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Background Heterozygous C104R or A181E TNF receptor superfamily member 13b (TNFRSF13B) mutations impair removal of autoreactive B cells, weaken B-cell activation, and convey to patients with common variable immune deficiency (CVID) an increased risk for autoimmunity. How mutant transmembrane activator and CAML interactor (TACI) influences wild-type TACI function is unclear; different models suggest either a dominant negative effect or haploinsufficiency. Objective We investigated potential TACI haploinsufficiency by analyzing patients with antibody-deficient Smith-Magenis syndrome (SMS) who possess only 1 TNFRSF13B allele and antibody-deficient patients carrying one c.204insA TNFRSF13B null mutation. Methods We tested the reactivity of antibodies isolated from single B cells from patients with SMS and patients with a c.204insA TNFRSF13B mutation and compared them with counterparts from patients with CVID with heterozygous C104R or A181E TNFRSF13B missense mutations. We also assessed whether loss of a TNFRSF13B allele induced haploinsufficiency in naive and memory B cells and recapitulated abnormal immunologic features typical of patients with CVID with heterozygous TNFRSF13B missense mutations. Results We found that loss of a TNFRSF13B allele does not affect TACI expression, activation responses, or establishment of central B-cell tolerance in naive B cells. Additionally, patients with SMS and those with a c.204insA TNFRSF13B mutation display normal regulatory T-cell function and peripheral B-cell tolerance. The lack of a TNFRSF13B allele did result in decreased TACI expression on memory B cells, resulting in impaired activation and antibody secretion. Conclusion TNFRSF13B hemizygosity does not recapitulate autoimmune features of CVID-associated C104R and A181E TNFRSF13B mutations, which likely encode dominant negative products, but instead reveals selective TACI haploinsufficiency at later stages of B-cell development.

The objective of this study was to determine the expression and effects of B-lymphocyte stimulator (BLyS) in T cell-mediated autoimmune arthritis, a rat model of human rheumatoid arthritis (RA). Rat adjuvant-induced arthritis (AA) was induced by intradermal injection of 0.1ml complete Freund's adjuvant. Arthritis was evaluated by the histopathological examination of joint ankle. The BLyS expression was detected by immunohistochemical analysis. The level of BLyS and interleukin (IL)-17 were assayed by enzyme-linked immunosorbent assay. The gene expression of BLyS and its receptors (TACI, BCMA and BAFF-R) were assessed by quantitative reverse-transcription polymerase chain reaction. The effect of BLyS on the function of T cell was investigated by transwell assay. Using an AA rat model, we detected dysregulated expression and level of BLyS and its receptors in the local joint synovium tissue, peripheral lymphoid organs (spleen) and immune cells (macrophage, dendritic cells (DC) and T cell) at the peak of inflammation. In vitro, BLyS-treated DC induced IL-17 producing T cells. Neutralization of BLyS by the TACI-Ig fusion protein attenuated these stimulating effects of BLyS. These data suggest that the overproduction of BLyS may contribute to T cell responses and may be an attractive target for control of autoimmune diseases, such as RA, that involves both T and B cells.

Introduction Anti-Jo-1 and anti-Ro52 autoantibodies are common in patients with myositis, but the mechanisms behind their production are not known. Survival of autoantibody-producing cells is dependent on B-cell-activating factor of the tumour necrosis factor family (BAFF). BAFF levels are elevated in serum of anti-Jo-1-positive myositis patients and are influenced by type-I interferon (IFN). IFN-producing cells and BAFF mRNA expression are present in myositis muscle. We investigated expression of the receptors for BAFF in muscle tissue in relation to anti-Jo-1 and anti-Ro52/anti-Ro60 autoantibodies and type-I IFN markers. Methods Muscle biopsies from 23 patients with myositis selected based on autoantibody profile and 7 healthy controls were investigated for expression of BAFF receptor (BAFF-R), B-cell maturation antigen (BCMA) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI). Nineteen samples were assessed for plasma (CD138) and B-cell (CD19) markers. The numbers of positive cells per area were compared with the expression of plasmacytoid dendritic cell (pDC) marker blood dendritic cell antigen-2 (BDCA-2) and IFNα/β-inducible myxovirus resistance-1 protein (MX-1). Results BAFF-R, BCMA and TACI were expressed in five, seven and seven patients, respectively, and more frequently in anti-Jo-1-positive and/or anti-Ro52/anti-Ro60-positive patients compared to controls and to patients without these autoantibodies (P = BAFF-R: 0.007, BCMA: 0.03 and TACI: 0.07). A local association of receptors with B and plasma cells was confirmed by confocal microscopy. The numbers of CD138-positive and BCMA-positive cells were correlated (r = 0.79; P = 0.001). Expression of BDCA-2 correlated with numbers of CD138-positive cells and marginally with BCMA-positive cells (r = 0.54 and 0.42, respectively; P = 0.04 and 0.06, respectively). There was a borderline correlation between the numbers of positively stained TACI cells and MX-1 areas (r = 0.38, P = 0.08). Conclusions The expression pattern of receptors for BAFF on B and plasma cells in muscle suggests a local role for BAFF in autoantibody production in muscle tissues of patients with myositis who have anti-Jo-1 or anti-Ro52/anti-Ro60 autoantibodies. BAFF production could be influenced by type-I IFN produced by pDCs. Thus, B-cell-related molecular pathways may participate in the pathogenesis of myositis in this subset of patients. Electronic supplementary material The online version of this article (doi:10.1186/s13075-014-0454-8) contains supplementary material, which is available to authorized users.

Fibroblast-like synoviocyte (FLS) is the ultimate effectual cells in the pathogenesis of rheumatoid arthritis (RA). The current study was undertaken to investigate whether a proliferation-inducing ligand (APRIL) mediates the function of FLS in an animal model of RA. Rat adjuvant-induced arthritis (AA) was induced by intradermal injection of 0.1 ml complete Freund's adjuvant. Synovium APRIL expression was detected by immunohistochemical analysis. The level of APRIL and matrix metalloproteinase (MMP)-9 were assayed by enzyme-linked immunosorbent assay. The expression of APRIL and its receptors (TACI, BCMA and BAFF-R) were assessed by immunofluorescence staining, flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR. The effects of APRIL on the function of FLS were investigated by MTT, Quantibody Rat Inflammation Array 1 and transwell assays, respectively. A higher concentration of APRIL was detected in AA synovium homogenate compared with normal group. AA FLS expressed APRIL, TACI, BAFF-R and BCMA at the mRNA levels, whereas only APRIL and BCMA were confirmed to be expressed on membrane by flow cytometry. APRIL stimulated AA FLS proliferation, migration and invasion and the secretion of proinflammatory factors. In addition, FLS cocultured with APRIL-treated B cells or T cells had a significantly greater proliferation than FLS cultured alone. Neutralization of APRIL by the TACI-Ig fusion protein attenuated these stimulating effects of APRIL on FLS. Our data indicate that APRIL may act as an important mediator for facilitating the function of FLS. Blockade of APRIL thus may be a valuable adjunct in the treatment of RA.

