Author: Aline Donker
Oxidative stress is a process that occurs due to an imbalance between reactive oxygen species (ROS) or free radicals and antioxidants in the body. ROS are molecules formed as a by-product of cellular metabolism.
Several molecules take part in the process of oxidative stress, such as superoxide anion (O2−), hydrogen peroxide (H2O2), and hydroxyl radical (•OH). As well as antioxidants like glutathione, vitamin C and E. They can cause damage to cellular components like proteins, lipids, and DNA. This can result in a variety of diseases.
Figure 1: The balance during homeostasis and the imbalance during oxidative stress.
Oxidative stress can occur in many organs, such as the liver, lungs, pancreas, intestines, and even in the eyes.
The liver plays a critical role in detoxification and metabolism, which can generate reactive oxygen species (ROS) as by-products. Excessive ROS production in the liver can result in oxidative stress and damage to liver cells. The liver produces antioxidant enzymes and molecules that can neutralize ROS. But if the liver’s antioxidant defences get overstimulated, it can lead to the accumulation of ROS which results in oxidative stress in other organs.
To counteract oxidative stress, the liver relies on antioxidant molecules such as glutathione and vitamins C and E, to neutralize ROS and prevent damage to cellular components.
Some diseases related to oxidative stress in the liver are viral hepatitis, non-alcoholic fatty liver disease and liver fibrosis.
Figure 2: Factors causing oxidative stress in the liver and conditions occurring as a result of oxidative stress
The lungs are highly susceptible to oxidative stress due to their constant exposure to environmental toxins and pollutants. Oxidative stress in the lungs can lead to inflammation and damage to the lung tissue.
Pancreatic beta cells are very susceptible to oxidative stress because of their high production of reactive oxygen species and their low capacity for antioxidants.
ROS can damage pancreatic beta cells. This impairs the secretion of insulin and glucose metabolism. Oxidative stress can also promote inflammation and pancreatic fibrosis, which can contribute to the development of cancer.
The pancreas plays a role in the regulation of the blood sugar level by producing insulin. Dysfunction of the pancreas can lead to insulin resistance and diabetes. This can impact other organs like the kidneys, eyes and cardiovascular system.
The eyes are also vulnerable to oxidative stress. This can lead to multiple diseases like cataracts, dry eyes and glaucoma. Reactive oxygen species are able to damage the lens and retina, which results in impaired vision and the increased risk of blindness. They can also damage the proteins in the lens of the eye. As an individual ages, this damage accumulates, which contributes to the development of cataract.
Figure 3: Diseases related to oxidative stress in the eyes.
Oxidative stress can also occur in the intestines. Here it can cause alteration in the microbiotics and dysfunction of the intestinal barrier. Oxidative stress can cause dysbiosis in the intestines. As a result of this, the proliferation of harmful bacteria can occur. There is a decrease in beneficial bacteria, which can further contribute to oxidative stress and inflammation in the intestines. Oxidative stress can also damage the intestinal barrier, which prevents harmful substances from entering the bloodstream. As a result of this, intestinal permeability can increase. This leads to the leakage of toxins, bacteria and other harmful substances into the bloodstream.
This article has been prepared from the presentation of our student Aline Donker.
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Edited on: 12 April 2023