Fig. 8. Proinflammatory factors ELANE and CXCL16 disrupt vasculature in GEs to promote hemorrhage in embryonic mouse brain.

a, Schematic diagram showing two schedules of ELANE and CXCL16 intraperitoneal (IP) injection in pregnant mouse dams for embryonic brain tissue collection at E13.5 and E17.5. b, ELANE and CXCL16 protein concentrations in the plasma of PBS-injected control and ELANE/CXCL16-injected pregnant dams. c, Immunostaining with IB4 and Ter119 show leaked red blood cells in the GE but not in VZ/SVZ of the pallium or cortical plate (CP) of control or ELANE/CXCL16-injected embryos at E13.5. d, Quantifications of densities of blood vessels and leaked red blood cells (RBC) in VZ of the GE, VZ/SVZ of the pallium and CP in control of PBS-injected or ELANE/CXCL16-injected embryos at E13.5. e, Immunostaining with IB4 and IBA1 show reduced vascular density and increased ameboid morphology in IBA1⁺ cells in VZ of the GE but not in VZ/SVZ of the pallium or CP in ELANE/CXCL16-injected embryos at E17.5. f, Quantifications of densities of blood vessels and IBA1⁺ cells in VZ of the GE, VZ/SVZ of the pallium and CP in non-injected control of PBS-injected or ELANE/CXCL16-injected embryos at E17.5. Statistics in b, d and f use a two-tailed, unpaired Student’s t-test; n.s., not significant. n indicates the number of independent biological samples used for quantification. g, Left: schematic diagram depicting how subsets of CD45⁺ immune cells, including monocytes (gray), HLA⁺ myeloid cells (purple) and VAM (light blue) interact with the nascent vasculature to promote angiogenesis in the germinal matrix during the second trimester in prenatal human brain. Right: activated neutrophils produce bactericidal factors, such as ELANE and AZU1, whereas activated monocytes produce CXCL16 to create a proinflammatory milieu that disrupts nascent vasculature and promotes GMH. MG, microglia.