Novel targets for the pharmacotherapy of diarrhoea: a view for the millennium

Evaluation of the Effect of Limosilactobacillus fermentum CECT5716 on Gastrointestinal Infections in Infants: A Systematic Review and Meta-Analysis

Reducing the incidence of gastrointestinal infections (GIs) that occur at early stages to mitigate hospitalizations and treatments with adverse effects is a promising strategy for providing well-being to infants and their families. This systematic review and meta-analysis explores whether the early administration of Limosilactobacillus fermentum CECT5716 might be effective as a preventive therapy for GIs. We reviewed the literature to identify randomized controlled trials (RCTs) investigating the effectiveness of milk formulas supplemented with L. fermentum CECT5716 administered to infants at early stages to reduce the incidence of GIs. The MEDLINE (via PubMed), Web of Science (WoS), and Cochrane Central Register of Controlled Trials (via CENTRAL) databases were searched up to 15 June 2021. GI data from the included studies were synthesized in a random-effects model. Three RCTs were finally selected including 435 infants. There was a significant reduction in the incidence rate of GIs for those receiving L. fermentum CECT5716 compared with those receiving placebo (IRR: 0.52, 95% CI: 0.36-0.74, p = 0.0004). Heterogeneity between studies was moderate (I² = 54.5%). Based on the present systematic review and meta-analysis, the administration of L. fermentum CECT5716 at doses from 1 × 10⁹ to 8.4 × 10⁸ cfu/day in milk formulas may prevent GIs in infants up to 12 months old. Longer-term studies including a higher number of infants are needed to determine whether the use of this probiotic during the early stages of life is an efficient way to reduce the incidence of GIs.

Drugs in Focus: The Use of Racecadotril in Paediatric Gastrointestinal Disease

Acute diarrhoea is a leading cause of morbidity and mortality in the paediatric population. Racecadotril is an antisecretory drug recommended as an adjuvant antidiarrhoeal treatment.In the small bowel, the enzyme neutral endopeptidase (NEP) inhibits the action of enkephalins, which prevent water and electrolyte hypersecretion. By inhibiting NEP, racecadotril allows enkephalins to exhibit their antisecretory effects. Consequently, racecadotril reduces the secretion of water and electrolytes in the small intestine, without having an effect on intestinal motility. No serious adverse events related to racecadotril have been reported.Racecadotril has proven its efficacy as an adjuvant antidiarrhoeal drug with a good safety profile. Its addition to oral rehydration solution (ORS) appears clinically beneficial and potentially leads to health care savings.

Gelatin tannate for acute diarrhoea and gastroenteritis in children: a systematic review and meta-analysis

OBJECTIVE

To determine the effectiveness and safety of gelatin tannate (GT) for reducing the duration of the acute diarrhoea and gastroenteritis (ADG) in children.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, CINAHL, Cochrane Central Register of Controlled Trials, LILACS and grey literature, published from inception to October 2018. No language restrictions.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials in children with ADG, comparing GT with placebo.

RESULTS

Of 797 titles identified, we included three studies (276 children). We performed a random effects model meta-analysis for the main outcome (diarrhoea duration). We did not find significant differences between GT and placebo for diarrhoea duration (mean difference (MD)=-15.85 hours; 95% CI -42.24 to 14.82, I²=92%; three studies), stool frequency at day 2 (MD=0.11 stools/day; 95% CI -0.39 to 0.62: I²=26%; two studies), diarrhoea at day 3 (risk ratio [RR]=0.46; 95% CI 0.06 to 3.47: I²=73%; two studies), vomiting (RR=1.31; 95% CI 0.95 to 1.80: I²=0%; two studies) or adverse events (RR=0.86; 95% CI 0.27 to 2.66: I²=0%; two studies). Most common adverse events included abdominal pain and nausea.

CONCLUSION

The effect of GT was no different to placebo for mean diarrhoea duration (low certainty on the evidence) and stool frequency at day 2 (high certainty) and for the presence of diarrhoea at day 3 (very low certainty) of vomiting (moderate certainty) and of adverse events (low certainty).

