Chronic stress promotes lymphocyte reduction through TLR2 mediated PI3K signaling in a β-arrestin 2 dependent manner

Reactive macrophages/microglia exert both protective or damaging effects in multiple sclerosis (MS), which contribute to the relapsing-remitting nature of MS. CD163 is considered a marker of M2 (alternatively activated) macrophages. In the MS brain, CD163(+) perivascular macrophages express molecules for antigen recognition and presentation. Here we further investigated the accumulation of CD163(+) macrophages/microglia in the parenchyma of MS brains. CD163 expression pattern was investigated in different lesions of brain tissue specimens from five MS brains and five neuropathologically unaffected controls by immunohistochemistry. In the parenchyma of normal brain samples, immunoreactivity (IR) of CD163 was absent. In acute active lesions and at the rim of chronic active lesions of MS, strong accumulation of CD163(+) macrophages/microglia was seen. In chronic inactive lesions and in the center of chronic active lesion, CD163(+) macrophages/microglia were rare. Further, double-labeling showed that parenchymal and perivascular CD163(+) macrophages/microglia were myelin basic protein positive and HLA-DR(+), suggesting that CD163(+) macrophages/microglia could ingest and present antigen. In addition, in vitro incubating macrophage RAW264.7 cells with myelin turned LPS-induced inflammatory macrophages into an anti-inflammatory phenotype, indicating that myelin basic protein positive, CD163(+) macrophages/microglia in MS might have anti-inflammatory effects. The parenchymal CD163(+) macrophages/microglia, which had the capacity for antigen ingestion and presentation, might contribute to the resolution of inflammation in MS.     

Characterization and distribution of phagocytic macrophages in multiple sclerosis plaques

Populations of phagocytic cells in multiple sclerosis (MS) plaques were examined by quantitative immunocytochemical analysis of macrophage markers and myelin degradation products in serial cryostat sections from 10 cases of MS. Around lesions with ongoing demyelination expression of the Class II antigen HLA-DQ appeared to be a marker of microglial activation. Alpha l-antichymotrypsin + monocytes and myelin-laden macrophages expressing the later differentiation markers Ber-MAC3 and RFD7 were predominantly perivascular in location. On the basis of the distribution of oil red 0 (ORO)⁺ phagocytes and myelin loss, plaques were divided into groups representing different stages in lesion development. In early lesions (group 1), there was no apparent myelin loss around ORO⁺ macrophages although these cells contained material stained with antibodies against myelin basic protein (MBP) epitopes and neoepitopes. However, patchy myelin loss was detectable around the phagocytic macrophages uniformly distributed throughout group 2 plaques. ORO⁺ macrophages containing MBP peptides were confined to the hypercellular border of group 4 lesions, in which the demyelinating process may be recurrent.     

The nature of inflammatory components during demyelination in multiple sclerosis

Immune reactivity in the central nervous system (CNS) in multiple sclerosis (MS) can be fuelled by activated T lymphocytes sequestered in the brain and those entering systemically. The perivascular cuff of the inflammatory lesion consists predominantly of T cells and macrophages, while the hypercellular interface between normal and degenerating myelin is comprised mainly of macrophages and activated microglia. MHC class II⁺ cells are abundant in the hypercellular zone and expression of both the polymorphic and invariant chains of the molecule are expressed beyond the plaque edge in the white matter where the staining is restricted largely to microglia.

Under carefully controlled staining conditions expression of MHC class II can be demonstrated on microglia in control white matter. Thus the immunological privilege of the CNS does not appear to preclude constitutive expression of MHC antigens or prevent the traffic of activated lymphocytes into the brain parenchyma. However, the antigens priming the immune reaction in the CNS in MS and the role of antibodies in the demyelinating process remain a matter for speculation and the exact mechanisms of demyelination are as yet unresolved.     

