Shohreh Issazadeh

Nasal administration of amyloid‐β peptide decreases cerebral amyloid burden in a mouse model of Alzheimer's disease

Progressive cerebral deposition of amyloid‐β (Aβ) peptide, an early and essential feature of Alzheimers disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease‐implicated proteins can induce antigen‐specific anti‐inflammatory immune responses in mucosal lymphoid tissue which then act systemically. We hypothesized that chronic mucosal administration of Aβ peptide might induce an anti‐inflammatory process in AD brain tissue that could beneficially affect the neuropathological findings. To test this hypothesis, we treated PDAPP mice, a transgenic line displaying numerous neuropathological features of AD, between the ages of ∼5 and ∼12 months with human Aβ synthetic peptide mucosally each week. We found significant decreases in the cerebral Aβ plaque burden and Aβ42 levels in mice treated intranasally with Aβ peptide versus controls treated with myelin basic protein or left untreated. This lower Aβ burden was associated with decreased local microglial and astrocytic activation, decreased neuritic dystrophy, serum anti‐Aβ antibodies of the IgG1 and IgG2b classes, and mononuclear cells in the brain expressing the anti‐inflammatory cytokines interleukin‐4, interleukin‐10, and tumor growth factor‐β. Our results demonstrate that chronic nasal administration of Aβ peptide can induce an immune response to Aβ that decreases cerebral Aβ deposition, suggesting a novel mucosal immunological approach for the treatment and prevention of AD. Ann Neurol 2000;48:567–579

Elevated interleukin-12 in progressive multiple sclerosis correlates with disease activity and is normalized by pulse cyclophosphamide therapy.

Multiple sclerosis is postulated to be a Th1-type cell-mediated autoimmune disease. We investigated cytokine profiles in patients with progressive multiple sclerosis by using intracytoplasmic staining. We found increased IL-12 production by monocytes and increased IFN-gamma production by T cells in untreated patients as compared with controls. In patients treated with methotrexate, methylprednisolone, or cyclophosphamide/methylprednisolone (CY/MP), only CY/MP treatment normalized the elevated IL-12 production. Furthermore, CY/MP-treated patients had decreased IFN-gamma and increased IL-4, IL-5, and TGF-beta expression. Patients followed prospectively before and after starting CY/MP treatment showed a gradual decrease in IL-12 and IFN-gamma production and an increase in IL-4 and IL-5. In vitro, addition of 4-hydroperoxycyclophosphamide, a metabolite of cyclophosphamide decreased IL-12 production in mononuclear cell cultures. When patients were classified as having active or stable disease, IL-12 production correlated with disease activity. In summary, our results demonstrate a Th1-type cytokine bias in peripheral blood mononuclear cells of untreated progressive MS patients that is reversed by CY/MP treatment and is associated with Th2 and TGF-beta (Th3) type responses. These findings provide a basis for immune monitoring of patients with MS and suggest that treatments that downregulate IL-12 may prove to be beneficial in progressive MS.

Cytokine production in the central nervous system of Lewis rats with experimental autoimmune encephalomyelitis: dynamics of mRNA expression for interleukin-10, interleukin-12, cytolysin, tumor necrosis factor α and tumor necrosis factor β

The kinetics of mRNA expression in the central nervous system (CNS) for a series of putatively disease-promoting and disease-limiting cytokines during the course of experimental autoimmune encephalomyelitis (EAE) in Lewis rats were studied. Cytokine mRNA-expressing cells were detected in cryosections of spinal cords using in situ hybridization technique with synthetic oligonucleotide probes. Three stages of cytokine mRNA expression could be distinguished: (i) interleukin (IL)-12, tumor necrosis factor (TNF)-beta (= lymphotoxin-alpha) and cytolysin appeared early and before onset of clinical signs of EAE; (ii) TNF-alpha peaked at height of clinical signs of EAE; (iii) IL-10 appeared increasingly at and after clinical recovery. The early expression of IL-12 prior to the expression of interferon-gamma (IFN-gamma) mRNA shown previously is consistent with a role of IL-12 in promoting proliferation and activation of T helper 1 (Th1) type cells producing IFN-gamma. The TNF-beta mRNA expression prior to onset of clinical signs favours a role for this cytokine in disease initiation. A pathogenic effector role of TNF-alpha was suggested from these observations that TNF-alpha mRNA expression roughly paralleled the clinical signs of EAE. This may be the case also for cytolysin. IL-10-expressing cells gradually increased to high levels in the recovery phase of EAE, consistent with a function in down-regulating the CNS inflammation. From these data we conclude that there is an ordered appearance of putative disease-promoting and -limiting cytokines in the CNS during acute monophasic EAE.

