To analyse B cell activating factor (BAFF) receptor (BAFF‐R) expression on peripheral lymphocytes from patients with primary Sjögren's syndrome (pSS) and systemic lupus erythematosus (SLE).
Patients and methods
Peripheral blood mononuclear cells from 20 patients with pSS, 19 patients with SLE and 15 controls were examined by flow cytometry to investigate BAFF‐R mean fluorescence intensity (MFI) on lymphocytes. BAFF‐R mRNA level from isolated blood B cells of nine patients with pSS and eight controls was assessed by real‐time quantitative reverse transcription‐PCR. BAFF serum level was determined by ELISA.
In all subjects, BAFF‐R was expressed on all naïve CD27− and memory CD27+ B‐cells and was present on <0.5% of T cells. The expression of BAFF‐R on B cells was significantly decreased in patients with pSS as compared with controls (MFI = 7.8 vs 10.6, p = 0.001), and was intermediate in patients with SLE (MFI = 9.5). Serum BAFF level was inversely correlated with BAFF‐R MFI (p = 0.007), but not because of competition between endogenous BAFF (at observed concentrations in patients) and the monoclonal antibody (11C1) detecting BAFF‐R. BAFF‐R mRNA levels did not differ between patients with pSS and controls (p = 0.48). BAFF‐R MFI decreased after overnight culture with recombinant human BAFF (from 32.5 to 25.4, p = 0.03). Contrary to the serum BAFF level, BAFF‐R expression was correlated with extraglandular involvement in pSS and SLE Disease Activity Index.
BAFF‐R expression is reduced on peripheral B cells of patients with pSS and SLE. This down‐regulation occurs through a post‐transcriptional mechanism and could be the consequence of chronic increase in BAFF. BAFF‐R levels on B cells could be a novel activity biomarker in autoimmune diseases.
Glucocorticoid-induced tumor necrosis factor receptor family-related protein (GITR) is a type I transmembrane protein belonging to the TNFR superfamily. After activated by its ligand GITRL, GITR could influence the activity of effector and regulatory T cells, participating in the development of several autoimmune and inflammatory diseases included rheumatoid arthritis and autoimmune thyroid disease. We previously reported that serum GITRL levels are increased in systemic lupus erythematosus (SLE) patients compared with healthy controls (HC). Here, we tested serum soluble GITR (sGITR) and GITRL levels in 41 primary Sjögren's syndrome (pSS) patients and 29 HC by ELISA and correlated sGITR and GITRL levels with clinical and laboratory variables. GITR and GITRL expression in labial salivary glands was detected by immunohistochemistry. pSS patients had significantly increased serum levels of sGITR and GITRL compared with controls (GITR: 5.66 ± 3.56 ng/mL versus 0.50 ± 0.31 ng/mL; P < 0.0001; GITRL: 6.17 ± 7.10 ng/mL versus 0.36 ± 0.28 ng/mL; P < 0.0001). Serum sGITR and GITRL levels were positively correlated with IgG (GITRL: r = 0.6084, P < 0.0001; sGITR: r = 0.6820, P < 0.0001) and ESR (GITRL: r = 0.8315, P < 0.0001; sGITR: r = 0.7448, P < 0.0001). Moreover, GITR and GITRL are readily detected in the lymphocytic foci and periductal areas of the LSGs. In contrast, the LSGs of HC subjects did not express GITR or GITRL. Our findings indicate the possible involvement of GITR-GITRL pathway in the pathogenesis of pSS. Further studies may facilitate the development of targeting this molecule pathway for the treatment of pSS.
Primary Sjögren's syndrome (pSS) shares clinical features and pathogenetic mechanisms with systemic lupus erythematosus (SLE). SLE is associated with an increased thromboembolic risk; however, it is unclear whether pSS patients are susceptible to thromboembolic diseases. In this study, we examined ex vivo blood clot formation (clot strength, rates of clot formation and lysis) in pSS using thromboelastography (TEG) and platelet aggregation to common agonists using multiple electrode aggregometry (MEA). We also investigated the relationship between TEG/MEA parameters and clinical/laboratory features of pSS.
Secondary care, single centre.
34 pSS patients, 11 SLE patients and 13 healthy volunteers (all women) entered and completed the study.
Primary and secondary outcome measures
Primary outcomes: TEG and MEA parameters between three subject groups. Secondary outcomes: The relationships between TEG/MEA and clinical/laboratory parameters analysed using bivariate correlation analysis with corrections for multiple testing.
All TEG and MEA parameters were similar for the three subject groups. After corrections for multiple testing, interleukin (IL)-1α and Macrophage inflammatory proteins (MIP)-1α remain correlated inversely with clot strength (r=−0.686, p=0.024 and r=−0.730, p=0.012, respectively) and overall coagulability (r=−0.640, p=0.048 and r=−0.648, p=0.048). Stepwise regression analysis revealed that several cytokines such as MIP-1α, IL-17a, IL-1α and Interferon (IFN)-γ may be key predictors of clot strength and overall coagulability in pSS.
Clot kinetics and platelet receptor function are normal in pSS. Several cytokines correlate with clot strength and overall coagulability in pSS.
B cell activation may result in an increased secretion of immunoglobulin free light chains (FLCs) in autoimmune diseases.
To analyse serum FLC levels in patients with rheumatoid arthritis and in those with primary Sjögren's syndrome (pSS).
Patients and methods
Blood samples were collected from 80 healthy blood donors, 50 patients with rheumatoid arthritis and 139 patients with pSS. Serum FLC level was measured using a new quantitative immunoassay.
