Showing posts with label Blastocystis. Show all posts
Showing posts with label Blastocystis. Show all posts

Thursday, May 5, 2016

This Month in Blastocystis Research (APR 2016)

I thought I’d give examples of some of the Blastocystis-related activities in which I was involved in April.

I was lucky to be invited as part of the faculty for this year’s ECCMID conference in Amsterdam. I had an opportunity to give a talk on Detection of protozoans using molecular techniques in routine clinical practice (click link to watch it). I also co-authored a poster with the title Blastocystis colonization correlates with gut bacterial diversity which is one of several studies recently performed by our group that suggest that Blastocystis is a biomarker – or an indicator if you wish – of a healthy gut microbial environment and high gut microbiota diversity. 

This very topic was one of the two major topics of my colleague Lee O’Brien Andersen’s PhD work; Lee just defended his thesis this Friday and being involved in his work is some of the most interesting, rewarding, and challenging professional activities I’ve experienced so far. I will soon provide a link to an electronic version of his thesis here on this site. I hope that we will be able to fund his post doc aiming to expand his work on comparative Blastocystis genomics, since he only just started this work. Also, I hope that we will be able to do much more research on Blastocystis’ impact on host immunity and gut microbiota using in vitro and in vivo models. We need to know much more about to which extent Blastocystis can actually induce changes in bacterial communities and what these changes are. We also need to know whether manipulation of gut bacteria in a Blastocystis carrier can lead to eradication of the organism. 

Last week, I was so fortunate to oversee the production of an e-learning course in faecal microbiota transplantation (FMT) for Unite European Gastroenterology (UEG), which will probably appear online already in June. FMT is currently used primarily for treating recurrent Clostridium difficile infections, but the application range may extend far beyond this. The presentations included both theoretical and live sessions, and it was a lot of fun to do, not only because of the topic, but also because my colleagues at the Agostino Gemelli University Hospital in Rome were extremely professional, enthusiastic and well-organised. The reason why FMT is interesting in a Blastocystis context includes the fact that while there are quite standardized guidelines as to what is not allowed in donor stool, there is no consensus on what is actually allowed in the stool. Obviously, Blastocystis will often be present in donor stool, and when conventional microbiological methods are used to screen donor stool for pathogens, Blastocystis will only rarely be picked up. Hence recipients may receive stool containing Blastocystis. And so of course we would like to know whether to recommend using or excluding stool positive for Blastocystis (and other common parasites such as Dientamoeba) for FMT.

Friday, April 1, 2016

This Month in Blastocystis Research (MAR 2016)

I'm going to dedicate this post entirely to a recent case presented by my wonderful colleague Bobbi Pritt (Mayo Clinic) in collaboration with Blaine Mathison (CDC), whom I have also been so fortunate to meet.

Please go here to see the case.

Creepy Dreadful Wonderful Parasites: Case of the Week 390.

Let me use the opportunity to congratulate Bobbi Pritt on her fantastic work, admirable skills, and dedication to parasitology!

And by the way; why not treat yourself to Bobbi's 2016 parasite calendar available for purchase here.

Tuesday, March 1, 2016

This Month in Blastocystis Research (FEB 2016) - Rash Edition

A couple of years ago, I contributed to writing up a Case Report on what appeared to be Blastocystis-associated urticaria (hives). Receiving various courses of ineffective antibiotic treatment with a view to eradicating Blastocystis, a woman continued to suffer from gastrointestinal symptoms and generalized urticaria. Only when the infection was eventually successfully eradicated using a combination of metronidazole and paromomycin, the women experienced symptom resolution.

There is a systematic review out just now in the well-esteemed journal "Allergy" on chronic spontaneous urticaria in patients with intestinal parasites. The approach is useful, interesting, and relevant. One of the main results, which was also highlighted in the abstract, is that patients with chronic urticaria more frequently have "Blastocystis hominis allele 34 (ST3)". This observation, however, pertains to one single study, and should be interpreted in this context. The original study was carried out by Rudolfo Daniel Casero and last-authored by a close colleague of mine, Juan David Ramirez, who currently does a lot to promote and improve molecular parasitology research in Latin America; among other things, he's a very successful and avid arranger of workshops. Anyway, the study included observations on Blastocystis in a group of Argentinean patients, who were stratified by the presence or absence of symptoms. Hence, there were four groups, reflecting 1) asymptomatic patients, 2) patients with chronic urticaria, 3) patients with non-specific gastrointestinal symptoms (NSGI), and 4) patients with both chronic urticaria and NSGI. No specific subtype was linked to any of the four groups; however, a very striking observation related to the distribution of ST3 strains across the groups: out of a total of 21 patients positive for ST3 allele 34 (the allele number is used to provide "genotype" information of the subtype), 18 had urticaria. On the other hand, out of 28 patients positive for ST3 allele 134, only 3 had urticaria.