PROSPERO REGISTRATION NUMBER

CRD42018087902.

In Silico Screening and Analysis of Broad-Spectrum Molecular Targets and Lead Compounds for Diarrhea Therapy

Diarrhoeal disease kills about 1.5 million human beings per year across the continents. The enterotoxigenic Escherichia coli (ETEC) pathotype has been noted as a major cause of diarrheal disease in human and livestock. The aim of this study is to identify broad-spectrum molecular targets in bacteria and broad-spectrum lead compounds (functional inhibitors) with high efficacy and no significant adverse implication on human systems, in relevance to diarrhea therapy through computational approaches which include phylogenetics, target prediction, molecular docking, and molecular flexibility dynamic simulations. Three molecular target genes, murA, dxr, and DnaE, which code for uridine diphosphate-N-acetylglucosamine-1-carboxyvinyltransferase, 1-deoxy-D-xylulose-5-phosphate reductoisomerase, and deoxyribonucleic acid polymerase III alpha subunit, respectively, were found to be highly conserved in 7 diarrhea-causing microbes. In addition, 21 potential compounds identified showed varied degree of affinity to these enzymes. At free energy cutoff of -8.0 kcal/mol, the highest effective molecular target was DNA polymerase III alpha subunit (PDB ID: 4JOM) followed by UDP-N-acetylglucosamine-1-carboxyvinyltransferase (PDB ID: 5UJS), and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (PDB ID: 1ONN), while the highest effective lead compound was N-coeleneterazine followed by amphotericin B, MMV010576, MMV687800, MMV028694, azithromycin, and diphenoxylate. The flexibility dynamics of DNA polymerase III alpha subunit unraveled the atomic fluctuation which potentially implicated Asp593 as unstable active site amino acid residue. In conclusion, bacteria DnaE gene or its protein is a highly promising molecular target for the next generation of antibacterial drugs of the class of N-coeleneterazine.

Probiotic Lactobacillus casei: Effective for Managing Childhood Diarrhea by Altering Gut Microbiota and Attenuating Fecal Inflammatory Markers

Background: Acute diarrhea is a major cause of childhood morbidity and an economic burden for families. The aim of this study is to explore the effect of probiotics on clinical symptoms, intestinal microbiota, and inflammatory markers during childhood diarrhea. Methods: Children (n = 81) aged six months to six years (mean age 2.31 years) hospitalized for acute diarrhea were randomized to receive probiotics (Lactobacillus casei variety rhamnosus; n = 42) or no probiotics (n = 39) orally twice daily for seven days. Feces samples were also collected to evaluate microbial content using a traditional agar plate and next-generation sequencing. Immunoglobulin A (IgA), lactoferrin, and calprotectin were determined by enzyme-linked immunosorbent assay (ELISA) and compared in different groups. Other clinical symptoms or signs, including fever, vomiting, diarrhea, abdominal pain, bloated abdomen, daily intake, appetite, and body weight were also assessed. Results: Data were collected from 81 individuals across three different time points. Total fecal IgA levels in fecal extracts of the probiotics group were higher than those in the control group, reaching statistical significance (p < 0.05). Concentrations of fecal lactoferrin and calprotectin were significantly downregulated in patients with probiotic Lactobacillus casei variety rhamnosus (Lc) consumption compared to those of the control (p < 0.05). Probiotic Lc administration may be beneficial for gut-microbiota modulation, as shown by the data collected at one week after enrollment. Counts of Bifidobacteria and Lactobacillus species were elevated in stool culture of the probiotic group. Appetite and oral intake, body-weight gain, abdominal pain, bloating, as well as bowel habits (diarrhea) were much better in children receiving probiotics compared with those in the control group. Conclusion: Fecal IgA increased during acute diarrhea under Lc treatment; in contrast, fecal lactoferrin and calprotectin were downregulated during acute diarrhea under Lc treatment. Probiotic Lc may be a useful supplement for application in children during acute diarrhea to reduce clinical severity and intestinal inflammatory reaction.

