Effects of increasing tidal volume and end-expiratory lung volume on induced bronchoconstriction in healthy humans.

BACKGROUND: Increasing functional residual capacity (FRC) or tidal volume (VT) reduces airway resistance and attenuates the response to bronchoconstrictor stimuli in animals and humans. What is unknown is which one of the above mechanisms is more effective in modulating airway caliber and whether their combination yields additive or synergistic effects. To address this question, we investigated the effects of increased FRC and increased VT in attenuating the bronchoconstriction induced by inhaled methacholine (MCh) in healthy humans. METHODS: Nineteen healthy volunteers were challenged with a single-dose of MCh and forced oscillation was used to measure inspiratory resistance at 5 and 19 Hz (R5 and R19), their difference (R5-19), and reactance at 5 Hz (X5) during spontaneous breathing and during imposed breathing patterns with increased FRC, or VT, or both. Importantly, in our experimental design we held the product of VT and breathing frequency (BF), i.e, minute ventilation (VE) fixed so as to better isolate the effects of changes in VT alone. RESULTS: Tripling VT from baseline FRC significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Doubling VT while halving BF had insignificant effects. Increasing FRC by either one or two VT significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Increasing both VT and FRC had additive effects on R5, R19, R5-19 and X5, but the effect of increasing FRC was more consistent than increasing VT thus suggesting larger bronchodilation. When compared at iso-volume, there were no differences among breathing patterns with the exception of when VT was three times larger than during spontaneous breathing. CONCLUSIONS: These data show that increasing FRC and VT can attenuate induced bronchoconstriction in healthy humans by additive effects that are mainly related to an increase of mean operational lung volume. We suggest that static stretching as with increasing FRC is more effective than tidal stretching at constant VE, possibly through a combination of effects on airway geometry and airway smooth muscle dynamics.

Repeated doses of captopril induce airway hyperresponsiveness by modulating the TRPV1 receptor in rats.

Although TRPV1 receptors play an essential role in the adverse effects on the airways following captopril treatment, there is no available evidence of their involvement in treatment regimens involving repeated doses of captopril. Comparing the difference in these two treatment regimens is essential since captopril is a continuous-use medication. Thus, this study explored the role of the transient receptor potential vanilloid 1 (TRPV1) in the effects of captopril on rat airways using two treatment regimens. Airway resistance, bronchoalveolar lavage (BAL), and histological and immunohistochemical analyses were conducted in rats administered with single or repeated doses of captopril. This study showed that the hyperresponsiveness to bradykinin and capsaicin in captopril-treated rats was acute. Treatment with the selective B2 antagonist, HOE140 reduced bradykinin hyperresponsiveness and abolished capsaicin exacerbation in single-dose captopril-treated rats. Likewise, degeneration of TRPV1-positive neurones also reduced hyperresponsiveness to bradykinin. Single-dose captopril treatment increased leukocyte infiltration in the BAL when compared with the vehicle and this increase was reduced by TRPV1-positive neurone degeneration. However, when compared with the vehicle treatment, animals treated with repeated doses of captopril showed an increase in leukocyte influx as early as 1 h after the last captopril treatment, but this effect disappeared after 24 h. Additionally, an increase in TRPV1 expression occurred only in animals who received repeated captopril doses and the degeneration of TRPV1-positive neurones attenuated TRPV1 upregulation. In conclusion, these data strongly indicate that a treatment regimen involving multiple doses of captopril not only enhances sensitisation but also upregulates TRPV1 expression. Consequently, targeting TRPV1 could serve as a promising strategy to reduce the negative impact of captopril on the airways.

Six-Year Follow-up of a Trial of Antenatal Vitamin D for Asthma Reduction.

BACKGROUND: We previously reported the results of a trial of prenatal vitamin D supplementation to prevent asthma and recurrent wheeze in young children, which suggested that supplementation provided a protective effect at the age of 3 years. We followed the children through the age of 6 years to determine the course of asthma and recurrent wheeze. METHODS: In this follow-up study, investigators and participants remained unaware of the treatment assignments through the children's sixth birthday. We aimed to determine whether, when maternal levels of 25-hydroxyvitamin D were taken into account, children born to mothers who had received 4400 IU of vitamin D3 per day during pregnancy (vitamin D group) would have a lower incidence of asthma and recurrent wheeze at the age of 6 years than would those born to mothers who had received 400 IU of vitamin D3 per day (control group). Time-to-event methods were used to compare the treatment groups with respect to time to the onset of asthma or recurrent wheeze. Multivariate methods were used to compare longitudinal measures of lung function between the treatment groups. RESULTS: There was no effect of maternal vitamin D supplementation on asthma and recurrent wheeze in either an intention-to-treat analysis or an analysis with stratification according to the maternal 25-hydroxyvitamin D level during pregnancy. There was no effect of prenatal vitamin D supplementation on most of the prespecified secondary outcomes. We found no effects of prenatal supplementation on spirometric indexes. Although there was a very small effect on airway resistance as measured by impulse oscillometry, this finding was of uncertain significance. CONCLUSIONS: Vitamin D supplementation during the prenatal period alone did not influence the 6-year incidence of asthma and recurrent wheeze among children who were at risk for asthma. (Funded by the National Heart, Lung, and Blood Institute; VDAART ClinicalTrials.gov number, NCT00920621.).

