The association of genetic factors with serum calretinin levels in asbestos-related diseases

BACKGROUND

Asbestos exposure is associated with different asbestos-related diseases, including malignant mesothelioma (MM). MM diagnosis is confirmed with immunohistochemical analysis of several markers, including calretinin. Increased circulating calretinin was also observed in MM. The aim of the study was to determine if CALB2 polymorphisms or polymorphisms in genes that can regulate calretinin expression are associated with serum calretinin levels or MM susceptibility.

SUBJECTS AND METHODS

The study included 288 MM patients and 616 occupationally asbestos-exposed subjects without MM (153 with asbestosis, 380 with pleural plaques and 83 without asbestos-related disease). Subjects were genotyped for seven polymorphisms in CALB2, E2F2, MIR335, NRF1 and SEPTIN7 genes using competitive allele-specific polymerase chain reaction (PCR). Serum calretinin was determined with ELISA in 545 subjects. Nonparametric tests, logistic regression and receiver operating characteristic (ROC) curve analysis were used for statistical analysis.

RESULTS

Carriers of at least one polymorphic CALB2 rs889704 allele had lower calretinin levels (P = 0.036). Carriers of two polymorphic MIR335 rs3807348 alleles had higher calretinin (P = 0.027), while carriers of at least one polymorphic NRF1 rs13241028 allele had lower calretinin levels (P = 0.034) in subjects without MM. Carriers of two polymorphic E2F2 rs2075995 alleles were less likely to develop MM (odds ratio [OR] = 0.64, 95% confidence interval [CI] = 0.43-0.96, P = 0.032), but the association was no longer significant after adjustment for age (P = 0.093). Optimal serum calretinin cut-off values differentiating MM patients from other subjects differed according to CALB2, NRF1, E2F2, and MIR335 genotypes.

CONCLUSIONS

The results of presented study suggest that genetic variability could influence serum calretinin levels. These findings could contribute to a better understanding of calretinin regulation and potentially to earlier MM diagnosis.

Subchronic pulmonary pathology, iron overload, and transcriptional activity after Libby amphibole exposure in rat models of cardiovascular disease

BACKGROUND

Surface-available iron (Fe) is proposed to contribute to asbestos-induced toxicity through the production of reactive oxygen species.

OBJECTIVE

Our goal was to evaluate the hypothesis that rat models of cardiovascular disease with coexistent Fe overload would be increasingly sensitive to Libby amphibole (LA)-induced subchronic lung injury.

METHODS

Male healthy Wistar Kyoto (WKY), spontaneously hypertensive (SH), and SH heart failure (SHHF) rats were intratracheally instilled with 0.0, 0.25, or 1.0 mg LA (with saline as the vehicle). We examined bronchoalveolar lavage fluid (BALF) and histological lung sections after 1 week, 1 month, or 3 months for pulmonary biomarkers and pathology. SHHF rats were also assessed at 6 months for pathological changes.

RESULTS

All animals developed concentration- and time-dependent interstitial fibrosis. Time-dependent Fe accumulation occurred in LA-laden macrophages in all strains but was exacerbated in SHHF rats. LA-exposed SHHF rats developed atypical hyperplastic lesions of bronchiolar epithelial cell origin at 3 and 6 months. Strain-related baseline differences existed in gene expression at 3 months, with persistent LA effects in WKY but not SH or SHHF rats. LA exposure altered genes for a number of pathways, including inflammation, immune regulation, and cell-cycle control. Cell-cycle control genes were inhibited after LA exposure in SH and SHHF but not WKY rats, whereas tumor suppressor genes were induced only in WKY rats. The inflammatory gene expression also was apparent only in WKY rats.

CONCLUSION

These data show that in Fe-overload conditions, progressive Fe accumulation occurs in fiber-laden macrophages within LA-induced lesions. Fe overload does not appear to contribute to chronic inflammation, and its role in hyperplastic lesion development requires further examination.

