Cigarette smoking and the risk of primary Sjögren's syndrome: a nested case control study

The analysis of the pulmonary domain involvement in Sjögren's disease

Background

The EULAR Sjögren's syndrome (SS) disease activity index (ESSDAI) pulmonary domain is used to assess the activity of respiratory system involvement in Sjögren's disease (SjD). The most unfavorable form of respiratory involvement in SjD, after lymphomas, is interstitial lung disease (ILD).

Objectives

The aim of the study was to assess the involvement of the respiratory system in SjD patients and the occurrence of ILD in high-resolution computed tomography (HRCT), depending on immunological markers, the influence of cigarette smoking, and the age of the patients.

Design

Single-center, registry, cohort study.

Methods

Among all SjD patients, a group with involvement in the pulmonary domain was distinguished. This group was later subjected to a detailed analysis of immunological and serological markers and chest imaging tests.

Results

In all, 64 patients out of 299 with SjD had involvement in the pulmonary domain defined according to the ESSDAI definition. The most frequently reported clinical symptoms of respiratory system involvement included dryness and chronic cough (over 80% of patients), followed by shortness of breath. Nine percent of patients with changes in lungs were asymptomatic. Patients with pulmonary involvement were older (54 vs 48 years, p < 0.05). In the subpopulation of patients with SjD and pulmonary involvement, the presence of rheumatoid factor (73% vs 60%, p < 0.05), and hematological domain involvement according to ESSDAI (54% vs 37%, p < 0.05) were more common. In the group of 64 patients with a positive pulmonary domain, 34 (53%) had ILD on HRCT. A higher incidence of comorbidities was found in the population of patients with ILD. No correlation was found between the type of lung involvement and the immunological profile, inflammatory markers, age, and smoking habit.

Conclusion

Involvement of the pulmonary domain is common in patients with SjD. However, the clinical picture is very heterogeneous, which determines the subsequent personalization of treatment.

The Impact of Tobacco Smoking on Systemic Sclerosis, Idiopathic Inflammatory Myositis, and Systemic Lupus Erythematosus

This narrative review aims specifically to explore the relationship between tobacco exposure and systemic sclerosis (SSc), idiopathic inflammatory myositis (IIM), and systemic lupus erythematosus (SLE). Relevant articles were obtained by searching key terms such as "tobacco," "smoking," "scleroderma," "myositis," "lupus," and "Sjögren's" in PubMed and Google Scholar databases. The selected articles ranged from the years 2010 to 2023. Inclusion criteria were based on the relevance and contribution to the field of study. Systemic sclerosis is a complex condition involving multiple immune cell lines that can be influenced by tobacco. However, the existing literature does not provide sufficient evidence to support an increased risk of SSc in smokers or the impact on treatment options. Cigarette smoking does increase the risk of skin ulcerations in SSc patients. In addition, cigarette smoking has been associated with IIM through genetic and molecular mechanisms. Smokers with dermatomyositis or polymyositis are at an elevated risk of atherosclerosis and interstitial lung disease. Similarly, smoking in patients with SLE increases the risk of organ damage, thrombosis, and disease severity compared with non-smokers. Smokers with SLE also have more difficulty in controlling disease flares compared with non-smokers. Tobacco exposure can lead to secondary complications in patients with IIM and SLE, although the course of treatment may not differ significantly. No definitive conclusions can be drawn to the clear relationship between tobacco smoking and Sjögren's's syndrome.

Evolving understanding of autoimmune mechanisms and new therapeutic strategies of autoimmune disorders

Autoimmune disorders are characterized by aberrant T cell and B cell reactivity to the body's own components, resulting in tissue destruction and organ dysfunction. Autoimmune diseases affect a wide range of people in many parts of the world and have become one of the major concerns in public health. In recent years, there have been substantial progress in our understanding of the epidemiology, risk factors, pathogenesis and mechanisms of autoimmune diseases. Current approved therapeutic interventions for autoimmune diseases are mainly non-specific immunomodulators and may cause broad immunosuppression that leads to serious adverse effects. To overcome the limitations of immunosuppressive drugs in treating autoimmune diseases, precise and target-specific strategies are urgently needed. To date, significant advances have been made in our understanding of the mechanisms of immune tolerance, offering a new avenue for developing antigen-specific immunotherapies for autoimmune diseases. These antigen-specific approaches have shown great potential in various preclinical animal models and recently been evaluated in clinical trials. This review describes the common epidemiology, clinical manifestation and mechanisms of autoimmune diseases, with a focus on typical autoimmune diseases including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and sjögren's syndrome. We discuss the current therapeutics developed in this field, highlight the recent advances in the use of nanomaterials and mRNA vaccine techniques to induce antigen-specific immune tolerance.

