• MIP2 improves neurological outcomes after collagenase-induced intracerebral hemorrhage (ICH). • MIP2 reduces hematoma volume and limits secondary brain injury by reducing oxidative stress and apoptosis. • MIP2 preserves blood–brain barrier integrity and reduces vascular leakage after ICH. • MIP2 attenuates neuroinflammation by suppressing glial activation and immune infiltration. Intracerebral hemorrhage (ICH) is a highly debilitating brain condition due to the limited availability of treatment options. MyD88 inhibitory peptide-2 (MIP2) is a broad-range TLR-targeting peptide. It provides neuroprotection by regulating neuroinflammatory and oxidative-stress responses. However, the underlying mechanisms by which MIP2 contributes to neuroinflammation remain unclear. To investigate the underlying neuroprotective, anti-inflammatory, and anti-oxidative stress-related therapeutic potential of MIP2 against secondary brain injury induced by ICH. ICH was induced by injecting collagenase into the striatum. MIP2 was administered at 0, 1, and 3 days post-ICH for subsequent behavioral and molecular analyses. Neurobehavioral function was evaluated using the focal neurological deficit score and corner test and the on days 1, 3, and 7 after ICH. Hematoma volume was measured by HE staining. Apoptosis was assessed by TUNEL staining and Evans blue assay. Tight junction proteins, MMP9, and vWF expression were investigated to assess blood–brain barrier (BBB) permeability after MIP2 treatment. To elucidate the molecular mechanism of MIP2-mediated neuroprotection, markers of neuroinflammation, glial activation, neutrophil recruitment, and oxidative stress were quantified on day 3 post-ICH using western blot, immunohistochemistry, and immunofluorescence analyses. The MIP2 treatment improved neurological function, reduced hematoma volume, and enhanced BBB integrity by upregulating tight junction proteins (ZO-1, Claudin-5, and Occludin) and lowering the expression of MMP9. MIP2 reduced neuroinflammation by suppressing glial cell activation, neutrophil infiltration, and inflammatory mediators (HO-1, MyD88, NF-κB, TLR4, and IL-1β). Moreover, MyD88 inhibitory peptide-2 increased the expression of anti-oxidative stress markers (GPX4, AIFM2, and Nrf2), likely through modulation of the MyD88-mediated signaling pathway. These findings suggest that MyD88 inhibitory peptide-2 confers neuroprotection against secondary brain injury following ICH. This therapeutic strategy preserves blood–brain barrier integrity, suppresses apoptosis, and attenuates neuroinflammation by suppressing glial activation, neutrophil infiltration, and pro-inflammatory mediators, while enhancing antioxidative defense post-ICH-mediated brain damage.
Siddique et al. (Sun,) studied this question.