Opioids, plasticity and phrenic motor performance: investigating the off-target effects of acute morphine administration

Peptide-Drug Conjugates: An Emerging Direction for the Next Generation of Peptide Therapeutics

Building on recent advances in peptide science, medicinal chemists have developed a hybrid class of bioconjugates, called peptide-drug conjugates, that demonstrate improved efficacy compared to peptides and small molecules independently. In this Perspective, we discuss how the conjugation of synergistic peptides and small molecules can be used to overcome complex disease states and resistance mechanisms that have eluded contemporary therapies because of their multi-component activity. We highlight how peptide-drug conjugates display a multi-factor therapeutic mechanism similar to that of antibody-drug conjugates but also demonstrate improved therapeutic properties such as less-severe off-target effects and conjugation strategies with greater site-specificity. The many considerations that go into peptide-drug conjugate design and optimization, such as peptide/small-molecule pairing and chemo-selective chemistries, are discussed. We also examine several peptide-drug conjugate series that demonstrate notable activity toward complex disease states such as neurodegenerative disorders and inflammation, as well as viral and bacterial targets with established resistance mechanisms.

Insufficient autophagy enables the nuclear factor erythroid 2-related factor 2 (NRF2) to promote ferroptosis in morphine-treated SH-SY5Y cells

RATIONALE

While morphine has important therapeutic value it is also one of the most widely abused drugs in the world. As a newly discovered style of cell death, ferroptosis is involved in the occurrence and development of many diseases, however, the current understanding of the relationship between ferroptosis and morphine is still limited.

OBJECTIVE

To clarify the role of opioid receptors in morphine-induced ferroptosis and to investigate the role of NRF2 in morphine-induced ferroptosis.

METHODS

We first used different doses of morphine (0, 0.5, 1, and 1.5 mM) to investigate morphine-induced ferroptosis in SH-SY5Y cells, and we choose 1.5 mM morphine for subsequent experiments. We next inhibited opioid receptors and NRF2 separately and examined their influence on morphine-induced ferroptosis. Finally, we tested morphine-induced insufficient autophagy.

RESULTS

Morphine triggered ferroptosis in a dose-dependent manner, which could be significantly rescued by the ferroptosis-specific inhibitor DFO. Moreover, GPX4 rather than xCT antiporter might be involved in morphine-induced ferroptosis. We also found naloxone could inhibit morphine-induced ferroptosis. Interestingly, our results demonstrated that NRF2 could promote rather than defend morphine-induced ferroptosis; this may be due to the increased p62-related insufficient autophagy.

CONCLUSION

Morphine-induced ferroptosis is regulated by the opioid receptor and GPX4 rather than the xCT antiporter. NRF2-mediated ferroptosis in morphine-exposed cells may stem from increased p62-related insufficient autophagy.