Genetic susceptibility to scleroderma-like syndrome induced by vinyl chloride

Drugs associated with systemic sclerosis: An updated list of suspected drugs using the WHO pharmacovigilance database

OBJECTIVE

The pathophysiological mechanisms involved in systemic sclerosis (SSc), especially the triggering factor, are poorly understood. The literature supporting the role of drugs in the onset of SSc primarily relies on case reports, short series or previous studies of old drugs. We aimed to update the list of suspected drugs associated with SSc (DASSc).

METHODS

Analyzing the World Health Organization (WHO) pharmacovigilance database (Vigibase®), we collected all individual case safety reports (ICSRs) of drugs putatively associated with SSc reported since 1967 using the Medical Dictionary for Regulatory Activities preferred terms "systemic sclerosis" and "scleroderma". For each drug, a disproportionality analysis was performed by calculating the information component (IC). An identified drug was considered significant if the IC₀₂₅ was >0.

RESULTS

A total of 2800 deduplicated ICSRs of DASSc were identified, accounting for 509 ICSRs and 38 suspected DASSc after exclusion of protopathic and indication biases. Anticancer drugs were the most represented drug class, accounting for 16/38 (42%) of DASSc and 317/509 (62.3%) of ICSRs, which occurred mostly in the first years after the introduction of the drugs. Among these, taxane-based agents, bleomycin, vinblastine, imatinib, dacarbazine, pembrolizumab and pemetrexed were associated with the highest disproportionate reporting. Hormone replacement therapy, romiplostim and eculizumab were associated with a significant signal. DASSc was considered a serious adverse drug reaction in 404 (92%, n = 441) cases with 41 (9%) cases resulting in death.

CONCLUSION

Several new drugs with significant disproportionality signals were identified as potential drugs implicated the development of SSc, particularly anticancer drugs.

Drug-induced scleroderma-like lesion

Drug-induced scleroderma-like lesion is a condition in which administration of a drug induces skin sclerotic lesions similar to systemic sclerosis or morphea. The clinical manifestations of drug-induced scleroderma-like lesion can be divided into two types: scleroderma-like lesions and morphea-like plaques. A wide variety of drugs can cause drug-induced scleroderma-like lesion. Bleomycin, _L-tryptophan, vinyl chloride, and phytonadione (vitamin K₁) have been reported, but in recent years, cases due to chemotherapeutic agents, such as taxane-based agents, gemcitabine, and tegafur-uracil, and immune checkpoint inhibitors have increased. Drug-induced scleroderma-like lesion differs from systemic sclerosis in that it does not include Raynaud's phenomenon, nail-fold capillary abnormality, organ involvement, such as reflux esophagitis, interstitial pneumonia, renal crisis, or anti-nuclear Abs. On the other hand, there are reports of cases in which Raynaud's phenomenon, positive conversion of anti-nuclear Abs, and development of skin sclerosis from the fingers developed after initiation of the drug. Whether the skin sclerosis improves after discontinuation of the drug depends on the patient. In patients with severe skin sclerosis, functional impairment, such as flexion contracture of the fingers, may occur, and systemic therapy, such as steroids, may be necessary. When treating patients with skin sclerosis, it is important to keep in mind the possibility that the sclerotic lesion may be induced by a drug.

The frequency of Raynaud's phenomenon, very early diagnosis of systemic sclerosis, and systemic sclerosis in a large Veteran Health Administration database

BACKGROUND

We describe Raynauds phenomenon (RP), potential very early diagnosis of systemic sclerosis (VEDOSS), and systemic sclerosis (SSc) in Veterans deployed in support of Post-9/11 operations. We sought to describe the military occupation specialty, clinical features, and vasodilator use across the three diagnoses.

METHODS

Individual Veterans medical records were assessed for RP (ICD-9443.0), VEDOSS with swelling of hands (ICD-9729.81) and RP (ICD-9443.0), and SSc (ICD-9710.1). The distribution of sociodemographic, military service branch, job classification, vasodilator use, and comorbidities were examined across the three classifications of disease. The chi-squared test and Fisher's exact compared frequency of these categorical variables. Logistic regression assessed the likelihood of characteristics of the three classifications.

RESULTS

In this population of 607,665 individual Veteran medical records, 857 had RP, 45 met possible VEDOSS criteria, and 71 had a diagnosis of SSc. The majority of RP, potential VEDOSS and SSc cases were white males. Those in craftworks, engineering or maintenance, and healthcare had a greater likelihood of RP. Less than half of RP and VEDOSS patients were on vasodilators. The most common comorbidities in this population were the diagnostic code for pain (highest in the potential VEDOSS group [81.6%]), followed by depression in all groups.

