Stratification of asthmatics based on relevant biomarkers enables it to predict the responsiveness against immune-targeted therapies in patients with asthma. Individualised therapy in patients with eosinophilic asthma has yielded improved clinical outcomes, and similar approaches in those with neutrophilic asthma have yet to be developed. We determined whether the colony stimulating factors (CSFs) in the airway reflect the inflammatory phenotypes of asthma and contribute to disease progression of neutrophilic asthma. We analysed three different mouse models of asthma and assessed the cytokine profiles in sputum from human patients with asthma stratified according to inflammatory phenotype; in addition, we evaluated the therapeutic efficacy of various cytokine blockades in a mouse model of neutrophilic asthma. Among the CSFs, airway granulocyte-CSF (G-CSF) contributes to airway neutrophilia by promoting neutrophil development in the bone marrow (BM), and thereby distinguishes neutrophilic inflammation from eosinophilic inflammation in mouse models of asthma. G-CSF is produced by concurrent stimulation of the lung epithelium with IL-17A and TNF-α; therefore, dual blockade of upstream stimuli using monoclonal antibodies or genetic deficiency of the cytokines in IL-17A × TNF-α double knockout (DKO) mice reduced the serum level of G-CSF, leading to alleviation of neutrophilic inflammation in the airway. In humans, the sputum level of G-CSF can be used to stratify patients with asthma with neutrophil-dominated inflammation. Our results indicated that myelopoiesis-promoting G-CSF and cytokines as the upstream inducing factors are potential diagnostic and therapeutic targets in patients with neutrophilic asthma.

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) has attracted a great deal of attention because of its association with severe asthma. However, it remains widely underdiagnosed in asthmatics as well as the general population. Upon pharmacological inhibition of cyclooxygenase 1 by NSAIDs, production of anti-inflammatory prostaglandin E2 and lipoxins ceases, while release of proinflammatory cysteinyl leukotrienes increases. To determine the underlying mechanisms, many studies have attempted to elucidate the genetic variants, such as single nucleotide polymorphisms, responsible for alterations of prostaglandins and leukotrienes, but the results of these genetic studies could not explain the whole genetic pathogenesis of NERD. Accordingly, the field of epigenetics has been introduced as an additional contributor to genomic alteration underlying the development of NERD. Recently, changes in CpG methylation, as one of the epigenetic components, have been identified in target tissues of NERD. This review discusses in silico analyses of both genetic and epigenetic components to gain a better understanding of their complementary roles in the development of NERD. Although the molecular mechanisms underlying NERD pathogenesis remain poorly understood, genetic and epigenetic variations play significant roles. Our results enhance the understanding of the genetic and epigenetic mechanisms involved in the development of NERD and suggest new approaches toward better diagnosis and management.

Background. Quinoline-3-carboxamides have been used to treat autoimmune/inflammatory diseases in humans because they inhibit the functions of S100 calcium-binding protein A9 (S100A9), which participates in the development of neutrophilic inflammation in asthmatics and in an animal model of neutrophilic asthma. However, the therapeutic effects of these chemicals have not been evaluated in asthma. The purpose of this study was to evaluate the effect of paquinimod, one of the quinoline-3-carboxamides, on a murine model of neutrophilic asthma. Methods. Paquinimod was orally administered to 6-week-old C57BL/6 mice sensitized and challenged with ovalbumin (OVA)/complete Freunds adjuvant (CFA) and OVA. Lung inflammation and remodeling were evaluated using bronchoalveolar lavage (BAL) and histologic findings including goblet cell count. S100A9, caspase-1, IL-1β, MPO, IL-17, IFN-γ, and TNF-α were measured in lung lysates using western blotting. Results. Paquinimod restored the enhancement of airway resistance and the increases in numbers of neutrophils and macrophages of BAL fluids and those of goblet cells in OVA/CFA mice toward the levels of sham-treated mice in a dose-dependent manner (0.1, 1, 10, and 25mg/kg/day, p.o.). Concomitantly, p20 activated caspase-1, IL-1β, IL-17, TNF-α, and IFN-γ levels were markedly attenuated. Conclusion. These data indicate that paquinimod effectively inhibits neutrophilic inflammation and remodeling in the murine model of neutrophilic asthma, possibly via downregulation of IL-17, IFN-γ, and IL-1β.

Lee JU, et al. J Korean Med Sci. 2023 Dec;39(1):e13. https://doi.org/10.3346/jkms.2024.39.e13