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-ß1 with lower FEV1 than ATA patients or HCs (p < .05 for each). NERD patients with higher DPP10 levels had higher TGF-ß1, 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-ß1 (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-ß1 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-ß1 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-ß1-mediated airway dysfunction in NERD patients, where blockade of DPP10 may have potential benefits.

Skin-resident natural killer T cells participate in cutaneous allergic inflammation in atopic dermatitis.

BACKGROUND: Natural killer T (NKT) cells are unconventional T cells that bridge innate and adaptive immunity. NKT cells have been implicated in the development of atopic dermatitis (AD). OBJECTIVE: We aimed to investigate the role of NKT cells in AD development, especially in skin. METHODS: Global proteomic and transcriptomic analyses were performed by using skin and blood from human healthy-controls and patients with AD. Levels of CXCR4 and CXCL12 expression in skin NKT cells were analyzed in human AD and mouse AD models. By using parabiosis and intravital imaging, the role of skin CXCR4+ NKT cells was further evaluated in models of mice with AD by using CXCR4-conditionally deficient or CXCL12 transgenic mice. RESULTS: CXCR4 and its cognate ligand CXCL12 were significantly upregulated in the skin of humans with AD by global transcriptomic and proteomic analyses. CXCR4+ NKT cells were enriched in AD skin, and their levels were consistently elevated in our models of mice with AD. Allergen-induced NKT cells participate in cutaneous allergic inflammation. Similar to tissue-resident memory T cells, the predominant skin NKT cells were CXCR4+ and CD69+. Skin-resident NKT cells uniquely expressed CXCR4, unlike NKT cells in the liver, spleen, and lymph nodes. Skin fibroblasts were the main source of CXCL12. CXCR4+ NKT cells preferentially trafficked to CXCL12-rich areas, forming an enriched CXCR4+ tissue-resident NKT cells/CXCL12+ cell cluster that developed in acute and chronic allergic inflammation in our models of mice with AD. CONCLUSIONS: CXCR4+ tissue-resident NKT cells may form a niche that contributes to AD, in which CXCL12 is highly expressed.

Eosinophil extracellular traps activate type 2 innate lymphoid cells through stimulating airway epithelium in severe asthma.

BACKGROUND: Activated eosinophils release extracellular traps (EETs), which contribute to airway inflammation in severe asthma (SA). However, the role of EETs in innate immunity has not yet been completely determined. The present study aimed to demonstrate the mechanism of airway inflammation in SA mediated by EETs. METHODS: Peripheral counts of EET+ eosinophils and type 2 innate lymphoid cells (ILC2s) were evaluated in patients with SA (n = 13), nonsevere asthma (NSA, n = 17), and healthy control subjects (HC, n = 8). To confirm the effect of EETs, airway hyperresponsiveness (AHR) and adapted/innate immune responses were assessed in mice. Furthermore, the effects of anti-IL-33/TSLP antibody were tested. RESULTS: The numbers of EET+ eosinophils and ILC2s were significantly elevated in SA, with a positive correlation between these two cells (r = .539, P < .001). When mice were injected with EETs, we observed significant increases in epithelium-derived cytokines (IL-1α, IL-1ß, CXCL-1, CCL24, IL-33, and TSLP) and eosinophil/neutrophil count in bronchoalveolar lavage fluid (BALF) as well as an increased proportion of IL-5- or IL-13-producing ILC2s in the lungs. When Rag1-/- mice receiving ILC2s were treated with EETs, increased AHR and IL-5/IL-13 levels in BALF were noted, which were effectively suppressed by anti-IL-33 or anti-TSLP antibody. CONCLUSION: EETs could enhance innate and type 2 immune responses in SA, in which epithelium-targeting biologics (anti-IL-33/TSLP antibody) may have a potential benefit.

Inhibitory Effect of Chebulic Acid on Alveolar Epithelial to Mesenchymal Transition in Response to Urban Particulate Matter Using Co-treatment and Post-treatment Exposure.

Urban particulate matter (UPM) is atmospheric particulate samples obtained from industrialized urban areas. It is known that pulmonary fibrosis can result directly or indirectly from particulate matter. In this study, the protective effect of chebulic acid (CA) against UPM-induced epithelial-mesenchymal transition (EMT) in the pulmonary alveolar epithelial (PAE) cells were investigated. Our findings revealed that PAE cells were changed from the epithelial phenotype to mesenchymal one after exposure to UPM. Furthermore, co-treatment and post-treatment of CA inhibited EMT progression. Especially the key epithelial marker, E-cadherin, was down-regulated by UPM and recovered by CA. Also, gelatin zymogram showed that the activity of matrix metalloproteinase (MMP)-2 and MMP-9 was decreased by co-treatment and post-treatment of CA. Further investigation revealed that CA attenuated UPM-stimulated PAE cells invasion ability. These data showed that UPM promoted PAE cells invasion, reactive oxygen species-mediated extracellular matrix degradation and CA reduced the potential health risks associated with UPM.

Protective effects of chebulic acid on alveolar epithelial damage induced by urban particulate matter.

