title: Monosodium urate crystals induce oxidative stress in human synoviocytes.
abstract: Gout is the most common inflammatory arthropathy of metabolic origin and it is characterized by intense inflammation, the underlying mechanisms of which are unknown. The aim of this study was to evaluate the oxidative stress in human fibroblast-like synoviocytes (FLS) exposed to monosodium urate (MSU) crystals, which trigger an inflammatory process.
  
  
  
  Human FLS isolated from synovial tissue explants were stimulated with MSU crystals (75 μg/mL) for 24 h. Cellular viability was evaluated by crystal violet staining, apoptosis was assessed using Annexin V, and the cellular content of reactive oxygen species (ROS) and nitrogen species (RNS) (O2 (-), H2O2, NO) was assessed with image-based cytometry and fluorometric methods. In order to determine protein oxidation levels, protein carbonyls were detected through oxyblot analysis, and cell ultrastructural changes were assessed by transmission electron microscopy.
  
  
  
  The viability of FLS exposed to MSU crystals decreased by 30 % (P < 0.05), while apoptosis increased by 42 % (P = 0.01). FLS stimulated with MSU crystals exhibited a 2.1-fold increase in H2O2 content and a 1.5-fold increase in O2 (-) and NO levels. Oxyblots revealed that the spots obtained from FLS protein lysates exposed to MSU crystals exhibited protein carbonyl immunoreactivity, which reflects the presence of oxidatively modified proteins. Concomitantly, MSU crystals triggered the induction of changes in the morphostructure of FLS, such as the thickening and discontinuity of the endoplasmic reticulum, and the formation of vacuoles and misfolded glycoproteins.
  
  
  
  Our results prove that MSU crystals induce the release of ROS and RNS in FLS, subsequently oxidizing proteins and altering the cellular oxidative state of the endoplasmic reticulum, which results in FLS apoptosis.
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.|Laboratorio de Microbiología Molecular, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas (ENCB), Instituto Politécnico Nacional (IPN), Prolongación de Carpio y Plan de Ayala S/N Col. Casco de Santo Tomas, Miguel Hidalgo, 11340, Mexico City, Mexico.
authors.forename: Yessica
authors.initials: Y
authors.lastname: Zamudio-Cuevas
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Karina
authors.initials: K
authors.lastname: Martínez-Flores
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.|Biological and Health Sciences PhD program, Universidad Autónoma Metropolitana, Avenida San Rafael Atlixco 186, Iztapalapa, 09340, Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Fernández-Torres
authors.affiliation: Laboratorio de Microbiología Molecular, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas (ENCB), Instituto Politécnico Nacional (IPN), Prolongación de Carpio y Plan de Ayala S/N Col. Casco de Santo Tomas, Miguel Hidalgo, 11340, Mexico City, Mexico.
authors.forename: Yahir A
authors.initials: YA
authors.lastname: Loissell-Baltazar
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Medina-Luna
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Ambar
authors.initials: A
authors.lastname: López-Macay
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Camacho-Galindo
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Cristina
authors.initials: C
authors.lastname: Hernández-Díaz
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Mónica G
authors.initials: MG
authors.lastname: Santamaría-Olmedo
authors.affiliation: Laboratorio Central de Microscopía, Departamento de Investigación, ENCB, IPN, Prolongación de Carpio y Plan de Ayala S/N Col. Santo Tomás, Miguel Hidalgo, 11340, Mexico City, Mexico.
authors.forename: Edgar Oliver
authors.initials: EO
authors.lastname: López-Villegas
authors.affiliation: Rheumatology Unit, Department of Medicine-DIMED, University of Padova, Via Giustiniani, 2, Padova, 35128, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Oliviero
authors.affiliation: Rheumatology Unit, Department of Medicine-DIMED, University of Padova, Via Giustiniani, 2, Padova, 35128, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Scanu
authors.affiliation: Laboratorio de Microbiología Molecular, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas (ENCB), Instituto Politécnico Nacional (IPN), Prolongación de Carpio y Plan de Ayala S/N Col. Casco de Santo Tomas, Miguel Hidalgo, 11340, Mexico City, Mexico.
authors.forename: Jorge Francisco
authors.initials: JF
authors.lastname: Cerna-Cortés
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Marwin
authors.initials: M
authors.lastname: Gutierrez
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico.
authors.forename: Carlos
authors.initials: C
authors.lastname: Pineda
authors.affiliation: Laboratorio de Líquido Sinovial, Instituto Nacional de Rehabilitación "Luis Guillermo Ibarra Ibarra", Calzada México-Xochimilco 289, Tlalpan, 14389, Mexico City, Mexico. allorey@yahoo.com.
authors.forename: Alberto
authors.initials: A
authors.lastname: López-Reyes
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006073:Gout / Q000378:metabolism; D006801:Humans; D046529:Microscopy, Electron, Transmission; D018384:Oxidative Stress / Q000187:drug effects*; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D060888:Real-Time Polymerase Chain Reaction; D000070918:Synoviocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D014527:Uric Acid / Q000633:toxicity*
chemical_list: D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D014527:Uric Acid
keywords: Gout; Monosodium urate crystals; Oxidative stress; Synoviocytes