CONCLUSION

This is a unique Veteran population of predominately-male patients. Our data suggests that vasodilator medications are potentially being under-utilized for RP and potential VEDOSS. Our data highlights mood and pain management as an important aspect of SSc care.

Toward Understanding of Environmental Risk Factors in Systemic Sclerosis [Formula: see text]

IMPORTANCE

Systemic sclerosis (SSc) is a severe, chronic, and incurable autoimmune fibrotic skin disease with significant extracutaneous involvement. Low concordance rate in twin studies and unequal geographic distribution of SSc argues for importance of environment in disease initiation and progression.

OBJECTIVE

In this manuscript we provide a summary of all investigated potential external risk factors for SSc.

DATA SOURCES

A literature search in PubMed and EMBASE database was performed for studies published until January 1, 2020 by 2 reviewers (EN and LO) independently.

FINDINGS

Occupational and/or environmental exposures to silica and organic solvents are associated with increased incidence and severity of SSc. Exposure to epoxy resins, asbestos, and particulate air pollution favors increased risk of SSc, but data are based on limited number of observational studies. There is insufficient evidence to conclude an association between SSc development and other occupational (eg, welding fumes) or personal exposures (eg, smoking, vitamin D deficiency). Association of SSc with silicone breast implants has been disproven. Infectious pathogens (eg, Helicobacter pylori and angiotropic viruses) and dysbiosis seem to play a role in SSc development and severity, but their role remains to be clarified.

CONCLUSIONS AND RELEVANCE

It may be prudent to counsel our patients with SSc (or those at risk of SSc) to avoid occupations with exposure to silica, organic solvents, asbestos and epoxy resins; restraint from smoking, using cocaine or drugs with pro-fibrotic potential. While the association between low vitamin D and SSc remains to be confirmed, we believe that SSc patients should be encouraged to maintain healthy vitamin D levels as benefits outweigh the risks.

Systemic sclerosis

Systemic sclerosis, also called scleroderma, is an immune-mediated rheumatic disease that is characterised by fibrosis of the skin and internal organs and vasculopathy. Although systemic sclerosis is uncommon, it has a high morbidity and mortality. Improved understanding of systemic sclerosis has allowed better management of the disease, including improved classification and more systematic assessment and follow-up. Additionally, treatments for specific complications have emerged and a growing evidence base supports the use of immune suppression for the treatment of skin and lung fibrosis. Some manifestations of the disease, such as scleroderma renal crisis, pulmonary arterial hypertension, digital ulceration, and gastro-oesophageal reflux, are now treatable. However, the burden of non-lethal complications associated with systemic sclerosis is substantial and is likely to become more of a challenge. Here, we review the clinical features of systemic sclerosis and describe the best practice approaches for its management. Furthermore, we identify future areas for development.

Skin fibrosis: Models and mechanisms

Matrix synthesis, deposition and remodeling are complex biological processes that are critical in development, maintenance of tissue homeostasis and repair of injured tissues. Disturbances in the regulation of these processes can result in severe pathological conditions which are associated with tissue fibrosis as e.g. in Scleroderma, cutaneous Graft-versus-Host-Disease, excessive scarring after trauma or carcinogenesis. Therefore, finding efficient treatments to limit skin fibrosis is of major clinical importance. However the pathogenesis underlying the development of tissue fibrosis is still not entirely resolved. In recent years progress has been made unraveling the complex cellular and molecular mechanisms that determine fibrosis. Here we provide an overview of established and more recently developed mouse models that can be used to investigate the mechanisms of skin fibrosis and to test potential therapeutic approaches.

The Pathogenesis of Systemic Sclerosis

Systemic sclerosis is a multisystem disorder with a high associated mortality. The hallmark abnormalities of the disease are in the immune system, vasculature, and connective tissue. Systemic sclerosis occurs in susceptible individuals and is stimulated by initiating events that are poorly understood at present. In order for the disease phenotype to appear there is dysfunction in the homoeostatic mechanisms of immune tolerance, endothelial physiology, and extracellular matrix turnover. The progression of disease is not sequential but requires simultaneous dysfunction in these normal regulatory mechanisms. Better understanding of the interplay of these factors is likely to contribute to improved treatment options.

