Beryllium-Induced Tumor Necrosis Factor-α Production by CD4+T Cells Is Mediated by HLA-DP

Beryllium increases the CD14(dim)CD16+ subset in the lung of chronic beryllium disease

CD14^dimCD16+ and CD14^brightCD16+ cells, which compose a minor population of monocytes in human peripheral blood mononuclear cells (PBMC), have been implicated in several inflammatory diseases. The aim of this study was to investigate whether this phenotype was present as a subset of lung infiltrative alveolar macrophages (AMs) in the granulomatous lung disease, chronic beryllium disease (CBD). The monocytes subsets was determined from PBMC cells and bronchoalveolar lavage (BAL) cells from CBD, beryllium sensitized Non-smoker (BeS-NS) and healthy subjects (HS) using flow cytometry. The impact of smoking on the AMs cell phenotype was determined by using BAL cells from BeS smokers (BeS-S). In comparison with the other monocyte subpopulations, CD14^dimCD16+ cells were at decreased frequency in PBMCs of both BeS-NS and CBD and showed higher HLA-DR expression, compared to HS. The AMs from CBD and BeS-NS demonstrated a CD14^dimCD16+phenotype, while CD14^brightCD16+ cells were found at increased frequency in AMs of BeS, compared to HS. Fresh AMs from BeS-NS and CBD demonstrated significantly greater CD16, CD40, CD86 and HLA-DR than HS and BeS-S. The expression of CD16 on AMs from both CBD and BeS-NS was downregulated significantly after 10μM BeSO₄ stimulation. The phagocytic activity of AMs decreased after 10μM BeSO₄ treatment in both BeS-NS and CBD, although was altered or reduced in HS and BeS-S. These results suggest that Be increases the CD14^dimCD16+ subsets in the lung of CBD subjects. We speculate that Be-stimulates the compartmentalization of a more mature CD16+ macrophage phenotype and that in turn these macrophages are a source of Th1 cytokines and chemokines that perpetuate the Be immune response in CBD. The protective effect of cigarette smoking in BeS-S may be due to the low expression of co-stimulatory markers on AMs from smokers as well as the decreased phagocytic function.

p38 Mitogen-Activated Protein Kinase in beryllium-induced dendritic cell activation

Dendritic cells (DC) play a role in the regulation of immune responses to haptens, which in turn impact DC maturation. Whether beryllium (Be) is able to induce DC maturation and if this occurs via the MAPK pathway is not known. Primary monocyte-derived DCs (moDCs) models were generated from Be non-exposed healthy volunteers as a non-sensitized cell model, while PBMCs from BeS (Be sensitized) and CBD (chronic beryllium disease) were used as disease models. The response of these cells to Be was evaluated. The expression of CD40 was increased significantly (p<0.05) on HLA-DP Glu69+ moDCs after 100 μM BeSO₄-stimulation. BeSO₄ induced p38MAPK phosphorylation, while IκB-α was degraded in Be-stimulated moDCs. The p38 MAPK inhibitor SB203580 blocked Be-induced NF-κB activation in moDCs, suggesting that p38MAPK and NF-κB are dependently activated by BeSO₄. Furthermore, in BeS and CBD subjects, SB203580 downregulated Be-stimulated proliferation in a dose-dependent manner, and decreased Be-stimulated TNF-α and IFNγ cytokine production. Taken together, this study suggests that Be-induces non-sensitized Glu69+ DCs maturation, and that p38MAPK signaling is important in the Be-stimulated DCs activation as well as subsequent T cell proliferation and cytokine production in BeS and CBD. In total, the MAPK pathway may serve as a potential therapeutic target for human granulomatous lung diseases.

Accelerator mass spectrometry detection of beryllium ions in the antigen processing and presentation pathway

