Maternal high-fat diet increases airway sensory innervation and reflex bronchoconstriction in adult offspring.

Children born to obese mothers are prone to develop asthma and airway hyperresponsiveness, but the mechanisms behind this are unclear. Here we developed a mouse model of maternal diet-induced obesity that recapitulates metabolic abnormalities seen in humans born to obese mothers. Offspring of dams fed a high-fat diet (HFD) showed increased adiposity, hyperinsulinemia, and insulin resistance at 16 wk of age despite being fed only a regular diet (RD). Bronchoconstriction induced by inhaled 5-hydroxytriptamine was also significantly increased in offspring of HFD-fed versus RD-fed dams. Increased bronchoconstriction was blocked by vagotomy, indicating this reflex was mediated by airway nerves. Three-dimensional (3-D) confocal imaging of tracheas collected from 16-wk-old offspring showed that both epithelial sensory innervation and substance P expression were increased in the offspring of HFD-fed dams compared with offspring of RD-fed dams. For the first time, we show that maternal high-fat diet increases airway sensory innervation in offspring, leading to reflex airway hyperresponsiveness.NEW & NOTEWORTHY Our study reveals a novel potential mechanism, by which maternal high-fat diet increases the risk and severity of asthma in offspring. We found that exposure to maternal high-fat diet in mice leads to hyperinnervation of airway sensory nerves and increased reflex bronchoconstriction in offspring fed a regular diet only. These findings have important clinical implications and provide new insights into the pathophysiology of asthma, highlighting the need for preventive strategies in this patient population.

The cumulative effect of methacholine on large and small airways when deep inspirations are avoided.

BACKGROUND AND OBJECTIVE: The effect of serial incremental concentrations of methacholine is only slightly cumulative when assessed by spirometry. This limited cumulative effect may be attributed to the bronchodilator effect of deep inspirations that are required between concentrations to measure lung function. Using oscillometry, the response to methacholine can be measured without deep inspirations. Conveniently, oscillometry can also dissociate the contribution of large versus small airways. Herein, oscillometry was used to assess the cumulative effect of methacholine in the absence of deep inspirations on large and small airways. METHODS: Healthy and asthmatic volunteers underwent a multiple-concentration methacholine challenge on visit 1 and a single-concentration challenge on visit 2 using the highest concentration of visit 1. The maximal response was compared between visits to assess the cumulative effect of methacholine. The lung volume was also measured after the final concentration to assess hyperinflation. RESULTS: In both healthy and asthmatic subjects, increases in resistance at 19 Hz (Rrs19 ), reflecting large airway narrowing, did not differ between the multiple- and the single-concentration challenge. However, increases in resistance at 5 Hz (Rrs5 ) minus Rrs19 , reflecting small airway narrowing, were 117 and 270% greater in the multiple- than the single-concentration challenge in healthy (p = 0.006) and asthmatic (p < 0.0001) subjects, respectively. Hyperinflation occurred with both challenges and was greater in the multiple- than the single-concentration challenge in both groups. CONCLUSION: Without deep inspirations, the effect of methacholine is cumulative on small airways but not on large airways. Lung hyperinflation and derecruitment may partially explain these different responses.

Effects of airway smooth muscle contraction and inflammation on lung tissue compliance.

There are renewed interests in using the parameter K of Salazar-Knowles' equation to assess lung tissue compliance. K either decreases or increases when the lung's parenchyma stiffens or loosens, respectively. However, whether K is affected by other common features of respiratory diseases, such as inflammation and airway smooth muscle (ASM) contraction, is unknown. Herein, male C57BL/6 mice were treated intranasally with either saline or lipopolysaccharide (LPS) at 1 mg/kg to induce pulmonary inflammation. They were then subjected to either a multiple or a single-dose challenge with methacholine to activate ASM to different degrees. A quasi-static pressure-driven partial pressure-volume (P-V) maneuver was performed before and after methacholine. The Salazar-Knowles' equation was then fitted to the deflation limb of the P-V loop to obtain K, as well as the parameter A, an estimate of lung volume (inspiratory capacity). The fitted curve was also used to derive the quasi-static elastance (Est) at 5 cmH2O. The results demonstrate that LPS and both methacholine challenges increased Est. LPS also decreased A, but did not affect K. In contradistinction, methacholine decreased both A and K in the multiple-dose challenge, whereas it decreased K but not A in the single-dose challenge. These results suggest that LPS increases Est by reducing the open lung volume (A) and without affecting tissue compliance (K), whereas methacholine increases Est by decreasing tissue compliance with or without affecting lung volume. We conclude that lung tissue compliance, assessed using the parameter K of Salazar-Knowles' equation, is insensitive to inflammation but sensitive to ASM contraction.

