Antibodies that specifically bind polyethylene glycol (PEG) can lead to rapid elimination of PEGylated therapeutics from the systemic circulation. We have recently shown that virus-binding IgG can immobilize viruses in
mucus via multiple low-affinity crosslinks between IgG and mucins. However, it remains unclear whether anti-PEG antibodies in
mucus may also alter the penetration and consequently biodistribution of PEGylated nano
particles delivered to mucosal surfaces. We found that both anti-PEG IgG and IgM can readily bind nano
particles that were densely coated with PEG polymer to minimize adhesive interactions with
mucus constituents. Addition of anti-PEG IgG and IgM into mouse cervicovaginal
mucus resulted in extensive trapping of
mucus-
penetrating PEGylated nano
particles, with the fraction of mobile
particles reduced from over 95% to only 34% and 7% with anti-PEG IgG and IgM, respectively. Surprisingly, we did not observe significant agglutination induced by either antibody, suggesting that particle immobilization is caused by adhesive crosslinks between mucin fibers and IgG or IgM bound to individual nano
particles. Importantly, addition of corresponding control antibodies did not slow the PEGylated nano
particles, confirming anti-PEG antibodies specifically bound to and trapped the PEGylated nano
particles. Finally, we showed that trapped PEGylated nano
particles remained largely in the luminal
mucus layer of the mouse vagina even when delivered in hypotonic formulations that caused untrapped
particles to be drawn by the flow of water (advection) through
mucus all the way to the epithelial surface. These results underscore the potential importance of elucidating mucosal anti-PEG immune responses for PEGylated therapeutics and biomaterials applied to mucosal surfaces.
Statement of Significance
PEG, generally considered a ‘stealth’ polymer, is broadly used to improve the circulation times and therapeutic efficacy of nanomedicines. Nevertheless, there is increasing scientific evidence that demonstrates both animals and humans can generate PEG-specific antibodies. Here, we show that anti-PEG IgG and IgM can specifically immobilize otherwise freely diffusing PEG-coated nanoparticles in fresh vaginal mucus gel ex vivo by crosslinking nanoparticles to the mucin mesh, and consequently prevent PEG-coated nanoparticles from accessing the vaginal epithelium in vivo. Given the increasing use of PEG coatings to enhance nanoparticle penetration of mucosal barriers, our findings demonstrate that anti-PEG immunity may be a potential concern not only for systemic drug delivery but also for mucosal drug delivery.