Mean (standard error (SE)) serum κ and λ FLC levels were significantly higher in patients with rheumatoid arthritis and in those with pSS than in controls (κ : 18.9 (1.1) and 16.3 (1.4) v 10.5 (0.4) mg/l, p<0.001 and p = 0.001, respectively; λ: 16.7 (1.2) and 19.3 (1.5) v 11.6 (0.6) mg/l, p<0.001 for both). 18 (36%) patients with rheumatoid arthritis and 31 (22.3%) patients with pSS had abnormal serum FLC levels (increased κ or λ levels and abnormal ratio of κ:λ). Serum κ and λ levels were correlated with other B cell activation markers in both diseases. FLC levels increased with disease activity, because, unlike total gammaglobulin and immunoglobulin G levels, they were significantly correlated with Disease Activity Score 28 in patients with rheumatoid arthritis (p = 0.004 for κ, p = 0.05 for λ) and with extraglandular involvement in pSS (p = 0.01 for κ, p = 0.04 for λ).
FLC levels are increased and correlate with disease activity in patients with rheumatoid arthritis and in those with pSS, two diseases in which increased risk of lymphoma could result from persistent B cell activation and disease activity. Further studies are required to determine whether FLC assessment could represent a relevant biomarker for response to treatment (especially B cell depletion) and for the risk of lymphoma in autoimmune diseases.
OBJECTIVES--To assess serial activation of T-cell subsets in relation to auto-antibody production and the occurrence of disease exacerbations in patients with systemic lupus erythematosus (SLE). METHODS--To study the possible role of T-cells in the pathophysiology of the disease, 16 consecutive exacerbations were prospectively studied in a cohort of patients with SLE, and serial plasma levels of sIL-2R, sCD4, and sCD8 preceding and during these exacerbations were determined. Levels of these molecules were related to total IgM and IgG, and anti-dsDNA. RESULTS--During major disease exacerbations (n = 6), levels of sIL-2R increased significantly (p < 0.001). Levels of sCD4 were predominantly in the normal range, whereas levels of sCD8 were frequently increased. No change in levels of both molecules could be detected in the period before the exacerbation. During minor exacerbations (n = 10), levels of sIL-2R remained stable. Levels of sCD4, however, tended to drop, whereas levels of sCD8 tended to rise. No correlations were found between sIL-2R, sCD4 or sCD8 on the one hand, and total IgM, IgG, or anti-dsDNA on the other. CONCLUSIONS--Levels of sIL-2R are increased, and rise before major exacerbations of SLE. Levels of sCD4 and sCD8, however, are not related to levels of sIL-2R, and do not reflect B-cell activation, nor disease activity during exacerbations of SLE. Thus for the clinical follow up of SLE measurement of levels of sCD4 or sCD8 is of limited value.
To evaluate the relevance of the blood B-cell subset profile for the diagnosis of Sjögren syndrome.
The distribution of mature blood B cells from Bm1 through Bm5 was determined in 161 patients, of whom 25 fulfilled the American–European Consensus Group criteria for primary SS (pSS), and 136 served as disease controls.
The percentage of Bm2 and Bm2′ cells was increased in the patients with pSS compared with 54 patients with rheumatoid arthritis (RA) and 18 with systemic lupus erythematosus (SLE) (p<0.001 for the two comparisons). In contrast, those of early Bm5 (eBm5) and Bm5 were decreased in patients with pSS, compared with patients with RA and with SLE (p<0.001 for the two comparisons). The receiver operating characteristic curves allowed for an optimising cut-off value of Bm2+Bm2′ cells at 71.1% for 88.0% sensitivity and 83.1% specificity, that of eBm5+Bm5 cells at ⩽13.5% for 84.0% sensitivity and 83.1% specificity, and, consequently, that of Bm2+Bm2′/eBm5+Bm5 at ⩾5 for 88.0% sensitivity and 84.6% specificity.
Given its presentation as a signature for pSS, relative to RA and SLE, such a distribution of B-cell subsets might provide a useful diagnostic tool.
Autoantibodies to the catalytic domain of v-raf murine sarcoma viral oncogene homologue B1 (BRAF) have been recently identified as a new family of autoantibodies involved in rheumatoid arthritis (RA). The objective of this study was to determine antibody responses to the catalytic domain of BRAF in RA and other autoimmune diseases. The association between RA-related clinical indices and these antibodies was also assessed.
The presence of autoantibodies to the catalytic domain of BRAF (anti-BRAF) or to peptide P25 (amino acids 656–675 of the catalytic domain of BRAF; anti-P25) was determined in serum samples from patients with RA, primary Sjögren's syndrome (pSS), systemic lupus erythematosus (SLE), and healthy controls by using indirect enzyme-linked immunosorbent assays (ELISAs) based on the recombinant catalytic domain of BRAF or a synthesized peptide, respectively. Associations of anti-BRAF or anti-P25 with disease variables of RA patients were also evaluated. Our results show that the BRAF-specific antibodies anti-BRAF and anti-P25 are equally present in RA, pSS, and SLE patients. However, the erythrocyte sedimentation rate (ESR) used to detect inflammation was significantly different between patients with and without BRAF-specific antibodies. The anti-BRAF-positive patients were found to have prolonged disease, and active disease occurred more frequently in anti-P25-positive patients than in anti-P25-negative patients. A weak but significant correlation between anti-P25 levels and ESRs was observed (r = 0.319, p = 0.004).
The antibody response against the catalytic domain of BRAF is not specific for RA, but the higher titers of BRAF-specific antibodies may be associated with increased inflammation in RA.
Gross cystic disease fluid protein-15(GCDFP-15)/prolactin-inducible protein (PIP) is a secretory acinar glycoprotein of 14 KDa which we have recently described as significantly lower in salivary samples of patients with primary Sjögren’s syndrome (pSS) in comparison to healthy volunteers by proteomic analysis.
