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This study was performed to evaluate the effects of total polysaccharides extracted from Pleurotus ostreatus on type 2 diabetes. Rats were administered with high-fat diet and streptozotocin (STZ) to induce diabetes. The rats were then treated with 100, 200, and 400 mg/kg/d POP or vehicle for 4 weeks. Our experiments indicated that POP reduces hyperglycemia and hyperlipidemia levels, improves insulin resistance, and increases glycogen storage by activating GSK3 phosphorylation and GLUT4 translocation. Moreover, POP reduces the risk of oxidative damage by increasing superoxide dismutase(SOD), catalase(CAT), and glutathione peroxidase(GSH-Px) activities and decreasing malonaldehyde(MDA) level. These results suggest that POP exerts antidiabetic effect on STZ-induced diabetic rats. [ABSTRACT FROM AUTHOR]

Malignant melanoma is a challenging problem worldwide, because the remaining tumor cells and extensive skin defects following surgical resection are difficult to treat. Biomaterial-mediated immunotherapy has emerged as a superior strategy for anti-tumor applications in recent years. Herein, a unique double-layer MNP was developed to address the problem of malignant melanoma. Hydroxyapatite (HAP) and short-chain peptides from tumor cells were self-assembled to prepare the bioinspired nano-vaccine, and then they were loaded onto the microneedle tips of methacrylated gelatin (GelMA)-based MNP. The products (dubbed HVMN) demonstrated relatively good biocompatibility and immune activity, inhibiting the proliferation and inducing apoptosis of malignant melanoma in a B16 cell-bearing model of C57BL/6 mice, and promoting skin tissue regeneration in a full thickness skin defect model of SD rats in 15 days. The putative molecular pathways were examined preliminarily. In conclusion, this research will develop a competitive microneedle patch with dual anti-tumor and pro-regenerative properties for the postoperative treatment of malignant melanoma. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the hepatoprotective effect of polysaccharides from Pleurotus ostreatus (POP) on carbon tetrachloride-induced acute liver injury (ALI) in rats. The hepatoprotective effect of POP against ALI was reflected by the decreased alanine transaminase and aspartate transaminase levels in blood, increased superoxide dismutase, catalase, and glutathione peroxidase levels, and decreased malondialdehyde levels in blood and liver. TUNEL and immunohistochemistry analyses showed that TUNEL apoptosis cell rate and Bax, cytochrome C, caspase-3, caspase-9, and apoptosis-inducing factor expression levels were obviously decreased, whereas Bcl-2 expression levels obviously increased after POP treatment. A total of 11 metabolites belonging to energy, amino acid, fatty acid, and gut bacteria metabolism were identified as biomarkers by using metabolite analysis of liver homogenate based on ultra-performance liquid chromatography–tandem mass spectrometry. POP exhibited hepatoprotective effects on CCl 4 -induced ALI, and the underlying mechanism is correlated with antioxidants that regulate metabolic pathway disorders and alleviate liver mitochondria apoptosis. • POP exhibited hepatoprotective effect against acute liver injury. • The hepatoprotective effects were correlated with antioxidants • The hepatoprotective effects were correlated with anti-apoptosis. • The hepatoprotective effects were correlated with regulate metabolism disorders. [ABSTRACT FROM AUTHOR]