Molecular activation of the NLRP3 Inflammasome in fibrosis: common threads linking divergent fibrogenic diseases

SIGNIFICANCE

Over the past 10 years, there has been a plethora of investigations centering on the NLRP3 inflammasome and its role in fibrosis and other disease pathologies. To date, the signaling pathways from the inflammasome to myofibroblast differentiation and chronic collagen synthesis have not been fully elucidated, and many questions are left to be answered.

RECENT ADVANCES

Recent studies have demonstrated the significant and critical role of reactive oxygen species (ROS) and calcium signaling in the assembly of the inflammasome, and this may result in autocrine signaling maintaining the myofibroblast phenotype, leading to fibrotic disease.

CRITICAL ISSUES

Traditionally, myofibroblasts under tight regulation aid in wound healing and then, once the wound has closed, undergo apoptosis and the collagen in the wound remodels. During fibrosis, however, the myofibroblast maintains an activated state via a chronically activated inflammasome, leading to the continual synthesis of collagens and other extracellular matrix proteins that result in damage to the tissue or organ. The mechanism that is driving this abnormality has not been fully elucidated.

FUTURE DIRECTIONS

However, studies have been conducted to suggest that modulating the calcium or the ROS axis may be of therapeutic value in regulating inflammasome activation. A number of novel drugs are currently being developed that may prove beneficial to patients suffering from fibrotic diseases.

Graft-versus-host reactions: clues to the etiopathology of a spectrum of immunological diseases

Parental strain T lymphocytes injected into adult F, mice respond to allogeneic MHC antigens and so induce the symptoms of systemic graft v. host disease (GVHD). GVHD has two forms, stimulatory and suppressive, and in each there are pathological changes which resemble those seen in a variety of human disorders of immune regulation. In this article Ernst Gleichmann and his colleagues review the pathogenesis of these disorders and their induction by GVH reactions.

Organic solvents as risk factor for autoimmune diseases: a systematic review and meta-analysis

BACKGROUND

Genetic and epigenetic factors interacting with the environment over time are the main causes of complex diseases such as autoimmune diseases (ADs). Among the environmental factors are organic solvents (OSs), which are chemical compounds used routinely in commercial industries. Since controversy exists over whether ADs are caused by OSs, a systematic review and meta-analysis were performed to assess the association between OSs and ADs.

METHODS AND FINDINGS

The systematic search was done in the PubMed, SCOPUS, SciELO and LILACS databases up to February 2012. Any type of study that used accepted classification criteria for ADs and had information about exposure to OSs was selected. Out of a total of 103 articles retrieved, 33 were finally included in the meta-analysis. The final odds ratios (ORs) and 95% confidence intervals (CIs) were obtained by the random effect model. A sensitivity analysis confirmed results were not sensitive to restrictions on the data included. Publication bias was trivial. Exposure to OSs was associated to systemic sclerosis, primary systemic vasculitis and multiple sclerosis individually and also to all the ADs evaluated and taken together as a single trait (OR: 1.54; 95% CI: 1.25-1.92; p-value<0.001).

CONCLUSION

Exposure to OSs is a risk factor for developing ADs. As a corollary, individuals with non-modifiable risk factors (i.e., familial autoimmunity or carrying genetic factors) should avoid any exposure to OSs in order to avoid increasing their risk of ADs.

Systemic sclerosis: environmental factors

Epidemiological evidence for the association between environmental and occupational risk factors and systemic sclerosis (SSc) has been extensively analyzed. Such exposures are frequently of long duration, and the inadequate classification of the type of exposure and other confounding variables may bias their estimated association with SSc. Environmental factors could be classified as occupational (silica, organic solvents), infectious (bacterial, viral), and non-occupational/non-infectious (drugs, pesticides, silicones). Understanding the link between environmental risk factors and the development of SSc is limited, due to the phenotypic and pathogenic heterogeneity of patients and disease, respectively, and also due to poor ability to assess environmental exposures quantitatively and the role of the gene-environment interactions in this disease. Global collaboration could increase the chance for a better use of the data obtained from a limited number of cases and also limited resources. Normalization and validation of biomarkers and questionnaires could also be very useful to reliably quantify environmental exposures.

