Mother-Fetus Immune Cross-Talk Coordinates "Extrinsic"/"Intrinsic" Embryo Gene Expression Noise and Growth Stability

Area of Science:

• Developmental biology
• Immunogenetics
• Statistical genetics

Background:

• Developmental instability (DI) reflects an organism's reduced capacity to buffer against developmental perturbations.
• DI is characterized by inter-individual variability (canalization) and intra-individual variability (fluctuating asymmetry).
• Existing methods lack a framework to statistically dissect extrinsic and intrinsic components of developmental noise.

Purpose of the Study:

• To establish a statistical framework for dissecting extrinsic and intrinsic components of developmental noise.
• To investigate the impact of mother-fetus major histocompatibility complex (MHC)-mediated immune cross-talk on gene expression noise and developmental stability.
• To correlate gene noise with embryonic growth and placental growth factor (PLGF) levels.

Main Methods:

• Utilized principal component analysis (PCA) for projecting trait measurements.
• Employed generalized additive models for location, scale, and shape (GAMLSS) to model eigenvalues representing DI components.
• Applied the framework to analyze gene expression noise in embryos with different mother-fetus MHC combinations.

Main Results:

• The statistical framework successfully dissected extrinsic and intrinsic DI components.
• Allogeneic MHC combinations decreased both extrinsic and intrinsic gene noise in embryos.
• Intrinsic gene noise negatively correlated with embryonic mass and PLGF levels, but positively with growth instability.

Conclusions:

• Mother-fetus MHC interactions can reduce intrinsic gene noise, promoting embryonic growth and developmental stability.
• Intrinsic gene noise can be estimated from a subset of genes, offering a potential diagnostic tool.
• The findings highlight the role of immune cross-talk in optimizing offspring development and fitness.