Is the hygiene hypothesis relevant for the risk of multiple sclerosis?

Chlamydia pneumonia infection and risk of multiple sclerosis: A meta-analysis

BACKGROUND

The role of infectious agents, including Chlamydia pneumoniae (Cpn), in the development of multiple sclerosis (MS), is still a matter of major contention.

OBJECTIVE

This meta-analysis study aimed to assess the actual involvement of Cpn in MS development.

METHODS

We undertook a search of international scientific databases to identify eligible studies. We used a random-effects meta-analysis model (REM) to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Heterogeneity was calculated using the I2 statistic. Sensitivity and subgroup analyses were applied to assess the effects of study characteristics and socio-demographic variables on the pooled OR.

RESULTS

We identified 37 studies comprising 51 datasets that satisfied the inclusion criteria. Considering diagnostic methods for Cpn, 26 and 25 datasets used PCR- and serological-based methods, respectively. In PCR-based datasets, REM showed a significant positive association between Cpn infection and the development of MS (OR, 5.29; 95% CI, 3.12-8.97), while a non-significant positive association was achieved in serological-based datasets (OR, 1.34; 95% CI, 0.88-2.03). In subgroup analyses on PCR-based datasets, results were significant for both CSF (OR, 5.70) and serum (OR, 4.84) samples; both healthy (OR, 16.11) and hospital-based (OR, 2.88) controls; and both moderate (OR, 5.14) and high (OR, 5.48) quality studies. In serological-based datasets, only those that used CSF samples yielded significant results (OR, 3.41).

CONCLUSIONS

Our findings verify the significant positive relationship between Cpn infection and MS. We advocate prospective cohort studies with lifelong follow-ups and also experimental studies to better understand the role of Cpn in MS development.

Association of Multiple Sclerosis Prevalence With Sociodemographic, Health Systems, and Lifestyle Factors on a National and Regional Level

BACKGROUND AND OBJECTIVES

Multiple sclerosis (MS) prevalence varies widely by country and world region, variation that is often attributed to latitude and its association with vitamin D exposure. Given that increasing latitude is also associated with higher national wealth, this study investigated associations between MS prevalence and other factors driving regional differences, with a focus on sociodemographic, health systems, and lifestyle factors on a national and regional level.

METHODS

Using data from multilateral organizations and scientific literature, an ecological study was conducted to evaluate associations between age- and sex-adjusted MS prevalence and prespecified sociodemographic (gross domestic product [GDP] per capita and gross national income [GNI] per capita), health systems (current health expenditure per capita and by percentage of GDP, universal health coverage [UHC] index, and medical doctors per capita), neurology-specific (MRI unit density and neurologists per capita), and lifestyle (obesity and tobacco use) factors. National, regional, and income-stratified data were aggregated and employed in relevant univariable and multivariable regression models. Stepwise variable selection techniques identified independent predictors of MS prevalence.

RESULTS

Univariable regression analyses showed significant associations at the national level for all investigated factors, except obesity prevalence and tobacco use. Latitude was significantly associated with MS prevalence in all world regions (β = 0.16-2.16), whereas the UHC index was significantly associated in 5 of 6 world regions (β = 0.18-3.17). MS prevalence was significantly associated with all factors except lifestyle factors and MRI unit density in high-income countries, but no associations were observed in low-income countries. Latitude was associated with MS prevalence for all income strata except low-income countries (β = 0.55-1.62). In multivariable analyses, current health expenditure per capita (β = 0.083, 95% CI 0.048-0.12, p < 0.01) and latitude (β = 1.05, 95% CI 0.63-1.47, p < 0.01) remained significantly associated with MS prevalence.

DISCUSSION

Health expenditure per capita is strongly associated with national MS prevalence, suggesting that theories that attribute variations in MS prevalence primarily to latitude effects on vitamin D are incomplete. Health care access significantly contributes to the global variations in MS prevalence, especially since national wealth rises with latitude and likely results in significant underestimation of MS prevalence in countries with lower health expenditure.

