The rationale for BAFF inhibition in systemic lupus erythematosus

Sequential immunotherapy: towards cures for autoimmunity

Despite major progress in the treatment of autoimmune diseases in the past two decades, most therapies do not cure disease and can be associated with increased risk of infection through broad suppression of the immune system. However, advances in understanding the causes of autoimmune disease and clinical data from novel therapeutic modalities such as chimeric antigen receptor T cell therapies provide evidence that it may be possible to re-establish immune homeostasis and, potentially, prolong remission or even cure autoimmune diseases. Here, we propose a 'sequential immunotherapy' framework for immune system modulation to help achieve this ambitious goal. This framework encompasses three steps: controlling inflammation; resetting the immune system through elimination of pathogenic immune memory cells; and promoting and maintaining immune homeostasis via immune regulatory agents and tissue repair. We discuss existing drugs and those in development for each of the three steps. We also highlight the importance of causal human biology in identifying and prioritizing novel immunotherapeutic strategies as well as informing their application in specific patient subsets, enabling precision medicine approaches that have the potential to transform clinical care.

B- and T-Lymphocyte Attenuator in Systemic Lupus Erythematosus Disease Pathogenesis

B- and T-lymphocyte attenuator (BTLA; CD272) is an immunoglobulin superfamily member and part of a family of checkpoint inhibitory receptors that negatively regulate immune cell activation. The natural ligand for BTLA is herpes virus entry mediator (HVEM; TNFRSF14), and binding of HVEM to BTLA leads to attenuation of lymphocyte activation. In this study, we evaluated the role of BTLA and HVEM expression in the pathogenesis of systemic lupus erythematosus (SLE), a multisystem autoimmune disease. Peripheral blood mononuclear cells from healthy volunteers (N = 7) were evaluated by mass cytometry by time-of-flight to establish baseline expression of BTLA and HVEM on human lymphocytes compared with patients with SLE during a self-reported flare (N = 5). High levels of BTLA protein were observed on B cells, CD4+, and CD8+ T cells, and plasmacytoid dendritic cells in healthy participants. HVEM protein levels were lower in patients with SLE compared with healthy participants, while BTLA levels were similar between SLE and healthy groups. Correlations of BTLA-HVEM hub genes' expression with patient and disease characteristics were also analyzed using whole blood gene expression data from patients with SLE (N = 1,760) and compared with healthy participants (N = 60). HVEM, being one of the SLE-associated genes, showed an exceptionally strong negative association with disease activity. Several other genes in the BTLA-HVEM signaling network were strongly (negative or positive) correlated, while BTLA had a low association with disease activity. Collectively, these data provide a clinical rationale for targeting BTLA with an agonist in SLE patients with low HVEM expression.

The noncanonical NFκB pathway: Regulatory mechanisms in health and disease

The noncanonical NFκB signaling pathway mediates the biological functions of diverse cell survival, growth, maturation, and differentiation factors that are important for the development and maintenance of hematopoietic cells and immune organs. Its dysregulation is associated with a number of immune pathologies and malignancies. Originally described as the signaling pathway that controls the NFκB family member RelB, we now know that noncanonical signaling also controls NFκB RelA and cRel. Here, we aim to clarify our understanding of the molecular network that mediates noncanonical NFκB signaling and review the human diseases that result from a deficient or hyper-active noncanonical NFκB pathway. It turns out that dysregulation of RelA and cRel, not RelB, is often implicated in mediating the resulting pathology. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Cancer > Molecular and Cellular Physiology Immune System Diseases > Stem Cells and Development.

Dysregulated MicroRNAs in the Pathogenesis of Systemic Lupus Erythematosus: A Comprehensive Review

Systemic lupus erythematosus is a chronic autoimmune disease of which clinical presentation is vastly heterogeneous, ranging from mild skin rashes to severe renal diseases. Treatment goal of this illness is to minimize disease activity and prevent further organ damage. In recent years, much research has been done on the epigenetic aspects of SLE pathogenesis, for among the various factors known to contribute to the pathogenic process, epigenetic factors, especially microRNAs, bear the most therapeutic potential that can be altered unlike congenital genetic factors. This article reviews and updates what has been discovered so far about the pathogenesis of lupus, while focusing on the dysregulation of microRNAs in lupus patients in comparison to healthy controls along with the potentially pathogenic roles of the microRNAs commonly reported to be either upregulated or downregulated. Furthermore, this review includes microRNAs of which results are controversial, suggesting possible explanations for such discrepancies and directions for future research. Moreover, we aimed to emphasize the point that had been overlooked so far in studies regarding microRNA expression levels; that is, which specimen was used to assess the dysregulation of microRNAs. To our surprise, a vast number of studies have not considered this factor and have analyzed the potential role of microRNAs in general. Despite extensive investigations done on microRNA levels, their significance and potential role remain a mystery, which calls for further studies on this particular subject in regard of which specimen is used for assessment.

