Obesity is an established risk factor for many diseases including
intestinal cancer. One of the responsible mechanisms is the chronic
inflammation driven by
obesity. However, it remains to be defined whether diet-induced
obesity exacerbates the intestinal inflammatory status by
cytokines produced in adipose tissue or the high fat diet first alters the gut microbiota and then drives intestinal
inflammation. To address this question, we fed C57BL/6 mice with a high fat diet (HF, 60%) and sacrificed them sequentially after 8, 12, and 16 weeks, and then compositions of gut microbiota and expressions of
antimicrobial peptides were determined. The compositions of gut microbiota were altered at 8 wk HF feeding, followed with reduced Paneth
antimicrobial peptides lysozyme and Reg IIIγ after 12 and 16 wk HF feeding (p < 0.05), whereas elevations of circulating inflammatory
cytokines IFNγ and TNF-α were observed until feeding a HF diet for 16 weeks (p < 0.05). These results indicated that high fat diet may stimulate intestinal
inflammation via altering gut microbiota, and it occurs prior to the potential influence by circulating inflammatory
cytokines. These findings emphasized the importance of microbiota, in addition to adipose tissue per se, in driving intestinal
inflammation, which may thereafter promote intestinal
tumorigenesis.