Pyruvate Oxidation Sustains B Cell Antigen-Specific Activation to Exacerbate MASH.

B cells play a crucial role in the pathogenesis of metabolic dysfunction-associated steatohepatitis (MASH), a severe form of steatotic liver disease that if persistent can lead to cirrhosis, liver failure, and cancer. Chronic inflammation and fibrosis are key features of MASH that determine disease progression and outcomes. Recent advances have revealed that pathogenic B cell-derived cytokines and antibodies promote the development of MASH. However, the mechanisms through which B cells promote fibrosis and the metabolic adaptations underlying their pathogenic responses remain unclear. Here, we report that a subset of mature B cells with heightened cytokine responses accumulate in the liver and promote inflammation in MASH. To meet the increased energetic demand of effector responses, B cells increase their ATP production via oxidative phosphorylation (OXPHOS) fueled by pyruvate oxidation in a B cell receptor (BCR)-specific manner. Blocking pyruvate oxidation completely abrogated the inflammatory capacity of MASH B cells. Accordingly, the restriction of the BCR led to MASH attenuation, including reductions in steatosis, hepatic inflammation, and fibrosis. Mechanistically, BCR restriction decreased B cell maturation, activation, and effector responses in the liver, accompanied by decreased T cell- and macrophage-mediated inflammation. Notably, attenuated liver fibrosis in BCR-restricted mice was associated with lower IgG production and decreased expression of Fc-gamma receptors on hepatic stellate cells. Together, these findings indicate a key role for B cell antigen-specific responses in promoting steatosis, inflammation, and fibrosis during MASH.

Machine Learning-Based Classification of Abnormal Liver Tissues Using Relative Permittivity.

The search for non-invasive, fast, and low-cost diagnostic tools has gained significant traction among many researchers worldwide. Dielectric properties calculated from microwave signals offer unique insights into biological tissue. Material properties, such as relative permittivity (εr) and conductivity (σ), can vary significantly between healthy and unhealthy tissue types at a given frequency. Understanding this difference in properties is key for identifying the disease state. The frequency-dependent nature of the dielectric measurements results in large datasets, which can be postprocessed using artificial intelligence (AI) methods. In this work, the dielectric properties of liver tissues in three mouse models of liver disease are characterized using dielectric spectroscopy. The measurements are grouped into four categories based on the diets or disease state of the mice, i.e., healthy mice, mice with non-alcoholic steatohepatitis (NASH) induced by choline-deficient high-fat diet, mice with NASH induced by western diet, and mice with liver fibrosis. Multi-class classification machine learning (ML) models are then explored to differentiate the liver tissue groups based on dielectric measurements. The results show that the support vector machine (SVM) model was able to differentiate the tissue groups with an accuracy up to 90%. This technology pipeline, thus, shows great potential for developing the next generation non-invasive diagnostic tools.

A Structure-based Design Approach for Generating High Affinity BRD4 D1-Selective Chemical Probes.

Chemical probes for epigenetic proteins are essential tools for dissecting the molecular mechanisms for gene regulation and therapeutic development. The bromodomain and extra-terminal (BET) proteins are master transcriptional regulators. Despite promising therapeutic targets, selective small molecule inhibitors for a single bromodomain remain an unmet goal due to their high sequence similarity. Here, we address this challenge via a structure-activity relationship study using 1,4,5-trisubstituted imidazoles against the BRD4 N-terminal bromodomain (D1). Leading compounds 26 and 30 have 15 and 18 nM affinity against BRD4 D1 and over 500-fold selectivity against BRD2 D1 and BRD4 D2 via ITC. Broader BET selectivity was confirmed by fluorescence anisotropy, thermal shift, and CETSA. Despite BRD4 engagement, BRD4 D1 inhibition was unable to reduce c-Myc expression at low concentration in multiple myeloma cells. Conversely, for inflammation, IL-8 and chemokine downregulation were observed. These results provide new design rules for selective inhibitors of an individual BET bromodomain.

Long non-coding RNA ACTA2-AS1 promotes ductular reaction by interacting with the p300/ELK1 complex.