Murine animal models of systemic sclerosis

Animal models of systemic connective tissue diseases have provided valuable insights into the causative mechanisms and the pathogenesis of these diseases, and have provided the means to test potentially useful therapeutic interventions. Although numerous animal models for systemic sclerosis (SSc) have been described, the most extensively studied are murine. One advantage of murine animal models is the large body of genetic information available for the mouse that is not available for other species. No animal model described to date reproduces precisely all manifestations of SSc. However, all animal models display tissue fibrotic changes similar to those present in SSc. The prudent interpretation of the results obtained from the study of animal models has provided substantial and valuable information about the pathogenesis of the human disease.

Systemic sclerosis: environmental and occupational risk factors

There is growing concern about the association between systemic sclerosis and certain environmental and occupational risk factors, including exposures to vinyl chloride, adulterated cooking oils, L-tryptophan, silica, silicone breast implants, organic solvents, and other agents such as epoxy resins, pesticides, and hand/arm vibration. This article highlights the current medical research that has examined these associations in scleroderma-like disorders and in systemic sclerosis.

Immunotoxicity of trichloroethylene: a study with MRL-lpr/lpr mice

In recent immunological studies, it has been suggested that trichloroethylene (TCE) participates in the onset of pneumatosis cystoides intestinalis (PCI) through a certain mechanism; however, the mechanism by which it develops remains unknown. Based on findings that secondary PCI is often linked with autoimmune disease, the possibility that some genetic or immunological mechanisms are involved in the development of PCI has been proposed. Pneumatosis cystoides intestinalis is not a type of disease where a dose-response relationship with TCE exposure can be recognized and it is difficult to reproduce its physiopathology through TCE exposure in ordinary experimental animals. In the present study, immunological changes caused by TCE exposure were investigated by employing MRL-lpr/lpr mice that are genetically labile to autoimmune diseases. To observe changes in B cell functions, serum antibody titres were measured; and for the T cell function, T cell subsets were examined. The animals were exposed to TCE at dosages of 0, 500, 1000 and 2000 ppm through inhalation 4 h a day, 6 days a week, for 8 weeks. It was found that only IgG production capacity was suppressed and there were no changes in T cell subsets with TCE concentrations up to 1000 ppm. At a concentration of 2000 ppm, changes were noted in both T and B cell functions. Typical organs that are responsible for immunological functions were examined for their morphological changes under a light microscope: the spleen and liver exhibited dose-response changes at a concentration of 500 ppm or greater. The development of immunoblastoid cells at a concentration of 1000 ppm indicated a possibility that a change has occurred in the immunological system. These findings show that exposure to TCE at high concentrations affects the immune system, but the study failed to induce PCI in the experimental animals. Further studies on TCE exposure at lower concentrations for longer periods are needed.

Autoimmune diseases associated with drugs, chemicals and environmental factors

Autoimmune connective tissue diseases are complex multisystems and may be life threatening. Their aetiology is unknown but genetic, hormonal and environmental factors are important. In systemic lupus erythematosus (SLE), factors such as UV light and drugs, including oestrogen, may trigger the disease; silica exposure may also be important. Scleroderma is associated with silica exposure and drugs such as bleomycin and pentazocine may induce scleroderma-like diseases. Organic solvents such as vinyl chloride and epoxy resins may also be associated with scleroderma-like illnesses. The toxic oil syndrome and eosinophila-myalgia syndrome are best known examples of connective tissue diseases induced by chemical exposure. The systemic vasculitides and in particular cutaneous vasculitis may be induced by drugs and possibly environmental factors. A number of autoimmune connective tissue diseases may therefore be associated with exposure to drugs, chemicals and environmental factors and the risks associated with these should be minimised where possible.

Epidemiology of organic solvents and connective tissue disease

Case reports suggest that solvents are associated with various connective tissue diseases (systemic sclerosis, scleroderma, undifferentiated connective tissue disease, systemic lupus erythematosis, and rheumatoid arthritis), particularly systemic sclerosis. A small number of epidemiological studies have shown statistically significant but weak associations between solvent exposure, systemic sclerosis, and undifferentiated connective tissue disease. However, the interpretation of these positive findings is tempered by a lack of replication, an inability to specify which solvents convey risk, and an absence of increasing risk with increasing exposure. Existing studies, on aggregate, do not show conclusively that solvents (either as a group of chemicals or individual chemicals) are causally associated with any connective tissue disease. Further investigations should be carried out to replicate the positive existing findings and to specify the solvents and circumstances of exposure that carry risk.

