Surfactant protein D alleviates eosinophil-mediated airway inflammation and remodeling in patients with aspirin-exacerbated respiratory disease.

BACKGROUND: Surfactant protein D (SPD) is a member of the collectin family that lines the airway epithelial cells with host defense. However, the role of SPD in the pathogenesis of aspirin-exacerbated respiratory disease (AERD) is still unclear. METHODS: The serum SPD level was measured in patients with AERD (n = 336), those with aspirin-tolerant asthma (ATA, n = 442), and healthy controls (HC, n = 104). Polymorphisms of SFTPD in the study subjects were analyzed. The effect of LTE4 on SPD production through eosinophil infiltration was investigated in BALB/c mice. The protective function of SPD against eosinophils inducing inflammation and remodeling was assessed in vitro/vivo. The potential efficacy of nintedanib against airway remodeling through the production of SPD was evaluated. RESULTS: The serum SPD level was significantly lower (P < .001) in AERD compared with ATA patients, and negatively correlated with fall in FEV1 (%) after lysine-aspirin bronchoprovocation test and/or the urinary LTE4 level. In addition, polymorphism of SFTPD at rs721917 was significantly different in the study subjects (odds ratio, 1.310; 95% confidence intervals, 2.124-3.446; P = .002). LTE4-exposed mice showed an increased eosinophil count with a decreased SPD level in bronchoalveolar lavage fluid. Eosinophils increased α-smooth muscle actin expression in airway epithelial cells, which was attenuated by SPD treatment. Furthermore, nintedanib protected the airway epithelial cells against eosinophils by enhancing the production of SPD. CONCLUSION: The decreased level of SPD in AERD was associated with airway inflammation/remodeling under the eosinophilic condition, suggesting that modulation of SPD may provide a potential benefit in AERD.

Neutrophil autophagy and extracellular DNA traps contribute to airway inflammation in severe asthma.

BACKGROUND: Autophagy and neutrophil extracellular DNA traps (NETs) are implicated in asthma; however, their roles in asthma pathogenesis have not been elucidated. OBJECTIVES: We compared autophagy and NET production levels from peripheral blood neutrophils (PBNs) of patients with severe asthma (SA) and non-severe asthma (NSA). Additionally, we investigated the inflammatory effects of NETs on human airway epithelial cells (AECs) and peripheral blood eosinophils (PBEs). METHODS: Peripheral blood neutrophils from patients with SA (n = 30) and NSA (n = 38) were treated with interleukin (IL)-8 (100 ng/mL). Autophagy (light chain 3-II expression) and NET production levels were evaluated by Western blot, immunofluorescence microscopy, and PicoGreen assay. The effects of NETs on AECs were assessed by investigating cell death, cell detachment, expression of occludin and claudin-1, and IL-8 production; the effects of NETs on PBEs were examined by investigating the activation and release of eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN). RESULTS: Untreated and IL-8-treated PBNs from the SA group produced higher autophagy and NET levels compared with those from the NSA group (P < 0.01). IL-8 increased autophagy and NET levels in PBNs from the SA group, but not from the NSA group. NET levels were correlated with autophagy levels in PBNs (P < 0.001). IL-8-induced NET production levels negatively were correlated with FEV1/FVC (r = -0.700, P = 0.016). NETs induced cell death, detachment, degradation of occludin and claudin-1, and IL-8 production from AECs. Higher levels of NET-induced ECP and EDN were released from PBEs in SA compared with NSA groups. CONCLUSIONS AND CLINICAL RELEVANCE: Neutrophil autophagy and NETs could enhance asthma severity by damaging airway epithelium and triggering inflammatory responses of AECs and PBEs. Modulating neutrophil autophagy and NET production may be a new target therapy for SA.

Metabolomic analysis identifies potential diagnostic biomarkers for aspirin-exacerbated respiratory disease.