Gelatin Tannate for Acute Childhood Gastroenteritis: A Randomized, Single-Blind Controlled Trial

BACKGROUND

Oral rehydration therapy is the recommended treatment for acute childhood gastroenteritis. The aim of this study was to assess the efficacy and safety of gelatin tannate plus oral rehydration compared with oral rehydration alone.

METHODS

We conducted a multicenter, parallel, randomized, controlled, single-blind, prospective, open-label trial. A central randomization center used computer generated tables to allocate treatments. The study was performed in two medical centers in Italy. Sixty patients 3-72 months of age with acute gastroenteritis were recruited (median age 18 months; age range 3-66 months): 29 received an oral rehydration solution (ORS) and 31 an ORS plus gelatin tannate (ORS + G). The primary outcome was the number of bowel movements 48 and 72 h after initiating treatment. Secondary outcomes were: duration of diarrhea, stool characteristics and adverse events.

RESULTS

No patient was lost at follow-up. No significant difference in the number of bowel movements after 48 h was reported (2.7 ± 1.3 ORS + G; 3.2 ± 0.8 ORS; p = 0.06), although the ORS + G group showed a significant improvement in stool consistency (3.7 ± 1.0 vs. 4.3 ± 0.8; p = 0.005). At 72 h, a significant reduction in bowel movements was reported in the ORS + G group compared with the ORS group (1.0 ± 1.4 vs. 2.0 ± 1.7; p = 0.01). Mean duration of diarrhea was significantly lower in the ORS + G group than in the ORS only group (76.8 ± 19.2 vs. 108 ± 24.0 h; p < 0.0001). No adverse events were reported.

CONCLUSIONS

Gelatin tannate added to oral rehydration in children with acute diarrhea was associated with a significant decrease in bowel movements at 72 h, with an early improvement in the stool consistency and shorter disease duration.

CLINICAL TRIAL REGISTRATION

NCT02644200-Gelatin Tannate as Treatment for Acute Childhood Gastroenteritis ( https://www.clinicaltrials.gov ).

Antidiarrhoeal, antimicrobial and antioxidant effects of myrtle berries (Myrtus communis L.) seeds extract

OBJECTIVES

The present study was carried out to determine the antidiarrheal effects of myrtle (Myrtus communis L.) berries seeds aqueous extract (MBSAE) from Tunisia as well as the involvement of its antimicrobial and antioxidant properties in such protection.

METHODS

Adult male wistar rats were used and divided into six groups of ten each: control, Castor oil, Castor oil + Loperamide and Castor oil + various doses of MBSAE. Animals were per orally (p.o.) pre-treated with MBSAE for one hour and intoxicated by castor oil acute oral administration.

KEY FINDINGS

Our results demonstrated that the MBSAE is rich in total and condensed tannins and exhibited a broad spectrum of antibacterial activity. In vivo, we found that MBSAE administration induced a significant dose-dependent protection against diarrhoea and intestinal fluid accumulation. Castor oil-induced intestinal hypersecretion was accompanied by an oxidative stress status in the intestine. More importantly, we showed that acute diarrhoea was accompanied by an increase in intestinal mucosa hydrogen peroxide (H2 O2 ), calcium and free iron levels while MBSAE pre-treatment reversed all castor oil-induced intracellular mediators disturbances.

CONCLUSIONS

We suggest that MBSAE had a potent protective effects against castor oil-induced acute diarrhoea due in part to its antioxidant and antimicrobial properties.

In Vivo Effects of Cagaita (Eugenia dysenterica, DC.) Leaf Extracts on Diarrhea Treatment

