Different distribution of HLA class II alleles in anti-topoisomerase I autoantibody responders between silicosis and systemic sclerosis patients, with a common distinct amino acid sequence in the HLA-DQB1 domain

Beyond very early systemic sclerosis: deciphering pre‑scleroderma and its trajectories to open new avenues for preventive medicine

The identification of individuals with systemic sclerosis in an oligosymptomatic phase preceding the very early manifestations of the disease represents a challenge in the search for a new window of opportunity in systemic sclerosis. This phase could be identified in a clinical scenario as the pre-scleroderma phase, in which the disease would still be far from systemic sclerosis-related fibrotic or irreversible manifestations in skin or organs. In this Personal View, we discuss parameters and candidate definitions for a conceptual framework of pre-scleroderma, from the identification of populations at risk to autoantibodies and their potential functional activities. We discuss how this new paradigm of pre-scleroderma could represent a game-changing approach in the management of systemic sclerosis, allowing the treatment of patients at high risk of organ involvement or skin fibrosis before such events occur.

Classical Examples of the Concept of the ASIA Syndrome

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) was first introduced in 2011 by Shoenfeld et al. and encompasses a cluster of related immune mediated diseases, which develop among genetically prone individuals as a result of adjuvant agent exposure. Since the recognition of ASIA syndrome, more than 4400 documented cases have been reported so far, illustrated by heterogeneous clinical manifestations and severity. In this review, five enigmatic conditions, including sarcoidosis, Sjögren's syndrome, undifferentiated connective tissue disease, silicone implant incompatibility syndrome (SIIS), and immune-related adverse events (irAEs), are defined as classical examples of ASIA. Certainly, these disorders have been described after an adjuvant stimulus (silicone implantation, drugs, infections, metals, vaccines, etc.) among genetically predisposed individuals (mainly the HLA-DRB1 and PTPN22 gene), which induce an hyperstimulation of the immune system resulting in the production of autoantibodies, eventually leading to the development of autoimmune diseases. Circulating autonomic autoantibodies in the sera of patients with silicone breast implants, as well as anatomopathological aspects of small fiber neuropathy in their skin biopsies have been recently described. To our knowledge, these novel insights serve as a common explanation to the non-specific clinical manifestations reported in patients with ASIA, leading to the redefinition of the ASIA syndrome diagnostic criteria.

Mechanisms of Environment-Induced Autoimmunity

Although numerous environmental exposures have been suggested as triggers for preclinical autoimmunity, only a few have been confidently linked to autoimmune diseases. For disease-associated exposures, the lung is a common site where chronic exposure results in cellular toxicity, tissue damage, inflammation, and fibrosis. These features are exacerbated by exposures to particulate material, which hampers clearance and degradation, thus facilitating persistent inflammation. Coincident with exposure and resulting pathological processes is the posttranslational modification of self-antigens, which, in concert with the formation of tertiary lymphoid structures containing abundant B cells, is thought to promote the generation of autoantibodies that in some instances demonstrate major histocompatibility complex restriction. Under appropriate gene-environment interactions, these responses can have diagnostic specificity. Greater insight into the molecular and cellular requirements governing this process, especially those that distinguish preclinical autoimmunity from clinical autoimmunedisease, may facilitate determination of the significance of environmental exposures in human autoimmune disease.

