Larazotide Acetate Protects the Intestinal Mucosal Barrier from Anoxia/Reoxygenation Injury via Various Cellular Mechanisms.
This study investigated the cellular mechanisms by which larazotide acetate (LA), a synthetic octapeptide in clinical development for celiac disease, protects the intestinal epithelial barrier. Researchers pretreated two intestinal epithelial cell lines — C2BBe1 (human) and IPEC-J2 (a "leaky" porcine line) — with LA before exposing them to anoxia/reoxygenation (A/R) injury, a model of ischemia-reperfusion stress. LA pretreatment significantly increased transepithelial electrical resistance (TEER), a measure of barrier integrity, and preserved the normal localization of tight junction (TJ) proteins. RNA sequencing identified enriched gene sets related to barrier regulation, small GTPase signaling, protein phosphorylation, cell proliferation, and migration. Consistent with transcriptomic findings, LA markedly reduced phosphorylation of myosin light chain-2 (MLC-2), suggesting modulation of the ROCK signaling pathway, which is known to influence TJ dynamics. LA also enhanced epithelial cell proliferation. Limitations include exclusive reliance on in vitro cell culture models with no animal or human data, and the use of a single, fixed LA concentration. The authors conclude that LA stabilizes tight junctions, reduces MLC-2 phosphorylation, and promotes epithelial renewal, supporting its broader potential in gastrointestinal conditions involving mucosal barrier disruption.
Why this grade: All experiments were conducted exclusively in two cell line models (C2BBe1 and IPEC-J2) with no animal or human subjects, limiting translation of findings to clinical efficacy.
Background/Objective : Larazotide acetate (LA) is a synthetic octapeptide under development as a therapeutic candidate for celiac disease, acting to reduce intestinal permeability and regulate tight junctions (TJs). Although several studies have shown barrier-protective effects, the cellular mechanisms underlying LA's actions in the intestinal epithelium remain unclear. This study aimed to elucidate the mechanistic roles of LA in maintaining intestinal epithelial integrity during cellular injury. Methods: C2BBe1 and leaky IPEC-J2 cell monolayers were pretreated with 10 mM LA and subjected to anoxia/reoxygenation (A/R) injury. Transepithelial electrical resistance (TEER), TJ protein localization, and phosphorylation of myosin light chain-2 (MLC-2) were analyzed. In addition, RNA sequencing was conducted to identify differentially expressed genes and signaling pathways affected by LA treatment. Results: LA pretreatment significantly increased TEER and preserved TJ protein organization during A/R injury. Transcriptomic analysis revealed enrichment of genes related to barrier regulation, small GTPase signaling, protein phosphorylation, proliferation, and migration. LA pretreatment markedly reduced MLC-2 phosphorylation, likely through modulation of the ROCK pathway, consistent with RNA-seq findings. Moreover, LA enhanced cellular proliferation, validating transcriptomic predictions. Conclusions: LA exerts a protective effect on intestinal epithelial integrity by stabilizing tight junctions, reducing MLC-2 phosphorylation, and promoting epithelial proliferation. These findings highlight a novel mechanism for LA and support its therapeutic potential in treating gastrointestinal disorders associated with "leaky gut" and mucosal injury.
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