Many have believed that inflammation can lead to cancer. On the contrary, University of Oslo researchers have now found that inflammation can fight cancer.

This means that in the future, cancer may be treated with inflammation-promoting immunotherapy.

After six years of intense work, researchers at the University of Oslo and Oslo University Hospital have found out how the various components of the immune system communicate among themselves to attack cancer cells.

They have discovered that inflammation fights cancer.

Their discovery may change the prevailing view of the connection between inflammation and cancer and lead to an entirely new type of immunotherapy against cancer. The research results were recently published in the prestigious scientific journal Nature Communications.

Inflammation is the body's own defence when a tissue or an organ becomes infected, irritated or damaged in other ways. Typical features of inflammation are swelling, redness, heat and pain. Usually, the inflammation causes the infection or injury to heal, but sometimes the immune system in the body becomes too eager, causing chronic inflammatory diseases.

The medical term is inflammatory diseases. Some examples include arthritis, chronic bowel disease and asthma. These diseases are treated with anti-inflammatory medications.

"Cancer researchers have long believed that the inflammatory reactions in the body are a contributory cause of cancer and can promote the growth of tumours.

A number of chronic inflammatory diseases, such as chronic bowel disease and chronic ulcers, are associated with higher rates of cancer. We have therefore believed that inflammation increases the risk of cancer. Sometimes this is true, but our findings show that certain inflammatory reactions are part of the body's natural defences against cancer.

This is new," says researcher Alexandre Corthay, a member of Professor Bjarne Bogen's research group, which is associated with both the Department of Immunology and Transfusion Medicine and Centre for Immune Regulation at the University of Oslo.

Not all cancer cells that occur in the body turn into cancer. The body's immune system constantly fights cancer cells in the body. Together with research fellow Ole Audun Werner Haabeth and Bjarne Bogen, Corthay studied the inflammatory reactions in the immune system that are important for fighting cancer. The research project has been a collaboration with the Department of Pathology and the Biotechnology Centre at the University of Oslo.

The immune system's language

Inflammation protection against cancer is a close collaboration between two of the immune system's main components: T helper cells and macrophages.

Researchers have described the signalling molecules that are necessary for enabling the T helper cells and macrophages to talk together.

"No one has done this before. We had to develop a completely new method to find the important signalling molecules."

The immune system communicates with over 200 signalling molecules. The researchers tested 33 signalling molecules and found the nine most important in the fight against cancer.

"Three of the nine signalling molecules play a key role in inflammatory reactions. This means that the inflammation-promoting signalling molecules are part of the immune system against cancer."

The T helper cells track down cancer cells by recognizing specific protein changes in cancer cells. Using signalling molecules, T helper cells instruct macrophages in what to do. Often called frontline soldiers, macrophages are big cells that devour other cells. In other words, the macrophages have the bloodthirsty task of killing cancer cells.

Sometimes the solution is more sophisticated. The macrophages can also send out signalling molecules that stop the formation of blood vessels in cancer cells. Blood vessel formation is essential for tumour growth. Without blood, oxygen does not get transported around. The tumours cannot grow and will eventually starve to death.

Immunotherapy against cancer

The three signalling molecules can be used in future immunotherapy against cancer. The researchers envisage that the medication can be injected directly into the tumour.

"When we decode the language of immune cells, we have an opportunity to find out how we can instruct the T helper cells to send the right command to macrophages."

In other words, the new medicine should make sure that the T helper cells command the macrophages locally to fight the tumour.

Checking survival rates

Scientists have to date researched lymphoma and bone marrow cancer in mice. Now the researchers are planning to test the communication system between T helper cells and macrophages in patients with lung, prostate and skin cancer. They will do this by looking for the special signalling molecules in ten- to twenty-year-old cancer samples to see if there is a correlation between signalling molecules and survival.

May stop new cancer treatment

The discovery may be a nail in the coffin for today's new and trendy anti-inflammatory treatment for cancer, which is being tested in the world today. Many cancer experts believe that inflammation is beneficial to the cancer cell. A natural solution is to fight the cancer with anti-inflammatory medicine.

If the researchers theory is correct, there is instead a risk that this treatment does not cure, but rather promotes cancer. Corthay cannot rule out that the test treatment is taking place at Norwegian hospitals.

"Anti-inflammatory treatment against cancer is not a good idea. It is good that this treatment has not progressed so far."

Despite the new recognition that inflammation may suppress cancer, Corthay believes it is important not to scare patients with inflammatory diseases.

"Anti-inflammatory medications are important for alleviating pain and saving lives, but the relationship between the use of these medications over time and increased likelihood of cancer is unclear. New studies are needed," says Corthay.




Source: University of Oslo

Author: Yngve Vogt, journalist, research magazine Apollon, University of Oslo