Unknown,Transcriptomics,Genomics,Proteomics

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Control vs. PGISp spine samples

ABSTRACT: OBJECTIVES: Ankylosing spondylitis (AS) is unique in its pathology where inflammation commences at the entheses before progressing to an osteoproliferative phenotype generating excessive bone formation that can result in joint fusion. The underlying mechanisms of this progression are poorly understood. Using the proteoglycan-induced spondylitis mouse (PGISp) model which displays spondylitis and eventual joint fusion following an initial inflammatory stimulus, we have characterised the structural and molecular changes that underlie disease progression METHODS: PGISp mice were characterised 12 weeks after initiation of inflammation using expression profiling. RESULTS: Microarray profiling showed genes involved in inflammation and immune-regulation were altered. Further, a number of genes specifically involved in bone regulation including other members of the Wnt pathway were also dysregulated. CONCLUSION: This study implicates the Wnt pathway as a likely mediator of the mechanism by which inflammation induces bony ankylosis in spondyloarthritis, raising the potential that therapies targeting this pathway may be effective in preventing this process. 4 unaffected spines vs. 4 spines from PGISp-affected mice

ORGANISM(S): Mus musculus

SUBMITTER: Gethin Thomas

PROVIDER: E-GEOD-41039 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:We have compared synovial biopsies from ankylosing spondylitis and undifferentiated spondylitis patients with healthy controls and osteoarthritis patients Objective: In spondylarthropies, whole-genome gene expression profiling studies have been limited to peripheral blood to date. By undertaking a study in knee synovial biopsies from spondylarthropy (SpA) and ankylosing spondylitis (AS) patients we aimed to identified joint-specific candidate genes and pathways. These pathways may mediate systemic inflammation driven joint damaging processes and more specifically, the osteoproliferation that is characteristic of these conditions. Methods: RNA was extracted from six seronegative SpA, two AS, three osteoarthritis (OA) and four normal control knee synovial biopsies. Whole genome expression profiling was undertaken using the Illumina DASL system, which assays 24000 cDNA probes. Differentially expressed candidate genes were then validated using quantitative PCR and immunohistochemistry. Results: 416 differentially expressed genes were identified that clearly delineated between AS/SpA and control groups. Pathway analysis showed altered gene-expression in oxidoreductase activity, osteoblast activity, B-cell associated, matrix catabolic, and metabolic pathways. The inflammatory mediator, MMP3, was strongly upregulated in AS/SpA samples and the Wnt pathway inhibitors DKK3 and Kremen1 were downregulated. Conclusion: Pathways mediating both systemic inflammation as well as local tissue changes were identified. This suggests initial systemic inflammation in spondylarthropies transfers to and persists in the local joint environment, subsequently mediating changes in genes directly involved in the destructive tissue remodelling. Fifteen knee synovial biopsy tissue samples consisting of six seronegative spondyloarthropy (SpA), two ankylosing spondylitis (AS), three osteoarthritis (OA) and four normal control biopsies were obtained from the Synovial Tissue Bank at the Repatriation General Hospital in Adelaide, South Australia with the appropriate ethical approval (Supplementary Table 1). All patients provided informed written consent.

Project description:The function of human circulating proangiogenic cells (PACs) has been described extensively. However, little focus has been placed on understanding how these cells differ in their functions in the presence of microenvironments mimicking vascular inflammation. We hypothesized that exposure to proinflammatory cytokines or the oxLDL, an autoantigen abundant in advanced atherosclerotic plaques, converts PACs into immune-modulating/proinflammatory cells. Hence, we examined the effect of oxLDL and inflammatory stimuli on their phenotype by use of a functional genomics model based on secretome and whole genome transcriptome profiling. PACs obtained from culturing a PBMC fraction in angiogenic medium were primed with DC differentiation cytokines for 3 days and then exposed to proinflammatory cytokines or oxLDL for 2 days. Under these conditions, PACs converted into APCs (APCcy and APCox, respectively), expressed maturation markers CD80 and CD83, and showed an up-regulation of CD86. APCcy and APCox induced a robust T cell BrdU incorporation. Despite a similar ability to induce lymphocyte proliferation, APCcy and APCox differed for the secretory pathway and mRNA expression. Analysis of the differentially expressed genes identified 4 gene "clusters", showing reciprocal modulation in APCcy vs. APCox justifying, according to functional genomics analyses, a different putative function of the cells in antigen processing. Together, these data show that treatment with inflammatory cytokines or oxLDL converts human PAC phenotype and function into that of APCs with similar lymphocyte-activating ability but distinct maturation degree and paracrine functions. PBMC-derived PACs were committed with GM-CSF and IL-4 to a dendritic phenotype, and then exposed to proinflammatory cytokines (IL-1β and TNF-α) or to the oxidized form of LDL (oxLDL). Functional assays and whole genome gene expression profiling were performed both on PACs (n=6) and or resulting cytokine- (APCcy, n=6) and oxLDL-induced APCs (APCox, n=6). RNA was reverse transcribed, labeled, and linearly amplified, and then hybridized to HumanHT-12 v.4 Expression BeadChip microarrays. To estimate technical variability, ≈20% of the samples (n=4) were hybridized in duplicate.

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Control vs. PGISp spine samples

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