Longevity Briefs: How Immune Cells Are Tricked Into Protecting Tumours

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: Our immune systems are able to distinguish cancer cells from normal cells, and will attempt to destroy cancers when they are detected. Unfortunately, tumours often develop the ability to evade and even manipulate the immune system in order to help them grow faster. Understanding exactly how cancer cells and immune cells interact, and how we can manipulate the immune system to prevent its subversion by cancer cells, will help us to improve cancer treatments in the future.

What did the researchers do: Tumours promote inflammation in surrounding tissue, which can help cancer cells to proliferate. In this study, researchers wanted to investigate whether this inflammation differed from inflammation occurring in other tissues. They developed a new way to study the immune cells of inflamed tissues, which involved applying complex computer analyses. The study examined the types of immune cells found around patients’ head and neck tumours, and compared this to what they found in tissue samples from patients with gum disease.

Key takeaway(s) from this research: The types of immune cells found in the inflamed tumour environments were very similar to those found in inflamed gum tissue. However, when they looked at a subtype of T cells called regulatory T cells (Tregs), they found a previously undescribed difference between the Tregs in the two types of tissue.

While most T cells boost the activity of the immune system or participate directly in killing diseased cells, Tregs do the opposite, suppressing the activity of other T cells. The researchers found that Tregs in the tumour tissue had two proteins on their surface called IL-1R1 and ICOS. No Tregs in the blood possessed both proteins at once, but about three quarters of the Tregs in the tumours did. These Tregs were particularly good at suppressing the activity of other T cells, thereby protecting the cancer against attack by the immune system.

It seems as though tumours are able to either trick Tregs in their vicinity into becoming more protective, or are able to attract such Tregs to the tumour site. Either way, we could potentially target these Tregs in order to improve cancer therapies, particularly those that work by enhancing the immune system (immunotherapy). Interestingly, an analysis of the genes expressed by T cells from 21 different cancer types revealed that the aforementioned IL-1R1 protein was expressed in all 19 solid-tumours, but not in the two blood cancers. This could explain why some cutting edge immunotherapies work much better against blood cancers than other cancers.