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Distinct stages during colonization of the mouse gastrointestinal tract by Candida albicans.

Prieto D, Pla J - Front Microbiol (2015)

Bottom Line: Candida albicans is a member of the human microbiota, colonizing both the vaginal and gastrointestinal tracts.This yeast is devoid of a life style outside the human body and the mechanisms underlying the adaptation to the commensal status remain to be determined.We show that long term (15 days) colonizing cells have increased fitness in the gut niche over those grown in vitro or residing in the gut for 1-3 days.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid Madrid, Spain.

ABSTRACT
Candida albicans is a member of the human microbiota, colonizing both the vaginal and gastrointestinal tracts. This yeast is devoid of a life style outside the human body and the mechanisms underlying the adaptation to the commensal status remain to be determined. Using a model of mouse gastrointestinal colonization, we show here that C. albicans stably colonizes the mouse gut in about 3 days starting from a dose as low as 100 cells, reaching steady levels of around 10(7) cells/g of stools. Using fluorescently labeled strains, we have assessed the competition between isogenic populations from different sources in cohoused animals. We show that long term (15 days) colonizing cells have increased fitness in the gut niche over those grown in vitro or residing in the gut for 1-3 days. Therefore, two distinct states, proliferation and adaptation, seem to exist in the adaptation of this fungus to the mouse gut, a result with potential significance in the prophylaxis and treatment of Candida infections.

No MeSH data available.


Related in: MedlinePlus

Dose and time influence in the colonization fitness. Differences in fitness are determined through comparison of CI values (log2). Each symbol represents data from an individual mouse. (A) Effect of dose among Ca-gS groups (n = 3–6). (B) Effect of dose among Ca-gL groups (n = 4–7). (C) Effect of the time past in the gut regardless the dose (n = 14–16). *p < 0.05, ***p < 0.001.
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Figure 4: Dose and time influence in the colonization fitness. Differences in fitness are determined through comparison of CI values (log2). Each symbol represents data from an individual mouse. (A) Effect of dose among Ca-gS groups (n = 3–6). (B) Effect of dose among Ca-gL groups (n = 4–7). (C) Effect of the time past in the gut regardless the dose (n = 14–16). *p < 0.05, ***p < 0.001.

Mentions: Since each strain is inoculated on different days (days 2, 15, or 21), it is difficult to compare the evolution of the populations in competitive fitness. We chose to use the proportions of strains determined in stool samples at day 1 as this value nicely correlates with the proportion in the mix inoculated in standard colonization competition assays in mice (Figure S1). We used colonization competition index (CI) (see Materials and Methods) as it actually reflects the ability of one population to persist over the other one. Using this parameter, we have analyzed whether the dose and/or stage of previous population influence the subsequent competition. While a high C. albicans dose (107 cells) helps Ca-n to reach higher fungal levels on day 1, it does not really impact the outcome of the evolution of the population levels as no statistically significant differences were detected in the CIg/n ratio at any dose administered, neither in short-term or long-term populations (Figures 4A,B). However, strikingly clear differences appear when comparing Ca-gS and Ca-gL groups, regardless the dose: the CIg/n was always higher for C. albicans cells that were in the gut for a long time, that is Ca-gL outcompetes more efficiently the new Ca-n population than Ca-gS (Figure 4C). Moreover, we only find values for CIg/n below 1 (negative as a logarithm) in the Ca-gS group. Remarkably, the mean of this index does not significantly changes within a group of mice over time (Figure 4C) with log2 values of 1.41 ± 0.36 (day 4), 2.31 ± 0.64 (day 8), 2.41 ± 0.64 (day 13), and 1.17 ± 0.45 (day 15) for short-term group; and 5.38 ± 0.69 (day 4), 4.54 ± 0.64 (day 8), 6.34 ± 0.49 (day 13), and 6.79 ± 0.73 (day 15) for Ca-gL group (log2CIg/n, mean ± SEM).


