TGF‐β2 Induces Maturation of Immature Human Intestinal Epithelial Cells and Inhibits Inflammatory Cytokine Responses Induced Via the NF‐κB Pathway

Objectives: Breast milk transforming growth factor (TGF)‐β2 is associated with healthy immune maturation and reduced risk of immune‐mediated disease in infants. We sought to investigate whether conditioning with TGF‐β2 may result in a more mature immune responder phenotype in immature human intestinal epithelial cells (IECs). Methods: Primary human fetal IECs (hFIECs) and the human fetal small intestinal epithelial cell line (H4 cells) were conditioned with breast milk levels of TGF‐β2, and an inflammatory response was subsequently induced. Inflammatory cytokine secretion and mRNA expression were measured by enzyme‐linked immunosorbent assay and quantitative real‐time polymerase chain reaction, respectively. Alterations in activation of inflammatory signaling pathways were detected from IECs by immunoblotting and immunofluorescence. The effects of TGF‐β2 conditioning on gene expression patterns in hFIECs were assessed by cDNA microarray analysis and quantitative PCR. Results: Conditioning with TGF‐β2 significantly attenuated subsequent interleukin (IL)‐1β‐, TNF‐α‐, and poly I:C‐induced IL‐8 and IL‐6 responses in immature human IECs. Conditioning with TGF‐β2 inhibited IL‐1β‐induced IκB‐α degradation and NF‐κB p65 nuclear translocation, which may partially result from TGF‐β2‐induced changes in the expression of genes in the NF‐κB signaling pathway detected by cDNA microarray and qPCR. Conclusions: Conditioning with TGF‐β2 attenuates the subsequent inflammatory cytokine response in immature human IECs by inhibiting signaling in the NF‐κB pathway. The immunomodulatory potential of breast milk may in part be mediated by TGF‐β2, which may provide a novel means of supporting intestinal immune maturation in neonates.