B cell activating factor (BAFF): Structure, functions, autoimmunity and clinical implications in Systemic Lupus Erythematosus (SLE)

Response to belimumab in thrombotic thrombocytopenic purpura associated with systemic lupus erythematosus: a case-based review

Thrombotic thrombocytopenic purpura (TTP), a life-threatening syndrome characterized by acute microangiopathic hemolytic anemia, thrombocytopenia, and visceral ischemia, can be classified as congenital TTP (inherited due to a mutation in ADAMTS13) and acquired TTP. The acquired TTP is further classified as idiopathic and secondary TTP. Systemic lupus erythematosus (SLE) is regarded as one of the most common causes of secondary TTP (SLE-TTP). In contrast to patients with idiopathic TTP, some patients with SLE-TTP, especially those diagnosed with refractory TTP, are resistant to plasma exchange and high-dose corticosteroids and usually require second-line drugs, including newly developed biologicals. Belimumab, a B-lymphocyte stimulator-specific inhibitor, was the first approved new therapy for SLE in the past 50 years. Only two cases of SLE-TTP using belimumab have been reported; however, detailed information has not been made available. Herein, we describe a 28-year-old female patient who presented with palm petechiae, strong tawny urine, and yellow stained skin and sclera, and was diagnosed with SLE-TTP supported by high anti-ANA titers; positive anti-SSA/SM; pleural effusion; decreased platelet count, hemoglobin, and complement C3/C4 counts; increased lactate dehydrogenase level, along with increased schistocytes; and a significant deficiency of ADAMTS13 activity. Belimumab (10 mg/kg) was administered after six plasma exchanges. Good efficiency and outcomes without any adverse events, SLE, or TTP relapse were observed during 12 months of follow-up. Therefore, belimumab is a promising choice for SLE-TTP management. In addition, we provide a focused review of the existing literature on the pathogenesis, diagnosis, and therapeutic strategies for SLE-TTP.

Autophagy in Rheumatic Diseases: Role in the Pathogenesis and Therapeutic Approaches

Autophagy is a lysosomal pathway for the degradation of damaged proteins and intracellular components that promotes cell survival under specific conditions. Apoptosis is, in contrast, a critical programmed cell death mechanism, and the relationship between these two processes influences cell fate. Recent evidence suggests that autophagy and apoptosis are involved in the self-tolerance promotion and in the regulatory mechanisms contributing to disease susceptibility and immune regulation in rheumatic diseases. The aim of this review is to discuss how the balance between autophagy and apoptosis may be dysregulated in multiple rheumatic diseases and to dissect the role of autophagy in the pathogenesis of rheumatoid arthritis, systemic lupus erythematosus, and Sjögren’s syndrome. Furthermore, to discuss the potential capacity of currently used disease-modifying antirheumatic drugs (DMARDs) to target and modulate autophagic processes.

Increased B Cell-Activating Factor Expression Is Associated with Postoperative Recurrence of Chronic Rhinosinusitis with Nasal Polyps

Background

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common upper airway inflammatory disease with a high postoperative recurrence rate. This study is aimed at exploring the expression of B cell-activating factor (BAFF) in CRSwNP and its association with postoperative recurrence.

Methods

A total of 80 CRSwNP patients, including 40 primary CRSwNP patients and 40 recurrent CRSwNP patients, 40 chronic rhinosinusitis without nasal polyps (CRSsNP) patients, and 40 healthy controls (HC) were enrolled in this study, and the serum and tissue samples were collected. The circulating and tissue BAFF expressions were detected by enzyme-linked immunosorbent assay reverse transcription-polymerase chain reaction and immunohistochemistry. Their clinical values for predicting postoperative recurrence of CRSwNP were evaluated.

Results

We determined serum levels of BAFF were remarkably increased in the CRSwNP group than the CRSsNP and HC groups (P < 0.05), and higher concentrations of BAFF were associated with peripheral eosinophil percentage (r = 0.614, P < 0.001). The serum BAFF concentrations were significantly higher in the recurrent CRSwNP group in comparison with the primary group (P < 0.05). Multivariate analysis and receiver operating characteristic (ROC) curve presented that serum BAFF levels were associated with the postoperative recurrence in CRSwNP patients (P < 0.05). Moreover, tissue BAFF levels were significantly increased in the CRSwNP group than the HC group, especially in the recurrent CRSwNP group (P < 0.05), and enhanced BAFF RNA expressions were correlated with serum BAFF levels (r = 0.703, P < 0.001).

Conclusion

Our results elucidated that the BAFF expression was enhanced in CRSwNP patients and associated with postoperative recurrence. BAFF could be a serologic biomarker for predicting postoperative recurrence in CRSwNP patients.

Endothelial function and endothelial progenitor cells in systemic lupus erythematosus

The observations that traditional cardiovascular disease (CVD) risk factors fail to fully account for the excessive cardiovascular mortality in patients with systemic lupus erythematosus (SLE) compared with the general population have prompted in-depth investigations of non-traditional, SLE-related risk factors that contribute to cardiovascular complications in patients with SLE. Of the various perturbations of vascular physiology, endothelial dysfunction, which is believed to occur in the earliest step of atherosclerosis, has been extensively investigated for its contribution to CVD risk in SLE. Endothelial progenitor cells (EPCs), which play a crucial part in vascular repair, neovascularization and maintenance of endothelial function, are quantitatively and functionally reduced in patients with SLE. Yet, the lack of a unified definition of EPCs, standardization of the quantity and functional assessment of EPCs as well as endothelial function measurement pose challenges to the translation of endothelial function measurements and EPC levels into prognostic markers for CVD in patients with SLE. This Review discusses factors that contribute to CVD in SLE, with particular focus on how endothelial function and EPCs are evaluated currently, and how EPCs are quantitatively and functionally altered in patients with SLE. Potential strategies for the use of endothelial function measurements and EPC quantification as prognostic markers of CVD in patients with SLE, and the limitations of their prognostication potential, are also discussed.

Monoclonal Antibody Therapies Beyond Complement for NMOSD and MOGAD

Aquaporin-4 (AQP4)-IgG seropositive neuromyelitis optica spectrum disorders (AQP4-IgG seropositive NMOSD) and myelin oligodendrocyte glycoprotein (MOG)-IgG-associated disease (MOGAD) are inflammatory demyelinating disorders distinct from each other and from multiple sclerosis (MS).While anti-CD20 treatments can be used to treat MS and AQP4-IgG seropositive NMOSD, some MS medications are ineffective or could exacerbate AQP4-IgG seropositive NMOSD including beta-interferons, natalizumab, and fingolimod. AQP4-IgG seropositive NMOSD has a relapsing course in most cases, and preventative maintenance treatments should be started after the initial attack. Rituximab, eculizumab, inebilizumab, and satralizumab all have class 1 evidence for use in AQP4-IgG seropositive NMOSD, and the latter three have been approved by the US Food and Drug Administration (FDA). MOGAD is much more likely to be monophasic than AQP4-IgG seropositive NMOSD, and preventative therapy is usually reserved for those who have had a disease relapse. There is a lack of any class 1 evidence for MOGAD preventative treatment. Observational benefit has been suggested from oral immunosuppressants, intravenous immunoglobulin (IVIg), rituximab, and tocilizumab. Randomized placebo-controlled trials are urgently needed in this area.