Risk Factors from Pregnancy to Adulthood in Multiple Sclerosis Outcome

Multiple sclerosis (MS) is an autoimmune disease characterized by a robust inflammatory response against myelin sheath antigens, which causes astrocyte and microglial activation and demyelination of the central nervous system (CNS). Multiple genetic predispositions and environmental factors are known to influence the immune response in autoimmune diseases, such as MS, and in the experimental autoimmune encephalomyelitis (EAE) model. Although the predisposition to suffer from MS seems to be a multifactorial process, a highly sensitive period is pregnancy due to factors that alter the development and differentiation of the CNS and the immune system, which increases the offspring’s susceptibility to develop MS. In this regard, there is evidence that thyroid hormone deficiency during gestation, such as hypothyroidism or hypothyroxinemia, may increase susceptibility to autoimmune diseases such as MS. In this review, we discuss the relevance of the gestational period for the development of MS in adulthood.

Childhood pet ownership and multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Many studies have been conducted investigating a range of environmental factors which have been implicated in the pathogenesis of multiple sclerosis (MS). We collated available data about exposure to domestic animals before symptom onset in MS to perform a systematic review and meta-analysis.

METHODS

Medline, Embase and Cinahl were searched for relevant articles, based on pre-defined inclusion and exclusion criteria and reference lists were hand-searched. Data were extracted and critical analysis was conducted using the Newcastle-Ottawa criteria. Meta-analysis used random effects.

RESULTS

Study heterogeneity was high and study quality was variable. Random effects meta-analysis showed no associations with any pet ownership and development of MS.

CONCLUSION

It is not possible to draw definitive conclusions from this work. The studies included had a high level of heterogeneity. There are many variables involved in pet ownership and exposure and the nature of the way these have been studied makes the analysis challenging.

The impact of Opisthorchis felineus infection and praziquantel treatment on the intestinal microbiota in children

The presence of some species of helminths is associated with changes in host microbiota composition and diversity, which varies widely depending on the infecting helminth species and other factors. We conducted a prospective case-control study to evaluate the gut microbiota in children with Opisthorchis felineus infection (n=50) before and after anthelmintic treatment and in uninfected children (n=49) in the endemic region. A total of 99 children and adolescents aged between 7 and 18 years were enrolled to the study. Helminth infection was assessed before and at 3 months after treatment with praziquantel. A complex examination for each participant was performed in the study, including an assessment of the clinical symptoms and an intestinal microbiota survey by 16S rRNA gene sequencing of stool samples. There was no change in alpha diversity between O. felineus-infected and control groups. We found significant changes in the abundances of bacterial taxa at different taxonomic levels between the infected and uninfected individuals. Enterobacteriaceae family was more abundant in infected participants compared to uninfected children. On the genus level, O. felineus-infected participants' microbiota showed higher levels of Lachnospira, Escherichia-Shigella, Bacteroides, Eubacterium eligens group, Ruminiclostridium 6, Barnesiella, Oscillibacter, Faecalitalea and Anaerosporobacter and reduction of Blautia, Lachnospiraceae FCS020 and Eubacterium hallii group in comparison with the uninfected individuals. Following praziquantel therapy, there were significant differences in abundances of some microorganisms, including an increase of Faecalibacterium and decrease of Megasphaera, Roseburia. Enterobacteriaceae and Escherichia abundances were decreased up to the control group values. Our results highlight the importance of the host-parasite-microbiota interactions for the community health in the endemic regions.

Association of the global distribution of multiple sclerosis with ultraviolet radiation and air pollution: an ecological study based on GBD data

Given the growing global trend of multiple sclerosis (MS), this study was designed to evaluate environmental determinates of the worldwide distribution of MS in the presence of socioeconomic and geographic indices. MS data was obtained from the Institute for Health Metrics and Evaluation website. The air pollution parameters, including particles with aerodynamic diameter less than 2.5 μm (PM_2.5), tropospheric ozone, and solid fuel use, were acquired from global burden of disease resources and the World Health Organization. Ultraviolet index (UVI) values were obtained from the Tropospheric Emission Monitoring Internet Service website. Correlation and linear regression analyses were used to investigate the relationship between air pollution and environmental parameters with MS variables. The average prevalence and incidence rates in countries with high UVI were 5.17 and 0.25 per 100,000, respectively, and in countries with low UVI were 101.37 and 0.78, respectively. The results showed negative associations between prevalence, incidence and mortality of MS with ozone concentrations (β = - 1.04, - 0.04, and - 0.01 respectively; P < 0.01). Also, the fully adjusted model showed significant negative correlation of UVI with the MS variables in the presence of other variables (P < 0.01). Our findings demonstrated that UVI had the strongest significant inverse association with MS distribution. Consequently, vitamin D intake may be a major contributor to MS development. However, this study showed a slight influence of air pollution on the prevalence of MS in the presence of other parameters. Given the inconsistent results of previous studies, further studies may be required.

