Bronchial reactivity, atopy, and airway response to cotton dust

Asthma, allergy and vitamin E: Current and future perspectives

Asthma and allergic disease result from interactions of environmental exposures and genetics. Vitamin E is one environmental factor that can modify development of allergy early in life and modify responses to allergen after allergen sensitization. Seemingly varied outcomes from vitamin E are consistent with the differential functions of the isoforms of vitamin E. Mechanistic studies demonstrate that the vitamin E isoforms α-tocopherol and γ-tocopherol have opposite functions in regulation of allergic inflammation and development of allergic disease, with α-tocopherol having anti-inflammatory functions and γ-tocopherol having pro-inflammatory functions in allergy and asthma. Moreover, global differences in prevalence of asthma by country may be a result, at least in part, of differences in consumption of these two isoforms of tocopherols. It is critical in clinical and animal studies that measurements of the isoforms of tocopherols be determined in vehicles for the treatments, and in the plasma and/or tissues before and after intervention. As allergic inflammation is modifiable by tocopherol isoforms, differential regulation by tocopherol isoforms provide a foundation for development of interventions to improve lung function in disease and raise the possibility of early life dietary interventions to limit the development of lung disease.

Oxidative Stress: Harms and Benefits for Human Health

Oxidative stress is a phenomenon caused by an imbalance between production and accumulation of oxygen reactive species (ROS) in cells and tissues and the ability of a biological system to detoxify these reactive products. ROS can play, and in fact they do it, several physiological roles (i.e., cell signaling), and they are normally generated as by-products of oxygen metabolism; despite this, environmental stressors (i.e., UV, ionizing radiations, pollutants, and heavy metals) and xenobiotics (i.e., antiblastic drugs) contribute to greatly increase ROS production, therefore causing the imbalance that leads to cell and tissue damage (oxidative stress). Several antioxidants have been exploited in recent years for their actual or supposed beneficial effect against oxidative stress, such as vitamin E, flavonoids, and polyphenols. While we tend to describe oxidative stress just as harmful for human body, it is true as well that it is exploited as a therapeutic approach to treat clinical conditions such as cancer, with a certain degree of clinical success. In this review, we will describe the most recent findings in the oxidative stress field, highlighting both its bad and good sides for human health.

Vitamin E: Emerging aspects and new directions

The discovery of vitamin E will have its 100th anniversary in 2022, but we still have more questions than answers regarding the biological functions and the essentiality of vitamin E for human health. Discovered as a factor essential for rat fertility and soon after characterized for its properties of fat-soluble antioxidant, vitamin E was identified to have signaling and gene regulation effects in the 1980s. In the same years the cytochrome P-450 dependent metabolism of vitamin E was characterized and a first series of studies on short-chain carboxyethyl metabolites in the 1990s paved the way to the hypothesis of a biological role for this metabolism alternative to vitamin E catabolism. In the last decade other physiological metabolites of vitamin E have been identified, such as α-tocopheryl phosphate and the long-chain metabolites formed by the ω-hydroxylase activity of cytochrome P-450. Recent findings are consistent with gene regulation and homeostatic roles of these metabolites in different experimental models, such as inflammatory, neuronal and hepatic cells, and in vivo in animal models of acute inflammation. Molecular mechanisms underlying these responses are under investigation in several laboratories and side-glances to research on other fat soluble vitamins may help to move faster in this direction. Other emerging aspects presented in this review paper include novel insights on the mechanisms of reduction of the cardiovascular risk, immunomodulation and antiallergic effects, neuroprotection properties in models of glutamate excitotoxicity and spino-cerebellar damage, hepatoprotection and prevention of liver toxicity by different causes and even therapeutic applications in non-alcoholic steatohepatitis. We here discuss these topics with the aim of stimulating the interest of the scientific community and further research activities that may help to celebrate this anniversary of vitamin E with an in-depth knowledge of its action as vitamin.

Vitamin E and D regulation of allergic asthma immunopathogenesis

Asthma occurs as complex interactions of the environmental and genetics. Clinical studies and animal models of asthma indicate dietary factors such as vitamin E and vitamin D as protective for asthma risk. In this review, we discuss opposing regulatory functions of tocopherol isoforms of vitamin E and regulatory functions of vitamin D in asthma and how the variation in global prevalence of asthma may be explained, at least in part, by these dietary components.

The vitamin E isoforms α-tocopherol and γ-tocopherol have opposite associations with spirometric parameters: the CARDIA study

Background

Clinical studies of the associations of vitamin E with lung function have reported conflicting results. However, these reports primarily examine the α-tocopherol isoform of vitamin E and have not included the isoform γ-tocopherol which we recently demonstrated in vitro opposes the function of α-tocopherol. We previously demonstrated, in vitro and in animal studies, that the vitamin E isoform α-tocopherol protects, but the isoform γ-tocopherol promotes lung inflammation and airway hyperresponsiveness.

