BAFF system expression in double negative 2, activated naïve and activated memory B cells in systemic lupus erythematosus.

Introduction: B cell activating factor (BAFF) has an important role in normal B cell development. The aberrant expression of BAFF is related with the autoimmune diseases development like Systemic Lupus Erythematosus (SLE) for promoting self-reactive B cells survival. BAFF functions are exerted through its receptors BAFF-R (BR3), transmembrane activator calcium modulator and cyclophilin ligand interactor (TACI) and B cell maturation antigen (BCMA) that are reported to have differential expression on B cells in SLE. Recently, atypical B cells that express CD11c have been associated with SLE because they are prone to develop into antibody-secreting cells, however the relationship with BAFF remains unclear. This study aims to analyze the BAFF system expression on CXCR5- CD11c+ atypical B cell subsets double negative 2 (DN2), activated naïve (aNAV), switched memory (SWM) and unswitched memory (USM) B cells. Methods: Forty-five SLE patients and 15 healthy subjects (HS) were included. Flow cytometry was used to evaluate the expression of the receptors in the B cell subpopulations. Enzyme-linked immunosorbent assay (ELISA) was performed to quantify the soluble levels of BAFF (sBAFF) and IL-21. Results: We found increased frequency of CXCR5- CD11c+ atypical B cell subpopulations DN2, aNAV, SWM and USM B cells in SLE patients compared to HS. SLE patients had increased expression of membrane BAFF (mBAFF) and BCMA receptor in classic B cell subsets (DN, NAV, SWM and USM). Also, the CXCR5+ CD11c- DN1, resting naïve (rNAV), SWM and USM B cell subsets showed higher mBAFF expression in SLE. CXCR5- CD11c+ atypical B cell subpopulations DN2, SWM and USM B cells showed strong correlations with the expression of BAFF receptors. The atypical B cells DN2 in SLE showed significant decreased expression of TACI, which correlated with higher IL-21 levels. Also, lower expression of TACI in atypical B cell DN2 was associated with high disease activity. Discussion: These results suggest a participation of the BAFF system in CXCR5- CD11c+ atypical B cell subsets in SLE patients. Decreased TACI expression on atypical B cells DN2 correlated with high disease activity in SLE patients supporting the immunoregulatory role of TACI in autoimmunity.

BAFFR expression in circulating T follicular helper (CD4+CXCR5+PD-1+) and T peripheral helper (CD4+CXCR5-PD-1+) cells in systemic lupus erythematosus.

BACKGROUND: Circulating T follicular helper (cTfh) and T peripheral helper (Tph) subpopulations are shown to be higher in systemic lupus erythematosus (SLE) patients and have been involved in promoting extrafollicular B cell responses. However, a possible association with the B cell activating factor (BAFF), a cytokine mainly related to B cell responses and disease activity in SLE, has not been investigated. Therefore, this study aimed to evaluate the association of cTfh and Tph subpopulations with the BAFF system expression and clinical activity in SLE patients. METHODS: This study included 43 SLE patients and 12 healthy subjects (HS). The identification of cTfh (CD4+CXCR5+PD-1+), Tph (CD4+CXCR5-PD-1+) cells, expression of membrane-bound BAFF (mBAFF), BAFFR, TACI, BCMA, and intracellular IL-21 was performed by flow cytometry. Serum levels of IL-21, CXCL13, and BAFF were analyzed using ELISA. The SLEDAI-2K score was used to evaluate disease activity in SLE patients. RESULTS: Compared with HS, SLE patients showed a significantly increased percentage of cTfh and Tph cells, higher in patients with clearly active disease. SLE patients had markedly higher IL-21-producing cTfh and Tph cells than HS. Both subpopulations were positively correlated with the disease activity in SLE patients. Tph cells were negatively correlated with CD19+CXCR5+ B cells and positively correlated with CD19+CXCR5- B cells. A low expression of mBAFF and their receptors TACI and BCMA was found on cTfh and Tph cells in SLE patients and HS. However, SLE patients with clearly active disease showed decreased expression of BAFFR on cTfh and Tph subpopulations than patients with mildly active/nonactive disease. Serum IL-21, CXCL13, and BAFF levels were higher in SLE patients than in HS. Levels of CXCL13 were correlated with disease activity. Non-significant correlations were observed among T cell subpopulations and IL-21, CXCL13, and BAFF levels. CONCLUSIONS: This study emphasizes the importance of cTfh and Tph cells in SLE pathogenesis. Besides the importance of IL-21, our results suggest that BAFFR could play a role in cTfh and Tph subpopulations in the autoimmunity context.