Clinical analysis of the "small plateau" sign on the flow-volume curve followed by deep learning automated recognition.

BACKGROUND: Small plateau (SP) on the flow-volume curve was found in parts of patients with suspected asthma or upper airway abnormalities, but it lacks clear scientific proof. Therefore, we aimed to characterize its clinical features. METHODS: We involved patients by reviewing the bronchoprovocation test (BPT) and bronchodilator test (BDT) completed between October 2017 and October 2020 to assess the characteristics of the sign. Patients who underwent laryngoscopy were assigned to perform spirometry to analyze the relationship of the sign and upper airway abnormalities. SP-Network was developed to recognition of the sign using flow-volume curves. RESULTS: Of 13,661 BPTs and 8,168 BDTs completed, we labeled 2,123 (15.5%) and 219 (2.7%) patients with the sign, respectively. Among them, there were 1,782 (83.9%) with the negative-BPT and 194 (88.6%) with the negative-BDT. Patients with SP sign had higher median FVC and FEV1% predicted (both P < .0001). Of 48 patients (16 with and 32 without the sign) who performed laryngoscopy and spirometry, the rate of laryngoscopy-diagnosis upper airway abnormalities in patients with the sign (63%) was higher than those without the sign (31%) (P = 0.038). SP-Network achieved an accuracy of 95.2% in the task of automatic recognition of the sign. CONCLUSIONS: SP sign is featured on the flow-volume curve and recognized by the SP-Network model. Patients with the sign are less likely to have airway hyperresponsiveness, automatic visualizing of this sign is helpful for primary care centers where BPT cannot available.

Sex Differences in the Impact of Dietary Fiber on Pulmonary Responses to Ozone.

Ozone causes airway hyperresponsiveness, a defining feature of asthma. We have reported that the gut microbiome contributes to sex differences in ozone-induced airway hyperresponsiveness. Altering dietary fiber affects the gut microbiome. The purpose of this study was to determine the effects of dietary fiber on pulmonary responses to ozone and whether these effects differ by sex. We fed male and female mice fiber-free diets or diets enriched in one of two types of dietary fiber, cellulose and pectin, for 3 days before ozone exposure. Compared with control diets or pectin-enriched diets, cellulose-enriched diets attenuated ozone-induced airway hyperresponsiveness in male but not female mice. In contrast, fiber-free diets augmented responses to ozone in female but not male mice. Analysis of 16S rRNA sequencing of fecal DNA also indicated sex differences in the impact of dietary fiber on the gut microbiome and identified bacterial taxa that were associated with ozone-induced airway hyperresponsiveness. Our data suggest that microbiome-based therapies such as prebiotics may provide an alternative therapeutic strategy for air pollution-triggered asthma, but they indicate that such therapeutics may need to be tailored differently for males and females.

DM-induced Hypermethylation of IR and IGF1R attenuates mast cell activation and airway responsiveness in rats.

