Effects of hyperbaric oxygen on NLRP3 inflammasome activation in the brain after carbon monoxide poisoning.

Neuroinflammation plays an important role in brain damage after acute carbon monoxide poisoning (ACOP). The nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing (NLRP) 3 inflammasome triggers the activation of inflammatory caspases and maturation of interleukin (IL)-1ß and -18, and has been linked to various human autoinflammatory and autoimmune diseases. In this study we investigated the effects of hyperbaric oxygen (HBO2) on NLRP3 inflammasome activation after ACOP. Mice were randomly divided into four groups: sham group (exposure to normobaric air - i.e., 21% O2 at 1 atmosphere absolute); HBO2-only group; CO + normobaric air group; and CO + HBO2 group. Cognitive function was evaluated with the Morris water maze; myelin injury was assessed by FluoroMyelin GreenTM fluorescent myelin staining and myelin basic protein (MBP) immunostaining; and mRNA and protein levels of NLRP3 inflammasome complex proteins were measured by quantitative real-time PCR and Western blot, respectively. Additionally, serum and brain levels of IL-1ßß and -18 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase were determined by enzyme-linked immunosorbent assay. It was found that HBO2 improved learning and memory, and alleviated myelin injury in mice subjected to acute CO exposure. Furthermore, HBO2 decreased NLRP3, absent in melanoma 2 (AIM2), caspase-1, and apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain mRNA and protein levels, and reduced brain and serum concentrations of IL-1ß and -18 and NADPH oxidase. These results indicate that HBO2 suppresses the inflammatory response after ACOP by blocking NLRP3 inflammasome activation, thereby alleviating cognitive deficits.

GFAP-Positive Progenitor Cell Production is Concentrated in Specific Encephalic Regions in Young Adult Mice.

Previous genetic fate-mapping studies have indicated that embryonic glial fibrillary acidic protein-positive (GFAP+) cells are multifunctional progenitor/neural stem cells that can produce astrocytes as well as neurons and oligodendrocytes throughout the adult mouse central nervous system (CNS). However, emerging evidence from recent studies indicates that GFAP+ cells adopt different cell fates and generate different cell types in different regions. Moreover, the fate of GFAP+ cells in the young adult mouse CNS is not well understood. In the present study, hGFAP-Cre/R26R transgenic mice were used to investigate the lineage of embryonic GFAP+ cells in the young adult mouse CNS. At postnatal day 21, we found that GFAP+ cells mainly generated NeuN+ neurons in the cerebral cortex (both ventral and dorsal), hippocampus, and cerebellum. Strangely, these cells were negative for the Purkinje cell marker calbindin in the cerebellum and the neuronal marker NeuN in the thalamus. Thus, contrary to previous studies, our genetic fate-mapping revealed that the cell fate of embryonic GFAP+ cells at the young adult stage is significantly different from that at the adult stage.

The expression pattern of Adam10 in the central nervous system of adult mice: Detection by in situ hybridization combined with immunohistochemistry staining.

ADAM10 (a disintegrin and metalloprotease 10) is a member of the ADAMs family, which is key in the development of the nervous system, by regulating proliferation, migration, differentiation and survival of various cells, including axonal growth and myelination. Previous studies have investigated the embryonic or postnatal expression of ADAM10, however, detailed information regarding its cellular distribution in the adult stage, to the best of our knowledge, is not available. The present study investigated the expression pattern of the ADAM10 gene in the adult mouse central nervous system (CNS) using an ADAM10 complementary RNA probe for in situ hybridization (ISH). Immunohistochemical staining was used to identify the type of the ISH staining­positive cells with neuron­ or astrocyte­specific antibodies. The results of the current study demonstrated that the ADAM10 gene was predominantly expressed in the neurons of the cerebral cortex, hippocampus, thalamus and cerebellar granular cells in adult mouse CNS.

Polymorphisms in protein disulfide isomerase are associated with sporadic amyotrophic lateral sclerosis in the Chinese Han population.

Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disease that targets the motor system; it is caused by the loss of motor neurons in the spinal cord, brain stem, and cerebral cortex. However, the etiology of ALS remains unknown, although genetic factors may play an important role in its development. The purpose of this study was to investigate the association between common polymorphisms in protein disulfide isomerase (PDI) with sporadic amyotrophic lateral sclerosis (SALS) in a Chinese Han population. Two single nucleotide polymorphisms (SNPs) in P4HB (rs876016 and rs2070872) were genotyped in 322 patients with SALS and 265 control subjects using polymerase chain reaction-restriction fragment length polymorphism. Our results showed that SNPs rs876016 and rs2070872 were significantly associated with ALS. The minor allele frequencies of rs876016 (C) and rs2070872 (G) were significantly higher in patients with sporadic ALS than in control subjects (P = 0.035 and 0.003, respectively). The genotype frequencies of rs876016 and rs2070872 were significantly different between SALS patients and control subjects (genotypic P < 0.001). Individuals carrying rs876016/ rs2070872 C/G genotypes were associated with a significantly increased risk of SALS. These results suggest that common variants in PDI might contribute to the development of SALS in the Chinese Han population.

Early postnatal GFAP-expressing cells produce multilineage progeny in cerebrum and astrocytes in cerebellum of adult mice.

