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1.
The purpose of this study was to determine whether fibrinolysis resulting from activation of the clotting cascade in juxtaposition to endothelial cells of the central nervous system (CNS) microvasculature is important for development of clinical signs of experimental allergic encephalomyelitis (EAE) in recipient Lewis rats. Rats were injected with previously primed syngeneic lymph node cells, activated in vitro with guinea pig myelin basic protein, and subsequently treated daily with trans-4-(aminomethyl)cyclohexanecarboxylic acid (AMCA), a synthetic inhibitor of plasminogen activator. Clinical signs of EAE were significantly suppressed in AMCA-treated rats compared to saline-treated control recipient animals. Furthermore, suppression of clinical signs in AMCA-treated rats was accompanied by a significant curtailment in EAE-associated increased permeability of the blood-brain barrier (BBB). These findings provide evidence that CNS-associated deposition of fibrin and ensuing fibrinolysis, together with increased permeability of the BBB, are related prerequisite events for expression of clinical manifestations of EAE.  相似文献   

2.
The immunopathogenesis of experimental allergic encephalomyelitis (EAE) is reviewed with special focus on the role of central nervous system fibrin deposition in the inflammatory cascade characterizing this autoimmune disease. Among rats sensitized to whole spinal cord or myelin basic protein of either guinea pig or bovine origin, there is a striking degree of concordance of perivascular fibrin deposits and occurrence of clinical paralytic signs. Neither paralytic signs nor fibrin deposition are temporally related to development of perivascular cellular infiltrates. Rats sensitized to neuroantigen and treated with ancrod, a polypeptide derived from the venom of Agkistrodon rhodostoma, develop profound hypofibrinogenemia, have a marked inhibition of fibrin deposition, and often exhibit no paralytic signs whatsoever. In contrast, cellular infiltrates are not demonstrably influenced by ancrod treatment. Activation of the clotting cascade at loci of developing immune injury of nervous tissue appears to result from and lead to increasing neurovascular permeability and accumulation of edema fluid. Distention of the extracellular space in central and peripheral nervous system tissues by edema fluid appears to be directly responsible for clinical abnormalities characterizing EAE in rats. Cellular infiltrates, on the other hand, appear to be an independent immune response to neuroantigenic sensitization.  相似文献   

3.
Role of the clotting system in the pathogenesis of neuroimmunologic disease   总被引:5,自引:0,他引:5  
Experimental allergic encephalomyelitis (EAE) is a prototypic neuroautoimmune disease involving sensitization to central nervous system myelin basic protein (MBP). Our studies of the clotting system and ensuing fibrinolysis implicate coagulation and cleavage of fibrin within or on the luminal surface of the cerebrovasculature as events initiating the inflammation characterizing EAE. Among recipient rats injected with MPB-primed, cultured-activated lymph node cells, opening of the blood-brain barrier (BBB) and deposition of perivascular fibrin within the spinal cord occur in parallel 1 day before onset of clinical signs of EAE. Daily treatment of recipient rats with trans-4-(aminomethyl)cyclohexanecarboxylic acid, a synthetic product that specifically inhibits plasminogen activator derived from endothelial cells, results in marked reduction of increased permeability of the BBB and suppression of clinical signs of EAE. We postulate that the critical event precipitating EAE is binding of circulating MBP-reactive immune effector cells to MBP immunodeterminants on the surface of cerebrovascular endothelial cells. Coagulation and ensuing fibrinolysis occur at sites of binding of effector cells to cerebrovascular endothelium. Release of biologically active peptides cleaved from fibrin open the BBB, thereby setting the stage for the cascade of inflammatory events culminating in clinical manifestations of EAE.  相似文献   

