Identification of OPN, TNC and E-selectin as potential recognition proteins in cerebral vasospasm after subarachnoid hemorrhage

Abstract

Cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) is a serious and significant health problem in the worldwide. There are still no effective therapies for treatment of CVS in patients suffering from SAH. Our early studies have demonstrated that the expression of connexin43 (Cx43, a member of gap junctional proteins) in cerebral spastic vessel is significantly up-regulated, and knocking down Cx43 with specific siRNA interference can significantly alleviate CVS after SAH. Therefore, Cx43 in cerebral vessel is a potential target in the treatment of CVS. However, Cx43 is widely distributed in many organs, particularly in the heart, and plays an important role in the physiological function. This study is aimed at identify whether OPN, TNC or E-selectin can be used as a target protein to be recognized in spastic cerebral vessels, then we can produce a carrier containing Cx43 siRNA or other inhibitors as a new potential treatment for CVS. Twenty eight male Sprague Dawley rats (weighing 300–350 g) were randomly divided into either SAH (n = 16) or sham group (n = 12). The double hemorrhage model was performed on day 0 and 1. All animals were sacrificed after performing India ink angiography on day 5. Initially, the expression of E-selectin, TNC and OPN in cerebral arteries, thoracic aorta and abdominal aorta were analyzed respectively by immunohistochemical staining, western blot in both groups. Then, only those with less expression in thoracic aorta, abdominal aorta and normal cerebral arteries, but higher expression in cerebral spastic arteries were further detected in the spinal cord, heart, kidney, liver, spleen, lung, pancreas, mesenteric and pulmonary arteries, retina and brain tissue, respectively. TNC, OPN and E-selectin were markedly elevated in the spastic cerebral arteries in SAH group but not in control group. The expression of TNC, but not OPN and E-selectin, is abundant in both groups of thoracic aorta and abdominal aorta. Further study demonstrated that expression of OPN, but not E-selecting, in both groups is relatively rich in brain tissue, kidney, pancreas, mesenteric artery, spinal cord and retina, but in heart, liver, lung and pulmonary artery. However, the positive expression of E-selectin was detected in spleen in both groups. TNC is highly expressed in thoracic aorta and abdominal aorta, so it is unsuitable for being a recognition protein. Although OPN, unlike TNC, does not express much in vascular system, but it expresses in many other organs or tissues. However, E-selecting could be considered as a potential recognition protein because it is not so widely distributed in the organs or tissues detected.