Researchers can now explain how a cell that is being attacked by bacteria or viruses specifically manages to ‘sound the alarm’ among its neighboring cells so they can react with a quick response. “They’ve succeeded in finding and describing a messenger which both quickly; and effectively can inform the surrounding cells that something is very wrong and that the cells must therefore band together to fight the foreign micro-organisms” says Professor Søren Riis Paludan from the Department of Bio medicine at Aarhus University, Denmark.
He has today published the research results in the journal Nature Microbiology together with Assistant Professor Ramya Nandakumar and a large group of partners from Aarhus, Austria, France; Switzerland and Germany. Ramya Nandakumar can see a number of interesting perspectives in the new findings:
“The study sheds new light on how the organism quickly and effectively alarms the neighbourhood; and now that we know about the mechanism, it makes sense to continue working on when it might be advantageous to give it a boost to inhibit an infection; and vice versa; when it should be blocked in order to halt an autoimmune disease,” says Ramya Nandakumar – we will return to this second point later.
On a general level; the findings fall under the scope of Søren Paludan’s many years of work on understanding how the immune system recognizes infections so that it is able to react with a quick and effective defence. This is a field of research that he has followed and moulded all the way from his postgraduate studies until today – driven by a desire to map how the innate immune system‘s cells respond to infection.
“As I see it; the immune system’s recognition of micro-organisms is one of biology’s most fundamental issues, and one that we; despite more than a century of research; still don’t completely understand;” says Søren Paludan. “The fact that our bodies can be constantly exposed to foreign microorganisms in the form of viruses and bacteria is deeply fascinating; as is the fact that in the vast majority of instances it is able to distinguish between foreign and non-foreign.
This is critical for our ability to fight microorganisms without our immune system attacking the body’s own tissue;” adds Søren Paludan. In the study; researchers cultured cells exposed to the listeria bacteria which can cause the serious but rare type of food poisoning called Listeriosis.
In the petri dish, the researchers uncovered how the attacking listeria bacteria initially penetrated the cell; where they dumped a little of their DNA. The chunk of DNA was then distributed into the cytoplasm; which is the part of a cell that surrounds the cell nucleus. Here the protein cGAS discovered the foreign DNA; and along with the signal protein STING; sent alarm signals into the cell.