Paroxetine attenuates sepsis by preserving the expression of the G protein-coupled chemokine receptor CXCR2 on neutrophils

Sepsis, a life-threatening organ dysfunction caused by a dysregulated host response to infection, is associated with impaired neutrophil migration to the infectious focus owing to G protein-coupled receptor kinase (GRK2)-dependent CXCR2 internalization. In the present study, we investigated whether paroxetine, an antidepressant that belongs to the selective serotonin reuptake inhibitor (SSRI) class of drugs and that is also identified as a GRK2 inhibitor, can improve neutrophil recruitment in the cecal ligation and puncture (CLP)-induced sepsis model. Moderate (mCLP) and severe (sCLP) polymicrobial peritonitis were induced in C57BL/6 mice. The in vivo effects of paroxetine (10 mg/kg/day) were evaluated by peritoneal neutrophil count, flow cytometry CXCR2 expression on circulating neutrophils, peritoneal bacterial load, serum quantification of chemokines/cytokines (CXCL1, CXCL2, and IL-6), heart and lung histological analysis, radiotelemetry blood pressure recording, and survival curves. The in vitro CXCR2 expression on the cellular membrane was evaluated by flow cytometry techniques using CXCL2- and LPS-stimulated murine neutrophils, CXCL2-stimulated HEK293 cells, and LPS-stimulated human neutrophils. The in vitro expression of CD11b, a marker of neutrophil activation, was evaluated in CXCL2 and LPS-stimulated murine neutrophils. Herein, we observed that paroxetine-treated mCLP mice showed improved neutrophil migration to the peritoneal cavity with a reduced presence of local bacteria, lower plasma levels of CXCL1, controlled blood pressure, and higher sepsis survival. In addition, sCLP mice post-treated with paroxetine plus antibiotics showed preserved membrane CXCR2 expression on circulating neutrophils, reduced plasma levels of CXCL2 and IL-6, attenuated leukocyte infiltration in the lungs and hearts, and a higher survival index. Finally, paroxetine also prevented LPS and CXCR2 ligands-induced reduction of CXCR2 expression in human and murine neutrophils and HEK293 cells, and increased the membrane CD11b expression in CXCL2 and LPS-stimulated murine neutrophils. Given that the pharmacokinetics and toxicology of paroxetine are already well defined, we suggest its repurposing as an adjuvant pharmacological approach in antibiotic therapy during infection management.