hACE2-Induced Allosteric Activation in SARS-CoV versus SARS-CoV-2 Spike Assemblies Revealed by Structural Dynamics.

SARS-CoV and SARS-CoV-2 cell entry begins when spike glycoprotein (S) docks with the human ACE2 (hACE2) receptor. While the two coronaviruses share a common receptor and architecture of S, they exhibit differences in interactions with hACE2 as well as differences in proteolytic processing of S that trigger the fusion machine. Understanding how those differences impact S activation is key to understand its function and viral pathogenesis. Here, we investigate hACE2-induced activation in SARS-CoV and SARS-CoV-2 S using hydrogen/deuterium-exchange mass spectrometry (HDX-MS). HDX-MS revealed differences in dynamics in unbound S, including open/closed conformational switching and D614G-induced S stability. Upon hACE2 binding, notable differences in transduction of allosteric changes were observed extending from the receptor binding domain to regions proximal to proteolytic cleavage sites and the fusion peptide. Furthermore, we report that dimeric hACE2, the native oligomeric form of the receptor, does not lead to any more pronounced structural effect in S compared to saturated monomeric hACE2 binding. These experiments provide mechanistic insights into receptor-induced activation of Sarbecovirus spike proteins.

Three-dimensional ordered DNA network constructed by a biomarker pair for accurate monitoring of colorectal cancer.

Precise and early screening of colorectal cancer (CRC) is one crucial yet challenging task for its treatment, and the analysis of multi-targets of CRC in a single assay with high accuracy is essential for pathological research and clinical diagnosis. Here, a CRC-related biomarker pair, microRNA-211 (miRNA-211) and H2S, was detected by constructing a three-dimensional (3D) ordered DNA network. First, trace amount of miRNA-211 could initiate a hybridization chain reaction-based amplification process. A highly ordered 3D DNA network was formed based on the organized assembly of DNA-cube frameworks that were constructed by DNA origamis and Ag nanoparticles (NPs) encapsulated inside. In the presence of the H2S, Ag NPs within the network can be etched to generate Ag2S quantum dots, which could be better visualized in fluorescence in situ cell imaging. Using the 3D DNA ordered network as the sensing platform, it can acquire dual analysis of biomolecule (miRNA-211) and inorganic gas (H2S) in vitro, overcoming the limitations of single type of biomarker detection in a single assay. This assay achieved a wide linearity range of H2S from 0.05 to 10 µM, and exhibited a low limit of detection of 4.78 nM. This strategy allows us to acquire the spatial distributions of H2S and miRNA expression levels in living CRC cells simultaneously, providing a highly sensitive and selective tool for early screening and monitoring of CRC.

Uric acid promotes myocardial infarction injury via activating pyrin domain-containing 3 inflammasome and reactive oxygen species/transient receptor potential melastatin 2/Ca2+pathway.

Cardiomyocytes injury has been considered as a key contributor for myocardial infarction (MI). Uric acid (UA) can induce cardiomyocytes injury, which is closely related to NLRP3 activation and inflammatory factor generation. However, the mechanism how UA modulates cardiomyocytes remains elusive. Western blotting and qRT-PCR were applied for measuring protein and mRNA expression, respectively. ROS production and Ca2+ influx were measured by flow cytometry. Patch clamp technique was used for measuring transient receptor potential melastatin 2 (TRPM2) channel. Ligation of left anterior descending for 2 h was performed to induce MI animal model. The rats were treated by different concentration of uric acid. The artery tissues were stained by HE and collected for measurement of NLRP3 and inflammatory factors. Supplementation of UA significantly promoted apoptosis, and augmented the expression of intercellular adhesion molecule-1, chemoattractant protein-1, vascular cell adhesion molecule-1, and NLRP3 inflammasome. Knockdown of NLRP3 reversed the influence of UA on MI by decreasing collagen deposition, fibrotic area, apoptosis. The expression of NLRP3 inflammasome increased markedly after treatment of UA. UA activated ROS/TRPM2/Ca2+ pathway through targeting NLRP3. UA activated NLRP3 inflammasome and augments inflammatory factor production, which in turn exacerbates cardiomyocytes injury. Knockdown of NLRP3 reversed the influence of UA on apoptosis and cell cycle. UA may promote cardiomyocytes injury through activating NLRP3 inflammasome and ROS/TRPM2 channel/Ca2+ pathway.

