Lactic acid bacteria reduce bacterial diarrhea in rabbits via enhancing immune function and restoring intestinal microbiota homeostasis.

BACKGROUND: Numerous previous reports have demonstrated the efficacy of Lactic acid bacteria (LAB) in promoting growth and preventing disease in animals. In this study, Enterococcus faecium ZJUIDS-R1 and Ligilactobaciiius animalis ZJUIDS-R2 were isolated from the feces of healthy rabbits, and both strains showed good probiotic properties in vitro. Two strains (108CFU/ml/kg/day) were fed to weaned rabbits for 21 days, after which specific bacterial infection was induced to investigate the effects of the strains on bacterial diarrhea in the rabbits. RESULTS: Our data showed that Enterococcus faecium ZJUIDS-R1 and Ligilactobaciiius animalis ZJUIDS-R2 interventions reduced the incidence of diarrhea and systemic inflammatory response, alleviated intestinal damage and increased antibody levels in animals. In addition, Enterococcus faecium ZJUIDS-R1 restored the flora abundance of Ruminococcaceae1. Ligilactobaciiius animalis ZJUIDS-R2 up-regulated the flora abundance of Adlercreutzia and Candidatus Saccharimonas. Both down-regulated the flora abundance of Shuttleworthia and Barnesiella to restore intestinal flora balance, thereby increasing intestinal short-chain fatty acid content. CONCLUSIONS: These findings suggest that Enterococcus faecium ZJUIDS-R1 and Ligilactobaciiius animalis ZJUIDS-R2 were able to improve intestinal immunity, produce organic acids and regulate the balance of intestinal flora to enhance disease resistance and alleviate diarrhea-related diseases in weanling rabbits.

Insect cuticle-inspired design of sustainably sourced composite bioplastics with enhanced strength, toughness and stretch-strengthening behavior.

Insect cuticles that are mainly made of chitin, chitosan and proteins provide insects with rigid, stretchable and robust skins to defend harsh external environment. The insect cuticle therefore provides inspiration for engineering biomaterials with outstanding mechanical properties but also sustainability and biocompatibility. We herein propose a design of high-performance and sustainable bioplastics via introducing CPAP3-A1, a major structural protein in insect cuticles, to specifically bind to chitosan. Simply mixing 10w/w% bioengineered CPAP3-A1 protein with chitosan enables the formation of plastics-like, sustainably sourced chitosan/CPAP3-A1 composites with significantly enhanced strength (∼90 MPa) and toughness (∼20 MJ m -3), outperforming previous chitosan-based composites and most synthetic petroleum-based plastics. Remarkably, these bioplastics exhibit a stretch-strengthening behavior similar to the training living muscles. Mechanistic investigation reveals that the introduction of CPAP3-A1 induce chitosan chains to assemble into a more coarsened fibrous network with increased crystallinity and reinforcement effect, but also enable energy dissipation via reversible chitosan-protein interactions. Further uniaxial stretch facilitates network re-orientation and increases chitosan crystallinity and mechanical anisotropy, thereby resulting in stretch-strengthening behavior. In general, this study provides an insect-cuticle inspired design of high-performance bioplastics that may serve as sustainable and bio-friendly materials for a wide range of engineering and biomedical application potentials.

Organized assembly of chitosan into mechanically strong bio-composite by introducing a recombinant insect structural protein OfCPH-1.

Chitosan, known for its appealing biological properties in packaging and biomedical applications, faces challenges in achieving a well-organized crystalline structure for mechanical excellence under mild conditions. Herein, we propose a facile and mild bioengineering approach to induce organized assembly of amorphous chitosan into mechanically strong bio-composite via incorporating a genetically engineered insect structural protein, the cuticular protein hypothetical-1 from the Ostrinia furnacalis (OfCPH-1). OfCPH-1 exhibits high binding affinity to chitosan via hydrogen-bonding interactions. Simply mixing a small proportion (0.5 w/w%) of bioengineered OfCPH-1 protein with acidic chitosan precursor induces the amorphous chitosan chains to form fibrous networks with hydrated chitosan crystals, accompanied with a solution-to-gel transition. We deduce that the water shell destruction driven by strong protein-chitosan interactions, triggers the formation of well-organized crystalline chitosan, which therefore offers the chitosan with significantly enhanced swelling resistance, and strength and modulus that outperforms that of most reported chitosan-based materials as well as petroleum-based plastics. Moreover, the composite exhibits a stretch-strengthening behavior similar to the training living muscles on cyclic load. Our work provides a route for harnessing the OfCPH-1-chitosan interaction in order to form a high-performance, sustainably sourced bio-composite.

