Beryllium binding to HLA-DP molecule carrying the marker of susceptibility to berylliosis glutamate beta 69

Prediction of beryllium clusters (Ben; n = 3-25) from first principles

Evolutionary searches using the USPEX method (Universal Structure Predictor: Evolutionary Xtallography) combined with density functional theory (DFT) calculations were performed to obtain the global minimum structures of beryllium (Be_n, n = 3-25) clusters. The thermodynamic stability, optoelectronic and photocatalytic properties as well as the nature of bonding are considered for the most stable clusters. It is found that the cluster with n = 15 is the transition point at which the configurations change from 3D hollow cages to filled cage structures (with an interior atom appearing in the structure). All the ground state structures are energetically favorable with negative binding energies, suggesting good synthetic feasibility for these structures. The calculated relative stabilities and electronic structure show that the Be₄, Be₁₀ and, Be₁₇ clusters are the most stable structures and can be considered as superatoms. The electron configurations of Be₄, Be₁₀ and Be₁₇ clusters with 8, 20 and 34 electrons are identified as 1S² 1P⁶, 1S² 1P⁶ 1D¹⁰ 2S², 1S² 1P⁶ 1D¹⁰ 2S² 1F¹⁴, respectively. Theoretical simulations determined that all the ground state structures exhibit excellent thermal stability, where the upper-limit temperature that the structures can tolerate is 900 K. During AIMD simulation of O₂ adsorption onto the Be₁₇ cluster an interesting phenomenon was happening in which the pristine Be₁₇ cluster becomes a new stable Be₁₇O₁₆ cluster. Based on ELF (electron localization function) analysis, it can be concluded that the Be-Be bonds in the small clusters are primarily of van der Waals type, while for the larger clusters, the bonds are of metallic nature. The Be_n clusters show very strong absorption in the UV and visible regions with absorption coefficients larger than 10⁵ cm^-1, which suggests a wide range of potential advanced optoelectronics applications. The Be₁₇ cluster has a suitable band alignment in the visible-light excitation region which will produce enhanced photocatalytic activities (making it a promising material for water splitting).

Pulmonary granulomatosis of genetic origin

Granulomatous inflammation of the lung can be a manifestation of different conditions and can be caused by endogenous inflammation or external triggers. A multitude of different genetic mutations can either predispose patients to infections with granuloma-forming pathogens or cause autoinflammatory disorders, both leading to the phenotype of pulmonary granulomatosis. Based on a detailed patient history, physical examination and a diagnostic approach including laboratory workup, pulmonary function tests (PFTs), computed tomography (CT) scans, bronchoscopy with bronchoalveolar lavage (BAL), lung biopsies and specialised microbiological and immunological diagnostics, a correct diagnosis of an underlying cause of pulmonary granulomatosis of genetic origin can be made and appropriate therapy can be initiated. Depending on the underlying disorder, treatment approaches can include antimicrobial therapy, immunosuppression and even haematopoietic stem cell transplantation (HSCT). Patients with immunodeficiencies and autoinflammatory conditions are at the highest risk of developing pulmonary granulomatosis of genetic origin. Here we provide a review on these disorders and discuss pathogenesis, clinical presentation, diagnostic approach and treatment.

Pulmonary granulomatosis of genetic origin mostly occurs in immunodeficiency disorders and autoinflammatory conditions. In addition to specific approaches in this regard, the diagnostic workup needs to cover environmental and occupational aspects.https://bit.ly/31SqdHW

Molecular mechanism of Be2+-ion binding to HLA-DP2: tetrahedral coordination, conformational changes and multi-ion binding

Be small and positive: the smaller size and higher charge of the Be²⁺-ion results in strong binding between the M2 peptide and the β-chain of HLA-DP2, which induces conformational changes at the periphery suitable for TCR binding.

