Jay Amin

Effect of active Aβ immunotherapy on neurons in human Alzheimer's disease

Amyloid β peptide (Aβ) immunization of Alzheimers disease (AD) patients has been reported to induce amyloid plaque removal, but with little impact on cognitive decline. We have explored the consequences of Aβ immunotherapy on neurons in post mortem brain tissue. Eleven immunized (AN1792, Elan Pharmaceuticals) AD patients were compared to 28 non‐immunized AD cases. Immunohistochemistry on sections of neocortex was performed for neuron‐specific nuclear antigen (NeuN), neurofilament protein (NFP) and phosphorylated‐(p)PKR (pro‐apoptotic kinase detected in degenerating neurons). Quantification was performed for pPKR and status spongiosis (neuropil degeneration), NeuN‐positive neurons/field, curvature of the neuronal processes and interneuronal distance. Data were corrected for age, gender, duration of dementia and APOE genotype and also assessed in relation to Aβ42 and tau pathology and key features of AD. In non‐immunized patients, the degree of neuritic curvature correlated with spongiosis and pPKR, and overall the neurodegenerative markers correlated better with tau pathology than Aβ42 load. Following immunization, spongiosis increased, interneuronal distance increased, while the number of NeuN‐positive neurons decreased, consistent with enhanced neuronal loss. However, neuritic curvature was reduced and pPKR was associated with Aβ removal in immunized patients. In AD, associations of spongiosis status, curvature ratio and pPKR load with microglial markers Iba1, CD68 and CD32 suggest a role for microglia in neurodegeneration. After immunization, correlations were detected between the number of NeuN‐positive neurons and pPKR with Iba1, CD68 and CD64, suggesting that microglia are involved in the neuronal loss. Our findings suggest that in established AD this form of active Aβ immunization may predominantly accelerate loss of damaged degenerating neurons. This interpretation is consistent with in vivo imaging indicating an increased rate of cerebral atrophy in immunized AD patients. Copyright

Dissection of the functional interaction between p53 and the embryonic proto‐oncoprotein PAX3

Studies from murine embryogenesis and cancer cells derived from human melanomas have identified a critical role for the transcription factor PAX3 in the suppression of p53 protein accumulation and p53‐dependent apoptosis. Here we show, using a well‐defined over‐expression system, that PAX3 suppresses p53‐dependent transcription from promoters of p53‐responsive genes, notably BAX and HDM2‐P2, and reduces p53 protein abundance by promoting its degradation. We define the functional domains of PAX3 required for this activity, and furthermore present evidence that PAX3‐dependent inhibition of p53 is independent of binding of the N‐terminal domain of p53 to HDM2, the primary negative regulator of cellular p53 activity.

What do we know about the inflammasome in humans

The inflammasome complex is part of the innate immune system, which serves to protect the host against harm from pathogens and damaged cells. It is a term first proposed by Tschopps group in 2002, with numerous original research articles and reviews published on the topic since. There have been many types of inflammasome identified, but all result in the common pathway of activation of caspases and interleukin 1β along with possible cell death called pyroptosis. Despite a growing body of research investigating the structure and function of the inflammasome in animal models, there is still limited evidence identifying inflammasome components in human physiology and disease. In this review, we explore the molecular structure and mechanism of activation of the inflammasome with a particular focus on inflammasome complexes expressed in humans. Inflammasome components have been identified in several human peripheral and brain tissues using both in vivo and ex vivo work, and the inflammasome complex has been shown to be associated with several genetic and acquired inflammatory and neoplastic disorders. We discuss the strengths and weaknesses of the information available on the inflammasome with an emphasis on the importance of prioritizing work on human tissue. There is a huge demand for more effective treatments for a number of inflammatory and neurodegenerative diseases. Modulation of the inflammasome has been proposed as a novel treatment for several of these diseases and there are currently clinical trials ongoing to test this theory.

Effect of amyloid‐β (Aβ) immunization on hyperphosphorylated tau: a potential role for glycogen synthase kinase (GSK)‐3β

Active amyloid‐β (Aβ) immunotherapy in Alzheimers disease (AD) induces removal of Aβ and phosphorylated tau (ptau). Glycogen synthase kinase (GSK)‐3β is a kinase, responsible for phosphorylation of tau, activation of which can be induced by phosphorylated double‐stranded RNA‐dependent protein kinase (pPKR). Using a post‐mortem cohort of immunized AD cases, we investigated the effect of Aβ immunization on GSK‐3β expression and pPKR.

