Ruth Maron

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

Mucosal Administration of Heat Shock Protein-65 Decreases Atherosclerosis and Inflammation in Aortic Arch of Low-Density Lipoprotein Receptor-Deficient Mice

Background—Increasing evidence supports the involvement of inflammation and immunity in atherogenesis as well as the role of autoimmunity to heat shock proteins (HSPs) in the progression of atherosclerosis. Mucosal administration of autoantigens decreases organ-specific inflammation and disease in several models of autoimmunity (diabetes, arthritis, and encephalomyelitis) and is also being tested in human clinical trials. Methods and Results—We examined the effect of nasal or oral administration of mycobacterial HSP-65 on atherosclerotic lesion formation in mice lacking the receptor for LDL that were maintained on a high-cholesterol diet. Animals were nasally or orally treated for 1 week with HSP-65, and a high-cholesterol diet was started after the last treatment. The mice were mucosally treated once a week for 8 or 12 weeks, at which time pathological analysis was performed. We found a significant decrease in the size of atherosclerotic plaques, a reduction in macrophage-positive area in the aortic arch, increased interleukin-10 expression, and a reduced number of T cells in nasally treated animals compared with control animals. A similar trend was observed in orally treated mice, but it was not significant. Conclusions—Our results demonstrate that nasal vaccination with HSP reduces the inflammatory process associated with atherosclerosis and provides a new immunologic approach for the treatment of atherosclerosis.

Oral CD3-specific antibody suppresses autoimmune encephalomyelitis by inducing CD4+ CD25- LAP+ T cells.

A major goal of immunotherapy for autoimmune diseases and transplantation is induction of regulatory T cells that mediate immunologic tolerance. The mucosal immune system is unique, as tolerance is preferentially induced after exposure to antigen, and induction of regulatory T cells is a primary mechanism of oral tolerance. Parenteral administration of CD3-specific monoclonal antibody is an approved therapy for transplantation in humans and is effective in autoimmune diabetes. We found that orally administered CD3-specific antibody is biologically active in the gut and suppresses autoimmune encephalomyelitis both before induction of disease and at the height of disease. Orally administered CD3-specific antibody induces CD4+CD25−LAP+ regulatory T cells that contain latency-associated peptide (LAP) on their surface and that function in vitro and in vivo through a TGF-β–dependent mechanism. These findings identify a new immunologic approach that is widely applicable for the treatment of human autoimmune conditions.

Induction of regulatory T cells decreases adipose inflammation and alleviates insulin resistance in ob/ob mice

Leptin-deficient ob/ob mice are overweight, develop insulin resistance, and serve as a model for type 2 diabetes (T2D). Studies suggest that inflammatory pathways are linked to the development of insulin resistance and T2D both in animals and humans. We asked whether the induction of regulatory T cells (Tregs) could alleviate the pathological and metabolic abnormalities in ob/ob mice. We induced TGF-β-dependent CD4+ latency-associated peptide (LAP)-positive Tregs by oral administration of anti-CD3 antibody plus β-glucosylceramide. We found a decrease in pancreatic islet cell hyperplasia, fat accumulation in the liver, and inflammation in adipose tissue, accompanied by lower blood glucose and liver enzymes. In addition, treated animals had decreased CD11b+F4/80+ macrophages and TNF-α in adipose tissue. Adoptive transfer of orally induced CD4+LAP+ Tregs ameliorated metabolic and cytokine abnormalities. Our results demonstrate the importance of inflammation in T2D and identify a unique immunological approach for treatment of T2D by the induction of Tregs.

