Effects of an alanyl-glutamine—based oral rehydration and nutrition therapy solution on electrolyte and water absorption in a rat model of secretory diarrhea induced by cholera toxin

Diarrheal disease is a severe global health problem. It is estimated that secretory diarrhea causes 2.5 million deaths annually among children under the age of five in the developing world. A critical barrier in treating diarrheal disease is lack of easy-to-use effective treatments. While antibiotics may shorten the length and severity of diarrhea, oral rehydration remains the primary approach in managing secretory diarrhea. Existing treatments mostly depend on reconstituting medicines with water that is often contaminated which can be an unresolved problem in the developing world. Standard treatments for secretory diarrhea also include drugs that decrease intestinal motility. This approach is less than ideal because in cases where infection is the cause, this can increase the incidence of bacterial translocation and the potential for sepsis. Our goal is to develop a safe, effective, easy-to-use, and inexpensive treatment to reduce fluid loss in secretory diarrhea. We have developed Rx100, which is a metabolically stable analog of lysophosphatidic acid. We tested the hypothesis that Rx100, similarly to lysophosphatidic acid, inhibits the activation of the cystic fibrosis transmembrane regulator Cl− channel and also reduces barrier permeability resulting in the decrease of fluid loss in multiple etiologies of secretory diarrhea. Here we have established the bioavailability and efficacy of Rx100 in cholera toxin-induced secretory diarrhea models. We have demonstrated the feasibility of Rx100 as an effective treatment for Citrobacter rodentium infection-induced secretory diarrhea. Using both the open- and closed-loop mouse models, we have optimized the dosing regimen and time line of delivery for Rx100 via oral and parenteral delivery. Impact statement A critical barrier in treating diarrheal disease is easy-to-use effective treatments. Rx100 is a first in class, novel small molecule that has shown efficacy after both subcutaneous and oral administration in a mouse cholera-toxin- and Citrobacter rodentium infection-induced diarrhea models. Our findings indicate that Rx100 a metabolically stable analog of the lipid mediator lysophosphatidic acid blocks activation of CFTR-mediated secretion responsible for fluid discharge in secretory diarrhea. Rx100 represents a new treatment modality which does not directly block CFTR but attenuates its activation by bacterial toxins. Our results provide proof-of-principle that Rx100 can be developed for use as an effective oral or injectable easy-to-use drug for secretory diarrhea which could significantly improve care by eliminating the need for severely ill patients to regularly consume large quantities of oral rehydration therapies and offering options for pediatric patients.

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Are oral rehydration solutions optimized for treating diarrhea?

Nutrition and Health ◽

10.1177/0260106021991641 ◽

2021 ◽

pp. 026010602199164

Author(s):

Samuel N Cheuvront ◽

Robert W Kenefick ◽

Laura Luque ◽

Katherine M Mitchell ◽

Sadasivan Vidyasagar

Keyword(s):

Water Absorption ◽

Intestinal Absorption ◽

Turning Point ◽

Oral Rehydration Solution ◽

Salt Water ◽

Food Science ◽

Oral Rehydration ◽

Rehydration Solutions ◽

Rehydration Solution ◽

Stool Volume

Background: A historical turning point occurred in the treatment of diarrhea when it was discovered that glucose could enhance intestinal sodium and water absorption. Adding glucose to salt water (oral rehydration solution, ORS) more efficiently replaced intestinal water and salt losses. Aim: Provide a novel hypothesis to explain why mainstream use of ORS has been strongly recommended, but weakly adopted. Methods: Traditional (absorptive) and novel (secretory) physiological functions of glucose in an ORS were reviewed. Results: Small amounts of glucose can stimulate both intestinal absorption and secretion. Glucose can exacerbate a net secretory state and may aggravate pathogen-induced diarrhea, particularly for pathogens that affect glucose transport. Conclusion: A hypothesis is made to explain why glucose-based ORS does not appreciably reduce diarrheal stool volume and why modern food science initiatives should focus on ORS formulations that replace water and electrolytes while also reducing stool volume and duration of diarrhea.

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78. TOWARD A SUPER-ORAL REHYDRATION SOLUTION (ORS): ENHANCEMENT OF INTESTINAL WATER ABSORPTION BY A POLY-NUTRIENT SOLUTION

Pediatric Research ◽

10.1203/00006450-198707000-00099 ◽

1987 ◽

Vol 22 (1) ◽

pp. 109-109

Author(s):

A Nocerlno ◽

M Migliavacca ◽

A Fasano ◽

C Verqa ◽

A Ferrara ◽

...

