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Background: Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia. Diagnosing AD before symptoms arise will facilitate earlier intervention. The early diagnostic approaches are thus urgently needed. Methods: The multifunctional nanoparticles W20/XD4-SPIONs were constructed by the conjugation of oligomer-specific scFv antibody W20 and class A scavenger receptor (SR-A) activator XD4 onto superparamagnetic iron oxide nanoparticles (SPIONs). The SPIONs' stability and uniformity in size were measured by dynamic light scattering and transmission electron microscopy. The ability of W20/XD4-SPIONs for recognizing A beta oligomers (A beta Os) and promoting A beta Os phagocytosis was assessed by immunocytochemistry and flow cytometry analysis. The blood-brain barrier permeability of W20/XD4-SPIONs was determined by a co-culture transwell model. The in vivo probe distribution of W20/XD4-SPIONs in AD mouse brains was detected by magnetic resonance imaging (MRI). Results: W20/XD4-SPIONs, as an A beta Os-targeted molecular MRI contrast probe, readily reached pathological A beta Os regions in brains and distinguished AD transgenic mice from WT controls. W20/XD4-SPIONs retained the property of XD4 for SR-A activation and significantly promoted microglial phagocytosis of A beta Os. Moreover, W20/XD4-SPIONs exhibited the properties of good biocompatibility, high stability and low cytotoxicity. Conclusion: Compared with W20-SPIONs or XD4-SPIONs, W20/XD4-SPIONs show the highest efficiency for A beta Os-targeting and significantly enhance A beta Os uptake by microglia. As a molecular probe, W20/XD4-SPIONs also specifically and sensitively bind to A beta Os in AD brains to provide an MRI signal, demonstrating that W20/XD4-SPIONs are promising diagnostic agents for early-stage AD. Due to the beneficial effect of W20 and XD4 on neuropathology, W20/XD4-SPIONs may also have therapeutic potential for AD.

It is widely accepted that amyloid oligomers are the most toxic species to initiate the pathologic processes of Parkinson’s disease (PD) and Huntingdon’s disease (HD). But there is no definitive diagnosis for PD and HD at their early stages. Here, we conjugated an amyloid oligomer-specific scFv antibody (W20) to PEGylated superparamagnetic iron oxide nanoparticles (SPIONs) and detected the properties of the SPIONs conjugated with W20. The results showed that W20-SPIONs, with the size of around 11.8 nm in diameter, were stable and nontoxic, and had enough relaxation capacity to be used as an MRI contrast agent. When applied to the transgenic mouse models of PD and HD, W20-SPIONs crossed the blood-brain barrier and specifically bound to the oligomer area to give MRI signal, distinguishing PD and HD from healthy controls. These results indicated that W20-SPIONs had potential in early-stage diagnosis for PD and HD and also opened up a new strategy for evaluating the efficacy of new drugs.

Although vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are under development, the antigen epitopes on the virus and their immunogenicity are poorly understood. Here, we simulate the 3D structures and predict the B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches and validate epitope immunogenicity by immunizing mice. Almost all 33 predicted epitopes effectively induce antibody production, six of these are immunodominant epitopes in individuals, and 23 are conserved within SARS-CoV-2, SARS-CoV, and bat coronavirus RaTG13. We find that the immunodominant epitopes of individuals with domestic (China) SARS-CoV-2 are different from those of individuals with imported (Europe) SARS-CoV-2, which may be caused by mutations on the S (G614D) and N proteins. Importantly, we find several epitopes on the S protein that elicit neutralizing antibodies against D614 and G614 SARS-CoV-2, which can contribute to vaccine design against coronaviruses., Graphical Abstract, Highlights • B cell epitopes of SARS-CoV-2 are obtained using structure-based approaches • The predicted epitopes effectively induce robust antibody responses • D614 and G614 SARS-CoV-2 display different immunodominant epitopes • Epitopes on S protein elicit D614 and/or G614 SARS-CoV-2-neutralizing antibodies, Lu et al. predict and validate B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches. The immunodominant epitopes vary between D614 and G614 SARS-CoV-2. The epitopes on the S protein elicit neutralizing antibodies against D614 and G614 SARS-CoV-2.