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 orthologs of HLA-DQ and -DP genes display abundant levels of variability in macaque species

The human major histocompatibility complex (MHC) region encodes three types of class II molecules designated HLA-DR, -DQ, and -DP. Both the HLA-DQ and -DP gene region comprise a duplicated tandem of A and B genes, whereas in macaques, only one set of genes is present per region. A substantial sequencing project on the DQ and DP genes in various macaque populations resulted in the detection of previously 304 unreported full-length alleles. Phylogenetic studies showed that humans and macaques share trans-species lineages for the DQA1 and DQB1 genes, whereas the DPA1 and DPB1 lineages in macaques appear to be species-specific. Amino acid variability plot analyses revealed that each of the four genes displays more allelic variation in macaques than is encountered in humans. Moreover, the numbers of different amino acids at certain positions in the encoded proteins are higher than in humans. This phenomenon is remarkably prominent at the contact positions of the peptide-binding sites of the deduced macaque DPβ-chains. These differences in the MHC class II DP regions of macaques and humans suggest separate evolutionary mechanisms in the generation of diversity.

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.

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.

Chronic Beryllium Disease: revealing the role of beryllium ion and small peptides binding to HLA-DP2

Chronic Beryllium (Be) Disease (CBD) is a granulomatous disorder that predominantly affects the lung. The CBD is caused by Be exposure of individuals carrying the HLA-DP2 protein of the major histocompatibility complex class II (MHCII). While the involvement of Be in the development of CBD is obvious and the binding site and the sequence of Be and peptide binding were recently experimentally revealed [1], the interplay between induced conformational changes and the changes of the peptide binding affinity in presence of Be were not investigated. Here we carry out in silico modeling and predict the Be binding to be within the acidic pocket (Glu26, Glu68 and Glu69) present on the HLA-DP2 protein in accordance with the experimental work [1]. In addition, the modeling indicates that the Be ion binds to the HLA-DP2 before the corresponding peptide is able to bind to it. Further analysis of the MD generated trajectories reveals that in the presence of the Be ion in the binding pocket of HLA-DP2, all the different types of peptides induce very similar conformational changes, but their binding affinities are quite different. Since these conformational changes are distinctly different from the changes caused by peptides normally found in the cell in the absence of Be, it can be speculated that CBD can be caused by any peptide in presence of Be ion. However, the affinities of peptides for Be loaded HLA-DP2 were found to depend of their amino acid composition and the peptides carrying acidic group at positions 4 and 7 are among the strongest binders. Thus, it is proposed that CBD is caused by the exposure of Be of an individual carrying the HLA-DP2*0201 allele and that the binding of Be to HLA-DP2 protein alters the conformational and ionization properties of HLA-DP2 such that the binding of a peptide triggers a wrong signaling cascade.

Sequence-based typing of HLA: an improved group-specific full-length gene sequencing approach

Matching for HLA at the allele level is crucial for stem cell transplantation. The golden standard approach for allele definition of full gene polymorphism, the so-called high-resolution HLA typing, is sequence-based typing (SBT). Although the majority of the polymorphism for class I is located in exons 2 and 3 and for class II in exon 2, for allele definition it is necessary to unravel the complete coding and intron sequences leading to an ultrahigh HLA typing resolution at the allele level, i.e., a full-length gene polymorphism identification.This chapter describes our recently developed SBT method for HLA-A, -B, -C, and -DQB1, that is based on full-length hemizygous Sanger sequencing of the alleles, separated by group-specific amplification using the low-resolution typing result as reference starting point. Group-specific amplification has already been established for DRB. This method enables a cost-efficient, user-friendly SBT approach resulting in a timely unambiguous HLA typing to an ultrahigh resolution level with minimal hands-on time.

A combined DPA1~DPB1 amino acid epitope is the primary unit of selection on the HLA-DP heterodimer

Here, we present results for DPA1 and DPB1 four-digit allele-level typing in a large (n = 5,944) sample of unrelated European American stem cell donors previously characterized for other class I and class II loci. Examination of genetic data for both chains of the DP heterodimer in the largest cohort to date, at the amino acid epitope, allele, genotype, and haplotype level, allows new insights into the functional units of selection and association for the DP heterodimer. The data in this study suggest that for the DPA1-DPB1 heterodimer, the unit of selection is the combined amino acid epitope contributed by both the DPA1 and DPB1 genes, rather than the allele, and that patterns of LD are driven primarily by dimer stability and conformation of the P1 pocket. This may help explain the differential pattern of allele frequency distribution observed for this locus relative to the other class II loci. These findings further support the notion that allele-level associations in disease and transplantation may not be the most important unit of analysis, and that they should be considered instead in the molecular context.

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.

