Rhinovirus (RV) infections in asthmatic patients are often associated with asthma exacerbation, characterized by worsened airways hyperreactivity and increased immune cell infiltration to the airways. The C-X-C chemokines, CXCL3 and CXCL5, regulate neutrophil trafficking to the lung via CXCR2, and their expression in the asthmatic lung is associated with steroid-insensitive type 2 inflammatory signatures. Currently, the role of CXCL3 and CXCL5 in regulating neutrophilic and type 2 responses in viral-induced asthma exacerbation is unknown. Inhibition of CXCL3 or CXCL5 with silencing RNAs in a mouse model of RV-induced exacerbation of asthma attenuated the accumulation of CXCR2+ neutrophils, eosinophils, and innate lymphoid cells in the lung and decreased production of type 2 regulatory factors IL-25, IL-33, IL-5, IL-13, CCL11, and CCL24. Suppression of inflammation was associated with decreased airways hyperreactivity, mucus hypersecretion, and collagen deposition. Similar results were obtained by employing RC-3095, which has been shown to bind to CXCR2, or by depletion of neutrophils. Our data demonstrate that CXCL3 and CXCL5 may be critical in the perpetuation of RV-induced exacerbation of asthma through the recruitment of CXCR2-positive neutrophils and by promoting type 2 inflammation. Targeting the CXCL3/CXCL5/CXCR2 axis may provide a new therapeutic approach to attenuating RV-induced exacerbations of asthma.
Biologics (mAbs) targeting pathways regulated by the type 2 cytokines IL-5 and IL-4/13 (IL-4R α) have yielded effective therapies for eosinophil-induced exacerbations of severe asthma. Despite these advances, difficulties remain in treating exacerbations, and this may reflect the contribution of other inflammatory cells such as neutrophils to pathogenesis.
Rhinovirus (RV) infection is a leading cause of asthma exacerbation in adults and children, accounting for the majority of hospitalized cases related to this disorder (1–5). Asthmatic patients with RV-induced exacerbations typically present with exaggerated inflammation, mucus production in the airways, and airways hyperreactivity (AHR), and conventional glucocorticoid therapy often has limited effects. Undertreated, persistent exacerbations can lead to airway remodeling because of angiogenesis and fibrogenesis and, over time, a decline in lung function (6–8). The lack of targeted therapies for the treatment of exacerbation remains a significant unmet clinical need and requires mechanistic investigations to identify future therapeutic approaches.
Neutrophil and eosinophil recruitment to the airways is a predominate feature of RV-induced exacerbation (9, 10). Eosinophil recruitment is regulated by the activation of CD4+ Th2 cells and innate lymphoid cells (ILC2s). However, this type 2 response can be amplified by neutrophils through the release of neutrophil extracellular traps (NETs) or proteases such as elastase (11–13). Neutrophils express the CXC motif receptor, CXCR2, which is activated by the CXC motif chemoattractant ligands CXCL-1, -2, -3,-5, and -8 (14–18). Of these, the chemokines CXCL3 and CXCL5 are distinct CXCL members because of their association with viral infections and type 2–driven inflammation (19, 20). CXCL3 may regulate the remodeling of airway smooth muscle in asthmatic subjects (17), whereas CXCL5 induces CXCL1 and CXCL2 expression in the lung (21). The expression of both chemokines was found to be epigenetically upregulated by the type 2 cytokine IL-13 (19) and are associated with the regulation of corticosteroid insensitivity in inflamed human primary bronchial epithelial cells (22). Although implicated in the mechanisms underlying the antiviral and asthmatic inflammatory responses, the exact role that CXCL3 and CXCL5 chemokines have in regulating RV-induced exacerbation of asthma has not been examined.
We have established a preclinical mouse model of RV-induced exacerbation on the background of Th2 cell–driven allergic airways disease (AAD) to investigate the role of CXCL3, CXCL5, and their receptor CXCR2 in disease induction and severity. RV serotype 1B (RV1B)–induced exacerbation of AAD was characterized by an exaggerated inflammatory response with increased leukocyte recruitment to the bronchoalveolar space, in addition to increased AHR, collagen deposition, mucus hypersecretion, and type 2 cytokines, all of which were associated with increased CXCL3 and CXCL5 production in the lung. Silencing RNAs (siRNAs) were then employed to inhibit protein translation of CXCL3 or CXCL5 before RV1B inoculation to investigate the therapeutic potential of targeting these chemokines. We also used RC-3095, a drug that has been demonstrated to bind to CXCR2 (23), to attenuate neutrophil chemotaxis as a novel intervention strategy to inhibit CXCL3/CXCL5 regulated recruitment of CXCR2-positive neutrophils during exacerbation.