Osteopontin modulates inflammation, mucin production, and gene expression signatures after inhalation of asbestos in a murine model of fibrosis

Inflammation and lung remodeling are hallmarks of asbestos-induced fibrosis, but the molecular mechanisms that control these events are unclear. Using laser capture microdissection (LCM) of distal bronchioles in a murine asbestos inhalation model, we show that osteopontin (OPN) is up-regulated by bronchiolar epithelial cells after chrysotile asbestos exposures. In contrast to OPN wild-type mice (OPN(+/+)) inhaling asbestos, OPN null mice (OPN(-/-)) exposed to asbestos showed less eosinophilia in bronchoalveolar lavage fluids, diminished lung inflammation, and decreased mucin production. Bronchoalveolar lavage fluid concentrations of inflammatory cytokines (IL-1β, IL-4, IL-6, IL-12 subunit p40, MIP1α, MIP1β, and eotaxin) also were significantly less in asbestos-exposed OPN(-/-) mice. Microarrays performed on lung tissues from asbestos-exposed OPN(+/+) and OPN(-/-) mice showed that OPN modulated the expression of a number of genes (Col1a2, Timp1, Tnc, Eln, and Col3a1) linked to fibrosis via initiation and cross talk between IL-1β and epidermal growth factor receptor-related signaling pathways. Novel targets of OPN identified include genes involved in cell signaling, immune system/defense, extracellular matrix remodeling, and cell cycle regulation. Although it is unclear whether the present findings are specific to chrysotile asbestos or would be observed after inhalation of other fibers in general, these results highlight new potential mechanisms and therapeutic targets for asbestosis and other diseases (asthma, smoking-related interstitial lung diseases) linked to OPN overexpression.

Glutathione S-transferases GSTM1 and GSTT1 polymorphisms and asbestosis

OBJECTIVE

In a nested case-control study, the authors investigated whether the deletion polymorphism of glutathione S-transferases GSTM1 and GSTT1 represents a risk factor for the development of asbestosis.

METHODS

In total, 262 cases with asbestosis and 265 controls, selected from a cohort of 2080 workers occupationally exposed to asbestos, were genotyped for GSTM1 and GSTT1-null alleles. Cumulative exposure for each subject was available.

RESULTS

Asbestosis was associated with cumulative exposure (odds ratio [OR]=3.21, confidence interval [CI] 2.43-4.23) and GSTT1-null genotype (OR=0.61, CI 0.40-0.94), but not with GSTM1-null genotype (OR=1.01, CI 0.71-1.43). The risk of GSTM1-null and GSTT1-null genotype for asbestosis did not change after adjustment by cumulative exposure, smoking, gender, and age.

CONCLUSIONS

An important finding of this study is that GSTT1 gene deletion might have a protective effect on the development of asbestosis.

Genetic predisposition and health effect of occupational exposure to asbestos

OBJECTIVES

As asbestos presents a direct genetic hazard for humans, a small-scale molecular epidemiological study was conducted to monitor 61 subjects long-term exposed to asbestos in comparison with 49 town controls and 21 control subjects from administration of the same factory.

RESULTS

Asbestos exposed workers had significantly higher numbers of chromosomal aberrations compared with both control groups (P=0.003). Clinical examination showed that 44.3% of exposed workers developed symptoms of asbestosis. We were interested in the relationship between the risk of asbestos-coupled diseases and individual variability in biotransformation enzymes, especially in glutathione S-transferases and microsomal epoxide hydrolase. GSTP1*105Val allele appeared less in the group of workers with asbestosis compared to those without asbestosis (18.5% vs 34.7%, P=0.044), and in subjects with developed asbestosis coupled with bronchitis compared to those without bronchitis (0% vs 25%, P=0.048). Similarly, the genotype corresponding to low activity of microsomal epoxide hydrolase was significantly decreased in workers with fibrotic plaques compared to those without plaques (26.7% vs 56.3%, P=0.045).

CONCLUSIONS

Our results suggest that GSTP1*105Val allele and low EPHX1 activity genotype may be protective for people occupationally exposed to asbestos. However, more extensive studies are needed to confirm our results.

[The relation of asbestosis to human 8-oxoguanine DNA glycosidase polymorphism and DNA damage in peripheral lymphocytes]

OBJECTIVE

To explore the relation of asbestosis to human 8-oxoguanine DNA glycosidase (hOGG1) genotype and DNA damage, the investigation of hOGG1 polymorphism distribution and DNA strand breakages in peripheral lymphocytes was carried on in occupational population.

