Neutrophil-derived interleukin-17A participates in neuroinflammation induced by traumatic brain injury.

After brain injury, infiltration and abnormal activation of neutrophils damages brain tissue and worsens inflammation, but the mediators that connect activated neutrophils with neuroinflammation have not yet been fully clarified. To identify regulators of neutrophil-mediated neuroinflammation after traumatic brain injury, a mouse model of traumatic brain injury was established by controlled cortical impact. At 7 days post-injury (sub-acute phase), genome-wide transcriptomic data showed that interleukin 17A-associated signaling pathways were markedly upregulated, suggesting that interleukin 17A may be involved in neuroinflammation. Double immunofluorescence staining showed that interleukin 17A was largely secreted by neutrophils rather than by glial cells and neurons. Furthermore, nuclear factor-kappaB and Stat3, both of which are important effectors in interleukin 17A-mediated proinflammatory responses, were significantly activated. Collectively, our findings suggest that neutrophil-derived interleukin 17A participates in neutrophil-mediated neuroinflammation during the subacute phase of traumatic brain injury. Therefore, interleukin 17A may be a promising therapeutic target for traumatic brain injury.

Tandem Mass Tag-based proteomics analysis reveals the vital role of inflammation in traumatic brain injury in a mouse model.

Proteomics is a powerful tool that can be used to elucidate the underlying mechanisms of diseases and identify new biomarkers. Therefore, it may also be helpful for understanding the detailed pathological mechanism of traumatic brain injury (TBI). In this study, we performed Tandem Mass Tag-based quantitative analysis of cortical proteome profiles in a mouse model of TBI. Our results showed that there were 302 differentially expressed proteins in TBI mice compared with normal mice 7 days after injury. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that these differentially expressed proteins were predominantly involved in inflammatory responses, including complement and coagulation cascades, as well as chemokine signaling pathways. Subsequent transcription factor analysis revealed that the inflammation-related transcription factors NF-κB1, RelA, IRF1, STAT1, and Spi1 play pivotal roles in the secondary injury that occurs after TBI, which further corroborates the functional enrichment for inflammatory factors. Our results suggest that inflammation-related proteins and inflammatory responses are promising targets for the treatment of TBI.

Genome-wide interrogation of transfer RNA-derived small RNAs in a mouse model of traumatic brain injury.

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) are a recently established family of regulatory small non-coding RNAs that modulate diverse biological processes. Growing evidence indicates that tsRNAs are involved in neurological disorders and play a role in the pathogenesis of neurodegenerative disease. However, whether tsRNAs are involved in traumatic brain injury-induced secondary injury remains poorly understood. In this study, a mouse controlled cortical impact model of traumatic brain injury was established, and integrated tsRNA and messenger RNA (mRNA) transcriptome sequencing were used. The results revealed that 103 tsRNAs were differentially expressed in the mouse model of traumatic brain injury at 72 hours, of which 56 tsRNAs were upregulated and 47 tsRNAs were downregulated. Based on microRNA-like seed matching and Pearson correlation analysis, 57 differentially expressed tsRNA-mRNA interaction pairs were identified, including 29 tsRNAs and 26 mRNAs. Moreover, Gene Ontology annotation of target genes revealed that the significantly enriched terms were primarily associated with inflammation and synaptic function. Collectively, our findings suggest that tsRNAs may be associated with traumatic brain injury-induced secondary brain injury, and are thus a potential therapeutic target for traumatic brain injury. The study was approved by the Beijing Neurosurgical Institute Animal Care and Use Committee (approval No. 20190411) on April 11, 2019.

Comparative transcriptomic analysis of rat versus mouse cerebral cortex after traumatic brain injury.

The heterogeneity of traumatic brain injury (TBI)-induced secondary injury has greatly hampered the development of effective treatments for TBI patients. Targeting common processes across species may be an innovative strategy to combat debilitating TBI. In the present study, a cross-species transcriptome comparison was performed for the first time to determine the fundamental processes of secondary brain injury in Sprague-Dawley rat and C57/BL6 mouse models of TBI, caused by acute controlled cortical impact. The RNA sequencing data from the mouse model of TBI were downloaded from the Gene Expression Omnibus (ID: GSE79441) at the National Center for Biotechnology Information. For the rat data, peri-injury cerebral cortex samples were collected for transcriptomic analysis 24 hours after TBI. Differentially expressed gene-based functional analysis revealed that common features between the two species were mainly involved in the regulation and activation of the innate immune response, including complement cascades as well as Toll-like and nucleotide oligomerization domain-like receptor pathways. These findings were further corroborated by gene set enrichment analysis. Moreover, transcription factor analysis revealed that the families of signal transducers and activators of transcription (STAT), basic leucine zipper (BZIP), Rel homology domain (RHD), and interferon regulatory factor (IRF) transcription factors play vital regulatory roles in the pathophysiological processes of TBI, and are also largely associated with inflammation. These findings suggest that targeting the common innate immune response might be a promising therapeutic approach for TBI. The animal experimental procedures were approved by the Beijing Neurosurgical Institute Animal Care and Use Committee (approval No. 201802001) on June 6, 2018.

Glucose metabolism: A link between traumatic brain injury and Alzheimer's disease.

Traumatic brain injury (TBI), a growing public health problem, is a leading cause of death and disability worldwide, although its prevention measures and clinical cares are substantially improved. Increasing evidence shows that TBI may increase the risk of mood disorders and neurodegenerative diseases, including Alzheimer's disease (AD). However, the complex relationship between TBI and AD remains elusive. Metabolic dysfunction has been the common pathology in both TBI and AD. On the one hand, TBI perturbs the glucose metabolism of the brain, and causes energy crisis and subsequent hyperglycolysis. On the other hand, glucose deprivation promotes amyloidogenesis via ß-site APP cleaving enzyme-1 dependent mechanism, and triggers tau pathology and synaptic function. Recent findings suggest that TBI might facilitate Alzheimer's pathogenesis by altering metabolism, which provides clues to metabolic link between TBI and AD. In this review, we will explore how TBI-induced metabolic changes contribute to the development of AD.

