scholarly journals Giardia colonizes and encysts in high density foci in the murine small intestine

2016 ◽  
Author(s):  
NR Barash ◽  
C Nosala ◽  
JK Pham ◽  
SG Mclnally ◽  
S Gourguechon ◽  
...  
Keyword(s):  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Diarrheal Disease ◽  
Laboratory Culture ◽  
High Density ◽  
Infection Dynamics ◽  
Proximal Small Intestine ◽  
Entire Duration ◽  
Duration Of Infection

AbstractGiardiais a highly prevalent, yet understudied protistan parasite causing diarrheal disease worldwide. Hosts ingestGiardiacysts from contaminated sources. In the gastrointestinal tract, cysts excyst to become motile trophozoites, colonizing and attaching to the gut epithelium. Trophozoites later differentiate into infectious cysts that are excreted and contaminate the environment. Due to the limited accessibility of the gut, the temporospatial dynamics of giardiasis in the host is largely inferred from laboratory culture and thus may not mirrorGiardiaphysiology in the host. Here we have developed bioluminescent imaging (BLI) to directly interrogate and quantify thein vivotemporospatial dynamics of giardiasis, thereby providing an improved murine model to evaluate anti-Giardiadrugs. Using BLI, we determined that parasites primarily colonize the proximal small intestine non-uniformly in high-density foci. By imaging encystation-specific bioreporters, we show that encystation initiates shortly after inoculation and continues throughout the entire duration of infection. Encystation also initiates in high-density foci in the proximal small intestine, and high-density laboratory cultures of parasites are also stimulated to encyst. This work overturns the assumption that parasites encyst later during infection as they are dislodged and travel through the colon. We suggest that these high-density regions of parasite colonization likely result in localized pathology to the epithelium, and encystation occurs when trophozoites reach a threshold density due to local nutrient depletion. This more accurate visualization of giardiasis redefines the dynamics ofin vivo Giardialife cycle, paving the way for future mechanistic studies of density-dependent parasitic processes in the host.SignificanceGiardiais a single-celled parasite causing both acute and chronic diarrheal disease in over one billion people worldwide. Due to limited access to the site of infection in the gastrointestinal tract, our understanding of the dynamics ofGiardiainfections in the host has remained limited, and largely inferred from laboratory culture. To better understand giardiasis in the host, we developed imaging methods to quantifyGiardiaexpressing bioluminescent physiological reporters in live mice. We discovered that parasites primarily colonize and encyst in the proximal small intestine in discrete, high-density foci. Furthermore, this work provides evidence of a parasite density-based threshold for the differentiation ofGiardiainto cysts in the host. These findings overturn existing paradigms of giardiasis infection dynamics in the host.

scholarly journals Giardia Colonizes and Encysts in High-Density Foci in the Murine Small Intestine

mSphere ◽  
2017 ◽  
Vol 2 (3) ◽  
Author(s):  
N. R. Barash ◽  
C. Nosala ◽  
J. K. Pham ◽  
S. G. McInally ◽  
S. Gourguechon ◽  
...  
Keyword(s):  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Animal Models ◽  
Diarrheal Disease ◽  
Laboratory Culture ◽  
High Density ◽  
Proximal Small Intestine ◽  
High Parasite Density ◽  
High Parasite