Aims of the study
(1) to validate our previous data on the decrease of GCDFP-15/PIP protein in a larger number of subjects with pSS (2) to integrate the proteomic results with complementary immunoassays in order better clarify the pathophysiological relevance of GCDFP-15/PIP in pSS exocrinopathy (3) to assess both the glandular expression of the GCDFP-15/PIP and the levels of glandular GCDFP-15/PIP mRNA in the patients’ minor salivary gland (MSG) biopsies in order to verify whether the observed reduction of GCDFP-15/PIP in saliva may be related to a decrease in the protein production.
Patients and methods
A total of 123 salivary samples from patients affected by pSS, no-SS sicca syndrome and sex- age-matched healthy volunteers were analyzed by different proteomic techniques (SELDI-TOF-MS, 2DE, MALDI-TOF-MS). The expression of GCDFP-15/PIP was then validated by western blot analysis. Real Time PCR and immunohistochemistry for GCDFP-15/PIP in the minor salivary glands (MSG) biopsies were then carried out.
By using complementary proteomic analysis we found that a putative peak of 16547 m/z was among the best independent biomarkers for pSS able to discriminate between patients and healthy controls with a sensitivity of 96 % and a specificity of 70%, with a global cross validated error of 29%. We identified the peak as the GCDFP-15/PIP protein and verified that the intensity of GCDFP-15/PIP was significantly lower in pSS patients when compared to both no-SS sicca subjects and healthy controls (p<0.0001). GCDFP-15/PIP expression also correlated with both the salivary flow rate (r=0.312, p=0.023) and MSG biopsies focus score (r=−0.377, p=0.04). Finally, immunohistochemistry confirmed that GCDFP-15/PIP staining was faint in mucus acini and Real Time PCR showed that GCDFP-15/PIP mRNA was significantly lower in pSS patients when compared to both no-SS sicca subjects and healthy controls (p=0.023) thus supporting the hypothesis that the observed reduction of GCDFP-15/PIP in pSS saliva may be related to a decrease in the protein production.
In this study by different complementary-omic techniques we confirmed the potential role of GCDFP-15/PIP as a novel biomarker for pSS. This finding might also be functionally important as GCDFP-15/PIP has previously been shown to bind to Aquaporin 5 (AQP5), a salivary gland water channel, critical to saliva formation that is known to be downregulated in pSS. It is likely that exploring the GCDFP-15/PIP/AQP5 axis will help better understand the mechanism of salivary gland dysfunction in pSS.
Sjören’s syndrome; GCDFP-15/PIP; Autoimmune disease
Anti-phospholipid (aPL) antibodies are important contributors to development of thrombosis in patients with the autoimmune rheumatic disease systemic lupus erythematosus (SLE). The underlying mechanism of aPL antibody-mediated thrombosis is not fully understood but existing data suggest that platelets and the complement system are key components. Complement activation on platelets is seen in SLE patients, especially in patients with aPL antibodies, and has been related to venous thrombosis and stroke. The aim of this study was to investigate if aPL antibodies could support classical pathway activation on platelets in vitro as well as in SLE patients. Furthermore, we investigated if complement deposition on platelets was associated with vascular events, either arterial or venous, when the data had been adjusted for traditional cardiovascular risk factors. Finally, we analyzed if platelet complement deposition, both C1q and C4d, was specific for SLE. We found that aPL antibodies supported C4d deposition on platelets in vitro as well as in SLE patients (p = 0.001 and p<0.05, respectively). Complement deposition on platelets was increased in SLE patients when compared with healthy individuals (p<0.0001). However, high levels of C4d deposition and a pronounced C1q deposition were also seen in patients with rheumatoid arthritis and systemic sclerosis. In SLE, C4d deposition on platelets was associated with platelet activation, complement consumption, disease activity and venous (OR = 5.3, p = 0.02), but not arterial, thrombosis, observations which were independent of traditional cardiovascular risk factors. In conclusion, several mechanisms operate in SLE to amplify platelet complement deposition, of which aPL antibodies and platelet activation were identified as important contributors in this investigation. Complement deposition on platelets was identified as a marker of venous, but not arterial thrombosis, in SLE patients independently of traditional risk factors and aPL antibodies. Further studies are needed to elucidate the role of complement deposition on platelets in development of venous thrombosis.
Lung cancer is the leading cause of cancer death worldwide. There is an urgent need for early diagnostic tools and novel therapies in order to increase lung cancer survival. Secretory phospholipase A2 group IIa (sPLA2-IIa) is involved in inflammation, tumorigenesis and metastasis. We were the first to uncover that cancer cells secrete sPLA2-IIa. sPLA2-IIa is overexpressed in almost all specimens of human lung cancers examined and is significantly elevated in the plasma of lung cancer patients. High levels of plasma sPLA2-IIa are significantly associated with advanced stage and decreased overall cancer survival. In this study, we further showed that elevated HER/HER2-PI3K-Akt-NF-κB signaling contributes to sPLA2-IIa overexpression in lung cancer cells. sPLA2-IIa in turn phosphorylates and activates HER2 and HER3 in a time- and dose-dependent manner in lung cancer cells. The structure and sequence-based docking analysis revealed that sPLA2-IIa β hairpin shares structural similarity with the corresponding EGF hairpin. sPLA2-IIa forms an extensive interface with EGFR and brings the two lobes of EGFR into an active conformation. sPLA2-IIa also enhances the NF-κB promoter activity. Anti-sPLA2-IIa antibody, but not the small molecule sPLA2-IIa inhibitor LY315920, significantly inhibits sPLA2-IIa-induced activation of NF-κB promoter. Our findings support the notion that sPLA2-IIa functions as a ligand for the EGFR family of receptors leading to an elevated HER/HER2-elicited signaling. Plasma sPLA2-IIa can potentially serve as lung cancer biomarker and sPLA2-IIa is a potential therapeutic target against lung cancer.
