Accumulation of tissue factor in endothelial cells promotes cellular apoptosis through over-activation of Src1 and involves β1-integrin signalling

Accumulation of tissue factor (TF) within cells leads to cellular apoptosis mediated through p38 and p53 pathways. In this study, the involvement of Src1 in the induction of TF-mediated cell apoptosis, and the mechanisms of Src1 activation were investigated. Human coronary artery endothelial cell (HCAEC) were transfected with plasmids to express the wild-type TF (TFWt-tGFP), or a mutant (Ser253 → Ala) which is incapable of being released from cells (TFAla253-tGFP). The cells were then activated with PAR2-agonist peptide (SLIGKV-NH) and the phosphorylation of Src and Rac, and also the kinase activity of Src were assessed. Transfected cells were also pre-incubated with pp60c Src inhibitor, FAK inhibitor-14, or a blocking anti-β1-integrin antibody prior to activation and the phosphorylation of p38 as well as cellular apoptosis was examined. Finally, cells were co-transfected with the plasmids, together with a Src1-specific siRNA, activated as above and the cellular apoptosis measured. Activation of PAR2 lead to the phosphorylation of Src1 and Rac1 proteins at 60 min regardless of TF expression. Moreover, Src phosphorylation and kinase activity was prolonged up to 100 min in the presence of TF, with a significantly higher magnitude when the non-releasable TFAla253-tGFP was expressed in HCAEC. Inhibition of Src with pp60c, or suppression of Src1 expression in cells, reduced p38 phosphorylation and prevented cellular apoptosis. In contrast, inhibition of FAK had no significant influence on Src kinase activity or cellular apoptosis. Finally, pre-incubation of cells with an inhibitory anti-β1-integrin antibody reduced both Src1 activation and cellular apoptosis. Our data show for the first time that the over-activation of Src1 is a mediator of TF-induced cellular apoptosis in endothelial cells through a mechanism that is dependent on its interaction with β1-integrin

Molecular and histopathological identification of ovine neosporosis (Neospora caninum) in aborted ewes in Iraq

Aim: The objective of the present study was to detect Neospora caninum DNA in the placenta of sheep and evaluate the association of risk factors to polymerase chain reaction (PCR) positive and histopathological analysis of the placenta and fetal tissue samples of aborted fetuses. Materials and Methods: Fresh placenta from 51 aborted ewes was collected for PCR assay. Placental and fetal tissues of aborted fetuses, including brain, heart, liver, lung, and thymus, were collected for histopathological analysis, besides the risk factor data were obtained during the time of sampling. Results: From 51 placentas examined by PCR, 13.73% appeared positive to N. caninum DNA. The relationship between PCR positive and the risk factors revealed a significant difference (p0.05). Histopathological investigation of placental and fetal tissues of positive samples showed tissue cyst-like structure, necrotic foci, and infiltration of mononuclear cells. Other lesions were thickening in chorionic plate in placenta, severe vacuolization and death of neurons, microgliosis, demyelination, edema, and proliferation of astrocytes in brain. In addition, fibrous and fat deposition with stenosis in the heart, parenchymal necrosis, severe atrophy, vacuolization and hyalinization of hepatocytes, megakaryocyte, portal fibrosis in the liver, and interlobular septal thickening in lung without obvious lesions is seen in the thymus tissue samples. Conclusion: This is a unique study that confirmed N. caninum DNA in the placenta of aborted ewes in Iraq using PCR assay. Histopathological analysis of some aborted fetuses organs could provide a more confirmatory and reliable data for a significant role of neosporosis in increasing the rate of abortion in sheep, while the clinical data of risk factors could be used to control the transmission of N. caninum infection