The effects of interleukin-1beta in tumor necrosis factor-alpha-induced acute pulmonary inflammation in mice

Acute respiratory distress syndrome enhances tumor metastasis into lungs: Role of BRD4 in the tumor microenvironment

Acute respiratory distress syndrome (ARDS) is associated with severe lung inflammation, edema, hypoxia, and high vascular permeability. The COVID-19-associated pandemic ARDS caused by SARS-CoV-2 has created dire global conditions and has been highly contagious. Chronic inflammatory disease enhances cancer cell proliferation, progression, and invasion. We investigated how acute lung inflammation activates the tumor microenvironment and enhances lung metastasis in LPS induced in vitro and in vivo models. Respiratory illness is mainly caused by cytokine storm, which further influences oxidative and nitrosative stress. The LPS-induced inflammatory cytokines made the conditions suitable for the tumor microenvironment in the lungs. In the present study, we observed that LPS induced the cytokine storm and promoted lung inflammation via BRD4, which further caused the nuclear translocation of p65 NF-κB and STAT3. The transcriptional activation additionally triggers the tumor microenvironment and lung metastasis. Thus, BRD4-regulated p65 and STAT3 transcriptional activity in ARDS enhances lung tumor metastasis. Moreover, LPS-induced ARDS might promote the tumor microenvironment and increase cancer metastasis into the lungs. Collectively, BRD4 plays a vital role in inflammation-mediated tumor metastasis and is found to be a diagnostic and molecular target in inflammation-associated cancers.

Critical Review on Toxicological Mechanisms Triggered by Inhalation of Alumina Nanoparticles on to the Lungs

Alumina nanoparticles (Al₂O₃ NPs) can be released in occupational environments in different contexts such as industry, defense, and aerospace. Workers can be exposed by inhalation to these NPs, for instance, through welding fumes or aerosolized propellant combustion residues. Several clinical and epidemiological studies have reported that inhalation of Al₂O₃ NPs could trigger aluminosis, inflammation in the lung parenchyma, respiratory symptoms such as cough or shortness of breath, and probably long-term pulmonary fibrosis. The present review is a critical update of the current knowledge on underlying toxicological, molecular, and cellular mechanisms induced by exposure to Al₂O₃ NPs in the lungs. A major part of animal studies also points out inflammatory cells and secreted biomarkers in broncho-alveolar lavage fluid (BALF) and blood serum, while in vitro studies on lung cells indicate contradictory results regarding the toxicity of these NPs.

Nose-only inhalations of high-dose alumina nanoparticles/hydrogen chloride gas mixtures induce strong pulmonary pro-inflammatory response: a pilot study

OBJECTIVE

Solid composite propellants combustion, in aerospace and defense fields, can lead to complex aerosols emission containing high concentrations of alumina nanoparticles (Al₂O₃ NPs) and hydrogen chloride gas (HCl_g). Exposure to these mixtures by inhalation is thus possible but literature data toward their pulmonary toxicity are missing. To specify hazards resulting from these combustion aerosols, a pilot study was implemented.

MATERIALS AND METHODS

Male Wistar rats were nose-only exposed to Al₂O₃ NPs (primary size 13 nm, 10 g/L suspension leading to 20.0-22.1 mg/m³ aerosol) and/or to HCl_g aerosols (5 ppm target concentration) following two exposure scenarios (single exposures (SE) or repeated exposures (RE)). Bronchoalveolar lavage fluids (BALF) content and lungs histopathology were analyzed 24 h after exposures.

RESULTS

Repeated co-exposures increased total proteins and LDH concentrations in BALF indicating alveolar-capillary barrier permeabilization and cytolysis. Early pulmonary inflammation was induced after RE to Al₂O₃ NPs ± HCl_g resulting in PMN, TNF-α, IL-1β, and GRO/KC increases in BALF. Both exposure scenarios resulted in pulmonary histopathological lesions (vascular congestions, bronchial pre-exfoliations, vascular and interalveolar septum edemas). Lung oxidative damages were observed in situ following SE.

CONCLUSION

Observed biological effects are dependent on both aerosol content and exposure scenario. Results showed an important pro-inflammatory effect of Al₂O₃ NPs/HCl_g mixtures on the lungs of rat 24 h after exposure. This pilot study raises concerns toward potential long-term pulmonary toxicity of combustion aerosols and highlights the importance for further studies to be led in order to define dose limitations and exposure thresholds for risk management at the work place.

