Apoptosis of neurons in rats with experimental allergic encephalomyelitis

NPP2, also known as phosphodiesterase-I alpha/autotaxin, is a type-II membrane protein that belongs to the nucleotide pyrophosphatase/phosphodiesterase family (NPP). We have recently demonstrated that NPP2 is expressed and released by differentiating oligodendrocytes during the critical stages of CNS myelination. The structural domains of this secreted macromolecule suggest a functional role in the regulation of oligodendrocyte adhesion. Here, we present data that demonstrates that NPP2 interferes with the ability of oligodendroglial cells to adhere to known CNS adhesion molecules present during the onset of myelination, such as fibronection, vitronectin, and merosin (laminin2). Responses to NPP2 appear to be regulated by a different mechanism depending on the developmental stage of the oligodendrocyte. Although the exact mechanisms for NPP2 mediated counter-adhesion are unknown, our studies have implicated that an active signalling mechanism involving heterotrimeric G proteins is responsible for adhesion modulation. These studies clearly define a role of NPP2 as a matricellular protein modulating oligodendrocyte adhesion and suggest that NPP2 function may represent the first step of oligodendrocyte remodelling when differentiating oligodendrocytes are actively involved in the formation of the myelin sheath.     

Suppression of experimental allergic encephalomyelitis in rats by mercuric chloride

Brown-Norway (BN) rats are uniquely susceptible to development of autoimmune phenomena and enlargement of lymph nodes and spleen after repeated injections of mercuric chloride. Despite its ability to produce autoimmunity, HgCl2 inhibited the development in BN rats of experimental allergic encephalomyelitis (EAE), another autoimmune process. The inhibition by mercury was probably due to lack of the normal absorption and granulomatous reaction to the EAE inoculum in the enlarged lymph nodes draining the inoculation site. Lewis rats did not develop enlarged nodes from HgCl2 treatment. Lewis lymph nodes absorbed the EAE inoculum abundantly and developed an extensive granulomatous reaction despite the mercury treatment, and there was only a slight inhibition of EAE. Therefore, the ability of HgCl2 to produce lymphadenopathy in BN rats may be responsible for the inability of these rats to absorb the inoculated antigen. The mercury-induced failure of absorption was manifested as an inhibition of EAE in BN rats.     

Niridazole suppression of experimental allergic encephalomyelitis in Lewis rats.

Administration of niridazole to Lewis rats beginning 2 days before sensitization with guinea pig spinal cord in combination with immunologic adjuvants exerted a dose related suppressive influence on development of experimental allergic encephalomyelitis (EAE). A daily dose of 75 mg/kg completely prevented clinical neurologic signs as well as markedly suppressed occurrence of immunohistopathologic manifestations of this autoimmune disease. A higher daily dose level of niridazole, i.e., 100 mg/k, also inhibited EAE but was associated with neurotoxic manifestations.     

Prolonged suppression of experimental allergic encephalomyelitis in the Lewis rats: the effect of lipopolysaccharides

The current investigations have revealed that Lewis rats preimmunized with BP in CFA, and after recovery from the first episode of EAE, developed a second mild attack of EAE after challenge with BP/CFA at specified times. However, preimmunization of Lewis rats with BP complexed to LPS in CFA protects animals for a longer time from a second attack induced by BP/CFA challenge.     

Lipid peroxidation in experimental allergic encephalomyelitis

Lipid peroxidation (LPO) in the brain and blood of guinea-pigs was studied during experimental allergic encephalomyelitis. The most pronounced activation of LPO in the brain occurred at the 7th day of sensitization with encephalolitogenic emulsion. It manifested by an increase in the content of diene conjugates and malonic dialdehyde, activation of catalase and reduction of superoxide dismutase activity. LPO activation in the blood occurred at the 3th-5th day of sensitization. It is assumed that LPO activation is caused by antigen-antibody reaction that occurs in the blood at the 3d day and in the brain at the 7th day of sensitization.     

Dissociation of experimental allergic encephalomyelitis protective effect and allergic side reactions in tolerization with neuroantigen

Administration of autoantigens under conditions that induce type 2 immunity frequently leads to protection from T cell-mediated autoimmune diseases. Such treatments, however, are inherently linked to the induction of IgG1 Abs and to the risk of triggering anaphylactic reactions. We studied the therapeutic benefit vs risk of immune deviation in experimental allergic encephalomyelitis of SJL mice induced by MP4, a myelin basic protein-proteolipid protein (PLP) fusion protein. MP4 administration in IFA induced type 2 T cell immunity, IgG1 Abs, and experimental allergic encephalomyelitis protection, and all three were enhanced by repeat injections. Despite high Ab titers, anaphylactic side reactions were not observed when MP4 was repeatedly injected in IFA or as soluble Ag s.c. In contrast, lethal anaphylaxis was seen after s.c. injection of soluble PLP:139-151 peptide, but not when the peptide was reinjected in IFA. Therefore, the Ab response accompanying the immune therapy constituted an anaphylactic risk factor only when the autoantigen was not retained in an adjuvant and when it was small enough to be readily disseminated within the body. Taken together, our data show that treatment regimens can be designed to boost the protective type 2 T cell response while avoiding the risk of Ab-mediated allergic side effects.     