Distinct stages during colonization of the mouse gastrointestinal tract by Candida albicans.

Prieto D, Pla J - Front Microbiol (2015)

Dose and time influence in the colonization fitness. Differences in fitness are determined through comparison of CI values (log2). Each symbol represents data from an individual mouse. (A) Effect of dose among Ca-gS groups (n = 3–6). (B) Effect of dose among Ca-gL groups (n = 4–7). (C) Effect of the time past in the gut regardless the dose (n = 14–16). *p < 0.05, ***p < 0.001.
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Figure 4: Dose and time influence in the colonization fitness. Differences in fitness are determined through comparison of CI values (log2). Each symbol represents data from an individual mouse. (A) Effect of dose among Ca-gS groups (n = 3–6). (B) Effect of dose among Ca-gL groups (n = 4–7). (C) Effect of the time past in the gut regardless the dose (n = 14–16). *p < 0.05, ***p < 0.001.
Mentions: Since each strain is inoculated on different days (days 2, 15, or 21), it is difficult to compare the evolution of the populations in competitive fitness. We chose to use the proportions of strains determined in stool samples at day 1 as this value nicely correlates with the proportion in the mix inoculated in standard colonization competition assays in mice (Figure S1). We used colonization competition index (CI) (see Materials and Methods) as it actually reflects the ability of one population to persist over the other one. Using this parameter, we have analyzed whether the dose and/or stage of previous population influence the subsequent competition. While a high C. albicans dose (107 cells) helps Ca-n to reach higher fungal levels on day 1, it does not really impact the outcome of the evolution of the population levels as no statistically significant differences were detected in the CIg/n ratio at any dose administered, neither in short-term or long-term populations (Figures 4A,B). However, strikingly clear differences appear when comparing Ca-gS and Ca-gL groups, regardless the dose: the CIg/n was always higher for C. albicans cells that were in the gut for a long time, that is Ca-gL outcompetes more efficiently the new Ca-n population than Ca-gS (Figure 4C). Moreover, we only find values for CIg/n below 1 (negative as a logarithm) in the Ca-gS group. Remarkably, the mean of this index does not significantly changes within a group of mice over time (Figure 4C) with log2 values of 1.41 ± 0.36 (day 4), 2.31 ± 0.64 (day 8), 2.41 ± 0.64 (day 13), and 1.17 ± 0.45 (day 15) for short-term group; and 5.38 ± 0.69 (day 4), 4.54 ± 0.64 (day 8), 6.34 ± 0.49 (day 13), and 6.79 ± 0.73 (day 15) for Ca-gL group (log2CIg/n, mean ± SEM).

Bottom Line: Candida albicans is a member of the human microbiota, colonizing both the vaginal and gastrointestinal tracts.This yeast is devoid of a life style outside the human body and the mechanisms underlying the adaptation to the commensal status remain to be determined.We show that long term (15 days) colonizing cells have increased fitness in the gut niche over those grown in vitro or residing in the gut for 1-3 days.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid Madrid, Spain.

ABSTRACT
Candida albicans is a member of the human microbiota, colonizing both the vaginal and gastrointestinal tracts. This yeast is devoid of a life style outside the human body and the mechanisms underlying the adaptation to the commensal status remain to be determined. Using a model of mouse gastrointestinal colonization, we show here that C. albicans stably colonizes the mouse gut in about 3 days starting from a dose as low as 100 cells, reaching steady levels of around 10(7) cells/g of stools. Using fluorescently labeled strains, we have assessed the competition between isogenic populations from different sources in cohoused animals. We show that long term (15 days) colonizing cells have increased fitness in the gut niche over those grown in vitro or residing in the gut for 1-3 days. Therefore, two distinct states, proliferation and adaptation, seem to exist in the adaptation of this fungus to the mouse gut, a result with potential significance in the prophylaxis and treatment of Candida infections.

No MeSH data available.


Related in: MedlinePlus