To determine the development of systemic lupus erythematosus (SLE) in NZM 2328 (NZM) mice deficient in 2 BAFF receptors.NZM.BR-3(-/-) .BCMA(-/-) , NZM.BR-3(-/-) .TACI(-/-) , and NZM.BCMA(-/-) .TACI(-/-) mice were evaluated on the clinical, pathologic, serologic, and cellular levels. BAFF receptor expression and lymphocyte phenotype were assessed by flow cytometry, IgG-secreting cells by enzyme-linked immunospot assay, B cell responsiveness to BAFF and generation of Treg cells by in vitro culture, serum BAFF and total IgG and IgG autoantibody levels by enzyme-linked immunosorbent assay, renal immunopathology by immunofluorescence and histologic analyses, and clinical disease by assessment of proteinuria and mortality.Renal immunopathology and clinical disease were attenuated in NZM.BR-3(-/-) .BCMA(-/-) and NZM.BR-3(-/-) .TACI(-/-) mice but were accelerated in NZM.BCMA(-/-) .TACI(-/-) mice. Accelerated disease was associated with increases in B cells, IgG-secreting cells, serum autoantibody levels, and T cells (especially CD4+ activated memory cells), whereas attenuated disease was associated with reductions in many of these parameters. Serum BAFF levels were increased in all double-deficient NZM mice. Exogenous BAFF promoted the in vitro survival of B cells from NZM.BCMA(-/-) .TACI(-/-) or NZM wild-type mice but not those from NZM.BR-3(-/-) .BCMA(-/-) or NZM.BR-3(-/-) .TACI(-/-) mice. In vitro generation of Treg cells was reduced in NZM.BCMA(-/-) .TACI(-/-) mice, but not in NZM.BR-3(-/-) .BCMA(-/-) or NZM.BR-3(-/-) .TACI(-/-) mice.Elimination of B lymphocyte stimulator receptor 3 (BR-3) and TACI or BR-3 and BCMA inhibits the development of SLE in NZM mice. Selective targeting of BR-3 plus TACI or BR-3 plus BCMA may be an efficacious therapeutic approach in human SLE.

Dendritic cells (DCs) play a critical role in immune homeostasis by regulating the functions of various immune cells, including T and B cells. Notably, DCs also undergo education on reciprocal signalling by these immune cells and environmental factors. Various reports demonstrated that B cells have profound regulatory functions, although only few reports have explored the regulation of human DCs by B cells. Here we demonstrate that activated but not resting B cells induce maturation of DCs with distinct features to polarize Th2 cells that secrete interleukin (IL)-5, IL-4 and IL-13. B-cell-induced maturation of DCs is contact dependent and implicates signalling of B-cell activation molecules CD69, B-cell-activating factor receptor, and transmembrane activator and calcium-modulating cyclophilin ligand interactor. Mechanistically, differentiation of Th2 cells by B-cell-matured DCs is dependent on OX-40 ligand. Collectively, our results suggest that B cells have the ability to control their own effector functions by enhancing the ability of human DCs to mediate Th2 differentiation.

Systemic lupus erythematosus is an autoimmune disease associated with an aberrant production of autoantibodies by self-reactive B lymphocytes. The study of the phenotypic characteristics of B lymphocytes and the identification of their surface receptors such as BAFF-R, TACI and BCMA, which are responsible of their survival and maturation, have contributed to the development of new therapeutic strategies in recent years.

Background Lymphoma is a malignant tumor of the immune system originating from lymph nodes and extralymphatic tissues. Its occurrence is believed to be associated with various immune cells due to the proliferation and differentiation of lymphocytes during the immune response. It has been found in many studies that B-cell activating factor (BAFF), as a member of the tumor necrosis factor (TNF) superfamily, could specifically activate B lymphocytes and promote their proliferation. Objectives To explore correlations between non-Hodgkin lymphoma (NHL) and the expression of BAFF and its receptors in NHL patients. Material and methods The protein expression of BAFF and its receptors in serum and BAFF mRNA expression in peripheral blood mononuclear cells (PBMCs) of 47 NHL patients and 20 healthy subjects were detected by ELISA and RFQ-PCR and compared with LDH and β2M levels. Results BAFF mRNA expression in the PBMCs of NHL patients was significantly higher than in healthy controls. The expression levels of serum BAFF and the three receptors (TACI, BCMA and BAFF-R) in NHL patients were significantly higher than in healthy controls, and were not significantly correlated with β2M and LDH levels. Conclusions The serum protein concentration of BAFF and the expression level of BAFF mRNA in PBMCs of NHL patients underwent abnormal changes, indicating that BAFF and its receptors may play some role in the pathogenesis of NHL.

Immune response to T cell independent type 2 (TI-2) Ags, such as bacterial polysaccharides, is severely impaired in X-linked immunodeficient (XID) mice. In this study, we investigated the involvement of a proliferation-inducing ligand (APRIL) or BAFF and their receptors in the unresponsiveness of XID mouse to TI-2 Ags. We discovered that whereas serum BAFF levels were increased, the expression of the APRIL and BAFF receptor transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) was severely reduced in XID B cells. Moreover, B cells from XID mouse were unable to secrete Igs in response to APRIL or BAFF. In correlation with reduced TACI expression and impaired TACI function, APRIL or BAFF did not activate the classical NF-κB pathway in XID cells. Also correlating with the unaltered expression of BAFF receptor, BAFF stimulation induced the activation of the alternative NF-κB pathway in XID cells. Moreover, activation of MAPK pathway was ablated in APRIL-stimulated XID cells. Prestimulation of XID B cells with the TLR9 agonist, CpG led to a significant increase in TACI expression and restored TACI-mediated functions. CpG prestimulation also restored TACI-mediated signaling in APRIL- or BAFF-stimulated XID B cells. Finally, immunization of XID mouse with the prototype TI-2 Ag NP-Ficoll induced IgG and IgM Abs when CpG was given with NP-Ficoll. Collectively, these results suggest that reduced TACI expression is responsible for the unresponsiveness of XID mouse to TI-2 Ags and BCR activation controls TACI expression.

Although decreased intestinal IgA expression has been reported in dogs with inflammatory bowel disease (IBD), the mechanism underlying this decrease is unknown. Transmembrane activator and calcium-modulating cyclophilin-ligand interactor (TACI) and B cell-activating factor of the TNF family (BAFF) receptor (BAFF-R) are key receptors for T cell-independent IgA class switching by the binding of IgA-inducing cytokine a proliferation-inducing ligand (APRIL) and BAFF. Here we show decreased TACI and BAFF-R mRNA expression and hypermethylation of their corresponding genes TNFRSF13B and TNFRSF13C, respectively in the duodenal mucosa of dogs with IBD. To examine whether DNA methylation of the TNFRSF13B and TNFRSF13C influences the mRNA expression of TACI and BAFF-R, respectively, we first analyzed methylation and mRNA expression levels in vitro using 2 canine B lymphoid cell lines, GL-1 and CLBL-1. Methylation profiles in the cells were examined by bisulfite sequencing and methylation-specific PCR (MSP) with primer pairs specific to methylated or unmethylated sequences. These methylation analyses revealed hypermethylation of the CpG islands of both TNFRSF13B and TNFRSF13C in GL-1, but not in CLBL-1 cells. The mRNA expression levels of TACI and BAFF-R were significantly lower in GL-1 than in CLBL-1 cells. Treatment with 5-aza-2'-deoxycytidine significantly increased TACI and BAFF-R mRNA expression in GL-1 cells through demethylation of TNFRSF13B and TNFRSF13C, respectively. These results suggest that the mRNA expression of TACI and BAFF-R is regulated through methylation of their genes in canine B cells. Quantitative real-time MSP showed significant hypermethylation of the CpG islands of TNFRSF13B and TNFRSF13C in the duodenal mucosa of dogs with IBD. Furthermore, duodenal mRNA expression levels of TACI and BAFF-R were significantly lower in dogs with IBD than in healthy controls. The mRNA expression levels of TACI positively correlated with intestinal IgA expression, whereas the methylation level of its gene (TNFRSF13B) negatively correlated with IgA expression. The present results suggest the role of TACI in the regulation of mucosal IgA expression through epigenetic modifications.