Diabetes has been reported to modulate the airway smooth muscle reactivity and lead to attenuation of allergic inflammatory response in the lungs. In this study, we aimed to study the effect of insulin on cell activation and airway responsiveness in patients with diabetes mellitus (DM). The airway contraction in rat model groups including a non-DM group, a non-DM+INDUCTION group, a DM+INDUCTION group and a DM+INDUCTION+INSULIN group was measured to observe the effect of insulin on airway responsiveness. Radioenzymatic assay was conducted to measure the levels of histamine, and ELISA assay was conducted to measure bronchial levels of interleukin (IL)-1b, tumour necrosis factor (TNF)-a, cytokine-induced neutrophil chemoattractant (CINC)-1, P-selectin and ß-hexosaminidase. The tension in the main and intrapulmonary bronchi of DM+INDUCTION rats was lower than that of the non-DM+INDUCTION rats, whereas the treatment of insulin partly restored the normal airway responsiveness to OA in DM rats. The release of histamine was remarkably suppressed in DM+INDUCTION rats but was recovered by the insulin treatment. Also, OA significantly increased the levels of IL-1b, TNF-a, CINC-1 and P-selectin in non-DM rats, whereas insulin treatment in DM+INDUCTION rats partly restored the normal levels of IL-1b, TNF-a, CINC-1 and P-selectin in DM rats. Moreover, the expression of IR and IGF1R was evidently suppressed in DM rats, with the methylation of both IR and IGF1R promoters was aggravated in DM rats. Therefore, we demonstrated that DM-induced hypermethylation inhibited mast cell activation and airway responsiveness, which could be reversed by insulin treatment.

IL-33, diet-induced obesity, and pulmonary responses to ozone.

BACKGROUND: Obesity augments pulmonary responses to ozone. We have reported that IL-33 contributes to these effects of obesity in db/db mice. The purpose of this study was to determine whether IL-33 also contributes to obesity-related changes in the response to ozone in mice with diet-induced obesity. METHODS: Male wildtype C57BL/6 mice and mice deficient in ST2, the IL-33 receptor, were placed on chow or high fat diets for 12 weeks from weaning. Because the microbiome has been implicated in obesity-related changes in the pulmonary response to ozone, mice were either housed with other mice of the same genotype (same housed) or with mice of the opposite genotype (cohoused). Cohousing transfers the gut microbiome from one mouse to its cagemates. RESULTS: Diet-induced increases in body mass were not affected by ST2 deficiency or cohousing. In same housed mice, ST2 deficiency reduced ozone-induced airway hyperresponsiveness and neutrophil recruitment in chow-fed but not HFD-fed mice even though ST2 deficiency reduced bronchoalveolar lavage IL-5 in both diet groups. In chow-fed mice, cohousing abolished ST2-related reductions in ozone-induced airway hyperresponsiveness and neutrophil recruitment, but in HFD-fed mice, no effect of cohousing on these responses to ozone was observed. In chow-fed mice, ST2 deficiency and cohousing caused changes in the gut microbiome. High fat diet-feeding caused marked changes in the gut microbiome and overrode both ST2-related and cohousing-related differences in the gut microbiome observed in chow-fed mice. CONCLUSION: Our data indicate a role for IL-33 in pulmonary responses to ozone in chow-fed but not high fat diet-fed mice and are consistent with the hypothesis that these diet-related differences in the role of IL-33 are the result of changes in the gut microbiome.

Lung volume dependence of respiratory function in rodent models of diabetes mellitus.

