B cell maturation protein is a receptor for the tumor necrosis factor family member TALL-1

Past and present discovery of the BAFF/APRIL system - A bibliometric study from 1999 to 2023

Cytokines from the Tumour Necrosis Factor (TNF) family are important regulators of both physiological and pathological processes. The discovery of novel TNF ligands and receptors, BAFF and APRIL, have opened up new possibilities for scientists to explore the effect of these cytokines on the human immune system. The role of BAFF/APRIL system in B lymphocytes is particularly important for survival and maintenance of homeostasis. Aberrant expression of the system is associated with various immunological disorders. Hence, this study provides a comprehensive overview of the past and present BAFF/APRIL system research development in a bibliometric perspective. To our best knowledge, this is the first ever bibliometric analysis conducted focusing on the BAFF/APRIL system. A total of 1055 relevant documents were retrieved from WoSCC. Microsoft Excel, VOSviewer, and Biblioshiny of R studio were bibliometric tools used to analyse the scientific literature. From 1999, the annual publications showed an upward trend, with Journal of Immunology being the most productive journal. USA leads the race for BAFF/APRIL system research developments. Pascal Schneider, a senior researcher affiliated with University of Lausanne, Switzerland was recognised as the most productive author and institution in the BAFF/APRIL system research field. The research focus transitioned from focusing on the role of the system in B cell biology, to immunological disorders and finally to development of BAFF/APRIL targeting drugs. Despite several studies elucidating briefly the pathway mechanism of BAFF/APRIL system in B-cell selection, substantial research on the mechanism of action in disease models and T cell activation and development of immunomodulating drugs from natural origins remains largely unexplored. Therefore, future research focusing on these areas are crucial for the deeper understanding of the system in disease manifestations and progression allowing a better treatment management for various immunological disorders.

BCMA-targeting chimeric antigen receptor T-cell therapy for multiple myeloma

Multiple myeloma (MM) remains an incurable hematologic malignancy, despite the development of numerous innovative therapies during the past two decades. Immunotherapies are changing the treatment paradigm of MM and have improved the overall response and survival of patients with relapsed/refractory (RR) MM. B cell maturation antigen (BCMA), selectively expressed in normal and malignant plasma cells, has been targeted by several immunotherapeutic modalities. Chimeric antigen receptor (CAR) T cells, the breakthrough in cancer immunotherapy, have revolutionized the treatment of B cell malignancies and remarkably improved the prognosis of RRMM. BCMA-targeting CAR T cell therapy is the most developed CAR T cell therapy for MM, and the US Food and Drug Administration has already approved idecabtagene vicleucel (Ide-cel) and ciltacabtagene autoleucel (Cilta-cel) for MM. However, the development of novel BCMA-targeting CAR T cell therapies remains in progress. This review focuses on BCMA-targeting CAR T cell therapy, covering all stages of investigational progress, including the innovative preclinical studies, the initial phase I clinical trials, and the more developed phase II clinical trials. It also discusses possible measures to improve the efficacy and safety of this therapy.

Dual Role of B Cells in Multiple Sclerosis

B cells have emerged as an important immune cell type that can be targeted for therapy in multiple sclerosis (MS). Depleting B cells with anti-CD20 antibodies is effective in treating MS. Yet, atacicept treatment, which blocks B-cell Activating Factor (BAFF) and A Proliferation-Inducing Ligand (APRIL), two cytokines important for B cell development and function, paradoxically increases disease activity in MS patients. The reason behind the failure of atacicept is not well understood. The stark differences in clinical outcomes with these therapies demonstrate that B cells have both inflammatory and anti-inflammatory functions in MS. In this review, we summarize the importance of B cells in MS and discuss the different B cell subsets that perform inflammatory and anti-inflammatory functions and how therapies modulate B cell functions in MS patients. Additionally, we discuss the potential anti-inflammatory functions of BAFF and APRIL on MS disease.

B cell depletion and inhibition in systemic lupus erythematosus

INTRODUCTION

Systemic lupus erythematosus (SLE) is characterized by autoantibody expression and aberrant autoreactive B cells contribute to disease progression; therefore, B cell inhibition has been an attractive target for novel therapies. However, after more than two decades of research and over 40 randomized clinical trials, only one such therapy, belimumab, has been approved for use in SLE.

AREAS COVERED

In this review, we discuss the evidence for B cell-targeted therapies in SLE and lupus nephritis. Belimumab has been successful in several large clinical trials and is approved in several countries for use in SLE and lupus nephritis. Despite a lack of supporting phase III evidence, rituximab is used off-label in SLE. Several other B cell-targeted therapies have failed to meet their end points in late-stage clinical trials. Successful phase II trials have recently been reported for obinutuzumab and telitacicept with larger confirmatory trials currently underway.

EXPERT OPINION

Refinements in pharmaceutical mechanisms of action, trial design, and patient selection have resulted in recent preliminary successes, offering renewed optimism for B-cell targeted therapeutics in SLE management.

sBCMA Plasma Level Dynamics and Anti-BCMA CAR-T-Cell Treatment in Relapsed Multiple Myeloma

BACKGROUND

Novel chimeric antigen receptor T-cells (CAR-T) target the B-cell maturation antigen (BCMA) expressed on multiple myeloma cells. Assays monitoring CAR-T cell expansion and treatment response are being implemented in clinical routine.

METHODS

Plasma levels of soluble BCMA (sBCMA) and anti-BCMA CAR-T cell copy numbers were monitored in the blood, following CAR-T cell infusion in patients with relapsed multiple myeloma. sBCMA peptide concentration was determined in the plasma, applying a human BCMA/TNFRS17 ELISA. ddPCR was performed using probes targeting the intracellular signaling domains 4-1BB und CD3zeta of the anti-BCMA CAR-T construct.

RESULTS

We report responses in the first five patients who received anti-BCMA CAR- T cell therapy at our center. Four patients achieved a complete remission (CR) in the bone marrow one month after CAR-T infusion, with three patients achieving stringent CR, determined by flow cytometry techniques. Anti-BCMA CAR-T cells were detectable in the peripheral blood for up to 300 days, with copy numbers peaking 7 to 14 days post-infusion. sBCMA plasma levels started declining one to ten days post infusion, reaching minimal levels 30 to 60 days post infusion, before rebounding to normal levels.

CONCLUSIONS

Our data confirm a favorable response to treatment in four of the first five patients receiving anti-BCMA CAR-T at our hospital. Anti-BCMA CAR-T cell expansion seems to peak in the peripheral blood in a similar pattern compared to the CAR-T cell products already approved for lymphoma treatment. sBCMA plasma level may be a valid biomarker in assessing response to BCMA-targeting therapies in myeloma patients.

B-cell maturation antigen targeting strategies in multiple myeloma treatment, advantages and disadvantages

B cell maturation antigen (BCMA), a transmembrane glycoprotein member of the tumor necrosis factor receptor superfamily 17 (TNFRSF17), highly expressed on the plasma cells of Multiple myeloma (MM) patients, as well as the normal population. BCMA is used as a biomarker for MM. Two members of the TNF superfamily proteins, including B-cell activating factor (BAFF) and A proliferation-inducing ligand (APRIL), are closely related to BCMA and play an important role in plasma cell survival and progression of MM. Despite the maximum specificity of the monoclonal antibody technologies, introducing the tumor-specific antigen(s) is not applicable for all malignancies, such as MM that there plenty of relatively specific antigens such as GPCR5D, MUC1, SLAMF7 and etc., but higher expression of BCMA on these cells in comparison with normal ones can be regarded as a relatively exclusive marker. Currently, different monoclonal antibody (mAb) technologies applied in anti-MM therapies such as daratuzumab, SAR650984, GSK2857916, and CAR-T cell therapies are some of these tools that are reviewed in the present manuscript. By the way, the structure, function, and signaling of the BCMA and related molecule(s) role in normal plasma cells and MM development, evaluated as well as the potential side effects of its targeting by different CAR-T cells generations. In conclusion, BCMA can be regarded as an ideal molecule to be targeted in immunotherapeutic methods, regarding lower potential systemic and local side effects.

