Update on cytokines in rheumatoid arthritis

Th17 development and autoimmune arthritis in the absence of reactive oxygen species

Dendritic cells (DC) express a functional NADPH oxidase and produce reactive oxygen species (ROS) upon interaction with microbes and T cells. Exposure to ROS leads to DC activation and maturation, as evidenced by phenotypic and functional changes. We have evaluated how endogenous ROS production affects the cytokine secretion pattern and T cell-activating capacity of bone marrow-derived murine DC. DC treated with ROS scavengers, as well as DC from mice that lack a functional NADPH oxidase (and thereby inherently deficient in ROS production) produced significantly increased levels of IL-1beta, IL-6, TNF-alpha and TGF-beta in response to microbial activation. DC deficient in ROS production induced high levels of IFN-gamma and IL-17 in responding T cells after Ag-specific or superantigen-induced activation. Finally, we show that ROS deficiency affected the induction of a T cell-dependent inflammatory condition, collagen-induced arthritis (CIA). C57BL/6 mice that lack a functional NADPH oxidase developed a severe and erosive CD4-dependent CIA, whereas the majority of the congenic wild-type animals remained healthy. These data suggest that ROS act as immunomodulators in DC-driven T cell activation and perhaps also in T cell-dependent immunopathology.

Molecular genetic studies of gene identification for osteoporosis

This review comprehensively summarizes the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of September 2007. It is intended to constitute a sequential update of our previously published reviews covering the available data up to the end of 2004. Evidence from candidate gene-association studies, genome-wide linkage and association studies, as well as functional genomic studies (including gene-expression microarray and proteomics) on osteogenesis and osteoporosis, are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. The major results of all studies are tabulated for comparison and ease of reference. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.

Role of Txk, a member of the Tec family of tyrosine kinases, in immune-inflammatory diseases

Txk/Rlk, a member of the Tec family of tyrosine kinases, is an important signaling mediator. We previously reported that human Txk is expressed in Th1/Th0 cells, and Txk translocates from cytoplasm into nuclei upon activation. Txk regulates specifically interferon-gamma gene transcription. Txk, poly(ADP-ribose) polymerase 1, and elongation factor 1alpha make a complex to bind to interferon-gamma gene promoter region-53/-39 (Txk responsive element) to exert positive effects on transcription as a Th1 cell-associated transcription factor. Txk expression is enhanced in rheumatoid arthritis and Behçet's disease, where Th1 dominant immunity occurs. In bronchial asthma and atopic dermatitis, typical Th2 diseases, Txk expression is reduced. Modulation of Txk expression by gene transfer or similar modality may lead to the correction of aberrant immunity and, consequently, disease treatment.

Mechanisms of Disease: angiogenesis in inflammatory diseases

Angiogenesis, the development of new vessels, is an important process in health and disease. The perpetuation of neovascularization in inflammatory diseases, such as rheumatoid arthritis, spondyloarthropathies and some systemic autoimmune diseases, might facilitate the ingress of inflammatory cells into the synovium and, therefore, stimulate pannus formation. Disorders associated with perpetuated neovascularization are considered to be angiogenic inflammatory diseases. Several angiogenic mediators, including growth factors, cytokines, matrix metalloproteinases, matrix macromolecules, cell adhesion receptors, chemokines and chemokine receptors, have been implicated in the process of capillary formation. There is a regulatory network in inflamed tissues that is involved in the upregulation or downregulation of angiogenesis. Endogenous angiostatic factors downregulate neovascularization and might act as angiostatic agents. Furthermore, angiogenesis might be targeted by several specific approaches that could be therapeutically used to control inflammatory diseases.

Cells of the synovium in rheumatoid arthritis. Macrophages

The multitude and abundance of macrophage-derived mediators in rheumatoid arthritis and their paracrine/autocrine effects identify macrophages as local and systemic amplifiers of disease. Although uncovering the etiology of rheumatoid arthritis remains the ultimate means to silence the pathogenetic process, efforts in understanding how activated macrophages influence disease have led to optimization strategies to selectively target macrophages by agents tailored to specific features of macrophage activation. This approach has two advantages: (a) striking the cell population that mediates/amplifies most of the irreversible tissue destruction and (b) sparing other cells that have no (or only marginal) effects on joint damage.