BLyS (B lymphocyte stimulator) family cytokines and receptors play key roles in B-2 cell maturation and survival, but their importance for B-1 cells remains less clear. Here we use knockout mice to show that APRIL (A proliferation-inducing ligand), but not BLyS, plays a role in peritoneal B-1 cell maintenance. APRIL likely exerts its effects on peritoneal B-1 cells through binding to HSPG (heparan sulfate proteoglycans) rather than to the TACI (transmembrane activator and cyclophilin ligand interactor) receptor. Finally, we show that peritoneal macrophages express high levels of APRIL message, and are a likely local source of the cytokine in this anatomic locale.

Current HIV-1 vaccines based on the HIV-1 envelope glycoprotein spike (Env), the only relevant target for broadly neutralizing antibodies, are unable to induce protective immunity. Env immunogenicity can be enhanced by fusion to costimulatory molecules involved in B cell activation, such as APRIL and CD40L. Here, we found that Env-APRIL signaled through the two receptors, BCMA and TACI. In rabbits, Env-APRIL induced significantly higher antibody responses against Env compared to unconjugated Env, while the antibody responses against the APRIL component were negligible. To extend this finding, we tested Env-APRIL in mice and found minimal antibody responses against APRIL. Furthermore, Env-CD40L did not induce significant anti-CD40L responses. Thus, in contrast to the 4-helix cytokines IL-21 and GM-CSF, the TNF-superfamily members CD40L and APRIL induced negligible autoantibodies. This study confirms and extends previous work and shows that fusion of Env-based immunogens to APRIL can improve Env immunogenicity and might help in designing HIV vaccines that induce protective humoral immunity.

BLyS is involved in CLL biology and its low soluble serum levels related to a shorter time to first treatment (TFT). TACI is a BLyS receptor and can be shed from cells’ surface and circulate in soluble form (sTACI). We investigated the impact of serum BLyS and sTACI levels at diagnosis in CLL patients and their relationship with disease parameters and patients’ outcome. Serum BLyS was determined in 73 patients, while sTACI in 60. Frozen sera drawn at diagnosis were tested by ELISA. sTACI concentrations correlated with BLyS (P=-0.000021), b2-microglobulin (P=0.005), anemia (P=-0.03), thrombocytopenia (P=0.04), Binet stage (P=0.02), and free light chains ratio (P=0.0003). Soluble BLyS levels below median and sTACI values above median were related to shorter TFT (P=0.0003and 0.007). During a ten-year followup, sTACI levels, but not BLyS, correlated with survival (P=0.048). In conclusion, we confirmed the prognostic significance of soluble BLyS levels with regard to TFT in CLL patients, and, more importantly, we showed for the first time that sTACI is a powerful prognostic marker, related to parameters of disease activity and staging and, more importantly, to TFT and OS.

Background. Tumor necrosis factor-alpha (TNF-α) is an important proinflammatory cytokine which plays an important role in the immunopathogenesis of Behcet’s disease (BD). B cell activating factor (BAFF) and its homolog A proliferation inducing ligand (APRIL) are members of the tumor necrosis factor family. BAFF binds to 3 receptors, B cell activating factor receptor (BAFF-R), transmembrane activator and calcium modulator ligand interactor (TACI), and B cell maturation antigen (BCMA) that are expressed by B cells.Objective. Estimation of the serum levels of TNF-α, APRIL, BAFF, and BCMA in patients with BD in an effort to evaluate their degree of involvement in the pathogenesis and development of BD.Patients and Methods. This study included 30 male patients fulfilling the international study group criteria for the diagnosis of BD. Twenty age-matched healthy male volunteers served as control. Serum samples were used for quantification of TNF-α, APRIL, BCMA, BAFF, and hsCRP using ELISA techniques.Results. The mean serum levels of TNF-α, APRIL, BCMA, and BAFF were more elevated in cases than in controls in a statistically significant manner(P<0.001). Positive correlation was observed between hs-CRP and BDCAF (Behcet’s disease current activity forum) index (r0.68,P<0.001). None of the TNF family members tested was affected by a positive pathergy test.Conclusions. Patients have significantly higher levels of TNF family members’ (TNF-α, BAFF, APRIL, and BCMA) compared to controls which might contribute to the pathogenesis of BD.

BLyS (also called BAFF, TALL-1, THANK, and zTNF4), a TNF superfamily member, binds two receptors, TACI and BCMA, and regulates humoral immune responses [1–7]. These two receptors also bind APRIL [7–10], another TNF superfamily member. The results from TACI −/− and BCMA −/− mice suggest the existence of additional receptor(s) for BLyS. The TACI knockout gives the paradoxical result of B cells being hyperresponsive, suggesting an inhibitory role for this receptor [11, 12], while BCMA null mice have no discernable phenotype [13]. Here we report the identification of a third BLyS receptor (BR3; BLyS receptor 3). This receptor is unique in that, in contrast to TACI and BCMA, BR3 only binds BLyS. Treatment of antigen-challenged mice with BR3-Fc inhibited antibody production, indicating an essential role for BLyS, but not APRIL, in this response. A critical role for BR3 in B cell ontogeny is underscored by our data showing that the BR3 gene had been inactivated by a discrete, approximately 4.7 kb gene insertion event that disrupted the 3′ end of the BR3 gene in A/WySnJ mice, which lack peripheral B cells.

B-cell maturation protein (BCMA) is a member of the tumor necrosis factor (TNF) receptor family and is expressed in B lymphocytes. BCMA binds two TNF family members, BAFF and APRIL, that stimulate cellular proliferation. BAFF in particular has been shown to influence B-cell survival and activation, and transgenic mice overexpressing BAFF have a lupus-like autoimmune disorder. We have inactivated BCMA in the mouse germ line. BCMA(-/-) mice have normal B-cell development, and the life span of mutant B lymphocytes is comparable to that of wild-type B cells. The humoral immune responses of BCMA(-/-) mice to T-cell-independent antigens as well as high and low doses of T-cell-dependent antigens are also intact. In addition, mutant mice have normal splenic architecture, and germinal centers are formed during an ongoing immune response. These data suggest a functional redundancy of BCMA in B-cell physiology that is probably due to the presence of TACI, another TNF receptor family member that is expressed on B cells and that can also bind BAFF and APRIL.

Gliomas are common and lethal tumors of the central nervous system (CNS). Genetic alterations, inflammatory and angiogenic processes have been identified throughout tumor progression; however, treatment still remains palliative for most cases. Biological research on parameters influencing cell survival, invasion and tumor heterogeneity identified several cytokines interfering in CNS inflammation, oxidative stress and malignant transformation, including TNF-superfamily (TNFSF) members. In this report we performed a meta-analysis of public gene-array data on the expression of a group of TNFSF ligands (BAFF, APRIL, TWEAK) and their receptors (BAFF-R, TACI, BCMA, Fn14) in gliomas. In addition, we investigated by immunohistochemistry (IHC) the tumor cells' expression of these ligands and receptors in a series of 56 gliomas of different grade. We show that in IHC, BAFF and APRIL as well as their cognate receptors (BCMA, TACI) and Fn14 expression correlate with tumor grade. This result was not evidenced in micro-arrays meta-analysis. Finally, we detected for the first time Fn14, BAFF, BCMA and TACI in glioma-related vascular endothelium. Our data, combined with our previous report in glioma cell lines, suggest a role for these receptors and ligands in glioma biology and advance these molecules as potential markers for the classification of these tumors to the proliferative, angiogenic or stem-like molecular subtype.