METHODS

A total 101 asbestos-exposed workers and 141 controls were investigated. The DNA damage level was obtained by single cell gel electrophoresis (SCGE) and hOGG1 Ser326Cys polymorphism by PCR-RELP.

RESULTS

(1) A significant increase in the exposed group was observed in comet scores at basal (34.8 +/- 16.8), H2O2-induced (136.7 +/- 36.0) and 4 hours after repair (51.0 +/- 18.7) as compared with the control group (P < 0.01). And the scores in H2O2-induced (147.0 +/- 30.8) and 4 hours after repair (56.9 +/- 21.4) were significantly higher in asbestosis workers than in non-asbestosis ones (125.7 +/- 38.2 and 44.9 +/- 15.4, P < 0.01). (2) There was no differences of the genotype distribution between the asbestos group and the control group (chi(2) = 0.22, P = 0.89). A significant difference in the distribution of this polymorphism (Ser/Ser, Ser/Cys, Cys/Cys) between asbestosis group (25.5%, 51.0%, 23.5%) and the non-asbestosis group (48.0%, 36.0%, 16.0%) was observed (chi(2) = 6.023, P < 0.05). The comet scores at H2O2-induced and 4 hours after repair were higher in asbestosis subjects than in non-asbestosis ones (P < 0.05). (3) After adjusting ages, sex, smoking and drinking status, the odds ratios of the Cys allele for asbestosis were 0.66 (95% CI = 0.38 - 1.13) in the exposed subjects.

CONCLUSION

The results suggested that the asbestos occupational exposure might induce DNA damage and the augment on susceptivity of H2O2 oxidation and the fall of the capacity of repairing DNA damage might be one of the mechanisms to induce asbestosis among subjects with the Cys allele.

Gene expression profiles reveal increased mClca3 (Gob5) expression and mucin production in a murine model of asbestos-induced fibrogenesis

To elucidate genes important in development or repair of asbestos-induced lung diseases, gene expression was examined in mice after inhalation of chrysotile asbestos for 3, 9, and 40 days. We identified changes in the expression of genes linked to proliferation (cyclin B2, CDC20, and CDC28 protein kinase regulatory subunit 2), inflammation (CCL9, CCL6, complement component 1, chitinase3-like 3, TNF superfamily member 10, and IL-1B), and matrix remodeling (MMP12, MMP3, integrin alphaX, and cathepsins K, Z, B, and S). The most highly induced gene at all time points was mclca3 (gob5), a putative calcium-activated chloride channel involved in the regulation of mucus production and/or secretion. Using histochemistry, we demonstrated accumulation of mucus and increased mClca3 protein in the bronchiolar epithelium of asbestos-exposed mice at all time points but peaking at 9 days. Cytokine levels (interleukin-1beta, interleukin-4, interleukin-6) in bronchoalveolar lavage fluid also increased at 9 days, suggesting Th2-mediated immunity may play a role in asbestos-induced mucus production. In contrast, levels of cathepsin K, a potent elastase, increased between 3 and 40 days at both the mRNA and protein levels, localizing primarily in CD45-positive leukocytes and interstitial cells. Identification of genes involved in lung injury and remodeling after asbestos exposure could aid in defining mechanisms of airborne particulate-induced disease and in developing therapeutic strategies.

[Studies on insulin-like growth factor-I expression in human lower airways]

Antisense techniques that inhibit intracellular expression of insulin-like growth factor-I (IGF-I) were efficient in gene therapy of some tumor diseases. IGF-I in the airways is considered to induce lung fibrosis in interstitial lung diseases, inhibit apoptosis of epithelial cells and participate in local carcinogenesis.

AIM OF THE STUDY

The aim of the study was--by examining the IGF-I expression in the lower airways--to evaluate preliminary the efficacy of anti-IGF-I antisense technicques in the treatment of airways diseases.

