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Activation of HIF-1α and LL-37 by commensal bacteria inhibits Candida albicans colonization.

Fan D, Coughlin LA, Neubauer MM, Kim J, Kim MS, Zhan X, Simms-Waldrip TR, Xie Y, Hooper LV, Koh AY - Nat. Med. (2015)

Bottom Line: Candida albicans colonization is required for invasive disease.Although antibiotic treatment enables C. albicans colonization, pharmacologic activation of colonic Hif1a induces CRAMP expression and results in a significant reduction of C. albicans GI colonization and a 50% decrease in mortality from invasive disease.Thus, modulating C. albicans GI colonization by activation of gut mucosal immune effectors may represent a novel therapeutic approach for preventing invasive fungal disease in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas.

ABSTRACT
Candida albicans colonization is required for invasive disease. Unlike humans, adult mice with mature intact gut microbiota are resistant to C. albicans gastrointestinal (GI) colonization, but the factors that promote C. albicans colonization resistance are unknown. Here we demonstrate that commensal anaerobic bacteria-specifically clostridial Firmicutes (clusters IV and XIVa) and Bacteroidetes-are critical for maintaining C. albicans colonization resistance in mice. Using Bacteroides thetaiotamicron as a model organism, we find that hypoxia-inducible factor-1α (HIF-1α), a transcription factor important for activating innate immune effectors, and the antimicrobial peptide LL-37 (CRAMP in mice) are key determinants of C. albicans colonization resistance. Although antibiotic treatment enables C. albicans colonization, pharmacologic activation of colonic Hif1a induces CRAMP expression and results in a significant reduction of C. albicans GI colonization and a 50% decrease in mortality from invasive disease. In the setting of antibiotics, Hif1a and Camp (which encodes CRAMP) are required for B. thetaiotamicron-induced protection against C. albicans colonization of the gut. Thus, modulating C. albicans GI colonization by activation of gut mucosal immune effectors may represent a novel therapeutic approach for preventing invasive fungal disease in humans.

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L-mimosine activation of HIf1a and Cramp in vivo decreases Candida albicans GI colonization and disseminationCandida albicans GI colonization levels in (a) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (b) Cramp KO mice treated with antibiotics, colonized with CA and then treated ± L-mimosine. n=8. Bars represent the mean ± SEM. Statistical analysis performed by Mann-Whitney test. * p<0.05; ** p<0.001; ns, not significant. Survival curves of (c) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (d) Cramp KO mice treated with antibiotic water, colonized with CA, treated ± L-mimosine for five days and then given cyclophosphamide. L-mimosine treatment continued for an additional 7 days after the first cyclophosphamide dose. n=8. Statistical analysis performed by log-rank test. * p< 0.05; ** p<0.01; ns, not significant. (e) Hif1a and Cramp mRNA levels in colons of Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice treated ± L-mimosine. n=4. All data shown are means ± SEM. Assays were performed in triplicate. Statistical analysis performed by Mann-Whitney test. * p< 0.05; ** p<0.01; ns, not significant. (g) C. albicans (red triangles) and B. theta (black circles) GI colonization levels in antibiotic-treated Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice. n= 6 for Hif1afl/fl and Cramp KO mice. n=5 for Hif1afl/fl Vil-Cre+. Black circles (B. theta) and red triangles (CA) represent results from individual animals. Horizontal lines represent the median with interquartertile range. * p<0.05, ** p<0.01. Statistical analysis by Mann-Whitney test.
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Figure 4: L-mimosine activation of HIf1a and Cramp in vivo decreases Candida albicans GI colonization and disseminationCandida albicans GI colonization levels in (a) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (b) Cramp KO mice treated with antibiotics, colonized with CA and then treated ± L-mimosine. n=8. Bars represent the mean ± SEM. Statistical analysis performed by Mann-Whitney test. * p<0.05; ** p<0.001; ns, not significant. Survival curves of (c) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (d) Cramp KO mice treated with antibiotic water, colonized with CA, treated ± L-mimosine for five days and then given cyclophosphamide. L-mimosine treatment continued for an additional 7 days after the first cyclophosphamide dose. n=8. Statistical analysis performed by log-rank test. * p< 0.05; ** p<0.01; ns, not significant. (e) Hif1a and Cramp mRNA levels in colons of Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice treated ± L-mimosine. n=4. All data shown are means ± SEM. Assays were performed in triplicate. Statistical analysis performed by Mann-Whitney test. * p< 0.05; ** p<0.01; ns, not significant. (g) C. albicans (red triangles) and B. theta (black circles) GI colonization levels in antibiotic-treated Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice. n= 6 for Hif1afl/fl and Cramp KO mice. n=5 for Hif1afl/fl Vil-Cre+. Black circles (B. theta) and red triangles (CA) represent results from individual animals. Horizontal lines represent the median with interquartertile range. * p<0.05, ** p<0.01. Statistical analysis by Mann-Whitney test.