This study was performed to evaluate the hepatoprotective effect of FVP on carbon tetrachloride induced acute liver injury rats. Transaminase levels, antioxidant effect and histopathology were used to assess the recovery of FVP treated acute liver injury rats. Metabolomic analysis of liver homogenate based on GC–MS was used to obtain a global understanding of metabolic change between acute liver injury model rats and FVP-treated rats in order to assess the underlying mechanisms. Multivariate statistical approaches such as principal component analysis and orthogonal projection to latent structure square-discriminant analysis revealed distinctions among the normal, liver injury model, and FVP groups. The results demonstrated that FVP had a hepatoprotective effect on acute liver injury by decreasing AST and ALT levels, enhancing antioxidant effect and attenuating pathological injury. Sixteen metabolites were identified as biomarkers. These biomarkers belonged to glyoxylate and dicarboxylate metabolism, galactose metabolism, glycine, serine and threonine metabolism, glycerolipid metabolism, alanine, aspartate and glutamate metabolism, TCA cycle, pyruvate metabolism, arginine and proline metabolism. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is a particularly transmissible virus that causes a severe respiratory disease known as COVID-19. Safe and effective vaccines are urgently needed to combat the COVID-19 pandemic. The receptor-binding domain (RBD) of SARS-CoV-2 spike protein elicits most neutralizing antibodies during viral infection and is an ideal antigen for vaccine development. In particular, RBD expressed by E. coli is amenable to low cost and high-yield manufacturability. The adjuvant is necessitated to improve the immunogenicity of RBD. IC28, a TLR5-dependent adjuvant, is a peptide from bacterial flagellin. Mannan is a ligand of TLR-4 or TLR-2 and a polysaccharide adjuvant. Here, IC28 and mannan were both covalently conjugated with RBD from E. coli. The conjugate (RBD-IC28-M) elicited high RBD-specific IgG titers, and a neutralization antibody titer of 201.4. It induced high levels of Th1-type cytokines (IFN-γ) and Th2-type cytokines (IL-5 and IL-10), along with high antigenicity and no apparent toxicity to the organs. The mouse sera of the RBD-IC28-M group competitively interfered with the interaction of RBD and ACE2. Thus, conjugation with IC28 and mannan additively enhanced the humoral and cellular immunity. Our study was expected to provide the feasibility to develop an affordable, easily scalable, effective vaccine SARS-CoV-2 vaccine. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) induces neurological and autoimmune complications such as microcephaly and Guillain-Barre syndrome. Effective vaccines are necessary to prevent the ZIKV infection. E protein of ZIKV is responsible for virus attachment, entry, and fusion. The domain III of E protein (EDIII) contains the neutralizing epitopes and is ideal to act as an antigen for ZIKV vaccine. However, EDIII is poorly immunogenic. CRM 197 is a carrier protein and can activate T helper cells for EDIII. Mannan is a ligand of TLR-4 or TLR-2. Eight-arm PEG can link multiple EDIII molecules in one entity. In the present study, EDIII was covalently conjugated with CRM 197 , 8-arm PEG and mannan to improve the immunogenicity of EDIII. The conjugate (CRM-EDIII-PM) elicited high EDIII-specific antibody titers in the BALB/c mice. Th1-type cytokines (IFN-γ and IL-2) and Th2-type cytokines (IL-5 and IL-10) were secreted at a marked level. Thus, CRM-EDIII-PM could stimulate potent humoral and cellular immune response to EDIII. The serum exposure of CRM-EDIII-PM to the immune system was prolonged. Moreover, CRM-EDIII-PM did not lead to apparent toxicity to the organs. Therefore, CRM-EDIII-PM was expected as a promising vaccine candidate for its ability to induce strong immune responses. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is a particularly transmissible virus that renders the worldwide COVID-19 pandemic and global severe respiratory distress syndrome. Protein-based vaccines hold great advantages to build the herd immunity for their specificity, effectiveness, and safety. Receptor-binding domain (RBD) of SARS-CoV-2 is an appealing antigen for vaccine development. However, adjuvants and delivery system are necessitated to enhance the immunogenicity of RBD. In the present study, RBD was chemically conjugated with loxoribine and SpyCatcher/SpyTag, followed by assembly to form a nanoparticle vaccine. Loxoribine (a TLR7/8 agonist) acted as an adjuvant, and nanoparticles functioned as delivery system for the antigen and the adjuvant. The nanoparticle vaccine elicited high RBD-specific antibody titers, high neutralizing antibody titer, and strong ACE2-blocking activity. It stimulated high splenic levels of Th1-type cytokines (IFN-γ and IL-2) and Th2-type cytokines (IL-4 and IL-5) in BALB/c mice. It promoted the splenocyte proliferation, enhanced the CD4+ and CD8+ T cell percentage and stimulated the maturation of dendritic cells. The vaccine did not render apparent toxicity to the organs of mice. Thus, the nanoparticle vaccine was of potential to act as a preliminarily safe and effective candidate against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

The hypoxic environment of tumor may retard the efficacy of tumor therapeutic agents. Hemoglobin (Hb)-based oxygen carriers (HBOCs) could overcome the hypoxia of tumor by the oxygen delivery. However, typical HBOCs may not provide sufficient oxygen for their low oxygen transferring efficiency (OTE). In order to increase the OTE, human adult Hb (HbA) was subjected to triple modifications, i.e., αα-fumaryl crosslink at Lys-99(α), carboxymethylation at Val-1(α) and 8-arm PEG-based polymerization. Crosslink at Lys-99(α) and carboxymethylation at Val-1(α) synergistically led to a T-like quaternary structure of HbA. The dual modification significantly increased the partial oxygen pressure at 50% saturation (P 50) of HbA from 14.8 mmHg to 34.6 mmHg and OTE from 9.1% to 33.1%. Eight-arm PEG-based polymerization slightly decreased the P 50 of the Hb derivative to 27.8 mmHg and OTE to 30.5%. However, it can enlarge the molecular size of HbA and then prolong the serum duration of HbA. The triple modifications synergistically increased the autoxidation rate of Hb, which promote the production of reactive oxygen species (ROS). Therefore, the sufficient oxygen delivery and substantial production of ROS by the triply modified Hb may provide a potential strategy for tumor therapy. [ABSTRACT FROM AUTHOR]

