Long Intergenic Noncoding RNAs Mediate the Human Chondrocyte Inflammatory Response and Are Differentially Expressed in Osteoarthritis Cartilage

Abstract

ObjectiveTo identify long noncoding RNAs (lncRNAs), including long intergenic noncoding RNAs (lincRNAs), antisense RNAs, and pseudogenes, associated with the inflammatory response in human primary osteoarthritis (OA) chondrocytes and to explore their expression and function in OA.MethodsOA cartilage was obtained from patients with hip or knee OA following joint replacement surgery. Non‐OA cartilage was obtained from postmortem donors and patients with fracture of the neck of the femur. Primary OA chondrocytes were isolated by collagenase digestion. LncRNA expression analysis was performed by RNA sequencing (RNAseq) and quantitative reverse transcriptase–polymerase chain reaction. Modulation of lncRNA chondrocyte expression was achieved using LNA longRNA GapmeRs (Exiqon). Cytokine production was measured with Luminex.ResultsRNAseq identified 983 lncRNAs in primary human hip OA chondrocytes, 183 of which had not previously been identified. Following interleukin‐1β (IL‐1β) stimulation, we identified 125 lincRNAs that were differentially expressed. The lincRNA p50‐associated cyclooxygenase 2–extragenic RNA (PACER) and 2 novel chondrocyte inflammation–associated lincRNAs (CILinc01 and CILinc02) were differentially expressed in both knee and hip OA cartilage compared to non‐OA cartilage. In primary OA chondrocytes, these lincRNAs were rapidly and transiently induced in response to multiple proinflammatory cytokines. Knockdown of CILinc01 and CILinc02 expression in human chondrocytes significantly enhanced the IL‐1–stimulated secretion of proinflammatory cytokines.ConclusionThe inflammatory response in human OA chondrocytes is associated with widespread changes in the profile of lncRNAs, including PACER, CILinc01, and CILinc02. Differential expression of CILinc01 and CIinc02 in hip and knee OA cartilage, and their role in modulating cytokine production during the chondrocyte inflammatory response, suggest that they may play an important role in mediating inflammation‐driven cartilage degeneration in OA.

Long Noncoding RNA CIR Promotes Chondrocyte Extracellular Matrix Degradation in Osteoarthritis by Acting as a Sponge For Mir-27b

“…Meanwhile, other studies have revealed that long noncoding RNA UFC1 promotes proliferation of chondrocyte in osteoarthritis by acting as a sponge for miR-34a [29]. In the present study, we found that lncRNA-CIR upregulates in OA patients, which is consistent with previous studies [1]. Further functional study demonstrates that miR-27b inhibits lncRNA-CIR by directly targeting its 3’UTR.…”

“…Based on the aforementioned data, we speculate that lncRNA-CIR plays pivotal role in OA. As a matter of fact, many reports have found that lncRNA-CIR is involved in ECM degradation [1, 30]. Thus, it is essential to fully understand the detailed mechanism of lncRNA-CIR in OA.…”

“…Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degradation and is the leading cause of pain, physical debilitation , and shortening of the adult working age throughout the world [1] . OA is associated with chronic joint injury, dysfunction of immune response, and inflammation, which is involved in the degradation of the ECM of chondrocyte [2].…”

Long non-coding RNAs (lncRNAs) and their transcriptional control of inflammatory responses

“…PACER is overexpressed in tissue samples from osteosarcoma when compared with control tissue and osteoblasts, and it enhances osteosarcoma cell proliferation and invasion (46). It is highly expressed in both knee and hip osteoarthritis chondrocytes when compared with non-osteoarthritic samples, suggesting a possible role in mediating inflammation-driven cartilage damage in osteoarthritis (54). Lethe is found to enhance the replication of the hepatitis C virus by suppressing interferon-stimulated gene expression after a type 1 interferon response (69).…”

“…Mechanistically, THRIL acts as a scaffold through interacting with heterogeneous nuclear ribonucleoprotein L (hnRNPL), and this complex binds to the TNF-␣ promoter to induce its transcription. Up-regulated after stimulation with LPS, IL-1␤, or TNF-␣, PACER has been shown to regulate the expression of a neighboring gene, PTGS2 (COX-2), a key inflammatory gene (46,53,54). PACER functions as a decoy by binding and sequestering NF-B p50 homodimers, which lack transcription activation domains, away from the PTGS2 promoter.…”