On the role of peripheral macrophages during active experimental allergic encephalomyelitis (EAE)

Experimental allergic encephalitis (EAE) is an experimental autoimmune inflammatory condition of the central nervous system (CNS) that serves as a disease model for multiple sclerosis (MS). The primary effector mechanisms of the immune system leading to tissue destruction during EAE remain still controversial. T-cells, microglia, and macrophages infiltrating the brain parenchyma are suggested to be involved. To clarify the role of these cells during disease Lewis rats were immunised with different immunisation protocols: Immunisation with myelin basic protein (MBP) in complete Freunds adjuvant (CFA) containing high dose of mycobacterial components induced severe disease, whereas immunisation with low dose of mycobacterial components induced only mild disease. Severely and mildly diseased animals were analysed with respect to infiltration of T-cells, macrophages and upregulation of MHC class II molecules on microglia in the brain. All immunised rats showed high T-cell infiltration accompanied by microglia activation. The degree of disease and the infiltration of macrophages varied with dose of adjuvant. Lowering the dose of adjuvant prevented the development of disease but also the influx of peripheral macrophages into the brain without affecting the peripheral T-cell response to the autoantigen. Thus, appearance of (autoreactive) T-cells in the brain and microglia activation were probably not sufficient for development of disease. It can be concluded that peripheral macrophages play an essential or even key role in the pathogenesis of active EAE.     

Selective induction of cAMP phosphodiesterase PDE4B2 expression in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) in Lewis rats is the most widely used animal model for multiple sclerosis. Cyclic adenosine monophosphate (cAMP) has been associated with neuroinflammation. The aim of this study was to investigate the possible involvement of different cAMP-specific phosphodiesterase (PDE) isoenzymes by analyzing their expression in the brain of EAE rats. We found in the brain of EAE animals that there was a dramatic increase in the mRNA expression levels of the PDE4B isozyme detected around blood vessels from the spinal cord to the upper midbrain. There was a single splicing form of the 4 splice variants that are known for PDE4B: PDE4B2, which showed increased expression levels. This overexpression is localized around the blood vessels and parenchyma in infiltrating T cells and macrophages/microglia. These results support the role played by the activation of the PDE4B2 gene in the neuroinflammatory process in EAE rats.     

Characterization of microglia induced from mouse embryonic stem cells and their migration into the brain parenchyma

We derived microglia from mouse embryonic stem cells (ES cells) at very high density. Using the markers Mac1⁺/CD45^low and Mac1⁺/CD45^high to define microglia and macrophages, respectively, we show that Mac1⁺ cells are induced by GM-CSF stimulation following neuronal differentiation of mouse ES cells using a five-step method. CD45^low expression was high and CD45^high expression was low on induced cells. We used a density gradient method to obtain a large amount of microglia-like cells, approximately 90% of Mac1⁺ cells. Microglia-like cells expressed MHC class I, class II, CD40, CD80, CD86, and IFN-γR. The expression level of these molecules on microglia-like cells was barely enhanced by IFN-γ. Intravenously transferred GFP⁺ microglia derived from GFP⁺ ES cells selectively accumulated in brain but not in peripheral tissues such as spleen and lymph node. GFP⁺ cells were detected mainly in corpus callosum and hippocampus but were rarely seen in cerebral cortex, where Iba1, another marker of microglia, is primarily expressed. Furthermore, both GFP⁺ and Iba1⁺ cells exhibited a ramified morphology characteristic of mature microglia. These studies suggest that ES cell-derived microglia-like cells obtained using our protocol are functional and migrate selectively into the brain but not into peripheral tissues after intravenous transplantation.     

