Suppression of MyD88 disturbs gut microbiota and activates the NLR pathway and hence fails to ameliorate DSS-induced colitis

Abstract

Background: Myeloid differentiation factor 88 (MyD88) is the core adaptor for Toll-like receptors defending against microbial invasion and initiating a downstream immune response during microbiota-host interaction. However, the role of MyD88 in the pathogenesis of inflammatory bowel disease is controversial. This study aims to investigate the impact of MyD88 on intestinal inflammation and the underlying mechanism.

Methods: MyD88 knockout (MyD88^−/−) mice and the MyD88 inhibitor (TJ-M2010-5) were used to investigate the impact of MyD88 on acute dextran sodium sulfate (DSS)-induced colitis. Disease activity index, colon length, histological score, and inflammatory cytokines were examined to evaluate the severity of colitis. RNA transcriptome analysis and 16S rDNA sequencing were used to detect the potential mechanism.

Results: In an acute DSS-colitis model, the severity of colitis was not alleviated in MyD88^−/− mice and TJ-M2010-5-treated mice, despite significantly lower levels of NF-κB activation being exhibited compared to control mice. Meanwhile, 16S rDNA sequencing and RNA transcriptome analysis revealed a higher abundance of intestinal Proteobacteria and an up-regulation of the nucleotide oligomerization domain-like receptors (NLRs) signaling pathway in colitis mice following MyD88 suppression. Further blockade of the NLRs signaling pathway or elimination of gut microbiota with broad-spectrum antibiotics in DSS-induced colitis mice treated with TJ-M2010-5 ameliorated the disease severity, which was not improved solely by MyD88 inhibition. After treatment with broad-spectrum antibiotics, downregulation of the NLR signaling pathway was observed.

Conclusion: Our study suggests that the suppression of MyD88 might be associated with unfavorable changes in the composition of gut microbiota, leading to NLR-mediated immune activation and intestinal inflammation.

Keywords

microbiota / innate immunity / myeloid differentiation factor 88 / MyD88 inhibitor / NOD-like receptor / inflammatory bowel disease

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant Nos. 81873556 and 82170546 to FX), China Crohn's & Colitis Foundation (Grant No. CCCF-QF-2022B67-3 to FX), and the Tongji Hospital Clinical Research Flagship Program (Grant No. 2019CR209 to DT). We thank Prof. Ping Zhou for providing the inhibitor of MyD88 TJ-M2010-5 (TJ5).

Author contributions

Y.C., J.L., and Z.Y. contributed equally to this work and share first authorship. Y.C., Z.Y., J.X., J.H., J.L., L.C., and F.X. performed experiments; L.X. and S.X. studied the properties of the MyD88 inhibitor TJ-M2010-5; Y.C., Z.Y., L.C., J.H., J.L., L.X., and S.X. analyzed data; Y.C., J.L., F.X., and J.Z.L. wrote the manuscript; U.S., J.Z.L., and F.X. supervised parts of the project and reviewed the paper; F.X. designed the study; F.X. and D.T. obtained funding for the project. All authors read and approved the manuscript.

Supplementary data

Supplementary data are available at PCMEDI Journal online.

Conflict of interest

None declared.

Ethics approval and consent to participate

All experimental involving animals were conducted according to ethical policies and procedures were approved by the Institute Animal Care and Use Committee at the Tongji Hospital, Wuhan, China (Approval no. TJH-201901004).

Data availability

The datasets supporting the conclusions of this article are included within the article and the sequencing data in this study are available in the NCBI online repository (https://www.ncbi.nlm.nih.gov/, accession numbers: PRJNA904645 and PRJNA904649).

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