ST3 allele 34 is probably the most common Blastocystis strain overall in many European countries; also in Asia (e.g. India), this genotype particularly common. Although common in South America too, it might not be the most common strain, given the data by Casero et al. These authors are the first to provide a clear association between a Blastocystis strain (i.e., on genotype level) and development of symptoms. Although the data warrant confirmation by prospective studies, the data should be food for thought.

About 20 papers are listed in PubMed on "Blastocystis AND urticaria". Last year, I was so fortunate to host Małgorzata Lepczynska in our lab for a couple of weeks. Incidentally, a review of the role of Blastocystis in the development of urticaria and first-authored by Lepczynska just emerged in PubMed. The authors try to explain the potential mecanisms underlying the development of Blastocystis-induced urticaria. For some reason, the authors did not include a study by Armentia et al. from 1993 (maybe due to the possibility that they had no access the paper?). Armentia presented a case series (n = 10) of Blastocystis patients who all had chronic urticaria; both the parasite and the symptom disappeared upon treatment with paromomycin sulfate.

I am not sure that the data available at this point are sufficient to generate inferences on the contributing role of Blastocystis in the development of urticaria; however, I would not hesitate to encourage dermatologists to look into the issues of "idiopathic chronic urticaria", with a view to clarifying the rate of Blastocystis colonisation among these patients and whether parasite eradication leads to symptom resolution. Such studies should also involve total analysis of the intestinal microbiota, both before and after treatment.

References:

Armentia A, Méndez J, Gómez A, Sanchís E, Fernández A, de la Fuente R, & Sánchez P (1993). Urticaria by Blastocystis hominis. Successful treatment with paromomycin. Allergologia et Immunopathologia, 21 (4), 149-51 PMID: 8237719   

Casero, R., Mongi, F., Sánchez, A., & Ramírez, J. (2015). Blastocystis and urticaria: Examination of subtypes and morphotypes in an unusual clinical manifestation Acta Tropica, 148, 156-161 DOI: 10.1016/j.actatropica.2015.05.004

Kolkhir P, Balakirski G, Merk HF, Olisova O, & Maurer M (2016). Chronic spontaneous urticaria and internal parasites - a systematic review. Allergy, 71 (3), 308-22 PMID: 26648083

Lepczyńska M, Chen WC, & Dzika E (2016). Mysterious chronic urticaria caused by Blastocystis spp.? International Journal of Dermatology, 55 (3), 259-66 PMID: 26469206 


Vogelberg C, Stensvold CR, Monecke S, Ditzen A, Stopsack K, Heinrich-Gräfe U, & Pöhlmann C (2010). Blastocystis sp. subtype 2 detection during recurrence of gastrointestinal and urticarial symptoms. Parasitology International, 59 (3), 469-71 PMID: 20363362 

Saturday, January 30, 2016

This Month in Blastocystis Research (JAN 2016)

Three publications have caught my attention over the past month.

The first one is by my Turkish colleagues Kurt, Dogruman-Al, and Tanyüksel. They just published the paper "Eradication of Blastocystis in humans: Really necessary for all?" This title implies that treatment of Blastocystis is recommendable in some cases. The authors appear to acknowledge the view that treatment should be given to symptomatic carriers when all other causes of gastrointestinal symptoms have been rule out, - the popular 'last-resort' approach.

What I think is really useful and admirable is that the authors leave so many questions open/unanswered, despite the fact that they have been "in business" for so many years, representing some of the most avid Blastocystis researchers. It becomes clear from reading the paper that even in 2016, we still do not know how to eradicate Blastocystis from the intestine in those cases where we'd really like to try and do so. Importantly, the authors give examples of data supporting the fact that treatment failure may be due to failure of the drug to reach the parasite as well as treatment resistance. They also highlight the possibility that eradication of Blastocystis by antibiotic/anti-protozoal agents may be due to microbiota perturbation rather than a direct action on Blastocystis. I also very much appreciate the fact that the authors are embracing the necessity of studying Blastocystis in a parasite-microbiota-host context in order to be able to draw useful conclusions on its role in human health and disease.