A proliferation-inducing ligand (APRIL) is a ligand of the tumor necrosis factor (TNF) family that stimulates tumor cell growth in vitro and in vivo. Expression of APRIL is highly upregulated in many tumors including colon and prostate carcinomas. Here we identify B cell maturation antigen (BCMA) and transmembrane activator and calcium modulator and cyclophilin ligand (CAML) interactor (TACI), two predicted members of the TNF receptor family, as receptors for APRIL. APRIL binds BCMA with higher affinity than TACI. A soluble form of BCMA, which inhibits the proliferative activity of APRIL in vitro, decreases tumor cell proliferation in nude mice. Growth of HT29 colon carcinoma cells is blocked when mice are treated once per week with the soluble receptor. These results suggest an important role for APRIL in tumorigenesis and point towards a novel anticancer strategy.

An expression cloning approach was employed to identify the receptor for B-lymphocyte stimulator (BLyS) and identified the tumor necrosis factor receptor superfamily member TACI as a BLyS-binding protein. Expression of TACI in HEK293T cells confers on the cells the ability to bind BLyS with subnanomolar affinity. Furthermore, a TACI-Fc fusion protein recognizes both the cleaved, soluble form of BLyS as well as the membrane BLyS present on the cell surface of a recombinant cell line. TACI mRNA is found predominantly in B-cells and correlates with BLyS binding in a panel of B-cell lines. We also demonstrate that TACI interacts with nanomolar affinity with the BLyS-related tumor necrosis factor homologue APRIL for which no clear in vivo role has been described. BLyS and APRIL are capable of signaling through TACI to mediate NF-kappaB responses in HEK293 cells. We conclude that TACI is a receptor for BLyS and APRIL and discuss the implications for B-cell biology.

The human Taci gene (Transmembrane Activator and CAML Interactor) encodes a recently discovered member of the Tumor Necrosis Factor Receptor family. TACI is expressed in B-lymphocytes and may act to regulate humoral immunity. To identify functionally important regions of the protein, we have isolated and characterized the murine homolog of the human Taci cDNA. The proteins display 61.5% similarity and 54.6% identity. Mouse TACI is a type III transmembrane protein, as judged by the lack of a cleaved signal sequence and its N-terminal extracellular exposure. The intracellular domains of the mouse and human proteins share a single, defined region of high sequence conservation (19 of 23 residues identical). This constitutes a novel domain that may play a part in the initiation of signal transduction through TACI. In support of this notion, mouse TACI was found to activate NFAT, NFkB, and AP1 transcription factors in a transient transfection assay. The Taci gene was localized to human Chromosome (Chr) 17p11 by fluorescence in situ hybridization. The murine homolog was localized by intraspecific backcross analysis to the middle of Chr 11, a region that is syntenic to human Chr 17p. This work identifies conserved domains within TACI that may mediate the cellular distribution and signal transduction function of the protein and extend the details of homology between mouse Chr 11 and human 17p.

BLyS (also called TALL-1, THANK, or BAFF) [1] [2] [3] [4] is a member of the tumor necrosis factor (TNF) gene family that stimulates proliferation and immunoglobulin production by B cells. BLyS interacts with the TNF receptor (TNFR) homologue TACI (transmembrane activator and CAML-interactor) [5], and treatment of mice with a TACI-Fc fusion protein abolishes germinal center formation after antigenic challenge [6]. Here we report a novel interaction between BLyS and another TNFR homologue, BCMA (B cell maturation antigen) [7] [8]. Further, the TNF homologue APRIL [9], a close relative of BLyS, also bound to BCMA and TACI. BLyS or APRIL activated nuclear factor-kappaB (NF-kappaB) through TACI and BCMA, and each ligand stimulated immunoglobulin M (IgM) production by peripheral blood B cells. These results define a dual ligand-receptor system that may play an important role in humoral immunity.

B cells are important in the development of autoimmune disorders by mechanisms involving dysregulated polyclonal B-cell activation, production of pathogenic antibodies, and co-stimulation of autoreactive T cells. zTNF4 (BLyS, BAFF, TALL-1, THANK) is a member of the tumour necrosis factor (TNF) ligand family that is a potent co-activator of B cells in vitro and in vivo. Here we identify two receptors for zTNF4 and demonstrate a relationship between zTNF4 and autoimmune disease. Transgenic animals overexpressing zTNF4 in lymphoid cells develop symptoms characteristic of systemic lupus erythaematosus (SLE) and expand a rare population of splenic B-Ia lymphocytes. In addition, circulating zTNF4 is more abundant in NZBWF1 and MRL-lpr/lpr mice during the onset and progression of SLE. We have identified two TNF receptor family members, TACI and BCMA, that bind zTNF4. Treatment of NZBWF1 mice with soluble TACI-Ig fusion protein inhibits the development of proteinuria and prolongs survival of the animals. These findings demonstrate the involvement of zTNF4 and its receptors in the development of SLE and identify TACI-Ig as a promising treatment of autoimmune disease in humans.

We and others recently reported tumor necrosis factor (TNF) and apoptosis ligand–related leukocyte-expressed ligand 1 (TALL-1) as a novel member of the TNF ligand family that is functionally involved in B cell proliferation. Transgenic mice overexpressing TALL-1 have severe B cell hyperplasia and lupus-like autoimmune disease. Here, we describe expression cloning of a cell surface receptor for TALL-1 from a human Burkitt's lymphoma RAJI cell library. The cloned receptor is identical to the previously reported TNF receptor (TNFR) homologue transmembrane activator and calcium modulator and cyclophilin ligand (CAML) interactor (TACI). Murine TACI was subsequently isolated from the mouse B lymphoma A20 cells. Human and murine TACI share 54% identity overall. Human TACI exhibits high binding affinities to both human and murine TALL-1. Soluble TACI extracellular domain protein specifically blocks TALL-1–mediated B cell proliferation without affecting CD40- or lipopolysaccharide-mediated B cell proliferation in vitro. In addition, when injected into mice, soluble TACI inhibits antibody production to both T cell–dependent and –independent antigens. By yeast two-hybrid screening of a B cell library with TACI intracellular domain, we identified that, like many other TNFR family members, TACI intracellular domain interacts with TNFR-associated factor (TRAF)2, 5, and 6. Correspondingly, TACI activation in a B cell line results in nuclear factor κB and c-Jun NH2-terminal kinase activation. The identification and characterization of the receptor for TALL-1 provides useful information for the development of a treatment for B cell–mediated autoimmune diseases such as systemic lupus erythematosus.

B-lymphocyte stimulator/B-cell activating factor (BLyS/BAFF) and a proliferation-inducing ligand (APRIL), members of the tumor necrosis family of ligands, are expressed by monocytes, macrophages, and dendritic cells, and increased expression of these ligands is noted in lymphomas and plasma cell malignancies. BLyS and APRIL are essential for the survival of normal and malignant B lymphocytes, and altered expression of BLyS or APRIL or the receptors B-cell maturation, transmembrane activator and calcium-modulating cyclophilin ligand interactor, or BAFF-R have been reported in various B-cell malignancies, including B-cell non-Hodgkin's lymphoma, chronic lymphocytic leukemia, Hodgkin's lymphoma, multiple myeloma, and Waldenstrom's macroglobulinemia. Levels of BLyS (in the tumor and in the serum) increased with the transformation of the tumors to a more aggressive phenotype. A high BLyS level inversely correlated with a poor median overall survival, presence of constitutional symptoms, and increased levels of lactate dehydrogenase in patients with non-Hodgkin's lymphoma. Additionally, patients who responded to therapy had a lower BLyS level than those with progressive disease. Several agents targeting BLyS and APRIL are currently being pursued in phase I clinical studies in patients with B-cell malignancies.

