Functional digestive disorders and the microbiome

A targeted combination of 5 immunomodulatory probiotic strains and OMEGA-3 fatty acids

The probiotic bacterial strains in this study were carefully selected on the basis of their scientifically demonstrable positive effects in the management of symptoms of functional digestive disorders.

In 2018 a clinical study was carried out on a targeted combination of 5 probiotic bacteria to evaluate the effect on alleviating the symptoms of functional digestive disorders, primarily irritable bowel syndrome (IBS). The results showed that the investigated probiotic blend is effective in improving the severity of IBS-type symptoms. After 6 weeks of treatment, a significantly higher treatment success rate was found, along with reduced perception of pain on various clinical scales and a modification of the gut microbiota, characterised by an increase in bifidobacteria that are still detectable 6 weeks after the probiotics were discontinued.

Clinical study

Introduction

Functional gastrointestinal disorders (FGID), known as gut–brain axis disorders, are characterised by marked changes in the gut microbiota profile, namely reduced biodiversity, a marked decrease in the numbers of bifidobacteria and lactobacilli, and an increase in the number of potentially pathogenic bacteria (1).

The resulting dysbiosis often leads to impaired integrity of the intestinal epithelium, visceral hypersensitivity and abnormalities of gut motility, which increases intestinal barrier dysfunction.

FGID include, among others, irritable bowel syndrome (IBS), functional dyspepsia (FD) or a spectrum of symptoms such as abdominal pain/burning, bloating, nausea, fullness, vomiting and altered bowel habits such as diarrhoea, constipation or both.

This clinical study revealed that a probiotic blend of lactobacilli and bifidobacteria is effective in reducing the severity of IBS-like symptoms by modifying the gut microbiota, primarily by increasing the numbers of bifidobacteria and lactobacilli. The severity of IBS symptoms on selected rating scales fell significantly in the probiotic group compared with the placebo group, as well as between the start and the end of the clinical study.

Aims

The primary aim of the clinical study was to evaluate the efficacy and safety of a probiotic blend in patients with symptoms of irritable bowel syndrome.

Methods

Patients with IBS-type symptoms entered a prospective, double-blind, randomised, placebo-controlled fourteen-week study.

The six-week treatment period (weeks 3 – 8) was preceded by a two-week run-in phase and followed by a 6-week observation phase.

Clinical data were monitored throughout the study using validated questionnaires: the IBS Severity Scoring System (IBS-SSS); the Gastrointestinal Symptom Rating Scale (GSRS) and the Bristol Stool Form Scale (BSFS). Faecal microbiota was tested by culture and 16S rRNA sequencing analysis (1).

Results

1) IBS Severity Scoring System (IBS-SSS)

The severity of IBS symptoms on the IBS-SSS rating scale fell significantly in the probiotic group compared with placebo (-21.4% ± 15.5% vs. -6.8% ± 21.7%; p < 0.01) (Figure 1) (1).

2) Gastrointestinal Symptom Rating Scale (GSRS) and Bristol Stool Form Scale (BSFS)

The severity of IBS symptoms on the GSRS rating scale fell significantly in the probiotic group compared with placebo (-19.8% ± 16.6% vs. 12.9% ± 31.6%; p < 0.001) (Figure 2) (Table 2).

At the end of treatment the BSFS score fell significantly in the probiotic group compared with placebo (-3.3% ± 41.6% vs. 51.5% ± 101.1%; P < 0.01) (1).

3) Evaluation of faecal culturable bacteria and the microbiome

Compared with baseline, total anaerobe counts increased from 7.02 to 8.35 log CFU/g (mean values, P = 0.018) after 6 weeks of probiotic treatment. Probiotic treatment also leads to an increase in presumptive lactic acid bacteria (Lactobacillus, Lactococcus, Streptococcus, Staphylococcus and Bifidobacterium) (Figure 3). Compared with baseline, higher levels of presumptive bifidobacteria were also found after 6 weeks of probiotic treatment (Figure 4).

Treatment success

Treatment success was significantly higher in patients taking probiotics than in those on placebo, both in the intention-to-treat analysis (14.8% vs. 3.6%; p < 0.04) and in the per-protocol analysis (15.3% vs. 3.8%; p < 0.04) (Figure 5 A and B) (1).

In vitro studies

Coeliac disease is an autoimmune enteropathy caused by intolerance to gluten proteins. The 2020 in vitro study aims to evaluate the ability of a targeted combination of 5 probiotic bacteria to hydrolyse gluten peptides after simulated gastrointestinal digestion of gliadin in Caco-2 cells.

The ability of bacterial hydrolysates to counteract the toxic effects of gliadin-derived peptides in Caco-2 cells was also assessed. The results of this study suggest that these probiotic strains are able to reduce the toxicity of the gliadin that remains after peptic-tryptic digestion, by degrading immunodominant gliadin peptides, thereby inhibiting their harmful effects on intestinal epithelial cells, and so may have a protective role in coeliac disease.

Aims

The primary aim was to evaluate the ability of a targeted combination of 5 probiotic bacteria to digest gliadin peptides in vitro and to modify the gliadin-induced pro-inflammatory response and changes in epithelial structure in the human intestinal cell line Caco-2 (2).