Cell volume regulation modulates macrophage-related inflammatory responses via JAK/STAT signaling pathways.

Cell volume as a characteristic of changes in response to external environmental cues has been shown to control the fate of stem cells. However, its influence on macrophage behavior and macrophage-mediated inflammatory responses have rarely been explored. Herein, through mediating the volume of macrophages by adding polyethylene glycol (PEG), we demonstrated the feasibility of fine-tuning cell volume to regulate macrophage polarization towards anti-inflammatory phenotypes, thereby enabling to reverse macrophage-mediated inflammation response. Specifically, lower the volume of primary macrophages can induce both resting macrophages (M0) and stimulated pro-inflammatory macrophages (M1) to up-regulate the expression of anti-inflammatory factors and down-regulate pro-inflammatory factors. Further mechanistic investigation revealed that macrophage polarization resulting from changing cell volume might be mediated by JAK/STAT signaling pathway evidenced by the transcription sequencing analysis. We further propose to apply this strategy for the treatment of arthritis via direct introduction of PEG into the joint cavity to modulate synovial macrophage-related inflammation. Our preliminary results verified the credibility and effectiveness of this treatment evidenced by the significant inhibition of cartilage destruction and synovitis at early stage. In general, our results suggest that cell volume can be a biophysical regulatory factor to control macrophage polarization and potentially medicate inflammatory response, thereby providing a potential facile and effective therapy for modulating macrophage mediated inflammatory responses. STATEMENT OF SIGNIFICANCE: Cell volume has recently been recognized as a significantly important biophysical signal in regulating cellular functionalities and even steering cell fate. Herein, through mediating the volume of macrophages by adding polyethylene glycol (PEG), we demonstrated the feasibility of fine-tuning cell volume to induce M1 pro-inflammatory macrophages to polarize towards anti-inflammatory M2 phenotype, and this immunomodulatory effect may be mediated by the JAK/STAT signaling pathway. We also proposed the feasible applications of this PEG-induced volume regulation approach towards the treatment of osteoarthritis (OA), wherein our preliminary results implied an effective alleviation of early synovitis. Our study on macrophage polarization mediated by cell volume may open up new pathways for immune regulation through microenvironmental biophysical clues.

Relay Catalysis for Selective Aerobic Oxidative Esterification of Primary Alcohols with Methanol.

Esters are bulk and fine chemicals and ubiquitous in polymers, bioactive compounds, and natural products. Their traditional synthetic approach is the esterification of carboxylic acids or their activated derivatives with alcohols. Herein, a bimetallic relay catalytic protocol was developed for the aerobic esterification of one alcohol in the presence of a slowly oxidizing alcohol, which has been identified as methanol. A concise synthesis of phlomic acid was executed to demonstrate the practicality and potential of this reaction.

Zygotic Splicing Activation of the Transcriptome is a Crucial Aspect of Maternal-to-Zygotic Transition and Required for the Conversion from Totipotency to Pluripotency.

