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Lethal inflammasome activation by a multidrug-resistant pathobiont upon antibiotic disruption of the microbiota.

Ayres JS, Trinidad NJ, Vance RE - Nat. Med. (2012)

Bottom Line: The mammalian intestine harbors a complex microbial community that provides numerous benefits to its host.In accordance with Koch's postulates, we found the E. coli pathobiont was sufficient to activate Naip5-Nlrc4 and cause disease when injected intravenously into unmanipulated mice.These findings reveal how sepsis-like disease can result from recognition of pathobionts by the innate immune system.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular & Cell Biology, Division of Immunology & Pathogenesis, University of California, Berkeley, USA. jayres@berkeley.edu

ABSTRACT
The mammalian intestine harbors a complex microbial community that provides numerous benefits to its host. However, the microbiota can also include potentially virulent species, termed pathobiont, which can cause disease when intestinal homeostasis is disrupted. The molecular mechanisms by which pathobionts cause disease remain poorly understood. Here we describe a sepsis-like disease that occurs upon gut injury in antibiotic-treated mice. Sepsis was associated with the systemic spread of a specific multidrug-resistant Escherichia coli pathobiont that expanded markedly in the microbiota of antibiotic-treated mice. Rapid sepsis-like death required a component of the innate immune system, the Naip5-Nlrc4 inflammasome. In accordance with Koch's postulates, we found the E. coli pathobiont was sufficient to activate Naip5-Nlrc4 and cause disease when injected intravenously into unmanipulated mice. These findings reveal how sepsis-like disease can result from recognition of pathobionts by the innate immune system.

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Naip5-Nlrc4 mediates the pathogenesis of a sepsis-like syndrome in response to intestinal injury in dysbiotic mice(a) Survival of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Kaplan-Meier plot is representative of two experiments and P = 0.0003 by log-rank analysis. Wild-type (n = 13) and Nlrc4−/−Naip5−/− (n = 14).(b) Representative images of cecums and colons from wild-type and mutant female fostermates treated with AVNM+5% DSS at 3 d post DSS treatment initiation.(c) Representative images of small intestines from AVNM+5% DSS treated wild-type and mutant female fostermates at 3 d post DSS treatment initiation.(d) Rectal temperatures of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are representative of three experiments. P < 0.05 by Student t-test. Wild-type (n = 10) and Nlrc4−/−Naip5−/− (n = 7).(e) Serum BUN, CPK, AST and ALT levels at 2 d post DSS treatment initiation of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are from three experiments and analyzed by Mann Whitney t-test. * P < 0.05. Wild-type (n = 3) and Nlrc4−/− Naip5−/− (n = 3).(f) Levels of AVNM-resistant E. coli in the intestinal tracts of wild-type and Nlrc4−/−Naip5−/− male and female fostermates after 7 d of AVNM treatment. Wild-type (n = 6) and Nlrc4−/−Naip5−/− (n = 4).(g) Lung and liver levels of total AVNM-resistant E. coli-O21:H+ in AVNM+DSS-treated wild-type mice and AVNM+DSS-treated Nlrc4−/− Naip5−/− male and female fostermates 3 d post DSS treatment initiation. Black dots represent tissues isolated from mice that had no bacteria above the limit detection.
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Figure 4: Naip5-Nlrc4 mediates the pathogenesis of a sepsis-like syndrome in response to intestinal injury in dysbiotic mice(a) Survival of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Kaplan-Meier plot is representative of two experiments and P = 0.0003 by log-rank analysis. Wild-type (n = 13) and Nlrc4−/−Naip5−/− (n = 14).(b) Representative images of cecums and colons from wild-type and mutant female fostermates treated with AVNM+5% DSS at 3 d post DSS treatment initiation.(c) Representative images of small intestines from AVNM+5% DSS treated wild-type and mutant female fostermates at 3 d post DSS treatment initiation.(d) Rectal temperatures of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are representative of three experiments. P < 0.05 by Student t-test. Wild-type (n = 10) and Nlrc4−/−Naip5−/− (n = 7).(e) Serum BUN, CPK, AST and ALT levels at 2 d post DSS treatment initiation of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are from three experiments and analyzed by Mann Whitney t-test. * P < 0.05. Wild-type (n = 3) and Nlrc4−/− Naip5−/− (n = 3).(f) Levels of AVNM-resistant E. coli in the intestinal tracts of wild-type and Nlrc4−/−Naip5−/− male and female fostermates after 7 d of AVNM treatment. Wild-type (n = 6) and Nlrc4−/−Naip5−/− (n = 4).(g) Lung and liver levels of total AVNM-resistant E. coli-O21:H+ in AVNM+DSS-treated wild-type mice and AVNM+DSS-treated Nlrc4−/− Naip5−/− male and female fostermates 3 d post DSS treatment initiation. Black dots represent tissues isolated from mice that had no bacteria above the limit detection.