Shared breastfeeding & other early multiple sclerosis risk factors: A case-control study

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease. Etiology is thought to be multifactorial with genetic and environmental factors interplay. Our objective in this study is to evaluate culture specific and other early life risk factors for MS. We examined the association between MS and breastfeeding including shared breastfeeding, parental consanguinity, being born abroad or living abroad during childhood, prematurity, vaccination, tonsillectomy, rank among siblings, number of siblings, number of household members (HHM) at birth, and age first time joining school.

METHODS

This is an age and sex matched case-control study that was conducted in Riyadh, Kingdom of Saudi Arabia (KSA). We enrolled 300 cases and 601 controls. A structured questionnaire about demographics, consanguinity and potential environmental factors was answered by participants. Data was analyzed using logistic regression adjusting for covariates occurring later in life such as waterpipe smoking and performing Hajj.

RESULTS

About two thirds of the cases and the controls were females. Mean age was 34.8 (9.2) for the cases and 33.6 (10.6) for the controls. We found that shared breastfeeding (OR=0.58; 95% CI, 0.35-0.96, p = 0.033), and older age first joining school (OR=0.83; 95% CI, 0.73-0.94, p = 0.005) were associated with decrease risk of MS. While longer duration of breastfeeding by biological mother (OR=1.03; 95% CI, 1.01-1.04, p = 0.001), rank among siblings of ≥6 (OR=1.69; 95% CI, 1.11-2.56, p = 0.014), and larger number of HHM at birth (OR=2.32; 95% CI, 1.64-3.28, p = 0.001) were associated with increased risk. Patients with MS were less likely to receive formula with breastfeeding than controls (OR=0.72; 95% CI, 0.51-0.99, p = 0.046). No association was found with breastfeeding by biological mother, number of siblings, prematurity, being born abroad or living abroad during childhood, vaccination, consanguinity, or tonsillectomy.

CONCLUSION

The findings of this case-control study add to the accumulating evidence that early life factors could modify the risk of developing MS. Among these, novel associations with shared breastfeeding and number of HHM at birth are suggested. Future studies are needed to verify the observed results.

Prevalence and incidence of multiple sclerosis in Ardabil, Northwest of Iran

BACKGROUND

Multiple sclerosis (MS) epidemiology is studies in many populations; however, studying populations with unique characteristics could provide opportunities to deepen the understanding of the underlying reason of the disease. In this regard, we aimed to study the epidemiology of MS in Ardabil, a province in northwest Iran, where the majority are of Iranian Azerbaijanis.

METHOD

A retrospective population-based study was conducted from 2008 to 2018 in Ardabil, based on the data of Iran's Ministry Of Health. Collected information includes sex, age, age at disease onset, education and type of MS. We used t-test to compare means and chi-square test to analyze the association among variables.

RESULTS

The total number of patients was 760 with 533 (70.13%) females and 227 (29.87%) males. The crude prevalence was 59.37 per 100,000 in 2018 (95% CI: 55.31, 63.73). The crude incidence rate was 7.65 per 100,000 in 2018 (95% CI: 6.28, 9.32). The most frequent educational level was high school diploma (38.36%). The relapsing-remitting (RR) form was the most frequent type of MS (48.16%). The F/M ratio was 2.92:1 and the mean onset age was 33.14 (95% CI: 31.56, 34.72) in 2018, significantly higher in males (P value= 0.01).

CONCLUSION

Ardabil is a medium risk zone of MS. The different ethnicity of its population, climate and environmental features, may explain the factors modulating the risk of MS in similar areas and present windows of opportunity to understand the causes of MS.

