Protists are a normal component of mammalian intestinal ecosystems that live alongside, and interact with, bacterial microbiota. Blastocystis, one of the most common intestinal eukaryotes, is reported as a pathogen that causes inflammation and disease, though health consequences likely vary depending on host health, the gut ecosystem, and genetic diversity. Accumulating evidence suggests that Blastocystis is by and large commensal. Blastocystis is more common in healthy individuals than those with immune mediated diseases such as Inflammatory Bowel Diseases (IBD). Blastocystis presence is also associated with altered composition and higher richness of the bacterial gut microbiota. It is not clear whether Blastocystis directly promotes a healthy gut and microbiome or is more likely to colonize and persist in a healthy gut environment. We test this hypothesis by measuring the effect of Blastocystis ST3 colonization on the health and microbiota in a rat experimental model of intestinal inflammation using the haptenizing agent dinitrobenzene sulfonic acid (DNBS). We experimentally colonized rats with Blastocystis ST3 obtained from a healthy, asymptomatic human donor and then induced colitis after 3 weeks (short term exposure experiment) or after 13 weeks (long term exposure experiment) and compared these colonized rats to a colitis-only control group. Across experiments Blastocystis ST3 colonization alters microbiome composition, but not richness, and induces only mild gut inflammation but no clinical symptoms. Our results showed no effect of short-term exposure to Blastocystis ST3 on gut inflammation following colitis induction. In contrast, long-term Blastocystis exposure appears to promote a faster recovery from colitis. There was a significant reduction in inflammatory markers, pathology 2 days after colitis induction in the colonized group, and clinical scores also improved in this group. Blastocystis colonization resulted in a significant reduction in tumor necrosis factor alpha (TNFα) and IL-1β relative gene expression, while expression of IFNγ and IL17re/17C were elevated. We obtained similar results in a previous pilot study. We further found that bacterial richness rebounded in rats colonized by Blastocystis ST3. These results suggest that Blastocystis sp. may alter the gut ecosystem in a protective manner and promote faster recovery from disturbance.

Department of Botany University of British Columbia Vancouver BC Canada

Department of Medical Biology Faculty of Science University of South Bohemia České Budějovice Czechia

Department of Pathology and Parasitology University of Veterinary and Pharmaceutical Sciences Brno Brno Czechia

Department of Zoology Biodiversity Research Centre University of British Columbia Vancouver BC Canada

Institute of Parasitology Biology Centre Czech Academy of Sciences České Budějovice Czechia

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Abdel-Hafeez E. H., Ahma A., Abdelgelil H. N., Abdellatif M. Z. N., Kamal A. M., Hassanin K. M. A., et al. (2016). Immunopathohistological assesments of human Blastocystis spp. in experimentally nfected immunocopetent and immunosuppressed mice. Parasitol. Res. 115 2061–2071. 10.1007/s00436-016-4951-3 PubMed DOI

Ajjampur S. S. R., Tan K. S. W. (2016). Pathogenic mechanisms in Blastocystis spp. interpreting results from in vitro and in vivo studies. Parasitol. Int. 65 772–779. 10.1016/j.parint.2016.05.007 PubMed DOI

Ajjampur S. S. R., Png C. W., Chia W. N., Zhang Y., Tan K. S. W. (2016). Ex vivo and in vivo mice models to study Blastocystis spp. adhesion, colonization and pathology: closer to proving Koch’s postulates. PLoS One 11:e160458. PubMed PMC

Andersen L. O. B., Stensvold C. R. (2016). Blastocystis in health and disease: are we moving from a clinical to a public health perspective? J. Clin. Microbiol. 54 524–528. 10.1128/jcm.02520-15 PubMed DOI PMC

Andersen L. O. B., Bonde I., Nielsen H. B., Stensvold C. R. (2015). A retrospective metagenomics approach to studying Blastocystis. FEMS Microbiol. Ecol. 91:fiv072. PubMed