Clinical evaluation of CENP-B and Scl-70 autoantibodies in silicosis patients

Silicosis patients (SIL) suffer from respiratory disorders and dysregulation of autoimmunity. Frequent complications such as rheumatoid arthritis, systemic sclerosis (SSc) and vasculitis are known in SIL. Furthermore, we reported previously that some SIL exhibited better respiratory conditions in association with a worse immunological status. In this study, the clinical roles of anti-CENP-B and Scl-70 autoantibodies in SIL were analyzed. The titer index (Log10) of anti-CENP-B autoantibody in SIL was higher than that of healthy volunteers (HV), and that of SSc was higher than those of HV and SIL. This titer index was positively correlated with an assumed immune status of 1 for HV, 2 for SIL, and 3 for SSc. Moreover, although factor analysis revealed that the titer index of the anti-CENP-B autoantibody formed the same factor with the anti-Scl-70 autoantibody, IgG value and age in SIL cases, another extracted factor indicated that the IgA value and anti-Scl-70 antibody were positively related, but anti-CENP-B showed an opposite pattern in the results of the factor analysis. These findings indicated that the titer index of anti-CENP-B autoantibody may be a biomarker for dysregulation in SIL cases. Future clinical follow-up of SIL may therefore require both respiratory and immunological assessment.

Alterations of Fas and Fas-Related Molecules in Patients with Silicosis

Persons with silicosis have not only respiratory disorders but also autoimmune diseases. To clarify the mechanisms involved in the dysregulation of autoimmunity found in patients with silicosis, we have been focusing on Fas and Fas-related molecules in the Fas-mediated apoptotic pathway, because Fas is one of the most important molecules regulating autoimmunity involving T cells. Our findings showed that patients with silicosis exhibited elevated serum soluble Fas levels, an increased relative expression of the soluble fas and dcr3 genes in peripheral blood mononuclear cells, high levels of other variant messages of the fas transcript, relatively decreased expression of genes encoding several physiological inhibitors (such as survivin and toso), and dominancy of lower-membrane Fas expressers in lymphocytes, which transcribe soluble fas dominantly, compared with soluble fas transcription in healthy donors. These findings are consistent with known features regarding immunological factors, such as serum immunogulobulin G levels and the titer of anti-nuclear autoantibodies in silicosis. In addition, anti-caspase 8 autoantibody and anti-Fas autoantibody were detected in serum specimens from patients with silicosis, and a functional assay showed that anti-Fas antibody stimulated Fas-mediated apoptosis. We hypothesize that there are two subpopulations of silicosis lymphocytes. One is a long-term surviving fraction that includes self-recognizing clones showing lower levels of membrane Fas and inhibition of Fas/Fas ligand binding in extracellular spaces. The other subpopulation exhibits apoptosis caused by silica and silicates, is recruited from bone marrow, shows higher levels of membrane Fas, and is sensitive to anti-Fas autoantibody. Further investigation should be performed to confirm the effects of silica and silicates on the human immune system.

Human Leukocyte Antigen and Systemic Sclerosis in Japanese: The Sign of the Four Independent Protective Alleles, DRB1*13:02, DRB1*14:06, DQB1*03:01, and DPB1*02:01

Objective

Several studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic sclerosis (SSc) have been reported. Anti-centromere antibodies (ACA) and anti-topoisomerase I antibodies (ATA) are found in SSc patients. Here, we sought to identify HLA alleles associated with SSc in Japanese, and explored their associations with SSc phenotypes including the presence of autoantibodies.

Methods

Associations of HLA-DRB1, DQB1, and DPB1 were analyzed in 463 Japanese SSc patients and 413 controls.

Results

We found that DRB1*13:02 (P = 0.0011, Pc = 0.0319, odds ratio [OR] 0.46, 95% confidence interval [CI] 0.29–0.73), DRB1*14:06 (P = 6.60X10^-5, Pc = 0.0020, OR 0.05, 95%CI 0.01–0.41), DQB1*03:01 (P = 0.0009, Pc = 0.0150, OR 0.56, 95%CI 0.40–0.79), and DPB1*02:01 (P = 5.16X10^-6, Pc = 8.77X10^-5, OR 0.52, 95%CI 0.39–0.69) were protectively associated with SSc. In addition, these four alleles seemed to be independently associated with the protection against the susceptibility of SSc. On the other hand, we could not find predisposing alleles for overall SSc. With respect to SSc subsets, a tendency for these four alleles to be protectively associated was observed. However, there was a significant association between DRB1*01:01, DRB1*10:01, DQB1*05:01, and DPB1*04:02 and the susceptibility to SSc with ACA. On the other hand, the presence of DRB1*15:02, DQB1*06:01, DPB1*03:01, and DPB1*09:01 was associated with SSc with ATA.

