Early downregulation of P‐glycoprotein facilitates bacterial attachment to intestinal epithelial cells and thereby triggers barrier dysfunction in a rodent model of total parenteral nutrition

Abstract

Intestinal barrier dysfunction is a major complication of total parenteral nutrition (TPN). Our preliminary study revealed that intestinal P‐glycoprotein (P‐gp) was significantly downregulated under TPN treatment followed by disruption of barrier function, and thus the significance of early downregulation of P‐gp needs to be addressed. Herein, we report a pivotal role of P‐gp in the development of intestinal barrier dysfunction under TPN. Functional suppression of P‐gp may facilitate bacterial attachment to intestinal epithelial cells (IECs) and thereby induce degradation of tight junctions to trigger barrier dysfunction. By using a rat model of TPN, we found early downregulation of P‐gp function in ileum after 3‐day TPN, followed by disruption of barrier function after 7‐day TPN. By using Escherichia coli (E. coli) k88 and DH5α as type strains, we found significantly increased bacterial attachment to IECs in TPN group compared to sham. By using Caco‐2 cells as an IEC model in vitro, we found that functional suppression of P‐gp remarkably facilitated bacterial attachment to Caco‐2 cells, leading to subsequent disruption of intestinal barrier function. Of note, Occludin was significantly downregulated by bacterial attachment when P‐gp was functionally suppressed. Mechanistically, changes on Occludin were attributed to enhanced protein degradation instead of suppressed protein translation. Despite the half‐life of Occludin protein being unchanged by DH5α treatment alone, it was decreased by about 40% when P‐gp was simultaneously suppressed. Taken together, our findings revealed that early downregulation of intestinal P‐gp under TPN may be a potential therapeutic target to prevent the development of barrier dysfunction.

Small noncoding vault RNA2‐1 disrupts gut epithelial barrier function via interaction with HuR

“…To gain a deeper molecular understanding, we focused specifically on vtRNA2‐1 , as this vtRNA changed significantly in the mucosal tissues of UC patients, there is earlier evidence of its possible influence on the epithelial barrier (Lee et al , 2011, 2014; Kong et al , 2015; Fort et al , 2020), and vtRNA2‐1 was a predicted ligand for RBPs including HuR. Two sets of studies were carried out in Caco‐2 cells, a widely accepted cell culture model for intestinal epithelial barrier studies (Guo et al , 2005; Zhang et al , 2020). First, we examined the effect of increasing the levels of vtRNA2‐1 on the expression of TJ and AJ proteins.…”

“…Total RNA was isolated by using the RNeasy mini kit (Qiagen, Valencia, CA) and used in reverse transcription (RT) and PCR amplification reactions as described (Zhang et al , 2020). Q‐PCR analysis was performed using Step‐one‐plus Systems with specific primers, probes, and software (Applied Biosystems, Foster City, CA).…”

Multi-Omics Unravels Metabolic Alterations in the Ileal Mucosa of Neonatal Piglets Receiving Total Parenteral Nutrition

“…In the past 50 years, PN has become a standard-of-care, lifesaving clinical support therapy for premature infants as well as patients who cannot tolerate EN, and particularly TPN has been the only approach of nutritional support for those patients with severe intestinal failure. However, despite the significant clinical benefit of PN, evidence is also accumulating that exclusive PN or TPN may lead to increasing associated risks of exacerbating intestinal injury, due in part to reduced gastrointestinal blood flow and the disruption of intestinal homeostasis, including villus atrophy [15,16], decline in mucosal immunity [17,18] and disassembly of tight junctions leading to hyperpermeability [19,20]. By using rodents as a laboratory TPN model, a variety of aberrantly activated signaling pathways have been identified, including PI3K/pAkt [21], TLR4/EGF [22] and NF-κB/MLCK [23].…”

Impaired FXR‐CPT1a signaling contributes to parenteral nutrition‐induced villus atrophy in short‐bowel syndrome

“…However, FAO seems to be deactivated in those SBS patients with intestinal failure compared to their counterparts with intestinal adaption. Given a growing body of evidence linking PN‐induced villus atrophy to intestinal failure, 34–36 we then asked by what kind of mechanism intestinal FAO was functionally inhibited in these SBS patients and PN piglets.…”