Sputum Transcriptomics Reveals FCN1+ Macrophage Activation in Mild Eosinophilic Asthma Compared to Non-Asthmatic Eosinophilic Bronchitis.

PURPOSE: Eosinophilic asthma (EA) and non-asthmatic eosinophilic bronchitis (EB) share similar eosinophilic airway inflammation. Unlike EA, EB did not present airway hyperresponsiveness or airflow obstruction. We aimed to compare the mechanism underlying the different manifestations between EA and EB via sputum transcriptomics analysis. METHODS: Induced-sputum cells from newly physician-diagnosed EA, EB patients, and healthy controls (HCs) were collected for RNA sequencing. RESULTS: Bulk RNA sequencing was performed using sputum cells from patients with EA (n = 18), EB (n = 15) and HCs (n = 28). Principal component analysis revealed similar gene expression patterns in EA and EB. The most differentially expressed genes in EB compared with HC were also shared by EA, including IL4, IL5 IL13, CLC, CPA3, and DNASE1L3. However, gene set enrichment analysis showed that the signatures regulating macrophage activation were enriched in EA compared to EB. Sputum cells were profiled using single-cell RNA sequencing. FABP4+ macrophages, SPP1+ macrophages, FCN1+ macrophages, dendritic cells, T cells, B cells, mast cells, and epithelial cells were identified based on gene expression profiling. Analysis of cell-cell communication revealed that interactions between FCN1+ macrophages and other cells were higher in EA than in EB. A wealth of transforming growth factor beta (TGF-ß) and vascular endothelial growth factor (VEGF) interactions between FCN1+ macrophages and other cells have been shown in EA. The gene expression levels of EREG, TGFBI, and VEGFA in FCN1+ macrophages of EA were significantly higher than those of EB. Furthermore, signatures associated with the response to TGF-ß, cellular response to VEGF stimulus and developmental cell growth were enriched in FCN1+ macrophages of EA compared to those of EB. CONCLUSIONS: FCN1+ macrophage activation associated with airway remodeling processes was upregulated in EA compared to that in EB, which may contribute to airway hyperresponsiveness and airflow obstruction.

Predictive value of clinical features for anti-reflux therapy response in suspected gastroesophageal reflux-induced chronic cough.

Background: Not all gastroesophageal reflux-induced cough (GERC) patients respond to anti-reflux treatment. It is not certain whether reflux-related symptoms or other clinical characteristics could indicate a successful response to anti-reflux treatment. In this study, we aimed to investigate the relationship between clinical features and anti-reflux response. Methods: We retrospectively analyzed the clinical characteristics of suspected GERC who had reflux-related symptoms or reflux evidence based on abnormal 24-hour esophageal pH value monitoring, or who had no evidence of other common causes of chronic cough in our chronic cough database with a standard case report form. All patients experienced anti-reflux treatment with proton pump inhibitors (PPIs) plus prokinetic agents for at least 2 weeks and were divided into responders and non-responders based on the treatment response. Results: Among 241 patients with suspected GERC, 146 (60.6%) showed a successful response. There was no significant difference in regard to the proportion of reflux-related symptoms, and results of 24-hour esophageal pH value monitoring between responders and non-responders. Compared with non-responders, responders had higher proportions of nasal itching (21.2% vs. 8.4%; P=0.014), tickle in the throat (51.4% vs. 35.8%; P=0.025) and lower proportion of pharyngeal foreign body sensation (32.9% vs. 54.7%; P=0.001). Multivariate analysis showed that nasal itching [hazard ratio (HR): 1.593, 95% confidence interval (CI): 1.025-2.476, P=0.039], tickle in the throat (HR: 1.605, 95% CI: 1.152-2.238, P=0.005), pharyngeal foreign body sensation (HR: 0.499, 95% CI: 0.346-0.720, P<0.001) and sensitivity to at least one cough trigger (HR: 0.480, 95% CI: 0.237-0.973, P=0.042) were associated with the therapeutic response. Conclusions: Over half of suspected GERC patients benefited from anti-reflux therapy. A few clinical features rather than reflux-related symptoms might indicate a response to anti-reflux treatment. Further study is needed for the predictive value.

A descending pathway emanating from the periaqueductal gray mediates the development of cough-like hypersensitivity.

Chronic cough is a common refractory symptom of various respiratory diseases. However, the neural mechanisms that modulate the cough sensitivity and mediate chronic cough remain elusive. Here, we report that GABAergic neurons in the lateral/ventrolateral periaqueductal gray (l/vlPAG) suppress cough processing via a descending pathway. We found that l/vlPAG neurons are activated by coughing-like behaviors and that tussive agent-evoked coughing-like behaviors are impaired after activation of l/vlPAG neurons. In addition, we showed that l/vlPAG neurons form inhibitory synapses with the nucleus of the solitary tract (NTS) neurons. The synaptic strength of these inhibitory projections is weaker in cough hypersensitivity model mice than in naïve mice. Important, activation of l/vlPAG GABAergic neurons projecting to the NTS decreases coughing-like behaviors. In contrast, suppressing these neurons enhances cough sensitivity. These results support the notion that l/vlPAG GABAergic neurons play important roles in cough hypersensitivity and chronic cough through disinhibition of cough processing at the medullary level.