Das and colleagues just published data on Blastocystis and subtypes of Blastocystis in IBS patients and controls in New Delhi, India. Using multiple traditional and DNA-based methods, they found that in their study material, the prevalence of Blastocystis was higher among patients with IBS than among healthy controls. It is not exactly clear how the controls were picked and what type of study population they represented. What I found really useful is the fact that they not only carried out subtyping of Blastocystis, but also identified subtype alleles. The subtypes and alleles found in the study were very similar to those found recently by Pandey et al. (2015) in Maharashtra, India.  Interestingly, it appears that only two subtypes are found in humans in India, namely ST1 and ST3. However, only two studies from India are available on subtypes in humans, to my knowledge, and so we need much more data to draw conclusions.

The last paper that I'm going to address is one by Zanzani and colleagues. When I read the abstract I almost dislocated my lower jaw from stupefaction: Studying the gastrointestinal parasitic fauna of captive non-human primates (Macaca fascicularis), they found a variety of protozoa and helminths, which is not surprising at all. Neither is it surprising that most macaques were positive for Blastocystis. Now, what really made my jaw drop was the fact their data on the subtypes found in the macaques challenged the host specificity of Blastocystis identified so far: They reported finding ST1, ST2, ST3, ST5, and ST7. And so, I had a closer look at the methods used to obtain data on subtypes. I take the liberty of questioning the data, since the authors report using a set of primers for amplification of Blastocystis DNA targeting the SSU rRNA gene, while using the STS primers developed by Yoshikawa et al. as sequencing primers! I guess that it is possible that the description of the methods was flawed (should have been picked up by the reviewer though), in which case I hope that an erratum will be developed and published.

References:

Das R, Khalil S, Mirdha BR, Makharia GK, Dattagupta S, & Chaudhry R (2016). Molecular Characterization and Subtyping of Blastocystis Species in Irritable Bowel Syndrome Patients from North India. PloS One, 11 (1) PMID: 26784888  

Kurt Ö, Doğruman Al F, & Tanyüksel M (2016). Eradication of Blastocystis in humans: Really necessary for all? Parasitology International PMID: 26780545

Pandey PK, Verma P, Marathe N, Shetty S, Bavdekar A, Patole MS, Stensvold CR, & Shouche YS (2015). Prevalence and subtype analysis of Blastocystis in healthy Indian individuals. Infection, Genetics and Evolution: Journal of Molecular Epidemiology and Evolutionary Genetics in Infectious Diseases, 31, 296-9 PMID: 25701123  

Zanzani SA, Gazzonis AL, Epis S, & Manfredi MT (2016). Study of the gastrointestinal parasitic fauna of captive non-human primates (Macaca fascicularis). Parasitology Research, 115 (1), 307-12 PMID: 26374536  

Yoshikawa H, Wu Z, Kimata I, Iseki M, Ali IK, Hossain MB, Zaman V, Haque R, & Takahashi Y (2004). Polymerase chain reaction-based genotype classification among human Blastocystis hominis populations isolated from different countries. Parasitology Research, 92 (1), 22-9 PMID: 14598169

Tuesday, December 29, 2015

This Month in Blastocystis Research (DEC 2015)

The potential pathogenicity of Blastocystis is something that has kept me preoccupied for more than a decade. Nonetheless, what I find perhaps even more interesting, is the overall role of Blastocystis in both health and disease.

And so, what do I mean by that?

Well, we just published a MiniReview in Journal of Clinical Microbiology (JCM) with the title: "Blastocystis in Health and Disease--Are we Moving from a Clinical to A Public Health Perspective?" I guess we were a bit lucky to get the paper published as a review, since it's probably more likely to be viewed upon as an Opinion paper, and so it would perhaps have been more suitable for a journal such as Trends in Parasitology. However, we would like medical doctors to be aware of our thoughts, and that's one of the reasons why we approached JCM.

Practically all Blastocystis research has focussed on identifying a role for the parasite in disease. Pathogenic properties have been identified for many other intestinal parasites since long; for Blastocystis, however, we still have no rockhard and reproducible evidence of
  • Outbreaks
  • Virulence-assoicated properties including invasiveness, phagocytosis, or adhesion to other cells
  • Symptom relief upon parasite eradication
Meanwhile, no one has really tried to looked into what Blastocystis may tell us about human health. Together with partner labs, our lab has produced data suggesting that Blastocystis carriage is extremely common, and probably also extremely long lasting. We have also shown that the parasite is associated with certain gut microbial communities and that it is more common in healthy individuals than in patients with IBD, IBS, etc. We have even identified intriguing data that suggest that Blastocystis may be less common in obese individuals compared with lean.