Protracted, relapsing and demyelinating experimental autoimmune encephalomyelitis in DA rats immunized with syngeneic spinal cord and incomplete Freund's adjuvant

Experimental autoimmune encephalomyelitis (EAE) is a model for multiple sclerosis (MS). However, MS is a chronic, relapsing and demyelinating disease, whereas EAE in rats is typically a brief and monophasic disorder showing little demyelination. We demonstrate here that DA rats develop severe, protracted and relapsing EAE (SPR-EAE) after a subcutaneous immunization at the tail base with syngeneic spinal cord and incomplete Freunds adjuvant (IFA). The neurological deficits were accompanied by demyelinating inflammatory lesions in the spinal cord, with infiltrating T lymphocytes and perivascular deposition of immunoglobulins and complement. The induction of SPR-EAE was associated with humoral autoreactivity to myelin oligodendrocyte glycoprotein (MOG) and cellular autoreactivity to the rat myelin basic protein (MBP) peptides 69-87 and 87-101. These two peptides, as well as whole rat MBP, were encephalitogenic. In conclusion, we believe that the presently described demyelinating SPR-EAE represents a useful model for MS.

The role of CD154-CD40 versus CD28-B7 costimulatory pathways in regulating allogeneic Th1 and Th2 responses in vivo

We used signal transducer and activator of transcription 4 (STAT4) and STAT6 gene knockout (-/-) mice as recipients of fully mismatched cardiac allografts to study the role of T-cell costimulatory pathways in regulating allogeneic T-helper 1 (Th1) versus Th2 responses in vivo. STAT4(-/-) mice have impaired Th1 responses, whereas STAT6(-/-) mice do not generate normal Th2 responses. Cardiac allografts from C57BL/6 mice were transplanted into normal wild-type (WT), STAT4(-/-), and STAT6(-/-) BALB/c recipients. STAT4(-/-) and STAT6(-/-) mice rejected their grafts with the same tempo as untreated WT recipients. CD28-B7 blockade by a single injection of CTLA4Ig induced long-term engraftment and donor-specific tolerance in all three groups of recipients. CD154 blockade by a single injection of MR1 was effective in prolonging allograft survival and inducing tolerance in STAT4(-/-) mice but was only marginally effective in STAT6(-/-) recipients and WT controls. In addition, a similar protocol of MR1 was ineffective in prolonging graft survival in CD28(-/-) BALB/c recipients, suggesting that the lack of efficacy seen in WT and STAT6(-/-) mice is not due to the presence of a functional CD28-B7 pathway. Furthermore, there was a similar differential effect of CD28-B7 versus CD154-CD40 blockade in inhibiting immune responses in animals immunized with ovalbumin and complete Freunds adjuvant. These novel data indicate that Th1 and Th2 cells are differentially regulated by CD28-B7 versus CD154-CD40 costimulation pathways in vivo and may have potential implications for the development of therapeutic strategies such as T-cell costimulatory blockade in humans.

Cytokines in relapsing experimental autoimmune encephalomyelitis in DA rats: persistent mRNA expression of proinflammatory cytokines and absent expression of interleukin-10 and transforming growth factor-β

Experimental autoimmune encephalomyelitis (EAE) in rats is typically a brief and monophasic disease with sparse demyelination. However, inbred DA rats develop a demyelinating, prolonged and relapsing encephalomyelitis after immunization with rat spinal cord in incomplete Freunds adjuvant. This model enables studies of mechanisms related to chronicity and demyelination, two hallmarks of multiple sclerosis (MS). Here we have investigated, in situ, the dynamics of cytokine mRNA expression in the central nervous system (CNS) and peripheral lymphoid organs (lymph node cells and splenocytes) of diseased DA rats. We demonstrate that peripheral lymphoid cells stimulated in vitro with encephalitogenic peptides 69-87 and 87-101 of myelin basic protein responded with high mRNA expression for proinflammatory cytokines; interferon-gamma, interleukin-12 (IL-12), tumour necrosis factors alpha and beta, IL-1 beta and cytolysin. A high expression of mRNA for these proinflammatory cytokines was also observed in the CNS where it was accompanied by classical signs of inflammation such as expression of major histocompatibility complex class I and II, CD4, CD8 and IL-2 receptor. The expression of mRNA for proinflammatory cytokines was remarkably long-lasting in DA rats as compared to LEW rats which display a brief and monophasic EAE. Furthermore, mRNAs for putative immunodownmodulatory cytokines, i.e. transforming growth factor-beta (TGF-beta), IL-10 and IL-4 were almost absent in DA rats, in both the CNS and in vitro stimulated peripheral lymphoid cells, while their levels were elevated in the CNS of LEW rats during the recovery phase. We conclude that the MS-like prolonged and relapsing EAE in DA rats is associated with a prolonged production of proinflammatory cytokines and/or low or absent production of immunodownmodulatory cytokines.

