| BackgroundBlood-brain barrier (BBB) is an important structure of the central nervous system, it is to maintain the stability of the central nervous system environment of great importance. BBB of the existence of the local environment within the central nervous system, as distinct from the body within the environment of other independent entity, thus ensuring the normal central nervous system of the physical activities.It is generally believed that the blood-brain barrier including:the brain capillary endothelial cells and their tight junctions (TJ) and the membrane Picchi astrocytes formed end-feet glial membrane. Among them, the brain capillary endothelial cells and their tight junctions are the main basis of the blood-brain barrier function and structure. Complex in the cell structure of the main material is based on the capillary endothelial cells and their closely linked, tight junction structure, quite stable, the main barriers and adhesions from the role of brain capillaries with the blood-brain endothelial cells material exchange between the first barrier. In the human tissue distribution closely connecting the molecular components of the expression was tissue-specific. The expression of different molecular components can be assembled in the human body has a different permeability barrier function of the organization to adapt to different organs and thus the functional needs. In the blood-brain barrier, the current discovery of the major molecular components in close connection with:①transmembrane protein claudin-5, claudin-1, occludin, JAM;②subsidiary cytoplasm protein ZO-1, ZO-2, ZO-3,7H6 and cingulin. The paracellular-tight junction channels(PTJC), the fence function was also have been found.The structure and function of blood-brain barrier to the maintenance of the integrity of the normal functioning of the nervous system is essential, at the same time, the changes of structure and function of tight junctions are key process of a variety of changes in the pathophysiology of diseases of the nervous system. With the development of neurooncology, it has been found that glioma cells can bring a variety of effects on blood-brain barrier during its occurrence and development and thus cause a variety of nervous system symptoms and complications. Glioma cell invasion, the development of blood-brain barrier tight junctions caused by the "destruction" is a glioma brain edema and epilepsy and other clinical manifestations of glioma and one of the main complications.Glioblastoma multiforme (GBM) is an extremely invasive, well-vascularized tumor believed to be of astroglial origin. It is the most prevalent and lethal of all primary malignant brain tumors, with a median survival rate of months. Despite the standard treatment of surgical resection of all primary malignant brain tumors followed by radiation and/or chemotherapy, the survival rate has increased only slightly over the past three decades. But how does glioma cell cause a series of pathophysiological changes in central nervous system? What is the molecular mechanism? These are weak links of current reaseach in glioma. In addition, the researchers also found that located in and around gliomas in vivo tumor vascular endothelial cells and their close inter-connections can be turned into a special kind of "blood tumor barrier" (BTB). This "barrier" is a major reason that now seriously restricted the presence of clinical efficacy of glioma. For a long time, in development and progression of glioma the specific structural and functional changes and mechanisms in the blood-brain barrier tight junctions have been not very clear.As to morphological changes of glioma in the blood-brain barrier, it is much differently described in literatures. Blood-brain barrier in gliomas of the impact of tight junctions, different scholars have also made an "open" and "integrity" of the results of different studies. To study the morphological changes of the blood-brain barrier in glioma, we analyzed 21 cases of human glioma specimens of glioma and explore the tumor cells to affect the ultrastructure of the blood-brain barrier; the same time, with advances of modern molecular biology, on the molecular level to clarify tight junctions of the blood-brain barrier in the glioma and its pathophysiological significance of the role has become the study of neural tumor priority. it has become the urgent work to clarify tight junctions of the blood-brain barrier in the glioma and its pathophysiological significance of the role on the molecular level.Studies have shown that tight junctions are compose of a variety of molecular components.Claudins currently be considered the formation of tight junction ultrastructure, tight junctions barrier properties of the decision and ion permeability properties of the main components. Claudins are the major transmembrane protein in the tight junctions complexes, while Claudin-5 is the main adhesion molecule within the brain microvessel endothelial cell tight junctions. Present study showed that in the variety of molecular components of tight junctions, Claudin-5 endothelial cells that form the skeleton