These are some of the most important reasons why I think that research into the public health significance of Blastocystis should be supported. We need to know much about what it means physiologically, microbiologically, and immunologically to be colonised, including 'what happens to our intestinal ecosystem when we are exposed to and colonised by Blastocystis?' Can we identify any benefits from colonisation, and if yes, which are these and can this knowledge be exploited with a view to producing drugs/probiotics that mimic any beneficient properties of Blastocystis? What does it mean to become colonised at an early age vs. only later in life?

In this regard, future areas of research could include studies on the ability of Blastocystis to
  • induce changes in bacterial communities in vitro and in vivo
  • assist in the metabolisation of food items (e.g., short-chain fatty acid metabolism)
  • promote stabilisation of gut microbiota
  • produce immunomodulatory and/or pro-/antibiotic substances, etc.

Happy New Year everone!

Reference:

Andersen LO & Stensvold CR (2015). Blastocystis in Health and Disease–Are We Moving from a Clinical to a Public Health Perspective? Journal of Clinical Microbiology PMID: 26677249

Tuesday, December 1, 2015

This Month in Blastocystis Research (NOV 2015) - Persian Gulf Edition

Today is the first time an Airbus A380 will be landing in Copenhagen Airport, Denmark. Flying in from Dubai, it will mark the inauguration of a runway that was recently refurbished to enable accommodation of a plane of this size.

I therefore thought I'd make a tribute to this particular day by dedicating the "This Month in Blastocystis Research" post to studies on Blastocystis recently published by researchers based along the Persian Gulf. Three surveys on Blastocystis from this region recently made it to parasite/microbiology research journals. The studies are important since they represent examples of studies employing molecular tools for screening and molecular characterisation of parasite isolates identified in regions where such data are extremely scarce. Some of these data will enable us to better understand host specificity, differences in geographic distribution, clinical and public health significance, and transmission patterns.

 The first study was on Blastocystis in Qatar and published in Acta Tropica; it was already mentioned in my September blog entry.

I was lucky to be involved in the second study, which was a study carried out in Sharjah, United Arab Emirates, and designed by Ali ElBakri and colleagues. In this study, we screened a total of 133 samples from ex-pats living in Sharjah, subtyping the samples positive for Blastocystis using partial small subunit (SSU) ribosomal RNA gene sequencing. Fifty-nine (44.4%) samples were positive, of which 39 were successfully sequenced and subtyped. The ST distribution was as follows: ST3, 58.9% (23/39); ST1, 28.2% (11/39); and ST2, 7.6% (3/39). This study is the first to provide data on the prevalence of Blastocystis and the distribution of various STs in the UAE. As usual, ST4 was absent, while ST1, ST2, and ST3 were all common in this geographical region; a situation similar to most other regions outside of Europe.

The third study was from the city of Baghmalek in Southwestern Iran, and was published by Khoshnood and colleagues in Jundishapur Journal of Microbiology. This team used microscopy to identify Blastocystis in 1,410 stool samples from patients presumably suffering gastrointestinal symptoms. A very low prevalence was identified, about 3%. This low figure most likely reflects the use of microscopy, which is an extremely insensitive diagnostic method. From Blastocystis-positive samples, DNA was extracted and submitted to PCR and sequencing targeting the (SSU) ribosomal RNA gene. It says in the article that the subtypes identified in the study included "ST3, ST4, ST5, and ST7 with the most prevalent being ST4 (40.9%)", and the main conclusion is that, unlike the situation in other countries in the Middle East, ST4 was identified as the most prevalent subtype.

