Interaction of genetic and exposure factors in the prevalence of berylliosis

Occupational interstitial lung diseases

Millions of workers are exposed to substances known to cause occupational interstitial lung diseases (ILDs), particularly in developing countries. However, the burden of the disease is likely to be underestimated due to under-recognition, under-reporting or both. The diagnosis of occupational ILD requires a high level of suspicion and a thorough occupational history, as occupational and non-occupational ILDs may be clinically, functionally and radiologically indistinguishable, leading to delayed diagnosis and inappropriate management. A potential occupational aetiology should always be considered in the differential diagnosis of ILD, as removal from the workplace exposure, with or without treatment, is a key therapeutic intervention and may lead to significant improvement. In this article, we provide an overview of the 'traditional' inorganic dust-related ILDs but also address idiopathic pulmonary fibrosis and the immunologically mediated chronic beryllium disease, sarcoidosis and hypersensitivity pneumonitis, with emphasis on the importance of surveillance and prevention for reducing the burden of these conditions. To this end, health-care professionals should be specifically trained about the importance of occupational exposures as a potential cause of ILD.

Realistic biomarkers from plasma extracellular vesicles for detection of beryllium exposure

Purpose

Exposures related to beryllium (Be) are an enduring concern among workers in the nuclear weapons and other high-tech industries, calling for regular and rigorous biological monitoring. Conventional biomonitoring of Be in urine is not informative of cumulative exposure nor health outcomes. Biomarkers of exposure to Be based on non-invasive biomonitoring could help refine disease risk assessment. In a cohort of workers with Be exposure, we employed blood plasma extracellular vesicles (EVs) to discover novel biomarkers of exposure to Be.

Methods

EVs were isolated from plasma using size-exclusion chromatography and subjected to mass spectrometry-based proteomics. A protein-based classifier was developed using LASSO regression and validated by ELISA.

Results

We discovered a dual biomarker signature comprising zymogen granule protein 16B and putative protein FAM10A4 that differentiated between Be-exposed and -unexposed subjects. ELISA-based quantification of the biomarkers in an independent cohort of samples confirmed higher expression of the signature in the Be-exposed group, displaying high predictive accuracy (AUROC = 0.919). Furthermore, the biomarkers efficiently discriminated high- and low-exposure groups (AUROC = 0.749).

Conclusions

This is the first report of EV biomarkers associated with Be exposure and exposure levels. The biomarkers could be implemented in resource-limited settings for Be exposure assessment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-022-01871-7.

Innate and Adaptive Immunity in Noninfectious Granulomatous Lung Disease

Sarcoidosis and chronic beryllium disease are noninfectious lung diseases that are characterized by the presence of noncaseating granulomatous inflammation. Chronic beryllium disease is caused by occupational exposure to beryllium containing particles, whereas the etiology of sarcoidosis is not known. Genetic susceptibility for both diseases is associated with particular MHC class II alleles, and CD4⁺ T cells are implicated in their pathogenesis. The innate immune system plays a critical role in the initiation of pathogenic CD4⁺ T cell responses as well as the transition to active lung disease and disease progression. In this review, we highlight recent insights into Ag recognition in chronic beryllium disease and sarcoidosis. In addition, we discuss the current understanding of the dynamic interactions between the innate and adaptive immune systems and their impact on disease pathogenesis.

Metals and molecular carcinogenesis

Many metals are essential for living organisms, but at higher doses they may be toxic and carcinogenic. Metal exposure occurs mainly in occupational settings and environmental contaminations in drinking water, air pollution and foods, which can result in serious health problems such as cancer. Arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr) and nickel (Ni) are classified as Group 1 carcinogens by the International Agency for Research on Cancer. This review provides a comprehensive summary of current concepts of the molecular mechanisms of metal-induced carcinogenesis and focusing on a variety of pathways, including genotoxicity, mutagenesis, oxidative stress, epigenetic modifications such as DNA methylation, histone post-translational modification and alteration in microRNA regulation, competition with essential metal ions and cancer-related signaling pathways. This review takes a broader perspective and aims to assist in guiding future research with respect to the prevention and therapy of metal exposure in human diseases including cancer.

Adaptive Immunity in Pulmonary Sarcoidosis and Chronic Beryllium Disease

Pulmonary sarcoidosis and chronic beryllium disease (CBD) are inflammatory granulomatous lung diseases defined by the presence of non-caseating granulomas in the lung. CBD results from beryllium exposure in the workplace, while the cause of sarcoidosis remains unknown. CBD and sarcoidosis are both immune-mediated diseases that involve Th1-polarized inflammation in the lung. Beryllium exposure induces trafficking of dendritic cells to the lung in a mechanism dependent on MyD88 and IL-1α. B cells are also recruited to the lung in a MyD88 dependent manner after beryllium exposure in order to protect the lung from beryllium-induced injury. Similar to most immune-mediated diseases, disease susceptibility in CBD and sarcoidosis is driven by the expression of certain MHCII molecules, primarily HLA-DPB1 in CBD and several HLA-DRB1 alleles in sarcoidosis. One of the defining features of both CBD and sarcoidosis is an infiltration of activated CD4+ T cells in the lung. CD4+ T cells in the bronchoalveolar lavage (BAL) of CBD and sarcoidosis patients are highly Th1 polarized, and there is a significant increase in inflammatory Th1 cytokines present in the BAL fluid. In sarcoidosis, there is also a significant population of Th17 cells in the lungs that is not present in CBD. Due to persistent antigen exposure and chronic inflammation in the lung, these activated CD4+ T cells often display either an exhausted or anergic phenotype. Evidence suggests that these T cells are responding to common antigens in the lung. In CBD there is an expansion of beryllium-responsive TRBV5.1+ TCRs expressed on pathogenic CD4+ T cells derived from the BAL of CBD patients that react with endogenous human peptides derived from the plexin A protein. In an acute form of sarcoidosis, there are expansions of specific TRAV12-1/TRBV2 T cell receptors expressed on BAL CD4+ T cells, indicating that these T cells are trafficking to and expanding in the lung in response to common antigens. The specificity of these pathogenic CD4+T cells in sarcoidosis are currently unknown.

Lack of an Exposure Response and Interaction With HLA-DPβ1 and DRβ1 Polymorphisms in the Development of Beryllium Toxicity in a High Beryllium Exposure Cohort

OBJECTIVE

To evaluate interaction of HLA-DPβ1 and DRβ1 polymorphisms with metrics of beryllium exposure, in the development of beryllium sensitization (BeS) and chronic beryllium disease (CBD).

METHODS

A matched case-control study of 61 CBD, 41 BeS, and 259 controls from two beryllium-processing facilities.

RESULTS

BES and CBD were significantly associated with presence of DPβE69. Dose response of exposure was not observed for the development of BES and CBD with/without adjustment for DPβE69 (P > 0.05). The DRβE71 polymorphism was more common in BeS than CBD after adjusting for exposure and maybe a protective factor (aOR 0.4, 95% CI 0.2 to 0.9) against the progression of BeS to CBD.

CONCLUSION

No exposure-response association was found, which may reflect that the workers in this high exposure cohort were above a threshold level where an exposure-response could be observed.

The Workplace, Social Work, and Social Justice: Framing an Emerging Research and Practice Agenda

Protecting the health and well-being of workers naturally aligns with the social work mission to advance human dignity. The workplace can both create and perpetuate health disparities by shaping health and well-being at multiple levels and in socially patterned ways. Yet workplace issues are rarely on social work research and practice agendas. This article serves as a call to action for social work, as a discipline, to engage with the workplace as a means of advancing the field's core values. It first provides evidence for why engagement with workplaces is critical for advancing social justice. It then presents evidence for the ways in which workplace exposures and experiences, at multiple levels, shape worker health and well-being. Finally, it provides concrete steps for how the skills and values of the social work profession can be applied to the workplace through research, practice, education, and policy efforts, and by extension improve population health and well-being.