lung cancer; HER/HER2-elicited signaling pathway; secretory phospholipase A2-IIa; ligand; NF-κB
The function of sPLA2 is site dependent. In tissue, sPLA2 regulates eicosanoid production; in the blood, sPLA2 primes neutrophils; and in the intestinal lumen sPLA2 provides innate bactericidal immunity as a defensin-related protein. Since parenteral nutrition (PN) with lack of enteral stimulation primes leukocytes while suppressing intra-luminal mucosal immunity, we hypothesized that 1) PN would diminish luminal sPLA2 activity, but increase sPLA2 activity in small intestinal (SI) tissue and serum and 2) stress would accentuate these changes.
Mice received Chow, Complex Enteral Diet (CED), intragastric PN (IG-PN), or PN in Experiment 1, and Chow, Chow + Stress, PN, and PN + Stress in Experiment 2. Tissue, intestinal luminal fluid, and portal and systemic serum were analyzed for sPLA2 activity. IgA was measured in luminal fluid as a marker of acquired mucosal immunity.
Luminal fluid sPLA2 activity was greatest in Chow and decreased in CED (p=0.0001), IG-PN (p=0.0002), and PN (p=0.0001) with PN lower than CED (p<0.002) or IG-PN (p<0.0001). Compared to Chow, serum sPLA2 activity dropped after CED (p = 0.042), IG-PN (p<0.0001), and PN (p=0.0004). Serum sPLA2 was higher in portal than systemic serum (p=0.04).
PN lowered luminal fluid sPLA2 activity vs Chow (p<0.0001). Stress lowered luminal sPLA2 activity in Chow (p<0.0001), without a change with PN. Following stress, luminal IgA increased in Chow (p=0.0025) but not PN (p=0.18). Serum sPLA2 activity was unchanged after Chow but increased in PN (p<0.03).
Parenteral nutrition with lack of enteral stimulation attenuates sPLA2 activity in intestinal fluid consistent with a suppressed innate mucosal defense. Stress suppresses luminal fluid sPLA2 activity in Chow, but not the IgA response: PN impairs both. Stress significantly elevates serum sPLA2 in PN fed mice consistent with the known increased neutrophil priming with PN. PN reduces innate bactericidal immunity of the gut but up-regulates serum pro-inflammatory products after stress.
secretory phospholipase A2; parenteral nutrition; surgical stress; small intestine; defensins; enteral feeding; innate immunity
Sjögren’s syndrome (SS) is a systemic autoimmune disease with a variety of presenting symptoms which may delay its diagnosis. We previously discovered a number of candidate salivary biomarkers for primary SS (pSS) using both mass spectrometry and expression microarray analysis (Arthritis Rheumatism, 2007;56(11):3588-3600). In this study, we aim to verify these candidate biomarkers in independent patient populations and to evaluate their predictive values for pSS detection.
In total, 34 patients with pSS, 34 patients with systemic lupus erythematosus (SLE) and 34 healthy individuals were enrolled for the validation studies. Salivary protein biomarkers were measured using either Western blotting or ELISA, and the mRNA biomarkers were measured using quantitative polymerase chain reaction (qPCR). Statistical analysis was performed using R2.9.
Three protein biomarkers, cathepsin D, alpha-enolase and beta-2-microglobulin (B2M), and three mRNA biomarkers, myeloid cell nuclear differentiation antigen (MNDA), Guanylate binding protein 2 (GIP2) and low affinity IIIb receptor for the Fc fragment of IgG (FCGR3B), were significantly elevated in patients with pSS compared to both SLE patients and healthy controls. The combination of three protein biomarkers, cathepsin D, alpha-enolase and B2M, yielded a receiver operating characteristic (ROC) value of 0.99 in distinguishing pSS from healthy controls. The combination of protein biomarkers B2M and two mRNA biomarkers, MNDA and GIP2, reached an ROC of 0.95 in discriminating pSS from SLE.
We have successfully verified a panel of protein and mRNA biomarkers that can discriminate pSS from both SLE and healthy controls. If further validated in pSS patients and those with sicca symptoms but no autoimmune disease, these biomarkers may lead to a simple yet highly discriminatory clinical tool for diagnosis of pSS.
OBJECTIVE—Urokinase type plasminogen activator (uPA) catalyses the formation of the proteolytic enzyme plasmin, which is involved in matrix degradation in the processes of tissue remodelling. Because of a surface bound uPA receptor (uPAR), expressed by some cell types (for example, macrophages, malignant cells and inflammatory activated synoviocytes), the action of uPA can be localised and intensified. uPAR seems to have a role in the mechanisms leading to invasive growth of malignant tissue and the rheumatoid pannus. uPAR may become cleaved at its cell surface anchor, thus forming a free soluble receptor (suPAR). suPAR is detectable in low but constant values in plasma of healthy people, while increased concentrations are found in patients with disseminated malignant disease, so that suPAR may be an indicator of invasive growth and tissue remodelling. suPAR concentrations in plasma have not previously been measured in rheumatic patients. A controlled cross sectional measurement was performed of suPAR in plasma of patients with various inflammatory rheumatic disorders with special reference to rheumatoid arthritis (RA).
METHODS—suPAR in plasma was measured by ELISA technique in patients with RA (n=51), reactive arthritis (ReA) (n=23), primary Sjögren's syndrome (PSS) (n=42) and sex and age matched healthy controls (n=53).
