Acidic Calcium-Independent Phospholipase A2 Regulates Eosinophil-Mediated Pathology during Filarial Manifestation of Tropical Pulmonary Eosinophilia.

Eosinophils mediate pathological manifestations during tropical pulmonary eosinophilia (TPE), a potentially fatal complication of lymphatic filariasis, by mechanisms that are incompletely understood. Using two-dimensional gel electrophoresis, mass spectrometry, flow cytometry, and pharmacological and functional studies, we identified acidic calcium-independent phospholipase A2 (aiPLA2) as the master regulator of TPE pathogenesis. FACS-sorted lung eosinophils from TPE mice exhibited aiPLA2-dependent activation characterized by heavy calcium influx, F-actin polymerization, increased degranulation, and heightened reactive oxygen species generation. Interestingly, aiPLA2 also promoted alternative activation in lung macrophages and regulated the release of inflammatory intermediates from them. Treatment of TPE mice with MJ33, a nontoxic pharmacological inhibitor of aiPLA2, lowered eosinophil counts in the bronchoalveolar lavage fluid, reduced eosinophil peroxidase and ß-hexosaminidase activity, increased airway width, improved lung endothelial barrier, and lowered the production of inflammatory lipid intermediates, which significantly improved the pathological condition of the lungs. Importantly, ex vivo reconstitution of arachidonic acid to eosinophils from MJ33-treated TPE mice increased eosinophil degranulation and inflammatory lipid intermediates underlining the pivotal role of aiPLA2 in arachidonic acid metabolism. Mechanistically, phosphorylation of JNK-1 regulated phospholipase activity of aiPLA2, whereas IgG cross-linking mediated pathological activation of eosinophils. Taken together, ours is the first study, to our knowledge, to report hitherto undocumented role of aiPLA2 in regulating TPE pathogenesis.

Acute Eosinophilic Pneumonia Masquerading as a Lung Abscess.

BACKGROUND: Acute Eosinophilic Pneumonia (AEP) is a rare form of non-infectious pneumonia that is easily missed and misdiagnosed because of its atypical clinical symptoms and misleading laboratory and imaging studies. METHODS: By reporting a case of an initial diagnosis of lung abscess, which was treated with antibiotics and then CT suggesting that the lesion continued to worsen, it was eventually confirmed to be AEP by lung biopsy, A joint literature analysis was conducted to improve clinicians' understanding of the diagnosis and treatment of AEP. RESULTS: Initially, because of the atypical ancillary findings, we thought the disease was a lung abscess, which was eventually confirmed by pathology as AEP. CONCLUSIONS: The presence of AEP needs to be considered when various laboratory findings point to infectious dis-ease, but anti-infection is not effective. Diagnosis can be confirmed by bronchoalveolar lavage and lung tissue biopsy. Prompt treatment can provide rapid relief and reduce the risk of patient death.

Label-free imaging and evaluation of characteristic properties of asthma-derived eosinophils using optical diffraction tomography.

Optical diffraction tomography (ODT), an emerging imaging technique that does not require fluorescent staining, can measure the three-dimensional distribution of the refractive index (RI) of organelles. In this study, we used ODT to characterize the pathological characteristics of human eosinophils derived from asthma patients presenting with eosinophilia. In addition to morphological information about organelles appearing in eosinophils, including the cytoplasm, nucleus, and vacuole, we succeeded in imaging specific granules and quantifying the RI values of the granules. Interestingly, ODT analysis showed that the RI (i.e., molecular density) of granules was significantly different between eosinophils from asthma patients and healthy individuals without eosinophilia, and that vacuoles were frequently found in the cells of asthma patients. Our results suggest that the physicochemical properties of eosinophils derived from patients with asthma can be quantitatively distinguished from those of healthy individuals. The method will provide insight into efficient evaluation of the characteristics of eosinophils at the organelle level for various diseases with eosinophilia.

[Clinical analysis of chronic eosinophilic pneumonia in 9 cases].