Store-operated calcium entry-associated regulatory factor regulates airway inflammation and airway remodeling in asthma mice models.

Store-operated calcium entry (SOCE) is involved in the pathogenesis of airway inflammation and remodeling in asthma. Store-operated calcium entry-associated regulatory factor (SARAF) can downregulate SOCE. We sought to investigate the role of SARAF in the regulation of airway inflammation and remodeling in asthma mice models, as well as in the functional regulation of human airway smooth muscle cells (hASMCs). Balb/c mice were sensitized and challenged with ovalbumin to establish the asthma mice models. Mice were transfected with lentivirus, which expressed the SARAF gene + GFP (green fluorescence protein) or the negative control gene + GFP. Airway resistance was measured with the animal pulmonary function system. Airway inflammation and remodeling were evaluated via histological staining. In vitro cultured hASMCs were transfected with scrambled small interfering RNA (siRNA) or SARAF-specific siRNA, respectively. The proliferation, migration rate, hypertrophy, and SOCE activity of hASMCs were examined with Cell Counting Kit-8, wound healing test, bright field imaging, and Ca2+ fluorescence imaging, respectively. SARAF expression was measured by quantitative real-time PCR. Asthma mice models showed decreased SARAF mRNA expression in the lungs. SARAF overexpression attenuated airway inflammation, resistance, and also remodeling. Downregulation of SARAF expression with siRNA promoted the proliferation, migration, hypertrophy, and SOCE activity in hASMCs. SARAF plays a protective role against airway inflammation and remodeling in asthma mice models by blunting SOCE; SARAF may also be a functional regulating factor of hASMCs.

Human ß-defensin-2 suppresses key features of asthma in murine models of allergic airways disease.

BACKGROUND: Asthma is an airway inflammatory disease and a major health problem worldwide. Anti-inflammatory steroids and bronchodilators are the gold-standard therapy for asthma. However, they do not prevent the development of the disease, and critically, a subset of asthmatics are resistant to steroid therapy. OBJECTIVE: To elucidate the therapeutic potential of human ß-defensins (hBD), such as hBD2 mild to moderate and severe asthma. METHODS: We investigated the role of hBD2 in a steroid-sensitive, house dust mite-induced allergic airways disease (AAD) model and a steroid-insensitive model combining ovalbumin-induced AAD with C muridarum (Cmu) respiratory infection. RESULTS: In both models, we demonstrated that therapeutic intranasal application of hBD2 significantly reduced the influx of inflammatory cells into the bronchoalveolar lavage fluid. Furthermore, key type 2 asthma-related cytokines IL-9 and IL-13, as well as additional immunomodulating cytokines, were significantly decreased after administration of hBD2 in the steroid-sensitive model. The suppression of inflammation was associated with improvements in airway physiology and treatment also suppressed airway hyper-responsiveness (AHR) in terms of airway resistance and compliance to methacholine challenge. CONCLUSIONS AND CLINICAL RELEVANCE: These data indicate that hBD2 reduces the hallmark features and has potential as a new therapeutic agent in allergic and especially steroid-resistant asthma.

Lung developmental is altered after inhalation exposure to various concentrations of calcium arsenate.

Exposure to dust from active and abandoned mining operations may be a very significant health hazard, especially to sensitive populations. We have previously reported that inhalation of real-world mine tailing dusts during lung development can alter lung function and structure in adult male mice. These real-world dusts contain a mixture of metal(loid)s, including arsenic. To determine whether arsenic in inhaled dust plays a role in altering lung development, we exposed C57Bl/6 mice to a background dust (0 arsenic) or to the background dust containing either 3% or 10% by mass, calcium arsenate. Total level of exposure was kept at 100 µg/m3. Calcium arsenate was selected since arsenate is the predominant species found in mine tailings. We found that inhalation exposure during in utero and postnatal lung development led to significant increases in pulmonary baseline resistance, airway hyper-reactivity, and airway collagen and smooth muscle expression in male C57Bl/6 mice. Responses were dependent on the level of calcium arsenate in the simulated dust. These changes were not associated with increased expression of TGF-ß1, a marker of epithelial to mesenchymal transition. However, responses were correlated with decreases in the expression of club cell protein 16 (CC16). Dose-dependent decreases in CC16 expression and increases in collagen around airways was seen for animals exposed in utero only (GD), animals exposed postnatally only (PN) and animals continuously exposed throughout development (GDPN). These data suggest that arsenic inhalation during lung development can decrease CC16 expression leading to functional and structural alterations in the adult lung.

