Modulation of Intestinal Epithelial Permeability via Protease-Activated Receptor-2-Induced Autophagy

Abstract

Protease-activated receptor 2 (PAR2) alleviates intestinal inflammation by upregulating autophagy. PAR2 also modulates tight junctions through β‑arrestin signaling. Therefore, we investigated the effect of PAR2-induced autophagy on intestinal epithelial tight junctions and permeability. RT-PCR, Western blot analysis, and immunoprecipitation were performed to investigate the underlying molecular mechanisms by which PAR2 regulates autophagy and intestinal epithelial tight junctions. Inhibition of PAR2 by GB83, a PAR2 antagonist, decreased the expression of autophagy-related and tight-junction-related factors in Caco-2 cells. Moreover, inhibition of PAR2 decreased intestinal transepithelial electrical resistance. When PAR2 was activated, intestinal permeability was maintained, but when autophagy was suppressed by chloroquine, intestinal permeability was significantly increased. In addition, the prolongation of ERK1/2 phosphorylation by PAR2–ERK1/2–β-arrestin assembly was reduced under autophagy inhibition conditions. Therefore, PAR2 induces autophagy to regulate intestinal epithelial permeability, suggesting that it is related to the β-arrestin–ERK1/2 pathway. In conclusion, regulating intestinal epithelial permeability through PAR2-induced autophagy can help maintain mucosal barrier integrity. Therefore, these findings suggest that the regulation of PAR2 can be a suitable strategy to treat intestinal diseases caused by permeability dysfunction.

Morphological and biochemical characteristics associated with autophagy in gastrointestinal diseases

“…Recent research found that autophagy promotes membrane localization of occluding protein, a principal TJ component involved in TJ barrier enhancement, which could protect against inflammation-induced barrier loss[ 12 ]. Furthermore, Kim et al [ 13 ] discovered that protease-activated receptor 2 regulates autophagy and intestinal epithelial TJs, thus reducing intestinal epithelial permeability. Additionally, another study discovered that rapamycin (autophagy inducer) dramatically improved intestinal damage in benzo[a]pyrene induced intestinal epithelial TJ disruption[ 14 ].…”

Octreotide attenuates intestinal barrier damage by maintaining basal autophagy in Caco2 cells

“…OCT maintains basal levels of autophagy in Caco2 cells through SSTR2. Previous studies revealed that autophagy has an important role in maintaining the intestinal epithelial barrier by regulating TJ proteins (34,35). To determine the protective mechanisms of OCT in intestinal TJ barrier function, the formation of autophagosomes and autophagolysosomes in Caco2 cells was observed using TEM.…”

Zonulin as a Potential Therapeutic Target in Microbiota-Gut-Brain Axis Disorders: Encouraging Results and Emerging Questions

“…Recently, it has been shown that, in contrast to larazotide acetate, peptidic antagonists of PAR 2 , including FSLLRY-NH 2 or SLIGRL-NH 2 , decreased the expression of ZO-1 and claudin-1 and destroyed the barrier function of nasal epithelial cells [ 121 ]. Similarly, a small molecule antagonist, GB83, exerted harmful effects on colon epithelial cells by decreasing the expression of autophagy- and TJ-related factors and increased permeability [ 234 ]. In contrast, inhibition of the PAR 2 pathway by GB88 in lung epithelial cells [ 235 ] or using I-191 in arterial endothelial cells [ 236 ] moderated actin rearrangement and TJ disruption and reduced the permeability of the cellular monolayers.…”