Atopy, home environment and the risk of childhood-onset type 1 diabetes: a population-based case-control study

Interplay between diabetes mellitus and atopic dermatitis

Inflammatory dermatoses such as atopic dermatitis (AD) have long been linked to the pathogenesis of diabetes mellitus. Indeed, numerous studies show an increased risk of diabetes mellitus in individuals with AD although lower prevalence of diabetes mellitus is also observed in few studies. Though the underlying mechanisms accounting for the reciprocal influence between these two conditions are still unclear, the complex interplay between diabetes mellitus and AD is attributable, in part, to genetic and environmental factors, cytokines, epidermal dysfunction, as well as drugs used for the treatment of AD. Proper management of one condition can mitigate the other condition. In this review, we summarize the evidence of the interaction between diabetes mellitus and AD, and discuss the possible underlying mechanisms by which these two conditions influence each other.

Prevalence of asthma in people with type 1 diabetes mellitus: a scoping review

BACKGROUND

According to the Th1/Th2 paradigm, the expansion of Th1-type clones in individuals with type 1 diabetes results in reduced Th2-type clones, preventing the development of atopic diseases and vice versa. However, there is no consensus regarding the direct or inverse relationship between autoimmune and atopic diseases.

OBJECTIVE

The aim of this scoping review was to examine the knowledge gap about the possibility of coexistence of asthma and type 1 diabetes and determine the prevalence of this association.

METHODS

A scoping review was conducted, following the proposal of the Joanna Briggs Institute. The Population, Concept, and Context strategy was used to formulate the guiding question. The proposed question was: "What is the prevalence of asthma in people with T1DM?" After excluding duplicate articles, analyzing titles and abstracts, and excluding articles that did not answer the guiding question, 17 articles remained and were included in this review.

RESULTS

Most of the articles selected conformed to the Th1/Th2 hypothesis, as the prevalence of asthma was lower in individuals with T1DM. However, similar or higher prevalence of asthma was found between cases and controls in few articles.

CONCLUSION

The prevalence of asthma in people with T1DM ranged from 1.7% to 23.1%. Maybe the mechanisms that characterizes the Th1/Th2 paradigm aren't as simple as just the interaction of certain cytokines, since Th1-mediated autoimmune diseases and Th2- mediated atopy can coexist.

On developmental programming of the immune system

Early-life environmental exposures play a significant role in shaping long-lasting immune phenotypes and disease susceptibility. Nevertheless, comprehensive understanding of the developmental programming of immunity is limited. We propose that the vertebrate immune system contains durable programmable components established through early environmental interactions and maintained in a stable and homeostatic manner. Some immune components, such as immunological memory, are intrinsically programmable. Others are influenced by conditions during critical developmental windows in early life, including microbiota, hormones, metabolites, and environmental stress, which impact programming. Developmental immune programming can promote adaptation to an anticipated future environment. However, mismatches between predicted and actual environments can result in disease. This is relevant because understanding programming mechanisms can offer insights into the origin of inflammatory diseases, ideally enabling effective prevention and treatment strategies.

Childhood asthma and type 1 diabetes mellitus: A meta-analysis and bidirectional Mendelian randomization study

BACKGROUND

Worldwide incidence and prevalence of both asthma and type 1 diabetes mellitus (T1DM) in children have been increasing in past decades. Association between the two diseases has been found in some but not in other studies.

OBJECTIVE

We conducted a meta-analysis to verify such an association, and bidirectional Mendelian randomization analysis to examine the potential cause-effect relationships.

METHODS

Three databases (PubMed, Embase, and Web of Science) were searched from their inception to February 1, 2021. Pooled hazard ratios (HR) or odds ratios (OR), and 95% confidence intervals, were calculated. Associations between single-nucleotide polymorphisms with childhood asthma and T1DM were selected based on genome-wide association studies. The outcome datasets were obtained from FinnGen study. We used the inverse-variance-weighted (IVW), weighted median and MR-Egger methods to estimate causal effects. To assess robustness and horizontal pleiotropy, MR-Egger regression and MR pleiotropy residual sum and outlier test were conducted.