BACKGROUND: Chebulic acid (CA) isolated from T. chebula, which has been reported for treating asthma, as a potent anti-oxidant resources. Exposure to ambient urban particulate matter (UPM) considered as a risk for cardiopulmonary vascular dysfunction. To investigate the protective effect of CA against UPM-mediated collapse of the pulmonary alveolar epithelial (PAE) cell (NCI-H441), barrier integrity parameters, and their elements were evaluated in PAE. METHODS: CA was acquired from the laboratory previous reports. UPM was obtained from the National Institutes of Standards and Technology, and these were collected in St. Louis, MO, over a 24-month period and used as a standard reference. To confirm the protection of PAE barrier integrity, paracellular permeability and the junctional molecules were estimated with determination of transepithelial electrical resistance, Western Blotting, RT-PCR, and fluorescent staining. RESULTS: UPM aggravated the generation of reactive oxygen species (ROS) in PAE and also decreased mRNA and protein levels of junction molecules and barrier integrity in NCI-H441. However, CA repressed the ROS in PAE, also improved barrier integrity by protecting the junctional parameters in NCI-H411. CONCLUSIONS: These data showed that CA resulted in decreased UPM-induced ROS formation, and the protected the integrity of the tight junctions against UPM exposure to PAE barrier.

Immunoregulatory effects of Lactococcus lactis-derived extracellular vesicles in allergic asthma.

BACKGROUND: Probiotics have been shown to prevent various allergic diseases by producing extracellular vesicles (EVs). However, the role of EVs in allergic asthma has not yet been completely determined. METHODS: Gut microbial composition, mainly genera related to probiotics, was investigated in allergic asthmatic mice. Moreover, EVs were isolated from Lactococcus lactis (L. lactis, a selected bacterium) and EV proteins were identified by peptide mass fingerprinting. EV functions in immune responses were evaluated in vivo or ex vivo. Furthermore, the levels of specific IgG antibodies (an alternative marker for EV quantification) to L. lactis-EVs were measured by ELISA in the sera of 27 asthmatic patients and 26 healthy controls. RESULTS: Allergic asthmatic mice showed a lower proportion of Lactococcus compared to healthy mice. L. lactis was cultured and its EVs abundantly contained pyruvate kinase. When allergic asthmatic mice were intranasally treated with EVs, airway hyperresponsiveness, eosinophil number, cytokine secretion, and mucus production were significantly decreased. Moreover, L. lactis-EV treatment shifted immune responses from Th2 to Th1 by stimulating dendritic cells to produce IL-12. In addition, significantly lower levels of serum specific IgG4 (but not IgG1) to L. lactis-EVs were noted in asthmatic patients than in healthy controls. A positive correlation between the levels of EV-specific IgG4 and FEV1 (%), but a negative correlation between the levels of EV-specific IgG4 and IL-13 were observed. CONCLUSION: These findings suggest that L. lactis-EVs may have immune-regulating effects on airway inflammation mediated by dendritic cell activation, providing a potential benefit for allergic asthma.

Effect of TGF-ß1 on eosinophils to induce cysteinyl leukotriene E4 production in aspirin-exacerbated respiratory disease.

Cysteinyl leukotriene (cysLT) overproduction and eosinophil activation are hallmarks of aspirin-exacerbated respiratory disease (AERD). However, pathogenic mechanisms of AERD remain to be clarified. Here, we aimed to find the significance of transforming growth factor beta 1 (TGF-ß1) in association with cysteinyl leukotriene E4 (LTE4) production, leading to eosinophil degranulation. To evaluate levels of serum TGF-ß1, first cohort enrolled AERD (n = 336), ATA (n = 442) patients and healthy control subjects (HCs, n = 253). In addition, second cohort recruited AERD (n = 34) and ATA (n = 25) patients to investigate a relation between levels of serum TGF-ß1 and urinary LTE4. The function of TGF-ß1 in LTE4 production was further demonstrated by ex vivo (human peripheral eosinophils) or in vivo (BALB/c mice) experiment. As a result, the levels of serum TGF-ß1 were significantly higher in AERD patients than in ATA patients or HCs (P = .001; respectively). Moreover, levels of serum TGF-ß1 and urinary LTE4 had a positive correlation (r = 0.273, P = .037). In the presence of TGF-ß1, leukotriene C4 synthase (LTC4S) expression was enhanced in peripheral eosinophils to produce LTE4, which sequentially induced eosinophil degranulation via the p38 pathway. When mice were treated with TGF-ß1, significantly induced eosinophilia with increased LTE4 production in the lung tissues were noted. These findings suggest that higher levels of TGF-ß1 in AERD patients may contribute to LTE4 production via enhancing LTC4S expression which induces eosinophil degranulation, accelerating airway inflammation.

Oleoylethanolamide induces eosinophilic airway inflammation in bronchial asthma.

Asthma is a chronic eosinophilic inflammatory disease with an increasing prevalence worldwide. Endocannabinoids are known to have immunomodulatory biological effects. However, the contribution of oleoylethanolamide (OEA) to airway inflammation remains to be elucidated. To investigate the effect of OEA, the expression of proinflammatory cytokines was measured by RT-qPCR and ELISA in airway epithelial (A549) cells. The numbers of airway inflammatory cells and cytokine levels in bronchoalveolar lavage fluid, airway hyperresponsiveness, and type 2 innate lymphoid cells (ILC2s) were examined in BALB/c mice after 4 days of OEA treatment. Furthermore, eosinophil activation after OEA treatment was evaluated by measuring cellular CD69 levels in eosinophils from human peripheral eosinophils using flow cytometry. OEA induced type 2 inflammatory responses in vitro and in vivo. OEA increased the levels of proinflammatory cytokines, such as IL-6, IL-8, and IL-33, in A549 cells. In addition, it also induced eosinophilic inflammation, the production of IL-4, IL-5, IL-13, and IL-33 in bronchoalveolar lavage fluid, and airway hyperresponsiveness. OEA increased the numbers of IL-5- or IL-13-producing ILC2s in a mouse model. Finally, we confirmed that OEA increased CD69 expression (an eosinophil activation marker) on purified eosinophils from patients with asthma compared to those from healthy controls. OEA may play a role in the pathogenesis of asthma by activating ILC2s and eosinophils.