Structural insights into NMDA receptor pharmacology.

N-methyl-d-aspartate receptors (NMDARs) comprise a subfamily of ionotropic glutamate receptors that form heterotetrameric ligand-gated ion channels and play fundamental roles in neuronal processes such as synaptic signaling and plasticity. Given their critical roles in brain function and their therapeutic importance, enormous research efforts have been devoted to elucidating the structure and function of these receptors and developing novel therapeutics. Recent studies have resolved the structures of NMDARs in multiple functional states, and have revealed the detailed gating mechanism, which was found to be distinct from that of other ionotropic glutamate receptors. This review provides a brief overview of the recent progress in understanding the structures of NMDARs and the mechanisms underlying their function, focusing on subtype-specific, ligand-induced conformational dynamics.

Ambient Air Pollution Is Associated With HDL (High-Density Lipoprotein) Dysfunction in Healthy Adults.

Objective- We aimed to assess whether exposure to higher levels of ambient air pollution impairs HDL (high-density lipoprotein) function and to elucidate the underlying biological mechanisms potentially involved. Approach and Results- In the Beijing AIRCHD study (Air Pollution and Cardiovascular Dysfunction in Healthy Adults), 73 healthy adults (23.3±5.4 years) were followed-up with 4 repeated study visits in 2014 to 2016. During each visit, ambient air pollution concentrations, HDL function metrics, and parameters of inflammation and oxidative stress were measured. Average daily concentrations of ambient particulate matter in diameter <2.5 µm were 62.9 µg/m3 (8.1-331.0 µg/m3). We observed significant decreases in HDL cholesterol efflux capacity of 2.3% (95% CI, -4.3 to -0.3) to 5.0% (95% CI, -7.6 to -2.4) associated with interquartile range increases in moving average concentrations of particulate matter in diameter <2.5 µm and traffic-related air pollutants (black carbon, nitrogen dioxide, and carbon monoxide) during the 1 to 7 days before each participant's clinic visit. Higher ambient air pollutant levels were also associated with significant reductions in circulating HDL cholesterol and apoA-I (apolipoprotein A-I), as well as elevations in HDL oxidation index, oxidized LDL (low-density lipoprotein), malondialdehyde, and high-sensitivity C-reactive protein. Conclusions- Higher ambient air pollution concentrations were associated with impairments in HDL functionality, potentially because of systemic inflammation and oxidative stress. These novel findings further our understanding of the mechanisms whereby air pollutants promote cardiometabolic disorders.

AG1296 enhances plaque stability via inhibiting inflammatory responses and decreasing MMP-2 and MMP-9 expression in ApoE-/- mice.

BACKGROUND: Atherosclerosis is a chronic process that progresses to unstable plaques. Plaque rupture leads to deleterious consequences such as acute coronary syndrome, thrombosis and stroke. AG1296 is a potent tyrosine kinase inhibitor which is able to block PDGF-PDGFR signaling pathway. This study aims to assess the effect of AG1296 on plaque stability and explore the potential mechanisms. METHODS: Atherosclerotic plaques were induced in carotid arteries in ApoE-/- mice by perivascular collar placement. All mice were randomly divided into PBS and AG1296 groups. 3 weeks after the surgery, the carotid arteries were harvested for histological analysis. RESULTS: In AG1296 group, plaque area decreased by 41.5% (p = 0.0041) and the contents of macrophages and lipids decreased by 43.5% (p = 0.0003) and 35.6% (p = 0.0032) respectively. The contents of smooth muscle cells increased by 22.3% (p = 0.0214) in AG1296 group. Vulnerable index decreased by 48.3% (p = 0.0002). The inflammation factors IL-6 and TNF- alpha decreased by 49.0% (p = 0.0008) and 51.8% (p < 0.0001) and matrix metalloproteinases MMP-2 and MMP-9 decreased by 54.1% (p = 0.0004) and 37.1% (p < 0.0001) in AG1296 group. M1 macrophage markers (MCP-1) were downregulated by 30.3% (p = 0.0007) and M2 macrophage markers (ARG-1) were increased by 55.2% (p = 0.0009) in AG1296 group. CONCLUSION: AG1296 inhibited the atherosclerotic plaque progression and enhanced plaque stability by inhibiting inflammatory responses, reducing the expression of matrix metalloproteinases and promoting macrophages from proinflammatory phenotype to anti-inflammatory phenotype.

