Engineered exosomes have become popular drug delivery carriers for cancer treatment. Systemic injection of organotropic exosome carrier leads to efficient targeting and efficacious anti-cancer outcome.

The molecular mechanism by which apolipoprotein E (apoE) suppresses inflammatory cytokine and NO production is unknown. Using an affinity purification approach, we found that peptide mimetics of apoE, derived from its receptor binding domain residues 130–150, bound to the SET protein, which is a potent physiological inhibitor of protein phosphatase 2A (PP2A). Both holo-apoE protein and apoE-mimetic peptides bound to the C-terminal region of SET, which is then associated with an increase in PP2A-mediated phosphatase activity. As physiological substrates for PP2A, the LPS-induced phosphorylation status of signaling MAPK and Akt kinase is reduced following treatment with apoE-mimetic peptides. On the basis of our previous report, in which apoE-mimetic peptides reduced I-κB kinase and NF-κB activation, we also demonstrate a mechanism for reduced production of inducible NO synthase protein and its NO product. These data provide evidence for a novel molecular mechanism by which apoE and apoE-mimetic peptides antagonize SET, thereby enhancing endogenous PP2A phosphatase activity, which reduces levels of phosphorylated kinases, signaling, and inflammatory response.

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Apolipoprotein E (apoE), well known to play a role in lipid transport and cholesterol metabolism, also exerts anti-inflammatory and neuroprotective effects in the central nervous system. Recent clinical and genetic studies display an association between apoE genotype (APOE) and the progression and severity of multiple sclerosis, raising the possibility that modulation of apoE may be a novel treatment for multiple sclerosis. Using a murine experimental autoimmune encephalomyelitis (EAE) model of human multiple sclerosis, we found that a peptidomimetic of apoE protein, COG133, substantially reduces the clinical symptoms of EAE and promotes remission from the disability when administered before or after onset of disease. Most notably, fusion of COG133 to a protein transduction domain creates COG112, a modified apoE-mimetic peptide with significantly enhanced anti-inflammatory bioactivities in vitro, and improved therapeutic effects on EAE in vivo, which renders a nearly full remission from the disability. Histopathological analysis showed that COG112 and COG133 attenuated demyelination and significantly diminished the number of peripheral cells infiltrating into the spinal cord. ApoE mimetics also interfered with several mechanisms relevant to the pathogenesis of EAE and multiple sclerosis, including activation of macrophages, subsequent production of nitric oxide and inflammatory cytokines, and lymphocyte proliferation. These data suggest that apoE mimetics represent a multidimensional therapeutic for multiple sclerosis capable of inhibiting the inflammatory cascade, modulating immune cell function, and reducing clinical signs, which may have novel utility for the treatment of inflammatory autoimmune diseases.