Publications by authors named "Chun Xia"

128 Publications

The Crystal Structure of the MHC Class I (MHC-I) Molecule in the Green Anole Lizard Demonstrates the Unique MHC-I System in Reptiles.

J Immunol 2021 Feb 26. Epub 2021 Feb 26.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China

The reptile MHC class I (MCH-I) and MHC class II proteins are the key molecules in the immune system; however, their structure has not been investigated. The crystal structure of green anole lizard peptide-MHC-I-β2m (pMHC-I or p-UA*0101) was determined in the current study. Subsequently, the features of p-UA*0101 were analyzed and compared with the characteristics of pMHC-I of four classes of vertebrates. The amino acid sequence identities between -UA*0101 and MHC-I from other species are <50%; however, the differences between the species were reflected in the topological structure. Significant characteristics of p-UA*0101 include a specific flip of ∼88° and an upward shift adjacent to the C terminus of the α1- and α2-helical regions, respectively. Additionally, the lizard MHC-I molecule has an insertion of 2 aa (VE) at positions 55 and 56. The pushing force from 55-56VE triggers the flip of the α1 helix. Mutagenesis experiments confirmed that the 55-56VE insertion in the α1 helix enhances the stability of p-UA*0101. The peptide presentation profile and motif of p-UA*0101 were confirmed. Based on these results, the proteins of three reptile lizard viruses were used for the screening and confirmation of the candidate epitopes. These data enhance our understanding of the systematic differences between five classes of vertebrates at the gene and protein levels, the formation of the pMHC-I complex, and the evolution of the MHC-I system.
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http://dx.doi.org/10.4049/jimmunol.2000992DOI Listing
February 2021

PLCγ1 inhibition-driven autophagy of IL-1β-treated chondrocyte confers cartilage protection against osteoarthritis, involving AMPK, Erk and Akt.

J Cell Mol Med 2021 Feb 28;25(3):1531-1545. Epub 2020 Dec 28.

Zhongshan Hospital, Xiamen University, Xiamen, China.

Previous studies identified the involvement of phosphoinositide-specific phospholipase C (PLC) γ1 in some events of chondrocytes. This study aims to investigate whether and how PLCγ1 modulates autophagy to execute its role in osteoarthritis (OA) progression. Rat normal or human OA chondrocytes were pretreated with IL-1β for mimicking or sustaining OA pathological condition. Using Western blotting, immunoprecipitation, qPCR, immunofluorescence and Dimethylmethylene blue assays, and ELISA and transmission electron microscope techniques, we found that PLCγ1 inhibitor U73122 enhanced Collagen II, Aggrecan and GAG levels, accompanied with increased LC3B-II/I ratio and decreased P62 expression level, whereas autophagy inhibitor Chloroquine partially diminished its effect. Meanwhile, U73122 dissociated Beclin1 from Beclin1-IP3R-Bcl-2 complex and blocked mTOR/ULK1 axis, in which the crosstalk between PLCγ1, AMPK, Erk and Akt were involved. Additionally, by haematoxylin and eosin, Safranin O/Fast green, and immunohistochemistry staining, we observed that intra-articular injection of Ad-shPLCγ1-1/2 significantly enhanced Collagen and Aggrecan levels, accompanied with increased LC3B and decreased P62 levels in a rat OA model induced by anterior cruciate ligament transection and medial meniscus resection. Consequently, PLCγ1 inhibition-driven autophagy conferred cartilage protection against OA through promoting ECM synthesis in OA chondrocytes in vivo and in vitro, involving the crosstalk between PLCγ1, AMPK, Erk and Akt.
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http://dx.doi.org/10.1111/jcmm.16245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875910PMC
February 2021

The Combination of CD8αα and Peptide-MHC-I in a Face-to-Face Mode Promotes Chicken γδT Cells Response.

Front Immunol 2020 23;11:605085. Epub 2020 Nov 23.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing, China.

The CD8αα homodimer is crucial to both thymic T cell selection and the antigen recognition of cytotoxic T cells. The CD8-pMHC-I interaction can enhance CTL immunity stabilizing the TCR-pMHC-I interaction and optimizing the cross-reactivity and Ag sensitivity of CD8 T cells at various stages of development. To date, only human and mouse CD8-pMHC-I complexes have been determined. Here, we resolved the pBF2*1501 complex and the cCD8αα/pBF2*1501 and cCD8αα/pBF2*0401 complexes in nonmammals for the first time. Remarkably, cCD8αα/pBF2*1501 and the cCD8αα/pBF2*0401 complex both exhibited two binding modes, including an "antibody-like" mode similar to that of the known mammal CD8/pMHC-I complexes and a "face-to-face" mode that has been observed only in chickens to date. Compared to the "antibody-like" mode, the "face-to-face" binding mode changes the binding orientation of the cCD8αα homodimer to pMHC-I, which might facilitate abundant γδT cells to bind diverse peptides presented by limited BF2 alleles in chicken. Moreover, the forces involving in the interaction of cCD8αα/pBF2*1501 and the cCD8αα/pBF2*0401 are different in this two binding model, which might change the strength of the CD8-pMHC-I interaction, amplifying T cell cross-reactivity in chickens. The coreceptor CD8αα of TCR has evolved two peptide-MHC-I binding patterns in chickens, which might enhance the T cell response to major or emerging pathogens, including chicken-derived pathogens that are relevant to human health, such as high-pathogenicity influenza viruses.
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http://dx.doi.org/10.3389/fimmu.2020.605085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7719794PMC
November 2020

PLCγ1 inhibition combined with inhibition of apoptosis and necroptosis increases cartilage matrix synthesis in IL-1β-treated rat chondrocytes.

FEBS Open Bio 2021 Feb 31;11(2):435-445. Epub 2020 Dec 31.

Zhongshan Hospital, Xiamen University, China.