Materials and Methods
Mice and specific treatments
Specific pathogen-free male BALB/c mice (6–8 wk old, littermates, n = 6–9 per group) were obtained from Central Animal House (University of Newcastle) and were housed in a specific pathogen-free environment. All experiments were conducted with approval from the Animal Care and Ethics Committee (University of Newcastle, Australia). AAD was induced by sensitizing mice to OVA (Sigma-Aldrich, Castle Hill, NSW, Australia) i.p. (50 μg/200 μl) on day 0 (or PBS only as a negative control) before being challenged with aerosolized OVA (1% in PBS) on days 13–16 for 30 min.
siRNAs targeting CXCL3 (5′-CAUCUAGUUUUGUAACUAU-3′) and CXCL5 (5′-GCUGCUUGUGUUUGCUUA-3′) or NONc siRNA were purchased from Thermo Fisher Scientific (North Ryde, NSW, Australia) and administered to mice intranasally (i.n.) on day 19 (3.75 nmol/30 μl) after being anesthetized with isoflurane. Alternatively, RC-3095 (Sigma-Aldrich) dissolved in PBS (5 mg/kg) using 5% DMSO or vehicle control (5% DMSO in PBS) was administered i.n. on day 19. Anti-mouse Ly6G mAb or isotype control (Bio X Cell) were administered i.p. on days 18 and 20. Human RV1B was obtained from the American Type Culture Collection and propagated using techniques previously described (23). Mice were inoculated (1 × 108 PFU/50 μl) i.n. with RV1B or UV-inactivated virus on day 20 under light isoflurane anesthesia. Mice were euthanized for removal of samples or assessed for AHR on day 24.
Assessment of AHR
Mice were anesthetized using ketamine (100 mg/kg) and xylazine (10 mg/ml, 200 μl; Troy Laboratories, Glendenning, NSW, Australia) before having their tracheas cannulated. Airway-specific resistance was measured using flexiVent apparatus (FX1 System; SCIREQ, Montreal, QC, Canada) to measure airway resistance (ventilation with a tidal volume of 8 ml/kg, 450 breaths/min) as previously described (24). Increasing doses of methacholine (Sigma-Aldrich) were nebulized and delivered to anesthetized mice to measure dose-dependent changes in airway resistance. The airway resistance for each methacholine dose was normalized as a percentage increase from baseline (PBS treatment).
Analysis of bronchoalveolar lavage fluid
HBSS was used to flush the right lung lobes of euthanized mice to collect cellular infiltrates in bronchoalveolar lavage fluid (BALF). BALF was RBC lysed, and total cell counts were measured via hemocytometry. Cells were cytospun onto a microscope slide and stained using May–Grünwald–Giemsa. Differential cell counts were performed blinded for each slide, with the total number each cell type determined as a percentage of the total cell counts per milliliter [as previously described (25)].
Quantification of cytokine and chemokine levels
Lung tissue was immersed in a solution of radioimmunoprecipitation assay buffer containing protease mixture inhibitors (Sigma-Aldrich, Melbourne, VIC, Australia) before being homogenized (TissueLyser LT platform; QIAGEN, Valencia, CA). Protein levels of CXCL3 (MyBioSource, San Diego, CA), CXCL5, CCL2, CCL11, IL-5, IL-13, IL-25, and IL-33 (R&D Systems, Noble Park, VIC, Australia) were quantified by ELISA in lung extracts. CXCL3 and CXCL5 were also measured in BALF supernatant. The OD of each sample for quantification was determined (SpectraMax M5; Molecular Devices, San Jose, CA). Chemokine and cytokine levels were normalized to total protein in lung and BALF supernatant (bicinchoninic acid [BCA]; Thermo Fisher Scientific).
RNA extraction and viral titer analysis
Whole lung immersed in RNA later (Ambion) underwent RNA extraction using TRIzol per the manufacturer’s instructions (Thermo Fisher Scientific). Isolated RNA suspended in chloroform was precipitated using isopropanol (Sigma-Aldrich), and RNA pellets were subsequently cleaned using ethanol and resuspended in nuclease-free water.
