title: Crocin exerts anti-inflammatory and anti-catabolic effects on rat intervertebral discs by suppressing the activation of JNK.
abstract: As intervertebral disc (IVD) degeneration has been proven to contribute to low back pain (LBP), drug treatment aiming at attenuating IVD degeneration may prove to be benefiical. Crocin, a bioactive component of saffron, has been found to exert anti-inflammatory effects on cartilage. In the present study, the anti-inflammatory and anti-catabolic effects of crocin on rat IVDs were analyzed in vitro and ex vivo. Nucleus pulposus (NP) cells were isolated from the lumbar IVDs of Sprague-Dawley rats. The NP cells were first treated with various concentrations of crocin, and then stimulated with lipopolysaccharide (LPS) to induce inflammation. Subsequently, RT-qPCR and enzyme-linked immunosorbent assay were carried out to measure the expression levels of catabolic enzymes, pro-inflammatory factors and the components of the extracellular matrix (ECM). In addition, western blot analysis was also used to investigate the related signaling pathways. The whole spinal motion segment (vertebra-IVD-vertebra section) of the rats was isolated and cultured in the presence or absence of LPS and crocin for 7 days. The ex vivo effects of crocin on the ECM of the IVD structures were determined by histological and biochemical analysis. In vitro, crocin significantly inhibited the LPS-induced overexpression of catabolic enzymes [matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, a disintegrin-like and metalloprotease (reprolysin type) with thrombospondin type 1 motif (ADAMTS)-4 and ADAMTS‑5], pro-inflammatory factors [interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6 and inducible nitric oxide synthase (iNOS)] and Toll-like receptor (TLR)‑2 in a concentration-dependent manner. Notably, crocin partly prevented the downregulation of aggrecan and type II collagen (collagen‑II). Moreover, crocin suppressed the LPS-induced activation of the mitogen-activated protein kinase (MAPK) pathway by inhibiting the phosphorylation of c-Jun N-terminal kinase (JNK). Ex vivo experiments demonstrated that crocin protected the rat IVDs from the LPS-induced depletion of the ECM components, including proteoglycan and collagen-II. In conclusion, crocin effectively suppressed the degeneration-related inflammation and catabolism in rat IVDs in vitro and ex vivo, suggesting that crocin has potential for use as a therapuetic strategy in the treatment of LBP.
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China.
authors.forename: Kang
authors.initials: K
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China.
authors.forename: Zhenjiang
authors.initials: Z
authors.lastname: Ma
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000494:pharmacology*; D002338:Carotenoids / Q000737:chemistry*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D007249:Inflammation / Q000188:drug therapy* / Q000378:metabolism; D007403:Intervertebral Disc / Q000187:drug effects* / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008660:Metabolism / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000893:Anti-Inflammatory Agents; D002338:Carotenoids; C029036:crocin; D048031:JNK Mitogen-Activated Protein Kinases; D020782:Matrix Metalloproteinases