Interleukin-12 induces mild experimental allergic encephalomyelitis following local central nervous system injury in the Lewis rat

The major pathological feature in the central nervous system (CNS) following traumatic brain injury is activation of microglia both around and distant from the injury site. Intraperitoneal administration of interleukin-12 (IL-12) after brain injury resulted in a 7% weight loss, clinical signs of mild EAE and significant myelin basic protein (MBP)-specific splenic cell proliferation. The extent of pathology, in terms of the number of inflammatory perivascular cuffs and activation of microglia was greatest if IL-12 was administered immediately compared to a week following brain injury, whether at one or two sites. Specifically immunostaining for MHC class II and iNOS on macrophages and microglia, ICAM-1 on endothelial cells and macrophages was observed around the site of injury. A degree of myelin processing was apparent from immunostaining of MBP in inflammatory cells distant from the lesion. Inflammatory cuffs comprising macrophages, activated microglia, CD4⁺ T cells and iNOS⁺ cells were also detected distant to the injury site in the medulla and spinal cord of animals treated with IL-12. These results suggest that immune-mediated events in which IL-12 production is stimulated as for example viral infection, superimposed on a brain injury, could provide a trigger for a MS-like pathology.     

Effect of K+ channel blockers on the clinical course and histological features of experimental allergic encephalomyelitis

Introduction – Beneficial clinical effects of 4-aminopyridine (4-AP) in multiple sclerosis (MS) have been reported. The use of 4-AP in MS is based upon its ability to facilitate conduction in axons blocked by demyelination. This improvement is due to blocking of potassium (K⁺) channels in these fibres. Because K⁺ channels also play an important role in immune mechanisms successful treatment with K⁺ channel blockers in neuroimmunological diseases may have several causes. Therefore it seems important to study effects of K⁺ channel blockers in animal models of autoimmune disease. Material & methods – We studied the effects of 4-AP and quinidine on actively induced acute experimental allergic encephalomyelitis (EAE) in Lewis rats. Results – There was no effect on the incidence of the disease. The severity of the disease was also unchanged although the disease duration was slightly diminished in the treated groups. Immunohistological comparison between the animals of different groups showed no differences. Conclusion – We conclude that 4-AP and quinidine are not capable of significantly changing the clinical course of EAE.     

Dexamethasone suppresses infiltration of RhoA<Superscript>+</Superscript> cells into early lesions of rat traumatic brain injury

Inflammatory cell infiltration is a major part of secondary tissue damage in traumatic brain injury (TBI). RhoA is an important member of Rho GTPases and is involved in leukocyte migration. Inhibition of RhoA and its downstream target, Rho-associated coiled kinase (ROCK), has been proven to promote axon regeneration and function recovery following injury in the central nervous system (CNS). Previously, we showed that dexamethasone, an immunosuppressive corticosteroid, attenuated early expression of three molecules associated with microglia/macrophages activation following TBI in rats. Here, the effects of dexamethasone on the early expression of RhoA have been investigated in brains of TBI rats by immunohistochemistry. In brains of rats treated with TBI alone, significant RhoA⁺ cell accumulation was observed at 18 h post-injury and continuously increased during our observed time period. The accumulated RhoA⁺ cells were distributed to the areas of pannecrosis and selective neuronal loss. Most accumulated RhoA⁺ cells were identified as active microglia/macrophages by double-labelling. Dexamethasone (1 mg/kg body weight) was intraperitoneally injected on day 0 and 2 immediately following brain injury. Numbers of RhoA⁺ cells were significantly reduced on day 1 and 2 following administration of dexamethasone but returned to vehicle control level on day 4. However, dexamethasone treatment did not change the proportion of RhoA⁺ cells. These observations suggest that dexamethasone has only a transient effect on early leukocyte recruitment.     

Nogo-A and nogo receptor expression in demyelinating lesions of multiple sclerosis