Mentions: We next tested the importance of HIF-1α and CRAMP in vivo by using genetically engineered mice. We demonstrated that CA GI colonization levels significantly decreased in mice treated with mimosine, but this effect was ified in mimosine-treated mice that had Hif1a specifically deleted from their intestinal epithelium (Hif1afl/fl Vil-Cre+ mice, Fig. 4a). In prior observations, mortality from invasive disease significantly decreased in mice with CA GI colonization levels < 107 cfu/g feces (data not shown). Thus, we administered cyclophosphamide to induce disseminated disease4. Strikingly, mice treated with mimosine had a 50% reduction in overall mortality (p=0.038 by Fisher’s exact test) and significantly increased length of survival (p<0.001 by log-rank test) compared to untreated counterparts (Fig. 4c). Further, mimosine treatment had no measurable effect on survival in Hif1afl/fl Vil-Cre+ mice (Fig 4c). We confirmed a reduction in colonization levels and increased length of survival (p=0.0082 by log-rank test, Supplementary Figure 7) when using a second CA strain, CAF2-1.


Activation of HIF-1α and LL-37 by commensal bacteria inhibits Candida albicans colonization.

Fan D, Coughlin LA, Neubauer MM, Kim J, Kim MS, Zhan X, Simms-Waldrip TR, Xie Y, Hooper LV, Koh AY - Nat. Med. (2015)