ABSTRACT Giardia is a single-celled parasite causing significant diarrheal disease in several hundred million people worldwide. Due to limited access to the site of infection in the gastrointestinal tract, our understanding of the dynamics of Giardia infections in the host has remained limited and largely inferred from laboratory culture. To better understand Giardia physiology and colonization in the host, we developed imaging methods to quantify Giardia expressing bioluminescent physiological reporters in two relevant animal models. We discovered that parasites primarily colonize and encyst in the proximal small intestine in discrete, high-density foci. We also show that high parasite density contributes to encystation initiation. Giardia lamblia is a highly prevalent yet understudied protistan parasite causing significant diarrheal disease worldwide. Hosts ingest Giardia cysts from contaminated sources. In the gastrointestinal tract, cysts excyst to become motile trophozoites, colonizing and attaching to the gut epithelium. Trophozoites later differentiate into infectious cysts that are excreted and contaminate the environment. Due to the limited accessibility of the gut, the temporospatial dynamics of giardiasis in the host are largely inferred from laboratory culture and thus may not mirror Giardia physiology in the host. Here, we have developed bioluminescent imaging (BLI) to directly interrogate and quantify the in vivo temporospatial dynamics of Giardia infection, thereby providing an improved murine model to evaluate anti-Giardia drugs. Using BLI, we determined that parasites primarily colonize the proximal small intestine nonuniformly in high-density foci. By imaging encystation-specific bioreporters, we show that encystation initiates shortly after inoculation and continues throughout the duration of infection. Encystation also initiates in high-density foci in the proximal small intestine, and high density contributes to the initiation of encystation in laboratory culture. We suggest that these high-density in vivo foci of colonizing and encysting Giardia likely result in localized disruption to the epithelium. This more accurate visualization of giardiasis redefines the dynamics of the in vivo Giardia life cycle, paving the way for future mechanistic studies of density-dependent parasitic processes in the host. IMPORTANCE Giardia is a single-celled parasite causing significant diarrheal disease in several hundred million people worldwide. Due to limited access to the site of infection in the gastrointestinal tract, our understanding of the dynamics of Giardia infections in the host has remained limited and largely inferred from laboratory culture. To better understand Giardia physiology and colonization in the host, we developed imaging methods to quantify Giardia expressing bioluminescent physiological reporters in two relevant animal models. We discovered that parasites primarily colonize and encyst in the proximal small intestine in discrete, high-density foci. We also show that high parasite density contributes to encystation initiation.

scholarly journals Transcriptomic profiling of high-density Giardia foci encysting in the murine proximal intestine

2017 ◽  
Author(s):  
JK Pham ◽  
C Nosala ◽  
EY Scott ◽  
KF Nguyen ◽  
KD Hagen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gastrointestinal Tract ◽  
Diarrheal Disease ◽  
Axenic Culture ◽  
Laboratory Culture ◽  
High Density ◽  
Live Animal ◽  
Mammalian Cell Lines ◽  
Proximal Intestine

AbstractGiardiais a highly prevalent, understudied protistan parasite causing significant diarrheal disease worldwide. Its life cycle consists of two stages: infectious cysts ingested from contaminated food or water sources, and motile trophozoites that colonize and attach to the gut epithelium, later encysting to form new cysts that are excreted into the environment. Current understanding of parasite physiology in the host is largely inferred from transcriptomic studies usingGiardiagrown axenically or in co-culture with mammalian cell lines. The dearth of information about the diversity of host-parasite interactions occurring within distinct regions of the gastrointestinal tract has been exacerbated by a lack of methods to directly and non-invasively interrogate disease progression and parasite physiology in live animal hosts. By visualizingGiardiainfections in the mouse gastrointestinal tract using bioluminescent imaging (BLI) of tagged parasites, we recently showed that parasites colonize the gut in high-density foci that may cause localized pathology to the epithelium. Encystation is also initiated in these foci throughout the entire course of infection, yet how the physiology of parasites within high-density foci in the host gut differs from that of cells in laboratory culture is unclear. Here we use BLI to precisely select parasite samples from high-density foci in the proximal intestine to interrogatein vivo Giardiagene expression in the host. Relative to axenic culture, we noted significantly higher expression (> 10-fold) of oxidative stress, membrane transporter, and metabolic and structural genes associated with encystation in the high-density foci. These differences in gene expression within parasite foci in the host may reflect physiological changes associated with high-density growth in localized regions of the gut. We also identified and verified six novel cyst-specific proteins, including new components of the cyst wall that were highly expressed in these foci. Ourin vivotranscriptome data support an emerging view that parasites encyst early in localized regions in the gut, possibly as a consequence of nutrient limitation, and also impact local metabolism and physiology.

