It is widely believed that rolling lymphocytes require successive chemokine-induced signaling for lymphocyte function-associated antigen 1 (LFA-1) to achieve a threshold avidity that will mediate lymphocyte arrest. Using an in vivo model of lymphocyte arrest, we show here that LFA-1-mediated arrest of lymphocytes rolling on high endothelial venules bearing LFA-1 ligands and chemokines was abrupt. In vitro flow chamber models showed that endothelium-presented but not soluble chemokines triggered instantaneous extension of bent LFA-1 in the absence of LFA-1 ligand engagement. To support lymphocyte adhesion, this extended LFA-1 conformation required immediate activation by its ligand, intercellular adhesion molecule 1. These data show that chemokine-triggered lymphocyte adhesiveness involves a previously unrecognized extension step that primes LFA-1 for ligand binding and firm adhesion.

In contrast to the other anti-TNFalpha agents tested, certolizumab pegol did not mediate increased levels of apoptosis in any of the in vitro assays used, suggesting that these mechanisms are not essential for the efficacy of anti-TNFalpha agents in CD. As certolizumab pegol, infliximab, and adalimumab, but not etanercept, almost completely inhibited LPS-induced IL-1beta release from monocytes, inhibition of cytokine production may be important for efficacy of anti-TNFalpha agents in CD.

SummaryA skin-associated population of memory T lymphocytes, defined by expression of the cutaneous lymphocyte antigen (CLA), binds selectively and avidly to the vascular lectin endothelial cellleukocyte adhesion molecule 1 (ELAM-1), an interaction that may be involved in targeting of CLA + T cells to cutaneous sites of chronic inflammation. Here we present evidence that CLA itself is the (or a) lymphocyte homing receptor for ELAM-1. Antigen isolated with anti-CLA monoclonal antibody HECA-452 from human tonsillar lysates avidly binds ELAM-1 transfected mouse cells. Anti-CLA antibody blocks T lymphocyte binding to ELAM-1 transfectants. HECA-452 and ELAM-1 binding to lymphocytes or to isolated tonsillar HECA-452 antigen is abrogated by neuraminidase treatment implying a prominent role for sialic acid in CLA structure and function. The dominant form of CLA on T cells is immunologically distinct from the major neutrophil ELAM-1 ligand, the sialyl Lewis x (sLe ~) antigen (NeuAcc~2-3GalB1-4[Fuccxl-3]GlcNAc), which is absent, weakly expressed, or masked on T ceUs. However, neuraminidase treatment of CLA + T cells, but not of CLA-T cells, reveals Lewis x (CD15) structures. In combination with the known requirement for terminal NeuAcoe2-3Gal and fucose residues attached to N-acetylglucosamine for ELAM-1 and HECA-452 binding, this finding suggests that CLA may comprise an additionally sialylated or otherwise modified form of sLe x. The identification of a lymphocyte homing receptor for skin may permit novel approaches to the diagnosis and therapy of cutaneous and inflammatory disorders.

Actinobacillus actinomycetemcomitans leukotoxin and

The development of bone-rebuilding anabolic agents for treating bone-related conditions has been a long-standing goal. Genetic studies in humans and mice have shown that the secreted protein sclerostin is a key negative regulator of bone formation. More recently, administration of sclerostin-neutralizing monoclonal antibodies in rodent studies has shown that pharmacologic inhibition of sclerostin results in increased bone formation, bone mass, and bone strength. To explore the effects of sclerostin inhibition in primates, we administered a humanized sclerostin-neutralizing monoclonal antibody (Scl-AbIV) to gonad-intact female cynomolgus monkeys. Two once-monthly subcutaneous injections of Scl-AbIV were administered at three dose levels (3, 10, and 30 mg/kg), with study termination at 2 months. Scl-AbIV treatment had clear anabolic effects, with marked dose-dependent increases in bone formation on trabecular, periosteal, endocortical, and intracortical surfaces. Bone densitometry showed that the increases in bone formation with Scl-AbIV treatment resulted in significant increases in bone mineral content (BMC) and/or bone mineral density (BMD) at several skeletal sites (ie, femoral neck, radial metaphysis, and tibial metaphysis). These increases, expressed as percent changes from baseline were 11 to 29 percentage points higher than those found in the vehicle-treated group. Additionally, significant increases in trabecular thickness and bone strength were found at the lumbar vertebrae in the highest-dose group. Taken together, the marked bone-building effects achieved in this short-term monkey study suggest that sclerostin inhibition represents a promising new therapeutic approach for medical conditions where increases in bone formation might be desirable, such as in fracture healing and osteoporosis. ß

