Molecular mechanism of the TGF­ß/Smad7 signaling pathway in ulcerative colitis.

Aberrant TGF­ß/Smad7 signaling has been reported to be an important mechanism underlying the pathogenesis of ulcerative colitis. Therefore, the present study aimed to investigate the effects of a number of potential anti­colitis agents on intestinal epithelial permeability and the TGF­ß/Smad7 signaling pathway in an experimental model of colitis. A mouse model of colitis was first established before anti­TNF­α and 5­aminosalicyclic acid (5­ASA) were administered intraperitoneally and orally, respectively. Myeloperoxidase (MPO) activity, histological index (HI) of the colon and the disease activity index (DAI) scores were then detected in each mouse. Transmission electron microscopy (TEM), immunohistochemical and functional tests, including Evans blue (EB) and FITC­dextran (FD­4) staining, were used to evaluate intestinal mucosal permeability. The expression of epithelial phenotype markers E­cadherin, occludin, zona occludens (ZO­1), TGF­ß and Smad7 were measured. In addition, epithelial myosin light chain kinase (MLCK) expression and activity were measured. Anti­TNF­α and 5­ASA treatments was both found to effectively reduce the DAI score and HI, whilst decreasing colonic MPO activity, plasma levels of FD­4 and EB permeation of the intestine. Furthermore, anti­TNF­α and 5­ASA treatments decreased MLCK expression and activity, reduced the expression of Smad7 in the small intestine epithelium, but increased the expression of TGF­ß. In mice with colitis, TEM revealed partial epithelial injury in the ileum, where the number of intercellular tight junctions and the expression levels of E­cadherin, ZO­1 and occludin were decreased, all of which were alleviated by anti­TNF­α and 5­ASA treatment. In conclusion, anti­TNF­α and 5­ASA both exerted protective effects on intestinal epithelial permeability in an experimental mouse model of colitis. The underlying mechanism may be mediated at least in part by the increase in TGF­ß expression and/or the reduction in Smad7 expression, which can inhibit epithelial MLCK activity and in turn reduce mucosal permeability during the pathogenesis of ulcerative colitis.

Colon Capsule Endoscopy in the Assessment of Mucosal Healing in Crohn's Disease.

BACKGROUND: Patients with Crohn's disease (CD) undergo frequent endoscopic procedures, with visualization of the gastrointestinal mucosa central to treatment decision-making. Subsequently, a noninvasive alternative to optical colonoscopy (OC) would be welcomed. One such technology is capsule endoscopy, including the PillCam COLON 2 (PCC2), though research validating its use in ileocolonic CD is limited. This study aims to compare PCC2 with ileocolonoscopy (OC) in assessing mucosal CD through use of a standardized scoring system. METHODS: At an Australian tertiary hospital, same-day PCC2 and ileocolonoscopy results of 47 CD patients, with known nonstricturing disease, were prospectively collected and analyzed for correlation and agreement. Deidentified recordings were reported by a single expert gastroenterologist. Mucosal disease was quantified using the Simple Endoscopic Score for Crohn's Disease (SES-CD). The SES-CD results of paired endoscopic modalities were compared in total per bowel segment and per SES-CD variable. RESULTS: Of 47 PCC2 recordings, 68% were complete, fully assessing terminal ileum to rectum, and OC was complete in 89%. Correlation (r) between total SES-CD scores was strongest in the terminal ileum (r = 0.77, P < .001), with the SES-CD variable of "ulcer detection" showing the strongest agreement. The PCC2 (vs OC) identified additional ulcers in the terminal ileum; ascending, transverse, and descending colon; and rectum; scores were 5 (1), 5 (3), 1 (1), 2 (1), and 2 (2), respectively. CONCLUSIONS: The PCC2 shows promise in assessing ileocolonic mucosa, especially in proximal bowel segments, with greater reach of visualization in the small bowel. Given the resource and safety considerations raised by the Coronavirus disease 2019 pandemic, capsule endoscopy has particular significance.This article aims to contribute to the limited body of research surrounding the validity of capsule endoscopy technology in assessing ileocolonic mucosa in Crohn's Disease patients. In doing so, an alternative option for patients enduring frequent endoscopies is given potential.

