Suppression of immune responses is necessary to limit damage to host tissue during inflammation, but it can

Noninflamed skin venules support constitutive leukocyte rolling. P-selectin controls the rolling frequency, whereas E-selectin dictates rolling velocity (Vroll). Fucosylated selectin ligands are essential for all interactions, as rolling was absent in mice doubly deficient in alpha1,3-fucosyltransferase (FucT)-IV and FucT-VII. The rolling fraction was reduced in FucT-VII-/- animals but normal in FucT-IV-/- mice. However, Vroll was markedly increased in both strains. P-selectin ligands generated by FucT-VII are crucial for initial leukocyte tethering, whereas E-selectin ligands that permit maximum slowing of Vroll require simultaneous expression of FucT-IV and FucT-VII. These results demonstrate a role for FucT-IV in selectin-dependent adhesion and suggest that the endothelial selectins and FucTs have distinct but overlapping functions in the immunosurveillance of the skin.

Detachment of the rear of the cell from its substratum is an important aspect of locomotion. The signaling routes involved in this adhesive release are largely unknown. One of the few candidate proteins to play a role is RhoA, because activation of RhoA in many cell types leads to contraction, a mechanism probably involved in detachment. To study the role of RhoA in detachment regulation, we analyzed several subsets of expert migratory leukocytes by video microscopy. In contrast to fast-migrating neutrophils, eosinophils do not detach the rear of the cell unless stimulated with serum. When measuring the amount of active RhoA, with the use of a GSTRhotekin pulldown assay, we found that serum is an excellent activator of RhoA in granulocytes. Inhibition of RhoA or one of Rho's target proteins, the kinase ROCK, in neutrophils leads to the phenotype seen in eosinophils: the rear of the cell is firmly attached to the substratum, whereas the cell body is highly motile. ROCK-inhibition leads to impaired migration of granulocytes in filters, on glass, and through endothelial monolayers. Also, the ROCK signaling pathway is involved in changes of integrin-mediated adhesion. Eosinophil transduction by a tat-fusion construct containing active RhoA resulted in detachment stimulation in the presence of chemoattractant. From these results we conclude that activation of the RhoA-ROCK pathway is essential for detachment of migratory leukocytes.

IntroductionStaphylococcus aureus is a common human pathogen that induces both community-acquired and nosocomial infections. This Grampositive bacterium is well known for its suppurative diseases such as skin-limited abscesses and boils and more seriously endocarditis, sepsis, and toxic shock syndrome. 1,2 Its invasiveness is ascribed to the production of a wide repertoire of cell surface-expressed as well as secreted virulence factors that interfere with host defense. 2,3 Superantigens constitute a large portion of the secreted arsenal of staphylococci and modulate immune responses. They trigger nonspecific activation of T lymphocytes by binding to major histocompatibility complex (MHC) class II molecules on antigenpresenting cells outside the antigen-binding cleft and V ␤ domains of T-cell receptors (TCRs). 4 We have described chemotaxis inhibitory protein of S aureus (CHIPS), an excreted virulence factor of S aureus. 5,6 CHIPS is known to inhibit formylated peptide-and complement factor C5a-induced responses in neutrophils through direct binding to the formyl peptide receptor and C5a receptor (C5aR), respectively. 7 Thereby, CHIPS inhibits the initial activation and migration of neutrophils to the site of infection; thus, it hampers clearance of S aureus by innate immune cells. Recently, the structure of CHIPS consisting of residues 31 to 121 (CHIPS ) was resolved. 8 CHIPS is composed of an ␣-helix packed onto a 4-stranded antiparallel ␤-sheet, a domain also present in the C-terminal domain of superantigens. This protein also revealed to be homologous to the C-terminal domain of staphylococcal superantigen-like 5 (SSL5) and SSL7.SSLs are a family of secreted proteins identified through sequence homology to staphylococcal and streptococcal superantigens. 9 Eleven different SSLs exist that are encoded on staphylococcal pathogenicity island 2 in a conserved order. Staphylococci contain 7 to 11 different SSLs, and their homology varies between 36% and 67%. Allelic variants show 85% to 100% homology. 10,11 Determination of the crystal structures of SSL5 12 and SSL7 13 also revealed their high structural homology to superantigens; the N-terminal oligonucleotide/oligosaccharide-binding fold and the C-terminal ␤-grasp domain characteristic for superantigens are also observed in SSLs. However, residues important for MHC class II and TCR binding of superantigens are not conserved in SSLs, which may explain their inability to display superantigenic activities. 9,10,12 Recently, Langley et al 14 described binding of complement component 5 and immunoglobulin A (IgA) by SSL7, suggesting a role for SSLs in staphylococcal defense against host immune responses. SSL7 was subsequently found to bind the C␣2/C␣3 interface of IgA Fc, which is the adhesion site for the Fc␣RI. 15 So far, no other functions have been linked to the SSLs.Neutrophil recruitment to sites of infection is a multistep process. 16 The initial tethering and rolling of neutrophils on the endothelium of vessel walls during inflammation are mediated by P-selec...

