ADAM8 is selectively up‐regulated in endothelial cells and is associated with angiogenesis after spinal cord injury in adult mice

Abstract

Endothelial cell (EC) loss and subsequent angiogenesis occurs over the first week after spinal cord injury (SCI). To identify molecular mechanisms that could be targeted with intravenous (i.v.) treatments we determined whether transmembrane A Disintegrin And Metalloprotease (ADAM) proteins are expressed in ECs of the injured spinal cord. ADAMs bind to integrins which are important for EC survival and angiogenesis. Female adult C57Bl/6 mice with a spinal cord contusion had progressively more ADAM8 (CD156) immunostaining in blood vessels and individual ECs between 1 and 28 days following injury. Uninjured spinal cords had little ADAM8 staining. The increase in ADAM8 mRNA and protein was confirmed in spinal cord lysates, and ADAM8 mRNA was present in FACS-enriched ECs. ADAM8 co-localized extensively and exclusively with the EC marker PECAM and also with i.v. injected lectins. I.v. injected isolectin B4 (IB4) labels a subpopulation of blood vessels at and within the injury epicenter 3-7 days after injury, coincident with angiogenesis. Both ADAM8 and the proliferation marker Ki-67 were present in IB4-positive microvessels. ADAM8-positive proliferating cells were seen at the leading end of IB4-positive blood vessels. Angiogenesis was confirmed by BrdU incorporation, binding of i.v. injected nucleolin antibodies, and MT1-MMP immunostaining in a subset of blood vessels. These data suggest that ADAM8 is vascular-selective and plays a role in proliferation and/or migration of ECs during angiogenesis following SCI.

Tumor Necrosis Factor-α (TNF-α) Regulates Shedding of TNF-α Receptor 1 by the Metalloprotease-Disintegrin ADAM8: Evidence for a Protease-Regulated Feedback Loop in Neuroprotection

“…Nevertheless, ADAM8 is upregulated in spinal cords of SOD1(G93A) tg under disease conditions, most likely by other proinflammatory cytokines such as IL-1␤ (U. Schlomann and J.W.B., unpublished data). Interestingly, ADAM8 upregulation was also observed after spinal cord injury (Mahoney et al, 2009). Under these conditions, ADAM8 was reported to be involved in angiogenesis by colocalization with PECAM-1 in endothelial cells in the CNS, suggesting that, apart from inflammatory modulation, ADAM8 has additional functions in CNS pathologies.…”

Sildenafil Improves Epicenter Vascular Perfusion but not Hindlimb Functional Recovery after Contusive Spinal Cord Injury in Mice

“…Young adult (6-8 weeks old, 18-21 g) female C57BL/6 mice were used in this study and anesthetized using a 1.2% avertin solution (2,2,2-tribromoethanol) administered at 240 mg/kg IP and prepared as previously described (Benton et al, 2008a). Mice received T10 laminectomies and 50-kdyn contusions using the IH impactor (Infinite Horizons Inc., Lexington, KY) as previously described (Benton et al, 2008a;Mahoney et al, 2009;Scheff et al, 2003). No difference in mortality rates between groups receiving saline or sildenafil was observed.…”

Structure of human ADAM-8 catalytic domain complexed with batimastat

“…These are all important biological control processes to maintain proper cell growth and function. Consequently, dysregulation of ADAMs is associated with pathophysiological states, including inflammation, asthma, cancer, cardiovascular dysfunction and Alzheimer's disease (Fourie et al, 2003;Matsuno et al, 2008;Levula et al, 2009;Mahoney et al, 2009). Therefore, efforts are currently under way to develop small-molecule inhibitors to selectively target ADAMs for therapeutic purposes.…”