The Relationship Between Neurosteroid Structures and Inhibition of Pyroptotic Lysis

Abstract

Pyroptosis is a form of programmed cell death with inflammatory biologicalconsequences. In moderation, pyroptosis helps to regulate and maintain a healthy immune response in the presence of invading pathogens. However, excessive, or inappropriate pyroptosis causes harmful consequences including inflammation and damage to tissues and organs. There are several steps within the pyroptotic cascade that result in lysis and release of cellular components implicated in harm to healthy cells and tissues. Previously identified small molecule inhibitors, like the amino acid glycine, have been shown to inhibit pyroptosis-mediated cell lysis, in vitro. Glycine is an ion channel modulator and examination of other ion channel modulators led to the discovery that pregnenolone sulfate also inhibits cell lysis in cells undergoing pyroptosis. Pregnenolone sulfate is a more potent inhibitor than glycine, but the mechanism of action for the protection is unknown. To begin to fill the gap in knowledge of how pregnenolone sulfate, and other small molecules, may be interacting with pyroptotic cells to prevent membrane lysis, we tested a rationally selected library of neurosteroids with similar structures to pregnenolone sulfate for inhibitive activity. We found some neurosteroids retain the same level of activity in comparison to pregnenolone sulfate, but others exhibit a partial or total loss in activity. No single aspect of the structure was responsible for inhibitive activity; different parts of the molecule contribute to inhibition of pyroptosis. Together, the results of this thesis lay the foundation for a deeper knowledge of what mechanisms may provide protection and how we can design future inhibitors with these mechanisms in mind.