An HIV-1 broadly neutralizing antibody overcomes structural and dynamic variation through highly focused epitope targeting.

The existence of broadly cross-reactive antibodies that can neutralize diverse HIV-1 isolates (bnAbs) has been appreciated for more than a decade. Many high-resolution structures of bnAbs, typically with one or two well-characterized HIV-1 Env glycoprotein trimers, have been reported. However, an understanding of how such antibodies grapple with variability in their antigenic targets across diverse viral isolates has remained elusive. To achieve such an understanding requires first characterizing the extent of structural and antigenic variation embodied in Env, and then identifying how a bnAb overcomes that variation at a structural level. Here, using hydrogen/deuterium-exchange mass spectrometry (HDX-MS) and quantitative measurements of antibody binding kinetics, we show that variation in structural ordering in the V1/V2 apex of Env across a globally representative panel of HIV-1 isolates has a marked effect on antibody association rates and affinities. We also report cryo-EM reconstructions of the apex-targeting PGT145 bnAb bound to two divergent Env that exhibit different degrees of structural dynamics throughout the trimer structures. Parallel HDX-MS experiments demonstrate that PGT145 bnAb has an exquisitely focused footprint at the trimer apex where binding did not yield allosteric changes throughout the rest of the structure. These results demonstrate that structural dynamics are a cryptic determinant of antigenicity, and mature antibodies that have achieved breadth and potency in some cases are able to achieve their broad cross-reactivity by "threading the needle" and binding in a highly focused fashion, thus evading and overcoming the variable properties found in Env from divergent isolates.

Recent Advances in the Application of Covalent Organic Frameworks in Extraction: A Review.

Covalent organic frameworks (COFs) are a class of emerging materials that are synthesized based on the covalent bonds between different building blocks. COFs possess unique attributes in terms of high porosity, tunable structure, ordered channels, easy modification, large surface area, and great physical and chemical stability. Due to these features, COFs have been extensively applied as adsorbents in various extraction modes. Enhanced extraction performance could be reached with modified COFs, where COFs are presented as composites with other materials including nanomaterials, carbon and its derivatives, silica, metal-organic frameworks, molecularly imprinted polymers, etc. This review article describes the recent advances, developments, and applications of COF-based materials being utilized as adsorbents in the extraction methods. The COFs, their properties, their synthesis approaches as well as their composite structures are reviewed. Most importantly, suggested mechanisms for the extraction of analyte(s) by COF-based materials are also discussed. Finally, the current challenges and future prospects of COF-based materials in extraction methods are summarized and considered in order to provide more insights into this field.

Mannose-binding lectin and complement mediate follicular localization and enhanced immunogenicity of diverse protein nanoparticle immunogens.

Nanoparticle (NP) vaccine formulations promote immune responses through multiple mechanisms. We recently reported that mannose-binding lectin (MBL) triggers trafficking of glycosylated HIV Env-immunogen NPs to lymph node follicles. Here, we investigate effects of MBL and complement on NP forms of HIV and other viral antigens. MBL recognition of oligomannose on gp120 nanoparticles significantly increases antigen accumulation in lymph nodes and antigen-specific germinal center (GC) responses. MBL and complement also mediate follicular trafficking and enhance GC responses to influenza, HBV, and HPV particulate antigens. Using model protein nanoparticles bearing titrated levels of glycosylation, we determine that mannose patches at a minimal density of 2.1 × 10-3 mannose patches/nm2 are required to trigger follicular targeting, which increases with increasing glycan density up to at least ∼8.2 × 10-3 patches/nm2. Thus, innate immune recognition of glycans has a significant impact on humoral immunity, and these findings provide a framework for engineering glycan recognition to optimize vaccine efficacy.

