Microvascular damage, neuroinflammation and extracellular matrix remodeling in Col18a1 knockout mice as a model for early cerebral small vessel disease.

Collagen type XVIII (COL18) is an abundant heparan sulfate proteoglycan in vascular basement membranes. Here, we asked (i) if the loss of COL18 would result in blood-brain barrier (BBB) breakdown, pathological alterations of small arteries and capillaries and neuroinflammation as found in cerebral small vessel disease (CSVD) and (ii) if such changes may be associated with remodeling of synapses and neural extracellular matrix (ECM). We found that 5-month-old Col18a1 mice had elevated BBB permeability for mouse IgG in the deep gray matter, and intravascular erythrocyte accumulations were observed brain-wide in capillaries and arterioles.