The role of TNF-α superfamily members in immunopathogenesis of sepsis.

BACKGROUND: Members of TNFα superfamily, A proliferation inducing ligand (APRIL), B-cell activating factor (BAFF) and Transmembrane activator and calcium cyclophylin interactor (TACI) are main regulators of B-cell function. The aim of this study was to evaluate concentrations of APRIL, BAFF and soluble TACI (sTACI) receptor in septic patients compared to healthy controls and compare concentrations of these biomarkers depending on sepsis severity and outcome. MATERIALS AND METHODS: A total of 115 septic patients and 30 healthy volunteers were included and concentrations of APRIL, BAFF and sTACI were determined in all subjects at the admission (ELISA R&D Systems tests). Concentrations of these biomarkers in function of sepsis severity (sepsis n = 94 and septic shock n = 21) and outcome (lethal n = 40, recovery n = 75) were tested, as well as correlations with APACHE II and SOFA scores, immunoglobulins, complement, PCT and CRP concentrations. RESULTS: Concentrations of all three biomarkers were significantly increased in septic patients compared to controls (AUCAPRIL = 0.982, AUCBAFF = 0.873, AUCsTACI = 0.683). Higher concentrations of APRIL and sTACI (p = 0.033, p = 0.037), and lower concentrations of BAFF (p = 0.005) were observed in patients with septic shock compared to sepsis. BAFF concentrations correlated positively with IgM, C3 and C4 levels. sTACI and APRIL were shown to be predictors of lethal outcome (p = 0.003, p = 0.049). CONCLUSIONS: Concentrations of observedTNFα superfamily members are significantly increased in septic patients, confirming their role in sepsis pathogenesis.Higher concentrations of anti-inflammatory sTACI receptor correlated with severity of sepsis and poorer prognosis, thus potentially indicating domination of anti-inflammatory response in septic patients with worse outcome.

B cell phenotypes in patients with rheumatoid arthritis relapsing after rituximab: expression of B cell-activating factor-binding receptors on B cell subsets.

Serum levels of B cell-activating factor (BAFF) rise following rituximab (RTX) therapy in patients with rheumatoid arthritis (RA). Initiation of naive B cell return to the periphery and autoreactive B cell expansion leading to relapse after RTX may therefore be linked to interactions between BAFF and BAFF-binding receptors (BBR). Relationships between serum BAFF and BBR expression [(BAFFR, calcium signal modulating cyclophilic ligand interactor (TACI) and B cell maturation antigen (BCMA)] were determined on B cell subsets, defined using immunoglobulin (Ig)D/CD38. Twenty pre-RTX and 18 RA patients relapsing after B cell depletion were included. Results were analysed with respect to timing of relapse up to 7 months after peripheral B cell return (≥ 5 B cells/µl) and to serum BAFF levels. After B cell return, B cell populations from relapsing patients had significantly lower BAFFR+ expression compared to HC and pre-RTX patients. The percentage of BAFFR+ B cells increased with time after B cell return and was correlated inversely with serum BAFF levels. BAFFR expression remained reduced. The percentage of TACI+ memory B cells were lower in RA patients after RTX compared with healthy controls (HC). BCMA expression (% and expression) did not differ between patients and HC. Relapse following B cell return appeared largely independent of the percentage of BAFFR+ or percentage of BCMA+ B cells or serum BAFF levels. The lower percentage of TACI+ memory B cells may reduce inhibitory signalling for B cell differentiation. In patients relapsing at longer periods after B cell return, recovery of the B cell pool was more complete, suggesting that selection or expansion of autoreactive B cells may be needed to precipitate relapse.

Serum methylation levels of TAC1. SEPT9 and EYA4 as diagnostic markers for early colorectal cancers: a pilot study.

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.

APRIL and sTACI could be predictors of multiorgan dysfunction syndrome in sepsis.

Although the role of B cells in sepsis immunoregulation has become an interesting topic, there is lack of data on the role of B cell function regulators in prediction of multiorgan dysfunction syndrome (MODS). The aim of this study was to evaluate the prognostic value of A Proliferation Inducing Ligand (APRIL) and soluble Transmembrane Activator and CAML Interactor Protein (sTACI), the main B cell function regulators, in prediction of MODS development within the first 48 h after admission to intensive care unit, among septic patients. We included 112 patients with sepsis, treated at Clinic for Infectious Diseases and Emergency Center, Clinical Center of Vojvodina, Novi Sad, Serbia. Plasma concentrations of APRIL and sTACI were determined at the admission and potential development of MODS was confirmed in the first 48 h. Concentrations of APRIL (p = 0.003) and sTACI (p<0.001) were higher in patients who developed MODS (n = 30). ROC curve analysis showed that AUC for sTACI (AUC = 0.764) was greater than that for procalcitonin (AUC = 0.719) and APRIL (AUC = 0.673) in MODS development prediction. Multivariate regression analysis showed that sTACI, as an anti-inflammatory biomarker stimulating the apoptosis of B cells, was the only independent predictor of MODS, beside SOFA score. Elevated level of sTACI could be the alarm for the increased B cell apoptosis and development of immune paralysis. Including these biomarkers into predictive scores specific for septic patients may potentially improve their sensitivity and specificity. Measurement of their concentrations dynamics could contribute to better assessment of sepsis evolution and timely introduction of immunomodulatory therapy.

Pharmacokinetics, Pharmacodynamics, Safety, and Clinical Activity of Multiple Doses of RCT-18 in Chinese Patients With Systemic Lupus Erythematosus.

