Nature: The central function of innate immune cells was discovered

Inflammation and increased mucus secretion are typical symptoms of
nematode infections and allergies.
This immune response involves our innate immune cells, but their exact function is not fully understood
.
A team from Charité-Universit tsmedizin Berlin has now elucidated the key tasks
performed by these cells.
In the study, published in the journal Nature, the researchers also identified potential treatments
for allergies.

The human immune system is made up of two interrelated branches: the adaptive immune system, which learns something new from each infection and evolves throughout life, and the innate immune system, which is less specialized but responds particularly quickly and effectively
.
The cells of the innate immune system are located on the mucous membranes of the respiratory tract and intestines, and they form the first line
of defense where pathogens enter.
These cells include group 2 innate lymphoid cells (ILC2 for short), which are active in the intestines of patients with parasitic diseases and in
the respiratory tract of allergy patients.

"Innate lymphoid cells were discovered about a decade ago, and we already know a lot about them, but their exact function in immune system mechanisms is not yet fully understood," explains
Dr.
Christopher Klose.
"There is a group of adaptive immune cells — T cells — that perform some similar functions as part of the type 2 immune response, so it was previously thought that the role of ILC2 may be redundant and easily replaced
by T cells.
"

However, recently published research disproves this theory
.
Using animal models and state-of-the-art molecular methods such as single-cell sequencing, scientists can zoom in on individual cells and analyze their molecular states, and they have elucidated the core function
of ILC2.

"When ILC2 is lost, a specific type of immune cell called eosinophils cannot develop
properly.
This relationship was unknown before, which was a big surprise
.
"Eosinophils are involved in inflammatory processes
in tissues.
The scientists also found that ILC2 has an important effect
on the ability of epithelial cells to promote mucus production and excrete parasites such as nematodes.
"In our tests that examine the immune response to nematode infection, the absence of ILC2 is clearly visible
.
There is only limited mucus production in the tissues, and the parasite can no longer fight effectively"
.

In further experiments, the researchers examined the symptoms of allergic asthma and found that these symptoms improved
when ILC2 was missing.
Dr Klose said: "This could be the starting point
for future research aimed at developing potential allergy therapies.
" "Through our research, we were able to show that 2 groups of innate lymphoid cells are essential cogs in the immune system mechanism and cannot be replaced
without affecting the immune response.
" In future research projects, Dr.
Klose and his team hope to investigate whether innate lymphoid cells regulate other aspects of
the immune response.

Journal Reference:

1. Jarick, K.
   J.
   , Topczewska, P.
   M.
   , Jakob, M.
   O.
   et al.
   Non-redundant functions of group 2 innate lymphoid cells.
   Nature, 2022 DOI: 10.
   1038/s41586-022-05395-5