Quantitative assessment of mucosal architecture using computer-based analysis of confocal laser endomicroscopy in inflammatory bowel diseases.

BACKGROUND AND AIMS: Confocal laser endomicroscopy (CLE) might discriminate mucosal lesions between Crohn's disease (CD) and ulcerative colitis (UC). However, the analysis of CLE images requires time-consuming methods, a long training time, and potential impediments, such as significant interobserver variability. Therefore, we developed a computer-based method to analyze mucosal architecture from CLE images and discriminate between healthy subjects and patients with inflammatory bowel disease (IBD) as well as between UC and CD patients. METHODS: We retrospectively screened patients who had undergone CLE either for an evaluation of IBD in remission or for colorectal cancer screening (control subjects) between 2009 and 2016. We assessed 14 morphologic and functional parameters in each CLE recording from 23 CD patients, 27 UC patients, and 9 control patients. Next, we constructed 2 scores, 1 for the IBD diagnosis and 1 for the differential diagnosis between UC and CD. RESULTS: In IBD patients, the mean intercrypt distance, wall thickness, and fluorescein leakage through the colonic mucosa were significantly increased compared with control patients by 155%, 188%, and 297%, respectively (P < .05). In UC patients, the same parameters were significantly increased by 109%, 117%, and 174%, respectively (P < .05), compared with CD patients. IBD diagnosis had 100% (95%CI, 93%; 100%) sensitivity and 100% (95%CI, 66%; 100%) specificity. IBD differential diagnosis provided discrimination of UC from CD patients with 92% (95%CI, 75%; 99%) sensitivity and 91% (95%CI, 72%; 99%) specificity. CONCLUSIONS: Confirming these results using prospective validation cohorts can substantiate that computer-based analysis of CLE images may provide new biomarkers for the diagnosis and characterization of IBD.

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.

Improvement of Refractory Ulcerative Proctitis With Sacral Nerve Stimulation.

BACKGROUND AND AIMS: Sacral nerve stimulation (SNS) is recognized for its efficiency and safety for anal incontinence, preventing high morbidity. Evidence from the literature suggests extending SNS to diseases associated with problems of intestinal barrier permeability. The aim of this study was to highlight clinical evidence of the beneficial impact of SNS in a refractory proctitis case report. MATERIALS AND METHODS: A permanent SNS was performed successfully in a patient with proctitis after implantation of the neuromodulator. Despite immunosuppressive drugs, the patient was experiencing mucus and blood discharge, pain, and fecal incontinence. To relieve fecal incontinence, SNS was tested without modification of medications. Disease activity, endoscopic and histologic score, ex vivo barrier permeability, expression of inflammatory cytokines (transforming growth factor-ß, tumor necrosis factor α, Interleukin-6, Interleukin-8), and junctional proteins (ZO-1, claudin-1, occludin) were assessed before and after SNS to observe the impact of SNS other than for incontinence. RESULTS: After a 3-week period of temporary stimulation, the patient experienced significant improvement with a decrease in fecal incontinence and disease activity scores. Both endoscopic and histologic scores showed improvement. The rectal barrier permeability decreased with SNS, whereas junctional protein mRNA expression transiently increased. Clinical and histologic improvement was sustained over time. After 18 months of permanent stimulation, the patient remained improved by SNS. CONCLUSION: This work demonstrates the relevance to explore further indications of SNS beyond fecal incontinence.

Confocal laser endomicroscopy as predictive biomarker of clinical and endoscopic efficacy of vedolizumab in ulcerative colitis: The DETECT study.

AIMS: In patients with ulcerative colitis (UC), no biomarker is available to help the physician to choose the most suitable biotherapy. The primary objective of this pilot study was to assess the feasibility of identification of α4ß7- and TNF-expressing cells, to predict the response to vedolizumab using confocal laser endoscopy (CLE). METHODS: Patients with moderate-to-severe UC, naïve of biotherapy, received vedolizumab. Clinical evaluation was performed at each infusion. Endoscopic evaluation was performed before inclusion and at week 22. Fresh colonic biopsies were stained using FITC-labelled vedolizumab and Alexa fluor-labelled adalimumab and ex vivo dual-band CLE images were acquired. Blood samples were collected to measure trough concentrations of vedolizumab and to determine absolute counts of T and B cells subpopulations, NK cells and monocytes. RESULTS: Nineteen patients were enrolled in the study and received at least one dose of vedolizumab. Clinical remission and endoscopic improvement were observed in 58% of whom 5 patients (45%) had an endoscopic subscore of 0. In terms of clinical response and remission, endoscopic improvement and histologic response, FITC-conjugated vedolizumab staining tended to be higher in responder patients compared to non-responders at week 22. A threshold value of 6 positive FITC-vedolizumab staining areas detected by CLE seemed informative to discriminate the responders and non-responders. The results were similar in terms of clinical remission and endoscopic improvement with a sensitivity of 78% and a specificity of 85% (p = 0.05). Trough concentrations and blood immune cells were not associated with responses to vedolizumab. CONCLUSION: This pilot study demonstrate that dual-band CLE is feasible to detect α4ß7- and TNF-expressing cells. Positive α4ß7 staining seems to be associated with clinical and endoscopic remission in UC patients treated by anti-α4ß7-integrin, subject to validation by larger-scale studies. Clinical-trial.gov: NCT02878083.

