Effect of anti-interferon-γ monoclonal antibody treatment on the development of experimental allergic encephalomyelitis in resistant mouse strains

Immunization with myelin basic protein (MBP) in complete Freund's adjuvant failed to induce experimental allergic encephalomyelitis (EAE) in six resistant mouse strains studied: A/J, BALB/c C3H/HeJ, AKR, NZW and DBA/2. However, treatment of challenged mice with anti-interferon-γ (IFN-γ) monoclonal antibody (mAb) induced severe EAE in mice of all strains except AKR. Furthermore, anti-IFN-γ mAb treatment led to increased disease incidence and severity in BALB/c mice challenged with the MBP peptide_87–103, known to be encephalitogenic for the susceptible SJL strain. In three strains tested, anti-IFN-γ mAb enhanced passively induced EAE in the A/J and C3H/HeJ but not in the BAlB/c mice. All mice with clinically overt EAE had widespread histological lesions characterized by mononuclear cell infiltrates and focal demyelination. The results indicate that resistant strains are genetically capable of developing EAE, and that IFN-γ can contribute to disease resistance.     

Induction of synchronized relapses in SJL/J mice with chronic relapsing experimental allergic encephalomyelitis

Summary Chronic relapsing experimental allergic encephalomyelitis (CR-EAE) was induced in SJL/J mice by two injections of encephalitogenic emulsion. The majority of mice developed multiple relapses from day 22 to day 367 post injection. To induce synchronized relapses a third injection of the encephalitogenic emulsion was given. Almost all mice that received the third injection developed an acute, synchronized relapse with severe clinical signs within 7 to 11 days. Histologically, there was no difference between the lesions in the spontaneous versus the precipitated relapse. CR-EAE in SJL/J mice modified with the third injection offers an advantage of a reproducible and well-timed acute relapse, which allows precise dissection of the immunological events governing spontaneous relapses in chronic EAE.     

Effect of anti-interferon-gamma and anti-interleukin-2 monoclonal antibody treatment on the development of actively and passively induced experimental allergic encephalomyelitis in the SJL/J mouse.

SJL/J mice challenged with myelin basic protein (MBP) in complete Freund's adjuvant (CFA) developed only mild chronic-relapsing experimental allergic encephalomyelitis (EAE) with very low incidence. However, treatment of challenged mice with anti-interferon-gamma (IFN-gamma) monoclonal antibody (mAb) determined severe disease in all cases. Similarly, in passive EAE, the addition of anti-IFN-gamma to the in vitro MBP-activated cells at the time of transfer led to significant disease exacerbation in all recipients. The disease enhancing effect was observed only when the mAb was given at the time of active challenge or of passive transfer, but not at later times. Anti-interleukin-2 (IL-2) antibody had only a marginal effect in the active induction, but drastically reduced the manifestations of passive EAE, even when mixed with a disease-enhancing dose of anti-IFN-gamma. These findings support the notion that IL-2 is required for disease induction whereas IFN-gamma plays a disease-limiting role early in the development of EAE.     

Treatment of PL/J mice with the superantigen, staphylococcal enterotoxin B, prevents development of experimental allergic encephalomyelitis

Experimental allergic encephalomyelitis (EAE), an antigen induced autoimmune disease, is mediated by Vβ8⁺ CD4⁺ T cells in PL/J mice after injection with the autoantigen, myelin basic protein (MBP). Recently the superantigen, staphylococcal enterotoxin B (SEB), has been shown to peripherally anergize and delete T cells in a Vβ specific manner. By treatment of PL/J mice with SEB, we have been able to protect PL/J mice from the development of EAE. Two-color FACS analysis of the spleens of SEB treated mice showed depletion of Vβ8⁺ CD4⁺ T cells. Consistent with this observation, spleen cells of SEB treated mice that did not show signs of EAE could not be stimulated in vitro with SEB but did respond to SEA. Thus, Vβ specific superantigens may prove to be a preventive therapy for autoimmune diseases mediated by Vβ specific T lymphocytes.     