Research to Practice Implications of High-Risk Genotypes for Beryllium Sensitization and Disease

OBJECTIVE

Beryllium workers may better understand their genetic susceptibility to chronic beryllium disease (CBD) expressed as population-based prevalence, rather than odds ratios from case-control studies.

METHODS

We calculated CBD prevalences from allele-specific DNA sequences of 853 workers for Human Leukocyte Antigen (HLA)-DPB1 genotypes and groups characterized by number of E69-containing alleles and by calculated surface electronegativity of HLA-DPB1.

RESULTS

Of 18 groups of at least 10 workers with specific genotypes, CBD prevalence was highest, 72.7%, for the HLA-DPB102:01:02/DPB117:01 genotype. Population-based grouped genotypes with two E69 alleles wherein one allele had -9 surface charge had a beryllium sensitization (BeS) of 52.6% and a CBD prevalence of 42.1%.

CONCLUSIONS

The high CBD and BeS prevalences associated with -9-charged E69 alleles and two E69s suggest that workers may benefit from knowing their genetic susceptibility in deciding whether to avoid future beryllium exposure.

Imaging of Occupational Lung Disease

Occupational lung diseases span a variety of pulmonary disorders caused by inhalation of dusts or chemical antigens in a vocational setting. Included in these are the classic mineral pneumoconioses of silicosis, coal worker's pneumoconiosis, and asbestos-related diseases as well as many immune-mediated and airway-centric diseases, and new and emerging disorders. Although some of these have characteristic imaging appearances, a multidisciplinary approach with focus on occupational exposure history is essential to proper diagnosis.

Role of the Hla-Dp Glu 69 and the Tnf-α Tnfa-α2 Gene Markers in Susceptibility to Beryllium Hypersensitivity

Berylliosis is an environmental chronic inflammatory disorder of the lung caused by inhalation of beryllium dusts, characterized by the accumulation of CD4+ T cells and macrophages in the lower respiratory tract. Beryllium presentation to CD4(+) T cells from patients with berylliosis results in T cell activation, and these Be-specific CD4(+) T cells undergo clonal proliferation and Th1-type cytokine production such as interleukin-2, interferon-gamma and tumor necrosis factor-alpha. In exposed workers, genetic susceptibility to this granulomatous disorder is associated with major histocompatibility gene and the TNF-α gene. The HLA-DP glutamic 69 residue was shown to be the MHC genetic marker associated with disease susceptibility; furthermore the TNF-α TNFA-308*2 allele was found to be independently associated with HLA-DP GIu69 in the determination of berylliosis risk.

Beryllium-Induced Hypersensitivity: Genetic Susceptibility and Neoantigen Generation

Chronic beryllium (Be) disease is a granulomatous lung disorder that results from Be exposure in a genetically susceptible host. The disease is characterized by the accumulation of Be-responsive CD4(+) T cells in the lung, and genetic susceptibility is primarily linked to HLA-DPB1 alleles possessing a glutamic acid at position 69 of the β-chain. Recent structural analysis of a Be-specific TCR interacting with a Be-loaded HLA-DP2-peptide complex revealed that Be is coordinated by amino acid residues derived from the HLA-DP2 β-chain and peptide and showed that the TCR does not directly interact with the Be(2+) cation. Rather, the TCR recognizes a modified HLA-DP2-peptide complex with charge and conformational changes. Collectively, these findings provide a structural basis for the development of this occupational lung disease through the ability of Be to induce posttranslational modifications in preexisting HLA-DP2-peptide complexes, resulting in the creation of neoantigens.

Metal-specific CD4+ T-cell responses induced by beryllium exposure in HLA-DP2 transgenic mice

Chronic beryllium disease (CBD) is a granulomatous lung disorder that is associated with the accumulation of beryllium (Be)-specific CD4(+) T cells into the lung. Genetic susceptibility is linked to HLA-DPB1 alleles that possess a glutamic acid at position 69 (βGlu69), and HLA-DPB1*02:01 is the most prevalent βGlu69-containing allele. Using HLA-DP2 transgenic (Tg) mice, we developed a model of CBD that replicates the major features of the human disease. Here we characterized the T-cell receptor (TCR) repertoire of Be-responsive CD4(+) T cells derived from the lungs of Be oxide-exposed HLA-DP2 Tg mice. The majority of Be-specific T-cell hybridomas expressed TCR Vβ6, and a subset of these hybridomas expressed identical or nearly identical β-chains that were paired with different α-chains. We delineated mimotopes that bind to HLA-DP2 and form a complex recognized by Be-specific CD4(+) T cells in the absence of Be. These Be-independent peptides possess an arginine at p5 and a tryptophan at p7 that surround the Be-binding site within the HLA-DP2 acidic pocket and likely induce charge and conformational changes that mimic those induced by the Be(2+) cation. Collectively, these data highlight the interplay between peptides and Be in the generation of an adaptive immune response in metal-induced hypersensitivity.

Gene-environment interaction from international cohorts: impact on development and evolution of occupational and environmental lung and airway disease

Environmental and occupational pulmonary diseases impose a substantial burden of morbidity and mortality on the global population. However, it has been long observed that only some of those who are exposed to pulmonary toxicants go on to develop disease; increasingly, it is being recognized that genetic differences may underlie some of this person-to-person variability. Studies performed throughout the globe are demonstrating important gene-environment interactions for diseases as diverse as chronic beryllium disease, coal workers' pneumoconiosis, silicosis, asbestosis, byssinosis, occupational asthma, and pollution-associated asthma. These findings have, in many instances, elucidated the pathogenesis of these highly complex diseases. At the same time, however, translation of this research into clinical practice has, for good reasons, proceeded slowly. No genetic test has yet emerged with sufficiently robust operating characteristics to be clearly useful or practicable in an occupational or environmental setting. In addition, occupational genetic testing raises serious ethical and policy concerns. Therefore, the primary objective must remain ensuring that the workplace and the environment are safe for all.

An official American Thoracic Society statement: diagnosis and management of beryllium sensitivity and chronic beryllium disease

RATIONALE

Beryllium continues to have a wide range of industrial applications. Exposure to beryllium can lead to sensitization (BeS) and chronic beryllium disease (CBD).

OBJECTIVES

The purpose of this statement is to increase awareness and knowledge about beryllium exposure, BeS, and CBD.

METHODS

Evidence was identified by a search of MEDLINE. The committee then summarized the evidence, drew conclusions, and described their approach to diagnosis and management.

MAIN RESULTS

The beryllium lymphocyte proliferation test is the cornerstone of both medical surveillance and the diagnosis of BeS and CBD. A confirmed abnormal beryllium lymphocyte proliferation test without evidence of lung disease is diagnostic of BeS. BeS with evidence of a granulomatous inflammatory response in the lung is diagnostic of CBD. The determinants of progression from BeS to CBD are uncertain, but higher exposures and the presence of a genetic variant in the HLA-DP β chain appear to increase the risk. Periodic evaluation of affected individuals can detect disease progression (from BeS to CBD, or from mild CBD to more severe CBD). Corticosteroid therapy is typically administered when a patient with CBD exhibits evidence of significant lung function abnormality or decline.

CONCLUSIONS

Medical surveillance in workplaces that use beryllium-containing materials can identify individuals with BeS and at-risk groups of workers, which can help prioritize efforts to reduce inhalational and dermal exposures.