Cigarette smoking and risk of adult-onset Still disease: a propensity score matching analysis

BACKGROUND

Environmental factors play an important role in the pathogenesis of rheumatic diseases. Smoking is thought to be a risk factor for autoimmune rheumatic diseases.

AIMS

The purpose of the present study was to assess the association between smoking and adult-onset Still disease (AOSD) and the effect of smoking on outcomes of this disease.

METHODS

In this case-control study, patients with AOSD who met the Yamaguchi criteria, were older than 16 years at the disease onset and were in follow-up for at least 12 months were consecutively enrolled in the study. The outcome of AOSD was assessed by acquiring remission on treatment, remission off treatment, time to remission and rate of flare. The smoking status of participants was defined by direct or phone interviews. Individuals who had smoked daily for at least 6 months were defined as a smoker. We performed propensity score matching analyses by using four parameters, including age, sex, educational status and marital status.

RESULTS

Propensity score matching resulted in 72 patients with AOSD and 216 matched controls. The number of ever smokers in the AOSD and control groups were 11 (15.3%) and 25 (11.6%) respectively. There was no significant increase in the risk of AOSD in multivariate analysis after adjustment for age, sex, marital status and educational level. There were no significant differences in the outcomes of AOSD between ever and never smokers.

CONCLUSIONS

Smoking probably is not a risk factor for AOSD and did not affect the response to treatment.

Epidemiology of Sjögren syndrome

Sjögren syndrome is a phenotypically varied autoimmune disorder that can occur alone in primary Sjögren syndrome or in association with other connective tissue diseases (CTDs), including rheumatoid arthritis, systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). The estimation of the prevalence and incidence of Sjögren syndrome varies depending on diagnostic criteria and study design, making it difficult to estimate geographical and temporal trends. Nonetheless, disease phenotype is influenced by geographical origin, which is a risk factor for systemic activity. Whether mortality in primary Sjögren syndrome is increased compared with that of the general population is not yet known, but extra-glandular manifestations, in particular lymphomas, are clear risk factors for mortality. In CTDs associated with Sjögren syndrome, lymphoma risk seems higher than that of patients with CTD alone, and there is potentially lower disease activity in SLE with Sjögren syndrome and in SSc with Sjögren syndrome than in SLE or SSc alone.

Organophosphate esters concentrations in human serum and their associations with Sjögren syndrome

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers due to their excellent properties. The interference of OPEs on immune function has been proven, but the epidemiological data on OPEs exposure to related immune function diseases, such as sjögren syndrome (SjS), is limited. In cross-sectional study, 283 serum samples were collected from healthy individuals (n = 145) and patients with SjS (n = 138) in Hangzhou, China. Eight OPEs, triethyl phosphate (TEP), tributyl phosphate (TBP), tris (2-chloroethyl) phosphine (TCEP), triphenyl phosphate (TPHP), tri (1-chloro-2-propyl) phosphate (TCIPP), 2-ethylhexyldi-phenyl phosphate (EHDPP), tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), and tri (2-butoxyethyl) phosphate (TBOEP), were frequently measured in serum samples. In addition, we explored the associations between the serum OPEs concentration and the risk of SjS. Results showed that TEP (mean controls 2.17 and cases 3.63 ng/mL) was the most abundant OPEs in the serum samples of the control and case groups, followed by TCIPP (mean controls 0.54 and cases 0.78 ng/mL). Serum TEP, TPHP, and EHDPP concentrations were positively correlated with SjS [odds ratio (OR): 1.97, 1.96, and 2.42, respectively; 95% confidence interval (CI):1.34-2.89, 1.34-2.87, and 1.34-2.87, respectively] in the adjusted model, and a negative correlation of TBP concentrations with SjS in the adjusted model (OR: 0.35, 95% CI: 0.17-0.70) was observed. Compared with the lowest quartile concentrations, the ORs of SjS at the highest quartile concentrations of TEP (OR: 4.93, 95% CI: 2.24-10.82) and TPHP (OR: 4.75, 95% CI:1.89-11.94) were significantly higher. This study suggests that human exposure to OPEs may increase the risk of SjS.