Risk Factors Associated with Durable Progression-Free Survival in Patients with Relapsed or Refractory Multiple Myeloma Treated with Anti-BCMA CAR T-cell Therapy

PURPOSE

B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T-cell therapy results in high remission rates in patients with relapsed/refractory (R/R) multiple myeloma. However, the factors associated with prognosis following CAR T-cell therapy are unknown.

PATIENTS AND METHODS

Between July 1, 2018 and July 31, 2020, 61 patients with R/R multiple myeloma received anti-BCMA CAR T-cell therapy (Chictr.org number, ChiCTR1800017404). Step-wise multivariate Cox regression and competing risk analyses were conducted to identify poor prognosis-associated risk factors.

RESULTS

Sixty patients (98.4%) experienced cytokine release syndrome (CRS), including 33, 23, and 4 cases of CRS grades 1 to 2, 3, and 4, respectively. The objective response rate (ORR) was 98.3%, and the complete remission (CR) rate was 70.3%. With a median follow-up period of 21.1 months, the 1-year overall survival (OS) and progression-free survival (PFS) rates were 78.0% and 50.2%, respectively. The median PFS was 12.7 months. Cox modeling revealed that poor PFS was associated with extramedullary disease [HR = 2.59, 95% confidence interval (95% CI) = 1.29-5.21, P = 0.008], light chain multiple myeloma (HR = 2.53, 95% CI = 1.03-5.97, P = 0.035), high-risk cytogenetics (HR = 2.80, 95% CI = 1.27-6.14, P = 0.01), and prior treatment with more than 3 therapeutic lines (HR = 3.14, 95% CI = 1.34-7.34, P = 0.008). Among the 41 CR cases, competing risk analyses demonstrated higher relapse predispositions in those with extramedullary disease (HR = 4.51, 95% CI = 1.86-10.9, P = 0.001), light chain multiple myeloma (HR = 4.89, 95% CI = 1.52 - 15.7, P = 0.008), or high-risk cytogenetics (HR = 5.09, 95% CI = 1.63-15.9, P = 0.005).

CONCLUSIONS

Anti-BCMA CAR T-cell therapy is safe and effective for R/R multiple myeloma. For patients with high-risk factors, improvements to extend remission and more specific individualized therapies are needed.

Keeping up with the stress of antibody production: BAFF and APRIL maintain memory plasma cells

Memory plasma cells, also called long-lived plasma cells, provide 'humoral immunity' by continued secretion of protective antibodies against pathogens, which the immune system has once encountered. They are maintained mainly in the bone marrow, docking on to stromal cells individually. In those niches they can apparently persist for decades (Chang et al., 2018 [1]). Integrin-mediated contact to the stromal cell provides an essential survival signal to the plasma cell, activating the PI3K signalling pathway, downregulating FoxO1/3a and repressing the activation of caspases 3 and 7. In a redundant form, the cytokines BAFF and APRIL, ligands of the plasma cell receptors TACI and BCMA, provide a second essential survival signal, preventing activation of caspase 12, as triggered by endoplasmic reticulum stress.

CNS Autoimmune Responses in BCMA-Deficient Mice Provide Insight for the Failure of Atacicept in MS

OBJECTIVE

B cells have emerged as a therapeutic target for MS. Anti-CD20 antibodies, which deplete B cells, are effective therapies for MS. However, atacicept (TACI-Fc), which blocks BAFF and APRIL and reduces B cells, unexpectedly exacerbates MS. We tested the hypothesis that B cell maturation antigen (BCMA), a receptor for BAFF and APRIL, plays a role in the paradoxical effects of anti-CD20 antibody and TACI-Fc using experimental autoimmune encephalomyelitis (EAE).

METHODS

EAE was induced in wild-type (BCMA^+/+) and BCMA-deficient (BCMA^-/-) mice with an immunization of rodent myelin oligodendrocyte glycoprotein (MOG)_35-55 peptide. Treatment with anti-CD20 antibody, TACI-Fc, and isotype controls was administered by intraperitoneal injections. CNS infiltration was evaluated by histology; immune cell phenotypes were evaluated by flow cytometry; MOG-specific antibodies were determined by ELISA. Mixed bone marrow chimeras and cell culture assays were used to identify the specific subsets of immune cells affected by BCMA deficiency.

RESULTS

First, we found that BCMA^-/- mice had more severe EAE compared with BCMA^+/+ mice and the increased disease was associated with elevated anti-MOG B-cell responses. Second, we found that anti-CD20 therapy attenuated EAE in BCMA^-/- mice but not in BCMA^+/+ mice. Third, TACI-Fc attenuated EAE in BCMA^+/+ mice but not in BCMA^-/- mice. Mixed bone marrow chimeric and cell culture experiments demonstrated that BCMA deficiency elevates inflammatory B-cell responses but inhibits inflammatory responses in macrophages.

CONCLUSIONS

BCMA has multifaceted roles during inflammation that affects therapeutic efficacies of anti-CD20 and TACI-Fc in EAE. Our results from BCMA-deficient mice provide insights into the failure of atacicept in MS.

Paving the Way toward Successful Multiple Myeloma Treatment: Chimeric Antigen Receptor T-Cell Therapy

Despite the significant progress of modern anticancer therapies, multiple myeloma (MM) is still incurable for the majority of patients. Following almost three decades of development, chimeric antigen receptor (CAR) T-cell therapy now has the opportunity to revolutionize the treatment landscape and meet the unmet clinical need. However, there are still several major hurdles to overcome. Here we discuss the recent advances of CAR T-cell therapy for MM with an emphasis on future directions and possible risks. Currently, CAR T-cell therapy for MM is at the first stage of clinical studies, and most studies have focused on CAR T cells targeting B cell maturation antigen (BCMA), but other antigens such as cluster of differentiation 138 (CD138, syndecan-1) are also being evaluated. Although this therapy is associated with side effects, such as cytokine release syndrome and neurotoxicity, and relapses have been observed, the benefit–risk balance and huge potential drive the ongoing clinical progress. To fulfill the promise of recent clinical trial success and maximize the potential of CAR T, future efforts should focus on the reduction of side effects, novel targeted antigens, combinatorial uses of different types of CAR T, and development of CAR T cells targeting more than one antigen.

Role of microRNAs in the Development of Cardiovascular Disease in Systemic Autoimmune Disorders

Rheumatoid Arthritis (RA), Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are the systemic autoimmune diseases (SADs) most associated with an increased risk of developing cardiovascular (CV) events. Cardiovascular disease (CVD) in SADs results from a complex interaction between traditional CV-risk factors, immune deregulation and disease activity. Oxidative stress, dyslipidemia, endothelial dysfunction, inflammatory/prothrombotic mediators (cytokines/chemokines, adipokines, proteases, adhesion-receptors, NETosis-derived-products, and intracellular-signaling molecules) have been implicated in these vascular pathologies. Genetic and genomic analyses further allowed the identification of signatures explaining the pro-atherothrombotic profiles in RA, SLE and APS. However, gene modulation has left significant gaps in our understanding of CV co-morbidities in SADs. MicroRNAs (miRNAs) are emerging as key post-transcriptional regulators of a suite of signaling pathways and pathophysiological effects. Abnormalities in high number of miRNA and their associated functions have been described in several SADs, suggesting their involvement in the development of atherosclerosis and thrombosis in the setting of RA, SLE and APS. This review focusses on recent insights into the potential role of miRNAs both, as clinical biomarkers of atherosclerosis and thrombosis in SADs, and as therapeutic targets in the regulation of the most influential processes that govern those disorders, highlighting the potential diagnostic and therapeutic properties of miRNAs in the management of CVD.

