasma IgG and anti-dsDNA IgG levels were higher in SLE mice compared with control mice but were lowered by bortezomib treatment. Mean arterial pressure (mm Hg) measured in conscious mice by carotid artery catheter was higher in SLE mice than in control mice, but mean arterial pressure was significantly lower in bortezomib-treated SLE mice. Bortezomib also attenuated renal injury, as assessed by albuminuria and glomerulosclerosis, and reduced glomerular immunoglobulin deposition and B and T lymphocytes infiltration into the kidneys. Taken together, these data show that the production of autoantibodies by plasma cells mechanistically contributes to autoimmune-associated hypertension and suggests a potential role for patients with primary hypertension who have increased circulating immunoglobulins.

The activity of myeloid cell-specific VHH immunotoxins is target-, epitope-, subset- and organ dependent

The central role of myeloid cells in driving autoimmune diseases and cancer has raised interest in manipulating their function or depleting them for therapeutic benefits. To achieve this, antibodies are used to antagonize differentiation, survival and polarization signals or to kill target cells, for example in the form of antibody-drug conjugates (ADC). The action of ADC in vivo can be hard to predict based on target expression pattern alone. The biology of the targeted receptor as well as its interplay with the ADC can have drastic effects on cell apoptosis versus survival. Here we investigated the efficacy of CD11b or Ly-6C/Ly-6G-specific variable fragments of camelid heavy chain-only antibodies (VHH) conjugated to Pseudomonas exotoxin A to deplete myeloid cells in vitro and in vivo. Our data highlight striking differences in cell killing in vivo, depending on the cell subset and organs targeted, but not antigen expression level or VHH affinity. We observed striking differences in depletion efficiency of monocytes versus granulocytes in mice. Despite similar binding of Ly-6C/Ly-6G-specific VHH immunotoxin to granulocytes and monocytes, granulocytes were significantly more sensitive than monocytes to immunotoxins treatment. Our results illustrate the need of early, thorough in vivo characterization of ADC candidates.

Belimumab in the treatment of systemic lupus erythematous: An evidence based review of its place in therapy

INTRODUCTION

Systemic lupus erythematous is an autoimmune disease with diverse clinical features and has its development associated with a complexity of genetic, hormonal and environmental factors and the development of autoantibodies. Identification of new treatments is currently an area of intense investigation. Belimumab is the first biologic approved for the treatment of the disease inhibiting the excessive B cell activity observed in these patients and consequently reduction of autoantibodies.

AIM

To review the current transition of the evidence available of its use in real life patients with persistent active disease while on conventional therapies.

EVIDENCE

The results observed on the large series of patients (over 50 patients) followed for at least six months confirm the observations from phase 3 trials. In clinical practice close to two third of the patients remained on belimumab and one third discontinued mostly due to evaluation by the doctor or the patient or both of no detectable positive response. The presence of adverse events was considerably low and the subgroups with skin and joint manifestations appear to benefit the most. Daily steroid use is usually reduced to a significantly low when compared with the intake before introduction of the biologic Although not seen on trials in real life the addition of belimumab to the conventional therapy in lupus nephritis is being reported in several patients. Cost of the medication is still an issue that hampers its use. Further evidence of its use in certain specific groups is under investigation and its results should shed light on additional indications.

PLACE IN THERAPY

Considering what is currently published on the evidence here reviewed in the use of belimumab in clinical practice it is our understanding that belimumab it will be gradually incorporated in the armamentarium of treatment not necessarily on refractory patients. We believe that with the upcoming of the subcutaneous route in the near future should also help in widen the use of the belimumab to be considered in first line combination set ups.