MATERIAL AND METHODS

The IGF-I expression was examined in the reverse transcriptase--polimerase chain reaction (RT-PCR) applied to A549 human cell line, that is representative for lower airway epithelium and exemplifies the model of bronchioloalveolar adenocarcinoma. IGF-I expression in non-neoplastic lower airways cells was assessed by immunocytochemical staining (anti-IGF-I) in cytological materials originating from bronchoalveolar lavage (BAL) of sarcoidosis and asbestosis patients and in individuals free of lung pathology.

RESULTS

The IGF-I expression was detected in A549 cells with use of RT-PCR method (3 independent probes). In BAL cytological specimens the appearance of IGF-I was found, mainly in alveolar macrophages (62 +/- 6, 5 in sarcoidosis vs. 36 +/- 6 in controls, p=0,09), as well as in BAL lymphocytes.

CONCLUSIONS

Summing up, the antisense technicques, blocking the intracellular IGF-I expression may be potentially useful in treatment of selected lower airways, both tumor (non-small cell lung carcinoma) and non-tumor (ILD complicated with lung fibrosis) conditions.

Concentration of hydroxyproline in blood: a biological marker in occupational exposure to asbestos and its relationship with Pi*Z and Pi*S polymorphism in the alpha-1 antitrypsin gene

BACKGROUND

Hydroxyproline (OHP) is one of the most abundant amino acids in collagen and, in general, it provides a good measure of overall collagen catabolism.

METHODS

Asbestos workers suffering from asbestosis (cases n = 85); asbestos exposed workers without asbestosis (exposed controls, EC, n = 86), and non-exposed population (non-exposed controls, NEC, n = 122) were studied. The concentration of free OHP in whole blood was measured following the Pico-Tag procedure.

RESULTS

Concentration of OHP in blood was significantly different in the three groups studied (P < 0.001), being higher in cases (19.8 +/- 14.7 micromol/L) than in EC (16 +/- 12.4) and NEC (13.5 +/- 6.7). When all individuals were grouped and stratified by the Pi*S and Pi*Z polymorphisms in the alpha-1-antitrypsin gene, the highest OHP levels were detected in the Pi*S homozygotes, one of the asbestosis-at risk-genotypes (Pi*S homozygotes, x = 24.5 +/- 11.7; Pi*S heterozygotes, x = 16.6 +/- 10.0; wild type, wt, x = 15.9 +/- 11.8).

CONCLUSIONS

Blood OHP concentration could be used for monitoring human exposure to asbestos, either as a marker for occupational monitoring or as an additional clinical parameter in diagnostic exploration of asbestosis.

Asbestos-induced pulmonary toxicity: role of DNA damage and apoptosis

Asbestos causes asbestosis and various malignancies by mechanisms that are not clearly defined. Here, we review the accumulating evidence showing that asbestos is directly genotoxic by inducing DNA strand breaks (DNA-SB) and apoptosis in relevant lung target cells. Although the exact mechanisms by which asbestos causes DNA damage and apoptosis are not firmly established, some of the implicated mechanisms include the generation of iron-derived reactive oxygen species (ROS) as well as reactive nitrogen species (RNS), alteration in the mitochondrial function, and activation of the death receptor pathway. We focus on the accumulating evidence implicating ROS. DNA repair mechanisms have a key role in limiting the extent of DNA damage. Recent studies show that asbestos activates DNA repair enzymes such as apurinic/apyrimidinic endonuclease (APE) and poly (ADP-ribose) polymerase (PARP). Asbestos-induced neoplastic transformation may result in the setting where DNA damage overwhelms DNA repair in the face of a persistent proliferative signal. Strategies aimed at limiting asbestos-induced oxidative stress may reduce DNA damage and, as such, prevent malignant transformation.

Pi*S and Pi*Z alpha 1 antitrypsin polymorphism and the risk for asbestosis in occupational exposure to asbestos

Alpha 1 antitrypsin is a highly polymorphic anti-elastase enzyme, especially active in the protection of alveoli and liver. Here we studied the distribution of two deficient alleles Pi*Z and Pi* S, in 194 asbestos workers, of whom 100 were asbestosis cases, and 94 were controls without disease (exposed controls, EC). A second group of controls without asbestos exposure (non-exposed controls, NEC; n=122) was also included. Multivariate analysis adjusted by age and smoking habit showed ninefold risk for asbestosis in Pi*Z heterozygous individuals and 5.9-fold risk for Pi*S homozygous although differences were only significant in the first case (cases vs. EC: OR 8.9; p=0.04). Considering both genotypes (Pi*Z heterozygous, Pi*S homozygous) we obtained an OR of 8 (p=0.01). Our results suggest that the alpha 1 antitrypsin polymorphisms, especially Pi*Z, could help to predict asbestosis risk and confirm the high prevalence of the Pi*S allele in Spain.

