Protein deficiency and intestinal nematode infection in pregnant mice differentially impact fetal growth through specific stress hormones, growth factors, and cytokines

Maternal gastrointestinal nematode infection enhances spatial memory of uninfected juvenile mouse pups

The developing brain is particularly vulnerable to factors including maternal infection during pregnancy. Establishment of neural networks critical for memory and cognition begins during the perinatal period, when Heligmosomoides bakeri, a gastrointestinal (GI) nematode restricted to the maternal mouse intestine, has been shown to upregulate expression of long-term potentiation genes in the young rodent pup brain. We explored the impact of maternal infection during pregnancy and early lactation on the spatial behavior of uninfected male and female juvenile mice. Pre-weaned pups of H. bakeri infected dams exhibited less exploratory behaviour compared to pups of uninfected dams on postnatal day (PD) 16 but not PD 17, possibly reflecting a transient fear of an unfamiliar environment and/or a brief neurodevelopmental delay. Our two spatial memory tests show for the first time an enhancement of spatial memory in response to maternal nematode infection regardless of pup sex. At PD 17, pups of infected dams expressed object location memories after 3 h in the Object Location Test whereas offspring of uninfected mothers did not. In addition, at PD 34, juveniles of infected mothers retained their ability to find the escape hole in the Barnes Maze Test for one week whereas offspring from uninfected mothers did not. This finding is even more striking given that spatial memory was positively associated with pup length, yet this maternal infection impaired linear growth of pups. Thus, the positive impact of maternal infection on spatial memory countered any impairment associated with the shorter length of the pups. Overall, these novel findings indicate that a maternal GI nematode infection during pregnancy and lactation positively influences the spatial memory of uninfected juvenile offspring with potential fitness implications for the next generation.

Relationship between hemoglobin and insulin-like growth factor-1 in children and adolescents with idiopathic short stature

BACKGROUND

The growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis is critical for the regulation of children's growth and development. Serum IGF-1 concentrations are usually low in individuals with idiopathic short stature (ISS) despite normal endogenous GH levels, and the associated underlying factors are unknown. This study aimed to explore the relationship between IGF-1 and hemoglobin (Hb) in children with ISS.

METHODS

A cross-sectional analysis was performed including 178 children and adolescents with ISS who were enrolled from March 2013 to February 2019. The related clinical and biochemical parameters were evaluated for each patient. Univariate analysis, smooth curve fitting and multivariate piecewise linear regression were performed.

RESULT

The mean levels of IGF-1 standard deviation scores (SDS) and Hb were - 0.99 (- 1.60 - -0.09) and 131.81 ± 9.36 g/L, respectively. Univariate analysis displayed a significant positive association between Hb and IGF-1 SDS (P < 0.001). After adjusting for potential confounding factors, the positive relationship between Hb and IGF-1 SDS remained (P = 0.001). Furthermore, there was an inflection point for Hb in the curve. In a multivariate piecewise linear regression model, IGF-1 SDS was significantly positively associated with Hb when Hb concentrations were lower than 145 g/L (B 0.05; 95% CI 0.02, 0.07; P < 0.001). However, IGF-1 SDS decreased with increasing Hb levels when Hb concentrations were greater than 145 g/L (B -0.15; 95% CI -0.23, - 0.06; P = 0.001).

CONCLUSION

This study demonstrated that Hb is associated with IGF-1 in Chinese children and adolescents with ISS. The levels of IGF-1 increased with the elevation of Hb, but when the concentration of Hb exceeded a certain range, with the increase of Hb, IGF-1 decreased instead.

Differential expression of genes in fetal brain as a consequence of maternal protein deficiency and nematode infection

Maternal dietary protein deficiency and gastrointestinal nematode infection during early pregnancy have negative impacts on both maternal placental gene expression and fetal growth in the mouse. Here we used next-generation RNA sequencing to test our hypothesis that maternal protein deficiency and/or nematode infection also alter the expression of genes in the developing fetal brain. Outbred pregnant CD1 mice were used in a 2×2 design with two levels of dietary protein (24% versus 6%) and two levels of infection (repeated sham versus Heligmosomoides bakeri beginning at gestation day 5). Pregnant dams were euthanized on gestation day 18 to harvest the whole fetal brain. Four fetal brains from each treatment group were analyzed using RNA Hi-Seq sequencing and the differential expression of genes was determined by the edgeR package using NetworkAnalyst. In response to maternal H. bakeri infection, 96 genes (88 up-regulated and eight down-regulated) were differentially expressed in the fetal brain. Differentially expressed genes were involved in metabolic processes, developmental processes and the immune system according to the PANTHER classification system. Among the important biological functions identified, several up-regulated genes have known neurological functions including neuro-development (Gdf15, Ing4), neural differentiation (miRNA let-7), synaptic plasticity (via suppression of NF-κβ), neuro-inflammation (S100A8, S100A9) and glucose metabolism (Tnnt1, Atf3). However, in response to maternal protein deficiency, brain-specific serine protease (Prss22) was the only up-regulated gene and only one gene (Dynlt1a) responded to the interaction of maternal nematode infection and protein deficiency. In conclusion, maternal exposure to GI nematode infection from day 5 to 18 of pregnancy may influence developmental programming of the fetal brain.

DOHaD at the intersection of maternal immune activation and maternal metabolic stress: a scoping review

The prenatal environment is now recognized as a key driver of non-communicable disease risk later in life. Within the developmental origins of health and disease (DOHaD) paradigm, studies are increasingly identifying links between maternal morbidity during pregnancy and disease later in life for offspring. Nutrient restriction, metabolic disorders during gestation, such as diabetes or obesity, and maternal immune activation provoked by infection have been linked to adverse health outcomes for offspring later in life. These factors frequently co-occur, but the potential for compounding effects of multiple morbidities on DOHaD-related outcomes has not received adequate attention. This is of particular importance in low- or middle-income countries (LMICs), which have ongoing high rates of infectious diseases and are now experiencing transitions from undernutrition to excess adiposity. The purpose of this scoping review is to summarize studies examining the effect and interaction of co-occurring metabolic or nutritional stressors and infectious diseases during gestation on DOHaD-related health outcomes. We identified nine studies in humans - four performed in the United States and five in LMICs. The most common outcome, also in seven of nine studies, was premature birth or low birth weight. We identified nine animal studies, six in mice, two in rats and one in sheep. The interaction between metabolic/nutritional exposures and infectious exposures had varying effects including synergism, inhibition and independent actions. No human studies were specifically designed to assess the interaction of metabolic/nutritional exposures and infectious diseases. Future studies of neonatal outcomes should measure these exposures and explicitly examine their concerted effect.