Fig. 6: Inhibition of G‑CSF receptor downstream signaling abrogates tissue toxicity of G‑neutrophils and improves bacterial clearance.

a Mice were injected subcutaneously with PBS (control, Co), MOPC, or ^GMOPC cells. On day 14, animals were sacrificed, and blood was collected. Plasma nicotinamide adenine dinucleotide (NAD) levels were elevated in ^GMOPC-bearing mice (n = 4) in comparison to MOPC-bearing (n = 3) and tumor-free mice (n = 2). b Bone marrow progenitors were cultured for 6 days in ^GMlOPC‑conditioned medium with or without the NAMPT inhibitor FK866. Inhibition of NAMPT decreased unstimulated reactive oxygen species (ROS) production in newly differentiated ^Gneutrophils (n = 4) in comparison to untreated ^Gneutrophils (n = 4) in biological replicates (gating strategy Fig. S3a). c–l ^GMOPC-bearing mice were treated intraperitoneally with FK866 every other day. On day 14, animals were sacrificed, and neutrophil (gating strategy Fig. S3a) phenotype and function were analyzed in lung single‑cell suspensions. c FK866 reduced lung infiltration by ^Gneutrophils (n = 6) in comparison to untreated mice (n = 5). d FK866 prevented accumulation of CD62L^{low G}neutrophils (n = 6) in comparison to untreated mice (n = 5). e–g FK866 increased ^Gneutrophil cell death (n = 6) in comparison to untreated mice (n = 5). h FK866 decreased unstimulated ROS production in ^Gneutrophils (n = 6) in comparison to untreated mice (n = 5). i FK866 normalized Pseudomonas aeruginosa–stimulated Mmp9 release by ^Gneutrophils (n = 5) in comparison to untreated mice (n = 5). j FK866 had no effect on the phagocytic capacity of ^Gneutrophils (n = 6) in comparison to untreated mice (n = 5). k, l ^GMOPC-bearing mice were treated with FK866 every other day. On day 14, mice were infected intratracheally with P. aeruginosa and sacrificed 18 h later. k FK866 enhanced bacterial clearance in the lower respiratory tract (n = 6) in comparison to untreated mice (n = 6). l FK866 improved clinical performance of infected mice (n = 6) in comparison to untreated mice (n = 6). Co control tumor‑free mice, MOPC mice bearing non-G‑CSF‑producing tumors, ^GMOPC mice bearing G‑CSF‑producing tumors, NAD nicotinamide adenine dinucleotide, ROS reactive oxygen species, Mmp9 matrix metalloproteinase‑9, CFU colony‑forming units, NAMPT nicotinamide phosphoribosyltransferase, BAL bronchoalveolar lavage. Data are presented as means with individual values (biological replicates) shown. Statistical tests: Kruskal–Wallis for multiple‑group comparisons with Bonferroni correction, and two-sided Mann–Whitney for two‑group comparisons (a–k); Chi‑square (l). *p < 0.05, **p < 0.01, ***p < 0.001; #p < 0.1. Source data and exact p-values are provided as a Source Data file.