New insights into risk factors of asthma

Skin prick reactivity among asthmatics in East Africa

Background

The burden of asthma in Africa is high, and yet the disease is not universally prioritised. Data on allergic asthma and its impact on asthma morbidity are limited in Africa. Our aim was to describe the distribution of skin prick positivity among asthmatics in Eastern Africa.

Methods

From August 2016 to May 2018, 1671 asthmatic patients were enrolled from Uganda, Kenya, and Ethiopia as part of the African Severe Asthma Program clinical study. Skin prick testing was performed at baseline using a panel of 12 allergens, and factors associated with skin prick reactivity determined.

Results

Of the 1, 671 patients recruited, 71% were female with a median age of 40 years, 93.6% were aged >15 years and the patterns of asthma symptom frequency was intermittent in 2.9%, mild persistent in 19.9%, moderate persistent in 42.6% and severe persistent in 34.6% at baseline. Self-reported triggers, were dust (92%), cold weather (89%), upper respiratory infections (84%), strong smells (79%) and exposure to tobacco (78%). The majority (90%) of the participants had at least 1 positive allergen reaction, with 0.9% participants reacting to all the 12 allergens. Participants commonly reacted to house dust mites (66%), Blomia tropicalis (62%), and the German cockroach (52%). Patients sensitized to more allergens (>2) had significantly reduced lung function (FEV ≤ 80%; p = 0.001) and were more likely to visit the emergency department due to asthma (p = 0.012). There was no significant relationship between number of allergens and measures of asthma control, quality of life, and other clinical outcomes. Only the country of origin was independently associated with atopy among African asthmatics.

Conclusion

There is a high prevalence of skin prick positivity among East African patients with asthma, with the commonest allergen being house dust mite. Skin reactivity did not correlate well with asthma severity and poor asthma control. The relation between atopy, measured through skin prick testing, and measures of asthma control among asthma patients in Eastern Africa is unclear and needs further study.

Trial registration

The ASAP study was registered prospectively. ClinicalTrials.gov Identifier: NCT03065920; Registration date: February 28, 2017; Last verified: February 28, 2017.

A Review of the Effects of Major Atmospheric Pollutants on Pollen Grains, Pollen Content, and Allergenicity

This review summarizes the available data related to the effects of air pollution on pollen grains from different plant species. Several studies carried out either on in situ harvested pollen or on pollen exposed in different places more or less polluted are presented and discussed. The different experimental procedures used to monitor the impact of pollution on pollen grains and on various produced external or internal subparticles are listed. Physicochemical and biological effects of artificial pollution (gaseous and particulate) on pollen from different plants, in different laboratory conditions, are considered. The effects of polluted pollen grains, subparticles, and derived aeroallergens in animal models, in in vitro cell culture, on healthy human and allergic patients are described. Combined effects of atmospheric pollutants and pollen grains-derived biological material on allergic population are specifically discussed. Within the notion of "polluen," some methodological biases are underlined and research tracks in this field are proposed.

Association between infection early in life and mental disorders among youth in the community: a cross-sectional study

BACKGROUND

The objective of this study was to examine the association between infection early in life and mental disorders among youth in the community.

METHODS

Data were drawn from the MECA (Methods in Epidemiology of Child and Adolescent psychopathology), a community-based study of 1,285 youth in the United States conducted in 1992. Multiple logistic regression analyses were used to investigate the association between parent/caregiver-reported infection early in life and DSM/DISC diagnoses of mental disorders at ages 9-17.

RESULTS

Infection early in life was associated with a significantly increased odds of major depression (OR = 3.9), social phobia (OR = 5.8), overanxious disorder (OR = 6.1), panic disorder (OR = 12.1), and oppositional defiant disorder (OR = 3.7).

CONCLUSIONS

These findings are consistent with and extend previous results by providing new evidence suggesting a link between infection early in life and increased risk of depression and anxiety disorders among youth. These results should be considered preliminary. Replication of these findings with longitudinal epidemiologic data is needed. Possible mechanisms are discussed.

Are frequent asthma symptoms among low-income individuals related to heavy traffic near homes, vulnerabilities, or both?

PURPOSE

To investigate whether frequent asthma symptoms (daily/weekly symptoms) can be attributed to traffic-related exposures, poverty, and/or vulnerabilities.

METHODS

Annual average daily vehicle traffic density (TD) within 500 feet of 2001 California Health Interview Survey respondents' residential cross streets was calculated. Logistic regression analyses were performed to evaluate the association between annual average TD and frequent asthma symptoms with income as a confounder and a modifier.