Objective: To investigate the clinical features, treatment and prognosis of chronic eosinophilic pneumonia. Methods: Nine patients with chronic eosinophilic pneumonia diagnosed in Shandong Provincial Qianfoshan Hospital from January 2014 to December 2020 were enrolled and followed up. The data of clinically proven chronic eosinophilic pneumonia were reviewed. Results: The 9 cases included one male and eight females, aged from 16 to 71 years (median 47 years). Among them, 5 cases were complicated with asthma, 1 case was complicated with allergic rhinitis, and 1 case had an allergic history of pollen. All the patients had cough, expectoration, chest tightness and wheezing, and a few had fatigue (3/9), fever (1/9) and chest pain (1/9). Single or multiple patchy high-density shadows (9/9), mediastinal lymphadenopathy (7/9), air bronchogram (2/9), and reticular shadow (1/9) were observed in chest CT. Peripheral eosinophils (EOS) and serum total IgE increased to varying degrees in the 9 patients. Meanwhile, the bronchoscopy of 5 cases showed elevated percentage of eosinophils in alveolar lavage fluid, and the lung biopsy of remaining 4 cases showed EOS infiltration in lung alveolar and interstitium. After receiving glucocorticoid therapy for 0.5 to 1 month, the clinical symptoms of all 9 patients had been improved and lung lesions on CT scans had been obviously absorbed. Four cases relapsed during follow-up. Conclusions: For patients especially women who have a history of allergy, elevated blood eosinophils and serum total IgE with pulmonary high-density shadow or consolidation, chronic eosinophilic pneumonia should be considered, and bronchoscopy or percutaneous lung biopsy is indicated for a definite diagnosis. Glucocorticoid therapy is effective, but the rate of recurrence is high.

Lung natural helper cells are a critical source of Th2 cell-type cytokines in protease allergen-induced airway inflammation.

Overproduction of cytokines by T helper 2 (Th2) cells in the lung is thought to be a cause of asthma. Here we report that innate lymphocytes termed lung natural helper (LNH) cells are a T cell-independent source of Th2 cell-type cytokines in protease allergen-treated lungs. LNH (Lin(-)Sca-1(+)c-kit(+/lo)CD25(+)CD127(+)) cells, when stimulated by IL-33 plus IL-2, IL-7, or thymic stroma lymphopoietin (TSLP), produced large amounts of IL-5 and IL-13. Intranasal administration of protease allergen papain induced eosinophil infiltration and mucus hyperproduction in the lung of wild-type and Rag1(-/-) mice, but not in Rag2(-/-)Il2rg(-/-) mice that lack LNH cells. LNH cell depletion inhibited papain-induced airway inflammation in Rag1(-/-) mice whereas adoptive transfer of LNH cells enabled Rag2(-/-)Il2rg(-/-) mice to respond to papain. Treatment of lung explants with papain induced IL-33 and TSLP production by stroma cells and IL-5 and IL-13 production by LNH cells. Thus, LNH cells are critical for protease allergen-induced airway inflammation.

TSLP drives acute TH2-cell differentiation in lungs.

BACKGROUND: Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine that is important for the development of type 2 inflammatory responses at mucosal surfaces. OBJECTIVE: In humans, TSLP level has been found to be elevated in the lungs of patients with asthma, and in mouse models, TSLP can promote type 2 airway inflammation, primarily through the activation of dendritic cells. However, the mechanisms underlying its role remain unclear. The objective of this study was to provide a mechanistic analysis of TSLP-mediated type 2 airway inflammation METHODS: To dissect the mechanisms of TSLP-mediated type 2 responses, mice were treated with TSLP and antigen to evaluate cellular immune responses. Flow cytometric analyses were used to follow responses in the airways, and conditional deletion of TSLP receptor and adoptive transfer were used to identify the cellular subsets involved in this inflammatory response. RESULTS: We showed that TSLP can directly promote TH2-cell differentiation in the lung, independent of the draining lymph nodes. We also identified a population of patrolling monocytes/interstitial macrophages (IMs) (CD11c-expressing IMs) that are both necessary and sufficient for TSLP-mediated TH2-cell differentiation and airway inflammation. TH2-cell-driven airway eosinophilia is attenuated by ablation of CD11c-expressing IMs or by selective deficiency of TSLP receptor signaling in these cells. More importantly, CD11c-expressing IMs are sufficient for the induction of acute TH2-cell responses in the lungs that is independent of dendritic cells and T-cell priming in the draining lymph nodes. CONCLUSION: These findings indicate a novel mechanistic role for TSLP and CD11c-expressing IMs in the development of acute TH2-cell-dependent allergic airway inflammation. This work also demonstrates a new role for TSLP in promoting type 2 responses directly in the lung.

