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Identification and characterisation of an iron-responsive candidate probiotic.

Bailey JR, Probert CS, Cogan TA - PLoS ONE (2011)

Bottom Line: The isolate of S. thermophilus selected was able to reduce epithelial cell death as well as NF-κB signalling and IL-8 production triggered by pathogens.It was capable of crossing an epithelial cell barrier in conjunction with E. coli and downregulating Th1 and Th17 responses in primary human intestinal leukocytes.Therefore, we offer an alternative paradigm which considers that probiotics should be able to be competitive during periods of intestinal bleeding, trauma or stress.

View Article: PubMed Central - PubMed

Affiliation: Mucosal Microbiology, School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom.

ABSTRACT

Background: Iron is an essential cofactor in almost all biological systems. The lactic acid bacteria (LAB), frequently employed as probiotics, are unusual in having little or no requirement for iron. Iron in the human body is sequestered by transferrins and lactoferrin, limiting bacterial growth. An increase in the availability of iron in the intestine by bleeding, surgery, or under stress leads to an increase in the growth and virulence of many pathogens. Under these high iron conditions, LAB are rapidly out-competed; for the levels of probiotic bacteria to be maintained under high iron conditions they must be able to respond by increasing growth rate to compete with the normal flora. Despite this, iron-responsive genera are poorly characterised as probiotics.

Methodology/principal findings: Here, we show that a panel of probiotics are not able to respond to increased iron availability, and identify an isolate of Streptococcus thermophilus that can increase growth rate in response to increased iron availability. The isolate of S. thermophilus selected was able to reduce epithelial cell death as well as NF-κB signalling and IL-8 production triggered by pathogens. It was capable of crossing an epithelial cell barrier in conjunction with E. coli and downregulating Th1 and Th17 responses in primary human intestinal leukocytes.

Conclusions/significance: We propose that an inability to compete with potential pathogens under conditions of high iron availability such as stress and trauma may contribute to the lack of efficacy of many LAB-based probiotics in treating disease. Therefore, we offer an alternative paradigm which considers that probiotics should be able to be competitive during periods of intestinal bleeding, trauma or stress.

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Probiotic effect on proliferation and death of epithelial cells in response to pathogenic E. coli.A) Proliferation of T84 cells; B) proliferation of Caco-2 cells; C) death of T84 cells; D) death of Caco-2 cells. Results are shown from 3 replicate experiments and are expressed as mean + S.E.M. * p≤0.05, ** p≤0.01 and *** p≤0.001.
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pone-0026507-g001: Probiotic effect on proliferation and death of epithelial cells in response to pathogenic E. coli.A) Proliferation of T84 cells; B) proliferation of Caco-2 cells; C) death of T84 cells; D) death of Caco-2 cells. Results are shown from 3 replicate experiments and are expressed as mean + S.E.M. * p≤0.05, ** p≤0.01 and *** p≤0.001.

