TNF-? augments RANKL-dependent intestinal M cell differentiation in enteroid cultures.

ABSTRACT: Microfold (M) cells are phagocytic intestinal epithelial cells in the follicle-associated epithelium of Peyer's patches that transport particulate antigens from the gut lumen into the subepithelial dome. Differentiation of M cells from epithelial stem cells in intestinal crypts requires the cytokine receptor activator of NF-?B ligand (RANKL) and the transcription factor Spi-B. We used three-dimensional enteroid cultures established with small intestinal crypts from mice as a model system to investigate signaling pathways involved in M cell differentiation and the influence of other cytokines on RANKL-induced M cell differentiation. Addition of RANKL to enteroids induced expression of multiple M cell-associated genes, including Spib, Ccl9 [chemokine (C-C motif) ligand 9], Tnfaip2 (TNF-?-induced protein 2), Anxa5 (annexin A5), and Marcksl1 (myristoylated alanine-rich protein kinase C substrate) in 1 day. The mature M cell marker glycoprotein 2 (Gp2) was strongly induced by 3 days and expressed by 11% of cells in enteroids. The noncanonical NF-?B pathway was required for RANKL-induced M cell differentiation in enteroids, as addition of RANKL to enteroids from mice with a null mutation in the mitogen-activated protein kinase kinase kinase 14 (Map3k14) gene encoding NF-?B-inducing kinase failed to induce M cell-associated genes. While the cytokine TNF-? alone had little, if any, effect on expression of M cell-associated genes, addition of TNF-? to RANKL consistently resulted in three- to sixfold higher levels of multiple M cell-associated genes than RANKL alone. One contributing mechanism is the rapid induction by TNF-? of Relb and Nfkb2 (NF-?B subunit 2), genes encoding the two subunits of the noncanonical NF-?B heterodimer. We conclude that endogenous activators of canonical NF-?B signaling present in the gut-associated lymphoid tissue microenvironment, including TNF-?, can play a supportive role in the RANKL-dependent differentiation of M cells in the follicle-associated epithelium.

SUBMITTER: Wood MB 

PROVIDER: S-EPMC5129760 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature