Journal of Shanghai Jiao Tong University (Medical Science) ›› 2022, Vol. 42 ›› Issue (9): 1188-1196.doi: 10.3969/j.issn.1674-8115.2022.09.005

• Innovative research team achievement column • Previous Articles    

Immune inhibitory receptor LILRB2 enhances SARS-CoV-2 spike protein-mediated immune inflammation

YANG Wenqian1(), CHEN Chiqi1(), ZHAO Lu1, CAO Liyuan1, XIA Yiqiu1, LU Zhigang2(), ZHENG Junke1()   

  1. 1.Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
    2.Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
  • Received:2022-06-13 Accepted:2022-08-21 Online:2022-09-28 Published:2022-09-28
  • Contact: LU Zhigang,ZHENG Junke;;
  • Supported by:
    National Natural Science Foundation of China(81825001);Scientific Project of Science and Technology Commission of Shanghai Municipality(19XD1422100)


Objective ·To explore the possible roles of immune inhibitory receptor leukocyte immunoglobulin-like receptor subfamily B member 2 (LILRB2) in the immune inflammation after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and provide a potential therapeutic way for the coronavirus disease 2019 (COVID-19). Methods ·The supernatants containing the extracellular domain of spike protein (S-ECD) were collected, and the detection of the protein expression and activity in the conditional medium by Western blotting and flow cytometric analysis was followed by. The binding of S-ECD with LILRB2 was measured by co-immunoprecipitation and flow cytometric analysis. The mRNA expression levels of several inflammation genes in a human mononuclear cell line (THP1) or peripheral blood mononuclear cells (PBMC) were measured after spike protein stimulation for 24 h by quantitative RT-PCR. The protein levels of interleukin-6 (IL-6) and interleukin-1β (IL-1β) in the conditional medium were examined by enzyme-linked immunosorbent assay (ELISA). The siLILRB2 was transferred into CD33+ myeloid cells purified from human peripheral blood with Lipofectamine 3000 reagents. The knockdown efficiency was detected 24 h after transfection by flow cytometric analysis. The difference in the protein levels of IL-6 between the control cells and LILRB2-knocked-down cells after spike protein treatment was evaluated by ELISA. Results ·The study established a transfection system with 293T cells by which the SARS-CoV-2 S-ECD could be secreted to supernatants with normal biological activities. The interaction and the binding of spike protein with LILRB2 were evaluated by a co-immunoprecipitation assay and flow cytometric analysis, respectively. The mRNA expression levels of IL-6, IL-8, arginase 1 and IL-2 in THP1 cells were significantly up-regulated 24 h after spike protein treatment compared to the control cells (all P<0.05). Consistently, the mRNA levels of IL-6, transforming growth factor-β(TGF-β), IL-8, IL-10 and IL-1β in PBMC were notably increased after spike protein stimulation (all P<0.05). In addition, spike protein could also induce the release of IL-6 and IL-1β in PBMC as measured by ELISA (all P<0.05). More importantly, spike protein was able to increase the secretion of IL-1β and IL-6 by CD33+ myeloid cells 24 h after treatment (both P<0.05). LILRB2-overexpressing THP1 cells produced more IL-6 24 h after treatment with spike protein than the control cells (P<0.05). Two siRNAs could efficiently down-regulate the expression of LILRB2 in CD33+ cells as evaluated by flow cytometric analysis. Consistently, spike protein had no effect on the IL-6 secretion to supernatant from LILRB2-knockdown CD33+ myeloid cells. Conclusion ·SARS-CoV-2 can induce cytokine release syndrome by inflammatory factors, such as IL-6 and IL-1β, released by myeloid cells through spike protein binding to LILRB2.

Key words: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), spike protein, leukocyte immunoglobulin-like receptor subfamily B member 2 (LILRB2), inflammatory cytokine, myeloid cell

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