There are at least two conspicuous situations here: The first one pertains to the rather unusual subtype distribution reported, which appears quite dissimilar to the ones reported from neighbouring countries. The next one is even more odd and pertains to the fact that the sequences (AB915194 - AB915214) generated in the study, and from which the subtype data must have been inferred, do not BLAST to other nuclear ribosomal RNA gene sequences in GenBank, of which there are thousands! In fact, AB915194 represents a protein-coding gene, translating into  

S P Y L L S I S T E E S Y T D S H Y Y G E C T T I A Q S I Y H Q S S K S V E A S I W D C V Y Met T L I Y E G V T D L T Y D E M K A S Y T D P V E T L T V L G K Y P G A D I S G I S L D L V F G Y I G R G I P V I S R I N D G R Y V L I V S Y N S E A V R Y Y D P V L D E Q V R K Q

... which is a Clostridium hypothetical protein with a peptidase domain! This may either reflect an error linked to the accession numbers, or it may reflect a situation where for some reason non-ribosomal DNA sequences were uploaded to GenBank. Given the appearance of the phylogeny included in the article, it could easily be suspected that the sequences produced and used were in fact non-Blastocystis DNA sequences, in which case the paper should be retracted. Before this mystery has been solved, the results of the Iranian study cannot be fully appreciated, and the relevance of citing the study appears very limited for now.

The last study highlights the importance of making sequence data publicly available; if these data had not been available for critical appraisal, the conclusions made in this article could easily have been accepted without any further ado!

References:

Abu-Madi M, Aly M, Behnke JM, Clark CG, & Balkhy H (2015). The distribution of Blastocystis subtypes in isolates from Qatar. Parasites & Vectors, 8 PMID: 26384209

AbuOdeh R, Ezzedine S, Samie A, Stensvold CR, & ElBakri A (2015). Prevalence and subtype distribution of Blastocystis in healthy individuals in Sharjah, United Arab Emirates. Infection, Genetics and Evolution: Journal of Molecular Epidemiology and Evolutionary Genetics in Infectious Diseases PMID: 26611823 

Khoshnood S, Rafiei A, Saki J, & Alizadeh K (2015). Prevalence and Genotype Characterization of Blastocystis hominis Among the Baghmalek People in Southwestern Iran in 2013 - 2014. Jundishapur Journal of Microbiology, 8 (10) PMID: 26587213 

Sunday, November 1, 2015

This Month in Blastocystis Research (OCT 2015)

I'm actually going to skip the small review I do each month for a variety of reasons. Instead, I'm just going to upload a presentation I gave in Tilburg, The Netherlands, a bit more than a week ago, before attending the UEG Week in Barcelona.

I uploaded it to Google Drive, hoping that it will be easy to download for everyone interested. I have not included any notes, hoping that the slides will be pretty much self-explanatory.

I think there is even a bit of Danish in there, - hope you don't mind! Also, the preview option does not work very well, so make sure you download it.

If the presentation left you wondering a bit and wish for more, why not look up my publications listed in PubMed? They are available here.  Some of them can be downloaded for free.

Thank you for your attention.

Monday, October 5, 2015

This Month in Blastocystis Research (SEP 2015)

The month of September saw the publication of the first data on Blastocystis subtypes going out from Qatar. Abu-Madi and colleagues--who have already been quite prolific in terms of surveying intestinal parasitic infections in Qatar--studied the positive rate of Blastocystis in 608 apparently healthy subjects arriving in Qatar for the first time, identifying a prevalence of 71% as identified by PCR. Strikingly, the positive rate by microscopy of the corresponding samples was only 7%. Three subtypes were idenfied, with ST3 being the most common subtype, followed in prevalence by ST1 and ST2. The study is important for at least two reasons: It confirms the drawback of basing Blastocystis epidemiological research on data generated using microscopy alone, and it confirms the virtual absence of ST4 outside of Europe.

Increased sensitivity of PCR relative to microscopy was also confirmed in a study carried out in Malaysia (I presume) by Ragavan and colleagues. This group surveyed the Blastocystis positivity rate among IBS and non-IBS patients analyzing colonic aspirates, including a total of 109 individuals. Given the data available on Blastocystis prevalence, I was quite surprised to learn that this group failed to detect Blastocystis in any of the samples by microscopy and culture. Using PCR (the subtype-specific [STS] primers were used as diagnostic primers), the group identified Blastocystis in 6 IBS patients and 4 non-IBS patients. Also these figures appear quite low. However, there is very little information available on the non-IBS patients, and since all study individuals were subject to colonscopy, this group of individuals might be suffering chronic and potentially severe intestinal disease, including for instance colorectal cancer, inflammatory bowel disease, etc., which would explain the low prevalence of Blastocystis observed among these individuals. Indeed, evidence is accumulating that the more "gut healthy" you are, the larger the probability of being Blastocystis-positive. I noticed that the colonic aspirates were spun down using 3,000 rpm prior to culture and microscopy; this process might have had an impact on cell viability and morphology; still, DNA should be detectable following this process. Meanwhile, we recently showed (Scanlan et al., 2015) that the sensitivity of the STS primers is relatively low, which is why the use of real-time PCR is recommendable for PCR-based screening. To see an example of how the STS primers perform relative to barcoding primers, go here (Suppl Table 2).
Moreover, care should be taken when reading this paper, since I'm fairly convinced that the subtype terminology used in the study is different from the consensus terminology (Stensvold et al., 2007). It says that the subtypes detected included ST2, ST3, ST4, and ST5; if this reflects the terminology that went along with the original description of the STS primers, these subtypes correspond to ST7, ST3, ST6, and ST2, which to me would be a more likely subtype distribution, taking this particular region into consideration, and given the fact that ST5 appears to be extremely rare in humans. 

