During lockdown, I spent a lot of ‘ME’ time. I felt more refreshed and ready to start this master’s year. Of course! This year has been exciting, very challenging and most of all, after two months, made me feel like I aged 5 more extra years! Stress IS one of the causes of ageing.
But at the end of the day, we all age. Ageing is inevitable, unstoppable! And even with that in mind, we try to stop or slow it down by doing simple things like meditating, going on walks regularly and yoga as the calm will reduce stress. People also incorporate more vitamins in their diets by eating fruits and vegetables or by taking supplements. Anti-ageing skin care products are always on the market! (But wrinkles will always be creeping). What they all have in common is that they contain antioxidants such as vitamin C and E.
The thought of antioxidants as somewhat anti-ageing may come from their role to alleviate the state of oxidative stress caused by increased levels of reactive oxygen species (ROS) (aka ‘oxidants’) as higher ROS levels is also seen in cellular ageing. ROS are highly reactive and can cause oxidative damage in the cells by reacting with carbohydrates, proteins, lipids and DNA. For instance, oxidative damage to the DNA can cause mutations, and accumulation of these mutations may ultimately lead to cancer. This is why, aside from the antioxidant supplements, our body also has its own antioxidant defence system to prevent oxidative stress.
Peroxisomes are subcellular organelles that can perform a variety of metabolic functions including ROS metabolism. Peroxisomes contain a protein called catalase which has a role in antioxidant defence as it can break down hydrogen peroxide to water and oxygen. Hydrogen peroxide is a technically not a ROS, but it is able to form hydroxyl ions which is an extremely reactive ROS that can damage the phospholipids in the cell membrane and proteins. Because the peroxisomes cannot make its own proteins, catalase is encoded by the nuclear DNA and translated in the cytoplasm. In a healthy cell, catalase is imported into the peroxisome, no problem, and be able to perform its ROS metabolism action! But in ageing cells, the import of catalase is like getting a flat tire on the way to work! It gets stuck in the cytoplasm and unable to perform ROS metabolism. This leads to higher levels of hydrogen peroxide leading to higher levels of ROS leading to oxidative stress and then OXIDATIVE DAMAGE!
What we think is that catalase is also experiencing a flat tire in our immune cells as they age. Our immune system protects our body against infections, tumours and inflammatory diseases. However, the immune system, like everything, also ages and this is called immune ageing. The effects of immune ageing can be seen more prominently in our elderly population with increased susceptibility to infections, inflammatory diseases and cancers. With our ever-ageing population, we need to find more solutions so that we can protect what protect us!
- Henson, S. M. et al.(2014) ‘P38 signaling inhibits mTORC1-independent autophagy in senescent human CD8+ T cells’, Journal of Clinical Investigation, 124(9), pp. 4004–4016. doi: 10.1172/JCI75051.
- Legakis, J. E. et al.(2002) ‘Peroxisome senescence in human fibroblasts’, Molecular Biology of the Cell, 13(2), pp. 4243-4255. doi: 10.1091/mbc.E02-06-0322.
- Liguori, I. et al.(2018) ‘Oxidative stress, aging, and diseases’, Clinical Interventions in Aging, 13, pp. 757-772. doi: 10.2147/CIA.S158513.
- National Center for Complementary and Integrative Health (2013) Antioxidants: In Depth. Available at: https://www.nccih.nih.gov/health/antioxidants-in-depth (Accessed: 26 November 2020).
- Weyand, C. M. and Goronzy, J. J. (2016) ‘Aging of the immune system: Mechanisms and therapeutic targets’, in Annals of the American Thoracic Society, 13(Suppl 5), pp. S422-S428. doi: 10.1513/AnnalsATS.201602-095AW.
Thanks for sharing information.