BACKGROUND: Diabetes mellitus causes the deterioration of smooth muscle cells and interstitial matrix proteins, including collagen. Collagen and smooth muscle cells are abundant in the lungs, but the effect of diabetes on airway function and viscoelastic respiratory tissue mechanics has not been characterized. This study investigated the impact of diabetes on respiratory function, bronchial responsiveness, and gas exchange parameters. METHODS: Rats were allocated randomly to three groups: a model of type 1 diabetes that received a high dose of streptozotocin (DM1, n = 13); a model of type 2 diabetes that received a low dose of streptozotocin with a high-fat diet (DM2, n = 14); and a control group with no treatment (C, n = 14). Forced oscillations were applied to assess airway resistance (Raw), respiratory tissue damping (G), and elastance (H). The arterial partial pressure of oxygen to the inspired oxygen fraction (PaO2/FiO2) and intrapulmonary shunt fraction (Qs/Qt) were determined from blood gas samples at positive end-expiratory pressures (PEEPs) of 0, 3, and 6 cmH2O. Lung responsiveness to methacholine was also assessed. Collagen fibers in lung tissue were quantified by histology. RESULTS: The rats in groups DM1 and DM2 exhibited elevated Raw, G, H, and Qs/Qt, compromised PaO2/FiO2, and diminished airway responsiveness. The severity of adverse tissue mechanical change correlated with excessive lung collagen expression. Increased PEEP normalized the respiratory mechanics, but the gas exchange abnormalities remained. CONCLUSIONS: These findings indicate that diabetes reduces airway and lung tissue viscoelasticity, resulting in alveolar collapsibility that can be compensated by increasing PEEP. Diabetes also induces persistent alveolo-capillary dysfunction and abnormal adaptation ability of the airways to exogenous constrictor stimuli.

Determinants of response to bronchodilator in patients with cough variant asthma- A randomized, single-blinded, placebo-controlled study.

BACKGROUND: Not all patients with cough variant asthma (CVA) show responsiveness to bronchodilators (RB) in clinic. Whether there are specific clinical and pathophysiological features can indicate RB in patients with CVA needs further investigation. Thus, we aimed to investigate the RB in patients with CVA and associated factors. METHODS: Forty-two CVA patients were randomized in a 2:1 ratio to receive oral bambuterol hydrochloride (10 mg, once daily, for 3 days) or matched placebo, 36 patients (24 with bronchodilator and 12 with placebo) completed the study eventually. RB was considered when cough visual analogue scale (VAS) score decreased 30% or more after 3 days treatment. The baseline clinical and pathophysiological characteristics between patients with RB and patients without RB were compared. CRS was presented with the lowest concentration of capsaicin inducing at least 5 coughing (C5). RESULTS: The responsive rate of patients with bronchodilator was significantly higher than that with placebo (62.5% vs 16.7%, p < 0.01). Patients with RB showed a significant greater mean decline of FEV1% predicted after bronchial provocation (26.7% vs 22.4%, p < 0.05) and higher geometric mean of sputum eosinophils (1.37 vs 0.69, p < 0.05) as compared with these without RB. No significant differences in sputum neutrophil, Log C5 were found between patients with RB and patients without RB. There was a moderate correlation between the decline of FEV1% pred and RB (rs = 0.443, p < 0.05). The regression analysis showed that nocturnal cough was a predictor of RB (OR, 7.33, 95% CI: 1.11-48.26, p = 0.038). No adverse events were reported by all of the patients after the study. CONCLUSION: More than one-third of patients with CVA do not respond to bronchodilator treatment, indicating that the response to bronchodilator should not be a diagnostic requirement of CVA. CVA patients with higher airway responsiveness will more likely respond to bronchodilator. Cough of CVA might be elicited by different mechanisms, which suggests that CVA could be divided into two phenotypes according to the response to bronchodilators.

Limonene-induced activation of A2A adenosine receptors reduces airway inflammation and reactivity in a mouse model of asthma.

Animal models of asthma have shown that limonene, a naturally occurring terpene in citrus fruits, can reduce inflammation and airway reactivity. However, the mechanism of these effects is unknown. We first performed computational and molecular docking analyses that showed limonene could bind to both A2A and A2B receptors. The pharmacological studies were carried out with A2A adenosine receptor knock-out (A2AKO) and wild-type (WT) mice using ovalbumin (OVA) to generate the asthma phenotype. We investigated the effects of limonene on lung inflammation and airway responsiveness to methacholine (MCh) and NECA (nonselective adenosine analog) by administering limonene as an inhalation prior to OVA aerosol challenges in one group of allergic mice for both WT and KO. In whole-body plethysmography studies, we observed that airway responsiveness to MCh in WT SEN group was significantly lowered upon limonene treatment but no effect was observed in A2AKO. Limonene also attenuated NECA-induced airway responsiveness in WT allergic mice with no effect being observed in A2AKO groups. Differential BAL analysis showed that limonene reduced levels of eosinophils in allergic WT mice but not in A2AKO. However, limonene reduced neutrophils in sensitized A2AKO mice, suggesting that it may activate A2B receptors as well. These data indicate that limonene-induced reduction in airway inflammation and airway reactivity occurs mainly via activation of A2AAR but A2B receptors may also play a supporting role.