Recent studies suggest that chemotherapy, in addition to its cytotoxic effects on tumor cells, can induce a cascade of host events to support tumor growth and spread. Here, we used an experimental pulmonary metastasis model to investigate the role of this host response in metastasis formation. Mice were pretreated with chemotherapy and after clearance of the drugs from circulation, tumor cells were administered intravenously to study potential "protumorigenic" host effects of chemotherapy. Pretreatment with the commonly used chemotherapeutic agents cisplatin and paclitaxel significantly enhanced lung metastasis in this model. This corresponded to enhanced adhesion of tumor cells to an endothelial cell monolayer that had been pretreated with chemotherapy in vitro. Interestingly, chemotherapy exposure enhanced the expression of VEGF receptor 1 (VEGFR-1) on endothelial cells both in vitro and in vivo. Administration of antibodies targeting VEGFR-1 reversed the early retention of tumor cells in the lungs, thereby preventing the formation of chemotherapy-induced pulmonary metastases. The data indicate that chemotherapy-induced expression of VEGFR-1 on endothelial cells can create an environment favorable to tumor cell homing. Inhibition of VEGFR-1 function may therefore be used to counteract chemotherapy-induced retention of tumor cells within the metastatic niche, providing a novel level of tumor control in chemotherapy. Cancer Res; 71(22); 6976-85. Ó2011 AACR.

Abstract-Mutations in the gene encoding thrombomodulin (TM), a thrombin regulator, are suspected risk factors for venous and arterial thrombotic disease. We have previously described the generation of TM Pro/Pro mice carrying a TM gene mutation that disrupts the TM-dependent activation of protein C. Here, it is shown that inbred C57BL/6J TM Pro/Pro mice exhibit a hypercoagulable state and an increased susceptibility to thrombosis and sepsis. Platelet thrombus growth after FeCl 3 -induced acute endothelial injury was accelerated in mutant mice. Vascular stasis after permanent ligation of the carotid artery precipitated thrombosis in mutant but not in normal mice. Mutant mice showed increased mortality after exposure to high doses of endotoxin and demonstrated altered cytokine production in response to low-dose endotoxin. The severity of the hypercoagulable state and chronic microvascular thrombosis caused by the TM Pro mutation is profoundly influenced by mouse strain-specific genetic differences between C57BL/6 and 129SvPas mice. These data demonstrate that in mice, TM is a physiologically relevant regulator of platelet-and coagulation-driven large-vessel thrombosis and modifies the response to endotoxin-induced inflammation. The phenotypic penetrance of the TM Pro mutation is determined by as-yet-uncharacterized genetic modifiers of thrombosis other than TM.

We provide evidence that hemostatic factors, associated with vascular injury, provide a regulatory microenvironment for re-endothelialization mediated by circulating progenitor cells.

This review aims to provide an in depth overview of the current knowledge of the effects of bovine immunoglobulins on the human immune system. The stability and functional effects of orally ingested bovine immunoglobulins in milk products are described and potential mechanisms of action are discussed. Orally ingested bovine IgG (bovine IgG) can be recovered from feces, ranging from very low levels up to 50% of the ingested IgG that has passed through the gastrointestinal tract. In infants the recovered levels are higher than in adults most likely due to differences in stomach and intestinal conditions such as pH. This indicates that bovine IgG can be functionally active throughout the gastrointestinal tract. Indeed, a large number of studies in infants and adults have shown that bovine IgG (or colostrum as a rich source thereof) can prevent gastrointestinal tract infections, upper respiratory tract infections, and LPS-induced inflammation. These studies vary considerably in target group, design, source of bovine IgG, dosage, and endpoints measured making it hard to draw general conclusions on effectiveness of bovine immunoglobulin rich preparations. Typical sources of bovine IgG used in human studies are serum-derived IgG, colostrum, colostrum-derived IgG, or milk-derived immunoglobulins. In addition, many studies have used IgG from vaccinated cows, but studies using IgG from nonimmunized animals have also been reported to be effective. Mechanistically, bovine IgG binds to many human pathogens and allergens, can neutralize experimental infection of human cells, and limits gastrointestinal inflammation. Furthermore, bovine IgG binds to human Fc receptors which, enhances phagocytosis, killing of bacteria and antigen presentation and bovine IgG supports gastrointestinal barrier function in in vitro models. These mechanisms are becoming more and more established and explain why bovine IgG can have immunological effects in vivo. The inclusion of oral bovine immunoglobulins in specialized dairy products and infant nutrition may therefore be a promising approach to support immune function in vulnerable groups such as infants, children, elderly and immunocompromised patients.