Rui-Sheng Duan

Decreased fractalkine and increased IP-10 expression in aged brain of APP(swe) transgenic mice.

Chemokines and their receptors have been strongly implicated in the inflammatory process and pathogenesis of the neurodegenerative disorders, such as Alzheimer’s disease (AD). In the present study, we examined the expression of chemokines, fractalkine, interferon-inducible protein-10 (IP-10) and macrophage inflammatory protein-1α (MIP-1α) by immunohistochemistry in the brain of transgenic mice APPSWE (Tg2576) at ages of 9, 11, and 17xa0months, which over-express a mutated form of human amyloid precursor protein (APP). Decreased fractalkine and increased IP-10 expression in cerebral cortex and hippocampus were found at ages of 9 and 17xa0months in Tg2576 mice when compared with age-matched control mice. On the contrary, MIP-1α expression showed no difference between Tg2576 mice and aged controls and was not influenced by ages. β-amyloid (Aβ) positive plaques were co-located with the intense IP-10 expression. The finding suggests fractalkine and IP-10 may participate in the pathogenesis of AD; and could be new therapeutic strategies for neuroprotection.

Protective potential of experimental autoimmune myasthenia gravis in Lewis rats by IL-10-modified dendritic cells.

Dendritic cells (DC) are usually regarded as antigen-presenting cells (APC) involved in T cell activation, but DC also directly or indirectly affect B cell function, antibody synthesis and isotype switch. In this study, we explore potential of DC-based immunotherapy in ongoing experimental autoimmune myasthenia gravis (EAMG) in Lewis rats, which is mediated by anti-acetylcholine receptor (AChR) antibodies. Spleen DC were isolated from onset of Lewis rat EAMG on day 39 post immunization (p.i.), exposed in vitro to IL-10 and then injected intraperitoneally into ongoing EAMG Lewis rats at dose of 1 x 10(6) cells/rat on day 5 p.i. with AChR + complete Freunds adjuvant. IL-10-modified DC resulted in lower clinical scores, less body weight loss, lower numbers of anti-AChR IgG antibody-secreting cells and lower affinity of anti-AChR antibodies in rats receiving IL-10-modified DC, accompanied with lower expression of CD80 and CD86 and lower lymphocyte proliferation among lymph node mononuclear cells compared with control EAMG rats. Lower levels of IL-10 and IFN-gamma were also found in the supernatants of AChR-stimulated lymph node MNC culture in rats receiving IL-10-modified DC. These results demonstrate that IL-10-modified DC induced hypo-responsiveness by down-regulating co-stimulatory molecules, and reduced production of anti-AChR antibodies possibly by inhibiting IL-10 production. Importantly, this procedure that autologous DC from EAMG were adopted to treat ongoing EAMG is more close to clinical trial in human, encouraging future evaluation in human myasthenia gravis.

Gender differences in susceptibility to kainic acid-induced neurodegeneration in aged C57BL/6 mice

Some epidemiological studies concerning gender differences in Alzheimers disease (AD) support the higher prevalence and incidence of AD in women, while most studies using animal models of aging have included only male subjects. It is still uncommon for aged males and females to be compared in the same study. In the present study, we investigated how age and gender influence the excitotoxic neurodegeneration by treating C57BL/6 mice (aged females and males as well as adult females and males) with kainic acid (KA) intranasally. Clinical signs, behavioural changes, pathological changes and astrocyte proliferation were tested; and the levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were measured after KA treatment. The results showed that aged female mice were more sensitive to KA-induced excitotoxicity as demonstrated by severer seizure activity, increased locomotion and rearing in open-field test, prominent hippocampal neuronal damage, enhanced astrocyte proliferation compared with aged males, adult females and adult male mice. In addition, higher BDNF level in hippocampus of aged female mice was observed. These results denote the disparity of aging and gender in KA-induced hippocampal neurodegeneration and aged female mice are more sensitive to the excitotoxicity.

IL-18 deficiency aggravates kainic acid-induced hippocampal neurodegeneration in C57BL/6 mice due to an overcompensation by IL-12.

