More on Blastocystis and Gut Bacteria...

As an appropriate follow-up on yesterday's post, I feel like guiding your attention to the paper by Laforest-Lapointe and Arrieta from University of Calgary, Canada with the title 'Microbial Eukaryotes: a Missing Link in Gut Microbiome Studies', which elaborates on some of the issues that we have already been highlighting several times in the past.

Nevermind, in their article, which just appeared in the ASM-based journal "mSystems", they speculate that the reason for the observed link between Blastocystis colonisation and increased bacterial diversity (which was mentioned several times in the paper that I referred to yesterday) might be due to predation by Blastocystis on bacteria, a process which selects for higher diversity. They argue that

"In the absence of Blastocystis, a strong bacterial competitor dominates the community, which limits species richness and community evenness; when [Blastocystis is] present, its predation on abundant bacterial taxa lowers the competition for nutrients and space, which leads to an increase in bacterial richness and community evenness."

Since predation on bacteria by Blastocystis has only been documented once (I believe) to date, the authors are right in encouraging colleagues to study engulfment of bacteria by Blastocystis.

Those of us who take a special interest in the public health impact of common intestinal parasites and who work in the field of clinical microbiology and infectious diseases might benefit from taking some lessons from experts in 'food web theory' and micro- and macroecology.

The article can be accessed here.

Associations Between Intestinal Parasites and Bacteria

For those interested in exploring the presence/absence of intestinal parasites in a gut microbiome context, Dr Mark van der Giezen and I did this small opinion paper for Trends in Parasitology. In it, we summarize data from studies looking at the associations between single-celled intestinal (luminal) parasites and gut bacteria, and we tried to come up with a hypothesis for the factors governing the presence/absence of e.g. Blastocystis.

The paper just appeared online, and you can access it here.

PhD position available in Pauline's lab

Message from Dr Pauline D Scanlan (view personal website here):

I have a potential PhD position available for a suitable candidate on the impact of antibiotics on gut microbiome diversity and function - check out the link to my site for more information! Please Retweet! https://t.co/GzqI2A2UwF

— Pauline Scanlan (@PaulineDScanlan) February 20, 2018

Abstract submission now open for 2nd International Blastocystis Conference!

Hi all,

 

The Scientific Program Committee of the 2nd International Blastocystis Conference now invites authors to submit abstracts. Please visit http://www.urosario.edu.co/Blastocystis/en/home/#call-for-abstracts) urosario.edu.co/Blastocystis/e… to register and upload your abstract(s). 

See you there!

Official Poster for the 2nd International Blastocystis Conference

Thanks to Juan-David Ramirez Gonzales and his colleauges, the official poster for the 2nd International Blastocystis Conference is now available.

I put it on Google Drive as a pdf file, which you can download here. Please share it on facebook. Please also print it and use it to adorn your institutes, hospital departments, offices, canteens, homes, etc... Thanks!

Website for 2nd International Blastocystis Conference is now live!

I'm happy to be able to point your attention towards the website for the 2nd International Blastocystis Conference in Bogotá in October 2018. You can access the website here.

On this site, you'll find information about the venue, the preliminary programme, speakers, registration, and sponsors. You will also find some information about Bogotá.

Please visit the website on a regular basis for potential updates/changes.

See you there!

Trends in Blastocystis Research

I thought I'd post two current conference abstracts to exemplify some of the trends in  Blastocystis research.

The first is from Dr Pauline D Scanlan, who will be speaking at 15th International Congress of Protistology currently taking place in Prague. Go here for more info about the meeting.

