G-CSF suppresses allergic pulmonary inflammation, downmodulating cytokine, chemokine and eosinophil production

Airway G-CSF identifies neutrophilic inflammation and contributes to asthma progression

Stratification of asthmatic patients based on relevant biomarkers enables the prediction of responsiveness against immune-targeted therapies in patients with asthma. Individualised therapy in patients with eosinophilic asthma has yielded improved clinical outcomes; similar approaches in patients with neutrophilic asthma have yet to be developed. We determined whether 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 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 bone marrow 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 interleukin (IL)-17A and tumour necrosis factor (TNF)-α; therefore, dual blockade of upstream stimuli using monoclonal antibodies or genetic deficiency of the cytokines in IL-17A×TNF-α double-knockout 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.

Polymorphisms and haplotypes of the chromosome locus 17q12-17q21.1 contribute to adult asthma susceptibility in Slovenian patients

One of the major asthma susceptibility loci is 17q12-17q21.1, but the relationship between this locus and adult asthma is unclear. Association analysis of 13 single nucleotide polymorphisms (SNPs) and haplotypes from 17q12-17q21.1 was performed in 418 adult patients with asthma and 288 controls from Slovenia. Single SNP analysis revealed only marginal associations with adult asthma for SNPs located in GSDMA, GSDMB, ORMDL3 and ZPBP2 genes, and rs7219080 was the most highly associated. Analyses of asthma phenotypes found no association with atopy or lung function, but rs2305480 and rs8066582 were associated with childhood asthma and rs9916279 was associated with asthma in smokers. Notably, haplotypes consisting of rs9916279, rs8066582, rs1042658, and rs2302777 harbouring PSMD3, CSF3 and MED24 genes were highly associated with asthma. The four most common haplotypes, TCCG, TTTA, CCCA and TTCA, were more frequent in patients with asthma, whereas TTCG, TCCA, TCTA and TTTG were more frequent in controls. Only 3% of asthma patients belonged to haplotypes TTCG, TCCA, TCTA and TTTG compared with nearly one-third (31%) of controls. Associations confirmed that the 17q12-17q21.1 locus harbours a genetic determinant for asthma risk in adults and suggest that in addition to the previously known ORMDL3-GSDM locus, CSF3-PSMD3-MED24 also plays a role in asthma pathogenesis.

Blockage of Eosinopoiesis by IL-17A Is Prevented by Cytokine and Lipid Mediators of Allergic Inflammation

Interleukin- (IL-) 17A, a pleiotropic mediator of inflammation and autoimmunity, potently stimulates bone-marrow neutrophil production. To explore IL-17A effects on eosinopoiesis, we cultured bone-marrow from wild-type mice, or mutants lacking inducible nitric oxide synthase (iNOS−/−), CD95 (lpr), IL-17RA, or IL-4, with IL-5, alone or associated with IL-17A. Synergisms between IL-17A-activated, NO-dependent, and NO-independent mechanisms and antagonisms between IL-17A and proallergic factors were further examined. While IL-17A (0.1–10 ng/mL) had no IL-5-independent effect on eosinopoiesis, it dose-dependently suppressed IL-5-induced eosinophil differentiation, by acting during the initial 24 hours. Its effectiveness was abolished by caspase inhibitor, zVAD-fmk. The effect of IL-17A (0.1–1 ng/mL) was sensitive to the iNOS-selective inhibitor aminoguanidine and undetectable in iNOS−/− bone-marrow. By contrast, a higher IL-17A concentration (10 ng/mL) retained significant suppressive effect in both conditions, unmasking a high-end iNOS-independent mechanism. Lower IL-17A concentrations synergized with NO donor nitroprusside. Eosinopoiesis suppression by IL-17A was (a) undetectable in bone-marrow lacking IL-17RA or CD95 and (b) actively prevented by LTD4, LTC4, IL-13, and eotaxin. Sensitivity to IL-17A was increased in bone-marrow lacking IL-4; adding IL-4 to the cultures restored IL-5 responses to control levels. Therefore, effects of both IL-17A and proallergic factors are transduced by the iNOS-CD95 pathway in isolated bone-marrow.

Effects of propranolol and isoproterenol on infantile hemangioma endothelial cells in vitro

The aim of the present study was to investigate the effects of propranolol and isoproterenol on the growth curve of infantile hemangioma endothelial cells (IHECs) in vitro and determine the functions of the β-adrenergic receptor in the pathogenesis of infantile hemangioma. IHECs were divided into three groups: The control group, the propranolol group (PG) and the isoproterenol group (IG). The PG and IG were administered with high, medium and low concentrations of the corresponding drugs. The cell growth in each group was determined using the MTT assay. A high propranolol concentration resulted in the inhibition of cell growth. By comparison, isoproterenol promoted cell growth. Within a specific time-frame (72–96 h), high drug concentrations (20 μg/ml) elicited strong effects on the cells. At certain concentrations, propranolol inhibited cell growth once the proliferation stage of IHECs had been affected for a specific length of time, whereas isoproterenol yielded opposite results. The β-adrenergic receptor elicits an important effect in the pathogenesis of infantile hemangioma.