scholarly journals Application of selective extraction to the study of iron species present in diet and rat gastrointestinal tract contents

1992 ◽  
Vol 67 (3) ◽  
pp. 437-444 ◽  
Author(s):  
Robert J. Simpson ◽  
Sanjiv Sidhar ◽  
Timothy J. Peters
Keyword(s):  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Stomach Contents ◽  
Selective Extraction ◽  
Proximal Small Intestine ◽  
Exchangeable Fraction ◽  
Fe Speciation ◽  
Pelleted Diet

Iron speciation in rodent diet and rat gastrointestinal tract lumen during dietary digestion and absorption was investigated with a novel selective extraction technique. Five Fe fractions were identified, namely exchangeable (soluble in 1 M-magnesium chloride), carbonate-bound (soluble in mild acid), oxide-bound (soluble in hydroxylamine–acetic acid), organic-bound (soluble after treatment with peroxide in nitric acid) and residual. Fe from the pelleted diet was mobilized by rat stomach to the exchangeable fraction, then redistributed to the carbonate- and oxide-bound fractions on passage through the proximal small intestine. In vitro incubation of diet with hydrochloric acid failed to mimic the in vivo effect of the stomach. In vitro neutralization of stomach contents with bicarbonate was found to produce a similar effect on Fe speciation to that seen when diet passed the proximal small intestine in vivo. Comparison of59Fe speciation in extrinsically labelled diet with endogenous Fe speciation showed that extrinsic labelling does not uniformly label all endogenous species. The experiments suggest that selective extraction may provide a useful approach to the study of Fe species present in diets, in vitro digestions and gastrointestinal contents.

scholarly journals Giardia Alters Commensal Microbial Diversity throughout the Murine Gut

2017 ◽  
Vol 85 (6) ◽  
Author(s):  
N. R. Barash ◽  
J. G. Maloney ◽  
S. M. Singer ◽  
S. C. Dawson
Keyword(s):  
Small Intestine ◽  
Diarrheal Disease ◽  
Content Type ◽  
Commensal Microbiota ◽  
Microbial Dysbiosis ◽  
Proximal Small Intestine ◽  
Culture Independent ◽  
Duration Of Infection ◽  
The Impact ◽  
Aerobic And Anaerobic

ABSTRACT Giardia lamblia is the most frequently identified protozoan cause of intestinal infection. Over 200 million people are estimated to have acute or chronic giardiasis, with infection rates approaching 90% in areas where Giardia is endemic. Despite its significance in global health, the mechanisms of pathogenesis associated with giardiasis remain unclear, as the parasite neither produces a known toxin nor induces a robust inflammatory response. Giardia colonization and proliferation in the small intestine of the host may, however, disrupt the ecological homeostasis of gastrointestinal commensal microbes and contribute to diarrheal disease associated with giardiasis. To evaluate the impact of Giardia infection on the host microbiota, we used culture-independent methods to quantify shifts in the diversity of commensal microbes throughout the gastrointestinal tract in mice infected with Giardia. We discovered that Giardia's colonization of the small intestine causes a systemic dysbiosis of aerobic and anaerobic commensal bacteria. Specifically, Giardia colonization is typified by both expansions in aerobic Proteobacteria and decreases in anaerobic Firmicutes and Melainabacteria in the murine foregut and hindgut. Based on these shifts, we created a quantitative index of murine Giardia-induced microbial dysbiosis. This index increased at all gut regions during the duration of infection, including both the proximal small intestine and the colon. Giardiasis could be an ecological disease, and the observed dysbiosis may be mediated directly via the parasite's unique anaerobic fermentative metabolism or indirectly via parasite induction of gut inflammation. This systemic alteration of murine gut commensal diversity may be the cause or the consequence of inflammatory and metabolic changes throughout the gut. Shifts in the commensal microbiota may explain observed variations in giardiasis between hosts with respect to host pathology, degree of parasite colonization, infection initiation, and eventual clearance.