Cytokines as therapeutic targets in primary Sjögren syndrome

Primary Sjögren syndrome (SjS) is a systemic autoimmune disease that may affect 1 in 1000 people (overwhelmingly women) and that can be a serious disease with excess mortality due to severe organ-specific involvements and the development of B cell lymphoma; systemic involvement clearly marks the disease prognosis, and strongly suggests the need for closer follow-up and more robust therapeutic management. Therapy is established according to the organ involved and severity. As a rule, the management of systemic SjS should be organ-specific, with glucocorticoids and immunosuppressive agents limited to potentially-severe involvements; unfortunately, the limited evidence available for these drugs, together with the potential development of serious adverse events, makes solid therapeutic recommendations difficult. The emergence of biological therapies has increased the therapeutic armamentarium available to treat primary SjS. Biologics currently used in SjS patients are used off-label and are overwhelmingly agents targeting B cells, but the most recent studies are moving on into the evaluation of targeting specific cytokines involved in the SjS pathogenesis. The most recent etiopathogenic advances in SjS are shedding some light in the search for new highly-selective biological therapies without the adverse effects of the standard drugs currently used (corticosteroids and immunosuppressant drugs). This review summarizes the potential pharmacotherapeutic options targeting the main cytokine families involved in the etiopathogenesis of primary SjS and analyzes potential insights for developing new therapies.

TLR-Induced SMPD3 Defects Enhance Inflammatory Response of B Cell and Macrophage in the Pathogenesis of SLE

B lymphocyte and macrophages may contribute to SLE pathogenesis through cytokine production after TLR stimulation. Emerging evidences suggested that defects of sphingolipid metabolism were responsible for SLE pathogenesis. However, it is not clear whether these defects exist in B cells and macrophages under SLE condition and whether TLR signalling pathway was related to the dysfunction of sphingolipid metabolism in SLE. Here, we demonstrated that the enzymes involved in the sphingolipid metabolism expressed abnormally in B cells from SLE patients and lupus-prone mice. Moreover, we found that TLR signalling induced the abnormal expression of sphingomyelin phosphodiesterase 3 (SMPD3), sphingosine-1-phosphate phosphatase 2 (SGPP2), ceramide kinase (CERK) and UDP glycosyltransferase 8 (UGT8), which were involved in sphingolipid metabolism. TLR signalling also induced the transportation of SMPD3 from Golgi apparatus. Furthermore, the dysfunction of SMPD3 enhanced TLR-induced inflammatory response of B cells and macrophages in turn. Thus, these findings provide an innovative direction and a new target for research and treatment of SLE.

Modelling clinical systemic lupus erythematosus: similarities, differences and success stories

Mouse models of SLE have been indispensable tools to study disease pathogenesis, to identify genetic susceptibility loci and targets for drug development, and for preclinical testing of novel therapeutics. Recent insights into immunological mechanisms of disease progression have boosted a revival in SLE drug development. Despite promising results in mouse studies, many novel drugs have failed to meet clinical end points. This is probably because of the complexity of the disease, which is driven by polygenic predisposition and diverse environmental factors, resulting in a heterogeneous clinical presentation. Each mouse model recapitulates limited aspects of lupus, especially in terms of the mechanism underlying disease progression. The main mouse models have been fairly successful for the evaluation of broad-acting immunosuppressants. However, the advent of targeted therapeutics calls for a selection of the most appropriate model(s) for testing and, ultimately, identification of patients who will be most likely to respond.

Targeted B cell therapies in the treatment of adult and pediatric systemic lupus erythematosus

Belimumab (Benlysta) is a fully-humanized monoclonal antibody that inhibits B-lymphocyte stimulator (also known as B cell activating factor) and was approved by the U.S. Federal Drug Administration and European Medicines Evaluation Agency for treatment in adults with autoantibody-positive systemic lupus erythematosus (SLE). Rituximab (Rituxan) is a chimeric anti-CD20 monoclonal antibody targeting B lymphocytes. This review discusses the key findings of the phase III trials in adults with SLE and of real-world use of belimumab and rituximab in the care of both adult and pediatric SLE patients. It highlights the safety profile of belimumab and rituximab and gives insight into the consideration of these therapies for specific SLE disease states. It concludes with a discussion of the current clinical trials investigating B cell therapies in specific SLE disease states and a look to the future, with ongoing clinical trials.

