Extracellular Matrix Interactome in Modulating Vascular Homeostasis and Remodeling.

The ECM (extracellular matrix) is a major component of the vascular microenvironment that modulates vascular homeostasis. ECM proteins include collagens, elastin, noncollagen glycoproteins, and proteoglycans/glycosaminoglycans. ECM proteins form complex matrix structures, such as the basal lamina and collagen and elastin fibers, through direct interactions or lysyl oxidase-mediated cross-linking. Moreover, ECM proteins directly interact with cell surface receptors or extracellular secreted molecules, exerting matricellular and matricrine modulation, respectively. In addition, extracellular proteases degrade or cleave matrix proteins, thereby contributing to ECM turnover. These interactions constitute the ECM interactome network, which is essential for maintaining vascular homeostasis and preventing pathological vascular remodeling. The current review mainly focuses on endogenous matrix proteins in blood vessels and discusses the interaction of these matrix proteins with other ECM proteins, cell surface receptors, cytokines, complement and coagulation factors, and their potential roles in maintaining vascular homeostasis and preventing pathological remodeling.

On-Demand 3D Spatial Distribution of Magnetic Permeability Based on Fe3 O4 Nanoparticle Liquid Toward Micro-Cavity Detectors.

The change of 3D spatial distribution of magnetic permeability can lead to the generation of introduced electrical signals. However, present studies can only achieve rough regulation by simple shape deformation of magnetic elastomers such as compression, bending, or stretching. Accurate control of the 3D spatial distribution of magnetic permeability is still an open question. In this study, an on-demand 3D spatial distribution of magnetic permeability by controlled flowing of Fe3 O4 nanoparticle liquid (FNL) is demonstrated. The flowing routes of FNL are tuned by a 3D-printed cage with pre-designed hollow structure, thus changing the 3D spatial distribution of magnetic permeability. Then, eight symmetrically distributed coils under cage are used to receive characteristic induction voltage signals. Maxwell numerical simulation reveals the working mechanism of signal generation. Notably, those eight coils can detect FNL flowing status in eight directions, allowing recognition of up to 255 different FNL flowing combinations. By introducing machine learning, the micro-cavity detector based on FNL can distinguish nine kinds of micro-cavity structures with an accuracy of 98.77%. This work provides a new strategy for the adjustment of the 3D spatial distribution of the magnetic permeability and expands the application of FNL in the field of space exploration.

Targeting endothelial tight junctions to predict and protect thoracic aortic aneurysm and dissection.

AIMS: Whether changes in endothelial tight junctions (TJs) lead to the formation of thoracic aortic aneurysm and dissection (TAAD) and serve as an early indicator and therapeutic target remains elusive. METHODS AND RESULTS: Single-cell RNA sequencing analysis showed aberrant endothelial TJ expressions in the thoracic aortas of patients with TAAD. In a ß-aminopropionitrile (BAPN)-induced TAAD mouse model, endothelial TJ function was disrupted in the thoracic aortas at an early stage (5 and 10 days) as observed by a vascular permeability assay, while the intercellular distribution of crucial TJ components was significantly decreased by en face staining. For the non-invasive detection of endothelial TJ function, two dextrans of molecular weights 4 and 70 kDa were conjugated with the magnetic resonance imaging (MRI) contrast agent Gd-DOTA to synthesize FITC-dextran-DOTA-Gd and rhodamine B-dextran-DOTA-Gd. MRI images showed that both probes accumulated in the thoracic aortas of the BAPN-fed mice. Particularly, the mice with increased accumulated signals from 5 to 10 days developed TAAD at 14 days, whereas the mice with similar signals between the two time points did not. Furthermore, the protease-activated receptor 2 inhibitor AT-1001, which seals TJs, alleviated the BAPN-induced impairment of endothelial TJ function and expression and subsequently reduced TAAD incidence. Notably, endothelial-targeted ZO-1 conditional knockout increased TAAD incidence. Mechanistically, vascular inflammation and edema were observed in the thoracic aortas of the BAPN-fed mice, whereas these phenomena were attenuated by AT-1001. CONCLUSION: The disruption of endothelial TJ function is an early event prior to TAAD formation, herein serving as a potential indicator and a promising target for TAAD.