Heliox for croup in children.

BACKGROUND: Croup is an acute viral respiratory infection with upper airway mucosal inflammation that may cause respiratory distress. Most cases are mild. Moderate to severe croup may require treatment with corticosteroids (the benefits of which are often delayed) and nebulised epinephrine (adrenaline) (the benefits of which may be short-lived and which can cause dose-related adverse effects including tachycardia, arrhythmias, and hypertension). Rarely, croup results in respiratory failure necessitating emergency intubation and ventilation. A mixture of helium and oxygen (heliox) may prevent morbidity and mortality in ventilated neonates by reducing the viscosity of the inhaled air. It is currently used during emergency transport of children with severe croup. Anecdotal evidence suggests that it relieves respiratory distress. This review updates versions published in 2010, 2013, and 2018. OBJECTIVES: To examine the effect of heliox compared to oxygen or other active interventions, placebo, or no treatment on relieving signs and symptoms in children with croup as determined by a croup score and rates of admission and intubation. SEARCH METHODS: We searched CENTRAL, which includes the Cochrane Acute Respiratory Infections Group Specialised Register, MEDLINE, Embase, CINAHL, Web of Science, and LILACS, on 15 April 2021. We also searched the World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch/) and ClinicalTrials.gov (clinicaltrials.gov) on 15 April 2021. We contacted the British Oxygen Company, a leading supplier of heliox. SELECTION CRITERIA: Randomised controlled trials (RCTs) and quasi-RCTs comparing the effect of heliox in comparison with placebo, no treatment, or any active intervention(s) in children with croup. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. Data that could not be pooled for statistical analysis were reported descriptively. MAIN RESULTS: We included 3 RCTs involving a total of 91 children aged between 6 months and 4 years. Study duration was from 7 to 16 months, and all studies were conducted in emergency departments. Two studies were conducted in the USA and one in Spain. Heliox was administered as a mixture of 70% heliox and 30% oxygen. Risk of bias was low in two studies and high in one study because of its open-label design. We did not identify any new trials for this 2021 update. One study of 15 children with mild croup compared heliox with 30% humidified oxygen administered for 20 minutes. There may be no difference in croup score changes between groups at 20 minutes (mean difference (MD) -0.83, 95% confidence interval (CI) -2.36 to 0.70) (Westley croup score, scale range 0 to 16). The mean croup score at 20 minutes postintervention may not differ between groups (MD -0.57, 95% CI -1.46 to 0.32). There may be no difference between groups in mean respiratory rate (MD 6.40, 95% CI -1.38 to 14.18) and mean heart rate (MD 14.50, 95% CI -8.49 to 37.49) at 20 minutes. The evidence for all outcomes in this comparison was of low certainty, downgraded for serious imprecision. All children were discharged, but information on hospitalisation, intubation, or re-presenting to emergency departments was not reported. In another study, 47 children with moderate croup received one dose of oral dexamethasone (0.3 mg/kg) with either heliox for 60 minutes or no treatment. Heliox may slightly improve Taussig croup scores (scale range 0 to 15) at 60 minutes postintervention (MD -1.10, 95% CI -1.96 to -0.24), but there may be no difference between groups at 120 minutes (MD -0.70, 95% CI -1.56 to 0.16). Children treated with heliox may have lower mean Taussig croup scores at 60 minutes (MD -1.11, 95% CI -2.05 to -0.17) but not at 120 minutes (MD -0.71, 95% CI -1.72 to 0.30). Children treated with heliox may have lower mean respiratory rates at 60 minutes (MD -4.94, 95% CI -9.66 to -0.22), but there may be no difference at 120 minutes (MD -3.17, 95% CI -7.83 to 1.49). There may be a difference in hospitalisation rates between groups (odds ratio 0.46, 95% CI 0.04 to 5.41). We assessed the evidence for all outcomes in this comparison as of low certainty, downgraded due to imprecision and high risk of bias related to an open-label design. Information on heart rate and intubation was not reported. In the third study, 29 children with moderate to severe croup all received continuous cool mist and intramuscular dexamethasone (0.6 mg/kg). They were then randomised to receive either heliox (given as a mixture of 70% helium and 30% oxygen) plus one to two doses of nebulised saline or 100% oxygen plus nebulised epinephrine (adrenaline), with gas therapy administered continuously for three hours. Heliox may slightly improve croup scores at 90 minutes postintervention, but may result in little or no difference overall using repeated-measures analysis. We assessed the evidence for all outcomes in this comparison as of low certainty, downgraded due to high risk of bias related to inadequate reporting. Information on hospitalisation or re-presenting to the emergency department was not reported. The included studies did not report on adverse events, intensive care admissions, or parental anxiety. We could not pool the available data because each comparison included data from only one study. AUTHORS' CONCLUSIONS: Given the very limited available evidence, uncertainty remains regarding the effectiveness and safety of heliox. Heliox may not be more effective than 30% humidified oxygen for children with mild croup, but may be beneficial in the short term for children with moderate croup treated with dexamethasone. The effect of heliox may be similar to 100% oxygen given with one or two doses of adrenaline. Adverse events were not reported, and it is unclear if these were monitored in the included studies. Adequately powered RCTs comparing heliox with standard treatments are needed to further assess the role of heliox in the treatment of children with moderate to severe croup.

