Difference between revisions of "Helminths and the gut microbiota"

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(→‎2020: Added a citation.)
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==== 2020 ====
==== 2020 ====
* [https://pubmed.ncbi.nlm.nih.gov/32436176/ Changes in the Severity of Gastric Mucosal Inflammation Associated With Helicobacter Pylori in Humans Coinfected With Intestinal Helminths]

* [https://www.ncbi.nlm.nih.gov/pubmed/32194529 Dietary Inulin and Trichuris suis Infection Promote Beneficial Bacteria Throughout the Porcine Gut] — [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064446/ Full text] | [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064446/pdf/fmicb-11-00312.pdf PDF]
* [https://www.ncbi.nlm.nih.gov/pubmed/32194529 Dietary Inulin and Trichuris suis Infection Promote Beneficial Bacteria Throughout the Porcine Gut] — [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064446/ Full text] | [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064446/pdf/fmicb-11-00312.pdf PDF]

Revision as of 00:15, 22 May 2020

Home>Effects of helminthic therapy>Helminths and the gut microbiota

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Helminths and bacteria form a complex, interactive ecosystem involved in immunity[edit]

The gut and its inhabitants should be considered a complex ecosystem, not only involving bacteria but also parasites, not just sitting together but interacting. (Prof Richard Grencis, Manchester University) [1]
It is like a three-legged stool - the microbes, worms and immune system regulate each other. The worms have been with us throughout our evolution and their presence, along with bacteria, in the ecosystem of the gut is important in the development of a functional immune system. (Prof Ian Roberts, Manchester University) [2]
Our findings show that murine intestinal helminth infection not only alters the intestinal bacterial communities but that intestinal bacteria contribute to the ability of helminth infection to attenuate allergic airway inflammation. (Zaiss, et al) [3]

Scientific papers and articles relating to helminths and the gut microbiota[edit]


Increased numbers of helminth co-infections, in particular with the gut-resident soil-transmitted helminths, were significantly associated with increased bacterial diversity which, in general, is associated with a healthy gut.


There is considerable interplay between helminths, micronutrients and the microbiota on the regulation of immune responses in humans.
The modulation of the immune system by helminths involves an interplay with several other factors, such as diet and environment, in addition to being influenced by the composition of the gut microbiome.
This work provides conclusive evidence that intestinal helminths can impact the mammalian intestinal microbiome, and indicates that helminth-induced changes can occur at regions distant from the site of parasite infection.
Helminths prevented weight gain in laboratory mice on a high-fat diet. They did this by boosting populations of bacteria - notably certain species of Bacillus and Escherichia - that produce compounds which trigger increased energy consumption.
This study contributes to understanding of how microbial communities differ between individuals infected by soil-transmitted helminths and those who are uninfected.
In a very detailed “Helminths” section (pages 26-35), this paper discusses evidence that host-associated microbes may impact helminth infection success, that helminth colonization may impact the diversity and composition of the gut microbiome, and that both can have impacts on immune function.


Trichuris suis and dietary inulin co-operatively mediate beneficial changes in microbiota composition in pigs to enhance anti-inflammatory immune responses.
Monospecific, chronic infection with the helminth, S. stercoralis, were found to be associated with global shifts in the composition of the human faecal microbiota, as well as subtle changes in faecal metabolic profiles.
The helminth, A. suum, uses a variety of factors with broad-spectrum antibacterial activity to affirm itself within its microbe-rich environment in the gut.
While this study focused on the parasites, Dientamoeba fragilis and Blastocystis, rather than helminths, its conclusions are nevertheless interesting.
“Presence of parasites was associated to a rich and diverse microbiome in healthy controls and individuals with unspecific GI symptoms… Observations of parasite colonization being associated to healthy features of the gut microbiome should differentiate our view of intestinal parasites beyond the focus on pathogenicity.”
This is a good review of studies investigating the interactions of the intestinal microbiota, gut parasites and their host, and how these interactions may affect the overall health of the host.
The eggs of T. muris that hatch in sterile conditions are free from bacteria.
T. muris maintains its own distinct microbiota, comprising bacteria selected from the intestine of its host, regardless of the surrounding bacterial populations.
Infection with T. muris causes significant restructuring of the host cecal microbiota and a reduction in total bacterial diversity.
T. muris-induced changes in the host microbiota suppresses subsequent parasite egg hatching, consequently controlling parasite numbers in the infected host intestine independently of the host adaptive immune system.


