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Ihara S, Nguyen BV, Miyamoto Y, Eckmann L. Mucosal vaccination in a murine gnotobiotic model of Giardia lamblia infection. Infect Immun 2024; 92:e0006524. [PMID: 38722167 PMCID: PMC11237505 DOI: 10.1128/iai.00065-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 04/10/2024] [Indexed: 06/12/2024] Open
Abstract
Giardia lamblia is an important protozoan cause of diarrheal disease worldwide, delayed development and cognitive impairment in children in low- and middle-income countries, and protracted post-infectious syndromes in developed regions. G. lamblia resides in the lumen and at the epithelial surface of the proximal small intestine but is not mucosa invasive. The protozoan parasite is genetically diverse with significant genome differences across strains and assemblages. Animal models, particularly murine models, have been instrumental in defining mechanisms of host defense against G. lamblia, but mice cannot be readily infected with most human pathogenic strains. Antibiotic pretreatment can increase susceptibility, suggesting that the normal microbiota plays a role in controlling G. lamblia infection in mice, but the broader implications on susceptibility to diverse strains are not known. Here, we have used gnotobiotic mice to demonstrate that robust intestinal infection can be achieved for a broad set of human-pathogenic strains of the genetic assemblages A and B. Furthermore, gnotobiotic mice were able to eradicate infection with a similar kinetics to conventional mice after trophozoite challenge. Germ-free mice could also be effectively immunized by the mucosal route with a protective antigen, α1-giardin, in a manner dependent on CD4 T cells. These results indicate that the gnotobiotic mouse model is powerful for investigating acquired host defenses in giardiasis, as the mice are broadly susceptible to diverse G. lamblia strains yet display no apparent defects in mucosal immunity needed for controlling and eradicating this lumen-dwelling pathogen.
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Affiliation(s)
- Sozaburo Ihara
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Brian V Nguyen
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Yukiko Miyamoto
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Lars Eckmann
- Department of Medicine, University of California San Diego, La Jolla, California, USA
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2
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DeMichele E, Sosnowski O, Buret AG, Allain T. Regulatory Functions of Hypoxia in Host-Parasite Interactions: A Focus on Enteric, Tissue, and Blood Protozoa. Microorganisms 2023; 11:1598. [PMID: 37375100 PMCID: PMC10303274 DOI: 10.3390/microorganisms11061598] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
Body tissues are subjected to various oxygenic gradients and fluctuations and hence can become transiently hypoxic. Hypoxia-inducible factor (HIF) is the master transcriptional regulator of the cellular hypoxic response and is capable of modulating cellular metabolism, immune responses, epithelial barrier integrity, and local microbiota. Recent reports have characterized the hypoxic response to various infections. However, little is known about the role of HIF activation in the context of protozoan parasitic infections. Growing evidence suggests that tissue and blood protozoa can activate HIF and subsequent HIF target genes in the host, helping or hindering their pathogenicity. In the gut, enteric protozoa are adapted to steep longitudinal and radial oxygen gradients to complete their life cycle, yet the role of HIF during these protozoan infections remains unclear. This review focuses on the hypoxic response to protozoa and its role in the pathophysiology of parasitic infections. We also discuss how hypoxia modulates host immune responses in the context of protozoan infections.
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Affiliation(s)
- Emily DeMichele
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Olivia Sosnowski
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Andre G. Buret
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Thibault Allain
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
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Grüttner J, van Rijn JM, Geiser P, Florbrant A, Webb DL, Hellström PM, Sundbom M, Sellin ME, Svärd SG. Trophozoite fitness dictates the intestinal epithelial cell response to Giardia intestinalis infection. PLoS Pathog 2023; 19:e1011372. [PMID: 37141303 DOI: 10.1371/journal.ppat.1011372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/16/2023] [Accepted: 04/18/2023] [Indexed: 05/06/2023] Open
Abstract
Giardia intestinalis is a non-invasive, protozoan parasite infecting the upper small intestine of most mammals. Symptomatic infections cause the diarrhoeal disease giardiasis in humans and animals, but at least half of the infections are asymptomatic. However, the molecular underpinnings of these different outcomes of the infection are still poorly defined. Here, we studied the early transcriptional response to G. intestinalis trophozoites, the disease-causing life-cycle stage, in human enteroid-derived, 2-dimensional intestinal epithelial cell (IEC) monolayers. Trophozoites preconditioned in media that maximise parasite fitness triggered only neglectable inflammatory transcription in the IECs during the first hours of co-incubation. By sharp contrast, "non-fit" or lysed trophozoites induced a vigorous IEC transcriptional response, including high up-regulation of many inflammatory cytokines and chemokines. Furthermore, "fit" trophozoites could even suppress the stimulatory effect of lysed trophozoites in mixed infections, suggesting active G. intestinalis suppression of the IEC response. By dual-species RNA-sequencing, we defined the IEC and G. intestinalis gene expression programs associated with these differential outcomes of the infection. Taken together, our results inform on how G. intestinalis infection can lead to such highly variable effects on the host, and pinpoints trophozoite fitness as a key determinant of the IEC response to this common parasite.