Previous Influenza Infection Exacerbates Allergen Specific Response and Impairs Airway Barrier Integrity in Pre-Sensitized Mice.

In this study we assessed the effects of antigen exposure in mice pre-sensitized with allergen following viral infection on changes in lung function, cellular responses and tight junction expression. Female BALB/c mice were sensitized to ovalbumin and infected with influenza A before receiving a second ovalbumin sensitization and challenge with saline, ovalbumin (OVA) or house dust mite (HDM). Fifteen days post-infection, bronchoalveolar inflammation, serum antibodies, responsiveness to methacholine and barrier integrity were assessed. There was no effect of infection alone on bronchoalveolar lavage cellular inflammation 15 days post-infection; however, OVA or HDM challenge resulted in increased bronchoalveolar inflammation dominated by eosinophils/neutrophils or neutrophils, respectively. Previously infected mice had higher serum OVA-specific IgE compared with uninfected mice. Mice previously infected, sensitized and challenged with OVA were most responsive to methacholine with respect to airway resistance, while HDM challenge caused significant increases in both tissue damping and tissue elastance regardless of previous infection status. Previous influenza infection was associated with decreased claudin-1 expression in all groups and decreased occludin expression in OVA or HDM-challenged mice. This study demonstrates the importance of the respiratory epithelium in pre-sensitized individuals, where influenza-infection-induced barrier disruption resulted in increased systemic OVA sensitization and downstream effects on lung function.

Peak nasal inspiratory airflow measurements for assessing laryngopharyngeal reflux treatment.

OBJECTIVES: To evaluate the effect of laryngopharyngeal reflux (LPR) and antireflux treatment on peak nasal inspiratory airflow (PNIF). DESIGN: Prospective observational study was conducted. SETTING: Tertiary otorhinolaryngology clinic. PARTICIPANTS: Adults with LPR and healthy controls. MAIN OUTCOME MEASURES: PNIF measurements were performed on 60 patients who applied with complaints suggestive of LPR having higher Reflux Symptom Index (RSI) (>13) and Reflux Finding Scores (RFS) scores (>7). Proton pump inhibitor (PPI) treatment was started and PNIF measurements were repeated two months later. A total of 100 patients without any history of LPR and sinonasal disease were included in the study. RESULTS: A statistically significant increase was observed in PNIF values after proton pump inhibitor treatment. The mean PNIF values of the LPR patients were 133.83 ± 27.99 L/min and 149.92 ± 23.23 L/min before and after treatment, respectively. The mean PNIF value in the control group was 145.0 ± 25.92 L/min. PNIF values were significantly lower in the LPR relative to the control group (P < .05). CONCLUSION: Laryngopharyngeal reflux decreases PNIF. This negative effect on PNIF disappears after antireflux medication. The results of the study indicate that PNIF measurements may be an appropriate method for clinical diagnosis of LPR and evaluation of treatment results.

Perinatal maternal antibiotic exposure augments lung injury in offspring in experimental bronchopulmonary dysplasia.

During the newborn period, intestinal commensal bacteria influence pulmonary mucosal immunology via the gut-lung axis. Epidemiological studies have linked perinatal antibiotic exposure in human newborns to an increased risk for bronchopulmonary dysplasia, but whether this effect is mediated by the gut-lung axis is unknown. To explore antibiotic disruption of the newborn gut-lung axis, we studied how perinatal maternal antibiotic exposure influenced lung injury in a hyperoxia-based mouse model of bronchopulmonary dysplasia. We report that disruption of intestinal commensal colonization during the perinatal period promotes a more severe bronchopulmonary dysplasia phenotype characterized by increased mortality and pulmonary fibrosis. Mechanistically, metagenomic shifts were associated with decreased IL-22 expression in bronchoalveolar lavage and were independent of hyperoxia-induced inflammasome activation. Collectively, these results demonstrate a previously unrecognized influence of the gut-lung axis during the development of neonatal lung injury, which could be leveraged to ameliorate the most severe and persistent pulmonary complication of preterm birth.