Passive induction of experimental allergic encephalomyelitis

Experimental allergic encephalomyelitis (EAE) is a widely used animal model of the human demyelinating disease multiple sclerosis. EAE is initiated by immunization with myelin antigens in adjuvant or by adoptive transfer of myelin-specific T cells, resulting in inflammatory infiltrates and demyelination in the central nervous system. Induction of EAE in rodents typically results in ascending flaccid paralysis with inflammation primarily targeting the spinal cord. This protocol describes passive induction of EAE by adoptive transfer of T cells isolated from mice primed with myelin antigens into na?ve mice. The advantages of using this method versus active induction of EAE are discussed.     

Active induction of experimental allergic encephalomyelitis

This protocol details a method to actively induce experimental allergic encephalomyelitis (EAE), a widely used animal model for studies of multiple sclerosis. EAE is induced by stimulating T-cell-mediated immunity to myelin antigens. Active induction of EAE is accomplished by immunization with myelin antigens emulsified in adjuvant. This protocol focuses on induction of EAE in mice; however, the same principles apply to EAE induction in other species. EAE in rodents is manifested typically as ascending flaccid paralysis with inflammation targeting the spinal cord. However, more diverse clinical signs can occur in certain strain/antigen combinations in rodents and in other species, reflecting increased inflammation in the brain.     

Lipid content in brain and spinal cord during experimental allergic encephalomyelitis in rats

Abstract— The content of cerebrosides, sulphatides, gangliosides, cholesterol and phospholipids was evaluated in the brain and spinal cord of rats during the acute and recovery stages of experimental allergic encephalomyelitis (EAE). During the acute stage there was a significant decrease of sulphatides and gangliosides in spinal cord; in brain, only sulphatides were diminished. In the recovery stage, cerebrosides and gangliosides were decreased in the brain, whereas the lipid content of the spinal cord was similar to that in control animals. Cholesterol esters were detected in the brain and spinal cord during both periods. The results show that the changes are not the same for brain and spinal cord during the acute and recovery stages and that glycosphingolipids from either white or grey matter seem to be preferentially altered.     

Neutral protease activity in lymphocytes of lewis rats with acute experimental allergic encephalomyelitis

Lymphocytes from popliteal and inguinal lymph nodes of Lewis rats with acute EAE as a result of injection of lyophilized guinea pig myelin in Freund's complete adjuvant exerted strong proteolytic activity at neutral pH toward myelin basic protein. After injection of myelin the level of proteolytic activity remained about the same as that in lymphocytes from Freund's adjuvant-injected controls until about day 10 after injection, just before the onset of paralytic symptoms; then the proteolytic activity increased to approximately double its former level. Myelin basic protein was hydrolyzed by whole lymphocytes, but more activity was unmasked by homogenization. Similar results were also obtained using lymphocytes from thymus of EAE and control animals. Lymphocytes with high levels of proteolytic activity were not absorbed by glass wool, did not stain with neutral red, nor did they phagocytose antibody-coated sheep red blood cells. Thymus and lymph node lymphocytes cleaved myelin basic protein to three major peptides and a fourth minor peptide, while spleen lymphocytes hydrolyzed basic protein at only one point resulting in two peptides whose molecular weights added up to that of myelin basic protein. The protease activity was inhibited by 5×10^–3 Mp-chloromercuribenzoate and by phenylmethyl sulfonyl fluoride, TPCK, and soybean trypsin inhibitor, therefore the enzymatic activity probably depends on a serine residue and a sulfhydryl group. The bulk of the enzymatic activity is mostly membrane bound with the highest specific activity and total activity contained in a lysosomal-mitochondrial fraction. In view of the infiltration of lymphocytes into the brain substance in acute EAE, it is suggested that these cells may contribute to the destruction of myelin which is usually attributed to the monocyte or macrophage.     

The suppression of experimental allergic encephalomyelitis in Lewis rats by treatment with myelin basic protein-cell conjugates

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.