Cancer biomarkers for targeted therapy

Tumor-associated antigens (TAA) or cancer biomarkers are major targets for cancer therapies. Antibody- based agents targeting the cancer biomarkers include monoclonal antibodies (MoAbs), radiolabeled MoAbs, bispecific T cell engagers, and antibody-drug conjugates. Antibodies targeting CD19, CD20, CD22, CD30, CD33, CD38, CD79B and SLAMF7 are in clinical applications for hematological malignancies. CD123, CLL-1, B cell maturation antigen, and CD138 are targets for cancer immunotherapeutic agents, including the chimeric antigen receptor - engineered T cells. Immune checkpoint inhibitors (ICIs) against PD-1, PD-L1, and CTLA-4 have led to the revolution of cancer immunotherapy. More ICIs targeting IDO, LAG3, TIM-3, TIGIT, SIGLECs, VISTA and CD47 are being explored. Small molecule inhibitors (SMIs) against tyrosine kinase oncoproteins such as BCR-ABL, JAK2, Bruton tyrosine kinase, FLT3, EGFR, ALK, HER2, VEGFR, FGFR, MEK, and MET have fundamentally changed the landscape of cancer therapy. SMIs against BCL-2, IDHs, BRAF, PI3 kinase, mTOR, PARP, and CDKs have become the mainstay in the treatment of a variety of cancer types. To reduce and avoid off-tumor toxicities, cancer-specific TAAs such as CD33 are being manufactured through systems biology approach. Search for novel biomarkers and new designs as well as delivery methods of targeted agents are fueling the next wave of advances in cancer therapy.

Recent updates on CAR T clinical trials for multiple myeloma

Proteasome inhibitors, immunomodulatory agents and monoclonal antibodies have dramatically changed the natural history of multiple myeloma (MM). However, most patients eventually suffer a relapse and succumb to the disease. Chimeric antigen receptor (CAR) engineered T cells targeting B cell maturation antigen (BCMA), CD138, CS1 glycoprotein antigen (SLAMF7) and light chains are in active development for therapy of refractory /relapsed (RR) MM. CD19- targeted CAR T cells in conjunction with autologous stem cell transplantation also showed activity in RRMM. Dual- target CAR T cells are in clinical trials for RRMM. This review summarized the recent updates of ongoing CAR T clinical trials for multiple myeloma.

Ancient BCMA-like Genes Herald B Cell Regulation in Lampreys

The TNF superfamily ligands BAFF and APRIL interact with three receptors, BAFFR, BCMA, and TACI, to play discrete and crucial roles in regulating B cell selection and homeostasis in mammals. The interactions between these ligands and receptors are both specific and redundant: BAFFR binds BAFF, whereas BCMA and TACI bind to either BAFF or APRIL. In a previous phylogenetic inquiry, we identified and characterized a BAFF-like gene in lampreys, which, with hagfish, are the only extant jawless vertebrates, both of which have B-like and T-like lymphocytes. To gain insight into lymphocyte regulation in jawless vertebrates, in this study we identified two BCMA-like genes in lampreys, BCMAL1 and BCMAL2, which were found to be preferentially expressed by B-like lymphocytes. In vitro analyses indicated that the lamprey BAFF-like protein can bind to a BCMA-like receptor Ig fusion protein and to both BCMAL1- and BCMAL2-transfected cells. Discriminating regulatory roles for the two BCMA-like molecules are suggested by their differential expression before and after activation of the B-like lymphocytes in lampreys. Our composite results imply that BAFF-based mechanisms for B cell regulation evolved before the divergence of jawed and jawless vertebrates.

The Role of B-Cell Maturation Antigen in the Biology and Management of, and as a Potential Therapeutic Target in, Multiple Myeloma

B-cell maturation antigen (BCMA) was originally identified as a cell membrane receptor, expressed exclusively on late stage B-cells and plasma cells (PCs). Investigations of BCMA as a target for therapeutic intervention in multiple myeloma (MM) were initiated in 2007, using cSG1 as a naked antibody (Ab) as well as an Ab-drug conjugate (ADC) targeting BCMA, ultimately leading to ongoing clinical studies for previously treated MM patients. Since then, multiple companies have developed anti-BCMA-directed ADCs. Additionally, there are now three bispecific antibodies in development, which bind to both BCMA and CD3ε on T-cells. This latter binding results in T-cell recruitment and activation, causing target cell lysis. More recently, T-cells have been genetically engineered to recognize BCMA-expressing cells and, in 2013, the first report of anti-BCMA-chimeric antigen receptor T-cells showed that these killed MM cell lines and human MM xenografts in mice. BCMA is also solubilized in the blood (soluble BCMA [sBCMA]) and MM patients with progressive disease have significantly higher sBCMA levels than those responding to treatment. sBCMA circulating in the blood may limit the efficacy of these anti-BCMA-directed therapies. When sBCMA binds to B-cell activating factor (BAFF), BAFF is unable to perform its major biological function of inducing B-cell proliferation and differentiation into Ab-secreting PC. However, the use of γ-secretase inhibitors, which prevent shedding of BCMA from PCs, may improve the efficacy of these BCMA-directed therapies.

Molecular structure, expression, and bioactivity of B-cell-activating factor of the TNF family (BAFF) and its receptor BAFF-R in cats (Felis catus)

B-cell survival depends on signals induced by binding of B-cell activating factor (BAFF) to its receptor (BAFF-R). In this study, the full-length cDNAs of cat BAFF (cBAFF) and BAFF-R (cBAFF-R) were amplified from the spleen by reverse transcription PCR. The open reading frame of cBAFF cDNA encodes a protein of 285 amino acids containing a predicted transmembrane domain and a furin protease cleavage site, similar to mammalian, avian, and reptile BAFFs. The cBAFF-R gene encodes a 189 amino acid protein. Real-time quantitative PCR analyses revealed that the two genes are predominantly expressed in the spleen. csBAFF, EGFP/csBAFF, and cBAFF-R were efficiently expressed in Escherichia coli BL21 (DE3), as confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting analyses. After purification, the EGFP/csBAFF fusion protein showed a fluorescence spectrum similar to that of EGFP. Confocal laser scanning microscopy showed that EGFP/csBAFF bound to its receptor. In vitro, csBAFF promoted the survival of cat and mouse splenic B cells with/without a priming agent (Staphylococcus aureus Cowan 1, SAC) or anti-mouse IgM. Furthermore, it stimulated the survival of mouse B cells, similar to msBAFF. Recombinant cBAFF-R blocked the function of sBAFF in vitro. These findings indicate that csBAFF plays an important role in the survival of cat B cells and has functional cross reactivity between cats and other mammals, and suggest a role for the BAFF-BAFF-R system in regulating B-cell survival. Therefore, BAFF and BAFF-R show promise for enhancing the immune systems of animals.

Anti-BCMA antibodies in the future management of multiple myeloma

INTRODUCTION

B-cell maturation antigen (BCMA) belongs to the tumor necrosis factor receptor family and is expressed on late B-cells and plasma cells. Serum BCMA is elevated in patients with multiple myeloma (MM) and chronic lymphocytic leukemia (CLL), and might represent a novel prognostic and monitoring tool. Serum BCMA levels can predict both progression free survival (PFS) and overall survival (OS). Several therapeutic strategies are currently under investigation including BCMA-directed monoclonal Abs (either naked or with drug conjugates, and bispecific Abs) and cellular T-cell therapies (chimeric antigen receptor T-cells) with impressive clinical results. Areas covered: This review aims to present the mechanisms of action and the available data on efficacy and safety of therapies targeting BCMA. Expert opinion: The preliminary preclinical and clinical results from the phase 1 and 2 studies have demonstrated significant activity of the anti-BCMA therapeutic strategies. The main toxicities induced include Cytokine Release Syndrome (CRS) and ocular toxicity. The management of these adverse events remains currently an issue of controversy.