Immunotherapy focusing on reducing the amyloid-beta (A&beta, ) burden is a promising treatment strategy for Alzheimer&rsquo, s disease (AD). Many clinical studies on AD immunotherapies have failed due to low safety and efficacy, calling for a highly potent AD vaccine which induces sufficient antibody titer while avoiding side effects. Here, we designed a yeast-based vaccine Y-5A15 comprising five copies of A&beta, 1-15 displayed on the surface of yeast cell wall, and we subcutaneously immunized APP/PS1 mice three times. Our results demonstrated that the Y-5A15 remarkably enhanced the A&beta, epitope immunogenicity and elicited high antibody titers against A&beta, in AD mice. Importantly, Y-5A15 vaccination successfully reduced A&beta, levels, plaque burden and glial activation, rescued synaptic deficits and significantly ameliorated memory and cognitive decline in APP/PS1 transgenic mice, suggesting that the yeast-based A&beta, epitope vaccine has a promising potency for the treatment of AD.

Background: Alzheimer’s disease (AD) is an incurable and progressive neurodegenerative disorder. Disease-modifying strategies to prevent or delay AD progression are urgently needed. Aβ oligomers (AβOs), rather than monomers or fibrils, are considered as the most neurotoxic species. Therapeutic approaches that direct against these oligomers and promote Aβ clearance may have great value for AD intervention. Results: We here reported the novel multifunctional nanoparticle W20/XD4-SPIONs, which were constructed by conjugating oligomer-specific scFv antibody W20 and class A scavenger receptor activator XD4 onto superparamagnetic iron oxide nanoparticles (SPIONs). Besides the diagnostic value, W20/XD4-SPIONs retained the properties of W20 and XD4 by inhibiting Aβ aggregation, attenuating AβOs-induced cytotoxicity and increasing microglial phagocytosis of Aβ. When applied to AD transgenic mouse model, W20/XD4-SPIONs significantly rescued cognitive deficits and alleviated neuropathology of AD transgenic mice. Conclusion: These results suggest that W20/XD4-SPIONs are a promising therapeutic agent for AD. As a molecular probe, W20/XD4-SPIONs also specifically and sensitively bind to the AβOs in AD brains to provide an MRI signal, demonstrating that W20/XD4-SPIONs are a promising agent for early-stage AD.

Enhancing both the humoral and cellular immune response for tumor vaccination remains a challenge. Inspired by natural pathogen structures, we took β-glucan particles derived from a baker's yeast cell shell (YS) as a vaccine carrier and danger signal for dendritic cells (DCs), and coated the YS with catanionic layered double hydroxides (LDH) by electrostatic adsorption to form a biomimetic yeast cell particle (YSL). Our experimental results showed that the YSL vaccine efficiently targeted antigen-presenting cells (APCs) and remarkably enhanced antigen cross-presentation, and strongly improved the activation and maturation of DCs. Moreover, the YSL vaccine elicited an extremely high antibody titer and strong antigen-specific cytotoxic T lymphocyte together with mixed Th1/Th17 cellular immune responses and induced marked prophylactic and therapeutic effects against E.G7-OVA tumors in mouse models. These results suggest that YSL, integrating a yeast shell to mimic natural pathogens and LDH with high antigen-loading capacity and lysosome escape, is a promising tumor vaccine platform for rapid, effective and strong induction of both humoral and cellular immune responses.