It's always interesting to expand on the natural host spectrum of Blastocystis. The parasite has been found in a perplexing array of hosts, but some host specificity has been observed. When it comes to animals held by humans as livestock or pets, we know that pigs and cattle are commonly, if not consistently, colonised by Blastocystis with some quite specific subtypes. With regard to pets, dogs and cats have been found positive, but there seems to be increasing evidence that these animals are not natural hosts (see also Wang et al., 2013). Osman and colleagues, recently published a survey on Cryptosporidium and Blastocystis in dogs using sensitive molecular methods, demonstrating a prevalence of Blastocystis of only about 3%. Moreover, the subtypes 2 and 10 were found, and ST10 is found mostly in cattle, and never before in dogs, as far as I know, which could suggest accidental colonisation - and possibly not a very long-lasting one. Similarly, when humans are found to be colonised with subtypes rarely found in humans, such as ST6, ST7, and ST8, it would be interesting to know for how long these subtypes are capable of "staying put" in the human intestine.

References

Abu-Madi M, Aly M, Behnke JM, Clark CG, & Balkhy H (2015). The distribution of Blastocystis subtypes in isolates from Qatar. Parasites & Vectors, 8 PMID: 26384209

Osman M, Bories J, El Safadi D, Poirel MT, Gantois N, Benamrouz-Vanneste S, Delhaes L, Hugonnard M, Certad G, Zenner L, & Viscogliosi E (2015). Prevalence and genetic diversity of the intestinal parasites Blastocystis sp. and Cryptosporidium spp. in household dogs in France and evaluation of zoonotic transmission risk. Veterinary Parasitology PMID: 26395822   

Ragavan, N., Kumar, S., Chye, T., Mahadeva, S., & Shiaw-Hooi, H. (2015). Blastocystis sp. in Irritable Bowel Syndrome (IBS) - Detection in Stool Aspirates during Colonoscopy PLOS ONE, 10 (9) DOI: 10.1371/journal.pone.0121173  

Scanlan PD, Stensvold CR, & Cotter PD (2015). Development and Application of a Blastocystis Subtype-Specific PCR Assay Reveals that Mixed-Subtype Infections Are Common in a Healthy Human Population. Applied and Environmental Microbiology, 81 (12), 4071-6 PMID: 25841010   

Stensvold CR, Suresh GK, Tan KS, Thompson RC, Traub RJ, Viscogliosi E, Yoshikawa H, & Clark CG (2007). Terminology for Blastocystis subtypes--a consensus. Trends in Parasitology, 23 (3), 93-6 PMID: 17241816

Wang W, Cuttell L, Bielefeldt-Ohmann H, Inpankaew T, Owen H, & Traub RJ (2013). Diversity of Blastocystis subtypes in dogs in different geographical settings. Parasites & vectors, 6 PMID: 23883734

Wednesday, July 1, 2015

This Month in Blastocystis Research (JUN 2015)

I started developing this blog more than three years ago. After a bit more than a year, I collected a bunch of the posts, edited them and published them as a book on Amazon. Recently, I logged into my Amazon profile to see how the book was doing, and I was very pleased to notice that there were no less than four reviews of the book, and very positive ones too! Thank you to everyone who read/browsed it.

Blastocystis research is currently a quickly moving field, and I'm please to be able to inform you that one of the most interesting contributions to Blastocystis research coming out from our intstitute has just been published in Fems Microbiology Ecology. The article appearing in this journal was first-authored by PhD student Lee O'Brien Andersen (Statens Serum Institut) and post doc Ida Bonde (Danish Technical University) and describes how Lee and Ida took a retrospective approach to analysing metagenomics data originally generated by the MetaHIT Consortium and published in the often cited paper by Arumugam et al. (2012).

