Abstract
We investigated the serum concentration of vascular endothelial growth factor (VEGF) and its two soluble receptors, sVEGFR-1 and sVEGFR-2, in a group of 60 patients with systemic lupus erythematosus (SLE), and 20 healthy controls, using an enzyme-linked immunosorbent assay. We examined a possible association between serum levels of these proteins and certain clinical and laboratory parameters as well as SLE activity. VEGF, sVEGFR-1 and sVEGFR-2 were detectable in all patients with SLE and in all normal individuals. The VEGF level was higher in active SLE (mean, 300.8 pg/ml) than in inactive SLE (mean, 165.9 pg/ml) (p < 0.05) or in the control group (mean, 124.7 pg/ml) (p < 0.04). The highest sVEGFR-1 concentrations were also detected in active SLE patients (mean, 42.2 pg/ml) and the lowest in inactive disease (mean, 32.0 pg/ml) (p < 0.01). In contrast, the levels of sVEGFR-2 were lower in SLE (mean, 12557.6 pg/ml) than in the control group (mean, 15025.3 pg/ml) (p < 0.05). We found a positive correlation between sVEGFR-1 concentration and the SLE activity score p = 0.375 (p < 0.004) and a negative, but statistically insignificant correlation between sVEGFR-2 and SLE activity (p = -0.190, p > 0.05). Treatment with steroids and cytotoxic agents did not influence VEGF or its soluble receptors levels. In conclusion, in SLE patients the levels of VEGF and sVEGFR-1 are higher in patients with active SLE than in inactive disease or healthy persons. In contrast, the level of sVEGFR-2 is lower in active SLE than in inactive disease. The imbalance between VEGF and its soluble receptors may be important in SLE pathogenesis.
Highlights
Vascular endothelial growth factor (VEGF) is a key regulator of vasculogenesis and angiogenesis.[1,2] VEGF is produced by endothelial cells, macrophages, fibroblasts and smooth muscle cells.[1]
The serum concentrations of VEGF and its soluble receptors sVEGFR-1 and sVEGFR-2 were detectable in all systemic lupus erythematosus (SLE) patients and in healthy volunteers
It has been shown that mRNA for a soluble form of VEGF receptor 1 (VEGFR-1) was generated by the alternative splicing in human umbilical vein endothelial cells and that sVEGFR-1, as a competitive inhibitor, was able to bind all isoforms of VEGF and to inhibit VEGFinduced endothelial cell proliferation.[13]
Summary
Vascular endothelial growth factor (VEGF) is a key regulator of vasculogenesis and angiogenesis.[1,2] VEGF is produced by endothelial cells, macrophages, fibroblasts and smooth muscle cells.[1] It is a chimeric glycoprotein with a molecular weight of 34Á/45 kDa, consisting of two subunits.[3,4] Five isoforms of human VEGF have been described to date, each generated by alternative splicing of a single mRNA and resulting in proteins of varying amino acid length, (VEGF).[121,145,165,189,206] This angiogenic cytokine binds to receptors on endothelial cells and acts as direct inducer of angiogenesis both in vivo and in vitro .5. Both receptors share common features such as seven immunglobulin-like extracellular domains, a single transmembrane region and a consensus tyrosine kinase sequence interrupted by a kinase insert domain, and they are highly glycosylated.[10,11] VEGFR-1 binds to VEGF with substantially higher affinity, most of the biological effects of VEGF seem to be mediated via VEGFR-2.12
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