BACKGROUND: To date, there has been no reliable in vitro test to diagnose aspirin-exacerbated respiratory disease (AERD). OBJECTIVE: To investigate potential diagnostic biomarkers for AERD using metabolomic analysis. METHODS: An untargeted profile of serum from asthmatics in the first cohort (group 1) comprising 45 AERD, 44 patients with aspirin-tolerant asthma (ATA), and 28 normal controls was developed using the ultra-high-performance liquid chromatography (UHPLC)/Q-ToF MS system. Metabolites that discriminate AERD from ATA were quantified in both serum and urine, which were collected before (baseline) and after the lysine-aspirin bronchoprovocation test (Lys-ASA BPT). The serum metabolites were validated in the second cohort (group 2) comprising 50 patients with AERD and 50 patients with ATA. RESULTS: A clear discrimination of metabolomes was found between patients with AERD and ATA. In group 1, serum levels of LTE4 and LTE4 /PGF2 α ratio before and after the Lys-ASA BPT were significantly higher in patients with AERD than in patients with ATA (P < 0.05 for each), and urine baseline levels of these two metabolites were significantly higher in patients with AERD. Significant differences of serum metabolite levels between patients with AERD and ATA were replicated in group 2 (P < 0.05 for each). Moreover, serum baseline levels of LTE4 and LTE4 /PGF2 α ratio discriminated AERD from ATA with 70.5%/71.6% sensitivity and 41.5%/62.8% specificity, respectively (AUC = 0.649 and 0.732, respectively P < 0.001 for each). Urine baseline LTE4 levels were significantly correlated with the fall in FEV1 % after the Lys-ASA BPT in patients with AERD (P = 0.008, r = 0.463). CONCLUSIONS AND CLINICAL RELEVANCE: Serum metabolite level of LTE4 and LTE4 /PGF2 α ratio was identified as potential in vitro diagnostic biomarkers for AERD using the UHPLC/Q-ToF MS system, which were closely associated with major pathogenetic mechanisms underlying AERD.

Identification of phenotypic clusters of nonsteroidal anti-inflammatory drugs exacerbated respiratory disease.

BACKGROUND: Clinical presentation of nonsteroidal anti-inflammatory drugs exacerbated respiratory disease (NERD) is found to be heterogeneous. This study classified phenotypic clusters to determine NERD subtypes. METHODS: We performed two-step cluster analysis using urticaria, chronic rhinosinusitis (CRS), and atopy, in a NERD cohort comprising 302 patients. Asthma exacerbation was defined as receiving at least one burst of intravenous steroid treatment and/or at least two bursts of oral steroid use (≥ 45 mg/3 days) per year. The possession rate of anti-asthmatic medications was estimated during the follow-up period. RESULTS: There were four subtypes: subtype 1 (NERD with CRS/atopy and no urticaria), subtype 2 (NERD with CRS and no urticaria/atopy), subtype 3 (NERD without CRS/urticaria), and subtype 4 (NERD with urticaria). Significant differences were found between the four subtypes in the female proportion, baseline FEV1%, serum total IgE level, and sputum/peripheral eosinophil count. A higher frequency of asthma exacerbations was noted in subtype 1 compared to subtype 3. The possession rates of medium- to high-dose inhaled corticosteroids/long-acting beta2 -agonists showed significant differences among the four subtypes. Metabolomic analysis showed that the four subtypes of NERD had a higher serum leukotriene E4 (LTE4) level than those with aspirin-tolerant asthma. The patients with subtypes 1 and 3 had a higher urine LTE4 level than those with subtype 2. CONCLUSION: We found four distinct subtypes with different clinical/biochemical findings and asthma exacerbations in a NERD cohort. These findings suggest that stratified strategies by applying subtype classification may help achieve better outcomes in the management of NERD.

Drug-specific CD4+ T-cell immune responses are responsible for antituberculosis drug-induced maculopapular exanthema and drug reaction with eosinophilia and systemic symptoms syndrome.

