Increased expression of serine palmitoyl transferase and ORMDL3 polymorphism are associated with eosinophilic inflammation and airflow limitation in aspirin-exacerbated respiratory disease

Cannabinoid receptor 2 as a regulator of inflammation induced oleoylethanolamide in eosinophilic asthma

BACKGROUND

Oleoylethanolamide (OEA), an endogenously generated cannabinoid-like compound, has been reported to be increased in patients with severe asthma and aspirin-exacerbated respiratory disease. Recruitment of activated eosinophils in the airways is a hallmark of bronchial asthma.

OBJECTIVE

We explored the direct contribution of cannabinoid receptor 2 (CB2), a cognate receptor of OEA, which induces eosinophil activation in vitro and in vivo.

METHODS

We investigated OEA signaling in the eosinophilic cell line dEol-1 in peripheral blood eosinophils from people with asthma. In order to confirm whether eosinophil activation by OEA is CB2 dependent or not, CB2 small interfering RNA and the CB2 antagonist SR144528 were used. The numbers of airway inflammatory cells and the levels of cytokines were measured in bronchoalveolar lavage fluid, and airway hyperresponsiveness was examined in the BALB/c mice.

RESULTS

CB2 expression was increased after OEA treatment in both peripheral blood eosinophils and dEol-1 cells. It was also elevated after OEA-induced recruitment of eosinophils to the lungs in vivo. However, SR144528 treatment reduced the activation of peripheral blood eosinophils from asthmatic patients. Furthermore, CB2 knockdown decreased the activation of dEol-1 cells and the levels of inflammatory and type 2 cytokines. SR144528 treatment alleviated airway hyperresponsiveness and eosinophil recruitment to the lungs in vivo.

CONCLUSION

CB2 may contribute to the pathogenesis of eosinophilic asthma. Our results provide new insight into the molecular mechanism of signal transduction by OEA in eosinophilic asthma.

Lung Function and Asthma Clinical Control in N-ERD Patients, Three-Year Follow-Up in the Context of Real-World Evidence

Purpose

To describe the lung function and clinical control of asthma in patients with N-ERD during three years of medical follow-up using GINA guidelines.

Methods

We evaluated 75 N-ERD and 68 asthma patients (AG). Clinical control, lung function, and asthma treatment were evaluated according to GINA-2014. We compared all variables at baseline and one, two, and three years after treatment.

Results

At baseline, the N-ERD group had better basal lung function (LF) than the AG group (p<0.01), and the AG group used higher doses of inhaled corticosteroids than the N-ERD group (52.4% vs 30.5%, p=0.01) and short-term oral corticosteroid (OCS) use (52.4% vs 30.5%, p<0.01). Instead, N-ERD patients needed more use of leukotriene receptor antagonists (LTRA) (29.3% vs 5.9%, p<0.01). This group had better clinical control than the AG group (62.1% vs 34.1%, p<0.01). During the medical follow-up, the LF of the N-ERD group remained at normal values; however, these parameters improved in AG from one year (p<0.01). Likewise, there was a diminished use of high doses of ICS (52.4% vs 33%, p<0.05) and short-term OCS (67.6% vs 20.6%, p<0.01) in asthma patients. However, N-ERD patients still needed more use of LTRAs (p<0.02) during the study. In this context, one-third of N-ERD patients had to use a combination of two drugs to maintain this control. From the second year on, clinical control of asthma was similar in both groups (p>0.05).

Conclusion

According to GINA guidelines, only one-third of patients with N-ERD can gradually achieve adequate lung function and good asthma control with a high ICS dosage. Only a very small portion of patients will require the continued use of a second medication as an LTRA to keep their asthma under control.

Nasal Transcriptome and Epigenome Analysis Identifies the Pathogenic Features of Aspirin-Exacerbated Respiratory Disease

Dysregulation of the arachidonic acid metabolic pathway is the most widely known pathomechanism of aspirin-exacerbated respiratory disease (AERD). This study aimed to perform integrative analysis of transcriptomic and epigenomic profiling with network analysis to determine the novel pathogenic features of AERD. Ten patients with asthma including 5 patients with AERD and another 5 patients with aspirin tolerant asthma (ATA) were enrolled. Nasal scraping was performed and nasal mucosa was used in omics profiling. Peripheral eosinophil counts, sputum eosinophil counts, fractional exhaled nitric oxide levels, and pulmonary function test results were evaluated. Differentially expressed genes (DEGs), differentially methylated probes (DMPs) and differentially correlated genes (DCGs) between patients with AERD and those with ATA were analyzed. Network analysis using ingenuity pathway analysis (IPA) was performed to determine the gene connection network and signaling pathways. In total, 1,736 DEGs, 1,401 DMPs, and 19 pairs for DCGs were identified. Among DCGs, genes related to vesicle transport (e.g., RAB3B and STX2) and sphingolipid dysregulation (e.g., SMPD3) were found to be hypo-methylated and up-regulated in AERD. Using the canonical pathway analysis of IPA with 78 asthma-related DEGs, signaling pathways of T helper cell differentiation/activation and Fcε receptor I were generated. Up-regulation of RORγt and FcER1A were noted in AERD. Gene expression levels of RAB3B, SYNE1, STX2, SMPD3 and RORγt were significantly associated with sputum eosinophil counts. Quantitative real-time polymerase chain reaction was performed and mRNA expression levels of STX2, SMPD3, RORγt, and FcER1A were significantly higher in AERD compared to ATA. Distinct pathogenic features were identified by using integrative multi-omics data analysis in patients with AERD.