TRAF3 as a Multifaceted Regulator of B Lymphocyte Survival and Activation

The adaptor protein TNF receptor-associated factor 3 (TRAF3) serves as a powerful negative regulator in multiple aspects of B cell biology. Early in vitro studies in transformed cell lines suggested the potential of TRAF3 to inhibit signaling by its first identified binding receptor, CD40. However, because the canonical TRAF3 binding site on many receptors also mediates binding of other TRAFs, and whole-mouse TRAF3 deficiency is neonatally lethal, an accurate understanding of TRAF3's specific functions was delayed until conditional TRAF3-deficient mice were produced. Studies of B cell-specific TRAF3-deficient mice, complemented by investigations in normal and malignant mouse and human B cells, reveal that TRAF3 has powerful regulatory roles that are unique to this TRAF, as well as functions context-specific to the B cell. This review summarizes the current state of knowledge of these roles and functions. These include inhibition of signaling by plasma membrane receptors, negative regulation of intracellular receptors, and restraint of cytoplasmic NF- κB pathways. TRAF3 is also now known to function as a resident nuclear protein, and to impact B cell metabolism. Through these and additional mechanisms TRAF3 exerts powerful restraint upon B cell survival and activation. It is thus perhaps not surprising that TRAF3 has been revealed as an important tumor suppressor in B cells. The many and varied functions of TRAF3 in B cells, and new directions to pursue in future studies, are summarized and discussed here.

B-Cell-Activating Factor and the B-Cell Compartment in HIV/SIV Infection

With the goal to design effective HIV vaccines, intensive studies focused on broadly neutralizing antibodies, which arise in a fraction of HIV-infected people. Apart from identifying new vulnerability sites in the viral envelope proteins, these studies have shown that a fraction of these antibodies are produced by self/poly-reactive B-cells. These findings prompted us to revisit the B-cell differentiation and selection process during HIV/SIV infection and to consider B-cells as active players possibly shaping the helper T-cell program within germinal centers (GCs). In this context, we paid a particular attention to B-cell-activating factor (BAFF), a key cytokine in B-cell development and immune response that is overproduced during HIV/SIV infection. As it does in autoimmune diseases, BAFF excess might contribute to the abnormal rescue of self-reactive B-cells at several checkpoints of the B-cell development and impair memory B-cell generation and functions. In this review, we first point out what is known about the functions of BAFF/a proliferation-inducing ligand and their receptors [B-cell maturation, transmembrane activator and CAML interactor (TACI), and BAFF-R], in physiological and pathophysiological settings, in mice and humans. In particular, we highlight recent results on the previously underappreciated regulatory functions of TACI and on the highly regulated production of soluble TACI and BAFF-R that act as decoy receptors. In light of recent data on BAFF, TACI, and BAFF-R, we then revisit the altered phenotypes and functions of B-cell subsets during the acute and chronic phase of HIV/SIV infection. Given the atypical phenotype and reduced functions of memory B-cells in HIV/SIV infection, we particularly discuss the GC reaction, a key checkpoint where self-reactive B-cells are eliminated and pathogen-specific memory B-cells and plasmablasts/cells are generated in physiological settings. Through its capacity to differentially bind and process BAFF-R and TACI on GC B-cells and possibly on follicular helper T-cells, BAFF appears as a key regulator of the physiological GC reaction. Its local excess during HIV/SIV infection could play a key role in B-cell dysregulations.

A Systems Vaccinology Approach Reveals Temporal Transcriptomic Changes of Immune Responses to the Yellow Fever 17D Vaccine

In this study, we used a systems vaccinology approach to identify temporal changes in immune response signatures to the yellow fever (YF)-17D vaccine, with the aim of comprehensively characterizing immune responses associated with protective immunity. We conducted a cohort study in which 21 healthy subjects in China were administered one dose of the YF-17D vaccine; PBMCs were collected at 0 h and then at 4 h and days 1, 2, 3, 5, 7, 14, 28, 84, and 168 postvaccination, and analyzed by transcriptional profiling and immunological assays. At 4 h postvaccination, genes associated with innate cell differentiation and cytokine pathways were dramatically downregulated, whereas receptor genes were upregulated, compared with their baseline levels at 0 h. Immune response pathways were primarily upregulated on days 5 and 7, accompanied by the upregulation of the transcriptional factors JUP, STAT1, and EIF2AK2. We also observed robust activation of innate immunity within 2 d postvaccination and a durable adaptive response, as assessed by transcriptional profiling. Coexpression network analysis indicated that lysosome activity and lymphocyte proliferation were associated with dendritic cell (DC) and CD4⁺ T cell responses; FGL2, NFAM1, CCR1, and TNFSF13B were involved in these associations. Moreover, individuals who were baseline-seropositive for Abs against another flavivirus exhibited significantly impaired DC, NK cell, and T cell function in response to YF-17D vaccination. Overall, our findings indicate that YF-17D vaccination induces a prompt innate immune response and DC activation, a robust Ag-specific T cell response, and a persistent B cell/memory B cell response.

Repurposing L-Menthol for Systems Medicine and Cancer Therapeutics? L-Menthol Induces Apoptosis through Caspase 10 and by Suppressing HSP90

The objective of the present study was to repurpose L-menthol, which is frequently used in oral health and topical formulations, for cancer therapeutics. In this article, we argue that monoterpenes such as L-menthol might offer veritable potentials in systems medicine, for example, as cheaper anti-cancer compounds. Other monoterpenes such as limonene, perillyl alcohol, and geraniol have been shown to induce apoptosis in various cancer cell lines, but their mechanisms of action are yet to be completely elucidated. Earlier, we showed that L-menthol modulates tubulin polymerization and apoptosis to inhibit cancer cell proliferation. In the present report, we used an apoptosis-related gene microarray in conjunction with proteomics analyses, as well as in silico interpretations, to study gene expression modulation in human adenocarcinoma Caco-2 cell line in response to L-menthol treatment. The microarray analysis identified caspase 10 as the important initiator caspase, instead of caspase 8. The proteomics analyses showed downregulation of HSP90 protein (also corroborated by its low transcript abundance), which in turn indicated inhibition of AKT-mediated survival pathway, release of pro-apoptotic factor BAD from BAD and BCLxL complex, besides regulation of other factors related to apoptosis. Based on the combined microarray, proteomics, and in silico data, a signaling pathway for L-menthol-induced apoptosis is being presented for the first time here. These data and literature analysis have significant implications for "repurposing" L-menthol beyond oral medicine, and in understanding the mode of action of plant-derived monoterpenes towards development of cheaper anticancer drugs in future.

A therapeutic role for BLyS antagonists

B lymphocytestimulator (BLyS) is a vital B cell survivalfactor. Overexpressionof BLyS in mice may lead to systemic lupus erythematosus (SLE)-like disease, and treatment of bona fide SLE mice with BLyS antagonists ameliorates disease progression and enhances survival. BLyS overexpression is common in human SLE, and results from a phase I clinical trial with a BLyS antagonistin human SLE have shown the antagonist to be biologicallyactive and safe. These features collectivelypoint to BLyS as an attractive therapeutic target in human disease.