Elevated serum level of B-cell activating factor (BAFF) after rituximab therapy in pemphigus vulgaris patients suggests a possible therapeutic efficacy of B-cell depletion therapies combined with anti-BAFF agents

BACKGROUND

Rituximab is widely used for treatment of pemphigus patients. B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) play key roles in B cell survival, maturation, and differentiation. Here, the effect of rituximab on BAFF and APRIL in patients with pemphigus vulgaris (PV) was studied.

METHODS

Fifty PV cases and 56 healthy individuals were recruited. Patients received rituximab for a period of 6 months. The levels of BAFF and APRIL were measured in the serum samples. The frequency of CD19+ B cells was measured by flow cytometry.

RESULTS

The level of BAFF was significantly higher in the patients at the baseline level than controls (P = 0.0005). The level of BAFF was significantly higher at the 3rd month follow-up compared to the baseline (P = 0.033). There was a significant increase in the BAFF level at the 6th month follow-up compared to baseline (P = 0.0134). There was no significant difference in the CD19+ B cells/total lymphocytes ratio in the PV patients between the 3rd and 6th month follow-ups.

CONCLUSIONS

Elevated BAFF in the sera could be associated with PV immunopathogenesis. Inhibition of BAFF after rituximab therapy might interfere with repopulation of B cells and confer a therapeutic approach in PV.

A novel selective spleen tyrosine kinase inhibitor SKI-O-703 (cevidoplenib) ameliorates lupus nephritis and serum-induced arthritis in murine models

Spleen tyrosine kinase (Syk) plays a pivotal role in the activation of B cells and innate inflammatory cells by transducing immune receptor-triggered signals. Dysregulated activity of Syk is implicated in the development of antibody-mediated autoimmune diseases including systemic lupus erythematosus (SLE) and rheumatoid arthritis, but the effect of Syk inhibition on such diseases remains to be fully evaluated. We have developed a novel selective Syk inhibitor, SKI-O-592, and its orally bioavailable salt form, SKI-O-703 (cevidoplenib). To examine the efficacy of SKI-O-703 on the progression of SLE, New Zealand black/white mice at the autoimmunity-established phase were administrated orally with SKI-O-703 for 16 weeks. Levels of IgG autoantibody, proteinuria, and glomerulonephritis fell significantly, and this was associated with hypoactivation of follicular B cells via the germinal center. In a model of serum-transferred arthritis, SKI-O-703 significantly ameliorated synovitis, with fewer neutrophils and macrophages infiltrated into the synovial tissue. This effect was recapitulated when mice otherwise refractory to anti-TNF therapy were treated by TNF blockade combined with a suboptimal dose of SKI-O-703. These results demonstrate that the novel selective Syk inhibitor SKI-O-703 attenuates the progression of autoantibody-mediated autoimmune diseases by inhibiting both autoantibody-producing and autoantibody-sensing cells.

Subclinical atherosclerosis profiles in rheumatoid arthritis and primary Sjögren's syndrome: the impact of BAFF genetic variations

OBJECTIVES

RA and primary SS carry increased atherosclerotic risk, while B-cell activating factor holds a vital role in disease pathogenesis and atherosclerosis. We aimed to compare subclinical atherosclerosis profiles between the two clinical entities and define whether BAFF genetic variants alter atherosclerotic risk.

METHODS

DNA from 166 RA, 148 primary SS patients and 200 healthy controls of similar age and sex distribution was subjected to PCR-based assay for the detection of five single nucleotide polymorphisms of the BAFF gene (rs1224141, rs12583006, rs9514828, rs1041569 and rs9514827). Genotype and haplotype frequencies were determined by SNPStats software and statistical analysis was performed by SPSS and Graphpad Software. Subclinical atherosclerosis was defined by the presence of carotid/femoral plaque formation and arterial wall thickening.

RESULTS

Atherosclerotic plaque formation was more frequently detected in the RA vs primary SS group (80.7% vs 62.2%, P-value <0.001), along with higher rates of family CVD history, current steroid dose and serum inflammatory markers. The TT genotype of the rs1224141 variant was more prevalent in RA but not primary SS patients with plaque and arterial wall thickening vs their counterparts without. Regarding the rs1014569 variant, among RA patients the TT genotype increased the risk for plaque formation while in primary SS patients the AT genotype conferred increased risk. Haplotype GTTTT was protective in the RA cohort, while TATTT and TTCTT haplotypes increased susceptibility for arterial wall thickening in the primary SS cohort.