Multiple roles of caspase-8 in cell death, inflammation, and innate immunity

Caspase-8 is an apical caspase involved in the programmed form of cell death called apoptosis that is critically important for mammalian development and immunity. Apoptosis was historically described as immunologically silent in contrast to other types of programmed cell death such as necroptosis or pyroptosis. Recent reports suggest considerable crosstalk between these different forms of cell death. It is becoming increasingly clear that caspase-8 has many non-apoptotic roles, participating in multiple processes including regulation of necroptosis (mediated by receptor-interacting serine/threonine kinases, RIPK1-RIPK3), inflammatory cytokine expression, inflammasome activation, and cleavage of IL-1β and gasdermin D, and protection against shock and microbial infection. In this review, we discuss the involvement of caspase-8 in cell death and inflammation and highlight its role in innate immune responses and in the relationship between different forms of cell death. Caspase-8 is one of the central components in this type of crosstalk.

Chronic Alcohol Exposure Enhances Lipopolysaccharide-Induced Lung Injury in Mice: Potential Role of Systemic Tumor Necrosis Factor-Alpha

BACKGROUND

It is well known that liver and lung injury can occur simultaneously during severe inflammation (e.g., multiple organ failure). However, whether these are parallel or interdependent (i.e., liver-lung axis) mechanisms is unclear. Previous studies have shown that chronic ethanol (EtOH) consumption greatly increases mortality in the setting of sepsis-induced acute lung injury (ALI). The potential contribution of subclinical liver disease in driving this effect of EtOH on the lung remains unknown. Therefore, the purpose of this study was to characterize the impact of chronic EtOH exposure on concomitant liver and lung injury.

METHODS

Male mice were exposed to EtOH-containing Lieber-DeCarli diet or pair-fed control diet for 6 weeks. Some animals were administered lipopolysaccharide (LPS) 4 or 24 hours prior to sacrifice to mimic sepsis-induced ALI. Some animals received the tumor necrosis factor-alpha (TNF-α)-blocking drug, etanercept, for the duration of alcohol exposure. The expression of cytokine mRNA in lung and liver tissue was determined by quantitative PCR. Cytokine levels in the bronchoalveolar lavage fluid and plasma were determined by Luminex assay.

RESULTS

As expected, the combination of EtOH and LPS caused liver injury, as indicated by significantly increased levels of the transaminases alanine aminotransferase/aspartate aminotransferase in the plasma and by changes in liver histology. In the lung, EtOH preexposure enhanced pulmonary inflammation and alveolar hemorrhage caused by LPS. These changes corresponded with unique alterations in the expression of pro-inflammatory cytokines in the liver (i.e., TNF-α) and lung (i.e., macrophage inflammatory protein-2 [MIP-2], keratinocyte chemoattractant [KC]). Systemic depletion of TNF-α (etanercept) blunted injury and the increase in MIP-2 and KC caused by the combination of EtOH and LPS in the lung.

CONCLUSIONS

Chronic EtOH preexposure enhanced both liver and lung injury caused by LPS. Enhanced organ injury corresponded with unique changes in the pro-inflammatory cytokine expression profiles in the liver and the lung.

Switch regulation of interleukin-1 beta in downstream of inflammatory cytokines induced by two micro-sized silica particles on differentiated THP-1 macrophages

To investigate the regulated role of IL-1β in initiating and maintaining inflammation, PMA-differentiated THP-1 macrophages were exposed to two micro-sized crystalline silica particles (Si3-5μm and Si1μm) from 3h to 24h, respectively. Cytotoxicity and inflammatory cytokines (IL-1β, TNF-α and IL-6) expressions measured showed that they were induced by both silica particles in positive dose-dependent manners. The levels of inflammatory cytokines induced by Si1μm were higher than those induced by Si3-5μm at low concentration. When pretreated with anti-human IL-1β, not only the high levels of IL-1β but also elevated TNF-α and IL-6 induced by both silica particles were remarkably blocked, especially Si1μm particle. In addition, recombinant human IL-1β protein could induce macrophages to strikingly augment TNF-α and IL-6 expressions. Our data suggest that IL-1β could play a critical role of switching regulation in the downstream inflammation induced by micro-sized silica particles.

