Neutrophil-specific ORAI1 Calcium Channel Inhibition Reduces Pancreatitis-associated Acute Lung Injury

Acute pancreatitis is initiated within pancreatic exocrine cells and sustained by dysregulated systemic inflammatory responses mediated by neutrophils. Store-operated Ca²⁺ entry (SOCE) through ORAI1 channels in pancreatic acinar cells triggers acute pancreatitis, and ORAI1 inhibitors ameliorate experimental acute pancreatitis, but the role of ORAI1 in pancreatitis-associated acute lung injury has not been determined. Here, we showed mice with pancreas-specific deletion of Orai1 (Orai1^ΔPdx1, ∼70% reduction in the expression of Orai1) are protected against pancreatic tissue damage and immune cell infiltration, but not pancreatitis-associated acute lung injury, suggesting the involvement of unknown cells that may cause such injury through SOCE via ORAI1. Genetic (Orai1^ΔMRP8) or pharmacological inhibition of ORAI1 in murine and human neutrophils decreased Ca²⁺ influx and impaired chemotaxis, reactive oxygen species production, and neutrophil extracellular trap formation. Unlike pancreas-specific Orai1 deletion, mice with neutrophil-specific deletion of Orai1 (Orai1^ΔMRP8) were protected against pancreatitis- and sepsis-associated lung cytokine release and injury, but not pancreatic injury in experimental acute pancreatitis. These results define critical differences between contributions from different cell types to either pancreatic or systemic organ injury in acute pancreatitis. Our findings suggest that any therapy for acute pancreatitis that targets multiple rather than single cell types is more likely to be effective.