title: Human cytokines activate JAK-STAT signaling pathway in porcine ocular tissue.
abstract: BACKGROUND
  The JAK/STAT (Janus Tyrosine Kinase, Signal Transducers and Activators of Transcription) pathway is associated with cytokine or growth factor receptors and it is critical for growth control, developmental regulation and homeostasis. The use of porcine ocular cells as putative xenotransplants appears theoretically possible. The aim of this study was to investigate the response of various porcine ocular cells in vitro to human cytokines in regard to the activation of JAK-STAT signaling pathways.
  
  
  METHODS
  Porcine lens epithelial cells, pigmented iris epithelial cells and pigmented ciliary body cells were used in this study. These cells were isolated from freshly enucleated porcine eyes by enzymatic digestion. Cultured cells between passages 3-8 were used in all experiments. Electromobility shift assay (EMSA), proliferation assay, immunofluorescence staining and flow cytometry were used to evaluate the JAK-STAT signaling pathway in these cells.
  
  
  RESULTS
  JAK/STAT signaling pathways could be activated in porcine pigmented epithelial ciliary body cells, in pigmented iris epithelial cells and in lens epithelial cells in response to porcine and human interferons and cytokines. All cells showed very strong STAT1 activation upon stimulation with porcine interferon-gamma. Porcine ocular cells also respond to human cytokines; IFN-alpha induced strong activation of STAT1 in EMSA, flow cytometry and immunofluorescence experiments whereas activation of STAT3 was less strong in EMSA, but strong in flow cytometry and immunofluorescence. Human recombinant IL-6 activated STAT3 and human IL-4 activated STAT6. With the help of immunofluorescence assay and flow cytometry we observed nuclear localization of STAT proteins after activation of porcine ocular cells with cytokines and interferons. Human IFN-α had an inhibitory effect on porcine ocular cells in proliferation assays.
  
  
  CONCLUSIONS
  Our study demonstrated that some types of human cytokines and interferon activate intracellular JAK-STAT signaling pathways in porcine ocular cells. We hypothesize that direct stimulation of the JAK-STAT pathway in porcine cells in response to human cytokines will lead to complications or failure, if pig-to-human ocular tissue xenotransplantation were to be carried out. For successful xenotransplantation among other obstacles there must be new approaches developed to regulate signaling pathways.
authors.affiliation: Department of Biomedicine, University of Basel and University Hospital Basel, Basel, Switzerland; Institute of Chemistry and Bioanalytics, University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Fasler-Kan
authors.forename: Natasha S
authors.initials: NS
authors.lastname: Barteneva
authors.forename: Sylvia
authors.initials: S
authors.lastname: Ketterer
authors.forename: Kerstin
authors.initials: K
authors.lastname: Wunderlich
authors.forename: Anca
authors.initials: A
authors.lastname: Reschner
authors.forename: Asil
authors.initials: A
authors.lastname: Nurzhanova
authors.forename: Josef
authors.initials: J
authors.lastname: Flammer
authors.forename: Jörg
authors.initials: J
authors.lastname: Huwyler
authors.forename: Peter
authors.initials: P
authors.lastname: Meyer
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002924:Ciliary Body / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism; D005123:Eye / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D005260:Female; D064593:Heterografts; D006801:Humans; D007372:Interferons / Q000378:metabolism; D007498:Iris / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D053612:Janus Kinases / Q000378:metabolism*; D007908:Lens, Crystalline / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008297:Male; D050791:STAT Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction; D013045:Species Specificity; D034421:Sus scrofa / Q000276:immunology* / Q000378:metabolism*
chemical_list: D016207:Cytokines; D050791:STAT Transcription Factors; D007372:Interferons; D053612:Janus Kinases
keywords: STAT proteins; cytokine signaling; interferon; pig retina; xenotransplantation