Inflammasome Activity in Non-Microbial Lung Inflammation

The understanding of interleukin-1 (IL-1) family cytokines in inflammatory disease has rapidly developed, due in part to the discovery and characterization of inflammasomes, which are multi-subunit intracellular protein scaffolds principally enabling recognition of a myriad of cellular stimuli, leading to the activation of caspase-1 and the processing of IL-1β and IL-18. Studies continue to elucidate the role of inflammasomes in immune responses induced by both microbes and environmental factors. This review focuses on the current understanding of inflammasome activity in the lung, with particular focus on the non-microbial instigators of inflammasome activation, including inhaled antigens, oxidants, cigarette smoke, diesel exhaust particles, mineral fibers, and engineered nanomaterials, as well as exposure to trauma and pre-existing inflammatory conditions such as metabolic syndrome. Inflammasome activity in these sterile inflammatory states contribute to diseases including asthma, chronic obstructive disease, acute lung injury, ventilator-induced lung injury, pulmonary fibrosis, and lung cancer.

Immunophenotype expressions and cytokine profiles of influenza A H1N1 virus infection in pediatric patients in 2009

Background. A novel swine-origin influenza A H1N1 virus (S-OIV) caused human infection and acute respiratory illness in 2009, resulting in an influenza pandemic. Objectives. This study characterized the immune responses of S-OIV infection in pediatric patients at risk of pulmonary complications. Methods. All enrolled pediatric patients were confirmed virologically for S-OIV infection in 2009-2010, prospectively. Changes in cellular immunophenotypes were analyzed using flow cytometry. Plasma cytokine levels associated with S-OIV infection by pulmonary and without pulmonary complications were measured using cytokine cytometric bead assay kits. Results. A total of 85 patients with a mean age of 10.3 years were recruited. The level of C-reactive protein (CRP) was high in patients exhibiting pulmonary complications. The percentage of cellular immunophenotypes did not change between patients with and without pulmonary complications. The absolute numbers of peripheral blood mononuclear cells (PBMC), CD3, CD8, and CD16CD56 decreased with acute S-OIV pulmonary complications. Acute influenza infection with pulmonary complications was associated with high plasma concentrations of IL-1β, IL-6, IL-12, and IFN-γ. Conclusion. Immunophenotype studies have reported variability in immune response to the severity of S-OIV infections. Acute phase cytokine profiles of the 2009 S-OIV infection might have contributed to the pathogenesis of the pulmonary complications.

IL-1β and TLR4 signaling are involved in the aggravated murine acute graft-versus-host disease caused by delayed bortezomib administration

It was shown that the proteasome inhibitor, bortezomib, administered immediately following allogeneic bone marrow transplantation resulted in marked inhibition of acute graft-versus-host disease (aGVHD), with retention of graft-versus-tumor effects. However, continuous bortezomib administration resulted in significant acceleration of graft-versus-host disease-dependent morbidity. We carried out studies to dissect the mechanisms of aggravated aGVHD caused by delayed bortezomib administration. First, we demonstrated that IL-1β was critically involved, and the subsequent aGVHD could be alleviated by IL-1β blockade. Bortezomib treatment after dendritic cell (DC) activation resulted in drastically elevated IL-1β production, whereas bortezomib treatment before DC activation inhibited IL-1β production, suggesting that the timing of bortezomib administration significantly affected IL-1β production by DCs. We further demonstrated that delayed administration of bortezomib accelerated aGVHD through TLR4 signaling. Because the LPS levels were much lower with reduced-intensity conditioning compared with high-dose irradiation, the accelerated graft-versus-host disease-dependent morbidity with delayed bortezomib administration could be rescued by reduced-intensity conditioning. Our studies suggested that TLR4 pathway activation and delayed bortezomib administration amplified the production of IL-1β and other inflammatory cytokines, which resulted in accelerated aGVHD-dependent morbidity. These results indicated that decreased toxicity of continuous bortezomib administration could be achieved by reduced-intensity conditioning or by inhibiting IL-1β.

