Preventive nasal administration of flagellin restores antimicrobial effect of gentamicin and protects against a multidrug-resistant strain of Pseudomonas aeruginosa.

The increasing prevalence of multidrug-resistant Pseudomonas aeruginosa (PA) is a significant concern for chronic respiratory disease exacerbations. Host-directed drugs, such as flagellin, an agonist of toll-like receptor 5 (TLR5), have emerged as a promising solution. In this study, we evaluated the prophylactic intranasal administration of flagellin against a multidrug-resistant strain of PA (PAMDR) in mice and assessed the possible synergy with the antibiotic gentamicin (GNT). The results indicated that flagellin treatment before infection decreased bacterial load in the lungs, likely due to an increase in neutrophil recruitment, and reduced signs of inflammation, including proinflammatory cytokines. The combination of flagellin and GNT showed a synergistic effect, decreasing even more the bacterial load and increasing mice survival rates, in comparison to mice pre-treated only with flagellin. These findings suggest that preventive nasal administration of flagellin could restore the effect of GNT against MDR strains of PA, paving the way for the use of flagellin in vulnerable patients with chronic respiratory diseases.

Poly-L-Lysine to Fight Antibiotic Resistances of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a major hospital-associated pathogen that can cause severe infections, most notably in patients with cystic fibrosis (CF) or those hospitalized in intensive care units. Given its remarkable ability to resist antibiotics, P. aeruginosa eradication has grown more challenging. Therefore, there is an urgent need to discover and develop new strategies that can counteract P. aeruginosa-resistant strains. Here, we evaluated the efficacy of poly-L-lysine (pLK) in combination with commonly used antibiotics as an alternative treatment option against P. aeruginosa. First, we demonstrated by scanning electron microscopy that pLK alters the integrity of the surface membrane of P. aeruginosa. We also showed using a fluorometry test that this results in an enhanced permeability of the bacteria membrane. Based on these data, we further evaluated the effect of the combinations of pLK with imipenem, ceftazidime, or aztreonam using the broth microdilution method in vitro. We found synergies in terms of bactericidal effects against either sensitive or resistant P. aeruginosa strains, with a reduction in bacterial growth (up to 5-log10 compared to the control). Similarly, these synergistic and bactericidal effects were confirmed ex vivo using a 3D model of human primary bronchial epithelial cells maintained in an air-liquid interface. In conclusion, pLK could be an innovative antipseudomonal molecule, opening its application as an adjuvant antibiotherapy against drug-resistant P. aeruginosa strains.

Host succinate inhibits influenza virus infection through succinylation and nuclear retention of the viral nucleoprotein.

Influenza virus infection causes considerable morbidity and mortality, but current therapies have limited efficacy. We hypothesized that investigating the metabolic signaling during infection may help to design innovative antiviral approaches. Using bronchoalveolar lavages of infected mice, we here demonstrate that influenza virus induces a major reprogramming of lung metabolism. We focused on mitochondria-derived succinate that accumulated both in the respiratory fluids of virus-challenged mice and of patients with influenza pneumonia. Notably, succinate displays a potent antiviral activity in vitro as it inhibits the multiplication of influenza A/H1N1 and A/H3N2 strains and strongly decreases virus-triggered metabolic perturbations and inflammatory responses. Moreover, mice receiving succinate intranasally showed reduced viral loads in lungs and increased survival compared to control animals. The antiviral mechanism involves a succinate-dependent posttranslational modification, that is, succinylation, of the viral nucleoprotein at the highly conserved K87 residue. Succinylation of viral nucleoprotein altered its electrostatic interactions with viral RNA and further impaired the trafficking of viral ribonucleoprotein complexes. The finding that succinate efficiently disrupts the influenza replication cycle opens up new avenues for improved treatment of influenza pneumonia.

Molecularly Imprinted Hydrogels Selective to Ribavirin as New Drug Delivery Systems to Improve Efficiency of Antiviral Nucleoside Analogue: A Proof-of-Concept Study with Influenza A Virus.