Chronic beryllium disease: computed tomographic findings

Chronic beryllium disease is a rare multisystem granulomatous disease predominantly involving the lungs and resulting from an immunologic response to long-term occupational exposure. Computed tomography of the chest reveals important lung parenchymal and mediastinal findings and plays an important role in the diagnosis and follow-up assessment of patients with chronic beryllium disease. Its significance lies in the exact localization and evaluation of the extent of lesions. We present an overview of the subject and a pictorial review of the spectrum of computed tomographic features of beryllium disease.

Chronic beryllium disease: an updated model interaction between innate and acquired immunity

During the last decade, there have been concerted efforts to reduce beryllium (Be) exposure in the workplace and thereby reduce potential cases of this occupational lung disorder. Despite these efforts, it is estimated that there are at least one million Be-exposed individuals in the U.S. who are potentially at risk for developing chronic beryllium disease (CBD). Previously, we reviewed the current CBD literature and proposed that CBD represents a model interaction between innate and acquired immunity (Sawyer et al., Int Immunopharmacol 2:249-261, 2002). We closed this review with a section on "future directions" that identified key gaps in our understanding of the pathogenesis of CBD. In the intervening period, progress has been made to fill in some of these gaps, and the current review will provide an update on that progress. Based on recent findings, we provide a new hypothesis to explain how Be drives sustained chronic inflammation and granuloma formation in CBD leading to progressive compromised lung function in CBD patients. This paradigm has direct implications for our understanding of the development of an immune response to Be, but is also likely applicable to other immune-mediated lung diseases of known and unknown etiology.

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.

Sarcoidosis HLA class II genotyping distinguishes differences of clinical phenotype across ethnic groups

The HLA class II (DRB1 and DQB1) associations with sarcoidosis have been studied by several groups but often without consistent results. In this paper, we consider the hypothesis that observed inconsistencies relate to distinct, genetically encoded disease phenotypes which differ in prevalence between centres. We therefore typed HLA-DRB1 and DQB1 in 340 UK, 139 Dutch and 163 Japanese sarcoidosis patients and, respectively, 354, 218 and 168 healthy controls from these populations. We applied consistent phenotyping and genotyping and investigated associations between HLA class II alleles and distinct disease phenotypes within and between ethnic groups. DRB1*01 and DQB1*0501 are protective against all manifestations of sarcoidosis. Lung-predominant sarcoidosis is associated with DRB1*12 and *14. Löfgren's syndrome is a common sarcoidosis phenotype in the Dutch and is strongly associated with the DRB1*0301 allele. This phenotype is not seen among the Japanese in whom DRB1*0301 is absent. The same allele is protective for UK uveitis. Sarcoid uveitis is common in Japan. The DRB1*04-DQB1*0301 haplotype is a risk factor for this disease manifestation in Japanese and UK subjects but protective for sarcoidosis overall. We show that distinct sarcoidosis phenotypes have similar genetic associations across ethnic groups. The disease case mix differs between centres and may be explained by different ethnic allelic frequencies.

Crystal structure of HLA-DP2 and implications for chronic beryllium disease

Chronic beryllium disease (CBD) is a fibrotic lung disorder caused by beryllium (Be) exposure and is characterized by granulomatous inflammation and the accumulation of Be-responsive CD4(+) T cells in the lung. Genetic susceptibility to CBD has been associated with certain alleles of the MHCII molecule HLA-DP, especially HLA-DPB1*0201 and other alleles that contain a glutamic acid residue at position 69 of the beta-chain (betaGlu69). The HLA-DP alleles that can 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. The structure of HLA-DP2 and its interaction with Be are unknown. Here, we present the HLA-DP2 structure with its antigen-binding groove occupied by a self-peptide derived from the HLA-DR alpha-chain. The most striking feature of the structure is an unusual solvent exposed acidic pocket formed between the peptide backbone and the HLA-DP2 beta-chain alpha-helix and containing three glutamic acids from the beta-chain, including betaGlu69. In the crystal packing, this pocket has been filled with the guanidinium group of an arginine from a neighboring molecule. This positively charged moiety forms an extensive H-bond/salt bridge network with the three glutamic acids, offering a plausible model for how Be-containing complexes might occupy this site. This idea is strengthened by the demonstration that mutation of any of the three glutamic acids in this pocket results in loss of the ability of DP2 to present Be to T cells.

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.

