Exposure to farming environments in early life and type 1 diabetes: a case-control study

Parental education and occupation in relation to childhood type 1 diabetes: nationwide cohort study

BackgroundSocioeconomic status in the risk of developing type 1 diabetes seems inconsistent. We investigated whether risk of childhood-onset type 1 diabetes differed by parental education or occupation in a nationwide cohort.

METHODS

This cohort study included all children born in Norway from 1974 to 2013. In individually linked data from nationwide population registries following children born in Norway up to 15 years of age, we identified 4647 with newly diagnosed type 1 diabetes during 15 381 923 person-years of follow-up.

RESULTS

Children of mothers with a master's degree had lower risk of type 1 diabetes than children of mothers with completed upper secondary education only (adjusted incidence rate ratio, aIRR=0.82 95% CI: 0.70 to 0.95). There was no difference between upper secondary and lower secondary maternal education (aIRR=0.98, 95% CI: 0.89 to 1.08). Paternal education was not significantly associated with type 1 diabetes, lower secondary compared with upper secondary aIRR 0.96 (0.88-1.05) and master compared with upper secondary aIRR 0.93 (0.83-1.05). While maternal elementary occupation was associated with a lower risk of type 1 diabetes, specific maternal or paternal occupations were not.

CONCLUSIONS

Our results suggested inverse U-shaped associations between maternal socioeconomic status and risk of type 1 diabetes. Non-linear associations may be part of the reason why previous literature has been inconsistent.

A prospective study of the association between living in a rural environment during childhood and risk of psoriasis

Psoriasis is one of the most common immune-mediated inflammatory diseases (IMIDs). Living in a rural environment during childhood is associated with a decreased risk of certain IMIDs, like asthma, in adulthood. However, its role in other IMIDs, such as psoriasis is still unclear. To evaluate the relationships between different factors related to the environment during childhood and the risk of psoriasis in adulthood we conducted a study in E3N, a French prospective cohort composed of 98 995 women. During the 1990-2018 follow-up of 72 154 study participants, we identified 1 967 incident cases of psoriasis from self-reports in self-administered structured questionnaires. During the 2004-2018 follow-up of 67 917 study participants, 188 moderate-to-severe cases of psoriasis were identified through self-reports and from data from a drug reimbursement database. We fitted Cox proportional hazards regression models with age as the time scale from which we estimated hazard ratios adjusted for putative confounders (aHRs). We found inverse associations with risk of psoriasis for rural birthplace [aHR: 0.89 (95%CI: 0.79-0.96)] and for having farming parents [aHR: 0.84 (95%CI: 0.72-0.97)]. For moderate-to-severe psoriasis we found a nominally similar inverse association with rural birthplace but not with having farming parents. Our results suggest that an exposure to a rural environment during childhood may be associated with a reduced risk of psoriasis. These findings may help to improve our understanding of the pathogenesis of psoriasis.

Type 1 diabetes-early life origins and changing epidemiology

Type 1 diabetes is a chronic, immune-mediated disease characterised by the destruction of insulin-producing cells. Standardised registry data show that type 1 diabetes incidence has increased 3-4% over the past three decades, supporting the role of environmental factors. Although several factors have been associated with type 1 diabetes, none of the associations are of a magnitude that could explain the rapid increase in incidence alone. Moreover, evidence of changing prevalence of these exposures over time is insufficient. Multiple factors could simultaneously explain the changing type 1 diabetes incidence, or the magnitude of observed associations could have been underestimated because of exposure measurement error, or the mismodelling of complex exposure-time-response relationships. The identification of environmental factors influencing the risk of type 1 diabetes and increased understanding of the cause at the individual level, regardless of the ability to explain the changing incidence at the population level, is important because of the implications for prevention.