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Affiliation(s)
- Jana Grüttner
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Jorik M van Rijn
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Petra Geiser
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Alexandra Florbrant
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Dominic-Luc Webb
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, Uppsala, Sweden
| | - Per M Hellström
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, Uppsala, Sweden
| | - Magnus Sundbom
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Mikael E Sellin
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Staffan G Svärd
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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Buret AG, Allain T. Gut microbiota biofilms: From regulatory mechanisms to therapeutic targets. J Exp Med 2023; 220:e20221743. [PMID: 36688957 PMCID: PMC9884580 DOI: 10.1084/jem.20221743] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Gut microbiota contain communities of viruses, bacteria, fungi, and Eukarya, and live as biofilms. In health, these biofilms adhere to the intestinal mucus surface without contacting the epithelium. Disruptions to the equilibrium between these biofilms and the host may create invasive pathobionts from these commensal communities and contribute to disease pathogenesis. Environmental factors appear to dominate over genetics in determining the shifts in microbiota populations and function, including when comparing microbiota between low-income and industrialized countries. The observations discussed herein carry enormous potential for the development of novel therapies targeting phenotype in microbiota dysbiosis.
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Affiliation(s)
- Andre G. Buret
- Department of Biological Sciences, Host-Parasite Interactions program, Inflammation Research Network, University of Calgary, Calgary, Canada
| | - Thibault Allain
- Department of Biological Sciences, Host-Parasite Interactions program, Inflammation Research Network, University of Calgary, Calgary, Canada
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Zhao P, Li J, Li X, Dong J, Wang X, Zhang N, Li S, Sun M, Zhang X, Wang Z, Liang M, Li Y, Cao L, Gong P. The NLRP3 inflammasome recognizes alpha-2 and alpha-7.3 giardins and decreases the pathogenicity of Giardia duodenalis in mice. Parasit Vectors 2023; 16:85. [PMID: 36869360 PMCID: PMC9983531 DOI: 10.1186/s13071-023-05688-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 02/01/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Giardia duodenalis is a parasitic organism that can cause giardiasis, an intestinal infection, particularly prevalent in young children, with clinical symptoms of diarrhea. We previously reported that extracellular G. duodenalis triggers intracellular nucleotide-binding oligomerization-like receptor 3 (NLRP3) inflammasome activation and regulates the host inflammatory response by secreting extracellular vesicles (EVs). However, the exact pathogen-associated molecular patterns in G. duodenalis EVs (GEVs) involved in this process and the role of the NLRP3 inflammasome in giardiasis remain to be elucidated. METHODS Recombinant eukaryotic expression plasmids of pcDNA3.1(+)-alpha-2 and alpha-7.3 giardins in GEVs were constructed, transfected into primary mouse peritoneal macrophages and screened by measuring the expression levels of the inflammasome target molecule caspase-1 p20. The preliminary identification of G. duodenalis alpha-2 and alpha-7.3 giardins was further verified by measuring the protein expression levels of key molecules of the NLRP3 inflammasome (NLRP3, pro-interleukin-1 beta [IL-1β], pro-caspase-1, and caspase-1 p20), the secretion levels of IL-1β, the level of apoptosis speck-like protein (ASC) oligomerization and the immunofluorescence localization of NLRP3 and ASC. The roles of the NLRP3 inflammasome in G. duodenalis pathogenicity were then evaluated using mice in which NLRP3 activation was blocked (NLRP3-blocked mice), and body weight, parasite burden in the duodenum and histopathological changes in the duodenum were monitored. In addition, we explored whether alpha-2 and alpha-7.3 giardins triggered IL-1β secretion in vivo through the NLRP3 inflammasome and determined the roles of these molecules in G. duodenalis pathogenicity in mice. RESULTS Alpha-2 and alpha-7.3 giardins triggered NLRP3 inflammasome activation in vitro. This led to caspase-1 p20 activation, upregulation of the protein expression levels of NLRP3, pro-IL-1β and pro-caspase-1, significant enhancement of IL-1β secretion, ASC speck formation in the cytoplasm and also induction of ASC oligomerization. Deletion of the NLRP3 inflammasome aggravated G. duodenalis pathogenicity in mice. Compared to wild-type mice gavaged with cysts, mice gavaged with cysts in NLRP3-blocked mice displayed increased trophozoite loads and severe duodenal villus damage, characterized by necrotic crypts with atrophy and branching. In vivo assays revealed that alpha-2 and alpha-7.3 giardins could induce IL-1β secretion through the NLRP3 inflammasome and that immunization with alpha-2 and alpha-7.3 giardins decreased G. duodenalis pathogenicity in mice. CONCLUSIONS Overall, the results of the present study revealed that alpha-2 and alpha-7.3 giardins trigger host NLRP3 inflammasome activation and decrease G. duodenalis infection ability in mice, which are promising targets for the prevention of giardiasis.