Osteoarthritis (OA) is an age-related, chronic degenerative disease. With the increasing median age of the population, this disease has become an important public health problem. New, disease-modifying therapies are needed. A potential novel molecular target is phospholipase Cγ1 (PLCγ1), a critical enzyme with important functions including calcium signaling regulation and cell proliferation. In rat chondrocytes treated with IL-1β (20 ng·mL for 36 h), inhibition of PLCγ1 with U73122 (2 μm for 12 h) increased levels and expression of the cartilage matrix components Collagen2 and Aggrecan. This beneficial effect of PLCγ1 inhibition was counteracted by increased chondrocyte apoptosis and necroptosis, increased cell death, and increase levels of ROS, all potentially negative for OA. Combined treatment of IL-1β + U73122-treated chondrocytes with inhibitors of apoptosis (Z-VAD, 10 μm) and necroptosis (Nec-1, 30 μm) enhanced the increases in levels and expression of Collagen2 and Aggrecan, and prevented the increases in cell death and ROS levels. These results suggest that PLCγ1 inhibition may be a viable approach for an OA therapy, if combined with targeted inhibition of chondrocyte apoptosis and necroptosis.
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http://dx.doi.org/10.1002/2211-5463.13064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7876495PMC
February 2021

Structural and Biophysical Insights into the TCRαβ Complex in Chickens.

iScience 2020 Dec 20;23(12):101828. Epub 2020 Nov 20.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, China.

In this work, chicken HPAIV H5N1 epitope-specific TCRαβ (ch-TCRαβ) was isolated and its structure was determined. The Cα domain of ch-TCRαβ does not exhibit the typical structure of human TCRαβ, and the DE loop extends outward, resulting in close proximity between the Cα domain of ch-TCRαβ and CD3εδ/γ. The FG loop of the Cβ domain of ch-TCRαβ is shorter. The changes in the C domains of ch-TCRαβ and the difference in chicken CD3εδ/γ confirm that the complexes formed by TCRαβ and CD3εδ/γ differ from those in humans. In the chicken complex, a positively charged cleft is formed between the two CDR3 loops that might accommodate the acidic side chains of the chicken pMHC-I-bound HPAIV epitope intermediate portion oriented toward ch-TCRαβ. This is the first reported structure of chicken TCRαβ, and it provides a structural model of the ancestral TCR system in the immune synapses between T cells and antigen-presenting cells in lower vertebrates.
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http://dx.doi.org/10.1016/j.isci.2020.101828DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7711287PMC
December 2020

Crystal structure of the giant panda MHC class I complex: First insights into the viral peptide presentation profile in the bear family.

Protein Sci 2020 12 30;29(12):2468-2481. Epub 2020 Oct 30.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing, China.

The viral cytotoxic T lymphocyte (CTL) epitope peptides presented by classical MHC-I molecules require the assembly of a peptide-MHC-I-β2m (pMHC-I) trimolecular complex for T cell receptor (TCR) recognition, which is the critical activation link for triggering antiviral T cell immunity. Research on T cell immunology in the Ursidae family, especially structural immunology, is still lacking. In this study, the structure of the key trimolecular complex pMHC-I, which binds a peptide from canine distemper virus, was solved for the first time using giant panda as a representative species of Ursidae. The structural characteristics of the giant panda pMHC-I complex (pAime-128), including the unique pockets in the peptide-binding groove (PBG), were analyzed in detail. Comparing the pAime-128 to others in the bear family and extending the comparison to other mammals revealed distinct features. The interaction between MHC-I and β2m, the features of pAime-128 involved in TCR docking and cluster of differentiation 8 (CD8) binding, the anchor sites in the PBG, and the CTL epitopes of potential viruses that infect pandas were clarified. Unique features of pMHC-I viral antigen presentation in the panda were revealed by solving the three-dimensional (3D) structure of pAime-128. The distinct characteristics of pAime-128 indicate an unusual event that emerged during the evolution of the MHC system in the bear family. These results provide a new platform for research on panda CTL immunity and the design of vaccines for application in the bear family.
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http://dx.doi.org/10.1002/pro.3980DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7679963PMC
December 2020

Structural insights into the co-evolution of IL-2 and its private receptor in fish.

Dev Comp Immunol 2021 Feb 14;115:103895. Epub 2020 Oct 14.

Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, 201306, China; National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China. Electronic address:

Interleukin (IL) -2, a member of the four α-helical cytokine family, has broad regulatory roles in mediating vertebrate immune response. In mammals, IL-2 and IL-15 share a common evolutionary origin and possess overlapping but distinct functions. IL-2 and IL-15 bind to distinct private receptors for signaling. However, fish appear to possess a single IL-15Rα like gene whilst lack additional gene(s) coding for IL-2Rα. Whether the IL-2 and IL-15 interact with the same receptor in fish and how their functions and receptors have evolved are not fully understood. In this study, homologues of IL-2 and IL-2/15Rα were sequenced from a teleost species, grass carp (Ctenopharyngodon idella), and the crystal structure of IL-2 was determined. The grass carp IL-2 (termed CiIL-2) displayed a classical cytokine structure consisting of four helical bundles which shares significant similarity with human IL-15. The key amino acids involved in the interface interaction of IL-2/15 and their receptors are well conserved. The CiIL-2 has been shown to bind the IL-2/15Rα like homologue with an affinity of 2.45 nM, supporting the notion that fish IL-2 and IL-15 may share a single common private receptor for exerting functions. Syntenic analysis suggests that the IL-2Rα of tetrapods has evolved from an IL-15Rα like homologue, in which a second sushi domain (D2) in the extracellular region has been duplicated to facilitate the specific interaction with IL-2. The CiIL-2 was predominantly expressed in lymphocyte-rich tissues such as the spleen, kidney and thymus, and could be induced by PHA and IL-21. In vivo challenge with grass carp reovirus and Flavobacterium columnare also resulted in upregulation of CiIL-2 expression. The recombinant CiIL-2 was shown to activate expression of STAT5b, IL-1β, IL-22 and IFN-γ, and to promote the proliferation of the primary cell cultures from head kidney leucocytes. Our results shed lights into the co-evolution of IL-2 and its private receptor, and the functional divergence of IL-2 and IL-15 during evolution.
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http://dx.doi.org/10.1016/j.dci.2020.103895DOI Listing
February 2021

Suppressing PLCγ1 enhances osteogenic and chondrogenic potential of BMSCs.

Biochem Biophys Res Commun 2020 Nov 29;532(2):292-299. Epub 2020 Aug 29.

