Browsing by Author "Saraiva-Pava, Kathy"
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- Characterization of new human gastric epithelial cell linesPublication . Saraiva-Pava, Kathy; Navabi, N.; Lindén, Sarah; Oleastro, Mónica; Roxo-Rosa, MónicaThe lack of a cellular model which correctly mimics the natural niche of the pathogen Helicobacter pylori is still limitative for the study of this infection. Aiming to overcome this limitation, we have previously isolated clones of a subpopulation of the widely used heterogenic NCI-N87 (ATCC CRL-5822) gastric cell line1, those presenting typical epithelial markers and a progenitor-like phenotype (simultaneous synthesis of mucus and zymogens). For that, we stably-transduced the NCIN87 cells with human telomerase reverse-transcriptase (hTERT) catalytic subunit (pGRN145 plasmid, ATCC MBA-141), using the FuGENE-HD reagent (Roche). The two most promising NCI-N87-derived clones (C5 and C6) were shown to be composed of cells with homogenous phenotype with ability to grow in adherent monolayers, to produce gastric zymogens (hematoxylin staining) and to produce and secrete neutral mucins (Periodic-Acid-Schiff staining). Preliminary results have also shown that they are able to generate transepithelial electrical resistance and the ability of C5 to produce and secrete acidic mucins (Alcian-Blue staining). We are now clarifying the identity of the mucin species C5 and C6 produce by immunohistochemical analysis and zymogens (Pepsinogen) by western-blot. Moreover, the subcellular localization (immunocytochemistry) of adherens and tight-junctions’ proteins (E-cadherin and ZO-1) and the polarization status of both clones is now under evaluation. Due to their improved properties, compared to the heterogeneous parental line, these NCI-N87-derived clones are promising models of the human gastric epithelium.
- The ulcerogenic profile of Helicobacter pylori paediatric strains associated with peptic ulcer disease.Publication . Vitoriano, Inês; Saraiva-Pava, Kathy; Rocha-Gonçalves, António; Alves-Matos, Pedro; Vale, Filipa; Santos, Andrea; Lopes, Ana Isabel; Oleastro, Mónica; Roxo-Rosa, MónicaHelicobacter pylori infection is the major cause of paediatric peptic ulcer disease (PUD). In children with no other aetiology for the disease, this rare event occurs shortly after infection, presuming a still poorly understood higher susceptibility of the patient and highlighting the virulence of the implicated strain. Recently, we showed that the enhanced virulence of a group of paediatric ulcerogenic-strains result from a synergy between their ability to better adapt to the hostility of their niche and the expression of cagA, vacAs1, oipA ‘‘on’’ status, homB and jhp5621. Accordingly, these ulcerogenic strains share a particular proteome profile, providing them with better antioxidant defences, a metabolism favouring the biosynthesis of aromatic amino acids and higher motility1. Corroborating these findings, our preliminary data on electronic microscopic analyses demonstrated the presence of more abundant flagella in PUD-associated paediatric strains, in contrast to the control strain, a paediatric strain associated with non-ulcer dyspepsia (NUD). Compared with paediatric NUD-associated isolates, ulcerogenic H. pylori strains present a greater ability to induce a marked decrease in the gastric cells’ viability and to cause them severe cytoskeleton damage and mucins’ production/secretion impairment1. To uncover the underlying molecular mechanisms, we are now characterizing the modifications induced by these strains in the proteome of human gastric cells, during in vitro infection, by two-dimensional gel electrophoresis followed by mass-spectrometry.
- Ulcerogenic Helicobacter pylori Strains Isolated from Children: A Contribution to Get Insight into the Virulence of the BacteriaPublication . Vitoriano, Inês; Saraiva-Pava, Kathy; Rocha-Gonçalves, Alexandra; Santos, Andrea; Lopes, Ana Isabel; Oleastro, Mónica; Roxo-Rosa, MónicaInfection with Helicobacter pylori is the major cause for the development of peptic ulcer disease (PUD). In children, with no other etiology for the disease, this rare event occurs shortly after infection. In these young patients, habits of smoking, diet, consumption of alcohol and non-steroid anti-inflammatory drugs and stress, in addition to the genetic susceptibility of the patient, represent a minor influence. Accordingly, the virulence of the implicated H. pylori strain should play a crucial role in the development of PUD. Corroborating this, our in vitro infection assays comparing a pool of five H. pylori strains isolated from children with PUD to a pool of five other pediatric clinical isolates associated with non-ulcer dyspepsia (NUD) showed the greater ability of PUD strains to induce a marked decrease in the viability of gastric cells and to cause severe damage in the cells cytoskeleton as well as an impairment in the production/secretion of mucins. To uncover virulence features, we compared the proteome of these two groups of H. pylori strains. Two-dimensional gel electrophoresis followed by mass-spectrometry allowed us to detect 27 differentially expressed proteins between them. In addition to the presence of genes encoding well established virulence factors, namely cagA, vacAs1, oipA "on" status, homB and jhp562 genes, the pediatric ulcerogenic strains shared a proteome profile characterized by changes in the abundance of: motility-associated proteins, accounting for higher motility; antioxidant proteins, which may confer increased resistance to inflammation; and enzymes involved in key steps in the metabolism of glucose, amino acids and urea, which may be advantageous to face fluctuations of nutrients. In conclusion, the enhanced virulence of the pediatric ulcerogenic H. pylori strains may result from a synergy between their natural ability to better adapt to the hostile human stomach and the expression of the established virulence factors.
- Ulcerogenic profile of helicobacter pylori pediatric strains: a contribution to get insight into the virulence of the BacteriaPublication . Vitoriano, Inês; Saraiva-Pava, Kathy; Rocha-Gonçalves, Alexandra; Santos, Andrea; Lopes, Ana Isabel; Oleastro, Mónica; Roxo-Rosa, Mónica