Molecular structure, distribution, and immunology function of TNFSF13B (BAFF) in Nile tilapia (Oreochromis niloticus)

B cell-activating factor (BAFF)is a member of the tumor necrosis factor (TNF) family and plays roles in B cell survival and maturation. In this study, the full-length cDNA of Nile tilapia (Oreochromis niloticus) BAFF (tBAFF) was amplified from the spleen by reverse transcription PCR (RT-PCR). The open reading frame of this cDNA encodes a protein of 261 amino acids containing a predicted transmembrane domain and a furin protease cleavage site, similar to mammalian, avian, and reptile BAFF. Real-time quantitative PCR (qPCR) analysis revealed that tBAFF is present in various tissues and is predominantly expressed in the spleen. The predicted three-dimensional (3D) structure of the Nile tilapia (Oreochromis niloticus) soluble BAFF (tsBAFF) monomer was determined by (3D) structure modeling monomeranalyzed by (3D) structure mouse counterpart. Both tsBAFF and EGFP/tsBAFF were efficiently expressed in Escherichia coli BL21 (DE3), as confirmed by SDS-PAGE and Western blot analysis. After purification, the EGFP/tsBAFF fusion protein showed a fluorescence spectrum similar to that of EGFP. Laser scanning confocal microscopy showed that EGFP/tsBAFF bound to its receptor. In vitro, tsBAFF promoted the proliferation of Nile tilapia and mouse splenic B cells together with/without a priming agent (Staphylococcus aureus Cowan 1, SAC) or anti-mouse IgM. Furthermore, tsBAFF showed a similar proliferation-stimulating effect on mouse B cells compared to msBAFF. These findings indicate that tsBAFF plays an important role in the proliferation of Nile tilapia B cells and has functional cross-reactivity among Nile tilapia and mammals. Therefore, BAFF may represent a useful factor for enhancing immunological efficacy in animals.

Transcriptomic Profile of Whole Blood Cells from Elderly Subjects Fed Probiotic Bacteria Lactobacillus rhamnosus GG ATCC 53103 (LGG) in a Phase I Open Label Study

We examined gene expression of whole blood cells (WBC) from 11 healthy elderly volunteers participating on a Phase I open label study before and after oral treatment with Lactobacillus rhamnosus GG-ATCC 53103 (LGG)) using RNA-sequencing (RNA-Seq). Elderly patients (65–80 yrs) completed a clinical assessment for health status and had blood drawn for cellular RNA extraction at study admission (Baseline), after 28 days of daily LGG treatment (Day 28) and at the end of the study (Day 56) after LGG treatment had been suspended for 28 days. Treatment compliance was verified by measuring LGG-DNA copy levels detected in host fecal samples. Normalized gene expression levels in WBC RNA were analyzed using a paired design built within three analysis platforms (edgeR, DESeq2 and TSPM) commonly used for gene count data analysis. From the 25,990 transcripts detected, 95 differentially expressed genes (DEGs) were detected in common by all analysis platforms with a nominal significant difference in gene expression at Day 28 following LGG treatment (FDR<0.1; 77 decreased and 18 increased). With a more stringent significance threshold (FDR<0.05), only two genes (FCER2 and LY86), were down-regulated more than 1.5 fold and met the criteria for differential expression across two analysis platforms. The remaining 93 genes were only detected at this threshold level with DESeq2 platform. Data analysis for biological interpretation of DEGs with an absolute fold change of 1.5 revealed down-regulation of overlapping genes involved with Cellular movement, Cell to cell signaling interactions, Immune cell trafficking and Inflammatory response. These data provide evidence for LGG-induced transcriptional modulation in healthy elderly volunteers because pre-treatment transcription levels were restored at 28 days after LGG treatment was stopped. To gain insight into the signaling pathways affected in response to LGG treatment, DEG were mapped using biological pathways and genomic data mining packages to indicate significant biological relevance.

Trial Registration: ClinicalTrials.gov NCT01274598

B-Cell Activating Factor as a Cancer Biomarker and Its Implications in Cancer-Related Cachexia

B-cell activating factor (BAFF) is a cytokine and adipokine of the TNF ligand superfamily. The main biological function of BAFF in maintaining the maturation of B-cells to plasma cells has recently made it a target of the first FDA-approved selective BAFF antibody, belimumab, for the therapy of systemic lupus erythematosus. Concomitantly, the role of BAFF in cancer has been a subject of research since its discovery. Here we review BAFF as a biomarker of malignant disease activity and prognostic factor in B-cell derived malignancies such as multiple myeloma. Moreover, anti-BAFF therapy seems to be a promising approach in treatment of B-cell derived leukemias/lymphomas. In nonhematologic solid tumors, BAFF may contribute to cancer progression by mechanisms both dependent on and independent of BAFF's proinflammatory role. We also describe ongoing research into the pathophysiological link between BAFF and cancer-related cachexia. BAFF has been shown to contribute to inflammation and insulin resistance which are known to worsen cancer cachexia syndrome. Taking all the above together, BAFF is emerging as a biomarker of several malignancies and a possible hallmark of cancer cachexia.

The role of BAFF in the progression of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease that is marked by a systemic inflammatory reaction and joint erosions. Elevated levels of B cell activating factor (BAFF) have been detected in the serum and synovial fluid of RA patients. Moreover, the levels of BAFF increase in cases of autoimmune disease and are correlated with the level of disease activity. As an innate cytokine mediator, BAFF affects the immune response of the synovial microenvironment. In this review, we consider recent observations of BAFF and its receptors in RA progression, as well as the effects of BAFF on the cell-cell interactions network. We also summarize the clinical development of BAFF antagonists for the treatment of RA.

The effects of Jieduquyuzishen prescription-treated rat serum on the BAFF/BAFF-R signal pathway

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease mainly characterized by B cell hyperactivity. Glucocorticoid (GC) is widely used in SLE for its potent anti-inflammatory and immunosuppressive effects. Despite its important clinical efficacy, high-dose or long-term use of GC can cause severe side effects, such as osteoporosis, osteonecrosis, cataracts, hyperglycemia, coronary heart disease and cognitive impairment. Our early clinical studies have shown that Jieduquyuzishen prescription (JP) can effectively reduce the adverse effects and improve the curative effect of GC in the treatment of SLE. The BAFF/BAFF-R signaling pathway plays an important role in the development of SLE and has been regarded as a potential target for the therapy of SLE. In this study, we attempt to investigate the effect of JP on the BAFF/BAFF-R signaling pathway to explore the mechanism of JP in reducing the toxicity and enhancing the efficacy of GC. YAC-1 cells, isolated rat peripheral blood lymphocytes, polymorphonuclear neutrophils and spleen lymphocytes were treated with drug-containing serum. The results of RT-PCR, Western blot and dual-luciferase reporter gene assays indicate that either JP or GC can inhibit the mBAFF-induced up-regulation of BAFF, BAFF-R, Bcl-2, IL-10 and NF-κB in YAC-1 cells and WEHI-231 cells. Furthermore, MTS, flow cytometry and CFSE results reveal that the proliferation and survival of lymphocytes activated by mBAFF are suppressed by JP, GC and their combination. Contrary to GC, JP can reduce the apoptosis and raise the survival of polymorphonuclear neutrophils and can’t increase the apoptosis of the peripheral blood lymphocytes and spleen lymphocytes. Therefore, it is possible that JP can down-regulate the BAFF/BAFF-R signaling pathway as effectively as GC, which may result in the dosage reduction of GC, thus decreasing the toxicity and improving the efficacy of GC-based treatment of SLE.