A myelin-associated neurite outgrowth inhibitor, Nogo-A, plays a key role in inhibition of axonal regeneration following injury and ischemia in the central nervous system (CNS). Because axonal injury is a pathologic hallmark of multiple sclerosis (MS), we have investigated the expression of Nogo-A and its receptor NgR in four MS and 12 non-MS control brains by immunohistochemistry. Nogo-A expression was markedly upregulated in surviving oligodendrocytes at the edge of chronic active demyelinating lesions of MS and ischemic lesions of acute and old cerebral infarction, whereas NgR expression was greatly enhanced in reactive astrocytes and microglia/macrophages in these lesions when compared with their expression in the brains of neurologically normal controls. Nogo-A and NgR were also identified in a subpopulation of neurons. In contrast, Nogo-A was undetectable in reactive astrocytes and microglia/macrophages and NgR was not expressed on oligodendrocytes in any cases examined. Western blot analysis and double labeling immunocytochemistry identified the constitutive expression of NgR in cultured human astrocytes. These results suggest that Nogo-A expressed on oligodendrocytes might interact with NgR presented by reactive astrocytes and microglia/macrophages in active demyelinating lesions of MS, although biologic effects caused by Nogo-A/NgR interaction among glial cells remain unknown.     

Normal and reactive NG2+ glial cells are distinct from resting and activated microglia

We have previously used antibodies to the NG2 proteoglycan and the alpha receptor for platelet-derived growth factor (PDGF α receptor) to identify oligodendroglial progenitor cells in vivo and in vitro. It has recently become evident that the GD3 antigen, which has been widely used as a marker for oligodendrocyte progenitor cells, is also expressed by microglial cells. In this study we have examined the relationship between the NG2+/PDGF α receptor+ glial progenitor cells and microglial cells in normal developing and mature rat brain and in inflammatory lesions in mice with experimental autoimmune encephalomyelitis (EAE). Double-labeling of sections from normal rat brain using anti-NG2 antibodies and lectin from Griffonia simplicifolia (GSA I-B₄) or monoclonal antibody 4H1 indicated that there is no overlap between NG2+ glial progenitor cells and microglia in the parenchyma of the central nervous system. In EAE lesions, both NG2+ cells and microglia, identified by antibodies to F4/80 and CD45, displayed reactive changes characterized by increased cell number and staining intensity and shortening and thickening of cell processes. Both cell types were found surrounding perivascular infiltrates of lymphocytes. Double-labeling EAE sections for NG2 and F4/80 or CD45 failed to reveal cells that co-expressed both antigens, suggesting that reactive NG2+ cells are distinct from activated microglia. However, a close spatial relationship between NG2+ cells and microglia was observed in the normal brain and to a greater extent in EAE, where processes of an activated microglial cell were sometimes seen to encircle an NG2+ cell. These observations are indicative of a functional interaction between microglia and the NG2+ glial cells. J. Neurosci. Res. 48:299–312, 1997. © 1997 Wiley-Liss, Inc.     

CD14 expression by activated parenchymal microglia/macrophages and infiltrating monocytes following human traumatic brain injury

The immune response in the central nervous system (CNS) is under tight control of regulatory mechanisms, resulting in the establishment of immune privilege. CNS injury induces an acute inflammatory reaction, composed mainly of invading leukocytes and activated microglial cells/macrophages. The generation of this robust immune response requires binding of receptors such as CD14, a pattern recognition receptor of the immune system. CD14, a surface molecule of monocytic cells, is up-regulated after monocyte stimulation and is involved in cellular activation. To examine CD14 expression in human brain lesions we investigated sections of brains obtained at autopsy from 25 cases following closed traumatic brain injury (TBI) and 5 control brains by immunohistochemistry. Detection of CD14 in controls demonstrated constitutive expression by perivascular cells, but not in parenchymal microglial cells, equivalent to known expression pattern of ED2 in rats. Following TBI, numbers of CD14(+) cells in perivascular spaces and in the brain parenchyma increased in parallel within 1-2 days, both at the lesion and in adjacent perilesional areas. The number of CD14(+) cells in perivascular spaces and in the brain parenchyma reached maximum levels within 4-8 days and remained elevated until weeks after trauma. In contrast to activated parenchymal microglia/macrophages, resting parenchymal microglial cells lacked CD14. Thus, early CD14 expression constitutes an essential part of the acute inflammatory CNS response following trauma.     