Conclusion

Thus, the present study has identified protective associations of the four HLA class II alleles with overall Japanese SSc and predisposing associations of HLA class II alleles with Japanese SSc subsets.

Genetics of Interstitial Lung Disease: Vol de Nuit (Night Flight)

Interstitial lung disease (ILD) is a chronic, progressive fibrotic lung disease with a dismal prognosis. ILD of unknown etiology is referred to as idiopathic interstitial pneumonia (IIP), which is sporadic in the majority of cases. ILD is frequently accompanied by rheumatoid arthritis (RA), systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), and other autoimmune diseases, and is referred to as collagen vascular disease-associated ILD (CVD-ILD). Susceptibility to ILD is influenced by genetic and environmental factors. Recent advances in radiographic imaging techniques such as high-resolution computed tomography (CT) scanning as well as high-throughput genomic analyses have provided insights into the genetics of ILD. These studies have repeatedly revealed an association between IIP (sporadic and familial) and a single nucleotide polymorphism (SNP) in the promoter region of the mucin 5B (MUC5B). HLA-DRB1*11 alleles have been reported to correlate with ILD in European patients with SSc, whereas in Japanese patients with RA, the HLA-DR2 serological group was identified. The aim of this review is to describe the genetic background of sporadic IIP, CVD-ILD, drug-induced-ILD (DI-ILD), pneumoconiosis, and hypersensitivity pneumonitis. The genetics of ILD is still in progress. However, this information will enhance the understanding of the pathogenesis of ILD and aid the identification of novel therapeutic targets for personalized medicine in future.

Silica exposure and altered regulation of autoimmunity

Silica particles and asbestos fibers, which are known as typical causatives of pneumoconiosis, induce lung fibrosis. Moreover, silicosis patients often complicate with autoimmune diseases, and asbestos-exposed patients suffer from malignant diseases such as pleural mesothelioma and lung cancer. We have been conducting experimental studies to investigate altered regulation of self-tolerance caused by silica exposure, including analyses using specimens such as plasma and immunocompetent cells obtained from silicosis patients, as a means of examining the supposition that silica exposure induces molecular and cellular biological alterations of immune cells. These approaches have resulted in the detection of several specific autoantibodies, alterations of CD95/Fas and its related molecules, and evidence of chronic activation of responder T cells and regulatory T cells following silica exposure. In this review, we present details of our investigations as an introduction to scientific approaches examining the immunological effects of environmental and occupational substances.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) 2013: Unveiling the pathogenic, clinical and diagnostic aspects

In 2011 a new syndrome termed 'ASIA Autoimmune/Inflammatory Syndrome Induced by Adjuvants' was defined pointing to summarize for the first time the spectrum of immune-mediated diseases triggered by an adjuvant stimulus such as chronic exposure to silicone, tetramethylpentadecane, pristane, aluminum and other adjuvants, as well as infectious components, that also may have an adjuvant effect. All these environmental factors have been found to induce autoimmunity by themselves both in animal models and in humans: for instance, silicone was associated with siliconosis, aluminum hydroxide with post-vaccination phenomena and macrophagic myofasciitis syndrome. Several mechanisms have been hypothesized to be involved in the onset of adjuvant-induced autoimmunity; a genetic favorable background plays a key role in the appearance on such vaccine-related diseases and also justifies the rarity of these phenomena. This paper will focus on protean facets which are part of ASIA, focusing on the roles and mechanisms of action of different adjuvants which lead to the autoimmune/inflammatory response. The data herein illustrate the critical role of environmental factors in the induction of autoimmunity. Indeed, it is the interplay of genetic susceptibility and environment that is the major player for the initiation of breach of tolerance.