Genetic susceptibility to beryllium: a case-referent study of men and women of working age with sarcoidosis or other chronic lung disease

OBJECTIVE

The study was designed to investigate whether beryllium exposure was related to illness diagnosed as sarcoidosis. Chronic beryllium disease (CBD) and sarcoidosis are clinically and pathologically indistinguishable, with only the presence of beryllium-specific T-lymphocytes identifying CBD. Testing for such cells is not feasible in community studies of sarcoidosis but a second characteristic of CBD, its much greater incidence in those with a glutamic acid residue at position 69 of the HLA-DPB1 gene (Glu69), provides an alternative approach to answering this question.

METHODS

Cases of sarcoidosis aged 18-60 years diagnosed in Alberta, Canada, from 1999 to 2005 were approached through their specialist physician, together with age-matched and sex-matched referents with other chronic lung disease. Referents were grouped into chronic obstructive pulmonary disease (COPD), asthma and other lung disease. Participants completed a telephone questionnaire, including industry-specific questionnaires. DNA was extracted from mailed-in mouthwash samples and genotyped for Glu69. Duration of employment in types of work with independently documented beryllium exposure was calculated.

RESULTS

DNA was extracted for 655 cases (270 Glu69 positive) and 1382 referents (561 positive). No increase in sarcoidosis was seen with either Glu69 or beryllium exposure (none, <10, ≥10 years) as main effects: longer duration in possible beryllium jobs was related to COPD. In Glu69 positive men with exposure ≥10 years, the trend towards increasing rate of COPD was reversed, and a significant interaction of duration of exposure and Glu69 was detected (OR=4.51 95% CI 1.17 to 17.48).

CONCLUSIONS

The gene-environment interaction supports the hypothesis that some cases diagnosed as sarcoidosis result from occupational beryllium exposure.

Ecogenetics of mercury: from genetic polymorphisms and epigenetics to risk assessment and decision-making

The risk assessment of mercury (Hg), in both humans and wildlife, is made challenging by great variability in exposure and health effects. Although disease risk arises following complex interactions between genetic ("nature") and environmental ("nurture") factors, most Hg studies thus far have focused solely on environmental factors. In recent years, ecogenetic-based studies have emerged and have started to document genetic and epigenetic factors that may indeed influence the toxicokinetics or toxicodynamics of Hg. The present study reviews these studies and discusses their utility in terms of Hg risk assessment, management, and policy and offers perspectives on fruitful areas for future research. In brief, epidemiological studies on populations exposed to inorganic Hg (e.g., dentists and miners) or methylmercury (e.g., fish consumers) are showing that polymorphisms in a number of environmentally responsive genes can explain variations in Hg biomarker values and health outcomes. Studies on mammals (wildlife, humans, rodents) are showing Hg exposures to be related to epigenetic marks such as DNA methylation. Such findings are beginning to increase understanding of the mechanisms of action of Hg, and in doing so they may help identify candidate biomarkers and pinpoint susceptible groups or life stages. Furthermore, they may help refine uncertainty factors and thus lead to more accurate risk assessments and improved decision-making.

Identification of multiple public TCR repertoires in chronic beryllium disease

Chronic beryllium disease (CBD) is a granulomatous lung disease characterized by the accumulation of beryllium (Be)-specific CD4(+) T cells in bronchoalveolar lavage. These expanded CD4(+) T cells are composed of oligoclonal T cell subsets, suggesting their recruitment to the lung in response to conventional Ag. In the current study, we noted that all bronchoalveolar lavage-derived T cell lines from HLA-DP2-expressing CBD patients contained an expansion of Be-responsive Vβ5.1(+) CD4(+) T cells. Using Be-loaded HLA-DP2-peptide tetramers, the majority of tetramer-binding T cells also expressed Vβ5.1 with a highly conserved CDR3β motif. Interestingly, Be-specific, Vβ5.1-expressing CD4(+) T cells displayed differential HLA-DP2-peptide tetramer staining intensity, and sequence analysis of the distinct tetramer-binding subsets showed that the two populations differed by a single conserved amino acid in the CDR3β motif. TCR Vα-chain analysis of purified Vβ5.1(+) CD4(+) T cells based on differential tetramer-binding intensity showed differing TCR Vα-chain pairing requirements, with the high-affinity population having promiscuous Vα-chain pairing and the low-affinity subset requiring restricted Vα-chain usage. Importantly, disease severity, as measured by loss of lung function, was inversely correlated with the frequency of tetramer-binding CD4(+) T cells in the lung. Our findings suggest the presence of a dominant Be-specific, Vβ5.1-expressing public T cell repertoire in the lungs of HLA-DP2-expressing CBD patients using promiscuous Vα-chain pairing to recognize an identical HLA-DP2-peptide/Be complex. Importantly, the inverse relationship between expansion of CD4(+) T cells expressing these public TCRs and disease severity suggests a pathogenic role for these T cells in CBD.

T cell recognition of beryllium

Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by a hypersensitivity to beryllium and characterized by the accumulation of beryllium-specific CD4(+) T cells in the lung. Genetic susceptibility to beryllium-induced disease is strongly associated with HLA-DP alleles possessing a glutamic acid at the 69th position of the β-chain (βGlu69). The structure of HLA-DP2, the most prevalent βGlu69-containing molecule, revealed a unique solvent-exposed acidic pocket that includes βGlu69 and represents the putative beryllium-binding site. The delineation of mimotopes and endogenous self-peptides that complete the αβTCR ligand for beryllium-specific CD4(+) T cells suggests a unique role of these peptides in metal ion coordination and the generation of altered self-peptides, blurring the distinction between hypersensitivity and autoimmunity.

Immunotoxicology of beryllium lung disease

Beryllium induces non-caseating granulomatous inflammation in humans exposed to the metal dust or fumes in both occupational and non-occupational settings. The resulting condition, chronic beryllium disease (CBD), affects principally the lungs, lymphatics, and skin and continues to plague modern industry. Beryllium exerts several important immunotoxic effects, including induction of a beryllium-antigen specific adaptive immune response and the triggering of inflammatory and innate immune responses. Genetic susceptibility plays a role in CBD adaptive immune responses, mainly mediated through single nucleotide polymorphisms in HLA-DP and, to a lesser extent, HLA-DR. The adaptive response is characterized by influx and proliferation of CD4+ central and effector memory T cells expressing Th1 cytokines. Insights into the immunopathogenesis of CBD have implications for the understanding of other immune-mediated granulomatous disorders and for metal antigen behavior.

The role of lymphocyte proliferation tests in assessing occupational sensitization and disease

PURPOSE OF REVIEW

Lymphocyte proliferation testing (LPT) is used in diagnosing occupationally acquired delayed-type hypersensitivity. It has been used in beryllium-health effects, and its role is expanding in metal allergy. It may find application in diagnosis of other sensitizers.

RECENT FINDINGS

Use of the beryllium LPT (BeLPT) in medical surveillance identifies beryllium sensitization at low exposure with chronic beryllium disease (CBD) that leads to physiologic impairment and need for immunosuppressive medications. New studies indicate that both beryllium exposure and genetic variation are associated with increased risk of CBD. Borderline positive BeLPTs warrant inclusion into diagnostic algorithms. Furthermore, use of LPTs to diagnose metal allergy is being proposed in diagnosis of chromium allergy and hypersensitivity to surgical implants. New occupational sensitizers continue to be identified including metalworking fluids, the sterilizing agent ortho-phthalaldehyde and the solvent para-chlorobenzotrifluoride. Use of LPT in occupational surveillance to these agents and other known sensitizers may play expanding roles.

SUMMARY

Lymphocyte proliferation testing serves a valuable role in diagnosing occupational sensitization, as demonstrated with beryllium-health effects, as cases continue to be found at low exposure levels. The use of LPTs in diagnosing contact allergy is expanding, and new applications may be identified in human and animal studies.