Nasal Vaccination with Myelin Oligodendrocyte Glycoprotein Reduces Stroke Size by Inducing IL-10-Producing CD4+ T Cells

Inflammation plays an important role in ischemic stroke and in humans IL-10 may have a beneficial effect in stroke. We mucosally administered myelin oligodendrocyte glycoprotein (MOG) 35–55 peptide to C57BL/6 mice before middle cerebral artery occlusion (MCAO) to induce an anti-inflammatory T cell response directed at CNS myelin. Nasal and oral administration of MOG35–55 peptide decreased ischemic infarct size at 24 and 72 h after MCAO surgery. Nasal MOG35–55 peptide was most efficacious and reduced infarct size by 70% at 24 h and by 50% at 72 h (p ≤ 0.0001 vs control) and also improved behavior score. Immunohistochemistry demonstrated increased IL-10 and reduced IFN-γ in the area surrounding the ischemic infarct following nasal treatment. Nasal MOG did not reduce infarct size in IL-10-deficient mice. Adoptive transfer of CD4+ T cells to untreated mice from nasally tolerized mice before MCAO surgery decreased stroke size (p < 0.001 vs control), whereas, CD4+ T cells from nasally tolerized IL-10-deficient mice had no effect. Our results demonstrate that IL-10-secreting CD4+ T cells induced by nasal MOG reduce injury following stroke. In addition, we observed a dramatic reduction of CD11b+ cells in nasal MOG-treated animals. CD11b+ cells may contribute to secondary infarct expansion by enhancing NO synthesis that may be reduced by elevated IL-10 levels. Modulation of cerebral inflammation by nasal vaccination with myelin Ags that increase IL-10 in the brain may improve outcome after stroke and enhance mechanisms of recovery.

Nasal Aβ Treatment Induces Anti‐Aβ Antibody Production and Decreases Cerebral Amyloid Burden in PD‐APP Mice

Amyloid accumulation1 and accompanying inflammation—including both the activation of glial cells2 and the accrual of inflammatory proteins, such as complement,3,4 cytokines,5 and acute phase proteins6–8—play key roles in the pathogenesis of Alzheimer’s disease (AD).9 Mucosal administration of proteins implicated in a disease can decrease organ-specific inflammatory processes in a number of animal models of autoimmune disorders, including those affecting the nervous system, principally by inducing antiinflammatory IL-4/IL-10 (Th2) and TGFβ immune responses in mucosal lymphoid tissue that then act systemically.10 For example, oral or nasal administration of myelin basic protein (MBP)11–13 or the acetylcholine receptor14,15 can suppress experimental autoimmune encephalomyelitis (EAE) and experimental myasthenia gravis, respectively. In an effort to reduce the inflammation associated with Aβ deposition via mucosal tolerance, we tested the effects of nasal or oral administration of Aβ1–40 peptide and a control protein, myelin basic protein (MBP), by treating 52 PD-APP transgenic mice, an animal model with certain key features of AD,16–18 on a weekly basis for seven months (ages 5 to 12 months). Doses were chosen based on preliminary nasal and oral studies in nontransgenic mice. Treatment groups included (1) untreated (n = 7); (2) MBP oral, 500 μg (n = 5); (3) MBP nasal, 50 μg (n = 6); (4) Aβ oral, 10 μg (n = 9); (5) Aβ oral, 100 μg (n = 9); (6) Aβ nasal, 5 μg (n = 7); and (7) Aβ nasal, 25 μg (n = 9). During the first week, mice were fed five times or nasally treated three times on consecutive days. Thereafter, mice were fed or nasally treated each week for seven months and then sacrificed. The brain from each mouse was removed and divided in half along the sagittal midline. One hemisphere was formalin fixed and embedded in paraffin for immunohistochemical analysis. Of the contralateral hemispheres, half were snap frozen for biochemical analysis; the other half were embedded sagittally in OCT and snap frozen for cryosectioning and immunohistochemistry.

Neuroprotection by IL-10-producing MOG CD4+ T cells following ischemic stroke.

Mucosal tolerance has been used successfully to treat animal models of autoimmune diseases and is being tested in human diseases. In this work we demonstrate the reduction of infarct size following mucosal tolerance by myelin oligodendrocyte glycoprotein (MOG) (35-55) peptide in mouse stroke model. Nasal MOG was most efficacious and reduced ischemic infarct size by 70% at 24 h as well as improving behavior score. Using immunohistological methods and IL-10 -/- mice, we demonstrate the importance of IL-10-producing CD4+ T cells in the reduction of the ischemic infarct volume following middle cerebral artery occlusion (MCAO). Furthermore, adoptive transfer of CD4+ T cells from nasally tolerized mice to untreated mice prior to MCAO surgery significantly decreased stroke size (p<0.001 vs. control), whereas CD4+ T cells from nasally tolerized IL-10-deficient mice had no significant effect. Based on these results, modulation of cerebral inflammation by mucosal tolerance to myelin antigens may have applicability both as prophylactic therapy and treatment following ischemia attacks.