Calcifying fibrous tumor and pathological analysis.

A 55-year-old male presented to our outpatient department with complaints of upper abdominal dull pain. Gastroscopy revealed a submucosal eminence at the greater curvature of the gastric body, with smooth surface mucosa, and biopsy pathology indicated inflammation. Physical examination showed no obvious abnormalities, and laboratory results were within the normal range. Computerized tomography (CT) showed thickening of the gastric body. Endoscopic submucosal dissection (ESD) was performed,and representative photomicrographs of histologic sections were shown.

Physical radiofrequency adjuvant enhances immune responses to influenza H5N1 vaccination.

Pre-pandemic influenza H5N1 vaccine has relatively low immunogenicity and often requires high antigen amounts and two immunizations to induce protective immunity. Incorporation of vaccine adjuvants is promising to stretch vaccine doses during pandemic outbreaks. This study presents a physical radiofrequency (RF) adjuvant (RFA) to conveniently and effectively increase the immunogenicity and efficacy of H5N1 vaccine without modification of vaccine preparation. Physical RFA is based on a brief RF treatment of the skin to induce thermal stress to enhance intradermal vaccine-induced immune responses with minimal local or systemic adverse reactions. We found that physical RFA could significantly increase H5N1 vaccine-induced hemagglutination inhibition antibody titers in murine models. Intradermal H5N1 vaccine in the presence of RFA but not vaccine alone significantly lowered lung viral titers, reduced body weight loss, and improved survival rates after lethal viral challenges. The improved protection in the presence of RFA was correlated with enhanced humoral and cellular immune responses to H5N1 vaccination in both male and female mice, indicating no gender difference of RFA effects in murine models. Our data support further development of the physical RFA to conveniently enhance the efficacy of H5N1 vaccine.

Membrane lipid remodeling and autophagy to cope with phosphorus deficiency in the dinoflagellate Prorocentrum shikokuense.

Dinoflagellates, which are responsible for more than 80% of harmful algal blooms in coastal waters, are competitive in low-phosphate environments. However, the specific acclimated phosphorus strategies to adapt to phosphorus deficiency in dinoflagellates, particularly through intracellular phosphorus metabolism, remain largely unknown. Comprehensive physiological, biochemical, and transcriptomic analyses were conducted to investigate intracellular phosphorus modulation in a model dinoflagellate, Prorocentrum shikokuense, with a specific focus on membrane lipid remodeling and autophagy in response to phosphorus deficiency. Under phosphorus deficiency, P. shikokuense exhibited a preference to spare phospholipids with nonphospholipids. The major phospholipid classes of phosphatidylcholine and phosphatidylethanolamine decreased in content, whereas the betaine lipid class of diacylglyceryl carboxyhydroxymethylcholine increased in content. Furthermore, under phosphorus deficiency, P. shikokuense induced autophagy as a mechanism to conserve and recycle cellular phosphorus resources. The present study highlights the effective modulation of intracellular phosphorus in P. shikokuense through membrane phospholipid remodeling and autophagy and contributes to a comprehensive understanding of the acclimation strategies to low-phosphorus conditions in dinoflagellates.

Long-term survival outcomes of endoscopic therapy vs. surgical resection in patients with cardia gastrointestinal stromal tumor.

