Mechanisms of antidiarrhoeal effects by diosmectite in human intestinal cells

SARS-CoV-2 causes secretory diarrhea with an enterotoxin-like mechanism, which is reduced by diosmectite

BACKGROUND AND AIMS

The pathophysiology of SARS-CoV-2-associated diarrhea is unknown. Using an experimental model validated for rotavirus-induced diarrhea, we investigated the effects of SARS-CoV-2 on transepithelial ion fluxes and epithelial integrity of human intestinal cells. The effect of the antidiarrheal agent diosmectite on secretion was also evaluated following its inclusion in COVID-19 management protocols.

METHODS

We evaluated electrical parameters (intensity of short-circuit current [Isc] and transepithelial electrical resistance [TEER]) in polarized Caco-2 cells and in colonic specimens mounted in Ussing chambers after exposure to heat-inactivated (hi) SARS-CoV-2 and spike protein. Spectrofluorometry was used to measure reactive oxygen species (ROS), a marker of oxidative stress. Experiments were repeated after pretreatment with diosmectite, an antidiarrheal drug used in COVID-19 patients.

RESULTS

hiSARS-CoV-2 induced an increase in Isc when added to the mucosal (but not serosal) side of Caco-2 cells. The effect was inhibited in the absence of chloride and calcium and by the mucosal addition of the Ca2+-activated Cl- channel inhibitor A01, suggesting calcium-dependent chloride secretion. Spike protein had a lower, but similar, effect on Isc. The findings were consistent when repeated in human colonic mucosa specimens. Neither hiSARS-CoV-2 nor spike protein affected TEER, indicating epithelial integrity; both increased ROS production. Pretreatment with diosmectite inhibited the secretory effect and significantly reduced ROS of both hiSARS-CoV-2 and spike protein.

CONCLUSIONS

SARS-CoV-2 induces calcium-dependent chloride secretion and oxidative stress without damaging intestinal epithelial structure. The effects are largely induced by the spike protein and are significantly reduced by diosmectite. SARS-CoV-2 should be added to the list of human enteric pathogens.

Long-term diosmectite use does not alter the gut microbiota in adults with chronic diarrhea

Background

Diosmectite, a natural colloidal clay, has been used worldwide for a number of approved indications, including the treatment of chronic functional diarrhea. Here, we used high-resolution whole metagenome shotgun sequencing to assess the impact of a 5 weeks administration of diosmectite (3 g/sachet, 3 sachets/day) on the fecal microbiota of 35 adults with functional chronic diarrhea.

Results

Gut microbiota was not impacted by diosmectite administration. In particular, richness remained stable and no microbial species displayed a significant evolution. Segregating patients either by diosmectite response (non responder, early responder, late responder) or by nationality (Great-Britain or Netherlands) yielded the same results.

Conclusion

We concluded that no microbiota-related physiological alterations are expected upon long-term treatment with diosmectite.

Trial registration

Clinicaltrials.gov NCT03045926

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02464-7.

Treading a HOSTile path: Mapping the dynamic landscape of host cell-rotavirus interactions to explore novel host-directed curative dimensions

Viruses are intracellular pathogens and are dependent on host cellular resources to carry out their cycles of perpetuation. Obtaining an integrative view of host-virus interaction is of utmost importance to understand the complex and dynamic interplay between viral components and host machineries. Besides its obvious scholarly significance, a comprehensive host-virus interaction profile also provides a platform where from host determinants of pro-viral and antiviral importance can be identified and further be subjected to therapeutic intervention. Therefore, adjunct to conventional methods of prophylactic vaccination and virus-directed antivirals, this host-targeted antiviral approach holds promising therapeutic potential. In this review, we present a comprehensive landscape of host cellular reprogramming in response to infection with rotavirus (RV) which causes profuse watery diarrhea in neonates and infants. In addition, an emphasis is given on how host determinants are either usurped or subverted by RV in course of infection and how therapeutic manipulation of specific host factors can effectively modulate the RV life cycle.