Mentions: Increased turnover of epithelial cells is a common response to infection therefore T84 and Caco-2 adenocarcinoma cells were incubated with the potential probiotics L. acidophilus ASF360, S. thermophilus NCIMB 41856 and E. coli Nissle 1917 to determine their effect on the proliferative or apoptotic cellular response to pathogenic E. coli strains, K12 and the Crohn's disease-associated AIEC strain HM615 [27]. All E. coli strains, including E. coli Nissle 1917, reduced the proliferation of T84 epithelial cells: E. coli K12 reduced proliferation by 78% compared to untreated cells (p = 0.002); AIEC HM615 reduced proliferation by 80% (p = 0.0001); and E. coli Nissle 1917 by 82% (p = 0.001) (Figure 1A). A similar reduction in proliferation of Caco-2 cells was seen following E. coli treatment: E. coli K12 induced a reduction of 77% compared to untreated cells (p = 0.003); AIEC HM615 induced a reduction of 76% (p = 0.003); and E. coli Nissle 1917 of 78% (p = 0.004) (Figure 1C). Simultaneously, cell death was increased in both T84 and Caco-2 cells; E. coli K12 induced a 254% increase in cell death in Caco-2 cells (p = 0.0005); AIEC HM615 induced a 498% increase in death in T84 cells (p = 0.0003) and a 254% increase in Caco-2 cell death (p = 0.001); E. coli Nissle 1917 induced a 498% increase in T84 cell death (p<0.0001) and a 218% increase in Caco-2 cell death (p = 0.001) (Figure 1D). S. thermophilus NCIMB 41856 reduced the proliferation of Caco-2 cells treated with E. coli K12 or AIEC HM615 by 35% (p = 0.003) and 31% (p = 0.05), respectively; while E. coli Nissle 1917 reduced proliferation induced by E. coli K12 by 32% (p = 0.007) and 37% in response to AIEC HM615 treatment (p = 0.03) (Figure 1B). In addition, L. acidophilus ASF360 further reduced proliferation of Caco-2 cells treated with AIEC HM615 by 22% (p = 0.02) (Figure 1B). S. thermophilus NCIMB 41856 reduced proliferation of T84 cells treated with AIEC HM615 and E. coli Nissle 1917 by 33% (p = 0.03) and 48% (p = 0.03), respectively (Figure 1A). Importantly, all three probiotic strains reduced death of Caco-2 cells following challenge with both E. coli K12 and HM615: L. acidophilus ASF360 reduced death of epithelial cells by 14% (p = 0.04) following E. coli K12 treatment and 16% following infection with AIEC HM615 (p = 0.03); S. thermophilus NCIMB 41856 reduced death of epithelial cells following E. coli K12 and AIEC HM615 treatment by 10% (p = 0.01) and 18% (p = 0.007), respectively; E. coli Nissle 1917 reduced death of epithelial cells following E. coli K12 and treatment by 26% (p = 0.006) and 27% (p = 0.003), respectively (Figure 1D). In addition, S. thermophilus NCIMB 41856 was able to reduce proliferation and cell death of untreated Caco-2 cells by 24% (p = 0.008) and 22% (p = 0.02) respectively (Figure 1B and D).


Identification and characterisation of an iron-responsive candidate probiotic.

Bailey JR, Probert CS, Cogan TA - PLoS ONE (2011)

Probiotic effect on proliferation and death of epithelial cells in response to pathogenic E. coli.A) Proliferation of T84 cells; B) proliferation of Caco-2 cells; C) death of T84 cells; D) death of Caco-2 cells. Results are shown from 3 replicate experiments and are expressed as mean + S.E.M. * p≤0.05, ** p≤0.01 and *** p≤0.001.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3198401&req=5

