The effect of submucosal edema on airways resistance

Respiratory problems in children with esophageal atresia and tracheoesophageal fistula

Background

Children with congenital esophageal atresia (EA) and tracheoesophageal fistula (TEF) have chronic respiratory symptoms including recurrent pneumonia, wheezing and persistent cough. The aim of this study is to describe the clinical findings of a large group of children with EA and TEF surgically corrected and the instrumental investigation to which they have undergone in order to better understand the patient’s needs and harmonize the care.

Methods

A retrospective data collection was performed on 105 children with EA and TEF followed at Department of Pediatric Medicine of Bambino Gesù Children’s Hospital (Rome, Italy) between 2010 and 2015.

Results

69/105 (66%) children reported lower respiratory symptoms with a mean age onset of 2.2 ± 2.5 years and only 63/69 (91%) performed specialist assessment at Respiratory Unit. Recurrent pneumonia (33%) and wheezing (31%) were the most reported symptoms. The first respiratory evaluation was performed after surgically correction of gastroesophageal reflux (GER) at mean age of 3.9 ± 4.2 years. Twenty nine patients have undergone to chest CT with contrast enhancement detecting localized atelectasis (41%), residual tracheal diverticulum (34%), bronchiectasis (31%), tracheal vascular compression (21%), tracheomalacia (17%) and esophageal diverticulum (14%). Fifty three patients have undergone to airways endoscopy detecting tracheomalacia (66%), residual tracheal diverticulum (26%), recurrent tracheoesophageal fistula (19%) and vocal cord paralysis (11%).

Conclusions

Our study confirms that respiratory symptoms often complicate EA and TEF; their persistence despite medical and surgical treatment of GER means that other etiological hypothesis must be examined and that a complete respiratory diagnostic work up must be considered.

Lung-homing of endothelial progenitor cells and airway vascularization is only partially dependant on eosinophils in a house dust mite-exposed mouse model of allergic asthma

Background

Asthmatic responses involve a systemic component where activation of the bone marrow leads to mobilization and lung-homing of progenitor cells. This traffic may be driven by stromal cell derived factor-1 (SDF-1), a potent progenitor chemoattractant. We have previously shown that airway angiogenesis, an early remodeling event, can be inhibited by preventing the migration of endothelial progenitor cells (EPC) to the lungs. Given intranasally, AMD3100, a CXCR4 antagonist that inhibits SDF-1 mediated effects, attenuated allergen-induced lung-homing of EPC, vascularization of pulmonary tissue, airway eosinophilia and development of airway hyperresponsiveness. Since SDF-1 is also an eosinophil chemoattractant, we investigated, using a transgenic eosinophil deficient mouse strain (PHIL) whether EPC lung accumulation and lung vascularization in allergic airway responses is dependent on eosinophilic inflammation.

Methods

Wild-type (WT) BALB/c and eosinophil deficient (PHIL) mice were sensitized to house dust mite (HDM) using a chronic exposure protocol and treated with AMD3100 to modulate SDF-1 stimulated progenitor traffic. Following HDM challenge, lung-extracted EPCs were enumerated along with airway inflammation, microvessel density (MVD) and airway methacholine responsiveness (AHR).

Results

Following Ag sensitization, both WT and PHIL mice exhibited HDM-induced increase in airway inflammation, EPC lung-accumulation, lung angiogenesis and AHR. Treatment with AMD3100 significantly attenuated outcome measures in both groups of mice. Significantly lower levels of EPC and a trend for lower vascularization were detected in PHIL versus WT mice.

Conclusions

This study shows that while allergen-induced lung-homing of endothelial progenitor cells, increased tissue vascularization and development lung dysfunction can occur in the absence of eosinophils, the presence of these cells worsens the pathology of the allergic response.

The effect of obesity degree on childhood pulmonary function tests

BACKGROUND

Childhood obesity has become a global epidemic. It is related to several chronic diseases such as essential hypertension, type 2 diabetes mellitus, and renal disease. The relationship between the degree of obesity and lung functions is well defined in adults, but limited information is available about the childhood period.