Manganese superoxide dismutase genotypes and asbestos-associated pulmonary disorders

Manganese superoxide dismutase (MnSOD) activity is highly elevated in the biopsies of human asbestos-associated malignant mesothelioma. We therefore examined if polymorphism in the mitochondrial targeting sequence of the MnSOD gene modified individual susceptibility to this malignancy or related asbestos-associated pulmonary disorders. The study population consisted of 124 male Finnish asbestos insulators who were all classified as having been exposed to high levels of asbestos; 63 of the workers had no pulmonary disorders and 61 either had malignant mesothelioma or the non-malignant pulmonary disorders asbestosis and/or pleural plaques. No significant associations were found between the MnSOD genotypes and these ill-health. This study therefore suggest no major modifying role for the MnSOD polymorphism in development of asbestos-associated pulmonary disorders.

Diseases caused by asbestos: mechanisms of injury and disease development

Asbestos is a ubiquitous, naturally occurring fiber that has been linked to the development of malignant and fibrotic diseases of the lung and pleura. These diseases may be initiated by injury to epithelial cells and mesothelial cells by asbestos fibers through the formation of reactive oxygen intermediates. Elaboration of oxidants are also a consequence of inflammation, a hallmark of exposure to asbestos after inhalation or injection of asbestos fibers into animals. The type, size, and durability of asbestos fibers may be important in toxicity and pathogenicity of asbestos types. This review discusses the pathways of oxidant generation by asbestos fibers, cell-cell interaction that may initiate and perpetuate inflammation, cytokine release and proliferative responses to asbestos, and cell signaling pathways implicated in these events.

[Malignant mesothelioma of the pleura, pericardium and peritoneum. 1: Etiology, pathogenesis, pathology]

The incidence of primary malignant neoplasms of the pleura, the pericardium and the peritoneum in Germany has been rising since about the mid-1980s. A continuing rise is expected until about 2020, predominantly due to the peak of asbestos processing in Germany between 1965 and 1980. About 90% of the mesotheliomas stored in the files of the German Mesothelioma Registry in Bochum are asbestos related and therefore possibly due to occupational exposure that may be compensated by the professional associations. More than 500 mesotheliomas annually can be diagnosed in the German Mesothelioma Registry. In this first part of the series on mesotheliomas, current concepts on etiology and pathogenesis as well as diagnostic procedures and standards are discussed. At the present, specific chromosomal or genetic defects that constantly give rise to a mesothelioma are not known. The initiation and progression of malignant mesotheliomas is a highly complex mechanism that is based on individual genetic alterations. A reliable diagnosis is the basis for therapeutic, prognostic and medicolegal consequences; in general, it can be achieved by thoracoscopic inspection with selected biopsy. Surgery may gain a more important role in the therapy of malignant tumors of serosal membranes not only in palliative, but also in potential curative approaches if the diagnosis can be made at earlier tumor stages.

Cellular and molecular mechanisms of asbestos-induced fibrosis

Pleural and pulmonary fibrosis (asbestosis) are ramifications of occupational exposures to asbestos fibers, a diverse family of ubiquitous, naturally-occurring minerals. The pathogenesis of asbestos-associated fibrosis involves the participation of a number of cell types and is characterized by an early and persistent inflammatory response that involves the generation of oxidants, growth factors, chemokines, and cytokines. These mediators may also contribute directly to cell injury, proliferation, and fibrogenesis. After interaction with cells, asbestos fibers trigger a number of signaling cascades involving mitogen-activated protein kinases (MAPK) and nuclear factor kappa-B (NF-kappaB). Activation of transcription factors such as NF-kappaB and activator protein-1 (AP-1) may be linked to increases in early response genes (e.g., c-jun and c-fos) which govern proliferation, apoptosis, and inflammatory changes in the cells of the lung. The goal of this article is to review the cellular and molecular mechanisms of asbestos-induced fibrosis that may be critical to the development of effective treatment regimens.