Personalized cancer vaccine which targets neoepitopes shows great promise for cancer treatment. However, rapid preparation is a critical challenge for clinical application of personalized cancer vaccine. Genetic recombination and chemical modification are a time-consuming "trial and error" pattern for making vaccines. Here we first constructed a platform for peptide vaccine preparation by inserting SpyCatcher into the major immunodominant region (MIR) of hepatitis B core protein (HBc) (1-183). The resulted recombinant protein HBc(1-183)-SpyCatcher (HBc(1-183)-S) assembled to virus-like particles (VLPs) and readily bound to SpyTag conjugated with OVA epitope peptides by just mixing, forming HBc(1-183)-S-OVA. HBc(1-183)-S-OVA VLPs effectively induced dendritic cell maturation. Our further results indicated that HBc(1-183)-S-OVA VLPs vaccination inhibited tumor growth in both prophylactic and treatment ways in E.G7-OVA tumor bearing mice by generating significant OVA-specific cytotoxic T lymphocyte responses. Our study provides a simple, rapid, efficient and universal HBc-based platform for the preparation of personalized cancer vaccine.

Therapeutic vaccine is a promising approach in cancer therapy. But tumor-associated antigen peptides have weak immunogenicity and cancer patients are often characterized by immunosuppression and tolerance, leading to less efficiency of immunotherapy. We here successfully developed indoleamine 2, 3-dioxygenase (IDO) siRNA nanoparticle-coated and tyrosinase-related protein 2 (Trp2)-displayed recombinant Saccharomyces cerevisiae (YCP). YCPs had positive charges with a diameter of approximately 5μm, resulting in selective phagocytosis by APC cells. YCP-delivered siRNA and Trp2 successfully escaped from phagosomes, efficiently inhibited IDO expression in DCs, promoted the immune reaction of T cell against Trp2, increased the secretion of proinflammatory cytokines such as IFN-γ,TNF-α, and IL-6, and decreased the generation of regulatory T cells. Moreover, YCPs significantly inhibited melanoma tumor growth by alleviating immune tolerance and promoting Trp2-specific CD8+ T cell immune response. These results suggest that Saccharomyces cerevisiae as a combined immunotherapeutic platform to simultaneously delivery IDO-siRNA and Trp2 epitope peptide is a promising vaccine system for melanoma treatment.

Background β-Amyloid peptide (Aβ) oligomers are initial factors used to induce Alzheimer’s disease (AD) development, and Aβ monomers have normal physiological function. The antibodies or vaccines against Aβ monomers have serious problems, such as side effects and low curative effects. Therefore, it is essential to specifically target Aβ oligomers rather than monomers for the treatment of AD. Methods The mimotopes of Aβ oligomers were obtained by panning the phage-displayed random peptide libraries using oligomer-specific antibodies as targets and expressed on the surface of EBY100 Saccharomyces cerevisiae to generate yeast cell base vaccines. One vaccine (AOE1) induced antibodies specifically against Aβ oligomers and was selected for further study. The APP/PS1 mice were subcutaneously immunized with AOE1 eight times. The levels and characteristics of antibodies induced by AOE1 were determined by enzyme-linked immunosorbent assay. The effect of AOE1 on the cognitive deficits of AD mice was tested by novel object recognition (NOR) and Y-maze. Dot blot analysis, Western blot analysis, and immunohistochemistry were applied to measure the effects of AOE1 on Aβ pathologies, neuroinflammation, and microhemorrhages in the brains of AD mice. Results Eight mimotope candidates of Aβ oligomers were selected and expressed on EBY100 S. cerevisiae. Only AOE1 vaccine containing mimotope L2 induced antibodies that specifically recognized Aβ42 oligomers rather than monomers. AOE1 immunization significantly increased the AD mice’s exploration times for the novel object in the NOR test and the choices for new arms in the Y-maze test, and it reduced levels of Aβ oligomers and glial activation in the AD mouse brains. No activation of Aβ-specific T cells and microhemorrhages was observed in their brains following AOE1 vaccination. Conclusions AOE1 is the first vaccine applying the oligomer-specific mimotope as an immunogen, which could induce antibodies with high specificity to Aβ oligomers. AOE1 immunization attenuated Aβ pathologies and cognitive deficits in AD mice, decreased the overactivation of glial cells, and did not induce microhemorrhage in the brains of AD mice. These findings suggest that AOE1 may be a safer and more effective vaccine for AD treatment.