Spectrum of HLA associations: the case of medically refractory pediatric acute lymphoblastic leukemia

Although studies of HLA and disease now date back some 50 years, a principled understanding of that relationship has been slow to emerge. Here, we examine the associations of three HLA loci with medically refractory pediatric acute lymphoblastic leukemia (pALL) patients in a case-control study involving 2,438 cases and 41,750 controls. An analysis of alleles from the class I loci, HLA-A and HLA-B, and the class II locus DRB1 illuminates a spectrum of extremely significant allelic associations conferring both predisposition and protection. Genotypes constructed from predisposing, protective, and neutral allelic categories point to an additive mode of disease causation. For all three loci, genotypes homozygous for predisposing alleles are at highest disease risk while the favorable effect of homozygous protective genotypes is less striking. Analysis of A-B and B-DRB1 haplotypes reveals locus-specific differences in disease effects, while that all three loci influence pALL; the influence of HLA-B is greater than that of HLA-A, and the predisposing effect of DRB1 exceeds that of HLA-B. We propose that the continuum in disease susceptibility suggests a system in which many alleles take part in disease predisposition based on differences in binding affinity to one or a few peptides of exogenous origin. This work provides evidence that an immune response mediated by alleles from several HLA loci plays a critical role in the pathogenesis of pALL, adding to the numerous studies pointing to a role for an infectious origin in pALL.

Mutagenesis of beryllium-specific TCRs suggests an unusual binding topology for antigen recognition

Unconventional Ags, such as metals, stimulate T cells in a very specific manner. To delineate the binding landscape for metal-specific T cell recognition, alanine screens were performed on a set of Be-specific TCRs derived from the lung of a chronic beryllium disease patient. These TCRs are HLA-DP2-restricted and express nearly identical TCR Vβ5.1 chains coupled with different TCR α-chains. Site-specific mutagenesis of all amino acids comprising the CDRs of the TCRA and TCRB genes showed a dominant role for Vβ5.1 residues in Be recognition, with little contribution from the TCR α-chain. Solvent-exposed residues along the α-helices of the HLA-DP2 α- and β-chains were also mutated to alanine. Two β-chain residues, located near the proposed Be binding site of HLA-DP2, played a dominant role in T cell recognition with no contribution from the HLA-DP2 α-chain. These findings suggest that Be-specific T cells recognize Ag using an unconventional binding topology, with the majority of interactions contributed by TCR Vβ5.1 residues and the HLA-DP2 β1-chain. Thus, unusual docking topologies are not exclusively used by autoreactive T cells, but also for the recognition of unconventional metal Ags, such as Be.

Genetic variability in susceptibility to occupational respiratory sensitization

Respiratory sensitization can be caused by a variety of substances at workplaces, and the health and economic burden linked to allergic respiratory diseases continues to increase. Although the main factors that affect the onset of the symptoms are the types and intensity of allergen exposure, there is a wide range of interindividual variation in susceptibility to occupational/environmental sensitizers. A number of gene variants have been reported to be associated with various occupational allergic respiratory diseases. Examples of genes include, but are not limited to, genes involved in immune/inflammatory regulation, antioxidant defenses, and fibrotic processes. Most of these variants act in combination with other genes and environmental factors to modify disease progression, severity, or resolution after exposure to allergens. Therefore, understanding the role of genetic variability and the interaction between genetic and environmental/occupational factors provides new insights into disease etiology and may lead to the development of novel preventive and therapeutic strategies. This paper will focus on the current state of knowledge regarding genetic influences on allergic respiratory diseases, with specific emphasis on diisocyanate-induced asthma and chronic beryllium disease.

Exposure and genetics increase risk of beryllium sensitisation and chronic beryllium disease in the nuclear weapons industry

OBJECTIVES

Beryllium sensitisation (BeS) and chronic beryllium disease (CBD) are caused by exposure to beryllium with susceptibility affected by at least one well-studied genetic host factor, a glutamic acid residue at position 69 (E69) of the HLA-DPβ chain (DPβE69). However, the nature of the relationship between exposure and carriage of the DPβE69 genotype has not been well studied. The goal of this study was to determine the relationship between DPβE69 and exposure in BeS and CBD.

METHODS

Current and former workers (n=181) from a US nuclear weapons production facility, the Y-12 National Security Complex (Oak Ridge, Tennessee, USA), were enrolled in a case-control study including 35 individuals with BeS and 19 with CBD. HLA-DPB1 genotypes were determined by PCR-SSP. Beryllium exposures were assessed through worker interviews and industrial hygiene assessment of work tasks.

RESULTS

After removing the confounding effect of potential beryllium exposure at another facility, multivariate models showed a sixfold (OR 6.06, 95% CI 1.96 to 18.7) increased odds for BeS and CBD combined among DPβE69 carriers and a fourfold (OR 3.98, 95% CI 1.43 to 11.0) increased odds for those exposed over an assigned lifetime-weighted average exposure of 0.1 μg/m(3). Those with both risk factors had higher increased odds (OR 24.1, 95% CI 4.77 to 122).

CONCLUSION

DPβE69 carriage and high exposure to beryllium appear to contribute individually to the development of BeS and CBD. Among workers at a beryllium-using facility, the magnitude of risk associated with either elevated beryllium exposure or carriage of DPβE69 alone appears to be similar.

Risk of chronic beryllium disease by HLA-DPB1 E69 genotype and beryllium exposure in nuclear workers

RATIONALE

Beryllium sensitization (BeS) and chronic beryllium disease (CBD) are determined by at least one genetic factor, a glutamic acid at position 69 (E69) of the HLA-DPB1 gene, and by exposure to beryllium. The relationship between exposure and the E69 genotype has not been well characterized.

OBJECTIVES

The study goal was to define the relationship between beryllium exposure and E69 for CBD and BeS.

METHODS

Workers (n = 386) from a U.S. nuclear weapons facility were enrolled into a case-control study (70 BeS, 61 CBD, and 255 control subjects). HLA-DPB1 genotypes were determined by sequence-specific primer-polymerase chain reaction. Beryllium exposures were reconstructed on the basis of worker interviews and historical exposure measurements.

MEASUREMENTS AND MAIN RESULTS

Any E69 carriage increased odds for CBD (odds ratio [OR], 7.61; 95% confidence interval [CI], 3.66-15.84) and each unit increase in lifetime weighted average exposure increased the odds for CBD (OR, 2.27; 95% CI, 1.26-4.09). Compared with E69-negative genotypes, a single E69-positive *02 allele increased the odds for BeS (OR, 12.01; 95% CI, 4.28-33.71) and CBD (OR, 3.46; 95% CI, 1.42-8.43). A single non-*02 E69 allele further increased the odds for BeS (OR, 29.54; 95% CI, 10.33-84.53) and CBD (OR, 11.97; 95% CI, 5.12-28.00) and two E69 allele copies conferred the highest odds for BeS (OR, 55.68; 95% CI, 14.80-209.40) and CBD (OR, 22.54; 95% CI, 7.00-72.62).

CONCLUSIONS

E69 and beryllium exposure both contribute to the odds of CBD. The increased odds for CBD and BeS due to E69 appear to be differentially distributed by genotype, with non-*02 E69 carriers and E69 homozygotes at higher odds than those with *02 genotypes.

Linking genetic susceptibility and T cell activation in beryllium-induced disease

Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by beryllium (Be) exposure in the workplace. It is characterized by the accumulation of Be-specific CD4(+) T cells in the lung as well as persistent lung inflammation, culminating in the development of lung fibrosis. CBD occurs in 2 to 16% of Be-exposed workers depending on the individuals' genetic susceptibility and the characteristics of the exposure. Genetic susceptibility to Be-induced disease has been linked to major histocompatibility complex class II molecules. In particular, HLA-DP alleles possessing a glutamic acid at the 69th position of the beta-chain (betaGlu69) are most strongly linked to disease susceptibility. The HLA-DP alleles that present Be to T cells match those implicated in the genetic susceptibility, suggesting that the HLA contribution to disease is based on the ability of those molecules to bind and present Be to T cells. However, the structural features of betaGlu69-containing HLA-DP molecules that explain the disease association remain unknown. We have recently crystallized HLA-DP2, which is the most prevalent of the betaGlu69-containing HLA-DP molecules. Its unique structure, which includes surface exposure of betaGlu69, provides an explanation of the genetic linkage between betaGlu69-containing HLA-DP alleles and Be-induced disease.