Manganese and Epilepsy: Brain Glutamine Synthetase and Liver Arginase Activities in Genetically Epilepsy Prone and Chronically Seizured Rats

Summary: Low blood manganese (Mn²⁺) concentration is associated with epilepsy in humans and rats. The low Mn²⁺ concentration is attributed by some investigators to the seizure activity associated with the epilepsy, whereas others propose that the low Mn²⁺ concentration may be secondary to genetic mechanisms underlying the epilepsy. To begin to differentiate between these possibilities, Mn²⁺-binding enzymes of liver and brain (i.e., arginase and glutamine synthetase, respectively) were assayed in rats exposed to chronically induced seizures and in genetically epilepsy-prone rats (GEPRs). Chronic seizures caused a decrease in whole blood Mn²⁺ levels but did not affect brain Mn²⁺ concentrations. Arginase activity was increased in livers of rats with chronic seizure as compared with controls, but this difference was eliminated when Mn²⁺ was added to the assay. Brain glutamine synthetase activity was unaffected by chronic seizures, but the activity of this enzyme was significantly lower in GEPR brain than in control brain. Liver arginase activity tended to be lower in GEPRs, although the difference was not statistically significant. These data indicate that seizures affect liver arginase activity through changes in liver Mn²⁺ concentration, but GEPRs show abnormalities in Mn²⁺ -dependent enzymes apparently independent of seizure activity.     

Resident microglia and hematogenous macrophages as phagocytes in adoptively transferred experimental autoimmune transferred experimental autoimmune encephalomyelitis: An investigation using rat radiation bone marrow chimeras

Hematogenous macrophages are known to be involved in the induction of tissue damage in the central nervous system (CNS) as well as of clinical symptoms in experimental autoimmune encephalomyelitis (EAE). Although resident microglia can become phagocytic under certain circumstances, little is known about the role of these cells in brain inflammation in vivo. We thus studied EAE in the model of radiation bone marrow chimeras that allows us to distinguish donor-derived hematogenous cells from resident effector cells. Inflammation in the CNS was qualitatively and quantitatively similar in chimeras compared to fully histocompatible Lewis rats. Although activated resident microglial cells were outnumbered four-to sevenfold in EAE lesions by hematogenous macrophages, the number of resident microglia with ingested myelin was equal to that of macrophages containing myelin debris. Phagocytic resident microglia, expressing the macrophage activation marker ED1, showed ramified as well as amoeboid morphology. From our studies the following conclusions can be drawn. First, a considerable proportion of resident microglia upregulated ED1. Second, resident microglia provide a small but substantial source of brain macrophages in EAE as compared to the large influx of macrophages. Third, our results suggest that macroglia, due to their strategic position within the CNS, are more effective in removal of myelin debris compared to hematogenous macrophages. © 1995 Wiley-Liss, Inc.     

Nitric-oxide-dependent and independent mechanisms of protection from CNS inflammation during Th1-mediated autoimmunity: evidence from EAE in iNOS KO mice

Experimental autoimmune encephalomyelitis (EAE) disease was accelerated iNOS-deficient (KO) mice: coinciding with greatly increased numbers of Ag-specific Th1 cells in the periphery that appeared to rapidly shift from the spleen to the CNS during onset of disease symptoms. iNOS KO mice had significantly increased Th1 cells in the CNS versus wild-type mice. Apoptosis of CNS-infiltrating CD4⁺ T cells was impaired in iNOS KO mice at peak of disease; consequently, these mice had more CNS-infiltrating CD4⁺ T cells. Subsequently, iNOS KO mice up-regulated apoptosis of CNS-CD4⁺ T cells. During chronic EAE, CNS macrophages were greatly decreased, suggesting elimination of CNS-infiltrating CD4⁺ T cells and activated macrophages by iNOS-independent mechanisms. INOS is not only required for apoptosis of CNS-CD4⁺ T cells but also prevents overexpansion of autoreactive Th1 cells in the periphery and the CNS.     