Analysis of TNFSF13B polymorphisms and BAFF expression in rheumatoid arthritis and primary Sjögren's syndrome patients.

BACKGROUND: The increased expression of B cell-activating factor (BAFF) has been linked to autoantibody production in autoimmune diseases (ADs). The aim of this study was to investigate the association among TNFSF13B gene (OMIM: 603969) single nucleotide polymorphisms (SNPs), TNFSF13B mRNA, and soluble BAFF (sBAFF) expression in patients with rheumatoid arthritis (RA) and primary Sjögren's syndrome (pSS). The diagnostic value of sBAFF also was evaluated by the area under the curve (AUC) of receiver operating characteristic or receptor (ROC) curves. METHODS: Genotypes of the TNFSF13B rs9514827 (-2841 T > C), rs1041569 (-2701 A > T) and rs9514828 (-871 C > T) SNPs were determined by PCR-RFLP assay. TNFSF13B mRNA and sBAFF expression were performed by RT-qPCR and ELISA, respectively. The study included 320 RA patients, 101 pSS patients, and 309 healthy subjects (HS). RESULTS: The rs9514828 T allele and the TAT haplotype were associated with an increased risk to develop RA. In both ADs, the TNFSF13B mRNA levels were increased in comparison with HS. The rs9514828 (-871 C > T) polymorphism was associated with increased gene expression in RA patients. Also, sBAFF levels were higher in both ADs, however pSS patients showed the highest sBAFF levels. sBAFF showed higher diagnostic performance for pSS with an AUC of 0.968, with a similar accuracy of anti-SSA/Ro antibody diagnosis (AUC = 0.974). CONCLUSIONS: Our findings demonstrate that the TNFSF13B rs9514828 (-871 C > T) polymorphism is a risk factor for RA in the western Mexican population. sBAFF levels may be a potential diagnosis biomarker in pSS.

Prone positioning in non-intubated patients with COVID-19 associated acute respiratory failure, the PRO-CARF trial: A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: To assess the effect of prone positioning therapy on intubation rate in awake patients with COVID-19 and acute respiratory failure. TRIAL DESIGN: This is a two-center parallel group, superiority, randomized (1:1 allocation ratio) controlled trial. PARTICIPANTS: All patients admitted to the Hospital Civil de Guadalajara and Hospital General de Occidente in Mexico for COVID-19 associated acute respiratory failure and in need of supplementary oxygen through high-flow nasal cannula are screened for eligibility. INCLUSION CRITERIA: all adult patients admitted to the COVID-19 unit who test positive for COVID-19 by PCR-test and in need for oxygen are eligible for inclusion. Randomization starts upon identification of requirement of a fraction of inspired oxygen ≥30% for an oxygen capillary saturation of ≥90% Exclusion criteria: less than 18 years-old, pregnancy, patients with immediate need of invasive mechanical ventilation (altered mental status, fatigue), vasopressor requirement to maintain median arterial pressure >65 mmHg, contraindications for prone positioning therapy (recent abdominal or thoracic surgery or trauma, facial, pelvic or spine fracture, untreated pneumothorax, do-not-resuscitate or do-not-intubate order, refusal or inability of the patient to enroll in the study. INTERVENTION AND COMPARATOR: Patients of the intervention group will be asked to remain in a prone position throughout the day as long as possible, with breaks according to tolerance. Pillows will be offered for maximizing comfort at chest, pelvis and knees. Monitoring of vital signs will not be suspended. Inspired fraction of oxygen will be titrated to maintain a capillary saturation of 92%-95%. For patients in the control group, prone positioning will be allowed as a rescue therapy. Staff intensivists will monitor the patient's status in both groups on a 24/7 basis. All other treatment will be unchanged and left to the attending physicians. MAIN OUTCOMES: Endotracheal intubation rate for mechanical ventilation at 28 days. RANDOMISATION: Patients will be randomly allocated to either prone positioning or control group at 1:1 ratio. Such randomization will be computer generated and stratified by center with permuted blocks and length of 4. BLINDING (MASKING): Due to logistical reasons, only principal investigators and the data analyst will be blinded to group assignment. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): With an intubation rate of 60% according to recent reports from some American centers, and assuming a decrease to 40% to be clinically relevant, we calculated a total of 96 patients per group, for a beta error of 0.2, and alpha of 0.5. Therefore, we plan to recruit 200 patients, accounting for minimal losses to follow up, with 100 non-intubated patients in the prone position group and a 100 in the control group. TRIAL STATUS: The local registration number is 048-20, with the protocol version number 2.0. The date of approval is 3rd May 2020. Recruitment started on 3rd May and is expected to end in December 2020. TRIAL REGISTRATION: The protocol was retrospectively registered under the title: "Prone Positioning in Non-intubated Patients With COVID-19 Associated Acute Respiratory Failure. The PRO-CARF trial" in ClinicalTrials.gov with the registration number: NCT04477655. Registered on 20 July 2020. FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol. The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (Additional file 2).