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Affiliation(s)
- Panpan Zhao
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Jianhua Li
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Xin Li
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Jingquan Dong
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China.,Jiangsu Key Laboratory of Marine Bioresources and Environment, Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Jiangsu Ocean University, Lianyungang, 222005, Jiangsu Province, People's Republic of China
| | - Xiaocen Wang
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Nan Zhang
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Shan Li
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Min Sun
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Xichen Zhang
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Zhibang Wang
- College of Life Science, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Min Liang
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Ying Li
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China
| | - Lili Cao
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China. .,Jilin Academy of Animal Husbandry and Veterinary Medicine, Changchun, 130062, Jilin Province, People's Republic of China.
| | - Pengtao Gong
- State Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, 130062, Jilin Province, People's Republic of China.
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Yang D, Wang Z, Chen Y, Guo Q, Dong Y. Interactions between gut microbes and NLRP3 inflammasome in the gut-brain axis. Comput Struct Biotechnol J 2023; 21:2215-2227. [PMID: 37035548 PMCID: PMC10074411 DOI: 10.1016/j.csbj.2023.03.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 03/29/2023] Open
Abstract
The role of the gut-brain axis in maintaining the brain's and gut's homeostasis has been gradually recognized in recent years. The connection between the gut and the brain takes center stage. In this scenario, the nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome promotes inflammatory cell recruitment. It plays a crucial role in coordinating host physiology and immunity. Recent evidence shows how vital the gut-brain axis is for maintaining brain and gut homeostasis. However, more research is needed to determine the precise causal link between changed gut microbiota structure and NLRP3 activation in pathogenic circumstances. This review examines the connection between gut microbiota and the NLRP3 inflammasome. We describe how both dynamically vary in clinical cases and the external factors affecting both. Finally, we suggest that the crosstalk between the gut microbiota and NLRP3 is involved in signaling in the gut-brain axis, which may be a potential pathological mechanism for CNS diseases and intestinal disorders.
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Affiliation(s)
- Ding Yang
- College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Zixu Wang
- College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yaoxing Chen
- College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Qingyun Guo
- Milu conservation research unit, Beijing Milu Ecological Research Center, Beijing 100163, China
| | - Yulan Dong
- College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
- Corresponding author.
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7
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Dougherty M, Bartelt LA. Giardia and growth impairment in children in high-prevalence settings: consequence or co-incidence? Curr Opin Infect Dis 2022; 35:417-423. [PMID: 35980005 PMCID: PMC10373467 DOI: 10.1097/qco.0000000000000877] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE OF REVIEW Giardia is a common intestinal parasite worldwide, and infection can be associated with clear, and sometimes persistent symptomatology. However, in children in high-prevalence settings, it is most often not associated with or is perhaps even protective against acute diarrhea. Nonetheless, recent longitudinal studies in high-prevalence settings increasingly identify an association with long-term outcomes that has been difficult to discern. RECENT FINDINGS Recent studies have made progress in disentangling this apparent paradox. First, prospective, well characterized cohort studies have repeatedly identified associations between Giardia infection, gut function, and child growth. Second, experimental animal and in-vitro models have further characterized the biological plausibility that Giardia could impair intestinal function and subsequently child development through different pathways, depending upon biological and environmental factors. Finally, new work has shed light on the potential for Giardia conspiring with specific other gut microbes, which may explain discrepant findings in the literature, help guide future higher resolution analyses of this pathogen, and inform new opportunities for intervention. SUMMARY Recent prospective studies have confirmed a high, if not universal, prevalence of persistent Giardia infections in low-and-middle income countries associated with child-growth shortfalls and altered gut permeability. However, the predominance of subclinical infections limits understanding of the true clinical impact of endemic pediatric giardiasis, and global disease burdens remain uncalculated. Integrating the role of Giardia in multipathogen enteropathies and how nutritional, microbial, metabolic, and pathogen-strain variables influence Giardia infection outcomes could sharpen delineations between pathogenic and potentially beneficial attributes of this enigmatic parasite.
