AIM:To establish the roles of lipopolysaccharide (LPS)/CD14/toll-like receptor 4 (TLR4)-mediated inflammation in a rat model of human necrotizing enterocolitis (NEC).METHODS: Six pairs of intestinal samples from human...AIM:To establish the roles of lipopolysaccharide (LPS)/CD14/toll-like receptor 4 (TLR4)-mediated inflammation in a rat model of human necrotizing enterocolitis (NEC).METHODS: Six pairs of intestinal samples from human NEC were collected before and after recovery for histological and molecular analysis of inflammatory cytokines and signaling components. In the rat NEC model, we isolated 10-cm jejunum segments and divided them into six groups (n=6) for sham operation, treatment with LPS, bowel distension, combined bowel distension and LPS stimulation, and two therapeutic groups. The potential eff icacy of a recombinant CD18 peptide and a monoclonal CD14 antibody was evaluated in the latter two groups. The serum and tissue levels of several inflammatory mediators were quantified by real-time polymerase chain reaction, ELISA and immunoblotting.RESULTS: Human acute phase NEC tissues displayed significant increases (P<0.05) in levels of TLR4, CD14, myeloid differentiation protein (MD)-2, tumor necrosis factor (TNF)-α and nuclear factor-κB when compared to those after recovery. The histological and inflammatory picture of human NEC was reproduced in rats that were treated with combined bowel distension and LPS, but not in the sham-operated and other control rats. Serum levels of interleukin-6 and TNF-α were also elevated. The NEC pathology was attenuated by treating the NEC rats with a monoclonal CD14 antibody or an LPS-neutralizing peptide.CONCLUSION:LPS and distension are required to produce the histological and inflammatory features of NEC. A potential treatment option is blocking LPS activation and leukocyte infi ltration.展开更多
AIM: Crohn's disease(CD)and ulcerative colitis(UC)are multifactorial diseases with a significant genetic background.Apart from CARD15/NOD2 gene, evidence is accumulating that molecules related to the innate immune...AIM: Crohn's disease(CD)and ulcerative colitis(UC)are multifactorial diseases with a significant genetic background.Apart from CARD15/NOD2 gene, evidence is accumulating that molecules related to the innate immune response such as CD14 or Toll-like receptor 4 (TLR4), are involved in their pathogenesis. In further exploring the genetic background of these diseases, we investigated the variations in the CARD15/NOD2 gene (Arg702Trp,Gly908Arg and Leu1007fsinsC), and polymorphisms in the TLR4 gene (Asp299Gly and Thr399Ile) as well as in the promoter of the CD14 gene (T/C at position -159) in Greek patients with CD and UC.METHODS: DNA was obtained from 120 patients with CD,85 with UC and 100 healthy individuals. Genotyping was performed by allele specific PCR or by PCR-RFLP analysis.RESULTS: The 299Gly allele frequency of the TLR4 gene and the T allele and TT genotype frequendes of the CD14 promoter were significantly higher in CD patients only compared to healthy individuals (P = 0.026＜0.05; P = 0.0048＜0.01 and P= 0.047＜0.05 respectively). Concerning the NOD2/CARD15mutations the overall presence in CD patients was significantly higher than that in UC patients or in controls.Additionally, 51.67% of the CD patients were carriers of a TLR4 and/or CD14 polymorphic allele and at least one variant of the NOD2/CARD15, compared to 27% of the UC patients. It should be pointed out that both frequencies significantly increased as compared with the 10% frequency of multiple carriers found in healthy controls. A possible interaction of the NOD2/CARD15 with TLR4 and especially CD14, increased the risk of developing inflammatory bowel disease (IBD).CONCLUSION: Our results indicate that co-existence of a mutation in either the TLR4 or CD14 gene, and in NOD2/CARD15is associated with an increased susceptibility to developing CD compared to UC, and to developing either CD or UC compared to healthy individuals.展开更多
Macrophages are activated by bacterial lipopolysaccharide (LPS) to produce inflammatory cytokines such as TNF-α or reactive oxygen species such as nitric oxide or superoxide anion. However, in the presence of an inhi...Macrophages are activated by bacterial lipopolysaccharide (LPS) to produce inflammatory cytokines such as TNF-α or reactive oxygen species such as nitric oxide or superoxide anion. However, in the presence of an inhibitor of protein synthesis, cyclohex-imide (CHX), at 10 μg/mL, LPS at 100 ng/mL induced macrophage apoptosis rapidly without producing phenotypes of activated macrophages. In order to understand the mechanism underlying LPS-induced cytotoxicity toward macrophages, we isolated mutant cells from a macrophage-like cell line, J774.1, as clones resistant against the cytotoxic effects of LPS + CHX by using a somatic cell genetics protocol. All of the mutant clones, designated as LCR mutants, showed resistance to the cell death induced by LPS + CHX as well as to that induced by higher doses of LPS alone, as did the LPS1916 mutant cell line, which had been previously established by its resistance to 100 μg/mL LPS. Characterization of the activated macrophage phenotypes revealed that these mutants showed reduced production of TNF-α and nitric oxide in response to LPS. Further analysis showed a much reduced amount of [125I]LPS-binding and lower CD14 expression on the cell surface, in spite of an adequate intracellular expression of CD14 molecules. Besides, the molecular weight of CD14 on these mutants was around 40-48 kDa, smaller than that of the wild-type JA-4 cells (around 50-55 kDa), suggesting impaired CD14 maturation in these mutants. However, expression of Toll-like receptor 4 (TLR4) and Myd 88 on the cell surface was not different between the wild type and the mutant cells. These results suggest that LCR mutants have common phenotypes of mal-expression of CD14 molecules on the macrophage cell surface, leading to not only reduced responses to LPS-mediated macrophage activation but acquisition of resistance to LPS-induced apoptotic cell death in the presence of CHX.展开更多
