Connective tissue diseases after heavy exposure to silica: a report of nine cases in stonemasons

Environmental Risks for Systemic Sclerosis

There is an increasing body of literature suggesting a relationship between environmental factors and the development of systemic sclerosis (SSc). These include occupational exposures, chemical materials, medications, alterations in the microbiome, and dysbiosis. Environmental exposures may impact epigenetic regulation thereby triggering an aberrant immune response resulting in the clinical and serologic phenotype that we diagnose as SSc. Screening and studying putative triggers will not only improve our understanding of the pathogenesis of SSc but also inform the institution for protective measures.

Rheumatological Diseases in Denim Sandblasters with Silicosis: What Should Pulmonologists Look for?

OBJECTIVE

Silica exposure is not only the cause of silicosis, also associated rheumatological diseases like rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and systemic sclerosis (SSc). This report will reveal the rheumatological diseases of silicosis patients who were exposed to silica while working as denim sandblasters. Additionally, we will describe some clinical and laboratory findings that will help pulmonologist suspect, recognize and manage rheumatological diseases related to silica exposure in patients with silicosis.

MATERIAL AND METHODS

We reviewed the records of 142 sandblasters diagnosed with silicosis and found ten silicosis cases who also had rheumatological diseases between the years 2009 and 2017. The occupational characteristics, serological, functional and radiological data, were collected for patients of silicosis with rheumatological diseases.

RESULTS

Ten silicosis patients with concomitant rheumatological diseases were found. Six patients among our cases had diagnosed SSc (4.2%), three of them had RA (2.1%), and one of them was being monitored for SLE (0.7%). The mean silica exposure time of the cases was 4.3±1.9 years (min: 1 max: 8). We also found elevated LD, sedimentation and CRP levels in our cases.

CONCLUSION

It should be kept in mind that, in silicosis cases with arthralgia, joint tenderness or sclerosis at the fingertips may be indicative of rheumatological diseases related to silica exposure, and in these cases, the unexplained elevations of sedimentation and CRP levels may also be a result of silica-induced rheumatological diseases.

[Silica-associated systemic sclerosis occurring after an occupational exposure to arc welding]

La sclérodermie systémique liée à l’exposition à la silice cristalline peut apparaître chez les personnes utilisant la soudure à l’arc. Une forme diffuse de sclérodermie a été diagnostiquée chez un plombier-soudeur de 57 ans, qui présentait des polyarthralgies inflammatoires, un phénomène de Raynaud, une sclérodactylie, une sclérose cutanée diffuse, des télangiectasies, une atteinte œsophagienne, une hypertension artérielle pulmonaire et une fibrose pulmonaire associées à la présence d’anticorps anti-nucléosomes. Au cours de son activité professionnelle, le patient était fréquemment exposé à des concentrations atmosphériques élevées de silice cristalline lors de la soudure à l’arc. Le diagnostic d’un syndrome d’Erasmus avec une association d’une sclérodermie systémique à une silicose pulmonaire était retenu. Une déclaration en maladie professionnelle au titre du tableau n°17 en Tunisie a été réalisée.

Identification of an Association of TNFAIP3 Polymorphisms With Matrix Metalloproteinase Expression in Fibroblasts in an Integrative Study of Systemic Sclerosis-Associated Genetic and Environmental Factors

OBJECTIVE

Systemic sclerosis (SSc) is a fibrotic disease attributed to both genetic susceptibility and environmental factors. This study was undertaken to investigate the associations between SSc-associated genetic variants and the expression of extracellular matrix (ECM) genes in human fibroblasts stimulated with silica particles in time-course and dose-response experiments.

METHODS

A total of 200 fibroblast strains were examined for ECM gene expression after stimulation with silica particles. The fibroblasts were genetically profiled using Immunochip assays and then subjected to whole-genome genotype imputation. Associations of genotypes and gene expression were first analyzed in a Caucasian cohort and then validated in a meta-analysis combining the results from Caucasian, African American, and Hispanic subjects. A linear mixed model for longitudinal data analysis was used to identify genetic variants associated with the expression of ECM genes, and the associations were validated by using a haplotype-based longitudinal association test on regions that included the loci identified.

RESULTS

The single-nucleotide polymorphism rs58905141 in TNFAIP3 was consistently associated with time-course and/or dose-response expression of MMP3 and MMP1 in the fibroblasts stimulated with silica particles in both the analysis of Caucasian subjects only and the meta-analysis. Results of the haplotype-based analysis validated the association signals.

CONCLUSION

Our findings indicate that a genetic variant of TNFAIP3 is strongly associated with the silica-induced profibrotic response of fibroblasts. In silico functional analysis based on the ENCODE database revealed that rs58905141 might affect the binding activities of the transcription factors for TNFAIP3. This is the first genome-wide study of interactions between genetic and environmental factors in a complex SSc fibroblast model.

Sjögren's Syndrome and Silicosis - a Case Report

Sjögren’s syndrome is an autoimmune disease of unknown etiology where immune response to self-antigens is believed to result from interactions between genetic and environmental factors. We describe the case of a patient who has been diagnosed with Sjögren’s syndrome based on typical clinical and immunological parameters. The clinical picture was dominated by the respiratory symptoms, and radiographic and multislice computed tomography examination of the chest showed certain changes characteristic of pneumoconiosis. Given that the patient has worked in a foundry where he has been exposed to the silica dust, he was subject to examination by occupational health specialists under the suspicion of lung silicosis, who confirmed the silicosis. This case report points to the possible connection between a professional exposure to silica and Sjögren’s syndrome. Occupational exposure to silica is a possible risk factor for the development of autoimmune diseases, and in the evaluation of patients with connective tissue diseases it is important to consider work-related history.