The role of interleukin-18 (IL-18) in excitotoxic neurodegeneration is largely unknown. To address this issue, we used kainic acid (KA)-induced hippocampal neurodegeneration in IL-18 knockout (KO) mice. One day after KA administration, clinical symptoms and histopathological changes did not differ between IL-18 KO mice and wild-type mice. However, 7 days after KA application the hippocampal neurodegeneration was markedly severe in IL-18 KO mice as demonstrated by increased locomotion and prominent histopathological changes including neuronal cell loss, microglia activation and astrogliosis. Surprisingly, when wild-type mice received recombinant mouse IL-18 (rmIL-18) in advance, after KA treatment both the clinical and pathological signs were dose-dependently aggravated compared to mice without rmIL-18 pre-treatment. To clarify the mechanism behind this, we assessed the expression of the IL-18 associated cytokines IL-12, IL-1beta, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) in the hippocampus by immunohistochemistry and flow cytometry. IL-12 and IFN-gamma expression was strongly increased in IL-18 KO mice when compared to wild-type mice 7 days after KA treatment in agreement with increased microglia activation. These results suggest that the role of IL-18 in excitotoxic injury in IL-18 deficient mice may be overcompensated by increased IL-12 secretion.

Aggravation of experimental autoimmune neuritis in TNF-α receptor 1 deficient mice

Abstract The role of tumor necrosis factor (TNF)-α and its receptors in the pathogenesis of experimental autoimmune neuritis (EAN) induced by P0 peptide 180–199 in TNFR1 (p55) deficient (TNFR1−/−) mice was investigated. Compared to wild type EAN mice, TNFR1−/− EAN mice developed significantly more severe clinical signs, in parallel with enhanced numbers of inflammatory infiltrating cells in peripheral nerves and splenic P0-reactive T cell proliferation, as well as increased obviously MHC class II and CCR3 expression on the macrophages in the cauda equina. Our data indicated that TNF-α might have anti-inflammatory effect preventing the development of EAN in this mouse model.

IL-12p35 deficiency alleviates kainic acid-induced hippocampal neurodegeneration in C57BL/6 mice.

The role of IL-12 in excitotoxic neurodegeneration of brain is largely unknown. To address this issue, we used the model of kainic acid (KA)-induced hippocampal injury in IL-12p35 knockout (KO) mice, a well-characterized model for human neurodegenerative diseases. After KA treatment, hippocampal neurodegeneration was significantly less severe in the IL-12p35 KO mice than in wild-type mice as demonstrated by reduced pathological changes and astrogliosis. One day after KA treatment, levels of F4/80 and CD86 expression on microglia were significantly lower in IL-12p35 KO mice than in wild-type mice analyzed by flow cytometry, indicating that IL-12p35 deficiency resulted in lower levels of microglial activation. Five days after KA treatment, CD86 expression on microglia of wild-type mice was still higher, whereas F4/80 expression in wild-type mice decreased and was similar to that in IL-12p35 KO mice. Because microglial activation is necessary for KA-induced neurodegeneration, the lower level of microglial activation in the absence of IL-12p35 may alleviate hippocampal injury in KO mice. In summary, this study indicates that IL-12 may play a critical role in excitotoxin-induced brain injury.

Apolipoprotein E deficiency enhances the antigen-presenting capacity of Schwann cells.

Apolipoprotein E (apoE) has immunomodulatory properties and has been implicated in the pathogenic mechanism of autoimmune diseases. Previously, the authors found that apoE deficiency increased the susceptibility to experimental autoimmune neuritis (EAN), an animal model for human Guillain‐Barré syndrome. To further elucidate the mechanism behind apoE deficiency exacerbating EAN, the authors investigated the role of major target and important antigen‐presenting cells of the peripheral nerve system, Schwann cells (SCs), in apoE knockout mice. Treatment of apoE deficient SCs with recombinant mouse interferon‐γ and lipopolysaccharide resulted in higher MHC‐II and CD40 expression as compared with normal SCs derived from wild‐type mice. The increased MHC‐II and CD40 expression on SCs was accompanied by lower levels of intracellular IL‐6 production within SCs of apoE deficiency, which is confirmed by the neutralization with anti IL‐6 antibody. The increased antigen‐presenting capacity of apoE deficient SCs was further explored by enhancement of T cell proliferation co‐cultured with P0 peptide 180–199 specific T cells derived from EAN mice immunized with the P0 peptide. In conclusion, apoE may protect mice from EAN and probably also from chronic inflammatory demyelinating polyneuropathy by affecting the antigen‐presenting function of SCs via influence of IL‐6 production.