Signaling by the tyrosine kinase Yes promotes liver cancer development.

Most patients with hepatocellular carcinoma (HCC) are diagnosed at a late stage and have few therapeutic options and a poor prognosis. This is due to the lack of clearly defined underlying mechanisms or a dominant oncogene that can be targeted pharmacologically, unlike in other cancer types. Here, we report the identification of a previously uncharacterized oncogenic signaling pathway in HCC that is mediated by the tyrosine kinase Yes. Using genetic and pharmacological interventions in cellular and mouse models of HCC, we showed that Yes activity was necessary for HCC cell proliferation. Transgenic expression of activated Yes in mouse hepatocytes was sufficient to induce liver tumorigenesis. Yes phosphorylated the transcriptional coactivators YAP and TAZ (YAP/TAZ), promoting their nuclear accumulation and transcriptional activity in HCC cells and liver tumors. We also showed that YAP/TAZ were effectors of the Yes-dependent oncogenic transformation of hepatocytes. Src family kinase activation correlated with the tyrosine phosphorylation and nuclear localization of YAP in human HCC and was associated with increased tumor burden in mice. Specifically, high Yes activity predicted shorter overall survival in patients with HCC. Thus, our findings identify Yes as a potential therapeutic target in HCC.

Effects of HIV protease inhibitors on progression of monocrotaline- and hypoxia-induced pulmonary hypertension in rats.

BACKGROUND: Pulmonary hypertension (PH) is among the complications of HIV infection. Combination antiretroviral therapy may influence the progression of HIV-related PH. Because Akt signaling is a potential molecular target of HIV protease inhibitors (HPIs), we hypothesized that these drugs altered monocrotaline- and hypoxia-induced PH in rats by downregulating the Akt pathway, thereby inhibiting pulmonary artery smooth muscle cell proliferation. METHODS AND RESULTS: Daily treatment with each of 3 first-generation HPIs (ritonavir 30 mg/kg, amprenavir 100 mg/kg, and nelfinavir 500 mg/kg) started 3 weeks after a subcutaneous monocrotaline injection (60 mg/kg) substantially diminished pulmonary artery pressure, right ventricular hypertrophy, number of muscularized pulmonary vessels, pulmonary arterial wall thickness, and proliferating pulmonary vascular Ki67-labeled cells without affecting vessel caspase 3 staining. HPI treatment partially prevented the development of hypoxia- and monocrotaline-induced PH. Monocrotaline-induced PH was associated with marked activation of Akt signaling in the lungs and proximal pulmonary arteries, with increases in phosphorylated Akt, phosphorylated glycogen-synthase-kinase-3ß (GSK3), and phosphorylated endothelial nitric oxide synthase, all of which decreased markedly after treatment with each HPI. In contrast, PH-associated increases in phosphorylated extracellular signal-related kinase 1/2 and myosin light-chain phosphatase were unaltered by the HPIs. The 3 HPIs and the phosphatidylinositol 3-kinase inhibitor LY294002 inhibited platelet-derived growth factor-induced phosphorylation of Akt and GSK3 in cultured pulmonary artery smooth muscle cells and blocked cell proliferation; this last effect was abolished by the GSK3 inhibitor SB216763. CONCLUSION: These results support an effect of HPIs on pulmonary vascular remodeling mediated by inhibition of Akt phosphorylation and consequently of pulmonary artery smooth muscle cell proliferation.

Early remodeling of the colonic mucosa after allogeneic hematopoietic stem cells transplantation: An open-label controlled pilot study on 19 patients.