This study describes the synthesis and evaluation of different imprinted hydrogels using ribavirin as template molecule. Ribavirin serves as a model molecule because it possesses a broad-spectrum antiviral effect against RNA viruses, which are expected as emerging viruses. The choice of monomers enables to stabilize the pre-polymerization complex and to synthesize biocompatible polymers. Predictive studies as well as experimental works conclude similar results on best ribavirin:monomers ratios. Thus, materials exhibit high selective cavities toward ribavirin. These affinities allow to show release profiles drastically different from the non-imprinted ones at two temperatures. The imprinted materials show a sustained profile able to release antiviral for more than 24 h. The hydrogels obtained are biocompatible with model cells retained, human lung epithelial BEAS-2B cells. Cell viability is excellent and pro-inflammatory response is insignificant when imprinted polymers are incubated with cells. Finally, viral tests carried out on Influenza A infected lung cells show that imprinted delivery systems delivering 1 to 3 µg of antiviral have the same efficiency as a medium containing 30 µg mL-1 of active agent. As a very interesting result, the molecularly imprinted polymers as drug delivery systems allow to increase the local concentration of antiviral, to improve their delivery when its bioavailability is low.

Kallikrein-related peptidase 5 contributes to the remodeling and repair of bronchial epithelium.

Inflammation, oxidative stress, and protease/protease inhibitor imbalance with excessive production of proteases are factors associated with pathogenesis of the chronic obstructive pulmonary disease (COPD). In this study, we report that kallikrein-related peptidase 5 (KLK5) is a crucial protease involved in extracellular matrix (ECM) remodeling and bronchial epithelial repair after injury. First, we showed that KLK5 degrades the basal layer formed by culture of primary bronchial epithelial cells from COPD or non-COPD patients. Also, exogenous KLK5 acted differently on BEAS-2B cells already engaged in epithelial-to-mesenchymal transition (EMT) or on 16HBE 14o- cells harboring epithelial characteristics. Indeed, by inducing EMT, KLK5 reduced BEAS-2B cell adherence to the ECM. This effect, neutralized by tissue factor pathway inhibitor 2, a kunitz-type serine protease inhibitor, was due to a direct proteolytic activity of KLK5 on E-cadherin, ß-catenin, fibronectin, and α5ß1 integrin. Thus, KLK5 may strengthen EMT mechanisms and promote the migration of cells by activating the mitogen-activated protein kinase signaling pathway required for this function. In contrast, knockdown of endogenous KLK5 in 16HBE14o- cells, accelerated wound healing repair after injury, and exogenous KLK5 addition delayed the closure repair. These data suggest that among proteases, KLK5 could play a critical role in airway remodeling events associated with COPD during exposure of the pulmonary epithelium to inhaled irritants or smoking and the inflammation process.

A Bioluminescent 3CLPro Activity Assay to Monitor SARS-CoV-2 Replication and Identify Inhibitors.

Our therapeutic arsenal against viruses is very limited and the current pandemic of SARS-CoV-2 highlights the critical need for effective antivirals against emerging coronaviruses. Cellular assays allowing a precise quantification of viral replication in high-throughput experimental settings are essential to the screening of chemical libraries and the selection of best antiviral chemical structures. To develop a reporting system for SARS-CoV-2 infection, we generated cell lines expressing a firefly luciferase maintained in an inactive form by a consensus cleavage site for the viral protease 3CLPro of coronaviruses, so that the luminescent biosensor is turned on upon 3CLPro expression or SARS-CoV-2 infection. This cellular assay was used to screen a metabolism-oriented library of 492 compounds to identify metabolic vulnerabilities of coronaviruses for developing innovative therapeutic strategies. In agreement with recent reports, inhibitors of pyrimidine biosynthesis were found to prevent SARS-CoV-2 replication. Among the top hits, we also identified the NADPH oxidase (NOX) inhibitor Setanaxib. The anti-SARS-CoV-2 activity of Setanaxib was further confirmed using ACE2-expressing human pulmonary cells Beas2B as well as human primary nasal epithelial cells. Altogether, these results validate our cell-based functional assay and the interest of screening libraries of different origins to identify inhibitors of SARS-CoV-2 for drug repurposing or development.

Controlled Heat and Humidity-Based Treatment for the Reuse of Personal Protective Equipment: A Pragmatic Proof-of-Concept to Address the Mass Shortage of Surgical Masks and N95/FFP2 Respirators and to Prevent the SARS-CoV2 Transmission.

