A new cellular process that accelerates immune cells

Like the police, the immune system depends on division of labor
.
The first is dendritic cells
.
They searched around the clock for traces
of suspected intruders known as antigens.
If they succeed, they rush to the lymphatic vessels, from where they reach the draining lymph nodes
.
There, they presented their findings
to a powerful research team, the T cell group.
These endogenous troops now know which enemy to fight
.

Such an attack must occur before
the intruder causes significant damage or overbreeds.
Therefore, it is important that dendritic cells migrate to the junction of the lymph nodes as quickly as possible
.
Professor Eva Kiermaier, from the Institute for Life and Medical Sciences at the University of Bonn, explains: "We have found a mechanism
that helps them do this.
" To do this, they form more specific structures
called centrosomes.
This helps them stay in their direction for longer, which leads to faster access to lymphatic vessels
.
”

An important function of cell division

Centrosomes belong to organelles – they are molecular complexes responsible for specific tasks in cells, just like
organs in the human body.
Normally, there is only one centrosome
in each human cell.
Shortly before cell division, it doubles
.
The two copies migrate to the poles of the cell and stretch a bundle of fibers between them, known as microtubules
.
Using them, they separate the chromosomes (which also double) during
division.
Thus, each resulting daughter cell acquires a complete set of genetic material as well as one of the
two centrosomes.

Kiermaier emphasizes: "However, centrosomes are also responsible for organizing the cytoskeleton
during cell migration.
We refer to fibrous structural proteins, which give cells shape and provide stability
.
The cytoskeleton also determines the position of
the "front" and "back" in the cell.
This, in turn, affects the direction of
its movement.
Ann-Kathrin Weier, a PhD student at the LIMS Institute, said: "We have now been able to show that dendritic cells form multiple centrosomes
once they are exposed to antigens.
Her colleague Mirka Homrich is the publication's lead author
.
Both completed important parts of
the experiment.

The longer you hold out, the faster you can reach your destination

Dendritic cells have a problem: they don't know where the next lymphatic vessel is, through which they can reach the lymph nodes
.
During the search, they follow a strategy of "trial and error": they run in one direction for a while, and if they do not encounter a ship in the process, they change direction
.
Mirka Homrich said: "The more centrosomes, the longer
they stay before continuing to search in the other direction.
We were able to show in computer simulations that this allowed them to find lymphatic vessels
faster than normal.
"In the process, centrosome proliferation adjusts their staying power to the right degree — so they don't stick to their direction
too stubbornly.
" This will increase their risk
of going astray and getting lost altogether.

The mechanism discovered in the study was previously completely unknown
in healthy cells.
Cancer cells are thought to use it to form metastases
.
However, proliferating centrosomes cannot be freely distributed
within cells.
Otherwise, they can severely disrupt functions
such as cell division.
Thus, in tumor cells and dendritic cells, organelles are clustered in a single location – they clump together
.
"There are now drugs that can disrupt the aggregation of centrosomes," says Kiermaier, who is also a member of the Cluster of Immunosensory Excellence and the interdisciplinary research field "Life and Health" at the University of
Bonn.
"As a result, cancer cells don't divide normally, but die
.
"

However, it is also possible for these substances to interfere with the immune system – after all, centrosomes also gather there
.
"We have tested several of these drugs
in cell culture," she said.
In fact, we have found evidence that they can significantly weaken the effectiveness of
immune defenses.
"If confirmed in clinical trials, this would be bad news because if the active substance is used in cancer treatment, it could have considerable side effects
.
"

Multiple centrosomes enhance migration and immune cell effector functions of mature dendritic cells