RESULTS

After adjustment for age, sex, and race/ethnicity, a 92% increase in frequent asthma symptoms was observed among those in high TD and a 50% increase among those in medium TD compared to those in low TD. Adjustment for poverty did not change these estimates, but individuals in poverty were twice more likely to experience frequent symptoms. Furthermore, delays in care, a poor/fair health status, current/previous smoking, overweight/obese, or unemployment showed independent associations with frequent asthma symptoms. Analyses stratified on income indicated greater estimated traffic effects for asthmatics in poverty, whereas the estimates for asthmatics above the poverty level moved closer toward the null.

CONCLUSIONS

Traffic-related exposures, poverty and vulnerabilities all increased the risk of frequent asthma symptoms. Those in poverty appeared to be more strongly affected by heavy traffic near their residences.

Localization of Per a 3 allergen in the gut and faecal pellets of the American cockroach (Periplaneta americana)

Cockroach-derived materials are known to be a major source of potent aeroallergens, causing allergic respiratory diseases such as asthma and allergic rhinitis. The aim of this study was to determine the localization of the major allergen, Per a 3 (Cr-PI), within the American cockroach (Periplaneta americana), which might reveal the relative importance of excreted materials and nonexcreted cockroach components as allergen sources. American cockroaches (P. americana) and their faecal pellets were embedded in paraffin, and serial sections were cut and collected on glass slides. After being stained with mouse polyclonal antiserum against Per a 3, the sections were incubated sequentially with biotin-labelled sheep antimouse immunoglobulin G (IgG) and a preformed fluorescent isothiocyanate (FITC)-avidin complex. Finally, the sections were mounted and examined under a fluorescent microscope. Examination of Per a 3 immunoreactivity on the sections of the American cockroaches (P. americana) revealed that the midgut mucosa, gut contents and faecal pellets were all strongly labelled. Per a 3 immunoreactive products were not detected in any other internal organs of the American cockroaches. These results suggest that Per a 3 allergen might be synthesized in and secreted from the epithelia of the midgut mucosa and excreted from the body in the faecal pellets.

Traffic and outdoor air pollution levels near residences and poorly controlled asthma in adults

BACKGROUND

Air pollution may exacerbate asthma.

OBJECTIVE

To investigate associations between traffic and outdoor air pollution levels near residences and poorly controlled asthma among adults diagnosed as having asthma in Los Angeles and San Diego counties, California.

METHODS

We estimated traffic density within 500 ft of 2001 California Health Interview Survey respondents' reported residential cross-street intersections. Additionally, we assigned annual average concentrations of ozone, nitrogen dioxide, particulate matter 2.5 and 10 micrometers or less in diameter, and carbon monoxide measured at government monitoring stations within a 5-mile radius of the reported residential cross-street intersections.

RESULTS

We observed a 2-fold increase in poorly controlled asthma (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.38-3.23) among asthmatic adults in the highest quintile of traffic density after adjusting for age, sex, race, and poverty. Similar increases were seen for nonelderly adults, men, and women, although associations seemed strongest in elderly adults (OR, 3.00; 95% CI, 1.13-7.91). Ozone exposures were associated with poorly controlled asthma among elderly adults (OR, 1.70; 95% CI, 0.91-3.18 per 1 pphm) and men (OR, 1.76; 95% CI, 1.05-2.94 per 1 pphm), whereas particulate matter 10 micrometers or less seemed to affect primarily women (OR, 2.06; 95% CI, 1.17-3.61), even at levels below the national air quality standard.

CONCLUSIONS

Heavy traffic and high air pollution levels near residences are associated with poorly controlled asthma.

Identification of the antigenic determinants of the American cockroach allergen Per a 1 by error-prone PCR

The group I allergen of cockroach is found in both American and German cockroaches, designated as Per a 1 and Bla g 1, respectively. Members of these allergens so far identified are composed of tandem repeats that may cause the high allergenicity of Per a 1 allergen. In this study, we used monoclonal antibodies HW-8 and HW-19, which can inhibit the binding of patient IgE to Per a 1 allergen, to define the structure of the antigenic determinants in Per a 1.0103 (designated C3), an isoallergen of Per a 1 allergen. Two recognition sites are present, one in the N-terminus (aa 1-208) and the other in the C-terminus (aa 208-395). The N-terminal epitope is not accessible to antibody molecules on the pET-expressed C3 protein. The C-terminal epitope was further localized to the aa 267-354 region (C3E) by colony immunoscreening of the cDNA epitope library. By negative screening of the mutated C3E expression library generated by error-prone PCR (ER-PCR), an approach which has rarely been applied in epitope mapping, the functional epitope was identified to lie in aa 318-337 with aa 323-331 being the core motif. The minimal region of the functional epitope was further delineated, by sequence alignment, to be D-x-[I, L]-A-[I, L]-L-P-V-D-E-[L, I]-x-A-[L, I], where x represents any amino acids. This motif is found in all Per a 1 allergens and may serve as a basis for designing a peptide vaccine for allergen-specific immunotherapy. To our knowledge, this is the first report for (1) detailed mapping of the cockroach allergens and (2) use of error-prone PCR random mutagenesis and negative selection in molecular allergology.