Decreased CD1d level is associated with CD86 over-expression in B cells from systemic lupus erythematosus

The disorder of B cells is one of the hallmarks of systemic lupus erythematosus (SLE). The activation state indicated by CD86 of B cells from SLE is well known, while the defect of regulatory B cells mediated by CD1d is also responsible for the process of SLE. In the present study, we focused on the relationship between B cell activation mediated by CD86 and B cell regulatory function mediated by CD1d. Our results showed that the level of CD1d in B cells was decreased during the early stages of B6.MRLlpr SLE mice and imiquimod-treated (IMQ-treated) mice, while the level of CD86 was significantly increased at the late stage. Moreover, the expression of CD1d showed a significantly negative correlation with CD86 level in B cells from IMQ-treated mice (r = -05741; P = 0.0022), B6.MRLlpr mice (r = -0.7091; P = 0.0268), and SLE patients (r = -0.4125; P = 0.0404). The in vivo and in vitro experiments with splenocytes demonstrated that CD1d signaling pathway could inhibit toll-like receptor 7 (TLR7)-induced CD86 expression of B cells. Further studies showed that this relationship also affected antibody production. Thus, our results confirmed the association of CD1d and CD86 levels in B cells from SLE, and demonstrated the importance to preserve the immunoregulatory function of B cells mediated by CD1d in the progression of SLE.

Treating the Underlying Pathophysiology of Primary Sjögren Syndrome: Recent Advances and Future Prospects

Sjögren Syndrome (SS) is a systemic autoimmune disease with a wide clinical spectrum that extends from sicca symptoms of the mucosal surfaces to extra-glandular systemic manifestations. Understanding of the pathophysiology of primary SS has advanced over recent years, and this, in turn, has presented new targeted treatment options. We provide a brief, up-to-date description of the pathophysiology of SS and the main etiopathogenic pathways implicated in the disease process and review clinical evidence in support of new treatment options targeting these pathways, highlighting successes and failures, and concluding with a summary of gaps in knowledge and where future research should be focused. Direct and indirect B-cell targeted therapies are currently the most promising biological agents in primary SS, especially for systemic involvement, but other pathways (T-cell co-stimulation, cytokine-based therapies, intracellular pathways and gene therapies) are under development. The next 10 years may witness a disruptive therapeutic scenario in primary SS.

Pharmacokinetics, Pharmacodynamics and Preliminary Observations for Clinical Activity and Safety of Multiple Doses of Human Mouse Chimeric Anti-CD22 Monoclonal Antibody (SM03) in Chinese Patients with Systemic Lupus Erythematosus

BACKGROUND AND OBJECTIVES

SM03 is a novel recombinant, human/mouse chimeric immunoglobulin G1 monoclonal antibody directed against the CD22 antigen on human B lymphocytes. This was the first study to investigate the pharmacokinetics, pharmacodynamics, immunogenicity, safety and clinical activity of SM03 in patients with systemic lupus erythematosus (SLE).

METHODS

This study was an open, multiple-centre, parallel-group, multiple-ascending-dose, phase I study in 29 SLE patients. Pharmacokinetic assessment was conducted in 22 of these patients. Eligible patients received multiple intravenous infusions of SM03 for 4 weeks (240 mg/m², 600 or 900 mg, once weekly) and were monitored over an 84-day observation period for pharmacokinetics, pharmacodynamics, immunogenicity, safety and clinical response.

RESULTS

After multiple-dose SM03, the maximal serum concentration of SM03 was reached within 3-7 h. The mean elimination half-life was 15 days. The average accumulation ratios of the area under the time-concentration curve and the maximum concentration after the fourth administration of SM03 were 2.0 and 1.5. CD19⁺ B-lymphocyte counts were decreased. Infections were the most common adverse events. No drug-related serious adverse events were reported. The therapeutic benefit of SM03 was observed mainly in patients with moderate-to-severe disease activity.

CONCLUSION

Pharmacokinetic exposure increased in a lower-than-dose-proportional manner up to 900 mg. SM03 was well tolerated at doses ranging from 240 mg/m² to 900 mg, with no new safety signals identified. SM03 has potential efficacy in Chinese patients with SLE.

CD16+ Monocyte Subset Was Enriched and Functionally Exacerbated in Driving T-Cell Activation and B-Cell Response in Systemic Lupus Erythematosus

Background

The roles that CD16⁺ monocyte subset plays in T-cell activation and B-cell response have not been well studied in systemic lupus erythematosus (SLE).

Objective

The present study aimed to investigate the distribution of CD16⁺ monocyte subsets in SLE and explore their possible roles in T-cell activation and B-cell differentiation.

