Autophagy, Spermidine & Coronaviruses
A recent Viewpoint published in Microbial Cell, highlights the role that virophagy (a subform of autophagy that directly eliminates viruses) plays with respect to coronaviruses. Autophagy is the cellular process whereby defective, unwanted, or superfluous components of the cell are eliminated or recycled via a fusion with the lysosome. This process is upregulated during times of caloric restriction or fasting.
The authors describe virophagy as an “arms race,” as some viruses have evolved the capacity to inhibit, escape, or even hijack cellular autophagy for their own benefit (Carmona-Gutierrez et al., 2020, p. 120). While the data on SARS-CoV-2 has yet to be fully elucidated, the researchers looked to other coronaviruses to understand whether autophagy could be manipulated for viral replication, or alternatively whether autophagy may play a role in counteracting coronavirus infection.
According to the researchers, existing evidence suggests that coronaviruses may inhibit autophagy (Carmona-Gutierrez et al., 2020, p. 121). As a result, upregulating cellular autophagy may provide antiviral protection in the case of coronoviruses (Carmona-Gutierrez et al., 2020, p. 121). A recent in vitro study seems to support this theory, demonstrating that SARS-CoV-2 inhibits autophagy, and that spermidine (an autophagy inducer) could inhibit viral propagation in vitro (Gassen et al., 2020). Further research is needed to determine whether spermidine, or other autophagy inducing compounds, may have a similar effect in humans.
Citations:
Carmona-Gutierrez, D., Bauer, M. A., Zimmermann, A., Kainz, K., Hofer, S. J., Kroemer, G., & Madeo, F. (2020). Digesting the crisis: autophagy and coronaviruses. Microbial Cell, 7(5), 119.
Gassen, N. C., Papies, J., Bajaj, T., Dethloff, F., Emanuel, J., Weckmann, K., ... & Niemeyer, D. (2020). Analysis of SARS-CoV-2-controlled autophagy reveals spermidine, MK-2206, and niclosamide as putative antiviral therapeutics. bioRxiv.