Systemic steroids and risk of fecal-oral shedding and increased transmission of SARS-CoV-2 in pemphigus cases.

Pemphigus and its variants, viz., vulgaris, foliaceous, vegetans, Ig A pemphigus, paraneoplastic pemphigus and Senear-Usher syndrome are rare autoimmune blistering diseases of the skin and/or mucous membranes. The autoantibodies involved in the pathogenesis of pemphigus against desmoglein result in the breach of the skin and mucosal barrier, which acts as the first line of defence against pathogens. In this paper we underscore the importance of the integumentary system as a shield against the acquisition as well as transmission of SARS-CoV-2 virion. We have also made an attempt to delineate the various treatment modalities available and the viral-drug dynamics involved in choosing the optimum therapeutic modality.

Multisystem inflammatory syndrome in children is driven by zonulin-dependent loss of gut mucosal barrier.

BACKGROUNDWeeks after SARS-CoV-2 infection or exposure, some children develop a severe, life-threatening illness called multisystem inflammatory syndrome in children (MIS-C). Gastrointestinal (GI) symptoms are common in patients with MIS-C, and a severe hyperinflammatory response ensues with potential for cardiac complications. The cause of MIS-C has not been identified to date.METHODSHere, we analyzed biospecimens from 100 children: 19 with MIS-C, 26 with acute COVID-19, and 55 controls. Stools were assessed for SARS-CoV-2 by reverse transcription PCR (RT-PCR), and plasma was examined for markers of breakdown of mucosal barrier integrity, including zonulin. Ultrasensitive antigen detection was used to probe for SARS-CoV-2 antigenemia in plasma, and immune responses were characterized. As a proof of concept, we treated a patient with MIS-C with larazotide, a zonulin antagonist, and monitored the effect on antigenemia and the patient's clinical response.RESULTSWe showed that in children with MIS-C, a prolonged presence of SARS-CoV-2 in the GI tract led to the release of zonulin, a biomarker of intestinal permeability, with subsequent trafficking of SARS-CoV-2 antigens into the bloodstream, leading to hyperinflammation. The patient with MIS-C treated with larazotide had a coinciding decrease in plasma SARS-CoV-2 spike antigen levels and inflammatory markers and a resultant clinical improvement above that achieved with currently available treatments.CONCLUSIONThese mechanistic data on MIS-C pathogenesis provide insight into targets for diagnosing, treating, and preventing MIS-C, which are urgently needed for this increasingly common severe COVID-19-related disease in children.

Exposure of human intestinal epithelial cells and primary human hepatocytes to trypsin-like serine protease inhibitors with potential antiviral effect.

Human intestinal epithelial cell line-6 (HIEC-6) cells and primary human hepatocytes (PHHs) were treated with 3-amidinophenylalanine-derived inhibitors of trypsin-like serine proteases for 24 hours. It was proven that treatment with MI-1900 and MI-1907 was tolerated up to 50 µM in HIEC-6. These inhibitors did not cause elevations in extracellular H2O2 levels and in the concentrations of interleukin (IL)-6 and IL-8 and did not alter occludin distribution in HIEC-6. It was also found that MI-1900 and MI-1907 up to 50 µM did not affect cell viability, IL-6 and IL-8 and occludin levels of PHH. Based on our findings, these inhibitors could be safely applicable at 50 µM in HIEC-6 and in PHH; however, redox status was disturbed in case of PHH. Moreover, it has recently been demonstrated that MI-1900 prevents the replication and spread of the new SARS-CoV-2 in infected Calu-3 cells, most-likely via an inhibition of the membrane-bound host protease TMPRSS2.

In search of preventive strategies: novel high-CBD Cannabis sativa extracts modulate ACE2 expression in COVID-19 gateway tissues.

