It’s a fact that salmonella infection can cause around 420 deaths in the United States each year. This is also worse in Africa as this has become the leading cause of blood infection. The infection that happens is linked to an increased hematopoietic stem cell (HSCs) activity and the production of white blood cells.
Researchers have conducted a series of new experiments. Their goal was to identify how resting HSCs help in the production of mature white blood cells. The hematopoietic stem cells found in mice with a Salmonella Typhimurium infection had more fatty acids than those without the infection. Hence, an increase in the CD36 protein, or what is otherwise known as a surface receptor, was linked to S.typhimurium infection. The additional CD36 receptors helped in the uptake of free fatty acid in order to activate the HSCs and provide an energy source for the infected.
According to the experts from Centers for Disease Control and Prevention (CDC), around 1.35 million people contract a Salmonella infection every year. This count is in the U.S. alone, and this leads to a total of 26,500 hospitalizations and 420 deaths.
The CDC also estimated how foods contaminated with feces transmit 94 percent of the said Salmonella infections. Drinking contaminated water and touching contaminated animals can also lead to infection. There are several symptoms for this, and it includes nausea, vomiting, abdominal cramps, diarrhea, and sepsis.
The S. typhimurium bacteria causes the majority of non-typhoidal salmonella infections. This is said to be the main cause of blood infection (sepsis) in Africa. The fatality rates are 20 to 25 percent.
Infection and stem cells
The infection that’s brought about by salmonella causes an increase in the number of hematopoietic stem cells (HSCs) found in the bone marrow. These are the very cells responsible for hematopoiesis, a process that forms all types of blood cells such as platelets, red blood cells, and white blood cells to help the body fight the infection. Scientists have yet to really comprehend how infection causes hematopoiesis.
HSCs are thought to be generally inactive. They only become active when they sense an infection. They act quickly by increasing the number of white blood cells. Studies made show how activated HSCs use free fatty acids from the body’s fat stores as energy in order to properly respond to the infection that’s happening.
Fatty Acids Become the Energy Source
The building blocks of the fat present in the body are these fatty acids. All fats play important roles, as not too many people are aware of. Of course, some fats are better than others when it comes to the person’s long-term health. Moreover, research conducted has found the connection to an increase in free fatty acids in the blood.
A study was made and this was led by Dr. Stuart Rushworth. He is an Associate Professor of Norwich Medical School, University of East Anglia in the United Kingdom. The study was able to demonstrate higher levels of free fatty acids in the blood of mice 72 hours after they were infected with S. typhimurium.
The details of the study were published in Nature Communications. In it, the details highlight the activity of HSCs in mice that were infected with S.typhimurium. They noticed how the number of HSCs increased 72 hours after infection. These contained more fat than the HSC of mice that didn’t carry the disease.
The results has led them to believe that HSCs can use free fatty acids to generate energy in order to support the increased cellular activity that happens when bacterial infection occurs in the body. “Fighting infection takes a lot of energy, and fat stores are huge energy deposits, which provide the fuel for the blood stem cells to power up the immune response,” Dr. Rushworth explained.
Fatty Acid Uptake Mechanism
It’s a fact that CD36 is a protein that’s located on the surface of HSCs. This moves free fatty acids inside the cell, and once they’re inside, they make their way to the “powerhouse,” otherwise known as the mitochondria, where the cell uses the free fatty acids to create more energy to use.
In the study that was made, the researchers pre-treated the mice with a CD36 inhibitor before they were infected them with S. typhimurium. The HSCs from the CD36-inhibited mice had lower levels of free fatty acids and lower activity levels. Hence, they did not observe an increase in the number of cells that were needed in order to properly and efficiently respond to the infection.
Post-doctoral researcher Dr. Jayna Mistry shared in a tweet, “We show Salmonella infection drives fatty acid uptake by HSCs, an essential process in the immune response to infection.”
More research and work need to be done in the future. In fact, Dr. Rushworth says, “I hope our findings will help improve treatment for vulnerable and older people with infections by strengthening their immune response.”
The research has given a deeper understanding of how HSCs act in the bone marrow when an infection occurs in the body. With more details that could be discovered, there could also be hope for alternative treatments for bacterial infections in the future.
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