Exposure to small amounts of beryllium (Be) can result in beryllium sensitization and progression to Chronic Beryllium Disease (CBD). In CBD, beryllium is presented to Be-responsive T-cells by professional antigen-presenting cells (APC). This presentation drives T-cell proliferation and pro-inflammatory cytokine (IL-2, TNFα, and IFNγ) production and leads to granuloma formation. The mechanism by which beryllium enters an APC and is processed to become part of the beryllium antigen complex has not yet been elucidated. Developing techniques for beryllium detection with enough sensitivity has presented a barrier to further investigation. The objective of this study was to demonstrate that Accelerator Mass Spectrometry (AMS) is sensitive enough to quantify the amount of beryllium presented by APC to stimulate Be-responsive T-cells. To achieve this goal, APC - which may or may not stimulate Be-responsive T-cells - were cultured with Be-ferritin. Then, by utilizing AMS, the amount of beryllium processed for presentation was determined. Further, IFNγ intracellular cytokine assays were performed to demonstrate that Be-ferritin (at levels used in the experiments) could stimulate Be-responsive T-cells when presented by an APC of the correct HLA type (HLA-DP0201). The results indicated that Be-responsive T-cells expressed IFNγ only when APC with the correct HLA type were able to process Be for presentation. Utilizing AMS, it was determined that APC with HLA-DP0201 had membrane fractions containing 0.17-0.59 ng Be and APC with HLA-DP0401 had membrane fractions bearing 0.40-0.45 ng Be. However, HLA-DP0401 APC had 20-times more Be associated with the whole cells (57.68-61.12 ng) than HLA-DP0201 APC (0.90-3.49 ng). As these findings demonstrate, AMS detection of picogram levels of Be processed by APC is possible. Further, regardless of form, Be requires processing by APC to successfully stimulate Be-responsive T-cells to generate IFNγ.

Overactive bladder syndrome and the potential role of prostaglandins and phosphodiesterases: an introduction

In this paper, a general introduction is given, presenting the overactive bladder syndrome (OAB) and its impact on the quality of life and economical burden in patients affected. Moreover, the anatomy, physiology and histology of the lower urinary tract are discussed, followed by a brief overview on the possible role of prostaglandin (PG) and phosphodiesterase type 5 (PDE5) in the urinary bladder. The current literature on the role and distribution of PGE2 and its receptors in the urinary bladder is discussed. In both animal models and in human studies, high levels of signaling molecules such as PG and cGMP have been implicated, in decreased functional bladder capacity and micturition volume, as well as in increased voiding contraction amplitude. As a consequence, inhibition of prostanoid production, the use of prostanoid receptor antagonists, or PDE inhibitors might be a rational way to treat patients with detrusor overactivity. Similarly, prostanoid receptor agonists, or agents that stimulate their production, might have a function in treating bladder underactivity.

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.

[Sarcoidosis and genetics]

Familial features of sarcoidosis and observations in monozygotic twins affected by the condition suggest the presence of a genetic predisposition. Various genetic associations have been described with genes coding for proteins involved in immune regulation in particular at the level of interaction between T-lymphocyte and antigen presenting cell. We review the various genetic targets described with techniques ranging from classic human lymphocyte antigen genotype to genome wide linkage scans. The 6p21 region has been highlighted, which includes relevant genes such as MHC class II, BTNL2 and TNFα. These studies show that the genetics of sarcoidosis are complex, that patient sub-groups exist, which may explain some of the heterogeneity in the results of genetic studies and that the interactions between genetic and environmental factors remains to be elucidated.

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.

Sulfasalazine and mesalamine modulate beryllium-specific lymphocyte proliferation and inflammatory cytokine production

Occupational exposure to beryllium (Be) results in Be sensitization (BeS) that can progress to pulmonary granulomatous inflammation associated with chronic Be disease (CBD). Be-specific lymphocytes are present in the blood of patients with BeS and in the blood and lungs of patients with CBD. Sulfasalazine and its active metabolite, mesalamine, are clinically used to ameliorate chronic inflammation associated with inflammatory bowel disease. We tested whether sulfasalazine or mesalamine could decrease Be-stimulated peripheral blood mononuclear cell (PBMC) proliferation in subjects with CBD and BeS and Be-induced cytokine production in CBD bronchoalveolar lavage (BAL) cells. CBD (n = 25), BeS (n = 12) and healthy normal control (n = 6) subjects were enrolled and ex vivo proliferation and cytokine production were assessed in the presence of Be and sulfasalazine or mesalamine. Be-stimulated PBMC proliferation was inhibited by treatment with either sulfasalazine or mesalamine. Be-stimulated CBD BAL cell IFN-γ and TNF-α cytokine production was decreased by treatment with sulfasalazine or mesalamine. Our data suggest that both sulfasalazine and mesalamine interfere with Be-stimulated PBMC proliferation in CBD and BeS and dampens Be-stimulated CBD BAL cell proinflammatory cytokine production. These studies demonstrate that sulfasalazine and mesalamine can disrupt inflammatory pathways critical to the pathogenesis of chronic granulomatous inflammation in CBD, and may serve as novel therapy for human granulomatous lung diseases.

