During MH closure, the ILM functioned as a scaffold for the proliferation and migration of Müller cells, and may promote Müller cell activation. Neurotrophic factors and bFGF produced by activated Müller cells and present on the surface of the ILM may contribute to MH closure.

Objective. To compare induction of the aggrecanases (ADAMTS-1, ADAMTS-4, ADAMTS-5, ADAMTS-8, ADAMTS-9, and ADAMTS-15) by interleukin-1␤ (IL-1␤) and tumor necrosis factor ␣ (TNF␣) in chondrocyte-like OUMS-27 cells and human chondrocytes, and to determine the mechanism of induction of the most responsive aggrecanase gene.Methods. OUMS-27 cells were stimulated for different periods of time and with various concentrations of IL-1␤ and/or TNF␣. Human chondrocytes obtained from osteoarthritic joints and human skin fibroblasts were also stimulated with IL-1␤ and/or TNF␣. Total RNA was extracted, reverse transcribed, and analyzed by quantitative real-time polymerase chain reaction and Northern blotting. ADAMTS-9 protein was examined by Western blotting, and the role of the MAPK signaling pathway for ADAMTS9 induction in IL-1␤-stimulated OUMS-27 cells was investigated.Results. IL-1␤ increased messenger RNA (mRNA) levels of ADAMTS4, ADAMTS5, and ADAMTS9 but not ADAMTS1 and ADAMTS8. The fold increase for ADAMTS9 mRNA was greater than that for mRNA of the other aggrecanase genes. The increase of ADAMTS9 mRNA by IL-1␤ stimulation was greater in chondrocytes than in fibroblasts. The combination of IL-1␤ and TNF␣ had a synergistic effect, resulting in a considerable elevation in the level of ADAMTS9 mRNA. ADAMTS-9 protein was also induced in IL-1␤-stimulated OUMS-27 cells. The MAPK inhibitors SB203580 and PD98059 decreased ADAMTS9 upregulation in OUMS-27 cells.Conclusion. ADAMTS9 is an IL-1␤-and TNF␣-inducible gene that appears to be more responsive to these proinflammatory cytokines than are other aggrecanase genes. Furthermore, these cytokines had a synergistic effect on ADAMTS9. Together with the known ability of ADAMTS-9 to proteolytically degrade aggrecan and its potential to cleave other cartilage molecules, the data suggest that ADAMTS-9 may have a pathologic role in arthritis.

ABSTRACT. Type XV and type XVIII collagens are classified as part of multiplexin collagen superfamily and their C-terminal parts, endostatin and restin, respectively, have been shown to be anti-angiogenic in vivo and in vitro. The α1(XV) and α1(XVIII) collagen chains are reported to be localized mainly in the basement membrane zone, but their distributions in blood vessels and nonvascular tissues have yet to be thoroughly clarified. In the present study, we raised monoclonal antibodies against synthetic peptides of human α1(XV) and α1(XVIII) chains and used them for extensive investigation of the distribution of these chains. We came to the conclusion that nonvascular BMs contain mainly one of two types: subepithelial basement membranes that contained type XVIII in general, or skeletal and cardiac muscles that harbored mainly type XV. But basement membranes surrounding smooth muscle cells in vascular tissues contained one or both of them, depending on their locations. Interestingly, continuous capillaries contained both type XV and type XVIII collagens in their basement membranes; however, fenestrated or specialized capillaries such as glomeruli, liver sinusoids, lung alveoli, and splenic sinusoids expressed only type XVIII in their basement membranes, lacking type XV. This observation could imply that different functions of basement membranes in various tissues and organs use different mechanisms for the endogenous control of angiogenesis.Key words: basement membrane/type XV collagen/type XVIII collagen/capillary/smooth muscle cellThe collagen family, which consists of 20 collagen types and 38 collagen α-chains (Myllyharju and Kivirikko, 2001), are known to be major components of connective tissues and/or basement membranes (BMs). They not only serve as scaffolds for tissues and organs but also are involved in various biological events such as development, morphogenesis, inflammation, tissue repair, and filtration, as well as in various pathological processes (Olsen and Ninomiya, 1999).The BM, lying beneath epithelia and around muscle, adipose, and Schwann cells, and made visible by the periodic acid-Schiff reaction under light microscopic observation, is composed mainly of type IV collagen, laminin, nidogen, and heparan sulfate proteoglycan. Multiple components of these materials have been reported to comprise BMs in a tissue-specific fashion. For instance, six α(IV) collagen chains have been identified and at least three molecular forms distribute in various BMs‫ (ޓ‬Hudson et al., 1993;Sado et al., 1998). One form, α3/α4/α5, is specifically present in BMs where it functions as a permeability selective barrier such as in the BMs in glomerulus in kidney and alveolus in lung Saito et al., 2000). Such findings suggest the possibility that the composition of collagen IV molecules in various tissues corresponds with specific biological *To whom correspondence should be addressed: Ichiro Naito, Ph. D., Division of Ultrastructural Biology, Shigei Medical Research Institute, 2117 Yamada, Okayama 701-0202, Japan.Tel: +...