Analysis of the receptor BCMA as a biomarker in systemic lupus erythematosus patients.

B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) play central roles in B cell development and maturation. Soluble forms of their receptors can be generated by proteolytic cleavage; however, their physiological and clinical roles are unknown. This study aimed to assess the relationships between the receptor soluble B cell maturation antigen (sBCMA) and clinical variables in systemic lupus erythematosus (SLE) patients. Serum cytokine concentrations were measured by ELISA for 129 SLE patients and 34 healthy controls (HCs), and the expression of the receptor BCMA was evaluated on B and plasma cells from 40 subjects. SLE patients showed aberrant expression of the receptor BCMA on B and plasma cells. Soluble levels of the receptor sBCMA and its ligands sAPRIL and sBAFF were increased in SLE patients compared with HCs. Additionally, sBCMA (rs = 0.6177) and sAPRIL (rs = 0.4952) correlated strongly with disease activity. Active SLE patients who achieved low disease activity showed decreased sBCMA (53.30 vs 35.30 ng/mL; p < 0.05) and sBAFF (4.48 vs 2.27 ng/mL; p < 0.05) serum levels after treatment, while sAPRIL expression remained unchanged. At a cutoff value of 22.40 ng/mL, sAPRIL showed high sensitivity (96.12%) and specificity (94.12%) for discrimination between HCs and SLE patients, while sBAFF showed lower sensitivity (82.2%) but higher specificity (94.1%) at a cutoff of 1.195 ng/mL. Relatively high levels of sAPRIL and sBCMA clustered active SLE patients. The receptor sBCMA could be a potential biomarker of disease activity in SLE.

Association of soluble CD40 levels with -1 C > T CD40 polymorphism and chronic kidney disease in systemic lupus erythematosus.

BACKGROUND: CD40 is a transmembrane protein mainly expressed on the antigen-presenting cells surface. CD40 plays a crucial role in immunoglobulin class switching and antibodies production. Genetic polymorphisms in the CD40 gene have been associated with increased risk of systemic lupus erythematosus (SLE) in several populations. This study aimed to evaluate the association of CD40 polymorphisms (-1 C > T, rs1883832 and 6,048 G > T, rs4810485) with SLE susceptibility, as well as with mRNA expression and soluble CD40 (sCD40) levels. METHODS: The study included 293 patients with SLE and 294 control subjects (CS). Genotyping was performed by PCR-RFLP method. CD40 mRNA expression was determined by quantitative real-time PCR, and ELISA quantified sCD40 levels. RESULTS: The CD40 polymorphisms -1 C > T and 6,048 G > T were associated with SLE susceptibility. There was no difference between CD40 mRNA expression and CD40 polymorphisms. The sCD40 levels were lower in SLE patients with TT haplotype, whereas higher sCD40 levels were associated with damage and impaired renal function according to SLICC and KDIGO. The sCD40 levels were negatively correlated with eGFR. CONCLUSION: The CD40 gene polymorphisms increase the risk of SLE in the western Mexican population. The sCD40 levels are associated with -1 C > T polymorphism and chronic kidney disease.

