IL-1 receptor antagonist attenuates proinflammatory responses to rhinovirus in airway epithelium.

BACKGROUND: Rhinoviruses (RVs) are the most common trigger for asthma exacerbations, and there are currently no targeted therapies for viral-induced asthma exacerbations. RV infection causes neutrophilic inflammation, which is often resistant to effects of glucocorticoids. IL-1 receptor antagonist (IL-1RA) treatment reduces neutrophilic inflammation in humans challenged with inhaled endotoxin and thus may have therapeutic potential for RV-induced asthma exacerbations. OBJECTIVE: We sought to test the hypothesis that IL-1RA treatment of airway epithelium reduces RV-mediated proinflammatory cytokine production, which is important for neutrophil recruitment. METHODS: Human bronchial epithelial cells from deceased donors without prior pulmonary disease were cultured at air-liquid interface and treated with IL-13 to approximate an asthmatic inflammatory milieu. Human bronchial epithelial cells were infected with human RV-16 with or without IL-1RA treatment. RESULTS: RV infection promoted the release of IL-1α and the neutrophil-attractant cytokines IL-6, IL-8, and CXCL10. Proinflammatory cytokine secretion was significantly reduced by IL-1RA treatment without significant change in IFN-ß release or RV titer. In addition, IL-1RA reduced MUC5B expression after RV infection without impacting MUC5AC. CONCLUSIONS: These data suggest that IL-1RA treatment significantly reduced proinflammatory cytokines while preserving the antiviral response. These results provide evidence for further investigation of IL-1RA as a novel targeted therapy against neutrophil-attractant cytokine release in RV-induced airway inflammatory responses.

Ozone in the Development of Pediatric Asthma and Atopic Disease.

Ozone (O3) is a ubiquitous outdoor air pollutant, which may be derived from various primary pollutants such as nitrates, hydrocarbons, and volatile organ compounds through ultraviolet radiation exposure, and has been shown to negatively impact respiratory health. O3 is the most common noninfectious environmental cause of asthma exacerbations among children and adults. Its effects on pediatric respiratory health could be due to multiple physiologic factors that may contribute to enhanced O3 exposure seen in children compared with adults, including differences in lung surface area per unit of body weight and ventilation rates. O3 can reach the distal regions of human lungs due to its low water solubility, resulting in either injury or activation of airway epithelial cells and macrophages. Multiple epidemiologic studies have highlighted a link between exposure to air pollution and the development of asthma. This review article specifically focuses on examining the impact of early life O3 exposure on lung development, lung function, and the risk of developing atopic diseases including asthma, allergic rhinitis, and atopic dermatitis among children.

Climate change and global issues in allergy and immunology.

The steady increase in global temperatures, resulting from the combustion of fossil fuels and the accumulation of greenhouse gases (GHGs), continues to destabilize all ecosystems worldwide. Although annual emissions must be halved by 2030 and reach net zero by 2050 to limit some of the most catastrophic impacts associated with a warming planet, the world's efforts to curb GHG emissions fall short of the commitments made in the 2015 Paris Agreement. To this effect, July 2021 was recently declared the hottest month ever recorded in 142 years. The ramifications of these changes for global temperatures are complex and further promote outdoor air pollution, pollen exposure, and extreme weather events. Besides worsening respiratory health, air pollution promotes atopy and susceptibility to infections. The effects of GHGs on pollen affect the frequency and severity of asthma and allergic rhinitis. Changes in temperature, air pollution, and extreme weather events exert adverse multisystemic health effects and disproportionally affect disadvantaged and vulnerable populations. This review article is an update for allergists and immunologists about the health impacts of climate change that are already evident in our daily practices. It is also a call to action and advocacy, including to integrate climate change-related mitigation, education, and adaptation measures to protect our patients and avert further injury to our planet.

Electronic cigarettes: One size does not fit all.

