β(2 → 1)-β(2 → 6) and β(2 → 1) fructans protect from impairment of intestinal tight junction's gene expression and attenuate human dendritic cell responses in a fructan-dependent fashion

ss(2 -> 1)-ss(2 -> 6) branched graminan-type fructans (GTFs) and ss(2 -> 1) linear fructans (ITFs) possess immunomodulatory properties and protect human intestinal barrier function, however the mechanisms underlying these effects are not well studied. Herein, GTFs and ITFs effects with different degree of polymerization (DP) values on tight junctions (TJs) genes CLDN-1, -2 and -3, CDH1, OCLN and TJP1 were studied in Caco-2 gut epithelial cells, under homeostatic and inflammatory conditions. Also, cytokine production in dendritic cells (DCs) was studied. Higher DP fructans decreased the expression of the pore forming CLDN-2. Higher DP GTFs enhanced CLDN-3, OCLN, and TJP-1. Fructans prevented mRNA dysregulation of CLDN-1, -2 and -3 induced by the barrier disruptors A23187 and deoxynivalenol in a fructan-type dependent fashion. The production of proinflammatory cytokines MCP-1/CCL2, MIP-1a/CCL3 and TNF alpha by DCs was also attenuated in a fructan-type dependent manner and was strongly attenuated by DCs cultured with medium of Caco-2 cells which were preexposed to fructans. Our data show that specific fructans have TJs and DCs modulating effects and contribute to gut homeostasis. This might serve to design effective dietary means to prevent intestinal inflammation.