CONCLUSIONS

Increased inflammatory burden, higher steroid doses and distinct BAFF gene variations imply chronic inflammation and B-cell hyperactivity as key contributors for the augmented atherosclerotic risk among autoimmune patients.

Belimumab for systemic lupus erythematosus - Focus on lupus nephritis

In recent years, advances in the treatment and management of patients with systemic lupus erythematosus (SLE) have improved their life expectancy and quality of life. However, lupus nephritis (LN) still represents a major life-threatening complication of the disease. Belimumab (BEL), a fully human monoclonal IgG1λ antibody neutralizing soluble B cell activating factor, was approved more than ten years ago as add-on therapy in adults and pediatric patients with a highly active, autoantibody-positive disease despite standard of care (SoC). Recently, the superiority of the addition of BEL to SoC was also demonstrated in LN. In this review, we provide a comprehensive overview of the study landscape, available therapeutic options for SLE (focusing on BEL in renal and non-renal SLE), and new perspectives in the treatment field of this disease. A personalized treatment approach will likely become available with the advent of novel therapeutic agents for SLE and LN.

Recent Advances in Understanding the Pathogenesis of Rheumatoid Arthritis: New Treatment Strategies

Rheumatoid arthritis (RA) is considered a chronic systemic, multi-factorial, inflammatory, and progressive autoimmune disease affecting many people worldwide. While patients show very individual courses of disease, with RA focusing on the musculoskeletal system, joints are often severely affected, leading to local inflammation, cartilage destruction, and bone erosion. To prevent joint damage and physical disability as one of many symptoms of RA, early diagnosis is critical. Auto-antibodies play a pivotal clinical role in patients with systemic RA. As biomarkers, they could help to make a more efficient diagnosis, prognosis, and treatment decision. Besides auto-antibodies, several other factors are involved in the progression of RA, such as epigenetic alterations, post-translational modifications, glycosylation, autophagy, and T-cells. Understanding the interplay between these factors would contribute to a deeper insight into the causes, mechanisms, progression, and treatment of the disease. In this review, the latest RA research findings are discussed to better understand the pathogenesis, and finally, treatment strategies for RA therapy are presented, including both conventional approaches and new methods that have been developed in recent years or are currently under investigation.

Rhupus: dual rheumatic disease

Autoimmune disorders are typically categorized into systematic and local diseases that affect a single organ or tissue. Organs and tissues affected by autoimmune disorders include components of the endocrine system, such as thyroid, pancreas, and adrenal glands; blood, such as red blood cells; and the connective tissues, skin, muscles, and joints. Rhupus is a complex musculoskeletal autoimmune disease (AD) in which features of both rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are simultaneously present. The cause and trigger of rhupus is still unknown, suggesting the role of genetic, immunological, hormonal, and environmental factors in the initiation and progression of the disease. The role of immune system has been established by the presence of specific autoantibodies as markers for diagnosis of rhupus and the formation of immune complex in serum. The complications of rhupus include the presence of rheumatoid factor (RF) and nodules and the involvement of nervous and renal systems that complicates its diagnosis and prognosis. The rhupus arthritis resembles RA-like pathophysiology and leads to inflammation, deformation, and disability. Due to the heterogeneity and rarity of the disease, the prevalence, pathophysiology, and natural history as well as radiological and immunological profiles of rhupus are still not properly understood.

The gene silencing of IRF5 and BLYSS effectively modulates the outcome of experimental lupus nephritis

Systemic lupus erythematosus is a highly complex and heterogeneous autoimmune disease mostly mediated by B cells. It is characterized by circulating self-reactive antibodies that deposit and form immune complexes in kidney, leading to irreparable tissue damage and resulting in lupus nephritis. In a New Zealand Black X New Zealand White F1 mouse model, we tested two different small interfering RNA (siRNA) silencing treatments against interferon regulatory factor 5 (IRF5) and B cell-activating factor (BLYSS) expression and their combination in a second set of animals. The administration of these two siRNAs separately prevented the progression of proteinuria and albuminuria at similar levels to that in cyclophosphamide animals. These treatments effectively resulted in a reduction of serum anti-double-stranded DNA (dsDNA) antibodies and histopathological renal score compared with non-treated group. Treated groups showed macrophage, T cell, and B cell infiltrate reduction in renal tissue. Moreover, kidney gene expression analysis revealed that siRNA treatments modulated very few pathways in contrast to cyclophosphamide, despite showing similar therapeutic effects. Additionally, the combined therapy tested in a second set of animals, in which the disease appeared more virulent, exhibited better results than monotherapies in the disease progression, delaying the disease onset and ameliorating the disease outcome. Herein, we provide the potential therapeutic effect of both selective IRF5 and BLYSS silencing as an effective and potential treatment, particularly in early phases of the disease.

Mining TCGA database for screening and identification of hub genes in kidney renal clear cell carcinoma microenvironment

To evaluate the diagnosis and prognosis of the tumor microenvironment (immunization and stromal cells) in kidney renal clear cell carcinoma (KIRC), KIRC cases selected from The Cancer Genome Atlas database were divided into two groups according to the ESTIMATE algorithm-derived immune scores. Our data suggested that the Von Hippel-Lindau mutations and pathologic grades are associated with immune scores. Importat ntly, we identified 173 differential expression genes (DEGs) associated with prognosis in patients with KIRC. Consequently, Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed on these DEGs, which included immune response, defense response, intrinsic to the plasma membrane, positive regulation of immune system process, and cytokine binding. Next, the protein-protein interaction network of DEGs and the most significant module was constructed. Five hub genes were identified and analyzed using biological analysis. The survival analysis of the hub genes showed that KIRC patients with high gene expression of C2, MXRA8, TNFSF13B, and X-linked inhibitor of apoptosis protein-associated factor 1 (XAF1) had worse overall survival, and MXRA8, TNFSF13B, and XAF1 alteration were significantly associated with disease-free survival (DFS). In addition, high gene expression of XAF1 alteration showed better DFS. Conclusion: we identified a list of microenvironment-related genes that are useful for understanding the molecular mechanisms and prognosis of KIRC.

An update on lupus animal models

PURPOSE OF REVIEW

The complexity and heterogeneity of the clinical presentation in systemic lupus of erythematosus (SLE), combined to the inherent limitations of clinical research, have made it difficult to investigate the cause of this disease directly in patients. Various mouse models have been developed to dissect the cellular and genetic mechanisms of SLE, as well as to identify therapeutic targets and to screen treatments. The purpose of this review is to summarize the major spontaneous and induced mouse models of SLE and to provide an update on the major advances they have contributed to the field.

RECENT FINDINGS

Mouse models of SLE have continued to contribute to understand the cellular, signaling and metabolic mechanisms contributing to the disease and how targeting these pathways can provide therapeutic targets. Whenever possible, we discuss the advantage of using one model over the others to test a specific hypothesis.

SUMMARY

Spontaneous and induced models of lupus models are useful tools for the study of the cause of the disease, identify therapeutic targets and screen treatments in preclinical studies. Each model shares specific subsets of attributes with the disease observed in humans, which provides investigators a tool to tailor to their specific needs.

The Lymphocytes Stimulation Induced DNA Release, a Phenomenon Similar to NETosis

The release of DNA into the extracellular milieu by neutrophil during a process called NETosis has been postulated as an additional source of autoantigens; a process believed to be important in the pathogenesis of some autoimmune disease, such as systemic lupus erythematosus (SLE). However, it is not established if the B and T cells undergo the release of DNA to the extracellular milleu, in response to different stimuli. In this study, it was observed that the treatment of B and T cells with PMA, ionomycin and the serum from patients with SLE induced the extracellular DNA presence in B and T cells. These findings suggest that the phenomenon were similar to those observed in neutrophil's Etosis; B and T cells also released their DNA into the extracellular milieu. The findings express that serum from patients with SLE and SLEDAI ≤ 8 triggers the release of extracellular DNA in neutrophils, B and T cells, that suggested the presence of soluble factors in the serum that favoured this phenomenon.

B-cell activating factor BAFF reflects patients' immunological risk profile after kidney transplantation

The B-cell activating factor BAFF plays an important role in the development and maturation of B-lymphocytes, which can contribute to the generation of donor-specific antibodies and thus may influence graft function and graft survival. Inconsistent data on the role of BAFF levels after renal transplantation for the formation of donor-specific antibodies and the contribution for allograft rejection exist. The aim of the current study was to determine to what extent the degree of pre-immunization is reflected by each patient's BAFF levels before transplantation and in the follow-up. Furthermore, the impact of BAFF on allograft rejection frequency as well as severity and resulting allograft function over time was analyzed. Additionally, the impact of viral infections on BAFF levels after transplantation - as a potential confounder - was examined. For this purpose, a group of pre-sensitized patients (PRA>0%, (52±24% on average), n=40) was compared with non-sensitized patients (PRA=0%, n=62) and in a subsequent analysis stratification in accordance to the detected BAFF level was performed. Pre-sensitized patients had significantly higher BAFF levels before transplantation and suffered significantly more often from early steroid-resistant, mainly antibody-mediated rejections. A result which was confirmed also in highly sensitized patients with PRA levels >50%. Additionally, in the follow-up patients with either rising BAFF levels over time or BAFF levels above the median also had significantly more often antibody mediated rejections. Additionally, patients with BAFF levels above detected median even displayed impaired creatinine values as well as an induced eGFR slope up to month 48 after transplantation. The occurrence of viral infections (CMV, BKV) was only an additional influencing factor in the absence of concomitant allograft rejections. Therefore, the B-cell proliferation factor BAFF appears not only to reflect the immunological risk profile of patients in the context of kidney transplantation, it may possibly be further developed as a predictor of patients with an increased risk profile for subsequent allograft rejection and impaired allograft function.