Chromosome 17q21 Genes ORMDL3 and GSDMB in Asthma and Immune Diseases

Chromosome 17q21 contains a cluster of genes including ORMDL3 and GSDMB, which have been highly linked to asthma in genome-wide association studies. ORMDL3 is localized to the endoplasmic reticulum and regulates downstream pathways including sphingolipids, metalloproteases, remodeling genes, and chemokines. ORMDL3 inhibits serine palmitoyl-CoA transferase, the rate-limiting enzyme for sphingolipid biosynthesis. In addition, ORMDL3 activates the ATF6α branch of the unfolded protein response which regulates SERCA2b and IL-6, pathways of potential importance to asthma. The SNP-linking chromosome 17q21 to asthma is associated with increased ORMDL3 and GSDMB expression. Mice expressing either increased levels of human ORMDL3, or human GSDMB, have an asthma phenotype characterized by increased airway responsiveness and increased airway remodeling (increased smooth muscle and fibrosis) in the absence of airway inflammation. GSDMB regulates expression of 5-LO and TGF-β1 which are known pathways involved in the pathogenesis of asthma. GSDMB is one of four members of the GSDM family (GSDMA, GSDMB, GSDMC, and GSDMD). GSDMD (located on chromosome 8q24 and not linked to asthma) has emerged as a key mediator of pyroptosis. GSDMD is a key component of the NLPR3 inflammasome and is required for its activation. GSDMD undergoes proteolytic cleavage by caspase-1 to release its N-terminal fragment, which in turn mediates pyroptosis and IL-1β secretion. Chromosome 17q21 has not only been linked to asthma but also to type 1 diabetes, inflammatory bowel disease, and primary biliary cirrhosis suggesting that future insights into the biology of genes located in this region will increase our understanding of these diseases.

Dog Exposure During the First Year of Life and Type 1 Diabetes in Childhood

IMPORTANCE

The association between early exposure to animals and type 1 diabetes in childhood is not clear.

OBJECTIVE

To determine whether exposure to dogs during the first year of life is associated with the development of type 1 diabetes in childhood.

DESIGN, SETTING, AND PARTICIPANTS

A nationwide cohort study utilizing high-quality Swedish national demographic and health registers was conducted. A total of 840 593 children born in Sweden from January 1, 2001, to December 31, 2010, were evaluated. Type 1 diabetes was identified using diagnosis codes from hospitals and dispensed prescriptions of insulin. Cox proportional hazards regression models were used to assess the association between exposure to dogs and risk of type 1 diabetes in childhood. The possible association was further investigated by performing dose-response and breed group-specific analyses. The cohort was followed up until September 30, 2012. Data analysis was conducted from October 15, 2015, to February 8, 2017.

EXPOSURES

Having a parent who was registered as a dog owner during the child's first year of life.

MAIN OUTCOMES AND MEASURES

Childhood-onset type 1 diabetes.

RESULTS

Of the 840 593 children reviewed, 408 272 (48.6%) were girls; mean (SD) age at diagnosis of type 1 diabetes was 5.1 (2.6) years. Dog exposure was identified in 102 035 children (12.1%). Follow-up started at age 1 year, and the children were followed up for as long as 10.7 years (median, 5.5 years). During follow-up, 1999 children developed type 1 diabetes. No association was found between exposure to dogs (adjusted hazard ratio [HR], 1.00; 95% CI, 0.86-1.16) and type 1 diabetes in childhood. The size of the dog (adjusted HR per 10-cm increase in height, 0.96; 95% CI, 0.86-1.06) or number of dogs in the household (1 dog: adjusted HR, 1.07; 95% CI, 0.91-1.26; 2 dogs: 0.79; 95% CI, 0.54-1.15; ≥3 dogs: 0.50; 95% CI, 0.23-1.12; compared with nonexposed children) also was not associated with type 1 diabetes risk. An analysis of children whose parent had type 1 diabetes (210 events) yielded an adjusted HR of 0.71 (95% CI, 0.43-1.17) for dog exposure.

CONCLUSIONS AND RELEVANCE

In a nationwide study, no evidence supporting an association of register-derived measures of dog exposure with childhood type 1 diabetes was identified.

