Nitric oxide (NO) is a pleiotropic free radical messenger molecule. There is a large body of evidence that the inducible form of the NO synthase enzyme (iNOS) that is responsible for high-output production of NO from l-arginine is up-regulated in various forms of mucosal inflammation. Consistent with this, multiple detection strategies have demonstrated that iNOS expression, enzymatic activity, and NO production are increased in human inflammatory bowel disease tissues. There is also evidence that the level of iNOS-derived NO correlates well with disease activity in ulcerative colitis, while for Crohn's disease, the results are more variable. A substantial number of animal studies have assessed the role of inducible NO production. While the majority of studies have shown improvement in experimental inflammatory bowel disease with iNOS inhibition, there are also a significant number of reports of exacerbation of disease with inhibitors. Similarly, studies using iNOS-deficient mice in colitis models have shown improvement, worsening, or no effect on disease. The authors suggest that additional studies to assess the role of the competing biochemical pathway, namely the conversion of l-arginine to polyamines via the actions of arginase and ornithine decarboxylase, may provide important new insights into understanding the regulation of mucosal inflammation and inflammatory bowel disease.

At time of publication, litigation between the manufacturer of VSL#3 and Dr. De Simone/ExeGi Pharma over intellectual property claims was ongoing.

Arginase is the endogenous inhibitor of inducible NO synthase (iNOS), because both enzymes use the same substrate, l-arginase (Arg). Importantly, arginase synthesizes ornithine, which is metabolized by the enzyme ornithine decarboxylase (ODC) to produce polyamines. We investigated the role of these enzymes in the Citrobacter rodentium model of colitis. Arginase I, iNOS, and ODC were induced in the colon during the infection, while arginase II was not up-regulated. l-Arg supplementation of wild-type mice or iNOS deletion significantly improved colitis, and l-Arg treatment of iNOS−/− mice led to an additive improvement. There was a significant induction of IFN-γ, IL-1, and TNF-α mRNA expression in colitis tissues that was markedly attenuated with l-Arg treatment or iNOS deletion. Treatment with the arginase inhibitor S-(2-boronoethyl)-l-cysteine worsened colitis in both wild-type and iNOS−/− mice. Polyamine levels were increased in colitis tissues, and were further increased by l-Arg. In addition, in vivo inhibition of ODC with α-difluoromethylornithine also exacerbated the colitis. Taken together, these data indicate that arginase is protective in C. rodentium colitis by enhancing the generation of polyamines in addition to competitive inhibition of iNOS. Modulation of the balance of iNOS and arginase, and of the arginase-ODC metabolic pathway may represent a new strategy for regulating intestinal inflammation.

INTRODUCTION: Telemedicine has shown promise in inflammatory bowel disease (IBD). The objective of this study was to compare disease activity and quality of life (QoL) in a 1-year randomized trial of IBD patients receiving telemedicine vs. standard care. METHODS: Patients with worsening symptoms in the prior 2 years were eligible for randomization to telemedicine (monitoring via texts EOW or weekly) or standard care. The primary outcomes were the differences in change in disease activity and QoL between the groups; change in healthcare utilization among groups was a secondary aim. RESULTS: 348 participants were enrolled (117 control group, 115 TELE-IBD EOW, and 116 TELE-IBD weekly). 259 (74.4%) completed the study. Age was 38.9 ± 12.3 years, 56.6% were women, 91.9% were Caucasian, 67.9% had Crohn’s disease (CD) and 42.5% had active disease at baseline. In CD, all groups experienced a decrease in disease activity (control −5.2 ± 5.0 to 3.7 ± 3.6, TELE-IBD EOW 4.7 ± 4.1 to 4.2 ± 3.9, and TELE-IBD weekly 4.2 ± 4.2 to 3.2 ± 3.4, p < 0.0001 for each of the groups) In UC, only controls had a significant decrease in disease activity (control 2.9 ± 3.1 to 1.4 ± 1.4, p = 0.01, TELE-IBD EOW 2.7 ± 3.1 to 1.7 ± 1.9, p = 0.35, and TELE-IBD Weekly 2.5 ± 2.5 to 2.0 ± 1.8, p = 0.31). QoL increased in all groups; the increase was significant only in TELE-IBD EOW (control 168.1 ± 34.0 to 179.3 ± 28.2, p = 0.06, TELE-IBD EOW 172.3 ± 33.1 to 181.5 ± 28.2, p = 0.03, and TELE-IBD Weekly 172.3 ± 34.5 to 179.2 ± 32.8, p = 0.10). Unadjusted and adjusted changes in disease activity and QoL were not significantly different among groups. Healthcare utilization increased in all groups. TELE-IBD weekly were less likely to have IBD-related hospitalizations and more likely to have non-invasive diagnostic tests and electronic encounters compared to controls; both TELE-IBD groups had decreased non-IBD related hospitalizations and increased telephone calls compared to controls. DISCUSSION: Disease activity and QoL, although improved in all participants, were not improved further through use of the TELE-IBD system. TELE-IBD participants experienced a decrease in hospitalizations with an associated increase in non-invasive diagnostic tests, telephone calls and electronic encounters. Research is needed to determine if TELE-IBD can be improved through patient engagement and whether it can decrease healthcare utilization by replacing standard care.

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