New 1,2,3,4-tetrahydropyrrolo[3,4-b]indole derivatives as selective CB2 receptor agonists.

The preparation and evaluation of a novel class of CB2 agonists based on a 1,2,3,4-tetrahydropyrrolo[3,4-b]indole moiety are reported. They showed binding affinities up to 4.2 nM toward CB2 with sub-nanomolar EC(50) values. They also showed moderate to good (>350-fold) selectivity over the CB1 receptor.

PAR-2 activation in intestinal epithelial cells potentiates interleukin-1beta-induced chemokine secretion via MAP kinase signaling pathways.

Intestinal epithelial cells can be induced to secrete the chemokine interleukin (IL)-8 during inflammation. The PAR-2 receptor is believed to play a proinflammatory role and is expressed in gut epithelial cells. The aim was to investigate PAR-2 signaling in Caco-2 intestinal epithelial cells, with respect to chemokine secretion. Activation of PAR-2 by high concentrations of the synthetic activating peptide (SLIGKV) did not induce secretion of IL-8, in contrast to stimulation with IL-1beta. However, upon simultaneous treatment with activating peptide and IL-1beta, a potentiating effect of PAR-2 stimulation was seen, resulting in a fivefold increase of IL-8. Available data suggest that NF-kappaB activation is required for IL-8 gene expression. Unlike IL-1beta, PAR-2 stimulation did not activate NF-kappaB, which may explain the lack of IL-8 expression. However, PAR-2 stimulation led to rapid phosphorylation of two MAP kinases, p38 MAPK and ERK1/2. ERK1/2 is known to activate the transcription factor AP-1, also involved in upregulation of IL-8 gene transcription. Inhibition of p38 MAPK led to decreased IL-8 following stimulation with IL-1beta and/or activating peptide. These results suggest that maximal IL-8 expression requires coordination of several signaling pathways. Thus, identifying antagonists to the PAR-2 receptor may be beneficial by inhibiting potentiation of a proinflammatory response, through inhibition of p38 and ERK MAP kinases.

Design and synthesis of dihydrofolate reductase inhibitors encompassing a bridging ester group. Evaluation in a mouse colitis model.

Crohn's disease is a chronic inflammatory bowel disease characterized by inflammation of both the small and large intestines. Methotrexate (MTX), a classical dihydrofolate reductase (DHFR) inhibitor, has been used as a therapeutic agent in the treatment of patients with Crohn's disease in recent years. We sought to develop antifolates similar in structure to MTX that would be effective in reducing inflammation in a mouse disease model of colitis. Four classical DHFR inhibitors encompassing ester bridges in the central parts of the molecules were synthesized. These antifolates were efficient inhibitors of the DHFR enzyme derived from rat. They were also tested in vitro for their ability to inhibit induced proliferation of lymphocytes from mouse spleen. Inhibition of cell proliferation was achieved only in the micromolar range, whereas MTX was effective at low nanomolar concentrations. One of the DHFR inhibitors (1), with an IC(50) value for rlDHFR approximately 8 times higher than that of methotrexate, was selected for in vivo experiments in an experimental colitis model in mice. This compound demonstrated a clear antiinflammatory effect after topical administration, comparable to the effect achieved with the glucocorticoid budesonide. Three parameters were evaluated in this model: myeloperoxidase activity, colon weight, and inflammation scoring. A favorable in vivo effect of compound 1 (15 mg/(kg.day)) was observed in all three inflammatory parameters. However, the results cannot be explained fully by DHFR inhibition or by inhibition of lymphocyte cell proliferation, suggesting that other yet unidentified mechanisms enable reduction of inflammation in the colitis model. The mechanism of action of methotrexate analogues encompassing a bridging ester group is not well understood in vivo but seems to lend itself well to further development of similar compounds.