title: Leukocyte response is regulated by microRNA let7i in patients with acute ischemic stroke.
abstract: OBJECTIVE
  To evaluate microRNA let7i in ischemic stroke and its regulation of leukocytes.
  
  
  METHODS
  A total of 212 patients were studied: 106 with acute ischemic stroke and 106 controls matched for risk factors. RNA from circulating leukocytes was isolated from blood collected in PAXgene tubes. Let7i microRNA expression was assessed using TaqMan quantitative reverse transcription PCR. To assess let7i regulation of gene expression in stroke, messenger RNA (mRNA) from leukocytes was measured by whole-genome Human Transcriptome Array Affymetrix microarray. Given microRNAs act to destabilize and degrade their target mRNA, mRNAs that inversely correlated with let7i were identified. To demonstrate let7i posttranscriptional regulation of target genes, a 3' untranslated region luciferase assay was performed. Target protein expression was assessed using ELISA.
  
  
  RESULTS
  Let7i was decreased in patients with acute ischemic stroke (fold change -1.70, p < 0.00001). A modest inverse correlation between let7i and NIH Stroke Scale score at admission (r = -0.32, p = 0.02), infarct volume (r = -0.21, p = 0.04), and plasma MMP9 (r = -0.46, p = 0.01) was identified. The decrease in let7i was associated with increased expression of several of its mRNA targets, including CD86, CXCL8, and HMGB1. In vitro studies confirm let7i posttranscriptional regulation of target genes CD86, CXCL8, and HMGB1. Functional analysis predicted let7i regulates pathways involved in leukocyte activation, recruitment, and proliferation including canonical pathways of CD86 signaling in T helper cells, HMGB1 signaling, and CXCL8 signaling.
  
  
  CONCLUSIONS
  Let7i is decreased in circulating leukocytes of patients with acute ischemic stroke. Mechanisms by which let7i regulates inflammatory response post stroke include targeting CD86, CXCL8, and HMGB1.
authors: From the Department of Neurology, University of California at Davis, Sacramento. gcjickling@ucdavis.edu.
authors: Glen C
authors: GC
authors: Jickling
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Bradley P
authors: BP
authors: Ander
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Natasha
authors: N
authors: Shroff
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Miles
authors: M
authors: Orantia
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Boryana
authors: B
authors: Stamova
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Cheryl
authors: C
authors: Dykstra-Aiello
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Heather
authors: H
authors: Hull
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Xinhua
authors: X
authors: Zhan
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: DaZhi
authors: D
authors: Liu
authors: From the Department of Neurology, University of California at Davis, Sacramento.
authors: Frank R
authors: FR
authors: Sharp
mesh_terms: D051940:B7-2 Antigen / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis; D002545:Brain Ischemia / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D024243:HMGB1 Protein / Q000097:blood; D006801:Humans; D016209:Interleukin-8 / Q000097:blood; D007962:Leukocytes / Q000378:metabolism*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000097:blood; D035683:MicroRNAs / Q000097:blood*; D046228:Microarray Analysis; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000097:blood*
chemical_list: D051940:B7-2 Antigen; D015415:Biomarkers; C497964:CD86 protein, human; C508606:CXCL8 protein, human; D024243:HMGB1 Protein; C585491:HMGB1 protein, human; D016209:Interleukin-8; D035683:MicroRNAs; D012333:RNA, Messenger; C487931:mirnlet7 microRNA, human; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9