Reverse transcription of RNA into cDNA was employed using Moloney murine leukemia virus reverse transcriptase following the manufacturer’s instructions (Thermo Fisher Scientific). Expression levels of genes were then determined in duplicate using the ViiA7 quantitative PCR (qPCR) platform (Life Technologies) in the presence of SYBR Green reagents and primers targeting negative-sense RV1B (forward 5′-AGTCCTCCGGCCCCTGAATG-3′, reverse 5′-AAAGTAGTTGGTCCCATCCGC-3′). Relative expression of RV1B was determined using hypoxanthine-guanine phosphoribosyltransferase (HPRT) (forward 5′-AGGCCAGACTTTGTTGGATTTGAA-3′, reverse 5′-CAACTTGCGCTCATCTTAGGCTTT-3′).
Histological analysis of mouse lung
Mouse lung tissue was fixed in 10% neutral buffered formalin solution (Sigma-Aldrich) before being embedded in paraffin and sectioned onto a microscope slide (5 μm thick). The lung sections were stained for collagen (fibrosis) using Masson trichrome or mucous secretion using an Alcian blue (AB)-periodic acid–Schiff (PAS) staining protocol. Masson trichrome–stained lungs were photographed using a Zeiss Axio Imager microscope, and the total area of fibrosis (collagen deposition) over a set length of the airway epithelium was determined using Image-Pro Plus 7.0 software (Media Cybernetics). AP-PAS–stained lungs were used to enumerate mucus-secreting cells per high power field (×1000 magnification) as determined by light microscopy.
Flow cytometry analysis
Mouse lungs were suspended in HEPES buffer in the presence of DNase and collagenase (Sigma-Aldrich) before being dissociated using the GentleMACS system (Miltenyi Biotec). Cells suspensions were strained and RBC lysed, and total cell counts were determined using the Vi-CELL cell counter system (Beckman Coulter). Cells were Fc blocked on ice for 10 min before being incubated with Abs targeting lineage markers (allophycocyanin), CD45 (Brilliant Violet [BV] 711), CD25 (PE Cy7), CD90.2 (allophycocyanin Cy7) ICOS (PE), and T1/ST2 (BV421) for ILC2 enumeration; CD45 (BV711), Ly6G (PECF594), CD11b (PerCp5.5), and CXCR2 (allophycocyanin) for neutrophil/CXCR2 enumeration; or CD3e (BUV395), CD4 (BB700), B220 (BV650), CD44 (FITC), and IL-13 (PE) for Th2 cells (BioLegend). Cells were washed and fixed before being assessed on the Fortessa X-20 Flow Cytometer. Populations were gated using forward and side scatter, in which ILC2 populations were determined as CD45+ve, CD90.2+ve, lineage−ve, CD25+ve, ICOST+ve, and T1/ST2+ve. CXCR2-positive neutrophilic populations were identified as CD45+ve, Ly6G+ve, CD11b+ve, and CXCR2+ve. Th2 cells were stained as CD3e+ve, CD4+ve, B220−ve, CD44+ve, and IL-13+ve. All analysis was conducted using FlowJo software.
Statistical differences between groups were assessed using one-way ANOVA (Dunnett, multiple comparison test) or two-way ANOVA (Sidak) when interpreting lung function data. Statistical significance was determined if the p value was found to be <0.05 as determined using GraphPad Prism 7 software.
Inhibition of CXCL3 and CXCL5 reduces hallmark features of disease in a model of RV-induced asthma exacerbation
RV1B inoculation of mice with AAD induced a significant increase in the number of neutrophils, lymphocytes, macrophages, and eosinophils in the BALF (Fig. 1A), increased airway resistance (Fig. 1B), viral titer (Fig. 1C), and the initiation of pathophysiological features of airway remodeling such as mucus hypersecretion and collagen deposition (precursor to fibrosis) (Fig. 2). These features of exacerbation correlated with increased protein levels of CXCL3 and CXCL5 (Fig. 1D) in the lungs of RV-exposed mice by comparison with controls.