Long Non-Coding RNAs in Systemic Lupus Erythematosus: New Insights into Disease Pathogenesis and Diagnosis

Systemic lupus erythematosus (SLE) is a remarkable heterogeneous autoimmune disease that is sometimes hard to diagnose at the early stage and can lead to premature mortality. Long non-coding RNAs (lncRNAs) are a class of non-protein-coding RNAs greater than 200 nucleotides in length that can regulate gene expression in various human diseases, including SLE. Peripheral blood samples and renal tissue samples from SLE patients were used for study. Abnormally expressed lncRNAs in SLE have been shown to influence several signaling pathways, including the IFN-I, MAPK and WNT pathways. This can affect cellular phenotypes like cell activation, differentiation skewing, cytokine production, and cell apoptosis. Many of the reported lncRNAs may be useful for diagnosing, evaluating progression, and predicting potential organ damage in SLE patients. While numerous lncRNAs play important roles in SLE, more basic and clinical studies are warranted to clarify the function of these regulatory molecules and determine their diagnostic value.

Marginal Zone B-Cell Populations and Their Regulatory Potential in the Context of HIV and Other Chronic Inflammatory Conditions

Inflammation in the context of Human Immunodeficiency Virus (HIV) establishes early and persists beyond antiretroviral therapy (ART). As such, we have shown excess B-cell activating factor (BAFF) in the blood of HIV-infected progressors, as soon as in the acute phase, and despite successful ART. Excess BAFF was associated with deregulation of the B-cell compartment; notably, with increased frequencies of a population sharing features of both transitional immature (TI) and marginal zone (MZ) B-cells, we termed Marginal Zone precursor-like (MZp). We have reported similar observations with HIV-transgenic mice, Simian Immunodeficiency Virus (SIV)-infected macaques, and more recently, with HIV-infected Beninese commercial sex workers, which suggests that excess BAFF and increased frequencies of MZp B-cells are reliable markers of inflammation in the context of HIV. Importantly, we have recently shown that in healthy individuals, MZps present an important regulatory B-cell (Breg) profile and function. Herein, we wish to review our current knowledge on MZ B-cell populations, especially their Breg status, and that of other B-cell populations sharing similar features. BAFF and its analog A Proliferation-Inducing Ligand (APRIL) are important in shaping the MZ B-cell pool; moreover, the impact that excess BAFF—encountered in the context of HIV and several chronic inflammatory conditions—may exert on MZ B-cell populations, Breg and antibody producing capacities is a threat to the self-integrity of their antibody responses and immune surveillance functions. As such, deregulations of MZ B-cell populations contribute to autoimmune manifestations and the development of MZ lymphomas (MZLs) in the context of HIV and other inflammatory diseases. Therefore, further comprehending the mechanisms regulating MZ B-cell populations and their functions could be beneficial to innovative therapeutic avenues that could be deployed to restore MZ B-cell immune competence in the context of chronic inflammation involving excess BAFF.

Increased vitreous levels of B cell activation factor (BAFF) and soluble interleukin-6 receptor in patients with macular edema due to uveitis related to Behçet's disease and sarcoidosis

PURPOSE

Uveitis accounts for 10-15% of all cases of blindness in the developed world. Uveitic macular edema (UME) is a primary cause of permanent visual impairment in patients with uveitis. Because proinflammatory mediators elicit inflammation and lead to UME, we determined the profiles of proinflammatory mediators associated with complications, such as ME, in the vitreous humor of patients with panuveitis related to Behçet's disease (BD) and sarcoidosis.

METHODS

In this retrospective study, we enrolled 21 patients with uveitis, including 6 with BD and 15 with sarcoidosis, and 15 patients with idiopathic epiretinal membrane (iERM) at the Department of Ophthalmology, Kyushu University Hospital, between January 2008 and April 2016. Vitreous concentrations of 32 proinflammatory mediators, including cytokines and soluble receptors of tumor necrosis factor (TNF) and interleukin (IL)-6 families, were assessed using a bead-based multiplex assay and their association with clinical data was examined.

