L-Glutamine Enhances Tight Junction Integrity by Activating CaMK Kinase 2-AMP-Activated Protein Kinase Signaling in Intestinal Porcine Epithelial Cells.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory study using porcine cell culture (bench research).
PubMed 26865645 · doi:10.3945/jn.115.224857
What was done
Jejunal enterocytes isolated from a newborn pig were cultured with 0 to 2.0 mmol/L L-glutamine (Gln) across multiple time points. Investigators evaluated cell proliferation, monolayer transepithelial electrical resistance (TEER), paracellular permeability, tight junction protein abundance and membrane localization (occludin, claudins, JAM-A, ZO-1/2/3), and phosphorylated AMPK. Calcium depletion and a CaMKK2 inhibitor were used to evaluate the role of the CaMKK2-AMPK pathway.
What was found
Compared with 0 mmol/L Gln, treatment with 2.0 mmol/L Gln significantly (P < 0.05) enhanced cell growth by 31.9% at 48 h and 11.1% at 60 h. At 60 h, 2.0 mmol/L Gln increased TEER by 32.2% and decreased tight junction permeability by 20.3% to 40.0% at 36-60 h (P < 0.05). Treatment with 2.0 mmol/L Gln increased the abundance of occludin, claudin-4, JAM-A, ZO-1, ZO-2, and ZO-3 by 1.8- to 6-fold (P < 0.05), whereas 0.5 mmol/L Gln increased occludin, claudin-3, claudin-4, JAM-A, and ZO-1 by 20.2% to 70.5% (P < 0.05). In addition, 2.0 mmol/L Gln increased plasma membrane distribution of claudin-1, claudin-4, and ZO-1. Calcium depletion or CaMKK2 inhibition eliminated the protective effects of Gln.
Why it matters
This study defines a specific intracellular pathway (CaMKK2-AMPK) through which L-glutamine promotes tight junction protein abundance and assembly, clarifying the cellular mechanism behind glutamine-mediated gut barrier support.
Limits
The study was performed entirely in vitro using jejunal enterocytes derived from a single newborn pig. The findings lack in vivo physiological verification in intact animals or human subjects.
Cited by
- supports Glutamine supports intestinal epithelial integrity by helping enterocytes link together.