Published: 23.1.2025
Text: Dominik Eichin
Pictures: Dominik Eichin | Microsoft Bing Create, Runway
Editing: Viestintätoimisto Jokiranta Oy

Don't you just love a good heroic story? One that features a protagonist that deals with adversity, obstacles and personal challenges, but manages to overcome them and is finally able to defeat the villain. I certainly enjoy facing these hardships alongside them and imagining myself in their shoes.

And the great thing is that EVERYONE can be a hero. It doesn't require you to be a colossus; all it takes is four or five moments - moments when your choices really matter and you can show character.

So, it might not be too surprising that heroes can come in all forms and shapes and can be encountered in the most unlikely places. In your own body, for example. Your body is filled with countless little heroes. Just think about it. There are the heroes that are your muscle cells, which allow your heart to beat and your body to move. Or the heroes we call neurons, which allow you to think and read and process this text. However, the heroes I would like to talk to you about today are macrophages.

Macrophages are phagocytes, “cells that eat”, and can take on a wide variety of tasks in your body. One of their most prominent features is their ability to engulf and digest bad guys, such as various particles, dead cells and pathogens. Think of them as the Ghostbusters of your body, which are there to handle strange occurrences. They not only tidy up and clear these entities, but they also present parts of them to other immune cells, leading to a more comprehensive immune response and, therefore, a better way to protect you. They get rid of bad guys and keep you healthy. Furthermore, macrophages are also capable of secreting different substances such as cytokines (small signaling molecules) or growth factors. This allows them to call for assistance, much like the Beacons of Gondor, or to initiate the healing of a wound.

How a macrophage behaves depends a lot on their “mood”. Just like us, they can be affected by their surroundings and can be anything from angry and annoyed to friendly and relaxed. These “moods” fulfil an important purpose, as they dictate how the macrophage interacts with its surroundings. An angry macrophage, often called a M1 macrophage, excels in promoting inflammation, which defends the body against pathogens and combats the growth of cancer cells. It can, however, also injure and damage other surrounding friendly cells. In contrast, a relaxed macrophage, often called a M2 macrophage, does its best to reduce inflammation and support tissue repair and growth.

These “moods” are not fixed states but rather a continuum, and a macrophage can shift (polarize) between them depending on what stimuli it receives. While this sounds smart and convenient, since a macrophage can first remove a pathogen and then help to repair any damage, it also means that a macrophage can fall prey to its surroundings. Just like some tragic heroes, it might do its best to follow its conviction and fulfil its (perceived) destiny, but might fail to see the overall impacts of its actions or stray from its path. One example of this is cancer. In cancer, cells of the body mutate and grow uncontrollably. As part of the process, they secrete growth factors and other molecules into their surroundings. Unfortunately, these factors can fool the macrophage into acting as a M2 phenotype, thereby further promoting cancer cell expansion. Fortunately, to counter this, the same mechanisms can be used to expose the macrophage to the right substances in order to bring it back to its angry phenotype, which can combat the cancer.

New ways of achieving this are constantly being developed. It was discovered that some drugs, which were intended for other purposes, can cause the process of macrophage polarization. In order to assist our heroic macrophages, we are now screening more than 1,000 drugs to discover whether they possess the ability to affect macrophage polarization. With a bit of luck and a lot of perseverance, we will hopefully find the ones that could be used to get our heroes back on the right path.

 

 

 

 

 

Dominik Eichin, PhD,  is a biologist who works as a post-doctoral researcher at the University of Turku. He works in the research group of Academician Sirpa Jalkanen, where he investigates various aspects of the immune system such as its regulation, its interplay with cancer and the importance of the lymphatic system. He thereby focuses on deciphering factors that influence cancer cell metastasis and immune cell activation.

 

Read more:

• https://orcid.org/0000-0002-6772-1086
• https://inflames.utu.fi
• https://celltrafficking.utu.fi/