RESULTS

In meta-analysis, childhood asthma was associated with an increased risk of T1DM (HR = 1.30, 95% CI 1.05-1.61, P = .014), whereas T1DM was not associated with the risk of asthma (HR = 0.98, 95% CI 0.64-1.51, P = .941; OR = 0.84, 95% CI 0.65-1.08, P = .168). MR analysis indicated increased genetic risk of T1DM in children with asthma (OR = 1.308; 95% CI 1.030-1.661; P = .028). Analysis using the IVW method indicated no association between T1DM and genetic risk of asthma (OR = 1.027, 95%CI 0.970-1.089, P = .358).

CONCLUSION

Both meta-analysis and MR study suggested that childhood asthma was a risk factor for T1DM. No epidemiological or genetic evidence was found for an association of T1DM with asthma incidence. Further studies could be carried out to leverage this newfound insight into better clinical and experimental research in asthma and T1DM.

Type 1 diabetes and asthma: a systematic review and meta-analysis of observational studies

PURPOSE

Type 1 diabetes (T1D) and asthma are both the top concurrent non-communicable diseases in the world, and the existence of a relationship between the two is an area of debate.

METHODS

All eligible observational studies in PubMed and EMBASE databases from inception to August 2021 were searched for data extraction and analysis. The pooled odds ratio (OR) with corresponding 95% confidence intervals (95% CI) was evaluated using fixed-effects or random-effects models in RevMan 5.3, and I² and Cochran Q tests were used to assess the heterogeneity.

RESULTS

22 studies with 25,578 T1D and 3,330,901 non-T1D were included in this meta-analysis. After data analysis, there seems to be no apparent connectivity between asthma and T1D as the crude OR (cOR) was 1.07 (95%CI, 0.93-1.23). Nevertheless, after limiting the meta-analysis to 6 studies with adjusted OR (aOR) available, the results suggested a positive association between T1D and asthma (aOR, 1.15; 95%CI, 1.06-1.25). Corresponding with this, a meta-analysis of cohort studies also found a positive association between T1D and asthma with the pooled cOR of 1.27 (95% CI, 1.09-1.49) and aOR of 1.15 (95%CI, 1.05-1.26). Further analysis of 7 studies in which the diagnosis of asthma precedes T1D onset revealed that asthma patients are at increased risk of subsequent T1D with the pooled cOR of 1.23 (95%CI, 1.04-1.44) and aOR of 1.58 (95% CI, 1.11-2.24).

CONCLUSION

Our meta-analysis suggests a possible association between T1D and asthma, and patients who were previously diagnosed with asthma carried higher odds of developing T1D.

Coaggregation of Asthma and Type 1 Diabetes in Children: A Narrative Review

Asthma and type 1 diabetes mellitus (T1DM) are two of the most frequent chronic diseases in children, representing a model of the atopic and autoimmune diseases respectively. These two groups of disorders are mediated by different immunological pathways, T helper (Th)1 for diabetes and Th2 for asthma. For many years, these two groups were thought to be mutually exclusive according to the Th1/Th2 paradigm. In children, the incidence of both diseases is steadily increasing worldwide. In this narrative review, we report the evidence of the potential link between asthma and T1DM in childhood. We discuss which molecular mechanisms could be involved in the link between asthma and T1DM, such as genetic predisposition, cytokine patterns, and environmental influences. Cytokine profile of children with asthma and T1DM shows an activation of both Th1 and Th2 pathways, suggesting a complex genetic-epigenetic interaction. In conclusion, in children, the potential link between asthma and T1DM needs further investigation to improve the diagnostic and therapeutic approach to these patients. The aim of this review is to invite the pediatricians to consider the potential copresence of these two disorders in clinical practice.

The Cross-Talk Between Atopic Dermatitis and Diabetes Mellitus: A Meta-Analysis

INTRODUCTION

Atopic dermatitis (AD) is associated with various systemic diseases. However, its association with diabetes mellitus (DM) was discussed controversially. Few researchers reviewed the association of these two common morbid disorders. This meta-analysis aimed to assess the relationship between AD and DM.