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Affiliation(s)
- Michael Dougherty
- Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina at Chapel Hill
- Rex Digestive Healthcare, UNC REX Healthcare, Raleigh
| | - Luther A. Bartelt
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Sardinha-Silva A, Alves-Ferreira EVC, Grigg ME. Intestinal immune responses to commensal and pathogenic protozoa. Front Immunol 2022; 13:963723. [PMID: 36211380 PMCID: PMC9533738 DOI: 10.3389/fimmu.2022.963723] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/15/2022] [Indexed: 11/17/2022] Open
Abstract
The physical barrier of the intestine and associated mucosal immunity maintains a delicate homeostatic balance between the host and the external environment by regulating immune responses to commensals, as well as functioning as the first line of defense against pathogenic microorganisms. Understanding the orchestration and characteristics of the intestinal mucosal immune response during commensal or pathological conditions may provide novel insights into the mechanisms underlying microbe-induced immunological tolerance, protection, and/or pathogenesis. Over the last decade, our knowledge about the interface between the host intestinal mucosa and the gut microbiome has been dominated by studies focused on bacterial communities, helminth parasites, and intestinal viruses. In contrast, specifically how commensal and pathogenic protozoa regulate intestinal immunity is less well studied. In this review, we provide an overview of mucosal immune responses induced by intestinal protozoa, with a major focus on the role of different cell types and immune mediators triggered by commensal (Blastocystis spp. and Tritrichomonas spp.) and pathogenic (Toxoplasma gondii, Giardia intestinalis, Cryptosporidium parvum) protozoa. We will discuss how these various protozoa modulate innate and adaptive immune responses induced in experimental models of infection that benefit or harm the host.
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Zhang X, Li X, Yu Y, Zhang X, Wang X, Zhang N, Chen M, Gong P, Li J. Giardia lamblia
regulates the production of proinflammatory cytokines through activating the NOD2–Rip2–ROS signaling pathway in mouse macrophages. Immunol Cell Biol 2022; 100:440-452. [DOI: 10.1111/imcb.12550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 02/17/2022] [Accepted: 03/31/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Xu Zhang
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Xin Li
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Yanhui Yu
- The Second Hospital of Jilin University Changchun Jilin 130021 China
| | - Xichen Zhang
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Xiaocen Wang
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Nan Zhang
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Mengge Chen
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Pengtao Gong
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
| | - Jianhua Li
- Key Laboratory of Zoonosis Research Ministry of Education College of Veterinary Medicine Jilin University 5333 Xian Road Changchun Jilin 130062 China
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Solaymani-Mohammadi S. Mucosal Defense Against Giardia at the Intestinal Epithelial Cell Interface. Front Immunol 2022; 13:817468. [PMID: 35250996 PMCID: PMC8891505 DOI: 10.3389/fimmu.2022.817468] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/31/2022] [Indexed: 02/05/2023] Open
Abstract
Human giardiasis, caused by the protozoan parasite Giardia duodenalis (syn. Giardia lamblia, Giardia intestinalis, Lamblia intestinalis), is one of the most commonly-identified parasitic diseases worldwide. Chronic G. duodenalis infections cause a malabsorption syndrome that may lead to failure to thrive and/or stunted growth, especially in children in developing countries. Understanding the parasite/epithelial cell crosstalk at the mucosal surfaces of the small intestine during human giardiasis may provide novel insights into the mechanisms underlying the parasite-induced immunopathology and epithelial tissue damage, leading to malnutrition. Efforts to identify new targets for intervening in the development of intestinal immunopathology and the progression to malnutrition are critical. Translating these findings into a clinical setting will require analysis of these pathways in cells and tissues from humans and clinical trials could be devised to determine whether interfering with unwanted mucosal immune responses developed during human giardiasis provide better therapeutic benefits and clinical outcomes for G. duodenalis infections in humans.