Treatment of clinical experimental allergic encephalomyelitis in the rat using fragments and combinations of monoclonal antibodies

We reported previously that two different anti-CD4 monoclonal antibodies (W3/25, MRC OX35) were effective in treating experimental allergic encephalomyelitis in the Lewis rat whereas anti-I-A antibody was ineffective. Further studies with other monoclonal antibodies and fragments have now been performed. Anti-I-E antibody was ineffective in shortening the disease duration even when used in combination with anti-I-A antibody. Anti-CD2 (T11) antibody was marginally effective, shortening the duration of disease by only one day on the average. Combination of anti-CD4 antibody with anti-CD2 antibody did not improve the recovery time over the use of anti-CD4 antibody alone. On the other hand, the F (ab')2 fragment of the anti-CD4 antibody was as effective in the treatment of disease as the intact antibody molecule, indicating that it was sufficient to block the CD4 molecules on the cell surface of the EAE effector cells in order to affect the disease course.     

In vivo and in vitro studies of the prevention of proteolipid apoprotein-induced murine experimental allergic encephalomyelitis by monoclonal antibody against L3T4

The suppressive effect of anti-L3T4 monoclonal antibody (mAb) on murine experimental allergic encephalomyelitis (EAE) induced by sensitization with proteolipid apoprotein (PLP) was examined in vivo and in vitro. This mAb inhibited the antigen-specific proliferation of the encephalitogenic T cell lines but did not block the mitogen-mediated response. Serial injections of the mAb during the pre-effector phase of EAE markedly suppressed the development and relapse of the disease but this treatment initiated after appearance of clinical signs was not effective. In treated animals, L3T4+ T cells in the spleen were profoundly decreased and the antigen-specific proliferative response of spleen cells was completely suppressed. Moreover, adoptive transfer of spleen cells from the treated mice induced resistance against EAE induction in the recipients. However, no obvious evidence for antigen-specific suppressor cells was found in vitro in the L3T4- populations of spleen cells from treated mice.     

The mechanism of inhibition of experimental allergic encephalomyelitis in the rat by monoclonal antibody against CD4

Lewis rats with actively induced or passively transferred experimental allergic encephalomyelitis (EAE) were treated with a monoclonal antibody (MAb) which binds to the CD4 antigen of rat helper/inducer T cells. Actively immunized animals treated at the first onset of clinical signs experienced only a mild form of the disease and rapidly recovered while the majority of those treated prophylactically never showed clinical signs of EAE. Passively transferred EAE was also completely inhibited with anti-CD4 MAb. In treated animals which exhibited only mild clinical signs of EAE, spinal cord and cerebellar leukocyte infiltrates were quite similar to those in untreated rats but where anti-CD4 MAb treatment completely prevented clinical EAE, histological signs were minimal or absent. Like Lewis rats which have recovered naturally from EAE, those treated with anti-CD4 MAb were both resistant to a secondary challenge with myelin basic protein and harboured potential encephalitogenic cells which were capable of transferring disease to recipient rats. Disease in these recipients was, however, of much greater severity than that experienced by animals receiving cells from naturally recovered (untreated) donors. These data demonstrate that administration of anti-CD4 MAb to rats can prevent EAE by a mechanism which does not ablate the encephalitogenic CD4+ cells or prevent the development of resistance to EAE but which may inhibit the disease by preventing the function of already activated effector cells.     

Recombinant human β-galactoside binding lectin suppresses clinical and histological signs of experimental autoimmune encephalomyelitis

Human placental tissue contains regulatory molecules that may prevent allo-sensitization. Recently, a 14 kDa β-galactoside binding protein with demonstrated immunoregulatory properties has been cloned using cDNA from human placenta and expressed in Escherichia coli. The present study assesses the ability of this recombinant immunomodulatory lectin (rIML-1), to prevent experimental autoimmune encephalomyelitis (EAE), a paralytic T cell-mediated disease directed against myelin basic protein (BP). Injection or rIML-1 into Lewis rats inhibited the induction of both clinical and histological signs of EAE, apparently by blocking sensitization of encephalitogenic BP-specific T cells and inducing BP-dependent suppressor cells. Because it is neither immunogenic nor toxic, rIML-1 may have application in humans, and would have distinct advantages over unselective cytotoxic immunosuppressive agents used currently in the treatment of autoimmune diseases and transplantation.     

