Modulation of the oxidative stress and inflammatory cytokine response by thymoquinone in the collagen induced arthritis in Wistar rats Sadiq Umar a , Jamil Zargan a , Khalid Umar d , Sayeed Ahmad b , Chandra Kant Katiyar c , Haider A. Khan a,⇑ a Clinical Toxicology Laboratory, Department of Medical Elementology & Toxicology, Jamia Hamdard (Hamdard University), New Delhi 110062, India b Faculty of Pharmacy, Jamia Hamdard (Hamdard University), New Delhi 110062, India c Ayurvedic Research Lab., Dabur Research Centre, Ghaziabad 201010, UP, India d Department of chemistry, Aligarh Muslim University, Aligarh 200202, UP, India article info Article history: Received 16 December 2011 Received in revised form 22 February 2012 Accepted 8 March 2012 Available online 19 March 2012 Keywords: Thymoquinone Collagen induced arthritis TNF-a IL-6 PGE 2 Nitric oxide abstract Thymoquinone (TQ) is the major active compound derived from Nigella sativa. Our aim of this work was to evaluate the antioxidant and antiarthritic activity of TQ in Wistar rat by collagen induced arthritis (CIA). TQ was administered at a dose of 5 mg kg À1 body weight once daily for 21 days. The effects of treat- ment in the rats were assessed by biochemical (articular elastase, MPO, LPO, GSH, catalase, SOD and NO), inflammatory mediators (IL-1b, IL-6, TNF-a, IL-10, IFN-c and PGE 2 ) and histological studies in joints. TQ was effective in bringing significant changes on all the parameters (articular elastase, MPO, LPO, GSH, cat- alase, SOD and NO) studied. Oral administration of TQ resulted in significantly reduced the levels of pro- inflammatory mediators (IL-1b, IL-6, TNF-a, IFN-c and PGE 2 ) and increased level of IL-10. The protective effects of TQ against RA were also evident from the decrease in arthritis scoring and bone histology. In conclusion, the fact that TQ abolished a number of factors known to be involved in RA pathogenesis indi- cates that the administration of thymoquinone may have potential value in the treatment of inflamma- tory disease. Ó 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by cellular infiltration and proliferation of synovium, leading to progressive destruction of the joints [24,45,61]. There has been progress in defining aetiology and pathogenesis of this disease but exact mechanism still remains obscure. Collagen-in- duced arthritis (CIA) is most commonly used animal model of inflammatory polyarthritis with clinical and pathological features similar to human rheumatoid arthritis (RA) [7,16]. The significance of this model lies in the fact that collagen type II is the major constituent protein of the cartilage in the diarthrodial joints, the primary site affected in RA [28]. In RA, the balance between pro-inflammatory and anti-inflam- matory cytokines determines the degree and extent of inflamma- tion [26,54]. Proinflammatory cytokines like interleukin (IL-1b), tumor necrosis factor (TNF-a), and IL-6 are highly expressed in the rheumatoid joint and play key role in the pathogenesis of RA [20]. Fibroblast like synoviocytes (FLS), in response to these cyto- kines produce chemokines, metalloproteinases (MMPs), prosta- glandin E 2 (PGE 2 ) and cycloxygenase-2 (COX-2) which further promote inflammation, hyperplasia and cartilage destruction [52]. A number of other biochemical mediators also act to initiate and perpetuate the inflammatory reaction. Reactive oxygen species (ROS) may perpetuate inflammation by facilitating the generation of chemotactic factors at the local site [27,52,58]. Superoxide anion radical, the peroxynitrite anion and the hydroxyl radical are the major ROS generated during the disease condition [13,36]. Poly- morphonuclear cells (PMNs) alter IgG by generating free radical, which could in turn activate PMNs to generate additional superox- ides [12,62]. Nitric oxide is a free radical that serves as an impor- tant messenger molecule in inflammatory conditions [19,41]. Pro-inflammatory cytokines induce the expression of iNOS in num- ber of cells, including fibroblasts [8,21,31,37,47]. Decreased pro- duction of NO via suppressing or inhibiting iNOS reduces arthritic symptoms and affords protection [33] against arthritis. Current treatment modalities for RA either produce symptom- atic relief (non-steroidal anti-inflammatory drugs; NSAIDs) or modify the disease process (disease-modifying anti-rheumatic drugs; DMARDs). Though effective, their use is also limited by their side effects including gastrointestinal ulcers and perforation, cardiovascular complications and emergence of opportunistic infections due to immunosuppressant [29,42]. In recent decades, many herbs and natural compounds have been receiving increas- ing public interest as complementary and alternative medicine (CAM) [1] and both clinical and basic research laboratories have 0009-2797/$ - see front matter Ó 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cbi.2012.03.003 ⇑ Corresponding author. Tel.: +91 9910940516; fax: +91 1126059663. E-mail address: halitox@gmail.com (H.A. Khan). Chemico-Biological Interactions 197 (2012) 40–46 Contents lists available at SciVerse ScienceDirect Chemico-Biological Interactions journal homepage: www.elsevier.com/locate/chembioint