E-selectin And Organ Damage In Hypertensive Rodents

E-selectin (Es), a kind of adhesion molecules, expressing on the surface of endothelial cell, was found in 1985 and the Es gene was cloned in 1989. Es has been referred to be"endothelial cell leukocyte adhesion molecule (EL-AM-1)", and it is named as Es or CD62E now. The same as other members of selectin family, Es is a single chain glycoprotein, of which one major character is tissue-specific. Expression of Es is confined to the surface of activated endothelial cells. Under normal circumstances, the body content of Es is very little. However, the expression of Es is significantly up-regulated when stimulated by the proinflammatory cytokines such as interleukin-1 (interleukin-1, IL-1), tumor necrosis factor-a (tumor necrosis factor-α, TNF-α), bacterial lipid sugar (LPS) and so on. Inflammatory response is co-mediated by a variety of adhesion molecules. Es, owing a Characteristic of transient expression and specificity, is prerequisite for the leukocyte adhering to endothelial cell, and passing through the vessel wall during inflammatory process. It can also mediate the early aggregation between leukocyte and endothelial cells, as well as to stimulate the interactions. Its role in inflammation has been confirmed to be not replaced by other adhesion molecules. Many studies have proved that Es are closely related to many diseases, including inflammation, skin diseases, tumor metastasis, organ transplantation, ischemic cerebral vascular and cardiovascular diseases. Soluble Es was formed by the abscission of Es into the blood within 24 h after expression on the endothelial cells. The level of Es in blood was considered to be reflected the level of Es expressed on endothelium, and the up-regulation of Es was considered to be one of the specific indicators of endothelial activation.Hypertension, a common disease caused by the combined action of many genes and environmental factors, is one of the major risk factors increasing the morbidity and mortality of many diseases, including stroke, coronary heart disease, chronic heart failure and kidney failure. Any great harm caused by almost all kinds of hypertension can be attributed to the damages of the body vessel and the target organs such as heart, kidney, aorta, and so on, by the elevated blood pressure. However, the level of blood pressure is not the only factor causing the damages of target organs. Recent studies showed that hypertension may be an inflammatory disease, and inflammation plays an important role in the occurrence and development of hypertension. Endothelial cell's activation, injury and renovation exist in patients with hypertension patients. It has been reported that the level of soluble Es significantly increased in patients with hypertension phaseⅡ, serum soluble Es is probably the target of activation of vascular endothelial cells in the hypertensive patients with target organ damage. Other studies have also confirmed that some Es gene polymorphism is associated with blood pressure. Our studies argued whether Es has relevance with the pathogenesis of different models of hypertension, as well as the impact for corresponding target organ damage. And we carry out the studies through the establishment of different hypertension animal models with different mechanism, including spontaneously hypertensive rats (SHR), C57Bl/6-2K1C, Es-/--2K1C, C57Bl/6-DOCA and Es-/--DOCA hypertension model.METHODSPartⅠ: The rats of SHR and its control WKY were eight, respectively. Femoral arterial blood was taken out after anaesthesia by diethyl ether, and was centrifugated at 2 000 g for 15 min after 2 hs. The organs heart, kidney and aorta were excised, and freezed into liquid nitrogen. Total protein of organs and serum were extracted for measuring expression of Es by ELASA.PartⅡ: 30 male C57Bl/6 and Es-/- (17~20g) were carried out two-kidney one clip (2K1C) surgery to establish renovascular hypertensive models, as well as to perform the sham-operated groups. All animals'blood pressure was measured by tail artery manometry at 12, 16 and 20 weeks, and all animals were killed after measurement of blood pressure at the 20 week, weighing the weight of target organs. The stand of the 2K1C model: SBP≥130 mmHg. The indexes, including LVW/BW, HW/BW, LVW/RVW and RKW/BW, were calculated. After the weighing, the marked organs were immediately placed in 4% neutral formalin for fixation, HE staining to observe pathological changes. Serum samples for serum creatinine (sCr), blood urea nitrogen (BUN) and creatine kinase (CK) were determined.PartⅢ: 30 male C57Bl/6 and 30 male Es-/- (22~26 g) were carried out left nephrectomy, experimental groups were injected deoxy corticosterone acetate (DOCA), as well as to