The effect of TCR Vβ8 peptide protection and therapy on T cell populations isolated from the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis

Vaccination or treatment of Lewis rats with TCR Vβ8 peptides can prevent or reverse the clinical signs of experimental autoimmune encephalomyelitis (EAE) which is mediated predominantly by Vβ8.2⁺ CD4⁺/CD45R lo T cells. However, rats protected or treated with Vβ8 peptides still developed histological lesions in the spinal cord (SC), even though they remained clinical well. We sought to discern phenotypic changes characteristic of these SC infiltrating lymphocytes. In particular, we focused on whether the immunoregulatory mechanism induced by TCR peptides caused a reduction of Vβ8.2⁺ T cells, or induced changes in CD45R lo or hi/CD4⁺ subpopulations that have been associated respectively with EAE induction or recovery. In the Vβ8 peptide vaccinated rats there was a dramatic decrease in the number of Vβ8.2⁺ T cells isolated from the SC early in disease. During the recovery phase, however, the number of Vβ8.2⁺ SC T cells was similar in protected and control groups; in contrast, there was a striking reduction in the number and size of CD45R hi/CD4⁺ T cells in the protected animals. In rats treated with Vβ8.2 peptide, no changes were observed in the number of SC Vβ8.2⁺ T cells or expression of Vβ8.2 message, but similar to vaccinated rats, there was a marked decrease in the number of CD45R hi/CD4⁺ T cells. These data suggest that vaccination with TCR peptides prevented the initial influx of encephalitogenic Vβ8.2⁺ T cells into the central nervous system (CNS), whereas treatment appeared to inactivate Vβ8.2⁺ T cells already present in the CNS. In both cases, TCR peptide-induced inhibition of the encephalitogenic T cells apparently preempted the need for CD45R hi/CD4⁺ T cells that may normally be necessary to resolve the disease.     

Nasal administration of myelin basic protein prevents relapsing experimental autoimmune encephalomyelitis in DA rats by activating regulatory cells expressing IL-4 and TGF-β mRNA

This study explores nasal administration of myelin basic protein (MBP) as a potential means of inducing tolerance to relapsing experimental autoimmune encephalomyelitis (PR-EAE), an experimental multiple sclerosis (MS) model that was induced in DA rats by immunization with rat spinal cord homogenate and incomplete Freund's adjuvant. DA rats received a total dosage of 0, 6, 60, 600 μg/rat of bovine MBP on ten consecutive days prior to immunization. EAE with typical course was observed in control rats receiving only PBS nasally, and in rats receiving 6 μg/rat of MBP. Rats receiving 60 μg/rat of MBP developed acute EAE but no relapse during 60 days of observation post immunization (p.i.). Only one of eight rats receiving 600 μg/rat of MBP developed slight, transient EAE. This protection was confirmed at the histology level and was associated with decreased levels of MBP-reactive IFN-γ secreting Th1-like spleen cells on day 13 and 60 p.i. Rats receiving 60 and 600 μg/rat of MBP showed decreased serum anti-MBP IgG2b antibody levels on day 60 p.i., and rats receiving 600 μg/rat of MBP had marginally increased anti-MBP IgG1 antibody levels in serum compared to control EAE rats. Cytokine mRNA profiles in central nervous system (CNS) and spleen mononuclear cells were evaluated. Dose-dependent reduction of TNF- mRNA expression were observed both in CNS and in splenocytes. Increased IL-4 and TGF-β mRNA expression were observed in CNS of low (6 μg/rat) and median (60 μg/rat) dose of MBP tolerized rats and in splenocytes of rats tolerized with 600 μg/rat of MBP. We conclude that nasal administration of MBP in DA rat prevents EAE induced by immunization with whole rat spinal cord homogenate that, besides MBP, contains multiple antigenic myelin proteins. A mechanism involving MBP-reactive regulatory cells expressing IL-4 and TGF-β mRNA acts as part in the induction of this tolerance.     

Effect of transforming growth factor-β1 and -β2 on Schwann cell proliferation on neurites