Active immunotherapy has shown promising potential for cancer treatment. However, there still remain major challenges including induction of a potent and specific T-cell response against the endogenous antigen and retention of tumor immunity. To address these problems, we used layered double hydroxide (LDH) nanoparticles (NPs) to co-deliver tyrosinase-related protein 2 (Trp2) and indoleamine 2,3-dioxygenase siRNA (siIDO) to dendritic cells (DCs). These LDH NPs were readily taken in by DCs, and escaped from endosomes into the cytoplasm. Compared with free Trp2 peptide or siIDO, the vaccination with the LDH NPs co-delivering Trp2 and siIDO significantly inhibited tumor growth in melanoma mouse models by relieving IDO-mediated immune suppression and increasing naïve and specific T cell activation process in vivo. Thus, these LDH NPs, which have a high loading capacity for peptide or siRNA effectively protect and deliver Trp2 and siIDO, overcome the immune tolerance and strengthen T cell immunity, are potential therapeutics to enhance cancer treatment.

Heterogenous aggregates of amyloid β (Aβ) and tau protein play a key role in Alzheimer’s disease (AD) progression. As the epitope profiles of Aβ and abnormally phosphorylated tau change over the course of the disease, tailor immunotherapy to specific patient groups according to the disease stage by targeting corresponding Aβ and tau species or both of tau and Aβ might improve treatment efficacy. However, epitope peptides have low immunogenicity and peptide vaccine preparation is laborious and time-consuming. We here first constructed a platform for peptide vaccine preparation by inserting SpyCatcher into the major immunodominant region (MIR) of truncated Hepatitis B core protein (HBc)(1-149). The resulted recombinant protein HBc-SpyCatcher (HBc-S) could assemble into uniform and stable virus-like particles (VLPs), and readily bind to the SpyTag conjugated epitope peptides. Several series of peptides such as linear, cyclic and phosphorylated peptides including Aβ(1-6), Aβ(1-15), cAβ(1-7), cEP1, cEP2 from β-amyloid monomer or oligomers, T294, pTau396-404, pTau422 from tau proteins, were glued onto HBc-S VLPs, forming HBc-S-peptide (HBc-S-P) VLPs and efficiently elicited specific Th2-type immune responses. When applied to AD transgenic mice, HBc-S-pTau422 alleviated cognition deficits and neuropathology progression in Tau.P301S transgenic mice. The present study provides an easy, quick, convenient and universal platform for high-throughput peptide epitope screening and personalized peptide vaccine preparation.

Cancer immunotherapy has shown tremendous progresses in recent years for various cancers and layered double hydroxide (LDH) nanoparticles are demonstrated as effective adjuvants for protein-based vaccines. This research further shows that the colloidal stability of LDH-based vaccines significantly influences the therapeutic efficacy and LDH nanoparticles are able to adjuvant multiple tumor-associated antigen peptides to provoke strong cell-mediated immune responses for effective inhibition of cancer growth. The LDH-based multi-target therapeutic vaccines were constructed by assembling epitope peptides and CpG onto LDH nanoparticles. Using melanoma as the model cancer and Tyrosinase-related protein 2 (Trp2) peptide as the model antigen, we demonstrated that dispersion-stable LDH-based vaccine induced stronger cytotoxic T-lymphocyte (CTL) responses and significantly inhibited tumor growth in comparison with aggregated LDH-based vaccine. We further constructed multi-target dispersion-stable LDH-based vaccine by co-loading Trp2, two mutated epitopes (M27 and M30) and CpG, which showed remarkable inhibition of melanoma growth. These results suggest that dispersion-stable LDH nanoparticles are an ideal platform to load multi-antigens and immune stimulants as effective personalized therapeutic cancer vaccines.

