Attaran et al[1] have recently shown that decreased susceptibility of established Helicobacter pylori(H. pylori) biofilms to specific antibiotics,was associated with the overtly enhanced transcription of two efflux pu...Attaran et al[1] have recently shown that decreased susceptibility of established Helicobacter pylori(H. pylori) biofilms to specific antibiotics,was associated with the overtly enhanced transcription of two efflux pump genes,hp1165 and hef A,involved in specific resistance to tetracycline and multiple antibiotics,respectively. Apart from antibiotic exposure,secretion of multiple antimicrobial peptides,such as human β-defensins(hβDs),by the gastric epithelium upon Hp challenge,may act as early triggering events that positively impact biofilm formation and thus,antibiotic resistance. In this regard,we undertook genomic transcriptional studies using Hp 26695 strain following exposure to sublethal,similar to those present in the gastric niche,concentrations of hβDs in an attempt to provide preliminary data regarding possible mechanisms of immune evasion and selective sensitivity of Hp. Our preliminary results indicate that hβD exposure ignites a rapid response that is largely due to the activation of several,possibly interconnected transcriptional regulatory networks – origons-that ultimately coordinate cellular processes needed to maintain homeostasis and successful adaptation of the bacterium in the gastric environment. In addition,we have shown that both antibiotic and hβD resistance are mediated by dedicated periplasmic transporters,including the aforementioned efflux pump genes hp1165 and hef A,involved in active export of antibiotics from the cell membrane and/or,as recently suggested,substrate sensing and signalling. Furthermore,itappears that sublethal doses of hβDs may enhance biofilm formation by the sustained expression of,mainly,quorum sensing-related genes. In conclusion,we provide additional data regarding the role of specific innate immune molecules in antibiotic cross-resistance mechanisms that may deepen our understanding in the context of the development of novel eradication regimens.展开更多
Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides ...Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.展开更多
AIM: To examine human β-defensin-3 (hBD-3) expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H pylori infection for better understanding the innate immune response to H pylo...AIM: To examine human β-defensin-3 (hBD-3) expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H pylori infection for better understanding the innate immune response to H pylori. METHODS: We used reverse transcription-polymerase chain reactions and immunohistochemistry to examine hBD-3 expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H pylori. Effects of hBD-3 against H pylori were also evaluated. RESULTS: The mean mRNA expression of hBD-3 in H pylori -positive specimens was significantly higher than that in H pylori-negative specimens (P = 0.0002, Mann-Whitney). In addition, unlike uninfected samples, 8 of 15 (53.33%) infected mucosal samples expressed hBD-3 protein. H pylori dose-dependently induced mRNA expression of hBD-3 in MKN45 cells, an effect inhibited by adding anti-toll-like receptor (TLR)-4 antibody. HBD-3 protein completely inhibited H pylori growth. CONCLUSION: Our results suggest that like hBD-2, hBD-3 may be involved in the pathophysiology of H pylori-induced gastritis.展开更多
文摘Attaran et al[1] have recently shown that decreased susceptibility of established Helicobacter pylori(H. pylori) biofilms to specific antibiotics,was associated with the overtly enhanced transcription of two efflux pump genes,hp1165 and hef A,involved in specific resistance to tetracycline and multiple antibiotics,respectively. Apart from antibiotic exposure,secretion of multiple antimicrobial peptides,such as human β-defensins(hβDs),by the gastric epithelium upon Hp challenge,may act as early triggering events that positively impact biofilm formation and thus,antibiotic resistance. In this regard,we undertook genomic transcriptional studies using Hp 26695 strain following exposure to sublethal,similar to those present in the gastric niche,concentrations of hβDs in an attempt to provide preliminary data regarding possible mechanisms of immune evasion and selective sensitivity of Hp. Our preliminary results indicate that hβD exposure ignites a rapid response that is largely due to the activation of several,possibly interconnected transcriptional regulatory networks – origons-that ultimately coordinate cellular processes needed to maintain homeostasis and successful adaptation of the bacterium in the gastric environment. In addition,we have shown that both antibiotic and hβD resistance are mediated by dedicated periplasmic transporters,including the aforementioned efflux pump genes hp1165 and hef A,involved in active export of antibiotics from the cell membrane and/or,as recently suggested,substrate sensing and signalling. Furthermore,itappears that sublethal doses of hβDs may enhance biofilm formation by the sustained expression of,mainly,quorum sensing-related genes. In conclusion,we provide additional data regarding the role of specific innate immune molecules in antibiotic cross-resistance mechanisms that may deepen our understanding in the context of the development of novel eradication regimens.
文摘Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.
文摘AIM: To examine human β-defensin-3 (hBD-3) expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H pylori infection for better understanding the innate immune response to H pylori. METHODS: We used reverse transcription-polymerase chain reactions and immunohistochemistry to examine hBD-3 expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H pylori. Effects of hBD-3 against H pylori were also evaluated. RESULTS: The mean mRNA expression of hBD-3 in H pylori -positive specimens was significantly higher than that in H pylori-negative specimens (P = 0.0002, Mann-Whitney). In addition, unlike uninfected samples, 8 of 15 (53.33%) infected mucosal samples expressed hBD-3 protein. H pylori dose-dependently induced mRNA expression of hBD-3 in MKN45 cells, an effect inhibited by adding anti-toll-like receptor (TLR)-4 antibody. HBD-3 protein completely inhibited H pylori growth. CONCLUSION: Our results suggest that like hBD-2, hBD-3 may be involved in the pathophysiology of H pylori-induced gastritis.