Increased prevalence of systemic sclerosis in a Native American tribe in Oklahoma. Association with an Amerindian HLA haplotype

OBJECTIVE

To investigate a high prevalence of systemic sclerosis (SSc; scleroderma) in a well-defined population of 21,255 Choctaw Indians residing in 8 southeastern Oklahoma counties who were "users" of Indian Health Services.

METHODS

A case-control study of 12 SSc cases and 48 matched non-SSc controls (4 per case) was conducted to investigate potential occupational, residential, and infectious exposures, as well as genetic factors which might predispose to SSc. HLA class II alleles were determined by DNA oligotyping, and class I and III alleles were defined serologically.

RESULTS

The prevalence of SSc in full-blooded Choctaws was at least 8/1,704, or 469/100,000 (95% confidence interval [95% CI] 203-930) over the 4-year interval 1990-1994 and was significantly higher than that among non-full-blooded Choctaws (6/19,551, or 31/100,000) (P = 0.00001, odds ratio [OR] = 15.4, 95% CI 4.9-49.8). The overall prevalence of SSc in Oklahoma Choctaws (66/100,000) also was significantly higher than that in other Native Americans in Oklahoma (9.5/100,000) (P = 10(-6), OR = 6.95, 95% CI 3.3-13.7), who showed a prevalence similar to that reported for whites (2.1-25.3/100,000). Among the SSc cases, there was striking homogeneity of disease expression with the majority exhibiting diffuse scleroderma, pulmonary fibrosis, and autoantibodies to topoisomerase I. No environmental exposures were found to be in excess among cases versus controls. The strongest risk factor for SSc in cases (100%) versus controls (54%) was an HLA haplotype bearing the alleles B35, Cw4, DRB1*1602 (DR2), DQA1*0501, and DQB1*0301 (DQ7) (P = 0.002, Pcorr = 0.036, OR = 21, 95% CI 2.9-437). Survey of another group of Choctaws residing in another state revealed no cases of SSc despite a high frequency of the same HLA haplotype.

CONCLUSION

Full-blooded Choctaw Native Americans living in southeastern Oklahoma have the highest prevalence of SSc yet found in any population. A major risk factor for disease is a uniquely Amerindian HLA haplotype; however, additional genes and/or an as-yet-unidentified environmental exposure seem likely.

Occupational scleroderma. A 17-year follow-up study

Two patients with a scleroderma-like disorder induced by epoxy resins were reported from the Department of Dermatology, Gunma University School of Medicine, Japan in 1980. Here, we describe the clinical and laboratory characteristics of these patients after 17 years' follow-up from 1976 to 1993. Their systemic manifestations and indurated sclerotic skin changes disappeared within 5 years. No internal organ involvement has developed during the period of follow-up. On routine laboratory tests, no abnormalities have been found in the peripheral blood or in the blood chemistry or serology. Histological examination revealed atrophy of the dermis and restoration of the normal pattern of fine collagen bundles, when compared with the previous skin biopsy specimens. This scleroderma-like disorder induced by epoxy resins is considered to be different from systemic sclerosis: it has an acute onset and a fairly good prognosis, and does not show involvement of the internal organs.

Sclerodermatous syndrome after occupational exposure to herbicides--response to systemic steroids

We report a case of generalized cutaneous sclerosis associated with muscle and oesophageal involvement in a patient exposed to herbicides containing bromocil, diuron and aminotriazole. Treatment with oral prednisolone resulted in some improvement in the cutaneous signs, particularly over the face, trunk and proximal limbs. The considerable exposure to chemicals, time course and unusual pattern of organ involvement suggested a diagnosis of occupational scleroderma.

Nodular scleroderma in a worker using a silica-containing abrasive

A patient with progressive systemic sclerosis and high levels of serum IgE developed multiple papules at/on an area of non-sclerotic skin. Histologic examination of the papule revealed the typical features of scleroderma. For several years, the patient had been working on polishing watches with an abrasive agent composed mainly of aluminum, chromium dioxide, and silica. An association of the abrasive agent, especially of the silica component, with the scleroderma was circumstantially suspected. To the best of our knowledge, this is the first report of nodular scleroderma which occurred in the course of PSS being associated with chemical agents.

Systemic sclerosis in Iceland. A nationwide epidemiological study

OBJECTIVES

To investigate the incidence, prevalence and clinical features of systemic sclerosis (SS) in Iceland.

METHODS

All patients diagnosed with SS from 1975-90 were included. Retrieval for the study began in 1980 and was carried out by computerised search from registers of all hospitals and health care clinics and death registration files, and with personal communication with doctors in Iceland.

