Zafar Rasheed1, Nahid Akhtar, Tariq M Haqqi. 1. Department of Medicine, Division of Rheumatology, MetroHealth Medical Center/Case Western Reserve University, Hamann Bldg, Suite 586, 2500 Metro Health Drive, Cleveland, OH 44109, USA.
Abstract
OBJECTIVE: To investigate whether advanced glycation end products (AGEs) induce the expression of IL-6 and IL-8 through the receptor for AGEs (RAGE)-activated pathways in human OA chondrocytes. METHODS: OA chondrocytes were stimulated with AGE-modified BSA (AGE-BSA). Gene expression of IL-6 and IL-8 was quantified by TaqMan assays and the production was determined using ELISAs. Immunoblotting was used to analyse the activation of mitogen-activated protein kinases (MAPKs) and the degradation of IκBα. Activation of NF-κB was determined using an ELISA. Pharmacological studies to elucidate the involved pathways were executed using transfection with small interfering RNAs (siRNAs), inhibitors of MAPKs and NF-κB. RESULTS: AGE-BSA induced the expression of IL-6 and IL-8 in OA chondrocytes, which was inhibited by pre-treatment with soluble RAGE (sRAGE) or RAGE knockdown by siRNAs. Treatment with SB202190 (p38-MAPK inhibitor) or PD98059 (ERK inhibitor) inhibited AGE-BSA-induced IL-6 and IL-8 expression. However, SP600125 (JNK inhibitor) had no effect on AGE-BSA-induced IL-6 expression but inhibited the expression of IL-8. Treatment with NF-κB inhibitors suppressed AGE-BSA-induced IL-6 and IL-8 expression. CONCLUSIONS: This is the first study to demonstrate that AGEs induce the expression of IL-6 and IL-8 in OA chondrocytes. A novel finding of our studies is that in OA chondrocytes, AGE-BSA-induced expression of IL-6, but not of IL-8, was independent of the JNK pathway. Activation of NF-κB was an absolute requirement for both IL-6 and IL-8 expression. These results demonstrate that AGE-BSA-induced expression of IL-6 and IL-8 via RAGE is mediated through different MAPK signalling pathways in OA and possibly in other degenerative diseases.
OBJECTIVE: To investigate whether advanced glycation end products (AGEs) induce the expression of IL-6 and IL-8 through the receptor for AGEs (RAGE)-activated pathways in human OA chondrocytes. METHODS: OA chondrocytes were stimulated with AGE-modified BSA (AGE-BSA). Gene expression of IL-6 and IL-8 was quantified by TaqMan assays and the production was determined using ELISAs. Immunoblotting was used to analyse the activation of mitogen-activated protein kinases (MAPKs) and the degradation of IκBα. Activation of NF-κB was determined using an ELISA. Pharmacological studies to elucidate the involved pathways were executed using transfection with small interfering RNAs (siRNAs), inhibitors of MAPKs and NF-κB. RESULTS: AGE-BSA induced the expression of IL-6 and IL-8 in OA chondrocytes, which was inhibited by pre-treatment with soluble RAGE (sRAGE) or RAGE knockdown by siRNAs. Treatment with SB202190 (p38-MAPK inhibitor) or PD98059 (ERK inhibitor) inhibited AGE-BSA-induced IL-6 and IL-8 expression. However, SP600125 (JNK inhibitor) had no effect on AGE-BSA-induced IL-6 expression but inhibited the expression of IL-8. Treatment with NF-κB inhibitors suppressed AGE-BSA-induced IL-6 and IL-8 expression. CONCLUSIONS: This is the first study to demonstrate that AGEs induce the expression of IL-6 and IL-8 in OA chondrocytes. A novel finding of our studies is that in OA chondrocytes, AGE-BSA-induced expression of IL-6, but not of IL-8, was independent of the JNK pathway. Activation of NF-κB was an absolute requirement for both IL-6 and IL-8 expression. These results demonstrate that AGE-BSA-induced expression of IL-6 and IL-8 via RAGE is mediated through different MAPK signalling pathways in OA and possibly in other degenerative diseases.
Authors: Albert C Chen; Michele M Temple; Darren M Ng; Nicole Verzijl; Jeroen DeGroot; Johan M TeKoppele; Robert L Sah Journal: Arthritis Rheum Date: 2002-12
Authors: Marjan M C Steenvoorden; Tom W J Huizinga; Nicole Verzijl; Ruud A Bank; H Karel Ronday; Hilco A F Luning; Floris P J G Lafeber; René E M Toes; Jeroen DeGroot Journal: Arthritis Rheum Date: 2006-01
Authors: Zafar Rasheed; Arivarasu N Anbazhagan; Nahid Akhtar; Sangeetha Ramamurthy; Frank R Voss; Tariq M Haqqi Journal: Arthritis Res Ther Date: 2009-05-15 Impact factor: 5.156