Mechanism of Isosorbide Dinitrate Combined with Exercise Training Rehabilitation to Mobilize Endothelial Progenitor Cells in Patients with Coronary Heart Disease.

it was to explore effect of isosorbide dinitrate combined with exercise training and rehabilitation on endothelial progenitor cells (EPCs) in coronary heart disease. EPCs were isolated and cultured from peripheral blood of coronary heart disease patients, and morphology and surface markers were detected. Then, 116 patients were rolled into treatment group (isosorbide dinitrate + exercise rehabilitation training) and control group (isosorbide dinitrate). Characteristics of EPCs cells after treatment were compared. The mononuclear cells were round and small in size and were not evenly distributed in the culture plate. EPCs cells grew as colonies after 8d-culture, and the surrounding cells grew outward in a germinating manner with colonies as the center, forming multiple cell populations. Positive rates of EPCs surface markers CD133, CD34, and vascular endothelial growth factor receptor (KDR) were 11.25±3.07%, 48.18±9.13%, and 76.36±8.27%, respectively. Proliferation activity of EPCs in the treatment group was dramatically higher versus controls at day three, five, and seven (P<0.05). Adhesion ability of EPCs in treatment group was dramatically higher than controls at day three, five, and seven (P<0.05). Migration ability of EPCs in treatment group was dramatically higher versus control group at day three, five, and seven (P<0.05). In short, isosorbide dinitrate plus exercise rehabilitation greatly enhanced the proliferation activity, adhesion ability, and migration ability of EPCs cells, which also played a beneficial role in the repair of endothelial injury, with notable effects.

Effect of azelastine hydrochloride combined with montelukast sodium in the treatment of patients with allergic rhinitis.

OBJECTIVE: To investigate efficacy of azelastine hydrochloride combined with montelukast sodium in the treatment of patients with allergic rhinitis. METHODS: A total of 137 patients with allergic rhinitis in our hospital were divided into two groups, 70 patients in the experimental group received azelastine hydrochloride combined with montelukast sodium treatment, while 67 patients in the control group were given only azelastine hydrochloride treatment. The clinical therapeutic effect, clinical symptom score and serum levels of inflammatory factors were recorded. RESULTS: The clinical therapeutic effect of the two groups after treatment were improved compared to those without intervention (P < 0.05), and the total effective rate of the experimental group was 94.3% (66/70), which was higher than that of the control group (83.6%). The clinical symptom score (nasal itching, nasal congestion and runny nose) of two groups was decreased after receiving the intervention, and the scores in the experimental group were much lower than the control group after receiving the intervention (P < 0.05). The serum levels of inflammatory factors (IL-6, IL-8 and hsCRP) were obviously lower in the two groups after treatment, and those levels in the experimental group were much lower than the control group after receiving the intervention. Furthermore, after the receiving treatment, the levels of each of the inflammatory and anti-inflammatory factors in the experimental group were significantly ameliorated compared to those in the control group (P < 0.05). CONCLUSION: Azelastine hydrochloride combined with montelukast sodium can effectively improve clinical symptoms and inflammatory reactions in patients with allergic rhinitis; furthermore, this research provides ideas for clinical practice.

Stabilization of the SARS-CoV-2 Spike Receptor-Binding Domain Using Deep Mutational Scanning and Structure-Based Design.

The unprecedented global demand for SARS-CoV-2 vaccines has demonstrated the need for highly effective vaccine candidates that are thermostable and amenable to large-scale manufacturing. Nanoparticle immunogens presenting the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein (S) in repetitive arrays are being advanced as second-generation vaccine candidates, as they feature robust manufacturing characteristics and have shown promising immunogenicity in preclinical models. Here, we used previously reported deep mutational scanning (DMS) data to guide the design of stabilized variants of the RBD. The selected mutations fill a cavity in the RBD that has been identified as a linoleic acid binding pocket. Screening of several designs led to the selection of two lead candidates that expressed at higher yields than the wild-type RBD. These stabilized RBDs possess enhanced thermal stability and resistance to aggregation, particularly when incorporated into an icosahedral nanoparticle immunogen that maintained its integrity and antigenicity for 28 days at 35-40°C, while corresponding immunogens displaying the wild-type RBD experienced aggregation and loss of antigenicity. The stabilized immunogens preserved the potent immunogenicity of the original nanoparticle immunogen, which is currently being evaluated in a Phase I/II clinical trial. Our findings may improve the scalability and stability of RBD-based coronavirus vaccines in any format and more generally highlight the utility of comprehensive DMS data in guiding vaccine design.

miR-19a/19b improves the therapeutic potential of mesenchymal stem cells in a mouse model of myocardial infarction.

