Cross-Linking Cellular Prion Protein Induces Neuronal Type 2-Like Hypersensitivity.

Background: Previous reports identified proteins associated with 'apoptosis' following cross-linking PrPC with motif-specific anti-PrP antibodies in vivo and in vitro. The molecular mechanisms underlying this IgG-mediated neurotoxicity and the role of the activated proteins in the apoptotic pathways leading to neuronal death has not been properly defined. Previous reports implicated a number of proteins, including apolipoprotein E, cytoplasmic phospholipase A2, prostaglandin and calpain with anti-PrP antibody-mediated 'apoptosis', however, these proteins are also known to play an important role in allergy. In this study, we investigated whether cross-linking PrPC with anti-PrP antibodies stimulates a neuronal allergenic response. Methods: Initially, we predicted the allergenicity of the epitope sequences associated with 'neurotoxic' anti-PrP antibodies using allergenicity prediction servers. We then investigated whether anti-PrP antibody treatment of mouse primary neurons (MPN), neuroblastoma cells (N2a) and microglia (N11) cell lines lead to a neuronal allergenic response. Results: In-Silico studies showed that both tail- and globular-epitopes were allergenic. Specifically, binding regions that contain epitopes for previously reported 'neurotoxic' antibodies such as ICSM18 (146-159), ICSM35 (91-110), POM 1 (138-147) and POM 3 (95-100) lead to activation of allergenic related proteins. Following direct application of anti-PrPC antibodies on N2a cells, we identified 4 neuronal allergenic-related proteins when compared with untreated cells. Furthermore, we identified 8 neuronal allergenic-related proteins following treatment of N11 cells with anti-PrPC antibodies prior to co-culture with N2a cells when compared with untreated cells. Antibody treatment of MPN or MPN co-cultured with antibody-treated N11 led to identifying 10 and 7 allergenic-related proteins when compared with untreated cells. However, comparison with 3F4 antibody treatment revealed 5 and 4 allergenic-related proteins respectively. Of importance, we showed that the allergenic effects triggered by the anti-PrP antibodies were more potent when antibody-treated microglia were co-cultured with the neuroblastoma cell line. Finally, co-culture of N2a or MPN with N11-treated with anti-PrP antibodies resulted in significant accumulation of NO and IL6 but not TNF-α in the cell culture media supernatant. Conclusions: This study showed for the first time that anti-PrP antibody binding to PrPC triggers a neuronal hypersensitivity response and highlights the important role of microglia in triggering an IgG-mediated neuronal hypersensitivity response. Moreover, this study provides an important impetus for including allergenic assessment of therapeutic antibodies for neurodegenerative disorders to derive safe and targeted biotherapeutics.

Current and future therapeutic targets of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic systematic autoimmune disease which affects about 1% of the population world wide. This article aimed to identify current therapeutic targets for RA based on data from the literature and drug target related databases. Identified targets were further analysed using a powerful bioinformatics tool, PANTHER (Protein ANalysis THrough Evolutionary Relationships). Additionally, we explored future possible therapeutic targets for RA and discussed the possibility of discovering novel drugs with improved efficacy and reduced toxicity for RA treatment. Data on current clinical drugs for RA treatment were extracted from the US Food and Drugs Administration (FDA) website. Candidate targets of RA were extracted from three online databases: Drugbank, Therapeutic Target Database (TTD) and Potential Drug Target Database (PDTD). A total of 95 clinical protein targets for RA have been identified and were analysed using the PANTHER Classification System. According to the PANTHER analysis, most commonly involved pathways in current RA targeting includes inflammation mediated by chemokine and cytokine signalling pathways, angiogenesis, p53 pathway, de novo purine biosynthesis, T-cell activation, apoptosis signalling pathway and vascular endothelial growth factor (VEGF) receptor signalling pathway. Accordingly, current clinical agents for the treatment of RA mainly include corticosteroids, non-steriodal anti-inflammatory drugs (NSAIDs) and disease-modifying antirheumatic drugs (DMARDs). In addition, a number of investigational targets for RA have been identified and many novel drugs for RA therapy are under investigation. Current approaches to handle RA aim to ameliorate inflammation, to relieve pain, and most importantly to protect the cartilage, joints and bones from further damage by blocking proinflammatory molecules and inhibit the production of matrix-degrading factors. New drugs for RA with improved efficacy and safety should be developed.