Plasma thrombomodulin levels in women with systemic lupus erythematosus

Soluble thrombomodulin levels in plasma of multiple sclerosis patients and their implication

Thrombomodulin (TM) on the cell-surface of cerebrovascular endothelial cells (CECs) is released into blood upon CEC damage. TM promotes activation of protein C (APC), an anticoagulant, anti-inflammatory, neuroprotective molecule that protects CECs and impedes inflammatory cell migration across the blood-brain barrier (BBB). Multiple sclerosis (MS) is associated with CEC damage and BBB dysfunction. We evaluated soluble TM (sTM) levels as a biomarker of BBB integrity and whether glatiramer acetate (GA) influenced sTM levels in MS patients. sTM levels quantified by 2-site ELISA from sera of healthy controls and systemic lupus erythematosus (SLE) patients (CEC-damage positive control) were compared with levels from patients with relapsing-remitting (RRMS) or secondary-progressive MS (SPMS), stratified as: RRMS/GA/no relapse, RRMS/GA/in relapse, RRMS no GA/no relapse, RRMS/no GA/in relapse; and SPMS/no GA. Additionally, soluble endothelial protein C receptor (sEPCR) levels were assessed in the non-stratified MS group, SLE patients, and controls. sTM levels were highest in RRMS patients taking GA with or without relapse, followed in decreasing order by SLE, RRMS/no GA/in relapse, SPMS, RRMS/no GA/no relapse, healthy controls. sEPCR levels were highest in MS patients, then SLE, then controls. sTM may be a useful biomarker of BBB integrity in RRMS patients. Further evaluation of sEPCR is needed. The finding that the highest sTM levels were in RRMS patients taking GA is interesting and warrants further investigation.

IgG anti-endothelial cell autoantibodies from patients with systemic lupus erythematosus or systemic vasculitis stimulate the release of two endothelial cell-derived mediators, which enhance adhesion molecule expression and leukocyte adhesion in an autocrine manner

OBJECTIVE

To investigate the ability of anti-endothelial cell antibodies (AECA) to modulate endothelial cell function.

METHODS

The effects of purified IgG from 11 patients with systemic lupus erythematosus (SLE) and 4 patients with systemic vasculitis on the expression of adhesion molecules (intercellular adhesion molecule 1, vascular cell adhesion molecule 1, E-selectin) by human umbilical vein endothelial cells and on the adhesion of the human promyelocytic cell line U937 were examined in vitro.

RESULTS

IgG from 6 of 8 AECA-positive SLE patients and 3 of 3 AECA-positive systemic vasculitis patients up-regulated adhesion molecule expression and leukocyte adhesion to endothelial cells. The 4 AECA-negative samples had no effect. Transfer experiments demonstrated that at later time points (2-8 hours) after AECA addition, endothelium-derived interleukin-1 (IL-1) accounted for the ability of AECA to increase leukocyte adhesion. However, even within very short times after addition of AECA (<30 minutes), endothelial cells released a distinct transferable mediator with similar effects.

CONCLUSION

AECA in patients with SLE or systemic vasculitis may contribute to pathogenesis by increasing leukocyte adhesion to endothelial cells. AECA act by inducing the release of at least two endothelium-derived mediators, one (as-yet-unidentified) rapidly and another (IL-1) more slowly, both of which stimulate endothelial cells in an autocrine manner.

Pregnancy in SLE

The effect of pregnancy on disease activity in systemic lupus erythematosus remains controversial. Studies on lupus flares in pregnancy are discussed, including prospective data on severity of flares and organ involvement from the Hopkins Lupus Pregnancy Center. The major fetal concerns of miscarriage (due to the antiphospholipid antibody syndrome), pre-term birth (largely due to pre-eclampsia or premature rupture of membranes) and neonatal lupus, are reviewed.

Soluble vascular cell adhesion molecule-1 as a biohumoral correlate of atherosclerosis

Vascular cell adhesion molecule-1 (VCAM-1) is a protein expressed on the surface of activated endothelial cells and expressed in early atherosclerosis. Because part of the protein is shed in the circulation and can be detected in peripheral plasma [soluble (s) VCAM-1], we hypothesized that sVCAM-1 may be a circulating marker of the presence and severity of atherosclerosis in humans. We selected 11 patients with essential hypertension plus peripheral vascular disease (PVD) and matched them for age, gender, body mass index, and smoking habits with 11 patients with uncomplicated essential hypertension (UH) and 11 healthy controls. We evaluated plasma concentrations of sVCAM-1 along with those of the soluble form of two other endothelial leukocyte adhesion molecules [sE-selectin and s-intercellular adhesion molecule-1 (sICAM-1)] and other markers of endothelial dysfunction/ damage [s-thrombomodulin, plasminogen activator inhibitor type I, and von Willebrand factor (vWF)]. We also measured insulin, glucose, fibrinogen, total and HDL cholesterol, and the urinary albumin excretion (UAE), which may also be related to atherosclerosis. Results of these assays were related to the echographic assessment of the maximum intima-media thickness (IMTmax) at the carotid bifurcation, as an index of atherosclerosis in the carotids. PVD patients had a clearly elevated IMTmax [2.7 (1.1-3.1) mm, median (range)] compared with both UH patients [1.2 (0.8-2.4) mm] and controls [1 (0.6-2) mm]. sVCAM-1 was clearly higher in PVD patients [990 (273-1808) ng/mL, median (range)] versus 340 (236-975) ng/mL in UH and 386 (204-835) ng/mL in controls, and it separated clinical categories better than sICAM-1, vWF, glucose, insulin, UAE, triglycerides, or total, LDL or HDL cholesterol, sVCAM-1 was also the best biohumoral correlate of IMTmax (R = .59; P < .001) in univariate analysis. Because many of the biohumoral variables assessed were mutually intercorrelated, they were entered in a multivariate analysis to assess their contribution in explaining IMTmax variability. sVCAM-1 remained the only independent predictor of IMTmax and totally abolished the contribution of other variables to IMTmax variability. Thus, sVCAM-1 is a good biohumoral correlate of overt atherosclerosis, independent of underlying hypertension, and may be an in vivo marker of endothelial activation. Its potential value as a surrogate for global risk assessment and its behavior in intervention studies remain to be determined.