Keyword(s):

Water Absorption ◽

Nutrient Solution ◽

Oral Rehydration Solution ◽

Oral Rehydration ◽

Rehydration Solution

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Glucose Polymer in the Fluid Therapy of Acute Diarrhoea: Studies in a Model of Rotavirus Infection in Neonatal Rats

Clinical Science ◽

10.1042/cs0860469 ◽

1994 ◽

Vol 86 (4) ◽

pp. 469-477 ◽

Cited By ~ 7

Author(s):

A. V. Thillainayagam ◽

J. A. Dias ◽

A. F. M. Salim ◽

F. H. Mourad ◽

M. L. Clark ◽

...

Keyword(s):

Water Absorption ◽

Polymer Solutions ◽

Acute Diarrhoea ◽

Optimal Size ◽

Neonatal Rats ◽

Rotavirus Infection ◽

Oral Rehydration ◽

Rehydration Solutions ◽

All Solutions ◽

Glucose Polymer

1. Unlike standard glucose-electrolyte oral rehydration solutions, solutions containing polymeric glucose as substrate can significantly reduce stool output, duration of diarrhoea and total oral rehydration solution requirements. However, neither the underlying mechanisms nor the optimal size and concentration of glucose polymer has been defined. 2. We have used a model of rotavirus diarrhoea in neonatal rats to compare the effects on water and solute absorption of varying the concentration of a glucose polymer (mean chain length five glucose residues) in experimental oral rehydration solutions. Three polymer (P) solutions were compared with solutions of identical electrolyte content (mmol/l: sodium, 60; potassium, 20; chloride, 60; citrate, 10) containing equivalent amounts of free glucose (G) as substrate by perfusion of the entire small intestine in situ. The polymer (9, 18, 36 mmol/l; 159, 168, 186 mosmol/kg, respectively) and the monomer (45, 90, 180 mmol/l; 195, 240 320 mosmol/kg) solutions were perfused in normal and rotavirus-infected neonatal rats. 3. In normal intestine polymer solutions promoted greater water absorption [P9, mean 291.4 (SEM 16.4); P18, 331.9(13.1); P36, 284.3 (11.8) μl mi−1 g−1] than their equivalent monomer solutions [G45, 220.8 (8.4); G90, 240 (21); G180,79.4 (145) μl min− g−1; P < 0.02]. In rotavirus-infected intestine, water absorption from all solutions declined, but the fall was much less pronounced from the polymer solutions [P9, 232.8 (6); P18, 277.2 (20.5); P36, 166 (18.2) μl min−1 g−1] than from their monomeric counterparts [G45, 116.7 (25.5); G90, 68.7 (12.4); G180, 21 (11.6) μl min−1 g−1; P < 0.005]. 4. In both the normal net absorptive state and the net secretory state induced by rotavirus infection, there was a striking inverse correlation between net water absorption and perfusate osmolality (r = −0.94 and r = −0.88, respectively; P < 0.05). In rotavirus-infected intestine, increasing the polymer concentration from 18 to 36 mmol/l resulted in a relative fall in water absorption (P < 0.01). The hypertonic solution G180 was associated with the lowest water absorption (P < 0.01). None of the solutions was able to reverse rotavirus-induced net secretion of sodium, which was similar from all solutions, whether polymer- or monomer-based. 5. These results (i) emphasize the pre-eminence of hypotonicity among the factors promoting water absorption from polymer-based oral rehydration solutions in acute diarrhoea, (ii) confirm the adverse consequence of raising substrate concentration (whether polymer or monomer) beyond certain limits and (iii) indicate that the concentration of this glucose polymer yielding the optimum compromise between substrate availability and low osmolality may be approximately 9–18 mmol/l.

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Characterization of Fluorescent Chimeras of Cholera Toxin and Escherichia coli Heat-Labile Enterotoxins Produced by Use of the Twin Arginine Translocation System

Infection and Immunity ◽

10.1128/iai.73.6.3627-3635.2005 ◽

2005 ◽

Vol 73 (6) ◽

pp. 3627-3635 ◽

Cited By ~ 17

Author(s):

Juliette K. Tinker ◽

Jarrod L. Erbe ◽

Randall K. Holmes

Keyword(s):

