skip to main content

Listeria in the gut: How our body cells fight infections with good communication and teamwork

04.02.2025 CMFI News

Listeria monocytogenes is a bacterium that enters the body through contaminated food. Common sources are uncooked eggs, raw fish or unwashed fruit and vegetables. In healthy people, an infection usually only causes diarrhea or vomiting. However, it can be life-threatening for pregnant women, newborn babies and people with a weakened immune system. The infection starts in the intestine and can spread from there to other parts of the body. In a new study published in the journal Cell Reports, researchers from the Cluster of Excellence CMFI at the University of Tübingen show how the human body defends itself against these bacterial invaders. They observed that epithelial cells communicate with each other in order to specifically remove cells infected with Listeria - a kind of biological ‘teamwork mechanism’ that only works through good communication.

Intestinal cells as the first line of defense

An infection with Listeria usually begins in the intestine. From there, they can spread further into the body and even infect the brain or placenta of pregnant women. However, the intestine is a high-performance organ that has developed defense mechanisms to prevent such spread. The epithelial cells in the intestine form the first line of defense against Listeria. These cells line the intestinal wall and play an active role in the fight against pathogens.

Communication as a weapon against infections

The team led by Effie Bastounis, Junior Research Group Leader at the CMFI, has discovered that epithelial cells can communicate amazingly fast and precise. As soon as a cell is infected with Listeria, it and its healthy neighboring cells send out warning signals. The infected cell is identified and encircled. The surrounding healthy cells act in concert and exert mechanical pressure to force the infected cell out of the cell cluster.

“It is fascinating to see how essential biomechanical processes are for our immune system. We have now observed several fundamental mechanisms for bacterial infections, without which a targeted immune response against the pathogens would not be possible. This example shows how well our body cells communicate with each other and can thus agree on joint action,” says Effie Bastounis, head of the study.

The principle of the ‘infectious cell’

Lara Hundsdorfer, the first author of the study, adds: “Infected cells could quickly infect the surrounding healthy cells if they remained in the cellular network. Healthy cells recognize the threat and remove the ‘infectious’ cells before the infection spreads. This process protects the organism and is an example of the impressive efficiency of our immune system on a cellular and molecular level.”

State-of-the-art technology for ground-breaking research

The researchers used cell culture methods and state-of-the-art microscopes to decipher the mechanisms. Effie Bastounis' laboratory at the University of Tübingen was equipped with technology worth half a million euros for this purpose. The equipment in her lab is finely tuned to work together and is complemented by custom equipment developed in-house that can, for example, simulate mechanical pulling forces on cells. The equipment enables so-called live cell imaging, i.e. the observation of living cells. This is important because the course of infection and immune defense must be observed on living tissue. Usually, samples used in high-resolution microscopy are dead. With these live images, the researchers were able to follow how infected cells were recognized and pushed out by their neighboring cells. A specific signaling cascade played a decisive role in this process, which was driven by the messenger substance, the enzyme ERK kinase. ERK kinase triggers a multitude of signals and reactions that lead to a network of messenger substances and proteins ensuring that the infected cells are recognized and ultimately removed.

 

Significance for medicine

The results provide the basis for new therapeutic approaches for the treatment of Listeria infections. The development of drugs that strengthen or specifically activate the epithelial cells' defense mechanisms is conceivable.

The discovery that epithelial cells in the intestine can specifically expel infected neighboring cells shows how efficiently our body fights even complex threats. This teamwork at cellular level protects us from infections and shows how much we can still learn from the body's fascinating mechanisms. These findings could also be useful for other bacterial infections. The defense mechanism has also been demonstrated in the bacterial intestinal infection shigellosis and was observed in the living organism in zebrafish.

 

Publication:

Hundsdorfer L, Muenkel M, Aparicio-Yuste R, Sanchez-Rendon JC, Gomez-Benito MJ, Balmes A, Schäffer TE, Velic A, Yeh YT, Constantinou I, Wright K, Özbaykal Güler G, Brokatzky D, Maček B, Mostowy S, Bastounis EE. ERK activation waves coordinate mechanical cell competition leading to collective elimination via extrusion of bacterially infected cells. (2025) Cell Rep. 44(1):115193. doi: 10.1016/j.celrep.2024.115193 .

Scientific contact

Effie Bastounis, PhD

University of Tübingen
Interfaculty Institute of Microbiology and Infection Medicine

effie.bastounis@uni-tuebingen.de
Website

 

Lara Hundsdorfer

University of Tübingen
Interfaculty Institute of Microbiology and Infection Medicine

lara.hundsdorfer@uni-tuebingen.de

 

Press Contact

Leon Kokkoliadis
Media and public relations

Cluster of Excellence “Controlling Microbes to Fight Infections” CMFI
University of Tübingen
Interfaculty Institute of Microbiology and Infection Medicine

Tel: +49 7071 29-74707 / +49 152 346 79 269
E-Mail: leon.kokkoliadis@uni-tuebingen.de