Objective. To analyze the differences in gene expression profiles of chondrocytes in intact and damaged regions of cartilage from the same knee joint of patients with osteoarthritis (OA) of the knee.Methods. We compared messenger RNA expression profiles in regions of intact and damaged cartilage (classified according to the Mankin scale) obtained from patients with knee OA. Five pairs of intact and damaged regions of OA cartilage were evaluated by oligonucleotide array analysis using a double in vitro transcription amplification technique. The microarray data were confirmed by real-time quantitative polymerase chain reaction (PCR) amplification and were compared with previously published data.Results. About 1,500 transcripts, which corresponded to 8% of the expressed transcripts, showed >2-fold differences in expression between the cartilage tissue pairs. Approximately 10% of these transcripts (n ‫؍‬ 151) were commonly expressed in the 5 patient samples. Accordingly, 114 genes (35 genes expressed in intact > damaged; 79 genes expressed in intact < damaged) were selected. The expression of some genes related to the wound-healing process, including cell proliferation and interstitial collagen synthesis, was higher in damaged regions than in intact regions, similar to the findings for genes that inhibit matrix degradation. Comparisons of the real-time quantitative PCR data with the previously reported data support the validity of our microarray data.Conclusion. Differences between intact and damaged regions of OA cartilage exhibited a similar pattern among the 5 patients examined, indicating the presence of common mechanisms that contribute to cartilage destruction. Elucidation of this mechanism is important for the development of effective treatments for OA.

Objective. To identify novel genes associated with dysregulated proliferation of activated synovial fibroblasts, which are involved in arthritic joint destruction.Methods. We performed transcriptome analysis to identify genes that were up-regulated in the foot joints of mice with collagen-induced arthritis (CIA). The effect of candidate genes on proliferation of synovial fibroblasts was screened using antisense oligodeoxynucleotides and small interfering RNAs (siRNAs). We characterized the expression and function of a novel gene, synoviocyte proliferation-associated in collageninduced arthritis 1 (SPACIA1)/serum amyloid A-like 1 (SAAL1) using antibodies and siRNA and established transgenic mice to examine the effect of SPACIA1/ SAAL1 overexpression in CIA.Results. Human and mouse SPACIA1/SAAL1 encoded 474 amino acid proteins that shared 80% homology. SPACIA1/SAAL1 was primarily expressed in the nucleus of rheumatoid arthritis (RA) synovial fibroblasts and was highly expressed in the hyperplastic lining of inflamed synovium. In addition, its expression level in RA-or osteoarthritis (OA)-affected synovial tissue was positively correlated with the thickness of the synovial lining. Furthermore, SPACIA1/SAAL1 siRNA inhibited the proliferation of synovial fibroblasts, especially tumor necrosis factor ␣-induced synovial fibroblasts, by blocking entry into the S phase without inducing apoptosis. Finally, transgenic mice overexpressing SPACIA1/SAAL1 exhibited early onset and rapid progression of CIA.Conclusion. These results suggest that SPACIA1/ SAAL1 is necessary for abnormal proliferation of synovial fibroblasts and its overexpression is associated with the progression of synovitis in mice and humans. Thus, therapy targeting SPACIA1/SAAL1 might have potential as an inhibitor of synovial proliferation in RA and/or OA.Synovitis is a common characteristic of rheumatoid arthritis (RA) and knee osteoarthritis (OA). The major pathologic features of synovitis are hyperplasia of the synovial lining, inflammatory cell infiltration, and

The results suggest that EP2 signalling has 'anti-catabolic' effects in osteoarthritis chondrocytes.

