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trocytes in lesions in multiple sclerosis (MS) brains. SP has been shown to play a pro-inflammatory role in some chronic diseases. Since reports have been pub- lished that peripheral blood human mononuclear phagocytes reduce interleukin 1 (ILl) and tumor necrosis factor (TNFa) in response to SP, we examined the induction of these cytokines by microglia and astro- cytes. Rat ameboid microglia express approximately 5000 receptors for SP per cell. 5% are high-affinity receptors with a K d of 8.2 × 106 M, and 95% are low-affinity receptors with a K d of 2 × 10 6 M. Compet- itive studies with SP analogue and the non-peptide antagonist CP96,345 demonstrate these receptors to be non-classical NK-1 receptors. SP alone did not stimu- late ILl or TNFa production nor did it stimulate intracellular Ca 2+. However, in synergy with subopti- mal concentrations of LPS, SP quadrupled ILl produc- tion compared to LPS alone and increased intracellular Ca 2+ by 10000-fold. TNFa was not induced. In con- trast, rat astrocytes were directly stimulated by SP to produce significant amounts of ILl and to a lesser extent TNFa. As in diseased or traumatized brain, astrocytes in vitro express SP receptors. SP and cal- cium ionophore A23187 both raised intracellular cal- cium and treatment with dibromo B A P T A / A M , an intracellular calcium buffer, blocked SP-induced ILl production. These findings indicate that SP induction of ILl in astrocytes is calcium-dependent. Because astrocytes do not express SP receptors in normal healthy brain, two signals must be generated to elicit the response to SP, in disease or trauma: one is to induce receptors and the second is a high enough concentration of SP to transduce a signal. Likewise, ameboid microglia which constitutively express recep- tors will not respond to SP without a priming signal. This suggests that in the brain there is a safety mecha- nism to prevent production of putatively inflammatory proteins like ILl and TNFa from being produced in response to ubiquitous neuropeptides in the absence of priming signals generated by disease processes. Our results indicate local SP may therefore play a role in multiple sclerosis and certain other CNS inflamma- tions.

C37.MJLFS932.3.

TNFoL-treated astrocytes express the leukocyte adhe- sion molecules ELAM-1, VCAM-1, IG9 protein and ICAM-1

A.A. Hurwitz, T.M. Calderon, M.K. Guida, W.D. Ly- man and J.W. Berman Albert Einstein College of Medicine, Bronx, NY,, USA

Astrocytes have been implicated in inflammatory responses in the CNS. Upregulation of class II MHC

molecules, cytokine secretion and intercellular adhe- sion molecule 1 (ICAM-1) expression are among the immunological functions which have been documented for astrocytes. In the present study, we assessed the expression of the leukocyte adhesion molecules E- selectin (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), IG9, a monocyte adhesion molecule identi- fied in our laboratory, as well as ICAM-1. Immuno- cytochemical results demonstrated that after 5 h of TNFa exposure, astrocytes express ELAM-1, IG9 pro- tein, and ICAM-1. However, VCAM-1 protein expres- sion was only detected after 16 h of TNFoz treatment. Northern blot analysis confirmed the immunochemical findings for ELAM-1 and VCAM-1 and current studies are analyzing ICAM-1 mRNA expression. Other on- going studies are designed to examine the expression of adhesion molecules by astrocytes in vivo. The find- ings presented in this study support the hypothesis of a critical role for astrocytes in the CNS inflammatory response.

Neuroimmune interaction of TGF[~I and TGF[~2

Ram Sriram Department of Neurology, Burlington, VT, USA

University of Vermont,

TGF/3 belongs to a family of growth factors that demonstrate multi-functional properties. Depending on the cell type and their state of differentiation, they act to both inhibit and promote growth of mesenchymal cells. In view of its immunosuppressive properties, we have studied the effect of TGF/3 on T cell response to MBP and its effect on EAE. In vivo administration of TGF/3 reverses the paralytic phase of EAE without causing significant immunosuppression. In animals re- ceiving 7 doses of 1 p~g of TGF/3 s.c., only one out of 13 animals was paralysed as compared to 8 of 11 in the saline treated group. In addition, TGF~ decreases the severity and number of relapses when treatment was begun after the development of the initial relapse. Administration of anti-TGF/3 antibody significantly in- creases the mortality of EAE in animals naturally recovering from EAE, suggesting that TGF/3 is directly involved in the recovery process. Mice recovering from EAE show the presence of TGF/3 in the perivascular lymphocytes, endothelial cells and in astrocytes. The mechanisms by which TGFfl suppresses the develop- ment of EAE in vivo is not clear. One possible mecha- nism is that it directly affects the homing of T cells across the blood-brain barrier. Alternatively, we pro- pose that TGF/3 decreases the expression of MHC class II molecules on antigen-presenting cells. In in vitro studies, we show that IA expression of mouse astrocytes and DR expression of human astrocytoma cell lines are decreased when cultured in the presence

of gamma interferon and TGF/31. The inhibition of I A / D R expression is not universal and may be ex- plained by the differential expression of TGF/3 recep- tors on cells.

Suppression of experimental allergic encephalomyelitis by treatment with catalase

S.R. Ruuls, I. Huitinga and C.D. Dijkstra Department of Cell Biology, Medical Faculty, Free Uni- versity, Amsterdam, Netherlands

During experimental allergic encephalomyelitis (EAE), large perivascular infiltrates are present in the central nervous system. These infiltrates consist for 50% of macrophages (m~b). The importance of these m~b in the pathogenesis of the disease has been shown in a study in which elimination of m~b was found to suppress the clinical signs [1]. The infiltrating m~b can secrete numerous factors, among which are the reac- tive oxygen species (ROS) that can cause severe tissue damage. Stimulated m~b produce ROS in a so-called respiratory burst in which oxygen is reduced to super- oxide and subsequently to hydrogen peroxide and hy-

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droxyl radicals, all of which are highly reactive molecules. ROS have been shown to degrade myelin [2] and to kill oligodendrocytes [3] in vitro. In the present study, we have examined the possible patho- genetic role of ROS during EAE by administration of two physiological scavenging enzymes of ROS: superox- ide dismutase (SOD), which scavenges superoxide, and catalase, which scavenges hydrogen peroxide. Both scavengers were injected intraperitoneally from day 7 until day 16 after immunization, 10000 units kg -1 day- 1. Treatment of EAE rats with catalase resulted in a marked suppression of the clinical signs. Treatment with SOD had no effect on the clinical signs. These findings indicate that ROS, in particular hydrogen per- oxide, do indeed contribute to the demyelination dur- ing EAE. These ROS are probably secreted by the infiltrating map. Our results corroborate the theory that macrophages and their products can be considered as important effectors in the pathogenesis of demyeli- nating diseases of the (central) nervous system.

1 Huitinga et al. (1990) J. Exp. Med. 172, 1025. 2 Konat and Wiggins (1985) J. Neurochem. 45, 1113. 3 Kim and Kim (1991) J. Neurosci. Res. 29, 100.