In a recent study published in the American Society for Microbiology’s journal MSystems, a team of researchers from the United States used a murine model to investigate the impact of broccoli sprouts and bio-actives on the interactions between the host and the gut microbiota and its role in resolving Crohn’s disease symptoms.
Study: Early life exposure to broccoli sprouts confers stronger protection against enterocolitis development in an immunological mouse model of inflammatory bowel disease. Image Credit: Nataly Studio/Shutterstock.com
Inflammatory bowel disease often presents as Crohn’s disease during childhood and adolescent years and manifests as severe and chronic enterocolitis and dysregulations of the immune system and gut microbiota.
The highly varied and intense presentation of symptoms and the multifactorial origin of the disease strongly impact the quality of life of the patients while making the condition hard to manage.
The current treatment options for Crohn’s disease involve immunosuppressants to reduce inflammation and help the patients return to a homeostatic state. Still, the response to these medications is often poor.
The symptoms can be ameliorated through autoinflammatory metabolites supplied through diet or produced by gut microbiota. Studies have shown that Crohn’s disease patients often exhibit lower alpha and beta diversity in the gut microbiome than healthier individuals.
The manifestation of the disease also differs across ages, with younger patients presenting with ileal disease and colitis being more prevalent in older patients. Including vegetables such as cruciferous vegetables containing sulfur-containing glucosinolates is known to reduce inflammation in the gastrointestinal tract.
About the study
In the present study, the researchers used the interleukin ten knockout mouse model to examine the interactions between the host, the gut microbiome, and broccoli sprouts and bioactives.
This murine model has been widely used for studying inflammation and immune factors, as interleukin 10 plays a major role in inhibiting the production of inflammatory cytokines.
The researchers hypothesized that the dietary inclusion of raw broccoli sprouts would protect the mice from inflammation caused by microbial conventionalization, especially in cases of gut microbiome dysbiosis.
They expected the broccoli bioactives to change the gut microbiota in a location-specific manner and increase the abundance of beneficial microbes while limiting the number of potentially pathogenic microbes.
Raw broccoli contains the precursor of the glucosinolate glucoraphanin, as well as sulforaphane, which is an anti-inflammatory isothiocyanate. Murine model studies have shown that glucoraphanin and sulforaphane protect against ulcerative colitis and some pathogenic bacteria.
Both these compounds are unstable in their pure form. Still, sulforaphane is produced from glucoraphanin by plant enzymes while chewing or chopping raw vegetables or through microbial activity in the gut.
The researchers inoculated the interleukin-10-knockout mice with Helicobacter hepaticus to induce Crohn’s disease-like symptoms in these immune-impaired mice. These mice were fed a raw diet containing broccoli sprouts in a 10% weight-to-weight ratio from four to seven weeks of age. The mice were compared to mice fed the standard chow's control diet.
Disease severity was assessed based on blood in feces and stool consistency. Fecal samples were collected at regular intervals, and plasma samples were collected after euthanizing the mice to measure fecal lipocalin, an intestinal inflammation marker.
The plasma samples were also analyzed for pro-inflammatory cytokines such as interleukin 1β, interleukin 6, and tumor necrosis factor α.
The results showed that the mice fed on the raw broccoli sprout diet had higher levels of sulforaphane in their plasma and showed a decrease in weight stagnation, diarrhea, and blood in the feces.
Furthermore, the microbial richness of the gut microbiome was also found to increase. Pathobiont bacteria such as Helicobacter and Escherichia coli, which cause inflammation in the interleukin-10-knockout mice, decreased in abundance and prevalence after the raw broccoli sprout diet.
The scientists observed that the younger mice showed a heightened response to the diet consisting of raw broccoli sprouts. They believe that the gut microbiomes of younger mice are still unstable and, therefore, remain amenable to modifications and selective pressure.
These results are supported by various other human studies that report that the gut microbiomes of infants and young children are comparatively more plastic than those of adults, suggesting that dietary interventions to help restructure gut microbiomes could be more effective if administered early in children.
Overall, the findings reported that a raw broccoli sprouts diet significantly improved factors such as weight stagnation and blood in the feces in murine models with chemically induced ulcerative colitis.
Broccoli sprouts also seem to modify the gut microbiome and lower the abundance and prevalence of pathogenic bacteria.
These results highlight the need for further research on the interactions between host, microbiome, and diet in the context of inflammatory bowel diseases.