Involvement of eNAMPT/TLR4 signaling in murine radiation pneumonitis: protection by eNAMPT neutralization

• Published in: Translational research : the journal of laboratory and clinical medicine Vol. 239; pp. 44 - 57
• Main Authors: Garcia, Alexander N., Casanova, Nancy G., Valera, Daniel G., Sun, Xiaoguang, Song, Jin H., Kempf, Carrie L., Moreno-Vinasco, Liliana, Burns, Kimberlie, Bermudez, Tadeo, Valdez, Mia, Cuellar, Genesis, Gregory, Taylor, Oita, Radu C., Hernon, Vivian Reyes, Barber, Christy, Camp, Sara M., Martin, Diego, Liu, Zhonglin, Bime, Christian, Sammani, Saad, Cress, Anne E., Garcia, Joe GN
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2022
• Subjects: Animals; Antibodies, Monoclonal, Humanized - pharmacology; Antibodies, Neutralizing - pharmacology; Cytokines - blood; Cytokines - genetics; Cytokines - immunology; Cytokines - metabolism; Humans; Lung - metabolism; Lung - pathology; Lung - radiation effects; Male; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - radiation effects; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; NF-kappa B - metabolism; Nicotinamide Phosphoribosyltransferase - blood; Nicotinamide Phosphoribosyltransferase - genetics; Nicotinamide Phosphoribosyltransferase - immunology; Nicotinamide Phosphoribosyltransferase - metabolism; Radiation Pneumonitis - drug therapy; Radiation Pneumonitis - metabolism; Signal Transduction - drug effects; Toll-Like Receptor 4 - metabolism; RILISS; HBE; DEGs; RILI; iQID; FDR; KEGG; WT; EC; ARDS; nmMLCK; 99mTc; IL-1; H&E; IR; MAPK; BAL; IL-6; mAb; pAb; WTLI; PAH; eNAMPT; TLR4; DAMP; ELISA
• ISSN: 1931-5244; 1878-1810
• DOI: 10.1016/j.trsl.2021.06.002

Therapeutic strategies to prevent or reduce the severity of radiation pneumonitis are a serious unmet need. We evaluated extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a damage-associated molecular pattern protein (DAMP) and Toll-Like Receptor 4 (TLR4) ligand, as a therapeutic target in murine radiation pneumonitis. Radiation-induced murine and human NAMPT expression was assessed in vitro, in tissues (IHC, biochemistry, imaging), and in plasma. Wild type C57Bl6 mice (WT) and Nampt+/− heterozygous mice were exposed to 20Gy whole thoracic lung irradiation (WTLI) with or without weekly IP injection of IgG1 (control) or an eNAMPT-neutralizing polyclonal (pAb) or monoclonal antibody (mAb). BAL protein/cells and H&E staining were used to generate a WTLI severity score. Differentially-expressed genes (DEGs)/pathways were identified by RNA sequencing and bioinformatic analyses. Radiation exposure increases in vitro NAMPT expression in lung epithelium (NAMPT promoter activity) and NAMPT lung tissue expression in WTLI-exposed mice. Nampt+/− mice and eNAMPT pAb/mAb-treated mice exhibited significant histologic attenuation of WTLI-mediated lung injury with reduced levels of BAL protein and cells, and plasma levels of eNAMPT, IL-6,  and IL-1β. Genomic and biochemical studies from WTLI-exposed lung tissues highlighted dysregulation of NFkB/cytokine and MAP kinase signaling pathways which were rectified by eNAMPT mAb treatment. The eNAMPT/TLR4 pathway is essentially involved in radiation pathobiology with eNAMPT neutralization an effective therapeutic strategy to reduce the severity of radiation pneumonitis.