eNAMPT Is a Novel Damage-associated Molecular Pattern Protein That Contributes to the Severity of Radiation-induced Lung Fibrosis.

Abstract

The paucity of therapeutic strategies to reduce the severity of radiation-induced lung fibrosis (RILF), a life-threatening complication of intended or accidental ionizing radiation exposure, is a serious unmet need. We evaluated the contribution of eNAMPT (extracellular nicotinamide phosphoribosyltransferase), a damage-associated molecular pattern (DAMP) protein and TLR4 (Toll-like receptor 4) ligand, to the severity of whole-thorax lung irradiation (WTLI)-induced RILF. Wild-type (WT) and Nampt+/- heterozygous C57BL6 mice and nonhuman primates (NHPs, Macaca mulatta) were exposed to a single WTLI dose (9.8 or 10.7 Gy for NHPs, 20 Gy for mice). WT mice received IgG1 (control) or an eNAMPT-neutralizing polyclonal or monoclonal antibody (mAb) intraperitoneally 4 hours after WTLI and weekly thereafter. At 8-12 weeks after WTLI, NAMPT expression was assessed by immunohistochemistry, biochemistry, and plasma biomarker studies. RILF severity was determined by BAL protein/cells, hematoxylin and eosin, and trichrome blue staining and soluble collagen assays. RNA sequencing and bioinformatic analyses identified differentially expressed lung tissue genes/pathways. NAMPT lung tissue expression was increased in both WTLI-exposed WT mice and NHPs. Nampt+/- mice and eNAMPT polyclonal antibody/mAb-treated mice exhibited significantly attenuated WTLI-mediated lung fibrosis with reduced: 1) NAMPT and trichrome blue staining; 2) dysregulated lung tissue expression of smooth muscle actin, p-SMAD2/p-SMAD1/5/9, TGF-β, TSP1 (thrombospondin-1), NOX4, IL-1β, and NRF2; 3) plasma eNAMPT and IL-1β concentrations; and 4) soluble collagen. Multiple WTLI-induced dysregulated differentially expressed lung tissue genes/pathways with known tissue fibrosis involvement were each rectified in mice receiving eNAMPT mAbs.The eNAMPT/TLR4 inflammatory network is essentially involved in radiation pathobiology, with eNAMPT neutralization an effective therapeutic strategy to reduce RILF severity.

• Authors: Alexander N Garcia, Nancy G Casanova, Carrie L Kempf, Tadeo Bermudez, Daniel G Valera, Jin H Song, Xiaoguang Sun, Hua Cai, Liliana Moreno-Vinasco, Taylor Gregory, Radu C Oita, Vivian Reyes Hernon, Sara M Camp, Claude Rogers, Espoir M Kyubwa, Naresh Menon, James Axtelle, Jay Rappaport, Christian Bime, Saad Sammani, Anne E Cress, Joe G N Garcia
• Journal: American journal of respiratory cell and molecular biology (Am J Respir Cell Mol Biol) Vol. 66 Issue 5 Pg. 497-509 (05 2022) ISSN: 1535-4989 [Electronic] United States
• PMID: 35167418 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Alarmins
• Antibodies, Monoclonal
• Cytokines
• Toll-Like Receptor 4
• Nicotinamide Phosphoribosyltransferase
• nicotinamide phosphoribosyltransferase, mouse

Topics

• Alarmins (metabolism)
• Animals
• Antibodies, Monoclonal
• Cytokines (metabolism)
• Lung (pathology)
• Lung Injury (pathology)
• Mice
• Mice, Inbred C57BL
• Nicotinamide Phosphoribosyltransferase (genetics)
• Pulmonary Fibrosis (genetics, metabolism)
• Thorax
• Toll-Like Receptor 4 (metabolism)