title: Exogenous HIV-1 Nef upsets the IFN-γ-induced impairment of human intestinal epithelial integrity.
abstract: BACKGROUND
  The mucosal tissues play a central role in the transmission of HIV-1 infection as well as in the pathogenesis of AIDS. Despite several clinical studies reported intestinal dysfunction during HIV infection, the mechanisms underlying HIV-induced impairments of mucosal epithelial barrier are still unclear. It has been postulated that HIV-1 alters enterocytic function and HIV-1 proteins have been detected in several cell types of the intestinal mucosa. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on human epithelial cell line.
  
  
  RESULTS
  We used unstimulated or IFN-γ-stimulated Caco-2 cells, as a model for homeostatic and inflamed gastrointestinal tracts, respectively. We investigated the effect of exogenous recombinant Nef on monolayer integrity analyzing its uptake, transepithelial electrical resistance, permeability to FITC-dextran and the expression of tight junction proteins. Moreover, we measured the induction of proinflammatory mediators. Exogenous Nef was taken up by Caco-2 cells, increased intestinal epithelial permeability and upset the IFN-γ-induced reduction of transepithelial resistance, interfering with tight junction protein expression. Moreover, Nef inhibited IFN-γ-induced apoptosis and up-regulated TNF-α, IL-6 and MIP-3α production by Caco-2 cells while down-regulated IL-10 production. The simultaneous exposure of Caco-2 cells to Nef and IFN-γ did not affect cytokine secretion respect to untreated cells. Finally, we found that Nef counteracted the IFN-γ induced arachidonic acid cascade.
  
  
  CONCLUSIONS
  Our findings suggest that exogenous Nef, perturbing the IFN-γ-induced impairment of intestinal epithelial cells, could prolong cell survival, thus allowing for accumulation of viral particles. Our results may improve the understanding of AIDS pathogenesis, supporting the discovery of new therapeutic interventions.
authors.affiliation: Department of Therapeutic Research and Medicine Evaluation, Istituto Superiore di Sanità, Roma, Italy. mariagiovanna.quaranta@iss.it
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Quaranta
authors.forename: Olimpia
authors.initials: O
authors.lastname: Vincentini
authors.forename: Cristina
authors.initials: C
authors.lastname: Felli
authors.forename: Francesca
authors.initials: F
authors.lastname: Spadaro
authors.forename: Marco
authors.initials: M
authors.lastname: Silano
authors.forename: Diego
authors.initials: D
authors.lastname: Moricoli
authors.forename: Luciana
authors.initials: L
authors.lastname: Giordani
authors.forename: Marina
authors.initials: M
authors.lastname: Viora
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D016718:Arachidonic Acid / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects*; D018925:Chemokines / Q000378:metabolism; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D003911:Dextrans / Q000493:pharmacokinetics; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D057809:HEK293 Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D062826:Zonula Occludens-1 Protein; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000494:pharmacology*
chemical_list: D018925:Chemokines; D016207:Cytokines; D003911:Dextrans; D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C015219:fluorescein isothiocyanate dextran; D054311:nef Gene Products, Human Immunodeficiency Virus; C514837:nef protein, Human immunodeficiency virus 1; D016718:Arachidonic Acid; D007371:Interferon-gamma; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D016650:Fluorescein-5-isothiocyanate; D015232:Dinoprostone