To understand the functional role that these chemokines play in the mechanism of exacerbation, siRNAs targeting CXCL3 or CXCL5 were administered 24 h before RV1B inoculation. Differential analysis of BALF cells showed that there was a significant reduction in the number of neutrophils, lymphocytes, and eosinophils (no significant changes in macrophage populations) after inhibition of CXCL3 or CXCL5 (Fig. 3A). Inhibition of CXCL3 or CXCL5 also attenuated RV1B-induced AHR (Fig. 3B), returning levels of reactivity to those observed in UV-inactivated RV1B-treated mice. Inhibition of CXCL3 or CXCL5 did not alter viral titers in the lungs of infected mice (Fig. 3C). Protein levels of CXCL3 or CXCL5 were reduced to baseline levels after siRNA treatment for each respective cytokine (Fig. 3D). Interestingly, siRNA targeting CXCL3 resulted in a significant reduction of CXCL5 protein levels, whereas CXCL3 levels in CXCL5-treated mice were not significantly altered. To show the specificity of these siRNAs reducing only its targets, we also ran an in vitro experiment using LA4 cells treated with OVA and RV1B in the presence or absence of CXCL3 or CXCL5 siRNAs (Supplemental Fig. 2).
CXCL3 and CXCL5 are key chemokines involved in regulating collagen deposition and mucus hypersecretion after RV1B exacerbation
Next, we examined the impact of inhibiting CXCL3 or CXCL5 on collagen deposition and mucus production (goblet hyperplasia), both processes linked to structural and functional alterations of the airways. RV inoculation in the presence of AAD induced a significant increase in collagen deposition and the production of mucus (Fig. 4). Administration of siRNAs targeting CXCL3 or CXCL5 significantly reduced the ability of RV to induce collagen deposition and enhance mucus production.
Increased levels of CXCL3 and CXCL5 induced by RV1B contribute to neutrophil influx and increased type 2 responses
We explored if siRNA inhibition of CXCL3 or CXCL5 during RV1B exposure was sufficient to reduce ILC2 populations as well as to attenuate the migration of neutrophils expressing CXCR2 to the lung. Flow cytometry analysis on cells isolated from whole lung demonstrated that ILC2-gated cells (T1/ST2+ve and ICOST+ve cells in Lin−ve, CD25+ve, CD90.2+ve, and CD45+ve populations), which were elevated in the nonsense control RV1B/OVA group, were subsequently suppressed upon siRNA treatment targeting either CXCL3 or CXCL5 (Fig. 5A).
As expected, RV1B induced increased levels of airway CXCR2+ neutrophils, which were CXCL3 and CXCL5 dependent (Fig. 5A). To determine if CXCL3 and CXCL5 also contribute to RV-induced exacerbation of AAD via type 2 inflammatory responses, we measured the protein levels of key effector molecules. Notably, RV exposure increased the protein levels of IL-25, IL-33, IL-5, IL-13, CCL11, and CCL24 (Fig. 5B), indicating that infection significantly amplifies the underlying type 2 response. siRNA inhibition of CXCL3 or CXCL5 resulted in a profound inhibition of these type 2 regulatory molecules. Thus, CXCL3 or CXCL5 play critical roles in regulating viral-induced neutrophilia and type 2 responses.
CXCR2 antagonism via RC-3095 administration reduces neutrophil influx, AHR, and type 2 responses
CXCL3- or CXCL5-dependent recruitment of CXCR2+ neutrophils directly correlated with the induction of RV1B-induced exacerbation of AAD. Therefore, we determined if inhibiting CXCR2 function using RC-3095 could also inhibit RV1B-induced exacerbations. Administration of RC-3095 to RV1B-exposed AAD mice resulted in a significant reduction in the number of infiltrating eosinophils and neutrophils in the BALF (Fig. 6A) as well as a marked reduction in AHR (Fig. 6B). No significant effects were observed in viral copy number after RC-3095 treatment (Fig. 6C). Furthermore, mucus production and collagen deposition were also significantly reduced in RC-3095–treated RV1B AAD mice (Fig. 6D).
ILC2 populations and CXCR2+ neutrophils were found to be significantly reduced within the lungs as a result of RC-3095 treatment (Fig. 7A) in RV1B-inoculated mice. Inhibition of inflammatory cell infiltration by treatment with RC-3095 was also associated with reduced protein levels of the type-2 molecules IL-25, IL-33, IL-5, IL-13, CCL11, and CCL24 (Fig. 7B). Thus, targeting the CXCL3/CXCL5/CXCR2 neutrophil chemotaxis pathway reduces disease severity (critical features of exacerbation such as AHR, neutrophilia, and notably, the underlying type 2 response) in a model of RV-induced asthma exacerbation.
We also show that RC-3095 treatment during RV1B-induced asthma exacerbation did not interfere with gastrin pathways. The levels of gastrin releasing peptide and its receptor were measured by qPCR in lung tissue and were not altered (Supplemental Fig. 1).