METHODS

We systematically searched PubMed including Epub and ahead of print (198 articles identified) and Cochrane (13 articles) databases. The searching engine was set to include case-control, prospective and retrospective cohorts, and cross-sectional studies from the first published up to February 12, 2021. Two hundred and eleven were identified, eighteen full texts were screened; of them, six were included in the final meta-analysis. The keywords used were AD, diabetes mellitus, type 1 diabetes, and type 2 diabetes. A datasheet was used to record the author's name, year of publication, country and type of the studies, number of events, and total number in the two arms (patients and controls).

RESULTS

Out of the 211 references identified, six studies were pooled to test the association between diabetes mellitus and AD. The studies showed that AD is lower among patients with DM, odds ratio, 0.69, 95% CI, and 0.67-0.72. No heterogeneity was observed (Chi-Square, 4.12, degree of freedom (df.)= 5, and I² = 0%, P-value), 0.53 and P-value for overall effect, <0.001. The included studies were published in Europe (five) and Canada (one study) and included 162,882 patients and 12,164 events, four of the studied articles were case-control studies, one retrospective, and one cross-sectional.

CONCLUSION

AD was lower among patients with DM compared to their counterparts without the disease. Further studies focusing on the genetic and environmental factors linking AD and diabetes are needed.

Development of atopic sensitization in Finnish and Estonian children: A latent class analysis in a multicenter cohort

BACKGROUND

The prevalence of atopy is associated with a Western lifestyle, as shown by studies comparing neighboring regions with different socioeconomic backgrounds. Atopy might reflect various conditions differing in their susceptibility to environmental factors.

OBJECTIVE

We sought to define phenotypes of atopic sensitization in early childhood and examine their association with allergic diseases and hereditary background in Finland and Estonia.

METHODS

The analysis included 1603 Finnish and 1657 Estonian children from the DIABIMMUNE multicenter young children cohort. Specific IgE levels were measured at age 3, 4, and 5 years, respectively, and categorized into 3 CAP classes. Latent class analysis was performed with the statistical software package poLCA in R software.

RESULTS

Both populations differed in terms of socioeconomic status and environmental determinants, such as pet ownership, farm-related exposure, time spent playing outdoors, and prevalence of allergic diseases (all P < .001). Nevertheless, we found similar latent classes in both populations: an unsensitized class, a food class, 2 inhalant classes differentiating between seasonal and perennial aeroallergens, and a severe atopy class. The latter was characterized by high total and specific IgE levels and strongly associated with wheeze (odds ratio [OR], 5.64 [95% CI, 3.07-10.52] and 4.56 [95% CI, 2.35-8.52]), allergic rhinitis (OR, 22.4 [95% CI, 11.67-44.54] and 13.97 [95% CI, 7.33-26.4]), and atopic eczema (OR, 9.39 [95% CI, 4.9-19.3] and 9.5 [95% CI, 5.2-17.5] for Finland and Estonia, respectively). Environmental differences were reflected in the larger seasonal inhalant atopy class in Finland, although composition of classes was comparable between countries.

CONCLUSION

Despite profound differences in environmental exposures, there might exist genuine patterns of atopic sensitization. The distribution of these patterns might determine the contribution of atopic sensitization to disease onset.

Socio-economic status and lifestyle factors are associated with achalasia risk: A population-based case-control study

AIM

To evaluate the association between various lifestyle factors and achalasia risk.

METHODS

A population-based case-control study was conducted in Northern Ireland, including n = 151 achalasia cases and n = 117 age- and sex-matched controls. Lifestyle factors were assessed via a face-to-face structured interview. The association between achalasia and lifestyle factors was assessed by unconditional logistic regression, to produce odds ratios (OR) and 95% confidence interval (CI).

RESULTS

Individuals who had low-class occupations were at the highest risk of achalasia (OR = 1.88, 95%CI: 1.02-3.45), inferring that high-class occupation holders have a reduced risk of achalasia. A history of foreign travel, a lifestyle factor linked to upper socio-economic class, was also associated with a reduced risk of achalasia (OR = 0.59, 95%CI: 0.35-0.99). Smoking and alcohol consumption carried significantly reduced risks of achalasia, even after adjustment for socio-economic status. The presence of pets in the house was associated with a two-fold increased risk of achalasia (OR = 2.00, 95%CI: 1.17-3.42). No childhood household factors were associated with achalasia risk.