Increased cyclin E expression may obviate the role of cyclin D1 during brain development in cyclin D1 knockout mice.

Cyclins D and E play critical roles during the G1 phase of mammalian cell division. Cyclin D1 expression is high and expected to play an important role during mouse brain development. However, in the present study, we found no difference in CNS morphology between cyclin D1 knockout (KO) and control wild‐type mice at the ages of 1, 4 and 12u2003months. Analysis of protein expression in embryonic brains revealed that cyclin E is obviously increased in cyclin D1 KO mice at 13.5u2003days post coitum. At the same age a high level of cyclin D1 expression is detected in the embryonic brain of wild‐type mice. The data indicate that enhanced cyclin E protein expression in cyclin D1 KO mice may obviate the role of cyclin D1 and contribute to the normal brain development of cyclin D1 KO mice.

Long-Term Effects of IFN-γ, IL-10, and TGF-β-Modulated Dendritic Cells on Immune Response in Lewis Rats

Increasing data have shown that IFN-γ, IL-10, and TGF-β-modulated dendritic cells (DC) provide a promising strategy in treatment of experimental allergic encephalomyelitis and experimental autoimmune myasthenia gravis through different manner. To explore the immune response status after long-term application of these cytokine-modulated-DC, Lewis rats were injected subcutaneously into naive DC and IFN-γ, IL-10, and TGF-β-modulated DC (i.e., IFN-γ-DC, IL-10-DC, and TGF-β-DC) at does of 1 × 106 cells/rat every month for continuous 18 months, respectively. No rats suffered from decreased vigor and activity as well as cachectic condition during 18-month observation, and no rats had body-weight loss after 18-month treatment. Exploratory laparectomy did not find any tumor in all rats. IL-10-DC and TGF-β-DC resulted in lower nonspecific (Con A-induced) and antigen specific (ovalbumin-stimulated) spleen mononuclear cells proliferation, accompanied by lower levels of IFN-γ, IL-10, and TNF-α. On the contrary, IFN-γ-DC did not suppress cell proliferation and IFN-γ and IL-10 production except only slightly decreased TNF-α levels. These results suggest that IFN-γ-DC seems to be a more ideal candidate in the treatment of autoimmune diseases without suppressing immune response.

Apolipoprotein E deficiency increased microglial activation/CCR3 expression and hippocampal damage in kainic acid exposed mice.

Apolipoprotein E (apoE) down-regulates microglial activation and the secretion of inflammatory molecules in an isoform specific fashion (E2 > E3 > E4); the E4 isoform is over-represented in Alzheimer cases while E2 is under-represented. To better define the role of apoE in neurodegeneration, we contrasted apoE knockout (n = 38) and wild-type mice (n = 41) with respect to seizure activity, mortality, locomotion, hippocampal microglial activation/chemokine receptor expression, and damage to the hippocampus after nasal administration of kainic acid (KA) (water as controls). Mice lacking apoE demonstrated more hunching and less rearing, more damage to neurons in the CA3 region (mean histopathologic score: 3.7 vs. 1.6, p < 0.05), greater microglial activation confirmed by high levels of CD11b and CD86 expression in hippocampus (CD11b p < 0.01, CD86 p < 0.05), and a greater percentage of activated microglia expressing CC chemokine receptors 3 (CCR3) (p < 0.05). Taken together, these findings imply that apoE modulates hippocampal damage induced by KA and found early in the sequence of human Alzheimers brain changes, by modulating microglial activation.