RIP3 deficiency protects against traumatic brain injury (TBI) through suppressing oxidative stress, inflammation and apoptosis: Dependent on AMPK pathway.

Traumatic brain injury (TBI) is a leading cause of disability and mortality in young adults worldwide. The pathophysiology is not fully understood. Programmed necrosis (necroptosis) is a newly identified mechanism of cell death combining features of both apoptosis and necrosis. Receptor-interacting protein 3 (RIP3) plays an important role in programmed necrosis. However, the effect of RIP3-related pathway in TBI is little to be known. We attempted to explore the significance of RIP3 in regulating TBI in vivo. Significantly, TBI induced over-expression of RIP3 in the hippocampus of mice, as well as RIP1 and phosphorylated mixed lineage kinase domain-like protein (MLKL). Mice after TBI exhibited cognitive dysfunction and activation of glia cells, which were significantly attenuated by RIP3-knockout (KO). Moreover, inflammation and oxidative stress in hippocampus were markedly induced by TBI in wild type (WT) mice. Of note, the reduction of pro-inflammatory cytokines and oxidants was observed in RIP3-deficient mice, which was linked to the blockage of NLR pyrin domain containing 3 (NLRP3)/apoptosis-associated speck-like protein containing a CARD (ASC)/Caspase-1 and kelch-like ECH-associated protein 1 (Keap 1) pathways. Further, TBI induced hippocampus apoptosis, evidenced by the increase of cleaved Caspase-8/-3 and poly (ADP)-ribose polymerase (PARP) in WT mice, whereas being decreased by RIP3-knockout. In addition, RIP3 knockout led to phosphorylation of AMP-activated protein kinase α (AMPKα) in hippocampus of mice after TBI. And of note, the in vitro findings indicated that RIP3-ablation attenuated oxidative stress, inflammation and apoptosis in astrocytes, which was dependent on AMPKα activation. Together, suppressing RIP3 might be served as a therapeutic target against brain injury through inhibiting inflammation, oxidative stress and apoptosis.

Magnetic Resonance Imaging of Plaque Burden in Vascular Walls of the Middle Cerebral Artery Correlates with Cerebral Infarction.

Intracranial atherosclerosis may be related to the risk of ischemic stroke. High-resolution magnetic resonance imaging (H-R MRI) makes it possible to measure the intracranial atheroma in vivo. The aim of this study was to evaluate the plaque burden of the middle cerebral artery (MCA) using H-R MRI, and to determine its relationship with both cerebral infarction size and plaque burden in the carotid artery (CA). 54 patients with MCA territory infarction were enrolled and HR-MRI was performed within 7 days following stroke onset. The lumen area (LA), wall area (WA), total vessel area (TVA), and the normalized wall index (NWI) of MCA and CA were measured. We analyzed the status of MCA and CA atheroma, and the size of cerebral infarction, in the corresponding vascular territory. We observed a significant positive correlation between the NWI of the index artery and the volume of the ipsilateral ischemic lesions. In addition, the mean NWI of MCA was significantly correlated with that of the ipsilateral CA (left, r = 0.88, P.0.001; right, r = 0.79, P.0.001), and the plaque burden of the M1 segment of MCA was significantly higher than that of the ipsilateral CA (P < 0.05). There was no significant correlation between the TVA and WA of MCA and that of CA. Our findings suggest that MCA atherosclerosis is significantly correlated with cerebral infarction. In ischemic stroke patients, the plaque burden of M1 segment of MCA is more significant than that of CA.

Photodynamic therapy mediated by 5-aminolevulinic acid suppresses gliomas growth by decreasing the microvessels.

Although 5-aminolevulinic acid (5-ALA)-mediated photodynamic therapy (PDT) has been demonstrated to be a novel and effective therapeutic modality for some human malignancies, its effect and mechanism on glioma are still controversial. Previous studies have reported that 5-ALA-PDT induced necrosis of C6 rat glioma cells in vitro. The aim of this study was to further investigate the effect and mechanism of 5-ALA-PDT on C6 gliomas implanted in rats in vivo. Twenty-four rats bearing similar size of subcutaneously implanted C6 rat glioma were randomly divided into 3 groups: receiving 5-ALA-PDT (group A), laser irradiation (group B), and mock procedures but without any treatment (group C), respectively. The growth, histology, microvessel density (MVD), and apoptosis of the grafts in each group were determined after the treatments. As compared with groups B and C, the volume of tumor grafts was significantly reduced (P<0.05), MVD was significantly decreased (P<0.001), and the cellular necrosis was obviously increased in group A. There was no significant difference in apoptosis among the three groups. The in vivo studies confirmed that 5-ALA-PDT may be an effective treatment for gliomas by inhibiting the tumor growth. The mechanism underlying may involve increasing the cellular necrosis but not inducing the cellular apoptosis, which may result from the destruction of the tumor microvessels.