The abstract reads as follows:
Blastocystis is a common single-celled intestinal parasitic genus, comprising several subtypes. Here, we screened data obtained by metagenomic analysis of faecal DNA for Blastocystis by searching for subtype-specific genes in co-abundance gene groups, which are groups of genes that co-vary across a selection of 316 human faecal samples, hence representing genes originating from a single subtype. The 316 faecal samples were from 236 healthy individuals, 13 patients with Crohn's disease (CD), and 67 patients with ulcerative colitis (UC). The prevalence of Blastocystis was 20.3% in the healthy individuals and 14.9% in patients with UC. Meanwhile, Blastocystis was absent in patients with CD. Individuals with intestinal microbiota dominated by Bacteroides were much less prone to having Blastocystis-positive stool (Matthew's correlation coefficient = -0.25, P < 0.0001) than individuals with Ruminococcus- and Prevotella-driven enterotypes. This is the first study to investigate the relationship between Blastocystis and communities of gut bacteria using a metagenomics approach. The study serves as an example of how it is possible to retrospectively investigate microbial eukaryotic communities in the gut using metagenomic datasets targeting the bacterial component of the intestinal microbiome and the interplay between these microbial communities.

As far as we know this is the first study to sift out data on Blastocystis from data originally intended for analysis of bacterial communities only, and in the paper we describe how this was done. We believe that this approach has imminent potential for quickly advancing our knowledge on Blastocystis in a gut ecology context, including knowledge on the role of Blastocystis in terms of impacting/manipulating one or more types of intestinal bacteria.

I have a feeling that this is the first study in a string of similar studies that will soon hit PubMed, and within a year or two, we should be able to with confidence to hypothesise on the relationship between the structure and function on of the gut microbiota and Blastocystis, and–hopefully–other intestinal micro-eukaryotes.

Lastly, it was very interesting to note the article by Paramsothy et al. on donor recruitment for faecal microbiota transplantation (FMT; never heard of this? Watch the video below to learn more), recently appearing in the journal Inflammatory Bowel Disease. The study is interesting because it shows that most FMT donors are seemingly ineligible due to a variety of reasons, including colonisation by intestinal parasites such as Blastocystis... Given emerging data suggesting that Blastocystis is more common in healthy invididuals than in patients with gastrointestinal disease, the question remains whether Blastocystis-positivity should be a limiting factor for stool donation?



References:

Andersen LO, Bonde I, Nielsen HB, Stensvold CR. A retrospective metagenomics approach to studying Blastocystis. Published online 30 June 2015. DOI: http://dx.doi.org/10.1093/femsec/fiv072

Paramsothy S, Borody TJ, Lin E, Finlayson S, Walsh AJ, Samuel D, van den Bogaerde J, Leong RW, Connor S, Ng W, Mitchell HM, Kaakoush N, & Kamm MA (2015). Donor Recruitment for Fecal Microbiota Transplantation. Inflammatory bowel diseases, 21 (7), 1600-6 PMID: 26070003

Thursday, April 30, 2015

This Month in Blastocystis Research (APR 2015)

#ECCMID2015 took place in Copenhagen. It was a great venue with a lot of interesting sessions. My favourite presentation was by Dr Paul D Cotter. We have had the pleasure of doing some work together with Dr Pauline D Scanlan as the main driving force. In his talk, Dr Cotter highlighted the emergence of research exploring whether certain organisms are pathobionts or probionts; among these, Blastocystis. Among many things, Dr Cotter reviewed the two recent Blastocystis-specific publications by Scanlan et al. focusing on the commonness and stability of Blastocystis colonisation [1] and on the need to use subtype-specific PCRs to detect and identify mixed subtype colonisation/infection [2].

Based at TEAGASC - Ireland, the Cotter/Scanlan group is one of the teams interested in looking into the ecology of Blastocystis (and other microbial eukaryotes of the gut), including its influence of the parasite on gut microbiota/microbiome (structure and function of our all gut organisms) and vice versa, and I'm sure that there will be a lot of interesting data coming out from their lab in the near future.