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Affiliation(s)
- Shahram Solaymani-Mohammadi
- Laboratory of Mucosal Immunology, Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States
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11
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Fekete E, Allain T, Amat CB, Mihara K, Saifeddine M, Hollenberg MD, Chadee K, Buret AG. Giardia duodenalis cysteine proteases cleave proteinase-activated receptor-2 to regulate intestinal goblet cell mucin gene expression. Int J Parasitol 2022; 52:285-292. [DOI: 10.1016/j.ijpara.2021.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 12/17/2022]
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12
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Zheng Z, Tang D, Zhao W, Wan Z, Yu M, Huang Z, Li L, Aweya JJ, Zhang Y. NLRP3-like protein negatively regulates the expression of antimicrobial peptides in Penaeus vannamei hemocyates. FISH AND SHELLFISH IMMUNOLOGY REPORTS 2021; 2:100039. [DOI: 10.1016/j.fsirep.2021.100039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/04/2021] [Accepted: 11/14/2021] [Indexed: 10/19/2022] Open
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Age and Giardia intestinalis Infection Impact Canine Gut Microbiota. Microorganisms 2021; 9:microorganisms9091862. [PMID: 34576757 PMCID: PMC8469385 DOI: 10.3390/microorganisms9091862] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 12/16/2022] Open
Abstract
Giardia intestinalis is a flagellated protozoan responsible for giardiosis (also called giardiasis in humans), the most prevalent and widespread parasitic infection in humans and mammals worldwide. The intestinal microbiota is highly diverse and any alteration in its composition may impact on the health of the host. While studies on the mouse model of giardiosis described the role of the gut microbiota in host susceptibility to infection by the parasite, little is known about the gut microbiota during natural infections in dogs and particularly in puppies. In this study, we monitored naturally G. intestinalis-infected puppies for 3 months and quantified cyst excretion every 2 weeks. All puppies remained subclinically infected during the sampling period as confirmed by fecal examination. In parallel, we performed 16S Illumina sequencing of fecal samples from the different time points to assess the impact of G. intestinalis infection on gut microbiota development of the puppies, as well as gut health markers of immunity such as fecal IgA and calprotectin. Sequencing results revealed that the canine fecal microbiota of Giardia-infected puppies becomes more complex and less diverse with increasing age. In addition, significant differences in the structure of the microbiota were observed between puppies with high and low Giardia cyst excretion. Chronic subclinical G. intestinalis infection appears to be associated with some detrimental structural changes in the gut microbiota. G. intestinalis-associated dysbiosis is characterized by an enrichment of facultative anaerobic, mucus-degrading, pro-inflammatory species and opportunistic pathogens, as well as a reduction of Lactobacillus johnsonii at specific time points. Calprotectin levels increased with age, suggesting the establishment of chronic low-grade inflammation in puppies. Further work is needed to demonstrate whether these alterations in the canine gut microbiota could lead to a dysbiosis-related disease, such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD).
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Abstract
Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a human pathogen until the 1960s, when outbreaks were reported. Key technological advances, including in vitro cultivation, genomic and proteomic databases, and advances in microscopic and molecular approaches, have led to an understanding that this is a eukaryotic organism with a reduced genome rather than a truly premitochondriate eukaryote. This has included the discovery of mitosomes (vestiges of mitochondria), a transport system with many of the features of the Golgi apparatus, and even evidence for a sexual or parasexual cycle. Cell biology approaches have led to a better understanding of how Giardia survives with two nuclei and how it goes through its life cycle as a noninvasive organism in the hostile environment of the lumen of the host intestine. Studies of its immunology and pathogenesis have moved past the general understanding of the importance of the antibody response in controlling infection to determining the key role of the Th17 response. This work has led to understanding of the requirement for a balanced host immune response that avoids the extremes of an excessive response with collateral damage or one that is unable to clear the organism. This understanding is especially important in view of the remarkable ranges of early manifestations, which range from asymptomatic to persistent diarrhea and weight loss, and longer-term sequelae that include growth stunting in children who had no obvious symptoms and a high frequency of postinfectious irritable bowel syndrome (IBS).
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15
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The risk factors for intestinal Giardia spp infection: Global systematic review and meta-analysis and meta-regression. Acta Trop 2021; 220:105968. [PMID: 34029531 DOI: 10.1016/j.actatropica.2021.105968] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 05/05/2021] [Accepted: 05/16/2021] [Indexed: 12/15/2022]
Abstract
Parasitic infections are a public health concern as they can cause aggression, growth retardation, weight loss, anemia, and other health problems. In this study, a systematic review and meta-analysis were performed to find an association between the probable social-environmental risk factors including lack of safe drinking water, no hand washing, sex, age, no access to education, no access to toilet, and Giardia spp infection. We conducted literature research among international databases including Scopus, PubMed, Web of Science and Cochrane from1 January 1995 to March 15, 2020, including 23 articles with 102 studies while the odds ratio (OR) was calculated using 2 × 2 tables or extracted. The pooled effect size with 95% confidence intervals (CIs) was estimated using a random or fixed-effects model. The results show a significant association between intestinal Giardia spp infection risk and lack of safe drinking water (OR: 1.14; 95%CI: 1.02-1.25); no access to toilet (OR: 1.22; 95%CI: 1.07-1.37); and age (2-10 vs 10-30 year) (OR: 1.42; 95%CI: 1.09-1.78). An insignificant association was observed between intestinal Giardia spp infection risk and age (<2 vs 2-10 year) (OR: 0.89; 95%CI: 0.75-1.02); no access to education (OR: 1.10; 95%CI: 0.80-1.40); Sex (male vs female) (OR: 1.04; 95%CI: 0.74-1.34); and no handwashing (OR: 1.18; 95%CI: 0.87-1.49). The results of meta-regression also indicate that intestinal Giardia spp infection has decreased over time (C= -0.024, p-value = 0.03) significantly, and also by growth of human development index (HDI) (C= - 0.42, p-value = 0.29) insignificantly. Improvement of personal hygiene, sanitation and raising public awareness can be effective in reducing Giardia spp infections.