The ideal surgical approach for treating cardia gastrointestinal stromal tumor (GIST) is not clearly established. This study aimed to assess the long-term survival results among patients who received endoscopic therapy (ET) or surgical resection (SR) for cardia GIST. Cardia GIST patients from 2000 to 2019 were selected from the surveillance, epidemiology, and end result (SEER) database. Multiple imputation (MI) was applied to handle missing data, and propensity score matching (PSM) was carried out to mitigate selection bias during comparisons. Demographic and clinical characteristics' effects on overall survival (OS) and cancer-specific survival (CSS) were assessed using Kaplan-Meier analyses and multivariate Cox proportional hazard models. A total of 330 patients with cardia GIST were enrolled, including 47 (14.2%) patients with ET and 283 (85.8%) patients with SR. The 5-year OS and CSS rates in the ET and SR groups were comparable [before PSM, (OS) (76.1% vs. 81.2%, P = 0.722), (CSS) (95.0% vs. 89.3%, P = 0.186); after PSM, (OS) (75.4% vs. 85.4%, P = 0.540), (CSS) (94.9% vs. 92.0%, P = 0.099)]. Moreover, there was no significant difference between ET and SR in terms of long-term OS (hazard ratio [HR] 0.735, 95% confidence interval [CI] 0.422-1.282) and CSS (HR 1.560, 95% CI 0.543-4.481). Our study found no significant disparity in long-term survival outcomes between ET and SR in cardia GIST patients, implying that ET could be a valid surgical strategy for treating cardia GIST.

Remnant cholesterol and risk of major adverse cardiovascular events: a systematic review and dose-response meta-analysis of cohort studies.

Emerging evidence indicates a significant role of remnant cholesterol in contributing to the residual risk associated with major adverse cardiovascular events (MACE). This study aims to evaluate the dose-response relationship between remnant cholesterol and the risk of MACE. PubMed, Embase and Cochrane databases were reviewed to identify cohort studies published in English up to 1 August 2023. Twenty-eight articles were selected. Pooled hazard ratios (HR) and their 95% confidence intervals (CIs) were calculated using fixed or random-effects models to evaluate the association between remnant cholesterol and the risk of MACE. The dose-response relationship between remnant cholesterol levels and the risk of MACE was analyzed using the linear model and restricted cubic spline regression models. For calculated remnant cholesterol levels, the pooled HR (95% CI) of MACE for per 1-SD increase was 1.13 (1.08, 1.17); HR (95% CI) for the second quartile (Q2), the third quartile (Q3) and the highest quartile (Q4) of remnant cholesterol levels were 1.14 (1.03, 1.25), 1.43 (1.23, 1.68) and 1.68 (1.44, 1.97), respectively, compared with the lowest quartile (Q1). For measured remnant cholesterol levels, the pooled HR (95% CI) of MACE per 1-SD increase was 1.67 (1.39, 2.01). The dose-response meta-analysis showed a dose-response relationship between remnant cholesterol levels and the risk of MACE, both on a linear trend (P < 0.0001) and a nonlinear trend (P < 0.0001). The risk of MACE is associated with increased levels of remnant cholesterol, and the dose-response relationship between remnant cholesterol levels and the risk of MACE showed both linear and nonlinear trends.

Transcriptomic and metabolomic analysis reveals the influence of carbohydrates on lignin degradation mediated by Bacillus amyloliquefaciens.

Introduction: Ligninolytic bacteria can secrete extracellular enzymes to depolymerize lignin into small-molecular aromatics that are subsequently metabolized and funneled into the TCA cycle. Carbohydrates, which are the preferred carbon sources of bacteria, influence the metabolism of lignin-derived aromatics through bacteria. Methods: In this study, untargeted metabolomics and transcriptomics analyses were performed to investigate the effect of carbohydrates on lignin degradation mediated by Bacillus amyloliquefaciens MN-13, a strain with lignin-degrading activity that was isolated in our previous work. Results: The results demonstrated that the cell growth of the MN-13 strain and lignin removal were promoted when carbohydrates such as glucose and sodium carboxymethyl cellulose were added to an alkaline lignin-minimal salt medium (AL-MSM) culture. Metabolomics analysis showed that lignin depolymerization took place outside the cells, and the addition of glucose regulated the uptake and metabolism of lignin-derived monomers and activated the downstream metabolism process in cells. In the transcriptomics analysis, 299 DEGs were screened after 24 h of inoculation in AL-MSM with free glucose and 2 g/L glucose, respectively, accounting for 8.3% of the total amount of annotated genes. These DEGs were primarily assigned to 30 subcategories, including flagellar assembly, the PTS system, RNA degradation, glycolysis/gluconeogenesis, the TCA cycle, pyruvate metabolism, and tryptophan metabolism. These subcategories were closely associated with the cell structure, generation of cellular energy, and precursors for biosynthetic pathways, based on a - log 10 (P adjust) value in the KEGG pathway analysis. Conclusion: In summary, the addition of glucose increased lignin degradation mediated by the MN-13 strain through regulating glycolysis, TCA cycle, and central carbon metabolism.

