Identification of microRNA-181a-5p and microRNA-4454 as mediators of facet cartilage degeneration
Akihiro Nakamura ... Igor Jurisica, Mohit Kapoor
Akihiro Nakamura ... Igor Jurisica, Mohit Kapoor
Published August 4, 2016
Citation Information: JCI Insight. 2016;1(12):e86820. doi:10.1172/jci.insight.86820.
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Categories: Research Article Cell biology

Identification of microRNA-181a-5p and microRNA-4454 as mediators of facet cartilage degeneration

Abstract

Osteoarthritis (OA) of spine (facet joints [FJs]) is one of the major causes of severe low back pain and disability worldwide. The degeneration of facet cartilage is a hallmark of FJ OA. However, endogenous mechanisms that initiate degeneration of facet cartilage are unknown, and there are no disease-modifying therapies to stop FJ OA. In this study, we have identified microRNAs (small noncoding RNAs) as mediators of FJ cartilage degeneration. We first established a cohort of patients with varying degrees of facet cartilage degeneration (control group: normal or mild facet cartilage degeneration; FJ OA group: moderate to severe facet cartilage degeneration) and then screened 2,100 miRNAs and identified 2 miRNAs (miR-181a-5p and miR-4454) that were significantly elevated in FJ OA cartilage compared with control facet cartilage. We further explored their role, function, and signaling mechanisms using computational, in vitro functional, and in vivo studies. We specifically indicate that miR-181a-5p and miR-4454 are involved in promoting inflammatory, catabolic, and cell death activity in FJ chondrocytes. This is the first report to our knowledge that identifies miR-181a-5p and miR-4454 as mediators of cartilage degeneration in FJs and potential therapeutic targets for stopping cartilage degeneration.

Authors

Akihiro Nakamura, Y. Raja Rampersaud, Anirudh Sharma, Stephen J. Lewis, Brian Wu, Poulami Datta, Kala Sundararajan, Helal Endisha, Evgeny Rossomacha, Jason S. Rockel, Igor Jurisica, Mohit Kapoor

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Establishment of a patient cohort with varying degrees of facet cartilag...

Figure 1

Establishment of a patient cohort with varying degrees of facet cartilage degeneration and MRI and histological analyses of facet joint degeneration.

(A) Representative MRI of patients with lumbar disc herniation (LDH; n = 21) showing grade 0 (normal) or grade 1 (mild) facet joint (FJ) degeneration scores and FJ osteoarthritis (FJ OA; n = 34) patients showing grade 2 (moderate) or grade 3 (severe) FJ degeneration scores,exhibiting narrowed joint space and presence of osteophytes. Histological analysis using Safranin O/fast green staining showing facet cartilage with no degeneration, mild degeneration, moderate degeneration, and severe degeneration. Original magnification, ×10. (B) Osteoarthritis Research Society International (OARSI) scores in control (n = 21) and FJ OA (n = 34) cartilage. (C) Expression of OA catabolic, inflammatory, and matrix markers. Real-time PCR showed significant increases in the expression of major catabolic marker (MMP13) and inflammatory markers (TNFA, IL6, and MCP1) and a decrease in the expression of major cartilage matrix molecule (COL2A1) in FJ OA cartilage (n = 12) compared with control cartilage (n = 7). (D) Representative immunohistochemistry images of control (grade 0) and FJ OA cartilage (grade 3) stained for poly (ADP-ribose) polymerase (PARP) p85 and TUNEL. The number of PARP p85– and TUNEL-positive cells in FJ OA cartilage compared with control cartilage was quantified (n = 4/group). Original magnification, ×20. For data presented as box-and-whiskers plots, horizontal lines and cross marks indicate the medians and the means, boxes indicate 25th to 75th percentiles, and whiskers indicate minimum and maximum values of the data set. The significance of differences in the levels of expression between the control and FJ OA groups was determined using a 2-tailed Student’s t test. *P < 0.05, **P < 0.01.