Methods

To translate these findings to humans, we conducted analysis of 4526 adults in the Coronary Artery Risk Development in Young Adults (CARDIA) multi-center cohort with available spirometry and tocopherol data in blacks and whites. Spirometry was obtained at years 0, 5, 10, and 20 and serum tocopherol was from years 0, 7 and 15 of CARDIA.

Results

In cross-sectional regression analysis at year 0, higher γ-tocopherol associated with lower FEV₁ (p = 0.03 in blacks and p = 0.01 in all participants) and FVC (p = 0.01 in blacks, p = 0.05 in whites, and p = 0.005 in all participants), whereas higher α-tocopherol associated with higher FVC (p = 0.04 in blacks and whites and p = 0.01 in all participants). In the lowest quartile of α-tocopherol, higher γ-tocopherol associated with a lower FEV₁ (p = 0.05 in blacks and p = 0.02 in all participants). In contrast, in the lowest quartile of γ-tocopherol, higher α-tocopherol associated with a higher FEV₁ (p = 0.03) in blacks. Serum γ-tocopherol >10 μM was associated with a 175–545 ml lower FEV₁ and FVC at ages 21–55 years.

Conclusion

Increasing serum concentrations of γ-tocopherol were associated with lower FEV1 or FVC, whereas increasing serum concentrations of α-tocopherol was associated with higher FEV1 or FVC. Based on the prevalence of serum γ-tocopherol >10 μM in adults in CARDIA and the adult U.S. population in the 2011 census, we expect that the lower FEV₁ and FVC at these concentrations of serum γ-tocopherol occur in up to 4.5 million adults in the population.

Cotton dust lung diseases

PURPOSE OF REVIEW

Although, in the industrialized world, there is a significant decline in the prevalence of cotton dust lung diseases, studies show an increasing incidence in the developing world. With rapid industrialization of the developing world, cotton dust-induced lung diseases are poised to become a global health problem. Discovery of other vegetable dusts causing similar conditions and appreciation of a wider variety of clinical features also make this an opportune time to review this topic.

RECENT FINDINGS

In addition to chronic exposure-related byssinosis and less common forms of acute byssinosis, recent reports describe the rare occurrence of cotton dust-induced pulmonary fibrosis. New data also relate long-term cotton dust exposure to symptoms and physiologic changes of chronic obstructive pulmonary disease. There have also been new developments relating the pathogenesis of cotton dust airway disease to endotoxin lipopolysaccharide found in cotton dust and bract extracts.

SUMMARY

Establishment of an association between prolonged exposure to cotton and other vegetable dusts and symptoms of chronic obstructive pulmonary disease widens the clinical implication of cotton dust exposure. In addition, accumulating knowledge of endotoxins will bring about promising new developments reshaping industrial safety standards and measures to prevent cotton dust exposure.

Endotoxin and occupational airway disease

PURPOSE OF REVIEW

This review provides an update on the role of bacterial endotoxin in occupational airway disease, a problem of importance from diagnostic and preventive points of view.

RECENT FINDINGS

Data from human inhalation studies have increased our understanding of the cell mechanisms underlying diseases related to endotoxin exposure. In addition, knowledge from molecular genetics may help us to identify individuals at risk. Several investigations have demonstrated that, apart from endotoxin, other microbial cell wall agents are also related to the risk for symptoms of occupational lung diseases, with pathogenic mechanisms different to those caused by endotoxin. Diagnostic methods have progressed from traditional lung function measurements to sampling of indicators of inflammation in the blood, nasal lavage and induced sputum. Investigations of a longitudinal design have provided important findings on the relationship between acute and chronic effects as well as exposures of risk and risk factors among individuals.

SUMMARY

Endotoxin, as well as other agents derived from microbes, are important causative agents for occupational respiratory and other diseases, and exposure may occur in a large variety of occupational environments. Recent data from longitudinal studies provide important information on diagnostic and preventive measures.

A longitudinal observation of early pulmonary responses to cotton dust

AIMS

To examine early adverse pulmonary effects of exposure to cotton dust, and to identify potential risk factors, including atopy for pulmonary responses to cotton dust.

METHODS

Spirometry, methacholine challenge testing, and questionnaire; performed among 101 non-smoking newly hired textile workers at baseline (prior to starting work), and at 3, 12, and 18 months after starting work. Concentrations of airborne cotton dust in various work areas were measured at each follow up survey using vertical elutriators.