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.

Modulation of lymphocyte proliferation by antioxidants in chronic beryllium disease

RATIONALE

Occupational exposure to beryllium (Be) can result in chronic granulomatous inflammation characterized by the presence of Be-specific CD4+ T cells. Studies show that oxidative stress plays a role in the pathogenesis of chronic inflammatory disorders.

OBJECTIVES

We hypothesized that Be-induced oxidative stress modulates the proliferation of Be-specific CD4+ T cells.

METHODS

Thirty-three subjects with chronic beryllium disease (CBD), 15 subjects with beryllium sensitization, and 28 healthy normal control subjects were consecutively enrolled from the Occupational and Environmental Health Clinic of the National Jewish Medical and Research Center.

MEASUREMENTS AND MAIN RESULTS

All studies were performed with Ficoll-Hypaque-isolated peripheral blood mononuclear cells from subsets of the study subjects. Decreased intracellular levels of the thiol antioxidants, glutathione and cysteine, were observed in peripheral blood mononuclear cells from subjects with beryllium sensitization and CBD, as compared with healthy control subjects. Beryllium stimulation decreased intracellular thiol antioxidants by more than 40%, accompanied by increased reactive oxygen species levels and the proliferation of Be-specific blood CD4+ T cells from subjects with CBD. Be-induced T-cell proliferation was inhibited by treatment with the thiol antioxidant N-acetylcysteine or the catalytic antioxidant manganese(III) 5,10,15,20-tetrakis(4-benzoic acid)porphyrin (MnTBAP). MnTBAP treatment also inhibited T-cell proliferation in response to the unrelated, MHC class II-restricted antigen tetanus toxoid. Treatment of CBD blood lymphocytes, but not antigen-presenting cells, with MnTBAP decreased Be-induced T-cell proliferation by more than 40%.

CONCLUSIONS

Beryllium can mediate a thiol imbalance leading to oxidative stress that may modulate the proliferation and clonal expansion of Be-specific blood CD4+ T cells. These data suggest that Be-induced oxidative stress plays a role in the pathogenesis of granulomatous inflammation in CBD.

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.

Association of HLA class II DRB1, DPA1 and DPB1 polymorphism with genetic susceptibility to idiopathic dilated cardiomyopathy in Chinese Han nationality

Although the aetiology of idiopathic dilated cardiomyopathy (IDC) remains unclear, many immunological abnormalities involving changes in cell-mediated and humoral immunity may be associated with cardiac impairment in IDC. Autoimmune mechanisms are likely to participate in the pathogenesis of at least a subgroup of IDC and components of the major histocompatibility complex may serve as markers for the propensity to develop immune-mediated myocardial damage. Human leukocyte antigen (HLA) class II genes, which are highly polymorphic, play an important role in the activating of immune responses and thus control the predisposition for or protection from IDC. This study explores the possible contribution of HLA-DRB and DP polymorphisms to IDC susceptibility. DNA genotyping for HLA-DRB1, DPA1 and DPB1 was performed using polymerase chain reaction-sequencing based typing (PCR-SBT) method in 198 IDC patients and 136 random selected healthy Han ethnic individuals living in Northern China. IDC patients were, sub-grouped into asymptomatics (subgroup A), with arrhythmia (subgroup B) and with overt congestive heart failure (subgroup C) according to the clinical manifestations and electrocardiogram or echocardiographic characteristics. ADP/ATP autoantibody was detected in IDC group by immunoblot analysis. The results revealed that HLA-DR15, -DPB*0601 frequencies were significantly elevated in IDC group compared with normal control. The DPB1*0601 allele in homozygous form or in combination with allele DPB1*2301 or *3901, was found present more often in IDC patients. The predominance of HLA-DR4 allele was observed in subgroup B after stratification. However, the frequency of DPB1*0101 allele increased in the control than in the IDC group. The frequency of HLA-DPB1*0601 allele was significantly higher in IDC patients with positive autoantibody against ADP/ATP carrier of myocardial mitochondria in contrast to those with negative autoantibody. We conclude that HLA-DR4, -DR15, -DPB1*0601 alleles confers susceptibility to, while DPB1*0101 allele confers protection from IDC among individuals of northern Chinese Han nationality. The glutamate at position 69 in the second exon of DPB1*0601, as a key residue for special conformation of HLA-DP, may confer predisposition to IDC. HLA-DR and -DP alleles polymorphisms may serve as genetic markers for IDC and be involved in the regulation of the immune specific response to auto or exterior anti-myocardium antibodies.