scholarly journals Giardiaalters commensal microbial diversity throughout the murine gut

2016 ◽  
Author(s):  
NR Barash ◽  
JG Maloney ◽  
SM Singer ◽  
SC Dawson
Keyword(s):  
Small Intestine ◽  
Diarrheal Disease ◽  
Commensal Microbiota ◽  
Microbial Dysbiosis ◽  
Proximal Small Intestine ◽  
Culture Independent ◽  
Duration Of Infection ◽  
The Impact ◽  
Aerobic And Anaerobic ◽  
Entire Gastrointestinal Tract

ABSTRACTGiardia lambliais the most frequently identified protozoan cause of intestinal infection. Over one billion people are estimated to have acute or chronic giardiasis, with infection rates approaching 90% in endemic areas. Despite its significance in global health, the mechanisms of pathogenesis associated with giardiasis remain unclear as the parasite neither produces a known toxin nor induces a robust inflammatory response.Giardiacolonization and proliferation in the small intestine of the host may, however, disrupt the ecological homeostasis of gastrointestinal commensal microbes and contribute to diarrheal disease associated with giardiasis. To evaluate the impact ofGiardiainfection on the host microbiota, we use culture-independent methods to quantify shifts in the diversity of commensal microbes throughout the entire gastrointestinal tract in mice infected withGiardia. We discovered thatGiardia’scolonization of the small intestine causes a systemic dysbiosis of aerobic and anaerobic bacterial taxa. Specifically, giardiasis is typified by both expansions in aerobicProteobacteriaand decreases in anaerobicFirmicutesandMelainabacteriain the murine foregut and hindgut. Based on these shifts, we created a quantitative index of murineGiardia-induced microbial dysbiosis. This index increased at all gut regions during the duration of infection, including both the proximal small intestine and the colon. Thus giardiasis could be an ecological disease, and the observed dysbiosis may be mediated directly via the parasite’s unique anaerobic fermentative metabolism or indirectly via parasite induction of gut inflammation. This systemic alteration of murine gut commensal diversity may be the cause or the consequence of inflammatory and metabolic changes throughout the gut. Shifts in the commensal microbiota may explain observed variation in giardiasis between hosts with respect to host pathology, degree of parasite colonization, infection initiation, and eventual clearance.

Ileal and hindgut fermentation in the growing pig fed a human-type diet

2020 ◽  
Vol 124 (6) ◽  
pp. 567-576 ◽  
Author(s):  
Anna M. E. Hoogeveen ◽  
Paul J. Moughan ◽  
Edward S. de Haas ◽  
Paul Blatchford ◽  
Warren C. McNabb ◽  
...  
Keyword(s):  
Body Weight ◽  
Organic Matter ◽  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Taxonomic Composition ◽  
Human Type ◽  
Growing Pig ◽  
Microbial Inocula

AbstractDietary fibre fermentation in humans and monogastric animals is considered to occur in the hindgut, but it may also occur in the lower small intestine. This study aimed to compare ileal and hindgut fermentation in the growing pig fed a human-type diet using a combined in vivo/in vitro methodology. Five pigs (23 (sd 1·6) kg body weight) were fed a human-type diet. On day 15, pigs were euthanised. Digesta from terminal jejunum and terminal ileum were collected as substrates for fermentation. Ileal and caecal digesta were collected for preparing microbial inocula. Terminal jejunal digesta were fermented in vitro with a pooled ileal digesta inoculum for 2 h, whereas terminal ileal digesta were fermented in vitro with a pooled caecal digesta inoculum for 24 h. The ileal organic matter fermentability (28 %) was not different from hindgut fermentation (35 %). However, the organic matter fermented was 66 % greater for ileal fermentation than hindgut fermentation (P = 0·04). Total numbers of bacteria in ileal and caecal digesta did not differ (P = 0·09). Differences (P < 0·05) were observed in the taxonomic composition. For instance, ileal digesta contained 32-fold greater number of the genus Enterococcus, whereas caecal digesta had a 227-fold greater number of the genus Ruminococcus. Acetate synthesis and iso-valerate synthesis were greater (P < 0·05) for ileal fermentation than hindgut fermentation, but propionate, butyrate and valerate synthesis was lower. SCFA were absorbed in the gastrointestinal tract location where they were synthesised. In conclusion, a quantitatively important degree of fermentation occurs in the ileum of the growing pig fed a human-type diet.