Activation of the nuclear factor of activated T cells transcription factor (NF-AT) is a key event underlying lymphocyte action. The CAML (calcium-modulator and cyclophilin ligand) protein is a coinducer of NF-AT activation when overexpressed in Jurkat T cells. A member of the tumor necrosis factor receptor superfamily was isolated by virtue of its affinity for CAML. Cross-linking of this lymphocyte-specific protein, designated TACI (transmembrane activator and CAML-interactor), on the surface of transfected Jurkat cells with TACI-specific antibodies led to activation of the transcription factors NF-AT, AP-1, and NFκB. TACI-induced activation of NF-AT was specifically blocked by a dominant-negative CAML mutant, thus implicating CAML as a signaling intermediate.

T cell-independent antibody responses develop rapidly, within 3 to 4 days, and are critical for preventing blood-borne pathogens from evolving into life-threatening infections. The interaction of BAFF, also known as BLyS, with its receptors BAFFR and TACI on B cells is critical for B cell homeostasis and function. Using a synthetic polysaccharide antigen, it has previously been shown that TACI is critical for T cell-independent antibody responses. To examine the role of BAFFR and TACI in T cell-independent antibody responses to an active infection, we utilized the Borrelia hermsii infection system. In this infection system, T cell-independent responses mediated by the B1b cell subset are critical for controlling bacteremia. We found that B1b cells express BAFFR and TACI and that the surface expression of both receptors is upregulated on B1b cells following exposure to whole B. hermsii cells. Surprisingly, we found that TACI −/− mice are not impaired either in specific antibody responses to B. hermsii or in controlling B. hermsii bacteremia. In contrast, TACI-deficient mice immunized with heat-killed type 3 serotype pneumococcus cells are impaired in generating pneumococcal polysaccharide-specific responses and succumb to challenge with live type 3 serotype pneumococcus, indicating that TACI is required for T cell-independent antibody responses to bacterial-associated polysaccharides. Although we have found that TACI is dispensable for controlling B. hermsii infection, mice deficient in BAFFR or BAFF exhibit impairment in B. hermsii -specific IgM responses and clearance of bacteremia. Collectively, these data indicate a disparity in the roles for TACI and BAFFR in primary T cell-independent antibody responses to bacterial pathogens.

B lymphocyte stimulator (BLyS), a tumor neurosis factor ligand superfamily, is an important factor of B cell survival and activation. However, BLyS also regulates T cell activation and survival, playing key roles in T cell-mediated autoimmune disorders. In the paper, we introduced the mechanisms of BLyS and a proliferation-inducing ligand (APRIL) regulating T cell responses and their roles in rheumatoid arthritis (RA).

Objective: To identify methylated genes in serum with diagnostic potentials for early colorectal cancer (CRC).Methods: Serum methylation levels of up to 12 genes were measured in two sets of serum samples with the second set from 26 stage I CRC patients and 26 age/gender-matched controls.Results: Serum methylation levels of TAC1, SEPT9, and EYA4 were significant discriminants between stage I CRC and healthy controls. Combination of TAC1 and SEPT9 rendered 73.1% sensitivity with 92.3% specificity.Conclusion: Serum methylation levels of TAC1. SEPT9 and EYA4 may be useful biomarkers for early detection of CRC though a validation study is necessary.

Systemic lupus erythematosus (SLE) is a complex heterogeneous disease, posing challenges to clinical trials. As in other autoimmune diseases, B-lymphocytes play a central role in lupus pathogenesis. The finding that selection and survival of B cells are controlled by a variety of signals, including those provided by the longevity factor BAFF (B-cell activating factor), also called BLyS (B-lymphocyte stimulator), led to preclinical trials that revealed that BAFF represents a promising therapeutic target for human lupus. Belimumab is a fully human monoclonal antibody directed against BAFF. Lessons learned from early clinical trials led to improved methods and success of phase III trials, with recruitment of patients with both clinically and serologically active disease, development and use of a novel SLE Responder Index, and progressive and special restrictions on immunosuppressive and corticosteroid use. These studies offer an attractive blueprint to conduct future clinical trials in SLE. The overall steroid-sparing ability and benefits of belimumab on musculoskeletal and mucocutaneous organ systems suggest that it has an impact on the clinical management of SLE patients. Future directions include studies to determine the role of belimumab in early SLE, as well as in renal or CNS involvement.

To determine the necessity for any individual BAFF receptor in the development of systemic lupus erythematosus (SLE).Bcma-, Taci-, and Br3-null mutations were introgressed into NZM 2328 mice. NZM.Bcma-/-, NZM.Taci-/-, and NZM.Br3-/- mice were evaluated for lymphocyte phenotype and BAFF receptor expression by flow cytometry; for B cell responsiveness to BAFF by in vitro culture; for serum levels of BAFF and total IgG and IgG anti-double-stranded DNA (anti-dsDNA) by enzyme-linked immunosorbent assay; for renal immunopathology by immunofluorescence and histopathology; and for clinical disease.BCMA, TACI, and B lymphocyte stimulator receptor 3 (BR3) were not surface-expressed in NZM.Bcma-/-, NZM.Taci-/-, and NZM.Br3-/- mice, respectively. Transitional and follicular B cells from NZM.Br3-/- mice were much less responsive to BAFF than were the corresponding cells from wild-type, NZM.Bcma-/-, or NZM.Taci-/- mice. In comparison with wild-type mice, NZM.Bcma-/- and NZM.Taci-/- mice harbored an increased number of spleen B cells, T cells, and plasma cells, whereas serum levels of total IgG and IgG anti-dsDNA were similar to those in wild-type mice. Despite their paucity of B cells, NZM.Br3-/- mice had an increased number of T cells, and the numbers of plasma cells and levels of IgG anti-dsDNA were similar to those in wild-type mice. Serum levels of BAFF were increased in NZM.Taci-/- and NZM.Br3-/- mice but were decreased in NZM.Bcma-/- mice. Despite their phenotypic differences, NZM.Bcma-/-, NZM.Taci-/-, and NZM.Br3-/- mice had renal immunopathology and clinical disease that were at least as severe as that in wild-type mice.Any single BAFF receptor, including BR3, is dispensable for the development of SLE in NZM mice. Development of disease in NZM.Br3-/- mice demonstrates that BAFF-BCMA and/or BAFF-TACI interactions contribute to SLE, and that a profound, life-long reduction in the numbers of B cells does not guarantee protection against SLE.

B-cell activating factor (BAFF) has been used as a therapeutic target. To develop BAFF-specific small molecular inhibitors, it is necessary to know the key amino acid in the BAFF binding with its receptor. The key binding amino acid of BAFF interacting with its receptor TACI (trans-membrane activator and calcium modulator and cyclophilin ligand interactor) was analyzed based on the computer-guided molecular modeling method. According to theoretical prediction, a series of key amino acid mutants of BAFF, including M204 (Lys 204 to Ala), M208 (Met 208 to Ala), M209 (Gly 209 to Ala), M210 (His 210 to Ala), M234 (Gln 234 to Ala), M236 (Met 236 to Ala), and M237 (Pro 237 to Ala) were designed and evaluated with biological experiments. The results show that M208, M209, M236, and M237 of BAFF were the key amino acids and in accord with the theoretical results. The results highlight clues for the further development of BAFF-specific small molecular inhibitors.

