Oral and systemic butyrate supplementation reduces mortality and bacterial dissemination in Western-type diet (WD)+acute necrotising pancreatitis (ANP) mice. (A) Butyrate was supplemented either preoperatively in the drinking water (BUTDW, 100 mM) for 4 weeks or systemically with intraperitoneal injections (BUTIP, 40 mM, 500 µL) at 0, 7 and 14 hours postoperatively. (B) Kaplan-Meijer survival curves demonstrating significantly reduced mortality with both oral (WD+ANP+BUTDW, n=9, p=0.002) and systemic (WD+ANP+BUTIP, n=14, p=0.019) butyrate supplementation. Survival curves are analysed using log-rank test. (C) Serum endotoxin levels are significantly attenuated by BUTDW (n=5, p=0.003 by Mann-Whitney) and BUTIP (n=5, p=0.012 by unpaired t-test) (D, E) Culture analysis of blood (D) and pancreas (E). p=0.016 of Gram-negative bacteria in BUTIP versus vehicle (VEH) and p=0.028 in BUTDW versus VEH in blood (D). p=0.012 of Gram-negative bacteria in BUTIP versus VEH, and p=0.088 in BUTIP versus VEH in pancreas (E). (F) Expression of tight junction genes indicates increased expression of CLDN1 (n=5, p=0.016) and CHD1 (p=0.032) in the cecum tissue of BUTDW mice versus the untreated control group (WD+ANP). (G) 16S rRNA analysis of relative abundance. Relative abundance at the phylum level demonstrating depletion of Proteobacteria in the BUTDW group to the level of WD+VEH (p=0.008 vs WD+ANP in cecum lumen). Depletion of Proteobacteria was also observed in WD+ANP+BUTIP mice but did not reach statistical significance. *p<0.05; **p<0.01; ns, not statistically significant.