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The natural occurrence of asbestos and asbestos-like minerals (NOA) poses a risk to the environment and human health, notably when natural processes and anthropic activities promote fibre dispersion. Hundreds of potentially hazardous elongate mineral particles (EMPs, NIOSH 2011 definition) exist, and their toxicological profile is often unknown. We aim here to define a general approach, from field analysis to nano-structural investigation, to assess whether a fibrous mineral occurring in a specific site could pose a risk to human health. To evaluate the hazard associated with NOA, a multi-scale and multi-analytical integrated approach was adopted. Specifically, the geological factors that control the occurrence and distribution of NOA on site, and the mechanisms of formation and liberation of airborne fibres were investigated. In parallel, we explored the key bulk and surface properties of several natural mineral fibres and defined crystallographic, chemical, and morphological aspects that should be considered during hazard assessment. Also, the effect of standardized mechanical stress was used to quantitatively evaluate the potency of NOA-bearing exposed rock to generate inhalable fibres. This property was connected with the mineral characteristic, the rock fabric, and the rock erosion rate. Isolated fibre specimens were used to assess solubility in simulated body fluids, surface reactivity, and toxicological endpoints in vitro and in vivo. Taken together, these findings allowed us to build a multidimensional description of the hazard parameters of mineral fibre and paved the way for a science-based risk assessment in an unexplored NOA site.

The current paradigm for explaining lung granulomatous diseases induced by inhaled particles is mainly based on macrophages. This mechanism is now challenging because B lymphocytes also infiltrate injured tissue, and the deficiency in B lymphocytes is associated with limited lung granulomas in silica-treated mice. Here, we investigated how B lymphocytes respond to micro- and nanoparticles by combining in vivo and in vitro mouse models. We first demonstrated that innate-like B-1 lymphocytes (not conventional B-2 lymphocytes or plasma cells) specifically accumulated during granuloma formation in mice instilled with crystalline silica (DQ12, 2.5 mg/mouse) and carbon nanotubes (CNT Mitsui, 0.2 mg/mouse). In comparison to macrophages, peritoneal B-1 lymphocytes purified from naïve mice were resistant to the pyroptotic activity of reactive particles (up to 1 mg/mL) but clustered to establish in vitro cell/particle aggregates. Mouse B-1 lymphocytes (not B-2 lymphocytes) in coculture with macrophages and CNT (0.1 µg/mL) organized three-dimensional spheroid structures in Matrigel and stimulated the release of TIMP-1. Furthermore, purified B-1 lymphocytes are sensitive to nanosilica toxicity through radical generation in culture. Nanosilica-exposed B-1 lymphocytes released proinflammatory cytokines and alarmins. In conclusion, our data indicate that in addition to macrophages, B-1 lymphocytes participate in micrometric particle-induced granuloma formation and display inflammatory functions in response to nanoparticles.

Although epidemiological studies have suggested an association between asbestos exposure and systemic autoimmunity, the underlying mechanisms are poorly understood. Short asbestos fibers are often considered less harmful than long fibers but such a statement is still a matter of debates. This study aimed to compare the effects of short (SFA) and long (LFA) amosite fiber exposure on lung damage, autoimmunity and macrophage phenotype. Four months after lung exposure to 0.1 mg of fibers, BAL levels of lactate dehydrogenase, free DNA, CCL2, TIMP-1 and immunoglobulins A of LFA-exposed C57Bl/6 mice were increased when compared to fluids from control- and SFA-exposed mice. Effects in LFA-exposed mice were associated with lung fibrosis and autoimmunity including anti-double-strand DNA antibody production. Human monocyte-derived macrophages (MDMs) exposed to SFA or LFA at 20 µg/cm2 have a pro-inflammatory phenotype characterized by a significant increase of TNFα and IL-6 secretion. A decrease of efferocytosis capacities was also noted after SFA and LFA, whereas macrophage abilities to phagocyte fluorescent beads were unchanged when compared to control MDMs. SFA exposure induced IL-6 secretion and reduced the percentage of MDMs expressing MHCII and CD86 markers involved in antigen and T-lymphocyte stimulation. By contrast, NLRP3 inflammasome activation, evaluated through quantification of caspase-1 activity and IL-1β secretion is rather associated to LFA than SFA exposure. Our results demonstrated that only long-term exposure to LFA has induced significant lung damages and autoimmune effects supporting a worsened health effects of LFA in comparison to SFA.

