Fig. 4. Dex-P-laden NPA₂ coacervate demonstrates enhanced therapeutic efficacy in a rat model of DSS-induced colitis.

a, b SD rats were given 4.5% DSS in drinking water to induce acute colitis. The colitic rats received oral gavages of Dex-P-laden NPA₂ coacervates (Dex-P/NPA₂) or the equivalent amount of Dex-P in PBS (Dex-P/PBS) on days 1, 3, and 5. Untreated colitic SD rats were used as the negative control (Control). All SD rats were sacrificed on day 7. c, d Colonic edema and diarrhea caused by DSS-induced colitis in SD rats receiving Dex-P/NPA₂ were significantly relieved compared with that of the untreated colitic SD rats (Control) and colitic SD rats receiving Dex-P in PBS (Dex-P/PBS). n = 6 biologically independent rats per group. Scale bar: 10 mm. e Representative images of H&E staining demonstrated that histological inflammation was diminished in the colitic SD rats receiving Dex-P/NPA₂, while histological damages were observed in untreated colitic SD rats (Control) or colitic SD rats receiving Dex-P/PBS. Scale bar: 150 μm. f–i On day 7, colon tissues were analyzed for histopathology score f, MPO activity g, mRNA levels of tight junction-associated proteins including ZO-1 and occludin-1 h, and pro-inflammatory cytokines including interleukin IL-1β and TNF i. Data were presented as mean ± SD. n = 6 biologically independent rats per group. *p < 0.05, **p < 0.01, ***p < 0.001 (Ordinary one-way ANOVA). Source data are provided as a Source Data file for Fig. 4d, f–i.