An endothelial microRNA-1-regulated network controls eosinophil trafficking in asthma and chronic rhinosinusitis.

BACKGROUND: Airway eosinophilia is a prominent feature of asthma and chronic rhinosinusitis (CRS), and the endothelium plays a key role in eosinophil trafficking. To date, microRNA-1 (miR-1) is the only microRNA known to be regulated in the lung endothelium in asthma models. OBJECTIVE: We sought to determine the role of endothelial miR-1 in allergic airway inflammation. METHODS: We measured microRNA and mRNA expression using quantitative RT-PCR. We used ovalbumin and house dust mite models of asthma. Endothelium-specific overexpression of miR-1 was achieved through lentiviral vector delivery or induction of a transgene. Tissue eosinophilia was quantified by using Congo red and anti-eosinophil peroxidase staining. We measured eosinophil binding with a Sykes-Moore adhesion chamber. Target recruitment to RNA-induced silencing complex was assessed by using anti-Argonaute2 RNA immunoprecipitation. Surface P-selectin levels were measured by using flow cytometry. RESULTS: Serum miR-1 levels had inverse correlations with sputum eosinophilia, airway obstruction, and number of hospitalizations in asthmatic patients and sinonasal tissue eosinophilia in patients with CRS. IL-13 stimulation decreased miR-1 levels in human lung endothelium. Endothelium-specific overexpression of miR-1 reduced airway eosinophilia and asthma phenotypes in murine models and inhibited IL-13-induced eosinophil binding to endothelial cells. miR-1 recruited P-selectin, thymic stromal lymphopoietin, eotaxin-3, and thrombopoietin receptor to the RNA-induced silencing complex; downregulated these genes in the lung endothelium; and reduced surface P-selectin levels in IL-13-stimulated endothelial cells. In our asthma and CRS cohorts, miR-1 levels correlated inversely with its target genes. CONCLUSION: Endothelial miR-1 regulates eosinophil trafficking in the setting of allergic airway inflammation. miR-1 has therapeutic potential in asthmatic patients and patients with CRS.

Lung eosinophils increase vagus nerve-mediated airway reflex bronchoconstriction in mice.

Eosinophils mediate airway hyperresponsiveness by increasing vagally mediated reflex bronchoconstriction. Here, we tested whether circulating or airway eosinophils change nerve function. Airway resistance in response to aerosolized 5-hydroxytryptamine (5-HT, 10-300 mM) was measured in wild-type mice or transgenic mice that overexpress IL5 in T cells (+IL5T), overexpress IL5 in airway epithelium (+IL5AE), or overexpress IL5 but are devoid of eosinophils (+IL5AE/-Eos). Inflammatory cells in bronchoalveolar lavage (BAL), blood, and bone marrow were quantified. Blood eosinophils were increased in +IL5T and +IL5AE mice compared with wild-type mice. +IL5T mice had increased eosinophils in bone marrow while +IL5AE mice had increased eosinophils in BAL. Eosinophils surrounding large airways were significantly increased only in +IL5AE mice. With intact vagal innervation, aerosolized 5-HT significantly increased airway resistance in +IL5AE mice. 5-HT-induced bronchoconstriction was blocked by vagotomy or atropine, demonstrating that it was mediated via a vagal reflex. Airway resistance was not increased in +IL5AE/-Eos mice, demonstrating that it required lung eosinophils, but was not affected by increased bone marrow or blood eosinophils or by increased IL5 in the absence of eosinophils. Eosinophils did not change M3 function on airway smooth muscle, since airway responses to methacholine in vagotomized mice were not different among strains. Eosinophils surrounding large airways were sufficient, even in the absence of increased IL5 or external insult, to increase vagally mediated reflex bronchoconstriction. Specifically blocking or reducing eosinophils surrounding large airways may effectively inhibit reflex hyperresponsiveness mediated by vagus nerves in eosinophilic asthma.