Methods

The in vitro study observed the proteolytic activity of selected probiotic strains in aliquots with a gliadin/enzyme complex (PT-gliadin, P: pepsin, T: trypsin or chymotrypsin w/w, ratio 1:40) as well as with crude gliadin, compared with a control sample without probiotic bacteria (2).

Results

1) Proteolytic activity of the targeted combination of 5 probiotic bacteria

The results of gliadin analysis by SDS-PAGE suggest that after the first enzymatic digestion with a combination of pepsin and trypsin (PT, lane 3) or with chymotrypsin alone (chymo-, lane 4), the selected probiotic bacteria are able to break gliadin down further into fragments with a molecular weight below 35 kDa (lanes 6, 7). In addition, gliadin not treated with digestive enzymes (lane 2) appears to be partly digested by the bacteria (lane 5), which speaks in favour of their proteolytic activity even without prior digestion (Figure 6). The results therefore suggest that probiotics can help with the digestion of gliadin (2).

2) Effect of PT-gliadin and PT-gliadin/probiotics on Caco-2 tight junctions

The results show that untreated Caco-2 monolayers had the typical localisation of ZO-1 and occludin at the cell periphery (3), whereas treatment with PT-gliadin for 3 hours induced a marked decrease in ZO-1 fluorescence and a redistribution of occludin at the cytosolic level, which may lead to weakening of the tight junctions of the barrier and an increase in its permeability. When the cells were treated with PT-gliadin/probiotics, neither release of ZO-1 nor redistribution of occludin was observed, which suggests an ability of the probiotics to protect tight junctions (Figure 7).

3) Modulation of IL-6 production and oxidative stress by Caco-2 cells exposed to PT-gliadin digested or undigested by bacteria

PT-gliadin was able to cause a significant increase in IL-6 production compared with the control. In the presence of PT-gliadin/probiotics no increase in IL-6 could be observed; instead, a significant decrease in IL-6 production was observed compared with the control cells, which suggests an anti-inflammatory protective effect of the probiotics (2).

Omega-3 PUFAs and enhancing the efficacy of probiotics

Combining probiotics with synergistically acting ingredients of natural origin is a suitable way to increase the efficacy of probiotic preparations. A number of suitable components, such as polyunsaturated fatty acids (PUFA), appear to be usable to potentiate the effect of probiotics. Their presence promotes the adhesion of probiotic bacteria (e.g. Lactobacillus spp.) to receptors of the intestinal mucosa (4).

Omega-3 PUFAs may have a positive effect in these diseases by changing the composition of the microbiota and increasing the production of anti-inflammatory compounds such as short-chain fatty acids (acetate, propionate, butyrate). In addition, accumulating evidence from animal-model studies suggests that the interplay between the gut microbiota, omega-3 fatty acids and immunity helps maintain the integrity of the intestinal wall and interacts with the host’s immune cells. Finally, studies in humans and animals have highlighted the ability of omega-3 PUFAs to influence the gut–brain axis through the composition of the gut microbiota (5).

Conclusion

Current research suggests that the severity of symptoms of functional digestive disorders, primarily IBS, can be alleviated by supplementation with a probiotic blend of lactobacilli and bifidobacteria, by modifying the gut microbiota and correcting dysbiosis.

The results of the clinical and in vitro studies suggest that selected strains of lactobacilli and bifidobacteria are suitable for patients with functional digestive disorders such as IBS, as well as for people with coeliac disease, because of their antioxidant and anti-inflammatory activities and their role in restoring the intestinal barrier.

In addition, the selected bacterial strains target the symptoms associated with HIT directly, do not produce histamine and so are also suitable for people with histamine intolerance (HIT).

The effect of the 5 specifically selected probiotic bacterial strains can be enhanced by synergistically acting polyunsaturated fatty acids (PUFA), Omega3-EPA and Omega3-DHA, which support the formation of anti-inflammatory compounds and help the probiotic bacteria to attach to the intestinal mucosa.

References

1. Francavilla R, et al. Clinical and Microbiological Effect of a Multispecies Probiotic Supplementation in Celiac Patients With Persistent IBS-type Symptoms: A Randomized, Double-Blind, Placebo-controlled, Multicenter Trial. J Clin Gastroenterol. 2019 Mar;53(3):e117–e125.
2. Giorgi A, et al. A Probiotic Preparation Hydrolyzes Gliadin and Protects Intestinal Cells from the Toxicity of Pro-Inflammatory Peptides. Nutrients. 2020 Feb 14;12(2):495.
3. Lei S, et al. Somatostatin ameliorates lipopolysaccharide-induced tight junction damage via the ERK-MAPK pathway in Caco2 cells. Eur. J. Cell Biol. 2014, 93, 299–307.
4. Bomba A, et al. Improvement of the probiotic effect of microorganisms by their combination with maltodextrins, fructooligosaccharides and polyunsaturated fatty acids. Br J Nutr. 2002 Sep;88 Suppl 1:S95–9.
5. Costantini L, Molinari R, Farinon B, Merendino N. Impact of Omega-3 Fatty Acids on the Gut Microbiota. Int J Mol Sci. 2017 Dec 7;18(12):2645.