The purpose of this study was to investigate the role of platelet-activating factor (PAF) and PAF acetylhydrolase (AH) in conjunctiva. The influence of PAF on conjunctival vascular permeability and the presence of PAF or its metabolites in tears from guinea pigs with allergic conjunctivitis were investigated. We instilled PAF to the eyes of guinea pigs and evaluated vascular permeability. Tear samples were collected from passively sensitized guinea pigs, and the concentration of PAF and its metabolites determined by liquid chromatography-tandem mass spectrometry. Exogenous PAF degradation in tear samples was evaluated with or without diisopropyl fluorophosphate (DFP). Topically applied PAF increased vascular permeability in conjunctiva. In the tear samples from guinea pigs with allergic conjunctivitis, PAF could not be detected. However, 40 +/- 6 ng/ml of lyso-platelet activating factor (lyso-PAF) and 230 +/- 50 ng/ml of 1-alkyl-2-acyl-sn-glycero-3-phosphocholine were detected at 10 min after challenge. Exogenous PAF was rapidly degraded in the tear samples from guinea pigs with allergic conjunctivitis, but not from normal guinea pigs. This PAF degradation was inhibited by DFP. These results suggest that PAF in the tear fluid is quickly hydrolyzed to lyso-PAF by PAF AH, which may be released or activated in allergic conjunctivitis.

No abstract

This study was performed to elucidate the molecular function of the synoviocyte proliferation-associated in collagen-induced arthritis (CIA) 1/serum amyloid A-like 1 (SPACIA1/SAAL1) in mice CIA, an animal model of rheumatoid arthritis (RA), and human RA-synovial fibroblasts (RASFs). SPACIA1/SAAL1-deficient mice were generated and used to create mouse models of CIA in mild or severe disease conditions. Cell cycle-related genes, whose expression levels were affected by SPACIA1/SAAL1 small interfering RNA (siRNA), were screened. Transcriptional and post-transcriptional effects of SPACIA1/SAAL1 siRNA on cyclin-dependent kinase (cdk) 6 gene expression were investigated in human RASFs. SPACIA1/SAAL1-deficient mice showed later onset and slower progression of CIA than wild-type mice in severe disease conditions, but not in mild conditions. Expression levels of cdk6, but not cdk4, which are D-type cyclin partners, were downregulated by SPACIA1/SAAL1 siRNA at the post-transcriptional level. The exacerbation of CIA depends on SPACIA1/SAAL1 expression, although CIA also progresses slowly in the absence of SPACIA1/SAAL1. The CDK6, expression of which is up-regulated by the SPACIA1/SAAL1 expression, might be a critical factor in the exacerbation of CIA.

After the breakthrough in the treatment of rheumatoid arthritis and numerous related disorders with biological therapies targeting TNFa at the Kennedy Institute in London Millions of patients have tremendously benefitted. However, we cannot cure these diseases yet and have to search for additional therapeutic targets. Since it was shown that synovial fibroblasts (SF) are not only effector cells responding to inflammatory stimuli, but appear endogenously activated and potentially involved into spreading the disease [1], we searched for the epigenetic modifications leading to the activated phenotype of these cells. Epigenetics in its scientific definition "is the study of all heritable and potentially reversible changes in genome function that do not alter the nucleotide sequence within the DNA", but might be considered in simpler terms as the regulation of gene expression. Epigenetic modifications include: Acetylation, Methylation, Phosphorylation, Sumoylation, miRs or microRNAs. Our laboratory is studying these processes and we have found that RASF reside in a hyperacetylated synovial tissue and appear hypomethylated [2]. Hypomethylation leads to the activated phenotype of RASF which is characterized by the production of matrix-degrading enzymes and of potent chemokines induced by Toll-like receptor signalling. Current strategies are designed to methylate these cells to deactivate and "normalise" them again. miRs are about 20 nucleotide long smallRNAs acting to destroy specific mRNA. In the race to identify specific miRs as novel targets we have identified for example, that interleukin-6 modulates the expression of the Bone Morphogenic Protein Receptor Type II through a novel STAT3microRNA cluster 17/92 pathway, which helps to explain the loss of the BMPR2 in the vascular cells in pulmonary hypertension [3]. Moreover, miR-203 is regulating the production of IL-6 [4]. Most interestingly, epigenetic therapy is also on the horizon [5]. References 1. Lefèvre S, et al: Synovial fibroblasts spread rheumatoid arthritis to unaffected joints.