Beryllium hypersensitivity and chronic beryllium lung disease

PURPOSE OF REVIEW

This review aims to present the clinician with a synthesis of recent studies that have enhanced our understanding of the epidemiology and pathogenesis of beryllium hypersensitivity (BeH) and chronic beryllium disease (CBD).

RECENT FINDINGS

Lower occupational limit levels to beryllium exposure and more stringent preventive measures can decrease the risk for development of BeH and CBD. Beryllium sensitization is determined by a positive beryllium lymphocyte proliferation test (BeLPT). Longitudinal data suggest that BeH progresses to CBD. Together with a comprehensive history the BeLPT may help identify berylliosis in patients erroneously diagnosed to have sarcoidosis. HLA-DPB1-Glu69 marker is associated with increased susceptibility to development of BeH and CBD but poor positive predictive value limits its use; other genetic markers are being investigated. Recent investigations augment our understanding on the role of T-lymphocytes and chemokines in the pathogenesis of beryllium-associated disease. However, the basis for treatment strategies remains scarce.

SUMMARY

Our enhanced understanding of beryllium-associated lung disease potentially provides a window to unraveling other granulomatous diseases. However, even more questions beg to be elucidated and additional efforts are needed to translate this body of knowledge into better prevention and treatment.

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.

Study on the effects of nitrilotriproprionic acid and 4,5-dihydroxy-1,3-benzene disulphonate on the fractionation of beryllium in human serum using graphite furnace atomic absorption spectrometry

Background

Occupational exposure to beryllium may cause Chronic Beryllium Disease (CBD), a lung disorder initiated by an electrostatic interaction with the MHC class II human leukocyte antigen (HLA). Molecular studies have found a significant correlation between the electrostatic potential at the HLA-DP surface and disease susceptibility. CBD can therefore be treated by chelation therapy. In this work, we studied the effect of two complexing agents, nitrilotriproprionic acid (NTP) and 4,5-dihydroxy-1,3-benzene disulphonate (Tiron), on the fractionation of beryllium in human serum analysed by graphite furnace atomic absorption spectrometry (GFAAS).

Results

We found the average serum beryllium concentration of fourteen non-exposed individuals to be 0.53 (± 0.14) μg l^-1, with 21 (± 3)% of the beryllium mass bound to the low molecular weight fraction (LMW), and 79 (± 3)% bound to the high molecular weight fraction (HMW). The addition of Tiron increased the beryllium mass in the HMW fraction, while NTP was not seen to have any influence on the fractionation of beryllium between the two fractions. NTP was, however, shown to complex 94.5% of the Be mass in the LMW fraction. The beryllium GFAAS detection limit, calculated as three times the standard deviation of 10 replicates of the lowest standard (0.05 μg L^-1), was 6.0 (± 0.2) ng L^-1.

Conclusion

The concentration of beryllium or its fractionation in human serum was not affected by sex or smoking habit. On average, three quarters of the beryllium in serum were found in the HMW fraction. Of the two ligands tested, only Tiron was effective in mobilising beryllium under physiological conditions, thus increasing the Be content in the HMW fraction.

Lymphocyte subpopulations in human exposure to metals (IUPAC Technical Report)

Numerous species of metal ions cause immunosensitization in humans. Possible approaches to determine those occupational and environmental exposures to metals that result in immunological changes include lymphocyte transformation assay, cytokine profiling, and measurement of lymphocyte subpopulations. In two previous papers, we considered lymphocyte transformation assay [1] and cytokine profiling [2]. Here we review the effects of exposures to metals on lymphocyte subpopulations. Specific consideration is given to beryllium, chromium, cobalt, nickel, palladium and platinum, cadmium, gold, mercury, and lead. Analysis of the scientific literature shows that immunosensitizing metals may have influences on the lymphocyte subset composition, but only in a few instances does exposure to metals cause reproducible shifts of lymphocyte subpopulations. If lymphocyte subpopulations are analyzed, each diagnostic step, including indication, sample handling, analytic procedure, and data interpretation, should adhere to good quality assurance and quality control.