Methods

The frequencies of monocyte subsets in the peripheral blood of healthy controls (HCs) and patients with SLE were determined by flow cytometry. Monocyte subsets were sorted and cocultured with CD4⁺ T cells and CD19⁺ B cells. Then, T and B cells were collected for different subset detection, while the supernatants were collected for immunoglobulin G, IgA, and IgM or interferon-γ and interleukin-17A detection by enzyme-linked immunosorbent assay.

Results

Our results showed that CD16⁺ monocytes exhibited a proinflammatory phenotype with elevated CD80, CD86, HLA-DR, and CX3CR1 expression on the cell surface. It’s further demonstrated that CD16⁺ monocytes from patients and HCs shared different cell-surface marker profiles. The CD16⁺ subset was enriched in SLE and had an exacerbated capacity to promote CD4⁺ T cell polarization into a Th17 phenotype. Also, CD16⁺ monocytes had enhanced impacts on CD19⁺ B cells to differentiate into plasma B cells and regulatory B cells with more Ig production.

Conclusion

This study demonstrated that CD16⁺ monocytes, characterized by different cell-surface marker profiles, were enriched and played a critical role in driving the pathogenic T- and B-cell responses in patients with SLE.

First Real-World Insights into Belimumab Use and Outcomes in Routine Clinical Care of Systemic Lupus Erythematosus in Germany: Results from the OBSErve Germany Study

OBSErve Germany was the first observational study of belimumab as add-on treatment for systemic lupus erythematosus (SLE) in routine clinical care in Germany, retrospectively collecting data from 102 SLE patients, 6 months before and after belimumab initiation. Most patients had moderate or severe SLE and several SLE manifestations. After 6 months of belimumab treatment, 78% of patients showed an improvement in overall disease activity of at least 20% in their physician’s judgment and for 42% of patients the improvement was at least 50%. Similar results were observed for the most common manifestations: arthritis, fatigue, rash, alopecia, increased anti-dsDNA antibody levels, and low complement. The SLE Disease Activity Index (SLEDAI/SELENA-SLEDAI) decreased from 10.6 to 5.6 (n = 65), with other indices also showing improvement. A notable dose reduction was seen for concomitant oral corticosteroids, from 13.7 to 7.6 mg/day overall (n = 91), and from 17.5 to 8.6 mg/day in patients with a high corticosteroid dose at belimumab initiation (≥7.5 mg; n = 63). Six patients discontinued belimumab therapy within 6 months. Overall, belimumab showed promising results for SLE patients in real-world settings. After 6 months of belimumab treatment, disease activity and corticosteroid use were reduced. The discontinuation rate was low and belimumab appeared to be well tolerated.

Funding GlaxoSmithKline UK.

Beyond pan-B-cell-directed therapy - new avenues and insights into the pathogenesis of SLE

New insights into the mechanisms of autoimmune diseases have been obtained not only from preclinical studies, but also from clinical trials of pan-B-cell-directed therapy. Overall, the results of these clinical trials suggest that more-specific approaches focusing on pathogenic B-cell functions, and perhaps sparing or even enhancing regulatory B-cell activity, might be attractive alternatives. Importantly, pathogenic B-cell subpopulations function within a network of cellular interactions, many of which might require additional interventions to restore immunologic balance and suppress autoimmune disease. Thus, approaches that simultaneously target innate immune cells as well as multiple nodes of T-cell and B-cell interactions might hold the promise of improved therapeutic efficacy. Interfering with B-cell intracellular signalling pathways, altering their intracellular metabolic pathways and perturbing transcription factors are additional options. This Review critically analyses these approaches, examines the role of cytokines and other functions of B-lineage cells separate from antibody secretion, and provides insights into the potential next generation of therapies targeting B-lineage cells.

MEDI-551 Treatment Effectively Depletes B Cells and Reduces Serum Titers of Autoantibodies in Mice Transgenic for Sle1 and Human CD19

OBJECTIVE

To evaluate treatment with MEDI-551, a humanized anti-human CD19 monoclonal antibody, in a model of autoimmunity involving mice transgenic (Tg) for Sle1 and human CD19 (hCD19).