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17
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Hoffmann W. Trefoil Factor Family (TFF) Peptides and Their Links to Inflammation: A Re-evaluation and New Medical Perspectives. Int J Mol Sci 2021; 22:ijms22094909. [PMID: 34066339 PMCID: PMC8125380 DOI: 10.3390/ijms22094909] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 12/16/2022] Open
Abstract
Trefoil factor family peptides (TFF1, TFF2, TFF3), together with mucins, are typical exocrine products of mucous epithelia. Here, they act as a gastric tumor suppressor (TFF1) or they play different roles in mucosal innate immune defense (TFF2, TFF3). Minute amounts are also secreted as endocrine, e.g., by the immune and central nervous systems. As a hallmark, TFF peptides have different lectin activities, best characterized for TFF2, but also TFF1. Pathologically, ectopic expression occurs during inflammation and in various tumors. In this review, the role of TFF peptides during inflammation is discussed on two levels. On the one hand, the expression of TFF1-3 is regulated by inflammatory signals in different ways (upstream links). On the other hand, TFF peptides influence inflammatory processes (downstream links). The latter are recognized best in various Tff-deficient mice, which have completely different phenotypes. In particular, TFF2 is secreted by myeloid cells (e.g., macrophages) and lymphocytes (e.g., memory T cells), where it modulates immune reactions triggering inflammation. As a new concept, in addition to lectin-triggered activation, a hypothetical lectin-triggered inhibition of glycosylated transmembrane receptors by TFF peptides is discussed. Thus, TFFs are promising players in the field of glycoimmunology, such as galectins and C-type lectins.
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Affiliation(s)
- Werner Hoffmann
- Institute of Molecular Biology and Medicinal Chemistry, Otto-von-Guericke University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
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18
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Zhao P, Cao L, Wang X, Dong J, Zhang N, Li X, Li J, Zhang X, Gong P. Extracellular vesicles secreted by Giardia duodenalis regulate host cell innate immunity via TLR2 and NLRP3 inflammasome signaling pathways. PLoS Negl Trop Dis 2021; 15:e0009304. [PMID: 33798196 PMCID: PMC8046354 DOI: 10.1371/journal.pntd.0009304] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 04/14/2021] [Accepted: 03/10/2021] [Indexed: 02/07/2023] Open
Abstract
Giardia duodenalis, also known as G. intestinalis or G. lamblia, is the major cause of giardiasis leading to diarrheal disease with 280 million people infections annually worldwide. Extracellular vesicles (EVs) have emerged as a ubiquitous mechanism participating in cells communications. The aim of this study is to explore the roles of G. duodenalis EVs (GEVs) in host-pathogen interactions using primary mouse peritoneal macrophages as a model. Multiple methods of electron microscopy, nanoparticle tracking analysis, proteomic assays, flow cytometry, immunofluorescence, qPCR, western blot, ELISA, inhibition assays, were used to characterize GEVs, and explore its effects on the host cell innate immunity as well as the underlying mechanism using primary mouse peritoneal macrophages. Results showed that GEVs displayed typical cup-shaped structure with 150 nm in diameter. GEVs could be captured by macrophages and triggered immune response by increasing the production of inflammatory cytokines Il1β, Il6, Il10, Il12, Il17, Ifng, Tnf, Il18, Ccl20 and Cxcl2. Furthermore, activation of TLR2 and NLRP3 inflammasome signaling pathways involved in this process. In addition, CA-074 methyl ester (an inhibitor of cathepsin B) or zVAD-fmk (an inhibitor of pan-caspase) pretreatment entirely diminished these effects triggered by GEVs exposure. Taken together, these findings demonstrated that GEVs could be internalized into mouse peritoneal macrophages and regulate host cell innate immunity via TLR2 and NLRP3 inflammasome signaling pathways. G. duodenalis, one of the most common cause of diarrheal diseases, is widely existed in the contaminated water and threatening the public health especially in developing countries. Along with the increasing resistance to anti-G. duodenalis drugs occurs, new targets against giardiasis are of urgently needed. The innate immune system is the first defense line of organism to resist multiple pathogens invasion through recognizing pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs), termed Toll-like receptors (TLRs) on the surface of cell membrane and nucleotide oligomerization domain (Nod)-like receptors (NLRs) inside immune cells. Recently, extracellular vesicles have emerged as a ubiquitous mechanism participating in cells communications. In this study, EVs secreted by extracellular protozoan G. duodenalis were obtained and displayed typical cup-shaped structure with 150 nm in diameter. Moreover, GEVs could enter into primary mouse peritoneal macrophages and regulate host cell innate immunity by up-regulation of various inflammatory cytokines expression. Furthermore, TLR2 and NLRP3 inflammasome signaling pathways involved in this process. This study demonstrated that GEVs could be internalized into primary mouse peritoneal macrophages, regulate host cell innate immunity via TLR2 and NLRP3 inflammasome signaling pathways, and may provide new targets against giardiasis.
