Bacteriophages – an element of immunity?
Bacteriophage viruses may be associated with the human immune system
Natalia Pelezneva, Naked Science
Scientists from Australia and the USA stated: bacteriophage viruses (sometimes called "phages") that infect some bacteria are able to penetrate the membranes of the internal organs of the human body. Previously, it was believed that bacteriophages do not interact with eukaryotic cells, including cells of the human body. Researchers suggest that bacteriophages may be associated with the work of the immune system.
Previous work led by bacteriophage researcher Jeremy J. Barr has shown that a significant part of bacteriophages in multicellular organisms is located in the mucus covering the mucous membranes of organs. Barr came to the conclusion that the protein shell of phages is able to bind mucins – components that give mucus and saliva a gel-like consistency. The scientist believes that interaction with mucus helps phages attack bacteria. Thus, the cells of the body are more protected from the effects of bacteria.
In a new paper, Barr and his colleagues stated that phages from mucus are able to penetrate into the epithelium – one of the layers of mucous membranes. The mechanism of their movement is still unknown, but scientists have discovered bacteriophages enclosed in vesicles, small intracellular organoids in which nutrients are usually stored or transported. The experiments were carried out using bacteriophage T4 (Escherichia virus T4) on tissues grown from canine kidney cells. Scientists have come to the conclusion that mucosal cells constantly "capture" phages and move them inside the organ. According to Barr, body tissues can absorb up to 30 billion phages daily. Scientists have not observed the "reverse" movement of phages – from tissues to mucus or the lumen inside the organ.
A picture from an article in mBio – VM.
Researchers believe that bacteriophages living in the human body make up a single aggregate – the phage. Perhaps it can affect the immune system. One of the confirmations of their hypothesis, scientists call a study conducted at Washington University in St. Louis. Its authors found a difference in the diversity of phages in the organisms of healthy people and patients with type I diabetes. Barr believes that some bacteriophages can also protect the body from bacterial infections. For example, in case of infection, phages could "notify" about the presence of bacteria-pathogens of the disease and fight them. Whether this is the case, further research will show.
The authors of the new work emphasize that the activity of phages has not been studied enough. If the conclusions of the new work turn out to be true, it will be possible to apply them in medicine only after decades.
The study is published in the journal mBio (Nguyen et al., Bacteriophage Transcytosis Provides a Mechanism To Cross Epithelial Cell Layers).
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