Myocardial infarction (MI) is the cardiac emergency that may leads to myocardial necrosis. Mesenchymal stem cells (MSCs) could be used to induce myocardial differentiation. However, the efficiency remains low. The aim of this study is to explore whether miR-19a/19b could enhance the therapeutic potential of mesenchymal stem cells in MI. Myocardial infarction mouse model was established using coronary artery ligation. Cardiac functional recovery was detected by Masson's trichrome staining. Under hypoxic condition, miR-19a/19b expression levels decreased in bone marrow-derived MSCs (BM-MSCs). MiR-19a/19b suppressed the proliferation of MSCs under hypoxic condition. After cell engraftment, miR-19a/19b promoted survival of MSCs. Mechanically, miR-19a/19b inhibited inflammatory cells infiltration into myocardium cells. Moreover, MSCs-miR-19a/19b improves cardiac functional recovery in diabetic MI mice models. All the results indicated that miR-19a/19b improves the therapeutic potential of mesenchymal stem cells in a mouse model of myocardial infarction.

Elicitation of Potent Neutralizing Antibody Responses by Designed Protein Nanoparticle Vaccines for SARS-CoV-2.

A safe, effective, and scalable vaccine is needed to halt the ongoing SARS-CoV-2 pandemic. We describe the structure-based design of self-assembling protein nanoparticle immunogens that elicit potent and protective antibody responses against SARS-CoV-2 in mice. The nanoparticle vaccines display 60 SARS-CoV-2 spike receptor-binding domains (RBDs) in a highly immunogenic array and induce neutralizing antibody titers 10-fold higher than the prefusion-stabilized spike despite a 5-fold lower dose. Antibodies elicited by the RBD nanoparticles target multiple distinct epitopes, suggesting they may not be easily susceptible to escape mutations, and exhibit a lower binding:neutralizing ratio than convalescent human sera, which may minimize the risk of vaccine-associated enhanced respiratory disease. The high yield and stability of the assembled nanoparticles suggest that manufacture of the nanoparticle vaccines will be highly scalable. These results highlight the utility of robust antigen display platforms and have launched cGMP manufacturing efforts to advance the SARS-CoV-2-RBD nanoparticle vaccine into the clinic.

Elicitation of potent neutralizing antibody responses by designed protein nanoparticle vaccines for SARS-CoV-2.

A safe, effective, and scalable vaccine is urgently needed to halt the ongoing SARS-CoV-2 pandemic. Here, we describe the structure-based design of self-assembling protein nanoparticle immunogens that elicit potent and protective antibody responses against SARS-CoV-2 in mice. The nanoparticle vaccines display 60 copies of the SARS-CoV-2 spike (S) glycoprotein receptor-binding domain (RBD) in a highly immunogenic array and induce neutralizing antibody titers roughly ten-fold higher than the prefusion-stabilized S ectodomain trimer despite a more than five-fold lower dose. Antibodies elicited by the nanoparticle immunogens target multiple distinct epitopes on the RBD, suggesting that they may not be easily susceptible to escape mutations, and exhibit a significantly lower binding:neutralizing ratio than convalescent human sera, which may minimize the risk of vaccine-associated enhanced respiratory disease. The high yield and stability of the protein components and assembled nanoparticles, especially compared to the SARS-CoV-2 prefusion-stabilized S trimer, suggest that manufacture of the nanoparticle vaccines will be highly scalable. These results highlight the utility of robust antigen display platforms for inducing potent neutralizing antibody responses and have launched cGMP manufacturing efforts to advance the lead RBD nanoparticle vaccine into the clinic.

Ginsenoside Rf relieves mechanical hypersensitivity, depression-like behavior, and inflammatory reactions in chronic constriction injury rats.

The aim of this study was to investigate whether ginsenoside Rf can effectively relieve pain hypersensitivity in a neuropathic pain rat model. Neuropathic pain was induced in rats by chronic constriction injury (CCI) to the right sciatic nerve. Ginsenoside Rf was administered intraperitoneally after CCI surgery. The von Frey filament test and forced swimming test were performed to examine pain hypersensitivity and depression-like behavior in rats. Western blot was used to measure the levels of inflammatory cytokines in the dorsal root ganglion (DRG) and the spinal cord. Pretreatment of ginsenoside Rf for 7 days did not affect the onset of mechanical allodynia in CCI rats; however, a single dose of ginsenoside Rf 1 day after surgery attenuated established mechanical allodynia in CCI rats. Additionally, chronic treatment of ginsenoside Rf 1 week before and 2 weeks after CCI surgery diminished mechanical allodynia and depression-like behavior without affecting spontaneous locomotor activity in CCI rats. Furthermore, in CCI rats, chronic ginsenoside Rf treatment partially reversed the upregulation of proinflammatory cytokines in the spinal cord and/or the DRG but elevated IL-10, an anti-inflammatory factor, in the DRG. Ginsenoside Rf alleviated neuropathic pain and its associated depression and restored the balance between proinflammatory and anti-inflammatory cytokines. Our results suggest that ginsenoside Rf may be a potential therapy for nerve injury-induced neuropathic pain.