Characterization of BAFF and APRIL subfamily receptors in rainbow trout (Oncorhynchus mykiss). Potential role of the BAFF / APRIL axis in the pathogenesis of proliferative kidney disease

Proliferative kidney disease (PKD) is a parasitic infection of salmonid fish characterized by hyper-secretion of immunoglobulins in response to the presence of the myxozoan parasite, Tetracapsuloides bryosalmonae. In this context, we hypothesized that the BAFF/APRIL axis, known to play a major role in B cell differentiation and survival in mammals, could be affected by the parasite and consequently be involved in the apparent shift in normal B cell activity. To regulate B cell activity, BAFF and APRIL bind to transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B cell maturation antigen (BCMA), whereas BAFF also binds to BAFF receptor (BAFF-R). In teleost fish, although some BAFF and APRIL sequences have been reported, their receptors have not been identified. Thus, as a first step in the current work, we have identified homologues to mammalian TACI, BCMA and BAFF-R in rainbow trout (Oncorhynchus mykiss), that constitute the first report of BAFF and APRIL receptor sequences in fish. Subsequently we studied the transcriptional modulation of BAFF, APRIL, and the fish-specific related cytokine, BALM and their putative receptors in fish naturally exposed to T. bryosalmonae. Finally, to gain further insights on the functional role that these cytokines play during the course of PKD, we have studied their effect on the survival of kidney IgM⁺ B cells and on immunoglobulin transcription. Our results support the premise that the BAFF / APRIL axis could play an important role during PKD, which may open the possibility of new therapeutic treatments against the disease.

CP-25 attenuates the inflammatory response of fibroblast-like synoviocytes co-cultured with BAFF-activated CD4(+) T cells

ETHNOPHARMACOLOGICAL RELEVANCE

Total glucosides of paeony (TGP) is the first anti-inflammatory immune regulatory drug approved for the treatment of rheumatoid arthritis in China. A novel compound, paeoniflorin-6'-O-benzene sulfonate (code CP-25), comes from the structural modification of paeoniflorin (Pae), which is the effective active ingredient of TGP. The aim of the present study is to investigate the effect of CP-25 on adjuvant arthritis (AA) fibroblast-like synoviocytes (FLS) co-cultured with BAFF-activated CD4(+) T cells and the expression of BAFF-R in CD4(+) T cells.

METHODS

The mRNA expression of BAFF and its receptors was assessed by qPCR. The expression of BAFF receptors in CD4(+) T cells was analyzed by flow cytometry. The effect of CP-25 on AA rats was evaluated by their joint histopathology. The cell culture growth of thymocytes and FLS was detected by cell counting kit (CCK-8). The concentrations of IL-1β, TNF-α, and IL-6 were measured by Enzyme-linked immunosorbent assay (ELISA).

RESULTS

The mRNA expression levels of BAFF and BAFF-R were enhanced in the mesenteric lymph nodes of AA rats, TACI expression was reduced, and BCMA had no change. The expression of BAFF-R in CD4(+) T cells was also enhanced. CP-25 alleviated the joint histopathology and decreased the expression of BAFF-R in CD4(+) T cells from AA rats in vivo. In vitro, CP-25 inhibited the abnormal cell culture growth of BAFF-stimulated thymocytes and FLS. In the co-culture system, IL-1β, IL-6 and TNF-α production was enhanced by FLS co-cultured with BAFF-activated CD4(+) T cells. Moreover, BAFF-stimulated CD4(+) T cells promoted the cell culture growth of FLS. The addition of CP-25 decreased the expression of BAFF-R in CD4(+) T cells and inhibited the cell culture growth and cytokine secretion ability of FLS co-cultured with BAFF-activated CD4(+) T cells.

CONCLUSION

The present study indicates that CP-25 may repress the cell culture growth and cytokine secretion ability of FLS, and its inhibitory effects might be associated with its ability to inhibit the expression of BAFF-R in CD4(+) T cells in a co-culture. These observations might provide a scientific basis for the development of new drugs for the treatment of autoimmune diseases by CP-25.