Audebert C., Even G., Cian A., Loywick A., Merlin S., Viscogliosi E., et al. (2016). Colonization with the enteric protozoa Blastocystis is associated with increased diversity of human gut bacterial microbiota. Sci. Rep. 6: 25255. PubMed PMC

Bart A., Wentink-Bonnema E. M., Gilis H., Verhaar N., Wassenaar C. J., van Vugt M., et al. (2013). Diagnosis and subtype analysis of Blastocystis sp.in 442 patients in a hospital setting in the Netherlands. BMC Infect. Dis. 13:389. PubMed PMC

Beghini F., Pasolli E., Truong T. D., Putignani L., Cacciò S. M., Segata N. (2017). Large-scale comparative metagenomics of Blastocystis, a common member of the human gut microbiome. ISME J. 11 2848–2863. 10.1038/ismej.2017.139 PubMed DOI PMC

Callahan B. J., McMurdie P. J., Rosen M. J., Han A. W., Johnson A. J. A., Holmes S. P. (2016). DADA2: high-resolution sample inference from Illumina amplicon data. Nat. Methods 13 581–583. 10.1038/nmeth.3869 PubMed DOI PMC

Chabé M., Lokmer A., Ségurel L. (2017). Gut protozoa: friends or foes of the human gut microbiota? Trends Parasitol. 33 925–934. 10.1016/j.pt.2017.08.005 PubMed DOI

Chandramathi S., Suresh K. G., Mahmood A. A., Kuppusamy U. R. (2010). Urinary hyaluronidase activity in rats infected with Blastocystis hominis – evidence for invasion? Parasitol. Res. 106 1459–1463. 10.1007/s00436-010-1825-y PubMed DOI

Chandramathi S., Suresh K., Sivanandam S., Kuppusamy U. R. (2014). Stress exacerbates infectivity and pathogenicity of Blastocystis hominis: in vitro and in vivo evidences. PLoS One 9:e94567. 10.1371/journal.pone.0094567 PubMed DOI PMC

Comeau A. M., Douglas G. M., Langille M. G. I. (2017). Microbiome helper: a custom and streamlined workflow for microbiome research. mSystems 2 e127–e116. PubMed PMC

Defaye M., Nourrisson C., Baudu E., Lashermes A., Meynier M., Meleine M., et al. (2020). Fecal dysbiosis associated with colonic hypersensitivity and behavioral alterations in chronically Blastocystis-infected rats. Sci. Rep. 10:9146. PubMed PMC

Defaye M., Nourrisson C., Baudu E., Warwzyniak I., Bonnin V., Bonnet M., et al. (2018). Efficient and reproducible experimental infections of rats with Blastocystis spp. PLoS One 13:e0207669. 10.1371/journal.pone.0207669 PubMed DOI PMC

El Safadi D., Gaayeb L., Meloni D., Cian A., Poirier P., Wawrzyniak I., et al. (2014). Children of senegal river basin show the highest prevalence of Blastocystis sp. ever observed worldwide. BMC Infect. Dis. 14:1471–2334. PubMed PMC

Elwakil H. S., Hewedi I. H. (2010). Pathogenic potential of Blastocystis hominis in laboratory mice. Parasitol. Res. 107 685–689. 10.1007/s00436-010-1922-y PubMed DOI

Eri R., McGuckin M. A., Wadley R. (2012). T-cell transfer model of colitis: a great tool to assess the contribution of T cells in chronic intestinal inflammation. Methods Mol. Biol. 844 261–275. 10.1007/978-1-61779-527-5_19 PubMed DOI

Fitzgibbon G., Mills K. H. G. (2020). The microbiota and immune-mediated diseases: opportunities for therapeutic intervention. Eur. J. Immunol. 50 326–337. 10.1002/eji.201948322 PubMed DOI

