Granulocyte colony-stimulating factor : missing link for stratification of type 2-high and type 2-low chronic rhinosinusitis patients

Background: Chronic rhinosinusitis (CRS) is a heterogeneous disease, with patients having either a high or low type 2 inflammatory endotype. Whereas the type 2-high group is well characterized by IL-5 expression, the type 2-low group, consisting of approximately 20% of CRS with and 50% of CRS without nasal polyp patients, lacks a clear biomarker profile and thus specific therapeutic targets. Objective: The aim was to identify underlying molecular pathways of type 2-low CRS, as stratification of patients may allow improvement of personalized treatments. Methods: Luminex assays were performed to analyze proteins in nasal secretions and tissues of CRS patients. Immunostainings were analyzed for differences in neutrophils, granulocyte-colony stimulating factor (G-CSF), and its receptor in nasal tissue. Neutrophils were isolated from blood of healthy volunteers and stimulated with G-CSF. Effects on apoptosis and neutrophil activity were analyzed with flow cytometry. Results: G-CSF was significantly upregulated in nasal tissue and secretion fluid of type 2-low CRS patients compared to type 2-high patients. In nasal polyp tissue of type 2-low patients, a large infiltration of neutrophils expressing both G-CSF and its receptor was detected, suggesting the presence of a neutrophil-intrinsic autocrine survival mechanism. In response to G-CSF, neutrophils were in an activated state and were resistant to apoptosis, possibly contributing to a chronic inflammation. Of interest, type 2-high nasal polyp patients treated with IgE-blocking omalizumab had increased G-CSF concentrations compared to before treatment. Conclusion: G-CSF is an important cytokine regulating neutrophils in type 2-low CRS and has potential in the diagnosis and therapy of the disease.

Publication year:2022

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