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In recent years, various vaccination strategies have shed new light on the treatment of atherosclerosis. Proprotein convertase subtilisin/Kexin type 9 (PCSK9) is a hot target in the development of antiatherosclerosis vaccine. However, the efficacy of conventional PCSK9 is largely limited by poor immunogenicity and low hapten density. Therefore, we hypothesized whether a nanostructure synthesized by self-assembled carrier protein accompanied by multicopy hapten display could improve the efficacy of vaccine. In this study, bovine serum albumin (BSA) was self-assembled into sub-100 nm nanoparticles via an intermolecular disulfide network as the inner core. Then, sequences of PCSK9 were conjugated onto the surface of nanoparticles by "click" chemistry to consequently form an orderly structured of nanovaccine with repetitive hapten display. Compared with conventional PCSK9 peptide vaccine, our immunization study demonstrated that the PCSK9 multicopy display nanovaccine (PMCDN) was able to induce higher titers of PCSK9 antibody and more efficient lymph node drainage and improve endocytosis by antigen presenting cells.

Additional file 1. Supplementary methods

Additional file 2. Supplementary results

Additional file 1. Supplementary results and methods.

Elevated low-density lipoprotein cholesterol (LDL-C) increases the risk of atherosclerotic cardiovascular disease. Peptide-based PCSK9 vaccines have shown a promising prospect of reducing LDL-C. In peptide vaccine (pVax) design, the peptide antigens need to conjugate with carrier protein (CP). However, CP incorporation can induce undesirable anti-CP antibodies, which sterically mask peptide epitopes from being recognized by specific B cells and impair subsequent therapeutically antibody production. This epitopic suppression has posed a barrier in clinical translation of conjugate vaccines all along. A model CP (keyhole limpet hemocyanin, KLH) is herein camouflaged with serum albumin (SA) into hybrid nanocarriers (SA@N), with PCSK9 peptide being anchored onto the surface to form nanovaccine (SA@NVax). Such camouflage of KLH via high "self" SA coverage is able to inhibit KLH from extracellular immune recognition and prevent detectable anti-KLH antibody production. Furthermore, the nanovaccine around 70 nm stabilized by intermolecular disulfide network is ideal for internalization and biodegradation by antigen presenting cells as well as better retention in draining lymph nodes and spleen. As expected, the SA@NVax efficiently primes higher anti-PCSK9 IgG antibody titer than PCSK9 pVax.

Infection resulting from carbapenem-resistant Klebsiella pneumoniae (CRKP) is an intractable clinical problem. Outer membrane vesicles (OMVs) from CRKP are believed to be potential vaccine candidates. However, their immune response remains elusive due to low structural stability and poor size homogeneity. In this study, hollow OMVs were reinforced internally by size-controlled BSA nanoparticles to obtain uniform and stable vaccines through hydrophobic interaction. The result showed that the BSA-OMV nanoparticles (BN-OMVs) were homogenous with a size around 100 nm and exhibited a core-shell structure. Remarkably, subcutaneous BN-OMVs vaccination mediated significantly higher CRKP specific antibody titers. The survival rate of the mice infected with a lethal dose of CRKP was increased significantly after BN-OMV immunization. The adoptive transfer experiment demonstrated that the protective effect of BN-OMVs was dependent on humoral and cellular immunity. This study demonstrated that the structure optimization improved the immune efficacy of OMVs for vaccine development against CRKP.

Great progress has been made in miRNA nanodelivery for the treatment of myocardial infarction (MI). However, miRNA nanodelivery within the infarct is impeded by microvascular obstruction as a local circulatory disorder caused by microthrombus formation in microvessels. Knowing that low molecular weight heparin (LMWH) can effectively prevent microthrombus formation in microcirculation, it is hypothesized whether surface modification of the nanocarrier with LMWH can overcome microvascular obstruction in the infarct area for better miRNA delivery. Herein, a novel nanocomlex consisting of dendrigraft poly-l-lysine (DGL)-loaded miR-1 inhibitor as the core to decrease apoptosis of cardiomyocytes and LMWH as the shell to overcome microvascular obstruction of the infarct area is developed. The results show that this anti-coagulative nanocomlex is able to reduce microthrombus formation in microvessels and inhibit blood-coagulation factor Xa, thereby overcoming microvascular obstruction in the infarct area. In addition, it further enhances the uptake of miR-1 inhibitor within the infarct and decreases myocardiocyte apoptosis, thus improving the cardiac function and attenuating the myocardial fibrosis. In conclusion, modification of DGL-loaded miR-1 inhibitor with LMWH helps overcome microvascular obstruction in delivering the drug to the infarct area, thus providing a promising therapeutic strategy for achieving a better therapeutic outcome of MI.

Objective: To investigate the expression of Notch signaling pathway after mechanical ventilation and its role in mechanical ventilation and lung injury. Methods: VILI model was established by mechanical ventilation at high tidal volume (VT = 20 ml/kg) for 4 hours. Lung injury and inflammatory response were evaluated. Hes-1 and Hes-5 mRNA levels were measured after mechanical ventilation, and the levels of NICD, Hes-1, and Hes-5 protein were measured. Furthermore, the Notch signaling pathway inhibitor (DAPT 100 mg/kg) was administered intraperitoneally before mechanical ventilation to assess the role of Notch signaling in VILI. Results: Compared with the control group, hypertonic mechanical ventilation induced VILI and increased the expression of inflammatory factors such as TNF-α, IL-6 and MIP-2 in the cell lavage fluid. The level of Hes-5 gene was significantly up-regulated in pulmonary macrophages with high tidal volume ventilation, and the protein levels of NICD and Hes-5 were up-regulated in pulmonary macrophages. The levels of TNF-α, IL-6, MIP-2 and other inflammatory cytokines in the alveolar lavage fluid decreased, and the levels of NICD and Hes-5 were also decreased, after DAPT pretreatment compared with the high tidal volume. The upregulation of p-IκBα and the degradation of IκBα protein in alveolar macrophages after mechanical ventilation was also observed. Conclusion: The expression of Notch signaling pathway protein in alveolar macrophages is upregulated after high tidal volume mechanical ventilation, and is involved in the regulation of mechanical ventilation and lung injury. Our results suggested that NF-κB pathway is likely involved in Notch-mediated mechanisms that underlie mechanical ventilation induced lung injury.

Myocardial infarction (MI), known to be rapidly progressed and fatal, necessitates a timely and effective intervention particularly within golden 24 h. The crux is to develop a therapeutic agent that can early target the infarct site with integrated therapeutic capacity. Finding the AT1 receptor being most over-expressed at 24 h after MI, we developed a nanovector (AT1-PEG-DGL) anchored with AT1 targeting peptide, and simultaneously armed it with specific microRNA-1 inhibitor (AMO-1) to attenuate cardiomyocyte apoptosis. In vivo imaging after IV administration demonstrated that AT1-PEG-DGL quickly accumulated in the MI heart during the desired early period, significantly outperforming the control group without AT1 targeting. Most importantly, a pronounced in-vivo anti-apoptosis effect was observed upon a single IV injection. Apoptotic cell death in the infarct border zone was significantly decreased and the myocardial infarct size was reduced by 64.1% as compared with that in MI control group, promising for early MI treatment.