RESULTS

Over a 16 year period from 1975-90, 15 new cases were found with an incidence of 0.7 and 0.05/100,000, for females and males at risk respectively, and 0.38 for both sexes. At the end of 1990 there were 18 patients alive with SS, 13 with limited and five with diffuse cutaneous involvement. The age standardised prevalence was 11.9 and 1.5/100,000 for females and males at risk respectively. The crude prevalence rate for both sexes was 7.1/100,000. There were five deaths, two patients died of SS related causes, one had SS renal disease. The relative risk of death was similar to that in the general population. The calculated five year survival rate was 100% and the 10 year survival rate 81%. No HLA antigen association was found.

CONCLUSION

Compared with previous surveys this study shows a low incidence of systemic sclerosis and a high proportion of patients with limited cutaneous involvement.

Epidemiology of systemic sclerosis

Systemic sclerosis is a family of disorders most appropriately considered in the category of the connective tissue diseases. Two major forms are recognized (diffuse cutaneous and limited cutaneous involvement subtypes), each with distinctive clinical and serologic findings as well as natural history. Scleroderma is characterized epidemiologically by several distinctive features. From a demographic viewpoint, the disease spares children and its incidence increases steadily with age among adults. If occurs much more frequently in women, especially during the child-bearing years, and most often and most severely in young black women, though there is no overall prominent racial predilection. The annual incidence approaches 20 per million population, and may be considerably underestimated. Both incidence and mortality have increased during the past several decades, but these changes are most likely a result of improved case detection rather than a true increase in incidence. Prevalence studies have not been undertaken, but 500 per million population may be a reasonable estimate. Family and genetic studies suggest a weak genetic predisposition, but several strong HLA associations with scleroderma-specific serum autoantibodies are evident. Certain environmental agents may be implicated in pathogenesis of scleroderma and closely related systemic illnesses associated with cutaneous fibrosis. The widespread pathologic process in systemic sclerosis leads to vascular insufficiency and fibrosis, which diminishes the reserve function of many organ systems. The result is considerable disability, especially affecting hand function, and a significant reduction in life span, with an overall 10-year survival from first physician diagnosis of under 70%. Further epidemiologic studies should take full advantage of established and newly proposed subsets of patients with homogeneous clinical, laboratory, serologic, and natural history features. The environment-host interactions noted here must be fully explored, especially in early untreated disease, where primary rather than secondary mechanisms are most likely to be operative.

Localized scleroderma in childhood: a report of 30 cases

Localized scleroderma (LS), a rare disease that occurs primarily in the pediatric age group, differs from systemic sclerosis (SSc) in that it is usually limited to the skin and subcutaneous tissue and is only rarely associated with systemic manifestations. The authors' experience with pediatric LS seen in 30 patients at a tertiary care center was reviewed: 26 had linear scleroderma, 19 on an extremity and 7 on the face; 3 had morphea; and 1 had generalized morphea. Antinuclear antibodies were present in 76% and rheumatoid factor in 39%. Five of 19 patients with linear scleroderma that involved an extremity had growth failure in that limb, and 1 required surgery. Sclerodermatous involvement over a joint resulted in limited range of movement in 6 patients, and 1 required surgery. One of the 30 patients developed SSc and polymyositis. There was difficulty in evaluating disease activity and hence in evaluating treatment. This experience with a large patient population suggests that LS, although usually a self-limiting disease, can result in significant morbidity.

Systemic sclerosis

Systemic sclerosis affects the connective tissue of various organs. It is characterized by alteration of the microvasculature with a dense inflammatory cellular infiltrate, followed by massive deposition of collagen. This review discusses diagnostic criteria, clinical subsets, survival data, clinical evaluation, epidemiology, pathogenesis, immunobiology, genetics, and therapy for systemic sclerosis in adults. Because the diagnosis of systemic sclerosis is most dependent on its cutaneous involvement, knowledge of this is essential in the evaluation and management of patients with this disorder.

A sclerodermatous syndrome with unusual features following prolonged occupational exposure to organic solvents

We describe a sclerodermatous syndrome in a middle-aged man who had worked with a wide variety of organic solvents over a prolonged period. Associated changes included cold sensitivity, a restrictive lung defect, peripheral neuropathy, oesophageal dysfunction, labile hypertension and a monoclonal paraproteinaemia. This unique syndrome is discussed in relation to other disorders associated with exposure to organic solvents.

