fMLP induces Hsp27 expression, attenuates NF-κB activation, and confers intestinal epithelial cell protection

Abstract

Sustained expression of cytoprotective intestinal epithelial heat shock proteins (Hsps), particularly Hsp27, depends on stimuli derived from bacterial flora. In this study, we examined the role of the bacterial chemotactic peptide fMLP in stimulating colonic epithelial Hsp expression at concentrations encountered in a physiological milieu. Treatment of the polarized human intestinal epithelial cell line Caco2bbe with physiological concentrations of fMLP (10-100 nM) induced expression of Hsp27, but not Hsp72, in a time- and concentration-dependent manner. Induction of Hsp27 by fMLP was specific since the fMLP analogs MRP and MLP were not effective. Hsp27 induction by fMLP was blocked by the fMLP-receptor antagonist BOC-FLFLF and was blocked when the dipeptide transporter PepT1, an entry pathway for fMLP, was silenced. fMLP activated both the p38 and ERK1/2 MAP kinase pathways in Caco2bbe cells, but not the SAPK/JNK pathway. The p38 inhibitor SB203580, but not the MEK-1 inhibitor PD98059, blocked Hsp27 induction by fMLP. fMLP treatment inhibited actin depolymerization and decreased transepithelial resistance caused by the oxidant monochloramine, and this inhibition was reversed by silencing Hsp27 expression. fMLP pretreatment also inhibited activation of proinflammatory transcription factor NF-kappaB by TNF-alpha in Caco2bbe cells, reducing induction of NF-kappaB target genes by TNF-alpha both in human intestinal biopsies and Caco2bbe cells. In conclusion, fMLP may contribute to the maintenance of intestinal homeostasis by mediating physiological expression of Hsp27, enhancing cellular protection, and negatively regulating the inflammatory response.

MicroRNA-193a-3p Reduces Intestinal Inflammation in Response to Microbiota via Down-regulation of Colonic PepT1

“…Moreover, we demonstrated that restoration of miR-193a-3p reduced PepT1 expression and transport activity, which subsequently decreased the activation of the NF-B signaling pathway and led to the suppression of fMLF triggered inflammation in Caco2 cells. Several studies have indicated that fMLF could stimulate a time-dependent increase of IB-␣ phosphorylation in the intestinal epithelial cells, and the NF-B pathway may play a role in the synergistic activation of intestinal immune response induced by fMLF (36,37). Activation of the NF-B pathway could be induced by IB kinase and ubiquitination of the NF-B essential modulator, which subsequently activates NOD2 by muramyl-dipeptide, which derives from peptidoglycan of bacteria (38).…”

Contribution of IL-6 to the Hsp72, Hsp25, and αβ-crystallin responses to inflammation and exercise training in mouse skeletal and cardiac muscle

“…Hsp25 and Hsp72 have been shown to reduce NF-B activation (4,22,55), which is central to the expression of several proinflammatory cytokines (23). While exercise can acutely activate NF-B (17,21), chronic activation of this pathway has been associated with muscle weakness (3) and contractile protein loss (28,30).…”

Gut epithelial inducible heat-shock proteins and their modulation by diet and the microbiota

“…Inducible HSP-dependent inhibition of the NFjB pathway has also been documented in GECs. 27,28 The underlying mechanisms could involve activation of IjBa gene expression and inhibition of phosphorylation and degradation of IjBa protein. Conversely, HSP27 is implicated in NF-jB activation by reactive oxygen species.…”