Changes in intestinal gene expression in antibiotic-treated NOD mice

Nicole Altomare, BS, Xue-Song Zhang, PhD, and Martin J. Blaser, MD
Robert Wood Johnson Medical School, Piscataway, NJ; Center for Advanced Biology and Medicine, Piscataway, NJ

Objective: We sought to understand how intestinal gene expression is affected following antibiotic treatment in non-obese diabetic (NOD) mice and to correlate this to the timing of Type 1 diabetes (T1D) onset.

Methods: Samples were obtained from control mice, NOD mice treated with PAT (one course of the macrolide antibiotic tylosin), and from NOD mice treated with PAT given a gavage of their mother’s cecal microbiome. Ileal and colonic samples were obtained at day of life 23 and 42. RNA was extracted, converted to cDNA, and expression was analyzed using RT-qPCR. A total protein assay and ELISA were performed to examine levels of expression of genes involved in host defenses antimicrobial peptides (REG3-γ), G protein-coupled trypsin receptor (F2RL1) and a tight junction molecule (zonulin).

Results:  For REG3-γ, there was a significant decrease in ileal expression between the control and the treatment groups and between the restoration and treatment groups at day 23. The difference between the control and treatment group remained significant at day 42. No significance was found in the colon samples. For F2RL1, no significance was found in the ileal samples. The colon showed a significant decrease between the control and (PAT) treatment group at day 23, which remained at day 42. For zonulin, there were no significant changes in expression within either the ileal or colonic samples.

Conclusions: We conclude that antibiotic exposure and restoration impacted ileal expression of REG3-γ and colonic expression of F2RL1, perhaps because of greater trypsin activity in the intestine, as shown in other studies. These changes may play a role in the earlier onset of T1D in the antibiotic-treated NOD mice. Zonulin expression was not affected by the antibiotic course, providing evidence that the observed dysbiosis did not affect the tight junctions.