Meningeal lymphatic vasculature, a general target for glioblastoma therapy?

Glioblastoma (GBM) causes nearly universal mortality as a result of the failure of conventional therapies including surgical resection, targeted radiation therapy, and chemotherapy. An increasingly important treatment option is combining immunotherapy with other therapies in both preclinical and clinical studies. The central nervous system (CNS) has been historically considered an immune privileged area, but increasing evidence, including the recent rediscovery of meningeal lymphatic vessels (MLVs), has overturned this notion. MLVs are populated by multiple immune cells and connect the CNS to the periphery by draining cerebrospinal fluid with soluble CNS antigens and immune cells into cervical lymph nodes. In the past few years, more and more studies have indicated that MLVs are involved in the regulation of inflammation and the immune response in the pathogenesis of various CNS diseases including GBM. Here, we explore the critical interlinkages between MLVs and GBM therapies including chemotherapy, radiotherapy and immunotherapy, and propose the meningeal lymphatic vasculature as a general target for GBM therapy.

Endothelial Myosin IIA Is Required for the Maintenance of Blood-Brain Barrier Integrity.

Brain endothelial cells (ECs) are essential elements of the blood-brain barrier (BBB), maintaining its integrity through both paracellular junctions and transcellular transport systems. Myosin IIA, a multifunctional protein, plays a significant role in various cellular processes, including cytoskeletal maintenance, cell division, and signal transduction. While Myosin IIA has been implicated in bleeding and ischemic stroke, its role in regulating BBB integrity under physiological conditions remains unclear. In this study, we investigated the impact of Myosin IIA deficiency on BBB integrity using intravenous tracer injections and models of epilepsy. Flow cytometry, Western blot, and real-time PCR were employed to isolate brain cells and assess changes in protein and mRNA levels. Additionally, immunofluorescence staining and electron microscopy were used to explore alterations in protein expression and the structure of BBB. Our results demonstrate that endothelial Myosin IIA deficiency increased BBB permeability and exacerbated symptoms in BBB-related diseases. Mechanistically, we found that Myosin IIA modulates ß-catenin transcription and protein interactions. The overexpression of ß-catenin in brain endothelial Myosin IIA deficiency mice improved BBB integrity and reduced disease severity. This study establishes Myosin IIA as a critical regulator of BBB integrity and suggests new therapeutic targets for vascular diseases.

A Novel System for Transcatheter Aortic Valve Implantation: First-in-Man Study.

Transcatheter aortic valve implantation (TAVI) has become a therapeutic treatment for severe symptomatic patients with aortic stenosis. This study aimed to test a novel transcatheter aortic self-expandable bioprosthesis-the ScienCrown system (Lepu Medtech Inc., Beijing, China)-and evaluate the safety of the new device during TAVI. ScienCrown aortic valve implantation was performed on 10 patients. Clinical assessment was performed at baseline, post procedure, and after 1 year. Clinical outcomes and adverse events were assessed according to Valvular Academic Research Consortium-3 criteria. The mean age was 75.30 ± 4.78 years with a mean Society of Thoracic Surgeons score of 4.64 ± 3.23%. Device success was achieved in all patients (80% transfemoral, 20% transapical). After 1 year, there were no deaths, disabling strokes, myocardial infarctions, conversions to surgery, or major procedure-related complications. New pacemaker implantation was required in one patient (10%). ScienCrown implantation resulted in a reduction in mean valve gradient (63.00 ± 18.84 to 9.67 ± 4.97 mm Hg, p <0.001) and an increase in effective orifice area (0.57 ± 0.20 to 2.57 ± 0.59 cm2, p <0.001) at 1 year. Paravalvular leak was absent in 9 patients (90%), and there was a trace in one patient (10%). All patients were in New York Heart Association class I to II at a mean follow-up of 1 year. The experience showed that ScienCrown transcatheter aortic valve system was safely and successfully implanted for treatment of severe symptomatic aortic stenosis. The newer-generation device affords a stable implantation while providing optimal hemodynamic performance.