Mechanisms regulating Schwann cell proliferation during development are unclear. Schwann cell division is known to be driven by an unidentified mitogen present on the surface of axons, but it is not known whether other molecules play a role in regulating this proliferation. Transforming growth factor-beta (TGF-β) which is found in the developing peripheral nervous system (PNS) and is mitogenic for neuron-free Schwann cells in vitro could be involved. We have investigated the effects of TGF-β 1, TGF-β 2 and antibodies to TGF-β and TGF-β 2 on axon driven Schwann cell proliferation. Rat embryonic dorsal root ganglion neurons (DRG) neurons and Schwann cells from the sciatic nerve were isolated, purified and recombined in vitro. Confirming earlier reports by others, we observed that TGF-β 1 and TGF-β 2 added to the culture medium stimulated the proliferation of Schwann cells in the absence of neurons. However, when added to neuron-Schwann cell co-cultures, TGFβ caused a variable response ranging from no effect to moderate inhibition of Schwann cell proliferation in different experiments. A stimulation of Schwann cell proliferation by TGFβ was never observed in neuron-Schwann cell co-cultures. Antibodies to TGF-β and TGF-β 2 did not influence axon driven Schwann cell proliferation. To further determine the role of TGF-β in Schwann cell proliferation and myelination, we studied Schwann cell proliferation in cultures from mice in which the TGF-β 1 gene was delected by homologous recombination. Neuron-Schwann cell cultures from wild-type, heterozygous and homozygous mice were used. No differences were observed in either Schwann cell proliferation or myelination between cultures obtained from homozygous mutants and their heterozygous and wild-type controls. These findings suggest that TGF-β does not function as a part of the mitogenic mechanism presented by neurons to Schwann cells, but that the presence of active TGFβ in the cellular environment might regulate the degree of proliferation induced by neuronal contact. Copy 1995 Wiley-Liss, Inc.     

Interferon γ, interleukin 4 and transforming growth factor β in experimental autoimmune encephalomyelitis in lewis rats: Dynamics of cellular mrna expression in the central nervous system and lymphoid cells

The potential role of certain important immunoregulatory and effector cytokines in autoimmune neuroinflammation have been studied. We have examined the expression of mRNA, with in situ hybridization, of interferon -γ (IFN-γ), interleukin 4 (IL-4) and transforming growth factor β (TGF-β) both in sections of spinal cords and the antigen-induced expression of these cytokines by lymphoid cells after stimulation with a dominant encephalitogenic peptide of MBP (MBP 63–88) during the course of actively induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats. In spinal cords, the target organ in EAE, cells expressing mRNA for IFN-γ, first appeared at the onset of clinical signs, i.e., day 10 postimmunization (p.i.), peaked at the height of disease (day 13 p.i.), and then gradually decreased concomitant with recovery. Very few IL-4 mRNA-expressing cells appeared in the spinal cord with no clear relation to clinical signs or histopathology. In contrast, expression of mRNA for TGF-β did not increase until day 13 p.i., at height of the disease, shortly preceding recovery. These data are consistent with a disease upregulating role of IFN-γ, while TGF-β may act to limit central nervous system (CNS) inflammation. In lymphoid organs, primed MBP 63–88 reactive T cells showed an interesting time-dependent evolution of their cytokine production in vitro. Thus, early after immunization there was a conspicuous MBP 63–88-induced production of both IFN-γ and IL-4. Such cells may act in the initiation and promotion of the disease. Later, in the recovery phase, MBP 63–88 induced lymphoid cells to TGF-β production. Thus, an autoantigen-specific production of TGF-β occurred during EAE and hypothetically such a mechanism may serve to downregulate aggressive autoimmunity systemically. © 1995 Wiley-Liss, Inc.     

Relative susceptibility of SJL/J and B10.S mice to experimental allergic encephalomyelitis (EAE) is determined by the ability of prethymic cells in bone marrow to develop into EAE effector T cells

SJL/J mice are highly susceptible to actively induced experimental allergic encephalomyelitis (EAE), whereas B10.S mice are resistant. However, both strains share the H-2^s haplotype. We have previously shown that the relative susceptibility of SJL/J and B10.S mice to acute EAE correlates, respectively, with high and low responsiveness to myelin basic protein (MBP), as determined by cloning and limiting dilution analysis of in vitro T cell proliferation. Here, we have investigated the ability of SJL/J and B10.S mice to generate EAE-effector T cells in vivo. We have developed a new mouse strain, B10.S Thy 1.1, that differs at the Thy 1 locus from SJL/J and B10.S mice (both Thy 1.2) but has the same MHC and resistance pattern to EAE as do B10.S mice. Using radiation bone marrow chimeras formed between SJL/J and B10.S Thy 1.1 mice, we have shown that a population of radiosensitive prethymic cells in SJL/J bone marrow has an intrinsic potential to generate EAE-effector T cells, whereas that in B10.S Thy 1.1 bone marrow does not. This lack of detectable EAE effector cells in B10.S Thy 1.1 mice does not appear to be due to the generation of suppressor T cells or to a detect in antigen-presenting cells. Moreover, the potential of SJL/J bone marrow to generate EAE-effector T cells is not inhibited by the concomitant presence of B10.S Thy 1.1 bone marrow cells, thymocytes or dendritic cells in mixed chimeras. Hence, the relative susceptibility of SJL/J and B10.S mice to EAE appears to be directly related to the respective responder status of their T cells to MBP, as evidenced by their ability (or inability) to generate EAE-effector T cells. This high and low responder status appears in turn to be linked to non-MHC background genes, although this has not been established formally.     

