Fetal Brain Gene Expression Is More Responsive to Maternal Intestinal Nematode Infection than to Maternal Protein Deficiency
Authors: Haque Manjurul , Koski Kristine G , Scott Marilyn E 
Published: November 2023

Background

Maternal dietary protein deficiency and 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 alter the expression of genes in the developing fetal brain.

Methods

Outbred pregnant CD1 mice were used in a 2×2 design with two levels of dietary protein (sufficient [24%] and deficient [6%]) and two levels of infection (sham and Heligmosomoides bakeri). Pregnant dams were euthanized on gestation day 18 to harvest the whole fetal brain. Four fetal brain samples from each treatment group (protein sufficient uninfected, protein sufficient infected, protein deficient uninfected and protein deficient infected) were analyzed using RNA Hiseq sequencing. The raw RNA‐seq FASTQ files were aligned to the reference genome to get BAM files and HTSeq was used to count the number of expressed transcripts. Differential expression of genes was determined by edge R package (P < 0.05 and 1.5 fold change) using Network Analyst.

Results

In response to maternal H. bakeri infection, a total of 96 genes (88 up‐regulated and 8 down‐regulated) were differentially expressed in the fetal brain. Differentially expressed genes were involved in metabolic processes, developmental processes and immune system according to PANTHER classification system. Gene ontology analysis in DAVID revealed more than 15 hits for seven GO terms: secreted, signal, extracellular region, disulphide bond, signal peptide, glycoprotein and glycosolation. Enrichment scores > 20 were found for ten GO terms: heterodimer, MHC II, Ca‐binding region 2, Ca‐binding region 1, prophase, meitotic prophase, S‐100 protein, surface antigen, synapsis, and chromosome organization involved in meiosis. Among the important biological functions identified, several up‐regulated genes have known neurological functions including neurodevelopment (GDF15, Ing4), neural differentiation (miRNA let‐7), synaptic plasticity (via NF‐κβ), neuro‐inflammatory and neuro‐degenerative diseases (S100A8 & S100A9) and glucose metabolism (Tnnt1 & Atf3). In response to maternal protein deficiency, brain specific serine protease (Prss22) was the only up‐regulated gene and no gene was down‐regulated in fetal brain. Only two genes (Troponin T1 and Dynlt1a dynein light chain) responded to the interaction of maternal nematode infection and PD, and their expression was reduced. The differential expressions of genes were confirmed by qPCR.

Conclusion

The study shows that exposure to maternal GI nematode infection from day 5 to 18 of pregnancy altered the fetal brain gene expression profile particularly genes related to neural development and energy metabolism. Infection may play an important and under recognized role in intrauterine development and developmental programming of the fetal brain.

Support or Funding Information

Natural Sciences and Engineering Research Council of Canada (NSERC)