Specialized pro-resolvin mediators induce cell growth and improve wound repair in intestinal epithelial Caco-2 cell cultures.

Specialized pro-resolvin mediators (SPMs) are a superfamily of bioactive molecules synthesized from polyunsaturated fatty acids (arachidonic, eicosapentaenoic and docosahexaenoic acids) that include resolvins, protectins and maresins. These metabolites are important to control the resolution phase of inflammation and the epithelial repair, which is essential in restoring the mucosal barriers. Unfortunately, the effects of SPMs on intestinal epithelial cell growth remain poorly understood. Caco-2 cell were used as intestinal epithelial cell model. Cell growth/DNA synthesis, cell signalling pathways, western blot and wound repair assay were performed. Our data demonstrated that SPMs such as lipoxin LxA4, resolvin (Rv) E1, RvD1, protectin D 1 and maresin 1 were able to enhance intestinal epithelial Caco-2 cell growth and DNA synthesis. Furthermore, our results provide evidence that these effects of RvE1 and RvD1 were associated with a pertussis toxin-sensitive G protein-coupled receptor, and that leukotriene B4 receptor 2 could be involved, at least in part, in these effects of RvE1/RvD1. Moreover, these mitogenic effects induced by SPMs were dependent on the ERK 1/2 and p38 MAPK pathways as well as phospholipase C and protein kinase C activation. Thus, these mitogenic effects of RvE1/RvD1 on intestinal epithelial cells could be involved in this signalling circuit involved in wounded epithelium and the catabasis process.

12(S)-hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) induces cell growth and improves barrier function through BLT2 interaction in intestinal epithelial Caco-2 cell cultures.

12(S)-hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) is an unusual product of the cyclooxygenase pathway that is an endogenous ligand of the low-affinity receptor for leukotriene 4 (LTB4), BLT2. Recent findings suggested that BLT2 possibly plays an important role in the healing of intestinal lesions and the regulation of barrier function. Here, we studied the role of 12-HHT on intestinal epithelial cell growth and the paracellular permeability of intestinal epithelium using Caco-2 cell cultures as experimental model. Our results demonstrated that 12-HHT stimulates intestinal epithelial Caco-2 cell growth through 12-HHT-BLT2-p38-PKC axis and improves paracellular permeability in differentiated Caco-2 cell cultures through the regulation of tight junction elements such as myosin light chain phosphorylation through 12-HHT-BLT2-p38-PKC-MYPT1 axis. Thus, 12-HHT-BLT2 interaction can be involved in intestinal epithelial cell growth and consequently in the epithelium regeneration/repair processes, together with an interesting improvement on the paracellular permeability. These effects appoint that 12-HHT/BLT2 axis may be a suitable strategy for treating wound healing epithelium and barrier-disrupted intestinal processes.

A Mediterranean diet supplemented with extra virgin olive oil or nuts improves endothelial markers involved in blood pressure control in hypertensive women.

PURPOSE: Serum nitric oxide (NO) reduction and increased endothelin-1 (ET-1) play a pivotal role in endothelial dysfunction and hypertension. Considering that traditional Mediterranean diet (TMD) reduces blood pressure (BP), the aim of this study was to analyze whether TMD induced changes on endothelial physiology elements such as NO, ET-1 and ET-1 receptors which are involved in BP control. METHODS: Non-smoking women with moderate hypertension were submitted for 1 year to interventions promoting adherence to the TMD, one supplemented with extra virgin olive oil (EVOO) and the other with nuts versus a control low-fat diet (30 participants/group). BP, NO, ET-1 and related gene expression as well as oxidative stress biomarkers were measured. RESULTS: Serum NO and systolic BP (SBP) or diastolic BP (DBP) were negatively associated at baseline, as well as between NO and ET-1. Our findings also showed a DBP reduction with both interventions. A negative correlation was observed between changes in NO metabolites concentration and SBP or DBP after the intervention with TMD + EVOO (p = 0.033 and p = 0.044, respectively). SBP reduction was related to an impairment of serum ET-1 concentrations after the intervention with TMD + nuts (p = 0.008). We also observed changes in eNOS, caveolin 2 and ET-1 receptors gene expression which are related to NO metabolites levels and BP. CONCLUSIONS: The changes in NO and ET-1 as well as ET-1 receptors gene expression explain, at least partially, the effect of EVOO or nuts on lowering BP among hypertensive women.

5-Hydroxyeicosatetraenoic acid and leukotriene D4 increase intestinal epithelial paracellular permeability.

The loss of epithelial barrier function plays a crucial role in the pathogenesis of inflammatory bowel disease, with levels of 5-lipoxygenase metabolites being increased in the mucosa of these patients. The objective of this study was to determine the effect of the eicosanoids produced by the 5-lipoxygenase pathway, leukotriene B4 and D4, and 5-hydroxyeicosatetraenoic acid on epithelial barrier function. Paracellular permeability was estimated from fluorescein isothiocyanate-dextran fluxes and transepithelial electrical resistance in differentiated Caco-2 cells. Our results suggest that leukotriene D4 and 5-hydroxyeicosatetraenoic acid altered both parameters. Identification of the receptors involved in these changes indicated that cysteinyl-leukotriene receptor 1 participates in the effects of leukotriene D4. For both eicosanoids, these effects were mediated by activation of the phospholipase C/Ca(2+)/protein kinase C pathway, in addition to cAMP-independent protein kinase A activation. Furthermore, we observed a correlation between increased paracellular permeability and the redistribution of occludin, and for leukotriene D4, the disorganization of the subapical actin ring and myosin light chain kinase activation. In conclusion, on the basis of our results, we propose that 5-lipoxygenase pathway metabolites participate in the disruption of epithelial barrier function that is characteristic of inflammatory bowel disease.