4.
Multiple sclerosis (MS) was characterized with widespread demyelination and axonal loss of central nervous system (CNS). Fibrinogen (fibrin) deposition was considered as one of the pathogenesis of MS. Therefore, we explored the effects of fibrinogen depleting agent batroxobin in experimental autoimmune encephalomyelitis (EAE) mice model. Our study showed that prevention and suppression with batroxobin significantly ameliorated clinical severity of EAE, reduced inflammatory cells infiltration, and demyelination, and suppressed the activation of astrocytes and macrophages comprising the CD11b+ population. Batroxobin treatment leads to reduced expression of p-Akt and increased expression of MBP as compared to control. In addition, batroxobin treatment partly reversed the dendric-like formation of macrophages irritated by fibrinogen in vitro. The reduced severity of EAE mice treated with batroxobin suggests that strategy targeting fibrin as a potential therapy for EAE may be beneficial for the treatment of MS patients.  相似文献   

5.
Dammarane steroids (DS) are a class of chemical compounds present in Panax ginseng. Here, we evaluated the effect of 10 weeks of DS supplementation on inflammatory modulation in the soleus muscle following eccentric exercise (EE)-induced muscle damage (downhill running). Eighty rats were randomized into 4 groups of DS supplementation (saline, 20, 60, 120 mg/kg body weight). Inflammatory markers were measured at rest and again 1 h after EE. At rest, NFκB signaling, TNF-alpha and IL-6 mRNAs, 3-nitrotyrosine, glutathione peroxidase, and GCS (glutamylcysteine synthetase) levels were significantly elevated in the skeletal muscle of DS-treated rats in a dose-dependent manner. Additionally, there were no detectable increases in the number of necrotic muscle fibers or CD68+ M1 macrophages. However, muscle strength, centronucleation, IL-10 mRNA expression, and the number of CD163+ M2 macrophages increased significantly over controls with DS treatment in rat soleus muscle. Under EE-challenged conditions, significant increases in muscle fiber necrosis, CD68+ M1 macrophage distribution, and 3-nitrotyrosine were absent in rats that received low and medium doses (20 and 60 mg/kg) of DS treatment, suggesting that DS possess anti-inflammatory action protecting against a muscle-damaging challenge. However, this protective activity was diminished when a high dose of DS (120 mg/kg) was administered, suggesting that DS possess hormetic properties. In conclusion, our study provides new evidence suggesting that DS is an ergogenic component of ginseng that potentiate inflammation at baseline but that produce anti-inflammatory effects on skeletal muscle following muscle-damaging exercise. Furthermore, high doses should be avoided in formulating ginseng-based products.  相似文献   

6.
The plasminogen activator 960 IU/mg protein activity isolated from cultured fluid of the calf kidney cells was introduced to albino rats (180-200 g) with experimental Heynmann nephritis every day during 4 days. Nephritis caused activation of haemostasis and inhibition of fibrinolysis in the blood. There was increased excretion of the fibrin, fibrinogen degradation products in urine as a results of the local fibrin deposition in diseased kidneys. The fibrinolytic activity of the cortical zone of kidney was markedly decreased. The plasminogen activator, infused to experimental animals, resulted in normalization of the altered indexes.  相似文献   

7.
Pretreatment of Lewis rats with guinea pig (GP) myelin basic protein (MBP) coupled to syngeneic spleen leukocytes (SL) suppressed the subsequent induction of experimental allegic encephalomyelitis (EAE) with GP-MBP in Freund's complete adjuvant. The degree of suppression correlated positively with the amount of antigen coupled to the SL. GP-MBP coupled to syngeneic red blood cells (RBC) also resulted in suppression of EAE and the extent of the suppression was related to the dose of cells. These regimens of pretreatment also resulted in a decrease in the in vitro lymphocyte proliferative response to GP-MBP and in the extent of perivascular cuffing in the spinal cord. No decrease in the anti-MBP antibody response was detected in rats pretreated with either GP-MBP-SL or GP-MBP-RBC conjugates. Transfer of lymph node cells from rats pretreated with GP-MBP-RBC resulted in a decrease in disease severity in recipients. It is concluded that prior administration of MBP-cell conjugates is an effective way of suppressing the symptoms of EAE.  相似文献   