pone-0026507-g001: Probiotic effect on proliferation and death of epithelial cells in response to pathogenic E. coli.A) Proliferation of T84 cells; B) proliferation of Caco-2 cells; C) death of T84 cells; D) death of Caco-2 cells. Results are shown from 3 replicate experiments and are expressed as mean + S.E.M. * p≤0.05, ** p≤0.01 and *** p≤0.001.
Mentions: Increased turnover of epithelial cells is a common response to infection therefore T84 and Caco-2 adenocarcinoma cells were incubated with the potential probiotics L. acidophilus ASF360, S. thermophilus NCIMB 41856 and E. coli Nissle 1917 to determine their effect on the proliferative or apoptotic cellular response to pathogenic E. coli strains, K12 and the Crohn's disease-associated AIEC strain HM615 [27]. All E. coli strains, including E. coli Nissle 1917, reduced the proliferation of T84 epithelial cells: E. coli K12 reduced proliferation by 78% compared to untreated cells (p = 0.002); AIEC HM615 reduced proliferation by 80% (p = 0.0001); and E. coli Nissle 1917 by 82% (p = 0.001) (Figure 1A). A similar reduction in proliferation of Caco-2 cells was seen following E. coli treatment: E. coli K12 induced a reduction of 77% compared to untreated cells (p = 0.003); AIEC HM615 induced a reduction of 76% (p = 0.003); and E. coli Nissle 1917 of 78% (p = 0.004) (Figure 1C). Simultaneously, cell death was increased in both T84 and Caco-2 cells; E. coli K12 induced a 254% increase in cell death in Caco-2 cells (p = 0.0005); AIEC HM615 induced a 498% increase in death in T84 cells (p = 0.0003) and a 254% increase in Caco-2 cell death (p = 0.001); E. coli Nissle 1917 induced a 498% increase in T84 cell death (p<0.0001) and a 218% increase in Caco-2 cell death (p = 0.001) (Figure 1D). S. thermophilus NCIMB 41856 reduced the proliferation of Caco-2 cells treated with E. coli K12 or AIEC HM615 by 35% (p = 0.003) and 31% (p = 0.05), respectively; while E. coli Nissle 1917 reduced proliferation induced by E. coli K12 by 32% (p = 0.007) and 37% in response to AIEC HM615 treatment (p = 0.03) (Figure 1B). In addition, L. acidophilus ASF360 further reduced proliferation of Caco-2 cells treated with AIEC HM615 by 22% (p = 0.02) (Figure 1B). S. thermophilus NCIMB 41856 reduced proliferation of T84 cells treated with AIEC HM615 and E. coli Nissle 1917 by 33% (p = 0.03) and 48% (p = 0.03), respectively (Figure 1A). Importantly, all three probiotic strains reduced death of Caco-2 cells following challenge with both E. coli K12 and HM615: L. acidophilus ASF360 reduced death of epithelial cells by 14% (p = 0.04) following E. coli K12 treatment and 16% following infection with AIEC HM615 (p = 0.03); S. thermophilus NCIMB 41856 reduced death of epithelial cells following E. coli K12 and AIEC HM615 treatment by 10% (p = 0.01) and 18% (p = 0.007), respectively; E. coli Nissle 1917 reduced death of epithelial cells following E. coli K12 and treatment by 26% (p = 0.006) and 27% (p = 0.003), respectively (Figure 1D). In addition, S. thermophilus NCIMB 41856 was able to reduce proliferation and cell death of untreated Caco-2 cells by 24% (p = 0.008) and 22% (p = 0.02) respectively (Figure 1B and D).

Bottom Line: The isolate of S. thermophilus selected was able to reduce epithelial cell death as well as NF-κB signalling and IL-8 production triggered by pathogens.It was capable of crossing an epithelial cell barrier in conjunction with E. coli and downregulating Th1 and Th17 responses in primary human intestinal leukocytes.Therefore, we offer an alternative paradigm which considers that probiotics should be able to be competitive during periods of intestinal bleeding, trauma or stress.

View Article: PubMed Central - PubMed

Affiliation: Mucosal Microbiology, School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom.

ABSTRACT

Background: Iron is an essential cofactor in almost all biological systems. The lactic acid bacteria (LAB), frequently employed as probiotics, are unusual in having little or no requirement for iron. Iron in the human body is sequestered by transferrins and lactoferrin, limiting bacterial growth. An increase in the availability of iron in the intestine by bleeding, surgery, or under stress leads to an increase in the growth and virulence of many pathogens. Under these high iron conditions, LAB are rapidly out-competed; for the levels of probiotic bacteria to be maintained under high iron conditions they must be able to respond by increasing growth rate to compete with the normal flora. Despite this, iron-responsive genera are poorly characterised as probiotics.

Methodology/principal findings: Here, we show that a panel of probiotics are not able to respond to increased iron availability, and identify an isolate of Streptococcus thermophilus that can increase growth rate in response to increased iron availability. The isolate of S. thermophilus selected was able to reduce epithelial cell death as well as NF-κB signalling and IL-8 production triggered by pathogens. It was capable of crossing an epithelial cell barrier in conjunction with E. coli and downregulating Th1 and Th17 responses in primary human intestinal leukocytes.

Conclusions/significance: We propose that an inability to compete with potential pathogens under conditions of high iron availability such as stress and trauma may contribute to the lack of efficacy of many LAB-based probiotics in treating disease. Therefore, we offer an alternative paradigm which considers that probiotics should be able to be competitive during periods of intestinal bleeding, trauma or stress.

Show MeSH
Related in: MedlinePlus