On the menu this evening, a beautiful nutritious virus that kills bacteria . Does it look out of this world? It may not be in your cells.
In a new study, scientists reveal that a type of bacteriophage found in the human gut (a virus that infects and kills bacteria) helps mammalian cells grow and thrive in what may be a symbiotic relationship. This is surprising because other phages (phages for short) are known to induce inflammatory responses when found in mammalian cells.
This phenomenon, described Thursday October 26 in the journal PLOS Biology, has only been demonstrated in laboratory cells. However, the authors hope the findings will support future research that may impact human health, such as additional research into phage therapy to treat infections with antibiotic-resistant germs .
“[The research] opens up a new area of symbiosis and symbiotic interactions between mammalian cells,” Jeremy Parr , associate professor of biological sciences at Monash University in Australia, told LiveScience. "I think this research suggests that there may be a lot we don't know."
Related: Can viruses that kill bacteria prevent STDs?
Phages are the most abundant biological entities on the planet . They are very small, most measuring between 24 and 200 nanometers; To put things in perspective, a coin is approximately 19 million nanometers. It consists of a DNA or RNA genome surrounded by a protein coat. Although interactions between phages and bacteria have been relatively well studied, the same is not true between phages and mammalian cells.
In the study, researchers looked at a well-known type of phage called T4 that typically infects E. coli bacteria. They applied T4 to three types of mammalian cells in the laboratory: an immune cell called a macrophage extracted from mouse tissue; and human lung and kidney cells derived from cancer lines.
T4 phages did not activate DNA-mediated inflammatory processes in cells. Instead, they trigger signaling pathways that promote cell growth and survival, leading to increased cellular metabolism and reorganization of actin, a protein found in the fluid-filled spaces of mammalian cells. Actin reorganization is necessary for cells to take up substances through macropinocytosis, a phenomenon also known as “ cellular drinking .”
Barr said the broader health implications of the research are not yet known. The researchers also only analyzed one type of phage, although there are approximately 10^15 phages in the intestine . Additionally, the findings could be a side effect of using immortal cancer cell lines, which are already more likely to grow and proliferate.
However, the results should stimulate further research. Phage therapy is generally considered safe , although it is still early in the clinical trial process, and current research suggests that phages may have "many other potential effects" on human cells, a Barr said.
Another way to apply research is the gut microbiome.
“There is interesting research showing that there are certain communities in the gut associated with inflammatory disorders ( inflammatory bowel disease , Crohn's disease ) that have viral signatures,” Barr said.
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"There's a lot of speculation and extrapolation, but it's interesting to think that maybe phages play a role in this, that there might be inflammatory interactions, and that increasing the balance might lead to beneficial interactions in the gut microbiome system,” he said.
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