PAF拮抗剂抑制环孢素A诱导的肾系膜细胞收缩作用的研究

本文采用SD大鼠肾脏系膜细胞培养及硅胶膜形态分析技术。研究环孢素A(CsA)诱导肾系膜细胞收缩作用及血小板活化因子拮抗剂BN52021对CsA诱导作用的抑制效应。结果示CsA引起系膜细胞收缩呈现时间和剂量依赖效应,其作用可逆。BN52021浓度为5×10~(-5)M时,可显著地抑制CsA的诱导作用。结果提示CsA通过可逆性诱导系膜细胞收缩引起肾小球毛细血管血流量和超滤系数(Kf)下降;血小板活化因子可能参与了这个过程,使用血小板活化因子拮抗剂可能有预防及治疗CsA肾毒性的作用。     

Eicosanoids and the liver

Prostaglandins and leukotrienes are ubiquitous mediators of a wide variety of physiologic and immunologic effects in liver function and disease. Although the biochemical, synthetic and catabolic pathways of these compounds from arachidonic acid are well known, their cellular mechanisms of action are less well understood. Numerous studies have demonstrated the role for leukotrienes in the pathogenesis and the protective action of PG in experimental animal models of liver injury. These have included models of liver cell damage due to ischemia, galactosamine, carbon tetrachloride, and lipopolysaccharide. More importantly, the results of these studies have led to the demonstration of protective properties of 16, 16 dimethyl PGE2 (dm PGE2) in a mouse model of viral hepatitis. These results have led to the use of IV PGE1 in the treatment of patients with fulminant viral hepatitis, where 71% overall survival was observed as well as in the setting of primary non function and recurrent hepatitis B following liver transplantation. While the mechanisms of prostaglandin hepatic protection are not well understood, it has been demonstrated that dm PGE2 abrogates the induction of tumour necrosis factor, leukotriene B4 (LTB4) and procoagulant activity by macrophages as well as attenuating the expression of major histocompatibility class antigens on the surface of hepatocytes, and may inhibit viral replication. Finally, prostaglandins are known to play a role in the renal dysfunction associated with cirrhosis and fulminant hepatic failure, and therefore further studies of these agents in the pathophysiology and treatment of liver diseases and their complications are warranted.     

Regulation of mesangial cell function by vasodilatory signaling molecules

Proliferation of mesangial cells and expansion of mesangial matrix is a hallmark of glomerular disease leading to end-stage renal failure and requiring renal replacement therapy. Independently from the type of injury, e.g. in glomerulonephritis or diabetic nephropathy, the response to injury is remarkably uniform. Chronic glomerular disease is frequently associated with increases in systemic blood pressure and altered intraglomerular hemodynamics. Furthermore, reduction of systemic blood pressure and inhibition of the vasoconstrictor peptide angiotensin II have been shown to delay end-stage renal failure in various types of human kidney disease. Since vasoconstrictors of mesangial cells and efferent glomerular arterioli, such as angiotensin II, are thought to be detrimental for the progression of chronic glomerular disease, we propose that vasodilatory factors which antagonize the effects of angiotensin II, might have beneficial effects during the course of progressive kidney disease. To support this concept we will summarize currently available data on the role of vasodilatory signaling molecules such as natriuretic peptides (ANP, BNP and CNP), nitric oxide (NO), the prostaglandines PGE2 and prostacycline, and the purine mediator adenosine in the regulation of mesangial function.     

Cholecystokinin-Stimulated Monocytes Produce Inflammatory Cytokines and Eicosanoids

