IgM in human immunity to Plasmodium falciparum malaria

Most studies on human immunity to malaria have focused on the roles of immunoglobulin G (IgG), whereas the roles of IgM remain undefined. Analyzing multiple human cohorts to assess the dynamics of malaria-specific IgM during experimentally induced and naturally acquired malaria, we identified IgM activity against blood-stage parasites. We found that merozoite-specific IgM appears rapidly in Plasmodium falciparum infection and is prominent during malaria in children and adults with lifetime exposure, together with IgG. Unexpectedly, IgM persisted for extended periods of time; we found no difference in decay of merozoite-specific IgM over time compared to that of IgG. IgM blocked merozoite invasion of red blood cells in a complement-dependent manner. IgM was also associated with significantly reduced risk of clinical malaria in a longitudinal cohort of children. These findings suggest that merozoite-specific IgM is an important functional and long-lived antibody response targeting blood-stage malaria parasites that contributes to malaria immunity.

Treg cells promote decidual vascular remodeling and modulate uterine NK cells in pregnant mice

Regulatory T (Treg) cells are essential for maternal immune tolerance of the fetus and placenta. In preeclampsia, aberrant Treg cell tolerance is implicated, but how Treg cells affect the uterine vascular dysfunction thought to precede placental impairment and maternal vasculopathy is unclear. We used Foxp3-diphtheria toxin receptor mice to test the hypothesis that Treg cells are essential regulators of decidual spiral artery adaptation to pregnancy. Transient Treg cell depletion during early placental morphogenesis caused impaired remodeling of decidual spiral arteries, altered uterine artery function, and fewer Dolichos biflorus agglutinin+ uterine natural killer (uNK) cells, resulting in late-gestation fetal loss and fetal growth restriction. Replacing the Treg cells by transfer from wild-type donors mitigated the impact on uNK cells, vascular remodeling, and fetal loss. RNA sequencing of decidua revealed genes associated with NK cell function and placental extravillous trophoblasts were dysregulated after Treg cell depletion and normalized by Treg cell replacement. These data implicate Treg cells as essential upstream drivers of uterine vascular adaptation to pregnancy, through a mechanism likely involving phenotypic regulation of uNK cells and trophoblast invasion. The findings provide insight into mechanisms linking impaired adaptive immune tolerance and altered spiral artery remodeling, 2 hallmark features of preeclampsia.

Maternal modifiable factors and risk of congenital heart defects: systematic review and causality assessment

OBJECTIVE

Primary prevention strategies are critical to reduce the global burden of congenital heart defects (CHDs); this requires robust knowledge of causal agents. We aimed to review associations between CHDs and maternal advanced age, obesity, diabetes, hypertension, smoking and alcohol consumption and assess the causal nature of the associations.

DESIGN

Systematic review of reviews with application of a Bradford Hill criteria score-based causal assessment system.

DATA SOURCES

We searched PubMed, Embase and Episteminokos (January 1990-April 2023).

ELIGIBILITY CRITERIA

Systematic reviews of original epidemiological studies reporting association (relative risk) between one or more of the above maternal factors and CHDs overall (any type) in subsequent offspring.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers selected eligible reviews, assessed the risk of bias and assigned the strength of evidence for causality.

RESULTS

There was strong evidence of a causal relationship between CHDs and maternal obesity (prepregnancy and early pregnancy) and pre-existing diabetes (six of seven Bradford Hill criteria met). For pre-existing hypertension (strength and biological gradient not met), and advanced age (strength, consistency and biological gradient not met), causal evidence was moderate. Evidence for the causal contribution of gestational diabetes, gestational hypertension, smoking and alcohol consumption was weak (strength, consistency, temporality and biological gradient not met).

CONCLUSIONS

CHDs can be reduced with stronger action to reduce maternal obesity and pre-existing diabetes prevalence. Investigating environmental exposures that have received limited attention, such as air pollutants and chemical exposures, is important to further inform prevention.