BACKGROUND & AIMS: Biliary disease is associated with a proliferative/fibrogenic ductular reaction (DR). p300 is an epigenetic regulator that acetylates lysine 27 on histone 3 (H3K27ac) and is activated during fibrosis. Long non-coding RNAs (lncRNAs) are aberrantly expressed in cholangiopathies, but little is known about how they recruit epigenetic complexes and regulate DR. We investigated epigenetic complexes, including transcription factors (TFs) and lncRNAs, contributing to p300-mediated transcription during fibrosis. METHODS: We evaluated p300 in vivo using tamoxifen-inducible, cholangiocyte-selective, p300 knockout (KO) coupled with bile duct ligation (BDL) and Mdr KO mice treated with SGC-CBP30. Primary cholangiocytes and liver tissue were analyzed for expression of Acta2-as1 lncRNA by qPCR and RNA in situ hybridization. In vitro, we performed RNA-sequencing in human cholangiocytes with a p300 inhibitor. Cholangiocytes were exposed to lipopolysaccharide (LPS) as an injury model. We confirmed formation of a p300/ELK1 complex by immunoprecipitation (IP). RNA IP was used to examine interactions between ACTA2-AS1 and p300. Chromatin IP assays were used to evaluate p300/ELK1 occupancy and p300-mediated H3K27ac. Organoids were generated from ACTA2-AS1-depleted cholangiocytes. RESULTS: BDL-induced DR and fibrosis were reduced in Krt19-CreERT/p300fl/fl mice. Similarly, Mdr KO mice were protected from DR and fibrosis after SGC-CBP30 treatment. In vitro, depletion of ACTA2-AS1 reduced expression of proliferative/fibrogenic markers, reduced LPS-induced cholangiocyte proliferation, and impaired organoid formation. ACTA2-AS1 regulated transcription by facilitating p300/ELK1 binding to the PDGFB promoter after LPS exposure. Correspondingly, LPS-induced H3K27ac was mediated by p300/ELK1 and was reduced in ACTA2-AS1-depleted cholangiocytes. CONCLUSION: Cholangiocyte-selective p300 KO or p300 inhibition attenuate DR/fibrosis in mice. ACTA2-AS1 influences recruitment of p300/ELK1 to specific promoters to drive H3K27ac and epigenetic activation of proliferative/fibrogenic genes. This suggests that cooperation between epigenetic co-activators and lncRNAs facilitates DR/fibrosis in biliary diseases. LAY SUMMARY: We identified a three-part complex containing an RNA molecule, a transcription factor, and an epigenetic enzyme. The complex is active in injured bile duct cells and contributes to activation of genes involved in proliferation and fibrosis.

Electrodynamic assisted self-assembled fibrous hydrogel microcapsules: a novel 3D in vitro platform for assessment of nanoparticle toxicity.

Nanoparticle (NP) toxicity assessment is a critical step in assessing the health impacts of NP exposure to both consumers and occupational workers. In vitro assessment models comprising cells cultured in a two-dimensional tissue culture plate (2D-TCP) are an efficient and cost-effective choice for estimating the safety risks of NPs. However, in vitro culture of cells in 2D-TCPs distorts cell-integrin and cell-cell interactions and is not able to replicate an in vivo phenotype. Three-dimensional (3D) in vitro platforms provide a unique alternative to bridge the gap between traditional 2D in vitro and in vivo models. In this study, novel microcapsules of alginate hydrogel incorporated with natural polymeric nanofibers (chitin nanofibrils) and synthetic polymeric nanofibers poly(lactide-co-glycolide) are designed as a 3D in vitro platform. This study demonstrates for the first time that electrodynamic assisted self-assembled fibrous 3D hydrogel (3D-SAF hydrogel) microcapsules with a size in the range of 300-500 µm in diameter with a Young's modulus of 12.7-42 kPa can be obtained by varying the amount of nanofibers in the hydrogel precursor solutions. The 3D-SAF microcapsules were found to mimic the in vivo cellular microenvironment for cells to grow, as evaluated using A549 cells. Higher cellular spreading and prolonged proliferation of A549 cells were observed in 3D-SAF microcapsules compared to control microcapsules without the nanofibers. The 3D-SAF microcapsule integrated well plate was used to assess the toxicity of model NPs, e.g., Al2O3 and ZnO. The toxicity levels of the model NPs were found to be dependent on the chemistry of the NPs and their physical agglomeration in the test media. Our results demonstrate that 3D-SAF microcapsules with an in vivo mimicking microenvironment can be developed as a physiologically relevant platform for high-throughput toxicity screening of NPs or pharmaceutical drugs.