Spinal cord injury impacts B cell production, homeostasis, and activation

Complex interactions govern the interplay of central nervous and immune systems, including the generation, homeostatic maintenance, and activation of B cells. Accordingly, spinal cord injury will likely impact all of these processes. Several laboratories have recently explored this possibility, and their observations in aggregate reveal both acute and chronic consequences that can vary based on the injury location. Acute effects include a transient cessation of bone marrow B lymphopoiesis, with a corresponding drop in the peripheral follicular and transitional B cell subsets, whereas the marginal zone subset is preserved. Despite recovery of B lymphopoiesis by 28 days post injury, follicular B cell numbers remain depressed; this may reflect reduced levels of the homeostatic cytokine BLyS. In general, the ability to mount T dependent antibody responses after injury are intact, as are pre-existing memory B cell pools and antibody levels. In contrast, T-independent responses are chronically compromised. Both glucocorticoid-dependent and -independent processes mediate these effects, but a detailed understanding of the mechanisms involved awaits further study. Nonetheless, these observations in toto strengthen the growing appreciation for bidirectional interactions between the CNS and immune system, highlighting the need for further basic and translational efforts.

Regulatory roles of the tumor necrosis factor receptor BCMA

B cell maturation antigen (BCMA) is a tumor necrosis family receptor (TNFR) member that is predominantly expressed on terminally differentiated B cells and, upon binding to its ligands B cell activator of the TNF family (BAFF) and a proliferation inducing ligand (APRIL), delivers pro-survival cell signals. Thus, BCMA is mostly known for its functional activity in mediating the survival of plasma cells that maintain long-term humoral immunity. The expression of BCMA has also been linked to a number of cancers, autoimmune disorders, and infectious diseases that suggest additional roles for BCMA activity. Despite recent advances in our understanding of the roles for the related TNFR members BAFF-R and transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI), the signaling pathway used by BCMA for mediating plasma cell survival as well as its putative function in certain disease states are not well understood. By examining the expression, regulation, and signaling targets of BCMA, we may gain further insight into this receptor and how it operates within cells in both health and disease. This information is important for identifying new therapeutic targets that may be relevant in treating diseases that involve the BAFF/APRIL cytokine network.

Roles for TNF-receptor associated factor 3 (TRAF3) in lymphocyte functions

TRAF3 is an adapter protein that serves and regulates the functions of several types of receptors, located both inside the cell and at the plasma membrane. These include members of the TNF receptor superfamily (TNFR-SF), toll-like receptors (TLR), and cytokine receptors. It has become increasingly evident that the roles and functions of TRAF3 are highly context-dependent. TRAF3 can serve distinct roles for different receptors in the same cell, and also has highly cell-type-dependent functions. This review focuses upon the current state of knowledge regarding how TRAF3 regulates the biology and effector functions of B and T lymphocytes, two major cell types of the adaptive immune response in which TRAF3 has markedly distinct roles.

Increased B cell-activating factor promotes tumor invasion and metastasis in human pancreatic cancer

B cell-activating factor (BAFF) is a cytokine belonging to the tumor necrosis factor (TNF) superfamily. It has been reported that BAFF is elevated in patients with autoimmune pancreatitis and contributes to the malignant potential of blood cancers and solid tumors. In this study, clinical evidence of increased BAFF levels in patients with pancreatic ductal adenocarcinoma (PDAC) was obtained, and the roles and mechanisms of BAFF in PDAC were clarified in human tissues of PDAC and from in vitro data of PDAC cell lines. Serum levels of BAFF in patients with PDAC were significantly higher than in healthy subjects (p = 0.0121). Patients with UICC stage IV PDAC (T1-4, N0-1, M1) had significantly higher levels of serum BAFF compared to patients with PDAC (p = 0.0182). BAFF was remarkably expressed in infiltrating B lymphocytes surrounding pancreatic cancer in human pancreatic tissues, suggesting that BAFF may play a role in progression of pancreatic cancer. PDAC cell lines were cultured with human recombinant BAFF, and morphology and gene expression were analyzed; pancreatic cancer cells changed to a fibroblast-like morphology, and showed altered gene expression of E-cadherin, vimentin and Snail. These BAFF-induced changes reflect enhanced cell motility and invasion. BAFF-R-overexpressing cell clones confirmed the association between these BAFF-induced changes and epithelial-mesenchymal transition (EMT)-related genes. BAFF was elevated in patients with metastatic advanced PDAC and induced alterations in PDAC cells via regulation of EMT-related genes. Elucidation of the precise role and mechanism of control of BAFF may lead to new therapeutic approaches with the aim of improving pancreatic cancer survival.

TRAF molecules in cell signaling and in human diseases

The tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of intracellular proteins were originally identified as signaling adaptors that bind directly to the cytoplasmic regions of receptors of the TNF-R superfamily. The past decade has witnessed rapid expansion of receptor families identified to employ TRAFs for signaling. These include Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), T cell receptor, IL-1 receptor family, IL-17 receptors, IFN receptors and TGFβ receptors. In addition to their role as adaptor proteins, most TRAFs also act as E3 ubiquitin ligases to activate downstream signaling events. TRAF-dependent signaling pathways typically lead to the activation of nuclear factor-κBs (NF-κBs), mitogen-activated protein kinases (MAPKs), or interferon-regulatory factors (IRFs). Compelling evidence obtained from germ-line and cell-specific TRAF-deficient mice demonstrates that each TRAF plays indispensable and non-redundant physiological roles, regulating innate and adaptive immunity, embryonic development, tissue homeostasis, stress response, and bone metabolism. Notably, mounting evidence implicates TRAFs in the pathogenesis of human diseases such as cancers and autoimmune diseases, which has sparked new appreciation and interest in TRAF research. This review presents an overview of the current knowledge of TRAFs, with an emphasis on recent findings concerning TRAF molecules in signaling and in human diseases.

Regulation of PI-3-Kinase and Akt Signaling in T Lymphocytes and Other Cells by TNFR Family Molecules

Activation of phosphoinositide 3-kinase (PI3K) and Akt (protein kinase B) is a common response triggered by a range of membrane-bound receptors on many cell types. In T lymphocytes, the PI3K-Akt pathway promotes clonal expansion, differentiation, and survival of effector cells and suppresses the generation of regulatory T cells. PI3K activation is tightly controlled by signals through the T cell receptor (TCR) and the co-stimulatory receptor CD28, however sustained and periodic signals from additional co-receptors are now being recognized as critical contributors to the activation of this pathway. Accumulating evidence suggests that many members of the Tumor Necrosis Factor receptor (TNFR) superfamily, TNFR2 (TNFRSF1B), OX40 (TNFRSF4), 4-1BB (TNFRSF9), HVEM (TNFRSF14), and DR3 (TNFRSF25), that are constitutive or inducible on T cells, can directly or indirectly promote activity in the PI3K-Akt pathway. We discuss recent data which suggests that ligation of one TNFR family molecule organizes a signalosome, via TNFR-associated factor (TRAF) adapter proteins in T cell membrane lipid microdomains, that results in the subsequent accumulation of highly concentrated depots of PI3K and Akt in close proximity to TCR signaling units. We propose this may be a generalizable mechanism applicable to other TNFR family molecules that will result in a quantitative contribution of these signalosomes to enhancing and sustaining PI3K and Akt activation triggered by the TCR. We also review data that other TNFR molecules, such as CD40 (TNFRSF5), RANK (TNFRSF11A), FN14 (TNFRSF12A), TACI (TNFRSF13B), BAFFR (TNFRSF13C), and NGFR (TNFRSF16), contribute to the activation of this pathway in diverse cell types through a similar ability to recruit PI3K or Akt into their signaling complexes.