Diosmectite inhibits the interaction between SARS-CoV-2 and human enterocytes by trapping viral particles, thereby preventing NF-kappaB activation and CXCL10 secretion

SARS-CoV-2 enters the intestine by the spike protein binding to angiotensin-converting enzyme 2 (ACE2) receptors in enterocyte apical membranes, leading to diarrhea in some patients. Early treatment of COVID-19-associated diarrhea could relieve symptoms and limit viral spread within the gastrointestinal (GI) tract. Diosmectite, an aluminomagnesium silicate adsorbent clay with antidiarrheal effects, is recommended in some COVID-19 management protocols. In rotavirus models, diosmectite prevents pathogenic effects by binding the virus and its enterotoxin. We tested the trapping and anti-inflammatory properties of diosmectite in a SARS-CoV-2 model. Trapping effects were tested in Caco-2 cells using spike protein receptor-binding domain (RBD) and heat-inactivated SARS-CoV-2 preparations. Trapping was assessed by immunofluorescence, alone or in the presence of cells. The effect of diosmectite on nuclear factor kappa B (NF-kappaB) activation and CXCL10 secretion induced by the spike protein RBD and heat-inactivated SARS-CoV-2 were analyzed by Western blot and ELISA, respectively. Diosmectite bound the spike protein RBD and SARS-CoV-2 preparation, and inhibited interaction of the spike protein RBD with ACE2 receptors on the Caco-2 cell surface. Diosmectite exposure also inhibited NF-kappaB activation and CXCL10 secretion. These data provide direct evidence that diosmectite can bind SARS-CoV-2 components and inhibit downstream inflammation, supporting a mechanistic rationale for consideration of diosmectite as a management option for COVID-19-associated diarrhea.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

The Role of Purported Mucoprotectants in Dealing with Irritable Bowel Syndrome, Functional Diarrhea, and Other Chronic Diarrheal Disorders in Adults

Chronic diarrhea is a frequent presenting symptom, both in primary care medicine and in specialized gastroenterology units. It is estimated that more than 5% of the global population suffers from chronic diarrhea. and that about 40% of these subjects are older than 60 years. The clinician is frequently faced with the need to decide which is the best therapeutic approach for these patients. While the origin of chronic diarrhea is diverse, impairment of intestinal barrier function, dysbiosis. and mucosal micro-inflammation are being increasingly recognized as underlying phenomena characterizing a variety of chronic diarrheal diseases. In addition to current pharmacological therapies, there is growing interest in alternative products such as mucoprotectants, which form a mucoadhesive film over the epithelium to reduce and protect against the development of altered intestinal permeability, dysbiosis, and mucosal micro-inflammation. This manuscript focuses on chronic diarrhea in adults, and we will review recent evidence on the ability of these natural compounds to improve symptoms associated with chronic diarrhea and to exert protective effects for the intestinal barrier.

Chemotherapy-induced diarrhoea in dogs and its management with smectite: Results of a monocentric open-label randomized clinical trial

Chemotherapy-induced diarrhoea (CID) is a frequent chemotherapy adverse event in dogs. Yet, there is currently no consensus regarding its management. Smectite is a natural medical clay, widely used in the treatment of acute diarrhoea in humans. The objectives of this study were to assess the efficacy of smectite in the management of CID in dogs, and to collect epidemiological data on CID. For each episode of diarrhoea, dogs were randomized into two management groups: Smectite group, receiving smectite at 0.5 g/kg PO per day divided in two to three doses initiated at the start of CID; control group, without initial medication. In both groups, rescue metronidazole was prescribed if CID progressed or was not improved within 48 hours. Sixty dogs were recruited and received 426 chemotherapy administrations between June 2017 and March 2019. The incidence rate of CID was 110/426 (25.8%, 95% CI: 21.7%-30.2%), and significantly differed between the chemotherapeutic drugs administered (P < .001). Metronidazole was administered in 5/54 events (9.3%, 95% CI: 3.1%-20.3%) in the smectite group and in 40/56 events (71.4%, 95% CI: 57.5%-82.3%) in the control group (P < .001). The time to resolution of diarrhoea was shorter (P < .001) in the smectite group (median: 19.5 hours, interquartile range [IQR]: 13.5-32 hours) compared with the control group (median: 53 hours, IQR: 31.5-113.5 hours). The results of this study support the administration of smectite in the first-line management of CID in dogs.

