AIM:To investigate whether oral tolerance is inducible during the active phase of dextran sulfate sodium (DSS)-induced colitis.
METHODS:Colitis was induced in 6-to 8-wk-old female BALB/c mice by the administration of 2% DSS. To induce oral tolerance, mice that received water with DSS [DSS (+)] and mice that received autoclaved water [DSS (-) Hiroshi Takahashi, Division of Gastroenterology, Department of Internal Medicine, Showa University, Yokohama 227-8501, JapanAuthor contributions: Ino S, Kohda C and Takeshima K performed the majority of experiments and analyzed the data; Norose T, Yamochi T and Takimoto M contributed pathological analysis; Kohda C, Ishikawa H, Takahashi H and Tanaka K designed and coordinated the research; Ino S and Kohda C wrote the paper.Institutional review board statement: All procedures involving experimental animals were approved by the Institutional Animal Care and Use Committee of Showa University (Permit Number: 04127) and complied with the Guide for the Care and Use of Laboratory Animals (7 th and 8 th edition, ILAR-NRC). In our facility, the Animal Care and Use Committee of Showa University also functions as an Institutional Review Board for animal experiments.Institutional animal care and use committee statement: All procedures involving experimental animals were approved by the Institutional Animal Care and Use Committee of Showa University (Permit Number: 04127) and complied with the Guide for the Care and Use of Laboratory Animals (7 th and 8 th edition, ILAR-NRC).
Conflict-of-interest statement:To the best of our knowledge, no conflict of interest exists.Data sharing statement: A technical appendix, statistical code, and dataset are available from the corresponding author at kohda@med.showa-u.ac.jp. All participants provided informed consent for data sharing.
ORIGINAL ARTICLE
Foxp3+ cell and B10 cell frequencies were evaluated using flow cytometry. Cytokine mRNA expression profiles were evaluated by reverse transcription real-time polymerase chain reaction.
RESULTS:Regardless of the presence of DSS colitis, OVA-specific immunoglobulin E concentrations were significantly reduced in mice that were i.g. administered OVA compared to mice that were i.g. administered PBS[DSS (+): 4.4 (4.2-9.5) ng/mL vs 83.9 (66.1-123.2) ng/mL, P < 0.01; DSS (-): 27.7 (0.1-54.5) ng/mL vs 116.5 (80.6-213.6) ng/mL, P < 0.01]. These results demonstrated that oral tolerance was induced in both the presence and absence of colitis. In the spleen and mesenteric lymph nodes (MLN), the frequencies of CD4 + CD25 + Foxp3 + cells and B10 cells, both of which are associated with oral tolerance, did not significantly change. In the spleen, interferon-γ mRNA expression significantly decreased in mice with colitis [DSS (+): 0.42 (0.31-0.53) vs DSS (-): 1.00 (0.84-1.39), P < 0.01]. The expression levels of other cytokines did not significantly change.
CONCLUSION:Oral tolerance is inducible during active DSS colitis. The stability of regulatory cell populations in the spleen and MLN in colitis might correla...