The Effect of Systemic Lupus Erythematosus Over the Physiologic Inhibition of 1,25(OH)2D on Monocyte-Tissue Factor (CD142) Expression

Background and Aims: Systemic Lupus Erythematosus is a systemic autoimmune disease with increased risk of thrombosis through the induction of tissue factor (TF) expression, the principal initiator of coagulation. Despite its correlation with some autoimmune diseases, including SLE; vitamin D also correlates well with thrombotic events in SLE or non SLE patients. Vitamin D is an immunomodulator that might have an anti-thrombotic effect by down-regulating TF expression in an vitro model of healthy subjects. Therefore, we studied the effect of metabolite active form of vitamin D [1,25(OH)2D] on monocyte-TF (CD142) expression of SLE patients.
Methods: Monocyte culture were obtained from 6 Indonesian SLE patients and 3 age- and sex- matched, healthy Indonesian participants to evaluate the effect of various concentrations of 1,25(OH)2D on monocyte-TF expression in LPS-induced monocytes. The monocyte-TF (CD142) expression was then analyzed by flow cytometry using Monoclonal Anti-human Coagulation Factor III/TF (CD142)-Phycoerythrin and FITC anti-human CD14.
Results: In vitro model of monocyte culture from SLE patients revealed that 1,25(OH)2D showed no inhibitory effects of monocyte-TF expression (p = .275). Higher or lower doses of 1,25(OH)2D did not correlate with high or low CD142 expression in monocyte culture of SLE patients(r=.1, p=.322).
Conclusion: In vitro study of SLE patients showed that 1,25(OH)2D has no inhibitory effect on TF expression. Ten nM 1,25(OH)2D seemed to be the optimal concentration for suppressing LPS-induced monocyte-TF expression in healthy groups but not in SLE groups.
The different characteristics of monocytes, VDR polymorphism, and the need of higher concentration of vitamin D were the best explanation so far for the different effects in monocyte culture of SLE patients.