Forsell J., Bengtsson-Palme J., Angelin M., Johansson A., Evengård B., Granlund M. (2017). The relation between Blastocystis and the intestinal microbiota in Swedish travelers. BMC Microbiol. 17:231. PubMed PMC

Gabrielli S., Furzi F., Fontanelli Sulekova L., Taliani G., Mattiucci S. (2020). Occurrence of Blastocystis-subtypes in patients from Italy revealed association of ST3 with a healthy gut microbiota. Parasite Epidemiol. Control 9:e00134. 10.1016/j.parepi.2020.e00134 PubMed DOI PMC

Gentekaki E., Curtis B. A., Stairs C. W., Klimeš V., Eliáš M., Salas-Leiva D. E., et al. (2017). Extreme genome diversity in the hyper-prevalent parasitic eukaryote Blastocystis. PLoS Biol. 15:e2003769. 10.1371/journal.pbio.2003769 PubMed DOI PMC

Hirano A., Umeno J., Okamoto Y., Shibata H., Ogura Y., Moriyama T., et al. (2018). Comparison of the microbial community structure between inflamed and non-inflamed sites in patients with ulcerative colitis. J. Gastroenterol. Hepatol. 33 1590–1597. 10.1111/jgh.14129 PubMed DOI

Iguchi A., Yoshikawa H., Yamada M., Kimata I., Arizono N. (2009). Expression of interferon gamma and proinflammatory cytokines in the cecal mucosa of rats experimentally infected with Blastocystis sp. strain RN94-9. Parasitol. Res. 105 135–140. 10.1007/s00436-009-1373-5 PubMed DOI

Jimenez-Gonzalez D. E., Martinez-Flores W. A., Reyes-Gordillo J., Ramirez-Miranda M. E., Arroyo-Escalante S., Romero-Valdovinos M., et al. (2012). Blastocystis infection is associated with irritable bowel syndrome in a Mexican patient population. Parasitol. Res. 110 1269–1275. 10.1007/s00436-011-2626-7 PubMed DOI

Jirků-Pomajbíková K., Jirků M., Levá J., Sobotková K., Morien E., Parfrey L. W. (2018). The benign helminth Hymenolepis diminuta ameliorates chemically induced colitis in a rat model system. Parasitology 145 1324–1335. 10.1017/s0031182018000896 PubMed DOI

Jones M. S., Whipps C. M., Ganac R. D., Hudson N. R., Boorom K. (2009). Association of Blastocystis subtype 3 and 1 with patients from an Oregon community presenting with chronic gastrointestinal illness. Parasitol. Res. 104 341–345. 10.1007/s00436-008-1198-7 PubMed DOI

Kabeerdoss J., Jayakanthan P., Pugazhendhi S., Ramakrishna B. S. (2015). Alterations of mucosal microbiota in the colon of patients with inflammatory bowel disease revealed by real time polymerase chain reaction amplification of 16S ribosomal ribonucleic acid. Indian J. Med. Res. 142 23–32. 10.4103/0971-5916.162091 PubMed DOI PMC

Krogsgaard L. R., Andersen L. O., Johannesen T. B., Engsbro A. L., Stensvold C. R., Nielsen H. V., et al. (2018). Characteristics of the bacterial microbiome in association with common intestinal parasites in irritable bowel syndrome. Clin. Trans. Gastroenterology 9:161. PubMed PMC

Krogsgaard L. R., Engsbro A. L., Stensvold C. R., Nielsen H. V., Bytzer P. (2015). The prevalence of intestinal parasites is not greater among individuals with irritable bowel syndrome: a population-based case-control study. Clin. Gastroenterol. Hepatol. 13 507–513. 10.1016/j.cgh.2014.07.065 PubMed DOI

Kumarasamy V., Kuppusamy U. R., Jayalakshmi P., Samudi C., Ragavan N. D., Kumar S. (2017). Exacerbation of colon carcinogenesis by Blastocystis sp. PLoS One 12:e183097. PubMed PMC

