Abstracts Biennial Meeting of the American Society for Matrix Biology 1 Biglycan as a ligand to TLR-4 and -2 aggravates inflammation Liliana Schaefer Department of Pharmacology, University of Frankfurt, 60590, Germany During inflammation the ECM turns into a dynamic microenvironment, generating a host of regulatory molecules, which interact with resident and infiltrating cells. There is growing evidence that ECM molecules may convey proinflammatory signals. Recently, we showed that biglycan, a small leucine-rich proteoglycan, acts as an endogenous ligand of the innate immunity receptors Toll-like receptor-4 (TLR4) and -2 (TLR2) in macro- phages, leading to rapid activation of p38, Erk and NF-κB, thereby stimulating the expression of TNF-α and macrophage inflammatory protein-2 (MIP-2). In agreement with these findings, the stimulatory effects of biglycan are significantly reduced in TLR4-mutant (TLR4-M), TLR2-/- and myeloid differentiation factor 88-/- (MyD88-/-) macrophages and com- pletely abolished in TLR2-/-/TLR4-M macrophages. Biglycan-null mice have a considerable survival benefit in LPS- or zymosan-induced sepsis due to lower levels of circulating TNF-α and reduced infiltration of mononuclear cells in the lung, causing less end-organ damage. Importantly, macrophages, normally not expressing biglycan, start to synthesize biglycan when stimulated by proinflammatory factors. Thus, biglycan, upon release from the ECM or from macrophages, is capable to boost inflammatory reactions by signaling through TLR4 and TLR2, thereby enhancing the synthesis of TNF-α and MIP-2. This novel concept, that under certain conditions matrix components may act as ligands to distinct immunity receptors and thereby regulate inflammatory reactions, might be of considerable significance for the pathogenesis of and the therapeutic approach to inflammatory disorders. doi:10.1016/j.matbio.2008.09.216 2 Lumican regulates integrin-mediated migration of neutrophils Seakwoo Lee a , Shukti Chakravarti a,b,c a Department of Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States b Department of Ophthalmology, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States c Department of Cell Biology, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States Purpose Lumican (Lum) is a leucine-rich repeat keratan sulfate proteoglycan of the extracellular matrix (ECM). We have shown that 1) lumican regulates toll- like receptor 4-mediated innate immune response and 2) influx of polymorphonuclear neutrophils (PMN) to the injured cornea is reduced and healing delayed in lumican-deficient mice. We investigated the role of lumican–integrin interactions in promoting PMN migration. Methods Lum +/+ and Lum -/- peritoneal lavage PMN were tested for migration towards the pro-inflammatory chemokine CXCL1/KC (bottom chamber) in transwells, with or without recombinant lumican and function-blocking antibodies against specific integrins (upper chamber). Lumican and integrin interactions were investigated by co-immunoprecipitation and immunofluorescent confocal microscopy. Cell surface integrin contents were compared by flow cytometry. Results and discussion There was no difference between lumican-deficient and wild type PMN in surface integrins. However, in transwell chemotaxis assays Lum -/- PMN showed reduced migration that could be increased to wild type levels by the addition of recombinant lumican. Furthermore, this lumican-aided PMN migration could be inhibited by anti-integrin antibodies. Confocal micro- scopy indicated lumican and integrin proximity on PMN cell surfaces. The co- immunoprecipitation experiments indicated prominent interaction between lumican and specific integrins. Taken together the results suggest the presence of lumican on the surface of PMN where it interacts with integrins and promotes chemotactic migration. doi:10.1016/j.matbio.2008.09.217 3 Role of gamma1-laminins in renal collecting ducts Dong-Hua Yang a , Zulin Chen b , Roy Zent c , Sidney Strickland b , Carlton Bates d , Karen K. McKee a , Peter D. Yurchenco a a Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States b Rockefeller University, New York, NY 10021, United States c Vanderbilt University, Nashville, TN 37232, United States d Ohio State University, Columbus, OH 43210, United States The laminin-gamma1 gene was deleted in the ureteric bud (UB). At birth, laminin-deficient pups exhibited bilateral renal-ureteric agenesis or renal hypoplasia, the latter followed by emergence of diabetes insipidus and hydronephrosis. Laminin-deficient UBs were absent or under-branched within the metanephric mesenchyme at E10.5 to 11.5. By E12.5 to E13.5 there was reduced epithelial/mesenchymal proliferation, delayed mesench- ymal condensation, and flattened and disorganized epithelia. UB basement membranes were initially severely attenuated to absent with marked reductions of laminin-gamma1, nidogen-1, collagen-IV and heparan sulfate (HS) proteoglycans. FGF-2, a HS-binding growth factor normally located within basement membranes, was largely absent. By E14.5, corresponding to the delayed appearance of renal vesicles and their basement membranes within the defective kidneys, increased deposition of the laminin gamma3 and gamma1 subunits, collagen-IV, nidogen and proteoglycans was detected. Matrix Biology 27 (2008) S9–S61 Contents lists available at ScienceDirect Matrix Biology journal homepage: www.elsevier.com/locate/matbio