Genetic susceptibility in pneumoconiosis

A large number of cellular mediators such as cytokines, antioxidants and growth factors have been implicated in the pathogenesis of chronic inflammatory and fibrotic diseases. Common functional polymorphisms in these genes have been shown to influence individual susceptibility to these diseases. Silicosis, coal worker pneumoconiosis, progressive massive fibrosis and berylliosis are examples of fibrotic pneumoconiosis and are characterized by irreversible fibrotic lesions in the lung resulting from chronic dust inhalation. Although the materials are the major contributory factors of the disease pathogenesis, not all individuals exposed to similar levels develop disease. This suggests that there is a genetic predisposition to their development. Therefore, an understanding of genetic variability and the interaction between genetic and environmental factors is crucial to the identification of high-risk individuals and prevention and treatment of these diseases.

TNF polymorphism and bronchoalveolar lavage cell TNF-alpha levels in chronic beryllium disease and beryllium sensitization

BACKGROUND

Beryllium stimulates TNF-alpha from chronic beryllium disease (CBD) bronchoalveolar lavage (BAL) cells.

OBJECTIVE

We sought to relate TNF polymorphisms to beryllium-stimulated TNF-alpha production, to the development of CBD, and to the risk of more severe CBD over time.

METHODS

We recruited 147 patients with CBD, 112 beryllium-sensitized subjects, and 323 control subjects; genotyped 5 TNF promoter polymorphisms; and measured beryllium-stimulated and unstimulated BAL cell TNF-alpha production from a subset of subjects.

RESULTS

Beryllium-stimulated, but not beryllium-unstimulated, BAL cell TNF-alpha production was significantly increased in patients with CBD compared with that seen in those only sensitized (P = .0002). Those subjects with the TNF -857T allele and the only haplotype (haplotype 4) containing this allele demonstrated significantly lower unstimulated BAL cell TNF-alpha production compared with that seen in noncarriers (P = .009). Patients with CBD alone and combined with sensitized subjects carrying the TNF haplotype 1 compared with those without this haplotype had significantly increased beryllium-stimulated BAL cell TNF-alpha levels (P = .02). We found no significant association between patients with CBD, sensitized subjects, and control subjects with any of the TNF promoter polymorphisms or haplotypes. A greater decrease in Pao(2) at maximum exercise was noted in patients with CBD with the -1031C allele (P = .03) and with haplotypes other than the TNF haplotype 1 (P = .01), 3 (from 5) of which contain the -1031C allele.

CONCLUSIONS

The -857T allele and haplotype 1 are associated with BAL cell TNF-alpha production, indicating a potential role of TNF promoter variants in regulation of TNF production in sensitized subjects and patients with CBD.

CLINICAL IMPLICATIONS

TNF promoter variants are not risk factors for CBD or sensitization.

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.

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).

Beryllium-induced TNF-alpha production is transcription-dependent in chronic beryllium disease

Beryllium (Be)-antigen presentation to Be-specific CD4(+) T cells from the lungs of patients with chronic beryllium disease (CBD) results in T cell proliferation and TNF-alpha secretion. We tested the hypothesis that Be-induced, CBD bronchoalveolar lavage (BAL) T cell, transcription-dependent, TNF-alpha secretion was accompanied by specific transcription factor upregulation. After 6 h of Be stimulation, CBD BAL cells produced a median of 883 pg/ml TNF-alpha (range, 608-1,275 pg/ml) versus 198 pg/ml (range, 116-245 pg/ml) by unstimulated cells. After 12 h CBD BAL cells produced a median of 2,963 pg/ml (range, 99-9,424 pg/ml) TNF-alpha versus 55 pg/ml (range, 0-454) by unstimulated cells. Using real-time RT-PCR, Be-stimulated TNF-alpha production at 6 h was preceded by a 5-fold increase in TNF-alpha pre-mRNA copy number:beta-actin copy number (Be median ratio 0.21; unstimulated median ratio 0.04). The median ratio of mature TNF-alpha mRNA:beta-actin mRNA was upregulated 1.4-fold (Be median ratio 0.17; unstimulated median ratio 0.12). Be exposure in the presence of the transcription inhibitor pentoxifylline (PTX) decreased CBD BAL cell TNF-alpha pre-mRNA levels > 60%, whereas treatment with the mRNA splicing inhibitor 2-aminopurine (2AP) decreased levels 40% relative to Be exposure alone. PTX treatment decreased mature TNF-alpha mRNA levels 50% while 2AP decreased levels > 80%, relative to Be exposure alone. Beryllium exposure specifically upregulated transcription factors AP-1 and NF-kappaB. The data suggest that Be exposure induces transcription-dependent TNF-alpha production, potentially due to upregulation of specific transcription factors.