Signaling by the tumor necrosis factor receptor superfamily in B-cell biology and disease

Members of the tumor necrosis factor receptor superfamily (TNFRSF) participate prominently in B-cell maturation and function. In particular, B-cell activating factor belonging to the TNF family receptor (BAFF-R), B-cell maturation antigen (BCMA), and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) play critical roles in promoting B-cell survival at distinct stages of development by engaging a proliferation-inducing ligand (APRIL) and/or BAFF. CD40 is also essential for directing the humoral response to T-cell-dependent antigens. Signaling by the TNFRSF is mediated primarily, albeit not exclusively, via the TNFR-associated factor (TRAF) proteins and activation of the canonical and/or non-canonical nuclear factor-κB (NF-κB) pathways. Dysregulated signaling by TNFRSF members can promote B-cell survival and proliferation, causing autoimmunity and neoplasia. In this review, we present a current understanding of the functions of and distinctions between APRIL/BAFF signaling by their respective receptors expressed on particular B-cell subsets. These findings are compared and contrasted with CD40 signaling, which employs similar signaling conduits to achieve distinct cellular outcomes in the context of the germinal center response. We also underscore how new findings and conceptual insights into TNFRSF signaling are facilitating the understanding of B-cell malignancies and autoimmune diseases.

Roles of tumor necrosis factor receptor associated factor 3 (TRAF3) and TRAF5 in immune cell functions

A large and diverse group of receptors utilizes the family of cytoplasmic signaling proteins known as tumor necrosis factor receptor (TNFR)-associated factors (TRAFs). In recent years, there has been a resurgence of interest and exploration of the roles played by TRAF3 and TRAF5 in cellular regulation, particularly in cells of the immune system, the cell types of focus in this review. This work has revealed that TRAF3 and TRAF5 can play diverse roles for different receptors even in the same cell type, as well as distinct roles in different cell types. Evidence indicates that TRAF3 and TRAF5 play important roles beyond the TNFR-superfamily (SF) and viral mimics of its members, mediating certain innate immune receptor and cytokine receptor signals, and most recently, signals delivered by the T-cell receptor (TCR) signaling complex. Additionally, much research has demonstrated the importance of TRAF3-mediated cellular regulation via its cytoplasmic interactions with additional signaling proteins. In particular, we discuss below evidence for the participation by TRAF3 in a number of the regulatory post-translational modifications involving ubiquitin that are important in various signaling pathways.

B-cell maturation antigen (BCMA) activation exerts specific proinflammatory effects in normal human keratinocytes and is preferentially expressed in inflammatory skin pathologies

TNFα is known to be expressed in human skin, regulating immune-related responses. Here we report that human normal skin keratinocytes express the members of the TNF superfamily members A proliferation-inducing ligand (APRIL; TNFSF13), B cell-activating factor (BAFF; TNFSF13B), and their receptors, B cell maturation antigen (BCMA; TNFRSF17) and transmembrane activator, calcium-modulator, and cyclophilin ligand interactor (TACI; TNFRSF13B), in a distinct spatial pattern. Our data show a differential expression of these molecules within epidermal layers and skin appendages, whereas the BAFF-specific receptor BAFFR (TNFRSF13C) is absent. Importantly, APRIL and BCMA but not BAFF or TACI are up-regulated in inflammatory skin lesions of psoriasis and squamous cell carcinomas. To explore the functional significance of this system in the skin, we assayed these receptors and ligands in cultured primary keratinocytes and HaCaT cells. We show that both cell types express BAFF, APRIL, BCMA, and TACI. Furthermore, APRIL and/or BAFF trigger nuclear factor-κB activation and IL-6 and granulocyte macrophage colony-stimulating factor (GM-CSF) expression through functional BCMA receptors, an activation inhibited by anti-BCMA short hairpin RNA. However, BAFF and/or APRIL do not induce IL-8 or TNFα production. Our data advance BCMA as an inflammation-related TNFSFR member in keratinocytes, of potential importance in the management of inflammatory skin conditions.

Beyond transitional selection: New roles for BLyS in peripheral tolerance

B cell targeted therapies have enjoyed recent success in the treatment of systemic autoimmune diseases. Among these, Belimumab, which blocks the B cell survival cytokine BLyS, was recently approved for the treatment of Systemic Lupus Erythematosus. It is therefore important to consider the roles BLyS plays in B cell tolerance. Herein, we review how BLyS contributes to the negative selection of autoreactive B cell clones from the preimmune repertoire as well as its role in regulating both germinal center and extrafollicular peripheral B cell responses. We further examine the complex role of Toll-like receptors (TLRs) in humoral autoimmunity, pointing out potential crosstalk between BLyS and TLR pathways.

Molecular cloning, expression and functional analysis of TNF13b (BAFF) in Japanese sea perch, Lateolabrax japonicus

Members of the tumor necrosis factor (TNF) family play key roles in the regulation of inflammation, immune responses and tissue homeostasis. Here we describe the identification of the Japanese sea perch (Lateolabrax japonicus) homologue of mammalian B cell activating factor of the TNF family (BAFF/BLyS) (designated LjBAFF). The cDNA contains an open reading frame (ORF) of 783 nucleotides that are translated into a predicted 260 amino acid protein. Like most known BAFFs, Japanese sea perch BAFF contains three cysteine residues (Cys(123), Cys(218) and Cys(232)) which are conserved in the aligned BAFF sequences and a furin protease cleavage site (R-K-K-R). Real-time quantitative PCR (qPCR) analysis revealed that LjBAFF could be detected in various tissues and predominantly expressed in lymphoid tissue spleen. The soluble BAFF (LjsBAFF) had been cloned into a pET28a vector to express the recombinant protein. The His-LjsBAFF was efficiently expressed in Escherichia coli BL21 (DE3) and its expression was confirmed by SDS-PAGE and Western blotting analysis. After purification, MTT assays and flow cytometric analysis revealed that LjsBAFF could promote the survival/proliferation of splenic B cells in vitro. Furthermore, bacterially expressed LjsBAFF induced the selective expansion of B cells in the spleen when administered to young mice. Our results suggest that like its mammalian counterparts, LjsBAFF plays an important role in the survival and/or proliferation of B cells.

Regulatory mechanisms for the production of BAFF and IL-6 are impaired in monocytes of patients of primary Sjögren's syndrome

INTRODUCTION

In this study, we investigated possible aberrations of monocytes from patients with primary Sjögren's syndrome (pSS). We focused on B-cell-activating factor of the TNF family (BAFF) and IL-6 because they are both produced by monocytes and are known to be involved in the pathogenesis of pSS.

METHODS

Peripheral monocytes were prepared from both pSS patients and normal individuals. The cells were stimulated in vitro with IFN-γ, and the amounts of IL-6 and soluble BAFF (sBAFF) produced by the cells were quantitated. The effect of sBAFF itself on the production of IL-6 was also studied. To investigate the response of pSS monocytes to these stimuli, the expression levels of the genes encoding BAFF receptors and IL-6-regulating transcription factors were quantitated.

RESULTS

Peripheral pSS monocytes produced significantly higher amounts of sBAFF and IL-6 than normal monocytes did, even in the absence of stimulation. The production of these cytokines was significantly increased upon stimulation with IFN-γ. The elevated production of IL-6 was significantly suppressed by an anti-BAFF antibody. In addition, stimulation of pSS monocytes with sBAFF induced a significant increase in IL-6 production. Moreover, the expression levels of a BAFF receptor and transcription factors regulating IL-6 were significantly elevated in pSS monocytes compared to normal monocytes.

CONCLUSIONS

The results of the present study suggest that the mechanisms underlying the production of sBAFF and IL-6 are impaired in pSS monocytes. Our research implies that this impairment is due to abnormally overexpressed IL-6-regulating transcription factors and a BAFF receptor. These abnormalities may cause the development of pSS.