Untethered & Stiffness-Tunable Ferromagnetic Liquid Robots for Cleaning Thrombus in Complex Blood Vessels.

Thrombosis is a significant threat to human health. However, the existing clinical treatment methods have limitations. Magnetic soft matter is used in the biomedical field for years, and ferromagnetic liquids exhibit tunable stiffness and on-demand movement advantages under magnetic fields. In this study, a ferromagnetic liquid robot (FMLR) is developed and applied it to thrombus removal in complex blood vessels. The FMLR consisted of Fe3O4 magnetic nanoparticles and dimethyl silicone oil. The FMLR can pass through a narrow complex maze through shape deformation by tailoring the intensity and direction of the external magnetic field. Finite element simulation analysis is used to validate the mechanism of controllable FMLR movements. Importantly, the storage modulus of FMLR can be tuned from 0.1 to 2018 Pa by varying the external magnetic intensity, ensuring its effectiveness in removing rigid and stubborn thrombi present on the vascular walls. Toward medical robotic applications, FMLR can be used in telerobotic neurointerventional. Experiments demonstrating the capability of FMLR to remove thrombi in the ear veins of rabbits are conducted. This study introduces an efficient approach for thrombus elimination, broadening the utilization of FMLRs within the realm of clinical medicine.

Icariside II protects from marrow adipose tissue (MAT) expansion in estrogen-deficient mice by targeting S100A16.

Icariside II, a flavonoid glycoside, is the main component found invivo after the administration of Herba epimedii and has shown some pharmacological effects, such as prevention of osteoporosis and enhancement of immunity. Increased levels of marrow adipose tissue are associated with osteoporosis. S100 calcium-binding protein A16 (S100A16) promotes the differentiation of bone marrow mesenchymal stem cells (BMSCs) into adipocytes. This study aimed to confirm the anti-lipidogenesis effect of Icariside II in the bone marrow by inhibiting S100A16 expression. We used ovariectomy (OVX) and BMSC models. The results showed that Icariside II reduced bone marrow fat content and inhibited BMSCs adipogenic differentiation and S100A16 expression, which correlated with lipogenesis. Overexpression of S100A16 eliminated the inhibitory effect of Icariside II on lipid formation. ß-catenin participated in the regulation adipogenesis mediated by Icariside II/S100A16 in the bone. In conclusion, Icariside II protects against OVX-induced bone marrow adipogenesis by downregulating S100A16, in which ß-catenin might also be involved.

Additively Manufactured Flexible Liquid Metal-Coated Self-Powered Magnetoelectric Sensors with High Design Freedom.

Although additive manufacturing enables controllable structural design and customized performance for magnetoelectric sensors, their design and fabrication still require careful matching of the size and modulus between the magnetic and conductive components. Achieving magnetoelectric integration remains challenging, and the rigid coils limit the flexibility of the sensors. To overcome these obstacles, this study proposes a composite process combining selective laser sintering (SLS) and 3D transfer printing for fabricating flexible liquid metal-coated magnetoelectric sensors. The liquid metal forms a conformal conductive network on the SLS-printed magnetic lattice structure. Deformation of the structure alters the magnetic flux passing through it, thereby generating voltage. A reverse model segmentation and summation method is established to calculate the theoretical magnetic flux. The impact of the volume fraction, unit size, and height of the sensors on the voltage is studied, and optimization of these factors yields a maximum voltage of 45.6 µV. The sensor has excellent sensing performance with a sensitivity of 10.9 kPa-1 and a minimum detection pressure of 0.1 kPa. The voltage can be generated through various external forces. This work presents a significant advancement in fabricating liquid metal-based magnetoelectric sensors by improving their structural flexibility, magnetoelectric integration, and design freedom.

