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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.

Neutrophils express many G protein-coupled receptors (GPCRs) including the two formyl peptide receptors (FPR1 and FPR2) and the medium chain fatty acid receptor GPR84. The FPRs are known to define a hierarchy among neutrophil GPCRs, i.e., the GPCR-mediated response can be either suppressed or amplified by signals generated by FPRs. In this study, we investigated the position of GPR84 in the FPR-defined hierarchy regarding the activation of neutrophil NADPH-oxidase, an enzyme system designed to generate reactive oxygen species (ROS). When naïve neutrophils are activated by GPR84 agonists a modest ROS release was induced. However, vast amounts of ROS production was induced by these GPR84 agonists in FPR2-desensitized neutrophils, and the response is inhibited not only by a GPR84 antagonist but also by an FPR2 specific antagonist. This suggests that the amplified GPR84 agonist response is achieved through a reactivation of the desensitized FPR2. In addition, the GPR84-mediated FPR2 reactivation was independent of β-arrestin recruitment and sensitive to a protein phosphatase inhibitor. In contrast, the modest ROS production induced by GPR84 agonists was primarily suppressed in FPR1-desensitized neutrophils through hierarchical desensitization of GPR84 by FPR1 generated signals.In summary, our data show that FPRs control the NADPH-oxidase activity mediated through GPR84 in human neutrophils. While an amplified ROS generation is achieved by GPR84 agonists through reactivation of desensitized FPR2, FPR1 heterologously desensitizes GPR84 and by that suppresses the release of ROS induced by GPR84 agonists.

α-synuclein (α-syn) is a protein associated with the pathogenesis of Parkinson’s disease (PD), the second most common neurodegeneration disease with no effective treatment. However, how α-syn drives the pathology of PD remains elusive. Recent studies suggest that α-syn oligomers are the primary cause of neurotoxicity and play a critical role in PD. In this review, we discuss the process of α-syn oligomers formation and the current understanding of the structures of oligomers. We also describe seed and propagation effects of oligomeric forms of α-syn. Then, we summarize the mechanism by which α-syn oligomers exert neurotoxicity and promote neurodegeneration, including mitochondrial dysfunction, endoplasmic reticulum stress, proteostasis dysregulation, synaptic impairment, cell apoptosis and neuroinflammation. Finally, we investigate treatment regimens targeting α-syn oligomers at present. Further research is needed to understand the structure and toxicity mechanism of different types of oligomers, so as to provide theoretical basis for the treatment of PD.

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.

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.

Alzheimer's disease (AD) is characterized by memory loss, intracellular neurofibrillary tangles, and extracellular plaque deposits composed of β-amyloid (Aβ). Previous reports showed that naturally occurring autoantibodies, such as intravenous immunoglobulin (IVIG), benefited patients with moderate-stage AD who carried an APOE-ε4 allele. However, the mechanism underlying the role of IVIG remains unclear. In this study, we identified naturally occurring autoantibodies against Aβ oligomers (NAbs-Aβo), which were purified by Aβ42 oligomer or Cibacron Blue affinity chromatography from IVIG and termed as Oli-NAbs and Blue-NAbs, respectively. Oli-NAbs and Blue-NAbs recognized Aβ42 oligomers or both Aβ40 and 42 oligomers, differently. Both antibodies inhibited Aβ42 aggregation and attenuated Aβ42-induced cytotoxicity. Compared with vehicles, Oli-NAbs, Blue-NAbs and IVIG significantly improved the memory and cognition, and reduced the soluble and oligomeric Aβ levels in APPswe/PS1dE9 transgenic mice. Further investigation showed that Blue-NAbs at increased doses effectively decreased plaque burden and insoluble Aβ levels, whereas Oli-NAbs significantly declined the microgliosis and astrogliosis, as well as the production of proinflammatory cytokines in vivo. Therefore, high levels of these antibodies against oligomeric Aβ40 or Aβ42 were required, correspondingly, to achieve the optimal effect. NAbs-Aβo could be condensed to a high concentration by affinity chromatography and its isolation from IVIG may not interfere with the normal function of conventional IVIG as its concentration is very low. Thus, the isolated NAbs-Aβo as an extra product of plasma required low cost and the enriched NAbs-Aβo may be more feasible than IVIG for the treatment of AD.

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.

It has been suggested that aggregation of α-synuclein (α-syn) into oligomers leads to neurodegeneration in Parkinson's disease (PD), but intravenous immunoglobulin (IVIG) which contains antibodies against α-syn monomers and oligomers fails to treat PD mouse model. The reason may be because IVIG contains much low level of antibodies against α-syn, and of which only a small part can penetrate the blood-brain barrier, resulting in an extremely low level of effective antibodies in the brain, and limiting the beneficial effect of IVIG on PD mice. Here, we first isolated naturally occurring autoantibodies against α-syn (NAbs-α-syn) from IVIG. Our further investigation results showed that NAbs-α-syn inhibited α-syn aggregation and attenuated α-syn-induced cytotoxicity in vitro. Compared with vehicles, NAbs-α-syn significantly attenuated the memory and motor deficits by reducing the levels of soluble α-syn, total human α-syn and α-syn oligomers, decreasing the intracellular p-α-synser129 deposits and axonal pathology, inhibiting the microgliosis and astrogliosis, as well as the production of proinflammatory cytokines, increasing the levels of PSD95, synaptophysin and TH in the brain of A53T transgenic mice. These findings suggest that NAbs-α-syn overcomes the deficiency of IVIG and exhibits a promising therapeutic potential for the treatment of PD.

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 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.

Alzheimer disease (AD) is characterized by extracellular senile plaques, intracellular neurofibrillary tangles, and memory loss. Aggregated amyloid-β (Aβ), oxidative stress, and inflammation have pivotal roles in the pathogenesis of AD. Therefore, the inhibition of Aβ-induced neurotoxicity, oxidative stress, and inflammation is a potential therapeutic strategy for the treatment of AD. In this study, a heptapeptide, isolated from a Ph.D.-C7C library by phage display, attenuated Aβ42-induced cytotoxicity in SH-SY5Y neuroblastoma cells and reduced Aβ42-induced oxidative stress by decreasing the production of reactive oxygen species and glutathione disulfide. As a result, glutathione level increased and superoxide dismutase and glutathione peroxidase activities were enhanced in vitro and in vivo. This peptide also suppressed the inflammatory response by decreasing the release of proinflammatory cytokines, such as tumor necrosis factor α and interleukin 1β, in microglia and by reducing microgliosis and astrogliosis in AD transgenic mice. This peptide was intracerebroventricularly administered to APPswe/PS1dE9 transgenic mice. We found that this peptide significantly improved spatial memory and reduced the amyloid plaque burden and soluble and insoluble Aβ levels. Our findings suggest that this multifunctional peptide has therapeutic potential for an Aβ-targeted treatment of AD.