CXCL12/CXCR4 Blockade Alleviates LPS-Induced Abortion by Regulating the Balance of Th17/Treg Cells in Mice

Background: C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) and T helper (Th)17/regulatory T (Treg) cells are reportedly involved in the immune response during pregnancy. The aim of this study was to investigate the effect of CXCL12/CXCR4 on Th17/Treg balance in a mouse model of lipopolysaccharide (LPS)-induced abortion. Methods: Abortion was induced by injection of LPS and AMD3100 was used to block CXCL12/CXCR4. The fetus absorption rates and spleen index were calculated, and hematoxylin and eosin staining was carried out. Quantitative reverse transcriptase-polymerase chain reaction was employed to determine the expression levels of chemokine ligand 12 (CXCL12), CXC receptor 4 (CXCR4), interleukin 17 (IL-17), IL-6, IL-21, IL-22, IL-2, IL-10, retinoid-related orphan nuclear receptor-gamma t (ROR gamma t), interferon-gamma (IFN-gamma), forkhead box P3 (Foxp3), and transforming growth factor-beta (TGF-beta). Protein levels of CXCL12 and CXCR4 were determined, using western blot analysis. Flow cytometry was applied to quantify IL-17 and Foxp3 expression levels. Results: AMD3100 significantly reversed the higher levels of CXCL12 and CXCR4, fetus absorption rates, and spleen indices induced by LPS (p < 0.05). Histopathological examination showed that decidual integrity was damaged and the trophoblasts were thinner after LPS treatment, which were blocked by AMD3100. Immunohistochemistry (IHC) analysis revealed that AMD3100 significantly attenuated Th17 infiltration but significantly promoted Foxp3 expression. AMD3100 significantly downregulated the proportion of Th17 cells and significantly upregulated that of Treg cells in the peripheral blood and spleen. Besides, the expression levels of Th17-related cytokines (IL-17, ROR gamma t, IFN-gamma, IL-6, IL-21 and IL-22) were significantly downregulated, while Treg-related cytokines (Foxp3, TGF-beta, IL-2 and IL-10) were significantly upregulated by AMD3100. Conclusions: The inhibition of C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) could alleviate the miscarriage in LPS-induced abortion by regulating the balance of Th17/Treg cells in mice. These findings may provide a promising strategy for the clinical management of recurrent miscarriage.