Background: The coronavirus infectious disease-2019 (COVID-19) pandemic has led to an unprecedented shortage of healthcare resources, primarily personal protective equipment like surgical masks, and N95/filtering face piece type 2 (FFP2) respirators. Objective: Reuse of surgical masks and N95/FFP2 respirators may circumvent the supply chain constraints and thus overcome mass shortage. Methods, design, setting, and measurement: Herein, we tested the effects of dry- and moist-air controlled heating treatment on structure and chemical integrity, decontamination yield, and filtration performance of surgical masks and FFP2 respirators. Results: We found that treatment in a climate chamber at 70°C during 1 h with 75% humidity rate was adequate for enabling substantial decontamination of both respiratory viruses, oropharyngeal bacteria, and model animal coronaviuses, while maintaining a satisfying filtering capacity. Limitations: Further studies are now required to confirm the feasibility of the whole process during routine practice. Conclusion: Our findings provide compelling evidence for the recycling of pre-used surgical masks and N95/FFP2 respirators in case of imminent mass shortfall.

Robust Control of a Brain-Persisting Parasite through MHC I Presentation by Infected Neurons.

Control of CNS pathogens by CD8 T cells is key to avoid fatal neuroinflammation. Yet, the modalities of MHC I presentation in the brain are poorly understood. Here, we analyze the antigen presentation mechanisms underlying CD8 T cell-mediated control of the Toxoplasma gondii parasite in the CNS. We show that MHC I presentation of an efficiently processed model antigen (GRA6-OVA), even when not expressed in the bradyzoite stage, reduces cyst burden and dampens encephalitis in C57BL/6 mice. Antigen presentation assays with infected primary neurons reveal a correlation between lower MHC I presentation of tachyzoite antigens by neurons and poor parasite control in vivo. Using conditional MHC I-deficient mice, we find that neuronal MHC I presentation is required for robust restriction of T. gondii in the CNS during chronic phase, showing the importance of MHC I presentation by CNS neurons in the control of a prevalent brain pathogen.

MHC I presentation of Toxoplasma gondii immunodominant antigen does not require Sec22b and is regulated by antigen orientation at the vacuole membrane.

The intracellular Toxoplasma gondii parasite replicates within a parasitophorous vacuole (PV). T. gondii secretes proteins that remain soluble in the PV space, are inserted into PV membranes or are exported beyond the PV boundary. In addition to supporting T. gondii growth, these proteins can be processed and presented by MHC I for CD8+ T-cell recognition. Yet it is unclear whether membrane binding influences the processing pathways employed and if topology of membrane antigens impacts their MHC I presentation. Here we report that the MHC I pathways of soluble and membrane-bound antigens differ in their requirement for host ER recruitment. In contrast to the soluble SAG1-OVA model antigen, we find that presentation of the membrane-bound GRA6 is independent from the SNARE Sec22b, a key molecule for transfer of host endoplasmic reticulum components onto the PV. Using parasites modified to secrete a transmembrane antigen with opposite orientations, we further show that MHC I presentation is highly favored when the C-terminal epitope is exposed to the host cell cytosol, which corresponds to GRA6 natural orientation. Our data suggest that the biochemical properties of antigens released by intracellular pathogens critically guide their processing pathway and are valuable parameters to consider for vaccination strategies.

Intravacuolar Membranes Regulate CD8 T Cell Recognition of Membrane-Bound Toxoplasma gondii Protective Antigen.

Apicomplexa parasites such as Toxoplasma gondii target effectors to and across the boundary of their parasitophorous vacuole (PV), resulting in host cell subversion and potential presentation by MHC class I molecules for CD8 T cell recognition. The host-parasite interface comprises the PV limiting membrane and a highly curved, membranous intravacuolar network (IVN) of uncertain function. Here, using a cell-free minimal system, we dissect how membrane tubules are shaped by the parasite effectors GRA2 and GRA6. We show that membrane association regulates access of the GRA6 protective antigen to the MHC I pathway in infected cells. Although insertion of GRA6 in the PV membrane is key for immunogenicity, association of GRA6 with the IVN limits presentation and curtails GRA6-specific CD8 responses in mice. Thus, membrane deformations of the PV regulate access of antigens to the MHC class I pathway, and the IVN may play a role in immune modulation.

Blockade of IL-1R signaling diminishes Paneth cell depletion and Toxoplasma gondii induced ileitis in mice.

