Helicobacter pylori Disrupts Epithelial Barrier Function in a Process Inhibited by Protein Kinase C Activators

Abstract

Helicobacter pylori colonizes the gastric mucosa, and the infection is related to the development of diverse gastric pathologies, possibly by directly or indirectly affecting epithelial-cell function. We analyzed the influence of the bacteria on transepithelial electrical resistance (TER) on a model tight epithelium, T84, grown to confluence in permeable filters. H. pylori sonicates produced a dramatic decrease in TER after 1 to 2 h of exposure, while sonicates from other bacteria did not induce a significant reduction of TER. The effect induced by sonicates was mimicked by a water-soluble fraction from the bacterial surface, was not reproducible with isolated lipopolysaccharide, and was concomitant with a significant increase in the paracellular permeability of the marker molecule [14C]mannitol. Furthermore, H. pylori sonicates also provoked a significant increase in permeability to [14C]mannitol across rat gastric mucosa in vitro. The sonicate-induced decrease in TER in T84 monolayers was inhibited by the protein kinase C (PKC) activator phorbol myristate acetate. As PKC is directly involved in tight junction regulation, we suggest that H. pylori may induce intracellular signalling events counteracting PKC effects. Following long-term H. pylori stimulation, epithelial monolayers regained baseline resistance values slowly after 24 h. The resistance recovery process was inhibited by cycloheximide, indicating its dependency upon protein synthesis. No association between resistance variation and E-cadherin protein levels was observed. These results indicate that H. pylori alters in vitro the barrier properties of the epithelium, probably by generating cell signalling events counteracting the normal function of PKC. This increased permeability may provide a potential mechanism by whichH. pylori antigens can reach the gastric lamina propria, thereby activating the mucosal immune system.

Changes of tight junction and interleukin‐8 expression using a human gastroid monolayer model of Helicobacter pylori infection

“…Although prior studies lasted up to 48 hours, 10,14,16,30,35,[37][38][39] our studies confirmed that the apical junctional complex remained relatively preserved and, as noted, the TEER recovered after temporally dropping which is in agreement with vivo studies. 40 These results suggest the gastroid monolayer model responds similarly to normal gastric epithelial cells in vivo.…”

Omeprazole increases permeability across isolated rat gastric mucosa pre-treated with an acid secretagogue

“…The observation that omeprazole enhanced macromolecular permeability in histamine-treated stomachs is interesting in terms of drug delivery across a gastric mucosa which harbours H. pylori. There is abundant evidence that H. pylori infection increases both transcellular (Matysiak-Budnik et al 2001) and also paracellular movement of macromolecules (Terres et al 1998). Thus, bacterial infection by itself could facilitate increased transepithelial delivery of antibiotics.…”

TLR4/PKC‐mediated tight junction modulation: A clinical marker of chemotherapy‐induced gut toxicity?

“…93 Additionally, application of the PKC activator, phorbol myristate acetate, ameliorates increased intestinal permeability induced by exposure to H. pylori, reinforcing a role for PKC in bacteria-mediated mucosal barrier dysfunction. 83 Given that PKC signaling has been implicated with not only proinflammatory cytokines and pathogenic bacteria, but numerous established mediators of CIGT (MMPs, TLRs), it is reasonable to propose PKC signaling as a candidate mechanisms for chemotherapy-induced tight junction disruption and mucosal barrier dysfunction.…”