Preclinical and clinical pharmacology of biotherapeutic agents: Saccharomyces boulardii

Qiweibaizhu Decoction Treats Diarrheal Juvenile Rats by Modulating the Gut Microbiota, Short-Chain Fatty Acids, and the Mucus Barrier

Background

Qiweibaizhu decoction (QBD), a classic Chinese herbal formula, has been widely used for treating diarrhea in infants and children with spleen deficiency syndrome for centuries, but its mechanism of action remains unclear. The gut microbiota, short-chain fatty acids (SCFAs), and intestinal mucus are closely associated with diarrhea.

Methods

In this study, the composition of the gut microbiota in diarrheal rats was analyzed by 16S rDNA amplicon sequencing. The concentrations of colon SCFAs were determined using gas chromatography-mass spectrometry (GC-MS). The expression of mucin 2 (MUC2) in the colon was detected by immunofluorescence.

Results

Diarrhea significantly changed the diversity and structure of the gut microbiota and disrupted the mucus barrier in juvenile rats. QBD did not significantly change the diversity and structure of the intestinal flora, but it enhanced the increasing tendencies of Verrucomicrobia and Akkermansia and decreased the abundance of Turicibacter (P=0.037) and Flavonifractor (P=0.043). QBD tends to repair the mucus layer and promote MUC2 expression in juvenile rats with diarrhea. Moreover, S. boulardii significantly increased the abundance of Parasutterella (P=0.043). In addition, QBD treatment tends to increase the propionic acid concentration during diarrhea, but its levels of acetic acid, propionic acid, butyric acid, and total SCFAs were lower than those in the S. boulardii group.

Conclusion

S. boulardii significantly increased the abundance of Parasutterella, leading to increased production of acetic acid, propionic acid, and butyric acid, consequently leading to alleviation of diarrhea. In comparison, QBD affected diarrhea via regulation of the intestinal flora, especially by increasing the abundance of Verrucomicrobia and Akkermansia, resulting in mucus barrier repair, protection of the intestines, and treatment of diarrhea.

Modulation of intestinal inflammation by yeasts and cell wall extracts: strain dependence and unexpected anti-inflammatory role of glucan fractions

Yeasts and their glycan components can have a beneficial or adverse effect on intestinal inflammation. Previous research has shown that the presence of Saccharomyces cerevisiae var. boulardii (Sb) reduces intestinal inflammation and colonization by Candida albicans. The aim of this study was to identify dietary yeasts, which have comparable effects to the anti-C. albicans and anti-inflammatory properties of Sb and to assess the capabilities of yeast cell wall components to modulate intestinal inflammation. Mice received a single oral challenge of C. albicans and were then given 1.5% dextran-sulphate-sodium (DSS) for 2 weeks followed by a 3-day restitution period. S. cerevisiae strains (Sb, Sc1 to Sc4), as well as mannoprotein (MP) and β-glucan crude fractions prepared from Sc2 and highly purified β-glucans prepared from C. albicans were used in this curative model, starting 3 days after C. albicans challenge. Mice were assessed for the clinical, histological and inflammatory responses related to DSS administration. Strain Sc1-1 gave the same level of protection against C. albicans as Sb when assessed by mortality, clinical scores, colonization levels, reduction of TNFα and increase in IL-10 transcription. When Sc1-1 was compared with the other S. cerevisiae strains, the preparation process had a strong influence on biological activity. Interestingly, some S. cerevisiae strains dramatically increased mortality and clinical scores. Strain Sc4 and MP fraction favoured C. albicans colonization and inflammation, whereas β-glucan fraction was protective against both. Surprisingly, purified β-glucans from C. albicans had the same protective effect. Thus, some yeasts appear to be strong modulators of intestinal inflammation. These effects are dependent on the strain, species, preparation process and cell wall fraction. It was striking that β-glucan fractions or pure β-glucans from C. albicans displayed the most potent anti-inflammatory effect in the DSS model.

Efficacy of probiotics and nutrients in functional gastrointestinal disorders: a preliminary clinical trial

The purpose of this study was to evaluate the efficacy and safety of commonly used probiotics and nutrients available for functional gastrointestinal disorders (FGID). Five different combinations of probiotics and nutrients, or placebo, were taken daily over 12 weeks. In this randomized controlled clinical trial, men and women 21 to 72 years of age with FGID symptoms of indigestion, bloating, and abdominal discomfort were assigned to one of six groups, 12 patients per group. Gastrointestinal Quality of Life Index (GIQLI) and visual analogue scale (VAS) for GI symptoms, SF-36, lactulose and mannitol test (LMT), and urine indican levels were evaluated. GIQLI, VAS scores, and LMT did not change significantly (P > 0.05). There were clinically notable improvements in two of the combination formulations. While the nonsignificant improvements in GI symptoms could suggest that combination probiotics and nutrients may be beneficial in conditions such as FGID, no conclusive evidence was found in this pilot trial. Further investigations to explore the findings are discussed.