Gene-environment interactions in sarcoidosis: challenge and opportunity

Susceptibility to most human diseases is polygenic, with complex interactions between functional polymorphisms of single genes governing disease incidence, phenotype, or both. In this context, the contribution of any discrete gene is generally modest for a single individual, but may confer substantial attributable risk on a population level. Environmental exposure can modify the effects of a polymorphism, either by providing a necessary substrate for development of human disease or because the effects of a given exposure modulate the effects of the gene. In several diseases, genetic polymorphisms have been shown to be context dependent, ie, the effects of a genetic variant are realized only in the setting of a relevant exposure. Because sarcoidosis susceptibility is dependent on both genetic and environmental modifiers, the study of gene-environment interactions may yield important pathogenetic information and will likely be crucial for uncovering the range of genetic susceptibility loci. The complexity of these relationships implies, however, that investigations of gene-environment interactions will require the study of large cohorts with carefully defined exposures and similar clinical phenotypes. A general principle is that the study of gene-environment interactions requires a sample size at least severalfold greater than for either factor alone. To date, the presence of environmental modifiers has been demonstrated for one sarcoidosis susceptibility locus, HLA-DQB1, in African-American families. This article reviews general considerations obtaining for the study of gene-environment interactions in sarcoidosis. It also describes the limited current understanding of the role of environmental influences on sarcoidosis susceptibility genes.

Comparative analysis between CFSE flow cytometric and tritiated thymidine incorporation tests for beryllium sensitivity

BACKGROUND

In this study, we evaluated alternative possibility for CFSE beryllium flow cytometric test against beryllium blood lymphocyte proliferation test (BeLPT) as a standard radioactive clinical screening method to identify sensitization to beryllium.

METHODS

Delta PD (the ratio of divided cell population to the total number of cells with subtracted counts of unstimulated cells) of specific beryllium-induced pathogenic CD3+ CD4+ T-lymphocytes and stimulation index (SI) in CFSE proliferation test was compared with delta counts per minute (mean test CPM minus mean control CPM) and SI in radioactive blood BeLPT.

RESULTS

Comparison analysis of CFSE and BeLPT demonstrated excellent agreement between delta PD and delta CPM (kappa = 0.845, P << 0.0001). We determined 6.8% positive subjects in the beryllium-exposed, Be-LPT-negative group. The decreased mean difference of these indexes to percentage of average and the long tail in the plot reflects increased sensitivity. CFSE/CD4+ T-cell proliferation assay has 100% specificity, significantly higher sensitivity and efficiency than BeLPT.

CONCLUSIONS

Both delta PD, measured by the precursor frequencies method in CFSE assay and delta CPM, defined by tritiated thymidine in BeLPT, can be used for the enumeration of beryllium specific CD4+ T-cell proliferation and may substantially improve the quality of the early diagnosis of beryllium hypersensitivity.

Genetics of sarcoidosis: candidate genes and genome scans

Human leukocyte antigen class II allele associations and T-cell receptor beta chain bias in sarcoidosis suggest a specific disease-triggering antigen exposure in a genetically susceptible host. The cause of sarcoidosis has been elusive, but genetics provides one of the few promising avenues to further our understanding. We review the association studies and genome scans used to identify the genes involved in sarcoidosis.

Diagnostic relevance of the determination of lymphocyte subpopulations in environmental medicine

Earlier hopes that determination of lymphocyte subpopulations might become a strong diagnostic tool in environmental medicine have not been fulfilled in recent years. Analysis of the scientific literature rather shows that there are only few examples for environmental exposures causing reproducible shifts of lymphocyte subpopulations. Moreover, current knowledge suggests that "environmental diseases" are not associated with characteristic changes of subpopulation patterns. If lymphocyte subpopulations are analyzed, each diagnostic step, including indication, sample handling, analytic procedure and data-interpretation, should adhere to good quality criteria. Taking all together, the determination of lymphocyte subpopulations in the context of environmental medicine comes under category IV of the criteria of the Commission for Methods and Quality Assurance in Environmental Medicine of the German federal health authority (Robert Koch-Institute; RKI): "A procedure cannot be recommended because there is not sufficient information to justify it" (here: no solid trends in epidemiological examinations), "and because theoretical considerations speak against an application" (here: high physiological variability and missing exposure or substance specificity).