Objectives : Plasma cholecystokinin increases with enteral feeding. Cholecystokinin increases intracellular calcium in lymphocytes/monocytes and is a lymphocyte co-mitogen. We hypothesize that decreased cholecystokinin production with "bowel rest" and parenteral nutrition may be beneficial in inflammatory bowel disease by down-regulating gut immune/inflammatory mechanisms. The majority of cells observed in mucosa of inflammatory bowel disease are monocytes and neutrophils. Cholecystokinin effect was therefore measured on monocyte production of proinflammatory mediators (tumor necrosis factor α, interleukin-1 β, intcrteukin-6) and neutrophil chemotaxins/activators (interleukin-8, granulocyte-macrophage colony stimulating factor, and leukotriene B₄). Methods : Peripheral blood monocytes (0.5 ± 10⁶) from healthy donors in 1 mL of RPMI 1640 plus 5% fetal calf serum were cultured for 24 h in 5% CO₂ at 37±C with 5 μg/mL endotoxin, 1 ± 10-⁻⁷ M cholecystokinin, or no agonist. Supernatants were analyzed by ELISA for cytokines and leukotriene B₄. Results : Endotoxin-stimulated monocytes produced 1130 pg/mL tumor necrosis factor versus 81 pg/mL for cholecystokinin, 612 pg/mL interleukin-1 versus 10 pg/mL, 694 pg/mL interIeukin-6 versus 30 pg/mL, 4531 pg/mL of interleukin-8 versus 3848 pg/mL, 21 pg/mL granulocytemacrophage colony stimulating factor versus 9 pg/mL, and 21 pg/mL leukotriene B₄ versus 12 pg/mL. Controls produced no cytokines/eicosanoids (N = 8, p < 0.001). Conclusion : Cholecystokinin increase with enteral feeding may up-regulate gut immune response. Cholecystokinin suppression with parenteral alimentation may decrease inflammatory mediator production.     

尼卡地平对大鼠肾小球系膜细胞凋亡的诱导

目的探讨尼卡地平体内对大鼠系膜细胞凋亡的诱导作用。方法分别用脱氧核糖核酸（ＤＮＡ）片断电泳、油镜观察细胞凋亡，浸条法测定蛋白尿和血尿。结果尼卡地平体内能诱导大鼠系膜细胞凋亡，同时伴轻度蛋白尿。结论尼卡地平在体内有诱导大鼠系膜细胞凋亡的作用。这可能是治疗系膜增生性肾小球肾炎的有效药物。     

Eicosanoids, osteoarthritis, and crystal deposition diseases

PURPOSE OF REVIEW: Eicosanoids are produced by chondrocytes, synoviocytes, and subchondral osteoblasts within the osteoarthritic joint and are involved in normal joint physiology as well as in the pathogenesis of joint disorders such as osteoarthritis. Calcium-containing crystals are found in most osteoarthritic joints and have been implicated in osteoarthritis. Recent advances in the understanding of the potential role of eicosanoids in the pathogenesis of osteoarthritis and in potential therapeutic targeting of eicosanoid pathways are reviewed. RECENT FINDINGS: The ability of interleukin-1beta to upregulate microsomal prostaglandin E2 synthase-1 in synovial fibroblasts and chondrocytes of patients with osteoarthritis has been demonstrated. A potential role for prostaglandin E2 in downregulating interleukin-1beta-induced inflammatory responses has also been described. Basic calcium phosphate crystals can upregulate cyclooxygenase-1 and cocylooxygenase-2 expression, both of which contributed to the observed increase in prostaglandin E2 production in human fibroblasts. Novel potential mechanisms of inhibition of eicosanoid synthesis are also discussed. Last, further evidence of amelioration of osteoarthritis in animal models by the dual 5-lipoxygenase/cyclooxygenase inhibitor licofelone has been reported. SUMMARY: The inhibition of prostaglandin synthesis has long been a ornerstone of the pharmacologic treatment of osteoarthritis. Nevertheless, prostaglandins may have potentially beneficial as well as deleterious effects in osteoarthritis. In addition, other eicosanoids such as leukotrienes have also been implicated in the pathogenesis of osteoarthritis. Therefore, more selective inhibition of prostaglandin pathways and/or inhibition of leukotriene activity may prove to be effective therapeutic strategies in osteoarthritis.     

