title: Contrasting effects of IFNα on MHC class II expression in professional vs. nonprofessional APCs: Role of CIITA type IV promoter.
abstract: We previously demonstrated that, in ex vivo cultures, IFNα downregulates the expression of MHC class II (MHCII) genes in human non-professional APCs associated with pancreatic islets. IFNα has an opposing effect on MHCII expression in professional APCs. In this study, we found that the mechanism responsible for the IFNα-mediated MHCII's downregulation in human MHCII-positive non-professional antigen presenting human non-hematopoietic cell lines is the result of the negative feedback system that regulates cytokine signal transduction, which eventually inhibits promoters III and IV of CIITA gene. Because the CIITA-PIV isoform is mostly responsible for the constitutive expression of MHCII genes in non-professional APCs, we pursued and achieved the specific knockdown of CIITA-PIV mRNA in our in vitro system, obtaining a partial silencing of MHCII molecules similar to that obtained by IFNα. We believe that our results offer a new understanding of the potential significance of CIITA-PIV as a therapeutic target for interventional strategies that can manage autoimmune disease and allograft rejection with little interference on the function of professional APCs of the immune system.
authors.affiliation: Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Pisapia
authors.affiliation: Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy.
authors.forename: Giovanna Del
authors.initials: GD
authors.lastname: Pozzo
authors.affiliation: Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Barba
authors.affiliation: Department of Medicine of Columbia University Medical Center, New York, NY, USA.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Citro
authors.affiliation: Department of Medicine of Columbia University Medical Center, New York, NY, USA.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Harris
authors.affiliation: Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy ; Department of Medicine of Columbia University Medical Center, New York, NY, USA.
authors.forename: Antonella
authors.initials: A
authors.lastname: Maffei
keywords: CIITA promoter IV; IFNα; MHCII; Non-professional antigen presenting cells