AIM:To investigate the effect of Clostridium difficile(C.difficile)infection in an interleukin 10-deficient(IL-10-/-)mouse model of inflammatory bowel disease.METHODS:Bone marrow-derived dendritic cells isolated from ...AIM:To investigate the effect of Clostridium difficile(C.difficile)infection in an interleukin 10-deficient(IL-10-/-)mouse model of inflammatory bowel disease.METHODS:Bone marrow-derived dendritic cells isolated from wild type(WT)and IL-10-/-mice were stimulated for 4 h with C.difficile toxin A(200μg/m L),and gene expression of interferon(IFN)-γ,IL-12 and IL-23was determined by real-time reverse transcription polymerase chain reaction.WT and IL-10-/-mice(n=20each)were exposed to an antibiotic cocktail for three days and then were injected with clindamycin(i.p.).Mice(n=10 WT,10 IL-10-/-)were then challenged with oral administration of C.difficile(1×105 colony forming units of strain VPI 10463).Animals were monitored daily for 7 d for signs of colitis.Colonic tissue samples were evaluated for cytokine gene expression and histopathologic analysis.RESULTS:C.difficile toxin A treatment induced IFN-γgene expression to a level that was significantly higher in BDMCs from IL-10-/-compared to those from WT mice(P<0.05).However,expression of IL-12 and IL-23 was not different among the groups.Following C.difficile administration,mice developed diarrhea and lost weight within 2-3 d.Weight loss was significantly greater in IL-10-/-compared to WT mice(P<0.05).C.difficile infection induced histopathologic features typical of colitis in both IL-10-/-and WT mice.The histopathologic severity score was significantly higher in the IL-10-/-than in WT mice(mean±standard error;5.50±0.53 vs 2.44±0.46;P<0.05).This was accompanied by a significantly greater increase in IFN-γgene expression in colonic tissues from IL-10-/-than from WT mice challenged with C.difficile(P<0.05).CONCLUSION:These results indicate that colitis is more severe after C.difficile infection in IL-10-/-mice,and that IFN-γexpression is involved in this process.展开更多
BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF...BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF-secreted toxin(BFT).Dendritic cells(DCs)play an important role in directing the nature of adaptive immune responses to bacterial infection and heme oxygenase-1(HO-1)is involved in the regulation of DC function.AIM To investigate the role of BFT in HO-1 expression in DCs.METHODS Murine DCs were generated from specific pathogen-free C57BL/6 and Nrf2−/−knockout mice.DCs were exposed to BFT,after which HO-1 expression and the related signaling factor activation were measured by quantitative RT-PCR,EMSA,fluorescent microscopy,immunoblot,and ELISA.RESULTS HO-1 expression was upregulated in DCs stimulated with BFT.Although BFT activated transcription factors such as NF-κB,AP-1,and Nrf2,activation of NF-κB and AP-1 was not involved in the induction of HO-1 expression in BFT-exposed DCs.Instead,upregulation of HO-1 expression was dependent on Nrf2 activation in DCs.Moreover,HO-1 expression via Nrf2 in DCs was regulated by mitogenactivated protein kinases such as ERK and p38.Furthermore,BFT enhanced the production of reactive oxygen species(ROS)and inhibition of ROS production resulted in a significant decrease of phospho-ERK,phospho-p38,Nrf2,and HO-1 CONCLUSION These results suggest that signaling pathways involving ROS-mediated ERK and p38 mitogen-activated protein kinases-Nrf2 activation in DCs are required for HO-1 induction during exposure to ETBF-produced BFT.展开更多
文摘AIM:To investigate the effect of Clostridium difficile(C.difficile)infection in an interleukin 10-deficient(IL-10-/-)mouse model of inflammatory bowel disease.METHODS:Bone marrow-derived dendritic cells isolated from wild type(WT)and IL-10-/-mice were stimulated for 4 h with C.difficile toxin A(200μg/m L),and gene expression of interferon(IFN)-γ,IL-12 and IL-23was determined by real-time reverse transcription polymerase chain reaction.WT and IL-10-/-mice(n=20each)were exposed to an antibiotic cocktail for three days and then were injected with clindamycin(i.p.).Mice(n=10 WT,10 IL-10-/-)were then challenged with oral administration of C.difficile(1×105 colony forming units of strain VPI 10463).Animals were monitored daily for 7 d for signs of colitis.Colonic tissue samples were evaluated for cytokine gene expression and histopathologic analysis.RESULTS:C.difficile toxin A treatment induced IFN-γgene expression to a level that was significantly higher in BDMCs from IL-10-/-compared to those from WT mice(P<0.05).However,expression of IL-12 and IL-23 was not different among the groups.Following C.difficile administration,mice developed diarrhea and lost weight within 2-3 d.Weight loss was significantly greater in IL-10-/-compared to WT mice(P<0.05).C.difficile infection induced histopathologic features typical of colitis in both IL-10-/-and WT mice.The histopathologic severity score was significantly higher in the IL-10-/-than in WT mice(mean±standard error;5.50±0.53 vs 2.44±0.46;P<0.05).This was accompanied by a significantly greater increase in IFN-γgene expression in colonic tissues from IL-10-/-than from WT mice challenged with C.difficile(P<0.05).CONCLUSION:These results indicate that colitis is more severe after C.difficile infection in IL-10-/-mice,and that IFN-γexpression is involved in this process.
基金Supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education,Science and Technology,South Korea,No.NRF-2018R1D1A1B07043350
文摘BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF-secreted toxin(BFT).Dendritic cells(DCs)play an important role in directing the nature of adaptive immune responses to bacterial infection and heme oxygenase-1(HO-1)is involved in the regulation of DC function.AIM To investigate the role of BFT in HO-1 expression in DCs.METHODS Murine DCs were generated from specific pathogen-free C57BL/6 and Nrf2−/−knockout mice.DCs were exposed to BFT,after which HO-1 expression and the related signaling factor activation were measured by quantitative RT-PCR,EMSA,fluorescent microscopy,immunoblot,and ELISA.RESULTS HO-1 expression was upregulated in DCs stimulated with BFT.Although BFT activated transcription factors such as NF-κB,AP-1,and Nrf2,activation of NF-κB and AP-1 was not involved in the induction of HO-1 expression in BFT-exposed DCs.Instead,upregulation of HO-1 expression was dependent on Nrf2 activation in DCs.Moreover,HO-1 expression via Nrf2 in DCs was regulated by mitogenactivated protein kinases such as ERK and p38.Furthermore,BFT enhanced the production of reactive oxygen species(ROS)and inhibition of ROS production resulted in a significant decrease of phospho-ERK,phospho-p38,Nrf2,and HO-1 CONCLUSION These results suggest that signaling pathways involving ROS-mediated ERK and p38 mitogen-activated protein kinases-Nrf2 activation in DCs are required for HO-1 induction during exposure to ETBF-produced BFT.
