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.
