Altered Th17/Treg Ratio in Recurrent Miscarriage after Treatment with Paternal Lymphocytes and Vitamin D3: a Double- Blind Placebo-Controlled Study

Background: Recurrent miscarriage (RM) affects 2-5% of pregnant women. Paternal lymphocyte immunotherapy is a common treatment for RM patients but the outcome has not been consistent. Therefore, combined therapy with other immunosuppressive drugs such as 1a, 25-dihydroxy-vitamin-D3 (vitamin D3) may improve the outcome. Objectives: To investigate the effect of vitamin D3 on the balance of two essential T cells subsets, T helper (Th) 17 and T regulatory (Treg) cells, which contribute to the immune tolerance during pregnancy. Methods: The expression levels of CD4 and forkhead box protein 3 (FOXP3) in Treg cells, and the expression levels of CD4 and IL- 17 in Th17 cells, were evaluated pre- and 3 months post-immunotherapy in RM patients treated with a combination of paternal lymphocytes and vitamin D3 compared with RM patients receiving lymphocyte immunotherapy alone. Results: Vitamin D3 therapy decreased the frequency of Th17 cells in addition to reducing the Th17/Treg ratio in peripheral blood of RM patients compared with the control group (p<0.05). Conclusion: Considering that RM patients have a higher Th17/Treg ratio in peripheral blood, vitamin D3 may be a candidate therapeutic approach in this disease.