Eugenia dysenterica is a plant typically found in the Cerrado biome and commonly used in popular medicine due to its pharmacological properties, which include antidiarrheal, skin healing, and antimicrobial activities. The effects of ethanolic extract, aqueous extract and infusion of E. dysenterica leaves on intestinal motility and antidiarrheal activity were evaluated using ricin oil-induced diarrhea in rats. At doses of 400 and 800 mg·Kg⁻¹, the ethanolic extract decreased intestinal motility while the other extracts showed no significant effects. Moreover, serum levels of chloride, magnesium, and phosphorus were also measured in rats. Histopathologic and enzymatic analyses were also performed to investigate any toxic effect. Animals treated with infusion, ethanolic extract, ricin oil, and loperamide presented morphological alterations in the small intestine, such as mucosa lesion, epithelial layer damage, and partial loss and/or morphological change of villi. Furthermore, the liver showed congestion and hydropic degeneration. Serum levels of alanine aminotransferase increased significantly in all treatments, but none rose above reference values. In summary, our results suggest that compounds present in leaves of E. dysenterica may have therapeutic benefits on recovery from diarrhea despite their toxic effects.

Use of racecadotril as outpatient treatment for acute gastroenteritis: a prospective, randomized, parallel study

OBJECTIVE

To compare the efficacy of therapy with racecadotril plus oral rehydration versus oral rehydration alone in children with gastroenteritis in an outpatient setting care.

STUDY DESIGN

Prospective, randomized, open and parallel study performed in a Pediatric Emergency Service of a tertiary care hospital. The study included 189 patients, ages 3 to 36 months, with acute gastroenteritis: 94 were administered an oral rehydration solution (OR), 94 received oral rehydration solution plus racecadotril (OR + R). The principal variable studied was the number of bowel movements in 48 hours after initiating treatment.

RESULTS

The groups were comparable clinically and epidemiologically at enrollment. No significant differences were found in the number of bowel movements between the 2 groups 48 hours after initiating treatment (4.1 +/- 2.7 bowel movements in the OR group vs 3.8 +/- 2.4 bowel movements in the OR + R group). No differences were found in the average duration of gastroenteritis (4.7 +/- 2.2 days in the OR group, 4.0 +/- 2.1 days in the OR + R group; P = .15). The incidence of adverse events was similar in both groups (19 patients [20.2%] in the OR group, 18 patients [19.1%] in the OR + R group).

CONCLUSIONS

In our study group, the use of racecadotril did not improve the symptoms of diarrhea compared with standard rehydration therapy.

Probiotics for treatment of acute diarrhoea in children: randomised clinical trial of five different preparations

OBJECTIVE

To compare the efficacy of five probiotic preparations recommended to parents in the treatment of acute diarrhoea in children. Design Randomised controlled clinical trial in collaboration with family paediatricians over 12 months.

SETTING

Primary care.

PARTICIPANTS

Children aged 3-36 months visiting a family paediatrician for acute diarrhoea.

INTERVENTION

Children's parents were randomly assigned to receive written instructions to purchase a specific probiotic product: oral rehydration solution (control group); Lactobacillus rhamnosus strain GG; Saccharomyces boulardii; Bacillus clausii; mix of L delbrueckii var bulgaricus, Streptococcus thermophilus, L acidophilus, and Bifidobacterium bifidum; or Enterococcus faecium SF68.

MAIN OUTCOME MEASURES

Primary outcomes were duration of diarrhoea and daily number and consistency of stools. Secondary outcomes were duration of vomiting and fever and rate of admission to hospital. Safety and tolerance were also recorded.

RESULTS

571 children were allocated to intervention. Median duration of diarrhoea was significantly shorter (P<0.001) in children who received L rhamnosus strain GG (78.5 hours) and the mix of four bacterial strains (70.0 hours) than in children who received oral rehydration solution alone (115.0 hours). One day after the first probiotic administration, the daily number of stools was significantly lower (P<0.001) in children who received L rhamnosus strain GG and in those who received the probiotic mix than in the other groups. The remaining preparations did not affect primary outcomes. Secondary outcomes were similar in all groups.

CONCLUSIONS

Not all commercially available probiotic preparations are effective in children with acute diarrhoea. Paediatricians should choose bacterial preparations based on effectiveness data.

TRIAL REGISTRATION NUMBER

Current Controlled Trials ISRCTN56067537 [controlled-trials.com].