Background Lung function is a long-term predictor of mortality and morbidity. Objective We sought to identify single nucleotide polymorphisms (SNPs) associated with lung function. Methods We performed a genome-wide association study (GWAS) of FEV 1 , forced vital capacity (FVC), and FEV 1 /FVC in 1144 Hutterites aged 6 to 89 years, who are members of a founder population of European descent. We performed least absolute shrinkage and selection operation regression to select the minimum set of SNPs that best predict FEV 1 /FVC in the Hutterites and used the GRAIL algorithm to mine the Gene Ontology database for evidence of functional connections between genes near the predictive SNPs. Results Our GWAS identified significant associations between FEV 1 /FVC and SNPs at the THSD4-UACA-TLE3 locus on chromosome 15q23 ( P = 5.7 × 10 −8 to 3.4 × 10 −9 ). Nine SNPs at or near 4 additional loci had P −5 with FEV 1 /FVC. Only 2 SNPs were found with P −5 for FEV 1 or FVC. We found nominal levels of significance with SNPs at 9 of the 27 previously reported loci associated with lung function measures. Among a predictive set of 80 SNPs, 6 loci were identified that had a significant degree of functional connectivity (GRAIL P CCL18 and CXCL12 ), and TNFRSF13B . Conclusion This study identifies genome-wide significant associations and replicates results of previous GWASs. Multimarker modeling implicated for the first time common variation in genes involved in antimicrobial immunity in airway mucosa that influences lung function.

Low albumin:globulin (A/G) ratios are associated with vascular adverse events, nephrotic syndrome and autoimmune disease. Genome-wide association studies (GWASs) have been identifying genetic variants associated with total serum protein, serum albumin and globulins, but A/G ratio has never been considered the target phenotype. To identify the genetic basis of the A/G ratio, we performed a GWAS on A/G ratio in 4205 individuals from the Ansan cohort and confirmed the results in 4637 subjects from the Ansung cohort. The single-nucleotide polymorphism (SNP) genotypes of Affymetrix SNP array 5.0 were obtained from the Korean Association Resource Consortium, and we selected 290 659 common SNPs with a minor allele frequency0.05. Genetic factors for A/G ratio were analyzed by linear regression analysis, controlling for age, sex, body mass index, smoking status and alcohol drinking status as covariates. From the GWAS of the Ansan cohort, we identified two significant genome-wide signals (P-values5 × 10(-8)) and 36 moderate signals (P-value1.0 × 10(-4)). These 38 signals were tested in the Ansung population. Eleven SNPs from six loci (GALNT2, IRF4, HLA-DBP1, SLC31A1, FADS1 and TNFRSF13B) were replicated, with P-values0.05. The most compelling association was observed in the TNFRSF13B locus on chromosome 17p11.2 (SNP: rs4561508), with an overall combined P-value=7.80 × 10(-24). The other significant signal was observed on chromosome 11q12.2-the FADS1 locus (SNP: rs174548)-with an overall combined P-value=3.54 × 10(-8).

TNFRSF13B/TACIdefects have been associated with CVID pathogenesis and/or phenotype, especially the development of benign lymphoproliferation and autoimmunity. Our purpose was to investigate the role ofTNFRSF13B/TACIdefects in the pathogenesis of two common lymphoproliferative disorders, namely, sarcoidosis and tonsillar hypertrophy (TH). 105 patients (71 with sarcoidosis and 34 with TH, including 19 without infectious causative and 15 due toHaemophilus influenzae) were analyzed forTNFRSF13B/TACIdefects. Two out of 19 TH patients without infectious cause (10.5%) and 2 patients with sarcoidosis (2.8%) displayed rareTNFRSF13B/TACIdefects (I87N, L69TfsX12, E36L, and R202H, resp.). Both mutations identified in TH patients have been assessed as deleterious for protein function, while the patient with the R202H mutation and sarcoidosis exhibited also sIgG4D. Our study further supports the notion thatTNFRSF13B/TACIdefects alone do not result in CVID but may be also found frequently in distinct clinical phenotypes, including benign lymphoproliferation and IgG subclass deficiencies.

B cells from common variable immunodeficiency (CVID) patients who have one mutant copy of the gene encoding the transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) often display dysfunctional antibody production. Interestingly, some individuals with mutations in both TACI alleles do not present with CVID, suggesting that TACI mutations influence CVID pathogenesis via dominant interference or haploinsufficiency. In this issue of the JCI, Romberg and colleagues report how TACI mutations impact B cell activation, removal of autoreactive B cells, and the development of autoimmune disease in CVID.

Mutations in the gene coding for the transmembrane activator and calcium-modulating cyclophilin ligand interactor (TACI) are found in 8% to 10% of subjects with common variable immunodeficiency (CVID). Although heterozygous mutations may coincide with immunodeficiency in a few families, most mutation-bearing relatives are not hypogammaglobulinemic. Thus, the role of TACI mutations in producing the immune defect remains unclear. Objective: This study examined the expression and function of TACI mutations in healthy heterozygous relatives. Methods: We examined the surface and intracellular expression of TACI protein in EBV-transformed B cells of patients and relatives with mutations in 7 families, binding of a proliferationinducing ligand, and secretion of IgG and IgA by ligandactivated B cells.We tested whether Toll-like receptor 9 agonists increased TACI expression and whether an agonistic anti-TACI antibody could induce activation-induced cytidine deaminase mRNA in those with mutations. Results: Intracellular and extracellular TACI expression was defective for B cells of all subjects with mutations, including subjects with CVID and relatives. Although Toll-like receptor 9 triggering normally up-regulates B-cell TACI expression, this was defective for all subjects with mutations. Triggering TACI by an agonistic antibody showed loss of activation-induced cytidine deaminase mRNA induction in all mutation-bearing B cells. However, ligand-induced IgG and IgA production was normal for healthy relatives but not for subjects with CVID. Conclusion: Thus, B cells of relatives of subjects with CVID who have mutations in TACI but normal immune globulin levels still have detectable in vitro B-cell defects. Fil: Martinez Gallo, Monica. Mount Sinai School of Medicine. Departament of Pediatrics; Estados Unidos. Mount Sinai School of Medicine. Immunology Institute; Estados Unidos. Hospital Universitari Vall d; España Fil: Radigan, Lin. Mount Sinai School of Medicine. Departament of Medicine; Estados Unidos Fil: Almejún, María Belén. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan". Servicio de Inmunolog ía y Reumatolog ía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mart ınez Pomar, Natalia. Son Espases University Hospital. Servei d’ Immunolog ia; España Fil: Matamoros, Nuria. Son Espases University Hospital. Servei d’ Immunolog ia; España Fil: Cunningham Rundles, Charlotte. Mount Sinai School of Medicine. Departament of Medicine; Estados Unidos. Mount Sinai School of Medicine. Immunology Institute; Estados Unidos. Mount Sinai School of Medicine. Departament of Pediatrics; Estados Unidos

Mutations in TNFRSF13B, better known as transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), contribute to common variable immunodeficiency and autoimmunity in humans. How TACI regulates these two opposing conditions is unclear, however. TACI binds the cytokines BAFF and APRIL, and previous studies using gene KO mice indicated that loss of TACI affected only T-cell–independent antibody responses. Here we demonstrate that Taci −/− mice have expanded populations of T follicular helper (T fh ) and germinal center (GC) B cells in their spleens when immunized with T-cell–dependent antigen. The increased numbers of T fh and GC B cells in Taci −/− mice are largely a result of up-regulation of inducible costimulator (ICOS) ligand on TACI-deficient B cells, given that ablation of one copy of the Icosl allele restores normal levels of T fh and GC B cells in Taci −/− mice. Interestingly, despite the presence of increased T fh and antigen-specific B cells, immunized Taci −/− mice demonstrate defective antigen-specific antibody responses resulting from significantly reduced numbers of antibody-secreting cells (ASCs). This effect is attributed to the failure to down-regulate the proapoptotic molecule BIM in Taci −/− plasma cells. Ablation of BIM could rescue ASC formation in Taci −/− mice, suggesting that TACI is more important for the survival of plasma cells than for the differentiation of these cells. Thus, our data reveal dual roles for TACI in B-cell terminal differentiation. On one hand, TACI modulates ICOS ligand expression and thereby limits the size of T fh and GC B-cell compartments and prevents autoimmunity. On the other hand, it regulates the survival of ASCs and plays an important role in humoral immunity.