8.
As part of a study on the role of vasoactive amines in experimental autoimmune encephalomyelitis (EAE), we have found that treatment beginning 7 days post-inoculation (dpi) with the specific alpha 1-adrenoceptor antagonist prazosin can significantly suppress clinical signs of disease in the Lewis rat. In this paper we have addressed the effect of treatment with prazosin commencing at varying times in the disease process. The results show that treatment during the early inductive stage (1 to 6 dpi) has no effect on the clinical course of the disease, whereas treatment commencing at the time of onset of early clinical signs (10 to 16 dpi) still significantly suppresses EAE. Leakage of serum proteins into the central nervous system (CNS) and histologic expression of EAE are also suppressed. Prazosin had no effect on lymphocyte responses to mitogen or antigen as determined by lymphocyte transformation tests when lymphocytes were exposed to prazosin in vitro, and the responses of lymphocytes from prazosin-treated animals were similar to those from saline-treated animals. These results support the hypothesis that prazosin suppresses EAE through a direct vascular effect although they do not preclude an immunologic component to its mechanism of action.  相似文献   

9.
The coagulation and fibrinolytic mechanisms were investigated in a group of patients with severe pre-eclampsia and eclampsia and the findings were compared with those of healthy women in late pregnancy. In patients with pre-eclampsia the following significant differences were found: (1) greater depression of plasma fibrinolytic activity (euglobulin lysis time) than in normal pregnancy, (2) a higher level of inhibitor to urokinaseinduced lysis, (3) increased levels of serum fibrin degradation products, and (4) reduced platelet counts.In patients with eclampsia a progressive increase of the level of serum fibrin degradation products was found over the three days following eclamptic seizures. No such increase occurred after grand mal seizures in late pregnancy. The findings in this study support the view that intravascular clotting is taking place in pre-eclampsia and that this disturbance of the balance between coagulation and fibrinolysis may be localized to certain areas of the vascular compartment, particularly the placental and renal circulations. Fibrin deposition in the maternal vessels supplying the placenta would impair the placental blood flow, which may explain the placental insufficiency which occurs in pre-eclampsia. Likewise fibrin deposition in the renal vasculature will result in glomerular damage and proteinuria. Hypertension may be related to the renal ischaemic changes or a compensatory response to the presence of fibrin deposition in the vascular compartment. This evidence of intravascular fibrin deposition raises the question of the possible therapeutic value of antithrombotic agents to inhibit the clotting process. On a theoretical basis such treatment might be expected to improve blood flow to the placenta and thereby fetal growth.  相似文献   

10.
The exact mechanisms leading to CNS inflammation and myelin destruction in multiple sclerosis and in its animal model, experimental allergic encephalomyelitis (EAE) remain equivocal. In both multiple sclerosis and EAE, complement activation is thought to play a pivotal role by recruiting inflammatory cells, increasing myelin phagocytosis by macrophages, and exerting direct cytotoxic effects through the deposition of the membrane attack complex on oligodendrocytes. Despite this assumption, attempts to evaluate complement's contribution to autoimmune demyelination in vivo have been limited by the lack of nontoxic and/or nonimmunogenic complement inhibitors. In this report, we used mice deficient in either C3 or factor B to clarify the role of the complement system in an Ab-independent model of EAE. Both types of complement-deficient mice presented with a markedly reduced disease severity. Although induction of EAE led to inflammatory changes in the meninges and perivascular spaces of both wild-type and complement-deficient animals, in both C3(-/-) and factor B(-/-) mice there was little infiltration of the parenchyma by macrophages and T cells. In addition, compared with their wild-type littermates, the CNS of both C3(-/-) and factor B(-/-) mice induced for EAE are protected from demyelination. These results suggest that complement might be a target for the therapeutic treatment of inflammatory demyelinating diseases of the CNS.  相似文献   