Occupational exposure in patients with the antisynthetase syndrome

Interstitial lung disease (ILD) is common in patients with myositis and is related with the presence of antisynthetase autoantibodies (aSA). Together with other manifestations, the resulting condition is known as the antisynthetase syndrome (ASS). Contact with certain environmental and occupational agents is also associated with the development of ILD. The objective of this study was to analyze occupational exposure and associated clinical manifestations in a cohort of patients with ASS. aSA had been identified by line immunoassay and confirmed by immunoprecipitation. Serial pulmonary function tests had been carried out to assess lung function. Thirty-two ASS patients and a control group of 32 myositis patients without aSA underwent a specific questionnaire interview to evaluate their cumulative exposure to biological dust, mineral dust, and gases/fumes up to disease onset. Comparisons were done with the Fisher exact test and Mann-Whitney test. Out from 32 ASS patients (median age, 42.7 yeras; IQR 32.2-52.5), twenty-six patients had anti-Jo-1, three anti-PL-12, and three anti-PL-7. Nine had polymyositis, 15 dermatomyositis, one amyopathic dermatomyositis, and seven pure ILD without myositis. Sixteen ASS patients (50 %) and seven (22 %) myositis patients without aSA had ever been highly exposed to dust, gases, or fumes (p < 0.05). A more than 10 % improvement in forced vital capacity occurred in 61 % of highly exposed patients and 23 % of those with low/no exposure (p = 0.06) over the observation period. In conclusion, a high percentage of patients with ASS had been exposed to dusts, gases, or fumes.

Impact of Age and Autoantibody Status on the Gene Expression of Scleroderma Fibroblasts in Response to Silica Stimulation

Environmental factors are believed to play an important role in the pathogenesis of systemic sclerosis (SSc). Silica exposure has been implicated as potentially hazardous in epidemiological studies of SSc. It can activate fibroblasts to express profibrotic genes at certain conditions. The aim of this study is to examine whether the fibroblasts of SSc patients respond to silica particles with specific gene expressions differentially from normal control fibroblasts. The fibroblasts obtained from skin biopsies of 96 SSc patients and 104 controls were examined. Silica particles were used to perturb the cultures of the fibroblasts in time-course and dose-response assays. The transcript levels of COLI A2, COL3A1, MMP1, MMP3, TIMP3 and CTGF genes of the fibroblasts were measured with quantitative RT-PCR. The results showed that the expressions of all six genes in SSc fibroblasts under silica perturbation appeared significantly different from normal control fibroblasts. In age stratified analysis, compared to control fibroblasts, SSc fibroblasts from patients at age 30–40 years and 50–60 years displayed significantly decreased expressions of MMP1 gene in all dosage assays and increased expression of COL3A1 genes started at low dosages perturbation of silica particles, respectively. In autoantibody stratified analysis, specific gene expression patterns were significantly associated with autoantibody-subgroups of fibroblasts. A common feature of SSc fibroblasts was unstable and a wide range of gene expression changes in response to silica perturbation. Our studies may suggest an altered intrinsic dynamic control in SSc fibroblasts. In addition, sensitivity and specificity of SSc fibroblasts to potentially hazardous environmental trigger is age and autoantibody-subgroup-dependent. The fibroblasts of SSc patients at age 30–60 years may be more sensitive to silica perturbation toward a profibrotic gene expression.

Silicon, a Possible Link between Environmental Exposure and Autoimmune Diseases: The Case of Rheumatoid Arthritis

Silicon is one of the most common chemicals on earth. Several compounds such as silica, asbestos, silicone or, nanoparticles are built from tetrahedral units with silicon as the central atom. Despite these, structural similarities, they have rarely been analyzed as a group. These compounds generate significant biological alterations that include immune hyperactivation, production of the reactive species of oxygen and tissue injury. These pathological processes may trigger autoimmune responses and lead to the development of rheumatoid arthritis. Populations at risk include those that constantly work in industrial process, mining, and agriculture as well as those that undergo silicone implants. Herein a review on the main features of these compounds and how they may induce autoimmune responses is presented.

Acrylamine-induced autoimmune phenomena

The objective of this study is to document a series of cases of occupationally derived autoimmune disease. Individuals with occupational exposure to acrylamides were evaluated clinically and biochemically/immunologically for evidence of autoimmune disease. Symptoms and signs and immuno-reactivity were monitored during exposure-free and re-exposure as part of the individuals' clinical evaluation. Six individuals with occupational acrylamide exposure had clinical and laboratory alterations characteristic of drug-induced autoimmune disease, specifically lupus, anti-phospholipid syndrome, Sjogren's syndrome, scleroderma, and polymyositis. The similarity of the full spectrum of disease in the reported patients to that found with procainamide strongly suggests the effects of occupational exposure. This uncontrolled study suggests the need for a full epidemiologic analysis of all individuals working with such occupational exposure, including full clinical and immunological examination.