IL-1α is an intracellular danger signal (DAMP) released by macrophages contributing to the development of silica-induced lung inflammation. The exact molecular mechanism orchestrating IL-1α extracellular release from particle-exposed macrophages is still unclear. To delineate this process, murine J774 and bone-marrow derived macrophages were exposed to increasing concentrations (1–40 cm2/ml) of a set of amorphous and crystalline silica particles with different surface chemical features. In particular, these characteristics include the content of nearly free silanols (NFS), a silanol population responsible for silica cytotoxicity recently identified. We first observed de novo stocks of IL-1α in macrophages after silica internalization regardless of particle physico-chemical characteristics and cell stress. IL-1α intracellular production and accumulation were observed by exposing macrophages to biologically-inert or cytotoxic crystalline and amorphous silicas. In contrast, only NFS-rich reactive silica particles triggered IL-1α release into the extracellular milieu from necrotic macrophages. We demonstrate that IL-1α is actively secreted through the formation of gasdermin D (GSDMD) pores in the plasma membrane and not passively released after macrophage plasma membrane lysis. Our findings indicate that the GSDMD pore-dependent secretion of IL-1α stock from macrophages solely depends on cytotoxicity induced by NFS-rich silica. This new regulated process represents a key first event in the mechanism of silica toxicity, suitable to refine the existing adverse outcome pathway (AOP) for predicting the inflammatory activity of silicas.

Pulmonary hypertension (PH) is a chronic disorder of the pulmonary circulation that often associates with other respiratory diseases (i.e., group III PH), leading to worsened symptoms and prognosis, notably when combined with interstitial lung diseases such as pulmonary fibrosis (PF). PH may lead to right ventricular (RV) failure, which accounts for a substantial part of the mortality in chronic lung disease patients. The disappointing results of pulmonary arterial hypertension (PAH)-related therapies in patients with PF emphasize the need to better understand the pathophysiologic mechanisms that drive PH development and progression in this specific setting. In this work, we validated an animal model of group III PH associated with PF (PH-PF), by using bleomycin (BM) intratracheal instillation and characterizing the nature of induced lung and vascular remodeling, including the influence on RV structure and function. To our knowledge, this is the first work describing this dose of BM in Sprague Dawley rats and the effects upon the heart and lungs, using different techniques such as echocardiography, heart catheterization, and histology. Our data shows the successful implementation of a rat model that mimics combined PF-PH, with most features seen in the equivalent human disease, such as lung and arterial remodeling, increased mPAP and RV dysfunction. ispartof: PULMONARY CIRCULATION vol:13 issue:1 ispartof: location:United States status: published

Papillary thyroid carcinoma (PTC) is the most frequent histological subtype of thyroid cancers (TC), and BRAFV600E genetic alteration is found in 60% of this endocrine cancer. This oncogene is associated with poor prognosis, resistance to radioiodine therapy, and tumor progression. Histological follow-up by anatomo-pathologists revealed that two-thirds of surgically-removed thyroids do not present malignant lesions. Thus, continued fundamental research into the molecular mechanisms of TC downstream of BRAFV600E remains central to better understanding the clinical behavior of these tumors. To study PTC, we used a mouse model in which expression of BRAFV600E was specifically switched on in thyrocytes by doxycycline administration. Upon daily intraperitoneal doxycycline injection, thyroid tissue rapidly acquired histological features mimicking human PTC. Transcriptomic analysis revealed major changes in immune signaling pathways upon BRAFV600E induction. Multiplex immunofluorescence confirmed the abundant recruitment of macrophages, among which a population of LYVE-1+/CD206+/STABILIN-1+ was dramatically increased. By genetically inactivating the gene coding for the scavenger receptor STABILIN-1, we showed an increase of CD8+ T cells in this in situ BRAFV600E-dependent TC. Lastly, we demonstrated the presence of CD206+/STABILIN-1+ macrophages in human thyroid pathologies. Altogether, we revealed the recruitment of immunosuppressive STABILIN-1 macrophages in a PTC mouse model and the interest to further study this macrophage subpopulation in human thyroid tissues.

Papillary thyroid carcinoma (PTC) is the most frequent histological subtype of thyroid cancers (TC), and BRAF