Changes in expressions of proinflammatory cytokines IL-1β, TNF-α and IL-6 in the brain of senescence accelerated mouse (SAM) P8

The senescence-accelerated mouse (SAM) is known to be a murine model for accelerated aging. The SAMP8 strain shows age-related deterioration of learning and memory at an earlier age than control mice (SAMR1). In the present study, we investigated the changes in expressions of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the brain of SAMP8. In the hippocampus of 10 months old SAMP8, the expression of IL-1 mRNA was significantly elevated in comparison with that of SAMR1. In both strains of SAMs, increases in IL-1β protein in the brain were observed at 10 months of age compared with 2 and 5 months. The only differences found between the strain in protein levels were at 10 months and were elevations in IL-1β in the hippocampus and hypothalamus, and in TNF-α and IL-6 in the cerebral cortex and the hippocampus in SAMP8 as compared with SAMR1. However, lipopolysaccharide-induced increases in the expression of these cytokines in brain did not differ between SAMP8 and SAMR1. Increases in expression of proinflammatory cytokines in the brain may be involved in the age-related neural dysfunction and/or learning deficiency in SAMP8.     

α2‐Adrenergic drugs modulate the binding of [18F]fallypride to dopamine D2/3 receptors in striatum of living mouse

Aim. To test for α₂ adrenergic modulation of dopamine D_2/3 receptor availability in striatum of living mice using the high‐affinity ligand [¹⁸F]fallypride and microPET. Methods. Groups of anesthetized mice were pretreated with saline, the α₂‐agonist clonidine (1 mg/kg), and the α₂‐antagonists RX821002 (1 mg/kg) and yohimbine (1 mg/kg). Dynamic microPET recordings lasting 120 min were then initiated upon i.v. tracer injection of [¹⁸F]fallypride. Parametric maps of [¹⁸F]fallypride binding potential (BP_ND) were calculated using the Logan method, with cerebellum serving as the reference region. Results. Mean striatal [¹⁸F]fallypride BP_ND was 10.6 ± 1.7 in the saline control animals, 8.9 ± 1.7 (?16%; P < 0.05) in the RX821002 group, 8.3 ± 2.6 (?22%; P < 0.05) in the yohimbine group and 10.3 ± 2.2 (n.s.) in the clonidine group. Conclusions. These findings are consistent with a tonic inhibition of dopamine release by α₂ adrenergic receptors, such that α₂ blockade increased the competition from endogenous dopamine at D_2/3 receptors, thus reducing the [¹⁸F]fallypride BP_ND by about 20%. Absent effects of clonidine suggest a ceiling effect in the tonic inhibition of dopamine release. This in vivo PET evidence for α₂/dopaminergic interaction may be relevant to putative actions of atypical antipsychotic medications via adrenergic receptors. Synapse, 2010. © 2010 Wiley‐Liss, Inc.     

Inhibition of phosphoinositide hydrolysis by the novel neurotoxinβ-N-oxalyl-l-α, β-diaminopropionic acid (l-BOAA)

Inhibition by a recently isolated neurotoxic amino acid, β-N-oxalyl-l-α, β-diaminopropionic acid, (l-BOAA), of stimulated phosphoinositide hydrolysis was studied in rat brain cerebral cortical slices.l-BOAA inhibited the norepinephrine-stimulated response but did not affect hydrolysis induced by 55 mM K⁺, carbachol in the presence of 20 mM K⁺. The inhibition was concentration-dependent with anIC₅₀ of 300 μM. This inhibition was insensitive to the excitatory amino acid antagonists, γ-glutamylglycine, glutamic acid diethyl ether, CNQX, AP-4, AP-7, or kynurenate. Thus, we propose that thel-BOAA-mediated inhibition of the norepinephrine-stimulated response was due to an interaction at a novel site, which may also be sensitive to quisqualate (see discussion). The mechanism of the inhibition is still unknown but was not prevented by inhibition of phospholipase A₂ or polyamine synthesis and it was not affected by blockade of chloride channels. However, the presence of 20 mM K⁺ completely blocked the inhibitory effect ofl-BOAA on norepinephrine-stimulated phosphoinositide hydrolysis.     