Autoimmune/inflammatory syndrome induced by adjuvants (Shoenfeld's syndrome): clinical and immunological spectrum

An adjuvant is a substance that enhances the antigen-specific immune response, induces the release of inflammatory cytokines, and interacts with Toll-like receptors and the NALP3 inflammasome. The immunological consequence of these actions is to stimulate the innate and adaptive immune response. The activation of the immune system by adjuvants, a desirable effect, could trigger manifestations of autoimmunity or autoimmune disease. Recently, a new syndrome was introduced, autoimmune/inflammatory syndrome induced by adjuvants (ASIA), that includes postvaccination phenomena, macrophagic myofasciitis, Gulf War syndrome and siliconosis. This syndrome is characterized by nonspecific and specific manifestations of autoimmune disease. The main substances associated with ASIA are squalene (Gulf War syndrome), aluminum hydroxide (postvaccination phenomena, macrophagic myofasciitis) and silicone with siliconosis. Mineral oil, guaiacol and iodine gadital are also associated with ASIA. The following review describes the wide clinical spectrum and pathogenesis of ASIA including defined autoimmune diseases and nonspecific autoimmune manifestations, as well as the outlook of future research in this field.

Dysregulation of the immune system caused by silica and asbestos

Silica and asbestos cause pneumoconioses known as silicosis and asbestosis, respectively, that are each characterized by progressive pulmonary fibrosis. While local effects of inhaled silica particles alter the function of alveolar macrophages and sequential cellular and molecular biological events, general systemic immunological effects may also evolve. One well-known health outcome associated with silica exposure/silicosis is an increase in the incidence of autoimmune disorders. In addition, while exposure to silica--in the crystalline form--has also been seen to be associated with the development of lung cancers, it remains unclear as to whether or not silicosis is a necessary condition for the elevation of silica-associated lung cancer risks. Since asbestos is a mineral silicate, it would be expected to also possess generalized immunotoxicological effects similar to those associated with silica particles. However, asbestos-exposed patients are far better known than silicotic patients for development of malignant diseases such as lung cancer and mesothelioma, and less so for the development of autoimmune disorders. With both asbestos and crystalline silica, one important dysregulatory outcome that needs to be considered is an alteration in tumor immunity that allows for silica- or asbestos- (or asbestos-associated agent)-induced tumors to survive and thrive in situ. In this review, the immunotoxicological effects of both silica and asbestos are presented and contrasted in terms of their abilities to induce immune system dysregulation that then are manifest by the onset of autoimmunity or by alterations in host-tumor immunity.

[Immunological effects of silica/asbestos]

Silica and asbestos cause pneumoconioses known as silicosis and asbestosis, respectively, that are each characterized by progressive pulmonary fibrosis. On the other hand, silicosis patients often suffer from a type of immunological dysregulation that gives rise to autoimmunity. These epidemiological findings suggest that silica may affect the immune system in humans. In addition, as asbestos itself is a mineral silicate, it may possess generalized immunotoxicological effects similar to those associated with silica particles. Because asbestos-exposed patients are well-known to often develop malignant diseases such as lung cancer and mesothelioma, one silica-like dysregulatory outcome that needs to be considered (apart from autoimmunity) is an alteration in host tumor immunity. In this review, the immunotoxicological effects of both silica and asbestos are presented and discussed in terms of immune system dysregulation as manifested by the onset of autoimmunity or alterations in host tumor immunity.