Mutations in the transmembrane activator and calcium-modulating cyclophilin ligand interactor (TACI) were previously found to be associated with hypogammaglobulinemia in humans. It has been shown that proliferation inducing ligand (APRIL) elicits class switch recombination (CSR) by inducing recruitment of MyD88 to a TACI highly conserved cytoplasmic domain (THC). We have identified a patient with hypogammaglobulinemia carrying a missense mutation (S231R) predicted to affect the THC. Aiming to evaluate the relevance of this novel mutation of TACI in CSR induction, we tested the ability of TACI, TLR9, or/and CD40 ligands to trigger CSR in naive B cells and B-cell lines carrying S231R. IgG secretion was impaired when triggered by TACI or/and TLR9 ligands on S231R-naive B cells. Likewise, these stimuli induced less expression of activation-induced cytidine deaminase, I(γ)1-C(μ), and I(γ)1-C(μ), while induction by optimal CD40 stimulation was indistinguishable from controls. These cells also showed an impaired cooperation between TACI and TLR9 pathways, as well as a lack of APRIL-mediated enhancement of CD40 activation in suboptimal conditions. Finally, after APRIL ligation, S231R-mutated TACI failed to colocalize with MyD88. Collectively, these results highlight the requirement of an intact MyD88-binding site in TACI to trigger CSR.

Common Variable Immunodeficiency Disorder (CVID) is a complex disorder that predisposes patients to recurrent and severe infections. The C104R mutation in the transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) is the most frequent mutation identified in patients with CVID. We carried out a detailed immunological and molecular study in a family with a C104R mutation. We have undertaken segregation analysis of a kindred with C104R mutations of the TACI gene. Detailed immunological and molecular investigations were carried out for this kindred and the clinical phenotype was compared to the genotype. Segregation analysis of our kindred showed that inheriting single or double copy of the C104R mutation does not consign an individual to CVID. All heterozygotes in the family were phenotypically different, ranging from asymptomatic to ill-health. A family member with a wild type TACI variant had CVID-related phenotype including IgA deficiency and type 1 diabetes. Interestingly, a family member with the homozygous C104R/C104R variant did not meet the criteria for CVID because he had excellent, albeit unsustained, vaccine responses to T cell dependent and T cell independent vaccine antigens despite profound hypogammaglobulinemia. The C104R mutation does not correlate with the clinical phenotypes in this family.

CD256 and CD257 belong to the TNFSF (Tumor necrosis factor superfamily), share closest homology structure, and can form functional heterotrimers. They may be involved in the progression of SLE (Systemic lupus erythematosus), RA (Rheumatoid arthritis), and other autoimmune disorders. In this present study, CD256 and some related molecules were detected and were investigated regarding the potential role of the CD256 signal during the development of renal allograft rejection.In 2009, 46 cases of renal allografts were collected, excised for evaluation of dysfunction, and 10 renal protocol biopsies with normal renal function were controlled. Immunohistochemistry (IHC) staining was applied to detect CD256, CD257, C4d, CD138 and other related molecules. HistoQuest Analysis software and SPSS16.0 were used to read and analyse the results.Pathological diagnosis was made according to Banff 2005 guidelines: antibody-mediated rejection (ABMR) 15 cases, T-cell-mediated rejection (TCMR) 16 cases, and 15 unknown aetiology cases (UAC). IHC results showed that CD256, CD257, and receptors for B cell activating factor receptor (BAFF-R), B cell maturation antigen (BCMA), and transmembrane activator calcium modulator, and cyclophilin ligand interactor (TACI) were expressed on the membrane/cytoplasm of renal tubular epithelial cells (RTEC) in the ABMR and TCMR group, while these molecules were not or weakly expressed in UAC and protocol biopsies. CD257 strong staining could be seen in ABMR, CD256 strong staining in both BCMR and TCMR, and there was statistical significance compared with other groups (p0.05). The receptors BAFF-R, BCMA, and TACI all strongly stained in ABMR, TACI also stained strongly in TCMR, and there was statistical significance compared with other groups (p0.05). The CD138+ molecule could be found in the renal interstitium and membrane/cytoplasm of RTEC, the CD138 mean expression in ABMR was statistically higher than other groups (p0.05). The correlation analysis indicated that CD256 significantly correlated with BCMA, TACI, and CD138, while CD257 significantly correlated with BAFF-R, BCMA, TACI, and CD138.CD256 can be found in ABMR tissues and may participate in the progression of ABMR together with CD257.

IgG has a crucial role in humoral immune response. Serum IgG level is mainly determined under genetic control. To explore the genetic influence on serum IgG levels, a two-stage genome-wide association study (GWAS) was performed in a healthy Chinese population of 3495 men, including 1999 unrelated subjects in the first stage and 1496 independent individuals in the second stage. Three single-nucleotide polymorphisms (SNPs) located in TNFRSF13B on 17p11.2 or nearby were significantly associated with IgG level: rs4792800 in the intron (combined P-value=1.45 × 10(-12)), rs12603708 in the intron (combined P-value=1.82 × 10(-8)) and rs3751987 at ~65 kb downstream of the 5'-UTR region of TNFRSF13B (combined P-value=3.67 × 10(-9)). Additionally, smoking was identified to be associated with IgG level in both stages (P0.001), but there was no significant interaction between smoking and the identified SNPs (P0.05). The strong association between variants at TNFRSF13B and IgG level may be helpful to further explore the biological mechanism by which the serum IgG is affected by transmembrane activator, calcium modulator and cyclophilin ligand interactor encoded by TNFRSF13B.

Background and aims Common variable immunodeficiency (CVID) is a primary antibody deficiency characterised by decreased antibody production and low or normal B-cell numbers. To elucidate the clinical and immunological heterogeneity of CVID, we studied 16 patients diagnosed with CVID. Methods We analysed B, T and NK cell populations. We also assessed CD27 expression to define B-cell subsets and examined the expression of molecules important in B-cell proliferation and differentiation, such as the transmembrane activator and CALM interactor (TACI), inducible costimulator (ICOS), CD154 and CD40. Results We observed reduced B and T-cell numbers in CVID patients; this reduction was more pronounced in adults. While one group of patients (group I) showed a significant reduction in CD27+ memory B-cells, another group (group II) of patients exhibited numbers of CD27+ memory B-cells similar to the healthy donor. The frequency of B-cells and T-cells expressing CD40 and ICOS, respectively, was significantly lower in all CVID patients compared with healthy donors. Finally, a correlation between the frequency of CD27+ memory B-cells and clinical features was observed in CVID patients. Conclusion These results suggest that in some patients, the combined defects in both T and B-cells may account for CVID. Additionally, patients in group I exhibited an increased frequency of pneumonia and chronic diarrhoea.

