Deficiency of the Metalloproteinase-Disintegrin ADAM8 Is Associated with Thymic Hyper-Cellularity

Thymopoiesis requires thymocyte-stroma interactions and proteases that promote cell migration by degrading extracellular matrix and releasing essential cytokines and chemokines. A role for several members of the A Disintegrin and Metalloprotease (ADAM) family in T cell development has been reported in the past

Role of ADAM and ADAMTS metalloproteinases in airway diseases

Lungs are exposed to the outside environment and therefore to toxic and infectious agents or allergens. This may lead to permanent activation of innate immune response elements. A Disintegrin And Metalloproteinases (ADAMs) and ADAMs with Thrombospondin motifs (ADAMTS) are proteinases closely related to Matrix Metalloproteinases (MMPs). These multifaceted molecules bear metalloproteinase and disintegrin domains endowing them with features of both proteinases and adhesion molecules. Proteinases of the ADAM family are associated to various physiological and pathological processes and display a wide spectrum of biological effects encompassing cell fusion, cell adhesion, "shedding process", cleavage of various substrates from the extracellular matrix, growth factors or cytokines... This review will focus on the putative roles of ADAM/ADAMTS proteinases in airway diseases such as asthma and COPD

ADAM8/MS2/CD156a: a metalloprotease-disintegrin involved in immune responses

From all ADAM family members known, interesting features of some members of this the family are is their distinct expression patterns. ADAM8 is such an example, as it was identified originally in monocytes and is expressed in many specialised cell types, among them macrophages, B-cells, granulocytes, follicle cells, glandular epithelial cells, osteoclasts, oligodendrocytes, microglia, neurons and astrocytes. ADAM8 is activated by autocatalytic prodomain removal and the substrates like the Close Homologue of L1 (CHL1) and CD23 identified so far are either involved in cell adhesion or immune responses. In turn, ADAM8 expression in some cell types such as macrophages, astrocytes and microglia is regulated by inflammatory mediators including tumor necrosis factor-α, lipopolysaccharides (LPS) and prostaglandins. Whereas embryonal development in ADAM8 deficient mice appears normal, its upregulation under inflammatory conditions like that seen in chronic neurodegeneration, after administration of LPS and in allergic asthma, seems to reflect a specific function of ADAM8 in cytokine response. From recent experiments it can be concluded that the ADAM8 induction by inflammatory cytokines serves protective functions, e.g. by shedding of receptors mediating inflammatory responses or by degrading immune mediators directly

Tumor necrosis factor a induces a metalloprotease-disintegrin, ADAM8 (CD 156): Implications for neuron-glia interactions during neurodegeneration

Schlomann U, Rathke-Hartlieb S, Yamamoto S, Jockusch H, Bartsch JW. Tumor necrosis factor a induces a metalloprotease-disintegrin, ADAM8 (CD 156): Implications for neuron-glia interactions during neurodegeneration. JOURNAL OF NEUROSCIENCE. 2000;20(21):7964-7971.ADAM proteases, defined by extracellular disintegrin and metalloprotease domains, are involved in protein processing and cell-cell interactions. Using wobbler (WR) mutant mice, we investigated the role of ADAMs in neurodegeneration and reactive glia activation in the CNS. We found that ADAM8 (CD 156), a suspected leukocyte adhesion molecule, is expressed in the CNS and highly induced in affected CNS areas of WR mice, in brainstem and spinal cord. ADAM8 mRNA and protein are found at low levels throughout the normal mouse CNS, in neurons and oligodendrocytes. In the WR CNS regions in which neurodegeneration occurs, ADAM8 is induced in neurons, reactive astrocytes, and activated microglia. Similarly, the proinflammatory cytokine tumor necrosis factor alpha (TN-alpha) is upregulated and shows the same cellular distribution. In primary astrocytes from wild-type and WR mice, in primary cerebellar neurons, and in mouse motoneuron-like NSC19 cells, ADAM8 expression was induced up to 15-fold by mouse TNF-alpha, in a dose-dependent manner. In both cell types, ADAM8 was also induced by human TNF-alpha, indicating that TNF receptor type I (p55) is involved. Induction of ADAM8 mRNA was suppressed by treatment with an interferon-regulating factor 1 (IRF-1) antisense oligonucleotide. We conclude that IRF-1-mediated induction of ADAM8 by TNF-alpha is a signaling pathway relevant for neurodegenerative disorders with glia activation, proposing a role for ADAM8 in cell adhesion during neurodegeneration