RESULTS—In the control group suPAR (median) was 0.91 (range 0.56-1.94) µg/l. Median suPAR value in RA was 1.47 (range 0.65-6.62) µg/l; in ReA 0.68 µg/l (range 0.52-1.48) and in PSS 1.12 µg/l (range 0.76-1.92); p versus controls <0.001 in all patient groups. suPAR values in RA were also significantly increased compared with ReA (p<0.001) and PSS (p=0.004) groups. suPAR in RA was positively correlated to C reactive protein (CRP) (p<0.01) and erythrocyte sedimentation rate (p<0.05) and number of swollen joints (p<0.05). The ReA group had the highest CRP values of all groups, but at the same time the lowest suPAR concentrations in plasma.
CONCLUSIONS—Increased suPAR concentrations were found in plasma in RA, and to a smaller extent also in PSS, but not in ReA. In RA suPAR is related to disease activity. suPAR seems though not merely to be an acute phase reactant like CRP. Increased suPAR values might reflect erosive activity in RA.
OBJECTIVE—Plasma concentrations of soluble CD95 (sCD95) are raised in patients with systemic lupus erythematosus (SLE) before clinical relapses become manifest. Increased sCD95 concentrations may therefore be a familial characteristic that is associated with susceptibility to severe disease. To test this, sCD95 concentrations were measured in healthy first degree relatives of patients with severe and non-severe SLE.
METHODS—Seventy seven first degree relatives of 26 patients with severe, and 72 relatives of 25 patients with non-severe lupus were studied. Controls were 42 first degree relatives of 17 patients with chronic cutaneous lupus erythematosus (CCLE) and 63 partners of the patients with their first degree relatives. Severe lupus was defined as both multi-organ disease and cyclophosphamide treatment, non-severe lupus as neither. Organ damage was assessed with the SLICC-ACR index, disease activity with SLEDAI.
RESULTS—Soluble CD95 concentrations in relatives of patients with severe SLE were similar to those in relatives of patients with non-severe SLE, relatives of patients with CCLE, and controls (median (interquartile range) sCD95 concentration 0.59 (0.52-0.66) v 0.57 (0.50-0.63), 0.56 (0.51-0.71), and 0.55 (0.49-0.61) ng/ml, p=0.25, p=0.94, and p=0.17, respectively). Increased concentrations of sCD95, however, were found in patients with severe SLE compared with those in patients with non-severe SLE, patients with CCLE, and control relatives (0.77 (0.70-0.97) v 0.60 (0.54-0.67), 0.57 (0.54-0.71), and 0.57 (0.52-0.63) ng/ml, respectively, p<0.001). Concentrations of sCD95 were significantly correlated with damage index scores (rs=0.47, p<0.01). Basic and clinical characteristics of patients with SLE, including SLEDAI scores, could not explain these observations.
CONCLUSION—Soluble CD95 concentrations are associated with severity of the disease and not with susceptibility for severe SLE.
Among several different types of phospholipase A2 (PLA2), cytosolic PLA2 (cPLA2)α and group IIA (IIA) secretory PLA2 (sPLA2) have been studied intensively. To determine the discrete roles of cPLA2α in platelets, we generated two sets of genetically engineered mice (cPLA2α−/−/sPLA2-IIA−/− and cPLA2α−/−/sPLA2-IIA+/+) and compared their platelet function with their respective wild-type C57BL/6J mice (cPLA2α+/+/sPLA2-IIA−/−) and C3H/HeN (cPLA2α+/+/sPLA2-IIA+/+). We found that cPLA2α is needed for the production of the vast majority of thromboxane (TX)A2 with collagen stimulation of platelets. In cPLA2α-deficient mice, however, platelet aggregation in vitro is only fractionally decreased because small amounts of TX produced by redundant phospholipase enzymes sufficiently preserve aggregation. In comparison, adenosine triphosphate activation of platelets appears wholly independent of cPLA2α and sPLA2-IIA for aggregation or the production of TX, indicating that these phospholipases are specifically linked to collagen receptors. However, the lack of high levels of TX limiting vasoconstriction explains the in vivo effects seen: increased bleeding times and protection from thromboembolism. Thus, cPLA2α plays a discrete role in the collagen-stimulated production of TX and its inhibition has a therapeutic potential against thromboembolism, with potentially limited bleeding expected.
knockout mice; platelet aggregation; bleeding; thromboembolism; thromboxane
B cell-activating factor (BAFF) has a key role in promoting B-lymphocyte activation and survival in primary Sjögren's syndrome (pSS). The cellular origin of BAFF overexpression in salivary glands of patients with pSS is not fully known. We investigated whether salivary gland epithelial cells (SGECs), the main targets of autoimmunity in pSS, could produce and express BAFF. We used quantitative RT-PCR, ELISA and immunocytochemistry in cultured SGECs from eight patients with pSS and eight controls on treatment with IL-10, tumor necrosis factor α (TNF-α), IFN-α and IFN-γ. At baseline, BAFF expression in SGECs was low in pSS patients and in controls. Treatment with IFN-α, IFN-γ and TNF-α + IFN-γ increased the level of BAFF mRNA in pSS patients (the mean increases were 27-fold, 25-fold and 62-fold, respectively) and in controls (mean increases 19.1-fold, 26.7-fold and 17.7-fold, respectively), with no significant difference between patients and controls. However, in comparison with that at baseline, stimulation with IFN-α significantly increased the level of BAFF mRNA in SGECs of pSS patients (p = 0.03) but not in controls (p = 0.2), which suggests that SGECs of patients with pSS are particularly susceptible to expressing BAFF under IFN-α stimulation. Secretion of BAFF protein, undetectable at baseline, was significantly increased after IFN-α and IFN-γ stimulation both in pSS patients (40.8 ± 12.5 (± SEM) and 47.4 ± 18.7 pg/ml, respectively) and controls (24.9 ± 8.0 and 9.0 ± 3.9 pg/ml, respectively), with no significant difference between pSS and controls. Immunocytochemistry confirmed the induction of cytoplasmic BAFF expression after stimulation with IFN-α and IFN-γ. This study confirms the importance of resident cells of target organs in inducing or perpetuating autoimmunity. Demonstrating the capacity of SGECs to express and secrete BAFF after IFN stimulation adds further information to the pivotal role of these epithelial cells in the pathogenesis of pSS, possibly after stimulation by innate immunity. Our results suggest that an anti-BAFF therapeutic approach could be particularly interesting in pSS.