Biseugenol Exhibited Anti-Inflammatory and Anti-Asthmatic Effects in an Asthma Mouse Model of Mixed-Granulocytic Asthma.

In the present work, the anti-inflammatory and antiasthmatic potential of biseugenol, isolated as the main component from n-hexane extract from leaves of Nectandra leucantha and chemically prepared using oxidative coupling from eugenol, was evaluated in an experimental model of mixed-granulocytic asthma. Initially, in silico studies of biseugenol showed good predictions for drug-likeness, with adherence to Lipinski's rules of five (RO5), good Absorption, Distribution, Metabolism and Excretion (ADME) properties and no alerts for Pan-Assay Interference Compounds (PAINS), indicating adequate adherence to perform in vivo assays. Biseugenol (20 mg·kg-1) was thus administered intraperitoneally (four days of treatment) and resulted in a significant reduction in both eosinophils and neutrophils of bronchoalveolar lavage fluid in ovalbumin-sensitized mice with no statistical difference from dexamethasone (5 mg·kg-1). As for lung function parameters, biseugenol (20 mg·kg-1) significantly reduced airway and tissue damping in comparison to ovalbumin group, with similar efficacy to positive control dexamethasone. Airway hyperresponsiveness to intravenous methacholine was reduced with biseugenol but was inferior to dexamethasone in higher doses. In conclusion, biseugenol displayed antiasthmatic effects, as observed through the reduction of inflammation and airway hyperresponsiveness, with similar effects to dexamethasone, on mixed-granulocytic ovalbumin-sensitized mice.

Microbiota Contribute to Obesity-related Increases in the Pulmonary Response to Ozone.

Obesity is a risk factor for asthma, especially nonatopic asthma, and attenuates the efficacy of standard asthma therapeutics. Obesity also augments pulmonary responses to ozone, a nonatopic asthma trigger. The purpose of this study was to determine whether obesity-related alterations in gut microbiota contribute to these augmented responses to ozone. Ozone-induced increases in airway responsiveness, a canonical feature of asthma, were greater in obese db/db mice than in lean wild-type control mice. Depletion of gut microbiota with a cocktail of antibiotics attenuated obesity-related increases in the response to ozone, indicating a role for microbiota. Moreover, ozone-induced airway hyperresponsiveness was greater in germ-free mice that had been reconstituted with colonic contents of db/db than in wild-type mice. In addition, compared with dietary supplementation with the nonfermentable fiber cellulose, dietary supplementation with the fermentable fiber pectin attenuated obesity-related increases in the pulmonary response to ozone, likely by reducing ozone-induced release of IL-17A. Our data indicate a role for microbiota in obesity-related increases in the response to an asthma trigger and suggest that microbiome-based therapies such as prebiotics may provide an alternative therapeutic strategy for obese patients with asthma.

Sex Differences in Pulmonary Responses to Ozone in Mice. Role of the Microbiome.

We have previously reported that the mouse gut microbiome contributes to pulmonary responses to ozone, a common asthma trigger, and that short-chain fatty acids, end products of bacterial fermentation, likely contribute to this role of the microbiome. A growing body of evidence indicates that there are sex-related differences in gut microbiota and these differences can have important functional consequences. The purpose of this study was to determine whether there are sex-related differences in the impact of the gut microbiota on pulmonary responses to ozone. After acute exposure to ozone, male mice developed greater airway hyperresponsiveness than female mice. This difference was abolished after antibiotic ablation of the gut microbiome. Moreover, weanling female pups housed in cages conditioned by adult male mice developed greater ozone-induced airway hyperresponsiveness than weanling female pups raised in cages conditioned by adult females. Finally, ad libitum oral administration via drinking water of the short-chain fatty acid propionate resulted in augmented ozone-induced airway hyperresponsiveness in male, but not female, mice. Overall, these data are consistent with the hypothesis that the microbiome contributes to sex differences in ozone-induced airway hyperresponsiveness, likely as a result of sex differences in the response to short-chain fatty acids.

