Sugar coating hides cell RNA from the immune system

In our immune system, naked RNA is a sign of a viral or bacterial invasion and must attack. But our cells also have RNA. To avoid the problem, our cells dress up their RNA in sugars, Vijay Rathinam and her colleagues at Uconn School of Medicine and Ryan Flynn at Boston Children’s Hospital Report on August 6 Nature.

Ribonucleic acid (RNA) is a family of large biological molecules fundamental for all forms of life, including viruses, bacteria and animals. Viruses as different as measles, influenza, Sars-COV-2 and rabies have all RNA, so this immune system begins to attack when the RNA sees in the bloodstream or other inappropriate positions. But our cells also have RNA, sometimes they show it on their surface, just to pass the immune cells to see – and yet the immune system ignores it.

“Recognizing RNA as a point of infection is problematic, as every cell in our body has RNA,” says the Uconn Vijay Rathinam immunologist. The question is, how does our immune system distinguish our own RNA from that of dangerous invaders?

Previous research led by Boston Children’s Hospital and Stanford University researchers Ryan Flynn and Carolyn Bertozzi had noticed that our bodies were adding sugars to RNA. These rnas that have coated sugar (also known as glycosylated rnas or glycornas) appear on the cell surface and do not appear to cause the immune system.

Rathinam and his colleagues wondered if sugar was somewhat protective of the sweetener from the immune system. This could be a strategy that uses the body to prevent our RNA from causing inflammation.

When Vincent Graziano, Ph.D. The student in the Rathinam laboratory and the chief writer on paper took Glycorna from human cell crops and blood, cut the sugars and re -introduced it to cells, their immune cells attacked. The cells of the immune system ignored the same RNA when it was elegant.

The sugar content hides our own RNA from the immune system. ”

Vijay Rathinam, Immunologist, Uconn Medical School

It is especially important for our body, because cells are often covered by glycornas. When cells die and are cleansed by the immune system, the RNA sugar overlap prevents dead cells from unnecessary stimulant inflammation.

The findings could help when thinking about autoimmune diseases. Some autoimmune diseases, such as wolf, are associated with specific RNA and dead cells expressing the immune system. Now that scientists understand the role of RNA glycosylation in diverting the attention of the immune system, they can check if this strategy goes a bit wrong and, if so, how it can be corrected.

This study was done in collaboration with the laboratories of Ryan Flynn, Thomas Carell, Franck Barrat, Beiyan Zhou, Sivapriya Kalasan Vanaja, Michael Wilson and Penghua Wang and was funded by grants by the National Health Institutes.