Preoperative Dietary Rehab Reduces the Risk of Lethal Gut Derived Sepsis

Author(s):
Emily Papazian; Robert Keskey; Alexander Zaborin; Olga Zaborina; John Alverdy

Background:

The intestinal microbiota play an essential role in the host immune response to stress and infection. The intestinal microbiota of surgical patients are exposed to extreme stress including but not limited to antibiotics, starvation and the surgical injury itself. The extent to which an altered microbiome predisposes patients to postoperative sepsis remains to be clarified.

Hypothesis:

A high fat Western-type diet (polyunsaturated fatty acid diet (PUFA)) predisposes mice to lethal sepsis following an otherwise recoverable surgical injury and can be reversed by short term exposure to a low-fat diet/high fiber diet.

Methods:

In two separate experiments, 6-week-old C57/B6 mice (n=13) were fed PUFA diet versus standard mouse chow (n=6) for 6 weeks and weights monitored. At the 6-week time point, mice were placed on a 5-day antibiotic regimen and underwent a 30% hepatectomy after remaining NPO for 12 hours. In a separate experiment, mice feeding on PUFA for 6 weeks were allowed standard chow diet ad libitum for 1 week (n=8) or 3 days (n=17) prior to the start of antibiotics. After transitioning diets, preoperative microbiome composition of expelled feces was determined by 16S rRNA. Post-operative recovery was monitored for signs of sepsis and scored 1-6 (5 = moribund and 6 = death between assessments). Cecal contents were used to determine microbiota metabolic profile with Biolog Phenotype Microarrays. TUNEL staining was performed on postop cecal tissue to evaluate intestinal epithelial biomarkers.

Results:

Mice feeding on PUFA developed a significant increase in postop lethal sepsis compared to chow fed mice (sepsis score PUFA=5.25, Chow= 1.17, p < 0.001). Mice transitioned to chow for 1 week prior antibiotics/hepatectomy (PUFA +1w Chow), had 100 % survival. Mice on chow 3d prior to antibiotics/hepatectomy (PUFA +3d Chow) showed improved survival by 63%.  A bloom of Proteobacteria was observed in PUFA mice as compared to complete absence in Chow and 1wk Chow fed mice along with significant attenuation in PUFA +3d Chow. There was a significant difference in Firmicutes to Bacteroidetes (F:B) ratio between the groups with a higher F:B ratio in the PUFA group (p < 0.001). Cecal tissue in the PUFA +3d Chow mice had less apoptosis in the crypt base compared to PUFA mice (p<0.001). PUFA +3d Chow mice demonstrated recovery of their anaerobic metabolic profile back to metabolic profile similar to Chow.

Conclusions:

PUFA diet induced severe dysbiosis and caused lethal sepsis in mice following an otherwise recoverable surgical injury. Preoperative rehabilitation with only 3 days of chow feeding had a significant impact on survival in PUFA fed mice that correlated to positive changes in the microbiota and epithelium.