Deficient and dysfunctional regulatory T cells in the lungs of chronic beryllium disease subjects

RATIONALE

Chronic beryllium disease (CBD) is a CD4(+) T cell-mediated disorder characterized by persistent lung inflammation. Naturally occurring regulatory T (T(reg)) cells modulate adaptive immune responses. The role of this T-cell subset in beryllium-induced lung disease is unknown.

OBJECTIVES

The aim of this study was to determine whether dysfunctional T(reg) cells in the lung contribute to the "unchecked" inflammatory response that characterizes CBD.

METHODS

Using blood and bronchoalveolar lavage (BAL) cells from normal control subjects and individuals with beryllium-induced disease, we determined the frequency and function of naturally occurring T(reg) cells.

MEASUREMENTS AND MAIN RESULTS

A significantly decreased percentage and expression of FoxP3 in BAL CD4(+) T cells from CBD patients compared with beryllium-sensitized subjects was seen, and the percentage of FoxP3-expressing CD4(+) T(reg) cells in BAL inversely correlated with disease severity. In contrast to blood T(reg) cells derived from beryllium-sensitized subjects and patients with CBD that completely suppressed blood responder T-cell proliferation, BAL FoxP3-expressing T(reg) cells from patients with CBD are unable to suppress anti-CD3-mediated BAL T-cell proliferation. Mixing studies showed that blood T(reg) cells are capable of suppressing autologous BAL responder T cells. Conversely, BAL CD4(+) T(reg) cells are incapable of suppressing blood T cells, confirming that the failure of BAL T(reg) cells to suppress T-cell proliferation is caused by a dysfunctional T(reg) cell subset and not by resistance of BAL effector T cells to suppression.

CONCLUSIONS

These findings suggest that the deficient and dysfunctional T(reg) cells in the lung of patients with CBD contribute to the persistent inflammatory response in this disease.

Current treatment of chronic beryllium disease

The current mainstay of management of chronic beryllium disease involves cessation of beryllium exposure and use of systemic corticosteroids. However, there are no randomized controlled trials to assess the effect of these interventions on the natural history of this disease. Despite this limitation, it is prudent to remove patients with chronic beryllium disease from further exposure and consider treating progressive disease early with long-term corticosteroids. The effect of treatment should be monitored using pulmonary function tests and high-resolution computed tomography of the chest. However, once pulmonary fibrosis has developed, corticosteroid therapy cannot reverse the damage.

Genetic determinants of sensitivity to beryllium in mice

Chronic beryllium disease (CBD), an irreversible, debilitating granulomatous lung disease is caused by exposure to beryllium. This occupational hazard occurs in primary production and machining of Be-metal, BeO, beryllium - containing alloys, and other beryllium products. CBD begins as an MHC Class II-restricted, T(H)1 hypersensitivity, and the Human Leukocyte Antigen, HLA-DPB1E(69), is associated with risk of developing CBD. Because inbred strains of mice have not provided good models of CBD to date, three strains of HLA-DPB1 transgenic mice in an FVB/N background were developed; each contains a single allele of HLA-DPB1 that confers a different magnitude of risk for chronic beryllium disease: HLA-DPB1*0401 (OR approximately 0.2), HLA-DPB1*0201 (OR approximately 3), and HLA-DPB1*1701 (OR approximately 46). The mouse ear swelling test (MEST) was employed to determine if these different alleles would support a hypersensitivity response to beryllium. Mice were first sensitized on the back and subsequently challenged on the ear. In separate experiments, mice were placed into one of three groups (sensitization/challenge): C/C, C/Be, and Be/Be. In the HLA-DPB1*1701 mice, the strain with the highest risk transgene, the Be/Be group was the only group that displayed significant maximum increased ear thickness of 19.6% +/- 3.0% over the baseline measurement (p < 0.05). No significant changes were observed in the other transgenic strains for any treatment condition. In addition, inter-strain differences in response to beryllium in seven inbred strains were investigated through use of the MEST, these included: FVB/N, AKR, Balb/c, C3H/HeJ, C57/BL6, DBA/2, and SJL/J. The FVB/N strain was least responsive, while the SJL/J and C57/BL6 strains were the highest responders. Our results suggest that the HLA-DPB1*1701 transgene product is an important risk factor for induction of the beryllium-sensitive phenotype. This model should be a useful tool for investigating beryllium sensitization.

Recent advances in understanding the biomolecular basis of chronic beryllium disease: a review

In this review we summarize the work conducted over the past decade that has advanced our knowledge of pulmonary diseases associated with exposure to beryllium that has provided a molecular-based understanding of the chemistry, immunopathology, and immunogenetics of beryllium toxicity. Beryllium is a strong and lightweight metal that generates and reflects neutrons, resists corrosion, is transparent to X-rays, and conducts electricity. Beryllium is one of the most toxic elements on the periodic table, eliciting in susceptible humans (a) an allergic immune response known as beryllium sensitization (BeS); (b) acute beryllium disease, an acutely toxic, pneumonitis-like lung condition resulting from exposure to high beryllium concentrations that are rarely seen in modern industry; and (c) chronic beryllium disease (CBD) following either high or very low levels of exposure. Because of its exceptional strength, stability, and heat-absorbing capability, beryllium is used in many important technologies in the modern world. In the early 1940s, beryllium was recognized as posing an occupational hazard in manufacturing and production settings. Although acute beryllium disease is now rare, beryllium is an insidious poison with a latent toxicity and the risk of developing CBD persists. Chronic beryllium disease-a systemic granulomatous lung disorder caused by a specific delayed immune response to beryllium within a few months to several decades after exposure-has been called the "unrecognized epidemic". Although not a disease in itself, BeS, the innate immune response to beryllium identified by an abnormal beryllium lymphocyte proliferation test result, is a population-based predictor of CBD. Genetic susceptibility to CBD is associated with alleles of the major histocompatibility gene, human leukocyte antigen DP (HLA-DP) containing glutamic acid at the 69th position of the beta chain (HLA-DPbeta-E69). Other genes are likely to be involved in the disease process, and research on this issue is in progress. The current Occupational Safety & Health Administration permissible exposure limit of 2 microg/m3 has failed to protect workers from BeS/CBD. As a safe exposure limit that will not lead to BeS or CBD has not yet been determined, the realization that the risk of CBD persists has led to a renaissance in research on the effects of the metal on human health. Current data support further reductions in exposure levels to help minimize the incidence of CBD. Steps that would directly impact both the power of epidemiologic studies and the cost of surveillance would be to develop and validate improved screening and diagnostic tests, and to identify more genetic factors that affect either sensitization or disease process. The major focus of this review is the recent research on the cellular and molecular basis of beryllium sensitization and disease, using a multidisciplinary approach of bioinorganic chemistry and immunology. First we present a historical background of beryllium exposure and disease, followed by occurrence of beryllium in the environment, toxicokinetics, biological effects, beryllium lung disease, and other human health effects.

Immunology of chronic beryllium disease

PURPOSE OF REVIEW

This review discusses the immunology of chronic beryllium disease. It addresses the importance of the interaction between class II molecules and the T cells that recognize beryllium, along with the subsequent immune response that results in sensitization and disease, and genetic factors leading to variation in this response.