FLIM-FRET-Based Structural Characterization of a Class-A GPCR Dimer in the Cell Membrane.

Class-A G protein-coupled receptors (GPCRs) are known to homo-dimerize in the membrane. Yet, methods to characterize the structure of GPCR dimer in the native environment are lacking. Accordingly, the molecular basis and functional relevance of the class-A GPCR dimerization remain unclear. Here, we present the dimeric structural model of GPR17 in the cell membrane. The dimer mainly involves transmembrane helix 5 (TM5) at the interface, with F229 in TM5, a critical residue. An F229A mutation makes GPR17 monomeric regardless of the expression level of the receptor. Monomeric mutants of GPR17 display impaired ERK1/2 activation and cannot be properly internalized upon agonist treatment. Conversely, the F229C mutant is cross-linked as a dimer and behaves like wild-type. Importantly, the GPR17 dimer structure has been modeled using sparse inter-protomer FRET distance restraints obtained from fluorescence lifetime imaging microscopy. The same approach can be applied to characterizing the interactions of other important membrane proteins in the cell.

[Study on the Extraction, Geometry Structure and Spectral Characterization of Piperine Alkaloid].

Using pepper fruit of Hainan as raw material and 95% ethanol as solvent, the alkaloid in pepper is extracted with reflux method in this paper. The piperonylic acid is removed by adjusting the pH; the fat-soluble substance being removed by adding ethyl ether; the piperine alkaloid being purified with acetone by recrystallization anddetected with HPLC, as well as characterized with IR. The characterizations of piperine are discussed. Meanwhile, B3LYP/6-31G (d,p) method of DFT is applied to optimize the structure, calculate frequency and energy of pepper alkaloid, then obtain four kinds of configurations (configuration Ⅰ as Piperine, configuration Ⅱ as Iso Piperine, configuration Ⅲ as Iso Chavicine, configuration Ⅳ as Chavicine) with 64 kinds of stability conformational structure. The distribution of the thermodynamic equilibrium of stable conformations of four kinds of configurations of the molecular is calculated with Gibbs free energy at room temperature (298.15 K). And IR spectra of the experimental were compared with the IR spectra of the theoretical. The results show that the alkaloid extracted from pepper is mainly conformer 1 in configuration Ⅰ, that is, Piperine; after purifying, the content of piperine is 7% with the purity of 99%. With analysis, the methods of extraction, separation and purification of piperine in this paper achieve good results. Established models are in good agreement with the experimental results. This research is of great significance in guiding extracting process, building structural model and the characterization and application of piperine.

[Study of the termination of two acrylonitrile radicals and infrared spectrum].

By using the density functional theory, the study of reaction termination mechanism of two (CH3)2 (CN)C--CH2-- (CN)CH was carried out at the B3LYP/6-31G(d) level. The initiator AIBN was used. Reactants, coupled intermediates, transition states and disproportionation products were optimized at the B3LYP/6-31G(d) level. Then the total energies corrected by zero-point energy, vibrational frequencies and electronic structures were calculated, the transition states structure was also verified. The results show that it forms the energy-rich adducts a through the coupling termination. Then, the disproportionation product P[p1 (CH3)2 (CN) C-CH=CHCN + p2 (CH3)2 (CN)C-CH2-CH2CN] formed via hydrogen shift and dissociation. The reactions of coupling termination and disproportionation termination are all exothermic reactions, and the coupled product has lower energy. The rate constant of step a→TS→P k(298.15 K) = 2.71 x 10(-59) at the normal atmospheric temperature. Disproportionation termination occurs more easily with the reaction temperature rising, so the proportion of disproportionation products is increasing. Also, the analysis of infrared spectrogram of each species in reaction process shows chemical change of free radicals in the whole termination reaction. The authors give the HOMO-LUMO in this paper to verify the accuracy of biradical coupling termination and structures. It has important guiding significance to controlling the free radicals termination methods of acrylonitrile monomer.

[Theory study on glycine linear oligopeptide vibrational spectrum frequency shift].

By using the density functional theory, glycine linear oligopeptide of different lengths was geometrically optimized on the 6-31G (d) basis set level, their growth processes were simulated, and the average binding energy and vibration frequency were calculated with geometry. The results showed that the average binding energies tend to change in a regular pattern and stabilize with the number of residues increasing; With the oligopeptide chain bond length analysis it was found that the chain to the radial direction there is a opposite trend for chain and radial direction, which is anisotropic. It was found by the IR spectrum analysis that red shifts and blue shifts occur respectively when the same group of peptide bond vibrate, which is anisotropic; These phenomena originate from that quasi one-dimensional nanostructures lead to the anisotropy of the bond length; the induced effects, coupling effects and hydrogen bonding etc. between the same groups lead to the vibration frequency red shifts and blue shifts. The authors conclude that the growth of glycine linear oligopeptide is conducive to stability of the structure, and the authors infer that the oligopeptide has the tendency of self-assembled growth; Through the conformation and spectrum, the authors infer that there is a size effect in physical and chemical properties. The physical and chemical properties of peptide chain end group are extremely stable and unaffected by the impact of the oligopeptide chain length The results are significant to measuring the length and the number of residue of peptide, and to manufacturing the special features oligopeptide chain.