Antinuclear autoantibodies in women with silicone breast implants

Clinical syndromes resembling autoimmune diseases have been reported in women who have had breast augmentation procedures. To see whether there is a humoral immune response in these diseases that is similar to the immune response in their idiopathic counterparts, we assessed the immunological specificity of antinuclear antibodies (ANAs) and certain epidemiological features in 24 patients, all of whom (with 1 exception) had received silicone gel breast implants. ANA specificities were identified by indirect immunofluorescence, immunodiffusion, western blot analysis, and immunoprecipitation of radiolabelled intracellular proteins. Of 11 patients who had symptoms and signs that met criteria for defined autoimmune diseases, 7 had scleroderma or subsets of this disorder and the others had systemic lupus erythematosus, rheumatoid arthritis, or overlapping autoimmune diseases. High ANA titres were present in 10 of these 11 patients and the ANA specificities were similar to those found in the idiopathic forms of the corresponding autoimmune diseases. Trauma, with resultant rupture of implants, accelerated onset of symptoms. 13 other patients had autoimmune disorders of a less clearly defined nature and low titres of ANAs whose specificities could not be identified. ANAs are associated with the development of autoimmune complications in women with silicone breast implants. Further studies are needed to see whether this relation is one of cause and effect and whether ANAs might be early serological markers preceding development of autoimmune symptoms.

The immunogenetic background of scleroderma--an overview

Currently it may be stated that the MHC associations in scleroderma support the classification of disease subsets, but in no ethnic group is the overall association strong enough for clinical use. In different ethnic groups, the distribution of MHC alleles varies, as does the degree of linkage disequilibrium between alleles of the linked loci. This concept is even relevant to relatively close populations. Thus Whiteside noticed that, if those patients referred from more than 100 miles from the study centre were excluded, then the strength of the DR1 association increased. The environmental contribution to scleroderma is unknown, except in the case of toxin or solvent associated disease. Different causal environmental agents found in different global regions might result in separate MHC associations and hence explain the discrepancies noted above. There are indications that associations between specific subsets of SSc patients and genetic markers will assume greater importance both diagnostically and prognostically. The lung fibrosis group look prime candidates, for example. Genetic markers are also a useful means of relating chemically-induced SSc-like disorders to the classical disease. Vinyl chloride disease provides an example. There is much heterogeneity within the disease, in terms of extent of skin involvement, severity, and of organ involvement. It is clear that the different clinical subsets of scleroderma are characterized by different associated MHC alleles. There are also many cases of clinical overlap with related diseases, and certain of these diseases have a different HLA association, which could detract from the primary HLA type associated with SSc.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology of scleroderma

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Major histocompatibility complex class II genes and systemic sclerosis

1. In no ethnic group is the overall association between systemic sclerosis and the MHC strong enough for direct clinical use. MHC associations do support the classification of the disease into limited cutaneous systemic sclerosis and diffuse cutaneous systemic sclerosis. 2. Indications are that associations between specific subsets of patients with systemic sclerosis and genetic markers will assume greater importance both diagnostically and prognostically. The group with lung fibrosis look prime candidates, for example. 3. Genetic markers are useful means of relating chemically induced systemic sclerosis like disorders with the classical disease. Vinyl chloride disease provides an example. 4. Evidence is emerging of strong associations between certain genetic markers and autoantibody production; a similar story has emerged in systemic lupus erythematosus. We believe that, eventually, genetic tests will be used to influence treatment in at least a subset of patients with systemic sclerosis but that a dramatic breakthrough will not be made until we know how the genetics of the disease relate to the primary biochemical disease characteristic--that is, the overproduction of collagen. In this respect it has been suggested that the 5' flanking DNA of dermal collagen genes is particularly susceptible to the action of Scl-70 (topoisomerase I). A problem is how to tie this and the other observations discussed above together. The association of autoantibodies with topoisomerase I provides a tentative link between the MHC and collagen gene expression. Although the role and reason for anti-Scl-70 in systemic sclerosis is unknown, humoral autoimmunity, at least in systemic lupus erythematosus, seems to be strongly dependent on specific HLA genes. With an understanding of the function of MHC products at the molecular level, HLA and disease associations can now be analysed on a mechanistic level. For insulin dependent diabetes mellitus it has been shown that the MHC determined susceptibility to the disease is conferred by neutral residues (Val, Ser, Ala), at position 57 of the DQ beta chain, while Asp at this position correlates with resistance. A similar phenomenon has been described in rheumatoid arthritis. Although DR4 in general is associated with rheumatoid arthritis, it is heterogeneous, but a subtype of DR4 which is characterised by positively charged residues at positions 70 and 71 of the beta chains is not found in patients with rheumatoid arthritis (Wordsworth B P et al, unpublished data). A similar approach applied to the study of systemic sclerosis is likely to be similarly rewarding. The precise subtyping of the class II genes and the characterisation of their associated haplotypes is therefore required for a complete understanding of the contribution of the MHC to the disease. Additional genes linked to the MHC must not be overlooked, and are relevant to associations of haplotypes with the disease. Of particular interest are the recent reports of a new class of proteins, which are determined by genes in the MHC and which are considered to play a part in the assembly of the antigen peptide/MHC molecule complex.