Enterosgel for the treatment of adults with acute diarrhoea in a primary care setting: a randomised controlled trial

Background

Acute intestinal infections are common conditions causing high morbidity and mortality especially in the young and elderly, resulting in a significant burden on health service resources and the economy. Current National Institute for Health and Care Excellence guidance are fluid and nutritional management; however, this does not reduce the duration of diarrhoea and the challenge of treating diarrhoea itself remains. We investigated the efficacy, tolerability and safety of intestinal adsorbent Enterosgel (polymethylsiloxane polyhydrate) compared with standard care in adults with acute diarrhoea.

Methods

This was a randomised controlled trial enrolling 105 subjects to receive the medical device Enterosgel up to six times daily for up to 8 days with standard care (oral rehydration solution), or standard care alone. The primary endpoint was the duration of diarrhoea (hours) from randomisation to first non-loose stool in the Enterosgel versus control group.

Results

A total of 51 subjects were randomised into the Enterosgel group and 54 into the control group, after excluding missing data, the data from 43 subjects in each group were analysed. Duration of diarrhoea was significantly shorter in the Enterosgel group at 27 hours versus 39 hours in the control group (HR was 1.74 [95% CI 1.06 to 2.87]) (p=0.03). This yielded a number needed to treat value of 5. Enterosgel was well tolerated and safe with no serious adverse events. One serious diarrhoea-related event resulting in hospitalisation was reported in the control group.

Conclusions

Enterosgel treatment was associated with a significant reduction in the duration of diarrhoea in adults with patient-reported acute diarrhoea, compared with standard care. These findings support the role of Enterosgel in acute diarrhoea especially in vulnerable groups where rapid resolution of symptoms is required. Reduction in symptom duration could translate to less healthcare costs and socioeconomic burden.

Trial registration number

ISRCTN20758708

Investigation of the adsorption capacity of the enterosorbent Enterosgel for a range of bacterial toxins, bile acids and pharmaceutical drugs

Oral intestinal adsorbents (enterosorbents) are orally administered materials which pass through the gut where they bind (adsorb) various substances. The enterosorbent Enterosgel (Polymethylsiloxane polyhdrate) is recommended as a symptomatic treatment for acute diarrhoea and chronic diarrhoea associated with irritable bowel syndrome (IBS). Since 1980’s there have been many Enterosgel clinical trials, however, the detailed mechanism of Enterosgel action towards specific toxins and interaction with concomitantly administered medications has not been fully investigated. Our in vitro study assessed the adsorption capacity of Enterosgel for bacterial enterotoxins and endotoxin, bile acids and interaction with the pharmaceutical drugs; Cetirizine and Amitriptyline hydrochloride. Our data demonstrate the good adsorption capacity of Enterosgel for bacterial toxins associated with gastrointestinal infection, with a lower than the comparator charcoal Charcodote capacity for bile acids whose levels can be raised in IBS patients. Adsorption capacity for the two drugs varied but was significantly lower than Charcodote. These findings suggest that the mechanism of Enterosgel action in the treatment of gastrointestinal infection or IBS is adsorption of target molecules followed by removal from the body. This therapy offers a drug free approach to prevention and treatment of infectious and chronic non-infectious diseases, where intestinal flora and endotoxemia play a role.

Effect of Montmorillonite powder on intestinal mucosal barrier in children with abdominal Henoch-Schonlein purpura: A randomized controlled study

BACKGROUND

Our previous studies found that intestinal barrier function has been changed in children with abdominal Henoch-Schonlein purpura (HSP). Montmorillonite has been shown to be protective for digestive tract mucosa.

OBJECTIVE

The present study aimed to investigate whether Montmorillonite powder could improve the intestinal mucosal barrier function in children with abdominal HSP.

METHODS

Using a randomized controlled study design, we compared plasma levels of diamine oxidase (DAO), D-lactate, and endotoxin in children with abdominal HSP before and after Montmorillonite powder treatment.

RESULTS

Among 28 patients in experimental group and 30 in control group, there was no significant difference in age, sex, height, weight, and course of disease between 2 groups (P > .05). Before treatment, there was no statistical difference in DAO, D-lactic acid, and endotoxin between experimental group and the control group (P > .05). However, significant differences were detected for DAO and D-lactate after treatment in comparison to before treatment in the Montmorillonite experimental group (P < .05). Such differences were not found in the control group (P > .05).

CONCLUSION

Montmorillonite powder is effective in the treatment of HSP via maintaining intestinal mucosal barrier function.