CONCLUSION

Achalasia is a disease of inequality, and individuals from low socio-economic backgrounds are at highest risk. This does not appear to be due to corresponding alcohol and smoking behaviours. An observed positive association between pet ownership and achalasia risk suggests an interaction between endotoxin and viral infection exposure in achalasia aetiology.

Microbial 'old friends', immunoregulation and socioeconomic status

The immune system evolved to require input from at least three sources that we collectively term the ‘old friends’: (i) the commensal microbiotas transmitted by mothers and other family members; (ii) organisms from the natural environment that modulate and diversify the commensal microbiotas; and (iii) the ‘old’ infections that could persist in small isolated hunter-gatherer groups as relatively harmless subclinical infections or carrier states. These categories of organism had to be tolerated and co-evolved roles in the development and regulation of the immune system. By contrast, the ‘crowd infections’ (such as childhood virus infections) evolved later, when urbanization led to large communities. They did not evolve immunoregulatory roles because they either killed the host or induced solid immunity, and could not persist in hunter-gatherer groups. Because the western lifestyle and medical practice deplete the ‘old’ infections (for example helminths), immunoregulatory disorders have increased, and the immune system has become more dependent upon microbiotas and the natural environment. However, urbanization maintains exposure to the crowd infections that lack immunoregulatory roles, while accelerating loss of exposure to the natural environment. This effect is most pronounced in individuals of low socioeconomic status (SES) who lack rural second homes and rural holidays. Interestingly, large epidemiological studies indicate that the health benefits of living close to green spaces are most pronounced for individuals of low SES. Here we discuss the immunoregulatory role of the natural environment, and how this may interact with, and modulate, the proinflammatory effects of psychosocial stressors in low SES individuals.

Nonallergic comorbidities of atopic eczema: an overview of systematic reviews

The aims of this overview are to synthesize the current evidence of published systematic reviews (SRs) on nonallergic comorbidities of atopic eczema (AE). EMBASE and MEDLINE were searched for SRs published from inception to November 2012. SRs were selected independently based on predefined inclusion criteria. Methodological quality of SRs included was assessed by two independent reviewers using the Revised Assessment of Multiple Systematic Reviews (R-AMSTAR) checklist. Nine SRs met all inclusion criteria. Six reviews addressing the association between AE and cancer suggest a decreased risk of glioma, meningioma, and acute lymphoblastic leukemia in patients with current or previous AE. One SR reported a consistent positive association of AE with attention-deficit hyperactivity disorder (ADHD). Diabetes mellitus type 1 and multiple sclerosis (MS) were not significantly related to AE in reviews based on cross-sectional and case-control studies. Patients with AE appear to be at decreased risk of brain tumors. The relationship of AE with Th1- and Th17-mediated (auto-)inflammatory conditions such as diabetes mellitus type 1 and MS should be clarified in prospective observational studies. Children with AE are at increased risk of ADHD. SRs on the risk of depression and Th17-mediated disorders such as inflammatory bowel disease of patients with AE are missing.

Hygiene hypothesis and autoimmune diseases

Throughout the twentieth century, there were striking increases in the incidences of many chronic inflammatory disorders in the rich developed countries. These included autoimmune disorders such as Type 1 diabetes and multiple sclerosis. Although genetics and specific triggering mechanisms such as molecular mimicry and viruses are likely to be involved, the increases have been so rapid that any explanation that omits environmental change is incomplete. This chapter suggests that a series of environmental factors, most of them microbial, have led to a decrease in the efficiency of our immunoregulatory mechanisms because we are in a state of evolved dependence on organisms with which we co-evolved (and that had to be tolerated) as inducers of immunoregulatory circuits. These organisms ("Old Friends") are depleted from the modern urban environment. Rather than considering fetal programming by maternal microbial exposures, neonatal programming, the hygiene hypothesis, gut microbiota, and diet as separate and competing hypotheses, I attempt here to integrate these ideas under a single umbrella concept that can provide the missing immunoregulatory environmental factor that is needed to explain the recent increases in autoimmune disease.