Trends in clinical management of lactational mastitis among women attending Australian general practice: a national longitudinal study using MedicineInsight, 2011-2022

OBJECTIVE

To examine longitudinal trends in clinical management of lactational mastitis in women attending general practice.

DESIGN

Open cohort study.

SETTING

Australian general practice using data from MedicineInsight.

PARTICIPANTS

Women aged 18 to 44 years with one or more clinical encounters for lactational mastitis between January 2011 and July 2022.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the proportion of prescribed oral antibiotics based on the antibiotic type. Secondary outcome measures were the proportion of women prescribed other medications (eg, antifungals, lactation suppressants) or ordered selected clinical investigations including breast ultrasound, blood test, breast milk culture, nipple swab culture or breast aspirate. Outcomes were examined based on the calendar year and individual- or clinical practice-level characteristics.

RESULTS

Among 25 002 women who had one or more clinical encounters related to mastitis, 90.9% were prescribed oral antibiotics. While the proportion of women prescribed an oral antibiotic remained consistent from 2011 to 2022 (91.1% vs 92.5%), there were changes in the proportion receiving prescriptions for di/flucloxacillin (46.1% vs 60.4%) and cefalexin (38.6% vs 26.5%). Fewer than 12% of women were clinically investigated for their mastitis encounter, most commonly a breast ultrasound (7.1%), followed by a selected blood test (3.8%). Requests for breast milk cultures, nipple swab cultures or breast aspirates occurred in less than 1.1% of individuals. Significant increases were evident with respect to ordering of all clinical investigations, with rates at least doubling between 2011 and 2022 (6.6% vs 14.7%). Large variability in clinical management was evident according to both individual- (eg, concessional status) and clinical practice-level characteristics (eg, remoteness).

CONCLUSIONS

Australian general practitioners commonly prescribe oral antibiotics to women with mastitis and largely in line with clinical guidelines. Their use of clinical investigations as part of mastitis management has increased over the last decade.

Effect of brewer's yeast or beta-glucan on breast milk supply following preterm birth: the BLOOM study - protocol for a multicentre randomised controlled trial

BACKGROUND

Many individuals who experience preterm birth struggle with early breast milk supply, which can translate into suboptimal longer-term breastfeeding outcomes. Further investigations into the potential role of early non-pharmacological and pharmacological interventions in improving breast milk production soon after birth is growing. While natural galactagogues, such as brewer's yeast, are widely perceived by women to be safer than pharmaceutical galactagogues and are taken by many women, evidence to support their efficacy is largely absent. The BLOOM study has been designed to determine the efficacy and safety of brewer's yeast and beta-glucans, derived from Saccharomyces cerevisiae, when administered soon after birth for increasing early breast milk supply in mothers who have delivered preterm.

METHODS

The BLOOM study is a multicentre, double-blinded, randomised controlled trial that will assess if brewer's yeast or beta-glucan can increase early breast milk production following preterm birth. Target population are mothers of preterm infants born at less than 34 weeks' gestation who intend to provide breast milk for their infant, are less than 72 h following birth and able to give informed consent. Participants will be randomly allocated into three parallel groups at 1:1:1 ratio (n = 33 per group) to receive either brewer's yeast, beta-glucan or placebo capsules for seven days. The primary outcome is total expressed breast milk volume over a 24-hour period on day 7 of intervention. Participants and their infants will be followed until the infant reaches term corrected age or is discharged home from the neonatal unit (whichever occurs first).

DISCUSSION

The use of brewer's yeast as a galactagogue to enhance milk production is extremely common amongst breastfeeding mothers, however, there are no trials evaluating its efficacy and safety. This will be the first randomised controlled trial to evaluate the efficacy and safety of two commonly used galactagogues, brewer's yeast and beta-glucan, compared with placebo in improving maternal breast milk supply following preterm birth. The trial will also evaluate whether early intervention with galactagogues soon after a preterm birth improves longer-term breastfeeding outcomes.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12622000968774 (registered on 8 July 2022) and UTN U1111-1278-8827.