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Affiliation(s)
- Panpan Zhao
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Lili Cao
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
- Jilin Academy of Animal Husbandry and Veterinary Medicine, Changchun, China
| | - Xiaocen Wang
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jingquan Dong
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Nan Zhang
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xin Li
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jianhua Li
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xichen Zhang
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Pengtao Gong
- Key Laboratory of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China
- * E-mail:
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19
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Fekete E, Allain T, Siddiq A, Sosnowski O, Buret AG. Giardia spp. and the Gut Microbiota: Dangerous Liaisons. Front Microbiol 2021; 11:618106. [PMID: 33510729 PMCID: PMC7835142 DOI: 10.3389/fmicb.2020.618106] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/15/2020] [Indexed: 12/11/2022] Open
Abstract
Alteration of the intestinal microbiome by enteropathogens is commonly associated with gastrointestinal diseases and disorders and has far-reaching consequences for overall health. Significant advances have been made in understanding the role of microbial dysbiosis during intestinal infections, including infection with the protozoan parasite Giardia duodenalis, one of the most prevalent gut protozoa. Altered species composition and diversity, functional changes in the commensal microbiota, and changes to intestinal bacterial biofilm structure have all been demonstrated during the course of Giardia infection and have been implicated in Giardia pathogenesis. Conversely, the gut microbiota has been found to regulate parasite colonization and establishment and plays a critical role in immune modulation during mono and polymicrobial infections. These disruptions to the commensal microbiome may contribute to a number of acute, chronic, and post-infectious clinical manifestations of giardiasis and may account for variations in disease presentation within and between infected populations. This review discusses recent advances in characterizing Giardia-induced bacterial dysbiosis in the gut and the roles of dysbiosis in Giardia pathogenesis.
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Affiliation(s)
- Elena Fekete
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
- Inflammation Research Network, University of Calgary, Calgary, AB, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB, Canada
| | - Thibault Allain
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
- Inflammation Research Network, University of Calgary, Calgary, AB, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB, Canada
| | - Affan Siddiq
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
- Inflammation Research Network, University of Calgary, Calgary, AB, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB, Canada
| | - Olivia Sosnowski
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
- Inflammation Research Network, University of Calgary, Calgary, AB, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB, Canada
| | - Andre G. Buret
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
- Inflammation Research Network, University of Calgary, Calgary, AB, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB, Canada
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20
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Singer SM, Angelova VV, DeLeon H, Miskovsky E. What's eating you? An update on Giardia, the microbiome and the immune response. Curr Opin Microbiol 2020; 58:87-92. [PMID: 33053502 PMCID: PMC7895496 DOI: 10.1016/j.mib.2020.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/10/2020] [Indexed: 02/07/2023]
Abstract
Giardia intestinalis has been observed in human stools since the invention of the microscope. However, it was not recognized as a pathogen until experimental infections in humans in the 1950s resulted in diarrheal illness [1]. We now know that this protozoan is capable of inducing a malabsorptive diarrhea and that the parasite is a major contributor to stunting in young children [2]. However, the majority of infections with this parasite are not accompanied by overt diarrhea and several studies indicate that it actually has a protective effect against moderate-severe diarrhea [3]. There is therefore significant interest in the mechanisms responsible for the wide variation observed in the clinical outcomes of infection with Giardia. This review will highlight recent work on the interactions among the parasite, the host microbiome and the immune response as contributing to this variation.
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Affiliation(s)
- Steven M Singer
- Department of Biology, Georgetown University, Washington, DC 20057, USA.
| | | | - Heriberto DeLeon
- Department of Biology, Georgetown University, Washington, DC 20057, USA
| | - Eleanor Miskovsky
- Department of Biology, Georgetown University, Washington, DC 20057, USA
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21
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Buret AG, Cacciò SM, Favennec L, Svärd S. Update on Giardia: Highlights from the seventh International Giardia and Cryptosporidium Conference. ACTA ACUST UNITED AC 2020; 27:49. [PMID: 32788035 PMCID: PMC7425178 DOI: 10.1051/parasite/2020047] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 08/01/2020] [Indexed: 12/22/2022]
Abstract
Although Giardia duodenalis is recognized as one of the leading causes of parasitic human diarrhea in the world, knowledge of the mechanisms of infection is limited, as the pathophysiological consequences of infection remain incompletely elucidated. Similarly, the reason for and consequences of the very specific genome-organization in this parasite with 2 active nuclei is only partially known. Consistent with its tradition, the 7th International Giardia and Cryptosporidium Conference (IGCC 2019) was held from June 23 to 26, 2019, at the Faculty of Medicine and Pharmacy of the University of Rouen-Normandie, France, to discuss current research perspectives in the field. This renowned event brought together an international delegation of researchers to present and debate recent advances and identify the main research themes and knowledge gaps. The program for this interdisciplinary conference included all aspects of host-parasite relationships, from basic research to applications in human and veterinary medicine, as well as the environmental issues raised by water-borne parasites and their epidemiological consequences. With regard to Giardia and giardiasis, the main areas of research for which new findings and the most impressive communications were presented and discussed included: parasite ecology and epidemiology of giardiasis, Giardia-host interactions, and cell biology of Giardia, genomes and genomic evolution. The high-quality presentations discussed at the Conference noted breakthroughs and identified new opportunities that will inspire researchers and funding agencies to stimulate future research in a “one health” approach to improve basic knowledge and clinical and public health management of zoonotic giardiasis.