Exposure to asbestos is known for inducing inflammation, pulmonary fibrosis, lung cancer and malignant mesothelioma. Although several novel biomarkers and treatments are being tested, these chronic disorders are currently incurable, and the prognosis is particularly poor. The development of asbestos-induced cancer results from mutations, cell transformation and proliferation caused by reactive oxygen species and elevated levels of pro-inflammatory cytokines. Fiber-induced chronic inflammation also explains asbestosis, an interstitial lung disease characterized by uncontrolled matrix protein deposition leading to detrimental lung fibrosis. The investigation of the in-vivo molecular mechanisms driving asbestos pathogenicity is still a matter of debate. In this context, it is accepted that the physico-chemical properties of the fibers play a crucial role in causing adverse effects, and long fibers are still considered more toxic than short ones. Indeed, when fibers reach the alveolar space and migrate to the pleural/peritoneal cavity, long and thin fibers shows stronger inflammogenic, fibrogenic and tumorigenic effects than short fibers, in the long term. It is largely hold that short asbestos fibers are more easily cleared from the lungs and elicit a lower reactional and/or inflammatory effect. To further investigate this paradigm of toxicity, we compared the pro-inflammatory and pro-fibrogenic potential of short and long amosite fibers in in-vitro (J774 murine macrophages) and in-vivo (C57BL/6 mice) models. Surprisingly, our results demonstrated that short fibers were more prone to induce in-vitro cytotoxicity, accompanied by the release of pro-inflammatory biomarkers, in comparison to long fibers. On the contrary, the long fibers were significantly more inflammogenic and fibrogenic in the lungs of treated mice, while the short fibers were almost inert and did not induce acute and chronic inflammation and fibrosis. Furthermore, we observed that, while the long fibers were still present in the lungs of the animals 4 months after the exposure, the short amosite was substantially absent. These findings imply that the pulmonary deposition and a defect of clearance of the fibers play a crucial role in the development of in-vivo detrimental effects associated to long asbestos. This effect overcomes the mere in-vitro cytotoxic and inflammogenic potential of short fibers. Present results provide new insights into the mechanisms that drive asbestos toxicity, opening new perspectives for the development of reliable in vitro tests that fully predict health adverse effects associated to inorganic mineral fibers.

Pulmonary fibrosis (PF) and pulmonary hypertension (PH) are chronic diseases of the pulmonary parenchyma and circulation, respectively, which may coexist, but underlying mechanisms remain elusive. Mutations in the GCN2 gene (EIF2AK4) were recently associated with pulmonary veno-occlusive disease. This study aims to explore the involvement of the GCN2/eIF2α pathway in the development of PH during PF, in both human disease and in an experimental animal model. Lung tissue from PF patients with or without PH were collected at the time of lung transplantation, and controls were obtained from tumor resection surgery. Experimental lung disease was induced in either male wild-type or EIF2AK4-mutated Sprague-Dawley rats, randomly receiving a single intratracheal instillation of bleomycin or saline. Hemodynamic studies, as well as organ collection were performed 3 weeks post-instillation. Only significant results (p

Cystic fibrosis is associated with chronic Pseudomonas aeruginosa colonization and inflammation. The role of MyD88, the shared adapter protein of the proinflammatory TLR and IL-1R families, in chronic P. aeruginosa biofilm lung infection is unknown. We report that chronic lung infection with the clinical P. aeruginosa RP73 strain is associated with uncontrolled lung infection in complete MyD88-deficient mice with epithelial damage, inflammation, and rapid death. Then, we investigated whether alveolar or myeloid cells contribute to heightened sensitivity to infection. Using cell-specific, MyD88-deficient mice, we uncover that the MyD88 pathway in myeloid or alveolar epithelial cells is dispensable, suggesting that other cell types may control the high sensitivity of MyD88-deficient mice. By contrast, IL-1R1–deficient mice control chronic P. aeruginosa RP73 infection and IL-1β Ab blockade did not reduce host resistance. Therefore, the IL-1R1/MyD88 pathway is not involved, but other IL-1R or TLR family members need to be investigated. Our data strongly suggest that IL-1 targeted neutralizing therapies used to treat inflammatory diseases in patients unlikely reduce host resistance to chronic P. aeruginosa infection.

Background: GCN2, a major stress regulator, was recently implicated in pulmonary veno-occlusive disease (Eyries M, et al. Nat Genet 2014 and Perros F, et al. Circulation 2015). This study aims to explore the involvement of the GCN2/eIF2α signalling pathway in the development of pulmonary hypertension (PH) during idiopathic pulmonary fibrosis (IPF), in both human disease and in an experimental animal model. Methods: Lung tissue from IPF patients (n=19) with or w/o PH were collected at the time of lung transplantation, and controls (CTR, n=11) were obtained from tumour resection surgery. Experimental lung disease was induced in male SD rats, randomly receiving a single intratracheal instillation of bleomycin (BM, 7.5U/Kg) or saline (SL). Echocardiographic and haemodynamic studies, as well as organ collection were performed 3 weeks post-instillation. Only significant results (p Results: In total IPF lung tissue, GCN2 protein expression was decreased, when compared with CTR. GCN2 expression was reduced in CD31-positive endothelial cells, regardless the presence of PH. Rats treated with BM showed increased parenchymal fibrosis (hydroxyproline levels) and vascular remodelling (media wall thickness) as well as increased mean pulmonary artery pressure and impaired right ventricular function. In line with human data, GCN2 protein expression was decreased in the lung of BM rats when compared with SL. Conclusion: Our data show that GCN2 is dysregulated in both human IPF and in an animal model of combined IPF+PH. The possibility of a causative implication of GCN2 dysregulation in IPF and/or PH development will be further studied.