Neutrophil depletion with anti-Ly6g treatment during RV1B asthma exacerbation alleviates lung inflammation, with a reduction in the levels of AHR, CXCL3, and CXCL5
Neutrophils were depleted in RV1B-exacerbated mice using mAb-targeting Ly6G. The depletion of neutrophils alleviated lung inflammation, reducing the levels of neutrophils, lymphocytes, macrophages, and eosinophils in BALF (Fig. 8A). AHR was also reduced (Fig. 8B), even when the levels of RV1B were maintained high when compared with OVA RV1B-treated mice (Fig. 8C). Furthermore, the protein levels of CXCL3 and CXCL5, both in lung tissue and in BALF, were reduced when compared with OVA RV-treated mice (Fig. 8D). Neutrophil depletion also induced the reduction of lung fibrosis, collagen deposition (Fig. 9A), and mucus hypersecretion (Fig. 9B).
Neutrophil depletion with anti-Ly6G treatment during RV1B-induced asthma exacerbation reduced the expression of Th2 cell–associated cytokines in the whole lung
Total ILC2 cells, Th2 cells, and CXCR2+ neutrophils numbers were determined by flow cytometry after anti-Ly6G treatment. Depletion of neutrophils during RV1B induced asthma exacerbation in a pronounced inhibition of the inflammatory response and the type 2 component when compared with the OVA RV1B group (Fig. 10A). This group also showed a reduction of the levels of type 2 associated cytokines such as IL-5, IL-13, IL-25, IL-33, CCL11, and CCL24 (Fig. 10B).
Severe asthma exacerbations due to viral infections are associated with worsened disease outcomes and are often nonresponsive to mainstay therapies. The association of CXCL3 and CXCL5 with the expression of steroid-insensitive inflammatory signatures in airways cells is indicative that these chemokines may play integral roles in severe asthma exacerbation (22). Furthermore, both ligands recruit neutrophils and are associated with the expression of type 2 lung signatures (19). In vivo modeling of RV-induced exacerbation of AAD determined that both CXCL3 and CXCL5 are upregulated, and this correlates with induction of an exaggerated inflammatory response and AHR. siRNA-mediated inhibition of CXCL3 or CXCL5 function during RV-induced exacerbation of AAD resulted in reduced eosinophilia, neutrophilia, and AHR. Additionally, CXCL3 inhibition also resulted in a reduction in CXCL5 protein levels, which may be attributed to a reduction of eosinophilic-derived CXCL5 (26). Persistent uncontrolled asthma exacerbations are also associated with structural remodeling of the airways, most notable of which is the deposition of collagen in the basal epithelium of the airways as well as goblet cell hyperplasia. As previously demonstrated in RV1B exacerbation models of asthma, fibrotic deposition is a prominent feature (27). Treatment with siRNA also significantly reduced this feature in RV-induced exacerbation of AAD. We also observed significant reductions in the number of mucus-producing cells in the airways, suggesting that CXCL3 and CXCL5 are regulating IL-13–driven mucus production or alternative regulatory pathways during exacerbation.
Eosinophil expansion and homing to tissues, AHR, and mucus hypersecretion are regulated by the type 2 cytokines IL-5 and IL-13 (28, 29), the latter of which can induce the expression of the eosinophil chemotactic factors CCL11 and CCL24 (30). Indeed, IL-5, IL-13, CCL11, and CCL24 were found to be significantly upregulated by RV1B and downregulated post–siRNA treatment. Furthermore, siRNA knockdown of CXCL5 also reduced IL-25 and IL-33 expression. It has been established that RV1B infection of the airway epithelium promotes the secretion of both of these alarmin cytokines, and their expression is notably amplified in asthmatic patients (31, 32). The release of such factors results in an innate-driven allergic inflammatory cascade, with both IL-25 and IL-33 shown to be critical mediators of ILC2 activation and proliferation. The treatment of RV1B-inoculated AAD mice with siRNAs targeting CXCL3 and CXCL5 was associated with a reduction of ILC2s in the lungs, indicative that these chemokines promote early epithelial responses that trigger the release of these alarmin factors and subsequent ILC2 expansion.
