White matter damage is associated with matrix metalloproteinases in vascular dementia

Abstract

Background and Purpose - Vascular disease causes multi-infarct dementia (MID) or Binswanger's disease (BD), the latter of which is a progressive form of vascular dementia (VaD) associated pathologically with fibrinoid and hyaline changes in brain arterioles with injury to the white matter. Clinically, BD patients have long-standing hypertension with disturbances of gait and intellect. Because matrix metalloproteinases (MMPs) are important in cerebral infarction, we hypothesized that disturbances in the MMPs may be involved in VaD. Methods - Brain tissues from 5 patients with VaD of the BD or multi-infarct type (MID) were immunostained with antibodies to glial fibrillary acidic protein (GFAP), a microglial/macrophage cell marker (PG-M1), gelatinase A (MMP-2), stromelysin-1 (MMP-3), and gelatinase B (MMP-9). Control tissues were from 8 elderly patients: 4 with strokes without dementia and 4 without neurological diseases. Results - PG-M1 + cells appeared around infarcts in patients with strokes without dementia and in patients with VaD. In 2 of the 3 BD patients, PG-M1 cells were prominent near damaged arterioles and scattered diffusely in white matter. MMP-2 was seen normally in perivascular macrophages and in astrocytic processes near blood vessels and was present in patients with strokes in reactive astrocytes. MMP-9 was rarely seen. MMP-3 was seen in PG-M1 + microglial/macrophage cells around the acute infarctions. In BD, MMP-3 persisted in tissue macrophages and disappeared in long-standing white matter gliosis. Conclusions - These observations suggest that MMPs may participate in the damage to the white matter associated with VaD. Microglia/macrophage-induced damage, which is amenable to treatment, may be a factor in the progressive forms of VaD.