Meningeal lymphatics regulate radiotherapy efficacy through modulating anti-tumor immunity.

As a first-line treatment, radiotherapy (RT) is known to modulate the immune microenvironment of glioma, but it is unknown whether the meningeal lymphatic vessel (MLV)-cervical lymph node (CLN) network regulates the process or influences RT efficacy. Here, we show that the MLV-CLN network contributes to RT efficacy in brain tumors and mediates the RT-modulated anti-tumor immunity that is enhanced by vascular endothelial growth factor C (VEGF-C). Meningeal lymphatic dysfunction impaired tumor-derived dendritic cell (DC) trafficking and CD8+ T cell activation after RT, whereas tumors overexpressing VEGF-C with meningeal lymphatic expansion were highly sensitive to RT. Mechanistically, VEGF-C-driven modulation of RT-triggered anti-tumor immunity was attributed to C-C Motif Chemokine Ligand 21 (CCL21)-dependent DC trafficking and CD8+ T cell activation. Notably, delivery of VEGF-C mRNA significantly enhanced RT efficacy and anti-tumor immunity in brain tumors. These findings suggest an essential role of the MLV-CLN network in RT-triggered anti-tumor immunity, and highlight the potential of VEGF-C mRNA for brain tumor therapy.

Anxa1 in smooth muscle cells protects against acute aortic dissection.

AIMS: Acute aortic dissection (AAD) is a life-threatening disease with high morbidity and mortality. Previous studies have showed that vascular smooth muscle cell (VSMC) phenotype switching modulates vascular function and AAD progression. However, whether an endogenous signalling system that protects AAD progression exists remains unknown. Our aim is to investigate the role of Anxa1 in VSMC phenotype switching and the pathogenesis of AAD. METHODS AND RESULTS: We first assessed Anxa1 expression levels by immunohistochemical staining in control aorta and AAD tissue from mice. A strong increase of Anxa1 expression was seen in the mouse AAD tissues. In line with these findings, micro-CT scan results indicated that Anxa1 plays a role in the development of AAD in our murine model, with systemic deficiency of Anxa1 markedly progressing AAD. Conversely, administration of Anxa1 mimetic peptide, Ac2-26, rescued the AAD phenotype in Anxa1-/- mice. Transcriptomic studies revealed a novel role for Anxa1 in VSMC phenotype switching, with Anxa1 deficiency triggering the synthetic phenotype of VSMCs via down-regulation of the JunB/MYL9 pathway. The resultant VSMC synthetic phenotype rendered elevated inflammation and enhanced matrix metalloproteinases (MMPs) production, leading to augmented elastin degradation. VSMC-restricted deficiency of Anxa1 in mice phenocopied VSMC phenotype switching and the consequent exacerbation of AAD. Finally, our studies in human AAD aortic specimens recapitulated key findings in murine AAD, specifically that the decrease of Anxa1 is associated with VSMC phenotype switch, heightened inflammation, and enhanced MMP production in human aortas. CONCLUSIONS: Our findings demonstrated that Anxa1 is a novel endogenous defender that prevents AAD by inhibiting VSMC phenotype switching, suggesting that Anxa1 signalling may be a potential target for AAD pharmacological therapy.

Structural Insight into Phospholipid Transport by the MlaFEBD Complex from P. aeruginosa.

