Dr. Nataniel Białas (Essen, DE), Elena K. Müller (Jena, DE), Prof. Dr. Ingrid Hilger (Jena, DE), Prof. Dr. Matthias Epple (Essen, DE)
Abstract text (incl. figure legends and references)
Introduction
Ulcerative colitis (UC) is a type of inflammatory bowel disease that affects the colon and rectum. UC causes abdominal pain, diarrhea and bloody stools, and, if chronic, it is a risk factor for colorectal cancer. NF-ĸB proteins are potent players in UC progression. Their regulation remains a challenge due to their intracellular localization. siRNA-carrying calcium phosphate nanoparticles target the p65 subunit of NF-ĸB on site and thus achieve NF-ĸB suppression and a therapeutic effect in vivo.
Objectives
The goal was to synthesize calcium phosphate nanoparticles loaded with anti-p65 NF-ĸB siRNA, and to study their in vivo efficiency in NF-ĸB downregulation in an UC mouse model.
Materials & methods
Calcium phosphate nanoparticles were stabilized with fluorescent polyethyleneimine (PEI-Dy734), loaded with anti-p65 NF-ĸB siRNA, purified and characterized in depth. The nanoparticles were injected intravenously into mice with DSS-induced UC or healthy ones (as control). In the studied animals we determined the UC features, the expression of NF-κB-associated proteins, pro-inflammatory local and systemic mediator secretion, and the organ leukocyte count in tissue sections. Furthermore, we performed NIR-studies on nanoparticle biodistribution.
Results
The nanoparticles were colloidally stable, efficiently loaded with therapeutic siRNA and met all quality criteria to be applied in in vivo studies. The nanoparticles effectively alleviated UC symptoms by suppressing the expression of NF-κB proteins in the colon. Consequently, they attenuated the secretion of pro-inflammatory mediators and the leukocyte load of spleen and mesenteric lymph nodes. The nanoparticle biodistribution in diseased animals was particularly strong in organs containing lymphoids.
Conclusion
siRNA-loaded calcium phosphate nanoparticles were effective in downregulating the symptoms of UC, and demonstrated biocompatibility and promising properties for the treatment of UC in the future.