Mentions: Since pathogenic E. coli were previously reported to activate inflammasomes containing Naip and Nlrc4 proteins44,45, we hypothesized that the Naip5-Nlrc4 inflammasome might mediate disease in our sepsis model. Indeed, we found AVNM+DSS-induced disease progression was highly attenuated in Nlrc4−/−Naip5−/− mice (Fig. 4a – e). Importantly, AVNM-treated Nlrc4−/− Naip5−/− mutant mice exhibited similar levels of AVNM-resistant E. coli overgrowth in the intestinal tract as wild-type fostermates prior to DSS treatment, implying that inflammasome-deficiency did not exert its protective effects by modulating bacterial growth (Figure 4f and Supplementary Fig. 6a, b). Moreover, the organs of AVNM+DSS-treated Nlrc4−/−Naip5−/− were colonized with similar levels of AVNM-resistant E. coli as wild-type mice (Figure 4g and Supplementary Fig. 6c, d). These data indicate that the absence of Naip5-Nlrc4 function protects AVNM+DSS-treated mice from developing sepsis at a step after extraintestinal dissemination of E. coli-O21:H+. Since Nlrc4−/−Naip5−/− mice eventually succumb to AVNM+DSS-induced sepsis, it is likely that additional host factors also contribute to disease.


Lethal inflammasome activation by a multidrug-resistant pathobiont upon antibiotic disruption of the microbiota.

Ayres JS, Trinidad NJ, Vance RE - Nat. Med. (2012)