Cytoskeletal reorganization by mycophenolic acid alters mesangial cell migration and contractility

Cytoskeleton alterations are a hallmark of mesangial cell activation during glomerulosclerosis. The aim of this study was to investigate whether mycophenolic acid (MPA) affects cytoskeletal organization and motility of human mesangial cells. Using the IP15 cell line, we found that treatment with 1 micromol/L MPA inhibited both receptor-dependent (angiotensin II) and receptor-independent (KCl) contractile responses, as well as serum-induced migration activity, suggesting alterations in the intracellular mechanisms that control mesangial cell motility. Immunofluorescence studies of MPA-treated cells provided evidence for decreased membrane disassembly/reassembly of alpha-smooth muscle actin and F-actin fibers, which was correlated with sustained quantitative and qualitative modifications of actin-associated proteins: calponin was overexpressed and became associated with actin fibers, whereas phosphorylation levels of cofilin and myosin light chain increased, suggesting both an activation of the mechanisms responsible for actin polymerization and an inhibition of actin-depolymerizing processes. These observations support a stabilizing effect of MPA on the mesangial actin cytoskeleton, which constitutes an additive action by which MPA, beyond its anti-inflammatory, antiproliferative and antifibrotic properties, might protect against excessive mesangial activation in the context of various glomerulopathies and kidney transplantation.     

Involvement of aldosterone and mineralocorticoid receptors in rat mesangial cell proliferation and deformability

We demonstrated recently that chronic administration of aldosterone to rats induces glomerular mesangial injury and activates mitogen-activated protein kinases including extracellular signal-regulated kinases 1/2 (ERK1/2). We also observed that the aldosterone-induced mesangial injury and ERK1/2 activation were prevented by treatment with a selective mineralocorticoid receptor (MR) antagonist, eplerenone, suggesting that the glomerular mesangium is a potential target for injuries induced by aldosterone via activation of MR. In the present study, we investigated whether MR is expressed in cultured rat mesangial cells (RMCs) and involved in aldosterone-induced RMC injury. MR expression and localization were evaluated by Western blotting analysis and fluorolabeling methods. Cell proliferation and micromechanical properties were determined by [3H]-thymidine uptake measurements and a nanoindentation technique using an atomic force microscope cantilever, respectively. ERK1/2 activity was measured by Western blotting analysis with an anti-phospho-ERK1/2 antibody. Protein expression and immunostaining revealed that MR was abundant in the cytoplasm of RMCs. Aldosterone (1 to 100 nmol/L) dose-dependently activated ERK1/2 in RMCs with a peak at 10 minutes. Pretreatment with eplerenone (10 micromol/L) significantly attenuated aldosterone-induced ERK1/2 phosphorylation. Aldosterone (100 nmol/L) treatment for 30 hours increased [3H]-thymidine incorporation and decreased the elastic modulus, indicating cellular proliferative and deforming effects of aldosterone, respectively. These aldosterone-induced changes in cellular characteristics were prevented by pretreatment with eplerenone or an ERK (MEK) inhibitor, PD988059 (100 micromol/L). The results indicate that aldosterone directly induces RMC proliferation and deformability through MR and ERK1/2 activation, which may contribute to the pathogenesis of glomerular mesangial injury.     

Possible catecholaminergic-opioidergic control of blood pressure during muscular contraction

The effects of an alpha 2 adrenoceptor blocker, yohimbine, and an alpha 1 adrenoceptor blocker, phenoxybenzamine, and the central alpha 2 adrenoceptor agonist, clonidine, on changes in arterial blood pressure and heart rate were studied during fatiguing muscular contractions to determine whether an adrenergic-opioidergic system might be involved in the mediation of cardiovascular function. Fatiguing contractions of the gastrocnemius and plantaris muscles of cats caused an increase in mean arterial blood pressure to 150-170 mmHg from resting values of 110-120 mmHg. Injection of clonidine into the cerebral aqueduct eliminated the increase in blood pressure; this effect was dose dependent. Naloxone antagonised the effects of the highest dose of clonidine (5 micrograms). Injections of yohimbine (1 microgram) into the cerebral aqueduct had no significant effect on this pressor response. Yohimbine (1 microgram) effectively counteracted the antipressor effects of clonidine when the two drugs were injected together until higher doses of clonidine (2-5 micrograms) were used. Phenoxybenzamine had no effect on the pressor response itself but unlike yohimbine was able to attenuate the effects of clonidine only when injected together. These data suggest that activation of muscle ergoreceptor afferent nerve fibres (group III and IV fibres) during muscular contractions may cause an increase in arterial blood pressure by interfering with an inhibitory adrenergic-endorphinergic pathway in the medullary region of the brainstem.     