Benralizumab efficacy for patients with fixed airflow obstruction and severe, uncontrolled eosinophilic asthma.

BACKGROUND: Fixed airflow obstruction (FAO) is associated with severe eosinophilic asthma. Benralizumab is an interleukin-5 receptor alpha-directed cytolytic monoclonal antibody for patients with severe, uncontrolled eosinophilic asthma. OBJECTIVE: We evaluated FAO influence on benralizumab treatment response. METHODS: We performed a post hoc analysis of pooled phase III SIROCCO (NCT01928771) and CALIMA (NCT01914757) data for patients with severe, uncontrolled asthma with baseline blood eosinophil counts of 300 or more cells/µL who received benralizumab 30 mg every 8 weeks or placebo. Demographics, baseline clinical characteristics, and treatment responses were evaluated by FAO status. FAO+ and FAO- were defined as ratios of postbronchodilator forced expiratory volume in 1 second (FEV1) to forced vital capacity of less than 70% and 70% or more, respectively, at baseline. RESULTS: FAO+ prevalence was 63% (935/1493). With benralizumab, similar annual asthma exacerbation rate (AER) reductions vs placebo were achieved for FAO+ and FAO- patients (rate ratio [95% confidence interval (CI)] = 0.56 [0.44-0.71] and 0.58 [0.41-0.83], respectively), whereas annual AER reductions associated with emergency department visits or hospitalizations were greater for FAO+ vs FAO- patients (rate ratio [95% CI] = 0.55 [0.33-0.91] and 0.70 [0.33-1.48], respectively). Prebronchodilator FEV1 (95% CI) increase from baseline to end of treatment was greater for FAO+ vs FAO- patients receiving benralizumab compared with placebo (0.159 L [0.082-0.236] vs 0.103 L [-0.008 to 0.215]). Other lung function measures, patient-reported outcomes, and symptom improvements were also numerically greater for FAO+ vs FAO- patients. CONCLUSION: Benralizumab improved asthma control across several measures for patients with severe, uncontrolled eosinophilic asthma and FAO. TRIAL REGISTRATION: SIROCCO trial: NCT01928771 (URL: https://clinicaltrials.gov/ct2/show/NCT01928771) CALIMA trial: NCT01914757 (URL: https://clinicaltrials.gov/ct2/show/NCT01914757).

Real-Life Study of Mepolizumab in Idiopathic Chronic Eosinophilic Pneumonia.

INTRODUCTION: Idiopathic chronic eosinophilic pneumonia (ICEP) is an orphan lung disease characterized by concomitant systemic and local eosinophilia, along with bilateral lung infiltrates. Symptoms include dyspnea of subacute/chronic onset, cough, and general systemic signs. Although all patients do respond to oral corticosteroids, relapse rate is very high, which highlights the need for alternative therapies in case of relapsing ICEP. Mepolizumab is a fully humanized antibody directed against interleukin 5, a key growth factor of eosinophils. In the present study, we retrospectively studied the effect of off-label use of mepolizumab for relapsing ICEP. MATERIALS AND METHODS: All data from patients treated with mepolizumab for relapsing ICEP were included in our database and diagnoses were reviewed. We analyzed the effect of treatment on relapse rate, oral corticosteroids (OCS) use, and lung lesions on high-resolution computed tomography (HRCT). RESULTS: We included ten patients in the final analysis, with a median follow-up of 9 months after initiation of mepolizumab. Beside its expected effect on circulating eosinophils, treatment with mepolizumab was associated with a significant reduction of annual rate of exacerbations and a reduced consumption of corticosteroids. We also observed a remission of lung lesions on follow-up HRCT. CONCLUSIONS: In this open-label retrospective study, treatment of ICEP with mepolizumab was associated with a reduction of relapses, OCS use, and the disappearance of lung infiltrates.

