Animal Models of IBD: Pre-Clinical Treatment of Intestinal Inflammation
Bruno Sarmento, PhD
Principal Investigator
i3S . Instituto de Investigação e Inovação em Saúde, University of Porto
Porto, Porto, Portugal
The rising global prevalence of Inflammatory Bowel Disease (IBD) and its significant socio-economic impact highlight the urgent need to develop innovative solutions to overcome the poor targeting efficiency and short retention time faced by current treatments. Hence, the aim of this work was to use an advanced oxidative-responsive nanosystem to selectively target and accumulate at inflamed tissues for oral administration of budesonide, a corticosteroid used to treat intestinal inflammation. For this system, muco-diffusive poly(lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) were functionalized with a dense hydrophilic PEG corona. These PEG chains were anchored by a ROS-sensitive linker, which in the presence of oxidative environment was able to effectively shed PEG chains, exposing of the NPs hydrophobic surface. This smart de-PEGylation generated muco-static NPs, which could accumulate nearby the epithelial cells, releasing the cargo at the target, inflamed site. Budesonide-loaded oxidative-responsive PLGA NPs were obtained by nanoprecipitation with 101 ± 1 nm, 0.20 ± 0.01 polydispersity index, -1.04 ± 0.7 mV zeta potential and near 70 % association efficiency. Budesonide showed a sustained release over 48 h that reached 60% in the presence of ROS and only 40 % release in the absence of ROS. NPs showed no cytotoxic effects on Caco-2 clone cells and HT29-MTX epithelial cells from intestine nor macrophages differentiated from THP-1-monocytes. Using fluorescently-labelled NPs by both confocal imaging and flow cytometry, in 2D culture, a high NPs association ( > 60 %) with Caco-2 clone, HT29-MTX and THP-1 macrophages was confirmed. Multicellular 3D intestinal models, comprising the aforementioned cells together with human intestinal fibroblasts (HIF), and undergoing inflammatory response, were used as a tool for evaluating both the budesonide permeability through the intestinal mucosa and the anti-inflammatory potential. Minimal permeation was observed over 24 h incubation and no significant reduction of pro-inflammatory cytokines was observed, only a slight reduction in CCL20/MIP3a compared to no treatment. Oral administration of fluorescently-labelled ROS-sensitive NPs in 2 % DSS-induced colitis C57BL/6 mice improved NPs accumulation in the colon after 4 h, when compared with the non-sensitive NPs. Administration of Budesonide-loaded NPs over 5 consecutive days post DSS-induced colitis improved the appearance of the intestinal mucosa by colonoscopy, reduced the disease activity index (DAI), being also anticipated that it was associated with a reduction of pro-inflammatory cytokines in colon tissue and serum (undergoing analysis). Overall, this nanosystem is based on a mPEG-cleavable corona which is responsive to oxidative environment, altering NPs motility and being promising to improve the efficacy of budesonide in the treatment of IBD.