Immunity system complexity: controlling gut biome (Introduction)

by David Turell , Monday, February 28, 2022, 19:31 (787 days ago) @ David Turell

Specialized lymph cells are identified:

https://medicalxpress.com/news/2022-02-discovery-innate-immunological-memory-intestine....

"Using an intestinal infection model, scientists from the Institut Pasteur and Inserm discovered that innate effector cells—group 3 innate lymphoid cells—act not only during the early stages of infection but can also be trained to develop an innate form of immunological memory that can protect the host during reinfection.

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"The gut mucosa harbors a complex defense system that allows it to combat pathogen infection while maintaining tolerance to commensal microbiota, which are essential for the normal bodily function. This constant surveillance is performed by the innate immune system, which provides early defense in the initial hours after infection. The adaptive immune system then develops a memory for the pathogens that it encounters by activating specific receptors expressed at the surface of B and T lymphocytes, thereby enabling the production of protective antibodies and inflammatory cytokines. Unlike the clearly established function of the adaptive system in long-term tolerance and protection, the role of the innate system in immune memory remains to be determined.

"In 2008, the team led by Inserm scientist James Di Santo (Innate Immunity Unit, Institut Pasteur/Inserm) described group 3 innate lymphoid cells (ILC3s) as a novel family of lymphocytes that were distinct from adaptive T and B lymphocytes. ILC3s play an essential role in the innate immune response, especially in the gut mucosa, by producing pro-inflammatory cytokines, such as interleukin (IL)-22. The cytokine release activates the production of antimicrobial peptides by epithelial cells, thereby reducing the bacterial load in order to maintain the integrity of the intestinal barrier.

"In this study, scientists from the Innate Immunity Unit (Institut Pasteur/Inserm) used an innovative protocol to expose the immune system to a time-restricted enterobacterial challenge based on Citrobacter rodentium (a mouse model of E. coli infection). They observed that ILC3s persist for several months in an activated state after exposure to C. rodentium. During a second infection, the "trained" ILC3s have a superior capacity to control infection through an enhanced proliferation and massive production of IL-22. "Our research demonstrates that intestinal ILC3s acquire a memory to strengthen gut mucosal defenses against repeated infections over time," explains Nicolas Serafini, first author of the study and an Inserm scientist in the Innate Immunity Unit (Institut Pasteur/Inserm)."

Comment: no surprise. All immune system cells develop a memorized library to fight again in the future, al automatic.