Melatonin reduces TNF-a induced expression of MAdCAM-1 via inhibition of NF-kB.

BACKGROUND: Endothelial MAdCAM-1 (mucosal addressin cell adhesion molecule-1) expression is associated with the oxidant-dependent induction and progress of inflammatory bowel disease (IBD). Melatonin, a relatively safe, potent antioxidant, has shown efficacy in several chronic injury models may limit MAdCAM-1 expression and therefore have a therapeutic use in IBD. METHODS: We examined how different doses of melatonin reduced endothelial MAdCAM-1 induced by TNF-a in an in vitro model of lymphatic endothelium. Endothelial monolayers were pretreated with melatonin prior to, and during an exposure, to TNF-a (1 ng/ml, 24 h), and MAdCAM-1 expression measured by immunoblotting. RESULTS: MAdCAM-1 was induced by TNF-a. Melatonin at concentrations over 100 μm (10(-4) M) significantly attenuated MAdCAM-1 expression and was maximal at 1 mM. CONCLUSIONS: Our data indicate that melatonin may exert therapeutic activity in IBD through its ability to inhibit NF-kB dependent induction of MAdCAM-1

TNF-α induced endothelial MAdCAM-1 expression is regulated by exogenous, not endogenous nitric oxide

BACKGROUND: MAdCAM-1 is an adhesion molecule expressed in Peyer's patches and lymphoid tissues which is mobilized by cytokines like TNF-α and is a major determinant of lymphocyte trafficking to the gut in human inflammatory bowel disease (IBD). It has been suggested that both reactive oxygen and nitrogen metabolites participate in regulating adhesion molecule expression in response to TNF-α. METHODS: To examine how exogenous and endogenous sources of NO modulate MAdCAM-1 induction by TNF-α, we pre-treated mouse lymphatic endothelial cells with either long or short acting NO donors prior to TNF-α-stimulation, and measured MAdCAM-1 induction at 24 h. RESULTS AND DISCUSSION: DETA-NO, a long-acting NO donor, and SperNO, a rapid releasing NO donor both inhibited TNF-α-stimulated MAdCAM-1 expression in a concentration dependent manner. Both NO donors also reduced a4b7-dependent lymphocyte endothelial adhesion. Inhibition of endogenous NO production by either L-NAME, a non-selective NOS inhibitor, or by 1400 w, a selective iNOS inhibitor failed to induce, or potentiate TNF-α regulated MAdCAM-1 expression. CONCLUSIONS: Exogenous NO donors may be beneficial in the treatment of IBD, while endogenous nitric oxide synthases may be less effective in controlling adhesion molecule expression in response to cytokines

Association of T-Zone Reticular Networks and Conduits with Ectopic Lymphoid Tissues in Mice and Humans

Ectopic or tertiary lymphoid tissues (TLTs) are often induced at sites of chronic inflammation. They typically contain various hematopoietic cell types, high endothelial venules, and follicular dendritic cells; and are organized in lymph node–like structures. Although fibroblastic stromal cells may play a role in TLT induction and persistence, they have remained poorly defined. Herein, we report that TLTs arising during inflammation in mice and humans in a variety of tissues (eg, pancreas, kidney, liver, and salivary gland) contain stromal cell networks consisting of podoplanin+ T-zone fibroblastic reticular cells (TRCs), distinct from follicular dendritic cells. Similar to lymph nodes, TRCs were present throughout T-cell–rich areas and had dendritic cells associated with them. They expressed lymphotoxin (LT) β receptor (LTβR), produced CCL21, and formed a functional conduit system. In rat insulin promoter–CXCL13–transgenic pancreas, the maintenance of TRC networks and conduits was partially dependent on LTβR and on lymphoid tissue inducer cells expressing LTβR ligands. In conclusion, TRCs and conduits are hallmarks of secondary lymphoid organs and of well-developed TLTs, in both mice and humans, and are likely to act as important scaffold and organizer cells of the T-cell–rich zone

Transfection of IL-10 expression vectors into endothelial cultures attenuates α4β7-dependent lymphocyte adhesion mediated by MAdCAM-1

BACKGROUND: Enhanced expression of MAdCAM-1 (mucosal addressin cell adhesion molecule-1) is associated with the onset and progression of inflammatory bowel disease. The clinical significance of elevated MAdCAM-1 expression is supported by studies showing that immunoneutralization of MAdCAM-1, or its ligands reduce inflammation and mucosal damage in models of colitis. Interleukin-10 (IL-10) is an endogenous anti-inflammatory and immunomodulatory cytokine that has been shown to prevent inflammation and injury in several animal studies, however clinical IL-10 treatment remains insufficient because of difficulties in the route of IL-10 administration and its biological half-life. Here, we examined the ability of introducing an IL-10 expression vector into endothelial cultures to reduce responses to a proinflammatory cytokine, TNF-α METHODS: A human IL-10 expression vector was transfected into high endothelial venular ('HEV') cells (SVEC4-10); we then examined TNF-α induced lymphocyte adhesion to lymphatic endothelial cells and TNF-α induced expression of MAdCAM-1 and compared these responses to control monolayers. RESULTS: Transfection of the IL-10 vector into endothelial cultures significantly reduced TNF-α induced, MAdCAM-1 dependent lymphocyte adhesion (compared to non-transfected cells). IL-10 transfected endothelial cells expressed less than half (46 ± 6.6%) of the MAdCAM-1 induced by TNF-α (set as 100%) in non-transfected (control) cells. CONCLUSION: Our results suggest that gene therapy of the gut microvasculature with IL-10 vectors may be useful in the clinical treatment of IBD