Cotter mentioned that Blastocystis has been subject to bad science. This may be due to a number of reasons. When developing hypotheses, we have a tendency of opting for dichotomous outcomes - either it is this or that, - maybe that's the very nature of hypotheses. If the clinical significance of Blastocystis is dependent on a number of different things such as co-colonising microbes (cross-talk), differences in host immunity response, Blastocystis subtype, and host diet for instance, then the true tapestry of physiological/biological/clinical mechanisms is likely to be extremely difficult to uncover. Moreover, despite the fact that so many people are curious about the public health significance of Blastocystis, apparently very little funding for targeted Blastocystis research exists. This means that mostly minor and not so significant studies ("cheap studies") on Blastocystis are available. Relatively little seminal research has been done in the clinical field (including the field of gastroenterology), and most studies on Blastocystis are cross-sectional and descriptive and usually not very well designed/carried out (use of diagnostic tools with limited sensitivity, for instance).

Maybe things will change when more and more people realise that we might be able to use Blastocystis as a biomarker/surrogate marker of intestinal homeostasis...

In my opinion the following topics would make for good research projects:

1) Large studies of both diseased cohorts and healthy individuals, including Blastocystis subtype data and data on accompanying protists, bacteria and fungi (16S/18S/ITS profiling).
2) Manipulaton studies where Blastocytsis (cysts) are introduced in ecosystems (in vitro or in vivo) to monitor potential changes.
3) Animal models using cyst challenge (to look at microbiota profile changing upon challenge, and, if in vivo colitis models are used, impact on host immunity)
4) Longitudinal microbiome studies of patients with and without Blastocystis.
5) Investigation of Blastocystis as a biomarker/surrogate marker of microbiota profiles and gut microbiome homeostasis... similar to my recent blog post: 'Show me your gut bacteria, and I'll tell you if you have Blastocystis!'
6) Comparative genomics (virulence gene identification for instance).
7) Identification of Blastocystis-specific signatures in metagenomics data sets.
8) Identification of drugs that have anti-Blastocystis properties, since currently, there is no drug regimen that consistently enables eradication of Blastocystis.

Speaking of which: We just published data in Journal of Ethnopharmacology on the anti-Blastocystis activity of 24 plant parts from 21 medicinal plants from Ghana [3]. We performed in vitro challenge of 48 h Blastocystis cultured cells (subtype 4) using ethanolic, warm and cold water plant extracts. Screening of these 24 different plant parts showed significant anti-Blastocystis activity of six of the ethanolic extracts: Mallotus oppositifolius, IC50, 24h 27.8 µg/mL; Vemonia colorata, IC50, 24h 117.9 µg/mL; Zanthoxylum zanthoxyloides, cortex IC50, 24h 255.6 µg/mL; Clausena anisata, IC50, 24h 314.0 µg/mL; Z. zanthoxyloides, radix IC50, 24h 335.7 µg/mL and Eythrina senegalensis, IC50, 24h 527.6 µg/mL. The reference anti-protozoal agent metronidazole (MTZ) had an IC50, 24h of 7.6 µg/mL. Since cultures were xenic, antimicrobial activity was tested against two Gram-positive and two Gram-negative bacteria for all 24 plant parts at a final concentration of 1 mg/mL. Only C. anisata showed antimicrobial activity at a concentration of 800 µg/mL.

Hence, M. oppositifolius showed nearly as good activity as the reference anti-protozoal drug MTZ. Historically, the active plants found in this study have been used against dysentery, diarrhoea or other stomach disorders. Nowadays they are not used specifically for dysentery, but they are being used as medicinal plants against various stomach disorders.

Our book 'Biology of Foodborne Parasites' is out and available for ordering.

Incidentally, Blastocystis earned a designated chapter in the book 'Biology of Foodborne Parasites' which is now out and available for ordering here. It was fun writing it up, and hope that the chapter will be of interest to health care professionals and students around the world. The book also contains  introductions to the public health importance of foodborne parasites, molecular biological techniques in studies of foodborne parasites, and detection of parasites in foods.

References:

[1] Scanlan PD, Stensvold CR, Rajilić-Stojanović M, Heilig HG, De Vos WM, O'Toole PW, & Cotter PD (2014). The microbial eukaryote Blastocystis is a prevalent and diverse member of the healthy human gut microbiota. FEMS Microbiology Ecology, 90 (1), 326-30 PMID: 25077936   

[2] Scanlan PD, Stensvold CR, & Cotter PD (2015). Development and application of Blastocystis subtype-specific PCR reveals that mixed subtype infections are common in a healthy human population. Applied and Environmental Microbiology PMID: 25841010

[3] Bremer Christensen C, Soelberg J, Stensvold CR, & Jäger AK (2015). Activity of medicinal plants from Ghana against the parasitic gut protist Blastocystis. Journal of Ethnopharmacology PMID: 25773490