R. G. Ramos1, M. Rogers1,2, A. Yeh1,2, J. Tian1,2, B. Firek1,2, E. Novak1,2, K. Mollen1,2, M. Morowitz1,2 1University Of Pittsburg,Surgery,Pittsburgh, PA, USA 2Children’s Hospital Of Pittsburgh Of UPMC,Pediatric Surgery,Pittsburgh, PA, USA
Introduction:
The beneficial effects of a high fiber diet on epithelial integrity, immune reactivity, and bacterial diversity have been well documented in the medical literature. Previously we have shown that when compared to standard mouse chow or conventional enteral nutrition (CEN), plant based enteral nutrition (PBEN) formulas significantly decrease disease activity in murine colitis models. To define the mechanisms underlying this beneficial effect, we utilize RNA Seq to compare colonic gene expression in mice with colitis on different nutritional regimens.
Methods:
Four groups of four C57BL6 male mice each were fed regular mouse chow, PBEN (Liquid Hope), CEN1 (PediaSure), or CEN2 (Vital) for 7 days. On day 8, 2% dextran sodium sulfate (DSS) was started. On day 12, mice were sacrificed and colon was preserved for RNA-seq analysis. Colonic gene expression was characterized with RNA-seq and reference matched with KEGG. R software with vegan package was used for analysis. False discovery rate (FDR) was used to adjust for multiple hypothesis testing, logarithmic fold change (LFC) was used to measure effect size, statistical significance was defined as a p value < .05.
Results:
As we have seen previously, weight loss and disease activity scores were significantly lower in PBEN animals (see figure). RNA Seq of whole colon tissue from each dietary group demonstrated a statistically significant change in transcription of the following pathways in the PBEN colitis group: interleukin 17 (IL-17) and tumor necrosis factor α (TNF-α ) signaling, vitamin A metabolism, nucleotide binding oligomerization domain domain-like receptors (NOD), and inflammatory bowel disease (IBD) associated pathways. A twofold change in expression levels was identified in the following pathways with LFC, upregulated genes include: Gasdermin-C4 (Gsdmc4), antigen peptide transporter 1 (Tap1), aldehyde dehydrogenase family 1 subfamily A2 (Ald1a2), UDP-Glucuronosyltransferase-2B7 (UGT2B7), members of major histocompatibility complex II (MHC), signal transducer and activator of transcription 1 (STAT1), capase 1 (Casp1), caspase 4 (Casp4), and mitofusin 2 (Mfn2). Downregulated genes include: TNF ligand superfamily member 11 and 14 (RANKL and LIGHT), IL-17 receptor A (IL17RA), interleukin 1 beta (IL-1β ) and interleukin 6 (IL-6).
Conclusion:
The downregulated TNF-α signaling (RANKL and LIGHT) and IL-17 signaling (IL17RA, IL-1β and IL-6) pathways, along with the upregulated vitamin A metabolism (Ald1a2 and UGT2B7), IBD (MHC II and STAT1) and NOD (Casp1, Casp4, and Mfn2) pathways offer a biologically plausible explanation of the molecular mechanisms underlying PBEN’s beneficial effects on epithelial integrity and inflammation.
