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Int J Parasitol. 2017 May;47(6):311-326. doi: 10.1016/j.ijpara.2016.11.010. Epub 2017 Feb 22.

Giardia duodenalis induces pathogenic dysbiosis of human intestinal microbiota biofilms.

Author information

1
Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 4N1, Canada.
2
Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 4N1, Canada; Department of Physiology & Pharmacology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
3
Department of Medicine, Division of Gastroenterology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
4
Department of Medicine, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
5
Department of Physiology & Pharmacology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
6
Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 4N1, Canada; Department of Physiology & Pharmacology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada. Electronic address: aburet@ucalgary.ca.

Abstract

Giardia duodenalis is a prevalent cause of acute diarrheal disease worldwide. However, recent outbreaks in Italy and Norway have revealed a link between giardiasis and the subsequent development of chronic post-infectious irritable bowel syndrome. While the mechanisms underlying the causation of post-infectious irritable bowel syndrome remain obscure, recent findings suggest that alterations in gut microbiota communities are linked to the pathophysiology of irritable bowel syndrome. In the present study, we use a laboratory biofilm system to culture and enrich mucosal microbiota from human intestinal biopsies. Subsequently, we show that co-culture with Giardia induces disturbances in biofilm species composition and biofilm structure resulting in microbiota communities that are intrinsically dysbiotic - even after the clearance of Giardia. These microbiota abnormalities were mediated in part by secretory-excretory Giardia cysteine proteases. Using in vitro cell culture and germ-free murine infection models, we show that Giardia-induced disruptions of microbiota promote bacterial invasion, resulting in epithelial apoptosis, tight junctional disruption, and bacterial translocation across an intestinal epithelial barrier. Additionally, these dysbiotic microbiota communities resulted in increased activation of the Toll-like receptor 4 signalling pathway, and overproduction of the pro-inflammatory cytokine IL-1beta in humanized germ-free mice. Previous studies that have sought explanations and risk factors for the development of post-infectious irritable bowel syndrome have focused on features of enteropathogens and attributes of the infected host. We propose that polymicrobial interactions involving Giardia and gut microbiota may cause persistent dysbiosis, offering a new interpretation of the reasons why those afflicted with giardiasis are predisposed to gastrointestinal disorders post-infection.

KEYWORDS:

Biofilm; Gastrointestinal microbiome; Giardia duodenalis; Post-infectious irritable bowel syndrome

PMID:
28237889
DOI:
10.1016/j.ijpara.2016.11.010
[Indexed for MEDLINE]
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