Defects in 15-HETE Production and Control of Epithelial Permeability by Human Enteric Glial Cells From Patients With Crohn's Disease.

BACKGROUND & AIMS: Enteric glial cells (EGCs) produce soluble mediators that regulate homeostasis and permeability of the intestinal epithelial barrier (IEB). We investigated the profile of polyunsaturated fatty acid (PUFA) metabolites produced by EGCs from rats and from patients with Crohn's disease (CD), compared with controls, along with the ability of one of these metabolites, 15-hydroxyeicosatetraenoic acid (15-HETE), to regulate the permeability of the IEB. METHODS: We isolated EGCs from male Sprague-Dawley rats, intestinal resections of 6 patients with CD, and uninflamed healthy areas of intestinal tissue from 6 patients who underwent surgery for colorectal cancer (controls). EGC-conditioned media was analyzed by high-sensitivity liquid-chromatography tandem mass spectrometry to determine PUFA signatures. We used immunostaining to identify 15-HETE-producing enzymes in EGCs and tissues. The effects of human EGCs and 15-HETE on permeability and transepithelial electrical resistance of the IEB were measured using Caco-2 cells; effects on signal transduction proteins were measured with immunoblots. Levels of proteins were reduced in Caco-2 cells using short-hairpin RNAs or proteins were inhibited pharmacologically. Rats were given intraperitoneal injections of 15-HETE or an inhibitor of 15-lipoxygenase (the enzyme that produces 15-HETE); colons were collected and permeability was measured. RESULTS: EGCs expressed 15-lipoxygenase-2 and produced high levels of 15-HETE, which increased IEB resistance and reduced IEB permeability. 15-HETE production was reduced in EGCs from patients with CD compared with controls. EGCs from patients with CD were unable to reduce the permeability of the IEB; the addition of 15-HETE restored permeability to levels of control tissues. Inhibiting 15-HETE production in rats increased the permeability of the IEB in colon tissues. We found that 15-HETE regulates IEB permeability by inhibiting an adenosine monophosphate-activated protein kinase and increasing expression of zonula occludens-1. CONCLUSIONS: Enteric glial cells from patients with CD have reduced production of 15-HETE, which controls IEB permeability by inhibiting adenosine monophosphate-activated protein kinase and increasing expression of zonula occludens-1.

Sacral nerve stimulation enhances early intestinal mucosal repair following mucosal injury in a pig model.

KEY POINTS: Reducing intestinal epithelial barrier (IEB) dysfunctions is recognized as being of major therapeutic interest for various intestinal disorders. Sacral nerve stimulation (SNS) is known to reduce IEB permeability. Here, we report in a pig model that SNS enhances morphological and functional recovery of IEB following mucosal injury induced via 2,4,6-trinitrobenzenesulfonic acid. These effects are associated with an increased expression of tight junction proteins such as ZO-1 and FAK. These results establish that SNS enhances intestinal barrier repair in acute mucosal injury. They further set the scientific basis for future use of SNS as a complementary or alternative therapeutic option for the treatment of gut disorders with IEB dysfunctions such as inflammatory bowel diseases or irritable bowel syndrome. ABSTRACT: Intestinal epithelial barrier (IEB) dysfunctions, such as increased permeability or altered healing, are central to intestinal disorders. Sacral nerve stimulation (SNS) is known to reduce IEB permeability, but its ability to modulate IEB repair remains unknown. This study aimed to characterize the impact of SNS on mucosal repair following 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced lesions. Six pigs were stimulated by SNS 3 h prior to and 3 h after TNBS enema, while sham animals (n = 8) were not stimulated. The impact of SNS on mucosal changes was evaluated by combining in vivo imaging, histological and functional methods. Biochemical and transcriptomic approaches were used to analyse the IEB and mucosal inflammatory response. We observed that SNS enhanced the recovery from TNBS-induced increase in transcellular permeability. At 24 h, TNBS-induced alterations of mucosal morphology were significantly less in SNS compared with sham animals. SNS reduced TNBS-induced changes in ZO-1 expression and its epithelial pericellular distribution, and also increased pFAK/FAK expression compared with sham. Interestingly, SNS increased the mucosal density of neutrophils, which was correlated with an increase in trypsin and TGF-ß1 levels compared with sham. Finally, SNS prevented the TNBS-induced increases in IL-1ß and IL-4 over time that were observed with sham treatment. In conclusion, our results show that SNS enhances mucosal repair following injury. This study highlights novel mechanisms of action of SNS and identifies SNS as a new therapy for diseases with IEB repair disorders.

