Elevated circulating soluble CD40 ligand in patients with mixed connective tissue disease

Soluble CD40L is associated with increased oxidative burst and neutrophil extracellular trap release in Behçet's disease

Background

Studies have suggested that soluble factors in plasma from patients with active (aBD) and inactive (iBD) Behçet’s disease (BD) stimulate neutrophil function. Soluble CD40 ligand (sCD40L) is an important mediator of inflammation in BD. Its expression and effect on neutrophil oxidative burst and neutrophil extracellular trap (NET) release have not been characterized. In this study, we sought to investigate the role of plasma and the CD40L pathway on NET release and the oxidative burst profile in patients with aBD and iBD.

Methods

Neutrophils and peripheral blood mononuclear cells (PBMCs) were obtained from patients with aBD (n = 30), patients with iBD (n = 31), and healthy control subjects (HCs; n = 30). sCD40L plasma concentration was determined in individual samples. A pool of plasma for each group was created. In some experiments, plasma pools were treated with recombinant CD40 (rhCD40-muIg) for sCD40L blockade. NET release and H₂O₂/O₂⁻ production were determined after stimulation with phorbol 12-myristate 13-acetate, sCD40L, or plasma pool. Flow cytometric analysis was performed to evaluate the expression of (1) CD40, Mac-1, and phosphorylated NF-κB p65 on neutrophils and monocytes and (2) CD40L on activated T cells and platelets. CD40L gene expression in PBMCs was determined by qRT-PCR.

Results

sCD40L plasma levels were significantly higher in patients with iBD (median 17,234, range 2346–19,279 pg/ml) and patients with aBD (median 18,289, range 413–19,883 pg/ml) than in HCs (median 47.5, range 33.7–26.7 pg/ml; p < 0.001). NET release was constitutively increased in BD compared with HC. NET release and H₂O₂/O₂⁻ were higher after stimulation with sCD40L or BD plasma and decreased after sCD40L blockade. Mac-1 expression was constitutively increased in neutrophils of patients with aBD (88.7 ± 13.2% of cells) and patients with iBD (89.2 ± 20.1% of cells) compared with HC (27.1 ± 18.8% of cells; p < 0.01). CD40 expression on phagocytes and CD40L expression on platelets were similar in the three groups. PBMCs as well as nonactivated and activated CD4⁺ T cells from patients with BD showed higher CD40L expression.

Conclusions

Plasma from patients with aBD exerts a stimulus on NET release and oxidative burst, probably induced by sCD40L.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1443-5) contains supplementary material, which is available to authorized users.

Diagnosis and risk stratification in patients with anti-RNP autoimmunity

INTRODUCTION

Anti-RNP autoantibodies occur either in mixed connective tissue disease (MCTD) (with a frequently favorable prognosis), or in systemic lupus erythematosus (SLE) cases with aggressive major organ disease. It is uncertain how to assess for the risk of severe disease in anti-RNP + patients.

METHODS

Following institutional review board-approved protocols, clinical data and blood were collected from patients with known or suspected anti-RNP autoimmunity and normal controls in a cohort study. Samples were screened for parameters of immune activation. Groups were compared based on clinical diagnoses, disease classification criteria, disease activity and specific end-organ clinical manifestations.

RESULTS

Ninety-seven per cent of patients satisfying Alarcon-Segovia MCTD criteria also met Systemic Lupus International Collaborating Clinic (SLICC) SLE criteria, while 47% of the anti-RNP + SLE patients also met MCTD criteria. Among SLICC SLE patients, MCTD criteria were associated with reduced rates of renal disease (odds ratio (OR) 4.3, 95% confidence interval (CI) 1.3-14.0), increased rates of Raynaud's phenomenon (OR 3.5, 95% CI 1.3-9.5) and increased serum B-cell maturation antigen, transmembrane activator and CAML interactor and TNFα levels. Circulating immune markers and markers of type I interferon activation were not effective at distinguishing clinical subgroups.