METHODS

Sle1.hCD19-Tg mice were given either a single intravenous dose of MEDI-551 or repeated doses of MEDI-551 biweekly for up to 12 weeks. The numbers of B cells in the blood, spleen, and bone marrow were determined by flow cytometry assay. In the spleen and bone marrow, the number of IgM- and IgG-specific antibody-secreting cells (ASCs) and the number of ASCs specific for anti-double-stranded DNA (anti-dsDNA) were determined by enzyme-linked immunospot assay. Serum autoantibody and total immunoglobulin levels were determined by enzyme-linked immunosorbent assay, and levels of inflammatory proteins were tested using a multianalyte profiling platform.

RESULTS

MEDI-551 treatment of Sle1.hCD19-Tg mice resulted in effective and sustained B cell depletion throughout the duration of the experiment. The frequency of IgM and IgG ASCs in the spleen was reduced by ≥90%, whereas in the bone marrow, the total ASC frequency was not changed. Levels of autoantibodies specific for dsDNA as well as antihistone and antinuclear antibodies were each reduced by 40-80%, but total serum immunoglobulin levels were largely unchanged at the end of 12 weeks of treatment.

CONCLUSION

These findings highlight the ability of MEDI-551 to deplete B cells and ASCs in autoimmune Sle1.hCD19-Tg mice. MEDI-551 treatment resulted in a robust reduction of autoantibodies but had minimal effect on total serum immunoglobulins. Thus, the novel ability of MEDI-551 to remove a broad range of B cells as well as to lower most disease-driving autoantibodies in an autoimmune disease mouse model warrants continued research. Several clinical studies to explore the safety and activity of MEDI-551 in autoantibody-associated autoimmune diseases are ongoing.

Network Analysis Identifies Proinflammatory Plasma Cell Polarization for Secretion of ISG15 in Human Autoimmunity

Plasma cells (PCs) as effectors of humoral immunity produce Igs to match pathogenic insult. Emerging data suggest more diverse roles exist for PCs as regulators of immune and inflammatory responses via secretion of factors other than Igs. The extent to which such responses are preprogrammed in B-lineage cells or can be induced in PCs by the microenvironment is unknown. In this study, we dissect the impact of IFNs on the regulatory networks of human PCs. We show that core PC programs are unaffected, whereas PCs respond to IFNs with distinctive transcriptional responses. The IFN-stimulated gene 15 (ISG15) system emerges as a major transcriptional output induced in a sustained fashion by IFN-α in PCs and linked both to intracellular conjugation and ISG15 secretion. This leads to the identification of ISG15-secreting plasmablasts/PCs in patients with active systemic lupus erythematosus. Thus, ISG15-secreting PCs represent a distinct proinflammatory PC subset providing an Ig-independent mechanism of PC action in human autoimmunity.

Generation and characterization of human B lymphocyte stimulator blocking monoclonal antibody

The cytokine, B lymphocyte stimulator (Blys) is essential for activation and proliferation of B cells and is involved in the pathogenesis of B-cell mediated autoimmune diseases. Based on its essential activity, Blys may be a potential therapeutic target for human autoimmune diseases. In this article, we have described the development of a novel humanized anti-Blys antibody, NMB04, that binds with high affinity and specificity to both soluble and membrane bound Blys. This monoclonal antibody has the potential to block Blys binding to all its three receptors, TACI, BCMA and BR-3. Further in vivo studies revealed that NMB04 possessed more potent inhibitory activity against human Blys as compared to an existing antibody, Belimumab. Therefore, NMB04 may have potential as a therapeutic candidate targeting autoimmune diseases.

Rethinking biologics in lupus nephritis

Lupus nephritis (LN) is a chronic and devastating complication of systemic lupus erythematosus. Despite advances in our understanding of LN and the availability of effective therapies, LN remains a difficult clinical problem, and progression to end stage renal disease remains a significant challenge. Though the advent of biologics has revolutionized the treatment of many rheumatological conditions, and several clinical trials of biologics have been conducted in LN, the promise of biologics remains unfulfilled. The experience gained from these initial clinical trials can help tailor approaches in future clinical trials, and the lessons learned can be applied to find a cure for this condition.

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.