O2199: Oral Delivery of Cerium Oxide Nanoparticle Conjugated to miR-146a Attenuates Inflammation in 2,4,6-Trinitrobenzenesulfonic Acid-Induced Colitis Model

Background: Inflammatory bowel disease (IBD) is a complex and relapsing chronic disease affecting ~2.5 million individuals nationally without a definitive cure. We have previously shown that enema delivery of a novel nanoparticle compound (CNP-miR146a) with anti-oxidative and anti-inflammatory properties decreases clinical disease activity and inflammation in 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis model of Crohn's disease. In vitro study demonstrated that CNP-miR146a is stable when exposed to acidic conditions. Given these findings, we hypothesize that oral administration of CNP-miR146a at varying doses will mitigate the inflammatory response in TNBS-induced colitis in a dose-dependent manner.

Methods: Colitis was induced in Balb/c mice using a 2.5% TNBS enema (75 mg/kg). Control mice received an equal amount of 50% ethanol enema. Four treatment groups were included in this study: Control + normal saline (NS), Colitis + NS, Colitis + 25ng CNP-miR146a, and Colitis + 50ng CNP-miR146a. Mice demonstrating clinical signs of colitis with 10% weight loss were included. After 48 hours, the controls received oral gavage of 200ul of normal saline (NS), whereas the TNBS-colitis groups received 200ul of either NS or CNP-miR146a for three days. On day 6, the mice were euthanized, and their colons were harvested for gene expression using qPCR. The data was analyzed using one-way ANOVA with an alpha value of 0.05 for statistical significance.

Results: Our data demonstrated that colitis + 25ng CNP-miR146a and colitis + 50ng CNP-miR146a treated groups demonstrated significant reduction in weight loss from day 3 (p=0.0246, p=0.0068), day 4 (p=0.0662, p=0.0067), and day 5 (p=0.1366, p=0.0102) compared to colitis + NS treated group. There is a reduction in gene expression of pro-inflammatory cytokine IL-6 (p=0.0456, p=0.0179), TNF-a (p=0.0887, p=0.0055) and inducible nitric oxide synthase (NOS2) (p < 0.0001, p=0.0005) in the colitis + 25ng CNP-miR146a and colitis + 50ng CNP-miR146a treated groups, respectively, compared to colitis + NS treated group. The expression of miR-146a was upregulated in the colitis + 50ng CNP-miR146a treated group compared to colitis + 25ng CNP-miR146a and colitis + NS groups (p < 0.0001).

Conclusion: Orally delivered CNP-miR146a showed promising efficacy in the TNBS-induced colitis model, with the higher dose resulting in a robust reduction in pro-inflammatory and oxidative stress markers implicated in IBD pathophysiology. This highlights the potential therapeutic benefits of the nanoparticle in treating IBD.