Ginger and its bioactive component 6-shogaol mitigate lung inflammation in a murine asthma model.

Asthma, a common disorder associated with airway inflammation and hyperresponsiveness, remains a significant clinical burden in need of novel therapeutic strategies. Patients are increasingly seeking complementary and alternative medicine approaches to control their symptoms, including the use of natural products. Ginger, a natural product that we previously demonstrated acutely relaxes airway smooth muscle (ASM), has long been reported to possess anti-inflammatory properties, although a precise mechanistic understanding is lacking. In these studies, we demonstrate that chronic administration of whole ginger extract or 6-shogaol, a bioactive component of ginger, mitigates in vivo house dust mite antigen-mediated lung inflammation in mice. We further show that this decrease in inflammation is associated with reduced in vivo airway responsiveness. Utilizing in vitro studies, we demonstrate that 6-shogaol augments cAMP concentrations in CD4 cells, consistent with phosphodiesterase inhibition, and limits the induction of nuclear factor-κB signaling and the production of proinflammatory cytokines in activated CD4 cells. Sustained elevations in cAMP concentration are well known to inhibit effector T cell function. Interestingly, regulatory T cells (Tregs) utilize cAMP as a mediator of their immunosuppressive effects, and we demonstrate here that 6-shogaol augments the Treg polarization of naïve CD4 cells in vitro. Taken together with previous reports, these studies suggest that ginger and 6-shogaol have the potential to combat asthma via two mechanisms: acute ASM relaxation and chronic inhibition of inflammation.

Lipopolysaccharide induces steroid-resistant exacerbations in a mouse model of allergic airway disease collectively through IL-13 and pulmonary macrophage activation.

BACKGROUND: Acute exacerbations of asthma represent a major burden of disease and are often caused by respiratory infections. Viral infections are recognized as significant triggers of exacerbations; however, less is understood about the how microbial bioproducts such as the endotoxin (lipopolysaccharide (LPS)) trigger episodes. Indeed, increased levels of LPS have been linked to asthma onset, severity and steroid resistance. OBJECTIVE: The goal of this study was to identify mechanisms underlying bacterial-induced exacerbations by employing LPS as a surrogate for infection. METHODS: We developed a mouse model of LPS-induced exacerbation on the background of pre-existing type-2 allergic airway disease (AAD). RESULTS: LPS-induced exacerbation was characterized by steroid-resistant airway hyperresponsiveness (AHR) and an exaggerated inflammatory response distinguished by increased numbers of infiltrating neutrophils/macrophages and elevated production of lung inflammatory cytokines, including TNFα, IFNγ, IL-27 and MCP-1. Expression of the type-2 associated inflammatory factors such as IL-5 and IL-13 were elevated in AAD but not altered by LPS exposure. Furthermore, AHR and airway inflammation were no longer suppressed by corticosteroid (dexamethasone) treatment after LPS exposure. Depletion of pulmonary macrophages by administration of 2-chloroadenosine into the lungs suppressed AHR and reduced IL-13, TNFα and IFNγ expression. Blocking IL-13 function, through either IL-13-deficiency or administration of specific blocking antibodies, also suppressed AHR and airway inflammation. CONCLUSIONS & CLINICAL RELEVANCE: We present evidence that IL-13 and innate immune pathways (in particular pulmonary macrophages) contribute to LPS-induced exacerbation of pre-existing AAD and provide insight into the complex molecular processes potentially underlying microbial-induced exacerbations.

Intranasal epinephrine effects on epinephrine pharmacokinetics and heart rate in a nasal congestion canine model.

BACKGROUND: Histamine release and vasodilation during an allergic reaction can alter the pharmacokinetics of drugs administered via the intranasal (IN) route. The current study evaluated the effects of histamine-induced nasal congestion on epinephrine pharmacokinetics and heart rate changes after IN epinephrine. METHODS: Dogs received 5% histamine or saline IN followed by 4 mg epinephrine IN. Nasal restriction pressure, epinephrine concentration, and heart rate were assessed. Maximum concentration (Cmax), area under plasma concentration-time curve from 1 to 90 min (AUC1-90), and time to reach Cmax (Tmax) were measured. Clinical observations were documented. RESULTS: In the 12 dogs in this study, nasal congestion occurred at 5-10 min after IN histamine administration versus no nasal congestion after IN saline. After administration of IN epinephrine, IN histamine-mediated nasal congestion was significantly reduced to baseline levels at 60, 80, and 100 min. There were no significant differences in Cmax and AUC1-90 between histamine and saline groups after IN epinephrine delivery (3.5 vs 1.7 ng/mL, p = 0.06, and 117 vs 59 ng/mL*minutes, p = 0.09, respectively). After receiving IN epinephrine, the histamine group had a significantly lower Tmax versus the saline group (6 vs 70 min, respectively; p = 0.02). Following IN epinephrine administration, the histamine group showed rapidly increased heart rate at 5 min, while there was a delayed increase in heart rate (occurring 30-60 min after administration) in the saline group. Clinical observations included salivation and emesis. CONCLUSION: IN histamine led to more rapid epinephrine absorption and immediately increased heart rate compared with IN saline. IN epinephrine decreased histamine-induced nasal congestion.