Early postnatal GFAP-expressing cells are thought to be immature astrocytes. However, it is not clear if they possess multilineage capacity and if they can generate different lineages (astrocytes, neurons and oligodendrocytes) in the brain of adult mice. In order to identify the fate of astroglial cells in the postnatal brain, hGFAP-Cre-ER(T2) transgenic mice were crossed with the R26R Cre reporter mouse strains which exhibit constitutive expression of ß-galactosidase (ß-gal). Mice carrying the hGFAP-Cre-ER(T2)/R26R transgene were treated with Tamoxifen to induce Cre recombination in astroglial cells at postnatal (P) day 6 and Cre recombinase-expressing cells were identified by X-gal staining. Immunohistochemical staining was used to identify the type(s) of these reporter-tagged cells. Sixty days after recombination, X-gal-positive cells in different cerebral regions of the adult mice expressed the astroglial markers Blbp and GFAP, the neuronal marker NeuN, the oligodendrocyte precursor cell marker NG2 and the mature oligodendrocyte marker CC1. X-gal-positive cells in the cerebellum coexpressed the astroglial marker Blbp, but not the granule cell marker NeuN, Purkinje cell marker Calbindin or oligodendrocyte precursor cell marker NG2. Our genetic fate mapping data demonstrated that early postnatal GFAP-positive cells possessed multilineage potential and eventually differentiated into neurons, astrocytes, and oligodendrocyte precursor cells in the cerebrum and into astrocytes (including Bergmann glia) in the cerebellum of adult mice.

Neonatal SVZ EGFP-labeled cells produce neurons in the olfactory bulb and astrocytes in the cerebral cortex by in-vivo electroporation.

Neural progenitors/stem cells (NSCs) exist in neonatal mouse subventricular zone (SVZ). To explore the differentiation of the NSCs in neonatal mouse SVZ and the distribution of the progeny cells derived from these NSCs in early adulthood, the enhanced green fluorescent protein (EGFP) plasmid was transferred into the NSCs in the lateral ventricle of newborn mice (P0) by in-vivo electroporation to trace these cells and their progeny cells. Thirty days after electroporation, histological sections of mouse brain were prepared for immunofluorescence with cell-specific antibodies to identify the type(s) of cells that were marked by EGFP. The results showed that EGFP-positive cells were distributed mainly in the olfactory bulb (OB), cortex, and SVZ, and double labeled with NeuN (neuron marker) in OB, glial fibrillary acidic protein (GFAP) (astrocyte marker) in the cortex, and Blbp and GFAP (astrocyte marker) in SVZ. However, there was no-EGFP-positive cell in the hippocampus. The present results indicate that the NSCs in SVZ of the neonatal mouse can give rise to neurons in the OB and astrocytes in the cortex in early adulthood, but not generate progeny cells residing in the hippocampus. In addition, there are still neural progenitors in SVZ until early adulthood.

Inhibition of EGFR/MAPK signaling reduces microglial inflammatory response and the associated secondary damage in rats after spinal cord injury.

BACKGROUND: Emerging evidence indicates that reactive microglia-initiated inflammatory responses are responsible for secondary damage after primary traumatic spinal cord injury (SCI); epidermal growth factor receptor (EGFR) signaling may be involved in cell activation. In this report, we investigate the influence of EGFR signaling inhibition on microglia activation, proinflammatory cytokine production, and the neuronal microenvironment after SCI. METHODS: Lipopolysaccharide-treated primary microglia/BV2 line cells and SCI rats were used as model systems. Both C225 and AG1478 were used to inhibit EGFR signaling activation. Cell activation and EGFR phosphorylation were observed after fluorescent staining and western blot. Production of interleukin-1 beta (IL-1 ß) and tumor necrosis factor alpha (TNF α) was tested by reverse transcription PCR and ELISA. Western blot was performed to semi-quantify the expression of EGFR/phospho-EGFR, and phosphorylation of Erk, JNK and p38 mitogen-activated protein kinases (MAPK). Wet-dry weight was compared to show tissue edema. Finally, axonal tracing and functional scoring were performed to show recovery of rats. RESULTS: EGFR phosphorylation was found to parallel microglia activation, while EGFR blockade inhibited activation-associated cell morphological changes and production of IL-1 ß and TNF α. EGFR blockade significantly downregulated the elevated MAPK activation after cell activation; selective MAPK inhibitors depressed production of cytokines to a certain degree, suggesting that MAPK mediates the depression of microglia activation brought about by EGFR inhibitors. Subsequently, seven-day continual infusion of C225 or AG1478 in rats: reduced the expression of phospho-EGFR, phosphorylation of Erk and p38 MAPK, and production of IL-1 ß and TNF α; lessened neuroinflammation-associated secondary damage, like microglia/astrocyte activation, tissue edema and glial scar/cavity formation; and enhanced axonal outgrowth and functional recovery. CONCLUSIONS: These findings indicate that inhibition of EGFR/MAPK suppresses microglia activation and associated cytokine production; reduces neuroinflammation-associated secondary damage, thus provides neuroprotection to SCI rats, suggesting that EGFR may be a therapeutic target, and C225 and AG1478 have potential for use in SCI treatment.