Asthma is a prevalent disease of chronic inflammation in which endogenous counter-regulatory signaling pathways are dysregulated. Recent evidence suggests that innate lymphoid cells (ILCs), including natural killer (NK) cells and type 2 innate lymphoid cells (ILC2), can participate in the regulation of allergic airways responses, in particular airway mucosal inflammation. Here, we have identified both NK cells and ILC2 in human lung and peripheral blood in healthy and asthmatic subjects. NK cells were highly activated in severe asthma, linked to eosinophilia and interacted with autologous eosinophils to promote their apoptosis. ILC2 generated antigen-independent IL-13 in response to the mast cell product prostaglandin D2 (PGD2) alone and in a synergistic manner with the airway epithelial cytokines IL-25 and IL-33. Both NK cells and ILC2 expressed the pro-resolving ALX/FPR2 receptors. Lipoxin A4, a natural pro-resolving ligand for ALX/FPR2 receptors, significantly increased NK cell mediated eosinophil apoptosis and decreased IL-13 release by ILC2. Together, these findings indicate that ILCs are targets for lipoxin A4 to decrease airway inflammation and mediate the catabasis of eosinophilic inflammation. Because lipoxin A4 generation is decreased in severe asthma, these findings also implicate unrestrained ILC activation in asthma pathobiology.

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Severe asthma is typically characterized by chronic airway inflammation that is refractory to corticosteroids and associated with excess morbidity. Patients were recruited into the National Heart, Lung, and Blood Institute–sponsored Severe Asthma Research Program and comprehensively phenotyped by bronchoscopy. Bronchoalveolar lavage (BAL) cells were analyzed by flow cytometry. Compared with healthy individuals (n = 21), patients with asthma (n = 53) had fewer BAL natural killer (NK) cells. Patients with severe asthma (n = 29) had a marked increase in the ratios of CD4+ T cells to NK cells and neutrophils to NK cells. BAL NK cells in severe asthma were skewed toward the cytotoxic CD56dim subset, with significantly increased BAL fluid levels of the cytotoxic mediator granzyme A. The numbers of BAL CD56dim NK cells and CCR6−CCR4− T helper 1–enriched CD4+ T cells correlated inversely with lung function [forced expiratory volume in 1 s (FEV1) % predicted] in asthma. Relative to cells from healthy controls, peripheral blood NK cells from asthmatic patients had impaired killing of K562 myeloid target cells despite releasing more cytotoxic mediators. Ex vivo exposure to dexamethasone markedly decreased blood NK cell lysis of target cells and cytotoxic mediator release. NK cells expressed airway lipoxin A4/formyl peptide receptor 2 receptors, and in contrast to dexamethasone, lipoxin A4–exposed NK cells had preserved functional responses. Together, our findings indicate that the immunology of the severe asthma airway is characterized by decreased NK cell cytotoxicity with increased numbers of target leukocytes, which is exacerbated by corticosteroids that further disable NK cell function. These failed resolution mechanisms likely contribute to persistent airway inflammation in severe asthma.

Formerly considered as a passive process, the resolution of acute inflammation is now recognized as an active host response, with a cascade of coordinated cellular and molecular events that promotes termination of the inflammatory response and initiates tissue repair and healing. In a state of immune fitness, the resolution of inflammation is contained in time and space enabling the restoration of tissue homeostasis. There is increasing evidence that poor and/or inappropriate resolution of inflammation participates in the pathogenesis of chronic inflammatory diseases, extending in time the actions of pro-inflammatory mechanisms, and responsible in the long run for excessive tissue damage and pathology. In this review, we will focus on how resolution can be the target for therapy in “Th1/Th17 cell-driven” immune diseases and “Th2 cell-driven” immune diseases, with inflammatory bowel diseases (IBD) and asthma, as relevant examples. We describe the main cells and mediators stimulating the resolution of inflammation and discuss how pharmacological and dietary interventions but also life style factors, physical and psychological conditions, might influence the resolution phase. A better understanding of the impact of endogenous and exogenous factors on the resolution of inflammation might open a whole area in the development of personalized therapies in non-resolving chronic inflammatory diseases.

Work-related asthma (WRA) is a relevant problem in several countries, is cause of disability and socioeconomic consequences for both the patient and the society and is probably still underdiagnosed. A correct diagnosis is extremely important to reduce or limit the consequences of the disease. This consensus document was prepared by a EAACI Task Force consisting of an expert panel of allergologists, pneumologists and occupational physicians from different European countries. This document is not intended to address in detail the full diagnostic work-up of WRA, nor to be a formal evidence-based guideline. It is written to provide an operative protocol to allergologists and physicians dealing with asthma useful for identifying the subjects suspected of having WRA to address them to in-depth investigations in a specialized centre. No evidence-based system could be used because of the low grade of evidence of published studies in this area, and instead, 'key messages' or 'suggestions' are provided based on consensus of the expert panel members.

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Introduction Survivors of viral ARDS are at risk of long-term physical, functional and neuropsychological complications resulting from the lung injury itself, but also from potential multiorgan dysfunction, and the long stay in the intensive care unit (ICU). Recovery profiles after severe SARS-CoV-2 pneumonia in intensive care unit survivors have yet to be clearly defined. Material and methods The goal of this single-center, prospective, observational study was to systematically evaluate pulmonary and extrapulmonary function at 12 months after a stay in the ICU, in a prospectively identified cohort of patients who survived SARS-CoV-2 pneumonia. Eligible patients were assessed at 3, 6 and 12 months after onset of SARS-CoV-2. Patients underwent physical examination, pulmonary function testing, chest computed tomography (CT) scan, a standardized six-minute walk test with continuous oximetry, overnight home respiratory polygraphy and have completed quality of life questionnaire. The primary endpoint was alteration of the alveolar–capillary barrier compared to reference values as measured by DLCO, at 12 months after onset of SARS-CoV-2 symptoms. Results In total, 85 patients (median age 68.4 years, (interquartile range [IQR] = 60.1–72.9 years), 78.8% male) participated in the trial. The median length of hospital stay was 44 days (IQR: 20–60) including 17 days in ICU (IQR: 11–26). Pulmonary function tests were completed at 3 months (n = 85), 6 months (n = 80), and 12 months (n = 73) after onset of symptoms. Most patients showed an improvement in DLCO at each timepoint (3, 6, and 12 months). All patients who normalized their DLCO did not subsequently deteriorate, except one. Chest CT scans were abnormal in 77 patients (96.3%) at 3 months and although the proportion was the same at 12 months, but patterns have changed. Conclusion We report the results of a comprehensive evaluation of 85 patients admitted to the ICU for SARS-CoV-2, at one-year follow-up after symptom onset. We show that most patients had an improvement in DLCO at each timepoint. Trial registration: Clinical trial registration number: NCT04519320.

Biomarkers of intravascular monocyte activation in at-risk patients were associated with development of ARDS. The potential clinical benefit of early aspirin for prevention of ARDS remains uncertain. Together, results of the biochemical and immunological analyses provide a window into the early pathogenesis of human ARDS and represent potential vascular biomarkers of ARDS risk. Clinical trial registered with www.clinicaltrials.gov (NCT01504867).