OBJECTIVES--To investigate the presence of antibodies to HTLV and HIV retroviral antigens in the rheumatological diseases rheumatoid arthritis (RA), polymyositis/dermatomyositis (PM/DM), primary Sjögren's syndrome (pSS), and systemic lupus erythematosus (SLE), and to use polymerase chain reaction (PCR) to seek these exogenous retroviruses in proviral form in cellular DNA from these patients. METHODS--Thirty patients with active RA, 13 with PM, 14 with pSS and five with SLE were recruited and their sera tested for antibodies to HTLV-I in enzyme linked immunosorbent assay (ELISA) and Western blot analysis. Seropositivity to HIV-1 was also sought. DNA was extracted from peripheral blood lymphocytes, synovial tissue and muscle biopsies and tested by polymerase chain reaction using consensus primers for HTLV-I and HIV-1. RESULTS--In HTLV-I ELISA, nine rheumatological sera (4/30 RA, 3/13 PM/DM and 2/5 SLE patients) were considered positive; 14 from pSS patients and 30 from normal subjects were negative. In a control group which included osteoarthritis, Crohn's disease and bacterial endocarditis patients, only two of 80 proved positive in this system. Validation of these sera by Western blotting generally revealed weak reactivity against a variety of HTLV-I antigens. PCR of genomic DNA derived from patients' peripheral blood mononuclear cells did not reveal the presence of HTLV-I and HIV-1 target sequences. CONCLUSIONS--This study shows that PCR precludes HTLV-I and HIV-1 infection as causative agents in these rheumatological diseases although a minority of patients possess antibodies that are weakly cross-reactive with retroviral antigens.
Dendritic cells (DC) are the most potent antigen-presenting cells of the immune system, involved in both initiating immune responses and maintaining tolerance. Dysfunctional and via toll-like receptor (TLR) ligands activated DC have been implicated in the development of autoimmune diseases, but their role in the etiology of Sjögren’s syndrome, a chronic inflammatory autoimmune disease characterized by progressive mononuclear cell infiltration in the exocrine glands, has not been revealed yet. Therefore, the aim of this study was to investigate phenotype and functional properties of immature and TLR7/8 stimulated monocyte-derived DC (moDC) of patients with primary Sjögren’s syndrome (pSS) and compare them to healthy controls.
The phenotype, apoptosis susceptibility and endocytic capacity of moDC were analyzed by flow cytometry. Secretion of cytokines was measured by enzyme-linked immunosorbent assay (ELISA) and multiplex Luminex analyses in moDC cell culture supernatants. The expression of TLR7 was analyzed by flow cytometry and real-time quantitative polymerase chain reaction (qPCR). Expression of Ro/Sjögren’s syndrome-associated autoantigen A (Ro52/SSA), interferon regulatory factor 8 (IRF-8), Bim, signal transduction and activators of transcription (Stat) 1, p-Stat1 (Tyrosin 701), p-Stat1 (Serin 727), Stat3, pStat3 (Tyrosin 705) and glyceraldehyde 3-phosphatase dehydrogenase (GAPDH) was measured by Western blotting. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) family members were quantified using the ELISA-based TransAM NF-κB family kit.
We could not detect differences in expression of co-stimulatory molecules and maturation markers such as cluster of differentiation (CD) 86, CD80, CD40 or CD83 on moDC from patients compared to healthy controls. Moreover, we could not observe variations in apoptosis susceptibility, Bim and Ro52/SSA expression and the endocytic capacity of the moDC. However, we found that moDC from pSS patients expressed increased levels of the major histocompatibility complex (MHC) class II molecule human leukocyte antigen (HLA)-DR. We also found significant differences in cytokine production by moDC, where increased interleukin (IL)-12p40 secretion in mature pSS moDC correlated with increased RelB expression. Strikingly, moDC from pSS patients matured for 48 hours with TLR7/8 ligand CL097 expressed significantly less Stat1.
Our results suggest a role for moDC in the pathogenesis of Sjögren’s syndrome.
TLR7/8 and TLR9 signaling pathways have been extensively studied in systemic lupus erythematosus (SLE) as possible mediators of disease. Monocytes are a major source of pro-inflammatory cytokines and are understudied in SLE. In the current project, we investigated sex differences in monocyte activation and its implications in SLE disease pathogenesis.
Human blood samples from 27 healthy male controls, 32 healthy female controls, and 25 female patients with SLE matched for age and race were studied. Monocyte activation was tested by flow cytometry and ELISA, including subset proportions, CD14, CD80 and CD86 expression, the percentage of IL-6-producing monocytes, plasma levels of sCD14 and IL-6, and urine levels of creatinine.