IL-1β promotes antimicrobial immunity in macrophages by regulating TNFR signaling and caspase-3 activation

In vivo control of Mycobacterium tuberculosis reflects the balance between host immunity and bacterial evasion strategies. Effector Th1 cells that mediate protective immunity by depriving the bacterium of its intracellular niche are regulated to prevent overexuberant inflammation. One key immunoregulatory molecule is Tim3. Although Tim3 is generally recognized to downregulate Th1 responses, we recently described that its interaction with Galectin-9 expressed by M. tuberculosis-infected macrophages stimulates IL-1β secretion, which is essential for survival in the mouse model. Why IL-1β is required for host resistance to M. tuberculosis infection is unknown. In this article, we show that IL-1β directly kills M. tuberculosis in murine and human macrophages and does so through the recruitment of other antimicrobial effector molecules. IL-1β directly augments TNF signaling in macrophages through the upregulation of TNF secretion and TNFR1 cell surface expression, and results in activation of caspase-3. Thus, IL-1β and downstream TNF production lead to caspase-dependent restriction of intracellular M. tuberculosis growth.

Effect of IL-1β and TNF-α vs IL-13 on bronchial hyperresponsiveness, β2-adrenergic responses and cellularity of bronchial alveolar lavage fluid

1 Levels of IL-13, IL-1β and TNF-α are increased in bronchial lavage fluid of asthmatics and induce certain significant features of bronchial asthma including airway hyper-responsiveness (AHR). In this study, we have investigated the effect of these cytokines in naïve mice and those sensitized to ovalbumin (OVA) on bronchoconstrictions to methacholine (MCh) and the functional antagonism induced by β2 -adrenoceptor agonism. 2 Naïve or OVA-sensitized mice were treated for 3 days with IL-1β (250 U), TNF-α (150 ng), IL-13 (5 μg) or combinations of IL-1β with TNF-α or IL-1β with IL-13. MCh-induced bronchoconstriction and its sensitivity to albuterol, a β2-adrenoceptor agonist, was assessed 24 h after the last cytokine administration. 3 In naïve mice, responsiveness to MCh was significantly increased by the combination of IL-1β and TNF-α, IL-13 alone or in combination with IL-1β, but not by treatment with IL-1β or TNF-α alone. Similar results were obtained in OVA-sensitized mice except that treatment with IL-13 alone did not increase sensitivity to MCh. 4 In naïve mice, albuterol sensitivity was only significantly attenuated by treatment with IL-1β and TNF-α in combination. In mice sensitized to OVA, albuterol sensitivity was significantly attenuated by treatment with TNF-α, IL-13 or IL-13 in combination with IL-1β. 5 Inflammatory cell influx was increased by all cytokines and combinations except IL-13 in OVA-sensitized mice. 6 Our data do not support a link between inflammatory cell influx and AHR. In addition, the mechanism of IL-13-induced AHR might involve decreased β2-adrenoceptor responsiveness.

Interferon-γ and tumor necrosis factor-α act synergistically to up-regulate tissue factor in alveolar epithelial cells

Fibrin deposition mediated through activation of tissue factor (TF) in the airspace is central to the pathogenesis of acute lung injury. Defining the mechanisms of TF regulation in the lung is critical to understanding pulmonary fibrin formation. Tumor necrosis factor-α (TNF-α) up-regulates TF in the injured lung, and there is emerging evidence that another cytokine, interferon-γ (IFN-γ), also modulates expression. The effects of TNF-α and IFN-γ on regulation of TF were studied in alveolar epithelial A549 cells. In addition, potential mechanisms of modulation of TF expression by the 2 cytokines were analyzed with the hypothesis that IFN-γ acts synergistically with TNF-α to up-regulate alveolar epithelial TF through modulation of TNF receptor (TNFR) expression. TNF-α but not IFN-γ treatment increased TF mRNA, protein, and cell surface TF activity. The combination of IFN-γ and TNF-α treatment augmented the effects of TNF-α on TF up-regulation and also increased release of procoagulant microparticles (MPs) from A549 cells. IFN-γ modulated expression of both TNF-α receptors. Studies utilizing neutralizing antibodies against the two TNF receptors showed that the TF effects were mediated primarily through augmentation of TNFR1-dependent cellular responses. These findings have important implications for regulation of fibrin formation in the lung in the setting of acute inflammation.