AUTHOR=Cai Dongjie , Tian Bin , Liang Shuang , Cen Yao , Fang Jing , Ma Xiaoping , Zhong Zhijun , Ren Zhihua , Shen Liuhong , Gou Liping , Wang Ya , Zuo Zhicai 

TITLE=More Active Intestinal Immunity Developed by Obese Mice Than Non-Obese Mice After Challenged by Escherichia coli

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.851226

DOI=10.3389/fvets.2022.851226

ISSN=2297-1769

ABSTRACT=<p>Obese mice presented lower mortality to non-fatal pneumonia induced by <italic>Escherichia coli</italic> (<italic>E. coli</italic>) than the non-obese mice. However, it remained obscure whether the intestine contributed to the protective effect of obese mice with infection. The 64 non-obese (NOB) mice were divided into NOB-uninfected and NOB-<italic>E. coli</italic> groups, while 64 high-fat diet-induced obesity (DIO) mice were divided into DIO-uninfected and DIO-<italic>E. coli</italic> groups. Mice in <italic>E. coli</italic> groups were intranasally instilled with 40 μl <italic>E. coli</italic> (4.0 ×10<sup>9</sup> colony-forming units [CFUs]), while uninfected groups with the same volume of phosphate buffer saline (PBS). The T subsets of Intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) in the intestine were collected for flow cytometry analysis at 0, 12, 24, and 72 h post-infection, also the duodenum and colon were harvested to survey histopathological change. The results showed that the percentage of CD3<sup>+</sup>T cells in LPLs in DIO-<italic>E. coli</italic> group was significantly lower than that in the DIO-uninfected group after infection (<italic>p</italic> &lt; 0.05). The percentage of CD4<sup>+</sup>T cells in IELs in NOB-<italic>E. coli</italic> was significantly lower than that in DIO-<italic>E. coli</italic> after infection (<italic>p</italic> &lt; 0.05). The percentage of CD8<sup>+</sup>T cells in LPLs in NOB-<italic>E. coli</italic> was significantly lower than that in DIO-<italic>E. coli</italic> at 12 and 24 h (<italic>p</italic> &lt; 0.05). The immunoglobulin A (IgA)<sup>+</sup> cells in DIO-uninfected were higher than that in NOB-uninfected at all time points (<italic>p</italic> &lt; 0.05). The IgA<sup>+</sup> cells in DIO-<italic>E. coli</italic> were higher than that in DIO-uninfected at 12, 24, and 72 h (<italic>p</italic> &lt; 0.05). The results revealed that the level of intestinal mucosal immunity in obese mice was more active than that in non-obese mice.</p>