To investigate the impact of colonic group 3 innate lymphoid cells (ILC3s) on intestinal barrier stress capability in mice fed with high-fat diet.

Twenty-four SPF male C57BL/6J mice were adaptively fed for 1 week and then randomly divided into 4 groups (n=6): blank control group (N-CON), SAP control group (N-SAP), high-fat diet control group (H-CON), and SAP high-fat diet group (H-SAP). N-CON and N-SAP received a normal diet, while H-CON and H-SAP were fed a high-fat diet for 21 weeks. In the SAP group, 20% Arg was injected intraperitoneally as stress stimulation to prepare the mouse SAP model, while an equal volume of saline was injected into the CON groups. After 48 hours of modeling, serum levels of TC, TG, AMY, LPS, TNF-α, IL-6 were measured by ELISA; pancreatic histopathology as well as lung and colon tissue morphology were observed using HE staining; flow cytometry was employed to analyze changes in the proportion of colonic ILC3s among lymphocytes and changes in the proportion of IL-22⁺ ILC3s among colonic ILC3s; immunofluorescence was conducted to detect UEA-Ⅰ and IL-22RA1 expression; Western blot was performed to measure Fut2 and IL-22RA1 protein expression levels.

Compared with the N-CON group, the H-CON group exhibited significantly increased levels of body weight, TG, TC, serum AMS, LPS, IL-6 and TNF-α (P<0.05), along with a significant decrease in the proportion of colon ILC3s in lymphocytes (P<0.05). The proportion of IL-22⁺ILC3s in the colon showed an increase (P>0.05), while the expressions of Fut2 and IL-22RA1 were decreased (P>0.05). The average fluorescence intensity of UEA-1 and IL-22RA1 slightly decreased (P>0.05). After stimulation with a 20% Arg stress in the N-SAP group compared to the N-CON group, there was a significant increase in serum AMS, LPS, IL-6 and TNF-a levels (P<0.05) and a significant decrease in the proportion of colon ILC3s in lymphocytes (P<0.05). The proportion of IL-22+ILC3s in the colon significantly increased (P<0.05), while protein expression of Fut2 and IL-22RA1 was increased as well (P>0.05). The average fluorescence intensity of UEA-I significantly decreased (P<0.05), but that for IL-22 RA1was increased (P>0.05). In comparison to the N-SAP group, the H-SAP group showed no significant changes regarding the proportions between colonic ILC3s and lymphocytes (P>0.05); however, the percentage of IL-22 ⁺ILC3s in colonic ILC3s was significantly increased (P>0.05), while the average fluorescence intensity of UEA-I was decreased significantly (P<0.05), and also the protein expression of Fut2 and IL-22 RA1 was increased (P>0.05).

The intestinal barrier stress capability of mice fed with high-fat diet is impaired, which may be related to the regulation of fucosylation by ILC3s in the colon.