Cyanobacterial lipopolysaccharides and human health - a review

Cyanobacterial lipopolysaccharide/s (LPS) are frequently cited in the cyanobacteria literature as toxins responsible for a variety of heath effects in humans, from skin rashes to gastrointestinal, respiratory and allergic reactions. The attribution of toxic properties to cyanobacterial LPS dates from the 1970s, when it was thought that lipid A, the toxic moiety of LPS, was structurally and functionally conserved across all Gram-negative bacteria. However, more recent research has shown that this is not the case, and lipid A structures are now known to be very different, expressing properties ranging from LPS agonists, through weak endotoxicity to LPS antagonists. Although cyanobacterial LPS is widely cited as a putative toxin, most of the small number of formal research reports describe cyanobacterial LPS as weakly toxic compared to LPS from the Enterobacteriaceae. We systematically reviewed the literature on cyanobacterial LPS, and also examined the much lager body of literature relating to heterotrophic bacterial LPS and the atypical lipid A structures of some photosynthetic bacteria. While the literature on the biological activity of heterotrophic bacterial LPS is overwhelmingly large and therefore difficult to review for the purposes of exclusion, we were unable to find a convincing body of evidence to suggest that heterotrophic bacterial LPS, in the absence of other virulence factors, is responsible for acute gastrointestinal, dermatological or allergic reactions via natural exposure routes in humans. There is a danger that initial speculation about cyanobacterial LPS may evolve into orthodoxy without basis in research findings. No cyanobacterial lipid A structures have been described and published to date, so a recommendation is made that cyanobacteriologists should not continue to attribute such a diverse range of clinical symptoms to cyanobacterial LPS without research confirmation.

Modulation of gut physiology through enteric toxins

Diarrheal diseases caused by microorganisms and their toxins are a major cause of mortality and morbidity throughout the world. Acute diarrhea is mainly caused due to increased intestinal secretion, commonly as a result of infection with enterotoxin producing organisms (enterotoxigenic Escherichia coli, Vibrio cholera) or due to decreased intestinal absorption from infection with organisms that damage the intestinal epithelium (enteropathogenic E. coli sp., Shigella sp., Salmonella sp.) The studies of the impact of enteric pathogens and their virulence factors exert their effect by producing toxins, called bacterial toxins. The protein toxins are produced by diverse group of bacteria. Most of the bacterial toxins exert their effect through involvement of ADP-ribosylation proteins; otherwise essential for several cellular functions while other toxins involve guanylate cyclase systems or calcium and protein kinases for their ultimate action.

Modulation of human enteric epithelial barrier and ion transport function by Peyer’s patch lymphocytes

AIM: To investigate the role of Peyer’s patch lymphocytes in the regulation of enteric epithelial barrier and ion transport function in homeostasis and host defense.

METHODS: Mouse Peyer’s patch lymphocytes were co-cultured with human intestinal epithelial cell line Caco-2 either in the mixed or separated (isolated but permeable compartments) culture configuration. Barrier and transport functions of the Caco-2 epithelial monolayers were measured with short-circuit current (Isc) technique. Release of cytokines was measured by enzyme-linked immunosorbent assay (ELISA) and cytokine mRNA expression was analyzed by semi-quantitative RT-PCR. Barrier and iontransport functions of both culture conditions following exposure to Shigella lipopolysaccharide (LPS) were also examined.

RESULTS: The transepithelial resistance (TER) of the epithelial monolayers co-cultured with Peyer’s patch lymphocytes was maintained whereas that of the Caco-2 monolayers alone significantly decreased after eight days in culture. The forskolin-induced anion secretion, in either absence or presence of LPS, was significantly suppressed in the both co-cultures as compared with the Caco-2 cells alone. Furthermore, only the mixed co-culture condition induced the expression and release of mIL-6 from Peyer’s patch lymphocytes, which could be further enhanced by LPS. However, both co-culture conditions suppressed expression and release of epithelial hIL-8 under the unstimulated conditions, while the treatment with LPS stimulated their hIL-8 expression and release.

CONCLUSION: Peyer’s patch lymphocytes may modulate intestinal epithelial barrier and ion transport function in homeostasis and host defense via cell-cell contact and cytokine signaling.

