INTRODUCTION: Chronic pain involves complex neuroimmune interactions, yet molecular drivers of inflammation across peripheral and central immune cells are poorly understood. GPR84, a pro-inflammatory GPCR expressed in myeloid cells, is a potential regulator of such responses.

AIM(S): To elucidate the role of GPR84 in driving inflammatory responses in both neutrophil-like and microglial cells, with a focus on its potential as a shared therapeutic target in peripheral and central pain mechanisms.

METHOD(S): NB4 cells were differentiated with ATRA and treated with DL175, LPS, NEL1, or their combinations (DL175+LPS, DL175+NEL1, LPS+NEL1). CyTOF was performed on days 3, 5, and 7 to assess activation and maturation markers. HMC3 cells were treated with DL175, LPS, STS, NEL1, nigericin, and their combinations (DL175+LPS, DL175+LPS+Nigericin, STS+DL175, NEL1+LPS, NEL1+LPS+Nigericin, STS+NEL1). RT-qPCR assessed expression of IL1B, IL18, NLRP3, CASP1, CASP4, NF-κB, GPR84.

RESULTS: CyTOF revealed that GPR84 stimulation promoted neutrophil maturation (CD11b, CD66b, CD44) and enhanced co-stimulatory molecule expression (HLA-DR), particularly under LPS co-treatment. Antagonist application attenuated these effects, confirming receptor specificity. In HMC3, DL175 amplified LPS- and STS-induced transcription of NLRP3, IL1, CASP1/4, and NF-κB. The DL175+LPS+nigericin condition showed the strongest IL18 and NLRP3 upregulation. Co-treatment with antagonist attenuated these effects, confirming receptor specificity.

CONCLUSIONS: GPR84 drives pro-inflammatory polarization in neutrophils and microglia. It may represent a shared therapeutic target in chronic pain-related immune responses.