Asthmatic children and risk factors at a province in the southeast of Turkey

BACKGROUND

The prevalence of asthma appears to be on the increase and the risk factors are not well established. Environmental and demographic characteristics of asthmatic children were investigated to identify the risk factors accompanying asthma.

METHODS

140 asthmatic children aged at 3-15 years were compared with 96 age-matched control subjects admitted to the paediatric outpatient clinics of Dicle University Hospital. Information about the children were obtained from parents and patients'charts.

RESULTS

Patients with asthma were most frequently admitted in May-June and November-January months. Association of the disease with allergic rhinitis was found in 84 children (60 %), allergic conjunctivitis in 63 (45 %), atopic dermatitis in 29 (21 %) and gastrointestinal symptoms in 18 (13 %). Mean age of the cases was 6.8 3.3 and 6.9 3.2 years (p > 0.05); male to female ratios were 91/49 and 43/53 (p = 0.002) in the study and control groups, respectively. There were significant differences at number of cases stated to have any symptoms induced by air pollution (25.6 %, 3.1 %, p < 0,001), exercise (47.5 %, 4.2 %, p < 0.001) and cold exposure (33 %, 15.6 %, p = 0.03), but not by damp, dust, indoor smoking, foods, drugs, and animal contact (p > 0.05) between the study and the control groups, respectively. Family history of atopy was 66 % and 8.4 %, (p < 0.001) in the study and control groups, respectively. Family crowding index, duration of breast feeding, parental education and number of consanguineous married parents were not different between both groups. History of upper respiratory tract infections were more frequent in asthmatic children than controls. Children with an earlier age of onset (</= 5 years) in the study group was more frequently associated with allergic rhinitis in comparison with the asthmatic children with an age of onset > 5 years.

CONCLUSIONS

Many risk factors, both individual and environmental are associated with asthmatic children in Diyarbakr. Among many risk factors that aggrevating asthma in children in Diyarbakr, air pollution, cold exposure and upper respiratory infections are preventable.

Sequence analysis of the first complete cDNA clone encoding an American cockroach Per a 1 allergen

C3, designated as Per a 1.0103 according to WHO/IUIS nomenclature, encoding a novel American cockroach allergen of 395 aa (44.6 kDa), is the first complete cDNA clone with a translatable immunoreactive protein among the reported group 1 cockroach allergens. Its deduced amino acid sequence possesses a signal sequence, phosphorylation sites, mitochondrial energy transfer protein signatures, and four repeats each sharing striking similarity with the corresponding repeats of the other cockroach allergens. The latter similarity suggests that the group 1 cockroach allergens might have evolved from a primordial mitochondrial sequence by exon duplication.

The relative importance of socio-economic status, parental smoking and air pollution (SO2) on asthma symptoms, spirometry and bronchodilator response in 11-year-old children

The aim of this study was to evaluate the relative contribution of several risk factors to the prevalence of allergic respiratory symptoms, and the positivity of the bronchodilator test with fenoterol, and to establish the relative importance of these factors on the variability of FVC, FEV1, PEF, MEF25, MEF50 and MEF75. A total of 340 11-year-old children attending school in polluted and non-polluted areas of the city of Cartagena, Spain, were studied. The polluted area had had an annual mean of 75 microg/m3 of SO2 over the last 10 years and the non-polluted area had < 20 microg/m3 during this period. A questionnaire about allergic respiratory symptoms was completed by the parents. Specific questions about parental smoking habits and socio-economic level were included. Each child's performance in spirometry before and after administration of 0.2 mg of inhaled fenoterol was evaluated. The only significant predictive variables in the logistic regression (for suffering any symptom or a positive bronchodilator response) were male sex for nasal symptoms (RR 1.37; p = 0.04) and housing near heavy traffic for eye symptoms (RR 1.45; p = 0.01). Living in the polluted area reduced the risk of a positive bronchodilator response (RR 0.61; p = 0.004). Maternal smoking, even though not statistically significant, tended to increased the risk of suffering any symptom (RR 1.26; p = 0.07) or of having a positive bronchodilator response (RR 1.23; p = 0.1). None of the risk factors studied was of significant importance in explaining the variability of spirometry results. Although none of the risk factors were specifically determinant to the symptom questions, bronchodilator test or spirometric measurements, having a mother who smokes seems more important than living in a polluted area if statistically non-significant trends are considered.