of the tight junction protein. It is involved in the maintenance of tight junction-specific functions and barrier fence, and is considered as the main components of forming tight junction ultrastructure and deciding tight junction barrier properties and ion permeability. Claudin-5 are the necessary and sufficient conditions in the formation of tight junction. In many nervous system diseases, reduced expression of Claudin-5 has been shown to have a close relationship with increasing vascular permeability. In the cerebellum into a hemangioblastoma of the brain microvascular endothelial cells decreased the expression of Claudin-5 is of the important reasons in the formation of tumor capsule.In order to study the changes of the expression of molecular components of the blood-brain barrier tight junction in glioma, to clarify the molecular level from the glioma cells to the effects of blood-brain barrier tight junctions and their pathophysiological significance, we used to immunohistochemistry and RT-PCR technology, to explore the glioma cells of the blood-brain barrier tight junction molecule components of claudin-5 and its possible role in molecular biology and pathophysiology mechanisms.Objective:1. To provide a theoretical foundation in the morphological, we studied on the blood-brain barrier tight junctions ultrastructure changes in human glioma.2. Clarify the blood-brain barrier endothelial cell tight junction structure change in the gliomas of pathophysiological significance.3. To explore glioma cells BBB endothelial cells tight junction structure change and its possible molecular mechanism Molecular level by molecular level. We studied in the expression of molecular components of blood-brain barrier tight junctions major changes.Methods:1. Statistics of 21 cases of glioma patients in general, to collect the cases of glioma after surgery tissue samples removed. And collected six cases of temporal lobe epilepsy, a very distant parts of the temporal resection specimens of normal brain tissue as a control group; The 27 cases were divided into three groups:normal brain tissue groups, low-grade gliomas and high-grade gliomas.2. Using transmission electron microscopy of the ultrastructural characteristics of glioma tissue and normal brain tissue.3. Double immunofluorescence staining were used to analyze their expression of Claudin-5.4. Reverse-transcriptase polymerase chain reaction was used to investigate their expression level of Claudin-5.5. Statistical analysis:The use of SPSS13.0 statistical analysis package. Data are expressed x±s, Different levels of glioma and normal Claudin-5 mRNA bands were used to compare the OD ratios using a one-way analysis of variance and multiple comparisons, Further pairwise comparison using Bonferroni method. Meaning P< 0.05 for the difference was significant.Results:1. By transmission electron microscopy, In the control brain, the paracellular cleft between adjacent endothelial cells is sealed by continuous strands of tight junctions. In the low-grade gliomas, majority microvascular endothelial cells visible continuous tight junction, no obvious window formation; In the high-grade gliomas, tight junctions between microvascular endothelial cells severely damaged and endothelial cells showed obvious fracture. Remaining tight junction is also visible, part of the connection between endothelial cells are gap junctions. Typical fenestrations were found in endothelial cell and cytoplasm pinocytotic vesicles obviously increased, especially in the multiforme glioblastoma as forward, endothelial cell locally vermiculata cavity formation.2. Double immunofluorescent microscopy showed strong expression of Claudin-5 in the microvascular endothelial cells in the control brain tissue but few was detected in the high-grade gliomas. 3. RT-PCR results showed:Normal brain tissue, low grade gliomas, high grade gliomas Claudin-5 mRNA expression relative intensity:0.633±0.068,0.519±0.172,0.227±0.148. Compared with the high-grade gliomas, the low-grade gliomas and normal brain tissues showed significantly highter Claudin-5 mRNA expression, the difference was statistically significant(F= 17.283, P=0.000). But normal brain and low grade gliomas Claudin-5 mRNA expression level no significant difference (P>0.05)Conclusion:1. Glioma in their occurrence and development can affect to blood-brain barrier endothelial cells and destroy blood-brain barrier tight junctions ultrastructure.2. Brain glioma at different levels, the blood-brain barrier damage closely linked with varying degrees of acceptance. The higher the level of brain glioma, blood-brain barrier tight junction integrity of the greater degree of damage.3. At different levels of glioma, glioma cells can reduce the expression of Claudin-5 protein in blood-brain barrier endothelial cells tight junction in a variety of ways. The higher level of glioma, the lower expression of Claudin-5 protein in blood-brain barrier endothelial cells tight junction. And the decrease of Claudin-5 may be one of the important molecular mechanisms explaining break down of tight junction in brain gliomas.
|
PDF Full Text Request