Keeping bugs in check: The mucus layer as a critical component in maintaining intestinal homeostasis.
In the mammalian gastrointestinal tract the close vicinity of abundant immune effector cells and trillions of commensal microbes requires sophisticated barrier and regulatory mechanisms to maintain vital host-microbial interactions and tissue homeostasis. During co-evolution of the host and its intestinal microbiota a protective multilayered barrier system was established to segregate the luminal microbes from the intestinal mucosa with its potent immune effector cells, limit bacterial translocation into host tissues to prevent tissue damage, while ensuring the vital functions of the intestinal mucosa and the luminal gut microbiota. In the present review we will focus on the different layers of protection in the intestinal tract that allow the successful mutualism between the microbiota and the potent effector cells of the intestinal innate and adaptive immune system. In particular, we will review some of the recent findings on the vital functions of the mucus layer and its site-specific adaptations to the changing quantities and complexities of the microbiota along the (gastro-) intestinal tract. Understanding the regulatory pathways that control the establishment of the mucus layer, but also its degradation during intestinal inflammation may be critical for designing novel strategies aimed at maintaining local tissue homeostasis and supporting remission from relapsing intestinal inflammation in patients with inflammatory bowel diseases.
Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
Martin
M
Faderl
Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
Mario
M
Noti
Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
Nadia
N
Corazza
Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
Christoph
C
Mueller
D018407:Bacterial Physiological Phenomena; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology / Q000502:physiology*; D007422:Intestines / Q000382:microbiology / Q000502:physiology*; D009093:Mucus / Q000378:metabolism
disease models; genetic models