Nanonet-nano fiber electrospun mesh of PCL-chitosan for controlled and extended release of diclofenac sodium.

Electrospun nanofiber (EN) technology has been used in the past to generate electrostatically charged multilayer-nanofibers. This platform offers versatile applications including in tissue engineering, drug delivery, wound dressings, and high-efficiency particulate air filters. In this study, we synthesized for the first time nanonet-nanofiber electrospun meshes (NNEMs) of polycaprolactone (PCL)-chitosan (CH) using EN technology. The fabricated NNEMs were utilized for high payload delivery and controlled release of a water-soluble drug. Diclofenac Sodium (DS), a hydrophilic anti-inflammatory drug, was selected as a model drug because of its high aqueous solubility and poor compatibility with insoluble polymers. Various compositions of DS drug-loaded NNEMs (DS-NNEMs) were synthesized. The physicochemical properties such as structure, morphology, and aqueous stability and the chemical properties of DS-NNEMs were evaluated. High drug entrapment efficiency and concentration-dependent drug release patterns were investigated for up to 14 days. Furthermore, the biocompatibility of the DS-NNEMs was tested with NIH 3T3 cells. The physicochemical characterization results showed that the DS drug is a key contributing factor in the generation of nanonet-nanofiber networks during electrospinning. DS-NNEMs also enhanced 3T3 cell adhesion, viability, and proliferation in the nanonet-nano fiber network through the controlled release of DS. The presented EN technology-based biodegradable NNEM material is not only limited for the controlled release of hydrophilic anti-inflammatory drugs, but also can be a suitable platform for loading and release of antiviral drugs.

Nano-fibre Integrated Microcapsules: A Nano-in-Micro Platform for 3D Cell Culture.

Nano-in-micro (NIM) system is a promising approach to enhance the performance of devices for a wide range of applications in disease treatment and tissue regeneration. In this study, polymeric nanofibre-integrated alginate (PNA) hydrogel microcapsules were designed using NIM technology. Various ratios of cryo-ground poly (lactide-co-glycolide) (PLGA) nanofibres (CPN) were incorporated into PNA hydrogel microcapsule. Electrostatic encapsulation method was used to incorporate living cells into the PNA microcapsules (~500 µm diameter). Human liver carcinoma cells, HepG2, were encapsulated into the microcapsules and their physio-chemical properties were studied. Morphology, stability, and chemical composition of the PNA microcapsules were analysed by light microscopy, fluorescent microscopy, scanning electron microscopy (SEM), Fourier-Transform Infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The incorporation of CPN caused no significant changes in the morphology, size, and chemical structure of PNA microcapsules in cell culture media. Among four PNA microcapsule products (PNA-0, PNA-10, PNA-30, and PNA-50 with size 489 ± 31 µm, 480 ± 40 µm, 473 ± 51 µm and 464 ± 35 µm, respectively), PNA-10 showed overall suitability for HepG2 growth with high cellular metabolic activity, indicating that the 3D PNA-10 microcapsule could be suitable to maintain better vitality and liver-specific metabolic functions. Overall, this novel design of PNA microcapsule and the one-step method of cell encapsulation can be a versatile 3D NIM system for spontaneous generation of organoids with in vivo like tissue architectures, and the system can be useful for numerous biomedical applications, especially for liver tissue engineering, cell preservation, and drug toxicity study.

Embedding magnesium metallic particles in polycaprolactone nanofiber mesh improves applicability for biomedical applications.

