title: In vivo microRNA-155 expression influences antigen-specific T cell-mediated immune responses generated by DNA vaccination.
abstract: BACKGROUND
  MicroRNA (miRNA) molecules are potent mediators of post-transcriptional gene silencing that are emerging to be critical in the regulation of innate and adaptive immunity.
  
  
  RESULTS
  Here we report that miR-155--an oncogenic miRNA with important function in the mammalian immune system--is induced in dendritic cells (DCs) upon maturation and potentially attenuates their ability to activate T cells. Biolistic epidermal transfection with DNA encoding miR-155 suppressed the induction of antigen-specific T cell-mediated immunity, whereas reduction of endogenous miR-155 by a partially complementary antisense sequence reversed this effect. Because DCs represent a significant component of epidermal tissue and are among the most potent of antigen-presenting cells, the inhibitory actions of miR-155 could be mediated through this subset of cells.
  
  
  CONCLUSIONS
  These results suggest that miR-155 may repress the expression of key molecules involved in lymph node migration, antigen presentation, or T cell activation in DCs, and thus forms part of a negative regulatory pathway that dampens the generation of T cell-mediated immune responses. Modulation of miR-155 expression in epidermis therefore represents a potentially promising form of gene therapy for the control of diseases ranging from autoimmunity to cancer and viral infection.
authors.affiliation: Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA. wutc@jhmi.edu.
authors.forename: Chih-Ping
authors.initials: CP
authors.lastname: Mao
authors.forename: Liangmei
authors.initials: L
authors.lastname: He
authors.forename: Ya-Chea
authors.initials: YC
authors.lastname: Tsai
authors.forename: Shiwen
authors.initials: S
authors.lastname: Peng
authors.forename: Tae Heung
authors.initials: TH
authors.lastname: Kang
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Pang
authors.forename: Archana
authors.initials: A
authors.lastname: Monie
authors.forename: Chien-Fu
authors.initials: CF
authors.lastname: Hung
authors.forename: T-C
authors.initials: TC
authors.lastname: Wu