Recombinant HLA-DP2 binds beryllium and tolerizes beryllium-specific pathogenic CD4+ T cells

Chronic beryllium disease is a lung disorder caused by beryllium exposure in the workplace and is characterized by granulomatous inflammation and the accumulation of beryllium-specific, HLA-DP2-restricted CD4+ T lymphocytes in the lung that proliferate and secrete Th1-type cytokines. To characterize the interaction among HLA-DP2, beryllium, and CD4+ T cells, we constructed rHLA-DP2 and rHLA-DP4 molecules consisting of the alpha-1 and beta-1 domains of the HLA-DP molecules genetically linked into single polypeptide chains. Peptide binding to rHLA-DP2 and rHLA-DP4 was consistent with previously published peptide-binding motifs for these MHC class II molecules, with peptide binding dominated by aromatic residues in the P1 pocket. 9Be nuclear magnetic resonance spectroscopy showed that beryllium binds to the HLA-DP2-derived molecule, with no binding to the HLA-DP4 molecule that differs from DP2 by four amino acid residues. Using beryllium-specific CD4+ T cell lines derived from the lungs of chronic beryllium disease patients, beryllium presentation to those cells was independent of Ag processing because fixed APCs were capable of presenting BeSO4 and inducing T cell proliferation. Exposure of beryllium-specific CD4+ T cells to BeSO4 -pulsed, plate-bound rHLA-DP2 molecules induced IFN-gamma secretion. In addition, pretreatment of beryllium-specific CD4+ T cells with BeSO4-pulsed, plate-bound HLA-DP2 blocked proliferation and IL-2 secretion upon re-exposure to beryllium presented by APCs. Thus, the rHLA-DP2 molecules described herein provide a template for engineering variants that retain the ability to tolerize pathogenic CD4+ T cells, but do so in the absence of the beryllium Ag.

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.

Carboxylate binding to be(2+) in proteins and influence of the dielectric environment

To gain insight into the interaction of Be2+ ions with negatively charged protein residues, the free energy changes associated with the replacement of water molecules in the first hydration shell of with one and two acetate anions were computed for the gas phase reactions using ab initio methods at the MP2 and DFT-B3LYP computational levels. Both unidentate and bidentate modes of coordination of the carboxylate group with the Be2+ ion are considered. Continuum dielectric calculations were then performed to estimate the corresponding free energy changes in several environments of varying dielectric strength. Environments with dielectric constants of 2 and 4, which represent a protein interior, and 78, which corresponds to water, were used. It is found that the free energy changes for the substitution reactions decrease in magnitude with increasing dielectric strength, in agreement with similar results reported for Mg2+, Ca2+, and Zn2+ (Dudev et al. J. Phys. Chem. B 2000, 104, 3692). However, unlike Mg2+, Ca2+, and Zn2+, the free energy change for single-anion or concerted two-anion substitution reactions with remains negative and indicates the reactions are still favorable in the high dielectric aqueous environment. It is also found that the unidentate mode of binding is favored over the bidentate mode, and this is attributed, in part, to the introduction of hydrogen bonds between one carboxylate oxygen and a water molecule within the cluster when unidentate binding with Be2+ is involved.

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 (2e partie)

INTRODUCTION

Chronic beryllium disease (CBD) is an occupational lung disease caused by the inhalation of beryllium dust, fumes or metallic salts.

CURRENT DATA

Beryllium affects the lungs via particles deposited in the pulmonary alveoli. These are ingested by alveolar macrophages which act as antigen presenting cells to CD4+ T lymphocytes. T lymphocytes proliferate in response to beryllium antigens and combined with macrophages produce numerous epithelioid granulomas with the release of inflammatory cytokines (IFNgamma, IL-2, TNFalpha and IL6) and growth factors. Beryllium induces macrophage apoptosis which reduces its clearance from the lung which in turn contributes to the host's continual re-exposure and thus a chronic granulomatous disorder. Pulmonary granulomatous inflammation is the primary manifestation of CBD, but the disease occasionally involves other organs such as the liver, spleen, lymph nodes and bone marrow. The clinical, radiological, and histopathological features of CBD can be difficult to distinguish from sarcoidosis. The Beryllium lymphocyte proliferation test (BeLPT) demonstrates a beryllium specific immune response, confirms the diagnosis of CBD, and excludes sarcoidosis.

CONCLUSIONS AND PERSPECTIVES

CBD provides a human model of pulmonary granulomatous disease produced by an occupational exposure, occurring more frequently in those with a genetic pre-disposition. It can be differentiated from sarcoidosis by specific immunological testing.

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.