Escherichia Coli ◽

Cholera Toxin ◽

Fusion Proteins ◽

Cell Biology ◽

Fluorescent Protein ◽

Cultured Cells ◽

Secretory Diarrhea ◽

E Coli ◽

Twin Arginine Translocation ◽

Heat Labile

ABSTRACT Cholera toxin (CT) is an AB5 toxin responsible for the profuse secretory diarrhea resulting from Vibrio cholerae infection. CT consists of a pentameric, receptor-binding B subunit (CTB) and a monomeric A subunit (CTA) that has latent enzymatic activity. In addition to its enterotoxicity, CT has potent mucosal adjuvant activity and can also function as a carrier molecule with many potential applications in cell biology. In earlier studies, the toxic CTA1 domain was replaced by several other antigenic protein domains to produce holotoxin-like chimeras for use as potential mucosal vaccines. In the present study we utilized the twin arginine translocation (tat) system to produce fluorescent CT chimeras, as well as fluorescent chimeras of Escherichia coli heat-labile toxins LTI and LTIIb. Fusion proteins containing either green fluorescent protein (GFP) or monomeric red fluorescent protein (mRFP) and the A2 domain of CT, LTI, or LTIIb were transported to the periplasm of E. coli by the tat system, and the corresponding B polypeptides of CT, LTI, and LTIIb were transported to the periplasm by the sec system. The fluorescent fusion proteins were shown to assemble spontaneously and efficiently with the corresponding B polypeptides in the periplasm to form chimeric holotoxin-like molecules, and these chimeras bound to and entered cultured cells in a manner similar to native CT, LTI, or LTIIb. The GFP and mRFP derivatives of CT, LT, and LTIIb developed here are useful tools for studies on the cell biology of trafficking of the CT/LT family of bacterial enterotoxins. In addition, these constructs provide proof in principle for the development of novel chimeric CT-like or LT-like vaccine candidates containing CTA2 fusion proteins that cannot be delivered to the periplasm of E. coli by use of the sec secretion pathway.

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Evaluation of the Effects of Varying Solute Content on the Efficacy of Oral Rehydration Solutions in a Rat Model of Secretory Diarrhoea

Journal of Pediatric Gastroenterology and Nutrition ◽

10.1097/00005176-199405000-00009 ◽

1994 ◽

Vol 18 (4) ◽

pp. 457-460 ◽

Cited By ~ 9

Author(s):

G. V. Pillai ◽

M. J. Brueton ◽

D. Burston ◽

B. K. Sandhu

Keyword(s):

Rat Model ◽

Solute Content ◽

Oral Rehydration ◽

Rehydration Solutions ◽

Secretory Diarrhoea

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Use of the hypoosmolar oral rehydration mixture in the comprehensive therapy of secretory diarrhea

ACTUAL INFECTOLOGY ◽

10.22141/2312-413x.5.4.2017.115731 ◽

2017 ◽

Vol 5 (4) ◽

pp. 182-184

Author(s):

V.R. Gaydey ◽

A.I. Savchuk ◽

N.V. Movlyanova ◽

S.I. Doan

Keyword(s):

Secretory Diarrhea ◽

Oral Rehydration ◽

Comprehensive Therapy

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Caco-2/HT29-MTX co-cultured cells as a model for studying physiological properties and toxin-induced effects on intestinal cells

PLoS ONE ◽

10.1371/journal.pone.0257824 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0257824

Author(s):

Pascal Hoffmann ◽

Marion Burmester ◽

Marion Langeheine ◽

Ralph Brehm ◽

Michael T. Empl ◽

...

Keyword(s):

Cholera Toxin ◽

Short Circuit ◽

Functional Model ◽

Chloride Secretion ◽

Bacterial Toxins ◽

Secretory Diarrhea ◽

Laboratory Animals ◽

Structural Level ◽

Heat Labile ◽

Physiological Properties

Infectious gastrointestinal diseases are frequently caused by toxins secreted by pathogens which may impair physiological functions of the intestines, for instance by cholera toxin or by heat-labile enterotoxin. To obtain a functional model of the human intestinal epithelium for studying toxin-induced disease mechanisms, differentiated enterocyte-like Caco-2 cells were co-cultured with goblet cell-like HT29-MTX cells. These co-cultures formed a functional epithelial barrier, as characterized by a high electrical resistance and the presence of physiological intestinal properties such as glucose transport and chloride secretion which could be demonstrated electrophysiologically and by measuring protein expression. When the tissues were exposed to cholera toxin or heat-labile enterotoxin in the Ussing chamber, cholera toxin incubation resulted in an increase in short-circuit currents, indicating an increase in apical chloride secretion. This is in line with typical cholera toxin-induced secretory diarrhea in humans, while heat-labile enterotoxin only showed an increase in short-circuit-current in Caco-2 cells. This study characterizes for the first time the simultaneous measurement of physiological properties on a functional and structural level combined with the epithelial responses to bacterial toxins. In conclusion, using this model, physiological responses of the intestine to bacterial toxins can be investigated and characterized. Therefore, this model can serve as an alternative to the use of laboratory animals for characterizing pathophysiological mechanisms of enterotoxins at the intestinal level.

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