Success and failure of biological treatment in systemic lupus erythematosus: A critical analysis

Patients affected with systemic lupus erythematosus (SLE) still display increased mortality and decreased quality of life in respect to general population. The major determinant of poor long term prognosis is organ damage, which is predictive of more damage and death. Damage is in turn triggered by uncontrolled disease activity and especially by the long-standing corticosteroid use which often accompanies SLE patients over their disease course, owing both to the need of reaching disease remission and to the habit of keeping patients on a small steroid dose for an indefinite period of time. Hence, the need for new drugs and therapeutic strategies aiming at minimizing damage accrual through a better control of disease activity and a steroid-sparing potential is paramount. So far, however, the therapeutic strategy in SLE requires a multitarget approach which is not devoid of widespread immunesuppression. In fact, several studies have been carried out in recent years targeting both the adaptive and the innate immune system, the majority of which did not achieve their primary endpoint, being often divergent from successful clinical experience and thereby committing physician to off-label use of targeted therapies in face of refractory SLE manifestations. The study designs and the chosen endpoints were often blamed for inadequacy, being at least in part responsible for study failures. In this review, we go over major clinical trials conducted in SLE by analyzing any critical aspects related to study design, predefined endpoints and biological activity of novel compounds that may have hampered study outcome, despite the great effort of providing less toxic drugs within a targeted, pathogenic-based approach.

Phase 1 Study of Tabalumab, a Human Anti-B-Cell Activating Factor Antibody, and Bortezomib in Patients with Relapsed/Refractory Multiple Myeloma

PURPOSE

Tabalumab, a human mAb that neutralizes B-cell-activating factor (BAFF), demonstrated antitumor activity in xenograft models of multiple myeloma. Here we report on a phase I study of relapsed/refractory multiple myeloma patients in which the primary objective was to identify a tolerable and potentially efficacious dose of tabalumab when combined with bortezomib.

EXPERIMENTAL DESIGN

Forty-eight patients were enrolled; 20 to the dose-escalation cohort, and 28 to cohort expansion in which a dose of 100 mg of tabalumab was evaluated. All patients had received either prior bortezomib or an immunomodulatory drug; the median number of prior therapies was 3. Bortezomib was administered intravenously on days 1, 4, 8, and 11 of a 21-day schedule. Tabalumab was given every 21 days for 3 cycles, then every 42 days thereafter.

RESULTS

The most common grade 3/4 toxicities included thrombocytopenia, neutropenia, pneumonia, and peripheral sensory neuropathy. There were no dose-limiting toxicities, and the maximum tolerated dose was not reached. Pharmacokinetic data suggested serum exposure increased in a greater than dose-proportional manner up to a dose of 100 mg. Out of 46 evaluable patients, 20 had confirmed responses. The median time to progression (9 patients censored) was 4.8 months, and the median response duration (4 patients censored) was 7.2 months.

CONCLUSIONS

A dose of 100 mg tabalumab in combination with bortezomib was well tolerated and active and is currently under further investigation. Clin Cancer Res; 22(23); 5688-95. ©2016 AACR.

BANK1 Regulates IgG Production in a Lupus Model by Controlling TLR7-Dependent STAT1 Activation

The purpose of our study was to investigate the effects of the adaptor Bank1 in TLR7 signaling using the B6.Sle1.yaa mouse, a lupus model that develops disease through exacerbated TLR7 expression. Crosses of B6.Sle1.yaa with Bank1^-/- mice maintained several B and myeloid cell phenotypes close to normal wild-type levels. Most striking was the reduction in total serum IgG antibodies, but not of IgM, and reduced serum levels of autoantibodies, IL-6, and BAFF. Bank1 deficiency did modify numbers of MZ B cells and total B cell numbers, as well as expression of CXCR4 by follicular helper T cells. Other T cell changes were not observed. Bank1 deficiency did not modify numbers of germinal center B cells or plasma cells or clinical disease outcomes. Purified B cells from Bank1 deficient mice had strongly reduced Ifnb, Ifna4, Irf7, Aicda and Stat1 gene expression following TLR7 agonist stimulation. Interestingly, phosphorylation of Tyr701, but not of Ser727 of STAT1, was impaired in splenic B cells from B6.Sle1.yaa.Bank1-/- mice, as was the nuclear translocation of IRF7 in response to TLR7 agonist stimulation. Further, Bank1 deficiency in B6.Sle1.yaa mice reduced the production of IgG2c after in vitro TLR7 agonist stimulation. Our results demonstrate that Bank1 controls TLR7-mediated type I interferon production. Combined with the control of the nuclear translocation of IRF7, the modulation of STAT1 transcription and phosphorylation, Bank1 contributes to IgG production during development of autoimmune disease.