feed brine (1.0% NaCl + 0.2% KCl) for 5 weeks to perform salt-induced hypertension models. Sham-operated groups were fed normally with left nephrectomy. All animals'blood pressure was measured by tail artery manometry at 12, 16 and 20 weeks, and all animals were killed after measurement of blood pressure at the 20 week, weighing the weight of target organs. The stand of the DOCA model: SBP≥130 mmHg. The indexes, including LVW/BW, HW/BW, LVW/RVW and RKW/BW, were calculated. After the weighing, the marked organs were immediately placed in 4% neutral formalin for fixation, HE staining to observe pathological changes. Serum samples for sCr, BUN and CK were determined.RESULTSPartⅠ:Compared to WKY rats, the Es expressions of SHR rat in heart, kidney, aorta significantly increased, but the no difference in serum.PartⅡ: Results of 2K1C experiments1. Blood pressure: the SBP of 2K1C sham-operated control groups between C57Bl/6 and Es-/- mice, no significant difference was determined (107±8.6 vs.111±5.6 mmHg, P>0.05). Compared with their respective control group, blood pressure of experimental group significantly increased, and the latter increased even more than the former (135±6.1 vs. 150±13.6 mmHg, P <0.01).2. Morphological and pathological observation: Compared with the respective control group, damage was showed in both C57Bl/6 and Es-/- mice kidneys with different degrees. Besides glomerular edema, hypertrophy, afferent glomerular arteriole and lobular artery wall thickening and edema, glomerular capillary plexus shrink, collapse, a great many of perivascular inflammatory cells infiltration can be seen by histopathological examination in the kidney of C57Bl/6 mice. Damage in Es-/- mice kidney was lighter than in C57Bl/6 mice kidney, with only glomerular edema, hypertrophy and hyperemia appearing, and less inflammatory cell infiltration. RKW/BW increased for both with Es-/- mice higher than C57Bl/6, which may be attributed to glomerular shrinkage in C57Bl/6 mice kidney. Damage in heart was not noticeable both in C57Bl/6 and Es-/- mice. Compared with the respective control group, the indicators, including LVW/BW, RVW/BW and VW/BW, did not change significant. Pathological examination showed better-defined cross striations in myocardial tissue, neither swelling nor hypertrophy, and at times inflammatory cell infiltration.3. Biochemical indicators: Compared with the respective control group, the serum CK concentration did not significantly changed both in C57Bl/6 and Es-/- experimental group. However, BUN and sCr levels were significantly increased, and the former was significantly higher than the latter, suggesting that the former renal injury is more serious than the latter.PartⅢ: Results of DOCA experiments1. Blood pressure: the SBP of DOCA sham-operated control groups between C57Bl/6 and Es-/- mice, no significant difference was determined (105±10.0 vs. 106±8.2 mmHg, P>0.05). Compared with their respective control group, blood pressure of experimental group significantly increased, however, no significant difference was seen between the two groups (134±4.0 vs. 138±6.4 mmHg, P>0.05).2. Morphological and pathological observation: Compared with the respective control group, damage was showed in both C57Bl/6 and Es-/- mice kidneys with different degrees. Besides glomerular edema, hypertrophy, afferent glomerular arteriole and lobular artery wall thickening and edema, glomerular capillary plexus shrink, collapse, perivascular inflammatory cell infiltration can be seen by histopathological examination in the kidney of C57Bl/6 mice. Es-/- mice kidney damage was lighter than in C57Bl/6 mice, with only glomerular edema, hypertrophy and hyperemia appearing, and less inflammatory cell infiltration. RKW/BW increased for both with Es-/- mice higher than C57Bl/6, which may be attributed to glomerular shrinkage in C57Bl/6 mice kidney. Mild heart damage was showed for both, between whom no significant differences were seen. Histopathological examination revealed mild swelling of myocardial tissue with clear striation, and scattered inflammatory cell infiltration. VW/BW, LVW/BW and LVW/RVW have increased, which may be related to myocardial swelling, but no significant difference between the two.3. Biochemical indicators: Compared with the respective control group, the serum CK concentration did not significantly changed both in C57Bl/6 and Es-/- experimental group. However, BUN and sCr levels were significantly increased, and the former was higher than the latter, suggesting that the former renal injury is more serious than the latter.CONCLUSION1. Es may be related to the target organ damage of SHR.2. Es plays a certain influence on the kidney damage of 2K1C renal hypertensive and DOCA salt hypertensive mice.