Advances in eosinophilic diseases in 2018.

Interest in eosinophil biology and eosinophilic diseases is increasing, as reflected in a doubling of the number of annual articles focused on this topic published in the Journal of Allergy and Clinical Immunology over the past decade. Although the majority of these publications relate to eosinophilic asthma, a growing proportion of them focus on breakthroughs in the diagnosis, treatment, and pathogenesis of other eosinophilic disorders, most notably eosinophilic esophagitis. This review highlights advances in our understanding of eosinophilia and eosinophilic disorders (excluding asthma) published in the Journal in 2018.

The Innate Immune Protein S100A9 Protects from T-Helper Cell Type 2-mediated Allergic Airway Inflammation.

Calprotectin is a heterodimer of the proteins S100A8 and S100A9, and it is an abundant innate immune protein associated with inflammation. In humans, calprotectin transcription and protein abundance are associated with asthma and disease severity. However, mechanistic studies in experimental asthma models have been inconclusive, identifying both protective and pathogenic effects of calprotectin. To clarify the role of calprotectin in asthma, calprotectin-deficient S100A9-/- and wild-type (WT) C57BL/6 mice were compared in a murine model of allergic airway inflammation. Mice were intranasally challenged with extracts of the clinically relevant allergen, Alternaria alternata (Alt Ext), or PBS every third day over 9 days. On Day 10, BAL fluid and lung tissue homogenates were harvested and allergic airway inflammation was assessed. Alt Ext challenge induced release of S100A8/S100A9 to the alveolar space and increased protein expression in the alveolar epithelium of WT mice. Compared with WT mice, S100A9-/- mice displayed significantly enhanced allergic airway inflammation, including production of IL-13, CCL11, CCL24, serum IgE, eosinophil recruitment, and airway resistance and elastance. In response to Alt Ext, S100A9-/- mice accumulated significantly more IL-13+IL-5+CD4+ T-helper type 2 cells. S100A9-/- mice also accumulated a significantly lower proportion of CD4+ T regulatory (Treg) cells in the lung that had significantly lower expression of CD25. Calprotectin enhanced WT Treg cell suppressive activity in vitro. Therefore, this study identifies a role for the innate immune protein, S100A9, in protection from CD4+ T-helper type 2 cell hyperinflammation in response to Alt Ext. This protection is mediated, at least in part, by CD4+ Treg cell function.

Epithelial SERPINB10, a novel marker of airway eosinophilia in asthma, contributes to allergic airway inflammation.

Serine peptidase inhibitor, clade B, member 10 (SERPINB10) expression is increased in IL-13-stimulated human bronchial epithelial cells and in a murine model of allergic airway inflammation. However, the role of SERPINB10 in asthma remains unknown. We examined the association between epithelial SERPINB10 expression and airway eosinophilia in subjects with asthma and the role of Serpinb10 in allergic airway inflammation in an animal model. Epithelial SERPINB10 mRNA and protein expression were markedly increased in subjects with asthma ( n = 60) compared with healthy controls ( n = 25). Epithelial SERPINB10 mRNA levels were significantly correlated with airway hyperresponsiveness (AHR) and three parameters reflecting airway eosinophilia including the percentage of sputum eosinophils, the number of eosinophils in bronchial submucosa, and fraction of exhaled nitric oxide in subjects with asthma. Moreover, epithelial SERPINB10 expression was strongly correlated with the epithelial gene signature ( CLCA1, POSTN, and SERPINB2) for type 2 status. In normal human bronchial epithelial cells cultured at air-liquid interface, knockdown of SERPINB10 suppressed IL-13-stimulated periostin (encoded by POSTN) and CCL26 (eotaxin-3) expression by inhibiting the activation of p38 MAPK. Epithelial CCL26 mRNA levels were correlated with SERPINB10 expression in subjects with asthma. Airway knockdown of Serpinb10 alleviated AHR, airway eosinophilia and the expression of periostin and Ccl26 in a murine model of allergic airway disease. Taken together, epithelial SERPINB10 is a novel marker for airway eosinophilia in asthma. Epithelial SERPINB10 contributes to allergic airway eosinophilic inflammation, at least in part, by regulating the expression of periostin and CCL26.