BAFF-R and TACI expression on CD3+ T cells: Interplay among BAFF, APRIL and T helper cytokines profile in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is the prototype of systemic autoimmune disease, characterized by loss of immune tolerance against self-antigens where autoantibody production is the hallmark of disease. B-cell-activating factor (BAFF) and A proliferation-inducing ligand (APRIL) are cytokines that promote autoreactive cell survival, immunoglobulin-class switching and autoantibody responses in human and mouse SLE models. BAFF and APRIL exert their functions through interactions with their receptors BAFF-R and TACI that are differentially expressed in B lymphocyte subsets, monocytes, dendritic cells and T lymphocytes. BAFF stimulation favors T lymphocyte activation and cytokine production through BAFF-R, which could contribute to the Th1, Th17 and/or Th2 response dysregulation observed in SLE patients. OBJECTIVE: To evaluate the expression of the cytokines BAFF and APRIL and their association with the receptors BAFF-R and TACI on CD3+ T cells and to evaluate Th1/Th2/Th17 cytokine profile in patients with SLE. METHODS: Fifteen healthy controls (HC) and 36 SLE patients were included, and their demographic and clinical data were assessed. The disease activity index (Mex-SLEDAI) and damage index (SLICC) were applied to the SLE patients. BAFF-R and TACI expression on CD3+ T cells were evaluated by flow cytometry. Serum BAFF and APRIL concentrations were measured by enzyme-linked immunosorbent assays (ELISA). Cytokine levels of Th1 (IL-12, IL-2, IFN-γ, TNF-α), Th2 (IL-4, IL-6, IL-10, IL-13) and Th17 (IL-1ß e IL-17) were quantified with a multiplex assay (MAGPIX). Statistical analysis was performed using PASW Statistics v.20 and GraphPad Prism v.6 software. RESULTS: No differences in BAFF-R or TACI expression on the CD3+ T cells of SLE and HC were observed. BAFF-R expression correlates inversely with disease activity (r = -0.538, p < 0.01), while TACI correlates with disease activity (r = 0.530, p < 0.05). Serum BAFF and APRIL levels were high in SLE patients and correlated with the disease activity index Mex-SLEDAI (r = 0.621, p < 0.01 and r = 0.416, p < 0.05). SLE patients were found to have significantly higher levels of IL-12, IFN-γ, TNF-α, IL-6, IL-10, IL-13, IL-1ß and IL-17 compared to HC (p < 0.05). Cytokines IL-17 (r = 0.526) and TNF-α (r = 0.410) correlate with disease activity (p < 0.05), while APRIL (r = 0.477), IL-10 (r = 0.426) and IFN-γ (r = 0.440) levels were associated with organ damage (p < 0.01). Serum BAFF expression levels correlate with IL-4 (r = 0.424; p < 0.05), IL-6 (r = 0.420; p < 0.05) and IL-10 (r = 0.459; p < 0.01), whereas APRIL levels correlate with IL-2 (r = 0.666; p < 0.01), IL-12 (r = 0.611; p < 0.01) and TNF-α (r = 0.471; p < 0.05) cytokines. A subgroup of SLE patients with high serum BAFF levels (>2 ng/mL) also showed increased APRIL, IL-2, IL-6 and IL-10 levels (p < 0.05). Finally, BAFF, IL-4 and TNF-α serum levels were associated with high titers of antinuclear antibodies. CONCLUSIONS: The study demonstrates an imbalance in the Th1/Th2 cytokine profile, with increased proinflammatory cytokines, as well as BAFF and APRIL serum levels. Associations of BAFF with Th2 profile cytokines and disease activity, as well as APRIL with Th1 profile cytokines and organ damage, suggest that BAFF and APRIL generated in the autoimmunity context could through still unknown mechanisms, modulate the microenvironment, and perpetuate the inflammatory response, autoantibody production and organ damage observed in SLE patients.