[Detection of p53 gene mutation in paraffin-embedded asbestos-related lung cancer tissue]

Paraffin-embedded asbestos-related lung cancer tissue of ten cases was analyzed with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) to study its genetic mutation of exon 5, 7 and 8 of anti-oncogene p53 by silver stain. Results showed that fragment of exon 7 or 8 of p53 gene in four cases was positive in silver-staining analysis of PCR-SSCP. Exon 7 or 8 fragments of p53 gene was detected positive for mutation in seven of these ten cases with autoradiographic analysis of PCR-SSCP. No exon 5 fragment was found positive for mutation in these ten cases with both methods. Agreement between results of silver staining and those of autoradiographic PCR-SSCP was 60%. Hence, autoradiographic method could be replaced by silver staining, a simpler and more sensitive one, in PCR-SSCP to study gene mutation of asbestosrelated lung cancer.

The glutathione S-transferase theta and mu deletion polymorphisms in asbestosis

The glutathione S-transferases (GSTs) catalyze the conjugation of a wide variety of reactive, electrophilic substrates with glutathione, facilitating their excretion. There is also evidence that GSTs can catalyze glutathione conjugation of lipid radicals as well as act in the generation of leukotriene inflammatory mediators. Studying construction carpenters screened for the presence of asbestos-related diseases, we have previously reported that the constitutional deletion of GSTM1 (the gene coding for glutathione S-transferase class mu) is associated with an increased risk of asbestos-related interstitial lung disease, measured radiographically. In the current work, we have further studied this group of workers, investigating the distribution of a novel deletion polymorphism in the newly described GSTT1 gene, that codes for the GST class theta enzyme. A total of 666 carpenters were studied, and 124 (19%) had the deleted genotype. There was no association between the GSTT1 deletion and the radiographic diagnosis of either asbestos-related pleural or parenchymal disease. The GSTM1 deletion remained associated with the presence of x-ray evidence of asbestosis after adjustment for GSTT1 genotype. The GSTM1 null genotype was also associated with a family history of any malignancy. These data suggest that the association of polymorphic GSTs with asbestos-induced radiographic changes is specific for substrates of the GST class mu.

Mutations, tissue accumulations, and serum levels of p53 in patients with occupational cancers from asbestos and silica exposure

In order to determine the relationship between mutations, tissue accumulations, and serum levels of p53 in occupational cancers, we used denaturing gradient gel electrophoresis and DNA sequencing of exons 5-9 of the p53 gene, immunohistochemical analysis for tissue identification of mutant p53 protein, and enzyme-linked immunosorbent assay for serum levels of mutant p53 protein to examine for such alteration in a cohort of individuals with workplace exposure to asbestos or silica, and resultant lung cancers or mesotheliomas. DNA analysis detected mutations in 5 of 18 (28%) tumors, and tissue accumulations of protein were detected in 7 of 20 (35%) tumors; the agreement between mutational and immunohistochemical analyses was significant (kappa = 0.62, P = 0.002). Serum elevations of protein were detected in 4 of 11 (36%) cases with available serum samples; the agreement between tissue alterations and serum elevations was also significant (kappa = 0.71, P = 0.017). In addition, based on the analysis of banked samples, serum results tended to be consistent over time prior to the diagnosis of disease (positive predictive value = 0.67, negative predictive value = 0.83). These results suggest that serum levels of p53 are reasonably accurate in reflecting tissue alterations in p53 at the gene and/ or protein level and may be early biomarkers of disease risk.