Genetics and epigenetics of primary Sjögren syndrome: implications for future therapies

In primary Sjögren syndrome (pSS), chronic inflammation of exocrine glands results in tissue destruction and sicca symptoms, primarily of the mouth and eyes. Fatigue, arthralgia and myalgia are also common symptoms, whereas extraglandular manifestations that involve the respiratory, nervous and vascular systems occur in a subset of patients. The disease predominantly affects women, with an estimated female to male ratio of 14 to 1. The aetiology of pSS, however, remains incompletely understood, and effective treatment is lacking. Large-scale genetic and epigenetic investigations have revealed associations between pSS and genes in both innate and adaptive immune pathways. The genetic variants mediate context-dependent effects, and both sex and environmental factors can influence the outcome. As such, genetic and epigenetic studies can provide insight into the dysregulated molecular mechanisms, which in turn might reveal new therapeutic possibilities. This Review discusses the genetic and epigenetic features that have been robustly connected with pSS, putting them into the context of cellular function, carrier sex and environmental challenges. In all, the observations point to several novel opportunities for early detection, treatment development and the pathway towards personalized medicine.

Risk factors for primary Sjögren's Syndrome: a systematic review and meta-analysis

OBJECTIVES

The aim of this study was to analyze the risk factors for primary Sjögren's Syndrome (pSS) by conducting a meta-analysis of observational studies.

METHODS

Four electronic databases were searched from inception to August 2022. The search strategy included medical subject headings (MeSH) and text words. Outcomes were calculated and reported as the odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Twelve studies consisting of nine case-control and three cohort studies were analyzed. Significant positive relationships between infection, a family history of autoimmune disease in first-degree relatives, negative stressful life events, CGGGG insertion/deletion polymorphisms in the IRF5 gene and the onset of pSS were found, with pooled ORs and 95% CIs of 2.73 (1.93, 3.86), 5.93 (3.34, 10.52), 1.69 (1.27, 2.24) and 2.69 (1.97, 3.66), respectively. In contrast, the results showed that a history of smoking was not associated with the onset of pSS, with a pooled OR and 95% CI of 1.39 (0.76, 2.53). However, a statistically significant negative association between current smoking and pSS was detected, with a pooled OR and 95% CI of 0.4 (0.29, 0.83).

CONCLUSIONS

Our research indicated that infection, a family history of autoimmune disease in first-degree relatives, negative stressful life events and CGGGG insertion/deletion polymorphisms in the IRF5 gene might be risk factors for pSS. In contrast, our study demonstrated that a history of smoking was not associated with the onset of pSS, whereas current smoking was negatively associated with pSS onset.

SYSTEMATIC REVIEW REGISTRATION

We registered this review on INPLASY ( https://inplasy.com/ ) under registration number INPLASY202230005.

Sjögren Syndrome: New Insights in the Pathogenesis and Role of Nuclear Medicine

In the last years, new insights into the molecular basis of rheumatic conditions have been described, which have generated particular interest in understanding the pathophysiology of these diseases, in which lies the explanation of the diversity of clinical presentation and the difficulty in diagnostic and therapeutic approaches. In this review, we focus on the new pathophysiological findings for Sjögren syndrome and on the derived new SPECT and PET radiopharmaceuticals to detect inflammation of immunological origin, focusing on their role in diagnosis, prognosis, and the evaluation of therapeutic efficacy.

Sex differences in comorbidities associated with Sjögren's disease

Background

Little is known about the association of comorbidities with sex and age at diagnosis in Sjögren's disease. We tested the hypothesis that sex differences occur in comorbidities in patients with Sjögren's disease.

Methods

Patients with Sjögren's disease were identified from 11/1974 to 7/2018 in the Mayo Clinic electronic medical record and assessed for 22 comorbidities according to sex and age at diagnosis.

