Protein-based biomaterials for combating viral infections: current status and future prospects for development

Altering the mechanical properties of self-assembled filaments through engineering of EspA bacterial protein

Protein-based biomaterials are in high demand due to their high biocompatibility, non-toxicity, and biodegradability. In this study, we explore the bacterial E. coli secreted protein A (EspA), which self-assembles into long extracellular filaments, as a potential building block for new protein-based biomaterials. We investigated the morphological and mechanical properties of EspA filaments and how protein engineering can modify them. Our study include three types of filaments: natural EspA filaments, full-length recombinant EspA filaments, and truncated recombinant EspA filaments lacking a third of the original codon region. The recombinant EspA proteins formed curly, thin filaments with higher longitudinal elasticity (shorter persistence length) compared to the natural, linear filaments. Additionally, the recombinant filaments had a radial elastic modulus about an order of magnitude lower than the natural filaments. The truncated recombinant filaments had a higher radial modulus than the full-length ones, and unlike the purely elastic natural filaments, recombinant filaments were less compliant with the applied force that penetrated them. These differences underscore the potential to modulate EspA filament properties through protein sequence mutations. Our findings suggest EspA as a fundamental element for developing a new biomaterial with a hierarchical structure, enabling the fabrication of macroscopic substances from self-assembled EspA-modulated filaments.

Microencapsulation and nanoencapsulation of bacterial probiotics: new frontiers in Alzheimer's disease treatment

Alzheimer's disease, a progressive neurodegenerative disorder marked by cognitive decline, affects millions worldwide. The presence of amyloid plaques and neurofibrillary tangles in the brain is the key pathological feature, leading to neuronal dysfunction and cell death. Current treatment options include pharmacological approaches such as cholinesterase inhibitors, as well as non-pharmacological strategies like cognitive training and lifestyle modifications. Recently, the potential role of probiotics, particularly strains, such as Lactobacillus and Bifidobacterium, in managing neurodegenerative diseases through the gut-brain axis has garnered significant attention. Probiotics can modulate inflammation, produce neurotransmitters, and support neuronal health, potentially slowing disease progression and alleviating symptoms, such as stress and anxiety. Optimizing the pharmacotherapeutic effects of probiotics is critical and involves advanced formulation techniques, such as microencapsulation and nanoencapsulation. Microencapsulation employs natural or synthetic polymers to protect probiotic cells, enhancing their viability and stability against environmental stressors. Methods like extrusion, emulsion, and spray-drying are used to create microcapsules suited for various applications. Nanoencapsulation, on the other hand, operates at the nanoscale, utilizing polymeric or lipid-based nanoparticles to improve the bioavailability and shelf life of probiotics. Techniques, such as nanoprecipitation and emulsification, are employed to ensure stable nanocapsule formation, thereby augmenting the therapeutic potential of probiotics as nutraceutical agents. This study delves into the essential formulation aspects of microencapsulation and nanoencapsulation for beneficial probiotic strains, aimed at managing Alzheimer's disease by optimizing the gut-brain axis. The insights gained from these advanced techniques promise to enhance probiotic delivery efficacy, potentially leading to improved health outcomes for patients suffering from neurodegenerative disorders.

Simultaneous Activation of Pyroptosis and cGAS-STING Pathway with Epigenetic/ Photodynamic Nanotheranostic for Enhanced Tumor Photoimmunotherapy

Promoting innate immunity through pyroptosis induction or the cyclic GMP-AMP synthase-stimulator of interferon gene (cGAS-STING) pathway activation has emerged as a potent approach to counteract the immunosuppressive tumor microenvironment and elicit systemic antitumor immunity. However, current pyroptosis inducers and STING agonists often suffer from limitations including instability, unpredictable side effects, or inadequate intracellular expression of gasdermin and STING. Here, a tumor-specific nanotheranostic platform that combines photodynamic therapy (PDT) with epigenetic therapy to simultaneously activate pyroptosis and the cGAS-STING pathway in a light-controlled manner is constructed. This approach involves the development of oxidation-sensitive nanoparticles (NP1) loaded with the photosensitizer TBE, along with decitabine nanomicelles (NP2). NP2 enables the restoration of STING and gasdermin E (GSDME) expression, while NP1-mediated PDT facilitates the release of DNA fragments from damaged mitochondria to potentiate the cGAS-STING pathway, and promotes the activation of caspase-3 to cleave the upregulated GSDME into pore-forming GSDME-N terminal. Subsequently, the released inflammatory cytokines facilitate the maturation of antigen-presentation cells, triggering T cell-mediated antitumor immunity. Overall, this study presents an elaborate strategy for simultaneous photoactivation of pyroptosis and the cGAS-STING pathway, enabling targeted photoimmunotherapy in immunotolerant tumors. This innovative approach holds significant promise in overcoming the limitations associated with existing therapeutic modalities and represents a valuable avenue for future clinical applications.

Protein by-products: Composition, extraction, and biomedical applications

Significant upsurge in animal by-products such as skin, bones, wool, hides, feathers, and fats has become a global challenge and, if not properly disposed of, can spread contamination and viral diseases. Animal by-products are rich in proteins, which can be used as nutritional, pharmacologically functional ingredients, and biomedical materials. Therefore, recycling these abundant and renewable by-products and extracting high value-added components from them is a sustainable approach to reclaim animal by-products while addressing scarce landfill resources. This article appraises the most recent studies conducted in the last five years on animal-derived proteins' separation and biomedical application. The effort encompasses an introduction about the composition, an overview of the extraction and purification methods, and the broad range of biomedical applications of these ensuing proteins.