Hydroxychloroquine protects against autoimmune premature ovarian insufficiency by modulating the Treg/Th17 cell ratio in BALB/c mice

Abstract Aims The role of hydroxychloroquine (HCQ) in premature ovarian insufficiency (POI) remains unclear. The purpose of this study was to evaluate the effect of HCQ on ovarian function in mice with POI and to clarify its potential mechanisms. Methods POI was induced in mice by injection with zona pellucida 3 peptide (pZP3), and HCQ was administered intragastrically. Stages of the estrous cycle were determined using vaginal cytology. The ovarian structure was observed under a microscope after hematoxylin‐eosin staining. The levels of serum hormones and anti‐ZP antibody (aZPAb) were measured using enzyme‐linked immunosorbent assay (ELISA). The expression levels of CD4, CD45, and ZP2, ZP3 were determined using immunofluorescence and immunohistochemistry, respectively. The T regulatory (Treg)/ T helper 17 (Th17) cell ratio was analyzed using flow cytometry analysis. Western blotting was performed to assess the expression levels of proteins, transcription factors and cytokines. Results Administration of HCQ to mice with POI greatly restored their estrus cycle. In the treatment group compared to the POI group, estradiol (E 2 ) levels were higher, and follicle stimulating hormone (FSH) levels were lower. In addition, following pZP3, HCQ treatment increased ZP2 and ZP3 expression. Additionally, by inhibiting the activation of the TLR7 signaling pathway, HCQ attenuated the infiltration of inflammatory cells and prevented the activated naive CD4 + T cells from developing into Th17 cells. Conclusion Our findings showed that HCQ effectively restored ovarian function by altering the Treg/Th17 cell ratio in mice with POI, indicating that HCQ maybe a promising therapeutic method for patients with POI.