Monocytes infiltrating scar tissue are predominantly viewed as progenitor cells. Here, we show that tissue CCR2+ monocytes have specific immunosuppressive and profibrotic functions. CCR2+ monocytic cells are acutely recruited to the lung before the onset of silica-induced fibrosis in mice. These tissue monocytes are defined as monocytic myeloid-derived suppressor cells (M-MDSCs) because they significantly suppress T-lymphocyte proliferation in vitro. M-MDSCs collected from silica-treated mice also express transforming growth factor (TGF)-β1, which stimulates lung fibroblasts to release tissue inhibitor of metalloproteinase (TIMP)-1, an inhibitor of metalloproteinase collagenolytic activity. By using LysMCreCCR2loxP/loxP mice, we show that limiting CCR2+ M-MDSC accumulation reduces the pulmonary contents of TGF-β1, TIMP-1 and collagen after silica treatment. M-MDSCs do not differentiate into lung macrophages, granulocytes or fibrocytes during pulmonary fibrogenesis. Collectively, our data indicate that M-MDSCs contribute to lung fibrosis by specifically promoting a non-degrading collagen microenvironment. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Background In workers exposed mostly to laboratory animals (LA), symptoms may be due to irritants or allergens. Correct aetiological diagnosis is important for health surveillance. Objectives This study aims to test whether work-related (WR) allergen-induced symptoms are associated with a cytokine profile distinct from that due to irritants. Methods In a cross-sectional study (n=114), WR respiratory and/or skin symptoms were assessed through a standardised clinical examination and sensitisation to rat and/or mouse allergen determined by serum immunoglobulin E. Serum cytokine concentrations were measured by multiplex assays. The predefined cytokine profiles ‘sensitiser’ (interleukin (IL)-4, IL-5, IL-13, eotaxin-1) and ‘irritation’ (IL-8, IL-17A, IL-17F, IL-22) were considered positive, when ≥3 concentrations exceeded the 95th percentile of the asymptomatic non-sensitised group. Results were examined by hierarchical clustering analyses (HCA) and multiple linear regression. Explorative analyses were carried out for nine additional cytokines. Exposure to allergens and endotoxin was assessed in a subpopulation. Results The prevalence of the profile ‘irritation’ was comparable in 28 symptomatic non-sensitised workers and 71 asymptomatic non-sensitised workers. HCA showed that nearly all symptomatic non-sensitised workers were gathered in two subclusters, characterised by high IL-17A levels, but different IL-8 levels. Multiple linear regression identified drug consumption and current complaints as confounders. Sensitised subjects were too few (n=14) for testing the profile ‘sensitiser’. Conclusions In this unselected population of LA workers, the profile ‘irritation’ did not prove to be a valuable health surveillance tool. Low power precluded assessment of the profile ‘sensitiser’. The increased IL-17A concentration may originate from irritative constituents of organic dust.

Brains of Alzheimer’s disease patients are characterized by the presence of amyloid plaques and neurofbrillary tangles, both invariably associated with neuroinfammation. A crucial role for NLRP3–ASC infammasome [NACHT, LRR and PYD domains-containing protein 3 (NLRP3)–Apoptosis-associated speck-like protein containing a CARD (ASC)] in amyloid-beta (Aβ)-induced microgliosis and Aβ pathology has been unequivocally identifed. Aβ aggregates activate NLRP3–ASC infammasome (Halle et al. in Nat Immunol 9:857–865, 2008) and conversely NLRP3–ASC infammasome activation exacerbates amyloid pathology in vivo (Heneka et al. in Nature 493:674–678, 2013), including by prion-like ASC-speck cross-seeding (Venegas et al. in Nature 552:355–361, 2017). However, the link between infammasome activation, as crucial sensor of innate immunity, and Tau remains unexplored. Here, we analyzed whether Tau aggregates acting as prion-like Tau seeds can activate NLRP3–ASC infammasome. We demonstrate that Tau seeds activate NLRP3–ASC-dependent infammasome in primary microglia, following microglial uptake and lysosomal sorting of Tau seeds. Next, we analyzed the role of infammasome activation in prion-like or templated seeding of Tau pathology and found signifcant inhibition of exogenously seeded Tau pathology by ASC defciency in Tau transgenic mice. We furthermore demonstrate that chronic intracerebral administration of the NLRP3 inhibitor, MCC950, inhibits exogenously seeded Tau pathology. Finally, ASC defciency also decreased nonexogenously seeded Tau pathology in Tau transgenic mice. Overall our fndings demonstrate that Tau-seeding competent, aggregated Tau activates the ASC infammasome through the NLRP3–ASC axis, and we demonstrate an exacerbating role of the NLRP3–ASC axis on exogenously and non-exogenously seeded Tau pathology in Tau mice in vivo. The NLRP3–ASC infammasome, which is an important sensor of innate immunity and intensively explored for its role in health and disease, hence presents as an interesting therapeutic approach to target three crucial pathogenetic processes in AD, including prionlike seeding of Tau pathology, Aβ pathology and neuroinfammation. This work was supported by the Belgian Fonds National pour la Recherche Scientifque–Fonds de la Recherche Scientifque (FNRS-FRS; Qualifed Researcher—IDW), VLAIO (Vlaams Agentschap Innoveren en Ondernemen), FWO (Fonds Wetenschappelijk Onderzoek—Vlaanderen—G0C6819N) and FRA-SAO (Fondation Recherche Alzheimer—Stichting Alzheimer Onderzoek, Belgium).