HLA class II DR and DQ genotypes and haplotypes associated with rheumatic fever among a clinically homogeneous patient population of Latvian children

The HLA system is being paid more and more attention because it is very significant in polymorphous immunological reactions. Several studies have suggested that genetic susceptibility to rheumatic fever (RF) and rheumatic heart disease (RHD) is linked to HLA class II alleles. We hypothesized that HLA class II associations within RHD may be more consistent if analysed amongst patients with a relatively homogeneous clinical outcome. A total of 70 RF patients under the age of 18 years were surveyed and analysed in Latvia. HLA genotyping of DQA1, DQB1 and DRB1 was performed using PCR with amplification with sequence-specific primers. We also used results from a previous study of DQB1 and DRB1 genotyping. In the RF patients, HLA class II DQA1*0401 was found more frequently compared to DQA1*0102. In the RF homogeneous patient groups, DQA1*0402 has the highest odds ratio. This is also the case in the multivalvular lesion (MVL) group, together with DQA1*0501 and DQA1*0301. In the chorea minor patients, DQA1*0201 was often found. Significant HLA DQA1 protective genotypes were not detected, although DQA1 genotypes *0103/*0201 and *0301/*0501 were found significantly and frequently. In the distribution of HLA DRB1/DQA1 genotypes, *07/*0201 and *01/*0501 were frequently detected; these also occurred significantly often in the MVL group. The genotype *07/*0201 was frequently found in Sydenhamn's chorea patients that had also acquired RHD, but DRB1*04/DQA1*0401 was often apparent in RF patients without RHD. In the distribution of HLA DQA1/DQB1 genotypes, both in RF patients and in the homogeneous patient groups, the least frequent were *0102/*0602-8. The genotype DQA1*0501 with the DQB1 risk allele *0301 was often found in the MVL group. The genotype *0301/*0401-2 was frequently found in the RF and Sydenhamn's chorea patient groups. The haplotype *07-*0201-*0302 was frequently found in RF and homogeneous patient groups, including the MVL group. In addition, haplotypes *04-*0401-*0301 and *04-*0301-*0401-2 were frequent amongst patients with Sydenhamn's chorea. The protective alleles DQA1*0102 and DQB1*0602-8 in the haplotype DRB1*15 were less frequently found in RF patients. The results of the present study support our hypothesis and indicate that certain HLA class II haplotypes are associated with risk for or protection against RHD and that these associations are more evident in patients in clinically homogeneous groups.

Genetic basis for systemic sclerosis

Among the connective tissue diseases, systemic sclerosis is an orphan disease in which diffuse connective tissue alterations lead to multi-organ involvement. Environmental factors implicated in triggering this multifactorial disease include crystalline silica, chlorine solvents, welding vapors, and various other solvents. Clustering within families indicates a role for genetic factors. Although concordance for the disease among identical twins is low, concordance for autoantibodies associated with systemic sclerosis and for fibroblast gene expression profiles is higher. Because multiplex families are rare, association and candidate gene strategies are the most appropriate methods for investigating the genetics of systemic sclerosis. The most consistent data relate to the involvement of fibrosis genes, most notably the TGF-beta regulation pathway, secreted protein acid and rich in cysteine (SPARC) genes, and the fibrillin-1 gene (FBN1). Several variants of genes for cytokines or their receptors may be involved. Data on the vasculopathy characteristic of systemic sclerosis are somewhat conflicting. Investigations into the genetics of systemic sclerosis may shed light on the complex pathophysiology of this disease, help to identify factors that predict organ involvement, and suggest new treatment strategies.

Involvement of IL-10 and Bcl-2 in resistance against an asbestos-induced apoptosis of T cells

To analyze the possibility that immunological alteration in asbestos-related diseases (ARDs) such as asbestosis (ASB) and malignant mesothelioma (MM) may affect the progression of cancers, a human adult T cell leukemia virus-immortalized T cell line (MT-2Org) was continuously exposed to 10 mug/ml of chrysotile-B (CB), an asbestos. After at least 8 months of exposure, the rate of apoptosis in the cells became very low and the resultant subline was designated MT-2Rst. The MT-2Rst cells were characterized by (i) enhanced expression of bcl-2, with regain of apoptosis-sensitivity by reduction of bcl-2 by siRNA, (ii) excess IL-10 secretion and expression, and (iii) activation of STAT3 that was inhibited by PP2, a specific inhibitor of Src family kinases. These results suggested that the contact between cells and asbestos may affect the human immune system and trigger a cascade of biological events such as activation of Src family kinases, enhancement of IL-10 expression, STAT3 activation and Bcl-2 overexpression. This speculation was partially confirmed by the detection of elevated bcl-2 expression levels in CD4 + peripheral blood T cells from patients with MM compared with those from patients with ASB or healthy donors. Further studies will be required to verify the role of T cells with enhanced bcl-2 expression in tumor progression induced by asbestos exposure.