Environmental Risk Factors of Pediatric-Onset Primary Sclerosing Cholangitis and Autoimmune Hepatitis

OBJECTIVES

The aim of this population-based observational case-control questionnaire study was to investigate the possible role of environmental risk factors associated with pediatric-onset autoimmune liver diseases.

METHODS

Seventy-one patients with autoimmune liver diseases (<16 years) received a questionnaire with 22 items, evaluating contact with environmental factors (eg, family manners, type of housing, pets) before the diagnosis. Two age- and sex-matched control groups were used: inflammatory bowel disease (IBD; n = 91) and healthy subjects (n = 716; matched also for place of residence at birth). Univariate analysis (odds ratio [OR] and 95% confidence interval) for all variables was calculated. Fisher exact test was performed to depict associations between variables and the multivariate logistic regression to test their interactions.

RESULTS

In the final analyses, the responses of 51 autoimmune liver diseases cases (n = 51/71, 72%), 59 IBD controls (n = 59/91, 65%), and 292 healthy controls (n = 292/716, 41%) were investigated. In univariate analysis only having a cat, a dog, and a cat or a dog were risk factors of autoimmune liver diseases (OR varying between 2.6-3.4); no other significant associations (eg, place of residence, number of siblings, family manners) were found. Multivariate logistic regression analyses showed that especially living with a cat in block of flats was a risk factor (OR 3.6, 1.2-10.8).

CONCLUSIONS

Living in a close contact with a pet (especially a cat) was a risk factor of autoimmune liver diseases. This finding may suggest an involvement of an unidentified agent (ie, toxin/microbe) among the triggers of these diseases.

The microbial environment and its influence on asthma prevention in early life

There is accumulating evidence to suggest that the environmental microbiome plays a significant role in asthma development. The very low prevalence of asthma in populations highly exposed to microbial environments (farm children and Amish populations) highlights its preventive potential. This microbial diversity might be necessary to instruct a well-adapted immune response and regulated inflammatory responses to other inhaled and ingested environmental elements, such as allergens, particles, and viruses. Like the internal gut microbiome, which is increasingly recognized as an important instructor of immune maturation, the external environmental microbiome might shape immune responses on the skin, airway mucosal surfaces, and potentially also the gut early in life. The diversity of the external microbial world will ensure that of the many maladapted pathways leading to asthma development, most, if not all, will be counterbalanced. Likewise, important contributors to asthma, such as allergen sensitization and allergic manifestations early in life, are being suppressed. Thus the facets of innate immunity targeted by microbes and their compounds and metabolites might be the master switch to asthma and allergy protection, which has been found in environments rich in microbial exposures.

Farm living: effects on childhood asthma and allergy

Numerous epidemiological studies have shown that children who grow up on traditional farms are protected from asthma, hay fever and allergic sensitization. Early-life contact with livestock and their fodder, and consumption of unprocessed cow's milk have been identified as the most effective protective exposures. Studies of the immunobiology of farm living point to activation and modulation of innate and adaptive immune responses by intense microbial exposures and possibly xenogeneic signals delivered before or soon after birth.

Total serum IgE levels in systemic lupus erythematosus and associations with childhood onset allergies

Elevated serum IgE has been described in systemic lupus erythematosus (SLE), but associations with disease risk and characteristics remain unresolved. We assessed total serum IgE levels and atopy (IgE > 100 IU/ml) in recently diagnosed SLE patients (n = 228) compared with population controls (n = 293) and in relation to disease activity, autoantibodies, clinical features, total immunoglobulins, C-reactive protein, and allergy history. Multivariate models estimated determinants of IgE and atopy in patients and controls, and associations of SLE with allergy and atopy. Total IgE levels were higher in patients than controls (median = 42 vs. 29 IU/ml); 32% of patients and 25% of controls were atopic (p = 0.06). IgE levels were significantly higher in non-Whites and patients reporting childhood onset (<18 years) asthma and hives, and in controls reporting childhood asthma, hay fever, eczema, and adult onset hives. After accounting for racial differences, atopy was not associated with SLE, nephritis, or other clinical and laboratory parameters. In sum, our findings provide limited evidence of a direct association between total serum IgE and SLE overall or with other disease characteristics after adjusting for demographic characteristics and allergy history. Future studies may want to explore potentially shared risk factors for development of allergy, atopy, and SLE.