Results

Of the 13,849 patients identified with Sjögren's disease, 11,969 (86%) were women and 1,880 (14%) men, primarily white (88%) with a sex ratio of 6.4:1 women to men. The mean age at diagnosis was 57 years for women and 59.7 years for men, and 5.6% had a diagnosis of fibromyalgia at Sjögren's diagnosis. Men with Sjögren's disease were more likely than women to be a current or past smoker. The average time to diagnosis of comorbidities after diagnosis of Sjögren's disease was 2.6 years. The top comorbidities in patients with Sjögren's disease were fibromyalgia (25%), depression (21.2%) and pain (16.4%). Comorbidities that occurred more often in women were hypermobile syndromes (31:1), CREST (29:1), migraine (23:1), Ehlers-Danlos syndrome (EDS) (22:1), Raynaud's syndrome (15:1), SLE (13:1), systemic sclerosis (SSc) (13:1), and fibromyalgia (12:1). Women with Sjögren's disease were at increased risk of developing hypermobile syndromes (RR 7.27, CI 1.00-52.71, p = 0.05), EDS (RR 4.43, CI 1.08-18.14, p = 0.039), CREST (RR 4.24, CI 1.56-11.50, p = 0.005), migraine (RR 3.67, CI 2.39-5.62, p < 0.001), fibromyalgia (RR 2.26, CI 1.92-2.66, p < 0.001), Raynaud's syndrome (RR 2.29, CI 1.77-2.96, p < 0.001), SLE (RR 2.13, CI 1.64-2.76, p < 0.001), and SSc (RR 2.05 CI 1.44-2.92; p < 0.001). In contrast, men with Sjögren's were at increased risk for developing myocardial infarction (RR 0.44, CI 0.35-0.55, p < 0.001), atherosclerosis/CAD (RR 0.44, CI 0.39-0.49, p < 0.001), cardiomyopathy (RR 0.63, CI 0.46-0.86, p = 0.003), stroke (RR 0.66 CI 0.51-0.85, p = 0.001), and congestive heart failure (RR 0.70, CI 0.57-0.85, p < 0.001).

Conclusions

The top comorbidities in Sjögren's disease were fibromyalgia, depression, and pain. Women with Sjögren's disease had a higher relative risk of developing fibromyalgia, depression, pain, migraine, hypermobile syndrome, EDS and other rheumatic autoimmune diseases. Men with Sjögren's disease had higher risk of developing cardiovascular diseases.

Can smoking have a positive effect on the course of certain diseases? A systematic review

Background: Smoking cigarettes is a process during which many harmful substances are introduced into the lungs and the influence of these substances on the human body is not completely known. There are many diseases caused by smoking. Interestingly, there are also reports of positive consequences of smoking on some disorders. Aim of the study: The purpose of this article is to review the literature in regards to the diseases in which cigarettes might have a paradoxically beneficial effect — both on the onset and their course. We also want to focus on the mechanisms responsible for this impact. Material and Methods: Electronic searching of PubMed was performed. We analyzed articles published in the last 10 years with a particular emphasis on the most recent publications. Combinations of the following words were used: “smoking”, “nicotine”, and “autoimmune”. Publications were selected for reliability and non-bias. Results: A total of 69 articles out of 2979 qualified for the review. Only studies involving humans were included. The positive effect of smoking cigarettes is observed especially in immunological diseases. It is possible that it is mediated by both stimulating and suppressing the immune system. It is assumed that cigarettes can reduce the risk of developing certain diseases. Smoking might also have an impact on the course of different comorbidities in the same patient. Conclusions: There are many different mechanisms through which cigarette smoke and nicotine affect the human body. The harmful impact of these substances on one’s health has been demonstrated and their addictive component disqualifies them as remedies. Analysis of the mechanisms responsible for the beneficial effects of nicotine can lead to the search for new forms of therapy and prevention.

Smoking associated with reduced odds of Sjögren's syndrome among rheumatoid arthritis patients

OBJECTIVE

The objective of this medical record review study is to define the association between smoking and Sjӧgren's syndrome (SS) in a large rheumatoid arthritis (RA) cohort.

METHODS

Electronic health records from a population-based cohort were screened for RA eligibility between 2005 and 2018. Inclusion criteria were age ≥ 18 years, two or more RA diagnoses, including two diagnoses by a rheumatologist, or positive rheumatoid factor or anti-cyclic citrullinated peptide (anti-CCP) antibody. The independent variable, smoking status, was defined as never, current, or past. The outcome, SS, was defined by two or more ICD-9 codes. Multivariable logistic regression was performed to determine odds ratios (ORs) of SS adjusted for age, sex, and race.