Airway cholinergic history modifies mucus secretion properties to subsequent cholinergic challenge in diminished chloride and bicarbonate conditions.

NEW FINDINGS: What is the central question of this study? What is the impact of airway cholinergic history on the properties of airway mucus secretion in a cystic fibrosis-like environment? What is the main finding and its importance? Prior cholinergic challenge slightly modifies the characteristics of mucus secretion in response to a second cholinergic challenge in a diminished bicarbonate and chloride transport environment. Such modifications might lead to retention of mucus on the airway surface, thereby potentiating exacerbations of airway disease. ABSTRACT: Viral infections precipitate exacerbations in many airway diseases, including asthma and cystic fibrosis. Although viral infections increase cholinergic transmission, few studies have examined how cholinergic history modifies subsequent cholinergic responses in the airway. In our previous work, we found that airway resistance in response to a second cholinergic challenge was increased in young pigs with a history of airway cholinergic stimulation. Given that mucus secretion is regulated by the cholinergic nervous system and that abnormal airway mucus contributes to exacerbations of airway disease, we hypothesized that prior cholinergic challenge would also modify subsequent mucus responses to a secondary cholinergic challenge. Using our established cholinergic challenge-rechallenge model in pigs, we atomized the cholinergic agonist bethanechol or saline control to pig airways. Forty-eight hours later, we removed tracheas and measured mucus secretion properties in response to a second cholinergic stimulation. The second cholinergic stimulation was conducted in conditions of diminished chloride and bicarbonate transport to mimic a cystic fibrosis-like environment. In pigs previously challenged with bethanechol, a second cholinergic stimulation produced a mild increase in sheet-like mucus films; these films were scarcely observed in animals originally challenged with saline control. The subtle increase in mucus films was not associated with changes in mucociliary transport. These data suggest that prior cholinergic history might modify mucus secretion characteristics with subsequent stimulation in certain environmental conditions or disease states. Such modifications and/or more repetitive stimulation might lead to retention of mucus on the airway surface, thereby potentiating exacerbations of airway disease.

Eucalyptol reduces airway hyperresponsiveness in rats following cigarette smoke-exposed.

BACKGROUND: Cigarette smoke is the major cause of airway inflammatory disease, including airway hyperresponsiveness. Eucalyptol (EUC), also named 1.8-cineole, is a monoterpenoid found in essential oil of medicinal plants, showing several biological effects. HYPOTHESIS/PURPOSE: Based in the eucalyptol protective activity in respiratory diseases as asthma, our hypothesis is that eucalyptol is able to reduce the airway hyperresponsiveness and the respiratory mechanic parameters in rats exposed to cigarette smoke. STUDY DESIGN: Wistar rats were divided into control and cigarettes smoke (CS) groups. CS group was daily subjected to cigarette smoke and treated by inhalation for 15 min/day with EUC (1 mg/mL) or vehicle during 30 days. After treatment, bronchoalveolar lavage (BAL) was collected to analyze the inflammatory profile, and tracheal rings were isolated for evaluation of the airway smooth muscle hyperresponsiveness. Lung function was analyzed in vivo. METHODS: The inflammatory profile was evaluated by optical microscopy performing total (Neubauer chamber) and differential leukocyte count (smear slides stained in H&E). The hyperresponsiveness was evaluated in tracheal rings contracted with potassium chloride (KCl) carbamoylcholine (CCh), or Barium chloride (BaCl2) in presence or absence of nifedipine. The lung function (Newtonian resistance-RN) was evaluated by bronco stimulation with methacholine (MCh). RESULTS: BAL from CS group increased the influx of leukocyte, mainly neutrophils and macrophages compared to control group. EUC reduced by 71% this influx. The tracheal contractions induced by KCl, CCh or BaCl2 were reduced by EUC in 59%, 42% and 26%, respectively. The last one was not different of nifedipine activity. Newtonian resistance (RN) was also reduced in 37% by EUC compared to CS group. CONCLUSION: EUC reduces the hyperresponsiveness and the airway inflammatory profile, recovering the lung function.

Methacholine dose response curve and acceptability criteria of respiratory mechanics modeling.