During maternal-to-zygotic transition (MZT) in the embryo, mRNA undergoes complex post-transcriptional regulatory processes. However, it is unclear whether and how alternative splicing plays a functional role in MZT. By analyzing transcriptome changes in mouse and human early embryos, dynamic changes in alternative splicing during MZT are observed and a previously unnoticed process of zygotic splicing activation (ZSA) following embryonic transcriptional activation is described. As the underlying mechanism of RNA splicing, splicing factors undergo dramatic maternal-to-zygotic conversion. This conversion relies on the key maternal factors BTG4 and PABPN1L and is zygotic-transcription-dependent. CDK11-dependent phosphorylation of the key splicing factor, SF3B1, and its aggregation with SRSF2 in the subnuclear domains of 2-cell embryos are prerequisites for ZSA. Isoforms generated by erroneous splicing, such as full-length Dppa4, hinder normal embryonic development. Moreover, alternative splicing regulates the conversion of early embryonic blastomeres from totipotency to pluripotency, thereby affecting embryonic lineage differentiation. ZSA is an essential post-transcriptional process of MZT and has physiological significance in generating new life. In addition to transcriptional activation, appropriate expression of transcript isoforms is also necessary for preimplantation embryonic development.

Machine learning-guided co-optimization of fitness and diversity facilitates combinatorial library design in enzyme engineering.

The effective design of combinatorial libraries to balance fitness and diversity facilitates the engineering of useful enzyme functions, particularly those that are poorly characterized or unknown in biology. We introduce MODIFY, a machine learning (ML) algorithm that learns from natural protein sequences to infer evolutionarily plausible mutations and predict enzyme fitness. MODIFY co-optimizes predicted fitness and sequence diversity of starting libraries, prioritizing high-fitness variants while ensuring broad sequence coverage. In silico evaluation shows that MODIFY outperforms state-of-the-art unsupervised methods in zero-shot fitness prediction and enables ML-guided directed evolution with enhanced efficiency. Using MODIFY, we engineer generalist biocatalysts derived from a thermostable cytochrome c to achieve enantioselective C-B and C-Si bond formation via a new-to-nature carbene transfer mechanism, leading to biocatalysts six mutations away from previously developed enzymes while exhibiting superior or comparable activities. These results demonstrate MODIFY's potential in solving challenging enzyme engineering problems beyond the reach of classic directed evolution.

Glycine/alginate-based piezoelectric film consisting of a single, monolithic ß-glycine spherulite towards flexible and biodegradable force sensor.

Development of piezoelectric biomaterials with high piezoelectric performance, while possessing excellent flexibility, biocompatibility, and biodegradability still remains a great challenge. Herein, a flexible, biocompatible and biodegradable piezoelectric ß-glycine-alginate-glycerol (Gly-Alg-Glycerol) film with excellent in vitro and in vivo sensing performance was developed. Remarkably, a single, monolithic ß-glycine spherulite, instead of more commonly observed multiple spherulites, was formed in alginate matrix, thereby resulting in outstanding piezoelectric property, including high piezoelectric constant (7.2 pC/N) and high piezoelectric sensitivity (1.97 mV/kPa). The Gly-Alg-Glycerol film exhibited superior flexibility, enabling complex shape-shifting, e.g. origami pigeon, 40% tensile strain, and repeated bending and folding deformation without fracture. In vitro, the flexible Gly-Alg-Glycerol film sensor could detect subtle pulse signal, sound wave and recognize shear stress applied from different directions. In addition, we have demonstrated that the Gly-Alg-Glycerol film sensor sealed by polylactic acid and beeswax could serve as an in vivo sensor to monitor physiological pressure signals such as heartbeat, respiration and muscle movement. Finally, the Gly-Alg-Glycerol film possessed good biocompatibility, supporting the attachment and proliferation of rat mesenchymal stromal cells, and biodegradability, thereby showing great potential as biodegradable piezoelectric biomaterials for biomedical sensing applications.

The microparticulate inks for bioprinting applications.

Three-dimensional (3D) bioprinting has emerged as a groundbreaking technology for fabricating intricate and functional tissue constructs. Central to this technology are the bioinks, which provide structural support and mimic the extracellular environment, which is crucial for cellular executive function. This review summarizes the latest developments in microparticulate inks for 3D bioprinting and presents their inherent challenges. We categorize micro-particulate materials, including polymeric microparticles, tissue-derived microparticles, and bioactive inorganic microparticles, and introduce the microparticle ink formulations, including granular microparticles inks consisting of densely packed microparticles and composite microparticle inks comprising microparticles and interstitial matrix. The formulations of these microparticle inks are also delved into highlighting their capabilities as modular entities in 3D bioprinting. Finally, existing challenges and prospective research trajectories for advancing the design of microparticle inks for bioprinting are discussed.