Saccharomyces boulardii and infection due to Giardia lamblia

Therapy with metronidazole is the recommended option in giardiasis. However, some clinical trial reports suggest the appearance of drug resistance to explain therapeutic failure. Several investigations have been carried out on the effect of probiotic microorganisms for preventing or treating gastrointestinal diseases, but little is known about their efficacy against protozoal infections. The principal objective of our study was to evaluate the efficacy of Saccharomyces boulardii against Giardia lamblia infections. A double-blind, placebo-controlled study was carried out on adult patients with giardiasis. Group 1 (30 patients) included metronidazole 750 mg 3 times daily along with S. boulardii capsules (250 mg b.i.d. orally) for 10 d while group 2 (35 patients) was treated with metronidazole 750 mg 3 times daily and with empty capsules as placebo for 10 d. Patients were re-examined at 2 and 4 weeks after treatment, and stool examinations were performed. At week 2, G. lamblia cysts were detected in 6 cases (17.1%) of group 2 and none in group 1. At the end of the fourth week, presence of the cysts continued in the same 6 cases in group 2 (control group). These findings indicated that S. boulardii may be effective in treating giardiasis when combined with metronidazole therapy.

Effect of regular ingestion of Saccharomyces boulardii plus inulin or Lactobacillus acidophilus LB in children colonized by Helicobacter pylori

AIM

To evaluate the effect of a probiotic, Lactobacillus acidophilus LB (LB), or a synbiotic, Saccharomyces boulardii plus inulin (SbI), on Helicobacter pylori (Hp) colonization in children.

SUBJECTS AND METHODS

A clinical trial was carried out in a school from a low socio-economic area of Santiago. Two hundred and fifty-four asymptomatic children (8.40+/-1.62 y) were screened for Hp by the (13)C-Urea Breath Test ((13)C-UBT). Hp-positive children were randomly distributed into three groups to receive either antibiotic treatment (lanzoprazole, clarythromycin and amoxicillin) for 8 d, or SbI or LB daily for 8 wk. A second (13)C-UBT was carried out at this time. Spontaneous clearance was evaluated in the same way in 81 infected, untreated children. The differences in the delta(13)CO(2) over baseline values before and after treatments (?DOB) were evaluated.

RESULTS

182 subjects (71.7%) were colonized by Hp, and 141 of them completed their treatment (22.5% dropout). Hp was eradicated in 66%, 12% and 6.5% of the children from the Ab, SbI and LB groups, respectively, while no spontaneous clearance was observed in the children without treatment. A moderate but significant difference in ?DOB was detected in children receiving living SbI (-6.31; 95% CI: -11.84 to -0.79), but not in those receiving LB (+0.70; 95% CI: -5.84 to +7.24).

CONCLUSION

S. boulardii seems promising as an agent that interferes with Hp in colonized individuals. More studies are needed to confirm these results and to elucidate the mechanisms by which Sb inhibits Hp.

Saccharomyces boulardii inhibits water and electrolytes changes induced by castor oil in the rat colon

The biotherapeutic agent Saccharomyces boulardii has been shown to inhibit castor oil-induced diarrhoea in rats. The present study investigated the mechanism(s) of this antidiarrhoeal effect in terms of water and electrolyte (sodium, potassium and chloride) changes using two rat models. A single oral dose of S. boulardii of up to 12 x 10(10) CFU/kg of viable cells did not inhibit castor oil-induced fluid secretion in the enteropooling model. However, the yeast dose dependently reduced castor oil induced fluid secretion into the colon, with a significant protection at 12 x 10(10) CFU/kg. In this model, castor oil reversed net sodium and chloride absorption into net secretion, and increased net potassium secretion into the lumen. Single pre-treatment with S. boulardii at 4 and 12 x 10(10) CFU/kg dose dependently decreased these electrolyte changes. In conclusion, S. boulardii possesses potent anti-secretory properties versus water and electrolyte secretion induced by castor oil in the rat colon.

Inducible nitric oxide synthase involvement in the mechanism of action of Saccharomyces boulardii in castor oil-induced diarrhoea in rats

The biotherapeutic agent Saccharomyces boulardii has been shown to inhibit castor oil-induced diarrhoea in rats in a dose-response fashion, and one of the suggested mechanisms of action included involvement of the nitric oxide pathway. The present study was designed to address this mechanism of action by firstly measuring the effects of S. boulardii on the inducible nitric oxide synthase (iNOS) isoform activity in vitro. Second, the effects of S. boulardii on the increase in colonic citrulline level associated with castor oil treatment were examined. In vitro, S. boulardii showed a dose-dependent inhibition of iNOS activity with an IC50 of 0.89 mg/ml. In the rat diarrhoea model, the antidiarrhoeal effect of S. boulardii was confirmed using a single oral dose of 12 x 10(10) CFU/kg (viable cells). In this model, castor oil significantly elevated citrulline level from 2526+/-164 to 3501+/-193 nmol/g in the colon. When the rats were treated with the same antidiarrhoeal single dose of S. boulardii, no increase in citrulline level was observed. Moreover, the iNOS inhibitor 1400 W at 10 mg/kg and the inhibitor of iNOS expression dexamethasone at 1 mg/kg, administered subcutaneously, blocked the citrulline production induced by the laxative. Taken together, these findings confirm the involvement of inhibition of the inducible isoform of nitric oxide synthase in the mechanism of action of S. boulardii in diarrhoea.

