Computational design of fusion proteins against ErbB2-amplified tumors inspired by ricin toxin

An open source in silico workflow to assist in the design of fusion proteins

Fusion proteins have the potential to become the new norm for targeted therapeutic treatments. Highly specific payload delivery can be achieved by combining custom targeting moieties, such as VHH domains, with active parts of proteins that have a particular activity not naturally targeted to the intended cells. Conversely, novel drug products may make use of the highly specific targeting properties of naturally occurring proteins and combine them with custom payloads. When designing such a product, there is rarely a known structure for the final construct which makes it difficult to assess molecular behaviour that may ultimately impact therapeutic outcome. Considering the time and cost of expressing a construct, optimising the purification procedure, obtaining sufficient quantities for biophysical characterisation, and performing structural studies in vitro, there is an enormous benefit to conduct in silico studies ahead of wet lab work. By following a repeatable, streamlined, and fast workflow of molecular dynamics assessment, it is possible to eliminate low-performing candidates from costly experimental work. There are, however, many aspects to consider when designing a novel fusion protein and it is crucial not to overlook some elements. In this work, we suggest a set of user-friendly, open-source methods which can be used to screen fusion protein candidates from the sequence alone. We used the light chain and translocation domain of botulinum toxin A (BoNT/A) fused with a selected VHH domain, termed here LC-HN-VHH, as a case study for a general approach to designing, modelling, and simulating fusion proteins. Its behaviour in silico correlated well with initial in vitro work, with SEC HPLC showing multiple protein states in solution and a dynamic protein shifting between these states over time without loss of material.

Oral Live-Carrier Vaccine of Recombinant Lactococcus lactis Inducing Prophylactic Protective Immunity Against Helicobacter pylori Infection

Helicobacter pylori infects the gastric mucosa and induces chronic gastritis, peptic ulcers, and gastric cancer. Research has demonstrated that vaccination can induce a protective immune response and prevent H. pylori infection. Oral administration of the Lactococcus lactis live-carrier vaccine is safe and easily complied with by the public. In this study, two recombinant L. lactis strains were constructed that expressed antigens of H. pylori urease subunit alpha (UreA) and UreA fused with Escherichia coli heat-labile toxin B subunit (LTB-UreA), named LL-UreA and LL-LTB-UreA, respectively. The expression of antigen proteins was confirmed by Western blotting analysis. Survival assessment indicated that the engineered L. lactis could colonize in the digestive tract of BALB/c mice up to 10 days after the last oral administration with our immunization protocol. The ability to induce immune response and immune protective efficacy of the L. lactis were confirmed. These results indicated that oral administration with LL-UreA or LL-LTB-UreA could induce UreA-specific mucosal secretory IgA (sIgA) and cellular immune response, significantly increasing the cytokines levels of interferon-gamma (IFN-γ), interleukin (IL)-17A, and IL-10, together with the proportion of CD4+IFN-γ+ T cells and CD4+IL17A+ T cells. More importantly, oral administration of LL-UreA and LL-LTB-UreA brought about effective protection in mice to prevent H. pylori infection, especially LL-UreA, resulting in 70% of mice showing no H. pylori colonization and the remaining 30% showing only low levels of colonization. These findings underscore the potential of using orally administered engineered L. lactis vaccines to prevent H. pylori infection.

Functionalized 3D Hydroxyapatite Scaffold by Fusion Peptides-Mediated Small Extracellular Vesicles of Stem Cells for Bone Tissue Regeneration

3D printing technology offers extensive applications in tissue engineering and regenerative medicine (TERM) because it can create a three-dimensional porous structure with acceptable porosity and fine mechanical qualities that can mimic natural bone. Hydroxyapatite (HA) is commonly used as a bone repair material due to its excellent biocompatibility and osteoconductivity. Small extracellular vesicles (sEVs) derived from bone marrow mesenchymal stem cells (BMSCs) can regulate bone metabolism and stimulate the osteogenic differentiation of stem cells. This study has designed a functionalized bone regeneration scaffold (3D H-P-sEVs) by combining the biological activity of BMSCs-sEVs and the 3D-HA scaffold to improve bone regeneration. The scaffold utilizes the targeting of fusion peptides to increase the loading efficiency of sEVs. The composition, structure, mechanical properties, and in vitro degradation performance of the 3D H-P-sEVs scaffolds were examined. The composite scaffold demonstrated good biocompatibility, substantially increased the expression of osteogenic-related genes and proteins, and had a satisfactory bone integration effect in the critical skull defect model of rats. In conclusion, the combination of EVs and 3D-HA scaffold via fusion peptide provides an innovative composite scaffold for bone regeneration and repair, improving osteogenic performance.