BACKGROUND: Graft-versus-host disease (GVHD), particularly acute digestive GVHD (aDGVHD), is a severe complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). It is necessary to identify predictive factors of GVHD to adapt prophylactic treatment. OBJECTIVE: In this context, our pilot study aimed (i) to determine whether an early remodeling of the colonic mucosa occurred after allo-HSCT and (ii) to identify potential predictive mucosal markers of aDGVHD after allo-HSCT. METHODS: Between day 21 and day 28 after the allo-HSCT, 19 allo-HSCT patients were included and had a rectosigmoidoscopy with probe-based confocal laser endomicroscopy (pCLE) recording and biopsies. Sixteen patients were included in the control group. Morphological (pCLE), functional (intestinal permeability), and inflammatory parameters (cytokine multiplex immunoassay) were assessed. RESULTS: Among allo-HSCT patients, 11 patients developed GVHD, and 6 of them developed aDGVHD. Morphological and functional changes of the colonic mucosa occurred after allo-HSCT. Indeed, the perimeter of colonic crypts was significantly increased in allo-HSCT patients compared to controls as well as crypt lumen fluorescein leakage (53% vs. 9%), whereas crypts sphericity, roundness, Feret diameter, and mean vessel area were significantly decreased in allo-HSCT patients compared to the control group. In addition, interleukin-6 (IL-6), IL-33, and IL-15 levels in the supernatants of 24 h explant cultures of colonic biopsies were significantly increased in allo-HSCT patients compared to controls. Finally, there was no difference in pCLE parameters, intestinal permeability, and inflammatory cytokines between patients who developed aDGVHD and those who did not. CONCLUSION: This pilot study identified early colonic mucosa remodeling after allo-HSCT conditioning therapy, that is morphological and functional mucosal alterations as well as mucosal inflammation. As to whether these changes are first steps in GVHD initiation and could be considered as predictive biomarkers of aDGVHD need to be determined in a larger cohort of patients.

Angiotensin II induces RhoA activation through SHP2-dependent dephosphorylation of the RhoGAP p190A in vascular smooth muscle cells.

Angiotensin II (ANG II) is a major regulator of blood pressure that essentially acts through activation of ANG II type 1 receptor (AT1R) of vascular smooth muscle cells (VSMC). AT1R activates numerous intracellular signaling pathways, including the small G protein RhoA known to control several VSMC functions. Nevertheless, the mechanisms leading to RhoA activation by AT1R are unknown. RhoA activation can result from activation of RhoA exchange factor and/or inhibition of Rho GTPase-activating protein (GAP). Here we hypothesize that a RhoGAP could participate to RhoA activation induced by ANG II in rat aortic VSMC. The knockdown of the RhoGAP p190A by small interfering RNA (siRNA) abolishes the activation of RhoA-Rho kinase pathway induced after 5 min of ANG II (0.1 microM) stimulation in rat aortic VSMC. We then show that AT1R activation induces p190A dephosphorylation and inactivation. In addition, expression of catalytically inactive or phosphoresistant p190A mutants increases the basal activity of RhoA-Rho kinase pathway, whereas phosphomimetic mutant inhibits early RhoA activation by ANG II. Using siRNA and mutant overexpression, we then demonstrate that the tyrosine phosphatase SHP2 is necessary for 1) maintaining p190A basally phosphorylated and activated by the tyrosine kinase c-Abl, and 2) inducing p190A dephosphorylation and RhoA activation in response to AT1R activation. Our work then defines p190A as a new mediator of RhoA activation by ANG II in VSMC.

Development of a porcine model for assessment of mucosal repair following endoscopic resection of the lower gastrointestinal tract.

BACKGROUND AND AIMS: Endoscopic mucosal resection (EMR) is widely performed for the treatment of colorectal polyps. However, the pathophysiological mechanisms of mucosal repair, including in situations at high risk of post-polypectomy bleeding, remain largely unknown. The objective of our study was to develop a porcine model of EMR in the lower gastrointestinal tract to monitor mucosal wound healing over time. METHODS: Under general anesthesia, five large wounds were created in the lower gastrointestinal tract at different times, i. e. at day 0, 3, 7, 10, and 14, by multiband EMR, in each of the six pigs in the study. A colorectal resection was performed at day 14 and the animal euthanized. Repeated endoscopic and endomicroscopic examination, and histological analysis were performed. RESULTS: No complications occurred and all animals reached the study end point. The endoscopic aspect of wound healing evolved into different phases with first a fibrin deposit covering the wounds which then gave way to granulomatous tissue. The size of the wound regressed significantly as early as day 3. Re-epithelialization of the wound started from day 7, and neo-mucosal crypts appeared from day 10. The endomicroscopic analysis described a 'ground glass appearance' from day 3 and irregular crypts from day 10, which was consistent with histological data. Good agreement between macroscopic, endomicroscopic, and histological parameters of mucosal wound healing was observed in vivo. CONCLUSION: This study demonstrates for the first time the feasibility of an experimental in vivo porcine model of lower gastrointestinal endoscopic resections to monitor tissue repair. This model might be helpful to document pharmacological approaches for preventing complications of endoscopic procedures performed in humans.