Aim: This study aimed to analyze the Constant Phase Model (CPM) Coefficient of Determination (COD) and an index of harmonic distortion ([Formula: see text]) behavior in intravenous methacholine dose response curve. We studied the COD and [Formula: see text] behavior of Control and Lung Inflammation (OVA) groups of mice and we proposed an alternative for moments when the CPM should not be applied. Methods: 9-week female BALB/c mice were studied, 8 of the control group (23.11 ± 1.27 g) and 11 of the lung inflammation group (OVA) (21.45 ± 2.16 g). The COD values were obtained during the respiratory mechanics assessment via Forced Oscillation Technique (FOT) and the [Formula: see text] was estimated a posteriori. Both control and OVA groups were submitted to 4 doses of Methacholine (MCh) protocol. Results: A strong correlation between COD and [Formula: see text] was present at the last two doses (0.3 mg/kg: r = -0.75, p = 0.0013 and 1 mg/kg: r = -0.91; p < 0.0001) in the OVA group. Differences were found in doses of 0.3 mg/kg between control and OVA for the maximum values of Rn (Newtonian Resistance) and G (tissue viscous); and between groups at PBS and doses of 0.03, 0.1 and 0.3 mg/kg for H (Elastance). A similar behavior was observed for the analysis of Area Under the Curve with the exclusion of the 3 first measurements of each dose. However, in this scenario, the comparison with the maximum value presented a higher discriminatory capacity of the parameters associated with the parenchyma. Conclusions: During severe bronchoconstriction there is a strong negative correlation between model goodness of fit and nonlinearities levels, reinforcing that COD is a robust acceptance criterion, whether still simple and easily obtained from the ventilator. We also pointed out the area under the CPM parameters dose response curve is a useful and can be used as a complementary analysis to peak comparison following bolus injections of methacholine.

Effect of nintedanib on airway inflammation in a mouse model of acute asthma.

Objective: New treatments are needed for cases of asthma that are refractory to traditional therapies. In this study, we examined the effect of oral nintedanib, an intracellular inhibitor of tyrosine kinases, on airway hyper-responsiveness (AHR) and airway smooth muscle cells, using a mouse model of experimental asthma. Methods: Asthma was experimentally induced in mice via subcutaneous injection of ovalbumin (OVA). A group of saline-injected mice served as a control group. The OVA mice were then divided into four treatment groups according to the dose of nintedanib. AHR was examined via exposure to vaporized methacholine. Airway inflammation was assessed via bronchoalveolar lavage fluid (BALF) cell counts and Th2 cytokine concentrations. Results: Baseline levels of AHR and airway inflammation were higher in OVA mice than in the control group. Treatment with nintedanib lowered AHR, BALF cell counts and BALF cytokine levels in a dose-dependent fashion. The effect of nintedanib was comparable to that of dexamethasone. In particular, treatment with nintedanib lowered the expression of transforming growth factor-ß1 and inhibited the expression and phosphorylation of platelet-derived growth factor receptor-ß, vascular endothelial growth factor receptor 1 (VEGFR1), VEGFR2, fibroblast growth factor receptor 2 (FGFR2), FGFR3, and extracellular signal-regulated kinase. Conclusions: Nintedanib lowered AHR and the expression of factors associated with airway inflammation and remodeling in a mouse model of experimental asthma. Our results suggest that nintedanib may be useful in the treatment of asthma.

Comparison of multi-wall carbon nanotube and nitrogen-doped multi-wall carbon nanotube effects on lung function and airway reactivity in rats.

Incorporation of multi-wall carbon nanotubes (MWCNT) into materials has raised concerns about their potential hazards to manufacturing workers. In animal models, airway inflammation and lung fibrosis follow aspiration, instillation, and inhalation exposures to MWCNT. However, the effects of MWCNT on pulmonary function, airway reactivity and airway epithelium function following inhalation exposure has not been studied. We investigated whether inhaled MWCNT affects lung resistance (RL) and dynamic compliance (Cdyn), reactivity to inhaled methacholine (MCh), epithelial regulation of airway reactivity to MCh in vitro, and airway epithelial ion transport. Male rats were exposed by whole body inhalation for 6 h to air or aerosolized MWCNT (0.5, 1 or 5 mg/m3) for one or nine days. Eighteen h after 1 d exposure to 5 mg/m3 MWCNT, basal RL was increased and basal Cdyn was decreased; changes did not persist for 7 d. Reactivity to MCh (RL) was increased and Cdyn responses were decreased at 18 h, but not 7 d after exposure to 1 and 5 mg/m3 MWCNT. The effects of i.t.-instilled MWCNT and nitrogen-doped MWCNT (N-MWCNT) on pulmonary function and reactivity to MCh at doses comparable to deposition after inhalation of 5 mg/m3 at 1 d and 0.5, 1, and 5 mg/m3 MWCNT 9 d-exposures were compared. Both nanoparticles increased airway reactivity (RL); N-MWCNT did not affect Cdyn responses. Lung function and airway reactivity are altered following a single MWCNT inhalation and generally subside over time. Given i.t., MWCNT's and N-MWCNT's effects were comparable, but N-MWCNT evoke smaller changes in Cdyn responses.