Cardiovascular risk in systemic autoimmune diseases: epigenetic mechanisms of immune regulatory functions

Autoimmune diseases (AIDs) have been associated with accelerated atherosclerosis (AT) leading to increased cardio- and cerebrovascular disease risk. Traditional risk factors, as well as systemic inflammation mediators, including cytokines, chemokines, proteases, autoantibodies, adhesion receptors, and others, have been implicated in the development of these vascular pathologies. Yet, the characteristics of vasculopathies may significantly differ depending on the underlying disease. In recent years, many new genes and signalling pathways involved in autoimmunity with often overlapping patterns between different disease entities have been further detected. Epigenetics, the control of gene packaging and expression independent of alterations in the DNA sequence, is providing new directions linking genetics and environmental factors. Epigenetic regulatory mechanisms comprise DNA methylation, histone modifications, and microRNA activity, all of which act upon gene and protein expression levels. Recent findings have contributed to our understanding of how epigenetic modifications could influence AID development, not only showing differences between AID patients and healthy controls, but also showing how one disease differs from another and even how the expression of key proteins involved in the development of each disease is regulated.

Accelerated atherosclerosis in systemic lupus erythematosus: role of proinflammatory cytokines and therapeutic approaches

Systemic lupus erythematosus (SLE), a chronic multisystem autoimmune disease with a broad range of clinical manifestations, is associated with accelerated atherosclerosis (AT) and increased risk of cardiovascular complications. Relevant factors directly influencing the development of AT comprise immune complex generation, complement activation, and changes in the production and activity of a complex network of cytokines, including type I and II interferons, B lymphocyte stimulator (BLyS), TNFα, IL-6, IL-17 and migration macrophage inhibitor (MIF). Autoantibodies, also responsible for cytokine expression and activation, play a supplementary key role in the development of AT. Genomic and proteomic studies have contributed to the discovery of genes and proteins involved in AT, including some that may be suitable to be used as biomarkers. All that data has allowed the development of new drugs, most of them evaluated in clinical trials: inhibitors of IFN and TNFα, B cell directed therapies, synthetic oligodeoxynucleotides, intravenous immunoglobulin, or statins. The focus of the present paper is to summarize recent evidence showing the role of cytokines in the development of AT in SLE and the rationale, and safety concerns, in the use of combined therapy to prevent AT and cardiovascular disease.

Identification and functional characterization of a human sTRAIL homolog, CasTRAIL, in an invertebrate oyster Crassostrea ariakensis

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) is one of the tumor necrosis factor (TNF) superfamily members, participating in many biological processes including apoptosis and immune responses. In present study, a novel human soluble TRAIL (sTRAIL) homolog, CasTRAIL was identified from the oyster, Crassostrea ariakensis. CasTRAIL has a 99% and 98% similarity to human sTRAIL over the cDNA sequence and the amino acid sequence, respectively. It mostly distributes in tissues of the oyster defense system and was mainly localized at cell membrane, and has no cytotoxicity to normal hemocytes of oyster. The phosphorylation state of MAP kinases revealed that CasTRAIL induced a rapid increase in the phospho-ERK and phospho-p38 levels, which indicated that the MAPK pathway was involved in CasTRAIL-mediated signaling. In addition, CasTRAIL also showed an ability of anti-RLO infection which might be through the p38-MAPK activation pathway. Present studies provide an understanding and insight of the biological functions of CasTRAIL.

Differential effects of BAFF on B cell precursor acute lymphoblastic leukemia and Burkitt lymphoma

B cell-activating factor belonging to the tumor necrosis factor superfamily (BAFF) is a crucial factor for B cell development and is involved in the survival of malignant B cells, but its effect on B cell precursors (BCPs) remains unclear. We investigated BCP acute lymphoblastic leukemia (-ALL) cells for BAFF receptor (-R) expression and compared the effect of BAFF on BCP-ALL cells and Burkitt lymphoma (BL) cells. Expression of BAFF-R was detected in some cell lines and some clinical specimens of both BL and BCP-ALL. BAFF acted on both BL and BCP-ALL cells and promoted proliferation by both. BAFF also inhibited apoptosis by BL cells induced by cross-linking of cell surface molecules and anticancer drugs, but failed to inhibit apoptosis by BCP-ALL cells. BAFF induced prompt and obvious activation of the NF-kappaB signaling pathway in BL cells, but only weak and delayed activation of the pathway in BCP-ALL cells. The results of this study indicate that some BCP-ALL cells and some BL cells express BAFF-R, but that the effects of BAFF on BCP-ALL cells are different from its effects on mature B cell malignancies.

The role of B lymphocyte stimulator (BLyS) in systemic lupus erythematosus

SLE, a chronic, multisystem autoimmune disorder with a broad range of symptoms, involves defective B cell selection and elimination of self-reactive B cells. B lymphocyte stimulator (BLyS), a soluble ligand of the TNF cytokine family, is a prominent factor in B cell differentiation, homeostasis, and selection. BLyS levels affect survival signals and selective apoptosis of autoantibody-producing B cells. High levels of BLyS may relax B cell selection and contribute to autoantibody production, exacerbating the SLE disease state. This review discusses the mechanism of BLyS action on B cells, its role in SLE, and specific targeting of BLyS in the treatment of SLE.

B-cell-activating factor inhibits CD20-mediated and B-cell receptor-mediated apoptosis in human B cells

B-cell-activating factor (BAFF) is a survival and maturation factor for B cells belonging to the tumour necrosis factor superfamily. Among three identified functional receptors, the BAFF receptor (BAFF-R) is thought to be responsible for the effect of BAFF on B cells though details of how remain unclear. We determined that a hairy-cell leukaemia line, MLMA, expressed a relatively high level of BAFF-R and was susceptible to apoptosis mediated by either CD20 or B-cell antigen receptor (BCR). Using MLMA cells as an in vitro model of mature B cells, we found that treatment with BAFF could inhibit apoptosis mediated by both CD20 and BCR. We also observed, using immunoblot analysis and microarray analysis, that BAFF treatment induced activation of nuclear factor-kappaB2 following elevation of the expression level of Bcl-2, which may be involved in the molecular mechanism of BAFF-mediated inhibition of apoptosis. Interestingly, BAFF treatment was also found to induce the expression of a series of genes, such as that for CD40, related to cell survival, suggesting the involvement of a multiple mechanism in the BAFF-mediated anti-apoptotic effect. MLMA cells should provide a model for investigating the molecular basis of the effect of BAFF on B cells in vitro and will help to elucidate how B cells survive in the immune system in which BAFF-mediated signalling is involved.

Lymphoma cell adhesion-induced expression of B cell-activating factor of the TNF family in bone marrow stromal cells protects non-Hodgkin's B lymphoma cells from apoptosis

This study explores whether lymphoma cell adhesion-induced B cell-activating factor (BAFF) expression in bone marrow stromal cells (BMSCs) protects B lymphoma cells from apoptosis. We first showed protection of lymphoma cells from apoptosis by conditioned medium of a stromal cell-lymphoma cell coculture, either spontaneous or induced by mitoxantrone, implying a role for soluble factor(s) in lymphoma cell survival. Addition of BAFF counteracted mitoxantrone-induced apoptosis and elicited a reduction in spontaneous apoptosis in primary lymphomas, suggesting a role of BAFF in sustaining B-cell survival. Abundant BAFF was detected in the BMSC cell line (HS-5) and primary BMSCs by flow cytometry, RT-PCR and immunoblotting. BAFF levels were 20- to 200-fold higher in BMSCs than in lymphoma cells, and lymphoma cell adhesion to BMSCs augmented BAFF secretion twofold through upregulation of BAFF gene expression. Finally, neutralization of BAFF by TACI-Ig or depletion of BAFF by small hairpin RNA (shRNA) in BMSCs significantly enhanced lymphoma cell response to chemotherapy and overcame stroma-mediated drug resistance, suggesting that lymphoma cells use BMSC-derived BAFF as a survival factor. These findings support the hypothesis that lymphoma cells interact with BMSCs, resulting in stromal niches with high BAFF concentration, and identify BMSC-derived BAFF as a functional determinant for B lymphoma cell survival in the bone marrow environment.