Abstract

The interaction between the immune and skeletal systems has long been acknowledged, but molecular mechanisms linking the two systems have not been demonstrated until recently. Investigation into autoimmune arthritis as well as the various bone phenotypes found in mice deficient in immunomodulatory molecules has highlighted the importance of the dynamic interplay between the two systems and brought about a rapid evolution of the field of osteoimmunology [1]. In bone loss in autoimmune arthritis, IL-17-producing helper T (TH17) cells play a major role by inducing RANKL [2]. Maintenance and mobilization of hematopoietic cells are regulated by bone cells. In addition to cellular interactions via cytokines, the immune and skeletal systems share various molecules, including transcription factors, signaling molecules and membrane receptors. RANKL stimulates osteoclastogenesis through NFATc1 in cooperation with immunoglobulin-like receptors. Here I will discuss emerging topics in osteoimmunology including the mechanisms underlying bone cell communication: osteocyte RANKL [3] and inhibition of bone formation by osteoclast Sema4D [4].

Highlights

  • Acute isolated neurological syndromes, such as optic neuropathy or transverse myelopathy, may cause diagnostic problems since they can be the first presentations in a number of demyelinating disorders including multiple sclerosis (MS) and collagen diseases

  • tumor necrosis factor (TNF) therapy and demyelinating event: A report indicates that adverse events such as the demyelinating lesion in the brain, optic neuritis, and neuropathy occurred after treatment with anti-TNF alpha therapy in collagen disease, and TNF antagonizing therapy showed worsening in a clinical trial with MS

  • Believing on the similarities of normal joints in humans and monkeys, we have employed a model of collagen-induced arthritis in Macaca fascicularis in an attempt to evaluate the histological alterations caused by such condition in the extracellular matrix of the articular cartilage

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Summary

Introduction

Acute isolated neurological syndromes, such as optic neuropathy or transverse myelopathy, may cause diagnostic problems since they can be the first presentations in a number of demyelinating disorders including multiple sclerosis (MS) and collagen diseases. Acute Serum Amyloid A (A-SAA) is an acute phase protein strongly expressed in rheumatoid arthritis (RA) synovial tissue (ST) critically involved in regulating cell migration and angiogenesis These processes are dependent on downstream interactions between extracellular matrix and cytoskeletal components. Conclusions: These results indicate that Egr-1 contributes to IL-1mediated down-regulation of PPARg expression in OA chondrocytes and suggest that this pathway could be a potential target for pharmacologic intervention in the treatment of OA and possibly other arthritic diseases. Immune cell-derived microparticles (MPs) are present at increased amounts in synovial fluid of rheumatoid arthritis (RA) patients [1] and can activate disease-relevant signalling pathways in RA synovial fibroblasts (SF) [2,3].

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