engleski

Transcriptional profiling of synovial myeloid cells to determine molecular mediators of bone resorption in antigen–induced arthritis.

Introduction: Rheumatoid arthritis (RA) is a chronic systemic autoimmune arthropathy, which often causes permanent joint damage due to local cartilage and bone resorption. Despite progress toward achieving disease remission current therapeutics are still unable to reverse local bone resorption. Using antigen-induced arthritis (AIA), a murine model of RA, we found that Fas gene deletion (Fas-/-) results in an ameliorated form of arthritis, characterized by abscence of subchondral bone destruction, and marked by a lower frequency of myeloid (CD11b+Gr1+) cells in the synovial compartment. Aim: By analyzing differentially expressed genes in sorted myeloid populations from wild-type (WT) and Fas -/- mice with AIA we aim to identify myeloid-specific molecular mediators driving bone-resorption in AIA. Materials and Methods: AIA was induced by intra- articular injection of methylated bovine serum albumin to previously immunized WT and Fas -/- mice. µCT was used to quantitatively assess subchondral bone volume. Synovial tissue was digested by collagenase and released cells were labeled with anti-mouse CD45-FITC, CD11b-PE, Gr1- PECy7, B220/CD3/NK1.1/CD31/TER119- APC, and CD51- APCeF780. CD11b+Gr-1+ population was sorted using BD FACSAria II, and RNA isolated from sorted cells was hybridized to Affymetrix ST 2.0 arrays. Analysis of gene expression data was preformed using Bioconductor and ToppGene. qRT-PCR was used to confirm expression differences in sorted populations and total joint tissue extracts. Results: Synovial CD11b+Gr1+ population is transcriptionally similar in Fas -/- and WT mice with AIA. Hierarchical clustering based on gene expression data separated two groups of synovial myeloid cells. Each cell group was predominantly represented by either Fas -/- or WT samples, where WT-dominant cluster revealed up-regulation of genes related to cell cycle progression and mitotic activity. Differential gene expression analysis revealed down-regulated Mid1 and Erdr1 genes in Fas -/- synovial myeloid cells. According to PCR validation performed on bulk joint tissue, Mid1 is clearly up-regulated in AIA in comparison to non-immunized WT mice and is upregulated only after arthritis induction in immunized mice. Conclusion: Resorptive AIA is characterized by increased frequency of synovial myeloid cells, which express more Mid1 and Erdr1, and less Thbs1 gene, in comparison to non-resorptive arthritis in Fas –/– mice. The inflammatory response in resorptive AIA is marked by a higher myeloid proliferation potential. Mid1 gene is a potential novel mediator for inflammation-mediated joint destruction in arthritis since it is clearly upregulated by induction of arthritis. Increased expression of Mid1 has already been reported in an allergic airway inflammation, and it is dependent on death receptor TRAIL

myeloid cells ; Fas ; arthritis ; transcriptome

nije evidentirano