Lepczyńska M., Dzika E. (2019). The influence of probiotic bacteria and human gut microorganisms causing opportunistic infections on Blastocystis ST3. Gut Pathog. 11:6. 10.3390/microorganisms7010006 PubMed DOI PMC

Lepczyńska M., Białkowska J., Dzika E., Piskorz-Ogórek K., Korycińska J. (2017). Blastocystis: how do specific diets and human gut microbiota affect its development and pathogenicity? Eur. J. Clin. Microbiol. Infect. Dis. 36 1531–1540. 10.1007/s10096-017-2965-0 PubMed DOI PMC

Lhotská Z., Jirků M., Hložková O., Brožová K., Jirsová D., Stensvold C. R., et al. (2020). A study on the prevalence and subtype diversity of the intestinal protist Blastocystis sp. in a gut-healthy human population in the Czech Republic. Front. Cell. Infect. Microbiol. 10:579. PubMed PMC

Li J., Deng T., Li X., Cao G., Li X., Yan Y. (2013). A rat model to study Blastocytis subtype 1 infections. Parasitol. Res. 112 3537–3541. 10.1007/s00436-013-3536-7 PubMed DOI

Lim M. X., Png C. W., Tay C. Y. B., Teo J. D. W., Jiao H., Lehming N., et al. (2014). Differential regulation of proinflammatory cytokine expression by mitogen-activated protein kinases in macrophages in response to intestinal parasite infection. Infect. Immun. 82 4789–4801. 10.1128/iai.02279-14 PubMed DOI PMC

Lukeš J., Stensvold C. R., Jirků-Pomajbíková K., Wegener Parfrey L. (2015). Are human intestinal eukaryotes beneficial or commensals? PLoS Pathog. 11:1005039. PubMed PMC

Mardani Kataki M., Tavalla M., Beiromvand M. (2019). Higher prevalence of Blastocystis hominis in healthy individuals than patients with gastrointestinal symptoms from Ahvaz, southwestern Iran. Comp. Immunol. Microbiol. Infect. Dis. 65 160–164. 10.1016/j.cimid.2019.05.018 PubMed DOI

Mattiucci S., Crisafi B., Gabrielli S., Paoletti M., Cancrini G. (2016). Molecular epidemiology and genetic diversity of Blastocystis infection in humans in Italy. Epidemiol. Infect. 144 635–646. 10.1017/s0950268815001697 PubMed DOI

Moe K. T., Singh M., Howe J., Ho L. C., Tan S. W., Chen X. Q., et al. (1997). Experimental Blastocystis hominis infection in laboratory mice. Parasitol. Res. 83 319–325. 10.1007/s004360050256 PubMed DOI

Nies J. F., Panzer U. (2020). IL-17C/IL-17RE: emergence of a unique axis in Th17 biology. Front. Immunol. 11:341. PubMed PMC

Nieves-Ramirez M. E., Partida-Rodriguez O., Laforest-Lapointe L. A., Reynolds L. A., Brown E. M., Morien E., et al. (2018). Asymptomatic intestinal colonization with protist Blastocystis. Host-Microbe Biol. 3:e00007-e18. PubMed PMC

Nourrisson C., Scanzi J., Pereira B., Nkoudmongo C., Wawrzyniak I., Cian A., et al. (2014). Blastocystis is associated with decrease of fecal microbiota protective bacteria: comparative analysis between patients with irritable bowel syndrome and control subjects. PLoS One 9:e111868. 10.1371/journal.pone.0111868 PubMed DOI PMC

Petersen A. M., Stensvold C. R., Mirsepasi H., Engberg J., Friis-Moller A., Porsbo L. J., et al. (2013). Active ulcerative colitis associated with low prevalence of Blastocystis and Dientamoeba fragilis infection. Scand. J. Gastroenterol 48 638–639. PubMed

