Endothelial eNAMPT amplifies pre-clinical acute lung injury: efficacy of an eNAMPT-neutralising monoclonal antibody

Quijada, Hector; Bermudez, Tadeo; Kempf, Carrie L.; Valera, Daniel G.; Garcia, Alexander N.; Camp, Sara M.; Song, Jin H.; Franco, Evelyn; Burt, Jessica K.; Sun, Belinda; Mascarenhas, Joseph B.; Burns, Kimberlie; Gaber, Amir; Oita, Radu C.; Reyes Hernon, Vivian; Barber, Christy; Moreno-Vinasco, Liliana; Sun, Xiaoguang; Cress, Anne E.; Martin, Diego; Liu, Zhonglin; Desai, Ankit A.; Natarajan, Viswanathan; Jacobson, Jeffrey R.; Dudek, Steven M.; Bime, Christian; Sammani, Saad; Garcia, Joe G.N.

RATIONALE: The severe acute respiratory syndrome coronavirus 2/coronavirus disease 2019 pandemic has highlighted the serious unmet need for effective therapies that reduce acute respiratory distress syndrome (ARDS) mortality. We explored whether extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a ligand for Toll-like receptor (TLR)4 and a master regulator of innate immunity and inflammation, is a potential ARDS therapeutic target. METHODS: Wild-type C57BL/6J or endothelial cell (EC)-cNAMPT(−/−) knockout mice (targeted EC NAMPT deletion) were exposed to either a lipopolysaccharide (LPS)-induced (“one-hit”) or a combined LPS/ventilator (“two-hit”)-induced acute inflammatory lung injury model. A NAMPT-specific monoclonal antibody (mAb) imaging probe ((99m)Tc-ProNamptor) was used to detect NAMPT expression in lung tissues. Either an eNAMPT-neutralising goat polyclonal antibody (pAb) or a humanised monoclonal antibody (ALT-100 mAb) were used in vitro and in vivo. RESULTS: Immunohistochemical, biochemical and imaging studies validated time-dependent increases in NAMPT lung tissue expression in both pre-clinical ARDS models. Intravenous delivery of either eNAMPT-neutralising pAb or mAb significantly attenuated inflammatory lung injury (haematoxylin and eosin staining, bronchoalveolar lavage (BAL) protein, BAL polymorphonuclear cells, plasma interleukin-6) in both pre-clinical models. In vitro human lung EC studies demonstrated eNAMPT-neutralising antibodies (pAb, mAb) to strongly abrogate eNAMPT-induced TLR4 pathway activation and EC barrier disruption. In vivo studies in wild-type and EC-cNAMPT(−/−) mice confirmed a highly significant contribution of EC-derived NAMPT to the severity of inflammatory lung injury in both pre-clinical ARDS models. CONCLUSIONS: These findings highlight both the role of EC-derived eNAMPT and the potential for biologic targeting of the eNAMPT/TLR4 inflammatory pathway. In combination with predictive eNAMPT biomarker and NAMPT genotyping assays, this offers the opportunity to identify high-risk ARDS subjects for delivery of personalised medicine.