Circulating Gasdermin-D in Critically Ill Patients

The key to further improving outcomes in sepsis lies in understanding and abrogating the dysfunctional immune response that leads to organ failure. Activation of gasdermin-D, a pore-forming protein within the inflammasome cascade, has recently been recognized as the critical step in pyroptosis and organ dysfunction. In this study, we sought to investigate the presence of gasdermin-D in critically ill subjects. DESIGN, SETTING, AND PATIENTS: Prospective pilot study comparing microparticulate active gasdermin-D levels in critically ill patients admitted to the medical ICU at The Ohio State University Medical Center to healthy donors and clinical outcomes. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma was collected from subjects upon consent and microparticles were isolated by ultracentrifugation. Proteins of interest were identified by immunoblot analysis of microparticle lysates. Quantification was accomplished by densitometry using ImageJ software (National Institutes of Health, Bethesda, MD). Investigators were then unblinded and compared microparticulate active gasdermin-D levels to physician adjudicated clinical diagnoses and outcomes. No appreciable levels of active gasdermin-D were observed in microparticles from healthy volunteers and nonseptic critically ill patients. However, elevated levels of gasdermin-D were noted in microparticles from the septic cohort of critically ill patients. Furthermore, a significant positive correlation by linear regression was noted when microparticulate active gasdermin-D levels were compared with microparticulate levels of CD63, an exosomal marker, CD14, a monocyte marker, and CD69, a marker of monocyte activation (R(2) = 0.37, p = 0.0011, R(2) = 0.85, p < 0.0001, and R(2) = 0.43, p = 0.0003, respectively). CONCLUSIONS: This is the first study to demonstrate circulating active gasdermin-D in septic patients in the intensive care setting. Our findings also suggest that active gasdermin-D in septic patients is encapsulated in exosomes derived from activated monocytes. Further characterization in the clinical setting is warranted.