Anti-11[E]-pyroglutamate-modified amyloid β antibodies cross-react with other pathological Aβ species: Relevance for immunotherapy Roxanna Perez-Garmendia a , Vanessa Ibarra-Bracamontes a , Vitaly Vasilevko b , Jose Luna-Muñoz c , Raul Mena c , Tzipe Govezensky a , Gonzalo Acero a , Karen Manoutcharian a , David H. Cribbs b,d , Goar Gevorkian a, ⁎ a Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), AP 70228, Cuidad Universitaria, México DF, 04510, Mexico b The Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697-4540, USA c Department of Neurosciences, CINVESTAV-IPN, Mexico, DF, Mexico d Department of Neurology, University of California Irvine, Irvine, CA 92697-4540, USA abstract article info Article history: Received 2 June 2010 Received in revised form 24 August 2010 Accepted 26 August 2010 Keywords: N-truncated amyloid beta (Aß) peptide Alzheimer's disease immunotherapy Immunodominant epitope B cell epitope N-truncated/modified forms of amyloid beta (Aß) peptide are found in diffused and dense core plaques in Alzheimer's disease (AD) and Down's syndrome patients as well as animal models of AD, and represent highly desirable therapeutic targets. In the present study we have focused on N-truncated/modified Aβ peptide bearing amino-terminal pyroglutamate at position 11 (AβN11(pE)). We identified two B-cell epitopes recognized by rabbit anti-AβN11(pE) polyclonal antibodies. Interestingly, rabbit anti-AβN11(pE) polyclonal antibodies bound also to full-length Aβ1-42 and N-truncated/modified AβN3(pE), suggesting that the three peptides may share a common B-cell epitope. Importantly, rabbit anti-AβN11(pE) antibodies bound to naturally occurring Aβ aggregates present in brain samples from AD patients. These results are potentially important for developing novel immunogens for targeting N-truncated/modified Aβ aggregates as well, since the most commonly used immunogens in the majority of vaccine studies have been shown to induce antibodies that recognize the N-terminal immunodominant epitope (EFRH) of the full length Aβ, which is absent in N-amino truncated peptides. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The accumulation of fibrillar and oligomeric forms of amyloid-beta (Aβ) peptide in the brain has been hypothesized to play a central role in the neuropathology of Alzheimer's Disease (AD) (Haas and Selkoe, 2007; Masters et al., 1985; Walsh and Selkoe, 2004). The main Aβ variants detected in the human brain are Aβ1-40 and Aβ1-42, however a significant proportion of AD brain Aβ consists also of N-terminal truncated/modified species (Guntert et al., 2006; Mori et al., 1992; Saido et al., 1995; Seubert et al., 1992; Tekirian et al., 1998; Wirths et al., 2010). Previous studies have demonstrated that these shortened Aβ forms are significantly more resistant to degradation, aggregate more rapidly in vitro and exhibit similar or, in some cases, increased toxicity in hippocampal neuronal cultures compared to the full-length peptides (D'Arrigo et al., 2009; Pike et al., 1995; Russo et al., 2002; Schilling et al., 2006; Youssef et al., 2007). Also, it has been demonstrated that N- truncated Aβ peptides progressively accumulate in the brain of Familial Alzheimer's disease (FAD) and Down syndrome patients as well as in the brain of sporadic AD patients at the earliest stages of AD even before the appearance of clinical symptoms (Huse et al., 2002; Kumar-Singh et al., 2000; Liu et al., 2006; naslund et al., 1994; Piccini et al., 2005; Saido et al., 1995; Sergeant et al., 2003; Tekirian et al., 1998; Vanderstichele et al., 2005). In addition, the presence of intraneuronal pool of N-truncated Aβ peptides has been shown to correlate with the progression of pathology and neuronal loss in transgenic mice models APP/PS1KI and TBA2 (Bayer et al., 2008; Casas et al., 2004; Wirths et al., 2009). Thus, the N-terminally truncated/modified Aβ peptides represent highly desirable and abundant therapeutic targets. Most of N-truncated Aβ peptides have been considered to be the degradation products of full-length Aβ, however, the cloning and overexpression in cultured cells of β-site amyloid precursor protein- cleaving enzyme 1 (BACE1) led to the conclusion that Aβ11-40/42 may be generated intracellularly directly by BACE1 cleavage of APP (Huse et al., 2002; Lee et al., 2003; Liu et al., 2006; Vassar et al., 1999). This shortened form of Aβ peptide may be further modified by cyclization of the N-terminal glutamate resulting in a peptide bearing amino-terminal pyroglutamate at position 11 (AβN11(pE)). This modification protects the peptide from degradation by most amino- peptidases leading to its accumulation and aggregation. Journal of Neuroimmunology 229 (2010) 248–255 ⁎ Corresponding author. Tel.: + 52 5556223151; fax: + 52 5556223369. E-mail address: gokar@servidor.unam.mx (G. Gevorkian). 0165-5728/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jneuroim.2010.08.020 Contents lists available at ScienceDirect Journal of Neuroimmunology journal homepage: www.elsevier.com/locate/jneuroim