Exposure to animals and risk of oligoarticular juvenile idiopathic arthritis: a multicenter case-control study

Background

An inverse association between early contact with microbial compounds and respiratory allergies is well established. The protective effect of infant contact with animals was also shown for inflammatory bowel disease (IBD) and systemic lupus erythematosus (SLE). We aimed to test the association between animal contact in infancy and oligoarticular juvenile idiopathic arthritis (OA JIA).

Methods

Parents of children with OA JIA registered at the Hospital for Pediatric Rheumatology in Garmisch-Partenkirchen were asked to complete a questionnaire. Children who underwent strabismus surgery at six referral centers for ophthalmology served as controls. Children age 6 to 18 years born in Germany without malformations were included (238 cases; response 89% and 832 controls; response 86%). Data were analyzed using logistic regression models after adjusting for potential confounders.

Results

Neither place of living (urban vs. rural area), living on a farm, nor regular farm animal (adjusted odds ratio 0.79; 95% confidence interval 0.42-1.47) or pet contact (0.79; 0.55-1.14) during infancy were clearly related to case status. Allergic rhinitis was inversely related to OA JIA (0.57; 0.34-0.95).

Neither place of living (urban vs. rural area), living on a farm, nor regular farm animal (adjusted odds ratio 0.79; 95% confidence interval 0.42-1.47) or pet contact (0.79; 0.55-1.14) during infancy were related to case status. Allergic rhinitis was inversely related to OA JIA (0.57; 0.34-0.95).

Conclusions

Contact with farm environments in infancy might not be associated with OA JIA. This finding is consistent with previous findings for diabetes mellitus type 1 but contradicts results for IBD and SLE.

Birthweight and the risk of childhood-onset type 1 diabetes: a meta-analysis of observational studies using individual patient data

AIMS/HYPOTHESIS

We investigated whether children who are heavier at birth have an increased risk of type 1 diabetes.

METHODS

Relevant studies published before February 2009 were identified from literature searches using MEDLINE, Web of Science and EMBASE. Authors of all studies containing relevant data were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of birthweight were calculated for each study, before and after adjustment for potential confounders.Meta-analysis techniques were then used to derive combined ORs and investigate heterogeneity between studies.

RESULTS

Data were available for 29 predominantly European studies (five cohort, 24 case-control studies), including 12,807 cases of type 1 diabetes. Overall, studies consistently demonstrated that children with birthweight from 3.5 to 4 kg had an increased risk of diabetes of 6% (OR 1.06 [95% CI 1.01-1.11]; p=0.02) and children with birthweight over 4 kg had an increased risk of 10% (OR 1.10 [95% CI 1.04-1.19]; p=0.003), compared with children weighing 3.0 to 3.5 kg at birth. This corresponded to a linear increase in diabetes risk of 3% per 500 g increase in birthweight (OR 1.03 [95% CI 1.00-1.06]; p=0.03). Adjustments for potential confounders such as gestational age, maternal age, birth order, Caesarean section, breastfeeding and maternal diabetes had little effect on these findings.

CONCLUSIONS/INTERPRETATION

Children who are heavier at birth have a significant and consistent, but relatively small increase in risk of type 1 diabetes.