Shallow tillage mitigates plant competition by increasing diversity and altering plant community assembly process.

Introduction: Understanding how human activities affect biodiversity is needed to inform systemic policies and targets for achieving sustainable development goals. Shallow tillage to remove Artemisia ordosica is commonly conducted in the Mu Us Desert. However, the impacts of shallow tillage on plant community species diversity, phylogenetic structure, and community assembly processes remain poorly understood. Methods: This study explores the effects of shallow tillage on species diversity including three a-diversity and two b-diversity indicators, as well as phylogenetic structure [phylogenetic diversity (PD), net relatedness index (NRI), and nearest taxon index (NTI)]. Additionally, this research analyzes the effects of shallow tillage on the community assembly process. Results and discussion: The results showed that the a-diversity index, b-diversity index, and PD of the shallow tillage (ST) communities were significantly higher than those of the non-shallow tillage (NT) communities, and the phylogenetic structures of both the ST and NT communities tended to be differentiated, with competitive exclusion being the main mechanism of plant assembly. However, shallow tillage increased the relative importance of the stochastic processes dominated by dispersal limitation, mitigating plant competition in the communities. This conclusion was supported by the Raup-Crick difference index-based analysis. Conclusion: Therefore, for the ecological restoration of the Mu Us Desert, species with adaptability and low niche overlap should be selected to increase the utilization efficiency of the environmental resources. The results of this study provide a foundation for policy development for ecosystem management and restoration in the Mu Us Desert.

Significance of phosphate adsorbed on the cellular surface as a storage pool and its regulation in marine microalgae.

The increasing prevalence of phosphorus limitation in coastal waters has drawn attention to the bioavailability of cellular surface-adsorbed phosphorus (SP) as a reservoir of phosphorus in phytoplankton. This study examined the storage, utilization, and regulation of SP in the coastal waters of the East China Sea, as well as three cultivated algal bloom species (Skeletonema marinoi, Prorocentrum shikokuense, and Karenia mikimotoi) prevalent in the area. SP accounted for 14.3%-45.5% of particulate phosphorus in the field and laboratory species. After the depletion of external phosphate, the studied species can rapidly transport SP within 3-24 h. The storage of SP is regulated by both external phosphate conditions and the internal growth stage of cells, but it is not influenced by the various cellular surface structures of the studied species. This study highlights the significance of SP as a crucial phosphorus reservoir and the potential use of the SP level as an indicator of phosphorus deficiency in phytoplankton.

Comparative tissue proteomics reveals unique action mechanisms of vaccine adjuvants.

Radiofrequency adjuvant (RFA) was recently developed to boost influenza vaccination without the safety concerns of chemical adjuvants due to their physical nature. Yet, the action mechanisms of RFA remain largely unknown. Omics techniques offer new opportunities to identify molecular mechanisms of RFA. This study utilized comparative tissue proteomics to explore molecular mechanisms of the physical RFA. Comparison of RFA and chemical adjuvant (Alum, AddaVax, MPL, MPL/Alum)-induced tissue proteome changes identified 14 exclusively induced proteins by RFA, among which heat shock protein (HSP) 70 was selected for further analysis due to its known immune-modulating functions. RFA showed much weakened ability to boost ovalbumin and pandemic influenza vaccination in HSP70 knockout than wild-type mice, hinting crucial roles of HSP70 in RFA effects. This study supports comparative tissue proteomics to be an effective tool to study molecular mechanisms of vaccine adjuvants.