RESULTS

Among 1861 patients with RA identified for cohort inclusion, 1296 had a reported smoking status. Current smokers were younger and less likely to be female than never smokers. The adjusted OR of current compared to never smokers was negatively associated with SS [OR 0.20, 95% confidence interval (CI) 0.06-0.65]. Female sex and age were associated with SS (OR 2.70, 95% CI 1.18-6.14; OR 3.75, 95% CI 1.23-11.4).

CONCLUSION

We report that RA patients who currently smoke had 80% lower odds of SS. Age had a 3.7-fold association and female sex a 2.7-fold association with SS among RA patients. Our data suggest a negative correlation between current smoking and prevalent SS among RA patients. Prospective studies examining pack-year relationships or smoking cessation could further examine risk reduction and causality to follow-up our cross-sectional observational study.

Associations Between Smoking and Primary Sjögren Syndrome Classification Using the Sjögren's International Collaborative Clinical Alliance Cohort

OBJECTIVE

The objective of this study was to examine the association of smoking with Primary Sjögren syndrome (pSS) classification and pSS diagnostic test results. We hypothesized that past and current smokers would have lower odds of being classified as having Sjögren syndrome (SS) and lower odds of having abnormal individual SS diagnostic test results compared with nonsmokers.

METHODS

Participants with suspected or established pSS were enrolled into the Sjögren's International Collaborative Clinical Alliance (SICCA) registry and had oral, ocular, and rheumatologic examinations performed; blood and saliva samples collected; and labial salivary gland biopsy examinations performed; they also completed questionnaires at baseline. Logistic regression was used to determine whether smoking status was associated with pSS classification and individual pSS diagnostic test results.

RESULTS

A total of 3514 participants were enrolled in SICCA. A total of 1541 (52.9%) met classification criteria for pSS. Compared with never smokers, current smokers had reduced odds of being classified as having pSS, reduced odds of having a focus score ≥ 1 and serologic positivity for anti-SSA/anti-SSB antibodies, and lower odds of having abnormal signs or test results of dry eye disease. Compared with never smokers, past smokers did not have a statistically significant reduction in odds of being classified as having pSS and of having abnormal individual pSS diagnostic test results.

CONCLUSION

Compared with never smokers, current smokers in the SICCA cohort had lower odds of being classified as having pSS, lower odds of exhibiting abnormal signs and test results for dry eye disease, and lower odds of having a labial salivary gland biopsy supportive of pSS classification. Such negative associations, however, do not suggest that current smoking is of any benefit with respect to pSS.

Preliminary Screening Questionnaire for Sjögren's Syndrome in the Rheumatology Setting

OBJECTIVE

Sjögren's syndrome (SS) is frequently undetected or misdiagnosed as other rheumatologic diseases. We aimed to develop an SS screening questionnaire for the rheumatology practice.

METHODS

We developed the Sjögren's Syndrome Screening Questionnaire (SSSQ) via secondary analysis of data from 974 participants referred by rheumatologists to the Sjögren's International Collaborative Clinical Alliance (SICCA) study. Participants answered 88 questions regarding symptoms, medical history, and demographics. They underwent ocular, dental, and serologic tests and were classified as SS or non-SS using the 2016 American College of Rheumatology/European League Against Rheumatism classification criteria. We conducted univariate and multivariate logistic regression to identify questions most discriminative of SS, from which we derived an individual's likelihood of SS ("SSSQ score").

RESULTS

Five questions were significantly discriminative of SS in the multivariate analysis (p < 0.05): (1) Can you eat a cracker without drinking a fluid/liquid? (no: odds ratio [OR], 1.39; 95% confidence interval [CI], 1.06-1.82]); (2) How would you describe your dental and oral health in general? (fair/poor: OR, 1.68; 95% CI, 1.04-2.75); (3) During the last week, have you experienced tearing? (none of the time: OR, 2.26; 95% CI, 1.23-4.34); (4) Are you able to produce tears? (no: OR, 1.62; 95% CI, 1.12-2.37); and (5) Do you currently smoke cigarettes? (no: OR, 2.83; 95% CI, 1.69-4.91). SSSQ score ≥7 (possible range, 0-11) distinguishes SS from non-SS patients with 64% sensitivity and 58% specificity (area under receiver operating characteristic curve, 0.65).