CONCLUSIONS

Among anti-RNP patients, the question of MCTD versus SLE is not either/or: most MCTD patients also have lupus. MCTD classification criteria (but not a broad set of immune markers) distinguish a subset of SLE patients at reduced risk for renal disease.

Pathogenesis of endometriosis: the role of defective 'immunosurveillance'

OBJECTIVE

To analyse the aetiopathogenesis and the role of defective 'immunosurveillance' in endometriosis.

METHOD

Review of studies on the pathogenesis of endometriosis, focusing particularly on novel molecules which express adhesive or proteolytic properties. Hypotheses addressing the role of oxidative stress in endometriosis were also reviewed.

RESULTS

Endometriosis is a multifactorial disease associated with a general inflammatory response aiming to clear the peritoneal cavity from the ectopic endometriotic cells and tissue. Modern theories suggest that this inflammatory response creates an environment that may promote implantation and proliferation due to defective 'immunosurveillance'.

CONCLUSION

The modern interpretation of the theory of reflux menstruation holds that women destined to develop endometriosis have a deficient immune system, which cannot defend against regurgitated endometrial cells. New findings on genetics, immune modulation, and secreted products of endometriotic lesions of affected women have given insight into the pathogenesis of this disorder and may serve as the background for new treatments of endometriosis-associated pain and infertility.

Elevated levels of soluble CD40 ligand (sCD40L) in serum of patients with systemic autoimmune diseases

The CD40-CD40L costimulatory pathway is involved in the evolution of many autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and Sjögren's syndrome (SS). Increased levels of sCD40L in the serum have been associated with disease activity in SLE. The aim of this study was to investigate the role of sCD40L in the development of lupus nephritis and examine its possible association with cryoglobulinemia in Sjögren's syndrome. We used a 2-site sandwich ELISA to measure the levels of sCD40L in sera, from 64 patients with SLE, RA and SS and 17 healthy blood donors. Biological specimens from the affected tissues such as urine from patients with lupus nephritis and saliva from patients with SS were also tested. In this regard, paired sera and first morning urine samples from 6 SLE patients (3 with active lupus nephritis and 3 with inactive lupus nephritis) were tested with the sCD40L ELISA protocol as well as paired sera and salivary samples from 5 patients with SS and cryoglobulinemia, 5 patients with SS and anti-Ro or anti-La autoantibodies and 5 age-matched healthy control donors. We also examined possible correlations of sCD40L levels with several laboratory and clinical parameters in SS and SLE. We found that sera from SLE and SS patients had significantly higher levels of sCD40L compared to sera from healthy control donors. No sCD40L was detected, in urine samples of patients with either active or inactive nephritis and in salivary samples from SS patients or normal subjects. Soluble CD40L is elevated in sera of SS and SLE patients but further investigation is needed to determine its possible role in SLE nephritis and Sjögren's syndrome.

Significant correlation between the CD63 assay and the histamine release assay in chronic urticaria

BACKGROUND

Antibodies directed to the alpha subunit of the high affinity IgE receptor and the IgE molecule are proposed to be of pathogenetic relevance in a group of patients with chronic urticaria (CU). The diagnosis of autoimmune chronic urticaria (ACU) is difficult; the autologous serum skin test (ASST) seems to be a useful screening test, but reliable, additional confirmatory methods are needed.

OBJECTIVES

To assess the diagnostic value of a modified serum-induced basophil activation test, the CD63 expression assay, in the diagnosis of ACU by comparing the results of the CD63 assay with the results of the histamine release (HR) test, the ASST and serum levels of soluble CD40 ligand (sCD40L).

METHODS

Using basophils from an atopic (DA) and a nonatopic (DNA) donor the activity of sera of 72 patients with CU were measured in HR assay by enzyme-linked immunosorbent assay and in CD63 expression assay by flow cytometry. An ASST was carried out in all patients; in 30 of the 72 patients sCD40L was detected and correlations were derived between the different assays. Sera of 20 normal controls and 26 patients with systemic autoimmune diseases were also tested in the HR assay and in the CD63 expression assay.