Background: Alzheimer’s disease (AD) is a neurodegenerative disease featured by memory loss, neuroinflammation and oxidative stress. Overproduction or insufficient clearance of Aβ leads to its pathological aggregation and deposition, which is considered the predominant neuropathological hallmark of AD. Therefore, reducing Aβ levels and inhibiting Aβ-induced neurotoxicity are feasible therapeutic strategies for AD treatment. Wolfberry has been traditionally used as a natural antioxidant and anti-aging product. However, whether wolfberry species has therapeutic potential on AD remains unknown. Method: The effects of fruitless wolfberry-sprout extract (FWE) on Aβ fibrillation and fibril disaggregation was measured by thioflavin T fluorescence and transmission electron microscope imaging; Aβ oligomer level was determined by dot-blot; Cell viability and apoptosis was assessed by MTT and TUNEL assay. The levels of Aβ40/42, oxidative stress biomarkers and inflammatory cytokines were detected by corresponding kits. 8-month-old male APP/PS1 mice and their age-matched WT littermates were treated with FWE or vehicle by oral administration (gavage) once a day for 4 weeks. Then the cognitive performance was determined using object recognition test and Y-maze test. The Aβ burden and gliosis was evaluated by immunostaining and immunoblotting, respectively. Results: FWE significantly inhibited Aβ fibrillation and disaggregated the formed Aβ fibrils, lowered Aβ oligomer level and Aβ-induced neuro-cytotoxicity, and attenuated oxidative stress in vitro. Oral administration of FWE remarkably improved cognitive function, reduced Aβ burden, decreased gliosis and inflammatory cytokines release, and ameliorated oxidative stress in the brains of APP/PS1 mice. Conclusion: These findings indicate that FWE is a promising natural agent for AD treatment.

Background Truncated mis-disordered tau protein plays an important role in the pathogenesis of Alzheimer’s disease (AD) and frontotemporal dementia (FTD). Tau294–305, an epitope in the truncated tau, is essential for pathological tau-tau interaction and aggregation. A tau294–305-targeted approach may have beneficial effects in the treatment of AD and FTD. Methods In this study, we genetically fused tau294–305 epitope to the hepatitis B virus core protein (HBc) major immunodominant region (MIR) (with the resultant protein termed T294-HBc), and we subcutaneously immunized a Tau.P301S transgenic mouse model of FTD and AD with T294-HBc four times. The levels and characteristics of antibodies induced by T294-HBc were determined by enzyme-linked immunosorbent assay. The effect of T294-HBc on the cognitive deficits of Tau.P301S mice was tested using the Morris water maze test, novel object recognition, and a Y-maze test. Western blot analysis and IHC were applied to measure the effect of T294-HBc on tau pathologies and neuroinflammation in the mouse brains. Results The results showed that T294-HBc self-assembled into HBc chimeric virus-like particles (VLPs) with tau294–305 displayed on the surface and that it induced high antibody titers specifically against the mis-disordered truncated tau. Further investigation showed that these antibodies simultaneously bound to microtubule-binding regions 1–4 (MTBR1–4) [tau263–274, tau294–305, tau325–336, tau357–368 and tau294–305(P301S)]. Moreover, T294-HBc VLP vaccination significantly ameliorated memory and cognitive decline; reduced the levels of AT8-positive tau, truncated tau monomer, and oligomer; attenuated microgliosis and astrogliosis; and rescued synaptic deficits in Tau.P301S transgenic mice. Conclusions T294-HBc VLP vaccine elicited strong immune response and alleviated cognitive deficits and neuropathology progression in Tau.P301S mice, indicating that the T294-HBc VLP vaccine has promising therapeutic potential for the treatment of AD and FTD.

Beta-amyloid (Aβ) oligomers are strongly associated with the cascade of harmful events leading to neurodegeneration in Alzheimer's disease (AD). Elimination of Aβ oligomers or inhibition of Aβ assembly is a valuable therapeutic approach for the treatment of AD. Here, we obtained a mimotope of Aβ oligomers, AOEP2, by screening a peptide library using oligomer-specific antibodies. The antibodies induced by AOEP2 specifically recognize Aβ oligomers rather than monomers and fibrils. Interestingly, the AOEP2 peptide binds to Aβ monomers and inhibits the formation of Aβ oligomers and β-sheet structure, reduces Aβ42-induced neurotoxicity, and decreases the release of proinflammatory cytokines. Taken together, AOEP2, a novel multifunctional peptide directly or indirectly targeting Aβ, has promising therapeutic potential for AD.