Genetic analysis of inflammation, cytokine mRNA expression and disease course of relapsing experimental autoimmune encephalomyelitis in DA rats

Genetic analysis of experimental autoimmune encephalomyelitis (EAE) can provide clues to the etiology of multiple sclerosis (MS). Identifying the susceptibility genes of DA rats may be particularly rewarding since they are prone to develop a remarkably MS-like chronic and demyelinating disease. As a first step in this direction, we investigated the role of DA genes within and outside the major histocompatibility complex (MHC) for susceptibility to severe protracted and relapsing EAE (SPR-EAE). This form of EAE developed in DA rats but not in LEW. ACI and BN rats after immunization with syngeneic spinal cord and complete Freunds adjuvant. Studies of crosses between DA and BN rats revealed that non-MHC genes determine susceptibility to SPR-EAE. A role for MHC-genes was also established using MHC-congenic rat strains, in which the DA MHC haplotype (av1) associated with relapsing EAE. Again, non-MHC genes were decisive since a high incidence of SPR-EAE only occurred in rats with DA non-MHC genes. Analysis of cytokine mRNA expression and infiltrating cells in the spinal cords of congenic strains revealed that the av1 haplotype associated with a high CD4/CD8 ratio and expression of mRNA for interferon-gamma (IFN-gamma), but not for transforming growth factor-beta (TGF-beta) or interleukin-10 (IL-10). In contrast, the other MHC haplotypes (h, l, u) associated with low CD4/CD8 ratios and mRNA expression for TGF-beta and IL-10, but not for IFN-gamma. DA non-MHC genes determined the intensity of inflammation since the number of cells expressing MHC class II, CD4 and interleukin-2 receptor (IL-2R) was higher in DA rats than in LEW.1AV1 and PVG.1AV1 rats which also carry the av1 haplotype. We conclude that the MHC haplotype of DA rats favors a prolonged proinflammatory autoimmune response associated with relapses, while the DA background intensifies inflammation correlating with a high incidence of relapsing disease.

Costimulatory signal blockade in murine relapsing experimental autoimmune encephalomyelitis

Blockade of the CD28-B7 or CD40L-CD40 T cell costimulatory signals prevents induction of experimental autoimmune encephalomyelitis (EAE). However, the effect of simultaneous blockade of these signals in EAE is unknown. We show that administration of either MR1 (to block CD40L) or CTLA4Ig (to block B7) after immunization or after the first attack protects from EAE. Treatment with a combination of CTLA4Ig and MR1 provides additive protection, and is associated with complete absence of mononuclear cell infiltrates in the central nervous system, and marked suppression of proliferation of primed T cells in the periphery. Selective B7-1 blockade did not protect from EAE. These observations have implications for therapy of autoimmune diseases.

The major histocompatibility complex influences myelin basic protein 63–88 induced T cell cytokine profile and experimental autoimmune encephalomyelitis

Polymorphism of the major histocompatibility complex (MHC) influences susceptibility to experimental autoimmune encephalomyelitis (EAE) induced by myelin basic protein (MBP) in rats. Current concepts relate such influences to the capacity of class II molecules to present relevant peptides to autoreactive T cells. We have here analyzed the MHC influence on the immune response and the development of EAE after immunization with the immunodominant peptide MBP-63-88. Analysis of MHC-congenic LEWIS strains showed that RT1a, RT1c and RT1(1) haplotypes are permissive for disease induction, whereas RT1d and RT1u are resistant. All EAE responding strains showed peptide-specific proliferation and interferon (IFN)-gamma secretion, but no early significant tendency to express interleukin (IL-4) or transforming growth factor (TGF)-beta mRNA in lymphocytes in response to the MBP 63-88, 7 days post immunization (p.i.). Later, 14 days p.i., peptide-specific induction of IL-4 and TGF-beta occurred in RT1(1) rats. Among the EAE non-responders strains, only the RT1u rats showed an immune response to MBP 63-88. This response, however, was qualitatively different from the immune response in the EAE-susceptible strains. Thus, there was no proliferation and only moderate IFN-gamma production in response to peptide, but in contrast, a significant and early peptide-induced IL-4 and TGF-beta response was observed. The data suggest that the MHC-associated susceptibility to EAE is partly related to the ability to mount a TH1-like immune response while the MHC-associated EAE resistance may either be related to MBP peptide non-responsiveness or to peptide recognition and induction of a qualitatively different and disease down-regulatory immune response.

Dynamics of cellular cytokine mRNA expression in the central nervous system during experimental autoimmune encephalomyelitis in Lewis rats

Introduction. igM has a very low concentration in cerabmspinal fluid (CSF) compemd to serum, end therefore determinations of igM in CSF are highly sensitive to pro-analytical errors caused by contamination with serum or interstitial fluid, Owing to the capillary force, a thin layer of liquid containing serum proteins may be formed at the inside of a conventional (Qulncke) needle dunng penetration of tissue.