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.

Secondary ion mass spectroscopy demonstrates retention of beryllium in chronic beryllium disease granulomas

OBJECTIVE

We hypothesized that beryllium (Be) might persist in lung granulomas in patients with chronic beryllium disease (CBD).

METHODS

A total of 33 Be-exposed ceramics workers underwent transbronchial biopsy. They were classified based on histopathology and Be-lymphocyte proliferation test as CBD or other categories. Lung tissue sections were analyzed using secondary ion mass spectroscopy.

RESULTS

Be was detected in the lungs of all Be-exposed groups. Be levels were increased within the granulomas of patients with CBD compared with the Be levels outside granulomas. Notably, Be was detectable in the lungs of CBD patients who had ceased exposure to Be an average of 9 years previously.

CONCLUSIONS

Be was detected in the lungs of all Be-exposed subjects, with the highest levels of persistent Be inside CBD lung granulomas. Be antigen persistence may help explain the chronicity of this granulomatous disorder.

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.

Beryllium-stimulated reactive oxygen species and macrophage apoptosis

Beryllium (Be), the etiologic agent of chronic beryllium disease, is a toxic metal that induces apoptosis in human alveolar macrophages. We tested the hypothesis that Be stimulates the formation of reactive oxygen species (ROS) which plays a role in Be-induced macrophage apoptosis. Mouse macrophages were exposed to 100 microM BeSO4 in the absence and presence of the catalytic antioxidant MnTBAP (100 microM). Apoptosis was measured as the percentage of TUNEL+ and caspase-8+ cells. ROS production was measured by flow cytometry using the fluorescence probes, dihydroethidine (DHE) and dichlorofluorescein diacetate (DCFH-DA). Be-exposed macrophages had increased TUNEL+ cells (15+/-1% versus controls 1+/-0.2%, P<0.05) and increased caspase-8+ cells (18.7+/-2% versus controls 1.8+/-0.4%, P<0.05). Be-induced caspase-8 activation, and a 4-fold increase in ROS formation, was ameliorated by exposure to MnTBAP. Hydrogen peroxide (30 microM) exposure potentiated Be-induced caspase-8 activation, and was also attenuated by MnTBAP. Our data are the first to demonstrate that Be stimulates macrophage ROS formation which plays an important role in Be-induced macrophage apoptosis.

Beryllium-Ferritin

A beryllium (Be)-ferritin adduct containing 270 pm of Be stimulated proliferation of bronchoalveolar lavage (BAL) lymphocytes from subjects with chronic beryllium disease (CBD) at concentrations 5-6 logs lower than the amounts of beryllium sulfate (BeSO4) needed to induce proliferation. We observed increased apoptotic CBD BAL macrophages after exposure to both BeSO4 (50 +/- 6%, mean +/- SEM, P <0.05 versus unstimulated controls) and Be-ferritin (40 +/- 2%), whereas only 2.0 +/- 0.2% of BAL lymphocytes underwent activation-induced cell death. Be-ferritin also induced apoptosis in BAL macrophages from subjects with Be sensitization (25 +/- 3%) and in the H36.12j hybrid macrophage cell line (15 +/- 2%). Be-ferritin induced lung macrophage CD95 (Fas) expression and the activation of intracellular caspase-3, -8 and -9. Thus, lung macrophages take up Be-ferritin, delivering physiologically relevant levels of Be that promote Be antigen presentation and macrophage apoptosis. Be-ferritin thereby serves as a "Trojan Horse," triggering proliferation of Be-ferritin-specific CBD BAL T cells. We hypothesize that Be-ferritin exposure may result in persistent antigen exposure inducing Be-specific T cell clonal expansion and T cell helper type 1-type cytokine production and potentially explains the chronicity of CBD and its development years after environmental Be exposure has ceased.