RESULTS

The incidence of non-specific respiratory symptoms was 8% at three months, then diminished afterwards. Substantial acute cross shift drops in FEV(1) at each follow up survey, and longitudinal declines in FVC and FEV(1) after 12 months of exposure were observed. Airway responsiveness to methacholine increased with follow up time, and was more pronounced among atopics. Increasing airway responsiveness was strongly correlated with cross shift drops in FEV(1). In addition, one or more respiratory symptoms at three months was significantly, and pre-existing atopy marginally significantly, associated with cross shift drops in FEV(1) after adjusting for other covariates and confounders.

CONCLUSION

Results suggest that non-specific respiratory symptoms, decreasing lung function, and increasing airway responsiveness are early pulmonary responses to cotton dust. In addition, the occurrence of respiratory symptoms and increasing airway responsiveness, as well as atopy, may be important predictors for acute changes in lung function among cotton textile workers.

Lung function, airway reactivity, and atopy in newly hired female cotton textile workers

To assess changes in lung function and airway reactivity resulting from exposure to cotton dust, and the role of atopic status in these changes, the authors observed a group of 225 newly hired Chinese textile workers for 1 yr. All workers were female, lifelong nonsmokers, and none of them had been exposed previously to cotton or other occupational dust. Atopic status was determined at baseline. Spirometry, response to methacholine challenge, and total serum immunoglobulin E level were examined at baseline and again after subjects began work in the cotton mills. Obvious cross-shift drops in forced expiratory volume in 1 sec (FEV1.0), and declines in forced vital capacity and FEV1.0 over 1 yr, were observed. Atopic workers had a significantly greater acute drop in FEV1.0 than did nonatopic workers. Both atopic and nonatopic workers had slightly increased airway reactivity at 1 yr, compared with baseline values. The results suggest that exposure to cotton dust is responsible for acute and longitudinal declines in lung function, as well as for slightly increased airway reactivity. Atopy may interact with cotton dust to accentuate the acute lung function response.

Non-eosinophilic asthma: importance and possible mechanisms

There is increasing evidence that inflammatory mechanisms other than eosinophilic inflammation may be involved in producing the final common pathway of enhanced bronchial reactivity and reversible airflow obstruction that characterises asthma. A review of the literature has shown that, at most, only 50% of asthma cases are attributable to eosinophilic airway inflammation. It is hypothesised that a major proportion of asthma is based on neutrophilic airway inflammation, possibly triggered by environmental exposure to bacterial endotoxin, particulate air pollution, and ozone, as well as viral infections. If there are indeed two (or more) subtypes of asthma, and if non-eosinophilic (neutrophil mediated) asthma is relatively common, this would have major consequences for the treatment and prevention of asthma since most treatment and prevention strategies are now almost entirely focused on allergic/eosinophilic asthma and allergen avoidance measures, respectively. It is therefore important to study the aetiology of asthma further, including the underlying inflammatory profiles.

Inter- and intraindividual variation of endotoxin- and beta(1 --> 3)-glucan-induced cytokine responses in a whole blood assay

Inflammatory airway responses to bioaerosols and to their active compounds, such as endotoxin and beta(1 --> 3)-glucan, vary between individuals. These differences may be explained by variation in cytokine responsiveness, which can be assessed by in vitro stimulation tests with isolated blood leukocytes or lung macrophages. In large-scale population studies, ex vivo induced cytokine production may also be tested with a more simple 'whole blood assay' (WBA). However, applicability of a WBA to characterize a subject's responsiveness depends largely on its reproducibility. This study was conducted to: 1) assess the within- and between-subject variability in cytokine production in a WBA after stimulation with endotoxin or beta(1 --> 3)-glucan; and 2) to determine under which conditions this test is most discriminating between subjects and most reproducible within subjects. Blood was collected from 14 healthy volunteers, of whom 10 also participated on a second occasion. Each blood sample was used in two WBA tests; the first WBA was initiated two hours and the second 26 hours after venapuncture. The WBA test itself comprised overnight incubation with serial dilutions of endotoxin [lipopolysaccharide (LPS)] and curdlan (a beta(1 --> 3)-glucan), after which blood cell supernatant was collected. Interleukin(IL)-1beta, IL6, IL8 and tumor necrosis factor alpha (TNFalpha) were determined in the supernatant. In all individuals, a dose-dependent production of cytokines was observed for both LPS and curdlan. For all cytokines, variation between subjects was higher than within subjects, and this was most pronounced for IL1beta and IL6. There was moderate-to-high correlation in the induced release of all four cytokines, and between cytokine release induced by LPS or curdlan. Optimal stimulation concentrations were 6.25 and 12.5 ng/mL for endotoxin and 12500 and 25000 ng/mL for curdlan. Cytokine production in WBA initiated 26 hours after venapuncture showed lower between-subject and larger within-subject variance, thus favoring an early initiation of the assay. In conclusion, measuring endotoxin- or glucan-induced cytokine production in a WBA initiated within two hours after venapuncture appears to be an effective method to determine a person's cytokine responsiveness, at least in healthy naive subjects.