AIMS

This study aims to determine the impact of the degree of obesity on the pulmonary functions of school children and adolescents.

STUDY DESIGN

Cross sectional study.

METHODS

Included in the study were a total of 170 school children and adolescents (9-17 years old) referred to our paediatric outpatient clinic. Of these subjects, 42 were lean and non-obese (BMI % <85), 30 subjects were overweight (BMI % >85, <95), 34 subjects were obese (BMI % >95, <97), and 64 subjects were morbidly obese (BMI % >97). Anthropometric measurements were taken and spirometry was performed on all subjects. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced vital capacity 25-75 (FEV25-75) and peak expiratory flow (PEF) were used to measure the ventilatory functions for all the subjects.

RESULTS

The groups showed no significant differences in age or gender. Despite no statistically significant differences in FEV1, FVC, or FEV1/FVC, there were significant reductions in PEF (p<0.001) and FEV25-75 (p<0.001) in the overweight, obese and morbidly obese subjects, when compared with those who were non-obese.

CONCLUSION

Overweight, obese and morbidly obese children have no obstructive abnormalities compared with healthy lean subjects.

Inhibition of substance P-induced microvascular leakage by inhaled methoxamine in rat airways

1. The effect of the inhaled alpha-adrenoceptor agonist, methoxamine (MTX), was studied on experimental airway oedema induced by injection of substance P (SP) in the rat. Sprague-Dawley rats (300-350 g) were anaesthetized with sodium thiopentone, tracheotomized and artificially ventilated. 2. MTX or its vehicle was administered by inhalation. Airway resistance and blood pressure were monitored continuously. Evans Blue dye (EB, 20 mg kg-1) was injected through a jugular catheter 1 min before SP (14.8 nmol kg-1). Airways were dissected out, weighed and placed in formamide for EB extraction and determination by spectrophotometry. 3. EB extravasation induced by SP was significantly reduced in distal intraparenchymal bronchi by inhaled MTX at doses of 50 micrograms kg-1 (58 +/- 9 vs 96 +/- 9 ng EB mg-1 tissue after vehicle, P < 0.001) and 100 micrograms kg-1 (69 +/- 11 vs 137 +/- 26 ng EB mg-1 tissue after vehicle, P < 0.01). Inhaled MTX by itself (100 micrograms kg-1) increased blood pressure: 172 +/- 6 vs 132 +/- 10 mmHg baseline (P < 0.02), but neither induced extravasation nor increased airway resistance. 4. In another set of experiments without SP, MTX was administered intravenously 1 min after EB. At 100 micrograms kg-1, i.v. MTX increased blood pressure to a similar extent as inhaled MTX (180 vs 147 mmHg baseline, P < 0.01), increased airway resistance and caused leakage of plasma proteins in distal intraparenchymal bronchi (79 +/- 7 vs 47 +/- 1 ng EB mg-1 tissue, P < 0.02). 5 Similarly, after sequential i.v. injections of doubling doses of MTX (50-800 microg kg-1), a marked EB extravasation was found in the airways. This was abrogated by pretreatment with prazosin (100 microg kg-1)but not with propranolol (2 mg kg-1).6 These results suggest that microvascular leakage and airway oedema induced by i.v. MTX may be linked to an increase in pressure in the pulmonary circulation, resulting from vasoconstriction of the pulmonary vasculature and acute cardiac dysfunction due to systemic hypertension.7 Our results with inhaled MTX show that direct deposition of MTX at the bronchial vasculature induces a reduction in SP-induced microvascular leakage in rat airways and that inhaled MTX does not share the untoward effect of i.v. MTX inducing airway oedema.

