Neurokinin A is the predominant tachykinin in human bronchoalveolar lavage fluid in normal and asthmatic subjects

BACKGROUND—Multiple sensory neuropeptides are present in human airways and may contribute to diseases such as asthma. This study quantified and characterised substance P (SP), neurokinin A (NKA), and calcitonin gene related peptide (CGRP) immunoreactivity in bronchoalveolar lavage fluid in asthmatic and normal subjects.
METHODS—Using specific radioimmunoassay (RIA), SP, NKA and CGRP were measured in bronchoalveolar lavage fluid from asthmatic subjects (n = 5), normal subjects (n = 5), atopic non-asthmatic subjects (n = 6), and asthmatic subjects four hours after allergen challenge (n = 12). Peptide immunoreactivity was characterised using high performance liquid chromatography (HPLC) and RIA.
RESULTS—No SP or CGRP immunoreactivity was detected in any of the fractions from samples after extraction, HPLC, and RIA. Non-specific binding resulted in spurious SP immunoreactivity being detected in bronchoalveolar lavage fluid when no extraction process was employed. NKA was detected in significant amounts in asthmatic (median 550, range 425-625 pg/ml) and normal subjects (median 725, range 350-1425 pg/ml). The level of NKA was significantly higher in the asthmatic subjects after allergen challenge (median 750, range 350-1250 pg/ml) than in unchallenged asthmatic subjects (median 600, range 425-600 pg/ml, p<0.01).
CONCLUSIONS—Extraction and characterisation of peptides from bronchoalveolar lavage fluid must be performed to ensure that the measured immunoreactivity represents target peptide. NKA is present in bronchoalveolar lavage fluid in high concentrations and is the predominant tachykinin. The concentrations of NKA are similar in normal subjects and subjects with mild asthma.

Histamine release from bronchoalveolar lavage cells from asthmatic subjects after allergen challenge and relationship to the late asthmatic response

Background


Metachromatic cells obtained from asthmatic subjects demonstrate increased spontaneous and stimulated histamine release in vitro. Their ability to synthesize and store proinflammatory cytokines has focused renewed interest on their role in asthma.


Objective: The late asthmatic response provides a useful model of clinical asthma. The aim of the study was to examine metachromatic cell derived mediators and histamine releasability in vitro after in vivo allergen exposure in atopic subjects with and without asthma and relate them to the type of physiological response observed.

Methods: Bronchoalveolar lavage (BAL) cells were obtained 4 h after challenge from asthmatics exhibiting a single early response (EAR, n = 5), a dual response (LAR, n = 7), unchallenged (basal, n = 5), atopic non-asthmatic (ANA, n = 6) and non-atopic non-asthmatics (normal, n = 5). BAL histamine and tryptase concentrations and in vitro histamine release (HR) after stimulation with anti-IgE, allergen, A23187, conconavalin A and substance P were compared.

Results:Metachromatic cell numbers were lower in normal controls compared with all asthmatic groups and in LAR compared with EAR. Metachromatic cell derived mediators were higher in asthmatic compared with normal subjects. Spontaneous HR in LAR (20.5 ± 5.0%) was lower than EAR (29.5 ± 3.9%) and ANA (30.2 ± 1.4%) (P < 0.05). No differences were seen in stimulated HR between EAR and LAR. HR in ANA stimulated with anti-IgE was greater than LAR (P < 0.05). HR in ANA stimulated with anti-IgE was greater than LAR (P < 0.05). After stimulation with ionophore A23187 (1 μM), release was greater in LAR compared with basal (P < 0.05) and no different at 5 μM. All subject groups responded to substance P (SP) but was significantly more in the asthmatic subjects compared to normal controls (P < 0.05). Allergen challenge did not modify the response of asthmatic subjects to SP.

Conclusion: Functional differences in metachromatic cell reactivity are present in atopic subjects 4 h after in vivo allergen exposure which relate to the physiological response observed after this time and suggest that there is ongoing metachromatic cell degranulation subjects who subsequently develop LAR.

Meal-induced 24-hour profile of circulating glycated insulin in type 2 diabetic subjects measured by a novel radioimmunoassay

Increasing evidence supports a role for glycated insulin in the insulin-resistant state of type 2 diabetes. We measured 24-hour profiles of plasma glycated insulin, using a novel radioimmunoassay (RIA), to evaluate the effects of meal stimulation and intermittent fasting on circulating concentrations of plasma glycated insulin in type 2 diabetes. Patients (n = 6; hemoglobin A(1c) [HbA(1c)], 7.2% +/- 0.6%; fasting plasma glucose, 7.4 +/- 0.7 mmol/L; body mass index [BMI], 35.7 +/- 3.5 kg/m(2); age, 56.3 +/- 4.4 years) were admitted for 24 hours and received a standardized meal regimen. Half-hourly venous samples were taken for plasma glycated insulin, glucose, insulin, and C-peptide concentrations between 8 Am and midnight and 2-hourly overnight. The mean plasma glycated insulin concentration over 24 hours was 27.8 +/- 1.2 pmol/L with a mean ratio of insulin:glycated insulin of 11:1. Circulating glucose, insulin, C-peptide, and glycated insulin followed a basal and meal-related pattern with most prominent increments following breakfast, lunch, and evening meal, respectively. The mean concentrations of glycated insulin during the morning, afternoon, evening, and night-time periods were 24.4 +/- 2.5, 28.7 +/- 2.3, 31.1 +/- 2.1, and 26.2 +/- 1.5 pmol/L, respectively, giving significantly higher molar ratios of insulin:glycated insulin of 18.0:1, 14.2:1, and 12.7:1 compared with 7.01 at night (P

Dietary intake of fruits and vegetables improves microvascular function in hypertensive subjects in a dose-dependent manner

Background— Observational evidence has consistently linked increased fruit and vegetable consumption with reduced cardiovascular morbidity; however, there is little direct trial evidence to support the concept that fruit and vegetable consumption improves vascular function. This study assessed the dose-dependent effects of a fruit and vegetable intervention on arterial health in subjects with hypertension.

Methods and Results— After a 4-week run-in period during which fruit and vegetable intake was limited to 1 portion per day, participants were randomized to consume either 1, 3, or 6 portions daily for the next 8 weeks. Endothelium-dependent and -independent arterial vasodilator responses were assessed by venous occlusion plethysmography in the brachial circulation before and after intervention. Compliance was monitored with serial contemporaneous 4-day food records and by measuring concentrations of circulating dietary biomarkers. A total of 117 volunteers completed the 12-week study. Participants in the 1-, 3-, and 6-portions/d groups reported consuming on average 1.1, 3.2, and 5.6 portions of fruit and vegetables, respectively, and serum concentrations of lutein and ß-cryptoxanthin increased across the groups in a dose-dependent manner. For each 1-portion increase in reported fruit and vegetable consumption, there was a 6.2% improvement in forearm blood flow responses to intra-arterial administration of the endothelium-dependent vasodilator acetylcholine (P=0.03). There was no association between increased fruit and vegetable consumption and vasodilator responses to sodium nitroprusside, an endothelium-independent vasodilator.

Conclusions— The present study illustrates that among hypertensive volunteers, increased fruit and vegetable consumption produces significant improvements in an established marker of endothelial function and cardiovascular prognosis.