The immunopathology of adoptively transferred experimental allergic encephalomyelitis (EAE) in Lewis rats. Part 1. Immunohistochemical examination of developing lesions of EAE

In order to examine developing lesions of experimental allergic encephalomyelitis (EAE) at the preclinical stage, adoptive transfer of EAE was achieved in Lewis rats using spleen cells obtained from rats previously immunized with 50 micrograms of guinea pig myelin basic protein (MBP) in complete Freund's adjuvant. After cell transfer, all the recipient rats developed severe paraparesis with minimal variation in the onset of clinical signs, which facilitated immunohistochemical examination of developing lesions of EAE in asymptomatic animals. The initial pathological finding detected in this system was an increased number of inflammatory cells (both OX19+ and OX8+ T cells and macrophages) in the subarachnoid space (SAS) which was observed on day 3 post-transfer (PT) when the recipient animals showed no neurological abnormalities. By day 4 PT, inflammatory cells were detected in the Virchow-Robin space of vessels which were continuous to the SAS. Perivascular lymphocytic infiltration was scarcely detected in the gray matter. On day 5 PT, the rats showed severe paraparesis. Inflammatory foci increased in number and were detected in both the white and gray matter. Diffuse parenchymal T-lymphocyte infiltration was also recognized at this stage. From day 6 PT onwards, inflammatory cells decreased gradually. On day 8 PT, all the rats recovered from EAE and few inflammatory cells were detected in the parenchyma and SAS. Immunohistochemical examination of T-cell subsets and Ia antigens revealed that the number of OX19+ cells was greater than that of OX8+ cells in the parenchyma and SAS at all stages examined, the distribution of OX19+ cells was almost the same as that of OX8+ cells, OX8+ cells decreased in number before clinical signs subsided, and that after the infiltration of T cells into the parenchyma, cells with dendritic morphology (microglia) expressed Ia antigens in close association with the infiltrating T cells. Adoptive transfer of MBP-sensitized spleen cells provides constant induction of EAE with minimal variation in clinical onset and severity, thus being a useful model for the examination of early events of EAE.     

EAE大鼠SFO中NF-kB、HO-1蛋白表达的相关性

目的探讨实验性自身免疫性脑脊髓炎(EAE)时,大鼠核转录因子-κB(NF-κB)、血红素氧合酶-1(HO-1)在穹隆下器(SFO)中的变化,为证明SFO是感受外周信息物质的早期位点之一提供依据。方法分别用HE染色和免疫组化双色标记技术,观察了完全福氏佐剂+豚鼠脊髓匀浆(CFA-GPSCH)诱导大鼠EAE1d、7d、14d、21d时SFO部位HO-1、NF-κB蛋白表达的动态变化,并分析了与症状之间的相关性。结果对照组大鼠脑仅有少量HO-1、NF-κB蛋白表达;实验组大鼠诱导EAE后,伴随着大鼠EAE症状及脑组织病理损伤的出现和进行性加重,其HO-1、NF-κB蛋白表达量逐渐增高;在诱导后1d,SFO部位即出现HO-1/NF-κB阳性细胞表达,而其他脑区变化不明显;7d时进一步增多;14d时,HO-1+/NF-κB+细胞至高峰,主要位于脉络丛、穹隆下器、血管"套袖样"病灶的周围,与EAE病变部位一致,此时大鼠EAE病情最重、体重减轻最显著、脑组织病理改变最明显;21d时脑组织HO-1+/NF-κB+细胞逐渐下降,大鼠EAE症状也逐渐恢复。应用NF-κB特异性抑制剂PDTC后,HO-1+/NF-κB表达明显减少,大鼠EAE症状和脑组织病变明显减轻,说明NF-κB水平的高低可以调节HO-1的活性及其生物学作用。结论SFO可能是外周信息物质向中枢神经系统传递的重要而早期的位点之一。     

Temporal expression of osteopontin and CD44 in rat brains with experimental cryolesions

