Neural tube defects, micronutrient deficiencies, and Helicobacter pylori: a new hypothesis

Role of Maternal Infections and Inflammatory Responses on Craniofacial Development

Pregnancy is a tightly regulated immunological state. Mild environmental perturbations can affect the developing fetus significantly. Infections can elicit severe immunological cascades in the mother's body as well as the developing fetus. Maternal infections and resulting inflammatory responses can mediate epigenetic changes in the fetal genome, depending on the developmental stage. The craniofacial development begins at the early stages of embryogenesis. In this review, we will discuss the immunology of pregnancy and its responsive mechanisms on maternal infections. Further, we will also discuss the epigenetic effects of pathogens, their metabolites and resulting inflammatory responses on the fetus with a special focus on craniofacial development. Understanding the pathophysiological mechanisms of infections and dysregulated inflammatory responses during prenatal development could provide better insights into the origins of craniofacial birth defects.

Helicobacter pylori infection and micronutrient deficiency in pregnant women: a systematic review and meta-analysis

Background

Over the last few years, epidemiological studies have shown that infection with Helicobacter pylori has a major effect on micronutrient deficiency as well as on adverse pregnancy outcomes. Importantly, there are gaps in understanding the linkage of H. pylori infection with micronutrients deficiency in pregnant women.

Objective

We conducted a systematic review and meta-analysis to estimate the association between H. pylori infection and micronutrient deficiencies in pregnant women.

Methods

A systematic literature search was conducted for relevant articles using PubMed, Web of Science, and Scopus database from inception to March 2020. The OR with 95% CIs was determined by meta-analysis of data extracted from the selected studies.

Results

From 2384 primary articles, 6 studies were selected for systematic reviews and 4 studies distinctively (with 1274 participants: 553 cases and 721 controls) were selected for meta-analysis. The meta-analysed fixed effect model estimated the odds of having H. pylori infection was not significantly higher among pregnant women with micronutrient deficiencies than those without deficiencies (OR=1.12, 95% CI 0.88 to 1.42, p=0.37). In the subgroup analysis, no correlation was found between H. pylori infection and vitamin B₁₂ (OR=0.74, 95% CI 0.45 to 1.21, p=0.22), folate (OR=1.07, 95% CI 0.73 to 1.58, p=0.73), and ferritin (OR=0.81, 95% CI 0.51 to 1.31, p=0.4). However, a positive correlation was found between iron-deficiency anaemia (IDA) and H. pylori infection (OR=16.23, 95% CI 4.19 to 62.93, p<0.0001) during pregnancy.

Conclusion

H. pylori infection is associated with increased risk of IDA but not with deficiency of other micronutrients in pregnancy.

PROSPERO registration number

CRD42019135683.

The risk of Helicobacter pylori infection for adverse pregnancy outcomes: A systematic review and meta-analysis

OBJECTIVE

To estimate the current evidence regarding the association between Helicobacter pylori infection during pregnancy and adverse pregnancy outcomes.

MATERIALS AND METHODS

A systematic literature search for relevant publications was conducted using PubMed, EMBASE, Cochrane Library, and Web of science databases through November 17th, 2018. The pooled odds ratios (ORs) with their corresponding 95% confidence intervals (CIs) were selected as the effect size. Subgroup analysis and sensitivity analysis were performed.

RESULTS

Thirty-one studies with a total of 22 845 participants were identified. There was significant association of H pylori infection with preeclampsia (OR: 2.51; 95% CI: 1.88-3.34; P < 0.001), fetal growth restriction (OR: 2.28; 95% CI: 1.21-4.32; P = 0.01), gestational diabetes mellitus (OR: 2.03; 95% CI: 1.56-2.64; P < 0.001), spontaneous abortion (OR: 1.50; 95% CI: 1.05-2.14; P = 0.024), and birth defect (OR: 1.63; 95% CI: 1.05-2.54; P = 0.03). Sensitivity analysis showed the significant association between H pylori infection and low birthweight (OR: 1.59; 95% CI: 1.05-2.40; P = 0.03).

CONCLUSION

The present meta-analysis offers proof to support that H pylori infection during pregnancy can increase the risk on adverse pregnancy outcomes. Screening and treating for H pylori infection before pregnancy should be taken into account.

Helicobacter pylori Seropositivity and Childhood Neurodevelopment, the Rhea Birth Cohort in Crete, Greece

BACKGROUND

Limited evidence exists on the association between exposure to Helicobacter pylori infection early in life, including fetal life, and neurodevelopment in childhood.

METHODS

We used prospective data on 352 mother-child pairs and cross-sectional data on 674 children to assess the association of maternal and child's H. pylori seropositivity correspondingly on child's neurodevelopment at age four in the Rhea birth cohort in Crete, Greece. Blood levels of immunoglobulin G antibodies to 12 H. pylori proteins were measured using multiplex serology. Child's neurodevelopment at age four was assessed using the McCarthy Scales of Children's Abilities. Linear regression models were used to explore the associations after adjusting for potential confounders.

