Scientists from Case Western Reserve University School of Medicine say they have discovered a way to stop immune cell death associated with multiple diseases, including sepsis, inflammatory bowel disease (IBD), and arthritis.
Their study (“Chemical disruption of the pyroptotic pore-forming protein gasdermin D inhibits inflammatory cell death and sepsis”), published in Science Immunology, identified a chemical that potently inhibits inflammatory cell death. Cells often perforate their own membranes in response to extreme inflammation—a type of cell suicide known as pyroptosis. In human cells and animal models, the chemical prevents these deadly holes from forming inside cell membranes. This is a new pharmacologic approach to stopping this destructive process.
“Dysregulation of inflammatory cell death is a key driver of many inflammatory diseases. Pyroptosis, a highly inflammatory form of cell death, uses intracellularly generated pores to disrupt electrolyte homeostasis and execute cell death. Gasdermin D, the pore-forming effector protein of pyroptosis, coordinates membrane lysis and the release of highly inflammatory molecules, such as interleukin-1β, which potentiate the overactivation of the innate immune response. However, to date, there is no pharmacologic mechanism to disrupt pyroptosis,” write the investigators.
“Here, we identify necrosulfonamide as a direct chemical inhibitor of gasdermin D, the pyroptotic pore-forming protein, which binds directly to gasdermin D to inhibit pyroptosis. Pharmacologic inhibition of pyroptotic cell death by necrosulfonamide is efficacious in sepsis models and suggests that gasdermin D inhibitors may be efficacious clinically in inflammatory diseases.”
“To date, there has been no pharmacologic mechanism to directly inhibit pyroptotic pore formation,” says Derek Abbott, M.D., Ph.D., Arline H. and Curtis F. Garvin professor of medicine at Case Western Reserve School of Medicine and member of the Case Comprehensive Cancer Center, whose lab performed the work. “We knew necrosulfonamide inhibited another type of pore formation and had a hunch it might work against pyroptosis, too. We found necrosulfonamide is effective in our sepsis models, and could be effective to treat diseases worsened by inflammation.”
In the new study, mice treated with necrosulfonamide survived longer than untreated mice, after exposure to bacterial proteins that cause inflammation. The results suggest the chemical alleviates extreme, harmful inflammation associated with bacterial sepsis. Necrosulfonamide has never before been studied as a pharmacologic agent.
The researchers tested necrosulfonamide by adding it to human cells growing in their laboratory. Even in the face of inflammatory triggers, like bacteria, immune cells exposed to the chemical remained intact, notes Dr. Abbott. They did not leak dyes or other molecules, and still sent signals to other cells as part of normal, healthy function.
The new study also describes how necrosulfonamide works inside cells. Dr. Abbott's team used biochemical analyses to show it directly attaches to gasdermin D, a protein that destroys cell membranes. During pyroptosis, long chains of gasdermin D aggregate inside cell membranes, forming pores. Necrosulfonamide physically gets in the way of this process. With the large chemical attached to it, gasdermin D can't aggregate.
The researchers studied different gasdermin D variations to pinpoint the exact location where necrosulfonamide attaches. They found it attaches to regions where gasdermin D proteins connect to each other. The specific attachment mechanism differs from how the chemical inhibits enzymes involved in other types of cell death.
“Our results suggest gasdermin D inhibitors are clinically possible,” explains Joseph Rathkey, first author on the study and student in the medical scientist training program at Case Western Reserve School of Medicine. “We've provided proof of principle that destructive pore formation can be inhibited, and that gasdermin D is a viable pharmaceutical target.”
He says the “high therapeutic potential” of chemicals like necrosulfonamide could inform future studies in humans.