Effects of exercise on vascular remodelling and fetal growth in uncomplicated and abortion-prone mouse pregnancies

Studies in humans and rodents show exercise in pregnancy can modulate maternal blood pressure, vascular volume, and placental efficiency, but whether exercise affects early uteroplacental vascular adaptations is unknown. To investigate this, CBA/J female mice mated with BALB/c males to generate healthy uncomplicated pregnancies (BALB/c-mated) or mated with DBA/2J males to generate abortion-prone pregnancies (DBA/2J-mated), were subjected to treadmill exercise (5 days/week, 10 m/min, 30 min/day for 6 weeks before and throughout pregnancy), or remained sedentary. In uncomplicated pregnancies, exercise caused symmetric fetal growth restriction in fetuses evidenced by reductions in fetal weight, crown-to-rump length, abdominal girth and biparietal diameter. Placental insufficiency was indicated by reduced fetal: placental weight ratio and increased glycogen cell content in the junctional zone of placentas of exercised BALB/c-mated mice on gestational day (GD)18.5. In abortion-prone pregnancy, exercise increased placental efficiency, but the number of late-pregnancy resorptions were elevated. Effects of paternal genotype independent of exercise were evidenced by a greater number of resorptions, poorer spiral artery remodelling, and larger placentas in the DBA/2J-mated compared to BALB/c-mated mice. Effects of exercise independent of paternal genotype included increased implantation sites at both mid and late pregnancy, accompanied by decreased junctional zone areas of placentas. Our findings show that exercise before and during pregnancy in mice can have different effects on fetal outcomes, depending on the paternal and/or fetal genotype. This suggests that the underlying mechanisms are responsive to fetal cues.

Trends in clinical encounters and management for infertility among women attending Australian general practice: a national longitudinal study using MedicineInsight, 2011 to 2021

OBJECTIVE

To examine longitudinal trends in infertility management in women attending general practice.

DESIGN

Cohort study using the national general practice dataset, MedicineInsight.

SETTING

Australian general practice.

INTERVENTIONS

Not applicable.

PARTICIPANTS

The cohort included 2 552 339 women aged 18-49 years with one or more general practice clinical encounters between January 2011 and December 2021.

PRIMARY AND SECONDARY OUTCOME MEASURESS

The primary outcome assessed was the proportion of women who had a clinical encounter related to infertility, stratified by year and age group. Second, the proportions of women receiving relevant clinical management actions, including selected pathology tests, imaging ordered and selected medications, were calculated. Univariable logistic regression analyses compared the likelihood of women having a documented clinical encounter related to infertility and receiving selected management actions based on individual characteristics. We also examined practice-level variation in the proportion receiving selected management for infertility by stratifying proportions based on practice site.

RESULTS

A total of 2 552 339 women had one or more clinical encounters with their general practitioner (GP) between January 2011 and December 2021, of which 27 671 (1.1%) had a clinical encounter related to infertility management. The rate of infertility encounters increased from 3.4 per 1000 in 2011 to 5.7 per 1000 in 2021. Over episodes of care, half (50.9%) of women presenting for an infertility encounter had at least one specified pathology test, and almost a quarter (23.1%) had a specified imaging test. A relatively small proportion of infertility encounters (5.4%) resulted in prescribing of a selected infertility medication by the GP.Large variation in clinical management (pathology, imaging and medication prescribing) was evident according to both individual characteristics and also at the clinical-practice level. Factors associated with increased likelihood of being provided infertility medications included younger age, holding a Commonwealth concession card (indicating low income), lower socioeconomic status and living outside a major city.

CONCLUSIONS

Clinical encounters related to infertility are increasing in primary care, with large variation evident in corresponding clinical management. These findings support the development of clinical practice guidelines to enhance standardised and equitable approaches towards the management of infertility in primary care.