We investigated the differential distribution of basement membrane type IV collagen a chains in the mouse brain by immunohistochemistry using a chain-specific monoclonal antibodies. Subendothelial basement membranes were found to contain alpha1 and alpha2 chains. Basement membranes surrounding smooth muscle cells on blood vascular walls were immunoreactive for alpha1 and alpha2 chains but not for alpha5 and alpha6 chains. Interestingly, the pia mater contained a thin basement membrane which was positive for alpha1, alpha2, alpha5, and alpha6 chains, suggesting that glia limitans superficialis coheres basement membranes containing [alpha1(IV)]2alpha2(IV) and [alpha5(IV)]2alpha6(IV) molecules. In contrast, capillaries always possessed thin basement membranes of [alpha1(IV)]2alpha2(IV) molecules. Cerebrospinal fluid is produced through filtration of blood at the choroid plexus, where two distinct basement membranes were detected by anti-al and anti-alpha2 antibodies. The subendothelial basement membrane appeared to consist of [alpha1(IV)]2alpha2(IV) molecules, whereas the subependymal basement membrane in the choroid plexus was strongly positive for alpha3, alpha4, and alpha5 chains, indicating that the filtering unit was composed of alpha3(IV)alpha4(IV)alpha5(IV) molecules. That the specific localizations of these molecules are shared by renal glomeruli and the choroid plexus leads us to hypothesize that the supramolecular network containing alpha3(IV) alpha4(IV)alpha5(IV) molecules may function as a permeability selective barrier.

We report the molecular cloning of a new member of the transmembrane-type immunoglobulin superfamily and designate the encoded protein as limitrin, since it localized selectively to glia limitans in mouse brain. Limitrin cDNA was obtained using a subtractive hybridization procedure designed to identify molecules responsible for blood-brain barrier function. Western blots using a limitrin-specific antibody demonstrated that the gene product is expressed significantly in mouse brain and primary murine astrocytes and is distributed in the plasma membrane. Immunohistochemical studies using confocal and electron microscopy clearly demonstrated highly polarized localization in astroglial endfeet in the perivascular region and under the pia mater in vivo. Limitrin is expressed in the spinal cord and in many areas of the brain, but not in the median eminence or subfornical organ (the circumventricular organs), where the blood-brain barrier is lacking. Disruption of the blood-brain barrier by cold injury resulted in a drastic reduction in limitrin expression. Furthermore, during retrieval from cold injury, the increased expression of limitrin in perivascular endfeet correlated with the recovery of angiogenesis in capillaries within the lesion margins. Our results suggest that limitrin is physically and functionally associated with the blood-brain barrier, implying that this protein may be useful as a diagnostic tool of barrier integrity.