Pharmacological modulation of inhaled sodium metabisulphite-induced airway microvascular leakage and bronchoconstriction in the guinea-pig

1. We have investigated the effects of chlorpheniramine, atropine and capsaicin pretreatment on inhaled sodium metabisulphite (MBS)-induced airway microvascular leakage and bronchoconstriction in anaesthetized guinea-pigs in order to clarify the mechanisms involved in these responses. The effects of frusemide and nedocromil sodium were also examined. 2. Lung resistance (RL) was measured for 6 min after inhalation of MBS (20, 40, 80 and 200 mM; 30 breaths), followed by measurement of extravasation of Evans blue dye into airway tissues, used as an index of airway microvascular leakage. MBS caused an increase in RL and leakage of dye at all airway levels in a dose-dependent manner. 3. Chlorpheniramine (10 mg kg-1, i.v.), atropine (1 mg kg-1, i.v.), their combination or inhaled nedocromil sodium (10 mg ml-1, 7 min) had no effect against the airway microvascular leakage induced by 80 mM MBS (30 breaths). Capsaicin pretreatment (50 mg kg-1, s.c.) caused a significant decrease in the leakage of dye in the main bronchi and inhaled frusemide (10 mg ml-1, 7 min) also in the main bronchi and proximal intrapulmonary airway. 4. Chlorpheniramine, atropine, their combination, capsaicin pretreatment and frusemide, but not nedocromil sodium, inhibited significantly the peak RL induced by 80 mM MBS (30 breaths) by approximately 50%. 5. We conclude that a cholinergic reflex and neuropeptides released from sensory nerve endings may participate in the mechanisms of MBS-induced airway responses. Frusemide but not nedocromil sodium may have an inhibitor effect on these neural mechanisms. The inhibitory effect of nedocromil sodium against lower doses of MBS is not excluded.

Mechanisms of platelet activating factor-induced changes in sheep tracheal blood flow

1. The effects of platelet activating factor (PAF) have been studied on the cervical tracheal vasculature and smooth muscle of anaesthetized sheep. 2. The predominant action of PAF (2 pmol-2nmol) was a dose-dependent fall in tracheal vascular resistance. The maximum fall in resistance was -41.6% (-38.5 to -44.7%, 95% confidence interval) and the ED50 was 17 pmol (12-28 pmol). Lyso-PAF (200 pmol) did not change vascular resistance. 3. PAF had no effect on tracheal smooth muscle tone assessed by measuring changes in the external diameter of the trachea. 4. The fall in vascular resistance produced with PAF was unaffected by the anti-asthma drug nedocromil sodium (1 mg, i.a.), the cyclo-oxygenase inhibitor indomethacin (5 mg kg-1, i.v.), the leukotriene receptor antagonist FPL55712 (2 mg kg-1, i.v.), or a combination of the histamine H1- and H2-antagonists mepyramine (2 mg kg-1, i.v.) with cimetidine (5 mg kg-1, i.v.). The PAF antagonist WEB 2086 (300 micrograms kg-1, i.v.) significantly reduced the vasodilatation produced by PAF (before, -40.8 +/- 4.2%; after -16.5 +/- 5.9%, P less than 0.05). 5. Thus in this model, PAF is a potent vasodilator of the tracheal circulation but has no action on tracheal smooth muscle. The vasodilatation is mediated by specific PAF receptors and is not due to the release of prostanoids, leukotrienes or histamine.

Bradykinin-induced plasma exudation in guinea-pig airways: involvement of platelet activating factor