RESULTS

The levels of proinflammatory mediators, including a proliferation-inducing ligand (APRIL), B cell activating factor belonging to the TNF family (BAFF), soluble cluster of differentiation 30 (sCD30), soluble TNF receptor-1 (sTNFR1), sTNFR2, TNF-α, IL-6, and soluble IL-6 receptor-α (sIL-6Rα), were significantly higher in patients with uveitis. With regard to clinical parameters in patients with uveitis, vitreous levels of BAFF and sIL-6Rα were prominently elevated in patients with UME compared to in those without UME (P < 0.01, respectively).

CONCLUSIONS

Our results suggest that elevated vitreous levels of BAFF and sIL-6Rα are associated with the pathogenesis of UME in patients with panuveitis related to BD and sarcoidosis.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

Pemphigus represents a group of rare and severe autoimmune intra-epidermal blistering diseases affecting the skin and mucous membranes. These painful and debilitating diseases are driven by the production of autoantibodies that are mainly directed against the desmosomal adhesion proteins, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). The search to define underlying triggers for anti-Dsg-antibody production has revealed genetic, environmental, and possible vaccine-driven factors, but our knowledge of the processes underlying disease initiation and pathology remains incomplete. Recent studies point to an important role of T cells in supporting auto-antibody production; yet the involvement of the myeloid compartment remains unexplored. Clinical management of pemphigus is beginning to move away from broad-spectrum immunosuppression and towards B-cell-targeted therapies, which reduce many patients’ symptoms but can have significant side effects. Here, we review the latest developments in our understanding of the predisposing factors/conditions of pemphigus, the underlying pathogenic mechanisms, and new and emerging therapies to treat these devastating diseases.

Belimumab: A BAFF-specific Inhibitor for the Treatment of Systemic Lupus Erythematosus and Lupus Nephritis

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that affects multiple organs. In particular, the presence of renal involvement, known as lupus nephritis, is a major determinant of prognosis. Conventional treatments for SLE include hydroxychloroquine, glucocorticoid and immunosuppressive agents. However, the use of such non-specific drugs increases the risk of side effects, such as infections. Soluble B-cell-activating factor (BAFF), belonging to the tumour necrosis factor family, is produced by dendritic cells and induces class switching of B cells and differentiation into antibody-producing cells. International phase III studies demonstrated the efficacy and safety of belimumab (a monoclonal antibody against soluble BAFF) not only in patients with SLE, but also in those with active lupus nephritis. There were no significant differences between the belimumab and placebo groups in the incidence of adverse events, including serious events and events necessitating drug cessation. Thus, belimumab could become an alternative induction treatment for lupus nephritis. This article describes the pathogenesis of SLE and lupus nephritis, and reviews the results of recent phase III trials of belimumab and its promising role for the treatment of patients.

Anti-Sm antibodies in the classification criteria of systemic lupus erythematosus

Systemic lupus erythematosus is characterized by autoantibodies and immune complex deposition. Several autoantibodies against mainly nuclear autoantigens have been described. One of these nuclear autoantigens is the Smith antigen. In this review, we focus on the position of autoantibodies against the Smith antigen in the classification criteria, the characteristics of the antigen, the production of anti-Smith antibodies in SLE and we discuss the different test methods available, together with their pitfalls, to detect these autoantibodies.

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Patients having anti-Sm antibodies already fulfil sixty percent of the criteria required for SLE classification.

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Correct interpretation of anti-Smith antibody test results is strongly related to the choice of the test used for detection.

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Anti-Sm antibodies are very specific for SLE.