Emerging therapies in immunoglobulin A nephropathy

Despite advances in our understanding of immunoglobulin A nephropathy (IgAN) over the past decade, there are currently no specific therapies capable of targeting key pathways involved in the pathogenesis of the disease. Recent studies have, however, provided new insights into important molecular pathways that are likely to be amenable to therapeutic manipulation in the future. Specifically, a deeper understanding of the role of mucosal immunity, B-cell activation and mesangial cell activation in IgAN has provided the impetus for a number of exciting phase II/III clinical trials in IgAN. In this review, we examine some of these on-going studies, first examining studies that clarify the role of traditional immunosuppression in IgAN, then focusing on novel therapies in early clinical studies, looking closely at the rationale for these agents in relation to our current understanding of the pathogenesis of IgAN. Finally, we examine emerging pathways and therapeutic agents that have the potential to be developed as novel therapies in the coming years. It is hoped that as we continue to develop a greater understanding of IgAN, emerging therapies will soon become a reality in the day-to-day treatment of patients with IgAN.

Decrease of Functional Activated T and B Cells and Treatment of Glomerulonephitis in Lupus-Prone Mice Using a Natural Flavonoid Astilbin

Treatment of systemic lupus erythematosus (SLE), a chronic inflammatory disease, involves the long-term use of immunosuppressive agents with significant side effects. New therapeutic approaches are being explored to find better treatment possibilities. In this study, age-matched female MRL/lpr mice were treated orally with a natural flavonoid astilbin. Astilbin administration started either at week 8 or week 12 of age though week 20. In the early treatment regimen, the treatment with astilbin reduced splenomegaly / lymphomegaly, autoantibody production and ameliorated lupus nephitis. Several serum cytokines were significantly decreased upon treatment including IFN-g, IL-17A, IL-1b, TNF-a and IL-6. Both spleen CD44^hiCD62L^lo activated T cells and CD138⁺B220^- plasma cells greatly declined. Furthermore, astilbin treatment resulted in decreased mitochondrial membrane potential in activated T cells and downregulated expression of the co-stimulatory molecules CD80 and CD86 on LPS stimulated B cells. Similar but less profound effectiveness was observed in the mice with established disease in the late treatment regimen. These results indicate that the natural product astilbin can mitigate disease development in lupus-prone mice by decreasing functional activated T and B cells.

Cellular signaling and production of galactose-deficient IgA1 in IgA nephropathy, an autoimmune disease

Immunoglobulin A (IgA) nephropathy (IgAN), the leading cause of primary glomerulonephritis, is characterized by IgA1-containing immunodeposits in the glomeruli. IgAN is a chronic disease, with up to 40% of patients progressing to end-stage renal disease, with no disease-specific treatment. Multiple studies of the origin of the glomerular immunodeposits have linked elevated circulating levels of aberrantly glycosylated IgA1 (galactose-deficient in some O-glycans; Gd-IgA1) with formation of nephritogenic Gd-IgA1-containing immune complexes. Gd-IgA1 is recognized as an autoantigen in susceptible individuals by anti-glycan autoantibodies, resulting in immune complexes that may ultimately deposit in the kidney and induce glomerular injury. Genetic studies have revealed that an elevated level of Gd-IgA1 in the circulation of IgAN patients is a hereditable trait. Moreover, recent genome-wide association studies have identified several immunity-related loci that associated with IgAN. Production of Gd-IgA1 by IgA1-secreting cells of IgAN patients has been attributed to abnormal expression and activity of several key glycosyltransferases. Substantial evidence is emerging that abnormal signaling in IgA1-producing cells is related to the production of Gd-IgA1. As Gd-IgA1 is the key autoantigen in IgAN, understanding the genetic, biochemical, and environmental aspects of the abnormal signaling in IgA1-producing cells will provide insight into possible targets for future disease-specific therapy.

Neutrophils contribute to excess serum BAFF levels and promote CD4+ T cell and B cell responses in lupus-prone mice

