Targeted Drug Delivery Using a Calf Intestinal Alkaline Phosphatase Bound Aptamer
Introduction & Background
Septic shock is one of the leading causes of death (“Products - Data Briefs - Number 62 - June 2011,” n.d.). It is typically accompanied by a bacterial infection and is characterized by the release of harmful chemicals into the circulatory system. This leads to severe inflammation that can cause low blood pressure, tissue death, organ failure, and in some cases even death. (“Sepsis Symptoms, Causes, Treatment - Why are there so many diseases with,” n.d.). During periods of inflammation, the production of alkaline phosphatases increases which acts to mediate the inflammation and thereby reduced the severity of bacterial based diseases. (Chantal et al., 2003). By taking a targeted drug delivery approach an aptamer can be used as a therapeutic. Aptamers are nucleic acid sequences that have a strong affinity for a particular protein or molecule. They can exist as either a RNA or DNA molecule, however the DNA form is typically more stable because RNA molecules are single stranded and tend to fold over and form secondary and tertiary structures. (Lai & DeStefano, 2011). Aptamers have various practical applications that range from therapeutics to diagnostics. They can be used to mimic antibodies and even treat various types of cancers. Even more, aptamers are cost effective and easy to manipulate. As a result recent research has started taking advantage of their unique specificity. In this application and aptamer that binds to CIAP will be used to deliver drugs such as resolvin, protectin, or maresins which all function to counter bacterial induced inflammation (Campbell et al., 2010). CIAP is found in the bovine bone, liver and intestine (Beumer et al., 2003), and it function as a catalyst for the removal of phosphate groups from the 5’ and 3’ ends of DNA and RNA (Biesterveld et al., 2015). Gram negative bacteria such as Escherichia coli can cause lipopolysaccharide (LPS) mediated diseases like sepsis. CIAP can detoxify the LPS cell membrane of these bacteria, and act to reduce the tumor necrosis factor alpha that causes apoptosis during septic shock (Chantal et al., 2003). It can even purify the bloodstream by dephosphorylating the toxic LPS side chain (Vesy et al., 2000). There are various other applications for aptamers against CIAP that have already been detected. For example, in an enzyme linked immunoabsorbant assay (ELISA) an antibody is used to detect and antigen (protein). Recent research has found an aptamer against CIAP that can be used in place of the antibody in an ELISA (Razvan & Yingfu, 2005). This presents many advantages because aptamers are more economical, easier to manipulate, and more diverse than antibodies. This type of application takes a diagnostic route by using an aptamer to bind to an antigen that has been immobilized onto a surface. When the aptamer binds to the antigen it can then behave as a reporter molecules by giving off a fluorescent color when a substrate binds to it.
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Citiations
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Campbell, E. L., MacManus, C. F., Kominsky, D. J., Keely, S., Glover, L. E., Bowers, B. E., … Colgan, S. P. (2010). Resolvin E1-induced intestinal alkaline phosphatase promotes resolution of inflammation through LPS detoxification. Proceedings of the National Academy of Sciences, 107(32), 14298–14303. http://doi.org/10.1073/pnas.0914730107
Chantal, B., Marty, W., Willem, R., Daniëlle, F., Rudd, B., & Willem, S. (2003). Calf Intestinal Alkaline Phosphatase, a Novel Therapeutic Drug for Lipopolysaccharide (LPS)-Mediated Diseases, Attenuates LPS Toxicity in Mice and Piglets. JPET, vol. 307(no. 2), 737–744.
Lai, Y.-T., & DeStefano, J. J. (2011). A primer-free method that selects high affinity single stranded DNA aptamers using Thermostable RNA Ligase. Analytical Biochemistry, 414(2), 246–253. http://doi.org/10.1016/j.ab.2011.03.018
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Razvan, N., & Yingfu, L. (2005). Aptamers with Xuorescence-signaling properties. ELSEVIER, 16*25.
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Tian, X.-J., Song, X.-H., Yan, S.-L., Zhang, Y.-X., & Zhou, H.-M. (2003). Study of refolding of calf intestinal alkaline phosphatase. Journal of Protein Chemistry, 22(5), 417–422.
Vesy, C. J., Kitchens, R. L., Wolfbauer, G., Albers, J. J., & Munford, R. S. (2000). Lipopolysaccharide-Binding Protein and Phospholipid Transfer Protein Release Lipopolysaccharides from Gram-Negative Bacterial Membranes. Infection and Immunity, 68(5), 2410–2417. http://doi.org/10.1128/IAI.68.5.2410-2417.2000