Resolution of Periodontal Inflammation Promotes Changes in Cytokine Expression in the Intestine and Gingival Tissues of Aged Rats with DSS-induced Colitis

Our research aimed to explore how resolving periodontal inflammation impacts cytokine expression in the colon of aged Wistar rats. Animal studies have been used to investigate the two-way relationship between periodontitis and Inflammatory Bowel Disease (IBD), where chronic inflammation in either the mouth or intestines can negatively affect the other. We allocated sixteen male Wistar rats, aged between 8-11 months, into four groups: (1) Ligature-induced periodontitis (LIP) without the resolution of periodontal inflammation (RPI) (LIP; n=4), (2) LIP + RPI (n=4), (3) LIP + DSS-induced colitis (DIC) without RPI (n=4), and LIP+DIC+RPI (n=5). We performed histopathological and immunological analyses on the periodontal and intestinal tissues and analysed cytokine expressions using a Rat Cytokine 23-Plex Immunoassay. Our findings showed that animals with and without DIC who underwent RPI showed significantly lower levels of IL-2, IL-4, IL-5, IL-10, IL-13, IL-17, IL-18, and TNF-α in the intestine compared to those without treatment. The RPI effectively reduced the number of inflammatory cells in the lamina propria and restored the epithelial barrier in the intestine in animals with DIC. The resolution of periodontal inflammation significantly reduced the levels of pro-inflammatory cytokines and chemokines in the intestine of aged rats with and without DSS-induced colitis.