title: Inflammation and N-formyl peptide receptors mediate the angiogenic activity of human vitreous humour in proliferative diabetic retinopathy.
abstract: Angiogenesis and inflammation characterise proliferative diabetic retinopathy (PDR), a major complication of diabetes mellitus. However, the impact of inflammation on the pathogenesis of PDR neovascularisation has not been elucidated. Here, we assessed the capacity of PDR vitreous fluid to induce pro-angiogenic/proinflammatory responses in endothelium and the contribution of the inflammation-related pattern recognition N-formyl peptide receptors (FPRs) in mediating these responses.
  
  
  
  Pooled and individual pars plana vitrectomy-derived PDR vitreous fluid ('PDR vitreous') samples were assessed in endothelial cell proliferation, motility, sprouting and morphogenesis assays, and for the capacity to induce proinflammatory transcription factor activation, reactive oxygen species production, intercellular junction disruption and leucocyte-adhesion molecule upregulation in these cells. In vivo, the pro-angiogenic/proinflammatory activity of PDR vitreous was tested in murine Matrigel plug and chick embryo chorioallantoic membrane (CAM) assays. Finally, the FPR inhibitors Boc-Phe-Leu-Phe-Leu-Phe (Boc-FLFLF) and Ac-L-Arg-Aib-L-Arg-L-Cα(Me)Phe-NH2tetrapeptide (UPARANT) were evaluated for their capacity to affect the biological responses elicited by PDR vitreous.
  
  
  
  PDR vitreous activates a pro-angiogenic/proinflammatory phenotype in endothelial cells. Accordingly, PDR vitreous triggers a potent angiogenic/inflammatory response in vivo. Notably, the different capacity of individual PDR vitreous samples to induce neovessel formation in the CAM correlates with their ability to recruit infiltrating CD45+cells. Finally, the FPR inhibitor Boc-FLFLF and the novel FPR antagonist UPARANT inhibit neovessel formation and inflammatory responses triggered by PDR vitreous in the CAM assay.
  
  
  
  This study provides evidence that inflammation mediates the angiogenic activity of PDR vitreous and paves the way for the development of FPR-targeting anti-inflammatory/anti-angiogenic approaches for PDR therapy.
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy. sara.rezzola@unibs.it.
authors.forename: Sara
authors.initials: S
authors.lastname: Rezzola
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Corsini
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Chiodelli
authors.affiliation: Department of Ophthalmology, University of Brescia, Piazzale Spedali Civili 1, Brescia, 25123, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Cancarini
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Imtiaz M
authors.initials: IM
authors.lastname: Nawaz
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Coltrini
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Mitola
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ronca
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy.
authors.forename: Mirella
authors.initials: M
authors.lastname: Belleri
authors.affiliation: Department of Chemical Sciences, 'Federico II' University of Naples, Naples, Italy.
authors.forename: Liliana
authors.initials: L
authors.lastname: Lista
authors.affiliation: Sooft Italia Spa, Montegiorgio, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Rusciano
authors.affiliation: Department of Experimental Medicine, Second University of Naples, Naples, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: De Rosa
authors.affiliation: Department of Chemical Sciences, 'Federico II' University of Naples, Naples, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Pavone
authors.affiliation: Department of Ophthalmology, University of Brescia, Piazzale Spedali Civili 1, Brescia, 25123, Italy. francesco.semeraro@unibs.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Semeraro
authors.affiliation: Department of Molecular and Translational Medicine, University of Brescia, Via Branze 39, Brescia, 25123, Italy. marco.presta@unibs.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Presta
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002460:Cell Line; D003930:Diabetic Retinopathy / Q000276:immunology / Q000378:metabolism*; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D008297:Male; D051379:Mice; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000276:immunology / Q000378:metabolism; D044042:Receptors, Formyl Peptide / Q000378:metabolism*; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: C469986:FPR1 protein, human; C469985:FPR3 protein, human; D044042:Receptors, Formyl Peptide
keywords: Angiogenesis; Diabetic retinopathy; Endothelial cells; Inflammation; N-formyl peptide receptor; Vitreous