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cFLIPS regulates alternative NLRP3 inflammasome activation in human monocytes

Cellular & Molecular Immunology volume 20, pages 1203–1215 (2023)Cite this article

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Abstract

The innate immune responses, including inflammasome activation, are paramount for host defense against pathogen infection. In contrast to canonical and noncanonical inflammasome activation, in this study, heat-killed gram-negative bacteria (HK bacteria) were identified as single-step stimulators of the NLRP3 inflammasome in human monocytes, and they caused a moderate amount of IL-1β to be released from cells. Time course experiments showed that this alternative inflammasome response was finished within a few hours. Further analysis showed that the intrinsically limited NLRP3 inflammasome activation response was due to the negative regulation of caspase-8 by the short isoform of cFLIP (cFLIPs), which was activated by NF-κB. In contrast, overexpressed cFLIPS, but not overexpressed cFLIPL, inhibited the activation of caspase-8 and the release of IL-1β in response to HK bacteria infection in human monocytes. Furthermore, we demonstrated that TAK1 activity mediated the expression of cFLIPs and was upstream and essential for the caspase-8 cleavage induced by HK bacteria in human monocytes. The functional specificity of cFLIPs and TAK1 revealed unique responses of human monocytes to a noninvasive pathogen, providing novel insights into an alternative regulatory pathway of NLRP3 inflammasome activation.

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Acknowledgements

We thank Qiuhong Guo and Xu Zheng for their experimental support. This study is supported by grants from the Natural Science Foundation of China (81830049, 92269202), National Key R&D Program (2022YFC2304700, 2022YFC2303200, 2018YFA0507300), Strategic Priority Research Program (XDB29030303) and International Partnership Program (153831KYSB20190008) of the Chinese Academy of Sciences, Shanghai Municipal Science and Technology Major Project (2019SHZDZX02) and Research Leader Program (20XD1403900), as well as the Innovation Capacity Building Project of Jiangsu Province (BM2020019).

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Author notes

  1. Shi Yu

    Present address: Department of Basic Research, Guangzhou Laboratory, Guangzhou International Bio-Island, Guangzhou, 510005, Guangdong, China

  2. These authors contributed equally: Yuhui Gao, Shi Yu.

Authors and Affiliations

  1. School of Life Sciences, Shanghai University, Shanghai, 200444, China

    Yuhui Gao & Bin Wei

  2. The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, University of Chinese Academy of Sciences, Shanghai, 200031, China

    Yuhui Gao, Shi Yu, Mengdan Chen, Lei Pan & Guangxun Meng

  3. Shanghai Blood Center, Shanghai, 200051, China

    Xun Wang

  4. Pasteurien College, Soochow University, Suzhou, 215006, Jiangsu, China

    Lei Pan & Guangxun Meng

  5. Nanjing Advanced Academy of Life and Health, Nanjing, 211135, Jiangsu, China

    Guangxun Meng

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  1. Yuhui Gao
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SY and GM conceived the project. YG conducted most experiments; SY, MC, XW, LP, and BW helped with experiments and prepared critical reagents; YG, SY, and GM analyzed the data and wrote the manuscript.

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Correspondence to Bin Wei or Guangxun Meng.

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Gao, Y., Yu, S., Chen, M. et al. cFLIPS regulates alternative NLRP3 inflammasome activation in human monocytes. Cell Mol Immunol 20, 1203–1215 (2023). https://doi.org/10.1038/s41423-023-01077-y

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