The interleukin-33 receptor contributes to pulmonary responses to ozone in male mice: role of the microbiome.

BACKGROUND: Interleukin-33 is released in the airways following acute ozone exposure and has the ability to cause airway hyperresponsiveness, a defining feature of asthma. Ozone causes greater airway hyperresponsiveness in male than female mice. Moreover, sex differences in the gut microbiome account for sex differences in this response to ozone. The purpose of this study was to determine whether there were sex differences in the role of interleukin-33 in ozone-induced airway hyperresponsiveness and to examine the role of the microbiome in these events. METHODS: Wildtype mice and mice genetically deficient in ST2, the interleukin-33 receptor, were housed from weaning with either other mice of the same genotype and sex, or with mice of the same sex but opposite genotype. At 15 weeks of age, fecal pellets were harvested for 16S rRNA sequencing and the mice were then exposed to air or ozone. Airway responsiveness was measured and a bronchoalveolar lavage was performed 24 h after exposure. RESULTS: In same-housed mice, ozone-induced airway hyperresponsiveness was greater in male than female wildtype mice. ST2 deficiency reduced ozone-induced airway hyperresponsiveness in male but not female mice and abolished sex differences in the response to ozone. However, sex differences in the role of interleukin-33 were unrelated to type 2 cytokine release: ozone-induced increases in bronchoalveolar lavage interleukin-5 were greater in females than males and ST2 deficiency virtually abolished interleukin-5 in both sexes. Since gut microbiota contribute to sex differences in ozone-induced airway hyperresponsiveness, we examined the role of the microbiome in these ST2-dependent sex differences. To do so, we cohoused wildtype and ST2 deficient mice, a situation that allows for transfer of microbiota among cage-mates. Cohousing altered the gut microbial community structure, as indicated by 16S rRNA gene sequencing of fecal DNA and reversed the effect of ST2 deficiency on pulmonary responses to ozone in male mice. CONCLUSIONS: The data indicate that the interleukin-33 /ST2 pathway contributes to ozone-induced airway hyperresponsiveness in male mice and suggest that the role of interleukin-33 is mediated at the level of the gut microbiome.

Effect of omega-3 fatty acid supplementation on resolvin (RvE1)-mediated suppression of inflammation in a mouse model of asthma.

Objective: ResolvinE1 (RvE1), an endogenous lipid mediator derived from omega 3 fatty acids contributes to resolution of allergic inflammatory responses. We investigated effects of RvE1 (R) and omega 3 fatty acids (O) on airway reactivity and inflammation using allergic mice. Methods: Mice were divided into control (nonasthmatic; CON) and allergen sensitized-challenged (asthmatic; SEN) groups, and were sensitized i.p. on days 1, 6 with 0.2 µg ovalbumin (OVA) followed by 5% OVA aerosol challenges on days 11-13. RvE1 was administered i.p. postallergen challenge, while omega 3 fatty acids (fish oil) were administered via oral gavage once daily (days 1-13). Whole body plethysmography and bronchoalveolar lavage (BAL) studies were performed on day 14. Results: RvE1 attenuated airway responsiveness to methacholine (48 mg/ml) in treated asthmatic mice vs. nontreated (150 ± 27.88% in SEN vs. 54 ± 7.52% in SEN + R, p < .05). No difference was observed with omega-3 supplementation (115 ± 19.28% in SEN + O) or treatment with both RvE1 and omega 3 fatty acids (39 ± 12.37% in SEN + R + O vs. 54 ± 7.52% in SEN + R). Differential BAL cell analysis showed that RvE1 decreased eosinophils and neutrophils in SEN mice (p < .005) while no difference was observed with omega-3 fatty acids. SEN + R + O group had similar results as RvE1 treated mice, suggesting that only RvE1 attenuated inflammation. Conclusions: RvE1 attenuated airway responsiveness and inflammation in asthmatic mice. Omega-3 fatty acids, although a precursor for RvE1 formation, had no additive effects on RvE1 decreases in airway inflammation and airway reactivity. Our data suggests that omega-3 supplementation has little effect on airway inflammation and reactivity in our model of asthma.