Critical role of CCL4 in eosinophil recruitment into the airway.

BACKGROUND: Excessive eosinophil airway infiltration is a clinically critical condition in some cases. Eosinophilic pneumonia (EP) is a pulmonary condition involving eosinophil infiltration of the lungs. Although several chemokines, including eotaxin-1 (CCL11), RANTES (CCL5) and macrophage inflammatory protein 1ß (MIP-1ß or CCL4), have been detected in bronchoalveolar lavage fluid (BALF) from patients with EP, the pathophysiological mechanisms underlying EP, including potential relationships between eosinophils and CCL4, have not been fully elucidated. OBJECTIVE: To examine the involvement of CCL4 in eosinophilic airway inflammation. METHODS: We analysed supernatants of activated eosinophils and BALF from 16 patients with eosinophilic pneumonia (EP). Further, we examined the effects of CCL4 on eosinophil functions in vitro and those of anti-CCL4 neutralizing antibody in an in vivo model. RESULTS: We found that purified human eosinophils stimulated with IL-5 predominantly secreted CCL4 and that patients with EP had elevated CCL11 and CCL4 levels in BALF compared with samples from individuals without EP. Because CCL4 levels were more strongly correlated with eosinophil count and expression of eosinophil granule proteins than CCL11, in vitro experiments using purified eosinophils concentrated on the former chemokine. Interestingly, CCL4 acted as a chemoattractant for eosinophils. In a mouse model, administration of a CCL4-neutralizing antibody attenuated eosinophilic airway infiltration and airway hyperresponsiveness. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, these findings highlight an important role of CCL4 in the mechanisms underlying eosinophil recruitment into the airway and may provide a novel insight into this potential therapeutic target.

IL-35 Suppresses Lipopolysaccharide-Induced Airway Eosinophilia in EBI3-Deficient Mice.

EBI3 functions as the subunit of immune-regulatory cytokines, such as IL-27 and IL-35, by pairing with p28 and p35, respectively. We treated wild-type and EBI3-deficient mice with intratracheal administration of LPS and obtained bronchoalveolar lavage fluid (BALF) 24 h later. Although neutrophils were the predominant cells in BALF from both groups of mice, eosinophils were highly enriched and there was increased production of eosinophil-attracting chemokines CCL11 and CCL24 in BALF of EBI3-deficient mice. The bronchial epithelial cells and alveolar macrophages were the major producers of CCL11 and CCL24. Because no such increases in eosinophils were seen in BALF of p28/IL-27-deficient mice or WSX-1/IL-27Rα subunit-deficient mice upon intratracheal stimulation with LPS, we considered that the lack of IL-35 was responsible for the enhanced airway eosinophilia in EBI3-deficient mice. In vitro, IL-35 potently suppressed production of CCL11 and CCL24 by human lung epithelial cell lines treated with TNF-α and IL-1ß. IL-35 also suppressed phosphorylation of STAT1 and STAT3 and induced suppressor of cytokine signaling 3. In vivo, rIL-35 dramatically reduced LPS-induced airway eosinophilia in EBI3-deficient mice, with concomitant reduction of CCL11 and CCL24, whereas neutralization of IL-35 significantly increased airway eosinophils in LPS-treated wild-type mice. Collectively, our results suggest that IL-35 negatively regulates airway eosinophilia, at least in part by reducing the production of CCL11 and CCL24.

