In vitro sepsis up‐regulates Nociceptin/Orphanin FQ receptor expression and function on human T‐ but not B‐cells

Abstract

Background and PurposeIn animal models of sepsis, increased activation of the Nociceptin/Orphanin FQ (N/OFQ) receptor NOP is associated with mortality and NOP antagonists improved survival. We have explored the role of the N/OFQ‐NOP system in freshly isolated volunteer human B‐ and T‐cells incubated with lipopolysaccharide (LPS) and peptidoglycan G (PepG) as a model of in vitro sepsis.Experimental ApproachB‐ and T‐cell NOP expression was measured using the NOP fluorescent probe N/OFQATTO594, N/OFQ content was measured using immunofluorescence, N/OFQ release was tracked using a CHOhNOPGαiq5 biosensor assay and NOP function was measured using transwell migration and cytokine/chemokine release using a 25‐plex assay format. Cells were challenged with LPS/PepG.Key ResultsCD19‐positive B‐cells bound N/OFQATTO594; they also contain N/OFQ. Stimulation with CXCL13/IL‐4 increased N/OFQ release. N/OFQ trended to reduced migration to CXCL13/IL‐4. Surface NOP expression was unaffected by LPS/PepG, but this treatment increased GM‐CSF release in an N/OFQ sensitive manner. CD3‐positive T‐cells did not bind N/OFQATTO594; they did contain N/OFQ. Stimulation with CXCL12/IL‐6 increased N/OFQ release. When incubated with LPS/PepG, NOP surface expression was induced leading to N/OFQATTO594 binding. In LPS/PepG‐treated cells, N/OFQ reduced migration to CXCL12/IL‐6. LPS/PepG increased GM‐CSF release in an N/OFQ sensitive manner.Conclusions and ImplicationsWe suggest both a constitutive and sepsis‐inducible N/OFQ‐NOP receptor autocrine regulation of B‐ and T‐cell function, respectively. These NOP receptors variably inhibit migration and reduce GM‐CSF release. These data provide mechanistic insights to the detrimental role for increased N/OFQ signalling in sepsis and suggest a potential role for NOP antagonists as treatments.