Background: Idiopathic pulmonary fibrosis (IPF) is characterized by a progressive and irreversible respiratory failure. Non-invasive markers of disease activity are essential for prognosis and evaluation of early response to anti-fibrotic treatments. Objectives: The aims of this study were to determine whether fluorodeoxyglucose ([18F]-FDG) lung uptake is reduced after initiation of pirfenidone or nintedanib and to assess its possible use as a prognostic factor. Methods: [18F]-FDG PET/CT was performed in IPF patients and in a murine model of pulmonary fibrosis. PET/CTs were performed at day 8 and day 15 post-instillation of bleomycin in pirfenidone- or vehicule-treated mice. In IPF patients, PET-CT was performed before and 3 months after the initiation of pirfenidone or nintedanib. Results: In bleomycin-treated mice, pirfenidone significantly reduced the [18F]-FDG uptake compared to vehicule-treated mice at day 15 (p < 0.001), whereas no difference was observed at day 8 after bleomycin administration. In IPF patients, [18F]-FDG lung uptake before and after 3 months of treatment by nintedanib (n = 11) or pirfenidone (n = 14) showed no significant difference regardless the antifibrotic treatment. Moreover, no difference was noticed between patients with progressive or non-progressive disease at one year of follow up. Conclusions: Pirfenidone significantly reduces the lung [18F]-FDG uptake during the fibrotic phase in a mouse model of IPF. However, these preclinical data were not confirmed in IPF patients 3 months after the initiation of antifibrotic therapy. [18F]-FDG seems therefore not useful in clinical practice to assess the early response of IPF patients to nintedanib or pirfenidone., SCOPUS: ar.j, info:eu-repo/semantics/published

The purpose of this study was to assess whether cationic nanoliposomes could address tumor vaccines to dendritic cells in the lungs in vivo. Nanoliposomes were prepared using a cationic lipid, dimethylaminoethanecarbamoyl-cholesterol (DC-cholesterol) or dioleoyltrimethylammoniumpropane (DOTAP), and dipalmitoylphosphatidylcholine (DPPC), the most abundant phospholipid in lung surfactant. The liposomes presented a size below 175 nm and they effectively entrapped tumor antigens, an oligodeoxynucletotide containing CpG motifs (CpG) and the fluorescent dye calcein used as a tracer. Although the liposomes could permanently entrap a large fraction of the actives, they could not sustain their release in vitro. Liposomes made of DOTAP were safe to respiratory cells in vitro, while liposomes composed of DC-cholesterol were cytotoxic. DOTAP nanoliposomes were mainly taken up by alveolar macrophages following delivery to the lungs in mice. Few dendritic cells took up the liposomes, and interstitial macrophages did not take up liposomal calcein more than they took up soluble calcein. Stimulation of the innate immune system using liposomal CpG strongly enhanced uptake of calcein liposomes by all phagocytes in the lungs. Although a small percentage of dendritic cells took up the nanoliposomes, alveolar macrophages represented a major barrier to dendritic cell access in the lungs.

Experimental lung fibrogenic injury was induced in male Sprague-Dawley rats, randomly receiving a single intratracheal instillation of bleomycin sulphate (B, 7.5U/Kg) or saline (S). Echocardiographic and haemodynamic studies, as well as bronchoalveolar lavage fluid (BALF), blood and organ collection were performed 3 weeks after B instillation. Biochemical and histological studies confirmed the development of fibrosis in B-treated lungs, as shown by the increase in hydroxyproline content, as well as an increase in Sirius red stained areas both in proximal and distal lung tissue. Interestingly, in addition to parenchymal fibrosis, echocardiographic and haemodynamic studies revealed that B group developed mild PH, as shown by increased right ventricular end-systolic pressure (RVESP), mean pulmonary artery pressure (mPAP) and total pulmonary vascular resistance (TPVR). There were also indices of compromised right ventricular function, with decreased cardiac output (CO) and tricuspid annular plane systolic excursion (TAPSE). Moreover, rats submitted to B presented RV hypertrophy as shown by the Fulton Index. In addition and confirming PH development in these animals, vascular remodelling was observed in the B group, as shown by the increase in the arterial wall area. Our data shows the successful implementation of a rodent model that mimics combined lung (parenchymal) fibrosis and PH, with most of the features seen in human, such as lung and arterial remodelling, increased mPAP and compromised RV function, allowing future research to be focused on pathological mechanisms and possible new therapeutic targets.

