Primary Sjögren's syndrome and occupational risk factors: A case–control study
Introduction
Sjögren's syndrome (pSS) is a systemic disease that was originally described in 1956 by Bloch et al. [1] Its prevalence is of 0–5% with a female preponderance (9 female to one male) [2], [3]. It is an autoimmune epithelitis characterized by eye and mouth dryness and lymphocytic infiltration of the salivary glands [3], [4], [5]. Apart from dryness, clinical presentation generally comprises asthenia and arthralgia [6], [7]. Moreover, the disease can extend beyond the exocrine glands and systemic manifestations including vasculitis, lung, renal or neurological involvement can potentially occur. In addition patients with pSS have an increased risk of lymphoma [8], [9]. As for other autoimmune diseases, it is associated with specific genetic background, impaired immune response and environmental factors [10]. Such factors are believed to trigger an innate immune response which leads to an activation of glandular cells and an alteration of glandular vascular endothelium [3], [11]. These phenomenon are followed by an activation of B and T lymphocytes within the glands which leads to cell destruction, cytokine production such as type I and II interferon [12], and autoantibodies secretion [3], [10]. Impaired salivary and lachrymal secretions are the consequence of the glandular dysfunction. To date, only a few environmental factors have been identified in pSS. Only weak associations with viruses have been reported and less than ten cases of patients with pSS exposed to silica were reported [13], [14], [15]. Occupational exposure to silica is known to be associated with autoimmune diseases such as systemic sclerosis and systemic lupus erythematosus [16], [17]. Therefore we hypothesized that occupational risks factors are associated with pSS. Herein we report a multicentric French case–control study that investigated the relationship between pSS and occupational exposure.
Section snippets
Patients
One hundred seventy five patients with pSS followed up in departments of Internal Medicine of the University Hospitals of Tours (France), Rouen (France), and Angers (France), from 2010 to 2013 were included in the study. pSS was defined according to the American-European Consensus Group (AECG) criteria [18].
Two age (±5 years) and gender matched controls were selected for each case. Controls were selected during the same period of time in the same departments. Subjects with connective tissue
Results
Between January 2010 and December 2013, 175 pSS patients and 350 matched controls were included in the study. Table 1 shows socioeconomic data of cases and controls. There was no difference between cases and controls for smoking habit and socio-economic levels and socio-professional categories were similar.
One hundred sixty eight patients (96%) reported ocular and oral symptoms. One hundred fifty patients (85.7%) had ocular signs and 50 patients (28.6%) had salivary gland involvement. Anti-SSA
Discussion
This case–control study shows that occupational exposure to certain organic solvents (chlorinated, aromatic) is associated with an increased risk of pSS. Our work is the first case–control study to evaluate occupational exposure in pSS. As our population was homogeneous because we only included patients with pSS and excluded patients with other autoimmune disease, we estimate that our results are highly specific for pSS.
As for other autoimmune diseases, environmental factors are believed to
Conclusion
In conclusion, this case–control study suggests the influence of occupational exposure in the development of pSS, especially exposure to white spirit or chlorinated or aromatic solvents, whereas exposure to crystalline silica is not associated with pSS. Further studies are needed to confirm a causative role in the development of the disease.
Competing interests
None.
Funding
None.
Contributorship statement
All authors have contributed to the planning, the conduct, and the reporting of the work described in the study.
Acknowledgments
The authors are grateful to Mrs. Penelope Hodges for her precious help all along the study and to Mr. Benjamin Schwartz for his precious comments on the manuscript.
References (31)
Sjögren’s syndrome
Lancet
(2005 Jul 23)- et al.
Sjögren’s syndrome: where do we stand, and where shall we go?
J. Autoimmun.
(2014 Jun) - et al.
Primary biliary cirrhosis and Sjogren's syndrome: autoimmune epithelitis
J. Autoimmun.
(2012 Aug) - et al.
Familial Sjögren’s syndrome with associated primary salivary gland lymphoma
Am. J. Med.
(1976 Feb) - et al.
Pathophysiology of primary Sjögren’s syndrome
Rev. Med. Interne
(2014 Aug) - et al.
Silicosis and primary Gougerot-Sjögren syndrome
Rev. Med. Interne
(1994) - et al.
Prospective study to evaluate the association between systemic sclerosis and occupational exposure and review of the literature
Autoimmun. Rev.
(2014 Feb) - et al.
Occupational exposures and autoimmune diseases
Int. Immunopharmacol.
(2002 Feb) - et al.
Lymphoma development in patients with autoimmune and inflammatory disorders–what are the driving forces?
Semin. Cancer Biol.
(2014 Feb) - et al.
Sjoegren's syndrome. A clinical, pathological, and serological study of sixty-two cases
Med. Baltim.
(1965 May)