11.
The effect of fibrin structure on fibrinolysis.   总被引:4,自引:0,他引:4  
Fibrin structure contributes to the regulation of the fibrinolytic rate. As the fibrin fiber size is decreased, the fibrinolytic rate also decreases. Fibrin structure was altered by either changing the ratio of thrombin to fibrinogen, i.e. altering the assembly rate or by adding a fibrin assembly inhibitor, iopamidol. Changes in the fibrinolytic rate were followed by measuring the time dependence of the decrease in the fiber mass/length ratio during fibrinolysis. A measure of the overall fibrinolytic rate was determined from the decrease in the mass/length ratio versus time. An 8-fold reduction in the fibrinolytic rate was seen on decreasing the mass/length ratio from 2.7 x 10(12) daltons/cm to 0.5 x 10(12) daltons/cm. It is shown that thin fibrin fibers have a decreased rate of conversion of plasminogen to plasmin by tissue plasminogen activator and that thin fibrin fibers are lysed more slowly than thick fibrin fibers.  相似文献   

12.
Fibrin deposition in parallel with loss of myelin basic protein (MBP), an antigenic constituent of central nervous system (CNS) myelin, within the lesions of animals with experimental allergic encephalomyelitis (EAE) suggested that degradation of MBP by proteolytic activity associated with blood clotting might be an important immunopathologic event in this prototypic autoimmune disease. Following incubation in normal rat serum at 37 °C for more than 4 hr, but not to any comparable degree in plasma, MBP had little or no encephalitogenic activity when bioassayed in guinea pigs or rats. Fragments of increasingly lower molecular weight were demonstrable by polyacrylamide gel electrophoresis after addition of MBP to rat serum; no fragments appeared after incubating the protein in rat plasma. Little or no loss of encephalitogenic activity was observed when MBP was incubated in serum containing protease inhibitors. These findings indicate that the serum-mediated degradation of MBP and concomitant loss of encephalitogenic activity is due to an enzymatic process associated with the coagulation cascade or/and the complement, kallikrein or fibrinolytic pathways. Implications of these findings concerning EAE and the multiple sclerosis process in man are discussed.  相似文献   

13.
The role of Ab deposition and complement activation, especially the membrane attack complex (MAC), in the mediation of injury in experimental allergic encephalomyelitis (EAE) is not resolved. The course of active EAE in normal PVG rats was compared with that in PVG rats deficient in the C6 component of complement (PVG/C6(-)) that are unable to form MAC. Following immunization with myelin basic protein, PVG/C6(-) rats developed significantly milder EAE than PVG/C rats. The anti-myelin basic protein response was similar in both strains, as was deposition of C3 in spinal cord. C9 was detected in PVG/C rats but not in PVG/C6(-), consistent with their lack of C6 and inability to form MAC. In PVG/C6(-) rats, the T cell and macrophage infiltrate in the spinal cord was also significantly less than in normal PVG/C rats. There was also reduced expression of P-selectin on endothelial cells, which may have contributed to the reduced cellular infiltrate by limiting migration from the circulation. Assay of cytokine mRNA by RT-PCR in the spinal cords showed no differences in the profile of Th1 or Th2 cytokines between PVG/C and PVG/C6(-) rats. PVG/C rats also had a greater increase in peripheral blood white blood cell, neutrophil, and basophil counts than was observed in the PVG/C6(-). These findings suggest that the MAC may have a role in the pathogenesis of EAE, not only by Ig-activated MAC injury but also via induction of P-selectin on vascular endothelium to promote infiltration of T cells and macrophages into the spinal cord.  相似文献   

14.
EN3638 is a new oxime derivative of salicylic acid that has immunosuppressive properties. Oral administration of the compound to rats during the incubation period of experimental allergic encephalomyelitis (EAE) delayed the onset of clinical signs. EN3638 was effective in both ordinary and hyperacute forms of EAE. Doses of 50, 100, or 150 mg/kg daily, 250 mg/kg three times a week, or 400 mg/kg twice a week suppressed both clinical and histologic evidence of EAE during the course of therapy (as long as 4 weeks) and for 8 or more days thereafter. Clinical EAE developed after a full incubation period after discontinuance of EN3638, probably due to the persisting depot of antigen in oil. When EAE was produced without an oily depot, a single dose suppressed the disease for at least 5 weeks in some rats. EN3638 was effective when given only in the second half of the incubation period but not when given at the time that EAE lesions and signs develop. Passive transfer experiments suggested that the drug prevented and even reversed sensitization to neural antigens. It had only slight effect on fully sensitized lymphoid cells or on the recruitment of nonimmune inflammatory cells in the nervous system, and it was not acting as a source of salicylate or as an adrenocortical stimulator.  相似文献   

