Size and targeting to PECAM vs ICAM control endothelial delivery, internalization and protective effect of multimolecular SOD conjugates

Abstract

Controlled endothelial delivery of SOD may alleviate abnormal local surplus of superoxide involved in ischemia-reperfusion, inflammation and other disease conditions. Targeting SOD to endothelial surface vs. intracellular compartments is desirable to prevent pathological effects of external vs. endogenous superoxide, respectively. Thus, SOD conjugated with antibodies to cell adhesion molecule PECAM (Ab/SOD) inhibits pro-inflammatory signaling mediated by endogenous superoxide produced in the endothelial endosomes in response to cytokines. Here we defined control of surface vs. endosomal delivery and effect of Ab/SOD, focusing on conjugate size and targeting to PECAM vs. ICAM. Ab/SOD enlargement from about 100 to 300 nm enhanced amount of cell-bound SOD and protection against extracellular superoxide. In contrast, enlargement inhibited endocytosis of Ab/SOD and diminished mitigation of inflammatory signaling of endothelial superoxide. In addition to size, shape is important: endocytosis of antibody-coated spheres was more effective than that of polymorphous antibody conjugates. Further, targeting to ICAM provides higher endocytic efficacy than targeting to PECAM. ICAM-targeted Ab/SOD more effectively mitigated inflammatory signaling by intracellular superoxide in vitro and in animal models, although total uptake was inferior to that of PECAM-targeted Ab/SOD. Therefore, both geometry and targeting features of Ab/SOD conjugates control delivery to cell surface vs. endosomes for optimal protection against extracellular vs. endosomal oxidative stress, respectively.

Up-regulation of NADPH oxidase-mediated redox signaling contributes to the loss of barrier function in KRIT1 deficient endothelium

“…These conjugates (PECAM-AOE) bind to PECAM-1 on the endothelial cell surface and get internalized 20 . Due to this targeting mechanism, PECAM-AOE quench ROS preferentially in the vascular endothelium 21 – 23 . Previous studies have validated the distribution and efficacy of these molecules in vivo and in vitro 24 ; injection of 100 µg of each conjugate was sufficient to inhibit H 2 O 2 or VEGF-induced endothelial permeability in vitro 25 , and ROS-induced pulmonary edema in vivo 26 .…”

Co-coating of receptor-targeted drug nanocarriers with anti-phagocytic moieties enhances specific tissue uptake versus non-specific phagocytic clearance

“…35 We and others have reported the use of ICAM-1 targeting in drug delivery, including protein conjugates, polymer nanoparticles, dendrimers, liposomes, etc., for various therapeutic and diagnostic applications. 40,45–50 Our previous studies have characterized anti-ICAM NCs in cell culture and in mice, 38,40,44,51 providing controls for this study.…”

Antioxidant Activity of SOD and Catalase Conjugated with Nanocrystalline Ceria

“…[ 1 , 2 ]. In most cases, oxidative stress is primarily caused by a deficiency of antioxidants and/or an excess of reactive oxygen/nitrogen species (ROS/RNS) [ 3 ]. According to multiple reports in the literature, superoxide radicals ( , hydrogen peroxide ( ), hydroxyl radicals ( ) and peroxynitrite ( ) cause the most harm in pathological conditions [ 2 , 4 , 5 ].…”

“…Over the past decades, multiple strategies to reduce the impact of oxidative stress have been developed. The use of naturally produced enzymes, such as superoxide dismutase (SOD) or catalase (CAT), or the genetic overexpression of these enzymes, has shown huge potential in in vitro and animal experiments [ 1 , 3 , 8 , 9 ]. In particular, attention has been focused on the effect of SOD therapy in myocardial reperfusion injury.…”