Inflammatory bowel disease (IBD) is a chronic intestinal
inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory
cytokines. Recent studies have shown that the
cannabinoid system may play a critical role in mediating protection against intestinal
inflammation. However, the effect of
cannabinoid receptor induction after chronic
colitis progression has not been investigated. Here, we investigate the effect of
cannabinoid receptor-2 (CB2) agonist,
JWH-133, after chronic
colitis in IL-10(-/-) mice.
JWH-133 effectively attenuated the overall clinical score, and reversed
colitis-associated pathogenesis and decrease in
body weight in IL-10(-/-) mice. After
JWH-133 treatment, the percentage of CD4(+) T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic
colitis.
JWH-133 was also effective in ameliorating
dextran sodium sulfate (DSS)-induced
colitis. In this model,
JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during
colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (
AM630), a
CB2 receptor antagonist, reversed the
colitis protection provided by
JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following
JWH-133 treatment both in-vivo and in-vitro. These findings suggest that
JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic
colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of
inflammation in the LP. These results support the idea that the
CB2 receptor agonists may serve as a therapeutic modality against IBD.