title: Mitochondrial and oxidative stress genes are differentially expressed in neutrophils of sJIA patients treated with tocilizumab: a pilot microarray study.
abstract: BACKGROUND
  Various pathways involved in the pathogenesis of sJIA have been identified through gene expression profiling in peripheral blood mononuclear cells (PBMC), but not in neutrophils. Since neutrophils are important in tissue damage during inflammation, and are elevated as part of the acute phase response, we hypothesised that neutrophil pathways could also be important in the pathogenesis of sJIA. We therefore studied the gene profile in both PBMC and neutrophils of sJIA patients treated with tocilizumab.
  
  
  METHODS
  We studied the transcriptomes of peripheral blood mononuclear cells (PBMC) and neutrophils from eight paired samples obtained from 4 sJIA patients taken before and after treatment, selected on the basis that they achieved ACR90 responses within 12 weeks of therapy initiation with tocilizumab. RNA was extracted and gene expression profiling was performed using Affymetrix GeneChip Human Genome U133 Plus 2.0 microarray platform. A longitudinal analysis using paired t-test (p < 0.05 and FC ≥ 1.5) was applied to identify differentially expressed genes (DEGs) between the two time points followed by ingenuity pathway analysis. Gene Set Enrichment Analysis (GSEA) and quantitative real-time PCR were then performed to verify the microarray results.
  
  
  RESULTS
  Gene ontology analysis in neutrophils revealed that response to tocilizumab significantly altered genes regulating mitochondrial dysfunction and oxidative stress (p = 4.6E-05). This was independently verified with GSEA, by identifying a set of oxidative genes whose expression correlated with response to tocilizumab. In PBMC, treatment of sJIA with tocilizumab appeared to affect genes in Oncostatin M signalling and B cell pathways.
  
  
  CONCLUSIONS
  For the first time we demonstrate that neutrophils from sJIA patients responding to tocilizumab showed significantly different changes in gene expression. These data could highlight the importance of mitochondrial genes that modulate oxidative stress in the pathogenesis of sJIA.
authors: Infection, Inflammation and Rheumatology Section, Institute of Child Health, UCL, London, UK. e.omoyinmi@ucl.ac.uk.
authors: Ebun
authors: E
authors: Omoyinmi
authors: Centre for Adolescent Rheumatology, University College London, 4th Floor, Rayne Building, 5, University Street, London, WC1E 6JF, UK. rajahamb@yahoo.fr.
authors: Raja
authors: R
authors: Hamaoui
authors: Centre for Adolescent Rheumatology, University College London, 4th Floor, Rayne Building, 5, University Street, London, WC1E 6JF, UK. abryant4@hotmail.com.
authors: Annette
authors: A
authors: Bryant
authors: Infection, Inflammation and Rheumatology Section, Institute of Child Health, UCL, London, UK. jcmike1992@hotmail.com.
authors: Mike Chao
authors: MC
authors: Jiang
authors: Infection, Inflammation and Rheumatology Section, Institute of Child Health, UCL, London, UK. chokie88@gmail.com.
authors: Trin
authors: T
authors: Athigapanich
authors: Infection, Inflammation and Rheumatology Section, Institute of Child Health, UCL, London, UK. d.eleftheriou@ucl.ac.uk.
authors: Despina
authors: D
authors: Eleftheriou
authors: UCL Genomics, Institute of Child Health, London, UK. m.hubank@ucl.ac.uk.
authors: Mike
authors: M
authors: Hubank
authors: Infection, Inflammation and Rheumatology Section, Institute of Child Health, UCL, London, UK. p.brogan@ucl.ac.uk.
authors: Paul
authors: P
authors: Brogan
authors: Centre for Adolescent Rheumatology, University College London, 4th Floor, Rayne Building, 5, University Street, London, WC1E 6JF, UK. patricia.woo@ucl.ac.uk.
authors: Patricia
authors: P
authors: Woo
mesh_terms: D000293:Adolescent; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D001171:Arthritis, Juvenile / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008297:Male; D046228:Microarray Analysis / Q000379:methods*; D009504:Neutrophils / Q000378:metabolism*; D018384:Oxidative Stress / Q000235:genetics*; D010865:Pilot Projects; D012313:RNA / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D016207:Cytokines; D012313:RNA; C502936:tocilizumab