D2.275 - Distinct Transcriptomic Responses Across Intestinal Segments in Egg Allergy Murine Model

Studies on food allergies largely rely on readouts from accessible peripheral samples, especially serum. Transcriptomic studies directly from the site of inflammation (gut) remain unexplored. We aim to establish an animal model to identify biological changes in the gut of healthy vs. allergic individuals.

Six-week-old, female Balb/c mice (n=8 per group) were sensitized with 3 subcutaneous injections of 1 mg Alhydrogel and 5 ug ovalbumin (OVA) once a week on day 1-15. From day 19-28, the mice received oral challenges every third day with 40 mg OVA and were monitored for 30 min each time for stool activity and rectal temperatures. On day 29, sera were collected for OVA-specific IgE measurements with ELISA, and tissue sections from colon, ileum, and jejunum were harvested for RNA isolation and sequencing. Differentially expressed genes (DEGs) were identified via Metaboanalyst and subsequent pathway analyses were performed on Ingenuity Pathway Analysis (IPA).

Following oral challenges, OVA-sensitized mice experienced diarrhea and an average 5% drop in body temperature. In contrast, the control mice had normal stool activity and increased body temperature during the monitoring period. We managed to induce OVA-specific IgE antibodies in all sensitized mice, whereas none was detectable in control mice. Most DEGs were identified in jejunum (n=338), followed by ileum (n=156) and colon (n=128). The majority of DEGs in ileum (79.5%) and jejunum (67.8%) of sensitized mice were upregulated, as opposed to downregulation for most DEGs found in colon (85.2%). The most significantly enriched pathways in ileum, jejunum, and colon were Macrophage-Stimulating Protein (MSP)-RON signaling, integrin cell surface interactions, and B-cell development, respectively. In addition to elevated IL-33 and wound healing pathways, we detected increased activity in leukocyte migration and recruitment in both ileum and jejunum.

We established an animal model using a robust protocol for egg allergy and analyzed their gut-specific responses during sensitization and the subsequent allergic reaction phase. Our findings suggest that each gut section reacts uniquely to allergen exposure and this might give insight into targeted therapeutic treatment for food allergies.