en Cellular and molecular biology Cellular and molecular biology پژوهشي Research <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span calibri="" style="font-family:"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Introduction: </span></span></span></b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Osteoarthritis is a public health concern that leads to disability due to chronic pain, stiffness, sleep disturbance, and depression.</span></span></span> <span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">D-limonene&nbsp;&nbsp; &nbsp;is a racemic mixture of limonene, a natural cyclic monoterpene, and the major component of the oil extracted from the citrus rind with chemo-preventive and anti-inflammatory activities.</span></span></span> <span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">The purpose of this study was to investigate </span></span></span><span lang="EN-GB" style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">the anti-inflammatory properties of D-limonene&nbsp; &nbsp;compared with dexamethasone and ibuprofen in </span></span></span><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">bovine fibroblast-like synoviocyte cells (BFLSc) as well as Human THP-1 monocyte/macrophage-like cells.</span></span></span><span lang="EN-GB" style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black"></span></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span calibri="" style="font-family:"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Materials and Methods</span></span></span></b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">: BFLSc was isolated from the synovial membrane of the metacarpal joint cartilage of an 8-month-old Holstein. THP-1 cells were prepared by the Pasteur Institute of Iran. Cells were cultivated and exposed to 20 ng/ml lipopolysaccharide (LPS) stimulation without, or in the presence of, ibuprofen, dexamethasone, or D-limonene (7.5&micro;g/ml). The gene expressions of cyclooxygenase-2 (COX-2), Interleukin-1&beta; (IL-1&beta;), inducible nitric oxide synthase (iNOS), and Tumor necrosis factor alpha (TNF-&alpha;) were evaluated by real-time PCR. Concentrations of Nitric Oxide (NO), and Prostaglandin-E₂ (PGE2) were measured by ELISA methods. </span></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span calibri="" style="font-family:"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Results: </span></span></span></b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times="">The inhibitory effects of D-limonene&nbsp; &nbsp;included dose-dependent decreases in the expression of iNOS and COX-2 proteins (P < 0.05). The treated cells secreted increased amounts of COX-2, IL-1&beta;, iNOS, TNF-&alpha;, NO, and PGE2 in response to LPS stimulation in all conditions. D-limonene quenched the gene expression of COX-2, iL-1&beta;, iNOS, and TNF-&alpha;, in BFLSc, and the production of PGE2 and NO in monocyte/macrophage cells alike dexamethasone, and ibuprofen. <b><span style="color:black"></span></b></span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span calibri="" style="font-family:"><b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">Conclusion: </span></span></span></b><span style="font-size:12.0pt"><span new="" roman="" style="font-family:" times=""><span style="color:black">The results obtained in this study show that D-limonene&nbsp; &nbsp;probably exerts anti-inflammatory effects through the suppression of TNF-&alpha;, IL-1&beta;, COX-2, and iNOS and NO, PGE2 production.</span></span></span></span></span></span></span><br> &nbsp; D-limonene, Osteoarthritis, Proinflammatory cytokine, THP-1, Bovine fibroblast-like synoviocytes cells 1 14 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-612-1&slc_lang=en&sid=1 Maghsoudi Hossein hosseinm2002@gmail.com 10031947532846006987 10031947532846006987 Yes Department of Biotechnology, Payame Nour University, Tehran Iran Enayatollah Yazadanpanah 10031947532846006988 10031947532846006988 No Department of Biology, Payame Nour University, Tehran, Iran