Dose-responsive increases in pulmonary fibrosis after inhalation of asbestos

We focused here on steady-state mRNA levels of genes involved in antioxidant defense, i.e., manganese superoxide dismutase and copper-zinc superoxide dismutase, and in cell proliferation, i.e., ornithine decarboxylase, c-jun, and glyceraldehyde-3-phosphate-dehydrogenase in whole-lung homogenates from Fischer 344 rats at 3 h to 20 d after exposure to crocridolite asbestos. Changes in gene expression were correlated with histopathologic findings, total and differential cell counts in bronchoalveolar lavage, and levels of hydroxyproline in lung. Dosage-dependent increases in mRNA levels of antioxidant enzymes and proliferation-related genes were observed. Differential cell counts revealed a dose-related infiltration of neutrophils that preceded elevations in gene expression. Neutrophil infiltration into lung and focal lesions of fibrosis as well as increased levels of hydroxyproline were observed only at high concentrations of asbestos. These results indicate that high airborne concentrations of asbestos cause molecular changes in lung that may be related to antioxidant defense and the triggering of cell proliferation, a feature of asbestosis and lung cancer.

[Genetic polymorphism of haptoglobin and quantitative changes in its levels during exposure to asbestos]

The polymorphism and serum levels of haptoglobin were studied in asbestosis patients, in the control and the workers exposed to asbest. Hp1-1 has the highest, Hp2-2--the lowest and Hp2-1 has the intermediate concentration of this protein. In the course of contact with asbest, and especially in asbestosis patients, the haptoglobin levels are higher (for all phenotypes). The standard deviation from the Hp concentration in asbestosis patients was significantly higher. The phenotypes Hp1-1 were found more often in asbestosis patients than among asbest-exposed workers.

[The association of genetic and functional variability of alpha 1-antitrypsin in asbestosis]

The polymorphism and serum levels of alpha 1-antitrypsin (AT) were studied in asbestosis patients, the control and the workers exposed to mineral flax longer or less than ten years. M1S, M3S, M1Z and M2M2 phenotypes had low concentration of this protein. In the course of contact with mineral flax decrease in alpha 1-AT concentration was found. The phenotypes with low protein levels were very rare among workers contacting with asbestos for a long time, and one of them--M1S was more often encountered in asbestosis patients. The standard deviation from the alpha 1-AT concentration was significantly higher in asbestosis patients.

[Familial clustering of asbestos-related diseases]

This article describes the case histories of four individuals in the same family, all of whom developed asbestos-related disease. Special emphasis is placed upon the case of a woman, who after seemingly minimal exposure to asbestos, in the form of cleaning her husband's working clothes, developed a malignant mesothelioma. The incidence of asbestos-related disease has increased steadily over the past ten years. This probably reflects the extensive use of asbestos in Norway since World War II, and the long latency period of the disease. The authors recommend obtaining an in-depth history of exposure when asbestos-related disease is suspected.

Changes on radiographs of wives of workers exposed to asbestos

Between January and March 1986, 117 wives of insulation workers exposed to asbestos were screened by means of chest radiography, pulmonary function testing, and a detailed questionnaire. The final study group included 93 women over 40 years of age. Eighteen of these (19.4%) demonstrated pleural changes consistent with asbestos exposure, including pleural plaque (88.9%), diaphragm plaque (27.8%), pleural calcification (16.6%), and diffuse pleural thickening (5.5%). In statistical correlation between the groups with normal and abnormal radiographs, the only factor that proved significant was the year of first exposure (the duration of the latent period). Finally, radiographs of the husbands were compared for 17 of the 18 wives with radiographic abnormalities. Fourteen of the husbands (82%) demonstrated more severe radiographic changes than their wives.

Asbestos diseases and pulmonary symptoms and signs in shipyard workers and their families in Los Angeles

Families of 338 male and 81 female shipyard workers (SYW), including 280 wives, 144 daughters, and 81 sons, were examined for diseases resulting from asbestos. The workers were initially exposed to asbestos at least 20 years prior to the study date. Radiographic signs of asbestosis (using standard criteria international Labor Office 1980) were found in 64% of 288 male SYW and 21% of 71 female SYW. After excluding those with any occupational exposure to asbestos, asbestosis prevalence was 11% in wives, 8% in sons, and 2% in daughters. Asbestos disease prevalence in workers and in wives increased with the number of years from initial exposure. Male SYW who had smoked had airway obstruction without volume loss. Nonsmokers had normal pulmonary functions. In SYW households prevalences of respiratory diseases, wheezing on physical examination, and symptoms of asthma and chronic bronchitis, exceeded those in the comparison (Michigan) population, even for the younger daughters and sons. These differences, and airway obstruction and distribution defects reported earlier were not explained by cigarette smoking or by asbestos exposure. Instead, they are tentatively ascribed to long-term exposure to ambient air pollution in Los Angeles.