Co-exposure of maize to polyethylene microplastics and ZnO nanoparticles: Impact on growth, fate, and interaction.

Microplastics (MPs), especially polyethylene MPs (PE MPs), which are the primary component of mulch, have attracted increasing attention in recent years. ZnO nanoparticles (NPs), which constitute a metal-based nanomaterial commonly used in agricultural production, co-converge with PE MPs in the soil. However, studies revealing the behavior and fate of ZnO NPs in soil-plant systems in the presence of MPs are limited. In this study, a pot experiment was used to evaluate the effects of maize co-exposure to PE MPs (0.5 % and 5 % w/w) and ZnO NPs (500 mg/kg) on growth, element distribution, speciation, and adsorption mechanism. The results demonstrate that individual exposure to PE MPs posed no significant toxicity; however, it significantly decreased maize grain yield (essentially 0). ZnO NP-exposure treatments significantly increased the Zn concentration and distribution intensity in maize tissues. Among them, the Zn concentration in the maize root exceeded 200 mg/kg, compared with 40 mg/kg in the grain. Moreover, the Zn concentrations in various tissues decreased in the following order: stem, leaf, cob, bract, and grain. Reassuringly, ZnO NPs still could not be transported to the maize stem under co-exposure to PE MPs. ZnO NPs had been biotransformed (64 % of the Zn was associated with histidine, with the remainder being associated with P [phytate] and cysteine) in maize stem. This study provides new insights into the plant physiological risks of PE MP and ZnO NP co-exposure in the soil-plant system and assesses the fate of ZnO NPs.

Nutrient strengthening of winter wheat by foliar ZnO and Fe3O4 NPs: Food safety, quality, elemental distribution and effects on soil bacteria.

With the anticipated application of engineered nanomaterials (ENMs) as foliar fertilizers in agriculture, there is a particular need to accurately assess crop intensification capacity, potential hazards, and effects on the soil environment when ENMs are applied alone or in combination. In this study, the joint analysis of scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) showed that ZnO NPs transformed on the leaf surface or within the leaf, and Fe3O4 NPs were able to translocate from the leaf (~ 25 memu/g) into the stem (~ 4 memu/g), but were unable to enter the grain (below 1 memu/g), guaranteeing food safety. Spray application of ZnO NPs significantly improved grain Zn content of wheat (40.34 mg/kg), whereas Fe3O4 NPs treatment and Zn + Fe NPs treatment did not significantly improve grain Fe content. According to the micro X-ray fluorescence of wheat grains(µ- XRF) and physiological structure in situ analysis showed that ZnO NPs treatment and Fe3O4 NPs treatment could increase the elemental contents of Zn and Fe in the crease tissue and endosperm components, respectively, while antagonism was observed in the grain treated with Zn + Fe NPs. The 16S rRNA gene sequencing results showed that the Fe3O4 NPs treatment had the greatest negative effect on soil bacterial community, followed by Zn + Fe NPs, and ZnO NPs showed some promotion effect. This may be caused by the significantly higher elemental contents of Zn/Fe in the treated roots and soils. This study critically evaluates the application potential and environmental risks of nanomaterials as foliar fertilizers and is instructive for agricultural applications of nanomaterials alone and in combination.

In Situ 4D Printing of Polyelectrolyte/Magnetic Composites for Sutureless Gastric Perforation Sealing.

In situ bioprinting has emerged as one of the most promising techniques for the sutureless tissue sealing of internal organs. However, most existing in situ bioprinting methods are limited by the complex and confined printing space inside the organs, harsh curing conditions for printable bioinks, and poor ability to suturelessly seal injured parts. The combination of in situ bioprinting and 4D printing is a promising technique for tissue repair. Herein, the in situ 4D printing of polyelectrolyte/magnetic composites by gastroscopy for sutureless internal tissue sealing is reported. Using gastric perforation as an example, a gelatin/sodium alginate/magnetic bioink is developed, which can be precisely located by a gastroscope with the assistance of an external magnetic field, solidified in gastric fluid, and firmly adhered to tissue surfaces. The solidified bioink along the defect can be attracted by an external magnetic field, resulting in sutureless sealing. A demonstration using a porcine stomach with an artificial perforation confirms the feasibility of sutureless sealing using 4D printing. Moreover, an in vivo investigation on gastric perforation in a rat model identifies the biocompatibility by H&E and CD68+ staining. This study provides a new orientation and concept for functionality-modified in situ 4D bioprinting.