Gastrointestinal tract protein synthesis and mRNA levels for proteolytic systems in adult fasted rats

1996 ◽  
Vol 271 (2) ◽  
pp. E232-E238 ◽  
Author(s):  
S. E. Samuels ◽  
D. Taillandier ◽  
E. Aurousseau ◽  
Y. Cherel ◽  
Y. Le Maho ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Mrna Levels ◽  
Protein Mass ◽  
Fractional Rate ◽  
Intestinal Protein ◽  
Critical Components ◽  
Fasted Rats

We studied protein turnover in the gastrointestinal tract of adult fasted rats, since the mechanisms responsible for protein wasting in these tissues are poorly understood. Protein mass of stomach, small intestine, and colon decreased by 14-29 and 21-49% after 1 and 5 days of fasting, respectively. The fractional rate of in vivo protein synthesis (ks) was approximately 34% lower in the stomach after 1 and 5 days of fasting due to decreased capacity for protein synthesis (Cs). In small intestine and colon, ks was not different after 1 day, but was approximately 26% lower on day 5, mainly because of a reduction in Cs. Thus protein wasting in the stomach is primarily mediated by decreased protein synthesis but not in small intestine and colon during short-term fasting. To determine which proteolytic systems may be activated in the gut, we measured mRNA levels for critical components of the lysosomal (cathepsins B and D), Ca(2+)-activated (m-calpain), and ubiquitin-dependent (ubiquitin, 14-kDa ubiquitin-conjugating enzyme E2, and C8, and C9 proteasome subunits) proteolytic pathways. mRNA levels for most of these components increased during fasting, suggesting that a coordinated activation of multiple proteolytic systems contributed to intestinal protein wasting.

COMPARISON OF THE METABOLISM OF TESTOSTERONE UNDECANOATE AND TESTOSTERONE IN THE GASTROINTESTINAL WALL OF THE RAT IN VITRO AND IN VIVO

1977 ◽  
Vol 86 (1) ◽  
pp. 216-224 ◽  
Author(s):  
J. Geelen ◽  
A. Coert ◽  
R. Meijer ◽  
J. van der Vies
Keyword(s):  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Portal Vein ◽  
Oral Administration ◽  
Small Extent ◽  
Great Similarity ◽  
Testosterone Undecanoate ◽  
Different Parts

ABSTRACT The metabolism of testosterone undecanoate (TU) and testosterone (T) is studied in the gastrointestinal wall of the rat in vitro. A comparison is made with the in vivo metabolism of these compounds in the rat. The major metabolite first appearing during incubation of TU with the small intestine is T. Incubation of TU or T with the small intestine reveals a great similarity between the metabolite patterns obtained. This is also the case with the patterns derived from portal vein plasma upon oral administration of TU and T. Incubation of different parts of the gastrointestinal tract with TU or T shows that the greatest metabolic activity is located in the wall of the small intestine. Unlike T, TU is metabolized only to a small extent in the wall of the stomach and the large intestine.