Introduction: Epithelial dysfunction, including bronchiolization and type 2 alveolar cells (AEC2) hyperplasia, is a hallmark of idiopathic pulmonary fibrosis (IPF). A recent study linked IgA level to IPF prognosis. Therefore, we investigated the involvement of the polymeric immunoglobulin receptor (pIgR), the IgA transporter across epithelium, in IPF. Methods: Surgical lung samples from IPF patients and control subjects were immunostained for pIgR and pro-SPC (AEC2). In vivo experiments were performed in a recent model of chronic fibrosis that closely recapitulates IPF: 12 weeks-old C57/B6 pIgR-/- mice, as compared to littermate controls (WT), were treated with 6 successive instillations of 0.015 IU of bleomycin (BLM) or control NaCl every 12 days (d1-60). Broncho-alveolar lavage was harvested for cell counting and lung sections were stained by HE, Sirius Red and Masson’s trichrome at day 95. Lung fibrosis was quantitatively assessed by the modified Ashcroft score and OH-proline assay (µg/lobe). Results: Immunostaining of human IPF lungs revealed an ectopic expression of pIgR in IPF but not in control lungs, within AEC2 clusters. These findings were confirmed in lungs from BLM-treated mice. In addition, pIgR-/- mice displayed significantly less fibrosis as compared to control mice (96.27±30.55 vs 133.70±19.46, mean ± SD OH-proline µg/lobe, p=0.01), which correlated with histologic findings. There was no significant difference regarding inflammatory cell counts in BAL. Discussion Our preliminary data indicate an involvement of the pIgR axis in lung fibrosis, supporting the role of aberrant pIgR expression in IPF pathogenesis. Next steps will include studies of a cohort of IPF patients and of the underlying mechanisms

Major progress has been achieved in recent years to elucidate mechanisms driving the early response of pulmonary innate immune cells to inhaled micrometric and nanometric particles. Mononuclear phagocytes promptly categorize particles, alert immune network and engage crescendo responses for particle clearance and homeostasis restoration. Negatively charged particles directly interact with scavenger receptors A and B (SR-A and SR-B) and consequently activate specific signaling pathways, resulting in the production of TNF and IL-1 family members, which coordinate effective innate immune responses. Cytokine secretion also arises after a simple contact between particle-associated radicals and cell membranes. Reactive particles engage the passive release of constitutive alarmins, ensuing particle- or TNF-α-induced cell death and membranolysis. Finally, the inflammasome machinery represents the decisive intracellular platform that finely tune immune pathways engaged after SR activation, alarmin release, TNF-α production and cell homeostasis perturbations. Disturbance of these collective recognition processes prolongs particle persistence and innate immune responses that generate long-lasting adaptive immunity and cause chronic lung diseases.

Occupational exposure to indium tin oxide (ITO) particles has been associated with the development of severe lung diseases, including pulmonary alveolar proteinosis (PAP). The mechanisms of this lung toxicity remain unknown. Here, we reveal the respective roles of resident alveolar (Siglec-Fhigh AM) and recruited interstitial (Siglec-Flow IM) macrophages contributing in concert to the development of PAP. In mice treated with ITO particles, PAP is specifically associated with IL-1α (not GM-CSF) deficiency and Siglec-Fhigh AM (not Siglec-Flow IM) depletion. Mechanistically, ITO particles are preferentially phagocytosed and dissolved to soluble In3+ by Siglec-Flow IM. In contrast, Siglec-Fhigh AM weakly phagocytose or dissolve ITO particles, but are sensitive to released In3+ through the expression of the transferrin receptor-1 (TfR1). Blocking pulmonary Siglec-Flow IM recruitment in CCR2-deficient mice reduces ITO particle dissolution, In3+ release, Siglec-Fhigh AM depletion, and PAP formation. Restoration of IL-1-related Siglec-Fhigh AM also prevented ITO-induced PAP. We identified a new mechanism of secondary PAP development according to which metal ions released from inhaled particles by phagocytic IM disturb IL-1α-dependent AM self-maintenance and, in turn, alveolar clearance.

Exposure to conidia of Aspergillus fumigatus was described as a causative factor of a number of the respiratory system diseases, including asthma, chronic eosinophilic pneumonia, hypersensitivity pneumonitis and bronchopulmonary aspergillosis. The study investigates the effects of the repeated exposure to A. fumigatus in mice pulmonary compartment. Our work tackles two, so far insufficiently addressed, important aspects of interaction between affected organism and A. fumigatus: 1) recurrent character of exposure (characteristic for pathomechanism of the abovementioned disease states) and 2) impact of aging, potentially important for the differentiation response to an antigen.

