Are we really alone in this fight against Covid-19?


Pranali Kasat

Nashik, Maharashtra, India

 

The constant surge in pandemic cases is indeed overwhelming. Ever since the rise of Covid-19, it has become a general notion to consider all microorganisms as evil. If truth be told, only the viruses are the bad beings while the rest of the microbes are not. But, could you have imagined that some microbes play a role in battling a war against Covid-19? Let’s find out what could be the scenario exactly.


There are trillions of microbes living, flourishing on and within our body, who call it their home and need it for their survival. According to the Spanish Society for Biochemistry and Molecular Biology, we are half-human, half-bacteria. Isn’t it fascinating? It means our body contains almost the same number of bacteria as that of human cells. These microbes (such as bacteria) inhabit every inch of our body, right from our skin, mouth, digestive tract, respiratory systems and whatnot. This massive pool of microbes is termed the human microbiota.


Different groups of gut microbes. Credit: Design Cells/iStock


Microverse within us is the result of a distinct age-old mutual relationship of our body with these minuscule organisms. Most of us think microorganisms are always evil and harmful. But several scientific studies show that these ubiquitous beings are assisting our body in ways beyond our thoughts. They help us in digestion, communicate with the brain through chemical messages and subsequently aid in mounting immune response against pathogens. This is not it! Just like every individual human has a unique fingerprint, the microbiota of a person is also unique. Because the development of microbiota depends on various factors such as–our birthplace, surrounding, daily diet, medication we consume, etc. To your surprise, it also depends on the people and pets around you. It could be yet another reason to surround yourself with positive people, isn’t it?


In fact, the unique and dynamic microbiota is responsible for dissimilar immune responses to the same disease by different individuals and can also be linked with the severity of Covid-19. How? Well, ever wondered why some people show life-threatening symptoms while others are asymptomatic? The answer could simply be “disturbed microbiota”. The severity of Covid-19 is enormously high in those who are comorbid with modern lifestyle disorders such as diabetes, obesity, cancer, etc. These modern lifestyle disorders are also a result of abnormal microbiota. To understand it further, we need to go through some crucial mechanisms and vital tasks performed by healthy microbiota to safeguard us against diseases.


A healthy gut is a key to a healthy lifestyle. Credit: Qiang Lyu, Cheng-Chih Hsu


The complex and highly diverse microbes from our microbiota fend off viruses and allied pathogens through three primary mechanisms–building a protective filter to block viruses, releasing virus-inhibitory chemicals, and stimulating the immune system. Let’s dive into each mechanism.


Building a protective filter to block viruses


Just like we avoid and block some toxic people, our microbiota does the same thing to their kins. But where do they occur? The largest population of microbes from human microbiota resides within the gut. Most of the consumed food is digested and absorbed in our intestines. However, during this process of digestion, plenty of harmful and toxic by-products are generated which promote the sustenance of pathogens. To keep these by-products and pathogens away from being absorbed into the bloodstream, our intestine produces a protective slimy inner layer–the mucus layer. When the pathogen load increases in the gut, intestinal microbes facilitate the intestine to form a thicker lining of the protective slimy filter which blocks the invasion of pathogens to other organs. But if the mucus layer is damaged, it leads to a condition called leaky gut. It simply means that the pathogens are leaked out through this filter and are capable of affecting other organs. Some studies show “leaky gut” as the main culprit behind the severity of Covid-19 symptoms. The virus gets away through this layer due to “unhealthy microbiota” and infects various organs. Most of the Covid-19 fatalities are the results of virus infecting not just the lungs but also the kidney, liver, heart, and brain. Who would have thought “gut feeling” is so real!

Releasing virus-inhibitory chemicals


Another way with which microbiota guards us against lethal viruses is through the release of inhibitory chemicals. These chemicals are released when gut microbiota feels threatened by the existence of pathogens and viruses in their territories. To defend the grounds, some gut microbiota produces bacteriocin. It is a toxic chemical to bacteria which kills pathogen and halts replication of certain viruses, thus reducing the risk of viral infections.


Additionally, when we consume leafy vegetables, gut microbes help us in our digestion. While they are busy assisting our gut in this process, a fermentative by-product of dietary fibres is formed. This by-product is nothing but a chemical (called Short-Chain Fatty Acids–SCFAs) playing a significant role to elicit an immune response against viruses and reducing lung inflammation. It’s like their way of offering rent to the digestive tract for allowing them to harbour within. Studies have shown that mental stress reduces the bacterial species which produce this elixir-like chemical. The reduction in this chemical eventually increases the susceptibility and severity of many diseases. To make a long story short, Eat Green, Stay Green!


Stimulating the immune system


A group of gut bacteria, known as Bacterioidetes, sends out a chemical message to our army of intestinal immune cells. The army then releases a signalling protein, called interferon, which performs a “surgical strike” on the virus-infected cells in such a way that they undergo a self-destruction mode. This mode again induces an attack on the virus by other classes of immune cells. So, if your gut microbiota is abnormal, you are likely to catch more viral infections than ever.


Gut bacteria sending out signals to intestinal immune cells. Credit: Michael DeForge


For the past few decades, we are fighting with pathogens through the help of antibiotics and vaccines. But they are not as efficient as you may believe. Development of these may also be taking a toll on finances, might cause some undesirable side effects, while some pathogens may even become resistant to the drugs. As many studies hint towards the potential benefits of human microbiota to combating infections, researchers are now using them for finding a cure and executing preventive measures against several diseases. While some researchers believe the solution to “disturbed microbiota” could be replacing it with a healthy microbiota, some scientists hope to create a pill containing all the essential chemicals synthesized by gut microbiota.

As of now, either of these visions is far from our reach. Nevertheless, we can easily achieve “healthy microbiota” at home by increasing dietary fibres and probiotics (like yoghurt) in our diet, regular exercise, and staying stress-free. And yes! We are not alone in this battle against Covid-19. Together we win!



References


  1. Zeppa, D.S., Agostini, D., Piccoli, G., Stocchi, V., and Sestili, P. (2020). Gut Microbiota Status in COVID-19: An Unrecognized Player? Frontiers in Cellular and Infection Microbiology

  2. Binns, N. (2013). Probiotics, Prebiotics And The Gut Microbiota. International Life Sciences Institute Europe

  3. Schroeder, O.B. (2019). Fight them or feed them: how the intestinal mucus layer manages the gut microbiota. Oxford University Press and Sixth Affiliated Hospital of Sun Yat-Sen University

  4. Maltz, R., Keirsey, J., Kim, S., Mackos, A., Gharaibeh, R., Moore, C., Xu, J., Somogyi, A., and Bailey, M. (2019). Social stress affects colonic inflammation, the gut microbiome,and short chain fatty acid levels and receptors. Journal of Pediatric Gastroenterology and Nutrition

  5. https://www.sebbm.es/revista/articulo.php?id=500&url=microbioma-humano-un-universo-en-nuestro-interior

  6. https://www.nationalgeographic.com/science/article/microbes-in-your-gut-may-be-new-recruits-in-the-fight-against-viruses

  7. https://www.bbvaopenmind.com/en/science/research/microbiota-a-microscopic-shield-against-covid-19

  8. https://www.gutmicrobiotaforhealth.com/what-major-scientific-breakthroughs-have-been-made-in-gut-microbiome-science-in-2020


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