Bone & Joint Research Institute, Zhongshan Hospital, Xiamen University, Xiamen, Fujian, 361004, China. Electronic address:

Phosphatidylcholine-specific phospholipase Cγ1 (PLCγ1) is involved in regulating cell metabolism. However, little is known how PLCγ1 directs BMSC differentiation. Here, we investigated the role of PLCγ1 in rat BMSC differentiation into osteoblasts and chondrocytes. The results of Alizarin red and Alcian blue staining showed that PLCγ1 inhibitor U73122 significantly enhanced the mineralization capacity and proteoglycan deposition of BMSCs. The results of qPCR technique and Western blot analysis showed that long-term treatment of U73122 enhanced COL1A1 and OPG mRNA levels and Collagen 1A1, BMP2, and p-Smad1/5/9 protein levels and that short-term treatment of U73122 enhanced COL2A1 and SOX9 mRNA levels and Collagen 2, SOX9, Aggrecan, TGF-β3, and p-Smad2/3 protein levels. Decreased p-mTOR and p-P38 contributed to enhanced osteogenic potentials of BMSCs and increased p-P38 contributed to enhanced chondrogenic potentials of BMSCs. The scaffold transplantation with U73122+BMSC was more efficacious than BMSC alone for osteochondral defect repair in a rat model. Therefore, suppressing PLCγ1 could improve the capacity to effectively use BMSCs for cell therapy of osteochondral defect.
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http://dx.doi.org/10.1016/j.bbrc.2020.08.049DOI Listing
November 2020

The Mechanism of β2m Molecule-Induced Changes in the Peptide Presentation Profile in a Bony Fish.

iScience 2020 May 30;23(5):101119. Epub 2020 Apr 30.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. Electronic address:

Contemporary antigen presentation knowledge is based on the existence of a single β2m locus, and a classical MHC class I forms a complex with a peptide (i.e., pMHC-I) to trigger CTL immunity. However, two β2m loci have been found in diploid bony fish; the function of the two β2m molecules is unclear. Here, we determined the variant peptide profiles originating from different products of the β2m loci binding to the same MHC-I molecule and further solved the crystal structures of the two pMHC-I molecules (i.e., pCtid-UAA-β2m-2 and pCtid-UAA-β2m-1-II). Of note, in pCtid-UAA-β2m-2, a unique hydrogen bond network formed in the bottom of the peptide-binding groove (PBG) led to α2-helix drift, ultimately leading to structural changes in the PBG. The mechanism of the change in peptide presentation profiles by β2m molecules is illustrated. The results are also of great significance for antivirus and antitumor functions in cold-blooded vertebrates and even humans.
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http://dx.doi.org/10.1016/j.isci.2020.101119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240133PMC
May 2020

Phosphoinositide specific phospholipase Cγ1 inhibition-driven autophagy caused cell death in human lung adenocarcinoma A549 cells and .

Int J Biol Sci 2020 21;16(8):1427-1440. Epub 2020 Feb 21.

Cancer Research Center, School of Medicine, Xiamen University, 361102, Fujian, China.

Our previous studies indicated that phosphoinositide specific phospholipase Cγ1 (PLCγ1) was involved in autophagy induction in colon and hepatic carcinoma cells. However, whether and how PLCγ1 regulation in human lung adenocarcinoma is linked to autophagy remains unclear. Here, we assessed the protein expression of PLCγ1 in human lung adenocarcinoma tissue using immunohistochemistry assay and the relationship between PLCG1 and autophagy in The Cancer Genome Atlas Network (TCGA) using Spearman correlation analysis and GSEA software. Furthermore, the interaction between PLCγ1 and autophagy-related signal molecules was investigated in human lung adenocarcinoma A549 cells treated with different inhibitors or transduction with lentivirus-mediated PLCγ1 gene short-hairpin RNA (shRNA) vectors using MTT, clonogenicity, Transwell migration, RT-PCR, Caspase-3, mitochondrial transmembrane potential, and western blotting assays, as well as transmission electron microscope technique. Additionally, the effect of shRNA/PLCγ1 alone or combined with autophagic activator Lithium Chloride (LiCl) on tumor growth and metastasis was measured using immunohistochemistry and assays in A549 xenograft nude mouse model. The results showed that increased PLCγ1 expression occurred frequently in human lung adenocarcinoma tissue with higher grades of T in TNM staging classification. PLCγ1 significantly enriched in autophagic process and regulation, which negatively regulating autophagy was enriched in higher expression of PLCγ1. PLCγ1 inhibition partially reduced cell proliferation and migration of A549 cells, with an increased autophagic flux involving alterations of AMPKα, mTOR, and ERK levels. However, PLCγ1 inhibition-driven autophagy led to cell death without depending on Caspase-3 and RIP1. Additionally, the abrogation of PLCγ1 signaling by shRNA and combination with autophagic activator LiCl could efficaciously suppress tumor growth and metastasis in A549 xenograft nude mice, in combination with a decrease in P62 level. These findings collectively suggest that reduction of cell proliferation and migration by PLCγ1 inhibition could be partially attributed to PLCγ1 inhibition-driven autophagic cell death (ACD). It highlights the potential role of a combination between targeting PLCγ1 and autophagy pathway in anti-tumor therapy, which may be an efficacious new strategy to overcome the autophagy addition of tumor and acquired resistance to current therapy.
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http://dx.doi.org/10.7150/ijbs.42962DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7085223PMC
February 2020

Characterization and a RT-RPA assay for rapid detection of Chilli Veinal mottle virus (ChiVMV) in tobacco.

Virol J 2020 03 10;17(1):33. Epub 2020 Mar 10.

College of Plant Protection, Shenyang Agricultural University, Shenyang, 110866, China.

Background: Chilli veinal mottle virus (ChiVMV), which belongs to the genus Potyvirus of the family Potyviridae, mainly infects solanaceous plants and has caused serious economic losses in Asia and Africa. Tobacco plants infected with ChiVMV suffered from punctate necrosis of leaves, leaf deformation, systemic necrosis of leaves and stems, and eventually plant death. However, ChiVMV infection could not usually be identified given the lack of rapid and efficient detection assays in tobacco plants. Therefore, an isolate of tobacco-infecting ChiVMV (ChiVMV-LZ) was obtained, and a novel isothermal amplification and detection technique, reverse transcription-recombinase polymerase amplification (RT-RPA), was established to detect ChiVMV in tobacco plants.

Methods: In this study, the full-length genome of ChiVMV-LZ was obtained using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) assays. The genome sequence of ChiVMV-LZ was characterized by sequence alignment and phylogenetic analysis. Then, a RT-RPA assay was established for rapid and sensitive detection of ChiVMV-LZ in tobacco. Additionally, the established RT-RPA assay was compared to the RT-PCR assay in aspect of sensitivity and application in field-collected tobacco samples.