Expression of osteopontin and CD44 in the brain was studied after cryolesioning to understand how osteopontin and its receptor, CD44, are involved in processes in the brains of rats with cryolesions. Western blot analysis showed that osteopontin increased significantly at days 4 and 7 post-injury and declined slightly thereafter in cryolesioned brains in comparison with levels in sham-operated controls. An immunohistochemical study localized osteopontin in activated microglia/macrophages in the core lesions, where the majority of macrophages proliferate. Osteopontin was also detected temporarily in some neurons and a few astrocytes in the lesion periphery on days 4 and 7 post-injury, but the immunoreactivity in macrophages, neurons, and astrocytes disappeared by day 14 post-injury. There was some CD44, a receptor for osteopontin, in the brain cells of sham-operated rats. After injury, intense CD44 immunostaining was seen in the majority of macrophages and in reactive astrocytes, but not in neurons, in the ipsilateral lesions after day 4 post-injury, and this immunoreactivity remained on day 14 post-injury. These findings suggest that activated microglia/macrophages and some neurons are major sources of osteopontin during the early stage of brain damage induced by a cryolesion and that osteopontin interacts with CD44 expressed on astrocytes and activated microglia/macrophages in the damaged cerebral cortex, possibly mediating cell migration after cryolesioning in the rat brain.     

Activation of mitogen-activated protein kinases in experimental autoimmune encephalomyelitis

The expression of mitogen-activated protein (MAP) kinases, including extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal protein kinase (JNK), and p38, was analyzed in experimental autoimmune encephalomyelitis (EAE) in rats.

Western blot analysis showed that the three MAP kinases (phosphorylated ERK (p-ERK), p-JNK, and p-p38) were increased significantly in the spinal cords of rats with EAE at the peak stage as compared with the levels in controls (p<0.05), and both p-ERK and p-JNK declined slightly in the recovery stage of EAE. Immunohistochemistry showed that p-ERK was constitutively expressed in brain cells, including astroglial cells, and showed enhanced immunoreactivity in those cells in EAE, while some T cells and macrophages were weakly immunopositive for p-ERK in EAE lesions. Both p-JNK and p-p38 were intensely immunostained in T cells in EAE lesions, while a few glial cells and astrocytes were weakly positive for both.

Taking all these facts into consideration, we postulate that increased expression of the phosphorylated form of each MAP kinase plays an important role in the initiation of acute monophasic EAE. Differential expression of three MAP kinases was discerned in an animal model of human autoimmune central nervous system diseases, including multiple sclerosis.     

The distribution of myelin basic protein in central nervous system lesions of multiple sclerosis and acute experimental allergic encephalomyelitis.

To obtain more information about early events in central nervous system myelin injury in multiple sclerosis (MS), a comparative study was conducted of the distribution of myelin basic protein (BP) in tissue lesions of both MS and experimental allergic encephalomyelitis (EAE). Sixteen postmortem specimens containing lesions from 4 persons with MS and the brains of 14 guinea pigs with acute EAE induced with BP were studied. Cryostat sections of quick-frozen material were fixed, treated with rabbit antibody to BP, and processed by immunoperoxidase techniques. The reaction of antibody to BP was reduced or absent in MS lesions but normal in uninvolved surrounding tissue. Alterations in BP generally paralleled changes in staining of myelin by histological methods. Marked diminution of reactivity with anti-BP occurred in early lesions of MS and extended far beyond any identifiable inflammatory elements. In both parenchyma and perivascular areas, lipid-laden macrophages in MS plaques frequently contained BP material in addition to a variable amount of endogenous peroxidatic activity. Compared with MS, BP was relatively well preserved in brains of guinea pigs with EAE. At the light microscopy level, normal-appearing patterns of BP existed adjacent to the perivascular cellular infiltrates, and macrophages containing BP material were rare. The results of this study suggest differences between MS and acute EAE in both removal of BP from the central nervous system and its subsequent disposal.