Eicosanoids, signal molecules of liver cells

The information that has been accumulated in recent years about metabolism and function of eicosanoids in the liver does not yet allow the presentation of a comprehensive picture. It suffices, however, to attribute to these mediators an important role in signal transduction between the different cells of the liver, especially in inflammatory reactions, in immunologic disorders, and in septic shock. Much knowledge has been gained in recent years about the biochemistry and physiology of eicosanoids in many other tissues; the methodology of the analysis of eicosanoids, their metabolites, and their cellular functions is rapidly improving. This will assist in the elucidation of the signal functions of arachidonic acid derivatives in the liver.     

Small cell anaplastic carcinoma of the lung with mesangial proliferative glomerulonephritis

Mesangial proliferative glomerulonephritis is an uncommon manifestation of renal injury associated with neoplastic disease. A 50-year-old woman with small cell anaplastic cancer of the lung and nephrotic syndrome had renal biopsy findings that were consistent with diffuse mesangial cell proliferation. Electron microscopic evaluation of renal tissue demonstrated numerous intramesangial and paramesangial dense deposits. Resolution of the nephrotic syndrome with improvement in renal function was noted after a response of the patient's tumor to combination chemotherapy.     

In vitro studies on the control of myoepithelial cell contraction in the granular glands of Xenopus laevis skin.

Dermal granular glands in the anuran amphibian Xenopus laevis consist of a syncytial secretory compartment surrounded by a single layer of myoepithelial cells. Stimulation of contraction of the myoepithelial cells by α-adrenergic agonists results in expulsion of the contents of the gland, but such contraction can be blocked or opposed by a number of agents. Using a simple in vitro method to measure the amount of granular material expelled and thus the degree of contraction of the myoepithelial cells, we have studied the calcium dependence of stimulation by adrenaline, noradrenaline, and phenylephrine, the stimulation by high K⁺, and the opposition of the α-adrenergic stimulation of contraction by ionophores, theophylline, and high Ca²⁺.     

人胎肾小球系膜细胞产生与表达白介素－6

采用生物学方法与分子杂交技术观察了人胎肾小球系膜细胞产生与表达白介素－６。结果显示系膜细胞上清液中白介素－６活性明显高于对照组（Ｐ＜０．０１），Ｎｏｒｔｈｅｒｎｂｌｏｔ信号扫描分析结果为１０μｇ系胰细胞总ＲＮＡ中白介素－６ｍＲＮＡ是２２．９３；３０μｇ是８４．４４，提示人胎系膜细胞可自然产生白介素－６，并表达白介素－６ｍＲＮＡ。     

Eicosanoids and their role in the pathogenesis of diarrhoeal diseases

Eicosanoids are unsaturated fatty acid compounds derived from 20-carbon 'essential' fatty acids, the most important being arachidonate. Both cyclooxygenase and lipoxygenase products of arachidonate are abundant in the human gut and their biological effects include modulation of fluid and electrolyte secretion, motor activity, mucosal blood flow, and cytoprotection, in addition to chemotaxis and immune response in inflammation. In health, these lipid mediators reinforce or synergize normal homeostatic mechanisms that could proceed in their absence. Receptors for control of intestinal secretion can be divided into two major classes, one of which triggers the production of cyclic AMP and another, which initiates phospholipid breakdown and arachidonate release. An intimate connection appears to exist between phospholipid metabolism, cytosolic Ca2+ levels, electrogenic anion secretion, Na+ pump rate, electroneutral Na+/H+ exchange activity, and intracellular pH. Ca2+-dependent secretagogues affect fluid and electrolyte transport in the small and the large bowel by increasing Ca2+ entry and Ca2+ mobilization through stimulation of eicosanoid formation, prostaglandins of the E type being the most important. Secretory diarrhoea may be thought of, therefore, as cellular Ca2+ intoxication. Uncontrolled formation of eicosanoids, perhaps with a changed spectrum of arachidonate metabolites, may not only be the source of diarrhoea associated with mucosal inflammation, but may also be critical for cell proliferation resulting in abnormal cell differentiation, which seems to be the link between long-standing inflammatory bowel disease and the increased risk of colonic neoplasia. A better understanding of the pathophysiological role of eicosanoids in diarrhoeal disease has allowed reinterpretation of the rationale behind current therapy.