Consequences of beta-amyloid immunotherapy for Alzheimer's disease on neurons in the human cerebral cortex

Background:Neuroinflammation, manifested by activation of microglia, is an important component of Alzheimer’s disease (AD) pathology with evidence to suggest that it is both a reaction to the disease process and a contributor to neuronal damage, promotingdisease progression. In this study, we have explored in detail the inflammatory processes in the human AD brain and compared the results with those obtained from patients following active Ab42 immunisation (Elan Pharmaceuticals, AN1792). Methods: We studied multiple brain regions in post-mortem tissue from 28 non-immunised AD patients and 11 AD patients immunised against Ab42 (up to 9 years prior to study). The antigen load was quantified in sections immunolabelled for microglial ionised calcium-binding adaptor molecule 1 (Iba-1), the lysosome marker CD68, macrophage scavenger receptor A (MSR-A), Fcg receptors I (CD64) and II (CD32), IgG, complement C1q and T lymphocytes, and compared to the amount of Ab and phospho-tau pathology. Results: The levels of CD68, MSR-A, CD64, CD32 loads and the number of MSR-A-positive plaque-related clusters were significantly lower in immunised AD than non-immunised cases, although there was no significant difference in Iba-1 load, number of Iba-1-positive cells, IgG load, C1q load or number of T cells. In non-immunized AD controls, Ab42 related inversely to CD32 and Iba-1, while phospho-tau was associated with all microglial markers, IgG, C1q and the total number of T cells. In immunised AD cases, Ab42 load related directly to MSR-A-positive clusters, and inversely to C1q.Conclusions:Our findings indicate that different microglial populations coexist in the AD brain and the local inflammatory response may provide an important link between Ab and tau pathology. After immunisation, the microglial functional state is altered in association with reduced Ab and tau pathology. The results suggest that, in the long term, Ab immunotherapy results in down-regulation of microglial activation and potentially reduces the inflammation-mediated component of neurodegeneration of AD.

Effect of Aβ immunisation on hyperphosphorylated tau: a potential role for GSK-3β

Active amyloid‐β (Aβ) immunotherapy in Alzheimers disease (AD) induces removal of Aβ and phosphorylated tau (ptau). Glycogen synthase kinase (GSK)‐3β is a kinase, responsible for phosphorylation of tau, activation of which can be induced by phosphorylated double‐stranded RNA‐dependent protein kinase (pPKR). Using a post‐mortem cohort of immunized AD cases, we investigated the effect of Aβ immunization on GSK‐3β expression and pPKR.

Effect of Aβ immunisation on hyperphosphorylated tau

Active amyloid‐β (Aβ) immunotherapy in Alzheimers disease (AD) induces removal of Aβ and phosphorylated tau (ptau). Glycogen synthase kinase (GSK)‐3β is a kinase, responsible for phosphorylation of tau, activation of which can be induced by phosphorylated double‐stranded RNA‐dependent protein kinase (pPKR). Using a post‐mortem cohort of immunized AD cases, we investigated the effect of Aβ immunization on GSK‐3β expression and pPKR.

Abstract 2266: Pioglitazone increases tumor progression and metastasis in an orthotopic mouse model of non-small cell lung cancer

RATIONALE: Pathways regulating lung cancer metastasis are not well understood. As with most cancers, metastasis depends on critical interactions between tumor cells and the surrounding tumor microenvironment. Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. In humans, a retrospective study of patients treated with thiazolidinediones (TZDs), which are ligands for PPARγ, demonstrated a 33% reduction in risk of developing lung cancer. However, the effect of PPARγ activation on progression and metastasis of established lung tumors has not been clearly established. Our laboratory has developed a mouse model in which murine lung cancer cells directly injected into the lung of syngeneic mice develop secondary pulmonary tumors and metastasize to the mediastinal lymph nodes, the liver, and the brain. The goal of this study was to assess the effects of the TZD pioglitazone on lung cancer progression using this model. METHODS: Murine non-small cell lung cancer cells stably transfected with firefly luciferase were implanted in the left lung of C57BL/6 wild-type mice. Mice were fed either chow impregnated with pioglitazone (0.05%) or control chow. At various time points following injection, animals were sacrificed and organs were assessed for tumors using ex vivo bioluminescence imaging. Primary tumors were measured with digital calipers, and the number of secondary tumors in the other lung lobes, liver and brain were quantified. RESULTS: There was no significant difference in the size of the primary tumor between pioglitazone-treated and control mice at one week. However, primary tumors were significantly larger in pioglitazone-treated animals both 16 and 22 days after implantation of cancer cells. The differences in pulmonary metastases were even more impressive. At both 7 and 16 days, pioglitazone-treated mice showed 2-3 times more secondary pulmonary tumors compared to control animals. By day 25-30, 37.5% of mice fed pioglitazone-impregnated chow developed liver metastases, whereas only 17.6% of mice fed normal chow developed liver metastases. Brain metastases were only detected in mice fed chow impregnated with pioglitazone. CONCLUSION: Treatment of mice with the PPARγ activator pioglitazone unexpectedly accelerates metastasis of established pulmonary tumors. Since selective activation of PPARγ in tumor cells has been shown to inhibit transformed growth and invasiveness, we hypothesize that the metastasis-promoting effects of pioglitazone are mediated through effects on the tumor microenvironment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2266.