The Microbiome Regulates Pulmonary Responses to Ozone in Mice.

Previous reports demonstrate that the microbiome impacts allergic airway responses, including airway hyperresponsiveness, a characteristic feature of asthma. Here we examined the role of the microbiome in pulmonary responses to a nonallergic asthma trigger, ozone. We depleted the microbiota of conventional mice with either a single antibiotic (ampicillin, metronidazole, neomycin, or vancomycin) or a cocktail of all four antibiotics given via the drinking water. Mice were then exposed to room air or ozone. In air-exposed mice, airway responsiveness did not differ between antibiotic- and control water-treated mice. Ozone caused airway hyperresponsiveness, the magnitude of which was decreased in antibiotic cocktail-treated mice versus water-treated mice. Except for neomycin, single antibiotics had effects similar to those observed with the cocktail. Compared with conventional mice, germ-free mice also had attenuated airway responsiveness after ozone. 16S ribosomal RNA gene sequencing of fecal DNA to characterize the gut microbiome indicated that bacterial genera that were decreased in mice with reduced ozone-induced airway hyperresponsiveness after antibiotic treatment were short-chain fatty acid producers. Serum analysis indicated reduced concentrations of the short-chain fatty acid propionate in cocktail-treated mice but not in neomycin-treated mice. Dietary enrichment with pectin, which increased serum short-chain fatty acids, also augmented ozone-induced airway hyperresponsiveness. Furthermore, propionate supplementation of the drinking water augmented ozone-induced airway hyperresponsiveness in conventional mice. Our data indicate that the microbiome contributes to ozone-induced airway hyperresponsiveness, likely via its ability to produce short-chain fatty acids.

Foetal growth restriction in mice modifies postnatal airway responsiveness in an age and sex-dependent manner.

Epidemiological studies demonstrate an association between intrauterine growth restriction (IUGR) and asthma; however the underlying mechanism is unknown. We investigated the impact of maternal hypoxia-induced IUGR on airway responsiveness in male and female mice during juvenility and adulthood. Pregnant BALB/c mice were housed under hypoxic conditions for gestational days 11-17.5 and then returned to normoxic conditions for the remainder of pregnancy. A control group was housed under normoxic conditions throughout pregnancy. Offspring were studied at 2 weeks (juveniles) and 8 weeks (adults), where lung volume was assessed by plethysmography, airway responsiveness to methacholine determined by the forced oscillation technique and lungs fixed for morphometry. IUGR offspring were lighter at birth, exhibited "catch-up growth" by 2 weeks, but were again lighter in adulthood. IUGR males were "hyper-responsive" at 2 weeks and "hypo-responsive" as adults, in contrast with IUGR females who were hyper-responsive in adulthood. IUGR males had increased inner and total wall thickness at 2 weeks which resolved by adulthood, while airways in IUGR females were structurally normal throughout life. There were no differences in lung volume between Control and IUGR offspring at any age. Our data demonstrate changes in airway responsiveness as a result of IUGR that could influence susceptibility to asthma development and contribute to sexual dimorphism in asthma prevalence which switches from a male dominated disease in early life to a female dominated disease in adulthood.

Predictive Value of the New Zealand Secretion Scale (NZSS) for Pneumonia.