1. We studied the effect of bradykinin on plasma exudation in the airways of the anaesthetized guinea-pig in vivo. Tissue content of extravasated Evans blue dye was used as an index of protein exudation in the larynx, trachea, main bronchi and intrapulmonary airways (i.p.a.). 2. Bradykinin increased the content of Evans blue in all tissues studied in a dose-related manner. The response was greatest in the main bronchi and i.p.a., less in the trachea and least in the larynx. A dose of 47 nmol kg-1 was the lowest tested which caused significant (P less than 0.001) plasma exudation with increases in leakage above control values of 256% in the larynx, 405% in the trachea, 394% in the main bronchi and 485% in intrapulmonary airways. 3. Leakage was significantly (P less than 0.05) increased above control values by 1 min after bradykinin (47 nmol kg-1) in the main bronchi and intrapulmonary airways and was maximal in all airways 5 min after bradykinin. Although reduced by 15 min, the tissue content of dye was still significantly (P less than 0.05) increased 2 h after bradykinin. 4. The prolonged tissue dye retention was due to a later phase of slow and maintained exudation preventing full clearance of dye after the initial response. 5. The initial phase of leakage was partially attenuated by the platelet activating factor (PAF) receptor antagonists WEB 2086 or BN 52021, by indomethacin or by inhibiting sensory nerve activation by opioid anaesthesia: it was not affected by mepyramine and cimetidine nor by the sulphidopeptide leukotriene receptor antagonists FPL 55712 or ICI 198,615. Adrenoceptor blockade of the anti-leakage effects of endogenously-released catecholamines significantly (P < 0.05) enhanced leakage. 6. The later phase of plasma leakage was completely inhibited by the PAF antagonists. 7. We conclude that, in guinea-pig airways in vivo, the initial phase of bradykinin-induced plasma exudation is mediated in part by PAF, sensory nerves and prostaglandins, whereas the later, prolonged phase of leakage is mediated exclusively by PAF. If bradykinin is generated in asthma, its potent and prolonged effects on plasma leakage may contribute significantly to airway oedema and may be involved in the development of bronchial hyperresponsiveness.

Importance of beta 2-adrenoceptor stimulation in the suppression of intradermal antigen challenge by adrenaline

1. Seven atopic subjects received two injections of antigen and one of saline intradermally in the back on each of 4 separate days. They were pretreated with four different drug combinations: (a) adrenaline 0.3 mg subcutaneously over the deltoid muscle (b) subcutaneous adrenaline preceded by 5 mg of the specific beta 2-adrenoceptor antagonist ICI 118,551 orally (c) 8 mg of salbutamol orally (d) placebo. Tablets were given 2 h before and subcutaneous injections 15 min before the intradermal injections of saline and antigen. 2. The median flare response to intradermal low dose antigen and high dose antigen after pretreatment with adrenaline was 4% and 49% of the response seen following pretreatment with placebo (P less than 0.001). When adrenaline was preceded by ICI-118,551, the corresponding median flare responses were 2% and 44% (P less than 0.001) of the placebo response. The flare response after pretreatment with salbutamol was not significantly different from placebo. 3. Adrenaline suppressed the median weal response to the higher dose of antigen to 52% of the response after pretreatment with placebo (P less than 0.05). This suppression by adrenaline was blocked by pretreatment with ICI 118,551. The median weal response after the highest dose of antigen was suppressed by salbutamol to 66% of the response seen after placebo, although this was not significant even when a further three subjects were studied with either salbutamol or placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nedocromil sodium on airway microvascular leakage and neural reflexes

Microvascular leakage and neurogenic mechanisms may be important components of the inflammatory response in asthmatic airways. We have examined the effects of nedocromil sodium on these responses. In guinea-pig airway, microvascular leakage induced by allergen was significantly inhibited by prior treatment with nedocromil sodium (100 micrograms/kg IV), but this had no effect on histamine-induced leakage and reduced PAF-induced leakage only at a dosage of 5 mg/kg. This suggests that nedocromil sodium acts mainly by preventing the release of inflammatory mediators. Both sulphur dioxide (SO2) and bradykinin cause bronchoconstriction in asthmatic patients, which is likely to be due to a neural mechanism since SO2 activates C-fibre sensory nerve endings in airways. Inhaled nedocromil sodium is effective in inhibiting both SO2- and bradykinin-induced bronchoconstriction, and furthermore reduces the sensation of dyspnoea, indicating a possible action on sensory nerve endings in airways.