Immunotoxicology: suppressive and stimulatory effects of drugs and environmental chemicals on the immune system. A discussion

The fundamental characteristic of the adaptive immune system which has evolved in the vertebrates is the ability to recognise, and subsequently destroy, "foreign", and potentially harmful, antigens. The selective advantage which the immune system confers is the capacity to resist infectious, and possibly malignant, disease. It has been apparent for many years that individuals in whom immune function is impaired, due either to a congenital defect or to other factors such as treatment with certain immunosuppressive drugs, exhibit an increased susceptibility to infection and, in some cases, an elevated risk of developing at least some forms of malignancy. There is an increasing awareness from rodent studies that a variety of drugs and environmental chemicals have the potential to unintentionally impair components of the immune system. Risk assessment, based upon data from chemically induced changes in one or more parameters of immune function, is, however, dependent upon a knowledge of the functional reserve of the immune system. One of the objectives of the meeting from which this report derives was to examine what sources of information are available, and what experimental protocols can be employed, to permit accurate evaluation of immunological reserve. Although, under normal circumstances, the immune system selectively and specifically recognises foreign antigen, it is clear that the potential to recognise "self" is present and that in certain circumstances this potential is realised. Antibodies directed against normal tissue antigens have been shown to be associated with, and in some instances the presumptive cause of, "autoimmune" disease. There is a growing list of drugs and chemicals which are capable of eliciting autoantibodies and pathological autoimmune reactions. A second purpose of this meeting and of this report was to review the current state of knowledge regarding drug- and chemical-induced autoimmunity.

Environmentally-induced systemic sclerosis-like illness

Interaction of the host immune system with certain substances found in the environment will, in the presence of other unknown factors such as genetic susceptibility, lead to aberrant immune responses manifested as disease. In most of the conditions discussed above, simple removal from exposure to the offending agent does not lead to resolution. This suggests that an ongoing response has been triggered which cannot immediately be turned off, perhaps due to continued presence of the substance such as in human adjuvant disease where paraffin or silicone has been found in lymphoid tissue. Scleroderma remains a disease of uncertain cause for which our present treatment is inadequate. Illnesses presented in this chapter resemble the natural form of the disease in many ways and may provide useful insight into its pathogenesis. In the short term, recognition of exposure to environmental hazards which appear to pose risk will prevent additional cases of disabling illness. Study of chemically induced forms of scleroderma may, in the future, allow us to predict potential toxicity of chemically similar compounds. If we could learn how they trigger disease, researchers might be able to apply the information to understanding the pathogenesis of naturally-occurring scleroderma.

Familial clustering of scleroderma spectrum disease

This is the second case report of familial scleroderma (systemic sclerosis) in South Carolina. The family includes two cases of scleroderma meeting American Rheumatism Association criteria, one of systemic sclerosis sine scleroderma, and two other cases of undifferentiated connective tissue disease with features of scleroderma spectrum disorders; there are also two cases of Raynaud's phenomenon (one associated with rheumatoid arthritis), for a total of seven affected relatives. Evidence of scleroderma spectrum disorders was sought in six siblings of the two co-index cases and in 23 of the 35 offspring. Laboratory studies included antinuclear antibody determinations and typing for the following genetic markers: HLA (A, B, C, DR), complotypes, Gm and Km allotypes, and alpha-1 antitrypsin phenotypes. No common genetic markers restricted to affected members of this family were found, and no environmental exposures were detected that could explain this familial clustering of cases. This report should, however, add to the slowly accumulating information on the genetic characteristics of families at unusually high risk for scleroderma spectrum disorders. Positive antinuclear antibody tests at a titer of 1/40 or higher were present in 57 percent of the first-degree relatives of the affected cases.