Results: ChiVMV-LZ was isolated from diseased tobacco in Luzhou, Sichuan, China. The tobacco plants inoculated with ChiVMV-LZ showed typical symptoms of yellow and round spots on the leaves, and curled and folded leaf margin, similar to those observed on naturally ChiVMV-infected tobacco in the field. The full-length genomic sequence of ChiVMV-LZ was determined to be 9742 nucleotides. Sequence alignment and phylogenetic analysis showed that ChiVMV-LZ was most closely related to ChiVMV-Yp8 isolated from pepper plants in Sichuan province while distantly related to ChiVMV-YN from tobacco in Yunnan province, indicating a possibly geographical differentiation of ChiVMV isolates. Additionally, a RT-RPA assay was established for rapid detection of ChiVMV in tobacco. The RT-RPA has no cross-reaction with other related tobacco viruses and is about 10-fold more sensitive than conventional RT-PCR method.

Conclusion: The characterization of ChiVMV-LZ infecting tobacco was determined, and the established RT-RPA assay provides a reliable and effective method for rapid detection of ChiVMV in tobacco.
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http://dx.doi.org/10.1186/s12985-020-01299-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065361PMC
March 2020

Structures of the MHC-I molecule BF2*1501 disclose the preferred presentation of an H5N1 virus-derived epitope.

J Biol Chem 2020 04 9;295(16):5292-5306. Epub 2020 Mar 9.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, People's Republic of China

Lethal infections by strains of the highly-pathogenic avian influenza virus (HPAIV) H5N1 pose serious threats to both the poultry industry and public health worldwide. A lack of confirmed HPAIV epitopes recognized by cytotoxic T lymphocytes (CTLs) has hindered the utilization of CD8 T-cell-mediated immunity and has precluded the development of effectively diversified epitope-based vaccination approaches. In particular, an HPAIV H5N1 CTL-recognized epitope based on the peptide MHC-I-β2m (pMHC-I) complex has not yet been designed. Here, screening a collection of selected peptides of several HPAIV strains against a specific pathogen-free pMHC-I (pBF2*1501), we identified a highly-conserved HPAIV H5N1 CTL epitope, named HPAIV-PA We determined the structure of the BF2*1501-PA complex at 2.1 Å resolution to elucidate the molecular mechanisms of a preferential presentation of the highly-conserved PA epitope in the chicken B15 lineage. Conformational characteristics of the PA epitope with a protruding Tyr-7 residue indicated that this epitope has great potential to be recognized by specific TCRs. Moreover, significantly increased numbers of CD8 T cells specific for the HPAIV-PA epitope in peptide-immunized chickens indicated that a repertoire of CD8 T cells can specifically respond to this epitope. We anticipate that the identification and structural characterization of the PA epitope reported here could enable further studies of CTL immunity against HPAIV H5N1. Such studies may aid in the development of vaccine development strategies using well-conserved internal viral antigens in chickens.
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http://dx.doi.org/10.1074/jbc.RA120.012713DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7170506PMC
April 2020

Lithium-Oxygen Batteries and Related Systems: Potential, Status, and Future.

Chem Rev 2020 Jul 5;120(14):6626-6683. Epub 2020 Mar 5.

Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel.

The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal-air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal-air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li-O cells but include Na-O, K-O, and Mg-O cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li-O cells.
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http://dx.doi.org/10.1021/acs.chemrev.9b00609DOI Listing
July 2020

Comparison of hemocoagulase atrox versus tranexamic acid used in primary total knee arthroplasty: A randomized controlled trial.

Thromb Res 2020 04 4;188:39-43. Epub 2020 Feb 4.

Zhongshan Hospital, Xiamen University, Fujian 361004, China. Electronic address:

Background: Total knee arthroplasty (TKA) has been considered as an effective choice for end-stage osteoarthritis or rheumatic arthritis. Tranexamic acid (TXA) has been widely used to prevent excessive blood loss perioperatively. Similarly, hemocoagulase atrox can significantly diminish blood loss and transfusion requirements in surgeries, however, it was rarely used in TKA. The purpose of this study is to identify whether hemocoagulase atrox is equal to TXA in reducing blood loss and transfusion rates following TKA, and compare clinical outcomes and complications between the two groups.

Methods: 74 patients were randomized to receive TXA (1.5 g intra-articular combined with 1.5 g intravenous), or hemocoagulase atrox (1 U intra-articular combined with 1 U intravenous). The primary outcome was total blood loss. The secondary outcomes included reduction of hemoglobin concentration, clinical outcomes, blood coagulation values, thromboembolic complications, and transfusion rates.

Results: The mean total blood loss was 431.7 mL in the TXA group compared with 644.6 mL in the hemocoagulase atrox group, with statistical significance (P < 0.05). There were significant differences in reduction of hemoglobin level (P < 0.05). The rate of deep vein thrombosis (DVT) in patients given TXA was higher than those given hemocoagulase atrox, however, there were no significant differences. No transfusions were required in either group, and no significant differences were found in the length of hospital stay and clinical outcomes.

Conclusions: Although the blood loss was significantly greater in the hemocoagulase atrox group, no transfusions were required and no significant differences were observed for any other outcomes measured. Meanwhile, the rate of DVT in the hemocoagulase atrox group tends to be lower than those in TXA group. We concluded that hemocoagulase atrox was not superior to TXA in reducing perioperative blood loss. Further studies are warranted to evaluate if hemocoagulase atrox use could improve perioperative blood loss in patients with high thrombotic risk undergoing TKA.
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http://dx.doi.org/10.1016/j.thromres.2020.02.001DOI Listing
April 2020

A Newly Recognized Pairing Mechanism of the α- and β-Chains of the Chicken Peptide-MHC Class II Complex.

