Publications

Steatosis or fatty liver in individuals with human immunodeficiency virus (HIV) may result from HIV itself, the use of nucleoside analogues, concurrent infection with hepatitis B or C, alcohol use, diabetes mellitus, obesity, or combinations of these factors. Nucleoside analogues have been the focus of increasing concern, because several fatal cases of severe macrosteatosis, lactic acidosis, and hepatomegaly have been linked to the use of nucleoside analogues. Other classes of antiretroviral drugs, as well as opportunistic infections, can also cause hepatic injury without steatosis. The additive effect of these different risk factors, especially in the presence of underlying hepatic steatosis, likely contributes to the increased prevalence of hepatic abnormalities among HIV-infected individuals. The conditions under which some patients rapidly progress to hepatic failure and/or cirrhosis need to be defined. This is a US government work. There are no restrictions on its use.

Discoidin domain receptor 2 (DDR2) is a tyrosine kinase receptor expressed in mesenchymal tissues, the ligand of which is fibrillar collagen. We have compared DDR2 signaling in skin fibroblasts derived from DDR2(-/-) and DDR2(+/-) mice. Proliferation of DDR2(-/-) fibroblasts was significantly decreased compared with DDR2(+/-) cells. DDR2(-/-) fibroblasts exhibited markedly impaired capacity to migrate through a reconstituted basement membrane (Matrigel) in response to a chemotactic stimulus, which correlated with diminished matrix metalloproteinase-2 (MMP-2) activity by gelatin zymography and diminished MMP-2 transcription of a minimal MMP-2 promoter. In contrast, a lack of DDR2 had no effect on cell motility or alpha-smooth muscle actin or vinculin expression. Additionally, expression of type I collagen was greatly reduced in DDR2(-/-) cells. Stable reconstitution of either wild-type DDR2 or constitutively active chimeric DDR2 in DDR2(-/-) cells by retroviral infection restored cell proliferation, migration through a reconstituted basement membrane (Matrigel), and MMP-2 levels to those of DDR2(+/-) fibroblasts. These data establish a role for DDR2 in critical events during wound repair.