The Therapeutic Strategies for SLE by Targeting Anti-dsDNA Antibodies

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by diverse serological autoantibodies. Anti-dsDNA antibodies are involved in multiple organ damage, especially the kidney, skin, and central nervous system. Anti-dsDNA antibodies play a pivotal role in SLE, and researchers have developed therapeutic strategies targeting these antibodies. Approaches to reduce anti-dsDNA antibodies via B cell targeted biologics against B cell surface antigens, B cell survival factors, or Bruton's tyrosine kinase have effectively eliminated B cells. However, their non-specific depletion hampers normal immune system functioning and limits the therapeutic benefits. Thus, scientists have attempted anti-dsDNA antibodies or lupus-specific strategies, such as the immature dendritic cell vaccine and immunoadsorption. Recently, synthetic mimic peptides (hCDR1, pCONs, DWEYS, FISLE-412, and ALW) that directly block anti-dsDNA autoantibodies have attracted attention, which could ameliorate lupus, decrease the serological autoantibody titer, reduce the deposition of renal autoantibodies, and improve pathological performance. These potent small peptide molecules are well tolerated, non-toxic, and non-immunogenic, which have demonstrated a benign safety profile and are expected to be hopeful candidates for SLE management. In this review, we clarify the role of anti-dsDNA antibodies in SLE, mainly focus on the current strategies targeting anti-dsDNA antibodies, and discuss their potential clinical value.

Immunopathological events surrounding IL-6 and IFN-α: A bridge for anti-lupus erythematosus drugs used to treat COVID-19

With the outbreak and rapid spread of COVID-19, the world health situation is unprecedentedly severe. Systemic lupus erythematosus (SLE) is a common autoimmune disease, which can cause multiple organ damage. Numerous studies have shown that immune factors have important roles in the pathogenesis of both COVID-19 and SLE. In the early stages of COVID-19 and SLE pathogenesis, IFN-α expression is frequently increased, which aggravates the virus infection and promotes SLE development. In addition, increased IL-6 levels, caused by different mechanisms, are observed in the peripheral blood of patients with severe COVID-19 and SLE, stimulating a series of immune cascades that lead to a cytokine storm, as well as causing B cell hyperfunction and production of numerous of antibodies, aggravating both COVID-19 and SLE. In this review, we explore the background immunopathological mechanisms in COVID-19 and SLE and analyze the advantages and disadvantages of commonly used SLE drugs for patients with COVID-19, to optimize treatment plans for patients with SLE who develop COVID-19.

Smoking associates with increased BAFF and decreased interferon-γ levels in patients with systemic lupus erythematosus

Objective

In SLE, smoking increases the burden of cutaneous disease and organ damage, and leads to premature mortality. However, the effect of smoking on disease manifestations and cytokine levels of patients with SLE is unclear. This study compared characteristics of patients with SLE across smoking status, and determined the association of smoking with serum cytokine levels.

Method

A cross-sectional study of patients with SLE (n=99) during a research visit in which smoking status was ascertained. Smoking status was compared across classification criteria (American College of Rheumatology Classification Criteria for SLE (ACR97)), disease activity (SLE Disease Activity Index), autoantibody levels, accrued damage (Systemic Lupus International Collaborating Clinics/ACR Damage Index), and circulating concentrations of serum interferon-gamma (IFN-γ), interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-12, IL-17, B cell-activating factor (BAFF), tumour necrosis factor-alpha, transforming growth factor beta 1 (TGF-β1), macrophage inflammatory protein 1 alpha (MIP-1α), MIP-1β and monocyte chemoattractant protein 1. Linear regression models determined the association between smoking and cytokine levels, adjusting for age and sex, clinical characteristics (model 1), and anti-inflammatory (IL-4, IL-10 and TGF- β1) and regulatory (IL-1β) cytokines (model 2).

Results

Among patients with SLE (97.9% ANA+; mean 48.48 years old; 86.9% female; mean 10 years of disease duration), 35.4% (n=35 of 99) were smoking (an average of 7 cigarettes/day for 24 years). Smokers had increased odds of prevalent ACR97 malar rash (OR 3.40, 95% CI 1.23 to 9.34) and mucosal ulcers (OR 3.31, 95% CI 1.36 to 8.05). Smokers had more arthritis (OR 3.19, 95% CI 1.19 to 8.60), migraine (OR 2.82, 95% CI 1.07 to 7.44), Raynaud’s phenomenon (OR 5.15, 95% CI 1.95 to 13.56) and increased non-steroidal anti-inflammatory drug use (OR 6.88, 95% CI 1.99 to 23.72). Smoking associated with 27% increased BAFF levels (95% CI 6% to 48%) and 42% decreased IFN-γ levels (95% CI −79% to −5%) in model 2.