Electronic cigarettes (ECs) have been growing rapidly in popularity among youth and adults in the United States over the last decade. This increasing prevalence is driven partially by the ability to customize devices, flavors, and nicotine content and the general notion that ECs are harmless, particularly in comparison with conventional cigarettes. In vitro and in vivo murine models have demonstrated a number of harmful biological effects of e-liquids and their aerosols. However, limited clinical data exist on whether these effects translate into detrimental long-term outcomes in human subjects. The short-term harmful respiratory effects of EC use demonstrated in nonsmokers argue against their use. However, slightly more favorable data exist for the respiratory benefits of substituting conventional cigarettes with ECs and the short-term efficacy of ECs as smoking cessation tools. Nonetheless, available research is severely limited in regard to long-term outcomes and by study designs fraught with bias, pointing to the need for additional research efforts with well-designed longitudinal studies to guide US Food and Drug Administration regulatory efforts. The hurdle presented by diverse device designs and e-liquid permutations, which contribute to the inconsistency of available data, also highlights the need for legislative standardization of ECs.

Environmental determinants of allergy and asthma in early life.

Allergic disease prevalence has increased significantly in recent decades. Primary prevention efforts are being guided by study of the exposome (or collective environmental exposures beginning during the prenatal period) to identify modifiable factors that affect allergic disease risk. In this review we explore the evidence supporting a relationship between key components of the external exposome in the prenatal and early-life periods and their effect on atopy development focused on microbial, allergen, and air pollution exposures. The abundance and diversity of microbial exposures during the first months and years of life have been linked with risk of allergic sensitization and disease. Indoor environmental allergen exposure during early life can also affect disease development, depending on the allergen type, dose, and timing of exposure. Recent evidence supports the role of ambient air pollution in allergic disease inception. The lack of clarity in the literature surrounding the relationship between environment and atopy reflects the complex interplay between cumulative environmental factors and genetic susceptibility, such that no one factor dictates disease development in all subjects. Understanding the effect of the summation of environmental exposures throughout a child's development is needed to identify cost-effective interventions that reduce atopy risk in children.

A proof-of-concept clinical study examining the NRF2 activator sulforaphane against neutrophilic airway inflammation.

UNLABELLED: Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, is implicated as a possible therapy for airway inflammation via induction of the transcription factor NF-E2-related factor 2 (NRF2). In this proof-of-concept clinical study, we show that supplementation of SFN with broccoli sprout homogenate in healthy human subjects did not induce expression of antioxidant genes or protect against neutrophilic airway inflammation in an ozone-exposure model. Therefore, dietary sulforaphane supplementation is not a promising candidate for larger scale clinical trials targeting airway inflammation. TRIAL REGISTRATION: NCT01625130 . Registered 19 June, 2012.

Wood Smoke Particle Sequesters Cell Iron to Impact a Biological Effect.

The biological effect of an inorganic particle (i.e., silica) can be associated with a disruption in cell iron homeostasis. Organic compounds included in particles originating from combustion processes can also complex sources of host cell iron to disrupt metal homeostasis. We tested the postulate that (1) wood smoke particle (WSP) sequesters host cell iron resulting in a disruption of metal homeostasis, (2) this loss of essential metal results in both an oxidative stress and biological effect in respiratory epithelial cells, and (3) humic-like substances (HULIS), a component of WSP, have a capacity to appropriate cell iron and initiate a biological effect. BEAS-2B cells exposed to WSP resulted in diminished concentrations of mitochondrial (57)Fe, whereas preincubation with ferric ammonium citrate (FAC) prevented significant mitochondrial iron loss after such exposure. Cellular oxidant generation was increased after WSP exposure, but this signal was diminished by coincubation with FAC. Similarly, exposure of BEAS-2B cells to 100 µg/mL WSP activated mitogen-activated protein (MAP) kinases, elevated NF-E2-related factor 2/antioxidant responsive element (Nrf2 ARE) expression, and provoked interleukin (IL)-6 and IL-8 release, but all these changes were diminished by coincubation with FAC. The biological response to WSP was reproduced by exposure to 100 µg/mL humic acid, a polyphenol comparable to HULIS included in the WSP that complexes iron. We conclude that (1) the biological response following exposure to WSP is associated with sequestration of cell iron by the particle, (2) increasing available iron in the cell diminished the biological effects after particle exposure, and (3) HULIS included in WSP can sequester the metal initiating the cell response.

Iron diminishes the in vitro biological effect of vanadium.