Gene-environment interactions in asthma and other respiratory diseases

It is generally agreed that many lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) have polygenic inheritance, and that the association of a specific genotype or genotypes with the disease is likely to vary between populations. Furthermore, it is recognized that the etiology of many lung diseases involves a complex interplay between genetic background and exposure to multiple environmental stimuli, and understanding the mechanisms through which genes and environment interact represents a major challenge for pulmonary researchers. We discuss experimental approaches and challenges that must be overcome to identify disease genes for asthma, COPD and chronic bronchitis, and occupational lung diseases. In particular, common polymorphisms in CD14, glutathione S-transferase, and tumor necrosis factor alpha have been found to be important in gene-environment interaction and asthma pathogenesis. An understanding of gene-environment interactions in complex lung diseases is essential to the development of new strategies for lung disease prevention and treatment.

Anti-caspase-8 autoantibody response in silicosis patients is associated with HLA-DRB1, DQB1 and DPB1 alleles

We reported previously the autoantibodies directed to caspase-8 among patients with silicosis, systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) , and in healthy individuals. In this study, we analyzed the correlation between anti-caspase-8 autoantibody responses and HLA class II alleles in silicosis patients. The frequencies of HLA-DRB1*0406 were significantly higher in antibody positive patients (16.67%) than in control individuals (3.03%, p=0.0006). The lysine (K) at position 71 as in DRB1*0406 has been reported to be associated with rheumatoid arthritis (RA) and insulin dependent diabetes mellitus (IDDM). The haplotype HLA-DR4; DQB1*0302 was detected in 4 of 12 antibody positive patients. RA, IDDM, or pemphygus vulgaris link to the haplotype. The frequencies of DQB1*0401 were significantly lower in antibody positive patients (0%) than that in controls (13.33%, p=0.0390). The aspartic acid at position 57 in the DQB1 molecule as in DQB1*0401 is reported to play a role in the resistance to IDDM. The frequency of DPB1*0601 in antibody positive patients (5.88%) was significantly higher than that in controls (0.56%, p=0.0003). DPB1*0601 is reported to be a risk factor among RA patients, and glutamate at position 69 of the DPB1 molecule may be involved. Repeated and continuous screening of autoantibodies seems to be necessary among workers in contact with Si-related substances for the detection of immunological disorders in the early stage.

Induction of CD69 antigen expression in peripheral blood mononuclear cells on exposure to silica, but not by asbestos/chrysotile-A

While cases of silicosis are often complicated by various autoimmune disorders, patients with asbestosis develop malignant tumors such as lung cancer and malignant mesothelioma. These differences may derive from different biological effects, particularly on immunological cells, of silica and asbestos. To find differences between silica and asbestos, the early activation antigen, CD69, on T cells was examined because dysregulated and continuous activation of T cells may promote the survival of self-recognizing T cells. After cultivation of peripheral blood mononuclear cells with or without silica or chrysotile-A, an asbestos, only silica induced CD69 expression on the lymphocytes. This induction of CD69 expression was mediated by protein kinase C activation. In addition, cell-cell contact mediated by HLA-DR was more important than soluble factors secreted from silica-phagocytosed cells such as IL-1beta, IL-6, and IL-8, even though IL-6 and IL-8 were produced during the culture of PBMCs with silica and chrysotile-A. It should be examined how these activated, CD69-expressing lymphocytes affect other immune systems as well as alter themselves in terms of cytokine production and cell-cell interaction, leading to autoimmune disorders in silicosis patients.