Regulation of gastrointestinal growth in fetal sheep by luminally administered insulin-like growth factor-I

1997 ◽  
Vol 152 (1) ◽  
pp. 29-38 ◽  
Author(s):  
J F Trahair ◽  
S J Wing ◽  
K J Quinn ◽  
P C Owens
Keyword(s):  
Small Intestine ◽  
Growth Factors ◽  
Gastrointestinal Tract ◽  
Growth Factor ◽  
Amniotic Fluid ◽  
Insulin Like Growth Factor ◽  
Fetal Sheep ◽  
Factor I ◽  
Proximal Small Intestine ◽  
Igf I

Abstract Fetuses swallow large volumes of amniotic fluid. Absence of swallowing results in gastrointestinal tract (GIT) growth deficits. While it is not yet known to what extent the growth factors present in amniotic fluid are involved in GIT ontogeny, milk-derived growth factors are considered to be important for neonatal growth. Our experiment tested the hypothesis that a luminal growth factor (insulin-like growth factor-I, IGF-I) can sustain or promote GIT growth in utero in a model of gastrointestinal tract growth retardation. Ten-day infusion of either human recombinant IGF-I or vehicle into twin fetal sheep at 80 days gestation via an indwelling esophageal catheter resulted in altered GIT growth. Weight of the forestomach and small intestine increased. Significant histological changes were noted in the proximal small intestine, i.e. the region most exposed to the luminal infusion. Mucosal tissues were reduced in size. While the enterocytes in the proximal small intestine were generally more mature with regard to the ontogeny of the apical endocytic complex (which is responsible for uptake and transport of whole peptides), there were also many abnormal cytological features present. These included the development of large lysosomal-like inclusion bodies and many surfactant-like particles within the apical cytoplasm. Plasma IGF-I levels were on average 20% higher in treated siblings, suggesting that luminal IGF-I crossed the fetal gut and entered blood. IGF-II levels were not significantly affected. These observations are consistent with the suggestion that growth factors, which are present in swallowed amniotic fluid, influence fetal ontogeny. Journal of Endocrinology (1997) 152, 29–38

scholarly journals Bile Acids and Bicarbonate Inversely Regulate Intracellular Cyclic di-GMP in Vibrio cholerae

2014 ◽  
Vol 82 (7) ◽  
pp. 3002-3014 ◽  
Author(s):  
Benjamin J. Koestler ◽  
Christopher M. Waters
Keyword(s):  
Small Intestine ◽  
Bile Acids ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Intracellular Concentration ◽  
Intestinal Epithelial ◽  
Content Type ◽  
Proximal Small Intestine ◽  
Ph Buffer ◽  
Messenger Molecule

ABSTRACTVibrio choleraeis a Gram-negative bacterium that persists in aquatic reservoirs and causes the diarrheal disease cholera upon entry into a human host.V. choleraeemploys the second messenger molecule 3′,5′-cyclic diguanylic acid (c-di-GMP) to transition between these two distinct lifestyles. c-di-GMP is synthesized by diguanylate cyclase (DGC) enzymes and hydrolyzed by phosphodiesterase (PDE) enzymes. Bacteria typically encode many different DGCs and PDEs within their genomes. Presumably, each enzyme senses and responds to cognate environmental cues by alteration of enzymatic activity. c-di-GMP represses the expression of virulence factors inV. cholerae, and it is predicted that the intracellular concentration of c-di-GMP is low during infection. Contrary to this model, we found that bile acids, a prevalent constituent of the human proximal small intestine, increase intracellular c-di-GMP inV. cholerae. We identified four c-di-GMP turnover enzymes that contribute to increased intracellular c-di-GMP in the presence of bile acids, and deletion of these enzymes eliminates the bile induction of c-di-GMP and biofilm formation. Furthermore, this bile-mediated increase in c-di-GMP is quenched by bicarbonate, the intestinal pH buffer secreted by intestinal epithelial cells. Our results lead us to propose thatV. choleraesenses distinct microenvironments within the small intestine using bile and bicarbonate as chemical cues and responds by modulating the intracellular concentration of c-di-GMP.

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