What is miRNA?

NOBEL PRIZE IN MEDICINE 2024 

The 2024 Nobel Prize in Medicine was awarded to scientists Victor Ambros and Gary Ruvkun for their groundbreaking research in the discovery of microRNA (miRNA) and its role in immune regulation and inflammatory diseases. Their work laid the foundation for understanding how these small RNA molecules control gene expression, particularly in inflammatory responses. 

What is miRNA? 

“The information stored in our chromosomes can be compared to a manual of instructions for all the cells in our body. Every cell contains the same chromosomes, and therefore every cell has exactly the same set of genes and the same instructions,” the committee said in a statement, describing the work of the two scientists. 

However, different types of cells—such as muscle and nerve cells—have different characteristics. The two biologists dedicated their careers to researching how these differences arise. 

“The answer lies in gene regulation, which allows each cell to select only the relevant instructions. This ensures that only the appropriate set of genes is activated in each cell type.” 

The Relationship Between miRNA and Cancer 

Gene regulation through microRNA has contributed to the evolution of increasingly complex organisms. When this regulation is disrupted, it can lead to cancer and other conditions found in humans and animals, such as hearing loss and skeletal disorders. 

“MicroRNAs are directly related to cancer. Intensive research is underway to develop therapies that utilize miRNA—either by mimicking miRNA or inhibiting it—to stop cancer progression. There are some technical difficulties, which is why we don’t yet have miRNA-targeted drugs,” said Thomas Perlmann, Secretary-General of the Nobel Committee. Research is ongoing. 

miRNA and the Microbiome 

The discovery of miRNA not only provides potential cancer treatments but also opens up new possibilities for treating chronic inflammatory diseases, such as inflammatory bowel diseases (IBD: Crohn’s disease and ulcerative colitis). This discovery offers critical insights into the connection between miRNA and the microbiome, which plays a key role in dysbiosis and the pathogenesis of these diseases. 

miRNAs regulate inflammation, but they also interact with gut bacteria, influencing the balance of the microbiome. Dysbiosis, the disruption of the “good-bad” bacteria balance, often leads to chronic inflammatory reactions. miRNAs can alter the expression of bacterial genes, modifying the composition of the microbiome. Similarly, bacteria influence the levels of miRNA in the body, leading to either positive or negative changes in gut health. This dynamic interaction can either trigger inflammation or restore the health of the intestinal barrier. 

The Role of Diet 

Diet plays a crucial role in this interaction, as dietary fibers, omega-3 fatty acids, and probiotics can help restore dysbiosis and regulate miRNA levels, improving the condition of patients with IBD. 

Dietary approaches to regulate miRNA and restore the microbiome in patients with inflammatory bowel diseases (IBD) are promising. There is now a wealth of clinical studies supporting this optimistic outlook. 

1. Dietary Fiber: Foods rich in fiber, such as vegetables, legumes, and whole grains, promote the growth of beneficial bacteria (e.g., Bifidobacteria and Lactobacilli). These bacteria produce short-chain fatty acids, which reduce inflammation and regulate miRNA levels associated with inflammation. 

2. Omega-3 Fatty Acids: Omega-3s, found in fatty fish like salmon and in flaxseed oil, have anti-inflammatory properties and help reduce the production of pro-inflammatory miRNA. At the same time, they enhance the growth of beneficial bacteria and improve the integrity of the intestinal barrier. 

3. Probiotics and Prebiotics: Probiotics (natural fermented foods and supplements with live organisms, such as Lactobacillus and Bifidobacterium) and prebiotics (foods that feed beneficial bacteria, e.g., fermented foods and fibers like inulin) help restore the balance of the microbiome. This can contribute to the regulation of miRNA that influences inflammation and repair of the intestinal barrier. 

4. Polyphenols: Antioxidants found in colorful fruits and vegetables—especially dark-colored ones like berries, plums, beets, green tea, and dark chocolate—can affect miRNA, reducing inflammation and improving microbiome function. 

miRNA in Clinical Studies 

Several studies focus on using miRNA as biomarkers to monitor inflammation and disease activity. Dietary interventions that combine the elements mentioned above show promise in reducing levels of inflammatory miRNA and restoring the balance of the microbiome in individuals with IBD. (Link to study)