Inflammatory bowel diseases (IBDs) are comprised of two major disorders: Crohn's disease (CD) and ulcerative colitis (UC). No curative treatment options are available, but gene therapy may offer an alternative therapeutic approach. For this a safe and reliable vector is needed. The adeno-associated viruses (AAV) have attracted considerable interest as gene therapy vectors. However, neutralizing antibodies (nAb's) made in response to wildtype AAV have been associated with a partial to complete block of transduction in case of reexposure. Therefore, and in order to define AAV vector candidates to treat IBD patients, we characterized preexisting humoral responses to AAV in this population.
We measured circulating antibodies against AAV serotypes 1, 2, 3, 4, 5, 6, and 8 using a previously established virus neutralization assay. In all, 100 healthy donors and 200 IBD patient's serum samples (101 CD and 99 UC) were analyzed.
A significant difference was detected in the prevalence of nAb's for AAV types 1, 5, 6, and 8 between the healthy donors and the patient population. Furthermore, various disease phenotypic characteristics correlated with the prevalence of nAb's to all the serotypes studied.
Our study establishes a foundation for the development of an AAV-based gene therapy approach as a novel treatment for IBD. Furthermore, we show a relationship between disease phenotype in IBD patients and the humoral immune response to AAV.
1 Research and Development, Amsterdam Molecular Therapeutics (AMT) B.V., Amsterdam, the Netherlands
2 Department of Gastroenterology & Hepatology, Leiden University Medical Center, Leiden, the Netherlands
3 Department of Gastroenterology & Hepatology, Academic Medical Center, Amsterdam, the Netherlands
4 Tytgat Institute for Liver and Intestinal disease, Academic Medical Center, Amsterdam, the Netherlands
*Reprints: Research and Development, Amsterdam Molecular Therapeutics (AMT) B.V., Meibergdreef 61, 1105 BA Amsterdam, the Netherlands
Received 6 January 2011; Accepted 12 January 2011
Published online 2 March 2011 in Wiley Online Library (wileyonlinelibrary.com).
Grant sponsor: Broad Foundation; Grant Number: IBD-029 5R.
Conflict-of-interest disclosure: Three of the authors are employees of AMT (E.C., H.P., and V.S.). S.M. currently works in the lab of AMT. S.D. is a board member of AMT.
Sander van der Marel (S.M.) and Daniel W. Hommes (D.H.) are supported by a grand from the Broad Foundation (Proposal No. IBD-029 5R).