Magnesium (Mg) metal is of great interest in biomedical applications, especially in tissue engineering. Mg exhibits excellent in vivo biocompatibility, biodegradability and, during degradation, releases Mg ions (Mg2+) with the potential to improve tissue repair. We used electrospinning technology to incorporate Mg particles into nanofibers. Various ratios of Mg metal microparticles (<44 µm diameter) were incorporated into nanofiber polycaprolactone (PCL) meshes. Physicochemical properties of the meshes were analyzed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), mechanical tensile testing, X-ray diffractometry and UV-VIS spectrophotometry. Biological properties of meshes were evaluated in vitro and in vivo. Under mammalian cell culture conditions, Mg-containing meshes released hydrogen gas and relative amounts of free Mg2+ that reflected the Mg/PCL ratios. All meshes were non-cytotoxic for 3T3 fibroblasts and PC-12 pheochromocytoma cells. In vivo implantation under the skin of mice for 3, 8 and 28 days showed that Mg-containing meshes were well vascularized, with improved measures of inflammation and healing compared to meshes without Mg. Evidence included an earlier appearance and infiltration of tissue repairing macrophages and, after 28 days, evidence of more mature tissue remodeling. Thus, these new composite nanofiber meshes have promising material properties that mitigated inflammatory tissue responses to PCL alone and improved tissue healing, thus providing a suitable matrix for use in clinically relevant tissue engineering applications. STATEMENT OF SIGNIFICANCE: The biodegradable metal, magnesium, safely biodegrades in the body, releasing beneficial byproducts. To improve tissue delivery, magnesium metal particles were incorporated into electrospun nanofiber meshes composed of a biodegradable, biocompatible polymer, polycaprolactone (PCL). Magnesium addition, at several concentrations, did not alter PCL chemistry, but did alter physical properties. Under cell culture conditions, meshes released magnesium ions and hydrogen gas and were not cytotoxic for two cell types. After implantation in mice, the mesh with magnesium resulted in earlier appearance of M2-like, reparative macrophages and improved tissue healing versus mesh alone. This is in agreement with other studies showing beneficial effects of magnesium metal and provides a new type of scaffold material that will be useful in clinically relevant tissue engineering applications.

pH-Responsive PLGA Nanoparticle for Controlled Payload Delivery of Diclofenac Sodium.

Poly(lactic-co-glycolic acid) (PLGA) based nanoparticles have gained increasing attention in delivery applications due to their capability for controlled drug release characteristics, biocompatibility, and tunable mechanical, as well as degradation, properties. However, thorough study is always required while evaluating potential toxicity of the particles from dose dumping, inconsistent release and drug-polymer interactions. In this research, we developed PLGA nanoparticles modified by chitosan (CS), a cationic and pH responsive polysaccharide that bears repetitive amine groups in its backbone. We used a model drug, diclofenac sodium (DS), a nonsteroidal anti-inflammatory drug (NSAID), to study the drug loading and release characteristics. PLGA nanoparticles were synthesized by double-emulsion solvent evaporation technique. The nanoparticles were evaluated based on their particle size, surface charge, entrapment efficacy, and effect of pH in drug release profile. About 390-420 nm of average diameters and uniform morphology of the particles were confirmed by scanning electron microscope (SEM) imaging and dynamic light scattering (DLS) measurement. Chitosan coating over PLGA surface was confirmed by FTIR and DLS. Drug entrapment efficacy was up to 52%. Chitosan coated PLGA showed a pH responsive drug release in in vitro. The release was about 45% more at pH 5.5 than at pH 7.4. The results of our study indicated the development of chitosan coating over PLGA nanoparticle for pH dependent controlled release DS drug for therapeutic applications.

Magnesium incorporated chitosan based scaffolds for tissue engineering applications.

Chitosan based porous scaffolds are of great interest in biomedical applications especially in tissue engineering because of their excellent biocompatibility in vivo, controllable degradation rate and tailorable mechanical properties. This paper presents a study of the fabrication and characterization of bioactive scaffolds made of chitosan (CS), carboxymethyl chitosan (CMC) and magnesium gluconate (MgG). Scaffolds were fabricated by subsequent freezing-induced phase separation and lyophilization of polyelectrolyte complexes of CS, CMC and MgG. The scaffolds possess uniform porosity with highly interconnected pores of 50-250 µm size range. Compressive strengths up to 400 kPa, and elastic moduli up to 5 MPa were obtained. The scaffolds were found to remain intact, retaining their original three-dimensional frameworks while testing in in-vitro conditions. These scaffolds exhibited no cytotoxicity to 3T3 fibroblast and osteoblast cells. These observations demonstrate the efficacy of this new approach to preparing scaffold materials suitable for tissue engineering applications.