Regulation of Neutrophil Antimicrobial Responses by the Glycerol-3-phosphate Shuttle

Neutrophils possess a plethora of antimicrobial responses that must be activated to extinguish pathogens while not being overtly harmful to nearby healthy tissue. Due to neutrophils short lifespans and limited transcriptional modifications, their antimicrobial responses are closely tied to neutrophil metabolic plasticity. This is best exemplified by activation of the oxidative pentose phosphate pathway (oxPPP) to fuel the neutrophil oxidative burst; however, metabolic pathways other than the oxPPP may coordinate antimicrobial responses or regulate their relative strength. Consistent with this idea, we find that neutrophil activation coincides with engagement of the glycerol 3-phosphate (G3P) shuttle. To understand how the G3P shuttle influences neutrophil function, we used a pharmacological inhibitor (iGP-1) to block the G3P shuttle and determined how it affects reactive oxygen species (ROS) production, granule release, phagocytosis, and microbial killing. Bone marrow-derived neutrophils were stimulated with either phorbol 12-myristate 13-acetate (PMA) or E. coli to activate neutrophil effector responses. We found that inhibition of the G3P shuttle reduced ROS generation by 30% (p < 0.05, n = 12, Student’s T-test) and NETosis by 15% (p < 0.05, n = 6, Student’s T-test). Furthermore, G3P shuttle inhibition decreased primary granule release while not impacting the release of secondary and tertiary granules (p < 0.05, n = 6, Student’s T-test). Additionally, iGP-1 treatment worsened phagocytic capacity, but, surprisingly, improved E. coli extinguishment (p < 0.05, n = 6, Student’s T-test). These findings highlight the intricate nature by which metabolism coordinates neutrophil effector functions. Future experiments using a genetic knockout model of the G3P shuttle will clarify the role of the G3P shuttle in vivo and provide information that could be used to develop targeted metabolic interventions to improve neutrophil-mediated immune functions. NIH HL168198; AHA 23TPA1141824; JHFE – Research Enhancement Grant This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.