Mechanistic pathways underlying inflammatory injury following exposures to vanadium-containing compounds are not defined. We tested the postulate that the in vitro biological effect of vanadium results from its impact on iron homeostasis. Human bronchial epithelial (HBE) cells exposed to vanadyl sulfate (VOSO4) showed a time- and dose-dependent increase in vanadium relative to PBS. HBE cells exposed to VOSO4 and then exposed to ferric ammonium citrate (FAC) significantly increased intracellular iron import supporting an interaction between the two metals. Following exposure to VOSO4, there was an increase (336±73%) in RNA for divalent metal transporter 1 (DMT1), a major iron importer. With inclusion of VOSO4 in the incubation, vanadium could be measured in the nuclear and mitochondrial fractions and the supernatant. Non-heme iron in the nuclear and mitochondrial fractions were decreased immediately following VOSO4 exposure while there was an increased concentration of non-heme iron in the supernatant. Provision of excess iron inhibited changes in the concentration of this metal provoked by VOSO4 exposures. Using Amplex Red, VOSO4 was shown to significantly increase oxidant generation by HBE cells in a time- and dose-dependent manner. HBE cells pre-treated with FAC and then exposed to VOSO4 demonstrated a decreased generation of oxidants. Similarly, activation of the transcription factor NF-ĸB promoter and release of interleukin-6 and -8 were increased following VOSO4 exposure and these effects were diminished by pre-treatment with FAC. We conclude that an initiating event in biological effect after exposure to vanadyl sulfate is a loss of requisite cell iron.

Sequestration of mitochondrial iron by silica particle initiates a biological effect.

Inhalation of particulate matter has presented a challenge to human health for thousands of years. The underlying mechanism for biological effect following particle exposure is incompletely understood. We tested the postulate that particle sequestration of cell and mitochondrial iron is a pivotal event mediating oxidant generation and biological effect. In vitro exposure of human bronchial epithelial cells to silica reduced intracellular iron, which resulted in increases in both the importer divalent metal transporter 1 expression and metal uptake. Diminished mitochondrial (57)Fe concentrations following silica exposure confirmed particle sequestration of cell iron. Preincubation of cells with excess ferric ammonium citrate increased cell, nuclear, and mitochondrial metal concentrations and prevented significant iron loss from mitochondria following silica exposure. Cell and mitochondrial oxidant generation increased after silica incubation, but pretreatment with iron diminished this generation of reactive oxygen species. Silica exposure activated MAP kinases (ERK and p38) and altered the expression of transcription factors (nF-κB and NF-E2-related factor 2), proinflammatory cytokines (interleukin-8 and -6), and apoptotic proteins. All of these changes in indexes of biological effect were either diminished or inhibited by cell pretreatment with iron. Finally, percentage of neutrophils and total protein concentrations in an animal model instilled with silica were decreased by concurrent exposure to iron. We conclude that an initiating event in the response to particulate matter is a sequestration of cell and mitochondrial iron by endocytosed particle. The resultant oxidative stress and biological response after particle exposure are either diminished or inhibited by increasing the cell iron concentration.

Sulforaphane induces SLPI secretion in the nasal mucosa.

Cells lining the respiratory tract are equipped with mechanisms that dampen the effects of oxidative stress. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a mediator involved in regulating oxidative stress. Recent data indicate Nrf2 also controls expression of secretory leukocyte protease inhibitor (SLPI). Sulforaphane (SFN), an isothiocyanate found in cruciferous vegetables, enhances Nrf2 activity. Therefore, we hypothesized that SFN supplementation induces SLPI secretion in the nasal mucosa in an Nrf2 dependent manner. Healthy nonsmoking adults ingested SFN-containing broccoli shake homogenate (BSH) for 3 consecutive days. Nasal lavage fluid (NLF) was collected before and after BSH ingestion and analyzed for SLPI protein levels. In follow up in vitro experiments, differentiated primary nasal epithelial cells were used to evaluate the relationship between SFN, Nrf2, and SLPI. Epithelial cells were transduced with Nrf2-specific shRNA to examine the regulatory role of Nrf2 on SLPI expression. Supplementation with BSH significantly increased SLPI levels in NLF. SFN supplementation in vitro significantly enhanced SLPI secretion and these effects were significantly decreased in cells transduced with Nrf2-specific shRNA. Our data support a relationship between nutritional supplementation, Nrf2 activation, and SLPI secretion. Therefore, ingestion of SFN-containing foods has therapeutic potential to augment SLPI expression in the nasal mucosa.