Lung-Infiltrating Foxp3+ Regulatory T Cells Are Quantitatively and Qualitatively Different during Eosinophilic and Neutrophilic Allergic Airway Inflammation but Essential To Control the Inflammation.

Understanding functions of Foxp3+ regulatory T cells (Tregs) during allergic airway inflammation remains incomplete. In this study, we report that, during cockroach Ag-induced allergic airway inflammation, Foxp3+ Tregs are rapidly mobilized into the inflamed lung tissues. However, the level of Treg accumulation in the lung was different depending on the type of inflammation. During eosinophilic airway inflammation, ∼30% of lung-infiltrating CD4 T cells express Foxp3, indicative of Tregs. On the contrary, only ∼10% of infiltrating CD4 T cells express Foxp3 during neutrophilic airway inflammation. Despite the different accumulation, the lung inflammation and inflammatory T cell responses were aggravated following Treg depletion, regardless of the type of inflammation, suggesting regulatory roles for Tregs. Interestingly, however, the extent to which inflammatory responses are aggravated by Treg depletion was significantly greater during eosinophilic airway inflammation. Indeed, lung-infiltrating Tregs exhibit phenotypic and functional features associated with potent suppression. Our results demonstrate that Tregs are essential regulators of inflammation, regardless of the type of inflammation, although the mechanisms used by Tregs to control inflammation may be shaped by environmental cues available to them.

Pneumonia eosinofilic in pediatrics, clinical cases. / Neumonía eosinofílica en pediatría, a propósito de dos casos clínicos.

INTRODUCTION: Eosinophilic Pneumonia (EP) is a very rare disorder in Pediatrics. It is characterized by the infiltra tion of eosinophils in the pulmonary and alveolar interstitium, and may be primary or secondary as well as present an acute or chronic progress. OBJECTIVE: to present 2 pediatric EP clinical cases which were diagnosed at the pediatric intensive care unit of Clinica Indisa in Santiago, Chile between 2014 and 2017. CLINICAL CASES: Two older infants, who were hospitalized due to respiratory failure with a diagnosis of viral pneumonia. Both have asthmatic mothers. Additionally, they both had febrile syn drome, persistent condensation images in the chest x-rays, and peripheral eosinophilia throughout the course of the disease. One of the infants required oxygen for more than one month, and there was no eosinophilia in the bronchoalveolar lavage (BAL). In this case, the diagnosis of EP was reached via pulmonary biopsy. The other infant required mechanic ventilation for 28 days, and was diagnosed due to eosinophilia greater than 25% in the bronchoalveolar lavage. Both patients had excellent res ponse to systemic corticosteroids. CONCLUSION: After ruling out other causes, EP should be suspected in children with pneumonia diagnosis, and persistent symptoms that do not respond positively to treatment, especially if associated with peripheral eosinophilia. The diagnosis of EP in pediatrics is confirmed with eosinophilia greater than 20% in BAL and, in some cases, it is necessary to perform a lung biopsy.

Lung eosinophilia induced by house dust mites or ovalbumin is modulated by nicotinic receptor α7 and inhibited by cigarette smoke.

Eosinophilia (EOS) is an important component of airway inflammation and hyperresponsiveness in allergic reactions including those leading to asthma. Although cigarette smoking (CS) is a significant contributor to long-term adverse outcomes in these lung disorders, there are also the curious reports of its ability to produce acute suppression of inflammatory responses including EOS through poorly understood mechanisms. One possibility is that proinflammatory processes are suppressed by nicotine in CS acting through nicotinic receptor α7 (α7). Here we addressed the role of α7 in modulating EOS with two mouse models of an allergic response: house dust mites (HDM; Dermatophagoides sp.) and ovalbumin (OVA). The influence of α7 on EOS was experimentally resolved in wild-type mice or in mice in which a point mutation of the α7 receptor (α7E260A:G) selectively restricts normal signaling of cellular responses. RNA analysis of alveolar macrophages and the distal lung epithelium indicates that normal α7 function robustly impacts gene expression in the epithelium to HDM and OVA but to different degrees. Notable was allergen-specific α7 modulation of Ccl11 and Ccl24 (eotaxins) expression, which was enhanced in HDM but suppressed in OVA EOS. CS suppressed EOS induced by both OVA and HDM, as well as the inflammatory genes involved, regardless of α7 genotype. These results suggest that EOS in response to HDM or OVA is through signaling pathways that are modulated in a cell-specific manner by α7 and are distinct from CS suppression.