15.
Remodeling of extracellular matrix (ECM) is a critical step in peripheral nerve regeneration. In fact, in human neuropathies, endoneurial ECM enriched in fibrin and vitronectin associates with poor regeneration and worse clinical prognosis. Accordingly in animal models, modification of the fibrinolytic complex activity has profound effects on nerve regeneration: high fibrinolytic activity and low levels of fibrin correlate with better nerve regeneration. The urokinase plasminogen receptor (uPAR) is a major component of the fibrinolytic complex, and binding to urokinase plasminogen activator (uPA) promotes fibrinolysis and cell movement. uPAR is expressed in peripheral nerves, however, little is known on its potential function on nerve development and regeneration. Thus, we investigated uPAR null mice and observed that uPAR is dispensable for nerve development, whereas, loss of uPAR affects nerve regeneration. uPAR null mice showed reduced nerve repair after sciatic nerve crush. This was a consequence of reduced fibrinolytic activity and increased deposition of endoneurial fibrin and vitronectin. Exogenous fibrinolysis in uPAR null mice rescued nerve repair after sciatic nerve crush. Finally, we measured the fibrinolytic activity in sural nerve biopsies from patients with peripheral neuropathies. We showed that neuropathies with defective regeneration had reduced fibrinolytic activity. On the contrary, neuropathies with signs of active regeneration displayed higher fibrinolytic activity. Overall, our results suggest that enforced fibrinolysis may facilitate regeneration and outcome of peripheral neuropathies.  相似文献   

16.
The effect of heparin on the proteolytic and fibrinolytic activities of plasmin and plasminogen was studied. Heparin at a concentration of 6.3.10(-6) M did not change the caseinolytic activity of plasmin and plasminogen stimulated by streptokinase but suppressed their fibrinolytic activity. At concentrations from 2.10(-8) to 0.5.10(-6) M heparin increased, whereas at 1.10(-6)-4.10(-6) M reduced the time of desAAfibrin clot half-lysis by plasmin. Within the concentration range of 2.10(-8) to 4.10(-6) M heparin did not change the time of the clot half-lysis by glu-plasminogen and slightly decreased the time of fibrin clot half-lysis by lys-plasminogen in the presence of the tissue activator. It was supposed that heparin inhibits the fibrinolytic effect of plasmin by way of formation of complexes with plasmin and reduction of plasmin specificity to the solid phase substrate, i. e., polymeric fibrin.  相似文献   

17.
Upregulation and/or maintenance of regulatory T cells (Tregs) during an autoimmune insult may have therapeutic efficacy in autoimmune diseases. Although several immunomodulatory drugs and molecules are available, most present significant side effects over long-term use. Cinnamon is a commonly used natural spice and flavoring material used for centuries throughout the world. Here, we have explored a novel use of cinnamon powder in protecting Tregs and treating the disease process of experimental allergic encephalomyelitis (EAE), an animal model of MS. Oral feeding of cinnamon (Cinnamonum verum) powder suppresses clinical symptoms of relapsing-remitting EAE in female PLP-TCR transgenic mice and adoptive transfer mouse model. Cinnamon also inhibited clinical symptoms of chronic EAE in male C57/BL6 mice. Dose-dependent study shows that cinnamon powder at a dose of 50 mg/kg body wt/d or higher significantly suppresses clinical symptoms of EAE in mice. Accordingly, oral administration of cinnamon also inhibited perivascular cuffing, maintained the integrity of blood-brain barrier and blood-spinal cord barrier, suppressed inflammation, normalized the expression of myelin genes, and blocked demyelination in the central nervous system of EAE mice. Interestingly, cinnamon treatment upregulated Tregs via reduction of nitric oxide production. Furthermore, we demonstrate that blocking of Tregs by neutralizing antibodies against CD25 abrogates cinnamon-mediated protection of EAE. Taken together, our results suggest that oral administration of cinnamon powder may be beneficial in MS patients and that no other existing anti-MS therapies could be so economical and trouble-free as this approach.  相似文献   