The outer membrane (OM) of Gram-negative bacteria, which consists of lipopolysaccharides (LPS) in the outer leaflet and phospholipids (PLs) in the inner leaflet, plays a key role in antibiotic resistance and pathogen virulence. The maintenance of lipid asymmetry (Mla) pathway is known to be involved in PL transport and contributes to the lipid homeostasis of the OM, yet the underlying molecular mechanism and the directionality of PL transport in this pathway remain elusive. Here, we reported the cryo-EM structures of the ATP-binding cassette (ABC) transporter MlaFEBD from P. areuginosa, the core complex in the Mla pathway, in nucleotide-free (apo)-, ADP (ATP + vanadate)- and ATP (AMPPNP)-bound states as well as the structures of MlaFEB from E. coli in apo- and AMPPNP-bound states at a resolution range of 3.4-3.9 Å. The structures show that the MlaFEBD complex contains a total of twelve protein molecules with a stoichiometry of MlaF2E2B2D6, and binds a plethora of PLs at different locations. In contrast to canonical ABC transporters, nucleotide binding fails to trigger significant conformational changes of both MlaFEBD and MlaFEB in the nucleotide-binding and transmembrane domains of the ABC transporter, correlated with their low ATPase activities exhibited in both detergent micelles and lipid nanodiscs. Intriguingly, PLs or detergents appeared to relocate to the membrane-proximal end from the distal end of the hydrophobic tunnel formed by the MlaD hexamer in MlaFEBD upon addition of ATP, indicating that retrograde PL transport might occur in the tunnel in an ATP-dependent manner. Site-specific photocrosslinking experiment confirms that the substrate-binding pocket in the dimeric MlaE and the MlaD hexamer are able to bind PLs in vitro, in line with the notion that MlaFEBD complex functions as a PL transporter.

ICAM-1 Activates Platelets and Promotes Endothelial Permeability through VE-Cadherin after Insufficient Radiofrequency Ablation.

Radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) often leads to aggressive local recurrence and increased metastasis, and vascular integrity and platelets are implicated in tumor metastasis. However, whether interactions between endothelial cells and platelets induce endothelial permeability in HCC after insufficient RFA remains unclear. Here, significantly increased CD62P-positive platelets and sP-selectin in plasma are observed in HCC patients after RFA, and tumor-associated endothelial cells (TAECs) activate platelets and are susceptible to permeability after heat treatment in the presence of platelets in vitro. In addition, tumors exhibit enhanced vascular permeability after insufficient RFA in mice; heat treatment promotes platelets-induced endothelial permeability through vascular endothelial (VE)-cadherin, and ICAM-1 upregulation in TAECs after heat treatment results in platelet activation and increased endothelial permeability in vitro. Moreover, the binding interaction between upregulated ICAM-1 and Ezrin downregulates VE-cadherin expression. Furthermore, platelet depletion or ICAM-1 inhibition suppresses tumor growth and metastasis after insufficient RFA in an orthotopic tumor mouse model, and vascular permeability decreases in ICAM-1-/- mouse tumor after insufficient RFA. The findings suggest that ICAM-1 activates platelets and promotes endothelial permeability in TAECs through VE-cadherin after insufficient RFA, and anti-platelet and anti-ICAM-1 therapy can be used to prevent progression of HCC after insufficient RFA.

Eva1a ameliorates atherosclerosis by promoting re-endothelialization of injured arteries via Rac1/Cdc42/Arpc1b.

AIMS: Eva-1 homologue 1 (Eva1a) is a novel protein involved in the regulation of cardiac remodelling and plaque stability, but little is known about its role in re-endothelialization and the development of atherosclerosis (AS). Thus, in the present study, we aimed to elucidate the function of Eva1a in re-endothelialization and AS. METHODS AND RESULTS: Wire injuries of carotid and femoral arteries were established in Eva1a-/- mice. Eva1a-deficient mice were crossed with apolipoprotein E-/- (ApoE-/-) mice to evaluate AS development and re-endothelialization of carotid artery injuries. Denudation of the carotid artery at 3, 5, and 7 days was significantly aggravated in Eva1a-/- mice. The neointima of the femoral artery at 14 and 28 days was consequently exacerbated in Eva1a-/- mice. The area of atherosclerotic lesions was increased in Eva1a-/-ApoE-/- mice. To explore the underlying mechanisms, we performed transwell, scratch migration, cell counting kit-8, and bromodeoxyuridine assays using cultured human aorta endothelial cells (HAECs), which demonstrated that EVA1A promoted HAEC migration and proliferation. Proteomics revealed that the level of actin-related protein 2/3 complex subunit 1B (Arpc1b) was decreased, while Eva1a expression was absent. Arpc1b was found to be a downstream molecule of EVA1A by small interfering RNA transfection assay. Activation of Rac1 and Cdc42 GTPases was also regulated by EVA1A. CONCLUSION: This study provides insights into anti-atherogenesis effects of Eva1a by promoting endothelium repair. Thus, Eva1a is a promising therapeutic target for AS.