Interactions between microbiome and underlying mechanisms in asthma

Microbiome primes host innate immunity in utero and play fundamental roles in the development, training, and function of the immune system throughout the life. Interplay between the microbiome and immune system maintains mucosal homeostasis, while alterations of microbial community dysregulate immune responses, leading to distinct phenotypic features of immune-mediated diseases including asthma. Microbial imbalance within the mucosal environments, including upper and lower airways, skin, and gut, has consistently been observed in asthma patients and linked to increased asthma exacerbations and severity. Microbiome research has increased to uncover hidden microbial members, function, and immunoregulatory effects of bacterial metabolites within the mucosa. This review provides an overview of environmental and genetic factors that modulate the composition and function of the microbiome, and the impacts of microbiome metabolites and skin microbiota on immune regulation in asthma.

Persistent Eosinophilic Inflammation in Adult Asthmatics with High Serum and Urine Levels of Leukotriene E4

Background

Cysteinyl leukotrienes (CysLTs) are key mediators for bronchoconstriction, eosinophil recruitment and mucus production in the airways of asthmatic patients. To better understand the role of CysLTs in different asthma phenotypes, we compared the levels of arachidonic acid metabolites in relation to asthma control status and phenotypes in adult asthmatics on regular anti-asthma medications.

Methods

A total of 137 adult asthmatics (47 with aspirin-exacerbated respiratory disease [AERD] and 90 asthmatics with aspirin-tolerant asthma [ATA]) and 20 healthy controls were enrolled. Arachidonic acid metabolites in serum and urine were analyzed using LC-MS/MS methods, and clinical data, including asthma control status, exhaled NO (FeNO) and lung function tests, were collected.

Results

Urine LTE₄ levels were significantly higher in AERD patients on inhaled corticosteroid-long-acting β₂- agonist plus leukotriene receptor antagonist (LTRA) treatment than in ATA patients (P=0.001). No differences were found in the serum or urine levels of 15-HETE, TXB_2, or PGF_2α. High serum LTE₄ levels were associated with lower FEV1% and uncontrolled status in AERD patients (P=0.006 and P=0.002, respectively), but not in ATA patients. Multivariate analysis demonstrated that blood eosinophil counts, FeNO levels and aspirin hypersensitivity were significant factors affecting urine LTE₄ levels.

Conclusion

Despite LTRA treatment in AERD, the LTE₄ levels remained high and showed close associations with blood eosinophilia, high FeNO levels and impaired disease control. Our real-world evidence indicates that control of asthma is not fully achieved by blocking the CysLT pathway with LTRA. Thus, introduction of treatment modalities targeting eosinophilia could be a better option for patients with high CysLTs.

Pathomechanisms of AERD—Recent Advances

The pathomechanisms behind NSAID-exacerbated respiratory disease are complex and still largely unknown. They are presumed to involve genetic predisposition and environmental triggers that lead to dysregulation of fatty acid and lipid metabolism, altered cellular interactions involving transmetabolism, and continuous and chronic inflammation in the respiratory track. Here, we go through the recent advances on the topic and sum up the current understanding of the background of this illness that broadly effects the patients' lives.

Contribution of dipeptidyl peptidase 10 to airway dysfunction in patients with NSAID-exacerbated respiratory disease

BACKGROUND

Genetic variants of dipeptidyl peptidase 10 (DPP10) have been suggested to contribute to the development of NSAID-exacerbated respiratory disease (NERD). However, the mechanisms of how DPP10 contributes to NERD phenotypes remain unclear.

OBJECTIVE

To demonstrate the exact role of DPP10 in the pathogenesis of NERD.

METHODS

Patients with NERD (n = 110), those with aspirin-tolerant asthma (ATA, n = 130) and healthy control subjects (HCs, n = 80) were enrolled. Clinical characteristics were analysed according to the serum DPP10 levels in both NERD and ATA groups. The function of DPP10 in airway inflammation and remodelling was investigated with in vitro, ex vivo and in vivo experiments.

RESULTS

NERD patients had higher levels of serum DPP10 and TGF-β1 with lower FEV₁ than ATA patients or HCs (p < .05 for each). NERD patients with higher DPP10 levels had higher TGF-β1, but lower FEV₁ (p < .05 for all), whilst no differences were noted in ATA patients. Moreover, the seum DPP10 levels had a positive correlation with TGF-β1 (r = 0.384, p < .001), but a negative correlation with FEV₁ (r = -0.230, p = .016) in NERD patients. In in vitro studies, expression of DPP10 in airway epithelial cells was enhanced by TGF-β1 treatments. Furthermore, DPP10 was found to be produced from immune cells and this molecule induced the ERK phosphorylation in airway epithelial cells, which was suppressed by anti-DPP10 treatment. In asthmatic mouse models, increased levels of DPP10 in the serum and TGF-β1 in the bronchoalveolar lavage fluid were noted, which were suppressed by anti-DPP10 treatment. Moreover, anti-DPP10 treatment inhibited the ERK phosphorylation and extracellular matrix deposition in the lungs.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings suggest that increased production of DPP10 may contribute to TGF-β1-mediated airway dysfunction in NERD patients, where blockade of DPP10 may have potential benefits.