Key Points• ADAM10 but not ADAM17 on leukocytes is essential for chemokine-induced signaling, adhesion, cytoskeletal rearrangement, and migration.• Leukocyte-expressed ADAM10 promotes leukocyte recruitment and edema formation in a murine model of acute pulmonary inflammation.Inflammation is a key process in various diseases, characterized by leukocyte recruitment to the inflammatory site. This study investigates the role of a disintegrin and a metalloproteinase (ADAM) 10 and ADAM17 for leukocyte migration in vitro and in a murine model of acute pulmonary inflammation. Inhibition experiments or RNA knockdown indicated that monocytic THP-1 cells and primary human neutrophils require ADAM10 but not ADAM17 for efficient chemokine-induced cell migration. Signaling and adhesion events that are linked to cell migration such as p38 and r GTPase-family activation, F-actin polymerization, adhesion to fibronectin, and upregulation of a 5 integrin were also dependent on ADAM10 but not ADAM17. This was confirmed with leukocytes isolated from mice lacking either ADAM10 or ADAM17 in all hematopoietic cells (vav 1 guanine nucleotide exchange factor [Vav]-Adam10 2/2 or Vav-Adam17 2/2 mice). In lipopolysaccharide-induced acute pulmonary inflammation, alveolar recruitment of neutrophils and monocytes was transiently increased in Vav-Adam17 2/2 but steadily reduced in Vav-Adam10 2/2 mice. This deficit in alveolar leukocyte recruitment was also observed in LysM-Adam10 2/2 mice lacking ADAM10in myeloid cells and correlated with protection against edema formation. Thus, with regard to leukocyte migration, leukocyteexpressed ADAM10 but not ADAM17 displays proinflammatory activities and may therefore serve as a target to limit inflammatory cell recruitment. (Blood. 2014;123(26):4077-4088)

The European Water Framework Directive aims to achieve a good ecological and chemical status in surface waters until 2015. Sediment toxicology plays a major role in this intention as sediments can act as a secondary source of pollution. In order to fulfill this legal obligation, there is an urgent need to develop whole-sediment exposure protocols, since sediment contact assays represent the most realistic scenario to simulate in situ exposure conditions. Therefore, in the present study, a vertebrate sediment contact assay to determine aryl hydrocarbon receptor (AhR)-mediated activity of particle-bound pollutants was developed. Furthermore, the activity and the expression of the CYP1 family in early life stages of zebrafish after exposure to freeze-dried sediment samples were investigated. In order to validate the developed protocol, effects of β-naphthoflavone and three selected sediment on zebrafish embryos were investigated. Results documented clearly AhR-mediated toxicity after exposure to β-naphthoflavone (β-NF) and to the sediment from the Vering canal. Upregulation of mRNA levels was observed for all investigated sediment samples. The highest levels of all investigated cyp genes (cyp1a, cyp1b1, cyp1c1, and cyp1c2) were recorded after exposure to the sediment sample of the Vering canal. In conclusion, the newly developed sediment contact assay can be recommended for the investigation of dioxin-like activities of single substances and the bioavailable fraction of complex environmental samples. Moreover, the exposure of whole zebrafish embryos to native (freeze-dried) sediment samples represents a highly realistic and ecologically relevant exposure scenario.

Metalloproteases of the A Disintegrin And Metalproteases (ADAM) family are important molecular mediators of inflammation. ADAMs participate at all stages of inflammation via the proteolytic cleavage of cell surface molecules. It has been shown that leukocyte expressed ADAM8 and ADAM17 are important during the initial rolling of leukocytes on the endothelium. However, the role of leukocyte expressed ADAMs in transendothelial migration and chemotaxis remains to be investigated and in particular it is still unclear to what extent ADAM10 and ADAM9 contribute to leukocyte migration. In this study we show that treatment of leukocytes with a pharmaceutical ADAM10 inhibitor reduced both the in vitro transendothelial migration and the chemotaxis of the monocytic cell line THP1. The combined pharmaceutical inhibition of both ADAM10 and ADAM17 did not further suppress leukocyte migration in either experimental setting. The subsequent analysis of THP1 cells with a gene silencing of ADAM8, 9, 10 or 17 in transendothelial migration and chemotaxis experiments revealed that ADAM8 and ADAM10 are critically involved in THP1 cell migration. While ADAM9 did not seem to be required ADAM17 was only ofminor importance for the migration of THP1 cells. This study analyses the role of the four proteases ADAM8, 9, 10 and 17 in the migration of leukocytic cells. It shows that ADAM8 and ADAM10 are crucial for the in vitro transendothelial migration and chemotaxis of the monocytic cell line THP1.