Local delivery of stem cell spheroids with protein/polyphenol self-assembling armor to improve myocardial infarction treatment via immunoprotection and immunoregulation.

Stem cell therapies have shown great potential for treating myocardial infarction (MI) but are limited by low cell survival and compromised functionality due to the harsh microenvironment at the disease site. Here, we presented a Mesenchymal stem cell (MSC) spheroid-based strategy for MI treatment by introducing a protein/polyphenol self-assembling armor coating on the surface of cell spheroids, which showed significantly enhanced therapeutic efficacy by actively manipulating the hostile pathological MI microenvironment and enabling versatile functionality, including protecting the donor cells from host immune clearance, remodeling the ROS microenvironment and stimulating MSC's pro-healing paracrine secretion. The underlying mechanism was elucidated, wherein the armor protected to prolong MSCs residence at MI site, and triggered paracrine stimulation of MSCs towards immunoregulation and angiogenesis through inducing hypoxia to provoke glycolysis in stem cells. Furthermore, local delivery of coated MSC spheroids in MI rat significantly alleviated local inflammation and subsequent fibrosis via mediation macrophage polarization towards pro-healing M2 phenotype and improved cardiac function. In general, this study provided critical insight into the enhanced therapeutic efficacy of stem cell spheroids coated with a multifunctional armor. It potentially opens up a new avenue for designing immunomodulatory treatment for MI via stem cell therapy empowered by functional biomaterials.

Shape-recovery of implanted shape-memory devices remotely triggered via image-guided ultrasound heating.

Shape-memory materials hold great potential to impart medical devices with functionalities useful during implantation, locomotion, drug delivery, and removal. However, their clinical translation is limited by a lack of non-invasive and precise methods to trigger and control the shape recovery, especially for devices implanted in deep tissues. In this study, the application of image-guided high-intensity focused ultrasound (HIFU) heating is tested. Magnetic resonance-guided HIFU triggered shape-recovery of a device made of polyurethane urea while monitoring its temperature by magnetic resonance thermometry. Deformation of the polyurethane urea in a live canine bladder (5 cm deep) is achieved with 8 seconds of ultrasound-guided HIFU with millimeter resolution energy focus. Tissue sections show no hyperthermic tissue injury. A conceptual application in ureteral stent shape-recovery reduces removal resistance. In conclusion, image-guided HIFU demonstrates deep energy penetration, safety and speed.

Cleaved SPP1-rich extracellular vesicles from osteoclasts promote bone regeneration via TGFß1/SMAD3 signaling.

Bone remodeling is a tightly coupled process between bone forming osteoblasts (OBs) and bone resorbing osteoclasts (OCs) to maintain bone architecture and systemic mineral homeostasis throughout life. However, the mechanisms responsible for the coupling between OCs and OBs have not been fully elucidated. Herein, we first validate that secreted extracellular vesicles by osteoclasts (OC-EVs) promote osteogenic differentiation of mesenchymal stem cells (MSCs) and further demonstrate the efficacy of osteoclasts and their secreted EVs in treating tibial bone defects. Furthermore, we show that OC-EVs contain several osteogenesis-promoting proteins as cargo. By employing proteomic and functional analysis, we reveal that mature osteoclasts secrete thrombin cleaved phosphoprotein 1 (SPP1) through extracellular vesicles which triggers MSCs osteogenic differentiation into OBs by activating Transforming Growth Factor ß1 (TGFß1) and Smad family member 3 (SMAD3) signaling. In conclusion, our findings prove an important role of SPP1, present as cargo in OC-derived EVs, in signaling to MSCs and driving their differentiation into OBs. This biological mechanism implies a paradigm shift regarding the role of osteoclasts and their signaling toward the treatment of skeletal disorders which require bone formation.