L-mimosine activation of HIf1a and Cramp in vivo decreases Candida albicans GI colonization and disseminationCandida albicans GI colonization levels in (a) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (b) Cramp KO mice treated with antibiotics, colonized with CA and then treated ± L-mimosine. n=8. Bars represent the mean ± SEM. Statistical analysis performed by Mann-Whitney test. * p<0.05; ** p<0.001; ns, not significant. Survival curves of (c) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (d) Cramp KO mice treated with antibiotic water, colonized with CA, treated ± L-mimosine for five days and then given cyclophosphamide. L-mimosine treatment continued for an additional 7 days after the first cyclophosphamide dose. n=8. Statistical analysis performed by log-rank test. * p< 0.05; ** p<0.01; ns, not significant. (e) Hif1a and Cramp mRNA levels in colons of Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice treated ± L-mimosine. n=4. All data shown are means ± SEM. Assays were performed in triplicate. Statistical analysis performed by Mann-Whitney test. * p< 0.05; ** p<0.01; ns, not significant. (g) C. albicans (red triangles) and B. theta (black circles) GI colonization levels in antibiotic-treated Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice. n= 6 for Hif1afl/fl and Cramp KO mice. n=5 for Hif1afl/fl Vil-Cre+. Black circles (B. theta) and red triangles (CA) represent results from individual animals. Horizontal lines represent the median with interquartertile range. * p<0.05, ** p<0.01. Statistical analysis by Mann-Whitney test.
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Figure 4: L-mimosine activation of HIf1a and Cramp in vivo decreases Candida albicans GI colonization and disseminationCandida albicans GI colonization levels in (a) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (b) Cramp KO mice treated with antibiotics, colonized with CA and then treated ± L-mimosine. n=8. Bars represent the mean ± SEM. Statistical analysis performed by Mann-Whitney test. * p<0.05; ** p<0.001; ns, not significant. Survival curves of (c) Hif1afl/fl, Hif1afl/fl Vil-Cre+, and (d) Cramp KO mice treated with antibiotic water, colonized with CA, treated ± L-mimosine for five days and then given cyclophosphamide. L-mimosine treatment continued for an additional 7 days after the first cyclophosphamide dose. n=8. Statistical analysis performed by log-rank test. * p< 0.05; ** p<0.01; ns, not significant. (e) Hif1a and Cramp mRNA levels in colons of Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice treated ± L-mimosine. n=4. All data shown are means ± SEM. Assays were performed in triplicate. Statistical analysis performed by Mann-Whitney test. * p< 0.05; ** p<0.01; ns, not significant. (g) C. albicans (red triangles) and B. theta (black circles) GI colonization levels in antibiotic-treated Hif1afl/fl, Hif1afl/fl Vil-Cre+, and Cramp KO mice. n= 6 for Hif1afl/fl and Cramp KO mice. n=5 for Hif1afl/fl Vil-Cre+. Black circles (B. theta) and red triangles (CA) represent results from individual animals. Horizontal lines represent the median with interquartertile range. * p<0.05, ** p<0.01. Statistical analysis by Mann-Whitney test.
Mentions: We next tested the importance of HIF-1α and CRAMP in vivo by using genetically engineered mice. We demonstrated that CA GI colonization levels significantly decreased in mice treated with mimosine, but this effect was ified in mimosine-treated mice that had Hif1a specifically deleted from their intestinal epithelium (Hif1afl/fl Vil-Cre+ mice, Fig. 4a). In prior observations, mortality from invasive disease significantly decreased in mice with CA GI colonization levels < 107 cfu/g feces (data not shown). Thus, we administered cyclophosphamide to induce disseminated disease4. Strikingly, mice treated with mimosine had a 50% reduction in overall mortality (p=0.038 by Fisher’s exact test) and significantly increased length of survival (p<0.001 by log-rank test) compared to untreated counterparts (Fig. 4c). Further, mimosine treatment had no measurable effect on survival in Hif1afl/fl Vil-Cre+ mice (Fig 4c). We confirmed a reduction in colonization levels and increased length of survival (p=0.0082 by log-rank test, Supplementary Figure 7) when using a second CA strain, CAF2-1.

Bottom Line: Candida albicans colonization is required for invasive disease.Although antibiotic treatment enables C. albicans colonization, pharmacologic activation of colonic Hif1a induces CRAMP expression and results in a significant reduction of C. albicans GI colonization and a 50% decrease in mortality from invasive disease.Thus, modulating C. albicans GI colonization by activation of gut mucosal immune effectors may represent a novel therapeutic approach for preventing invasive fungal disease in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas.

ABSTRACT
Candida albicans colonization is required for invasive disease. Unlike humans, adult mice with mature intact gut microbiota are resistant to C. albicans gastrointestinal (GI) colonization, but the factors that promote C. albicans colonization resistance are unknown. Here we demonstrate that commensal anaerobic bacteria-specifically clostridial Firmicutes (clusters IV and XIVa) and Bacteroidetes-are critical for maintaining C. albicans colonization resistance in mice. Using Bacteroides thetaiotamicron as a model organism, we find that hypoxia-inducible factor-1α (HIF-1α), a transcription factor important for activating innate immune effectors, and the antimicrobial peptide LL-37 (CRAMP in mice) are key determinants of C. albicans colonization resistance. Although antibiotic treatment enables C. albicans colonization, pharmacologic activation of colonic Hif1a induces CRAMP expression and results in a significant reduction of C. albicans GI colonization and a 50% decrease in mortality from invasive disease. In the setting of antibiotics, Hif1a and Camp (which encodes CRAMP) are required for B. thetaiotamicron-induced protection against C. albicans colonization of the gut. Thus, modulating C. albicans GI colonization by activation of gut mucosal immune effectors may represent a novel therapeutic approach for preventing invasive fungal disease in humans.

Show MeSH
Related in: MedlinePlus