Modeling Hypoxic-Ischemic Brain Injury with Infection

To model the clinical scenario of hypoxic-ischemic (HI) brain injury in the setting of Gram-negative systemic infection, lipopolysaccharide (LPS, E. coli, O55:B5, Sigma-Aldrich, St. Louis, MO, 0.05 mg/kg), a Toll-like receptor 4 (TLR4) agonist, was injected intraperitoneally (i.p.), 2.5 h prior to carotid ligation, and 1.5 h post-ligation, exposure to 50 min 8% O₂ began ^{20 (link), 35 (link)}; this protocol is designated as “LPS+HI”. To model concurrent Gram-positive systemic infection, the synthetic lipopeptide TLR2 agonist Pam₃Cys-Ser-(Lys)₄ (Pam3CSK4, PAM, Sigma-Aldrich, 0.5 mg/kg) was injected i.p. 4.5 h prior to carotid ligation, and 1.5 h post-ligation, exposure to 60 min 8% O₂ started ^{37 (link)}; this protocol is designated as “PAM+HI”.