Aneurysmal subarachnoid hemorrhage (SAH) is known as one of the most devastating diseases in the central nervous system. In the past few decades, research on SAH has focused on cerebral vasospasm to prevent post-SAH delayed cerebral ischemia (DCI) and to improve outcomes. However, increasing evidence has suggested that early brain injury (EBI) is an important mechanism contributing to DCI, cerebral vasospasm as well as poor outcomes. Though the mechanism of EBI is very complex, inflammation is thought to play a pivotal role in EBI. Galectin-3 is a unique chimera type in the galectin family characterized by its β-galactoside-binding lectin, which mediates various pathologies, such as fibrosis, cell adhesion, and inflammation. Recently, two clinical studies revealed galectin-3 to be a possible prognostic biomarker in SAH patients. In addition, our recent report suggested that higher acute-stage plasma galectin-3 levels correlated with subsequent development of delayed cerebral infarction that was not associated with vasospasm in SAH patients. We review the possible role and molecular mechanisms of inflammation as well as galectin-3 in brain injuries, especially focusing on EBI after SAH, and discuss galectin-3 as a potential new therapeutic or research target in post-SAH brain injuries.

Background: Early brain injury including neuronal apoptosis is a main contributor to neurological deterioration after subarachnoid hemorrhage (SAH). This study was aimed to investigate whether EGFR (epidermal growth factor receptor)/NFκB (nuclear factor-kappa B) inducing kinase (NIK)/NFκB (p65 and p50) pathway is involved in the neuronal apoptosis after SAH in mice. Methods: C57BL/6 adult male mice underwent endovascular perforation SAH modeling or sham-operation (n=286), and 86 mild SAH mice were excluded. In experiment 1, vehicle or an EGFR inhibitor (632.0 ng AG1478) was administered intraventricularly at 30 minutes postmodeling. At 24 or 72 hours, after neurological score was tested, brain water content, double immunolabeling with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and a neuronal marker antimicrotubule-associated protein-2 antibody, Western blotting using whole tissue lysate or nuclear protein extraction of the left cortex, and immunohistochemistry for cleaved caspase-3, phosphorylated (p-) EGFR, NIK, p-NFκB p65, and NFκB p105/50 were evaluated. In experiment 2, after sham or SAH modeling, AG1478+vehicle or AG1478+4.0 ng EGF was administered intraventricularly. The brain was used for TUNEL staining and immunohistochemistry after 24-hour observation. Results: SAH group showed deteriorated neurological score ( P <0.01, Mann-Whitney U test), more TUNEL- and cleaved caspase-3-positive neurons ( P <0.01, ANOVA), and higher brain water content ( P <0.01, Mann-Whitney U test), and these observations were improved in SAH-AG1478 group. Western blotting showed that expression levels of p-EGFR, p-p65, p50, and nuclear-NIK were increased after SAH ( P <0.05, ANOVA), and decreased by AG1478 administration. Immunohistochemistry revealed these molecules localized in degenerating neurons. EGF administration resulted in neurological deterioration, increased TUNEL-positive neurons, and activation of EGFR, NIK, and NFκB. Conclusions: Activated EGFR, nuclear-NIK, and NFκB expressions were observed in cortical degenerating neurons after SAH, and were decreased by administration of AG1478, associated with suppression of TUNEL- and cleaved caspase-3-positive neurons. EGFR/NIK/NFκB pathway is suggested to be involved in neuronal apoptosis after SAH in mice.

Some patients with Parkinson's disease (PD) develop peri-lead brain edema after deep brain stimulation (DBS) surgery. The influence of edema on neurological function is not well characterized. We investigated the relationship of brain edema after DBS surgery with motor and cognitive function. Thirteen patients with PD (6 males and 7 females; mean age: 61.2 years) who underwent bilateral subthalamic nucleus (STN) DBS surgery were included. All patients underwent magnetic resonance imaging (MRI) examination on day 6 post-DBS surgery. The volume of edema was measured either in the frontal white matter or STN on fluid attenuated inversion recovery (FLAIR) images. We examined the relationship between these volumes and changes in cognitive and motor function. Patients were divided into those with frontal subcortical edema (FE) ≥3,000 mm³ (FE + group; n = 7) and <3,000 mm³ (FE–group; n = 6). In the FE + group, the postoperative Mini-Mental State Examination score worsened by 2.4 points after one week compared with that immediately before surgery, while that in the FE-group worsened only by 0.2 points (p = 0.038). On comparing patients with peri-STN edema (SE) ≥1,000 mm³ (SE + group; n = 3) and those with SE < 1,000 mm³ (SE-group; n = 10) showed that frequency of DBS tuning in the early postoperative period of the SE + group was lesser than that in the SE-group. Development of FE after DBS surgery was related to transient cognitive decline. On the other hand, SE seemed associated with altered motor function and reduces the requirement for tuning in the initial period after DBS implantation.