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Theranostics 2022; 12(6):2639-2657. doi:10.7150/thno.66831 This issue Cite

Research Paper

An engineered nano-liposome-human ACE2 decoy neutralizes SARS-CoV-2 Spike protein-induced inflammation in both murine and human macrophages

Sandro Satta^1*, Zhaojie Meng^2*, Rebecca Hernandez², Susana Cavallero¹, Tong Zhou³, Tzung K. Hsiai^1,4✉, Changcheng Zhou^2✉

1. Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA.
2. Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA.
3. Department of Physiology and Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV.
4. Department of Bioengineering, Henry Samueli School of Engineering & Applied Science, University of California, Los Angeles, CA.
*These authors contributed equally to this work.

✉ Corresponding authors: Dr. Changcheng Zhou, Division of Biomedical Sciences, School of Medicine, University of California, Riverside, 900 University Avenue, Riverside, CA 92521. E-mail: changcheng.zhouucr.edu; Dr. Tzung K. Hsiai, Department of Bioengineering, Department of Medicine (Cardiology), Schools of Engineering & Applied Science, University of California, Los Angeles, 10833 Le Conte Ave., CHS17-054A, Los Angeles, CA 90095-1679. E-mail: thsiaiucla.edu. More

Abstract

Rationale: Macrophages are the frontline immune cells in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Angiotensin-converting enzyme 2 (ACE2) serves as the binding receptor to SARS-CoV-2 Spike glycoprotein for fusion and internalization into the human host cells. However, the mechanisms underlying SARS-CoV-2-elicited macrophage inflammatory responses remain elusive. Neutralizing SARS-CoV-2 by human ACE2 (hACE2) decoys has been proposed as a therapeutic approach to ameliorate SARS-CoV-2-stimulated inflammation. This study aims to investigate whether an engineered decoy receptor can abrogate SARS-CoV-2-induced macrophage inflammation.

Methods: hACE2 was biotinylated to the surface of nano-liposomes (d = 100 nm) to generate Liposome-human ACE2 complex (Lipo-hACE2). Lentivirus expressing Spike protein (D614G) was also created as a pseudo-SARS-CoV-2 (Lenti-Spike). Liposome-hACE2 was used as a decoy receptor or competitive inhibitor to inhibit SARS-CoV-2 or Lenti-Spike-induced macrophage inflammation in vitro and in vivo.

Results: Both SARS-CoV-2 and Lenti-Spike stimulated strong inflammatory responses by inducing the expression of key cytokine and chemokines, including IL-1β, IL-6, TNFα, CCL-2, and CXCL-10, in murine and human macrophages in vitro, whereas Lipo-hACE2 decoy abolished these effects in macrophages. Furthermore, intravenous injection of Lenti-Spike led to increased macrophage and tissue inflammation in wild type mice, which was also abolished by Lipo-hACE2 treatment. Mechanistically, Spike protein stimulated macrophage inflammation by activating canonical NF-κB signaling. RNA sequencing analysis revealed that Lenti-Spike induced over 2,000 differentially expressed genes (DEGs) in murine macrophages, but deficiency of IκB kinase β (IKKβ), a key regulator for NF-κB activation, abrogated Lenti-Spike-elicited macrophage inflammatory responses.

Conclusions: We demonstrated that the engineered Lipo-hACE2 acts as a molecular decoy to neutralize SARS-CoV-2 or Spike protein-induced inflammation in both murine and human macrophages, and activation of the canonical IKKβ/NF-κB signaling is essential for SARS-CoV-2-elicited macrophage inflammatory responses.

Keywords: SARS-CoV-2, Liposome-Human ACE2, Spike Protein, IKKβ/NF-κB signaling, myeloid-specific IKKβ knockout

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