RESULTS

Histamine-releasing activity was detected in the sera of 51% (DA) and 32% (DNA) of CU patients and 57% (DA) and 28% (DNA) of sera upregulated CD63 expression on the surface of basophils from the different donors. There was a significant correlation between the HR and the CD63 assays carried out on both donors, but the ASST showed a strong correlation with the HR assay only for basophils from the DA. The serum level of sCD40L was significantly higher in patients with CU compared with controls, but the difference between the autoimmune and the nonautoimmune groups was not significant.

CONCLUSIONS

The CD63 expression assay seems to be a reliable functional test in the diagnosis of ACU, particularly if highly sensitive donor basophils are used, but the determination of the sCD40L serum level was not sufficient to differentiate between the autoimmune and the nonautoimmune patient groups.

Analysis of serum soluble CD40 ligand in patients with influenza virus-associated encephalopathy

CD40 ligand (CD40L) is mainly expressed on activated platelets and CD4+T cells, and it can be cleaved from the cell surface, releasing a soluble CD40L (sCD40L). Most sCD40L is derived from activated platelets. A previous paper revealed that the platelet number of patients with influenza virus-associated encephalopathy (IE) was correlated with the outcome. We determined the utility of sCD40L as a predictor for the prognosis of IE. We measured the serum concentration of sCD40L and the platelet number on the day of hospitalization in 34 patients with IE, 16 with influenza virus-associated febrile seizures (IFS), 19 with influenza virus infection without complications (Flu), and 7 with Epstein-Barr virus (EBV) infection. The serum sCD40L concentrations in IE and IFS were significantly lower than those in controls, Flu, and EBV infections. Serum sCD40L concentrations in the IE group were 0.70+/-0.43 ng/ml for deceased patients, 1.73+/-1.36 ng/ml for those with sequelae, and 3.85+/-2.91 ng/ml for those without sequelae. There was no significant difference in platelet number between IE patients with and without sequelae, while the platelet number of deceased patients with IE was significantly lower than in controls, Flu, and IFS. Serum sCD40L concentration on the day of hospitalization was more correlated with the outcome of IE than platelet number. Our findings suggest that the serum sCD40L concentration during acute IE is important for predicting the prognosis at an early stage.

Association between enhanced soluble CD40 ligand and prothrombotic state in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease is associated with an increased incidence of thromboembolic complications. The aim of this study was to investigate the role of the soluble CD40 ligand (sCD40L), which displays prothrombotic properties, in patients with ulcerative colitis (UC) and Crohn's disease (CD) in comparison with inflammatory and healthy controls.

METHODS

Plasma levels of sCD40L, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin (TAT) complex and soluble P-selectin were measured in 104 inflammatory bowel disease patients (54 ulcerative colitis and 50 Crohn's disease), in 18 cases with other causes of intestinal inflammation and in 80 healthy controls using commercially available enzyme-linked immunosorbent assays. Plasma levels of sCD40L were correlated with disease activity, type, localization and treatment as well as with the measured thrombophilic parameters.

RESULTS

CD patients had significantly higher sCD40L levels than both groups of controls (CD vs HC P < 0.001; CD vs non-IBD P < 0.05). UC patients had higher but not significantly different sCD40L levels compared with the controls. Both UC and CD patients with active disease had significantly higher sCD40L levels in comparison with patients with inactive disease. Plasma levels of sCD40L were correlated with platelet count (r = 0.27, P = 0.001). They also showed a correlation with prothrombin F1+2 (r = 0.16, r = 0.03) and TAT (r = 0.15, r = 0.04) as well as with P-selectin (r = 0.19, P = 0.01).

CONCLUSIONS

The increased sCD40L plasma levels may represent, at least in some degree, a molecular link between inflammatory bowel disease and the procoagualant state.