Team:UCL/amandeep/Oxidative Stress

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SOD gene therapy for lungs

Reactive oxygen species (ROS) are free radicals that are generated during oxidative phosphorylation. They have various physiological roles and are removed rapidly from the body [1] . Many papers have suggested that the overproduction of ROS causes DNA damage, cell dysfunction, cell death which lead to the ageing of a cell. Overproduction of ROS is also associated with pathogenesis of some age related diseases including cardiovascular diseases, neurological disorders, and pulmonary diseases [2] . An imbalance between generation of ROS and antioxidant defences leads to oxidative stress in which cell antioxidants are at an insufficient level to keep ROS below a toxic threshold [1] . There are also antioxidant enzymes that naturally occur in the human body, responsible for converting the ROS into less harmful substances. Superoxidise dismutase (SOD) is an important antioxidant enzyme in nearly all living cells exposed to oxygen and is present inside and outside the cell membrane.

SOD enzyme’s catalyses the reaction O-2 + O-2 + 2H+ → H2O2 + O2.

ROS accumulate as we age [3] , therefore the overexpression of SOD is one potential way to decrease the levels free radicals that accumulate.

There are three types of SOD enzymes:

  • SOD1 (Soluble - CuZnSOD) – Involved in removing oxidative stress causing ischemia-reperfusion injury and ischemic heart disease.
  • SOD2 (Mitochondrial - MnSOD) - SOD2 clears mitochondrial reactive oxygen species (ROS).
  • SOD3 (Extracellular - ECSOD) - protect the brain, lungs, and other tissues from oxidative stress.

SOD3, lungs and ageing

SOD3 is found in the extracellular matrix of tissues and is ideally situated to prevent cell and tissue damage initiated by extracellularly produced ROS. It is also the primary extracellular antioxidant enzyme found in the lungs [2] and protects the extracellular matrix during lung injury [4] [5] [6] . It’s been found that mutations in the SOD3 protein is associated with reduced lung function in adults [7] and lung function decline in chronic obstructive pulmonary disease (COPD) [8] [9]. Because of their anatomy, location and function, the lungs are highly susceptible to oxidative damage. [1] One study also showed that SOD3 levels decreased as the mice aged in the lungs [10] .

ROS are mainly produced by phagocytes as well as by the alveolar, bronchial and endothelial cells. Increased oxidant levels and decreased antioxidant defences can contribute to the progression of idiopathic pulmonary fibrosis and other lung diseases. Chronic obstructive pulmonary disease (COPD) is an age related diseases that is also a major public health problem worldwide (fourth leading cause of death in the world) and leads to small airway inflammation, fibrosis and alveolar wall destruction [11] . It is thought that COPD is stimulated by free radicals from cigarette smoke, which lead to chronic inflammation and progressive destruction of lung tissues. COPD prevalence rises with increasing age and SOD3 is an antioxidant and anti-inflammatory protein found in both lung tissue and in the lung lining fluids.

What’s the idea?

Overexpressing SOD3 can be a way to prevent excessive ROS building up in the lungs causing chronic inflammation and COPD. Our strategy is to design a gene therapy that releases SOD3 enzyme when oxidative stress is detected in the lungs.

  • SOD3 has not been used in any iGEM projects before
  • There has been attempts of making an oral supplement with pure SOD enzyme to act as an ageing therapy, but it's been found that the SOD protein molecule is easily deactivated by harsh acids and enzymes contained in the digestive tract.
  • Possibly put it with a human oxidative stress promotor that was made by Turkey ATOMS – Nfkb (http://parts.igem.org/wiki/index.php?title=Part:BBa_K1456015).
  • Nfkb is a transcription factor and is found in nearly all cell types in the body and binds to the promotor when ROS is present.
  • The product: Inhaler device which has a lentivirus containing the SOD3 gene. The inhaler will deliver the system into the lungs where it will incorporate into the host DNA. Is an inhaler that is a gene therapy that can be given to an individual that is suffering with a lung associated age related disease (prevent progression of COPD due to oxidative damage) or can be given to anyone as a preventative method (mop up ROS as you age).

Lycopene probiotic

Lycopene is an antioxidant naturally occuring in tomatoes, giving them their rich red colour. This antioxidant is also known to be lacking in the elderly population, meaning there are higher levels of unregulated oxidative stress. This biobrick is induced by oxidative stress and will then produce lycopene as a mean to 'mop up' the oxidative stress in the environment in the form of a probiotic.

References

  • [1] Bargagli, E., Olivieri, C., Bennett, D., Prasse, A., Muller-Quernheim, J. and Rottoli, P. (2009). Oxidative stress in the pathogenesis of diffuse lung diseases: A review. Respiratory Medicine, 103(9), pp.1245-1256.
  • [2] FATTMAN, C., SCHAEFER, L. and OURY, T. (2003). Extracellular superoxide dismutase in biology and medicine. Free Radical Biology and Medicine, 35(3), pp.236-256.
  • [3] Medina, J. (1996). The clock of ages. Cambridge: Cambridge University Press (Page 258)
  • [4] Ahmed MN, Suliman HB, Folz RJ, Nozik-Grayck E, Golson ML, Mason SN, Auten RL. Extracellular superoxide dismutase protects lung development in hyperoxia-exposed newborn mice. Am J Respir Crit Care Med 167: 400–405, 2003
  • [5] Auten RL, O'Reilly MA, Oury TD, Nozik-Grayck E, Whorton MH. Transgenic extracellular superoxide dismutase protects postnatal alveolar epithelial proliferation and development during hyperoxia. Am J Physiol Lung Cell Mol Physiol 290: L32–L40, 2006.
  • [6] Ghio AJ, Suliman HB, Carter JD, Abushamaa AM, Folz RJ. Overexpression of extracellular superoxide dismutase decreases lung injury after exposure to oil fly ash. Am J Physiol Lung Cell Mol Physiol 283: L211–L218, 2002.
  • [7] Dahl M, Bowler RP, Juul K, Crapo JD, Levy S, Nordestgaard BG. Superoxide dismutase 3 polymorphism associated with reduced lung function in two large populations. Am J Respir Crit Care Med 178: 906–912, 2008.
  • [8] Juul K, Tybjaerg-Hansen A, Marklund S, Lange P, Nordestgaard BG. Genetically increased antioxidative protection and decreased chronic obstructive pulmonary disease. Am J Respir Crit Care Med 173: 858–864, 2006.
  • [9] Wilk JB, Walter RE, Laramie JM, Gottlieb DJ, O'Connor GT. Framingham Heart Study genome-wide association: results for pulmonary function measures. BMC Med Genet 8, Suppl 1: S8, 2007.
  • [10] Daniel Jane-Wit, H. (2012). Special Issue on The Aging Lung: Mechanisms of Dysfunction in Senescent Pulmonary Endothelium. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, [online] 67A(3), p.236. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297765/ [Accessed 18 Aug. 2016].
  • [11] Rebecca E. Oberley-Deegan, J. (2009). Extracellular Superoxide Dismutase and Risk of COPD. COPD, [online] 6(4), p.307. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4075061/ [Accessed 18 Aug. 2016].