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Affiliation(s)
- André G Buret
- Biological Sciences, University of Calgary, TN4N1 Calgary (AB), Canada
| | - Simone M Cacciò
- Department of Infectious Diseases, Istituto Superiore di Sanita, 00161 Rome, Italy
| | - Loïc Favennec
- French National Cryptosporidiosis Reference Center, Rouen University Hospital, 1 rue de Germont, 76031 Rouen cedex, France - EA 7510, UFR Santé, University of Rouen Normandy, Normandy University, 22 bd Gambetta, 76183 Rouen cedex, France
| | - Staffan Svärd
- Department of Cell and Molecular Biology, Uppsala University, SE 75124 Uppsala, Sweden
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22
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Natural Infection with Giardia Is Associated with Altered Community Structure of the Human and Canine Gut Microbiome. mSphere 2020; 5:5/4/e00670-20. [PMID: 32759335 PMCID: PMC7407069 DOI: 10.1128/msphere.00670-20] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
While enteric parasitic infections are among the most important infections in lower- and middle-income countries, their impact on gut microbiota is poorly understood. We reasoned that clinical symptoms associated with these infections may be influenced by alterations of the microbiome that occur during infection. To explore this notion, we took a two-pronged approach. First, we studied a cohort of dogs naturally infected with various enteric parasites and found a strong association between parasite infection and altered gut microbiota composition. Giardia, one of the most prevalent parasite infections globally, had a particularly large impact on the microbiome. Second, we took a database-driven strategy to integrate microbiome data with clinical data from large human field studies and found that Giardia infection is also associated with marked alteration of the gut microbiome of children, suggesting a possible explanation for why Giardia has been reported to be associated with protection from moderate to severe diarrhea. Enteric parasitic infections are among the most prevalent infections in lower- and middle-income countries (LMICs) and have a profound impact on global public health. While the microbiome is increasingly recognized as a key determinant of gut health and human development, the impact of naturally acquired parasite infections on microbial community structure in the gut, and the extent to which parasite-induced changes in the microbiome may contribute to gastrointestinal symptoms, is poorly understood. Enteric parasites are routinely identified in companion animals in the United States, presenting a unique opportunity to leverage this animal model to investigate the impact of naturally acquired parasite infections on the microbiome. Clinical, parasitological, and microbiome profiling of a cohort of 258 dogs revealed a significant correlation between parasite infection and composition of the bacterial community in the gut. Relative to other enteric parasites, Giardia was associated with a more pronounced perturbation of the microbiome. To compare our findings to large-scale epidemiological studies of enteric diseases in humans, a database mining approach was employed to integrate clinical and microbiome data. Substantial and consistent alterations to microbiome structure were observed in Giardia-infected children. Importantly, infection was associated with a reduction in the relative abundance of potential pathobionts, including Gammaproteobacteria, and an increase in Prevotella—a profile often associated with gut health. Taken together, these data show that widespread Giardia infection in young animals and humans is associated with significant remodeling of the gut microbiome and provide a possible explanation for the high prevalence of asymptomatic Giardia infections observed across host species. IMPORTANCE While enteric parasitic infections are among the most important infections in lower- and middle-income countries, their impact on gut microbiota is poorly understood. We reasoned that clinical symptoms associated with these infections may be influenced by alterations of the microbiome that occur during infection. To explore this notion, we took a two-pronged approach. First, we studied a cohort of dogs naturally infected with various enteric parasites and found a strong association between parasite infection and altered gut microbiota composition. Giardia, one of the most prevalent parasite infections globally, had a particularly large impact on the microbiome. Second, we took a database-driven strategy to integrate microbiome data with clinical data from large human field studies and found that Giardia infection is also associated with marked alteration of the gut microbiome of children, suggesting a possible explanation for why Giardia has been reported to be associated with protection from moderate to severe diarrhea.
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