Carbon Disulfide Induces Embryo Implantation Disorder by Disturbing the Polarization of Macrophages in Mice Uteri

Carbon disulfide (CS2) induces embryo implantation disorders. Macrophages participate in the process of pregnancy. Therefore, we want to explore the effects of CS2 exposure on polarization and immune function of macrophages in pregnant mice uteri. The exposure times were gestation days 3 (GD3), 4 (GD4), and 5 (GDS), and the observation end points were arranged in a time series after CS2 exposure. The uterine tissues were collected to detect the expression levels of macrophages cytokines (IL-6, IL-12, TGF-beta 1, and Vegf-a) and downstream regulatory cytokines of Thl-type (IL-2 and IFN-gamma) and Th2-type (IL-10 and IL-4) by flow cytometry, ELISA, and q-PCR The results showed that, compared with the controls, the ratios of M1/M2 macrophages in the endometrium significantly increased by 96%, 110%, and 177% at the GD4, GD6, and GD7 observation end points after GD3 exposure and increased about 3.88-fold and 2.37-fold at the GD6 and GD7 observation end points after GD4 exposure, respectively. In contrast, the ratio of M1 and M2 macrophages significantly reduced by 53% at the GD5 observation end point after GD3 exposure. Meanwhile, the expression levels of IL-6 were significantly increased about 2.00-fold for mRNA and 1.60-fold for protein at GD4 observation end points after GD3 exposure, and the mRNA levels of IL-12 increased about 3.61-fold at the GD6 observation end points after GD4 exposure. The mRNA levels of TGF-beta 1 were significantly decreased by 41%, 25%, and 20% at the GD7 observation end points after exposure at GD3, GD4, and GD5, and the expression levels of Vegf-a mRNA and protein were decreased. Furthermore, the ratio of IL-2/IL4, IL-2/IL-10, IFN-gamma/IL-4, and IFN-gamma/IL-10 in the uterine tissue was significantly increased at the exposure groups. These findings suggest that the imbalanced polarization of macrophages is the key regulator in the progress of CS2-induced embryo loss.