In the symposium 'The eukaryome, bringing protists into the spotlight of microbiome research' taking place today, Pauline will be giving a talk with the title:

Inter-Kingdom Interactions in the human gut microbiome-the prevalence of the intestinal protist Blastocystis is linked to host age, antibiotic use and gut bacterial diversity and composition

and the abstract reads like this:

The human gut is host to a complex microbial ecosystem that plays a central role in host health. In addition to bacteria, viruses and archaea, the gut microbiota includes a diversity of fungal and protist species that are collectively referred to as the gut ‘eukaryome’. Although research into the gut eukaryome is in its infancy, emerging data indicates that the intestinal protist Blastocystis is perhaps the most common member of the human gut eukaryome worldwide. Despite its association with intestinal disease, asymptomatic carriage is common with Blastocystis frequently observed in surveys of the healthy adult gut microbiome. Furthermore, Blastocystis is less prevalent in chronic diseases such as Irritable Bowel Syndrome compared to healthy controls. Antibiotic administration significantly reduces Blastocystis prevalence rates between case and controls groups with the reduction in Blastocystis prevalence in the antibiotic treated group possibly due to direct effects on Blastocystis and/or secondary loss due to loss of bacteria that Blastocystis interacts with. In support of this latter hypothesis, data showing correlations between the presence of Blastocystis and specific features of the bacterial component of the gut microbiome (high diversity and a specific bacterial composition) are suggestive of inter-kingdom interactions between bacteria and Blastocystis in the gut microbiome. Blastocystis is less prevalent in infant populations relative to contemporaneous adult populations indicating that Blastocystis is not adapted to the infant gut. Given the difference in microbiome composition and diversity in infants compared to adults perhaps Blastocystis requires a more adult-like gut microbiome for successful colonisation. Collectively, emerging data suggests that successful colonisation of the gut by Blastocystis is linked to the composition and diversity of the bacterial fraction of human gut microbiome. Consequently, interactions between Blastocystis and bacteria in the gut microbiome may account for some of the variation in prevalence rates observed across age, health and geography.

 
Along similar lines, I will be giving a talk at the EMBO conference 'Anaerobic protists: Integrating Parasitology with mucosal microbiota and immunology' running from 31 AUG to 03 SEP in Newcastle, UK. You can read about the conference here.

The title and abstract of my talk are as follows:

The diversity of the most common intestinal protists, Blastocystis and Dientamoeba, and their interactions with the microbiota: what role in health and disease?

The integration of DNA-methods in Clinical Microbiology has enabled a more detailed and accurate snapshot of the protists colonising and infecting our guts. Parasites like Blastocystis and Dientamoeba are much more common than previously known, when detection relied mainly on microscopy of faecal concentrates and smears only.

While Dientamoeba isolated from humans exhibits very little genetic variation across the small subunit ribosomal gene, Blastocystis displays a perplexing amount of genetic heterogeneity, and nine subtypes, which are arguably separate species, have been found in humans. Subtypes 1 to 4 account for about 95% of human Blastocystis carriage.

It is expected that over 1 billion people are colonised by Blastocystis, and based on DNA-based detection, prevalence figures of up to 100% have been reported in developing countries. Conversely, the prevalence of Blastocystis appears relatively low in e.g. the US, and it has been suggested that the low prevalence is indicative of the defaunation of indviduals adapting a Westernized life style.

In a developed country like Denmark, the prevalence of Blastocystis and Dientamoeba is highest in individuals without gastrointestinal, while the prevalence of these parasites is lower in patients with functional and organic bowel disease, suggesting that these parasites are in fact markers of gastrointestinal health.

This is also in part exemplified by recent independent data linking high gut microbiota diversity to the presence of these parasites. Certain bacterial populations appear to be linked to parasite carriage, and studies are emerging that try to look into the association between these parasites and the remaining gut microbiota.

Moreover, higher age appears to be linked to Blastocystis colonisation. Blastocystis is more common in older children and adults, while in younger children, Dientamoeba is much more common.

Whether these parasites are able to modulate gut microbiota structure and function remains unknown, and it also remains to be demonstrated whether certain microbiota communities and/or metabolites are required for successful establishment of these parasites. More research data on these topics will inform future advances in probiotics in particular and gut microbiota manipulation in general.

 Thanks for your time.