Longitudinal profiling of the lung microbiome in the AERIS study demonstrates repeatability of bacterial and eosinophilic COPD exacerbations.

BACKGROUND: Alterations in the composition of the lung microbiome associated with adverse clinical outcomes, known as dysbiosis, have been implicated with disease severity and exacerbations in COPD. OBJECTIVE: To characterise longitudinal changes in the lung microbiome in the AERIS study (Acute Exacerbation and Respiratory InfectionS in COPD) and their relationship with associated COPD outcomes. METHODS: We surveyed 584 sputum samples from 101 patients with COPD to analyse the lung microbiome at both stable and exacerbation time points over 1 year using high-throughput sequencing of the 16S ribosomal RNA gene. We incorporated additional lung microbiology, blood markers and in-depth clinical assessments to classify COPD phenotypes. RESULTS: The stability of the lung microbiome over time was more likely to be decreased in exacerbations and within individuals with higher exacerbation frequencies. Analysis of exacerbation phenotypes using a Markov chain model revealed that bacterial and eosinophilic exacerbations were more likely to be repeated in subsequent exacerbations within a subject, whereas viral exacerbations were not more likely to be repeated. We also confirmed the association of bacterial genera, including Haemophilus and Moraxella, with disease severity, exacerbation events and bronchiectasis. CONCLUSIONS: Subtypes of COPD have distinct bacterial compositions and stabilities over time. Some exacerbation subtypes have non-random probabilities of repeating those subtypes in the future. This study provides insights pertaining to the identification of bacterial targets in the lung and biomarkers to classify COPD subtypes and to determine appropriate treatments for the patient. TRIAL REGISTRATION NUMBER: Results, NCT01360398.

Subcutaneous Allergic Sensitization to Protease Allergen Is Dependent on Mast Cells but Not IL-33: Distinct Mechanisms between Subcutaneous and Intranasal Routes.

Protease activity of papain, a plant-derived occupational allergen homologous to mite major allergens, is essential to IgE/IgG1 production and lung eosinophilia induced by intranasal papain administration in mice, and IL-33 contributes to these responses. In this work, we investigate skin and Ab responses induced by s.c. papain administration into ear lobes and responses induced by subsequent airway challenge with papain. Subcutaneous papain injection induced swelling associated with increased epidermal thickness, dermal inflammation, serum IgE/IgG1 responses, and Th2 cytokine production in draining lymph node cells restimulated in vitro. These responses were markedly less upon s.c. administration of protease inhibitor-treated papain. Results obtained by using mast cell-deficient mice and reconstitution of tissue mast cells suggested the contribution of mast cells to papain-specific IgE/IgG1 responses and eosinophil infiltration. The responses were equivalent between wild-type and IL-33(-/-) mice. After the subsequent airway challenge, the s.c. presensitized wild-type mice showed more severe lung eosinophilia than those without the presensitization. The presensitized IL-33(-/-) mice showed modest lung eosinophilia, which was absent without the presensitization, but its severity and IgE boost by the airway challenge were markedly less than the presensitized wild-type mice, in which protease activity of inhaled papain contributed to the responses. The results suggest that mechanisms for the protease-dependent sensitization differ between skin and airway and that cooperation of mast cell-dependent, IL-33-independent initial sensitization via skin and protease-induced, IL-33-mediated mechanism in re-exposure via airway to protease allergens maximizes the magnitude of the transition from skin inflammation to asthma in natural history of progression of allergic diseases.