J Immunol 2020 03 7;204(6):1630-1640. Epub 2020 Feb 7.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, China; and

MHC class II (MHC-II) molecules play a crucial role in cellular and humoral immunity by forming peptide-MHC-II (pMHC-II) complexes. The three-dimensional structures of pMHC-II complexes have been well resolved in humans and mice. However, there is no structural information for pMHC-II complexes in nonmammals. In chickens, there are two closely related and highly polymorphic β-chains and one monomorphic α-chain, and the mechanism by which one monomorphic α-chain combines with two polymorphic β-chains to form a functional heterodimer remains unknown. In this study, we report the crystal structure of a chicken pMHC-II complex (pBL2*019:01) at 1.9-Å resolution as the first nonmammalian structure of a pMHC-II complex. The structure reveals an increase in hydrogen bonding between the α and β main chains at the central interface that is introduced by the insertion of four residues in the α-chain. The residues in the β-chain that form hydrogen bonds with the α-chain are conserved among all β alleles. These structural characteristics explain the phenomenon of only one allele without sequence variation pairing with highly diverse alleles from two loci in the genome. Additionally, the characteristics of the peptide in the peptide-binding groove were confirmed. These results provide a new understanding of the pairing mechanism of the α- and β-chains in a pMHC-II complex and establish a structural principle to design epitope-related vaccines for the prevention of chicken diseases.
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http://dx.doi.org/10.4049/jimmunol.1901305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7061270PMC
March 2020

Illumination of PRRSV Cytotoxic T Lymphocyte Epitopes by the Three-Dimensional Structure and Peptidome of Swine Lymphocyte Antigen Class I (SLA-I).

Front Immunol 2019 8;10:2995. Epub 2020 Jan 8.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing, China.

To investigate CTL epitope applications in swine, SLA-11502-restricted peptide epitopes matching porcine reproductive and respiratory syndrome virus (PRRSV) strains were explored by crystallography, biochemistry, and the specific pathogen-free (SPF) swine experiments. First, nine predicted PRRSV peptides were tested by assembly of the peptide-SLA-11502 (pSLA-11502) complexes, and the crystal structure of the SLA-11502 complex with one peptide (NSP9-TMP9) was determined. The NSP9-TMP9 peptide conformation presented by pSLA-11502 is different from that of the peptides presented by the known pSLA-10401 and pSLA-3hs0202 complexes. Two consecutive Pro residues make the turn between P3 and P4 of NSP9-TMP9 much sharper. The D pocket of pSLA-11502 is unique and is important for peptide binding. Next, the potential SLA-11502-restricted peptide epitopes matching four typical genetic PRRSV strains were identified based on the peptide-binding motif of SLA-11502 determined by structural analysis and alanine scanning of the NSP9-TMP9 peptide. The tetrameric complex of SLA-11502 and NSP9-TMP9 was constructed and examined. Finally, taking NSP9-TMP9 as an example, the CTL immunogenicity of the identified PRRSV peptide epitope was evaluated. The SPF swine expressing the SLA-11502 alleles were divided into three groups: modified live vaccine (MLV), MLV+NSP9-TMP9, and the blank control group. NSP9-TMP9 was determined as a PRRSV CTL epitope with strong immunogenicity by flow cytometry and IFN-γ expression. Our study developed an integrated approach to identify SLA-I-restricted CTL epitopes from various important viruses and is helpful in designing and applying effective peptide-based vaccines for swine.
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http://dx.doi.org/10.3389/fimmu.2019.02995DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960135PMC
November 2020

Clinical value of CTLA4-associated microRNAs combined with inflammatory factors in the diagnosis of non-small cell lung cancer.

Ann Clin Biochem 2020 03 23;57(2):151-161. Epub 2020 Jan 23.

Department of Clinical Laboratory, Wuchang Hospital Affiliated to Wuhan University of Science and Technology, Wuhan, China.

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http://dx.doi.org/10.1177/0004563220901564DOI Listing
March 2020

Construction and analysis of finite element model of defected articular cartilage.

Saudi J Biol Sci 2020 Jan 25;27(1):556-560. Epub 2019 Nov 25.

Department of Joint Surgery & Sports Medicine, Zhongshan Hospital Xiamen University, Xiamen 361004, China.

In order to construct a finite element model of defected articular cartilage, the mechanical behavior and degeneration of articular cartilage after injury were studied. The simplified analytical models of normal and defected articular cartilage and finite element models were established, respectively. Firstly, the analytical solution model and finite element model of hollow defect were constructed by using the elasticity theory of multi-hollow medium. Then, the analytical results of each model were calculated and programmed. The software MATLAB was used for programming calculation. Finally, a finite element solid model of defected articular cartilage was established by using human femoral joint. The solid model was analyzed and calculated by magnetic resonance imaging (MRI). The results showed that when the radius of articular cartilage defect r = 0, i.e. there was no defect in articular cartilage, the internal pore pressure of the defect cartilage was the largest, and its pore pressure value was pa. When the depth of articular cartilage defect r = 0, i.e. there was no defect in articular cartilage, the internal pore pressure of the defect cartilage was the largest, and its pore pressure value was pa, and it gradually decreased towards the outer boundary of cartilage. When the surface of femoral cartilage began to defect, with the increase of the depth of the defect (from shallow to deep), the maximum pore pressure in the defect cartilage gradually decreased, but the speed is slowly. With the increase of the defect radius, that is, the area of the defect, the maximum pore pressure in the defect cartilage gradually decreased. When there was no defect of articular cartilage, the internal pore pressure of the defect cartilage was the maximum, the value of pore pressure was pa, the value of pore pressure at the contact position of femoral cartilage was the largest, and it gradually decreased towards the outer boundary of cartilage. At the same location, the pore pressure of normal cartilage was significantly higher than that of defected cartilage. With the change of defect location, the pore pressure was reduced accordingly. Moreover, when the defect position moved from the outside to the inside, the corresponding pore pressure value was decreased gradually. To sum up, the finite element model of defected articular cartilage based on porous elasticity theory has better calculation ability, which proves the validity of the finite element software, and provides a strong basis for future model establishment and clinical treatment of articular cartilage.
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http://dx.doi.org/10.1016/j.sjbs.2019.11.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6933165PMC
January 2020

Investigation of ion-ion interaction effects on Yb-doped fiber amplifiers.

Opt Express 2019 Sep;27(20):28179-28193

Ytterbium (Yb)-doped materials have been widely used for high efficiency high energy laser sources at the 1 µm wavelength region because of their very low quantum defect and the unique simple energy level structure of Yb, resulting in no excited-state absorption and low occurrence probability of deleterious ion-ion interaction processes. It has been generally recognized that these ion-ion interaction processes have very little influence on the operation of Yb-doped fiber lasers at low and moderate power levels. However, our recent study shows that the performance of Yb-doped fiber amplifiers operating at low power levels is still influenced by the ion-ion interaction processes due to the large amount of population at the upper laser level F. In this paper, experimental evidences of the ion-ion interaction effects in Yb-doped fiber amplifiers are presented and a new model including these effects is developed for the numerical simulation. Our experimental and numerical investigations on the 976 nm and 1030 nm Yb-doped silica and phosphate fiber amplifiers show that ion-ion interaction has non-negligible impact on the performance of Yb-doped fiber amplifiers indeed, and compared to Yb-doped silica fibers, Yb-doped phosphate fibers suffer much less from the ion-ion interaction effects due to the much less clustered ions.
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http://dx.doi.org/10.1364/OE.27.028179DOI Listing
September 2019

Intra-articular Injection of Kartogenin-Incorporated Thermogel Enhancing Osteoarthritis Treatment.