With the current COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is an urgent need for new therapies and prevention strategies that can help curtail disease spread and reduce mortality. The inhibition of viral entry and thus spread is a plausible therapeutic avenue. SARS-CoV-2 uses receptor-mediated entry into a human host via the angiotensin-converting enzyme 2 (ACE2), which is expressed in lung tissue as well as the oral and nasal mucosa, kidney, testes and gastrointestinal tract. The modulation of ACE2 levels in these gateway tissues may be an effective strategy for decreasing disease susceptibility. Cannabis sativa, especially those high in the anti-inflammatory cannabinoid cannabidiol (CBD), has been found to alter gene expression and inflammation and harbour anti-cancer and anti-inflammatory properties. However, its effects on ACE2 expression remain unknown. Working under a Health Canada research license, we developed over 800 new C. sativa cultivars and hypothesized that high-CBD C. sativa extracts may be used to down-regulate ACE2 expression in target COVID-19 tissues. Using artificial 3D human models of oral, airway and intestinal tissues, we identified 13 high-CBD C. sativa extracts that decrease ACE2 protein levels. Some C. sativa extracts down-regulate serine protease TMPRSS2, another critical protein required for SARS-CoV-2 entry into host cells. While our most effective extracts require further large-scale validation, our study is important for future analyses of the effects of medical cannabis on COVID-19. The extracts of our most successful novel high-CBD C. sativa lines, pending further investigation, may become a useful and safe addition to the prevention/treatment of COVID-19 as an adjunct therapy.

The Role of Angiotensin Converting Enzyme 2 in Modulating Gut Microbiota, Intestinal Inflammation, and Coronavirus Infection.

The role of angiotensin converting enzyme 2 has expanded from regulating the renin angiotensin system to regulating intestinal amino acid homeostasis and the gut microbiome. Recently, angiotensin converting enzyme 2 was identified as a primary receptor for severe acute respiratory syndrome coronaviruses 1 and 2 being expressed in multiple tissues including the luminal surface of the gut. In this brief perspective, we examine the role of angiotensin converting enzyme 2 as the receptor for severe acute respiratory syndrome coronavirus 2 and the impact of coronavirus disease 19 infection on the gut microbiome and on the gut epithelium.

Intestinal Inflammation Modulates the Expression of ACE2 and TMPRSS2 and Potentially Overlaps With the Pathogenesis of SARS-CoV-2-related Disease.

BACKGROUND AND AIMS: The presence of gastrointestinal symptoms and high levels of viral RNA in the stool suggest active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication within enterocytes. METHODS: Here, in multiple, large cohorts of patients with inflammatory bowel disease (IBD), we have studied the intersections between Coronavirus Disease 2019 (COVID-19), intestinal inflammation, and IBD treatment. RESULTS: A striking expression of ACE2 on the small bowel enterocyte brush border supports intestinal infectivity by SARS-CoV-2. Commonly used IBD medications, both biologic and nonbiologic, do not significantly impact ACE2 and TMPRSS2 receptor expression in the uninflamed intestines. In addition, we have defined molecular responses to COVID-19 infection that are also enriched in IBD, pointing to shared molecular networks between COVID-19 and IBD. CONCLUSIONS: These data generate a novel appreciation of the confluence of COVID-19- and IBD-associated inflammation and provide mechanistic insights supporting further investigation of specific IBD drugs in the treatment of COVID-19. Preprint doi: https://doi.org/10.1101/2020.05.21.109124.

Lactoferrin as Protective Natural Barrier of Respiratory and Intestinal Mucosa against Coronavirus Infection and Inflammation.

Recently, the world has been dealing with a devastating global pandemic coronavirus infection, with more than 12 million infected worldwide and over 300,000 deaths as of May 15th 2020, related to a novel coronavirus (2019-nCoV), characterized by a spherical morphology and identified through next-generation sequencing. Although the respiratory tract is the primary portal of entry of SARS-CoV-2, gastrointestinal involvement associated with nausea, vomiting and diarrhoea may also occur. No drug or vaccine has been approved due to the absence of evidence deriving from rigorous clinical trials. Increasing interest has been highlighted on the possible preventative role and adjunct treatment of lactoferrin, glycoprotein of human secretions part of a non-specific defensive system, known to play a crucial role against microbial and viral infections and exerting anti-inflammatory effects on different mucosal surfaces and able to regulate iron metabolism. In this review, analysing lactoferrin properties, we propose designing a clinical trial to evaluate and verify its effect using a dual combination treatment with local, solubilized intranasal spray formulation and oral administration. Lactoferrin could counteract the coronavirus infection and inflammation, acting either as natural barrier of both respiratory and intestinal mucosa or reverting the iron disorders related to the viral colonization.