Transforming growth factor-beta (TGF-beta) and vascular disease: CARP as a putative TGF-beta target gene in the vessel wall

CARP, a cardiac ankyrin repeat protein, is up-regulated during wound healing and induces angiogenesis in experimental granulation tissue

Cardiac ankyrin repeat protein (CARP) was identified by subtractive hybridization as one of a group of genes that are rapidly modulated by acute wounding of mouse skin. Quantitative RT-PCR showed that CARP was strongly induced during the first day after wounding (157.1-fold), and the high level persisted for up to 14 days. Immunohistochemistry and in situ hybridization revealed that CARP was expressed in skeletal muscle, vessel wall, hair follicle, inflammatory cells, and epidermis in the wound area. To examine the effects of CARP on wound healing, we developed an adenoviral CARP vector to treat subcutaneously implanted sponges in either rats or Flk-1(LacZ) knock-in mice. Four days after infection, CARP-infected sponges in rats showed a remarkable increase in the vascular component in granulation tissue as compared to Ad-LacZ controls. This result was confirmed by CD34 immunostaining. By 7 days post-infection of sponge implants in Flk-1(LacZ) knock-in mice, granulation tissue showed many more LacZ-positive cells in Ad-CARP-infected sponges than in virus controls. Ad-CARP treatment also induced neovascularization and increased blood perfusion in rabbit excisional wounds in and ischemic rat wounds. These findings indicate that CARP could play a unique role in therapeutic angiogenesis during wound healing.

Alterations in TGF-beta1 expression in lambs with increased pulmonary blood flow and pulmonary hypertension

The mechanisms responsible for pulmonary vascular remodeling in congenital heart disease with increased pulmonary blood flow remain unclear. We developed a lamb model of congenital heart disease and increased pulmonary blood flow utilizing an in utero placed aortopulmonary vascular graft (shunted lambs). Morphometric analysis of barium-injected pulmonary arteries indicated that by 4 wk of age, shunts had twice the pulmonary arterial density of controls (P < 0.05), and their pulmonary vessels showed increased muscularization and medial thickness at both 4 and 8 wk of age (P < 0.05). To determine the potential role of TGF-beta1 in this vascular remodeling, we investigated vascular changes in expression and localization of TGF-beta1 and its receptors TbetaRI, ALK-1, and TbetaRII in lungs of shunted and control lambs at 1 day and 1, 4, and 8 wk of life. Western blots demonstrated that TGF-beta1 and ALK-1 expression was elevated in shunts compared with control at 1 and 4 wk of age (P < 0.05). In contrast, the antiangiogenic signaling receptor TbetaRI was decreased at 4 wk of age (P < 0.05). Immunohistochemistry demonstrated shunts had increased TGF-beta1 and TbetaRI expression in smooth muscle layer and increased TGF-beta1 and ALK-1 in endothelium of small pulmonary arteries at 1 and 4 wk of age. Moreover, TbetaRI expression was significantly reduced in endothelium of pulmonary arteries in the shunt at 1 and 4 wk. Our data suggest that increased pulmonary blood flow dysregulates TGF-beta1 signaling, producing imbalance between pro- and antiangiogenic signaling that may be important in vascular remodeling in shunted lambs.