Childhood agricultural and adult occupational exposures to organic dusts in a population-based case-control study of systemic lupus erythematosus

Organic dust exposure can influence the development and symptoms of immune-related diseases such as atopy and asthma, but has rarely been examined in relation to systemic autoimmunity. The present analyses explore the association of lifetime farm and occupational organic dust exposures with systemic lupus erythematosus (SLE) in recently diagnosed patients (n = 265) compared with controls (n = 355) frequency matched by age, sex and state. Questionnaire data included childhood farm residence, childhood and adult experience with specific crops, and adult work in textiles, hog or poultry processing and paper or furniture manufacture. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression models including age, sex, state, race, education and silica exposure. Overall childhood or adult farm contact and childhood farm residence were not associated with SLE. Farm contact with livestock was inversely associated with SLE (OR = 0.55, 95% CI 0.35, 0.88). This effect was most pronounced among those with childhood farm residence and both childhood and adult livestock exposure (OR = 0.19; 95% CI 0.06, 0.63), but was difficult to separate from adult exposure to grains or corn. Other adult occupational exposures were not associated with SLE risk overall, regardless of childhood farm residence or livestock exposure, although an inverse association was seen among non-smokers (OR = 0.59; 95% CI 0.33, 1.1), particularly for textile work (OR = 0.34; 95% CI 0.19, 0.64). These exploratory findings support the development of studies to specifically investigate the effects of organic dust exposure on SLE risk, with particular attention to exposure assessment and characterization of demographics, smoking and other occupational exposures.

Contact with farm animals in early life and juvenile inflammatory bowel disease: a case-control study

OBJECTIVE

The aim of this study was to test the association between farm animal contact in infancy and the development of juvenile Crohn disease and ulcerative colitis.

METHODS

A case-control study was conducted in 13 children's hospitals by using a mailed questionnaire. Case subjects with Crohn disease or ulcerative colitis who were registered in these hospitals were eligible (response rate: 90%). Children who underwent strabismus surgery at 11 of the 13 centers served as control subjects (response rate: 85%). All children 6 to 18 years of age who were born in Germany without malformations were included (444 case subjects with Crohn disease, 304 case subjects with ulcerative colitis, and 1481 control subjects).

RESULTS

Regular contact with farm animals during the first year of life was associated inversely with Crohn disease and ulcerative colitis. In addition, regular contact with cats in infancy was linked inversely with case status. Allergic rhinitis was correlated significantly with Crohn disease but not with ulcerative colitis.

CONCLUSION

Contact with farm environments in infancy might decrease the risk of juvenile Crohn disease and ulcerative colitis.

Systemic autoimmune disease mortality and occupational exposures

OBJECTIVE

To generate hypotheses regarding occupational exposures that may cause systemic autoimmune diseases.

METHODS

Based on examination of US death certificates, we identified deaths in 26 states for which a cause was listed as rheumatoid arthritis (RA) (n = 36,178), systemic lupus erythematosus (SLE) (n = 7,241), systemic sclerosis (n = 5,642), or other systemic autoimmune disease (n = 4,270). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to estimate associations between occupation and death from any systemic autoimmune disease, and from RA, SLE, and systemic sclerosis, specifically. Additionally, we estimated risks associated with occupational exposures, which were assigned using job-exposure matrices.

RESULTS

A broad array of occupations was associated with death from systemic autoimmune diseases, including several of a priori interest. Farming occupation was associated with death from any systemic autoimmune disease (OR 1.3 [95% CI 1.2-1.4]), and increased risk was also seen with occupational exposure to animals and pesticides. Several industrial occupations were associated with death from any systemic autoimmune disease, including mining machine operators (OR 1.3 [95% CI 1.1-1.5]), miscellaneous textile machine operators (OR 1.2 [95% CI 1.0-1.4]), and hand painting, coating, and decorating occupations (OR 1.8 [95% CI 1.0-2.9]). These occupations were also significantly associated with death from the specific autoimmune diseases examined. Certain occupations entailing exposure to the public, such as teachers, were associated with systemic autoimmune disease-related death, whereas others, such as waiters and waitresses, were not.

CONCLUSION

Our results suggest that death from systemic autoimmune diseases may be associated with occupational exposures encountered in farming and industry. The hypotheses generated in this study provide leads for future research on determinants of these diseases.