Selective interruption of axonal transport of neurofilament proteins in the visual system by β,β′-iminodipropionitrile (IDPN) intoxication

β,β′-iminodipropionitrile (IDPN) is an agent that produces a marked impairment in the transport of neurofilaments. Its effect on other slowly transported cytoskeletal components sucas tubulin and actin is variable. Previous studies have evaluated transport of neurofilaments after IDPN intoxication in a neurofilament-ricsystem (sciatic motor nerves) and in a system devoid of neurofilaments (axons of the dorsal motor nucleus of the vagus). In the former, IDPN impairs the transport of tubulin and actin but to a lesser degree than it does neurofilament proteins. In the latter, tubulin and actin transport were not impaired, and neurofilament proteins were not present. In this study we evaluated the transport of the cytoskeletal components in a system witan intermediate amount of neurofilaments (the visual system). In the visual system, there is a selective and marked (50%) impairment in the transport of neurofilaments witno impairment in transport of tubulin or microtubule-associated proteins (tau group). We conclude that these different patterns of impairment in transport reflect the differences in pre-intoxication neurofilament content of the nerves examined, the effect of IDPN on the transport of the other components of slow transport being secondary to the presence of stagnated neurofilaments. This model also suggests that transport of neurofilaments can be selectively impaired without producing an effect on other major slow transport components.     

Structural correlates of physiological abnormalities in β,β′-Iminodipropionitrile

β,β′-Iminodipropionitrile (IDPN) produces neurofilamentous giant axonal swellings in proximal internodes of large myelinated axons. Secondary demyelinative changes result from the production of these axonal enlargments. Electrophysiological studies have demonstrated profound alterations in the electrical properties of motor neurons (MN) within the spinal cord. On the basis of intracellular recordings, it has been suggested that electrical contacts may exist between swollen axons and neighboring MN. In addition, the possibility remained that synaptic contacts develop on demyelinated axonal swellings. In the present study, we report the lack of either synapses on demyelinated axonal swellings or direct electrical contacts between neighboring MN. Axonal swellings are surrounded by attenuated processes of glial cells (probably fibrillary astrocytes), a finding discussed in terms of its possible role in the production of ephaptic transmission. There was considerable variation in the degree of axonal enlargements and in the extent of secondary (passive and active) demyelination. It is suggested that these morphological changes may represent structural correlates of some electrophysiological alterations observed in IDPN neuropathy.     

Alzheimer's β-amyloid peptides induce inflammatory cascade in human vascular cells: the roles of cytokines and CD40

Accumulating evidence suggests that β-amyloid (Aβ)-induced inflammatory reactions may partially drive the pathogenesis of Alzheimer's disease (AD). Recent data also implicate similar inflammatory processes in cerebral amyloid angiopathy (CAA). To evaluate the roles of Aβ in the inflammatory processes in vascular tissues, we have tested the ability of Aβ to trigger inflammatory responses in cultured human vascular cells. We found that stimulation with Aβ dose-dependently increased the expression of CD40, and secretion of interferon-γ (IFN-γ) and interleukin-1β (IL-1β) in endothelial cells. Aβ also induced expression of IFN-γ receptor (IFN-γR) both in endothelial and smooth muscle cells. Characterization of the Aβ-induced inflammatory responses in the vascular cells showed that the ligation of CD40 further increased cytokine production and/or the expression of IFN-γR. Moreover, IL-1β and IFN-γ synergistically increased the Aβ-induced expression of CD40 and IFN-γR. We have recently found that Aβ induces expression of adhesion molecules, and that cytokine production and interaction of CD40–CD40 ligand (CD40L) further increase the Aβ-induced expression of adhesion molecules in these same cells. These results suggest that Aβ can function as an inflammatory stimulator to activate vascular cells and induces an auto-amplified inflammatory molecular cascade, through interactions among adhesion molecules, CD40–CD40L and cytokines. Additionally, Aβ_1–42, the more pathologic form of Aβ, induces much stronger effects in endothelial cells than in smooth muscle cells, while the reverse is true for Aβ_1–40. Collectively, these findings support the hypothesis that the Aβ-induced inflammatory responses in vascular cells may play a significant role in the pathogenesis of CAA and AD.