Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2009 Apr 7;106(14):5779-83.
doi: 10.1073/pnas.0813410106. Epub 2009 Mar 17.

Activation of critical, host-induced, metabolic and stress pathways marks neutrophil entry into cystic fibrosis lungs

Megha Makam  1 , Daisy Diaz, Julie Laval, Yael Gernez, Carol K Conrad, Colleen E Dunn, Zoe A Davies, Richard B Moss, Leonore A Herzenberg, Leonard A Herzenberg, Rabindra Tirouvanziam
Affiliations

Activation of critical, host-induced, metabolic and stress pathways marks neutrophil entry into cystic fibrosis lungs

Megha Makam et al. Proc Natl Acad Sci U S A. .

Abstract

Cystic fibrosis (CF) patients undergo progressive airway destruction caused in part by chronic neutrophilic inflammation. While opportunistic pathogens infecting CF airways can cause inflammation, we hypothesized that host-derived metabolic and stress signals would also play a role in this process. We show that neutrophils that have entered CF airways have increased phosphorylation of the eukaryotic initiation factor 4E and its partner the 4E-binding protein 1; 2 key effectors in the growth factor- and amino acid-regulated mammalian target of rapamycin (mTOR) pathway. Furthermore CF airway neutrophils display increased phosphorylation of the cAMP response element binding protein (CREB), a major transcriptional coactivator in stress signaling cascades. These active intracellular pathways are associated with increased surface expression of critical adaptor molecules, including the growth factor receptor CD114 and the receptor for advanced glycation end-products (RAGE), a CREB inducer and sensor for host-derived damage-associated molecular patterns (DAMPs). Most CF airway fluids lack any detectable soluble RAGE, an inhibitory decoy receptor for DAMPs. Concomitantly, CF airway fluids displayed high and consequently unopposed levels of S100A12; a potent mucosa- and neutrophil-derived DAMP. CF airway neutrophils also show increased surface levels of 2 critical CREB targets, the purine-recycling enzyme CD39 and the multifunctional, mTOR-inducing CXCR4 receptor. This coordinated set of events occurs in all patients, even in the context of minimal airway inflammation and well-preserved lung function. Taken together, our data demonstrate an early and sustained activation of host-responsive metabolic and stress pathways upon neutrophil entry into CF airways, suggesting potential targets for therapeutic modulation.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Activation of mTOR and CREB pathways in CF airway neutrophils. (A–E) Viable neutrophils from induced sputum (black histograms) are compared to their blood counterparts (gray histograms) for expression of phospho-eIF4E, 4E-BP1, CREB, Stat6, and S6rp, respectively. A fluorescence control (left unstained in the relevant channel) is also shown (open histogram, first line of each panel). Data are from 3 representative patients with low, medium, and high airway neutrophil count, respectively (from Top to Bottom in each panel). Differences in median fluorescence intensities between airway and blood neutrophils were similar across all patients in the study (N.S.: not significant; see Table S1 for detailed statistics).
Fig. 2.
Fig. 2.
Modulation of mTOR and CREB-associated surface adaptor molecules in CF airway neutrophils. (A–E) Viable neutrophils from induced sputum (black histograms) are compared to their blood counterparts (gray histograms) for expression of CD98, CD114, RAGE, CD39, and CXCR4, respectively. A fluorescence control (left unstained in the relevant channel) is also shown (open histogram, first line of each panel). Data are from 3 representative patients with low, medium, and high airway neutrophil count, respectively (from Top to Bottom in each panel). Differences in median fluorescence intensities between airway and blood neutrophils were similar across all patients (N.S.: not significant; see Table S1 for detailed statistics).
Fig. 3.
Fig. 3.
Putative model of CF airway inflammation highlighting the role of host-derived metabolic and stress signals. Results presented here and previously (refs. 6, 10, 28), support the existence of 4 discrete states of neutrophils, 1 in CF blood (Neu B) and 3 in the airways (Neu A1–3). We propose that host-derived cues such as oxidants, DAMPs, growth factors, and, in the airways, amino acids (AAs) and other metabolites, drive the transition between these discrete states. Pathogen-derived cues mirroring the categories defined for host-derived cues (i.e., pathogen-associated molecular patterns or PAMPs, pathogen-derived metabolites and virulence factors) also impact the biology of Neu A1, A2, and A3 subsets. Early and sustained activation of mTOR and CREB pathways and associated surface molecules is readily detectable in the Neu A1 subset, while active HNE release defines the Neu A2 subset. Both Neu A1 and A2 subsets are viable and thus may be therapeutically targeted to prevent their transition into the dying Neu A3 subset, which passively releases undigested DNA and actin fibers in the lumen.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Davis PB. Cystic fibrosis since 1938. Am J Respir Crit Care Med. 2006;173:475–482. - PubMed
    1. Tirouvanziam R. Neutrophilic inflammation as a major determinant in the progression of cystic fibrosis. Drug News Perspect. 2006;19:609–614. - PubMed
    1. Meyer KC, Zimmerman J. Neutrophil mediators, pseudomonas, and pulmonary dysfunction in cystic fibrosis. J Lab Clin Med. 1993;121:654–661. - PubMed
    1. Borregaard N, Sorensen OE, Theilgaard-Monch K. Neutrophil granules: A library of innate immunity proteins. Trends Immunol. 2007;28:340–345. - PubMed
    1. McMorran BJ, et al. Novel neutrophil-derived proteins in bronchoalveolar lavage fluid indicate an exaggerated inflammatory response in pediatric cystic fibrosis patients. Clin Chem. 2007;53:1782–1791. - PubMed

Publication types

Substances