Front Chem 2019 18;7:677. Epub 2019 Oct 18.

Department of Joint Surgery and Sports Medicine, Xiamen University Zhongshan Hospital, Xiamen, China.

To provide a vehicle for sustained release of cartilage-protective agent for the potential application of osteoarthritis (OA) treatment, we developed a kartogenin (KGN)-incorporated thermogel for intra-articular injection. We fabricated a poly(lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) thermogel as a KGN carrier for IA injection. OA chondrocytes were cultured in thermogel with or with no KGN to investigate the effect of KGN thermogel on cartilage matrix. The effect of KGN thermogel on OA was examined in a rabbit OA model. The KGN thermogel showed a sustained release of KGN for 3 weeks. OA chondrocytes proliferated well both in thermogel and KGN thermogel. In addition, OA chondrocytes produced higher amount of [type 2 collagen (COL-2) and glycosaminoglycan (GAG)], as well as lower level of matrix metalloproteinase 13 (MMP-13) in KGN thermogel that those in thermogel with no addition of KGN. The gene analysis supported that KGN thermogel enhanced expression of hyaline-cartilage specific genes Col 2 and AGC, and inhibited the expression of MMP-13. Compared with intra-articular injection of saline or thermogel containing no KGN, KGN thermogel can enhance cartilage regeneration and inhibit joint inflammation of arthritic knees in a rabbit ACLT-induced OA model at 3 weeks after the injection. Therefore, the KGN-incorporated PLGA-PEG-PLGA thermogel may provide a novel treatment modality for OA treatment with IA injection.
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http://dx.doi.org/10.3389/fchem.2019.00677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6813204PMC
October 2019

Clinical characteristics and biomarkers of coronary microvascular dysfunction and obstructive coronary artery disease.

J Int Med Res 2019 Dec 9;47(12):6149-6159. Epub 2019 Aug 9.

Department of Cardiovascular Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.

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http://dx.doi.org/10.1177/0300060519859134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7045648PMC
December 2019

IL-1β receptor antagonist (IL-1Ra) combined with autophagy inducer (TAT-Beclin1) is an effective alternative for attenuating extracellular matrix degradation in rat and human osteoarthritis chondrocytes.

Arthritis Res Ther 2019 07 10;21(1):171. Epub 2019 Jul 10.

Zhongshan Hospital, Xiamen University, Xiamen, 361004, Fujian, China.

Background: Autophagy induction is an effective approach for OA therapy. IL-1β is one of the major inflammatory cytokines linked to OA pathological progression, and its receptor blockade interrupts OA cartilage destruction. The objective of this study was to decipher the link between autophagy and regulatory mechanism of IL-1β and to investigate the effect of IL-1β receptor blockade by IL-1 receptor antagonist (IL-1Ra) combined with or without an autophagy inducer (TAT-Beclin1) on extracellular matrix (ECM) in OA chondrocytes in vitro and in vivo.

Methods: IL-1β-treated rat and human OA chondrocytes were cultured in response to IL-1Ra. The expression and distribution of signal molecules regulating ECM synthesis and autophagy were investigated via western blotting, immunoprecipitation, real-time PCR, immunofluorescence, and transmission electron microscope technique. Furthermore, after intra-articular injection of IL-1Ra, TAT-Beclin1, and a combination of both in a rat OA model established by anterior cruciate ligament transection and medial meniscus resection, the morphological changes of cartilage and related signal molecule expression levels were monitored using H.E., Safranin O-Fast green, and immunohistochemistry staining.

Results: Reduced autophagy by IL-1β contributed to ECM degradation, and blockade of IL-1β by IL-1Ra restored autophagy and attenuated ECM degradation in rat and human OA chondrocytes, as well as in a rat OA model. Akt/mTOR/ULK1, Akt/mTOR/NF-κB, and LC3B deacetylation were involved in autophagy regulated by IL-1β. Intra-articular injection of IL-1Ra combined with TAT-Beclin1 was more effective than IL-1Ra alone.

Conclusions: IL-1Ra restored autophagy and attenuated ECM degradation, with an implication that blocking IL-1β combined with enhancing autophagy might be a potential therapeutic strategy for OA.
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http://dx.doi.org/10.1186/s13075-019-1952-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6617669PMC
July 2019

Structure and Peptidome of the Bat MHC Class I Molecule Reveal a Novel Mechanism Leading to High-Affinity Peptide Binding.

J Immunol 2019 06 10;202(12):3493-3506. Epub 2019 May 10.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100094, China;

Bats are natural reservoir hosts, harboring more than 100 viruses, some of which are lethal to humans. The asymptomatic coexistence with viruses is thought to be connected to the unique immune system of bats. MHC class I (MHC I) presentation is closely related to cytotoxic lymphocyte immunity, which plays an important role in viral resistance. To investigate the characteristics of MHC I presentation in bats, the crystal structures of peptide-MHC I complexes of , Ptal-N*01:01/HEV-1 (DFANTFLP) and Ptal-N*01:01/HEV-2 (DYINTNLVP), and two related mutants, Ptal-N*01:01/HEV-1 (DFANTFLL) and Ptal-N*01:01/HEV-1, were determined. Through structural analysis, we found that Ptal-N*01:01 had a multi-Ala-assembled pocket B and a flexible hydrophobic pocket F, which could accommodate variable anchor residues and allow Ptal-N*01:01 to bind numerous peptides. Three sequential amino acids, Met, Asp, and Leu, absent from the α1 domain of the H chain in other mammals, were present in this domain in the bat. Upon deleting these amino acids and determining the structure in p/Ptal-N*01:01/HEV-1, we found they helped form an extra salt-bridge chain between the H chain and the N-terminal aspartic acid of the peptide. By introducing an MHC I random peptide library for de novo liquid chromatography-tandem mass spectrometry analysis, we found that this insertion module, present in all types of bats, can promote MHC I presentation of peptides with high affinity during the peptide exchange process. This study will help us better understand how bat MHC I presents high-affinity peptides from an extensive binding peptidome and provides a foundation to understand the cellular immunity of bats.
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http://dx.doi.org/10.4049/jimmunol.1900001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6545463PMC
June 2019

Fabrication of high-aspect-ratio structures using Bessel-beam-activated photopolymerization.