RCT-18 is a novel recombinant fusion protein that blocks the activity of a B-lymphocyte stimulator and a proliferation-inducing ligand. This was a randomized, single-blind, and placebo-controlled phase 1 study in 12 patients with systemic lupus erythematosus. Eligible patients were randomized 3:1 to receive multiple subcutaneous doses of RCT-18 for 4 weeks (180 mg, once weekly) or placebo and monitored over an 84-day observation period for pharmacokinetics, pharmacodynamics, immunogenicity, safety, and clinical activity. After multiple-dose RCT-18, the maximal serum concentration (Cmax ) of total and free RCT-18 was reached within 1 to 2 days. Mean elimination half-life for total RCT-18 and free RCT-18 was 11.4 to 26.4 days and 2.4 to 26.5 days, respectively. Slight accumulation was found after multiple subcutaneous administrations. The average accumulation ratios of AUC and Cmax after the fourth administration of RCT-18 were 2.0 and 1.7 for total RCT-18, and 1.8 and 1.6 for free RCT-18. The formation and elimination of BLyS-RCT-18 complex were much slower, with a time to Cmax of 14 to 46 days. Pharmacokinetic characteristics of RCT-18 in SLE patients were similar to those in patients with rheumatoid arthritis. No positive reaction was detected in the immunogenicity assessments. RCT-18 was biologically active, according to serum immunoglobulin and B-cell levels. Treatment-related IgM and IgA reduction was found during this study. CD19(+) , IgD(+) , and CD27(+) B-cell counts were increased after administration and decreased subsequently. SLE patients treated with RCT-18 were more prone to infections, including moderate and severe infections. Lower dosages of RCT-18 should be considered in further clinical development.

The Correlation Between Non-Hodgkin Lymphoma and Expression Levels of B-Cell Activating Factor and Its Receptors.

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 ß2M 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 ß2M 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.

TACI expression and signaling in chronic lymphocytic leukemia.

TACI is a membrane receptor of BAFF and APRIL, contributing to the differentiation and survival of normal B cells. Although malignant B cells are also subjected on TACI signaling, there is a remarkable intradisease and interindividual variability of TACI expression in B-cell malignancies. The aim of our study was to explore the possible role of TACI signaling in the biology of chronic lymphocytic leukemia (CLL), including its phenotypic and clinical characteristics and prognosis. Ninety-four patients and 19 healthy controls were studied. CLL patients exhibited variable TACI expression, with the majority of cases displaying low to undetectable TACI, along with low to undetectable BAFF and increased APRIL serum levels compared to healthy controls. CLL cells with high TACI expression displayed a better survival capacity in vitro, when cultured with BAFF and/or APRIL. Moreover, TACI expression was positively correlated with the presence of monoclonal gammopathy and inversely with CD11c expression. Therefore, our study provides further evidence for the contribution of BAFF/APRIL signaling to CLL biology, suggesting also that TACI detection might be useful in the selection of patients for novel targeting therapeutic approaches.

Serum soluble TACI, a BLyS receptor, is a powerful prognostic marker of outcome in chronic lymphocytic leukemia.

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 = 0.0003 and 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.

Expression of TNF-α, APRIL and BCMA in Behcet's disease.

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 (r 0.68, 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.

BAFF and TACI gene expression are increased in patients with untreated very early rheumatoid arthritis.

OBJECTIVE: B cells play important roles in rheumatoid arthritis (RA). Given the beneficial effect of B cell depletion therapy in RA as well as the observed alterations in B cell subpopulations in this disease, we evaluated whether changes in the expression of genes related to B cell survival and activation were already present in patients with untreated very early RA (VERA; < 6 weeks of disease duration). METHODS: The expression of a group of B cell-related activation and survival genes was quantified in peripheral blood mononuclear cells from patients with VERA by real-time PCR and compared with untreated early RA (< 1 year), established treated RA, and other untreated early arthritis conditions. Serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) was quantified by ELISA. RESULTS: BAFF gene expression and serum levels were highest in patients with VERA. The expression of BAFF receptor (BAFF-R) increased with disease progression, while transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) was elevated since the first weeks of RA onset. Paired box 5 gene expression was also increased at all RA stages. Chemokine (C-X-C motif) receptor 5 was elevated only in established RA. No differences were observed in B cell maturation antigen, activation-induced cytidine deaminase, B lymphocyte-induced maturation protein, and B cell lymphoma 2 expression. CONCLUSION: Disturbances in the expression of B cell-related activation and survival genes, particularly BAFF and TACI, occur from the onset of RA and precede changes in BAFF-R. These alterations can lead to the development of autoreactive B cells from the first weeks of RA onset.

High serum levels of BAFF, APRIL, and TACI in common variable immunodeficiency.

Common variable immunodeficiency (CVID) is characterized by low levels of immune globulins and lack of antibody. Mutations in transmembrane activator and calcium-modulating cyclophilin ligand (TACI), are found in 8-10%, associated with autoimmunity and splenomegaly. Some patients with mutations had increased serum levels of TACI. Because of this, and the prevalence of autoimmunity, splenomegaly, and lymphadenopathy, we quantitated levels of TACI ligands, a proliferation inducing ligand (APRIL) and B cell activating factor (BAFF) and TACI in serum of 77 patients. CVID subjects had markedly increased serum levels of BAFF (p<0.0001), APRIL (p<0.0001), and TACI (p=0.001) but there was no relationship between levels and autoimmunity, lymphadenopathy, splenomegaly, B cell numbers, or mutations in TACI. Peripheral blood mononuclear cells of CVID subjects had increased levels of BAFF mRNA. We conclude that increased constitutive production and/or underlying immuno-regulatory or inflammatory conditions lead to enhanced release of ligands; however, the biological result remains unclear.