文摘AIM:To establish the roles of lipopolysaccharide (LPS)/CD14/toll-like receptor 4 (TLR4)-mediated inflammation in a rat model of human necrotizing enterocolitis (NEC).METHODS: Six pairs of intestinal samples from human NEC were collected before and after recovery for histological and molecular analysis of inflammatory cytokines and signaling components. In the rat NEC model, we isolated 10-cm jejunum segments and divided them into six groups (n=6) for sham operation, treatment with LPS, bowel distension, combined bowel distension and LPS stimulation, and two therapeutic groups. The potential eff icacy of a recombinant CD18 peptide and a monoclonal CD14 antibody was evaluated in the latter two groups. The serum and tissue levels of several inflammatory mediators were quantified by real-time polymerase chain reaction, ELISA and immunoblotting.RESULTS: Human acute phase NEC tissues displayed significant increases (P<0.05) in levels of TLR4, CD14, myeloid differentiation protein (MD)-2, tumor necrosis factor (TNF)-α and nuclear factor-κB when compared to those after recovery. The histological and inflammatory picture of human NEC was reproduced in rats that were treated with combined bowel distension and LPS, but not in the sham-operated and other control rats. Serum levels of interleukin-6 and TNF-α were also elevated. The NEC pathology was attenuated by treating the NEC rats with a monoclonal CD14 antibody or an LPS-neutralizing peptide.CONCLUSION:LPS and distension are required to produce the histological and inflammatory features of NEC. A potential treatment option is blocking LPS activation and leukocyte infi ltration.
基金Supported by the EU Project "Sacrohn" N. QLK2-CT-2000-00928.
文摘AIM: Crohn's disease(CD)and ulcerative colitis(UC)are multifactorial diseases with a significant genetic background.Apart from CARD15/NOD2 gene, evidence is accumulating that molecules related to the innate immune response such as CD14 or Toll-like receptor 4 (TLR4), are involved in their pathogenesis. In further exploring the genetic background of these diseases, we investigated the variations in the CARD15/NOD2 gene (Arg702Trp,Gly908Arg and Leu1007fsinsC), and polymorphisms in the TLR4 gene (Asp299Gly and Thr399Ile) as well as in the promoter of the CD14 gene (T/C at position -159) in Greek patients with CD and UC.METHODS: DNA was obtained from 120 patients with CD,85 with UC and 100 healthy individuals. Genotyping was performed by allele specific PCR or by PCR-RFLP analysis.RESULTS: The 299Gly allele frequency of the TLR4 gene and the T allele and TT genotype frequendes of the CD14 promoter were significantly higher in CD patients only compared to healthy individuals (P = 0.026＜0.05; P = 0.0048＜0.01 and P= 0.047＜0.05 respectively). Concerning the NOD2/CARD15mutations the overall presence in CD patients was significantly higher than that in UC patients or in controls.Additionally, 51.67% of the CD patients were carriers of a TLR4 and/or CD14 polymorphic allele and at least one variant of the NOD2/CARD15, compared to 27% of the UC patients. It should be pointed out that both frequencies significantly increased as compared with the 10% frequency of multiple carriers found in healthy controls. A possible interaction of the NOD2/CARD15 with TLR4 and especially CD14, increased the risk of developing inflammatory bowel disease (IBD).CONCLUSION: Our results indicate that co-existence of a mutation in either the TLR4 or CD14 gene, and in NOD2/CARD15is associated with an increased susceptibility to developing CD compared to UC, and to developing either CD or UC compared to healthy individuals.
文摘Macrophages are activated by bacterial lipopolysaccharide (LPS) to produce inflammatory cytokines such as TNF-α or reactive oxygen species such as nitric oxide or superoxide anion. However, in the presence of an inhibitor of protein synthesis, cyclohex-imide (CHX), at 10 μg/mL, LPS at 100 ng/mL induced macrophage apoptosis rapidly without producing phenotypes of activated macrophages. In order to understand the mechanism underlying LPS-induced cytotoxicity toward macrophages, we isolated mutant cells from a macrophage-like cell line, J774.1, as clones resistant against the cytotoxic effects of LPS + CHX by using a somatic cell genetics protocol. All of the mutant clones, designated as LCR mutants, showed resistance to the cell death induced by LPS + CHX as well as to that induced by higher doses of LPS alone, as did the LPS1916 mutant cell line, which had been previously established by its resistance to 100 μg/mL LPS. Characterization of the activated macrophage phenotypes revealed that these mutants showed reduced production of TNF-α and nitric oxide in response to LPS. Further analysis showed a much reduced amount of [125I]LPS-binding and lower CD14 expression on the cell surface, in spite of an adequate intracellular expression of CD14 molecules. Besides, the molecular weight of CD14 on these mutants was around 40-48 kDa, smaller than that of the wild-type JA-4 cells (around 50-55 kDa), suggesting impaired CD14 maturation in these mutants. However, expression of Toll-like receptor 4 (TLR4) and Myd 88 on the cell surface was not different between the wild type and the mutant cells. These results suggest that LCR mutants have common phenotypes of mal-expression of CD14 molecules on the macrophage cell surface, leading to not only reduced responses to LPS-mediated macrophage activation but acquisition of resistance to LPS-induced apoptotic cell death in the presence of CHX.
