The effects of cannabinoids on intestinal permeability in a model of inflammation

Abdussalam Alhamoruni1, Karen Wright1,2, Mike Larvin1, Saoirse O’Sullivan1. 1University of Nottingham, Nottingham, United Kingdom, 2Lancaster University, Lancaster, United Kingdom.

Pro-inflammatory cytokines cause damage in the gastrointestinal epithelial barrier, causing increased translocation of luminal antigens. The ability to modulate the intestinal permeability during the inflammatory process could be important in devising future therapeutic strategies. Cannabinoids have previously been shown to also exert anti-inflammatory actions in the gut, therefore the aim of the present study was to examine whether cannabinoids modulate intestinal permeability during inflammation

Caco-2 cells (Colon Adenocarcinoma cell line) were grown until fully confluent on inserts in 12-well plates. Cells were treated with 10ng/ml of INF-γ for 8 h and 10ng/ml TNF-α for a further 16 hours. Transepithelial electrical resistance (TEER) measurements were made as a measure of permeability. The effects of cannabinoids on TEER during inflammation were assessed.

Potential target sites of action were investigated using the following (all 1 μM); AM251 (CB1 receptor antagonist), AM630 (CB2 receptor antagonist), capsazepine (TRPV1 antagonist), GW9662 (PPARγ antagonist), GW6471 (PPARα antagonist), and O-1918 (proposed endothelial cannabinoid receptor antagonist).

Cytokine treatment caused a fall in TEER (indicating an increase in cell permeability) of approx 20% after 24h. Phytocannabinoids enhanced the recovery of cytokines-induced reduced TEER, although statistically significantly differences were only observed in the micromolar ranges for both THC and CBD (P<0.05). By contrast, endocannabinoids caused a further fall in TEER during inflammation in a concentration-dependent manner, although an irreversible drop in TEER was observed at higher concentration (30μM) (55-60%) of the initial TEER. CB1 receptor antagonism was significantly preventing the action of both phyto-and endocannabinoids (P<0.05). Both phytocannabinoids significantly prevent the drop of TEER caused by cytokines when applied together in all time courses of the experiment (P<0.05).

These findings suggest that endocannabinoids may play a role in modulating intestinal permeability during the inflammatory process and that phytocannabinoids may have therapeutic potential in the treatment of leaky gut disorders.

Fish SM et al (1999). Synergistic effects of interferon gamma and tumour necrosis factor alpha on T84 cell function. Gut 45: 191-8.
D’Argenio G et al (2007). Overactivity of the intestinal endocannabinoid system in celiac disease and in methotrexate-treated rats. J Mol Med 85: 523-30.