BACKGROUND: A multidrug regimen including isoniazid, rifampicin, pyrazinamide and ethambutol is commonly used as first-line treatment for tuberculosis. However, this regimen can occasionally result in severe adverse drug reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome and drug-induced liver injury. The culprit drug and mechanistic basis for the hypersensitive reaction are unknown. OBJECTIVES: To investigate drug-specific T-cell responses in patients with antituberculosis drug (ATD)-induced cutaneous hypersensitivity and its underlying mechanism. METHODS: We enrolled eight patients with ATD-induced maculopapular exanthema and DRESS and performed a lymphocyte transformation test. Subsequently, drug-specific T-cell clones were generated from four of the patients who showed proliferation in response to ATDs. We measured the drug-specific proliferative responses and counted the drug-specific interferon (IFN)-γ/granzyme B-producing cells after drug stimulation. Antihuman leukocyte antigen (HLA) class I and class II blocking antibodies were used to analyse human leukocyte antigen-restricted T-cell responses. RESULTS: Positive proliferative responses to ATDs were mostly found in patients with cutaneous hypersensitivity. Furthermore, we isolated isoniazid/rifampicin-specific T cells from patients, which consisted primarily of CD4+ T cells. Drug-specific CD4+ T cells proliferated and secreted IFN-γ/granzyme B when stimulated with isoniazid or rifampicin, respectively. Isoniazid-responsive T-cell clones did not proliferate in the presence of rifampicin and vice versa. Drug-specific T-cell responses were blocked in the presence of anti-HLA class II antibodies. CONCLUSIONS: This study identifies the presence of isoniazid/rifampicin-specific T cells in patients with ATD-induced maculopapular exanthema and DRESS. Furthermore, it highlights the important role of drug-specific T-cell immune responses in the pathogenesis of these reactions.

Autophagy mechanisms in sputum and peripheral blood cells of patients with severe asthma: a new therapeutic target.

BACKGROUND: Autophagy and genetic predisposition have been suggested to potentially play roles in the development of asthma. However, little is known about the role of autophagy in the pathogenesis of severe asthma. OBJECTIVE: We compared autophagy in the sputum granulocytes, peripheral blood cells (PBCs) and peripheral blood eosinophils (PBEs) between patients with severe asthma and those with non-severe asthma and investigated the functional effects of autophagy. METHODS: We enrolled 36 patients with severe asthma, 14 with non-severe asthma and 23 normal healthy controls in this study. Sputum granulocytes, PBCs and PBEs were isolated from each subject. Autophagy was evaluated based on the expression of microtubule-associated protein light chain 3 (LC3) by Western blot, confocal microscopy, transmission electron microscopy and flow cytometry. IL-8 levels were measured by ELISA. To induce autophagy, HL-60 cells, human primary small airway epithelial cells (SAECs) and A549 cells were treated with IL-5, IL-1ß and TNF-α. To inhibit autophagy, PI3K inhibitors (LY29400 and 3-methyladenine [3-MA]) and hydroxychloroquine (HCQ) were used. Knockdown of ATG5 and Beclin-1 was performed in A549 cells, and the therapeutic effects of dexamethasone were evaluated. RESULTS: Higher autophagy levels were noted in sputum granulocytes, PBCs and PBEs from patients with severe asthma than from patients with non-severe asthma and healthy controls (P < 0.05 for all). IL-5 increased autophagy levels in both PBCs and PBEs (P < 0.05). 3-MA attenuated the increased expression of LC3-II and eosinophil cationic protein in HL-60 cells induced by IL-5 (P = 0.034 for both). Dexamethasone did not affect autophagy levels in PBEs. IL-1ß increased LC3-II expression and IL-8 production (P < 0.01) in SAECs, and this was attenuated by LY294002, 3-MA, HCQ and knockdown of ATG5 and Beclin-1 (in A549 cells) (P < 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Autophagy could play a role in the pathogenesis of severe asthma. Autophagy modulation may be a novel therapeutic target for conventional therapy-resistant severe asthma.