Macrophages play a central role in immune and tissue responses of granulomatous lung diseases induced by pathogens and foreign bodies. Circulating monocytes are generally viewed as central precursors of these tissue effector macrophages. Here, we provide evidence that granulomas derive from alveolar macrophages serving as a local reservoir for the expansion of activated phagocytic macrophages. By exploring lung granulomatous responses to silica particles in IL-1-deficient mice, we found that the absence of IL-1α, but not IL-1β, was associated with reduced CD11b(high) phagocytic macrophage accumulation and fewer granulomas. This defect was associated with impaired alveolar clearance and resulted in the development of pulmonary alveolar proteinosis (PAP). Reconstitution of IL-1α(-/-) mice with recombinant IL-1α restored lung clearance functions and the pulmonary accumulation of CD11b(high) phagocytic macrophages. Mechanistically, IL-1α induced the proliferation of CD11b(low) alveolar macrophages and differentiated these cells into CD11b(high) macrophages which perform critical phagocytic functions and organize granuloma. We newly discovered here that IL-1α triggers lung responses requiring macrophage proliferation and maturation from tissue-resident macrophages. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

In laboratory animal work, allergens are classically considered to play a prominent role in generation of respiratory and skin symptoms. However, recent development may have changed working conditions and require an updating of preventive measures. In workers exposed to a range of animals besides laboratory mice and rats the relative role of endotoxin, irritants, and allergens in symptom generation was assessed for updating preventative measures and health surveillance. Eligible workers were recruited from university units in which exposure to rats and/or mice, occurrence of respiratory and/or skin symptoms, and/or a history of animal bites had been reported. Exposure to endotoxin and rat and mouse allergen was assessed (71 half-day personal samples). 'Symptomatic' was defined by work-related ocular, nasal, respiratory, or skin symptoms. A concentration of specific IgE against rat or mouse (e87 and e88) ≥0.35 kU/l defined sensitization. Sensitivity analyses examined the effect of alternative exposure indicators and definitions of 'sensitized' and 'symptomatic'. From 302 eligible workers, 177 participated. There were 121 and 41 workers in the asymptomatic and non-sensitized and symptomatic but non-sensitized group, respectively. Eight subjects were symptomatic and sensitized. Six sensitized subjects were asymptomatic. One participant could not be assigned to a subgroup. Airborne endotoxin and allergen concentrations were mostly below 20 EU m-3 or the detection limit, respectively. Clinical history showed that irritants and sensitizers other than mouse/rat allergen or endotoxin were a major cause of symptoms. Results were sensitive to the selected exposure indicator and the definition of 'symptomatic'. Health surveillance programs need to be adapted to include a larger range of allergens and pay more attention to irritants.

Background The added value of fractional exhaled nitric oxide (Feno) remains controversial in the investigation of occupational asthma (OA). Objective We sought to assess whether or not the increase of Feno levels following positive specific inhalation challenge (SIC) was restricted to phenotypes of subjects sharing common clinical characteristics by using a statistical cluster analysis. Methods Subjects were investigated for possible OA in a tertiary center using SICs from 2006 to 2012. Feno levels and sputum eosinophil counts were assessed at baseline and 24 hours after SIC. We performed a 2-step cluster analysis of the subgroup of subjects with OA. A multivariate logistic regression was performed in order to identify the variables associated with an increase in Feno in subjects with OA. Results One hundred and seventy-eight subjects underwent SIC; 98 had a positive test. The cluster analysis performed in the OA subgroup identified 3 clusters. Despite a positive SIC, there was no increase in the Feno levels after exposure to occupational agents in Cluster 3, in which subjects were only exposed to low-molecular-weight (LMW) agents. The molecular weight of the agent (high molecular weight vs LMW) was the only factor associated with an increase in Feno (OR: 4.2 [1.1-16.8]) in subjects with a positive SIC. Conclusion An increase in Feno after exposure to agents causing OA seems to occur more consistently in subjects with OA caused by high molecular weight than in those with OA due to LMW.

Rapid changes in cell volume characterize macrophage activation, but the role of water channels in inflammation remains unclear. We show here that, in vitro, aquaporin (AQP) blockade or deficiency results in reduced IL-1β release by macrophages activated with a variety of NLRP3 activators. Inhibition of AQP specifically during the regulatory volume decrease process is sufficient to limit IL-1β release by macrophages through the NLRP3 inflammasome axis. The immune-related activity of AQP was confirmed in vivo in a model of acute lung inflammation induced by crystals. AQP1 deficiency is associated with a marked reduction of both lung IL-1β release and neutrophilic inflammation. We conclude that AQP-mediated water transport in macrophages constitutes a general danger signal required for NLRP3-related inflammation. Our findings reveal a new function of AQP in the inflammatory process and suggest a novel therapeutic target for anti-inflammatory therapy.