Monocytes were significantly more activated in women compared to men and in patients with SLE compared to controls in vivo. We observed increased proportions of non-classic monocytes, decreased proportions of classic monocytes, elevated levels of plasma sCD14 as well as reduced surface expression of CD14 on monocytes comparing women to men and lupus patients to controls. Plasma levels of IL-6 were positively related to sCD14 and serum creatinine.
Monocyte activation and TLR4 responsiveness are altered in women compared to men and in patients with SLE compared to controls. These sex differences may allow persistent systemic inflammation and resultant enhanced SLE susceptibility.
IL-10--producing B cells, Foxp3-expressing T cells (Tregs) and the IDO-expressing dendritic cells (pDC) are able to modulate inflammatory processes, to induce immunological tolerance and, in turn, to inhibit the pathogenesis of autoimmune disease.
The aim of the study was to characterize and to enumerate peripheral IL-10--producing B cells, Tregs and pDCregs in primary Sjögren's Syndrome (pSS) patients in regard of their clinical and serologic activity.
Fifty pSS patients and 25 healthy individuals were included in the study. CD19+--expressing peripheral B lymphocytes were purified by positive selection. CD19+/CD24hi/CD38hi/IL-10--producing B cells, CD4+/CD25hi/Foxp3+ and CD8+/CD28-/Foxp3+ Tregs, as well as CCR6+/CD123+/IDO+ DCs, were quantitated by flow cytometry.
Immature/transitional circulating IgA+ IL-10--producing B cells had higher levels in pSS patients versus control group, whereas CD19+/CD38hi/IgG+/IL-10+ cells had lower percentage versus control. Indeed CD19+/CD24hi/CD38hi/CD5+/IL-10+, CD19+/CD24hi/CD38hi/CD10+/IL-10+, CD19+/CD24hi/CD38hi/CD20+/IL-10+, CD19+/CD24hi/CD38hi/CD27-/IL-10+, and CD19+/CD24hi/CD38hi/CXCR7+/IL-10+ cells had higher frequency in clinical inactive pSS patients when compared with control group. Remarkably, only percentages of CD19+/CD24hi/CD38hi/CD10+/IL-10+ and CD19+/CD24hi/CD38hi/CD27-/IL-10+ subsets were increased in pSS serologic inactive versus control group (P < 0.05). The percentage of IDO-expressing pDC cells was higher in pSS patients regardless of their clinical or serologic activity. There were no statistically significant differences in the percentage of CD4+/CD25hi/Foxp3+ Tregs between patient groups versus controls. Nonetheless, a decrease in the frequency of CD8+/CD28-/Foxp3+ Tregs was found in inactive pSS patients versus controls (P < 0.05).
The findings of this exploratory study show that clinical inactive pSS patients have an increased frequency of IL-10--producing B cells and IDO-expressing pDC cells.
BACKGROUND: Platelet-activating factor (PAF) seems to be implicated in systemic lupus erythematosus (SLE) patients with associated renal diseases. AIMS: In this study, we ensured the role of PAF in SLE patients without renal complications. METHODS: Blood PAF and acetylhydrolase activity, plasma soluble phospholipase A(2), and the presence of antibodies against PAF were investigated in 17 SLE patients without active nephritis and in 17 healthy controls. RESULTS: Blood PAF levels were not different (p=0.45) between SLE patients (6.7+/-2.8 pg/ml) and healthy subjects (9.6+/-3.1 pg/ml). Plasma acetylhydrolase activity (the PAF-degrading enzyme) was significantly (p=0.03) elevated in SLE patients (57.8+/-6.4 nmol/min/ml) as compared with controls (37.9+/-2.6 nmol/min/ml). Plasma soluble phospholipase A(2) (the key enzyme for PAF formation) was not different (p=0.6) between SLE patients (59.1+/-5.1 U/ml) and controls (54.7+/-2.4 U/ml). Antibodies against PAF were detected only in 3/17 SLE patients. Flow cytometry analysis did not highlight PAF receptors on circulating leukocytes of SLE patients. CONCLUSION: This clinical study highlights no evidence for a putative important role of PAF in SLE patients without active nephritis.
Simple measures of type I interferon (IFN) activity constitute highly attractive biomarkers in systemic lupus erythematosus (SLE). We explore galectin-3-binding protein (G3BP) as a novel measure of type I IFN activity and serum/plasma biomarker in large independent cohorts of patients with SLE and controls.
Serum and plasma G3BP concentrations were quantified using ELISA. Type I IFN activity was assessed by Mx1 reporter gene expression assays and correlated to serum G3BP concentrations (SLE-IFN-α, n=26 and healthy controls (HCs), n=10). Plasma G3BP concentrations in the SLE-Denmark (DK) (n=70) and SLE-Sweden (SE) (n=68) cohorts were compared with the HC-DK (n=47) and HC-SE (n=50) cohorts and patients with systemic sclerosis (n=111). In 15 patients with SLE, serum G3BP in consecutive samples was correlated to disease activity. Correlation analysis between G3BP, clinical parameters including disease activity in the four SLE cohorts was performed.
G3BP concentrations correlated significantly with the IFN-α reporter gene assay (r=0.56, p=0.0005) and with IFN-α gene expression scores (r=0.54, p=0.0002). Plasma concentrations were significantly increased in the SLE-DK and SLE-SE cohorts compared with HCs and patients with systemic sclerosis (p<0.0001 and p=0.0009). G3BP concentrations correlated with disease activity measures in the SLE-DK- and SLE-IFN-α cohorts (p=0.0004 and p=0.05) but not in the SLE-SE cohort (p=0.98). Markedly temporal variation was observed in G3BP levels in the consecutive SLE-samples and was significantly associated with changes in disease activity (r=0.44, p=0.014).
