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

Alexander N. Garcia, Nancy G. Casanova, Daniel G. Valera, Xiaoguang Sun, Jin H. Song, Carrie L. Kempf, Liliana Moreno-Vinasco, Kimberlie Burns, Tadeo Bermudez, Mia Valdez, Genesis Cuellar, Taylor Gregory, Radu C. Oita, Vivian Reyes Hernon, Christy Barber, Sara M. Camp, Diego Martin, Zhonglin Liu, Christian Bime, Saad SammaniAnne E. Cress, Joe GN Garcia

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)44-57
Number of pages14
JournalTranslational Research
StatePublished - Jan 2022

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Physiology (medical)
  • Biochemistry, medical


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