Airway protease/antiprotease imbalance in atopic asthmatics contributes to increased influenza A virus cleavage and replication.

Asthmatics are more susceptible to influenza infections, yet mechanisms mediating this enhanced susceptibility are unknown. Influenza virus hemagglutinin (HA) protein binds to sialic acid residues on the host cells. HA requires cleavage to allow fusion of the viral HA with host cell membrane, which is mediated by host trypsin-like serine protease. We show data here demonstrating that the protease:antiprotease ratio is increased in the nasal mucosa of asthmatics and that these changes were associated with increased proteolytic activation of influenza. These data suggest that disruption of the protease balance in asthmatics enhances activation and infection of influenza virus.

Exposure to ozone modulates human airway protease/antiprotease balance contributing to increased influenza A infection.

Exposure to oxidant air pollution is associated with increased respiratory morbidities and susceptibility to infections. Ozone is a commonly encountered oxidant air pollutant, yet its effects on influenza infections in humans are not known. The greater Mexico City area was the primary site for the spring 2009 influenza A H1N1 pandemic, which also coincided with high levels of environmental ozone. Proteolytic cleavage of the viral membrane protein hemagglutinin (HA) is essential for influenza virus infectivity. Recent studies suggest that HA cleavage might be cell-associated and facilitated by the type II transmembrane serine proteases (TTSPs) human airway trypsin-like protease (HAT) and transmembrane protease, serine 2 (TMPRSS2), whose activities are regulated by antiproteases, such as secretory leukocyte protease inhibitor (SLPI). Based on these observations, we sought to determine how acute exposure to ozone may modulate cellular protease/antiprotease expression and function, and to define their roles in a viral infection. We utilized our in vitro model of differentiated human nasal epithelial cells (NECs) to determine the effects of ozone on influenza cleavage, entry, and replication. We show that ozone exposure disrupts the protease/antiprotease balance within the airway liquid. We also determined that functional forms of HAT, TMPRSS2, and SLPI are secreted from human airway epithelium, and acute exposure to ozone inversely alters their expression levels. We also show that addition of antioxidants significantly reduces virus replication through the induction of SLPI. In addition, we determined that ozone-induced cleavage of the viral HA protein is not cell-associated and that secreted endogenous proteases are sufficient to activate HA leading to a significant increase in viral replication. Our data indicate that pre-exposure to ozone disrupts the protease/antiprotease balance found in the human airway, leading to increased influenza susceptibility.

Nrf2 expression modifies influenza A entry and replication in nasal epithelial cells.

Influenza infection is a major cause of morbidity and mortality worldwide, especially during pandemics outbreaks. Emerging data indicate that phase II antioxidant enzyme pathways could play a role in virus-associated inflammation and immune clearance. While Nrf2-dependent gene expression is known to modify inflammation, a mechanistic role in viral susceptibility and clearance has yet to be elucidated. Therefore, we utilized differentiated human nasal epithelial cells (NEC) and an enzymatic virus-like particle entry assay, to examine the role Nrf2-dependent gene expression has on viral entry and replication. Herein, lentiviral vectors that express Nrf2-specific short hairpin (sh)-RNA effectively decreased both Nrf2 mRNA and Nrf2 protein expression in transduced human NEC from healthy volunteers. Nrf2 knockdown correlated with a significant increase in influenza virus entry and replication. Conversely, supplementation with the potent Nrf2 activators sulforaphane (SFN) and epigallocatechin gallate (EGCG) significantly decreased viral entry and replication. The suppressive effects of EGCG on viral replication were abolished in cells with knocked-down Nrf2 expression, suggesting a causal relationship between the EGCG-induced activation of Nrf2 and the ability to protect against viral infection. Interestingly, the induction of Nrf2 via nutritional supplements SFN and EGCG increased antiviral mediators/responses: RIG-I, IFN-ß, and MxA at baseline in the absence of infection. Our data indicate that there is an inverse relationship between the levels of Nrf2 expression and the viral entry/replication. We also demonstrate that supplementation with Nrf2-activating antioxidants inhibits viral replication in human NEC, which may prove to be an attractive therapeutic intervention. Taken together, these data indicate potential mechanisms by which Nrf2-dependent gene expression regulates susceptibility to influenza in human epithelial cells.