A shear stress-responsive pathway in monocytes drives cardiopulmonary bypass-induced inflammation via spectrin/RAF1/store-operated calcium entry

Patients undergoing cardiac surgery face significant inflammation induced by exposure to cardiopulmonary bypass (CPB), contributing to heightened morbidity and mortality. The molecular and cellular mechanisms that underpin this inflammatory process remain unknown. To address this knowledge gap, we conducted snRNA/ATAC sequencing to profile transcriptional and chromatin changes on circulating leukocytes from neonatal CPB patients. Classical monocytes become more prevalent after CPB, showing dysregulation of numerous inflammatory genes and significant changes in chromatin accessibility, highlighting their role in CPB-associated inflammation. The proinflammatory cytokine Interleukin 8 (IL8 or CXCL8), is significantly induced by CPB, with its promoter accessibility to the AP-1 transcription factor significantly increased. A genome-wide CRISPR screen using IL8 gene as a readout in non-adherent monocytic cells identified two genes, non-erythroid spectrin (SPTAN1) and RAF1, as novel effectors of hemodynamic stress. We further found that SPTAN1 and RAF1 activate store-operated calcium entry (SOCE) under CPB conditions, leading to elevated IL8 expression. We propose a novel shear stress-responsive pathway consisting of SPTAN1/RAF1/SOCE signaling. Drug treatment experiments offer a potential therapeutic approach to alleviate CPB-induced inflammation. Together, these findings provide novel insights into the pathogenesis of CPB-associated inflammation, enhancing our understanding of sterile inflammation and how non-adherent cells sense shear stress at molecular level.