Interleukin 1 is a critical inflammatory mediator and involved in host defense to several pathogens. Oral T. gondii infection causes lethal ileitis in C57BL/6 (BL6) mice and serves to investigate the mechanisms of acute intestinal inflammation. Here we show that IL-1 is expressed upon oral T. gondii (76K strain) infection in the small intestine and mediates ileitis as IL-1R1 deficient mice have reduced neutrophil recruitment in the lamina propria, parasite invasion, inflammatory lesions and enhanced survival as compared to BL6 infected control mice. Protection in the absence of IL-1R1 signaling was associated with reduced IFN-γ expression and preserved Paneth cells, while these cells were eliminated in infected BL6 mice. Furthermore, blockade of IL-1 by IL-1ß antibody attenuated inflammation in BL6 mice. In conclusion, IL-1 signaling contributes to the inflammatory response with increase IFN-γ expression and Paneth cell depletion upon oral T. gondii infection.

Location of the CD8 T cell epitope within the antigenic precursor determines immunogenicity and protection against the Toxoplasma gondii parasite.

CD8 T cells protect the host from disease caused by intracellular pathogens, such as the Toxoplasma gondii (T. gondii) protozoan parasite. Despite the complexity of the T. gondii proteome, CD8 T cell responses are restricted to only a small number of peptide epitopes derived from a limited set of antigenic precursors. This phenomenon is known as immunodominance and is key to effective vaccine design. However, the mechanisms that determine the immunogenicity and immunodominance hierarchy of parasite antigens are not well understood. Here, using genetically modified parasites, we show that parasite burden is controlled by the immunodominant GRA6-specific CD8 T cell response but not by responses to the subdominant GRA4- and ROP7-derived epitopes. Remarkably, optimal processing and immunodominance were determined by the location of the peptide epitope at the C-terminus of the GRA6 antigenic precursor. In contrast, immunodominance could not be explained by the peptide affinity for the MHC I molecule or the frequency of T cell precursors in the naive animals. Our results reveal the molecular requirements for optimal presentation of an intracellular parasite antigen and for eliciting protective CD8 T cells.

Relative contribution of IL-1α, IL-1ß and TNF to the host response to Mycobacterium tuberculosis and attenuated M. bovis BCG.

TNF and IL-1 are major mediators involved in severe inflammatory diseases against which therapeutic neutralizing antibodies are developed. However, both TNF and IL-1 receptor pathways are essential for the control of Mycobacterium tuberculosis infection, and it is critical to assess the respective role of IL-1α, IL-1ß, and TNF. Using gene-targeted mice we show that absence of both IL-1α and IL-1ß recapitulates the uncontrolled M. tuberculosis infection with increased bacterial burden, exacerbated lung inflammation, high IFNγ, reduced IL-23 p19 and rapid death seen in IL-1R1-deficient mice. However, presence of either IL-1α or IL-1ß in single-deficient mice is sufficient to control acute M. tuberculosis infection, with restrained bacterial burden and lung pathology, in conditions where TNF deficient mice succumbed within 4 weeks with overwhelming infection. Systemic infection by attenuated M. bovis BCG was controlled in the absence of functional IL-1 pathway, but not in the absence of TNF. Therefore, although both IL-1α and IL-1ß are required for a full host response to virulent M. tuberculosis, the presence of either IL-1α or IL-1ß allows some control of acute M. tuberculosis infection, and IL-1 pathway is dispensable for controlling M. bovis BCG acute infection. This is in sharp contrast with TNF, which is essential for host response to both attenuated and virulent mycobacteria and may have implications for anti-inflammatory therapy with IL-1ß neutralizing antibodies.

MyD88 signaling in B cells regulates the production of Th1-dependent antibodies to AAV.

The administration of recombinant adeno-associated viral vectors (rAAV) for gene transfer induces strong humoral responses through mechanisms that remain incompletely characterized. To investigate the links between innate and adaptive immune responses to the vector, rAAVs were injected intravenously into mice deficient in cell-intrinsic components of innate responses (Toll-like receptors (TLRs), type-1 interferon (IFN) or inflammasome signaling molecules) and AAV-specific antibodies were measured. Of all molecules tested, only MyD88 was critically needed to mount immunoglobulin G (IgG) responses since MyD88(-/-) mice failed to develop high levels of AAV-specific IgG2 and IgG3, regardless of capsid serotype injected. None of the TLRs tested was essential here, but TLR9 ensured a Th1-biased antibody responses. Indeed, capsid-specific Th1 cells were induced upon injection of rAAV1, as directly confirmed with an epitope-tagged capsid, and the priming and development of these Th1 cells required T cell-extrinsic MyD88. Cell transfer experiments showed that autonomous MyD88 signaling in B cells, but not T cells, was sufficient to produce Th1-dependent IgGs. Therefore, rAAV triggers innate responses, at least via B cells, controlling the development of capsid-specific Th1-driven antibodies. MyD88 emerges as a critical and pivotal regulator of both T- and B-cell adaptive immunity against AAV.