Artesunate attenuates airway resistance in vivo and relaxes airway smooth muscle cells in vitro via bitter taste receptor-dependent calcium signalling.

NEW FINDINGS: What is the central question of this study? The aim of this study was to evaluate artesunate for its use as a bronchodilator in asthma treatment. What is the main finding and its importance? We found that artesunate reduces airway resistance in both normal and ovalbumin-treated Balb/c mice in vivo. Artesunate reduces traction force while inducing Ca2+ influx into cultured airway smooth muscle cells in vitro, most probably via the bitter taste receptor. These findings provide important evidence at both animal and cellular levels that artesunate might potentially be used as a bronchodilator for treating obstructive airway diseases, such as asthma. ABSTRACT: Following the surprising discovery that bitter taste receptors (TAS2Rs) expressed in the lung and can be stimulated to relax airway smooth muscle cells (ASMCs), there is great interest in searching for a bitter taste receptor agonist as a new bronchodilator for asthma therapy. Among the great many other natural bitter substances, artesunate is of special interest to be evaluated for this purpose because of its pharmacological value as a derivative from the well-known anti-malarial, artemisinin. Therefore, in this study we treated either normal or ovalbumin (OVA)-induced asthmatic Balb/c mice in vivo with artesunate (30, 60 or 120 µg) via aerosol inhalation. Subsequently, we measured the airway resistance of the mice in the presence or absence of artesunate. In addition, we treated either mouse or human ASMCs cultured in vitro with artesunate (0.25-2.0 mM) and then measured the traction force and [Ca2+ ]i flux of the cells in the presence or absence of artesunate. The results demonstrate that artesunate attenuated airway resistance in a dose-dependent manner in both the normal and the OVA-treated mice, but more potently in the latter. The in vivo efficacy of artesunate at 120 µg was comparable to that of the conventional bronchodilator, salbutamol, at 3 µg in terms of the reduction in airway resistance. Artesunate also reduced traction force and induced an increase in [Ca2+ ]i in the cultured ASMCs, which was mediated, at least in part, by TAS2R signalling in the human ASMCs. These results together suggest that artesunate might potentially be a cheap and safe bronchodilator to complement the current therapy of asthma.

Elucidating Mechanisms of Long-Term Gasoline Vehicle Exhaust Exposure-Induced Erectile Dysfunction in a Rat Model.

INTRODUCTION: Exposure to air pollution poses a risk for morbidity in multiple diseases. However, the role of ambient air pollutant emissions in public sexual health is just beginning to be understood and remains controversial. AIM: We have determined to elucidate the specific role of gasoline vehicle exhaust (VE), a crucial source and toxicant of air pollution, in the penile erectile function via a rat model. METHODS: 40 male Sprague Dawley rats, 12 weeks of age, were used in this experiment. Except for the control group (10 rats), rats were equally exposed to VE for total 2 hours, 4 hours, and 6 hours daily for 3 months consecutively. During each VE exposure periods, particulate matter (PM) mass concentrations of PM1, PM2.5, and PM10 were 1.43 ± 0.036, 1.45 ± 0.033, and 1.47 ± 0.037 mg/m3, respectively. MAIN OUTCOME MEASURE: Erectile function, pulmonary function, serum inflammatory factors, and histologic examinations of the lung and penile tissues were evaluated. RESULTS: Our study indicates that in vivo, 4-hour, and 6-hour daily exposure to VE causes significant reduction of erectile function, as judged by intracavernous pressure measurement. Meanwhile, we have observed that the 4-hour and 6-hour VE exposure rats exhibited remarkable increased levels of serum inflammatory factors, decreased total lung capacity and chord compliance, thickened alveoli septum, destroyed alveoli, pulmonary fibrosis, as well as down-regulation of the messenger RNA and protein expression of endothelial and neuronal nitric oxide synthase in the penile tissue when compared with normal control rats. CLINICAL IMPLICATIONS: We speculated that the underlying mechanisms of VE inducing erectile dysfunction could be attributed to systemic inflammation, pulmonary dysfunction, and the reduction of nitric oxide synthase activity in the corpus cavernosum. STRENGTH & LIMITATIONS: For the first time, our study revealed the deleterious effect of VE on penile erection in vivo. However, the VE exposure model might not entirely mimic the natural condition of ambient air pollution. CONCLUSION: Our results raise concerns about the potential role played by long-term exposure to gasoline VE in the development of erectile dysfunction. Zhao S, Wang J, Xie Q, et al. Elucidating Mechanisms of Long-Term Gasoline Vehicle Exhaust Exposure-Induced Erectile Dysfunction in a Rat Model. J Sex Med 2019;16:155-167.