CONCLUSIONS

The SSSQ is a simple 5-item questionnaire designed to screen for SS in clinical practice, with a potential impact to reduce delays in diagnosis.

Airborne pollutants as potential triggers of systemic autoimmune rheumatic diseases: a narrative review

The pathogenesis of systemic autoimmune rheumatic diseases (SARDs) is complex and remains insufficiently understood. It is commonly accepted that both intrinsic and extrinsic environmental factors interact to induce a self-reactive immune response. Case reports and observational studies have revealed an association between SARDs and specific airborne environmental factors, but the heterogeneity of the published studies hampers clear conclusions. The aim of this review is to provide an overview of the available epidemiological evidence on the relationship between airborne pollutants and SARDs. We performed a narrative review using the PubMed database. Observational studies have shown significant associations between airborne pollutants and SARDs. Cigarette smoking is strongly associated with the development of rheumatoid arthritis (RA) while the association between cigarette smoke and the development of other SARDs remains controversial. For decades, silica exposure has been linked to systemic sclerosis (SSc), RA and systemic lupus erythematosus (SLE). There is also strong evidence for a link between solvents and SSc. Recent observations even suggest that ambient air pollution is associated with the development of SARDs. Some studies have shown associations between asbestos, organic dust, metals and pesticides and SARDs, but more studies are needed to confirm these findings. Increasing evidence has linked airborne pollutants to SARDs. Although more studies are needed to understand the potential mechanisms by which these environmental agents contribute to disease pathogenesis, awareness of the link between environmental agents and SARDs is important to recognize and prevent work-related and environmentally induced diseases.

BLK and BANK1 variants and interactions are associated with susceptibility for primary Sjögren's syndrome and with some clinical features

BLK and BANK1 in primary Sjögren's syndrome (pSS) have scarcely been evaluated and the results are inconclusive. The aim of our study was to determine whether single nucleotide variants (SNVs) located within BLK or BANK1 are associated with susceptibility, clinical and serological features, and smoking in pSS. BLK rs13277113A/G, BANK1 rs10516487G/A and rs3733197G/A were genotyped in 203 cases and 424 controls using a TaqMan® SNP genotyping assay. The BLK rs13277113A allele showed association with pSS under the allelic (OR 1.35, p = 0.02), and recessive (OR 1.83, p = 0.003) model, while, BANK1 rs3733197G/A showed association under the dominant model (OR 2.90, p = 0.043). Interactions between BANK1 and BLK genotypes also showed association (OR 2.36, p < 0.0001). In addition, BLK rs13277113A/G was associated with protection against arthritis and BANK1 rs10516487G/A with both arthritis and keratoconjunctivitis sicca, meanwhile, BANK1 rs3733197G/A was associated with smoking in patients with pSS. This is the first study to describe an association between BLK and susceptibility to pSS in a Latin-American population. Our data also shows a first evidence of association between interactions of BLK and BANK1 in pSS, and association of BLK and BANK1with arthritis, keratoconjunctivitis sicca and smoking in patients with pSS.

Cigarette smoking patterns preceding primary Sjögren's syndrome

BACKGROUND

Cigarette smoking is a well-established risk factor for several autoimmune diseases, but its role in primary Sjögren's syndrome (pSS) remains unclear. Here, we investigated the association between cigarette smoking and subsequent development of pSS.

METHODS

Information on smoking habits was collected from lifestyle habit questionnaires of patients with pSS (n=815) and a matched control group (n=4425) for a case-control study. Differences in smoking exposure were analysed by conditional logistic regression. Potential interactions between smoking and risk-associated human leucocyte antigens (HLA) were assessed by multivariate regression.