Conclusion

In patients with SLE, smoking independently associated with increased BAFF and decreased IFN-γ levels, and an increased frequency of arthritis, migraine and Raynaud’s phenomenon. Smoking cessation is advisable to reduce systemic inflammation, reduce disease activity and improve host defence.

Shared Pathogenetic Features Between Common Variable Immunodeficiency and Sjögren's Syndrome: Clues for a Personalized Medicine

Common variable immunodeficiency disorders (CVID) are a group of rare diseases of the immune system and the most common symptomatic primary antibody deficiency in adults. The “variable” aspect of CVID refers to the approximately half of the patients who develop non-infective complications, mainly autoimmune features, in particular organ specific autoimmune diseases including thyroiditis, and cytopenias. Among these associated conditions, the incidence of lymphoma, including mucosal associated lymphoid tissue (MALT) type, is increased. Although these associated autoimmune disorders in CVID are generally attributed to Systemic Lupus Erythematosus (SLE), we propose that Sjogren’s syndrome (SS) is perhaps a better candidate for the associated disease. SS is an autoimmune disorder characterized by the lymphocytic infiltrates of lacrimal and salivary glands, leading to dryness of the eyes and mouth. Thus, it is a lymphocyte aggressive disorder, in contrast to SLE where pathology is generally attributed to auto-antibody and complement activation. Although systemic lupus erythematosus (SLE) shares these features with SS, a much higher frequency of MALT lymphoma distinguishes SS from SLE. Also, the higher frequency of germ line encoded paraproteins such as the monoclonal rheumatoid factor found in SS patients would be more consistent with the failure of B-cell VDJ switching found in CVID; and in contrast to the hypermutation that characterizes SLE autoantibodies. Thus, we suggest that SS may fit as a better “autoimmune” association with CVID. Examining the common underlying biologic mechanisms that promote lymphoid infiltration by dysregulated lymphocytes and lymphoma in CVID may provide new avenues for treatment in both the diseases. Since the diagnosis of SLE or rheumatoid arthritis is usually based on specific autoantibodies, the associated autoimmune features of CVID patients may not be recognized in the absence of autoantibodies.

Altered Expression of TSPAN32 during B Cell Activation and Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease with various clinical features. Autoreactive B cells play a role in disease pathogenesis, through the production of multiple autoantibodies, which form immune complexes and induce the inflammatory response and tissue damage associated with SLE. Recently, tetraspanins, and in particular, TSPAN32, have been recognized to play a central role in immunity, as they are involved in various biological processes, such as the antigen presentation and the activation of lymphocytes. Evidence suggests that tetraspanins could represent in the future a target for therapeutic purposes in patients suffering from autoimmune/immunoinflammatory disorders. In the present study, by performing in silico analyses of high-throughput data, we evaluated the expression levels of TSPAN32 in B cell activation and investigated its modulation in circulating B cells from SLE patients. Our data show that B cell activation is associated with a significant downregulation of TSPAN32. Additionally, significantly lower levels of TSPAN32 were observed in circulating plasmablasts from SLE patients as compared to healthy donor plasmablasts. In addition, type I interferons (IFNs)-related genes were enriched among the genes negatively correlated to TSPAN32, in SLE plasmablasts. Accordingly, IFN-α is able to induce a dose-dependent downregulation of TSPAN32 in B cells. Overall, the data here presented suggest the potential use of TSPAN32 as a diagnostic marker and therapeutic target for the evaluation and management of humoral immune responses in chronic diseases, such as SLE.