Childhood infections, vaccinations, and tonsillectomy and risk of first clinical diagnosis of CNS demyelination in the Ausimmune Study

BACKGROUND

The association between childhood vaccinations and infections and risk of multiple sclerosis is unclear; few studies have considered age at vaccination/infection.

OBJECTIVE

To explore age-related associations between childhood vaccinations, infection and tonsillectomy and risk of a first clinical diagnosis of CNS demyelination.

METHODS

Data on case (n = 275, 76.6% female; mean age 38.6 years) and age- and sex-matched control (n = 529) participants in an incident population-based case-control study included self-reported age at time of childhood vaccinations, infections, and tonsillectomy. Conditional logistic regression models were used to calculate adjusted odds ratios (AOR) and 95% confidence intervals (CI).

RESULTS

Poliomyelitis vaccination prior to school-age was associated with increased risk of a first clinical diagnosis of CNS demyelination (AOR = 2.60, 95%CI 1.02-6.68), based on a very small unvaccinated reference group. Late (11-15 years) rubella vaccination (compared to none) was associated with lower odds of being a case (AOR = 0.47, 95%CI 0.27-0.83). Past infectious mononucleosis at 11-15 years (AOR = 2.84, 95%CI 1.0-7.57) and 16-20 years (AOR = 1.92, 95%CI 1.12-3.27) or tonsillectomy in adolescence (11-15 years: AOR = 2.45, 95%CI 1.12-5.35), including after adjustment for IM, were associated with increased risk of a first clinical diagnosis of CNS demyelination.

CONCLUSIONS

Age at vaccination, infection or tonsillectomy may alter the risk of subsequent CNS demyelination. Failing to account for age effects may explain inconsistencies in past findings.

Association of infections with multiple sclerosis in Gulf Cooperation Council countries: a review

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system, causing inflammation, demyelination, and neurodegeneration. Infection can play a role in its etiology. Herein, a review is presented of studies that have reported an association between infection and MS risk in countries of the Arabian Gulf region. Searches of the PubMed, Google Scholar, and Science Direct databases were carried out using various search terms, and relevant studies published through January 2019 on the epidemiology of MS in Gulf Cooperation Council countries identified. MS has been found to be associated with measles in Saudi Arabia and Epstein–Barr virus in Kuwait whereas no association has been identified between risk of MS and varicella-zoster virus, mumps, or human herpesvirus-6. However, few epidemiological studies on this topic have been conducted in countries of the Gulf region. Longitudinal and serological studies to establish robust evidence between infection and risk of MS are highly recommended, and a regional MS registry is needed.

Micronized Cells of the Probiotic Strain Bifidobacterium lactis BS01 Activate Monocyte Polarization: A New Approach

GOALS

The aim of this research was to evaluate whether micronized cells (MCs) from selected biotherapeutic bacteria have the ability to effectively modulate the polarization of monocyte/macrophage subpopulations to advantageously provide a first line of defense against infections.

BACKGROUND

Inflammation is a reaction of the host to viral and bacterial infections with the physiological purpose of restoring tissue homeostasis. However, uncontrolled or unresolved inflammation can lead to tissue damage, giving rise to a plethora of chronic inflammatory diseases. The monocytes/macrophages play a key role in the initiation and resolution of inflammation through different activation programs.

STUDY

MCs were obtained from Bifidobacterium lactis BS01 strain using a Bioimmunizer extraction protocol. Monocytes were stimulated with the probiotic strain and/or MCs (10 mg/mL) for 24 hours and 5 days. Monocyte/macrophage differentiation was evaluated by cytometry analysis of surface markers and the activity of the 2 subpopulations on oxidative stress was assessed in an in vitro oxidative stress model with a spectrophotometric test.

RESULTS

The MCs have been shown to modulate considerably the 2 subpopulations of human monocytes/macrophages, both the "patrolling subpopulation" and the "inflammatory subpopulation," thus highlighting a strong immunostimulatory effect. In addition, MCs are able to mitigate significantly the oxidative stress induced by homocysteine in an in vitro model.

CONCLUSIONS

Our findings suggest that MCs derived from the biotherapeutic strain BS01 could represent a possible therapy aimed to effectively prevent and/or cure viral, bacterial, fungal, or protozoal diseases, as well as prevent and/or treat inflammatory processes triggered by external pathogenic agents.