Browsing by Subject "Synoviocyte"

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    Human articular chondrocytes, synoviocytes and synovial microvessels express aquaporin water channels; upregulation of AQP1 in rheumatoid arthritis
    (Murcia : F. Hernández, 2004) Trujillo, E.; Gonzalez, T.; Marín, R.; Martín-Vasallo, P.; Marples, D.; Mobasheri, A.
    Recent studies have shown that aquaporin water channels are expressed in human Meckel’s cartilage. The aim of the present investigation was to determine if human articular chondrocytes and synoviocytes express aquaporin 1 (AQP1) water channels and to establish if there are any alterations in AQP1 expression in osteoarticular disorders such as osteoarthritis (OA) and rheumatoid arthritis (RA). Immunohistochemistry was employed semiquantitatively to compare the expression of AQP1 in human chondrocytes derived from normal, OA and RA joints. PCR, cloning and sequencing confirmed the presence of AQP1 transcripts in chondrocytes. Normal human tissue microarrays including samples of kidney, choroid plexus and pancreas were used as positive controls for AQP1 expression. In most tissues AQP1 was expressed along endothelial barriers. In the kidney AQP1 was present in the glomerular capillary endothelium, proximal tubule and descending thin limbs. AQP1 was also localized to pancreatic ducts and acini and the apical membrane domain of the choroid plexus. Immunohistochemistry showed that AQP1 is expressed in synovial micro-vessels, synoviocytes and predominantly in chondrocytes located in the deep zone of articular cartilage. Image analysis of normal, OA and RA cartilage suggested that AQP1 may be upregulated in RA. This is the first report of AQP1 mRNA and protein expression in articular chondrocytes and synoviocytes. These findings suggest a potential role for AQP1 and possibly other members of the AQP gene family in the movement of extracellular matrix and metabolic water across the membranes of chondrocytes and synoviocytes for the purposes of chondrocyte volume regulation and synovial homeostasis.
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    Primary cilia in fibroblast-like type B synoviocytes lie within a cilium pit, a site of endocytosis
    (Murcia : F. Hernández, 2010) Rattner, Jerome B.; Sciore, Paul; Ou, Young; van der Hoorn, Frans A.; Lo, I.K.Y.
    The synovium is a thin connective tissue that lines the joint space of free moving articulations. In this report, the expression, structure, and composition of non-motile (primary) cilia in fibroblast-like synoviocytes (FLS) that populate the synovium have been studied. Primary cilia are non-motile, microtubule-based organelles that have been found in a variety of vertebrate cell types. We document that primary cilia are expressed in normal human synovium FLS, cultured human FLS, and FLS cells present in human synovial fluid, and that the cellular region occupied by the primary cilium shows a similar and highly defined architecture within these FLS. This architecture includes the presence of a unique structure that surrounds the lower portion of the cilium shaft. This structure, given the term cilium-pit, includes a space, the pit reservoir. Actin filament bundles surround the cilium-pit, and when these bundles are removed experimentally the volume of the cilium-pit and its continuity with the extracellular environment changes. Finally, this study documents that the cilium-pit is a site of endocytosis and is also the site for the localization of receptors (TNF receptors TNFR1 and TNFR2) associated with synoviocyte function. Taken together, the results of the present study suggest that the FLS cilium-pit functions to regulate the exposure of the primary cilium, both spatially and temporally to extracellular molecules and to couple primary cilium based signaling pathways with those linked to endocytosis.