Acute lung injury (ALI) can be accompanied by secondary systemic manifestations. In a model of ALI induced by bleomycin (bleo), we examined the response of D prostanoid receptor 1 (DP1)-deficient mice (DP1(-/-)) to better understand these processes. DP1 deficiency aggravated the toxicity of bleo as indicated by enhanced body weight loss, mortality, and lung inflammation including bronchoalveolar permeability and neutrophilia. Thymic atrophy was also observed after bleo and was strongly exacerbated in DP1(-/-) mice. This resulted from the enhanced depletion of immature T lymphocytes in the thymus of DP1(-/-) mice, a phenomenon usually related to increased glucocorticoid release in blood. Serum corticosterone was more elevated in DP1(-/-) mice after bleo than in wild-type (wt) mice. Thymocytes of DP1(-/-) mice were not more sensitive to dexamethasone in vitro, and systemic delivery of dexamethasone or peritoneal inflammation after LPS induced a similar thymic atrophy in wt and DP1(-/-) mice, indicating that pulmonary DP1 was critical to the control of thymic atrophy after bleo. DP1(-/-) mice showed increased lung and/or blood mediators involved in neutrophil recruitment and/or glucocorticoid production/thymic atrophy (osteopontin, leukemia inhibitory factor, and keratinocyte-derived chemokine) after bleo. Finally, local pulmonary DP1 activation or inhibition in wt mice abrogated or amplified thymic atrophy after bleo, respectively. Altogether, our data reveal that ALI can perturb the systemic T-cell pool by inducing thymic atrophy and that both pathological processes are controlled by the pulmonary DP1 receptor. This new pathway represents a potential therapeutic target in ALI.

Bacterial peritonitis remains the main cause of technique failure in peritoneal dialysis (PD). During peritonitis, the peritoneal membrane undergoes structural and functional alterations that are mediated by IL-1β. The NLRP3 inflammasome is a caspase-1–activating multiprotein complex that links sensing of microbial and stress products to activation of proinflammatory cytokines, including IL-1β. The potential roles of the NLRP3 inflammasome and IL-1β in the peritoneal membrane during acute peritonitis have not been investigated. Here, we show that the NLRP3 inflammasome is activated during acute bacterial peritonitis in patients on PD, and this activation associates with the release of IL-1β in the dialysate. In mice, lipopolysaccharide- or Escherichia coli-induced peritonitis led to IL-1β release in the peritoneal membrane. The genetic deletion of Nalp3, which encodes NLRP3, abrogated defects in solute transport during acute peritonitis and restored ultrafiltration. In human umbilical vein endothelial cells, IL-1β treatment directly enhanced endothelial cell proliferation and increased microvascular permeability. These in vitro effects require endothelial IL-1 receptors, shown by immunofluorescence to be expressed in peritoneal capillaries in mice. Furthermore, administration of the IL-1β receptor antagonist, anakinra, efficiently decreased nitric oxide production and vascular proliferation and restored peritoneal function in mouse models of peritonitis, even in mice treated with standard-of-care antibiotherapy. These data demonstrate that NLRP3 activation and IL-1β release have a critical role in solute transport defects and tissue remodeling during PD-related peritonitis. Blockade of the NLRP3/IL-1β axis offers a novel method for rescuing morphologic alterations and transport defects during acute peritonitis.

Hypersensitivity pneumonitis (HP) represents the immunologically mediated lung disease induced by repeated inhalations of a wide variety of certain finely dispersed organic antigens. In susceptible subjects, these inhalations provoke a hypersensitivity reaction characterized by intense inflammation of the terminal bronchioles, the interstitium and the alveolar tree. The inflammation often organizes into granulomas and may progress to pulmonary fibrosis. Our previous work indicated that cell extract of gram-negative bacteria Pantoea agglomerans (SE-PA) causes, in young C57BL/6J mice, pulmonary changes that are very similar to the clinical manifestations of HP in men. The purpose of presented studies was to describe the response of mice immune system while exposed to SE-PA. Particular attention was paid to examine the age influence on SE-PA induced inflammation and fibrosis in lung tissue. We used 3- and 18-month-old C57BL/6J mice. Lung samples were collected from untreated mice and animals exposed to harmful agent for 7 and 28 days. HP development was monitored by histological and biochemical evaluation. Using ELISA tests, we examined concentration of pro- and anti-inflammatory cytokines in lung homogenates. Our study demonstrated again that SE-PA provokes in mice changes typical for the clinical picture of HP, and that successive stages of disease (acute, subacute and chronic) might be obtained by modulation of time exposure. Furthermore, we found that animals' age at the time of sensitization influences the nature of observed changes (cytokine expression pattern) and the final outcome (reaction intensity and scale of fibrosis).