Detailed analysis of the effects of Glu/Lys beta69 human leukocyte antigen-DP polymorphism on peptide-binding specificity

The polymorphism at position beta69 of the human leukocyte antigen (HLA)-DP molecule has been associated with susceptibility to several immune disorders and alloreactivity. Using molecular modeling, we have predicted a detailed structure of the HLA-DP2 molecule (carrying Glubeta69) complexed with class II associated invariant chain derived peptide (CLIP) and compared it with the form carrying Lys at beta69 (HLA-DP2K69). Major changes between the two models were observed in the shape and charge distribution of pocket 4 and of the nearby pocket 6. Consequently, we analyzed in detail the peptide-binding specificities of both HLA-DP molecules expressed as recombinant proteins. We first determined that the minimum peptide-binding core of CLIP for both HLA-DP2 and DP2K69 is represented by nine aminoacids corresponding to the sequence 91-99 of invariant chain (Ii). We then assessed the peptide-binding specificities of the two pockets and determined the role of position beta69, using competition tests with the Ii-derived peptide CLIP and its mutated forms carrying all the aminoacidic substitutions in P4 and P6. Pocket 4 of HLA-DP2 showed high affinity for positively charged, aromatic, and polar residues, whereas aliphatic residues were disfavored. Pocket 4 of the DP2K69 variant showed a reduced aminoacid selectivity with aromatic residues most preferred. Pocket 6 of HLA-DP2 showed high affinity for aromatic residues, which was increased in DP2K69 and extended to arginine. Finally, we used the experimental data to determine the best molecular-modeling approach for assessing aminoacid selectivity of the two pockets. The results with best predictive value were obtained when single aminoacids were evaluated inside each single pocket, thus, reducing the influence of the overall peptide/ major histocompatibility complex interaction. In conclusion, the HLA-DPbeta69 polymorphism plays a fundamental role in the peptide-binding selectivity of HLA-DP. Furthermore, as this polymorphism is the main change in the pocket 4 area of HLA-DP, it could represent a supertype among HLA-DP molecules significantly contributing to the selection of epitopes presented in the context of this HLA isotype.

Potential binding modes of beryllium with the class II major histocompatibility complex HLA-DP: a combined theoretical and structural database study

In an effort to understand the molecular basis of chronic beryllium disease (CBD), a study of the chemical relationship between beryllium, antigen, and the major histocompatibility complex II, HLA-DP, was undertaken. A homology model of the HLA-DP protein was developed. An analysis of the sequences of HLA-DPB1 and HLA-DPA1 alleles most common among CBD patients revealed several carboxylate rich regions in the peptide-binding cleft. These regions contain many hard Lewis base sites that may provide bonding opportunities for beryllium, a hard Lewis acid. Quantum chemistry calculations and structural database results support the presence of beryllium clusters, bridged by carboxylate, hydroxo, and/or oxo ligands, in the HLA-DP binding cleft. These results strongly suggest that beryllium clusters are an integral part of the antigen, and may even act solely as antigen. This work provides an initial model for thinking about beryllium interactions with proteins relevant to CBD and other metal-induced diseases.

Human leukocyte antigen Class II amino acid epitopes: susceptibility and progression markers for beryllium hypersensitivity

Chronic beryllium disease (CBD) is a hypersensitivity granulomatosis characterized by beryllium hypersensitivity (BH) and mediated by CD4+ T cells. However, all individuals with BH may not develop CBD. To examine the role of the three different human leukocyte antigen (HLA) Class II isotypes in BH with (CBD) and without clinical disease (BHWCD), we performed DNA-based typing of HLA-DPB1, HLA-DQB1, and HLA-DRB1 loci on 55 subjects with BH (25 with established CBD and 30 with BHWCD), and compared this with the results for 82 beryllium-exposed workers with no evidence of BH. The allele distribution was utilized to identify candidate amino acid epitopes that differed between the study groups. HLA-DPB1-E69 was the most important marker for BH, and did not differentiate BHWCD from CBD. A significant association with CBD was observed with HLA-DQB1-G86 (p(corr) < 0.04), and HLA-DRB1-S11 was significantly increased in CBD as compared with BHWCD (p < 0.03). These observations suggest that HLA-DPB1-E69 is a marker for susceptibility to BH and not just a progression marker for CBD. In addition, HLA amino acid epitopes on HLA-DRB1 and -DQB1, in concert with or independently of HLA-DPB1-E69, may be associated with progression to CBD.