Page 17 - Dream March 2021

phagocytosis (the process by which a cell uses its plasma membrane to engulf a large particle), and prevention of excessive inflammation. However, it is not that simple and depends a lot on the quality of the microbiome. Different species of the gut microbiome can tilt the balance either towards pro- or anti-inflammatory responses, with the latter being more protective. Thus, different sets of gut microbes play different roles in regulating the immune system.
With regards to COVID-19,
recent studies have shown that specific members of the gut microbiome are always associated with severe disease. They have also been shown to be associated with immune markers known to be present in higher levels during severe disease. The association between gut microbiota and immune markers was found to be greater than that of the other known risk factors of COVID-19 severity, such as age and obesity.
However, we must stop wondering about what role the microbiome has in protecting against a virus that targets the lungs. Research with mice models have shown that if gut microbes are destroyed by antibiotics then the lungs become more susceptible to infection by influenza virus. There are many other studies which have shown that improving the microbiome in the gut by use of prebiotics and probiotics can significantly improve immune response to many infections including to those of the lung.
This is because prebiotics can induce significant shifts in immune and metabolic markers. It has been shown that a diet containing non-digestible carbohydrates such as those found in whole grains caused a decline in the levels of pro-inflammatory cytokine IL-6 and insulin resistance. In a related study, the dietary inclusion of butyrylated high- amylose maize starch improved plasma level of anti-inflammatory cytokine IL-10. These beneficial effects came from
Common fermented foods and potential probiotic isolates on selective media A and C-Curd; B-Rice beer (Xaj Pani); D-Pickle; E and F-Potential probiotic isolates on selective media.
the prebiotic inclusion in diet and is due to production of short-chain fatty acids and improved immune modulation in the gut-associated lymphoid tissue.
Probiotics are live microbes which when administered in adequate amounts confer health benefits on the host. The common probiotics are the bacterial genera Lactobacillus and Bifidobacterium. Fermented milk products and yogurt are rich in probiotics. Probiotic-rich yogurt has been shown to be effective in reducing the counts of the enteric pathogens such as E. coli and Helicobacter pylori. Interestingly, Bifidobacteria along
Metagenomics is a technique of studying microbes recovered directly from environmental samples without culturing them. Using this technique, a significant reduction
of bacterial diversity in the COVID-19 patients has been observed.
with Lactobacilli have been successful as a prophylactic against traveller’s diarrhoea.
Probiotics have also shown good response in improving inflammatory conditions and in regulation of innate immunity using receptors and their corresponding signalling pathways. In mice model- based research it has been shown that T regulatory cells, responsible for reducing the allergic response, are activated on administration of probiotic
bacteria such as Lactobacillus rhamnosus, Bifidobacterium lactis, and Bifidobacterium
breve. Probiotics can modulate the balance between pro-inflammatory and anti-inflammatory cytokines and thereby enhance virus clearance by host immune system. The acute respiratory distress syndrome is a major complication associated with COVID-19. Studies suggest the role of Lactobacillus plantarum in enhancement of anti- inflammatory cytokines and suppression of pro-inflammatory cytokines in young adults. Prebiotics in diet such as wheat bran, beans, and certain root vegetables can increase butyrate levels that leads to reduction in inflammation and improvement in asthma and cystic fibrosis.
Thus, there is sufficient amount of scientific evidence to link the human microbiome with the risk of infection and protection against COVID-19. Further work will likely confirm that pro- inflammatory microbes can contribute to immune responses that make severe cases of COVID-19 more likely. At the same time, this could also mean that beneficial microbial species, the type that promote anti-inflammatory response, can be used to prevent or supplement the treatment in favour of immune alterations that can prevent manifestation of severe COVID-19.
Dr Mojibur R. Khan is Associate Professor II, Life Science Division, IASST Guwahati and Jinu Medhi is UGC SRF, IASST Guwahati. Email: jinumedhi@gmail.com
march2021/dream2047 17