In vitro screening of probiotic properties of Saccharomyces cerevisiae var. boulardii and food-borne Saccharomyces cerevisiae strains

The probiotic potential of 18 Saccharomyces cerevisiae strains used for production of foods or beverages or isolated from such, and eight strains of Saccharomyces cerevisiae var. boulardii, was investigated. All strains included were able to withstand pH 2.5 and 0.3% Oxgall. Adhesion to the nontumorigenic porcine jejunal epithelial cell line (IPEC-J2) was investigated by incorporation of 3H-methionine into the yeast cells and use of liquid scintillation counting. Only few of the food-borne S. cerevisiae strains exhibited noteworthy adhesiveness with the strongest levels of adhesion (13.6-16.8%) recorded for two isolates from blue veined cheeses. Merely 25% of the S. cerevisiae var. boulardii strains displayed good adhesive properties (16.2-28.0%). The expression of the proinflammatory cytokine IL-1alpha decreased strikingly in IPEC-J2 cells exposed to a Shiga-like toxin 2e producing Escherichia coli strain when the cells were pre- and coincubated with S. cerevisiae var. boulardii even though this yeast strain was low adhesive (5.4%), suggesting that adhesion is not a mandatory prerequisite for such a probiotic effect. A strain of S. cerevisiae isolated from West African sorghum beer exerted similar effects hence indicating that food-borne strains of S. cerevisiae may possess probiotic properties in spite of low adhesiveness.

The taxonomic position of Saccharomyces boulardii as evaluated by sequence analysis of the D1/D2 domain of 26S rDNA, the ITS1-5.8S rDNA-ITS2 region and the mitochondrial cytochrome-c oxidase II gene

A taxonomic study was carried out on eight strains of Saccharomyces boulardii. Morphological and physiological characteristics were consistent with those of Saccharomyces cerevisiae. Sequences of the D1/D2 domain of the 26S rDNA were identical for all strains examined and had a similarity value of 100% compared to sequences of the type strain of S. cerevisiae (CBS 1171T) and strain S288c. For all S. boulardii isolates was found the exact same ITS1-5.8S rDNA-ITS2 sequence, which displayed a close resemblance with the sequences published for S288c (99.9%), CBS 1171(T) (99.3%) and other S. cerevisiae strains. Sequence analysis of the mitochondrial cytochrome-c oxidase II gene (COX2) also resulted in identical sequences for the S. boulardii isolates and comparisons with available nucleotide sequences revealed close relatedness to strains of S. cerevisiae including S288c (99.5%) and CBS 1171(T) (96.6%). The electrophoretic karyotypes of the S. boulardii strains appeared quite uniform and although very typical of S. cerevisiae, they formed a cluster separate from strains of this species. The results of the present study strongly indicate a close relatedness of S. boulardii to S. cerevisiae and thereby support the recognition of S. boulardii as a member of S. cerevisiae and not as a separate species.

Acid tolerance and fecal recovery following oral administration of Saccharomyces cerevisiae

Probiotic microorganisms to be used as biotherapeutic agents have to resist the rigors of the upper human gastrointestinal tract. In this study we evaluated the acid tolerance in vitro and the fecal recovery in vivo after oral administration of a Saccharomyces cerevisiae strain to healthy volunteers. At the lowest pH value (pH 1.0) the yeast load in tablets decreased slightly. From pH 1.0 to pH 7.0 the release of S. cerevisiae in buffer solutions increased. The selected yeast strain showed good tolerance to low pH which mimic the gastric environment. After one month of treatment at a dose of 100 million cells per day, S. cerevisiae grew from the feces of 6 (37.5%) of the 16 healthy, treated volunteers. Based on the results of the present experiments the yeast studied can be considered a strain that tolerates adverse conditions comparable to those of the human gastrointestinal tract, and when administered orally may colonize the bowel of healthy volunteers and even replace resident Candida species.

Manipulation of the bacterial flora in inflammatory bowel disease

In this chapter we summarize the clinical and experimental data which indicate that bacteria, especially from the endogenous microflora, play a role in the pathogenesis of Crohn's disease, ulcerative colitis and pouchitis. We review the clinical trials, focusing on randomized controlled trials which used antibiotics or probiotics to treat situations of IBD or prevent recurrence, and we discuss the future of this approach.