Hexokinase II-derived cell-penetrating peptide targets mitochondria and triggers apoptosis in cancer cells.

Overexpression of mitochondria-bound hexokinase II (HKII) in cancer cells plays an important role in their metabolic reprogramming and protects them against apoptosis, thereby facilitating their growth and proliferation. Here, we show that covalently coupling a peptide corresponding to the mitochondrial membrane-binding N-terminal 15 aa of HKII (pHK) to a short, penetration-accelerating sequence (PAS) enhances the cellular uptake, mitochondrial localization, and cytotoxicity of the peptide in HeLa cells. Further analysis revealed that pHK-PAS depolarized mitochondrial membrane potential, inhibited mitochondrial respiration and glycolysis, and depleted intracellular ATP levels. The effects of pHK-PAS were correlated with dissociation of endogenous full-length HKII from mitochondria and release of cytochrome c Of significance, pHK-PAS treatment of noncancerous HEK293 cells resulted in substantially lower cytotoxicity. Thus, pHK-PAS effectively disrupted the mitochondria-HKII association in cancer cells, which led to mitochondrial dysfunction and, finally, apoptosis. Our results demonstrate the potential of the pHK-PAS cell-penetrating peptide as a novel therapeutic strategy in cancer.-Woldetsadik, A. D., Vogel, M. C., Rabeh, W. M., Magzoub, M. Hexokinase II-derived cell-penetrating peptide targets mitochondria and triggers apoptosis in cancer cells.

Hierarchically Porous Calcium Carbonate Scaffolds for Bone Tissue Engineering.

Hierarchically porous CaCO3 scaffolds comprised of micro- (diameter = 2.0 ± 0.3 µm) and nano-sized (diameter = 50.4 ± 14.4 nm) pores were fabricated on silicon substrates using a supercritical CO2-based process. Differentiated human THP-1 monocytes exposed to the CaCO3 scaffolds produced negligible levels of the inflammatory cytokine tumor necrosis factor-alpha (TNF-α), confirming the lack of immunogenicity of the scaffolds. Extracellular matrix (ECM) proteins, vitronectin and fibronectin, displayed enhanced adsorption to the scaffolds compared to the silicon controls. ECM protein-coated CaCO3 scaffolds promoted adhesion, growth, and proliferation of osteoblast MC3T3 cells. MC3T3 cells grown on the CaCO3 scaffolds produced substantially higher levels of transforming growth factor-beta and vascular endothelial growth factor A, which regulate osteoblast differentiation, and exhibited markedly increased alkaline phosphatase activity, a marker of early osteoblast differentiation, compared to controls. Moreover, the CaCO3 scaffolds stimulated matrix mineralization (calcium deposition), an end point of advanced osteoblast differentiation and an important biomarker for bone tissue formation. Taken together, these results demonstrate the significant potential of the hierarchically porous CaCO3 scaffolds for bone tissue engineering applications.

Subcutaneous inverse vaccination with PLGA particles loaded with a MOG peptide and IL-10 decreases the severity of experimental autoimmune encephalomyelitis.

"Inverse vaccination" refers to antigen-specific tolerogenic immunization treatments that are capable of inhibiting autoimmune responses. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), initial trials using purified myelin antigens required repeated injections because of the rapid clearance of the antigens. This problem has been overcome by DNA-based vaccines encoding for myelin autoantigens alone or in combination with "adjuvant" molecules, such as interleukin (IL)-4 or IL-10, that support regulatory immune responses. Phase I and II clinical trials with myelin basic protein (MBP)-based DNA vaccines showed positive results in reducing magnetic resonance imaging (MRI)-measured lesions and inducing tolerance to myelin antigens in subsets of MS patients. However, DNA vaccination has potential risks that limit its use in humans. An alternative approach could be the use of protein-based inverse vaccines loaded in polymeric biodegradable lactic-glycolic acid (PLGA) nano/microparticles (NP) to obtain the sustained release of antigens and regulatory adjuvants. The aim of this work was to test the effectiveness of PLGA-NP loaded with the myelin oligodendrocyte glycoprotein (MOG)35-55 autoantigen and recombinant (r) IL-10 to inverse vaccinate mice with EAE. In vitro experiments showed that upon encapsulation in PLGA-NP, both MOG35-55 and rIL-10 were released for several weeks into the supernatant. PLGA-NP did not display cytotoxic or proinflammatory activity and were partially endocytosed by phagocytes. In vivo experiments showed that subcutaneous prophylactic and therapeutic inverse vaccination with PLGA-NP loaded with MOG35-55 and rIL-10 significantly ameliorated the course of EAE induced with MOG35-55 in C57BL/6 mice. Moreover, they decreased the histopathologic lesions in the central nervous tissue and the secretion of IL-17 and interferon (IFN)-γ induced by MOG35-55 in splenic T cells in vitro. These data suggest that subcutaneous PLGA-NP-based inverse vaccination may be an effective tool to treat autoimmune diseases.

Differential induction of IL-17, IL-10, and IL-9 in human T helper cells by B7h and B7.1.

ICOS and CD28 are expressed by T cells and are involved in costimulation of cytokine production in T helper (TH) cells. ICOS binds B7h expressed by several cell types, whereas CD28 binds B7.1 and B7.2 expressed by activated antigen presenting cells. This work investigated the role of B7h and B7.1 in TH17 and TH9 cell differentiation by assessing activity of recombinant B7h-Fc and B7.1-Fc on human naïve TH cells activated in the presence of different combinations of exogenous cytokines. In the presence of TGF-ß1 and IL-1ß (TH17 promoting condition), B7h-Fc was more effective than B7.1-Fc in inducing IL-17A and IL-10 secretion, whereas B7.1-Fc was more effective in inducing IL-17F. Dual costimulation with B7h-Fc and B7.1-Fc displayed an intermediate pattern with predominance of IL-17F over IL-17A, secretion of high levels of IL-10, and secretion of IL-9 levels lower than those induced by B7.1-Fc alone. In the presence of TGF-ß1 and IL-4 (TH9 promoting condition), B7h-Fc induced IL-17A only, whereas B7.1-Fc induced also IL-17F, IL-10, and high levels of IL-9. Experiments on memory TH cells showed that B7h-Fc mainly supported secretion of IL-17A and IL-10, whereas B7.1-Fc supported secretion of IL-17A, IL-17F, IL-10, and IL-9. These data indicate that B7h and B7.1 play different roles in modulation of TH17 and TH9 differentiation. This plasticity might be important in the immune response to pathogens and tumors, and in the development of autoimmune diseases, and should be taken in consideration in designing of immunotherapeutic protocols triggering ICOS or CD28.

Anti-cytokine autoantibodies in autoimmune diseases.

An overview of the current literature is showing that autoantibodies (AutoAbs) against cytokines are produced in several pathological conditions, including autoimmune diseases, but can also be detected in healthy individuals. In autoimmune diseases, these AutoAbs may also be prognostic markers, either negative (such as AutoAbs to IL-8 and IL-1α in rheumatoid arthritis) or positive (such as AutoAbs to IL-6 in systemic sclerosis and those to osteopontin in rheumatoid arthritis). They may have neutralizing activity and influence the course of the physiological and pathological immune responses. High levels of AutoAbs against cytokines may even lead to immunodeficiency, such as those to IL-17 in autoimmune polyendocrine syndrome type I or those to IFN-γ in mycobacterial infections. Their role in human therapy may be exploited not only through passive immunization but also through vaccination, which may improve the costs for long lasting treatments of autoimmune diseases. Detection and quantification of these AutoAbs can be profoundly influenced by the technique used and standardization of these methods is needed to increase the value of their analysis.