Pfaffl M. W. (2001). A new mathematical model for relative quantification in real-time RT-PCR. Nucleic Acids Res. 29:e45. PubMed PMC

Poirier P., Wawrzyniak I., Vivarès C. P., Delbac F., El Alaoui H. (2012). New insights into Blastocystis spp.: a potential link with irritable bowel syndrome. PLoS Pathog. 8:e1002545. 10.1371/journal.ppat.1002545 PubMed DOI PMC

Poulsen C. S., Efunshile A. M., Nelson J. A., Stensvold C. R. (2016). Epidemiological aspects of Blastocystis colonization in children in Ilero. Nigeria. Am. J. Trop. Med. Hyg. 95 175–179. 10.4269/ajtmh.16-0074 PubMed DOI PMC

Quast C., Pruesse E., Yilmaz P., Gerken J., Schweer T., Yarza P., et al. (2013). The SILVA ribosomal RNA gene database project: improved data processing and web-based tools. Nucleic Acids Res. 41 590–596. PubMed PMC

R Core Team (2013). R: a Language and Environment for Statistical Computing. Vienna: R Foundation for statistical computing.

Ramirez-Carrozzi V., Sambandam A., Luis E., Lin Z., Jeet S., Lesch J., et al. (2011). IL-17C regulates the innate immune function of epithelial cells in an autocrine manner. Nat. Immunol. 12 1159–1166. 10.1038/ni.2156 PubMed DOI

Renelies-Hamilton J., Noguera-Julian M., Parera M., Paredes R., Pacheco L., Dacal E., et al. (2019). Exploring interactions between Blastocystis sp., Strongyloides spp. and the gut microbiomes of wild chimpanzees in Senegal. Infect. Genet. Evol. J. Mol. Epidemiol. Evol. Genet. Infect. Dis. 74:104010. 10.1016/j.meegid.2019.104010 PubMed DOI

Reynolds J. M., Martinez G. J., Nallaparaju K. C., Chang S. H., Wang Y.-H., Dong C. (2012). Regulation of intestinal inflammation and barrier function by IL-17C. J. Immunol. 189 4226–4230. 10.4049/jimmunol.1103014 PubMed DOI PMC

Rossen N. G., Bart A., Verhaar N., van Nood E., Kootte R., de Groot P. F., et al. (2015). Low prevalence of Blastocystis sp. in active ulcerative colitis patients. Eur. J. Clin. Microbiol. Infect. Dis. 34 1039–1044. 10.1007/s10096-015-2312-2 PubMed DOI PMC

Round J. L., Palm N. W. (2018). Causal effects of the microbiota on immune-mediated diseases. Sci. Immunol. 3:eaao1603. 10.1126/sciimmunol.aao1603 PubMed DOI

Růžková J., Květoňová D., Jirků M., Lhotská Z., Stensvold C. R., Parfrey L. W., et al. (2018). Evaluating rodent experimental models for studies of Blastocystis ST1. Exp. Parasitol. 191 55–61. 10.1016/j.exppara.2018.06.009 PubMed DOI

Salem F., Kindt N., Marchesi J. R., Netter P., Lopez A., Kokten T., et al. (2019). Gut microbiome in chronic rheumatic and inflammatory bowel diseases: similarities and differences. United Eur. Gastroenterol. J. 7 1008–1032. 10.1177/2050640619867555 PubMed DOI PMC

Scanlan P. D., Marchesi J. R. (2008). Micro-eukaryotic diversity of the human distal gut microbiota: qualitative assessment using culture-dependent and -independent analysis of faeces. ISME J. 2 1183–1193. 10.1038/ismej.2008.76 PubMed DOI

Scanlan P. D., Knight R., Song S. J., Ackermann G., Cotter P. D. (2016). Prevalence and genetic diversity of Blastocystis in family units living in the United States. Infect. Genet. Evol. 45 95–97. 10.1016/j.meegid.2016.08.018 PubMed DOI