Magnetic Ni/Fe layered double hydroxide nanosheets as enhancer for DNA hairpin sensitive detection of miRNA.

A new non-enzyme method based on hybridization chain reaction (HCR) and colorimetric reaction catalyzed by magnetic Ni/Fe layered double hydroxide (LDH) nanosheets was developed for detection of microRNA (miRNA), let-7b. The DNA hairpins from HCR were separated and adsorbed by Ni/Fe LDH. The peroxidase-like activity of Ni/Fe LDH was found to be enhanced by the DNA hairpins on the surface. The factors, such as ratio of Ni/Fe and concentration of DNA hairpins, related to the catalytic activity were evaluated and the mechanism was discussed. The results of this new detection method for let-7b provided low limit of detection (0.36 fM), wide linear range (0.01 pM to 200 pM) with good linearity (r2 = 0.9968). The optimized method was applied to analyze let-7b in real samples, lung cancer cells. This work demonstrated a new and cost-effective approach for efficient detection of miRNA.

Valsartan attenuates oxidative stress and NF-κB activation and reduces myocardial apoptosis after ischemia and reperfusion.

Myocardial apoptosis is primarily triggered during reperfusion. Various mechanisms are involved, including oxidative stress which activates the translocation of nuclear factor-kappa B (NF-κB) and stimulates the release of tumor necrosis factor-alpha (TNF-α). However, the relative contribution of the renin angiotensin system (RAS) to the development of myocardial apoptosis during reperfusion remains unknown. In the present study, we examined whether inhibition of RAS with Valsartan, an Angiotensin II 1 receptor (AT1) antagonist, could reduce apoptosis during reperfusion. We constructed a rat model of myocardial ischemia reperfusion injury. Rats were pretreated with Valsartan for 2 weeks, and then subjected to 30 min ischemia and 4h reperfusion. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Levels of malondialdehyde (MDA), superoxide dismutase (SOD), TNF-α, and caspase-3 were detected by ELISA. NF-κB, Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase expression was assessed by Western blot analysis. Valsartan inhibited apoptosis (TUNEL staining) in ischemic myocardium (P<0.05), consistent with reduced caspase-3 activity. Valsartan also inhibited of NF-κB translocation to nucleus (P<0.05), and decreased plasma TNF-α levels (P<0.05). Valsartan pretreatment suppressed MDA content and preserved SOD activity, consistent with reduced NADPH oxidase expression (P<0.01). These data provided substantial evidence that RAS was involved in NF-κB activation, mediated by AT1 dependent oxidative stress; thus, RAS might ultimately promote myocardial apoptosis during reperfusion pathogenesis.

Investigation on the removal of Mo(VI) from Mo-Re containing wastewater by chemically modified persimmon residua.

Persimmon waste was chemically modified by crosslinking with concentrated sulfuric acid to obtain a novel kind of adsorption gel, which was termed as crosslinked persimmon tannin (CPT), hereinafter. The adsorption behaviors of Mo(VI) with other coexisting metal ions onto the CPT gel were investigated. The gel exhibited selectivity only for Mo(VI) ions evidenced by the high value of separation factor of molybdenum and rhenium (ß(Mo/Re)=164.37), and the adsorption mechanism of Mo(VI) as a multispecies was studied. The molybdenum adsorption behavior conforms to the Langmuir model with a remarkably high adsorption capacity of 0.56 mol/kg. A kinetic study for the adsorption of molybdenum at various temperatures confirmed that the endothermic adsorption process followed pseudo-second order kinetics. Moreover, its excellent adsorption properties and applicability for Mo(VI) were demonstrated by the removal and separation of Mo(VI) from different Mo-Re containing industrial wastewaters.