Maternal Bacillus probiotic regulates offspring growth and immunity via spleen IGF-1/mTOR and FOXO1/IL-10 pathways.

Administering Bacilli clausii as probiotics during the maternal period may enhance microbial balance and positively impact offspring growth and immune health. This study evaluated the influence of Bacillus given to pregnant mice on the growth and immune development of their male albino offspring at 28 days old. Twenty-four Swiss albino mice (16 females and 8 males) were mated and assigned to four groups. Sixteen pregnant mice were divided into four groups (n = 4/group). The control group received a standard diet with distilled water, while the other three groups received daily doses of Bacilli (1.25 mL at 1 × 10^9 CFU) at different pregnancy stages: the second group on gestational day (GD) 0, the third on GD 8, and the fourth on GD 16. At 28 days after birth, male offspring were weighed, and blood samples were collected. The EDTA samples were used for hematological profiles, while serum samples were analyzed for growth hormone (GH), insulin-like growth factor-1 (IGF-1), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-10 (IL-10), and immunoglobulins (IgA and IgG). Spleens were weighed and analyzed for mTOR using qPCR, ELISA, and histological analysis and immunohistochemical staining for IGF-1 and FOXO1 markers. The GD0 group showed significant increases in body weight, spleen weight, spleen somatic index (SSI), GH, IGF-1, IL-10, IgA, and IgG levels, as well as mTOR protein and transcript levels, while TNF-α and IFN-γ levels decreased. Macroscopic analysis revealed a well-structured white pulp containing aggregated lymphocytes. Elevated levels of IGF-1 expression were observed, while FOXO1 expression was decreased. These findings indicate that early maternal probiotic supplementation improves lymphocyte activity and facilitates the remodeling of the splenic immune system in offspring and thus represents an innovative approach to immune programming during early life.