Despite increased frequencies of neutrophils found in autoimmune diseases such as systemic lupus erythematosus (SLE), how they contribute to disease pathogenesis and the mechanisms that affect the accumulation of neutrophils are poorly understood. The aim of this study was to identify factors in autoantibody-mediated autoimmunity that controls the accumulation of spleen resident neutrophils and to determine whether neutrophils contribute to abnormal B cell responses. Increased levels of the cytokine BAFF have been linked to loss of B cell tolerance in autoimmunity, but the cellular source responsible for excess BAFF is unknown. B cell maturation antigen (BCMA) is a receptor for BAFF and is critical for the survival of bone marrow plasma cells. Paradoxically, BCMA deficiency exacerbates the formation of autoantibody-secreting plasma cells in spleens of lupus-prone mice and the reasons for this effect are not understood. Here we analyzed the phenotype, localization and function of neutrophils in spleens of healthy mice and congenic lupus-prone mice, and compared mice sufficient or deficient in BCMA expression. Neutrophils were found to be significantly increased in frequency and activation status in spleens of lupus-prone mice when BCMA was absent. Furthermore, neutrophils localized within T cell zones and enhanced CD4⁺ T cell proliferation and IFNγ production through the production of BAFF. Reduced BAFF and IFNγ serum levels, decreased frequencies of IFNγ-producing T cells, germinal center B cells, and autoantibody production after neutrophil depletion indicated the involvement of neutrophils in these autoimmune traits. Thus, we have identified a novel role for BCMA to control excess BAFF production in murine lupus through restraining the accumulation of BAFF-producing neutrophils. Our data suggests that devising therapeutic strategies to reduce neutrophils in autoimmunity may decrease BAFF levels and ameliorate disease.

IFN-gamma AU-rich element removal promotes chronic IFN-gamma expression and autoimmunity in mice

We generated a mouse model with a 162 nt AU-rich element (ARE) region deletion in the 3' untranslated region (3'UTR) of the interferon-gamma (IFN-γ) gene that results in chronic circulating serum IFN-γ levels. Mice homozygous for the ARE deletion (ARE-Del) (-/-) present both serologic and cellular abnormalities typical of patients with systemic lupus erythematosus (SLE). ARE-Del(-/-) mice display increased numbers of pDCs in bone marrow and spleen. Addition of IFN-γ to Flt3-ligand (Flt3L) treated in vitro bone marrow cultures results in a 2-fold increase in pDCs with concurrent increases in IRF8 expression. Marginal zone B (MZB) cells and marginal zone macrophages (MZMs) are absent in ARE-Del(-/-) mice. ARE-Del(+/-) mice retain both MZB cells and MZMs and develop no or mild autoimmunity. However, low dose clodronate treatment in ARE-Del(+/-) mice specifically eliminates MZMs and promotes anti-DNA antibody development and glomerulonephritis. Our findings demonstrate the consequences of a chronic IFN-γ milieu on B220(+) cell types and in particular the impact of MZB cell loss on MZM function in autoimmunity. Furthermore, similarities between disease states in ARE-Del(-/-) mice and SLE patients suggest that IFN-γ may not only be a product of SLE but may be critical for disease onset and progression.

Improving outcomes in patients with lupus and end-stage renal disease

The development of lupus-related end-stage renal disease (ESRD) confers the highest mortality rates among individuals with lupus. Lupus-related ESRD is also associated with higher morbidity and mortality rates compared with non-lupus ESRD. We review the evidence that persistent lupus activity, hypercoagulability, and continuing immunosuppression may contribute to unfavorable outcomes in dialysis and renal transplantation among lupus patients. Robust epidemiologic studies are needed to develop individualized evidence-based approaches to treating lupus-related ESRD. In the meantime, managing lupus-related ESRD presents a significant challenge for clinicians and requires a team approach involving nephrologists and rheumatologists. Goals of therapy after developing ESRD should include continuing monitoring of lupus activity, minimizing corticosteroid exposure, and choosing the most appropriate renal replacement therapy based on patient's risk profile and quality-of-life considerations.

Galectin-9 ameliorates clinical severity of MRL/lpr lupus-prone mice by inducing plasma cell apoptosis independently of Tim-3

Galectin-9 ameliorates various murine autoimmune disease models by regulating T cells and macrophages, although it is not known what role it may have in B cells. The present experiment shows that galectin-9 ameliorates a variety of clinical symptoms, such as proteinuria, arthritis, and hematocrit in MRL/lpr lupus-prone mice. As previously reported, galectin-9 reduces the frequency of Th1, Th17, and activated CD8(+) T cells. Although anti-dsDNA antibody was increased in MRL/lpr lupus-prone mice, galectin-9 suppressed anti-dsDNA antibody production, at least partly, by decreasing the number of plasma cells. Galectin-9 seemed to decrease the number of plasma cells by inducing plasma cell apoptosis, and not by suppressing BAFF production. Although about 20% of CD19(-/low) CD138(+) plasma cells expressed Tim-3 in MRL/lpr lupus-prone mice, Tim-3 may not be directly involved in the galectin-9-induced apoptosis, because anti-Tim-3 blocking antibody did not block galectin-9-induced apoptosis. This is the first report of plasma cell apoptosis being induced by galectin-9. Collectively, it is likely that galectin-9 attenuates the clinical severity of MRL lupus-prone mice by regulating T cell function and inducing plasma cell apoptosis.