RECENT FINDINGS

HLA-DPB1 with a glutamic acid at amino acid position 69 (Glu69) confers increased risk of beryllium sensitization and is not specific for chronic beryllium disease. The degree of negative surface charge of the molecule may increase risk of chronic beryllium disease but not sensitization. In the absence of Glu69, HLA-DRB1 alleles may function in beryllium presentation, increasing the risk of chronic beryllium disease. The T-cell response as assessed by the beryllium lymphocyte proliferation test is dependent on central memory T-cells, while Th1 cytokine secretion leading to granulomatous inflammation and chronic beryllium disease is dependent on the activity of effector memory T cells. Polymorphisms in cytokine genes, such as the TGF-beta1 gene, also affect the risk of chronic beryllium disease and more severe disease.

SUMMARY

The current diagnostic criteria for sensitization and chronic beryllium disease rely on the beryllium lymphocyte proliferation test. By understanding the novel immunologic mechanisms and genetic factors associated with sensitization and chronic beryllium disease, we may improve our ability to detect beryllium health effects with new diagnostics, and hopefully refine therapies for disease.

Exposure-response in occupational allergy

PURPOSE OF REVIEW

This review examines the relationship between exposure to workplace allergens and the risk of developing occupational allergy.

RECENT FINDINGS

Evidence suggests that the risk of developing occupational allergy increases with allergen exposure; however, with some occupational allergens, this exposure-response relationship is more complex. In laboratory animal workers, the risk of developing occupational allergy increases with exposure, except at high allergen exposure when there is a reduction in sensitization. This attenuation of specific immunoglobulin E antibody is associated with increased specific immunoglobulin G4 antibodies, which are likely to play a protective role, leading to a form of natural tolerance. Exposure-response relationships are also very dependent on the genetic susceptibility of the individual. The interaction between genes, occupational allergens and other cofactors in the environment, such as endotoxin, are also important risk factors in the development of sensitization and asthma.

SUMMARY

Occupational allergy provides a good opportunity to understand the complex relationships between exposure to allergens in the workplace, interaction with genes and the coexposures with other factors in the working environment and the increased risk of developing occupational allergy.

Role of high-affinity HLA-DP specific CLIP-derived peptides in beryllium binding to the HLA-DPGlu69 berylliosis-associated molecules and presentation to beryllium-sensitized T cells

Berylliosis is driven by the accumulation in the lung of beryllium-specific T helper type 1 (Th1) cells recognizing beryllium as antigen when presented principally by human leucocyte antigen DP molecules carrying a glutamate at position beta69 (HLA-DPGlu69). This study was designed to clarify the precise role of peptides in beryllium binding to the HLA-DP groove's pocket 4 and to identify peptides with higher affinity for pocket 4 that might prevent beryllium presentation and T-cell stimulation. Beryllium/HLA-DP interactions were analysed by the ability of beryllium to compete with CLIP and CLIP-derived peptides to HLA-DPGlu69 soluble molecule. The CLIP-derived low-affinity peptide CLIP-AA, could not outcompete beryllium; while the CLIP-derived high-affinity peptides CLIP-YY, CLIP-QY and CLIP-RF were only marginally influenced by the presence of beryllium in the competition assay. The effect of these CLIP-derived high-affinity peptides on beryllium presentation was determined by measuring interferon-gamma (IFN-gamma) release upon beryllium stimulation of peripheral blood mononuclear cells obtained from beryllium-hypersensitive subjects. CLIP-YY did inhibit beryllium presentation and T-cell activation, while CLIP-QY and CLIP-RF markedly enhanced the IFN-gamma response to beryllium. Anti-HLA-DP monoclonal antibody blocked the beryllium-induced IFN-gamma release in the presence of CLIP-QY (88%) and CLIP-RF (76%). A similar effect was observed for CLIP-YY capability to block IFN-gamma release by beryllium stimulation in the presence of CLIP-QY (79%) and CLIP-RF (76%). Overall, these data support the proposal that HLA-DP high-affinity peptides might be used as a model for specific berylliosis therapy.

Impact of negatively charged patches on the surface of MHC class II antigen-presenting proteins on risk of chronic beryllium disease

Chronic beryllium disease (CBD) is a granulomatous lung disease that occurs primarily in workers who are exposed to beryllium dust or fumes. Although exposure to beryllium is a necessary factor in the pathobiology of CBD, alleles that code for a glutamic acid residue at the 69th position of the HLA-DPbeta1 gene have previously been found to be associated with CBD. To date, 43 HLA-DPbeta1 alleles that code for glutamic acid 69 (E69) have been described. Whether all of these E69 coding alleles convey equal risk of CBD is unknown. The present study demonstrates that, on the one hand, E69 alleloforms of major histocompatibility complex class II antigen-presenting proteins with the greatest negative surface charge convey the highest risk of CBD, and on the other hand, irrespective of allele, they convey equal risk of beryllium sensitization (BeS). In addition, the data suggest that the same alleles that cause the greatest risk of CBD are also important for the progression from BeS to CBD. Alleles convey the highest risk code for E26 in a constant region and for E69, aspartic acid 55 (D55), E56, D84 and E85 in hypervariable regions of the HLA-DPbeta1 chain. Together with the calculated high binding affinities for beryllium, these results suggest that an adverse immune response, leading to CBD, is triggered by chemically specific metal-protein interactions.

Genetic susceptibility to occupational exposures

Because of their high prevalence in the general population, genetic variants that determine susceptibility to environmental exposures may contribute greatly to the development of occupational diseases in the setting of specific exposures occurring in the workplace. Studies investigating genetic susceptibilities in the workplace may: (1) provide mechanistic insight into the aetiology of disease, in particular the determination of environmentally responsive genes; (2) identify susceptible subpopulations with respect to exposure; and (3) provide valuable input in setting occupational exposure limits by taking genetic susceptibility into account. Polymorphisms in the NAT2 and the HLA-DPB1(G)(lu69) genes provide classic examples of how genetic susceptibility markers have a clear role in identifying disease risk in bladder cancer and chronic beryllium disease, respectively. For diseases with more complex and multifactorial aetiology such as occupational asthma and chronic airways disease, susceptibility studies for selected genetic polymorphisms provide additional insight into the biological mechanisms of disease. Even when polymorphisms for genetic susceptibility have a clear role in identifying disease risk, the value of wide scale genetic screening in occupational settings remains limited due to primarily ethical and social concerns. Thus, large scale genetic screening in the workplace is not currently recommended.

TNF-alpha polymorphisms in chronic beryllium disease and beryllium sensitization

OBJECTIVE

Tumor necrosis factor-alpha (TNF-alpha) is a potent cytokine involved in normal immune functions. The aim of this study was to investigate if there is an association between chronic beryllium disease or beryllium sensitization and two variants of the TNF-alpha gene located at -308 and -238 called TNF-alpha-308*02 and TNF-alpha-238*02.

METHODS

TNF-alpha-308 and TNF-alpha-238 genotyping was conducted in a large, population-based cohort consisting of 886 beryllium workers (92 individuals with chronic beryllium disease, 64 who were beryllium sensitized, and 730 individuals without sensitization or disease).

RESULTS

The odds of chronic beryllium disease in the presence of at least one TNF-alpha-308*02 or TNF-alpha-238*02 allele was not significant (OR=1.0; 95% CI=0.7, 1.7 and OR=0.8; 95% CI=0.4, 1.6). This was true regardless of whether a worker was homozygous or heterozygous for TNF-alpha-308*02 or TNF-alpha-238*02. Similarly, neither allele was associated with sensitization (P>0.05).

CONCLUSIONS

Unlike an earlier report, there was no association between these specific TNF-alpha alleles and either chronic beryllium disease or sensitization to beryllium.

