Vaccination against amyloid ␤-peptide (A␤) has been shown to be successful in reducing A␤ burden and neurotoxicity in mouse models of Alzheimer's disease (AD). However, although A␤ immunization did not show T cell infiltrates in the brain of these mice, an A␤ vaccination trial resulted in meningoencephalitis in 6% of patients with AD. Here, we explore the characteristics and specificity of A␤-induced, T cell-mediated encephalitis in a mouse model of the disease. We demonstrate that a strong A␤-specific T cell response is critically dependent on the immunizing T cell epitope and that epitopes differ depending on MHC genetic background. The amounts and the ratio between the two forms and their deposition in the brain are affected by mutations in the APP and presenilin genes or the presence of the ApoE4 allele (3, 4). Immunolabeling of extracellular A␤ in the brain reveals neuritic and diffuse plaques. The former are colocalized with activated microglia and astrocytes as well as degenerating neurons, whereas the latter do not clearly associate with glial activation or neurotoxicity (5). Recent findings also demonstrate a role for A␤ synaptotoxicity independent of plaques, possibly mediated by soluble A␤ oligomers at intra-and extracellular compartments (6-9).Parenteral immunization of APP transgenic (Tg) mice with synthetic A␤ in adjuvant can markedly decrease the number and density of A␤ deposits in the brain, with concomitant improvement in neuritic dystrophy and gliosis (10, 11). Positive effects have also been found after repetitive mucosal (intranasal) administration of the A␤ peptide to Tg mice (12, 13). Passive transfer of A␤ antibodies has shown similar beneficial neuropathological effects (14-16); however, brain hemorrhage appears as a possible side effect of this approach if tested in mice with cerebral amyloid angiopathy (7).The finding that active vaccination with A␤ had profound A␤-lowering effects in an animal model of AD led to a clinical trial in which an A␤1-42 synthetic peptide was administered parenterally with adjuvant to patients with mild to moderate AD. Although a phase I safety study in a small number of patients did not reveal significant side effects, a subsequent phase II trial was discontinued shortly after its initiation, when Ϸ6% of the treated patients developed meningoencephalitis (17). Nonetheless, a cohort of patients with AD vaccinated with A␤ have shown promising results, demonstrating slower decline of cognitive functions over a 1-year period, which was evident also in patients who experienced transient encephalitis (18). Postmortem analysis of brain sections revealed decreased A␤ plaques in neocortex regions associated with activated microglia and T cell infiltrates in the CNS, as compared with unimmunized patients with AD (19).The meningoencephalitis observed after A␤ vaccination of patients with AD is postulated to be the result of activation of A␤-reactive T cells in the periphery and their migration to A␤ plaques in the brain. Understanding the factors that are required to ...

Objective:We assessed whether peripheral activation of microglia by a nasal proteosome-based adjuvant (Protollin) that has been given safely to humans can prevent amyloid deposition in young mice and affect amyloid deposition and memory function in old mice with a large amyloid load. Methods: Amyloid precursor protein (APP) transgenic (Tg) J20 mice received nasal treatment with Protollin weekly for 8 months beginning at age 5 months. Twenty-four-month-old J20 mice were treated weekly for 6 weeks. Results: We found reduction in the level of fibrillar amyloid (93%), insoluble ␤-amyloid (A␤; 68%), and soluble A␤ (45%) fragments in 14-month-old mice treated with Protollin beginning at age 5 months. Twenty-four-month-old mice treated with nasal Protollin for 6 weeks had decreased soluble and insoluble A␤ (1-40) and (1-42) and improved memory function. Activated microglia (CD11b ϩ cells) colocalized with A␤ fibrils in the 24-month-old animals, and microglial activation correlated with the decrease in A␤. No microglial activation was observed in 14-month-old mice, suggesting that once A␤ is cleared, there is downregulation of microglial activation. Both groups had reduction in astrocytosis. Protollin was observed in the nasal cavity and cervical lymph node but not in the brain. Activated CD11b ϩ SRA ϩ (scavenger receptor A) cells were found in blood and cervical lymph node and increased interleukin-10 in cervical lymph node. No toxicity was associated with treatment.Interpretation: Our results demonstrate a novel antibody-independent immunotherapy for both prevention and treatment of Alzheimer's disease that is mediated by peripheral activation of microglia with no apparent toxicity.

The main goal of this study was to develop a liposome formulation with sulfanilamide and to investigate the liposomes impact on its release and stability to the UV-A/UV-B and UV-C irradiation. Liposome dispersions with incorporated sulfanilamide were prepared by thin-film hydration method and liposomes role to the sulfanilamide release was investigated by using a dialysis method. Comparatively, sulfanilamide in phosphate buffer solution was subject to release study as well to the UV irradiation providing for the possibilities of kinetics analysis. drug release study demonstrated that 20% of sulfanilamide was released from liposomes within 1 h that is approximately twice as slower as in the case of dissolved sulfanilamide in phosphate buffer solution. The kinetic release process can be described by Korsmeyer-Peppas model and according to the value of diffusion release exponent it can be concluded that drug release mechanism is based on the phenomenon of diffusion. The sulfanilamide degradation in phosphate buffer solution and liposomes is related to the formation of UV-induced degradation products that are identified by UHPLC/MS analysis as: sulfanilic acid, aniline and benzidine. The UV-induced sulfanilamide degradation in the phosphate buffer solution and liposome vesicles fits the first- order kinetic model. The degradation rate constants are dependent on the involved UV photons energy input as well as sulfanilamide microenvironment. Liposome microenvironment provides better irradiation sulfanilamide stability. The obtained results suggest that liposomes might be promising carriers for delayed sulfanilamide delivery and may serve as a basis for further research.