PCSK9-deficiency does not alter blood pressure and sodium balance in mouse models of hypertension.

OBJECTIVE: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is highly expressed in the kidney, where its function remains unclear. In vitro data suggested that PCSK9 could impair the trafficking of the epithelial Na channel (ENaC). Here, we aimed at determining the consequences of PCSK9-deficiency on blood pressure, sodium balance and ENaC function in vivo in mice. METHODS: Blood pressure was measured using non-invasive tail-cuff system or radiotelemetry under basal conditions in male and female PCSK9(+/+) and PCSK9(-/-) mice, as well as in models of hypertension: l-NAME (2 mg/kg/day), angiotensin II (1 mg/kg/day) and deoxycorticosterone acetate (DOCA)-salt in male mice only. Plasma and urine electrolytes (Na(+), K(+), Cl(-)) were collected under basal conditions, after DOCA-salt and amiloride treatment. Renal expression of ENaC subunits was assessed by western blotting. RESULTS: PCSK9-deficiency did not alter both basal blood pressure and its increase in salt-insensitive (l-NAME) and salt-sensitive (Ang-II and DOCA-salt) hypertension models. Plasma PCSK9 concentrations were increased by 2.8 fold in DOCA-salt-induced hypertension. The relative expression of the cleaved, active, 30-kDa αENaC subunit was significantly increased by 32% in kidneys of PCSK9(-/-) mice under basal, but not under high-Na(+) diet or DOCA-salt conditions. Amiloride increased urinary Na(+) excretion to similar level in both genotypes, indicating that ENaC activity was not affected by PCSK9-deficiency. CONCLUSIONS: Despite an increase of cleaved αENaC under basal condition, PCSK9(-/-) mice display normal sodium balance and blood pressure regulation. Altogether, these data are reassuring regarding the development of PCSK9 inhibitors in hypercholesterolemia.

Angiotensin II activates the RhoA exchange factor Arhgef1 in humans.

Although a causative role for RhoA-Rho kinase has been recognized in the development of human hypertension, the molecular mechanism(s) and the RhoA guanine exchange factor(s) responsible for the overactivation of RhoA remain unknown. Arhgef1 was identified as a RhoA guanine exchange factor involved in angiotensin II (Ang II)-mediated regulation of vascular tone and hypertension in mice. The aim of this study was to determine whether Arhgef1 is activated and involved in the activation of RhoA-Rho kinase signaling by Ang II in humans. In vitro stimulation of human coronary artery smooth muscle cells and human peripheral blood mononuclear cells by Ang II (0.1 µmol/L) induced activation of Arhgef1 attested by its increased tyrosine phosphorylation. Silencing of Arhgef1 expression by siRNA inhibited Ang II-induced activation of RhoA-Rho kinase signaling. In normotensive subjects, activation of the renin-angiotensin system by a low-salt diet for 7 days increased RhoA-Rho kinase signaling and stimulated Arhgef1 activity in peripheral blood mononuclear cells. In conclusion, our results strongly suggest that Arhgef1 mediates Ang II-induced RhoA activation in humans. Moreover, they show that measurement of RhoA guanine exchange factor activity in peripheral blood mononuclear cells might be a useful method to evaluate RhoA guanine exchange factor activity in humans.

The Rho exchange factor Arhgef1 mediates the effects of angiotensin II on vascular tone and blood pressure.

Hypertension is one of the most frequent pathologies in the industrialized world. Although recognized to be dependent on a combination of genetic and environmental factors, its molecular basis remains elusive. Increased activity of the monomeric G protein RhoA in arteries is a common feature of hypertension. However, how RhoA is activated and whether it has a causative role in hypertension remains unclear. Here we provide evidence that Arhgef1 is the RhoA guanine exchange factor specifically responsible for angiotensin II-induced activation of RhoA signaling in arterial smooth muscle cells. We found that angiotensin II activates Arhgef1 through a previously undescribed mechanism in which Jak2 phosphorylates Tyr738 of Arhgef1. Arhgef1 inactivation in smooth muscle induced resistance to angiotensin II-dependent hypertension in mice, but did not affect normal blood pressure regulation. Our results show that control of RhoA signaling through Arhgef1 is central to the development of angiotensin II-dependent hypertension and identify Arhgef1 as a potential target for the treatment of hypertension.