Agravos respiratórios decorrentes da atividade agrícola

As doenças respiratórias são um importante problema crítico para trabalhadores rurais, uma vez constatada evidência de aumento significativo do risco de morbidade e mortalidade, por problemas respiratórios, em trabalhadores agrícolas. Este fato é de grande importância especialmente nos países em desenvolvimento, onde grande parte da população depende da agricultura como fonte de subsistência. Sabidamente, pessoas envolvidas em atividades agrícolas estão potencialmente expostas a vários agentes como poeira inorgânica do solo, poeira orgânica, gases tóxicos, pesticidas, etc. O aparelho respiratório pode reagir a estes insultos ao nível de vias aéreas superiores com rinite, sinusite e otite. As vias aéreas inferiores podem responder desencadeando ou agravando asma brônquica, com o quadro conhecido como síndrome asthma-like, com obstrução crônica e lesões causadas por poeira orgânica, pneumonite por hipersensibilidade e fibrose intersticial. Assim, se faz necessário uma identificação precisa dos possíveis agentes etiológicos e conseqüentes medidas profiláticas das doenças respiratórias decorrentes da atividade agrícola.

Occupationally induced airways obstruction

The studies reviewed in this article indicate the association of occupational exposure to a variety of organic and inorganic dusts and various gases and fumes with chronic bronchitis and decrements of FEV1. Usually an obstructive pattern was noted, although in some occupations a similar decrement in FVC was noted. The effect of smoking on chronic bronchitis, respiratory symptoms, and FEV1 was usually additive, although workers exposed to cotton dust in one study demonstrated an interaction between exposure and smoking, as did a study of a general population sample. In coal workers, exposure to dust in younger workers resulted in a greater decline in lung function than if the exposure occurred in older workers. Studies in coal miners and grain workers further suggest that occupational standards in effect are not sufficient to protect the working population from adverse effects. The magnitude of the effect of occupation on decrement in FEV1 is usually less than cigarette smoking. Studies in coal miners indicate, however, that a minority of workers could be more severely affected by exposure. When considered together with cigarette smoking, additional decrements in lung function because of occupational exposure could contribute to disability. Additional study is needed for better understanding of exposure-response relationships, host factors, potential interaction with cigarette smoking, and pathophysiology of the development of occupationally induced airway disease.

Clinical symptoms and immunologic reactivity to bee and wasp stings in beekeepers

We compared the history of sting reactions with venom skin prick test (SPT) and CAP RAST reactions in beekeepers in order to assess the value of structured questions and symptom backgrounds. The study population consisted of 102 beekeepers, who were 25-75 years of age. Bee and wasp venom SPT was performed with concentrations of 10, 100, and 300 micrograms/ml. The CAP Phadiatop test was used in the screening of IgE antibodies against common inhalant allergens. Forty-two beekeepers had never experienced large local or systemic reactions after a bee sting. Of the 31 subjects with a history of systemic reactions, 13 had experienced these during the previous year. A significant difference (P < 0.01) between systemic reactors and nonreactors was found in bee venom CAP and SPT (300 micrograms/ml). However, due to considerable overlap, these tests are unable to discriminate between allergic and nonallergic beekeepers. Both bee venom SPT (300 micrograms/ml) and CAP tests were positive in 65% of systemic reactors and in 34% of nonreactors (P = 0.008). Venom SPT (300 micrograms/ml) correlated significantly with CAP for both venoms. No correlation was observed between venom allergy and atopy. Clinically, the most practical concentration for evaluating bee and wasp venom sensitization by SPT proved to be 300 micrograms/ml.

Longitudinal study of the health of cotton workers

OBJECTIVES

To follow up a group of newly employed workers in a cotton mill, and to report changes in symptoms over time.

METHODS

A group of 110 mill workers at a cotton mill in Shijiazhuang, China, was investigated by questionnaire, skin testing, and spirometric measurements of airway responsiveness through forced expiratory volume in one second (FEV1). The workers were examined before starting work, at 10 weeks, and at one year.

RESULTS

Decreases in FEV1 over shifts were small at 10 weeks and one year, and slightly higher among people with skin reactions to cotton dust extracts. Airway responsiveness, defined as the average decrease in FEV1 after 1.25 mg methacholine was increased at 10 weeks. It remained about the same after one year, except in the workers positive for the skin test, in whom it was further increased. Subjective symptoms of chest tightness and cough with phlegm increased progressively at 10 weeks and one year; nasal irritation remained unchanged and dry cough decreased between 10 weeks and one year.

CONCLUSION

The results suggest that the airway inflammation caused by cotton dust increases with increasing exposure time and that the changes are more notable in workers with reactivity to cotton dust extract.