Anthrax is an acute and highly lethal disease caused by Bacillus anthracis. Protective antigen (PA) is the primary candidate antigen for the anthrax vaccines. However, PA suffers from poor immunogenicity with short-term anti-PA antibody response. High effectiveness, durable immunity, and minimal risk are required for development of an effective anthrax vaccine. In the present study, PA was self-conjugated by 8-arm polyethylene glycol (PEG) and further by thioester chemistry. As a result, 3–5 PA molecules were covalently conjugated and functioned as an antigen delivery system. The conjugate (PA-PEG) could maintain the structural properties of PA and increase the thermal stability of PA. PA-PEG could elicit a robust anti-PA IgG and neutralization antibody response in the magnitude and quality. The antibodies could be largely maintained for 180 days after three immunizations of PA-PEG. PA-PEG effectively stimulated the maturation of dendritic cell and rapidly induced the germinal center (GC) reaction. The percentages of the GC B-cells and T follicular helper (Tfh) cells were thus significantly augmented. The inflammatory response elicited by PA-PEG was comparable to those by PBS and PA. Therefore, PA-PEG is expected as an effective anthrax vaccine candidate with durable immunoprotection against anthrax. [ABSTRACT FROM AUTHOR]

Staphylokinase (SAK) is a bacterial protein with profibrinolytic activity. However, SAK suffers from short serum half-life and high immunogenicity. PEGylation with high Mw (20 kDa or 40 kDa) could decrease the immunogenicity and prolong the serum half-life of the proteins. However, the PEGylated protein could induce the anti-PEG antibodies and its bioactivity was significantly decreased. Arabinogalactan (AG) is a health-promoting substance with numerous biological activities. Conjugation of AG is an alternative strategy to solve the above-mentioned problems. However, conjugation with AG significantly decreased the bioactivity of a protein by shielding the bioactive domain. Here, AG conjugation and PEGylation were combined to improve the therapeutic efficacy of SAK. PEG with low Mw (2 kDa or 5 kDa) acted as a linker to conjugate AG from Larix. As compared with SAK-AG (22.3%), the conjugates (SAK-P2K-AG and SAK-P5K-AG) largely maintained the bioactivity of SAK (73.8% and 62.9%). The two conjugates both showed an 8-fold decrease in the SAK-specific IgG titers and a prolonged serum half-life. Moreover, the conjugates did not render any apparent toxicity to the heart, liver and renal functions of mice. Thus, our conjugation strategy is promising for the development of an effective long-acting therapeutic protein. [ABSTRACT FROM AUTHOR]

Abstract Haloalkane dehalogenase DhaA catalyzes the hydrolysis of halogenated compounds by cleavage of the carbon-halogen bond. However, DhaA suffers from poor environmental stability and difficult recovery, which significantly increase the cost of DhaA. Here, an effective enzyme immobilization strategy was developed to overcome the disadvantages of DhaA. DhaA was physically absorbed with amine-functionalized meso-cellular foam (MCF). The MCF-absorbed DhaA (MD) was intermolecularly crosslinked with 8-arm PEG N ‑hydroxysuccinimide ester and then PEGylated by maleimide-thiol chemistry. DhaA from Rhodococcus rhodochrous was absorbed at a loading capacity of 100 mg/g in MD. The bulk crystallinity and morphology of MCF were largely maintained. The immobilized DhaA (MD-P1-P2) showed a lower Michaelis constant (K m , 0.588 mM) than DhaA (0.905 mM), along with an extremely low leaching ratio of DhaA (1.1%) from MCF. MD-P1-P2 exhibited a high stability in the extreme environmental conditions, as reflected by the remaining activity of 99.8% in 40% (v/v) DMSO for 5 h, 87.3% in 3 M urea solution for 1 h, 25.9% at pH 3.0, and 51.8% at room temperature for 30 days. Thus, our study was expected to develop an effective immobilized DhaA for practical application. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]