B lymphocyte subpopulations, previously defined classification schemes (Freiburg, Paris, EuroClass), TNFRSF13B (TACI), TNFRSF13C (BAFF-R), TNFSF13 (APRIL) gene mutations, CTLA-4 and ICOS gene polymorphisms were analyzed in 25 common variable immunodeficiency (CVID) patients and 25 healthy controls. Patients were also divided into two subgroups due to some disease severity criteria. SG (severe disease group) (n:11) included patients who have splenomegaly and/or granulomatous diseases and/or bronchiectasis and/or lower baseline IgG values (270 mg/dl). MG (moderate disease group) (n:14) patients diagnosed as having ESID/PAGID criteria but does not fulfill SG inclusion criteria. The onset of infectious symptoms and age at diagnosis were 50.0 ± 45.7 and 78.5 ± 54.5 months, respectively. Parental consanguinity rate was 54.5% in SG and 7.1% in MG. Switched-memory B cells (CD19 + 27 + IgD-IgM-) showed significant decrease in CVID patients and these cells were also significantly lower in SG compared to MG. CVID patients had significantly higher percentages of CD19 + κ + B cells and CD19 + λ + B cells than healthy controls. Freiburg classification: 87.5% of patients (n:21) were in group I and 12.5% were in Group II. Eighteen (75%) CVID patients with a low percentage of CD21(low) B cells were in Group Ib while three patients classified as Group Ia. The significantly lower levels of IgG and IgA in Group Ia is a novel finding. The percentages of patients for Paris Classification groups MB0, MB1, MB2 were 88%, 4% and 8%, respectively. There was a significant increase of splenomegaly, lymphadenopathy and autoimmune cytopenia in Group MB0. EuroClass: 45.8% of patients were smB+ and 54.2% were smB-. Splenomegaly and lymphadenopathy were significantly higher in smB- group. TACI: One patient carried heterozygous C104R mutation which was known as disease causing. APRIL: G67R and N96S SNPs were detected in most of the patients and healthy controls. BAFF-R: P21R/H159Y compound heterozygous mutation (n:1) and P21R heterozygous mutations (n:3) were detected. +49 A G changes in exon 1 of CTLA-4 gene: GG and AG genotypes increase the risk of CVID development 1.32 and 2.18 fold, respectively. 1564 T C polymorphisms on 3'UTR region in exon 2 of ICOS gene was not found to be significantly different in CVID patients. CVID classifications were not helpful in determining the genetic etiology of CVID.

Background The role of B Lymphocyte Stimulator (BLyS) in the survival of malignant B cells and the maintenance of normal B cell development and homeostasis has been intensively studied in the literature. However, the influence of BLyS on breast cancer progression remains unclear. The study aimed to investigate the effect of hypoxia on BLyS regulation, cell migratory response to BLyS and the possible molecular mechanisms. Methods In this study, we examined the role of BLyS in the migration of human breast cancer cells by transwell assay. We also explored whether BLyS and its receptors expressed in human breast cancer cell lines by immunofluorescence and Western Blotting. Then we detected the expression level of BLyS in both normoxic and hypoxic conditions by real time-PCR and Western Blotting. Pathways involved were confirmed by Western Blotting, immunofluorescence, transwell assay and luciferase assay. Results According to our study, the expression level of BlyS was increased in human breast cancer cell lines in hypoxic conditions. Up-regulation of this protein led to activation and nuclear translocation of NF-kappa B p65. We also found that the number of migrated cells was increased in the presence of BLyS and inhibition of phosphorylation of Akt attenuated the enhanced migratory response. Conclusions It suggested that better understanding of BLyS, an immunopotentiator, may offer a potential therapeutic target for the treatment of human breast cancers. In addition, BLyS promoted breast cancer cells migration, underscoring the necessity of appropriate applications of immunopotentiators to cancer treatment.

Patients with Sjögren's syndrome (SS) show aberrant expression of the B cell-related mediators, B cell-activating factor (BAFF), and a proliferation-inducing ligand (APRIL) in serum and salivary glands (SGs). We studied the biological effect of neutralizing these cytokines by local gene transfer of the common receptor transmembrane activator and CAML interactor (TACI) in an animal model of SS.A recombinant serotype 2 adeno-associated virus (rAAV2) encoding TACI-Fc was constructed, and its efficacy was tested in the SGs of non-obese diabetic mice. Ten weeks later, SG inflammation was evaluated and serum and SG tissue were analyzed for inflammatory markers including immunoglobulins (Ig) and cytokines.AAV2-TACI-Fc gene therapy significantly reduced the number of inflammatory foci in the SG, owing to a decrease in IgD(+) cells and CD138(+) cells. Moreover, IgG and IgM levels, but not IgA levels, were reduced in the SG. Overall expression of mainly proinflammatory cytokines tended to be lower in AAV2-TACI-Fc-treated mice. Salivary flow was unaffected.Although local expression of soluble TACI-Fc reduced inflammation and immunoglobulin levels in the SG, further research will have to prove whether dual blockade of APRIL and BAFF by TACI-Fc can provide a satisfying treatment for the clinical symptoms of patients.

Common variable immunodeficiency (CVID) is considered the most common symptomatic antibody deficiency and, although mainly reported in adults, it may present from childhood. Few data on the impact of TACI defects on the clinical and immunological status of children are available. We screened 42 hypogammaglobulinemic children to investigate the frequency and mutational features of TACI defects. The genetic, clinical and immunological characterization was extended to 31 relatives of 11 children with TACI mutations. Of interest, our analysis showed a considerably higher mutation frequency in hypogammaglobulinemic children (13/42; 31#x0025;) than in other cohorts of adult patients. In seven out of nine families with the C104R variant, the prevalence of autoimmunity was significantly higher in C104R heterozygous relatives (8/15; 53#x0025;) than in those with no C104R mutation (1/11; 9#x0025;). Our data suggest a different impact of TACI mutations, from hypogammaglobulinemia in children to autoimmune disease in adulthood.

SummaryActivation-induced cell death (AICD) plays a critical role in immune homeostasis and tolerance. In T-cell-dependent humoral responses, AICD of B cells is initiated by Fas ligand (FasL) on T cells, stimulating the Fas receptor on B cells. In contrast, T-cell-independent B cell responses involve innate-type B lymphocytes, such as marginal zone (MZ) B cells, and little is known about the mechanisms that control AICD during innate B cell responses to Toll-like receptor (TLR) activation. Here, we show that MZ B cells undergo AICD in response to TLR4 activation in vivo. The transmembrane activator, calcium modulator, and cyclophilin ligand interactor (TACI) receptor and TLR4 cooperate to upregulate expression of both FasL and Fas on MZ B cells and also to repress inhibitors of Fas-induced apoptosis signaling. These findings demonstrate an unappreciated role for TACI and its ligands in the regulation of AICD during T-cell-independent B cell responses.

Human adipose-derived stem cells (hASC) are mesenchymal stem cells with reduced immunogenicity and the ability to modulate immune responses. APRIL and BAFF proteins are overexpressed in inflammatory and autoimmune diseases for which allogeneic hASC therapy is currently under clinical investigation. Modification of hASC properties by the tissue microenvironment could be a critical factor in patient outcome and is still not well understood. Our aim was to characterize the APRIL/BAFF system in hASC by analyzing the ligand and receptor expression patterns, the effects mediated by APRIL and BAFF on hASC, and the underlying signaling. We found that hASC express the tumor necrosis factor proteins APRIL (a proliferation-inducing ligand) and BAFF (B cell-activator factor) as well as their receptors TACI (transmembrane activator and calcium-modulator and cyclophilin ligand interactor), BCMA (B cell maturation antigen) and the BAFF-specific receptor (BAFF-R). APRIL and BAFF secretion was differentially enhanced by CXCL12 and interferon (IFN)-γ, implicated in hASC-mediated migration and immunosuppression, respectively. In addition, APRIL and BAFF induced rapid phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) and Akt kinases and promoted an increase in hASC proliferation, without affecting the immunosuppressive capacity of these cells. The use of specific chemical inhibitors indicated that the PI3K transduction pathway is involved in hASC basal growth and that APRIL- and BAFF-mediated effects are ERK-dependent. These results provide new information about the molecular mechanisms that underlie APRIL and BAFF secretion and signaling in hASC, and are of special relevance for the use of allogeneic hASC as therapeutic tools.