Highlights findings concerning responses to bacterial stimuli, antimicrobial peptides and the reciprocal influences between nematodes and their environmental bacteria. Also discussed are the microbiota of nematodes and alterations in the intestinal microbiota of mammalian hosts by helminth infections.


Helminth infection protects mice deficient in the Crohn’s disease susceptibility gene Nod2 from intestinal abnormalities by inhibiting colonization with an inflammatory Bacteroides species.
Discusses at length the interrelationships between intestinal helminths and microbiota, in both humans and mice, and highlights the fact that certain microbiota species can determine the outcomes of helminth infection.
"... although intestinal helminths are generally accepted to possess potent immuno-modulatory activity, it is unknown whether this capacity requires interactions with intestinal bacteria. We propose that this 'ménage à trois' situation is likely to have exerted a strong selective pressure on the development of our metabolic and immune systems."


Helminths and bacterial microbiota act in bi-directional synergy to modulate immune responses.
Helminths move the balance of the intestinal flora to favour “probioticmicroorganisms.
"Notably, we observed a significant increase in microbial species richness over the course of the trial, which could represent a potential mechanism by which hookworms can regulate gluten-induced inflammation and maintain intestinal immune homeostasis."
"Dynamic interactions between the host and gastrointestinal microbiota play an important role for local and systemic immune homeostasis."
"In general, helminth presence is linked with high microbiota diversity, which may confer health benefits to the host… The most pronounced helminth-microbiota association was between the presence of tapeworms in the small intestine and increased S24-7 (Bacteroidetes) family in the stomach."
"In this article, we review recent progress in the elucidation of host-parasite-microbiota interactions in both animal models of chronic inflammation and humans, and provide a working hypothesis of the role of the gut microbiota in helminth-induced suppression of inflammation."
Colonisation by Hymenolepis diminuta led to several changes in rat cecal microbiome that were mostly within the Firmicutes phylum, involved about 20% of the total bacteria, and entailed a shift from Bacilli to Clostridia species.
"... infection of T. muris causes a significant and substantial impact on intestinal microbiota and digestive function of mice with affects in long term immune regulation."


Hookworm infection produces a minor increase in microbial species richness, but has no detectable effect on community structure, diversity or relative abundance of individual bacterial species. (NB. Testing was done at only 8 weeks, so the worms were not yet fully engaged.)
“… helminth-induced immunomodulation occurs independently of changes in the microbiota but is dependent on Ym1.”
Discusses changes occurring in the microbiota upon helminth infection and the underlying mechanisms leading to these changes.
Helminths may have an impact on the diversity, bacterial community structure and function of the gut microbiota.
Some bacteria and nematode-trapping fungi form mutually beneficial relationships to victimise nematodes.
The bacterium, B. animalis, significantly decreased the S. venezuelensis worm burden and egg output.


"… by inducing an immune response that includes IL-22, intestinal helminths may enhance the mucosal barrier function of the intestinal epithelium. This may restore the mucosal microbiota populations from dysbiosis associated with colitis and improve intestinal homeostasis."


Whipworms can restore the balance of gut bacterial communities in sick monkeys.


Some probiotic strains have been shown to be effective in controlling some species of parasitic worm. NB. This study was not concerned with helminths used in therapy, but other types of parasite.


Helminth infection shifts the composition of intestinal bacteria.
"It is like a three-legged stool - the microbes, worms and immune system regulate each other. The worms have been with us throughout our evolution and their presence, along with bacteria, in the ecosystem of the gut is important in the development of a functional immune system."