Neighborhood level risk factors for type 1 diabetes in youth: the SEARCH case-control study

BACKGROUND

European ecologic studies suggest higher socioeconomic status is associated with higher incidence of type 1 diabetes. Using data from a case-control study of diabetes among racially/ethnically diverse youth in the United States (U.S.), we aimed to evaluate the independent impact of neighborhood characteristics on type 1 diabetes risk. Data were available for 507 youth with type 1 diabetes and 208 healthy controls aged 10-22 years recruited in South Carolina and Colorado in 2003-2006. Home addresses were used to identify Census tracts of residence. Neighborhood-level variables were obtained from 2000 U.S. Census. Multivariate generalized linear mixed models were applied.

RESULTS

Controlling for individual risk factors (age, gender, race/ethnicity, infant feeding, birth weight, maternal age, number of household residents, parental education, income, state), higher neighborhood household income (p = 0.005), proportion of population in managerial jobs (p = 0.02), with at least high school education (p = 0.005), working outside the county (p = 0.04) and vehicle ownership (p = 0.03) were each independently associated with increased odds of type 1 diabetes. Conversely, higher percent minority population (p = 0.0003), income from social security (p = 0.002), proportion of crowded households (0.0497) and poverty (p = 0.008) were associated with a decreased odds.

CONCLUSIONS

Our study suggests that neighborhood characteristics related to greater affluence, occupation, and education are associated with higher type 1 diabetes risk. Further research is needed to understand mechanisms underlying the influence of neighborhood context.

Risk Factors for Type 1 Diabetes Mellitus among Children and Adolescents in Basrah

OBJECTIVES

Environmental factors play an important role in the pathogenesis of type 1 diabetes mellitus, many of these factors have been uncovered despite much research. A case-control study was carried out to determine the potential maternal, neonatal and early childhood risk factors for type 1 diabetes mellitus in children and adolescents in Basrah.

METHODS

A total of 96 diabetic patients who have been admitted to the pediatric wards at 3 main hospitals in Basrah, and those who have visited primary health care centers over the period from the 4(th) of November 2006 to the end of May 2007 were recruited. In addition, 299 non-diabetic children were included, their age ranged from 18 months to 17 years.

RESULTS

Family history of type 1 diabetes mellitus and thyroid diseases in first and second degree relatives was found to be an independent risk factor for type 1 diabetes mellitus, (p<0.001). Regarding maternal habits and illnesses during pregnancy, the study has revealed that tea drinking during pregnancy is a risk factor for type 1 diabetes mellitus in their offspring, (p<0.05). In addition, maternal pre-eclampsia and infections were found to be significant risk factor for type 1 diabetes mellitus, (p<0.001). Neonatal infections, eczema and rhinitis during infancy were also significantly associated with development of type 1 diabetes mellitus. Moreover, the results revealed that duration of <6 months breast feeding is an important trigger of type 1 diabetes mellitus.

CONCLUSION

Exposure to environmental risk factors during pregnancy (tea drinking, pre-eclampsia, and infectious diseases), neonatal period (respiratory distress, jaundice and infections) and early infancy are thought to play an important role in triggering the immune process leading to B-cell destruction and the development of type 1 diabetes mellitus.

The 'hygiene hypothesis' for autoimmune and allergic diseases: an update

According to the 'hygiene hypothesis', the decreasing incidence of infections in western countries and more recently in developing countries is at the origin of the increasing incidence of both autoimmune and allergic diseases. The hygiene hypothesis is based upon epidemiological data, particularly migration studies, showing that subjects migrating from a low-incidence to a high-incidence country acquire the immune disorders with a high incidence at the first generation. However, these data and others showing a correlation between high disease incidence and high socio-economic level do not prove a causal link between infections and immune disorders. Proof of principle of the hygiene hypothesis is brought by animal models and to a lesser degree by intervention trials in humans. Underlying mechanisms are multiple and complex. They include decreased consumption of homeostatic factors and immunoregulation, involving various regulatory T cell subsets and Toll-like receptor stimulation. These mechanisms could originate, to some extent, from changes in microbiota caused by changes in lifestyle, particularly in inflammatory bowel diseases. Taken together, these data open new therapeutic perspectives in the prevention of autoimmune and allergic diseases.