Effects of TAK-637 on NK(1) receptor-mediated mechanisms regulating colonic secretion

This study investigates the effect of a selective NK(1) receptor antagonist TAK-637 on enteric mechanisms involved in regulation of epithelial secretion in the colon. Mucosal sheets isolated from guinea-pig colon were placed in modified Ussing chambers and the net active transport of electrolytes was measured as short-circuit current (Isc). GR-73632, a selective NK(1) receptor agonist, induced an increase in basal Isc, which was inhibited by TAK-637 (IC(50) of 21 nM). The increase in Isc induced by GR-73632 was significantly attenuated by tetrodotoxin (TTX, 1 microM), indicating that TAK-637 inhibits neuronal NK(1) receptors. Moreover, TAK-637 reduced the TTX-resistant component of the response to GR-73632 suggesting that NK(1) receptors expressed by epithelial cells are inhibited by TAK-637. In separate experiments, TAK-637 partially inhibited the submaximal Isc induced by electrical field stimulation (EFS, 0.5 ms, 15 Hz) of enteric nerves or by activation of primary afferent fibers using capsaicin (50 microM). TAK-637 had no significant effect on the basal Isc or on responses induced by neurokinin A (NKA), senktide, or forskolin. The results imply that inhibition of peripheral NK(1) receptors may reduce autonomic epithelial secretion in response to activation of autonomic secretomotor pathways, while having no significant effect on basal epithelial transport.

Rotavirus infection stimulates the Cl- reabsorption process across the intestinal brush-border membrane of young rabbits

Rotavirus is a major cause of infantile gastroenteritis worldwide. However, the mechanisms underlying fluid and electrolyte secretion associated with diarrhea remain largely unknown. We investigated the hypothesis that loss of Cl(-) into the luminal contents during rotavirus infection may be caused by a dysfunction in the chloride absorptive capacity across the intestinal brush-border membrane (BBM). The luminal Cl(-) concentrations in the entire small intestine of young rabbits infected with lapine rotavirus decreased at 1 and 2 days postinfection (dpi), indicating net Cl(-) absorption. At 7 dpi, luminal Cl(-) concentrations were slightly increased, indicating a moderate net Cl(-) secretion. By using a rapid filtration technique, (36)Cl uptake across BBM was quantified by modulating the alkali-metal ion, electrical, chloride, and/or proton gradients. Rotavirus infection caused an identical, 127% +/- 24% increase in all Cl(-) uptake activities (Cl(-)/H(+) symport, Cl(-) conductance, and Cl(-)/anion exchange) observed across the intestinal BBM. The rotavirus activating effects on the symporter started at 1 dpi and persisted up to 7 dpi. Kinetic analyses revealed that rotavirus selectively affected the capacity parameter characterizing the symporter. We report the novel observation that rotavirus infection stimulated the Cl(-) reabsorption process across the intestinal BBM. We propose that the massive Cl(-) reabsorption in villi could partly overwhelm chloride secretion in crypt cells, which possibly increases during rotavirus diarrhea, the resulting imbalance leading to a moderate net chloride secretion.

New developments in the understanding of cholera

Recent advances in prevention and treatment of cholera have occurred in the areas of vaccine testing, modifications of oral-rehydration solutions (ORS), and antimicrobial treatment. Oral vaccines consisting of killed whole bacterial cells (WC) with and without the B-subunit of cholera toxin (BS) were shown to be effective in large trials in Bangladesh, Peru, and Vietnam. However, the trials did not resolve whether two or three doses of vaccine are required and whether BS adds significantly to the immune protection of WC. Live, attenuated bacterial vaccines that are immunogenic and have been shown protective in human volunteer studies are candidates for future field trials. Rehydration of patients is a life- saving effort. The best ORS contains rice powder in place of glucose, and solutions with reduced osmolarity (245 mOsm/L, sodium 75 mEq/L) are as effective as standard ORS. Ciprofloxacin in a single dose is effective in adults, and erythromycin or ampicillin in multiple doses is effective in children.