G-CSF preferentially supports the generation of gut-homing Gr-1high macrophages in M-CSF-treated bone marrow cells

The G-CSF is best known for its activity in the generation and activation of neutrophils. In addition, studies on G-CSF−/− or G-CSFR−/− mice and BMC cultures suggested a role of G-CSF in macrophage generation. However, our understanding on the role of G-CSF in macrophage development is limited. Here, using in vitro BMC models, we demonstrated that G-CSF promoted the generation of Gr-1high/F4/80+ macrophage-like cells in M-BMCs, likely through suppressing cell death and enhancing generation of Gr-1high/F4/80+ macrophage-like cells. These Gr-1high macrophage-like cells produced “M2-like” cytokines and surface markers in response to LPS and IL-4/IL-13, respectively. Adoptive transfer of EGFP-expressing (EGFP+) M-BMCs showed a dominant, gut-homing phenotype. The small intestinal lamina propria of G-CSFR−/− mice also harbored significantly reduced numbers of Gr-1high/F4/80+ macrophages compared with those of WT mice, but levels of Gr-1+/F4/80− neutrophil-like cells were similar between these mice. Collectively, these results suggest a novel function of G-CSF in the generation of gut-homing, M2-like macrophages.

Modulation of the effects of lung immune response on bone marrow by oral antigen exposure

Allergic airway inflammation is attenuated by oral tolerization (oral exposure to allergen, followed by conventional sensitization and challenge with homologous antigen), which decreases airway allergen challenge-induced eosinophilic infiltration of the lungs and bone marrow eosinophilia. We examined its effects on bone marrow eosinophil and neutrophil production. Mice of wild type (BP-2, BALB/c, and C57BL/6) and mutant strains (lacking iNOS or CD95L) were given ovalbumin (OVA) or water (vehicle) orally and subsequently sensitized and challenged with OVA (OVA/OVA/OVA and H₂O/OVA/OVA groups, resp.). Anti-OVA IgG and IgE, bone marrow eosinophil and neutrophil numbers, and eosinophil and neutrophil production ex vivo were evaluated. T lymphocytes from OVA/OVA/OVA or control H₂O/OVA/OVA donors were transferred into naïve syngeneic recipients, which were subsequently sensitized/challenged with OVA. Alternatively, T lymphocytes were cocultured with bone marrow eosinophil precursors from histocompatible sensitized/challenged mice. OVA/OVA/OVA mice of the BP-2 and BALB/c strains showed, relative to H₂O/OVA/OVA controls, significantly decreased bone marrow eosinophil counts and ex vivo eosinopoiesis/neutropoiesis. Full effectiveness in vivo required sequential oral/subcutaneous/intranasal exposures to the same allergen. Transfer of splenic T lymphocytes from OVA/OVA/OVA donors to naive recipients prevented bone marrow eosinophilia and eosinopoiesis in response to recipient sensitization/challenge and supressed eosinopoiesis upon coculture with syngeneic bone marrow precursors from sensitized/challenged donors.

Fish oil has beneficial effects on allergen-induced airway inflammation and hyperreactivity in mice

Background

Fish oil (FO) is rich in n-3 polyunsaturated fatty acids (PUFA), which have been suggested to be anti-inflammatory and are associated with improvement of several inflammatory diseases. In this study, we investigated the influence of FO on allergen-induced lung inflammation and airway hyperreactivity in mice.

Methods

Male A/J mice were fed either a standard-chow (SC) or a FO diet (FO) for 8 weeks. After 4 weeks, each group was further randomized for ovalbumin (SC-OVA and FO-OVA) or saline (SC-SAL and FO-SAL) challenge. Resistance and elastance were measured at baseline and after aerosolized methacholine, 24h after the last challenge. Bronchoalveolar lavage (BAL) was performed for leukocyte counts. Lung tissue mucus deposition, peribronchiolar matrix deposition and eosinophil infiltration were quantified. Serum immunoglobulin E (IgE) and IgG1 (ref 2.2), lung IL-4, IL-5, IL-10, IL-13, IL-17, INFγ and eotaxin-1 and 2 were detected by ELISA and nuclear factor kappa B (NFκB), GATA-3 and peroxisome proliferator-activated receptor gamma (PPARγ) expression was measured by Western blot.

Results

Levels of serum IgE and IgG1 were significantly higher in OVA sensitized mice. OVA challenge resulted in increased eosinophil infiltration, increased inflammatory cytokine production, peribronchiolar matrix and mucus deposition and airway hyperreactivity to aerosolized methacholine. Elevated lung NFκB and GATA-3 expression was noted in OVA-challenged mice. These changes were attenuated in mice fed with FO diet. Higher PPARγ expression was also detected in the lungs from the FO-fed groups.

Conclusion

Our results demonstrate that FO intake attenuated classical asthma features by suppressing the systemic sensitization, thus providing evidence that FO might be a prophylactic alternative for asthma prevention.