Mitochondria-dependent synthetic small-molecule vaccine adjuvants for influenza virus infection

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 23; pp. 1 - 10
• Main Authors: Sato-Kaneko, Fumi, Yao, Shiyin, Lao, Fitzgerald S., Nan, Jason, Shpigelman, Jonathan, Cheng, Annette, Saito, Tetsuya, Messer, Karen, Pu, Minya, Shukla, Nikunj M., Cottam, Howard B., Chan, Michael, Molina, Anthony J., Corr, Maripat, Hayashi, Tomoko, Carson, Dennis A.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 08.06.2021
• Subjects: Adjuvants; Adjuvants, Immunologic - pharmacology; Aging; Animals; Antibodies, Viral - immunology; Antioxidants; Biological Sciences; Bone marrow; Cytokines; Dendritic cells; Dendritic Cells - immunology; Female; Gene Expression; Gene polymorphism; Humans; Immune system; Immunity, Innate - drug effects; Influenza; Influenza Vaccines - immunology; Influenza Vaccines - pharmacology; Influenza, Human - immunology; Innate immunity; Interferon; Leukocytes (mononuclear); Leukocytes, Mononuclear - immunology; Lipopolysaccharides; Mice; Mice, Inbred BALB C; Mitochondria; Mitochondria - drug effects; Mitochondria - genetics; Mitochondria - metabolism; NF-κB protein; Orthomyxoviridae Infections - immunology; Pattern recognition; Peripheral blood mononuclear cells; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Receptors; Saponins; Signaling; Stress, Physiological; Toll-Like Receptors; Toxicity; Vaccines; Viruses; influenza virus; NF-κB; vaccine adjuvant; mitochondrial reactive oxygen species; mitochondrial stress
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2025718118

Vaccine adjuvants enhance and prolong pathogen-specific protective immune responses. Recent reports indicate that host factors—such as aging, pregnancy, and genetic polymorphisms—influence efficacies of vaccines adjuvanted with Toll-like receptor (TLR) or known pattern-recognition receptor (PRR) agonists. Although PRR independent adjuvants (e.g., oil-in-water emulsion and saponin) are emerging, these adjuvants induce some local and systemic reactogenicity. Hence, new TLR and PRR-independent adjuvants that provide greater potency alone or in combination without compromising safety are highly desired. Previous cell-based high-throughput screenings yielded a small molecule 81 [N-(4-chloro-2,5- dimethoxyphenyl)-4-ethoxybenzenesulfonamide], which enhanced lipopolysaccharide-induced NF-κB and type I interferon signaling in reporter assays. Here compound 81 activated innate immunity in primary human peripheral blood mononuclear cells and murine bone marrow-derived dendritic cells (BMDCs). The innate immune activation by 81 was independent of TLRs and other PRRs and was significantly reduced in mitochondrial antiviral-signaling protein (MAVS)-deficient BMDCs. Compound 81 activities were mediated by mitochondrial dysfunction as mitophagy inducers and a mitochondria specific antioxidant significantly inhibited cytokine induction by 81. Both compound 81 and a derivative obtained via structure–activity relationship studies, 2F52 [N-benzyl-N-(4-chloro-2,5-dimethoxyphenyl)-4-ethoxybenzenesulfonamide] modestly increased mitochondrial reactive oxygen species and induced the aggregation of MAVS. Neither 81 nor 2F52 injected as adjuvants caused local or systemic toxicity in mice at effective concentrations for vaccination. Furthermore, vaccination with inactivated influenza virus adjuvanted with 2F52 demonstrated protective effects in a murine lethal virus challenge study. As an unconventional and safe adjuvant that does not require known PRRs, compound 2F52 could be a useful addition to vaccines.