Scanlan P. D., Stensvold C. R., Rajilić-Stojanović M., Heilig H. G. H. J., De Vos W. M., O’Toole P. W., et al. (2014). The microbial eukaryote Blastocystis is a prevalent and diverse member of the healthy human gut microbiota. FEMS Microbiol. Ecol. 90 326–330. 10.1111/1574-6941.12396 PubMed DOI

Segata N., Izard J., Waldron L., Gevers D., Miropolsky L., Garrett W. S., et al. (2011). Metagenomic biomarker discovery and explanation. Genome Biol. 12:R60. PubMed PMC

Seyer A., Karasartova D., Ruh E., Güreser A. S., Turgal E., Imir T., et al. (2017). Epidemiology and prevalence of Blastocystis spp. in North Cyprus. Am. J. Trop. Med. Hyg. 96 1164–1170. PubMed PMC

Siegwald L., Audebert C., Even G., Viscogliosi E., Caboche S., Chabé M. (2017). Targeted metagenomic sequencing data of human gut microbiota associated with Blastocystis colonization. Sci. Data 4:170081. PubMed PMC

Song X., Zhu S., Shi P., Liu Y., Shi Y., Levin S. D., et al. (2011). IL-17RE is the functional receptor for IL-17C and mediates mucosal immunity to infection with intestinal pathogens. Nat. Immunol. 12 1151–1158. 10.1038/ni.2155 PubMed DOI

Stensvold C. R., Clark C. G. (2016). Current status of Blastocystis: a personal view. Parasitol. Int. 65 763–771. 10.1016/j.parint.2016.05.015 PubMed DOI

Stensvold C. R., Clark C. G. (2020). Pre-empting Pandora’s box: Blastocystis subtypes revisited. Trends Parasitol. 36 229–232. 10.1016/j.pt.2019.12.009 PubMed DOI

Stensvold C. R., Tan K. S. W., Clark C. G. (2020). Blastocystis. Trends Parasitol. 36 315–316. PubMed

Tan T. C., Suresh K. G., Smith H. V. (2008). Phenotypic and genotypic characterization of Blastocystis hominis isolates implicates subtype 3 as a subtype with pathogenic potential. Parasitol. Res. 104 85–93. PubMed

Tito R. Y., Chaffron S., Caenepeel C., Lima-Mendez G., Wang J., Vieira-Silva S., et al. (2019). Population-level analysis of Blastocystis subtype prevalence and variation in the human gut microbiota. Gut 68 1180–1189. PubMed PMC

Wallace J. L., Le T., Carter L., Appleyard C. B., Beck P. L. (1995). Hapten-induced chronic colitis in the rat: alternatives to trinitrobenzene sulfonic acid. J. Pharmacol. Toxicol. Methods 33 237–239. PubMed

Wawrzyniak I., Poirier P., Texier C., Delbac F., Viscogliosi E., Dionigia M., et al. (2013). Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis. Ther. Adv. Infect. Dis. 1 167–178. PubMed PMC

Wong K. H. S., Ng G. C., Lin R. T. P., Yoshikawa H., Taylor M. B., Tan K. S. W. (2008). Predominance of subtype 3 among Blastocystis isolates from a major hospital in Singapore. Parasitol. Res. 102 663–670. PubMed

Wu Y. (2014). Barcode Demultiplex for Illumina I1, R1, R2 Fastq.gz Files. Available online at: https://github.com/yhwu (accessed November 20, 2017).

Yakoob J., Jafri W., Beg M. A., Abbas Z., Naz S., Islam M., et al. (2010). Irritable bowel syndrome: is it associated with genotypes of Blastocystis hominis. Parasitol Res. 106 1033–1038. PubMed

Yason J. A., Liang Y. R., Png C. W., Zhang Y., Tan K. S. W. (2019). Interactions between a pathogenic Blastocystis subtype and gut microbiota: in vitro and in vivo studies. Microbiome 7:30. PubMed PMC

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