Comparison of two techniques used in routine care for the treatment of inflammatory macular oedema, subconjunctival triamcinolone injection and intravitreal dexamethasone implant: medical and economic importance of this randomized controlled trial.

BACKGROUND: Whether they are injected peri- or intraocularly, corticosteroids are still essential tools in the therapeutic arsenal for treating inflammatory macular oedema. A few years ago, however, only triamcinolone acetonide was available to ophthalmologists. While this compound was initially developed for rheumatological or dermatological use, it has been increasingly deployed in ophthalmology, despite still being off-label. In 2011, the system for delivery of dexamethasone from a biodegradable, injectable implant into the vitreous cavity obtained approval for use in inflammatory macular oedema. While the efficacy and safety of triamcinolone in macular oedema, including inflammatory oedema, have already been studied, there are currently no publications on subconjunctival triamcinolone injections, which are simple, effective and well tolerated. To date, the dexamethasone 700 µg implant has been authorized for the treatment of noninfectious intermediate and posterior uveitis, but there have been no studies to evaluate the efficacy and safety of the different peri- and intraocular strategies, including the treatment of inflammatory macular oedema. METHODS: This protocol is therefore designed to compare the efficacy and safety of peri- and intraocular corticosteroid injections in the treatment of inflammatory macular oedema. In this ongoing study, 142 patients will be included, and the oedematous eye will be randomised to treatment with either subconjunctival triamcinolone injection or an intravitreal implant containing 700 µg dexamethasone. Follow-up is planned for 6 months with monthly visits. Each visit will include visual acuity measurement, a slit lamp examination, fundoscopy, intraocular pressure measurement, laser flare measurement (if available) and spectral domain optical coherence tomography. DISCUSSION: The results of this trial will have a real impact on public health if it is shown that a Kenacort retard® (i.e. triamcinolone) injection costing just €2.84 and performed in the physician's office (with no additional overhead costs) is at least as effective as the dexamethasone 700 µg implant (Ozurdex®; costing approximately €960 with the injection performed in a dedicated room), with no increased side effects. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02556424. Registered on 22 September 2015.

The arachidonic acid metabolite 11ß-ProstaglandinF2α controls intestinal epithelial healing: deficiency in patients with Crohn's disease.

In healthy gut enteric glial cells (EGC) are essential to intestinal epithelial barrier (IEB) functions. In Crohn's Disease (CD), both EGC phenotype and IEB functions are altered, but putative involvement of EGC in CD pathogenesis remains unknown and study of human EGC are lacking. EGC isolated from CD and control patients showed similar expression of glial markers and EGC-derived soluble factors (IL6, TGF-ß, proEGF, GSH) but CD EGC failed to increase IEB resistance and healing. Lipid profiling showed that CD EGC produced decreased amounts of 15-HETE, 18-HEPE, 15dPGJ2 and 11ßPGF2α as compared to healthy EGC. They also had reduced expression of the L-PGDS and AKR1C3 enzymes. Produced by healthy EGC, the 11ßPGF2 activated PPARγ receptor of intestinal epithelial cells to induce cell spreading and IEB wound repair. In addition to this novel healing mechanism our data show that CD EGC presented impaired ability to promote IEB functions through defect in L-PGDS-AKR1C3-11ßPGF2α dependent pathway.