Limited role for lymphotoxin α in the host immune response to Mycobacterium tuberculosis.

The contribution of lymphotoxin (LT)α in the host immune response to virulent Mycobacterium tuberculosis and Mycobacterium bovis bacillus Calmette-Guérin infections was investigated. Despite their ability to induce Th1 cytokine, IFN-γ, and IL-12 pulmonary response, "conventional" LTα(-/-) mice succumb rapidly to virulent M. tuberculosis aerosol infection, with uncontrolled bacilli growth, defective granuloma formation, necrosis, and reduced pulmonary inducible NO synthase expression, similar to TNF(-/-) mice. Contributions from developmental lymphoid abnormalities in LTα(-/-) mice were excluded because hematopoietic reconstitution with conventional LTα(-/-) bone marrow conferred enhanced susceptibility to wild-type mice, comparable to conventional LTα(-/-) control mice. However, conventional LTα(-/-) mice produced reduced levels of TNF after M. bovis bacillus Calmette-Guérin infection, and their lack of control of mycobacterial infection could be due to a defective contribution of either LTα or TNF, or both, to the host immune response. To address this point, the response of "neo-free" LTα(-/-) mice with unperturbed intrinsic TNF expression to M. tuberculosis infection was investigated in a direct comparative study with conventional LTα(-/-) mice. Strikingly, although conventional LTα(-/-) mice were highly sensitive, similar to TNF(-/-) mice, neo-free LTα(-/-) mice controlled acute M. tuberculosis infection essentially as wild-type mice. Pulmonary bacterial burden and inflammation was, however, slightly increased in neo-free LTα(-/-) mice 4-5 mo postinfection, but importantly, they did not succumb to infection. Our findings revise the notion that LTα might have a critical role in host defense to acute mycobacterial infection, independent of TNF, but suggest a contribution of LTα in the control of chronic M. tuberculosis infection.

Interleukin 17 receptor signaling is deleterious during Toxoplasma gondii infection in susceptible BL6 mice.

Th17 cells are involved in host defense against several pathogens. Using interleukin (IL) 17RA-deficient mice, we demonstrated reduced ileitis with diminished neutrophil recruitment and inflammatory lesions in the ileum, in the regional lymph node, in the spleen, and in the liver at day 7 and prolonged survival after Toxoplasma gondii infection. In addition, IL-17A antibody neutralization reduced inflammation and enhanced survival in BL6 mice. Diminished inflammation is associated with augmented interferon (IFN) gamma serum levels and enhanced production of IL-10 and IFN-gamma in cultured splenocytes upon antigen restimulation. Finally, cyst load and inflammation in the brain at 40 days are greater in surviving BL6 mice than in IL-17RA-deficient mice. In conclusion, oral T. gondii infection increases IL-17 expression and contributes to the inflammatory response, and IL-17 neutralization has a partial protective effect against fatal T. gondii-associated inflammation.

Partial redundancy of the pattern recognition receptors, scavenger receptors, and C-type lectins for the long-term control of Mycobacterium tuberculosis infection.

Mycobacterium tuberculosis is recognized by multiple pattern recognition receptors involved in innate immune defense, but their direct role in tuberculosis pathogenesis remains unknown. Beyond TLRs, scavenger receptors (SRs) and C-type lectins may play a crucial role in the sensing and signaling of pathogen motifs, as well as contribute to M. tuberculosis immune evasion. In this study, we addressed the relative role and potential redundancy of these receptors in the host response and resistance to M. tuberculosis infection using mice deficient for representative SR, C-type lectin receptor, or seven transmembrane receptor families. We show that a single deficiency in the class A SR, macrophage receptor with collagenous structure, CD36, mannose receptor, specific ICAM-3 grabbing nonintegrin-related, or F4/80 did not impair the host resistance to acute or chronic M. tuberculosis infection in terms of survival, control of bacterial clearance, lung inflammation, granuloma formation, and cytokine and chemokine expression. Double deficiency for the SRs class A SR types I and II plus CD36 or for the C-type lectins mannose receptor plus specific ICAM-3 grabbing nonintegrin-related had a limited effect on macrophage uptake of mycobacteria and TNF response and on the long-term control of M. tuberculosis infection. By contrast, mice deficient in the TNF, IL-1, or IFN-gamma pathway were unable to control acute M. tuberculosis infection. In conclusion, we document a functional redundancy in the pattern recognition receptors, which might cooperate in a coordinated response to sustain the full immune control of M. tuberculosis infection, in sharp contrast with the nonredundant, essential role of the TNF, IL-1, or IFN-gamma pathway for host resistance to M. tuberculosis.