Largely Enhanced Surface Flashover Voltage of Poly(ether Imide) by Scalable and Durable ZnO Coating: A Gift from In Situ Growth.

Dielectric materials with high surface electric insulation strength are in great demand in a high-power space solar cell array (SSCA). A moderately conductive surface is favorable to inhibit charge accumulation and mitigate electric field distortion, thus improving the surface flashover voltage. Although numerous modification methods have been proposed to achieve this goal, the facile, efficient, scalable, and environmentally friendly modification strategy remains a critical challenge to date. Considering the excellent charge modulation ability of ZnO and its mild preparation conditions, a facile and economical hydrothermal strategy was proposed to fabricate in situ a durable poly(ether imide)/zinc oxide (PEI/ZnO) coating with a high charge decay rate. The blooming flower-like ZnO in the coating is proved to play a key role in enhancing lateral charge dissipation on the surface of PEI, thereby suppressing surface charge accumulation. It was also shown that the shielding effect of ZnO on high-energy photons during flashover and the catalytic effect of Zn2+ on PEI molecular chains during hydrothermal treatment had a facilitating and suppressing effect on outgassing, respectively, and consequently affected the flashover. Excitingly, the synergistic effects of both accelerated charge dissipation and suppressed outgassing helped to improve the flashover voltage of PEI by up to 36.7%. The strategy selected here is efficient, scalable, and facile, and the coating is durable, which makes sense for commercial promotion.

Flagellin/Virus-like Particle Hybrid Platform with High Immunogenicity, Safety, and Versatility for Vaccine Development.

Hepatitis B core (HBc) virus-like particles (VLPs) and flagellin are highly immunogenic and widely explored vaccine delivery platforms. Yet, HBc VLPs mainly allow the insertion of relatively short antigenic epitopes into the immunodominant c/e1 loop without affecting VLP assembly, and flagellin-based vaccines carry the risk of inducing systemic adverse reactions. This study explored a hybrid flagellin/HBc VLP (FH VLP) platform to present heterologous antigens by replacing the surface-exposed D3 domain of flagellin. FH VLPs were prepared by the insertion of flagellin gene into the c/e1 loop of HBc, followed by E. coli expression, purification, and self-assembly into VLPs. Using the ectodomain of influenza matrix protein 2 (M2e) and ovalbumin (OVA) as models, we found that the D3 domain of flagellin could be replaced with four tandem copies of M2e or the cytotoxic T lymphocyte (CTL) epitope of OVA without interfering with the FH VLP assembly, while the insertion of four tandem copies of M2e into the c/e1 loop of HBc disrupted the VLP assembly. FH VLP-based M2e vaccine elicited potent anti-M2e antibody responses and conferred significant protection against multiple influenza A viral strains, while FljB- or HBc-based M2e vaccine failed to elicit significant protection. FH VLP-based OVA peptide vaccine elicited more potent CTL responses and protection against OVA-expressing lymphoma or melanoma challenges than FljB- or HBc-based OVA peptide vaccine. FH VLP-based vaccines showed a good systemic safety, while flagellin-based vaccines significantly increased serum interleukin 6 and tumor necrosis factor α levels and also rectal temperature at increased doses. We further found that the incorporation of a clinical CpG 1018 adjuvant could enhance the efficacy of FH VLP-based vaccines. Our data support FH VLPs to be a highly immunogenic, safe, and versatile platform for vaccine development to elicit potent humoral and cellular immune responses.