18.
A fibrinolytic metalloprotease with in vitro fibrinolytic effects was purified from the edible mushroom Pleurotus ferulae using several chromatography steps including anion and ion exchange, gel filtration, and fast protein liquid chromatography columns. The molecular mass of the enzyme was estimated to be 20.0?kDa, as determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fibrin zymography. The protease was active at 50°C, and pH 4.0, 5.0, and 8.0. The fibrinolytic activity of the enzyme was inhibited by ethyleneglycol-bis-(2-aminoethyl)-N,N,N′,N′ tetraacetic acid and strongly inhibited by two metal ions, Cu and Mg. In vitro assays evaluating fibrinolytic activity on a fibrin plate, fibrin turbidity, and thrombolytic activity on fibrin clots using human fibrinogen and human thrombin revealed that the enzyme could hydrolyze fibrin polymers directly and inhibit the formation of fibrin clots. In activated partial thromboplastin time (APTT) and prothrombin time assays, the enzyme strongly prolonged the APTT, which detects an activity of intrinsic and common pathways. The enzyme showed strong in vivo protective effect against mortality/paralysis from epinephrine plus collagen-induced acute thromboembolism in in vivo model. Our findings suggest that the enzyme may have a potential for treatment and prevention of thrombosis-relative diseases.  相似文献   

19.
Abstract Dextran sulphate (DS) 500 (M.W. 500 000) is commonly used as a reticuloendothelial (RE) blocker. We found that lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF) production in sera was enhanced when mice were pretreated with DS500. When mice were pretreated with DS1000 (M.W. 1 000 000), TNF activity in sera was also significantly enhanced by the LPS injection in comparison with the saline-treated group, but not by the pretreatment with the low molecular weight of DS5 (M.W. 5 000), neutral dextran (Dex) 500, or positively-charged diethylaminoethyl dextran (DEAE-Dex) 500. The enhancement of LPS-induced TNF production occurred from 2 h after DS500 pretreatment. Pretreatment with DS500 or DS1000 significantly suppressed the carbon clearance from the blood in mice from 2 h after DS injection, but this suppression was not detected by the pretreatment with DS5, Dex500, or DEAE-Dex500. We suggest that negative-charge and high molecular weight are essential for dextran derivatives to enhance LPS-induced TNF production, and that the enhancing effect of DS is closely related to the suppression of the RE function.  相似文献   

20.
Zhu CS  Hu XQ  Xiong ZJ  Lu ZQ  Zhou GY  Wang DJ 《Life sciences》2008,83(11-12):404-412
Previous studies have shown that vascular endothelial growth factor (VEGF) expression is up-regulated in both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), a model for MS, and may exacerbate the disease. However, it remains unknown whether anti-VEGF modalities could serve as a potential treatment for such central nervous system (CNS) autoimmune diseases. We constructed a recombinant adenoviral vector carrying FLAG-tagged sFlt-1(1-3) (the first three extracellular domains of Flt-1, the hVEGF receptor-1). Intramuscular transfection of the recombinant adenoviral vector suppressed VEGF-induced inflammatory cell infiltration in matrigel plugs. When given intracerebrally to EAE rats, recombinant sFlt-1(1-3) adenoviral vector significantly reduced disease severity compared to untreated rats. sFlt-1(1-3) gene transfer blocked VEGF and greatly reduced the number of cells that express VEGF and ED1-positive cells in CNS in EAE rats. This study demonstrates that sFlt-1(1-3) gene transfer into the brain ameliorates the severity of EAE by inhibiting monocyte recruitment in the CNS of dark Agouti rats.  相似文献   

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