Oral tolerance induced by continuous feeding: enhanced up-regulation of transforming growth factor-β/interleukin-10 and suppression of experimental autoimmune encephalomyelitis

Oral administration of antigen leads to specific immune hyporesponsiveness termed as oral tolerance. Different doses and feeding regimens have been demonstrated to induce different types of tolerance and degrees of immune suppression. Herein, we compare distinct different regimens of feeding using equivalent final doses of antigen in order to investigate the role of frequency of antigen uptake in the induction of oral tolerance. We demonstrate that continuous feeding of antigen in the drinking water, as compared to a single feeding or feeding once per day over several days enhances suppression to both Th1 and Th2 type responses in B6D2F1 and BALB/c mice. Continuous feeding suppresses antibody responses in aged B6D2F1 mice, which are otherwise refractory to oral tolerance induction. Continuous feeding of ovalbumin (OVA) in high or low doses, as compared to control or single daily feeding over several days, up-regulates interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) production in both OVA TCR transgenic and BALB/c mice. In all regimens tested in wild type mice, low doses were more efficacious than high doses in inducing IL-10 and TGF-beta. Serial feeding (multiple low dose daily gavages) using OVA or myelin basic protein (MBP), also led to up-regulation of TGF-beta and IL-10 production in OVA TCR and MBP TCR transgenic mice, as well as enhanced inhibition of MBP-induced experimental autoimmune encephalomyelitis (EAE) in (PLxSJL) F1 mice. We did not find differences in the cytokine profile between serial (multiple low dose daily gavages) and continuous feeding regimens, suggesting that repetitive discrete delivery of oral antigen provides a sustained signal for the induction of oral tolerance. Thus, using different regimens of feeding that resemble natural feeding with equivalent final doses of antigen, we found enhancement of oral tolerance utilizing regimens that resemble natural feeding. Such feeding regimens may be advantageous in the application of oral tolerance for clinical purposes in the treatment of autoimmune and other inflammatory conditions.

Nasal Vaccination with β-Amyloid Peptide for the Treatment of Alzheimer's Disease

Alzheimers disease (AD) is a severe neurodegenerative disease for which there is currently no effective prevention or treatment. The prediction that the number of U.S. patients with AD will triple...

Inhibition of Autoimmune Diabetes by Oral Administration of Anti-CD3 Monoclonal Antibody

Anti-CD3 monoclonal antibody (mAb) has been shown to induce tolerance and to be an effective treatment for diabetes both in animal models and in human trials. We have shown that anti-CD3 mAb given orally is biologically active in the gut and suppresses experimental autoimmune encephalitis by the induction of a regulatory T-cell that expresses latency-associated peptide (LAP) on its surface. In the present study, we investigated the effect of oral anti-CD3 mAb on the prevention of autoimmune diabetes in AKR mice in which the low-dose streptozocin (STZ) model induces autoimmunity to the β-cells of the islets. We found that oral anti-CD3 mAb given at doses of 50 and 250 μg/feeding suppressed the incidence of diabetes in this model with the best effects seen at the 50 μg/dose. Associated with suppression, we observed decreased cell proliferation in the spleen and conversion of T-helper (Th)1 responses into Th2/Th3 responses in the periphery, including the pancreatic lymph nodes. Oral anti-CD3 mAb increased the expression of LAP on CD4+ T-cells, and these cells could adoptively transfer protection. Protection by oral anti-CD3 was transforming growth factor-β dependent. Our results demonstrate that oral anti-CD3 is effective in the model of STZ-induced diabetes and may be a useful form of therapy for type 1 diabetes in humans.