Pulmonary functional impairment and symptoms in women in the Los Angeles Harbor area

Spirometric measurements of vital capacity and flow rates, thoracic gas volume, and single-breath diffusing capacity for carbon monoxide were obtained in 360 white women, 238 wives age 58 years and 122 daughters age 32 years of shipyard workers from the Long Beach area of southern California. The values for nonsmokers, exsmokers, and current smokers were compared with smoking-specific mean values, age- and height-adjusted, from a reference population in Michigan. The wives from Long Beach had significantly lower mid and terminal flows, single-breath diffusing capacity for carbon monoxide, and alveolar volume, except that single-breath diffusing capacity for carbon monoxide was not significantly lower in current smokers. Nonsmokers and ex-smokers showed significantly different values for one-second forced expiratory volume in addition to flow rates and single-breath diffusing capacity for carbon monoxide. Daughters showed significant reductions in single-breath diffusing capacity for carbon monoxide and alveolar volume, which are attributable to maldistribution of inspired gas. These data showed that a powerful factor has affected expiratory air flow and distribution of gas, resulting in altered single-breath diffusing capacity for carbon monoxide and alveolar volume in this population. The factor is additive with and resembles the effect of cigarette smoking, and it is postulated that this factor is oxidant air pollution.

Sister chromatid exchange frequency in asbestos workers

In vitro cytogenetic studies of amosite, chrysotile, and crocidolite asbestos have shown that these fibers may induce chromosome abnormalities and an elevated sister chromatid exchange (SCE) rate in mammalian cells. Twenty-five asbestos insulators (6 with radiographic asbestosis) were compared to 14 controls frequency matched for age and were found to have a marginally increased SCE rate in circulating lymphocytes with increasing years of exposure (P= 0.057). There was a significant association between SCE rate and smoking (P=0.002) after controlling for years of asbestos exposure and age. Smoking asbestos insulators had the highest SCE rate. Sister chromatid exchanges in chromosomes of group A, i.e., the group with the longest chromosomes, were significantly associated with asbestos exposure and cigarette smoking, with an interaction between the two.

Asbestos-related disease from household exposure

The importance of nonoccupational asbestos exposure has been emphasized recently. To illustrate this problem, we report 4 persons with asbestos-related disease from household exposure. There were 2 wives of asbestos workers, who cleaned their husbands' work clothes. One developed a mesothelioma and the other plaques, calcification, benign asbestos pleural effusion and subpleural parenchymal fibrosis. 2 men were exposed as children while playing in a cellar room which was also used for their father's muffler repair business. At ages 27 and 33, they had pleural and diaphragmatic calcifications.

HLA-A and B antigen frequencies in an asbestos exposed population with normal and abnormal chest radiographs

Previous studies of HLA antigen frequencies in asbestos related pulmonary fibrosis have suggested some weak associations both with susceptibility to the disease (B12 and B27) and protection from the disease (B18 and Bw35). HLA typing was performed on a further series of 64 asbestos workers with no chest abnormality and 166 workers with various radiographic changes, 78 having pulmonary fibrosis. The results fail to give statistical confirmation of these associations although B27 was twice as frequently associated with pulmonary fibrosis and diffuse pleural thickening. Analysis of the combined data from this and four other studies failed to show any consistent associations.

Frequency of HLA antigen in asbestos workers with and without pulmonary fibrosis

HLA antigens were determined in 37 patients with asbestosis and 37 matched controls with equivalent asbestos exposure but no pulmonary fibrosis. All had worked in the same textile factory. No significant differences in the prevalence of antigens were found between the two groups or between either group and controls who had not been exposed to asbestos. When the data were combined with findings from other pilot studies the previously suggested association between asbestosis and HLA-B27 was not confirmed. Subjects who were positive for HLA-B12 tended also to have advanced radiographic fibrosis. Asbestos workers without pulmonary fibrosis had an unexpectedly high frequency of HLA-BW5, which might indicate that this antigen protects against the development of pulmonary fibrosis.