The role of diet‐induced obesity on Peyer's Patch gene expression

Abstract

Peyer’s Patches (PP) are part of the complex gut‐associated lymphoid tissue located throughout the intestinal wall. PP consists of highly organized ovoid‐shaped follicles, classified as non‐encapsulated lymphatic tissues. PP are populated with B cells, T cells, macrophages and dendritic cells allowing them to function as an organism’s internal surveillance of the intestine. There is limited research on PP in relation to diet‐induced obesity. In the current study, we attempt to close this gap in knowledge. We placed male, Long Evans rats on Chow or high‐fat diet (HFD) for 8 weeks and harvested PP from the small intestine. HFD‐fed rats had significantly increased number of total PP, p<0.05. All rats had significantly reduced number of PP in the duodenum in comparison to either the jejunum or ileum, p<0.0001. We performed gene expression analysis for immune cell markers in mRNA obtained from individual PP in the 3 distinct regions of the intestine. Expression of T cell markers CD4/CD3 was differentially reduced in PP from the distal intestine in comparison to the proximal. Macrophage marker, CD68, was more highly expressed in the duodenum in comparison to the more distal PP. Master regulator of T cell expression, TGFβ, is more highly expressed in duodenal PP in comparison to ileal PP, p<0.05. In summary, gene expression of immune cell markers was most highly associated with the location of the intestinal PP. Surprisingly, HFD did not influence gene expression of immune markers in the PP as was predicted. Further work is necessary to understand whether other inflammatory markers are affected by obesity.