RESULTS

The fraction of patients with pSS having ever smoked prior to diagnosis was lower than in controls (OR 0.67, 95% CI 0.55 to 0.81). Current smoking at diagnosis was also less prevalent in cases (OR 0.37, 95% CI 0.26 to 0.53). However, period prevalence of smoking during early adulthood was not statistically different from controls (OR 0.89, 95% CI 0.66 to 1.22) but markedly decreased over time. This was partly due to patients being more prone to stop smoking, starting already 30 years prior to diagnosis (OR 2.01, 95% CI 1.22 to 3.30). Smoking patterns were also stratified by autoantibody status, yielding similar estimates. No interaction effects between HLA-DRB1 haplotypes and smoking were observed.

CONCLUSION

The observed smoking patterns indicate that individuals who develop pSS smoke equally much as the general population during early life but are then more prone to stop. The data can be interpreted as smoking conferring protective effects, or reflecting early symptoms of pSS that affect smoking habits, emphasising the slow, progressive development of the disease.

Environmental factors in the pathogenesis of primary Sjögren's syndrome

Primary Sjögren's syndrome (SS) is a systemic autoimmune disease in which exocrine organs, primarily the salivary and lacrimal glands, are targets of chronic inflammation, leading to severe dryness of eyes and mouth. Fatigue and arthralgia are also common, and extraglandular manifestations involving the respiratory, nervous and vascular systems occur in a subset of patients. Persistent activation of the type I interferon system, and autoreactive B and T cells with production of disease-associated autoantibodies are central to the pathogenesis. Genetic polymorphisms that associate with an increased risk of SS have been described, though the risk-increase contributed by the respective variant is generally low. It is thus becoming increasingly clear that genetics cannot alone account for the development of SS and that other, presumably exogenous, factors must play a critical role. Relatively few studies have investigated exposure to potential risk factors prior to SS disease onset. Rather, many factors have been studied in prevalent cases. In this review, we summarize current literature on exogenous factors in the pathogenesis of SS including infections, hormones, smoking, solvents and additional compounds. We delineate for which factors there is current evidence of increased disease risk, and for which our present knowledge is confined to suggesting their role in SS pathogenesis. Finally, we outline future perspectives in the continued search for environmental risk factors for SS, a research area of great importance considering the possibilities for preventive measures.

Infections increase the risk of developing Sjögren's syndrome

OBJECTIVE

Environmental factors have been suggested in the pathogenesis of rheumatic diseases. We here investigated whether infections increase the risk of developing primary Sjögren's syndrome (pSS).

METHODS

Patients with pSS in Sweden (n = 945) and matched controls from the general population (n = 9048) were included, and data extracted from the National Patient Register to identify infections occurring before pSS diagnosis during a mean observational time of 16.0 years. Data were analysed using conditional logistic regression models. Sensitivity analyses were performed by varying exposure definition and adjusting for previous health care consumption.

RESULTS

A history of infection associated with an increased risk of pSS (OR 1.9, 95% CI 1.6-2.3). Infections were more prominently associated with the development of SSA/SSB autoantibody-positive pSS (OR 2.7, 95% CI 2.0-3.5). When stratifying the analysis by organ system infected, respiratory infections increased the risk of developing pSS, both in patients with (OR 2.9, 95% CI 1.8-4.7) and without autoantibodies (OR 2.1, 95% CI 1.1-3.8), whilst skin and urogenital infections only significantly associated with the development of autoantibody-positive pSS (OR 3.2, 95% CI 1.8-5.5 and OR 2.7, 95% CI 1.7-4.2). Furthermore, a dose-response relationship was observed for infections and a risk to develop pSS with Ro/SSA and La/SSB antibodies. Gastrointestinal infections were not significantly associated with a risk of pSS.

CONCLUSIONS

Infections increase the risk of developing pSS, most prominently SSA/SSB autoantibody-positive disease, suggesting that microbial triggers of immunity may partake in the pathogenetic process of pSS.

Association between Periodontal Disease and Subsequent Sjögren's Syndrome: A Nationwide Population-Based Cohort Study

Xerostomia (dry mouth) is the cardinal symptom of Sjögren’s syndrome (SS), which is an autoimmune disease involving the exocrine glands and other organs. Xerostomia may predispose patients to periodontal disease (PD) and an association between SS and PD has been reported. This association may be bidirectional; therefore, we conducted this study to investigate the risk of SS in patients with PD using data from the National Health Insurance Research Database of Taiwan. A total of 135,190 patients were enrolled in our analysis. In all, 27,041 patients with PD were matched by gender, age, insured region, urbanization and income, with cases and controls in a 1:4 ratio. Both groups were followed and the risks of SS were calculated by Cox proportional hazards regression. Finally, 3292 (2.4%) patients had newly diagnosed SS. Patients with PD had a significantly higher risk of subsequent SS (903 (3.3%) vs. 2389 (2.2%), adjusted hazard 1.47, 95% confidence interval: 1.36–1.59). In conclusion, patients with PD had an approximately 50% increased risk of subsequent SS. Physicians should be aware of the symptoms and signs of SS in patients with PD.

