The surprising connections between the microbial residents of our gut and various human body systems continue to astound. Medical research has uncovered many mechanisms which connect a variety of bacteria and other organisms with our brain, our immune system, our hormones, and more. In this paper, researchers not only found a very strong correlation between a specific gut bacteria and resistance to respiratory viral infections, but also believe they identified the very mechanism which makes this a causation instead of just a correlation. We live in exciting times as such research continues until it gives us actionable changes to make in our own gut microbiome.
Our colons hold anywhere from 3 to 5 pounds of bacteria per average adult, with bacterial counts numbering in the 100’s of billions, even a trillion different bacteria. A few thousand different bacteria species typically account for these totals in a person’s colon with most being common across most individual people. The exact percentages and species vary considerably across populations with pattern depending on diet, exposure to antibiotics, and the microbiomes of others in the household. These bacteria perform various functions for the individual, from digestion to vitamin production to immune stimulation to detoxification and more. The presence or absence of specific microbes like bacteria or fungi or parasites can affect the health of the person across various routes described in other research.
In this study, scientists found that a specific species of bacteria called segmented filamentous bacteria (SFB) conferred clinically significant improvement in immunity against respiratory viruses for mice. Those mice with the bacteria suffered a less severe respiratory infection by viruses they were given. When the mice without the bacteria were given then bacteria and then the influenza virus, they also experienced a less severe form of the illness.
Rather than stopping with the satisfaction of such a finding, they went further and believe they identified the mechanism of this protection. In the mice lungs, one of the first immune cells to interact with a virus and respond to it are basally resident alveolar macrophages. Macrophages in general engulf or “eat” invading organisms, killing them before they cause further harm. In the mice without the SFB, these specific lung macrophages were quickly depleted leaving the lung to suffer further damage from the influenza virus. When SFB were present, these macrophages remain alive and active, decreasing the extent and severity of the flu virus damage in the lung.
This leaves further connections to be answered in understanding how a specific gut bacteria can influence immune cells in the lungs. Our immune systems are intricate and complex with many connections and understandings left to be discovered. The researchers also are hopeful that many other bacteria can be identified that play similar roles in immunity, as they doubt this one bacteria is the only one out of thousands which can do so.
Helping our patients restore healthier, more abundant life requires understanding these connections and learning how to apply them. While we cannot yet point you to a store-shelf SFB probiotic, we can continue to encourage healthy guts from health nutrition in all our patients. Sometimes this includes probiotics and prebiotics (food for good bacteria), but the foundation is a balanced nutrition routine which encourages a wide variety of healthy bacteria to support our other body functions.
Original Article:
Vu L. Ngo, Carolin M. Lieber, Hae-ji Kang, Kaori Sakamoto, Michal Kuczma, Richard K. Plemper, Andrew T. Gewirtz. Intestinal microbiota programming of alveolar macrophages influences severity of respiratory viral infection. Cell Host & Microbe, 2024; DOI: 10.1016/j.chom.2024.01.002
Thanks to Science Daily:
Georgia State University. “Gut microbiota influence severity of respiratory viral infection.” ScienceDaily. ScienceDaily, 30 January 2024. <www.sciencedaily.com/releases/2024/01/240130133532.htm>.
Sanctuary Functional Medicine, under the direction of Dr Eric Potter, IFMCP MD, provides functional medicine services to Nashville, Middle Tennessee and beyond. We frequently treat patients from Kentucky, Alabama, Mississippi, Georgia, Ohio, Indiana, and more... offering the hope of healthier more abundant lives to those with chronic illness.
