Urokinase Plasminogen Activator in Injured Adventitia Increases the Number of Myofibroblasts and Augments Early Proliferation

Abstract

Myofibroblasts are involved in vessel remodeling during the development of hypertension as well as after angioplasty and aortocoronary grafting, but the mechanisms of myofibroblastic phenotypic modulation are not fully elucidated. We assessed the role of urokinase plasminogen activator (uPA) and its proteolytic activity in myofibroblast differentiation and the early proliferation following mechanical injury of the rat carotid adventitia. The effects of perivascular application of recombinant uPA (r-uPA), proteolytically inactive r-uPA(H/Q) and uPA neutralizing antibody were evaluated 4 days after surgical injury to the adventitia. The phenotype of adventitial cells was assessed using anti-α-smooth muscle actin (α-SM actin) antibody, anti-SM heavy chain myosin, anti-high-molecular-weight caldesmon, anti-smoothelin and anti-ED-1 antibodies, proliferation by the expression of proliferating cell nuclear antigen, and the size of the adventitia by quantitative morphometry. Four days after injury, the intensive immunostaining for urokinase appeared in the rat carotid artery adventitia. At the same time, the frequency of α-SM actin-positive adventitial cells was 1.8 ± 1.1% in uninjured arteries and 25.2 ± 5.4% in injured arteries (p < 0.05), and the respective frequency of ED-1-positive cells 1.5 ± 1.1 and 25.0 ± 5.2%. The application of exogenous r-uPA doubled the numbers of α-SM actin-positive adventitial cells to 55.7 ± 6.8% (p < 0.05). ED-1-positive cells and proliferating cell nuclear antigen-positive cells as well as the size of the adventitia were also significantly increased after r-uPA compared with injury alone. In contrast, the proteolytically inactive r-uPA(H/Q) did not affect any parameters. The application of uPA neutralizing antibody attenuated the frequency of α-SM actin-positive cells to 12.6 ± 3.5% (p < 0.05), the frequency of ED-1-positive cells, and the numbers of adventitial cells. r-uPA stimulation of cultured human skin fibroblasts significantly increased the α-SM actin content in a concentration-dependent manner. In contrast, r-uPA(H/Q) did not induce changes in α-SM actin content. We conclude that uPA, which is upregulated in the injured adventitia, can augment adventitial cell accumulation, including myofibroblasts, and adventitia growth early after injury of the rat carotid artery adventitia by mechanisms involving proteolysis.

Presence of Myofibroblasts and Expression of Matrix Metalloproteinase-2 (MMP-2) in Ameloblastomas Correlate with Rupture of the Osseous Cortical

“…Previous studies demonstrated the expression of MMPs and uPA in both neoplastic and stromal components of ameloblastomas, permitting the hypothesis that these matrixdegrading enzymes may contribute to the local invasiveness of this odontogenic tumor [22][23][24][25]. Since recent reports have demonstrated that identification of myofibroblast have a prognostic role in many neoplasm [2,12,26,27] and that those cells produce high levels of MMP-2 and uPA [2,4,[14][15][16][17][18][19][20], the aim of the present study was to analyze the presence of myofibroblasts and the expression of MMP-2 and uPA in intra-osseous solid multicystic ameloblastoma to establish their prognostic significance.…”

“…Through expression and secretion of cytokines, chemokines, growth factors, extracellular matrix molecules, adhesion molecules and receptors, myofibroblasts promote epithelial-mesenchymal interactions, including neoplastic growth and invasion [4,[8][9][10][11][12][13]. Myofibroblasts also secrete enzymes responsible for matrix remodeling, including matrix metalloproteinase-2 (MMP-2) [4,[14][15][16] and urokinase plasminogen activator (uPA) [2,[17][18][19][20]. In addition, activation of those enzymes can lead to release and activation of sequestered cytokines and growth factors, which may favor angiogenesis and promotion of cellular migration [4].…”

A Novel Signaling Pathway

“…5a). Northern blot analyses were performed to investigate the effects of uPA-nAChR␣1/ uPAR interactions on fibroblast ␣SMA expression, a cytoskeleton protein marker for "activated" fibroblasts or myofibroblast phenotypic transformation (41,42) (Fig. 5b).…”

Role of multidomain structure of urokinase in regulation of growth and remodeling of vessels

“…Ассоциация uPar с α5β1 индуцирует в интегрине появление дополни-тельного сайта для фибронектина в дополне-ние к связывающему rgd-сайту. недавно на uPar был идентифицирован сайт связывания с α5β1 во втором домене (130)(131)(132)(133)(134)(135)(136)(137)(138)(139)(140)(141)(142) [49].…”

“…Способность урокиназы вызывать констриктивное ремоде-лирование поврежденной артерии может быть обусловлена ее влиянием на адвентицию сосу-да. нанесение на адвентицию экзогенной уро-киназы стимулирует ее рост, пролиферацию клеток и аккумуляцию α-актинположительных клеток и моноцитарно-макрофагальную ин-фильтрацию, а нейтрализующие урокиназу антитела, напротив, уменьшают количество клеток сок ратительного фенотипа и подавляют рост неоадвентиции в ответ на повреждение [142]. при этом, неактивная урокиназа (uPah/Q) и тканевой активатор плазминогена не оказывают стимулирующего влияния на ак-кумуляцию α-актинположительных клеток и макрофагов в поврежденной адвентиции, что указывает на определяющее значение протео-литической активности урокиназы для осу-ществления этих процессов.…”