A pathogenic role for IL-10 signalling in capillary stalling and cognitive impairment in type 1 diabetes

Vascular pathology is associated with cognitive impairment in diseases such as type 1 diabetes, but precisely how capillary flow is affected and the underlying mechanisms remain elusive. Here we show that capillaries in the diabetic mouse brain are prone to stalling, with blocks composed primarily of erythrocyte plugs in branches off penetrating venules. Increased capillary obstructions were evident in both sexes and only partially reversed by insulin. Screening for circulating inflammatory cytokines revealed persistently high levels of interleukin-10 (IL-10) in diabetic mice. Contrary to expectation, stimulating IL-10 signalling increased capillary obstructions, whereas inhibiting IL-10 receptors with neutralizing antibodies or endothelial specific knockdown in diabetic mice, reversed these impairments. Chronic IL-10R blocking antibody treatment in diabetic mice also improved stimulus evoked cerebral blood flow, increased capillary widths in lower-order branches and reversed cognitive deficits. These data suggest IL-10 signalling plays an unexpected pathogenic role in cerebral microcirculatory defects and cognitive impairment.