Insights into the bamboo genome: syntenic relationships to rice and sorghum.

Bamboo occupies an important phylogenetic node in the grass family and plays a significant role in the forest industry. We produced 1.2 Mb of tetraploid moso bamboo (Phyllostachys pubescens E. Mazel ex H. de Leh.) sequences from 13 bacterial artificial chromosome (BAC) clones, and these are the largest genomic sequences available so far from the subfamily Bambusoideae. The content of repetitive elements (36.2%) in bamboo is similar to that in rice. Both rice and sorghum exhibit high genomic synteny with bamboo, which suggests that rice and sorghum may be useful as models for decoding Bambusoideae genomes.

Genome size and sequence composition of moso bamboo: a comparative study.

Moso bamboo (Phyllostachys pubescens) is one of the world's most important bamboo species. It has the largest area of all planted bamboo--over two-thirds of the total bamboo forest area--and the highest economic value in China. Moso bamboo is a tetraploid (4x=48) and a special member of the grasses family. Although several genomes have been sequenced or are being sequenced in the grasses family, we know little about the genome of the bambusoids (bamboos). In this study, the moso bamboo genome size was estimated to be about 2034 Mb by flow cytometry (FCM), using maize (cv. B73) and rice (cv. Nipponbare) as internal references. The rice genome has been sequenced and the maize genome is being sequenced. We found that the size of the moso bamboo genome was similar to that of maize but significantly larger than that of rice. To determine whether the bamboo genome had a high proportion of repeat elements, similar to that of the maize genome, approximately 1000 genome survey sequences (GSS) were generated. Sequence analysis showed that the proportion of repeat elements was 23.3% for the bamboo genome, which is significantly lower than that of the maize genome (65.7%). The bamboo repeat elements were mainly Gypsy/DIRS1 and Ty1/Copia LTR retrotransposons (14.7%), with a few DNA transposons. However, more genomic sequences are needed to confirm the above results due to several factors, such as the limitation of our GSS data. This study is the first to investigate sequence composition of the bamboo genome. Our results are valuable for future genome research of moso and other bamboos.

Changes in pathogenicity and immunogenicity of Mycoplasma mycoides subsp. mycoides strains revealed by comparative genomics analysis.

Mycoplasma mycoides subsp. mycoides is the causative agent of contagious bovine pleuropneumonia. A pathogenic strain BEN-1 was isolated from bovine lung and underwent continuous passages in rabbits for 468 generations. During this process, the strain's strong virulence became weak and, gradually, it lost the ability to confer protective immunity in cattle but developed virulence in rabbits. In order to gain insight into the mechanisms behind the reduction in virulence and the loss of immunogenicity, we sequenced five representative strains of the BEN series, including the original strain (BEN-1), the strain generation that first acquired virulence in rabbits (BEN-50), the two vaccine strain generations (BEN-181 and BEN-326), and the strain generation showing the greatest loss of immunogenicity (BEN-468). The gene mutation rate in the four different propagation stages varied greatly, and over half of variations observed in each generation were removed during the propagation process. However, the variation maintained in the BEN-468 generation might contribute to its changes in virulence and immunogenicity. We thus identified 18 genes associated with host adaptation, six genes contributing to virulence in cattle, and 35 genes participating in conferring immunity in cattle. These findings might help us optimize the vaccine to obtain more effective immunization results.

Synthesis and evaluation of antibacterial activity of 7-alkyloxy-4,5-dihydro-imidazo[1,2-a]quinoline derivatives.

In this study, a series of 7-alkyloxy-4,5-dihydro-imidazo[1,2-a]quinoline derivatives was synthesized and tested for their antibacterial activity against various bacterial strains. Most of the compounds exhibited potential antibacterial activity against gram-negative and gram-positive bacteria. Compound 7p (7-heptyloxy-4,5-dihydro-imidazo[1,2-a]quinoline) was found to be the most potent inhibitor. The minimum inhibitory concentration (MIC) of compound 7p against Escherichia coli was 0.5 µg/mL, better than that of reference agent ciprofloxacin and amoxicillin. Furthermore, compound 7p exhibited a modest activity against several gram-negative bacterial strains at a dose range of 2-64 µg/mL.