Background Prenatal chronic psychological stress may increase the risk of allergic diseases in children, and eczema is the most common allergic disease in children, the pathogenesis of which is not yet fully understood.

Objective To preliminarily clarify the changes in offspring intestinal flora after chronic stress exposure during pregnancy in rats that increases offspring immune imbalance and eczema susceptibility.

Methods Thirty SPF-grade adult female SD rats were selected and randomly divided into a model group and a control group (n=15). Sixteen male rats were randomly divided into a model mating group and a control mating group (n=8). A 28-day chronic unpredictable mild stress (CUMS) model during pregnancy was established. On the 7th day of stress, male and female rats were caged in a ratio of 3:1. Blood samples were collected from female rats in each group via angular vein on the 1st day before stress, and on the 7th, 14th, 21st, and 28th days after stress. The content of plasma corticosterone during pregnancy was determined by enzyme-linked immunosorbent assay (ELISA). For the offspring rats, an eczema model was constructed using 2,4-dinitrochlorobenzene (DNCB). The number of scratching times of the offspring rats within 5 min was recorded. The offspring rats were divided into 4 groups: DNCB-CUMS group (MM), DNCB-control group (MC), solvent control-CUMS group (CM), and blank control group (CC), with 8 rats in each group. The eczema was induced once every 3 days, and the induction period was 12 d. The expression level of immunoglobulin E (IgE) in the serum of offspring rats after the eczema induction experiment were determined by ELISA. The concentrations of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-2 (IL-2), interleukin-4 (IL-4), and interleukin-13 (IL-13) in the serum were quantified by multi-parameter flow cytometry. The composition and abundance of intestinal microbiota in the feces of offspring rats were detected by 16S rRNA high-throughput sequencing technology.

Results The plasma corticosterone concentrations in the model group were higher than those in the control group on the 7th and 21st days of stress (P<0.05). On the 14th and 21st days of stress, the 1% sucrose preference percentages of female rats in the model group were lower than that in the control group. On the 7th, 14th, and 21st days of stress, the horizontal movement scores of female rats in the model group and the vertical movement scores on the 7th and 14th days were lower than those in the control group (P<0.05). After 6, 9, and 12 d of model building, the scratching frequencies in the MC group and MM group were significantly higher than those in the CC group and CM group (P<0.05). Moreover, there were differences in the contents of cytokines including IFN-γ, IL-2, TNF-α, IL-4, IL-13, and IgE among the offspring rat groups (P<0.05). The CM group and MM group led to an increase in the contents of TNF-α, IL-4, IL-13, and IgE cytokines (P<0.05), while the MM group caused a decrease in the contents of IFN-γ and IL-2 (P<0.05). After the eczema induction experiment, the α-diversity analysis showed that the Simpson index and Shannon index in the CM were higher than those in the CC (P<0.05), indicating that CUMS during the pregnancy of female rats could increase the species abundance of their offspring. The abundances of Prevotella and Lactobacillus in the CM group decreased (P<0.05).

Conclusion Intestinal dysbiosis in offspring due to chronic prenatal psychological stress, which may be one of the mechanisms linking maternal stress to immune imbalance and increased susceptibility to eczema in offspring.