Beryllium: A Modern Industrial Hazard

Beryllium exposure can cause a granulomatous lung disease in workers who develop a lymphocyte-mediated sensitization to the metal. Workers in diverse industries are at risk because beryllium's properties are critical to nuclear, aerospace, telecommunications, electronic, metal alloy, biomedical, and semiconductor industries. The occupational air concentration standard's failure to protect beryllium workers is driving many scientific and occupational health advances. These developments include study of bioavailability of different physicochemical forms of beryllium, medical surveillance to show effectiveness of skin protection in preventing sensitization in high-risk processes, gene-environment interaction, transgenic mice for use in experimental research, and risk-based management of industrial exposures in the absence of effective exposure-response information. Beryllium sensitization and disease prevention are paradigms for much broader public health action in both occupational and general population settings.

Ethical considerations in testing workers for the -Glu69 marker of genetic susceptibility to chronic beryllium disease

OBJECTIVE

The most compelling real-world example of genetic testing for susceptibility to a workplace exposure involves those industries that process or fabricate beryllium. We examined ethical issues associated with testing for susceptibility to chronic beryllium disease.

METHODS

Using ethical and clinical criteria, we examined voluntary employer-sponsored testing programs in which individual results are reported directly to workers in a confidential manner.

RESULTS

Under reasonable assumptions, the longitudinal positive predictive value of the HLA-DPB1-Glu69 marker of susceptibility to beryllium disease is 12%. Interpretive challenges further limit the utility of the test and may inadvertently suggest a false sense of safety among workers. Concerns about confidential participation and pressures to be tested also must be addressed.

CONCLUSIONS

Difficulties surrounding the interpretation of the HLA-DPB1-Glu69 marker, lack of assurance regarding the protection of worker confidentiality, and the potential lowering of social barriers to the implementation of mandatory worker screening combine to make testing beryllium workers inappropriate at this time.

Self-presentation of beryllium by BAL CD4+ T cells: T cell-T cell interactions and their potential role in chronic beryllium disease

Chronic beryllium disease (CBD) is characterized pathologically by granulomatous inflammation in the lung, composed of a large core of epithelioid cells surrounded by a dense shell of CD4+ T cells. Using beryllium-specific CD4+ T cell lines derived from the bronchoalveolar lavage (BAL) fluid of CBD patients, we show that purified CD4+ T cells produced significant amounts of IFN-gamma and TNF-alpha upon exposure to beryllium in the absence of antigen-presenting cells (APC). However, unlike BAL T cells stimulated by beryllium in the presence of APC, self-presentation by BAL T cells did not induce detectable IL-2 production, and in its absence these activated T cells die from programmed cell death. Resting BAL CD4+ T cells constitutively express high levels of HLA-DP, lymphocyte function-associated antigen 1 (LFA-1) and ICAM-3. When stimulated with beryllium/APC, the adhesion molecule ICAM-1 was up-regulated, as well as several costimulation molecules including CD28, OX-40 (CD134), 4-1-BB (CD137) and B7-1 (CD80). Notably, CD28 was not up-regulated during self-presentation by BAL T cells, and these cells do not express OX-40L, suggesting that lack of appropriate costimulation was responsible for programmed cell death observed upon beryllium self-presentation. Restricting anti-MHC class II mAb completely eliminated beryllium-induced T cell proliferation during self-presentation and significantly reduced IFN-gamma and TNF-alpha production. Our data demonstrate for the first time that self-presentation by BAL T cells in response to beryllium can occur ex vivo, in the absence of professional APC, with a specific dependence on T cell-expressed MHC class II molecules and exogenous IL-2 for survival.

T cell recognition in chronic beryllium disease

Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by beryllium exposure in the workplace and is characterized by the accumulation of beryllium-specific CD4(+) T cells. Depending on genetic susceptibility and the nature of the exposure, CBD occurs in up to 20% of exposed workers. Genetic susceptibility has been associated with particular HLA-DP alleles, especially those possessing a negatively charged glutamic acid residue at the 69th position of the beta-chain. The mechanism for this association lies in the ability of these HLA-DP molecules to bind and present beryllium to pathogenic CD4(+) T cells. Large numbers of effector memory, beryllium-specific CD4(+) T cells are recruited to the lung of these subjects and secrete Th1-type cytokines upon beryllium recognition. The presence of circulating beryllium-specific CD4(+) T cells directly correlates with the severity of lymphocytic alveolitis. With the presence of a known antigenic stimulus, CBD serves as an important model of immune-mediated, organ destruction. Thus, our findings in CBD have important implications for studies in autoimmune diseases, in particular those with an unknown inciting antigen and an inaccessible target organ.

Gene expression influences on metal immunomodulation

Heavy metals in the environment originate from both human activities and natural processes. Exposure to these metals can result in important changes to immune activity. Depending on the metal and dose, these changes can result in enhanced immune function, diminished immune responses, or altered responses that produce autoimmune disease. One of the intriguing aspects of these various phenomena are the multiple points of interaction with cellular machinery at which metals elicit these changes. The individual sections of this review serve to underscore the variety of targets that can be altered by exposure to heavy metals, and provide some comparisons between the effects of specific heavy metals on the immune system. These observations may ultimately lead us to a comprehensive understanding of the mechanisms by which metals alter the immune system, and may enable the development of countermeasures to offset these effects.

Immunogenetic factors in beryllium sensitization and chronic beryllium disease

Exposure to beryllium in the workplace can cause beryllium sensitization and chronic beryllium disease. Sensitization to beryllium can be detected in the laboratory using the beryllium lymphocyte proliferation test. It was shown that anti-HLA antibodies could block the beryllium-specific response in the beryllium lymphocyte proliferation test, thereby implicating HLA genes in chronic beryllium disease. A supratypic genetic marker, HLA-DPB1*E69, was found to be strongly associated with immunologic sensitization to beryllium and chronic beryllium disease in beryllium workers. However, there are 40 HLA-DPB1 gene variants that have E69 but that also have other DNA sequence variations. The purpose of the study was to evaluate the evidence for potential differential susceptibility that may be associated with the physical characteristics of HLA protein molecules for which different HLA-DPB1*E69 variants code; that is, do some HLA-DPB1*E69 variants convey higher risk of beryllium sensitization and chronic beryllium disease than others. To do this, two approaches were pursued: first, detailed analysis of the findings from the published literature was performed, and second, computational chemistry was used to seek clues concerning the physical properties of the HLA protein molecules for which these alleles code. Among the 40 HLA-DPB1 gene variants that code for E69, molecular epidemiological studies have suggested a risk hierarchy, where some variants appear to convey low to moderate risk of chronic beryllium disease (e.g., HLA-DPB1*0201, approximately 3-fold increased risk), some convey an intermediate risk (e.g., HLA-DPB1*1901, approximately 5-fold) and others convey high risk (e.g., HLA-DPB1*1701, >10-fold). Molecular modeling has been used to further investigate a potential mechanistic basis for these observations. We found a strong correlation between the hierarchical order of risk of chronic beryllium disease associated with specific alleles and the predicted surface electrostatic potential and charge of the corresponding isotypes. Therefore, when alleles were grouped by the relative negative charge on the molecules for which they code, the data suggest that those alleles associated with the most negatively charged proteins carry the greatest risk of beryllium sensitization and disease.