Association of Smoking and Obesity on the Risk of Developing Primary Sjögren Syndrome: A Population-based Cohort Study

OBJECTIVE

To explore the role of smoking and obesity in primary Sjögren syndrome (pSS).

METHODS

Olmsted County (Minnesota, USA) residents (n = 106) diagnosed with pSS from 2000 to 2015 were compared to 3 controls without pSS and matched for age and sex who were randomly selected from Olmsted County residents.

RESULTS

Current smokers were less likely to be pSS cases (OR 0.34, 95% CI 0.14-0.85), while there was no association between former smoking and case/control status (OR 1.27, 95% CI 0.80-2.03) compared to never smokers. Smoking status was not associated with antinuclear antibody, anti-SSA, anti-SSB, or rheumatoid factor positivity (p > 0.05). OR for obesity was 0.79 (95% CI 0.48-1.30).

CONCLUSION

In this population-based study, current smoking was inversely associated with case/control status, while body mass index lacked any association.

Smoking, disease characteristics and serum cytokine levels in patients with primary Sjögren's syndrome

Smoking affects several disease processes. Epidemiological studies have previously found a negative association between primary Sjögren’s syndrome (pSS) and smoking. The aim of this study was to examine whether markers of disease activity and cytokine expression in pSS patients differ between ever and never smokers. Fifty-one consecutive pSS patients and 33 population controls were included in the study. Clinical and standard laboratory parameters were registered. Serum cytokines (IL-1β, IL-2, IL-3, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17, IL-18, IL-33, IFN-α, IFN-γ, TNF-α, EGF, BAFF, Fas-ligand, RANTES, TGF-β1) were assessed. A positive lip biopsy was less prevalent among ever smoking patients compared to never smokers (81 vs 100%; p = 0.03). However, except for TNF-α, which was higher in ever smokers, no differences in cytokine levels were found when comparing ever and never smoking pSS patients. Furthermore, no significant differences were found between ever and never smoking patients in the ESSDAI total score, IgG levels, or complement levels. However, IL-6, IL-12, IL-17 and IL-18 were significantly increased in pSS patients compared to controls. In this study, a negative association between ever smoking and positive lip biopsy was found, confirming previous reports. Expected differences in cytokine levels compared to controls were noted, but no major differences were found between ever and never smoking pSS patients. Taking into account the negative association between pSS diagnosis and smoking in epidemiological studies, possible explanations include a local effect of smoking on salivary glands rather than systemic effects by cigarette smoke.

Cytochrome c is important in apoptosis of labial glands in primary Sjogren's syndrome

The present study aimed to investigate the expression and effect of cytochrome c (Cytc) in patients with primary Sjogren's syndrome (pSS). In total, 35 newly diagnosed pSS patients and 35 healthy subjects were enrolled in the present study. The mRNA expression levels of Cytc were detected using reverse transcription‑polymerase chain reaction and RT‑quantitative PCR. The expression of the Cytc protein in labial salivary glands was detected by immunohistochemistry and was associated with the integral optical density (IOD) of clinical and laboratory variables. In addition, the content of Cytc in the cytoplasm and mitochondria were examined. The mRNA and protein expression levels of Cytc, and the content of Cytc in the cytoplasm of the pSS patients was increased significantly compared with the healthy controls (P<0.05). The content of Cytc in the mitochondria was significantly decreased compared with the healthy controls (P<0.05). The IOD of Cytc protein levels was positively correlated with immunoglobin G (r=0.8142, P<0.05) and erythrocyte sedimentation rate (r=0.7512, P<0.05). Cytc was upregulated in the pSS patients, indicating the potential role of Cytc in the pathogenesis and development of pSS. Further studies may facilitate the development of targeting this molecular pathway for the treatment of pSS.