TLR9-dependent induction of intestinal alpha-defensins by Toxoplasma gondii.

Alpha-defensins (or Cryptdins [Crps]) are a group of antimicrobial peptides produced as a component of Paneth cell (PC) secretory granules in the small intestine. In vivo ligation of TLR9 by synthetic agonists leads to PC degranulation, although the mechanism by which this occurs remains uncertain. In this report, we investigated TLR9-dependent mechanisms, triggered by the parasite Toxoplasma gondii, inducing Crp release in the lumen. Oral challenge of C57BL/6J (B6) wild-type (WT) mice with T. gondii induced TLR9 mRNA upregulation associated with a marked increase of type I IFN mRNA expression. PC secretory granules were released, and Crp-3/-5 mRNA expression by purified epithelial cells was increased following oral challenge of B6 WT mice. Although PCs failed to degranulate in infected B6 TLR9-/- mice, i.p. injection of mouse IFN-beta alone led to Crp-3/-5 mRNA upregulation in B6 WT and TLR9-/- mice. In addition, modulation of Crp mRNA expression in response to T. gondii infection was abrogated in B6 IFNAR-/- mice, which lack a functional type I IFN receptor. Taken together, these data demonstrate that T. gondii induces Crp-3/-5 production and release by PCs via a TLR9-dependent production of type I IFNs. Crps have a limited direct effect against T. gondii but may indirectly affect the early control of T. gondii invasiveness by promoting the initiation of a protective Th1 response against the parasite.

TNF in host resistance to tuberculosis infection.

TNF is essential to control Mycobacterium tuberculosis infection and cannot be replaced by other proinflammatory cytokines. Overproduction of TNF may cause immunopathology, while defective TNF production results in uncontrolled infection. The critical role of TNF in the control of tuberculosis has been illustrated recently by primary and reactivation of latent infection in some patients under pharmacological anti-TNF therapy for rheumatoid arthritis or Crohn's disease. In this review, we discuss results of recent studies aimed at better understanding of molecular, cellular and kinetic aspects of TNF-mediated regulation of host-mycobacteria interactions. In particular, recent data using either mutant mice expressing solely membrane TNF or specific inhibitor sparing membrane TNF demonstrated that membrane TNF is sufficient to control acute M. tuberculosis infection. This is opening the way to selective TNF neutralization that might retain the desired anti-inflammatory effect but reduce the infectious risk.

IL-1R1/MyD88 signaling is critical for elastase-induced lung inflammation and emphysema.

Lung emphysema and fibrosis are severe complications of chronic obstructive pulmonary disease, and uncontrolled protease activation may be involved in the pathogenesis. Using experimental elastase-induced acute inflammation, we demonstrate here that inflammation and development of emphysema is IL-1R1 and Toll/IL-1R signal transduction adaptor MyD88 dependent; however, TLR recognition is dispensable in this model. Elastase induces IL-1beta, TNF-alpha, keratinocyte-derived chemokine, and IL-6 secretion and neutrophil recruitment in the lung, which is drastically reduced in the absence of IL-1R1 or MyD88. Further, tissue destruction with emphysema and fibrosis is attenuated in the lungs of IL-1R1- and MyD88-deficient mice. Specific blockade of IL-1 by IL-1R antagonist diminishes acute inflammation and emphysema. Finally, IL-1beta production and inflammation are reduced in mice deficient for the NALP3 inflammasome component apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and we identified uric acid, which is produced upon elastase-induced lung injury, as an activator of the NALP3/ASC inflammasome. In conclusion, elastase-mediated lung pathology depends on inflammasome activation with IL-1beta production. IL-1beta therefore represents a critical mediator and a possible therapeutic target of lung inflammation leading to emphysema.