Appl Opt 2019 May;58(13):D91-D97

Microfabrication based on photopolymerization is typically achieved by scanning a focal spot within the material point by point, which significantly limits fabrication speed. In this paper, we explore a method for rapid fabrication of high-aspect-ratio microstructures based on photopolymerization using a femtosecond laser beam that is converted into a Bessel beam by an axicon. With stationary exposure, a polymer fiber measured at 200 μm in length and 400 nm in width (500∶1 aspect ratio) was fabricated within 50 ms of exposure time. The exposure conditions can be adjusted to produce fibers with variable widths. A phenomenological polymerization-threshold model is adapted for Bessel-beam exposure. The revised model is applied to analyze the structure width and estimate the order of multi-photon absorption. Examination of the cross section of the fibers shows that they are nearly monolithic, suggesting that active species diffuse during photopolymerization. By scanning the Bessel beam in the plane transverse to the direction of beam propagation, mesh structures are fabricated with a single-pass scan, showing the potential of this method for rapid fabrication of large-scale high-aspect-ratio microstructures for applications in photonics, micro-machines, and tissue engineering.
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http://dx.doi.org/10.1364/AO.58.000D91DOI Listing
May 2019

Distribution of ancient α1 and α2 domain lineages between two classical MHC class I genes and their alleles in grass carp.

Immunogenetics 2019 05 2;71(5-6):395-405. Epub 2019 Apr 2.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing, China.

Major histocompatibility complex (MHC) class I molecules play a crucial role in the immune response by binding and presenting pathogen-derived peptides to specific CD8 T cells. From cDNA of 20 individuals of wild grass carp (Ctenopharyngodon idellus), we could amplify one or two alleles each of classical MHC class I genes Ctid-UAA and Ctid-UBA. In total, 27 and 22 unique alleles of Ctid-UAA and Ctid-UBA were found. The leader, α1, transmembrane and cytoplasmic regions distinguish between Ctid-UAA and Ctid-UBA, and their encoded α1 domain sequences belong to the ancient lineages α1-V and α1-II, respectively, which separated several hundred million years ago. However, Ctid-UAA and Ctid-UBA share allelic lineage variation in their α2 and α3 sequences, in a pattern suggestive of past interlocus recombination events that transferred α2+α3 fragments. The allelic Ctid-UAA and Ctid-UBA variation involves ancient variation between domain lineages α2-I and α2-II, which in the present study was dated back to before the ancestral separation of teleost fish and spotted gar (> 300 million years ago). This is the first report with compelling evidence that recombination events combining different ancient α1 and α2 domain lineages had a major impact on the allelic variation of two different classical MHC class I genes within the same species.
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http://dx.doi.org/10.1007/s00251-019-01111-2DOI Listing
May 2019

Application of multiple chemical and biological approaches for quality assessment of Carthamus tinctorius L. (safflower) by determining both the primary and secondary metabolites.

Phytomedicine 2019 May 9;58:152826. Epub 2019 Jan 9.

Tianjin State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, 312 Anshanxi Road, Tianjin 300193, China; Shanghai Research Center for Modernization of Traditional Chinese Medicine, National Engineering Laboratory for TCM Standardization Technology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Haike Road, Shanghai 201203, China. Electronic address:

Background: The florets of Carthamus tinctorius L. (safflower) serve as the source of a reputable herbal medicine targeting gynecological diseases. Conventional investigations regarding the quality control of safflower, however, mainly focused on the secondary metabolites with primary metabolites ignored.

Purpose: To holistically evaluate the quality difference of safflower samples collected from five different producing regions by multiple chemical and biological approaches with both the primary and secondary metabolites considered.

Methods: A precursor ions list-triggered data-dependent MS approach was established by ultra-high performance liquid chromatography/Q-Orbitrap mass spectrometry (UHPLC/Q-Orbitrap MS) to comprehensively identify the secondary metabolites from safflower. Primary metabolites were identified by various 1D and 2D nuclear magnetic resonance (NMR) experiments. Similarity evaluation and quantitative assays of all the characterized primary metabolites and a quinochalcone C-glycoside (QCG) marker, hydroxysafflor yellow A (HSYA), were performed by quantitative H NMR (qNMR) using an external standard method. Multiple in vitro models with respect to the antioxidant, anti-platelet aggregation, and antioxidant stress injury effects, were assayed to determine the efficacy differences.

Results: Totally thirteen primary metabolites (including one nucleoside, two sugars, five organic alkali/acids, and five amino acids) and 135 secondary metabolites (97 QCGs and 38 flavonoids) could be identified or tentatively characterized from safflower. Good chemical consistency was observed between the commercial safflower samples and a standard safflower sample, with similarity varying in the range of 0.95‒0.99. The results from qNMR-oriented quantitative experiments (thirteen primary metabolites and HSYA) and biological assays indicated the quality of safflower samples from Xinjiang (XJ-2 and XJ-4), Hunan (HuN-1 and HuN-2), and Sichuan (SC), was comparable to the standard safflower sample.

Conclusion: The integration of multiple chemical (using two analytical platforms, UHPLC/Q-Orbitrap MS and NMR) and biological (four in vitro models) approaches by determining both the primary and secondary metabolites demonstrated a powerful strategy that could facilitate the holistic quality evaluation of traditional Chinese medicine.
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http://dx.doi.org/10.1016/j.phymed.2019.152826DOI Listing
May 2019

Chondroprotection of PPARα activation by WY14643 via autophagy involving Akt and ERK in LPS-treated mouse chondrocytes and osteoarthritis model.

J Cell Mol Med 2019 04 7;23(4):2782-2793. Epub 2019 Feb 7.

Zhongshan Hospital, Xiamen University, Xiamen, Fujian, China.