Integrins ␣2␤1, ␣X␤2, and ␣V␤3 have been implicated in rotavirus cell attachment and entry. The virus spike protein VP4 contains the ␣2␤1 ligand sequence DGE at amino acid positions 308 to 310, and the outer capsid protein VP7 contains the ␣X␤2 ligand sequence GPR. To determine the viral proteins and sequences involved and to define the roles of ␣2␤1, ␣X␤2, and ␣V␤3, we analyzed the ability of rotaviruses and their reassortants to use these integrins for cell binding and infection and the effect of peptides DGEA and GPRP on these events. Many laboratory-adapted human, monkey, and bovine viruses used integrins, whereas all porcine viruses were integrin independent. The integrin-using rotavirus strains each interacted with all three integrins. Integrin usage related to VP4 serotype independently of sialic acid usage. Analysis of rotavirus reassortants and assays of virus binding and infectivity in integrin-transfected cells showed that VP4 bound ␣2␤1, and VP7 interacted with ␣X␤2 and ␣V␤3 at a postbinding stage. DGEA inhibited rotavirus binding to ␣2␤1 and infectivity, whereas GPRP binding to ␣X␤2 inhibited infectivity but not binding. The truncated VP5* subunit of VP4, expressed as a glutathione S-transferase fusion protein, bound the expressed ␣2 I domain. Alanine mutagenesis of D308 and G309 in VP5* eliminated VP5* binding to the ␣2 I domain. In a novel process, integrin-using viruses bind the ␣2 I domain of ␣2␤1 via DGE in VP4 and interact with ␣X␤2 (via GPR) and ␣V␤3 by using VP7 to facilitate cell entry and infection.Rotaviruses are leading causes of acute gastroenteritis in human infants and young animals. Their restricted tropism suggests that very specific virus-host cell interactions are necessary to establish infection. The viral spike protein VP4, the major cell attachment protein, is cleaved by trypsin for enhanced infectivity into two subunits, VP5* (60 kDa) and VP8* (28 kDa). VP4 and the major outer capsid protein VP7 independently define serotype specificities. The inner capsid protein VP6 contains group-specific antigenic determinants. Reassortant rotaviruses containing combinations of the 11 double-stranded RNA genes from two parental viruses can be generated (27) which occasionally show unexpected phenotypes due to VP4-VP7 interactions (43).Integrins ␣2␤1, ␣X␤2, and ␣4␤1 were implicated in group A rotavirus cell attachment and entry (11, 23), and ␣V␤3 was proposed to mediate rotavirus cell entry (20). Integrin usage by rotaviruses was discovered when VP5* was shown to contain the type I collagen-derived, ␣2␤1 ligand sequence DGE at amino acids 308 to 310, and the fibrinogen-derived ␣X␤2 integrin ligand sequence GPR was identified in VP7 at amino acids 253 to 255 (11). Peptides containing these viral integrin ligand sequences (GPRP and RDGEE), monoclonal antibodies (MAbs) to ␣2␤1 and MAbs to ␤2, inhibited the infection of monolayers of MA104 and Caco-2 cells by simian rotavirus SA11 and/or human rotavirus RV-5 by 30 to 90% in additive fashion (9, 11). Infectivity blockade in MA104 cell monolayers...

Abstract. The trafficking of lymphocytes from the blood and into lymphoid organs is controlled by tissueselective lymphocyte interactions with specialized endothelial cells lining post capillary venules, in particular the high endothelial venules (HEV) found in lymphoid tissues and sites of chronic inflammation . Lymphocyte interactions with HEV are mediated in part by lymphocyte homing receptors and tissue-specific HEV determinants, the vascular addressins. A peripheral lymph node addressin (PNAd) has been detected immunohistologically in mouse and man by monoclonal antibody MECA79, which inhibits lymphocyte homing to lymph nodes and lymphocyte binding to lymph node and tonsillar HEV The human MECA-79 antigen, PNAd, is molecularly distinct from the 65-kD mucosal vascular ADHESION to endothelial cells initiates the process of DH

By inserting synthetic oligonucleotides into a highly expressed gene in E. coli it has been shown that unfavourable codon usage can reduce the maximum translation rate of a protein. However, in the case of the codon used (AGG), a significant effect on translation was only seen at very high transcription rates from a gene containing multiple copies of the unfavourable codon.