title: MicroRNA-146a reduces IL-1 dependent inflammatory responses in the intervertebral disc.
abstract: Because miR-146a expression in articular chondrocytes is associated with osteoarthritis (OA), we assessed whether miR-146a is linked to cartilage degeneration in the spine. Monolayer cultures of nucleus pulposus (NP) cells from the intervertebral discs (IVD) of bovine tails were transfected with a miR-146a mimic. To provoke inflammatory responses and catabolic extracellular matrix (ECM) degradation, cells were co-treated with interleukin-1 (IL-1). Transfection of miR-146a decreases IL-1 induced mRNA levels of inflammatory genes and catabolic proteases in NP cells based on quantitative real-time reverse transcriptase PCR (qRT-PCR) analysis. Similarly, miR146a suppresses IL-1 induced protein levels of matrix metalloproteinases and aggrecanases as revealed by immunoblotting. Disc segments from wild type (WT) and miR-146a knockout (KO) mice were cultured ex vivo in the presence or absence of IL-1 for 3days. Histological and immuno-histochemical (IHC) analyses of disc organ cultures revealed that IL-1 mediates changes in proteoglycan (PG) content and in-situ levels of catabolic proteins (MMP-13 and ADAMTS-5) in the nucleus pulposus of the disc. However, these IL-1 effects are more pronounced in miR-146a KO discs compared to WT discs. For example, absence of miR-146a increases the percentage of MMP-13 and ADAMTS-5 positive cells after treatment with IL-1. Thus, miR-146a appears to protect against IL-1 induced IVD degeneration and inflammation. Stimulation of endogenous miR-146a expression or exogenous delivery of miRNA-146a are viable therapeutic strategies that may decelerate disc degeneration and regain a normal homeostatic balance in extracellular matrix production and turn-over.
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA; Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA; Department of Orthopedic Surgery, PLA309 Hospital, Beijing 100091, China.
authors.forename: Su-Xi
authors.initials: SX
authors.lastname: Gu
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Hamilton
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Chee
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Kc
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Di
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
authors.affiliation: The Division of Natural Medical Sciences, College of Health Science, Chosun University, Gwangju 501-759, Republic of Korea.
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Chun-do
authors.initials: CD
authors.lastname: Oh
authors.affiliation: Department of Orthopedic Surgery, PLA309 Hospital, Beijing 100091, China. Electronic address: 309mayuanzheng@gmail.com.
authors.forename: Yuan-Zheng
authors.initials: YZ
authors.lastname: Ma
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN 55905, USA; Department of Biochemistry & Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA. Electronic address: vanwijnen.andre@mayo.edu.
authors.forename: Andre J
authors.initials: AJ
authors.lastname: van Wijnen
authors.affiliation: Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA; Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA; Department of Internal Medicine Section of Rheumatology, Rush University Medical Center, Chicago, IL 60612, USA; Department of Bioengineering, University of Illinois at Chicago, IL 60612, USA. Electronic address: Hee-Jeong_Sampen@rush.edu.
authors.forename: Hee-Jeong
authors.initials: HJ
authors.lastname: Im
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000071116:ADAMTS5 Protein; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism; D005786:Gene Expression Regulation; D006706:Homeostasis; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007249:Inflammation / Q000378:metabolism*; D007375:Interleukin-1 / Q000494:pharmacology*; D007403:Intervertebral Disc / Q000378:metabolism*; D055959:Intervertebral Disc Degeneration / Q000378:metabolism*; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism; D014162:Transfection
chemical_list: D007375:Interleukin-1; D035683:MicroRNAs; C534190:Mirn146 microRNA, mouse; D011509:Proteoglycans; D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; C498489:Adamts5 protein, mouse; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse
keywords: ADAMTS-5; IL-1; Intervertebral disc degeneration; MMP-13; Nucleus pulposus; miR-146a