Autophagy maintains cellular homoeostasis. The enhancement of autophagy in chondrocytes could prevent osteoarthritis (OA) progression in articular cartilage. Peroxisome proliferator-activated receptor α (PPARα) activation may also protect articular chondrocytes against cartilage degradation in OA. However, whether the protective effect of activated PPARα is associated with autophagy induction in chondrocytes is not determined. In this study, we investigated the effect of PPARα activation by its agonist, WY14643, on the protein expression level of Aggrecan and ADAMTS5, and the protein expression level of autophagy biomarkers, including LC3B and P62, using Western blotting analysis in isolated mouse chondrocytes pre-treated with lipopolysaccharides (LPS, mimicking OA chondrocytes) with or without the autophagy inhibitor chloroquine diphosphate salt. Furthermore, Akt and ERK phosphorylation was detected in LPS-treated chondrocytes in response to WY14643. In addition, the effect of intra-articularly injected WY14643 on articular cartilage in a mouse OA model established by the destabilization of the medial meniscus was assessed using the Osteoarthritis Research Society International (OARSI) histopathology assessment system, along with the detection of Aggrecan, ADAMTS5, LC3B and P62 protein levels using immunohistochemistry assay. The results indicated that PPARα activation by WY14643 promoted proteoglycan synthesis by autophagy enhancement in OA chondrocytes in vivo and in vitro concomitant with the elevation of Akt and ERK phosphorylation. Therefore, autophagy could contribute to the chondroprotection of PPARα activation by WY14643, with the implication that PPARα activation by WY14643 may be a potential approach for OA therapy.
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http://dx.doi.org/10.1111/jcmm.14184DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6433667PMC
April 2019

Microstructure and Mechanical Properties of 34CrNiMo6 Steel Repaired by Friction Stir Processing.

Materials (Basel) 2019 Jan 16;12(2). Epub 2019 Jan 16.

Engineering Research Center in Additive Manufacturing, Nanchang Hangkong University, Nanchang 330063, China.

Repairing damaged parts using proper repairing methods has become an important means to reduce manufacturing and operational costs and prolong the service life of 34CrNiMo6 steel structures. In the conventional fusion repairing method, welding wire and powder are often used as filling materials. Filling materials are often expensive or difficult to find. Some metallurgical issues (such as solidification crack, higher distortion) were also found with these methods. At the same time, most of the equipment that requires welding wire and powder is expensive. In this study, a new method based on friction stir processing (FSP) was successfully employed to repair 34CrNiMo6 steel, using a block as filling material. Filling blocks are much cheaper than conventional fusion repair consumables. As a result of solid-state repair, this method can also avoid the metallurgical issues of fusion repair. The microstructure and mechanical properties of the repaired samples were investigated using OM (Optical Microscope), SEM, EDS (Energy Dispersive Spectroscopy), XRD, and a Vickers hardness electronic universal tensile tester. The results showed that 34CrNiMo6 steel was successfully repaired by this method, with no defect. Tensile tests showed that the maximum ultimate strength (UTS) was 900 MPa and could reach 91.8% of that of the substrate. The fracture mode of the tensile samples was ductile/brittle mixed fracture. Hence, the repairing method based on FSP appears to be a promising method for repairing castings.
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http://dx.doi.org/10.3390/ma12020279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356225PMC
January 2019

microRNAs regulate nitric oxide release from endothelial cells by targeting NOS3.

J Thromb Thrombolysis 2018 Oct;46(3):275-282

Zhongshan Hospital, Xiamen University, Hubin South Road 201, Xiamen, 361004, Fujian, China.

Endothelial nitric oxide synthase (eNOS) encoded by nitric oxide synthase 3 (NOS3), can generate nitric oxide (NO) which serves as an important deterrent to the pathogenesis of thrombosis by modulating the activation, adhesion and aggregate formation of platelets. Three serum miRNAs (miR-195, miR-532 and miR-582) have been suggested as biomarkers for the diagnosis of deep vein thrombosis (DVT), however their potential roles in DVT is not clear. The effect of miRNAs inhibiting the expression of NOS3 was evaluated in vitro. miR-195, miR-532 and miR-582 mimic, inhibitor, and control miRNAs were transfected into endothelial cells. The roles of miR-195, miR-532 and miR-582 regulating the expression of eNOS were evaluated by real-time quantitative PCR, Western Blotting and luciferase reporter assays. NO release was measured by Griess method. We confirmed NOS3 as a direct target of miR-195 and miR-582, which binds to the 3'-UTR of NOS3 mRNA in endothelial cells. A significantly inverse correlation between these two miRNAs and eNOS expression was detected. NO release from endothelial cells was decreased when the expression level of miR-195 and miR-582 was up-regulated. These findings indicated that miR-195 and miR-582 regulated NO release by targeting 3'-UTR of NOS3 post-transcriptionally in endothelial cells. Therefore, miR-195 and miR-582 might play an important role in maintaining endothelial NO bioavailability and could be a novel target for treatment of thrombotic diseases.
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http://dx.doi.org/10.1007/s11239-018-1684-4DOI Listing
October 2018

Structural insights into the evolution feature of a bony fish CD8αα homodimer.

Mol Immunol 2018 05 4;97:109-116. Epub 2018 Apr 4.

Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing, 100094, People's Republic of China; Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, People's Republic of China. Electronic address:

The CD8αα homodimer structures of endotherms demonstrate that despite distinct diversity at the amino acid sequence level, a few conserved key amino acids ensure common structural features. The structure of CD8αα in ancient ectotherms, such as lower bony fish, remains unclear. In this study, the high-resolution structure of the grass carp (Ctenopharyngodon idella) CD8αα (Ctid-CD8αα) homodimer was determined using the single-wavelength anomalous diffraction (SAD) method. The structure of Ctid-CD8αα shows distinct differences from the known CD8αα structures of endotherms, including a distinct topological structure with shorter back β sheets. The configuration and distribution of the hydrophobic core are different from those in endotherms. Interestingly, mutation of the key amino acid F32S, which is very common in fish and lies in the CDR loop region, leads to the absence of the typical cavity that binds to an epitope-MHC I (p/MHC I) in endotherms, yet Ctid-CD8αα can still specifically bind the grass carp peptide-Ctid-UAA-β2m (p/UAA-β2m). Our results indicate that during the evolutionary process, CD8αα has undergone dramatic changes that affect its dimeric structure and may use a new strategy to interact with p/MHC I.
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http://dx.doi.org/10.1016/j.molimm.2018.03.023DOI Listing
May 2018