Scavenger Receptor and Targeting Strategies. In: Devarajan PV, Dandekar P, D'souza AA, editors. Targeted Intracellular Drug Delivery by Receptor Mediated Endocytosis. Cham: Springer International Publishing; 2019. pp. 297-321. [DOI: 10.1007/978-3-030-29168-6_10]

Formation of polyphenol-based nanoparticles in dried hawthorn with enhanced in vitro absorption over free polyphenols

Plant-derived nanoparticles are gaining attention for enhancing the delivery and bioavailability of bioactive compounds, though the mechanisms remain unclear. This study aims to investigate dried hawthorn-derived nanoparticles (DHNPs), focusing on their composition, molecular interactions and impact on polyphenol absorption. The results showed that DHNPs, averaging 275.7 nm, were primarily composed of polysaccharides and high content of polyphenolic compounds (~25 %), with covalent and non-covalent interactions forming between them. Saponification increased the polyphenol release, and metabolomics identified 252 polyphenolic compounds, with 195 showing a relative increase post-treatment, including caffeic acid and (-)-catechin. An in vitro intestinal absorption test using Caco-2 cell monolayer model demonstrated that DHNPs-bound polyphenols exhibited significantly higher permeability (27.90 %) compared to free polyphenols (12.38 %), indicating that endocytosis may serve as a potential pathway through which DHNPs enhance polyphenol absorption. This study provides new insights into the role of plant-derived nanoparticles contributing to bioactive compound delivery and bioavailability.

Oxidized Low-Density Lipoprotein and Its Role in Immunometabolism

Modified cholesterols such as oxidized low-density lipoprotein (OxLDL) contribute to atherosclerosis and other disorders through the promotion of foam cell formation and inflammation. In recent years, it has become evident that immune cell responses to inflammatory molecules such as OxLDLs depend on cellular metabolic functions. This review examines the known effects of OxLDL on immunometabolism and immune cell responses in atherosclerosis and several other diseases. We additionally provide context on the relationship between OxLDL and aging/senescence and identify gaps in the literature and our current understanding in these areas.

Species-Specific Endotoxin Stimulus Determines Toll-Like Receptor 4- and Caspase 11-Mediated Pathway Activation Characteristics

The innate immune system is the body’s first line of defense against pathogens and its protection against infectious diseases. On the surface of host myeloid cells, Toll-like receptor 4 (TLR4) senses lipopolysaccharide (LPS), the major outer membrane component of Gram-negative bacteria. Intracellularly, LPS is recognized by caspase 11 through the noncanonical inflammasome to induce pyroptosis—an inflammatory form of lytic cell death. While TLR4-mediated signaling perturbations result in secretion of cytokines and chemokines that help clear infection and facilitate adaptive immunity, caspase 11-mediated pyroptosis leads to the release of damage-associated molecular patterns and inflammatory mediators. Although the core signaling events and many associated proteins in the TLR4 signaling pathway are known, the complex signaling events and protein networks within the noncanonical inflammasome pathway remain obscure. Moreover, there is mounting evidence for pathogen-specific innate immune tuning. We characterized the major LPS structures from two different pathogens, modeled their binding to the surface receptors, systematically examined macrophage inflammatory responses to these LPS molecules, and surveyed the temporal differences in global protein secretion resulting from TLR4 and caspase 11 activation in macrophages using mass spectrometry (MS)-based quantitative proteomics. This integrated strategy, spanning functional activity assays, top-down structural elucidation of endotoxins, and secretome analysis of stimulated macrophages, allowed us to identify crucial differences in TLR4- and caspase 11-mediated protein secretion in response to two Gram-negative bacterial endotoxins.

IMPORTANCE Macrophages and monocytes are innate immune cells playing an important role in orchestrating the initial innate immune response to bacterial infection and the tissue damage. This response is facilitated by specific receptors on the cell surface and intracellularly. One of the bacterial molecules recognized is a Gram-negative bacteria cell wall component, lipopolysaccharide (LPS). The structure of LPS differs between different species. We have characterized the innate immune responses to the LPS molecules from two bacteria, Escherichia coli and Bordetella pertussis, administered either extracellularly or intracellularly, whose structures we first determined. We observed marked differences in the temporal dynamics and amounts of proteins secreted by the innate immune cells stimulated by any of these molecules and routes. This suggests that there is specificity in the first line of response to different Gram-negative bacteria that can be explored to tailor specific therapeutic interventions.