G3BP plasma levels reflect type I IFN activity and are increased in SLE. Associations with disease activity or clinical manifestations are uncertain. This study highlights G3BP as a convenient measure of type I IFN-dependent gene activation.
Systemic Lupus Erythematosus; Systemic Sclerosis; Interferon; Lupus Nephritis; Autoantibodies
Background: In primary Sjögren's syndrome (pSS), extraglandular involvement might result from more intense stimulation of autoreactive B cells. Thus markers of B cell activation could be useful in the clinical assessment of this disease.
Objective: To investigate the association of serum B lymphocyte stimulator (BLyS) and ß2 microglobulin with autoantibody production and extraglandular involvement in pSS.
Methods: Serum concentrations of BLyS and ß2 microglobulin were analysed in 177 patients with pSS according to the American–European consensus group criteria. Serum ß2 microglobulin was determined serially in 25 patients.
Results: Autoantibody secretion (presence of anti-SSA antibody alone or of both anti-SSA and anti-SSB) was associated with increased serum BLyS and ß2 microglobulin. No correlation was found between BLyS and ß2 microglobulin levels (p = 0.36). Serum concentrations of ß2 microglobulin and C reactive protein and positive anti-SSB antibody results were associated with extraglandular involvement on univariate analysis (p<10–4, p = 0.003, and p = 0.004, respectively). Serum ß2 microglobulin was also significantly increased in patients with extraglandular involvement without autoantibodies (mean (SD): 1.75 (0.7) v 1.39 (0.5) mg/l, p = 0.039). Multivariate analysis showed that extraglandular involvement was associated only with increased serum ß2 microglobulin (p = 0.035, odds ratio = 2.78 (95% confidence interval, 1.07 to 7.22)). Among the 25 patients who had serial determinations of serum ß2 microglobulin, the concentrations were increased in all those with disease flare and decreased in three following treatment. Serum BLyS, gamma globulin, IgG, and rheumatoid factor levels were not associated with features of systemic involvement.
Conclusions: Serum ß2 microglobulin and BLyS reflect B cell activation in different ways in pSS. Serum ß2 microglobulin assessment could be helpful as an activity marker in pSS.
IgG4-related disease (IgG4-RD) is a multisystem-involved autoimmune disease. Abnormally activated and differentiated B cells may play important roles. Regulatory B cells (Breg) are newly defined B cell subgroups with immunosuppressive functions. In this study, we investigated the differences of B cell subsets, the expressions of co-stimulatory molecules on B cells, and the function of Breg cells in patients with IgG4-RD, primary Sjögren’s syndrome (pSS) as well as in healthy controls (HC).
Newly diagnosed IgG4-RD patients (n = 48) were enrolled, 38 untreated pSS patients and 30 healthy volunteers were recruited as disease and healthy controls. To analyze B cell subsets and B cell activity, PBMCs were surface stained and detected by flow cytometry. The function of Breg cells was tested by coculturing isolated CD19 + CD24hiCD38hi Breg cells with purified CD4 + CD25- T cells. Serum cytokines were measured by ELISA and cytometric bead array. Relationship between clinical data and laboratory findings were analyzed as well.
Compared with pSS patients and HC, IgG4-RD patients had a lower frequency of peripheral Breg cells. Interestingly, CD19 + CD24-CD38hi B cell subsets were significantly higher in peripheral B cells from IgG4-RD patients than in pSS patients and HC, which correlated with serum IgG4 levels. The expression of BAFF-R and CD40 on B cells was significantly lower in IgG4-RD patients compared with those in pSS patients and HC. Unlike HC, Breg cells from pSS patients lacked suppressive functions.
B cells in patients with IgG4-RD and pSS display a variety of abnormalities, including disturbed B cell subpopulations, abnormal expression of key signaling molecules, co-stimulatory molecules, and inflammatory cytokines. In addition, a significantly increased B cell subset, CD19 + CD24-CD38hi B cells, may play an important role in the pathogenesis of IgG4-RD.
The aims of this study were to evaluate the diagnostic accuracy of blood B-cell subset profiling and immune-system activation marker assays in primary Sjögren’s syndrome (pSS) and to assess whether adding these tools to the current laboratory item would improve the American-European Consensus Group (AECG) criteria.
In a single-center cohort of patients with suspected pSS, we tested the diagnostic performance of anti-SSA, antinuclear antibody (ANA), rheumatoid factor (RF), gammaglobulins, IgG titers, and B-cell ratio defined as (Bm2 + Bm2′)/(eBm5 + Bm5), determined using flow cytometry. The reference standard was a clinical diagnosis of pSS established by a panel of experts.
Of 181 patients included in the study, 77 had pSS. By logistic regression analysis, only ANA ≥1:640 (sensitivity, 70.4%; specificity 83.2%) and B-cell ratio ≥5 (sensitivity, 52.1%; specificity, 83.2%) showed independent associations with pSS of similar strength. In anti-SSA-negative patients, presence of either of these two criteria had 71.0% sensitivity but only 67.3% specificity for pSS; whereas combining both criteria had 96.2% specificity but only 12.9% sensitivity. Adding either of these two criteria to the AECG criteria set increased sensitivity from 83.1% to 90.9% but decreased specificity from 97.1% to 85.6%, whereas adding both criteria in combination did not substantially modify the diagnostic performance of the criteria set. The adjunction of RF + ANA ≥1:320, as proposed in the new American College of Rheumatology (ACR) criteria, did not improve the diagnostic value of anti-SSA.
Blood B-cell subset profiling is a simple test that has good diagnostic properties for pSS. However, adding this test, with or without ANA positivity, does not improve current classification criteria.