IL10 and colitis: In order to examine the impact of the mucosal opioid tone on the development of colitis, IL-10-/- mice fed with standard chow diet containing piroxicam were intraperitoneally injected over the 10 days of treatment with either PBS or naloxone-methiodide (NLX-methiodide), a general antagonist of opioid receptors unable to cross the blood-brain barrier, that has no pro-inflammatory effect per se in normal mice (Supplementary Figure S1).