RESULTS

Helicobacter pylori seroprevalence (95% CI) in cord blood, representing maternal status, was 41.5% (36.3%, 46.8%) and in 4 years old children was 6.5% (95% CI 4.8%, 8.7%). Children of H. pylori seropositive mothers had lower score in the general cognitive (-3.87, 95% CI -7.02, -0.72), verbal (-2.96, 95% CI -6.08, 0.15), perceptual performance (-3.37, 95% CI -6.60, -0.15), quantitative (-2.85, 95% CI -6.28, 0.58), and memory scale (-3.37, 95% CI -6.67, -0.07) compared to those of seronegative mothers. Seropositivity in cord blood specifically to GroEl and NapA - two of the 12 H. pylori proteins investigated - was associated with lower scores in almost all scales. At age four, H. pylori seropositive children performed worst in neurodevelopment assessment compared to their seronegative counterparts although no association reached statistically significant level.

CONCLUSIONS

Helicobacter pylori infection in early life may be an important but preventable risk factor for poor neurodevelopment.

Contemporary migration patterns in the prevalence of Helicobacter pylori infection: A systematic review

BACKGROUND

A rapid growth in the number of international migrants over the past years has occurred with most traveling to more affluent settings. As Helicobacter pylori infects over half of the adult population and its prevalence is higher in developing countries, understanding the prevalence of infection in migrants can provide insight into future trends in the burden and management of infection. We aimed to describe the prevalence of H. pylori among migrants through a systematic literature review.

METHODS

We searched PubMed^® from inception to September 2015 to identify studies reporting the prevalence of H. pylori in international migrants according to country of birth for first-generation, and country of birth and parents' nationality for successive generations. Comparable data from origin and destination populations were obtained from the same studies or, when not present, from a previous systematic review on H. pylori worldwide.

RESULTS

A total of 28 eligible studies were identified with data for 29 origin and 12 destination countries. Two studies that evaluated refugees presented prevalences of infection higher than both the origin and destination countries. Otherwise, the prevalences among migrants were generally similar or below that of the origin and higher than the destination. Second- or more generation had lower prevalences compared to first-generation migrants.

CONCLUSIONS

Our study findings are consistent with what would be expected based on the prevalence of H. pylori worldwide. The results of this review show that migrants are particularly at risk of infection and help to identify gaps in the knowledge of migrants' prevalence of infection globally.

Helicobacter pylori and pregnancy-related disorders

Helicobacter pylori (H. pylori) infection is investigated in gastric diseases even during pregnancy. In particular, this Gram-negative bacterium seems to be associated with hyperemesis gravidarum, a severe form of nausea and vomiting during pregnancy. During the last decade, the relationship among H. pylori and several extra-gastric diseases strongly emerged in literature. The correlation among H. pylori infection and pregnancy-related disorders was mainly focused on iron deficiency anemia, thrombocytopenia, fetal malformations, miscarriage, pre-eclampsia and fetal growth restriction. H. pylori infection may have a role in the pathogenesis of various pregnancy-related disorders through different mechanisms: depletion of micronutrients (iron and vitamin B₁₂) in maternal anemia and fetal neural tube defects; local or systemic induction of pro-inflammatory cytokines release and oxidative stress in gastrointestinal disorders and pre-eclampsia; cross-reaction between specific anti-H. pylori antibodies and antigens localized in placental tissue and endothelial cells (pre-eclampsia, fetal growth restriction, miscarriage). Since H. pylori infection is most likely acquired before pregnancy, it is widely believed that hormonal and immunological changes occurring during pregnancy could activate latent H. pylori with a negative impact not only on maternal health (nutritional deficiency, organ injury, death), but also on the fetus (insufficient growth, malformation, death) and sometime consequences can be observed later in life. Another important issue addressed by investigators was to determine whether it is possible to transmit H. pylori infection from mother to child and whether maternal anti-H. pylori antibodies could prevent infant’s infection. Studies on novel diagnostic and therapeutic methods for H. pylori are no less important, since these are particularly sensitive topics in pregnancy conditions. It could be interesting to study the possible correlation between H. pylori infection and other pregnancy-related diseases of unknown etiology, such as gestational diabetes mellitus, obstetric cholestasis and spontaneous preterm delivery. Since H. pylori infection is treatable, the demonstration of its causative role in pregnancy-related disorders will have important social-economic implications.

Extragastric manifestations of Helicobacter pylori infection: other Helicobacters

The finding that Helicobacter pylori is the main cause of gastritis and peptic ulcer disease has opened a new era in the gastrointestinal world. Today there is evidence that H. pylori may also play a role in different nongastric diseases, opening the new "extragastric manifestations of H. pylori infection" field. Concerning this, several studies have been published in the last year. The most convincing data arise from those investigating idiopathic thrombocytopenic purpura and sideropenic anemia, while there is also an increasing evidence for a possible association with atherosclerotic disease. Furthermore, the discovery of a number of other novel Helicobacter species has stimulated the research in different extragastric diseases, in which an infectious hypothesis is plausible. In particular, several species have been studied for a potential role in different liver and intestinal diseases with interesting findings.