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Regulation of the Inflammatory Synovial Fibroblast Phenotype by Metastasis‐Associated Lung Adenocarcinoma Transcript 1 Long Noncoding RNA in Obese Patients With Osteoarthritis
Author(s) -
Nanus Dominika E.,
Wijesinghe Susanne N.,
Pearson Mark J.,
Hadjicharalambous Marina R.,
Rosser Alex,
Davis Edward T.,
Lindsay Mark A.,
Jones Simon W.
Publication year - 2020
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.41158
Subject(s) - fibroblast , osteoarthritis , interleukin 8 , proinflammatory cytokine , long non coding rna , medicine , synovial fluid , messenger rna , rna , transcriptome , inflammation , reverse transcription polymerase chain reaction , endocrinology , microbiology and biotechnology , biology , gene expression , pathology , gene , in vitro , biochemistry , alternative medicine
Objective To identify long noncoding RNA s (lnc RNA s) associated with the inflammatory phenotype of synovial fibroblasts from obese patients with osteoarthritis ( OA ), and to explore the expression and function of these lnc RNA s. Methods Synovium was collected from normal‐weight patients with hip fracture (non‐ OA ; n = 6) and from normal‐weight (n = 8) and obese (n = 8) patients with hip OA . Expression of RNA was determined by RNA ‐sequencing and quantitative reverse transcription–polymerase chain reaction. Knockdown of lnc RNA was performed using LNA ‐based GapmeRs. Synovial fibroblast cytokine production was measured by enzyme‐linked immunosorbent assay. Results Synovial fibroblasts from obese patients with OA secreted greater levels of interleukin‐6 ( IL ‐6) (mean ± SEM 162 ± 21 pg/ml; P < 0.001) and CXCL 8 (262 ± 67 pg/ml; P < 0.05) compared to fibroblasts from normal‐weight patients with OA ( IL ‐6, 51 ± 4 pg/ml; CXCL 8, 78 ± 11 pg/ml) or non‐ OA patients ( IL ‐6, 35 ± 3 pg/ml; CXCL 8, 56 ± 6 pg/ml) (n = 6 patients per group). RNA ‐sequencing revealed that fibroblasts from obese OA patients exhibited an inflammatory transcriptome, with increased expression of proinflammatory messenger RNA s ( mRNA s) as compared to that in fibroblasts from normal‐weight OA or non‐ OA patients (>2‐fold change, P < 0.05; n = 4 patients per group). A total of 19 lnc RNA s were differentially expressed between normal‐weight OA and non‐ OA patient fibroblasts, and a further 19 lnc RNA s were differentially expressed in fibroblasts from obese OA patients compared to normal‐weight OA patients (>2‐fold change, P < 0.05 for each), which included the lnc RNA for metastasis‐associated lung adenocarcinoma transcript 1 ( MALAT 1). MALAT 1 was rapidly induced upon stimulation of OA synovial fibroblasts with proinflammatory cytokines, and was up‐regulated in the synovium from obese OA patients as compared to normal‐weight OA patients (1.6‐fold change, P < 0.001) or non‐ OA patients (6‐fold change, P < 0.001). MALAT 1 knockdown in OA synovial fibroblasts (n = 4 patients) decreased the levels of mRNA expression and protein secretion of CXCL 8 (>1.5‐fold change, P < 0.01), whereas it increased expression of mRNA s for TRIM 6 (>2‐fold change, P < 0.01), IL 7R (<2‐fold change, P < 0.01), HIST 1H1C (>1.5‐fold change, P < 0.001), and MAML 3 (>1.5‐fold change, P < 0.001). In addition, MALAT 1 knockdown inhibited the proliferation of synovial fibroblasts from obese patients with OA. Conclusion Synovial fibroblasts from obese patients with hip OA exhibit an inflammatory phenotype. MALAT 1 lnc RNA may mediate joint inflammation in obese OA patients.