Naip5-Nlrc4 mediates the pathogenesis of a sepsis-like syndrome in response to intestinal injury in dysbiotic mice(a) Survival of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Kaplan-Meier plot is representative of two experiments and P = 0.0003 by log-rank analysis. Wild-type (n = 13) and Nlrc4−/−Naip5−/− (n = 14).(b) Representative images of cecums and colons from wild-type and mutant female fostermates treated with AVNM+5% DSS at 3 d post DSS treatment initiation.(c) Representative images of small intestines from AVNM+5% DSS treated wild-type and mutant female fostermates at 3 d post DSS treatment initiation.(d) Rectal temperatures of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are representative of three experiments. P < 0.05 by Student t-test. Wild-type (n = 10) and Nlrc4−/−Naip5−/− (n = 7).(e) Serum BUN, CPK, AST and ALT levels at 2 d post DSS treatment initiation of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are from three experiments and analyzed by Mann Whitney t-test. * P < 0.05. Wild-type (n = 3) and Nlrc4−/− Naip5−/− (n = 3).(f) Levels of AVNM-resistant E. coli in the intestinal tracts of wild-type and Nlrc4−/−Naip5−/− male and female fostermates after 7 d of AVNM treatment. Wild-type (n = 6) and Nlrc4−/−Naip5−/− (n = 4).(g) Lung and liver levels of total AVNM-resistant E. coli-O21:H+ in AVNM+DSS-treated wild-type mice and AVNM+DSS-treated Nlrc4−/− Naip5−/− male and female fostermates 3 d post DSS treatment initiation. Black dots represent tissues isolated from mice that had no bacteria above the limit detection.
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Figure 4: Naip5-Nlrc4 mediates the pathogenesis of a sepsis-like syndrome in response to intestinal injury in dysbiotic mice(a) Survival of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Kaplan-Meier plot is representative of two experiments and P = 0.0003 by log-rank analysis. Wild-type (n = 13) and Nlrc4−/−Naip5−/− (n = 14).(b) Representative images of cecums and colons from wild-type and mutant female fostermates treated with AVNM+5% DSS at 3 d post DSS treatment initiation.(c) Representative images of small intestines from AVNM+5% DSS treated wild-type and mutant female fostermates at 3 d post DSS treatment initiation.(d) Rectal temperatures of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are representative of three experiments. P < 0.05 by Student t-test. Wild-type (n = 10) and Nlrc4−/−Naip5−/− (n = 7).(e) Serum BUN, CPK, AST and ALT levels at 2 d post DSS treatment initiation of wild-type and Nlrc4−/−Naip5−/− male and female fostermates treated with AVNM+5% DSS. Data are from three experiments and analyzed by Mann Whitney t-test. * P < 0.05. Wild-type (n = 3) and Nlrc4−/− Naip5−/− (n = 3).(f) Levels of AVNM-resistant E. coli in the intestinal tracts of wild-type and Nlrc4−/−Naip5−/− male and female fostermates after 7 d of AVNM treatment. Wild-type (n = 6) and Nlrc4−/−Naip5−/− (n = 4).(g) Lung and liver levels of total AVNM-resistant E. coli-O21:H+ in AVNM+DSS-treated wild-type mice and AVNM+DSS-treated Nlrc4−/− Naip5−/− male and female fostermates 3 d post DSS treatment initiation. Black dots represent tissues isolated from mice that had no bacteria above the limit detection.
Mentions: Since pathogenic E. coli were previously reported to activate inflammasomes containing Naip and Nlrc4 proteins44,45, we hypothesized that the Naip5-Nlrc4 inflammasome might mediate disease in our sepsis model. Indeed, we found AVNM+DSS-induced disease progression was highly attenuated in Nlrc4−/−Naip5−/− mice (Fig. 4a – e). Importantly, AVNM-treated Nlrc4−/− Naip5−/− mutant mice exhibited similar levels of AVNM-resistant E. coli overgrowth in the intestinal tract as wild-type fostermates prior to DSS treatment, implying that inflammasome-deficiency did not exert its protective effects by modulating bacterial growth (Figure 4f and Supplementary Fig. 6a, b). Moreover, the organs of AVNM+DSS-treated Nlrc4−/−Naip5−/− were colonized with similar levels of AVNM-resistant E. coli as wild-type mice (Figure 4g and Supplementary Fig. 6c, d). These data indicate that the absence of Naip5-Nlrc4 function protects AVNM+DSS-treated mice from developing sepsis at a step after extraintestinal dissemination of E. coli-O21:H+. Since Nlrc4−/−Naip5−/− mice eventually succumb to AVNM+DSS-induced sepsis, it is likely that additional host factors also contribute to disease.

Bottom Line: The mammalian intestine harbors a complex microbial community that provides numerous benefits to its host.In accordance with Koch's postulates, we found the E. coli pathobiont was sufficient to activate Naip5-Nlrc4 and cause disease when injected intravenously into unmanipulated mice.These findings reveal how sepsis-like disease can result from recognition of pathobionts by the innate immune system.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular & Cell Biology, Division of Immunology & Pathogenesis, University of California, Berkeley, USA. jayres@berkeley.edu

ABSTRACT
The mammalian intestine harbors a complex microbial community that provides numerous benefits to its host. However, the microbiota can also include potentially virulent species, termed pathobiont, which can cause disease when intestinal homeostasis is disrupted. The molecular mechanisms by which pathobionts cause disease remain poorly understood. Here we describe a sepsis-like disease that occurs upon gut injury in antibiotic-treated mice. Sepsis was associated with the systemic spread of a specific multidrug-resistant Escherichia coli pathobiont that expanded markedly in the microbiota of antibiotic-treated mice. Rapid sepsis-like death required a component of the innate immune system, the Naip5-Nlrc4 inflammasome. In accordance with Koch's postulates, we found the E. coli pathobiont was sufficient to activate Naip5-Nlrc4 and cause disease when injected intravenously into unmanipulated mice. These findings reveal how sepsis-like disease can result from recognition of pathobionts by the innate immune system.

Show MeSH
Related in: MedlinePlus