Beryllium Presentation to CD4+ T Cells Is Dependent on a Single Amino Acid Residue of the MHC Class II β-Chain

Chronic beryllium disease (CBD) is characterized by a CD4+ T cell alveolitis and granulomatous inflammation in the lung. Genetic susceptibility to this disease has been linked with HLA-DP alleles, particularly those possessing a glutamic acid at position 69 (Glu69) of the beta-chain. However, 15% of CBD patients do not possess a Glu69-containing HLA-DP allele, suggesting that other MHC class II alleles may be involved in disease susceptibility. In CBD patients without a Glu69-containing HLA-DP allele, an increased frequency of HLA-DR13 alleles has been described, and these alleles possess a glutamic acid at position 71 of the beta-chain (which corresponds to position 69 of HLA-DP). Thus, we hypothesized that beryllium presentation to CD4+ T cells was dependent on a glutamic acid residue at the identical position of both HLA-DP and -DR. The results show that HLA-DP Glu69- and HLA-DR Glu71-expressing molecules are capable of inducing beryllium-specific proliferation and IFN-gamma expression by lung CD4+ T cells. Using fibroblasts expressing mutated HLA-DP2 and -DR13 molecules, beryllium recognition was dependent on the glutamic acid at position 69 of HLA-DP and 71 of HLA-DR, suggesting a critical role for this amino acid in beryllium presentation to Ag-specific CD4+ T cells. Thus, these results demonstrate that a single amino acid residue of the MHC class II beta-chain dictates beryllium presentation and potentially, disease susceptibility.

Identification of HLA-DRPhebeta47 as the susceptibility marker of hypersensitivity to beryllium in individuals lacking the berylliosis-associated supratypic marker HLA-DPGlubeta69

Background

Susceptibility to beryllium (Be)-hypersensitivity (BH) has been associated with HLA-DP alleles carrying a glutamate at position 69 of the HLA-DP β-chain (HLA-DPGlu69) and with several HLA-DP, -DQ and -DR alleles and polymorphisms. However, no genetic associations have been found between BH affected subjects not carrying the HLA-DPGlu69 susceptibility marker.

Methods

In this report, we re-evaluated an already described patient populations after 7 years of follow-up including new 29 identified BH subjects. An overall population 36 berylliosis patients and 38 Be-sensitization without lung granulomas and 86 Be-exposed controls was analysed to assess the role of the individual HLA-class II polymorphisms associated with BH-susceptibility in HLA-DPGlu69 negative subjects by univariate and multivariate analysis.

Results

As previously observed in this population the HLA-DPGlu69 markers was present in higher frequency in berylliosis patients (31 out of 36, 86%) than in Be-sensitized (21 out of 38, 55%, p = 0.008 vs berylliosis) and 41 out of 86 (48%, p < 0.0001 vs berylliosis, p = 0.55 vs Be-sensitized) Be-exposed controls.

However, 22 subjects presenting BH did not carry the HLA-DPGlu69 marker. We thus evaluated the contribution of all the HLA-DR, -DP and -DQ polymorphisms in determining BH susceptibility in this subgroup of HLA-Glu69 subjects. In HLA-DPGlu69-negatives a significant association with BH was found for the HLA-DQLeu26, for the HLA-DRB1 locus residues Ser13, Tyr26, His32, Asn37, Phe47 and Arg74 and for the HLA-DRB3 locus clusterized residues Arg11, Tyr26, Asp28, Leu38, Ser60 and Arg74. HLA-DRPhe47 (OR 2.956, p < 0.05) resulting independently associated with BH. Further, Be-stimulated T-cell proliferation in the HLA-DPGlu69-negative subjects (all carrying HLA-DRPhe47) was inhibited by the anti-HLA-DR antibody (range 70–92% inhibition) significantly more than by the anti-HLA-DP antibody (range: 6–29%; p < 0.02 compared to anti-HLA-DR) while it was not affected by the anti-HLA-DQ antibody.

Conclusion

We conclude that HLA-DPGlu69 is the primary marker of Be-hypersensitivity and HLA-DRPhe47 is associated with BH in Glu69-negative subjects, likely playing a role in Be-presentation and sensitization.

Bérylliose Pulmonaire Chronique : un modèle d’interaction entre environnement et prédisposition génétique (1re partie)

INTRODUCTION

The physico-chemical properties of beryllium (Be) are crucial for high technology industries. The inhalation of beryllium may cause, in certain individuals, a specific sensitisation (BeS) and lead, in some of them, to a pulmonary granulomatosis called chronic pulmonary berylliosis (CPB).

BACKGROUND

Although there is no linear relationship between the level of exposure to Be and the risks of BeS and CPB, the highest exposures are associated with an increased risk. The specific influences of the chemical composition, the solubility and different types of Be on the risk of BeS an CPB are poorly understood. Insoluble particles of small diameter are probably associated with an increased risk. Many studies have reported the role of a genetic predisposition in the risk of BeS and CPB. At present the role of HLA-DPB1 Glu69 in sensitisation to Be is the best studied.

CONCLUSION

Sensitisation to Be and CPB result from the combination of exposure and predisposing genetic polymorphisms. CPB is a model for the understanding of the pathology of certain ideopathic pulmonary granulomatoses such as sarcoidosis.

Function associated transforming growth factor-beta gene polymorphism in chronic beryllium disease

Chronic beryllium disease (CBD) is a rare occupational, granulomatous lung disease clinically resembling sarcoidosis. The immune response to beryllium is thought to depend on genetic susceptibility. Although a glutamic acid in position 69 of the human leukocyte antigen-DP beta chain (HLA-DPB1-Glu69) is associated with the development of CBD, it cannot fully explain susceptibility. It is likely that additionally other genes are involved in regulating the immune and inflammatory response in the pathogenesis of this disease. Functional gene polymorphisms (PMs) of the tumor necrosis factor (TNF)A and transforming growth factor (TGF) beta(1) genes are suspected to modify the course of granulomatous disorders. We analyzed the TGF-beta(1) (codon 25) PM in 59 patients with CBD and 164 matched healthy controls, from two groups of European/Israeli and United States origin. Additionally, patients were genotyped for HLA class II gene variants and the TNFA (-308) PM. The most significant results were found for the TGF-beta(1) (codon 25) PM with a shift towards the low producing non-GG genotypes in the subgroup of European and Israeli patients with CBD (62.50% vs. 13.82% in healthy controls; P<0.001). This phenomenon was not observed in the group from the United States. Moreover, TGF-beta(1) (codon 25) PM genotype frequencies from United States CBD patients differed significantly from those of European and Israeli patients. In contrast, increased frequencies for the high producing TNFA2 allele were found only in the patients from the United States (28.20% vs. 8.96% in healthy controls; P<0.005) but not in the group of Europe and Israel. In conclusion, the increase in TGF-beta(1) (codon 25) PM genotype frequency associated with a low TGF-beta release suggests that immunoregulatory cytokines such as TGF-beta are involved in the pathogenesis of CBD. Moreover, based on the interaction of gene PMs associated with the control of the immune response, such as TNF-alpha and TGF-beta(1), with a specific immune response gene such as HLA-DPB1-Glu69 or other HLA-class II PMs driving the immune response to Be, the present data suggest that a combination of different genetic backgrounds determine susceptibility for the same immunopathological reaction and disease.

Idiopathic pleuroparenchymal fibroelastosis: description of a novel clinicopathologic entity

Between 1996 and 2001, we identified five cases of a unique idiopathic pleuroparenchymal lung disease characterized by a clinical presentation suggestive of a chronic idiopathic interstitial pneumonia, marked pleural and parenchymal radiographic involvement with an upper lobe predominance, and surgical lung biopsy findings that did not fit with any of the currently defined interstitial pneumonias. The pathologic findings included the following: (1) intense fibrosis of the visceral pleura; (2) prominent, homogenous, subpleural fibroelastosis; (3) sparing of the parenchyma distant from the pleura; (4) mild, patchy lymphoplasmacytic infiltrates; and (5) small numbers of fibroblastic foci present at the leading edge of the fibrosis. In this report, we characterize the clinical, radiographic, physiologic, and pathologic findings of this entity, which we term idiopathic pleuroparenchymal fibroelastosis.