Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2011 Mar;27(2):125-31.
doi: 10.1097/MOG.0b013e3283438dea.

Innate immunity in the small intestine

Rebeca Santaolalla  1 , Masayuki Fukata, Maria T Abreu
Affiliations
Review

Innate immunity in the small intestine

Rebeca Santaolalla et al. Curr Opin Gastroenterol. 2011 Mar.

Abstract

Purpose of review: In this article, we provide an update of the latest findings related to the innate immunity in the small intestine. In particular, we will focus on innate immune receptors and antimicrobial strategies that keep luminal bacteria and viral pathogens under control to avoid mucosal damage. These strategies include IgA secretion and antimicrobial peptides produced by Paneth cells, and downregulation or anergy of the innate immune receptors themselves.

Recent findings: Pattern-recognition receptors are the main target in the study of innate immunity in the intestinal mucosa due to their involvement in the regulation of host-commensal interactions. It has been shown that TLR5-deficient mice develop metabolic syndrome and have altered intestinal microbiota. On the contrary, NOD2 has been associated with the activation of autophagy and the inhibition of TLR4. Moreover, NOD2 has been described to be essential to keep a feedback loop in the host-commensal homeostasis, through the kinase Rip-2.

Summary: Innate immunity in the small intestine is mainly characterized by IgA secretion and Paneth cell antimicrobial function. In both cases pattern-recognition receptors, Toll-like receptors and nucleotide-binding and oligomerization domain-like receptors, are involved. A better understanding of the innate immunity in the small intestine would provide valuable information to develop vaccines against pathogens.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Innate immunity in the small intestine
The intestinal bacterial load is controlled by antimicrobial peptides and IgA secreted into the intestinal crypt. Paneth cells, situated in the base of the crypt, are the main producers of antimicrobial agents. IgA is produced by plasma cells located in the lamina propria, and is secreted to the lumen via transcellular transport. Innate immune receptors, TLRs and NLRs, are expressed in the intestinal epithelium and are the sensors for pathogen-associated molecular patterns. In the lamina propria, dendritic cells and macrophages function as antigen presenting cells.
See this image and copyright information in PMC

References

    1. Rescigno M. CCR6(+) dendritic cells: the gut tactical-response unit. Immunity. 2006;24:508–10. - PubMed
    1. Niess JH, Brand S, Gu X, Landsman L, Jung S, McCormick BA, Vyas JM, Boes M, Ploegh HL, Fox JG, Littman DR, Reinecker HC. CX3CR1-mediated dendritic cell access to the intestinal lumen and bacterial clearance. Science. 2005;307:254–8. - PubMed
    1. Fukata M, Vamadevan AS, Abreu MT. Toll-like receptors (TLRs) and Nod-like receptors (NLRs) in inflammatory disorders. Semin Immunol. 2009;21:242–53. - PubMed
    1. Fukata M, Chen A, Klepper A, Krishnareddy S, Vamadevan AS, Thomas LS, Xu R, Inoue H, Arditi M, Dannenberg AJ, Abreu MT. Cox-2 is regulated by Toll-like receptor-4 (TLR4) signaling: Role in proliferation and apoptosis in the intestine. Gastroenterology. 2006;131:862–77. - PMC - PubMed
    1. Fukata M, Hernandez Y, Conduah D, Cohen J, Chen A, Breglio K, Goo T, Hsu D, Xu R, Abreu MT. Innate immune signaling by Toll-like receptor-4 (TLR4) shapes the inflammatory microenvironment in colitis-associated tumors. Inflamm Bowel Dis. 2009;15:997–1006. - PMC - PubMed