Antibodies to vascular heparan sulfate proteoglycan in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease which involves the basement membranes of blood vessels in multiple organs. An important component of the microvasculature is vascular heparan sulfate proteoglycan (HSPG). In this study, we investigated the presence in SLE and other immune disease sera of autoantibodies to purified vascular HSPG. Our data demonstrate that antibody to HSPG is found primarily in SLE sera, and not in sera from controls or patients with other immune diseases. The titer of antibody to HSPG correlated with complement depletion in SLE sera. Antibody to HSPG was frequently found in high titer in SLE patients with renal and neurologic involvement. These studies indicate that our assay for antibody to vascular HSPG detects a pathologically relevant autoantibody in SLE sera. The implications of our findings for pathogenesis of vascular autoimmunity are discussed, including the relationship of anti-vascular HSPG antibody to anti-DNA and antiphospholipid antibodies.