3D molecular modeling, free radical modulating and immune cells signaling activities of the novel peptidomimetic L-glutamyl-histamine: possible immunostimulating role

Targeted delivery with peptidomimetic conjugated self-assembled nanoparticles

Peptides produce specific nanostructures, making them useful for targeting in biological systems but they have low bioavailability, potential immunogenicity and poor metabolic stability. Peptidomimetic self-assembled NPs can possess biological recognition motifs as well as providing desired engineering properties. Inorganic NPs, coated with self-assembled macromers for stability and anti-fouling, and conjugated with target-specific ligands, are advancing imaging from the anatomy-based level to the molecular level. Ligand conjugated NPs are attractive for cell-selective tumor drug delivery, since this process has high transport capacity as well as ligand dependent cell specificity. Peptidomimetic NPs can provide stronger interaction with surface receptors on tumor cells, resulting in higher uptake and reduced drug resistance. Self-assembled NPs conjugated with peptidomimetic antigens are ideal for sustained presentation of vaccine antigens to dendritic cells and subsequent activation of T cell mediated adaptive immune response. Self-assembled NPs are a viable alternative to encapsulation for sustained delivery of proteins in tissue engineering. Cell penetrating peptides conjugated to NPs are used as intracellular delivery vectors for gene expression and as transfection agents for plasmid delivery. In this work, synthesis, characterization, properties, immunogenicity, and medical applications of peptidomimetic NPs in imaging, tumor delivery, vaccination, tissue engineering, and intracellular delivery are reviewed.

Phagocytosis of apoptotic bodies by hepatic stellate cells induces NADPH oxidase and is associated with liver fibrosis in vivo

Hepatic stellate cell activation is a main feature of liver fibrogenesis. We have previously shown that phagocytosis of apoptotic bodies by stellate cells induces procollagen alpha1 (I) and transforming growth factor beta (TGF-beta) expression in vitro. Here we have further investigated the downstream effects of phagocytosis by studying NADPH oxidase activation and its link to procollagen alpha1 (I) and TGF-beta1 expression in an immortalized human stellate cell line and in several models of liver fibrosis. Phagocytosis of apoptotic bodies in LX-1 cells significantly increased superoxide production both in the extracellular and intracellular milieus. By confocal microscopy of LX-1 cells, increased intracellular reactive oxygen species (ROS) were detected in the cells with intracellular apoptotic bodies, and immunohistochemistry documented translocation of the NADPH oxidase p47phox subunit to the membrane. NADPH oxidase activation resulted in upregulation of procollagen alpha1 (I); in contrast, TGF-beta1 expression was independent of NADPH oxidase activation. This was also confirmed by using siRNA to inhibit TGF-beta1 production. In addition, with EM studies we showed that phagocytosis of apoptotic bodies by stellate cells occurs in vivo. In conclusion, these data provide a mechanistic link between phagocytosis of apoptotic bodies, production of oxidative radicals, and the activation of hepatic stellate cells.