Accumulated pharyngo-laryngeal secretions have been associated with aspiration and pneumonia. While traditional secretion scales evaluate location and amount, the eight-point New Zealand Secretion Scale (NZSS) uniquely encompasses a responsiveness subcomponent. This prospective observational study investigated the predictive value of NZSS for aspiration and pneumonia. Consecutive inpatients (N:180) referred for flexible endoscopic evaluation of swallowing (FEES) were recruited (neurological 49%, critical care 31%, structural 15%, other 5% etiologies). Mean age was 63 years (range 18-95 years, S.D. 18). A standardized protocol was completed on 264 FEES (180 first FEES, 84 repeat FEES). Penetration-aspiration scale (PAS) (ICC = .89) and NZSS (ICC = .91) were independently scored by two raters. Aspiration of food and/or fluids occurred in 36% of FEES; 24% silently. Median NZSS was 3 (range 0-7); with silent aspiration of secretions in 33% of FEES. There was a significant correlation between NZSS and PAS (R = .37, p < .001). Incidence of pneumonia during admission was 46% and was significantly associated with PAS (p < .001), NZSS (p < .001), age (p < .001), and tracheostomy (p < .001). Of those who developed pneumonia, 33% had both high PAS (>5) and high NZSS (>4). Eleven percent of those who developed pneumonia had an elevated NZSS (>4) in the absence of aspiration (PAS < 6). This large study reports the significant relationship between accumulated secretions, airway responsiveness, and pneumonia. This comprehensive scale is a useful tool when carrying out endoscopic evaluation and has the potential to predict pneumonia in patients irrespective of their aspiration status.

Definition and diagnosis of asthma-COPD overlap (ACO).

It is now widely recognized that asthma and COPD can coexist as asthma-COPD overlap (ACO), but the preliminary attempts at providing universal guidelines for the diagnosis of ACO still need to be improved. We believe that a case can be made for devising guidelines for the diagnosis of this increasingly common disease that are specific to Japan. In this paper, we present our consensus-based description of ACO which we believe is realistic for use in our country. In addition, we cite the scientific evidence for our own "objective" features used to develop the criteria for COPD and asthma diagnosis. We acknowledge that they will need to be validated and updated over time, but hope the results will encourage further research on the characteristics and treatment of this commonly encountered clinical problem.

Spleen tyrosine kinase inhibition blocks airway constriction and protects from Th2-induced airway inflammation and remodeling.

BACKGROUND: Spleen tyrosine kinase (Syk) is an intracellular nonreceptor tyrosine kinase, which has been implicated as central immune modulator promoting allergic airway inflammation. Syk inhibition has been proposed as a new therapeutic approach in asthma. However, the direct effects of Syk inhibition on airway constriction independent of allergen sensitization remain elusive. METHODS: Spectral confocal microscopy of human and murine lung tissue was performed to localize Syk expression. The effects of prophylactic or therapeutic Syk inhibition on allergic airway inflammation, hyperresponsiveness, and airway remodeling were analyzed in allergen-sensitized and airway-challenged mice. The effects of Syk inhibitors BAY 61-3606 or BI 1002494 on airway function were investigated in isolated lungs of wild-type, PKCα-deficient, mast cell-deficient, or eNOS-deficient mice. RESULTS: Spleen tyrosine kinase expression was found in human and murine airway smooth muscle cells. Syk inhibition reduced allergic airway inflammation, airway hyperresponsiveness, and pulmonary collagen deposition. In naïve mice, Syk inhibition diminished airway responsiveness independently of mast cells, or PKCα or eNOS expression and rapidly reversed established bronchoconstriction independently of NO. Simultaneous inhibition of Syk and PKC revealed additive dilatory effects, whereas combined inhibition of Syk and rho kinase or Syk and p38 MAPK did not cause additive bronchodilation. CONCLUSIONS: Spleen tyrosine kinase inhibition directly attenuates airway smooth muscle cell contraction independent of its protective immunomodulatory effects on allergic airway inflammation, hyperresponsiveness, and airway remodeling. Syk mediates bronchoconstriction in a NO-independent manner, presumably via rho kinase and p38 MAPK, and Syk inhibition might present a promising therapeutic approach in chronic asthma as well as acute asthma attacks.