As CXCL3 and CXCL5 are involved in neutrophil chemotaxis through CXCR2, we investigated if neutrophil recruitment was a factor involved in the secretion of epithelial alarmin factors and the promotion of type 2 responses and ILC2 expansion. Inhibition of CXCL3 or CXCL5 reduced the recruitment of CXCR2 positive neutrophils into RV1B exposed lungs. Administering RC-3095 to RV-exacerbated mice resulted in a significant reduction in both neutrophils and eosinophils recruitment into the BALF, in addition to CXCR2-positive neutrophils into RV1B-exposed lung tissue. Reductions in inflammation after RC-3095 treatment was directly associated with reduced AHR, mucus production, and collagen deposition within the airways. Notably, inhibition of these pathophysiological features correlated with a reduction in IL-25 and IL-33 expression, expansion of ILC2 cells, and the level of type 2 cytokines and eotaxins in the lung. These results indicate that neutrophilia is required for the induction of these type 2 responses during RV-induced exacerbation, which was confirmed using Ly6G Abs to directly inhibit neutrophils in this model. Furthermore, the reduction of both IL-25 and IL-33 after siRNA administration, in addition to RC-3095 treatment and Ly6G neutrophil inhibition, strongly suggests that CXCL3 and CXCL5 regulates the release of IL-25 and IL-33 through neutrophil recruitment to the airways and thus are a key driver of the subsequent inflammatory cascade involving ILC2 release of IL-5 and IL-13.
Although neutrophils are primarily associated with Th1/Th17-regulated host defense responses, our data and that of others indicate that these cells may also be involved in the perpetuation of type 2 responses during viral-induced exacerbation of asthma. Neutrophils can induce profound increases in type 2 cytokines through the release of NETs, which activate Th2 cells directly through the secretion of dsDNA (11). Additionally, neutrophils can compromise epithelial cell barrier function through the secretion of proinflammatory stimuli (33), and neutrophil elastase has been demonstrated to increase the biological activity of IL-33 (34). Collectively, this suggests that CXCL3- and CXCL5-recruited neutrophils may indirectly drive inflammation by compromising epithelial barrier function, which results in the subsequent release of ILC2-activating cytokines (e.g., IL-25 and IL-33). It is also plausible that neutrophils may release type 2 cytokines, as IL-33–polarized neutrophils in an OVA-induced asthma model were shown to secrete IL-4, IL-5, IL-9, and IL-13 (35). Furthermore, IL-33 suppresses antiviral responses in asthmatic patients while promoting NETosis of neutrophils and suppressing Th1-promoting dendritic cells (36). Additional studies must, therefore, be employed to elucidate if CXCL3- and CXCL5-recruited neutrophils are indirectly driving inflammation through NETs and epithelial barrier disruption, or if IL-33 interacting with neutrophilic factors, in part, influences these RV1B-induced exacerbations.
Although CXCR2 antagonists have not been explored clinically in regards to viral-induced exacerbation of asthma, antagonists have previously been administered to patients with severe neutrophilic asthma in a double-blinded placebo-controlled study. The CXCR2 antagonist significantly attenuated the frequency of mild exacerbations and inflammation (37), although its effectiveness specifically in viral-induced exacerbation remains unclear. Administration of CXCR2 antagonists to chronic obstructive pulmonary disease patients resulted in a reduction in pulmonary neutrophil numbers and a significant improvement of lung function (38). It is worth noting that chronic obstructive pulmonary disease pathophysiology is associated with both a compromised epithelium and elevated levels of a range of CXC ligands (39, 40), which are thought to be critical factors involved in RV-induced exacerbations of this disorder. Thus, we propose that inhibition of CXCR2 and its upstream ligands CXCL3 and CXCL5 are potential therapeutic targets that should be further explored in a clinical setting.
Our study suggests that the chemokines CXCL3 and CXCL5 may be critical in the perpetuation of RV-induced exacerbation of asthma through the recruitment of CXCR2-positive neutrophils that drive type 2 responses. Targeting the CXCL3/CXCL5/CXCR2 axis may provide a new therapeutic approach to attenuating RV-induced exacerbations of asthma.
We acknowledge the contributions of Fiona Eyers, Dr. Kelly Asquith, Dr. Hock Tay, Dr. Steven Maltby, Jessica Weaver, and Alyssa Lochrin, in addition to members of the Hunter Medical Research Institute Bioresources Facility and members of the Hunter Cancer Biobank, for support and expertise.
This work was supported by National Health and Medical Research Council Grant APP1120696.
The online version of this article contains supplemental material.
Abbreviations used in this article:
allergic airways disease
bronchoalveolar lavage fluid
innate lymphoid cell
neutrophil extracellular trap
RV serotype 1B
The authors have no financial conflicts of interest.